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# Survival and Emergency Preparedness

montalk.net » 21 March 19

History has shown that nothing lasts forever. Calm periods have always without exception been punctuated by natural upheavals and man-made disruptions that turn things upside down. Our medical, police, and utility services can only handle things as they are during normal times. When stretched by circumstances, they fall short.

Therefore, we must prep. We can’t help others from a position of weakness, so we must be strong and well-equipped. Prepping reduces suffering and prolongs our ability to do good in this world.

Preparedness spans the scale from quick and easy to hardcore and all-consuming. You take a gamble in what level to go with. Too little and you might painfully regret it one day. Too much and you will have spent time, money, and sacrificed spiritual harmony out of proportion to the risk. But something is better than nothing, which is why I advocate that everyone at least have the basics.

Everyone must be ready to survive bare minimum one week without power, internet, cell service, food, water, gasoline, medical, fire, or police service. One month is a more reasonable goal and would cover the most probable natural disasters. One year would take some serious investment. One decade would require a luxe bunker or well-defended homestead. The sweet spot is around 2-3 months. It all depends on the dangers unique to your region, so plan accordingly.

Thankfully, it doesn’t take much time or effort to get the bare basics, and no skill or training is required for that level of preparedness. The simplest and cheapest anyone can do for short term disruptions (wildfire, hurricane, storms, power outage):

• several cases of bottled water
• canned and ready-to-eat foods with decent shelf life
• cash in small bills, enough for food, gas, and motel covering 2-3 days of travel
• extra toiletries and hygiene supplies, meds, and everyday household items
• N95 or better dust mask and eye protection

That’s good enough for up to a week and light enough to quickly load into your vehicle if necessary. You can get all these things in one day, put it away in your closet, and go on with your life.

For longer situations (weeks to months) these and more would be necessary, not only in terms of supplies but also skill and fitness.

Regarding supplies, basic needs in order of urgency: water, food, medical, shelter, energy/lighting, defense, and tools. Some suggestions with links to Amazon:

#### Water

Portable water filter like the Sawyer Squeeze Water Filtration System, cases of bottled water in clear containers, water purification tablets, collapsible water bags, 100 gallon water bag for bathtub or line your bathtub with a plastic drop cloth and fill if you know a disaster is about to happen.

If there is only one item to get, it is a high quality portable water filter (followed by a respirator mask, see below). While bottled water gets you through the initial phase, you simply can’t store or carry enough water to last you longer than that. Serious water storage, if one has the space, would involve 55 gallon drums or IBC totes.

Therefore, a water filter is essential regardless. I cannot stress this enough because water is the first and most essential thing to go after any disaster, and portable filters are so compact yet good for hundreds to thousands of gallons. That Sawyer water filter uses new technology that makes it 5x more affordable than previous filters, and you can even let gravity do the work by using two collapsible water bags (top for dirty water, bottom for clean) with an adapter. To collect rain water, you can use an angled tarp suspended by paracord to channel water into a large container, or get a rain barrel connected to a gutter spout.

#### Food

Considering what people spend on car insurance, life insurance, health insurance, etc. it would be foolish to not have some emergency food stored.

Foods vary in shelf life. Short-life foods like energy bars, dried fruits and nuts, crackers and cereal require no preparation to eat and are quick and convenient, but only last 1-2 years. Medium shelf-life foods like canned and jarred products are better but heavy and still require rotating through them every 2-4 years. Long term foods like rice, pasta, beans, and freeze-dried or canned dry foods are either bland or expensive but can last 10-30 years. Ideally, you would have a mix of all three. Here are some options:

Mountain House freeze dried meal pouches or cans for long term food storage. The most costly option, but best in terms of shelf life (up to 30 years), weight, and taste. Compared to throwing out canned foods every few years that you didn’t manage to rotate through, it may save money in the long term. In terms of preparedness, it’s a better investment than gold and silver.

Alternatively or additionally, buy cases of canned dry foods from the Mormons. The most cost-effective long-term option. Mormons are required by their religion to be preppers and offer good value for these.

Rice is overall the cheapest bulk calorie source and can augment other stored foods. Grab 10lb, 20lb, or 50lb bags at the grocery store and seal them airtight. Dry beans, peas, pasta, and lentils are other bulk staple foods to consider adding. Asian grocery stores sell large bags of rice way cheaper than other places especially organic / health food stores. Just note that rice may contain weevil eggs that hatch in storage unless the rice is first frozen for 24 hours; put in zip lock bags and freeze for a day then let return to room temperature, make sure it’s dry, and store in sealed buckets or storage containers. Only instant and parboiled/converted rice doesn’t have this problem (since it’s pre-cooked before being dehydrated).

Bulk protein: cheapest/easiest is 5lb containers of whey protein. 2 year shelf life, so rotate through it as needed. Without enough protein your strength, immune system, and emotional well-being take a hit. Mountain House freeze-dried chicken and beef in #10 cans are also good if you can afford it. Powdered eggs likewise. Otherwise: canned meats like chicken, tuna, salmon, sardines, or peanut butter.

Rice and peanut butter are two bulk foods that can be supplemented by canned and jarred foods. Peanut butter from bulk discount outlet stores is one of the most affordable sources of calories, fat, and protein. Not the healthiest form of fat, and shelf life is about 3-5 years max, but for those on a budget prepping for emergencies coming within 3-5 years, it will keep you alive and has more to offer nutritionally than rice. You can also be in keto and survive off peanut butter for a while. (Vitamin C powder or a multivitamin would still be needed).

For short term (use within 1-2 years) : granola bars, protein bars, instant rice, instant mashed potatoes, oatmeal, Flora brand Italian toasts, saltine crackers, canned beans, canned or jarred fruits and vegetables, canned/pouched meat, powdered eggs, powdered milk, salt and honey, pasta and jarred pasta sauces, olive oil, canned butter, vitamins (especially Vitamin B and C, keep them fresh in the freezer if desired).

Military meal packs (MREs) are fine but only have a 2-3 year shelf life and are not always sold fresh. They’re more of a novel convenience.

Fats are really important. Fat deficiency leads to autoimmune and nervous system disorders. Freeze dried and dry canned goods tend to lack fat. But storing fats and oils is challenging due to spoilage, which is accelerated by light, heat, and oxygen. Unopened olive oil lasts 2 years at room temperature, maybe 5 years refrigerated. Coconut oil is good for 5 years and has antiviral properties, but lacks certain important fatty acids (linoleic and oleic). Canned butter lasts 10 years. A mix of these is recommended.

For cooking, most convenient for short term use: Esbit folding stove and fuel or Coleman propane stove. To use wood as fuel, which is great for long term if you’re on foot, a biofuel stove works but takes longer to light and smoke disallows indoor use.

For month+ emergency preparations, I generally recommend an alcohol stove and quart-sized canisters of denatured alcohol (found in the paint thinner section of hardware stores, and is also known as marine stove fuel) because you can stockpile gallons of fuel for months of smoke-free cooking; an ounce of alcohol boils 2 cups of water. The alcohol stove is an easy and cost-effective setup for home or in between travel-by-car. Propane canisters and stoves are fine too if you have the room for them.

Gardening, aquaponics, and homesteading offer a renewable food supply but take quite a bit of land, time, money, effort, and skills to get right. Disease, predators, or unfavorable weather can wipe out a harvest in short time. Preserving harvested food is another challenge. Security complicates things too, especially during the most dangerous phase of a grid-down situation when it’s wiser to stay inside. That’s why stored food and water are necessary regardless.

#### Medical

Extra prescription items stored in a cool place, toiletries and personal hygiene essentials, and First Aid kit ( M2 Basics, Comprehensive Kit, or similar).

Or make your own kit: anti-bacterial ointment (most important), anti-fungal ointment, cortisone cream, anti-diarrheal, laxative, SAM splints for sprains and breaks, assorted band-aids, buffered aspirin, vaseline, rubbing alcohol, iodine liquid, medical tape, gauze rolls, elastic bandage wrap, wound dressing pads, butterfly sutures, superglue for cuts, burn gel or burn pad, moleskin for blisters, bandage scissors, tweezers, latex-free gloves, plastic syringe for wound washing, Bic lighter, sturdy drinking straws, Gold Bond medicated powder, scissors, digital thermometer. Additional anti-microbials: oregano oil and colloidal silver.

For dealing with deep gashes, stabbing wounds, or gunshot wounds, you would need a trauma kit. SOFTT Wide tourniquet, OLAES compression bandage, trauma scissors, nasophyringial airways, chest decompression needle, HALO chest seals. Some of these require medical training to use and are mostly meant to stabilize someone long enough to get to a hospital. Without a hospital, these will prolong life but not guarantee survival.

First aid and trauma kits cover two extremes. One is for minor issues, the other for catastrophic issues. If you want to be properly prepared, you’d also need to cover the realm between these two extremes, the realm of general medicine that’s familiar to doctors and nurses but not so much those outside the medical field. They understand the necessity and use of prescription-strength painkillers, antibiotics, IV fluids, and other specialized drugs and equipment. To get a basic grounding on that, including a list of what drugs to get (which can be bought online without a prescription if you look around), please read The Prepper’s Medical Handbook as it gives a more realistic picture of what’s required for general coverage than simple First Aid.

#### Energy / Lighting

Storms can knock out power for 2-3 days. Severe storms, 1-2 weeks especially in rural areas. Major hurricanes and tornadoes with widespread devastation, 1-3 months. The problem now is that due to the pandemic, supply chain shortages of transformers, breakers, and cables are hitting power companies hard. They can’t fix things as quickly as before, if at all. Other threats include cyber attack, oil crisis, credit crunch, or war with China that blocks shipping lanes from Asia. The future of centralized electric power is on thin ice. Brown-outs, black outs, and rolling black-outs will be more common.

For emergencies up to a week long, simply get a USB portable battery bank. The battery bank is charged via USB (hence solar panel, 12V car charger, computer, or home wall adapter) and can then provide power anywhere and anytime to recharge phones, tablets, radios, headlamps, batteries, etc. anything that can be charged via USB. The higher the capacity, the better. There are also much heavier duty portable battery banks like this portable power station and 100W solar panel, for running small AC powered devices like laptops, radios, lamps, etc.

USB devices can be charged by solar power. If you have two battery banks, you can charge one while using the other. The results of solar USB chargers may be disappointing, however, if you trust the advertised power rating (in watts) of the panel. Manufacturers test them at the most intense direct sunlight, if not lying outright. So the rule of thumb is to go overkill with the advertised watts. An iPad charges at 5V 2A which is 10 watts, but a solar panel rated at 10 watts will not be enough; 30-50 watts is more in line with what people imagine solar power should be for that application.

In terms of solar technology, there are different kinds of panels:

• Polycrystaline: Old tech, heavy, inefficient, but cheap. Terrible in cloudy conditions, needs direct full sunlight. Appearance: large flakes of varying shades of blue amid a grid of thin parallel lines. Sunlight to electricity conversion efficiency: 15%. Best for rooftop solar power on a budget.
• Monocrystaline: Similar to polycrystaline but efficiency is better at 20%. Still needs direct sunlight to function, and therefore not good for cloudy days. Appearance: uniformly dark blue-brown color, horizontal lines, in squares with rounded corners. What you’ll find in most consumer portable solar chargers.
• Amorphous/thin-film: Best option but most expensive and larger surface area. Lightweight, very thin and flexible, and absorbs more of the light spectrum for more power including cloudy conditions and partial shade. What the military uses. The best thin-film manufacturer is PowerFilm. Appearance: grid of small u-shaped dark rectangles.

Your best choice is a monocrystaline or amorphous/thin-film panel at 2×-3x the watts you think you need. Make sure to get something durable and reliable, as the cheaper ones tend to stop working after a couple months. To charge USB devices, on a budget look into portable mono panels like the Topsolar 60w. Otherwise, PowerFilm 30 Watt plus an Anker 12V-to-USB charger. That one can charge car batteries too, albeit slowly.

For lighting, headlamps keep your hands free and are superior to flashlights. Premium LED headlamp with 18650 batteries. And/or low cost LED headlamp and packs of alkaline or lithium AA/AAA batteries (lithium batteries don’t leak and keep longer in storage).

Whole-house solar panel systems, batteries and charge controllers are quite an investment and require professional consultation and installation.

Alternatively, you can get a generator that runs on gasoline, diesel, or propane. These are good for short term high power applications like running kitchen appliances or whole homes for a short wihle. But they are noisy, emit exhaust, and run out of fuel within days or weeks. Stored gasoline must have stabilizers added to last longer than six months (or a little longer if premium gasoline, which has lower water-absorbing ethanol in it). Diesel lasts longer and can be stored in 55 gallon drums. Propane fed from the gas line infrastructure will lose its pressure when the remote pump fails in a power outage, so must instead be stored in a large propane tank on site.

#### Other

Besides a water filter, a respirator is the next most important hardware item. Unlike a simple N95 mask, these are silicone and make a complete seal around mouth and nose. There are many situations when you would need one: smoke from wildfire and structure fires, chemical spills, mold after a flood, volcanic eruptions, viral and bacterial outbreaks, nuclear fallout, chemical and biological weapons, tear gas, dust storms, and rotting bodies/garbage.

3M Respirator mask with 6001 Filter for smoke, dust, biological and chemical fumes or the 7093 Filter for smoke, dust, and biological particles (easier to breathe through, but doesn’t protect against chemicals or vapors).

For more protection, especially against viruses and bacteria, you must also wear safety goggles or swim goggles that form a seal. Or a full face mask, whether a 3M full mask or a military surplus gas mask that takes 40mm threaded filters, like the Scott M95 or similar.

Swiss Army Knife or Leatherman Multi-Tool. Convenient to always have with you.

Glock Field Knife. Strongest cheapest multi-use knife for sawing, prying, shaving, splitting wood, use as a spear head, and defense.

Pocket chain saw or folding saw. To remove downed branches, cut logs for fires. If you’re going to be chainsawing quite often, an electric chainsaw and solar power system is a good option.

Mechanix gloves. Safety from cuts and scrapes, and good for tactical use too.

Lock pick set, fence wire cutters, and pry bar. For getting into / out / through things. Picking locks isn’t as easy as in the movies, but you’ll get further with a quality set.

Bic Lighters. Easier to use than ferro rods. Good barter item too.

Repair gear like duck tape, hot glue sticks, epoxy putty, JB weld, plastic tarps or contractor trash bags, paracord/accessory cord, hand sewing needles and bonded nylon thread, sewing awl, zip ties small and large, ranger bands (bicycle inner tubes cut to rubber band size), tire repair kit, solder and electrical tape and hookup wire, hammer and nails long enough to board up a window.

Common sense items like clothing, backpacks, sunglasses, hats, socks, shoes etc.

#### Communications

A cheap AM/FM radio will help you stay informed when there’s no internet or cell service. If the government drops off supplies just two blocks away, without a radio you might never know it (that happened after Hurricane Andrew and people suffered just a block or two away from pallets of food and water).

Even better is an AM/FM/Shortwave radio with Single Sideband. With a shortwave radio you can listen to shortwave news stations from very far away. And with single-sideband (SSB) ability, you can hear HAM radio operators from hundreds and sometime thousands of miles away in the 20m, 40m and 80m bands. SSB drives up the price of the radio but it’s important to have if you can afford it, as HAM operators can report local conditions around the country, which you might not hear about any other way. Here’s a larger better radio with shortwave and SSB.

If cell phone networks go down, local communications can be done with simple GMRS Walkie Talkies (couple miles range, down to half a mile if buildings or hills are in the way). CB radios are also good for local comms but require 12V batteries and large antennas and are therefore better suited to home and vehicle use.

Another option for local comms are the low-cost UHF and VHF (ultra and very high frequency) HAM radios like the Baofengs. They are like walkie talkies but can send/receive on additional frequencies including the 2m and 70cm HAM bands, and receive FM radio as well. Baofengs require a HAM license to transmit on legally. If you stay on the FRS/GMRS, and MURS frequencies and use low power no one will know or care. These are meant for short range communication, or else for interacting with a local repeater tower that forwards your signal to another one far away but such towers can’t be relied on when the grid is down.

If you want encrypted radios for a local comms network, get a couple DMR radios. Just be warned that these take some effort to program correctly, their range isn’t as good (get a better antenna), and know that encryption is illegal. But the option exists if you need it. Without encryption, everyone in the area can eavesdrop on your conversation.

For long range regional or international communications (hundreds or thousands of miles), you would need an HF (high frequency) HAM transceiver with a suitable antenna for the given frequency band. That means Yaesu, ICOM, and Kenwood units capable of receiving and transmitting on the 20m, 40m, and 80m (a.k.a. 75m) bands. Example is the Yaesu FT-891. There’s a lot to that, especially with choosing and setting up the right antenna, the protocols to follow when speaking to other HAM operators, and again you need a license to transmit legally. But HAM radio is the only option for true grid-down long range communication.

#### Shelter / Hiking

Bugging out on foot into the woods is a bit of a fantasy. You’re more likely to be sleeping in cars, buildings, or your own home than in the wilderness. Wilderness is a last resort. Preparing for on-foot or woods survival requires a different approach focusing on minimalism and lightweight. Realistically, someone bugging out into their own property will cache goods there ahead of time. Otherwise you can only take what you can carry, and that severely limits how prepared you can be. Further, cold weather and questionable availability of food, not to mention running into hostile people, further reduce chances of survival in the wild.

Regardless, even if you don’t plan on bugging out on foot, it can’t hurt to have a sleeping bag appropriate to your climate since even at home or in cars, heat will not be available during utility or gas outages unless you have a well-maintained fireplace and plenty of firewood. Note that when sleeping bags say 15F they’re exaggerating and it’s really only good down to 35F. That’s truer for budget sleeping bags. Even so, two bags can be nested for colder conditions.

For warmer weather, a jungle blanket or jungle bag may be sufficient. For intermediate or colder weather, the Carinthia Defence 1 or Defence 4 are excellent. These are also good for winter power outages when it gets into the 30s inside the home. Of course you can use heavy blankets, but sleeping bags are easier to transport and use outside the home should the need arise.

Another essential item for everyone is an inflatable sleeping pad, which will conserve body heat and let you sleep comfortably in more places including the floors of buildings, hard soil and gravel, and cots that lack padding. They have different R ratings (thermal insulation) which matters if you’re using them in cold environments since the ground will suck body heat away if you don’t use a pad or if you use one with a low R rating. So in colder weather you’ll need an insulated pad with an R rating above 4.

If on a tight budget, look into buying military surplus goods like sleeping bags on eBay as you can get products equivalent to high dollar commercial items at 1/3rd the cost. Get back some of your tax dollars that way.

For outdoor shelter, a lightweight tent or tarp and a military thermal casualty blanket as a ground sheet suffices. And carrying all this requires a good backpack, like a hiking backpack in the 45-100 liter range. Remember to keep the total weight under 30% of your healthy bodyweight or you won’t be walking far.

Research hiking, mountaineering, bushcraft, and orienteering to get accustomed with the types of variables involved in traversing the land. If your main aim is to travel while avoiding people and ambushes, and you have the cash, then investing in a portable infrared thermal scope can be of value since in open air (i.e. not through glass) it lets you detect body heat signatures from hundreds of yards away even at night.

It helps to know the area: where you are, where you’re going, how to get there, and where strategic points are located like bridges, stores and hospitals, back roads, supply caches, nuclear plants and other danger areas.

In order of priority: map, compass, GPS.

GPS is convenient and precise but will be the first to fail. Dead batteries, extreme solar activity, attack on GPS satellites, or nuclear EMP (electromagnetic pulse) will make GPS useless. Then you’ll have to rely on map and compass. But while it’s still working, GPS is amazing.

Install the free maps.me smartphone app to have a road map that displays your location. In the app, download the databases for your state and surrounding states, for offline use. Then, even if internet and GPS go down, you still have a digital road map in your pocket. An old smartphone (even without a SIM card) can be repurposed for this. The free Commander Compass app is useful if you need a digital compass. There are also topographic map apps for the phone, or PDFs you can put on there, but in the wilderness you really should have paper maps.

For standalone GPS devices, the Foretrex 601 is as simple as it gets, to the point of being primitive, but it runs on two AAA batteries and can be strapped to your wrist. It doesn’t store detailed maps, so those are still needed on the side, but you can get GPS coordinates, mark locations, record your tracks, retrace your tracks, plan routes with waypoints, and follow those routes with distance, heading, and estimated time of arrival displayed on the screen. There are other handheld GPS devices that display color maps, but you might as well use a smartphone at that point, though unlike phones these GPS devices can’t be tracked so they’re more secure if you’re hiding from authorities.

For paper maps, start with a road atlas to keep in your vehicle, like the Rand McNally 2022 Atlas. Consider also getting a more detailed atlas just for your state, which shows topography, camping sites, and the more obscure back roads. Just driving, you don’t really need a compass but a simple one like the Brunton TruArc 3 can orient you when lost.

Many think a compass is just for finding north. But with a proper map and compass you can do so much more: measure distances, triangulate your position, read and plot GPS coordinates on the map, get the precise bearing between two points, design routes to your destinations, and navigate these routes by going from waypoint to waypoint by heading in a specific bearing for a specified distance.

To learn land navigation like this, first print or buy a detailed map of your area, one designed to work with a good compass. This is especially needed for navigating in the wilderness in the absence of buildings and streets.

One option is Caltopo, where you can make your own custom maps. The help docs will familiarize you with the workflow. You can blend different maps together.

#### Resources

Books like the SAS Survival Handbook that focus on bushcraft and short term survival in the woods are useful but not adequate for emergency preparedness since we’re more likely to be in our homes, offices, or vehicles than lost in the forest or stranded on a desert island. For the more immediate and likely disruptions, you’re better off with the natural disaster preparation advice from sites like ready.gov.

Economic collapse without complete societal collapse is the more realistic scenario that warrants serious foresight and preparation, for which you can cautiously read FerFal’s book The Modern Survival Manual: Surviving the Economic Collapse.

And if you’re concerned about the more tactical aspects of survival in the face of widespread violence and desperation, then study Max Velocity’s book Contact! A Tactical Manual for Post Collapse Survival. The book covers subjects far beyond the scope of bushcraft or disaster preparation books, but things would have to get pretty dire to ever reach that point. If nothing else, the purpose of reading this book is to demystify Hollywood-programmed expectations of how force and violence is conducted in the real world.

Studying and applying this stuff can take its mental and spiritual toll, so be careful and weigh the risk of that versus the risk of not being prepared.

#### Guidelines

Here are some things to keep in mind:

1) You can only prepare for a limited set of scenarios. A point comes in your attempt to prepare for everything, where you’ve just thrown away your life, your destiny, your mission if you have one, all for the sake of surviving. Then you would be surviving for the sake of existing, not for the sake of living. Life would be meaningless and you just defeated your very purpose for coming here. Therefore, no amount of preparation warrants throwing your life away and heading into the hills, shutting yourself off from the world until doomsday comes. All preparations should be done in parallel with your regular life and not infringe upon it. If your main life is Plan A (nothing happens) then keep that open while you simultaneously have Plan B (S.H.T.F. = shit hits the fan, meaning a condition of survival amidst social chaos and civil breakdown).

2) Do not become obsessed, preoccupied, or emotionally lost in this. If you get some survival item, know how to use it and put it away until time for maintenance, training, and use. Don’t dress up in ninja gear like you have some kind of survivalism fetish, don’t be turning over heroic post-apocalyptic fantasies in your mind hours upon hours a day, and don’t keep gloating over your advantage over the other poor suckers who are asleep and unprepared. Reason being that holding onto an extreme survivalism mentality, beyond what’s needed to actually do it and be proficient at it, is highly detrimental to your spiritual balance. Have the knowledge and supplies, but be very cautious of aligning your heart and thought-train completely and exclusively with the mere idea of physical survivalism. Making it your life goal will kill your soul, and you need your soul and a spiritual connection to gain the synchronistic and intuitive protection needed to keep you safe in all scenarios, not just the ones you can physically prepare for.

3) To an extent, spiritual balance, good intuition (honed through past trial and error), and sharp awareness (observe and think several steps ahead) will get you farther than any physical survival dwelling or supplies. Why? Because then you can respond flexibly to whatever comes, as it comes. By spiritual balance I mean keeping a leash on your ego, your jealousies, contempt and hatred, desperate materialism, greed, and other base impulses… and instead, striving for equanimity, gratitude to the Creator, devotion to truth and beauty and fairness, and consideration for others. Then you acquire divine blessing that increases the luck factor in your life. In the midst of calamity you can get an intuitive or synchronistic helping hand.

Of course, spiritual versus physical preparation are not mutually exclusive; just avoid physical obsession that infringes on spiritual balance; that’s the most important thing I can say. Same goes for looking toward the future and getting apprehensive. Don’t lose hope or optimism, as you need these to carve out a pathway to heaven through times of hell.


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# Quantum Animals

A penguin exhibiting quantum behaviour

It is known that animals cannot be explained using classical physics, since they tunnel through walls. The chickens thus exhibit quantum behavior and should be described with quantum mechanics.

Time-independent Schrödinger equation

${\displaystyle {\hat {H}}\vert \Psi \rangle =E\vert \Psi \rangle }$

The Schrödinger Equation gives us the behavior of wave function of the animal, which describes probabilistically how the animal will behave. According to the Born interpretation, ${\displaystyle \langle \Psi (x,t)|\Psi (x,t)\rangle }$ describes the probability that the chicken will be at ${\displaystyle x}$, but the exact outcome of the experiment cannot be known.

## Estimation of mass of chicken

We know that chickens tunnel through 1m thick walls, so their De Broglie Wavelength should be on the order of 1m, and their speed is on the order of ${\displaystyle 0.1{\frac {\text{m}}{\text{s}}}}$. We know that

${\displaystyle \lambda ={\frac {h}{p}}={\frac {h}{mv}}\iff m={\frac {h}{v\lambda }}}$

Plugging our values in and with ${\displaystyle h=6.626\ 070\ 15\times 10^{-34}\ {\text{J}}{\cdot }{\text{s}}}$, we get

${\displaystyle m={\frac {h}{0.1{\frac {{\text{m}}^{2}}{\text{s}}}}}=6.626\ 070\ 15\times 10^{-33}\ {\text{kg}}}$

This shows us that the chickens are very very light.

## Behaviour of chicken in pen

This problem requires that we know the Hamiltonian operator ${\displaystyle {\hat {H}}=V(r)-{\frac {\hbar }{2m}}\nabla ^{2}}$ of our chicken pen, where ${\displaystyle V(r)}$ is the potential of the pen, so we can solve the Schrödinger equation for this problem. We can assume that the potential is piecewise constant, zero inside the pen and ${\displaystyle V_{0}>0}$ outside (finite potential well model), so ${\displaystyle V(r)={\begin{cases}0&|r|\leq L\\V_{0}&|r|>L\end{cases}}.}$

### Inside the pen

Inside the pen, we have ${\displaystyle V(r)=0}$. Plugging this into the Schrödinger equation gives us

${\displaystyle -{\frac {\hbar }{2m}}\nabla ^{2}\Psi =E\Psi }$

Define ${\displaystyle k:={\frac {\sqrt {2mE}}{\hbar }}}$. Since our problem is one-dimensional, we can solve this second-order differential equation with a function

${\displaystyle \Psi (x)=A\sin(kx)+B\cos(kx)}$

for some constants ${\displaystyle A,B\in \mathbb {C} }$

### Outside the pen

Outside the pen, we have ${\displaystyle V(r)>0}$. The calculation of the Hamiltonian and the solving of the Schrödinger equation is left as an exercise to the reader.

This is an excerpt of the upcoming book "Quantum Mechanics of Animals"

Book Cover

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# Fatal Error with Google API

Hi Experts,

This is a  weird issue. I have been developing a small PHP App on my Dev Server (IIS7) with Google Calendar API, then launched it on my live Server (IIS8). At that time, the connection to the API worked from both servers, which was a month back.

While the connection from my Live Server continues to work, on my Dev Server I get
PHP Fatal error:  Uncaught GuzzleHttp\Ring\Exception\RingException: Error creating resource: [message] fopen(): SSL operation failed with code 1. OpenSSL Error messages:
error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed
[line] 406
[message] fopen(): Failed to enable crypto
[line] 406
[message] fopen(https://www.googleapis.com/oauth2/v4/token): failed to open stream: operation failed
[line] 406

You can see a working version on my Live Server here:

A success result is a JSON object.

The error suggest a  SSL issue, but as you can see by the URL, https is not used.

Actually for my Live Server I  have support, and they were supposed to replace cacert.pem under Plesk. On my Dev, i don't have Plesk, and did not need to replace cacert.pem, or don't know how

Thank you
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Software DeveloperAuthor Commented:
Developer & EE ModeratorCommented:
I develop on PHP for windows myself. When something like this happens, I have to specify where my local PEM file is.

https://curl.haxx.se/docs/sslcerts.html
https://curl.haxx.se/docs/caextract.html

I just pull the cert.pem from that second link and place it in my webroot. Then somewhere in your code for your cURL or other api call you will need to specify where it is. Something like below.

 'cert' => '/path/to/cert.pem'

In my case, I also add the intermediate cert for my provider.
Software DeveloperAuthor Commented:
I have been to those links before, but the problem is I dont know to do with the cacert.pem when I download it. How do I add it to my web server and/or browser?
Developer & EE ModeratorCommented:
Put it somewhere on your server that you have given access to the internet user.  If you put it outside of the www folder, make sure the intenet user has access. You can put it inside the www and then access it that way.

For Authorize.net as example you can see on line 18 of this code. This is the httpclient.php file.  You probably have something similar. I think I always had problems and downloaded the pem file from hax, then added the intermediate cert from my provider to the pem file.
 public function _sendRequest($xmlRequest) {$xmlResponse = "";

$post_url =$this->_getPostUrl();
$curl_request = curl_init($post_url);
curl_setopt($curl_request, CURLOPT_POSTFIELDS,$xmlRequest);
curl_setopt($curl_request, CURLOPT_HEADER, 0); curl_setopt($curl_request, CURLOPT_TIMEOUT, 45);
curl_setopt($curl_request, CURLOPT_RETURNTRANSFER, 1); curl_setopt($curl_request, CURLOPT_SSL_VERIFYHOST, 2);

$this->logger->info(sprintf(" Url: %s",$post_url));
// Do not log requests that could contain CC info.
$this->logger->info(sprintf("Request to AnetApi: \n%s",$xmlRequest));

if ($this->VERIFY_PEER) { curl_setopt($curl_request, CURLOPT_CAINFO, dirname(dirname(__FILE__)) . '/../../ssl/cert.pem');
} else {
$this->logger->error("Invalid SSL option for the request"); return false; } if (preg_match('/xml/',$post_url)) {
curl_setopt($curl_request, CURLOPT_HTTPHEADER, Array("Content-Type: text/xml")); // file_put_contents($this->_log_file, "\nSending 'XML' Request type", FILE_APPEND);
$this->logger->info("Sending 'XML' Request type"); } try {$this->logger->info("Sending http request via Curl");
$xmlResponse = curl_exec($curl_request);
$this->logger->info("Response from AnetApi:$xmlResponse");

} catch (\Exception $ex) {$errorMessage = sprintf("\n%s:Error making http request via curl: Code:'%s', Message:'%s', Trace:'%s', File:'%s':'%s'",
$this->now(),$ex->getCode(), $ex->getMessage(),$ex->getTraceAsString(), $ex->getFile(),$ex->getLine() );
$this->logger->error($errorMessage);
}
if ($this->logger &&$this->logger->getLogFile()) {
if ($curl_error = curl_error($curl_request)) {
$this->logger->error("CURL ERROR:$curl_error");
}

}
curl_close($curl_request); return$xmlResponse;
}

Software DeveloperAuthor Commented:
Developer & EE ModeratorCommented:
Does your php.ini have something that looks like:

curl.cainfo=c:\path\to\cacert.pem

Perhaps you can update your ini file or in your app's config file. I suspect once you update that it will work. Since it is on your dev server, you can probably updated it directly on the php.ini file though.

Experts Exchange Solution brought to you by


text:
# Modules whose direct summands are FI-extending

Document Type: Research Paper

Authors

1 Department of Mathematics, Balkan Campus, Trakya University, 22030 Edirne, Turkey.

2 Department of Mathematics, Yunus Emre Campus, Education Faculty, Anadolu University, 26470 Eskisehir, Turkey.

Abstract

A module $M$ is called FI-extending if every fully invariant submodule of $M$ is essential in a direct summand of $M$. It is not known whether a direct summand of an FI-extending module is also FI-extending. In this study, it is given some answers to the question that under what conditions a direct summand of an FI-extending module is an FI-extending module?

Keywords

Main Subjects

### References

G.F. Birkenmeier, B.J. Muller and S.T. Rizvi, Modules in which every fully invariant submodule is essential in a direct summand, Comm. Algebra 30 (2002), no. 3, 1395--1415.

G.F. Birkenmeier, J.K. Park and S.T. Rizvi, Modules with fully invariant submodules essential in fully invariant summands, Comm. Algebra 30 (2002), no. 4, 1833-1852.

N.V. Dung, D.V. Huynh, P.F. Smith and R. Wisbauer, Extending Modules, Pitman Research Notes in Math. Ser. 313, Longman, Harlow, 1994.

F. Karabacak and A. Tercan, On modules and matrix rings with SIP-extending, Taiwanese J. Math. 11 (2007), no. 4, 1037--1044.

P.F. Smith and A. Tercan, Direct summands of modules which satisfy (C11), Algebra Colloq. 11 (2004), no. 2, 231--237.

B. Stenstrom, Rings of Quotients, Springer-Verlag, New York, 1975.

X. Wang and J. Chen, On FI-extending rings and modules, Northeast. Math. J. 24 (2008), no. 1, 77--84.

### History

• Receive Date: 20 July 2016
• Revise Date: 16 January 2017
• Accept Date: 20 January 2017


text:
## Zero-energy bound state decay for non-local Schrodinger operators

2019-06-06T08:40:41Z (GMT) by
We consider solutions of the eigenvalue equation at zero energy for a class of non-local Schrodinger operators with potentials decreasing to zero at infinity. Using a path integral approach, we obtain detailed results on the spatial decay of both \$L^2\$ and resonance solutions at infinity. We highlight the interplay of the kinetic term and the potential in these decay behaviours, and identify the decay mechanisms resulting from specific balances of global lifetimes with or without the potential.


text:
2. Operations Management
3. question 11 adverse impact refers to the rejection for employment...

# Question: question 11 adverse impact refers to the rejection for employment...

###### Question details

QUESTION 11

1. Adverse impact refers to the rejection for employment, placement, or promotion of a significantly higher percentage of a protected class when compared to a nonprotected class.

True

False


text:
Getting series outcome probabilities based on individual game probabilities

I have the probabilities for Team X beating Team Y in a game. Each team has two separate probabilities - the probability of winning at home and the probability of winning away.

These probabilities can then be used to calculate the expected winner of a best-of-7 series between the two team. Based on whether or not a team finished higher in the standings, they'll either play a maximum of 4 games at home, or a maximum 3. The format for these games is 2-2-1-1-1, with the higher seed playing twice at home, twice on the road, once at home (if necessary), once on the road (if necessary), and once at home (if necessary).

How could I find the probability that team one wins the series (wins 4 games) in X number (ranging from 4 to 7) of games? My initial thought was to multiply binomial probabilites, like so in R:

 games.out <- function(ph, pa) {
df <- data.frame(w = NA, x = NA, y = NA, z = NA)
for(games.played in 4:7){
home.games <- ceiling(games.played/2)
away.games <- floor(games.played/2)
home.wins <- 4 - away.games
away.wins <- away.games
loops <- games.played - 4
win.prob <- (dbinom(home.wins, home.games, ph)*dbinom(away.wins, away.games, pa))
home.wins <- home.wins + 1
away.wins <- away.wins - 1
for(i in 1:loops) {
temp.prob <- (dbinom(home.wins, home.games, ph)*dbinom(away.wins, away.games, pa))
home.wins <- home.wins + 1
away.wins <- away.wins -1
win.prob <- temp.prob + win.prob
}
df[1,games.played-3] <- win.prob
colnames(df)[games.played-3] <- paste0("Win", games.played)
}
return(df)
}

But, when summed, this code gave values that were much too large to make sense.

> games.out(.5, .5)
HW4     HW5      HW6       HW7
1 0.0625 0.15625 0.234375 0.2734375
> sum(games.out(.5, .5))
[1] 0.7265625

A similar question was asked here (How to calculate probability of winning best of 7 series), but that problem simply deals with one probability associated with all seven games - here, I'm looking at two different probabilities associated with potentially different numbers of games.

Any help is definitely appreciated - I've been banging my head against the wall for a couple of hours on this.

• They are too large because you expect the answer to be 0.5, in your example. The reason why they are too large is as follows. What you have calculated for HWN, where N is the number of games before the home team wins the series, is the value 0.5^N * choose(N, 4). This overestimates the probability. Instead, you should calculate 0.5^N * (choose(N, 4) - choose(N-1, 4)). This is because the number of games where the home team wins 4 games in N games includes the winning pathways where the home team wins 4 games in N-1 games. E.g. if N = 5 then the sequence WWWWL is counted...
– Alex
Apr 10, 2018 at 1:54
• ... when you use choose(5,4). You need to exclude these games that terminate early.
– Alex
Apr 10, 2018 at 1:56
• I was working towards something like this, but remember coming across a problem because there are two distinct probabilities. Since P(Home) and P(Away) are going to have different values, the probability of winning the series wouldn't be 0.5^N * (choose(N,4) - choose(N-1, 4)). It would be the sum of two formulas involving P(Home) and P(Away), correct? For example, if P(Home) = .65 and P(Away) = .5, the results would be different. Apr 10, 2018 at 2:56
• Yes, I am merely commenting on your calculations where both home and away win probs are 0.5. I have not looked at your code but it seemed to me that you can calculate the answer elegantly for this specific case. As of yet I do not know of an elegant way of calculating your desired result.
– Alex
Apr 10, 2018 at 4:02

Essentially you want to have a formula for the probability mass function of a negative binomial, except instead of observing the outcomes of identically distributed Bernoulli trials, we now have sequences of Bernoulli trials that are not identically distributed.

Unfortunately I do not know of a nice formula. However, we can derive a solution combinatorially by enumerating all possible paths that end when four team 1 wins or team 2 wins have been observed (these are respectively coded with 1's and 0's in the following functions). I will go through the steps by commenting in-line within these two functions in R.

get_succ_prob <- function(p, q) { # modify as necessary depending on pattern of home/away games
# probability team 1 wins at the i-th game
# can extend to other game win probs
c(p, p, q, q, p, q, p)
}

The main work is done by this function. n_trials is the number of games in the series, n_success is the number of games required to win the series, and succ_prob is the vector (generated by the previous function), such that the i-th element is the probability that team 1 wins the i-th game.

get_win_prob <- function(n_trials, n_success, succ_prob) {

stopifnot(length(succ_prob) == n_trials)

# enumerate 2^n_trials sequences of 0, 1.
tmp_mat <- as.matrix(do.call(expand.grid, rep(list(0:1), n_trials)))

# now terminate series of games at the first instance
# four zeroes or ones are observed
tmp_mat <- t(apply(tmp_mat, 1, function(x) {

threshold_to_NA <- suppressWarnings(min(min(which(cumsum(x == 0) == n_success)), min(which(cumsum(x == 1) == n_success))))
x[seq_len(n_trials) >= (threshold_to_NA + 1)] <- NA

return(x)
}
))

# Find unique paths to a series ending
tmp_mat <- unique(tmp_mat)

# calculate probability of observing series of game outcomes
prob_row <-
apply(tmp_mat, 1, function(x) prod(succ_prob * x + (1 - succ_prob) * (1 - x),
na.rm = T))

# make data frame and aggregate by team/series length
tmp_df <- data.frame(tmp_mat)

tmp_df$prob <- prob_row tmp_df$winning_team <-
2 - (rowSums(tmp_df[, seq_len(n_trials)], na.rm = T) == n_success)

tmp_df$trials_required <- n_trials - rowSums(is.na(tmp_df[, seq_len(n_trials)])) out_df <- aggregate(tmp_df$prob, by = list(tmp_df$trials_required, tmp_df$winning_team), FUN = sum)
names(out_df) <- c('games_required_to_win', 'winning_team', 'win_prob')

return(out_df)
}

> get_win_prob(7, 4, get_succ_prob(0.5, 0.5))
games_required_to_win winning_team win_prob
1                     4            1  0.06250
2                     5            1  0.12500
3                     6            1  0.15625
4                     7            1  0.15625
5                     4            2  0.06250
6                     5            2  0.12500
7                     6            2  0.15625
8                     7            2  0.15625

On more general home/away win probs:

> get_win_prob(7, 4, get_succ_prob(0.6, 0.3))
games_required_to_win winning_team win_prob
1                     4            1 0.032400
2                     5            1 0.116640
3                     6            1 0.093960
4                     7            1 0.192456
5                     4            2 0.078400
6                     5            2 0.120960
7                     6            2 0.236880
8                     7            2 0.128304


text:
# wx.lib.plot.utils¶

## utils.py¶

This is a collection of utilities used by the wx.lib.plot package.

## Functions Summary¶

 pairwise s -> (s0,s1), (s1,s2), (s2, s3), … pendingDeprecation Raise PendingDeprecationWarning and display a message. scale_and_shift_point Creates a scaled and shifted 2x1 numpy array of [x, y] values. set_displayside Wrapper around _DisplaySide that allows for “overloaded” calls.

## Classes Summary¶

 DisplaySide Generic class for describing which sides of a box are displayed. PlotPendingDeprecation Base class for warnings about deprecated features. TempStyle Decorator / Context Manager to revert pen or brush changes.

### Functions¶

pairwise(iterable)

s -> (s0,s1), (s1,s2), (s2, s3), …

pendingDeprecation(new_func)

Raise PendingDeprecationWarning and display a message.

Uses inspect.stack() to determine the name of the item that this is called from.

Parameters

new_func (string.) – The name of the function that should be used instead.

scale_and_shift_point(x, y, scale=1, shift=0)

Creates a scaled and shifted 2x1 numpy array of [x, y] values.

The shift value must be in the scaled units.

Parameters
• x (float) – The x value of the unscaled, unshifted point

• y (float) – The y valye of the unscaled, unshifted point

• scale (np.array) – The scale factor to use [x_sacle, y_scale]

• shift (np.array) – The offset to apply [x_shift, y_shift]. Must be in scaled units

Returns

a numpy array of 2 elements

Return type

np.array

Note

$$new = (scale * old) + shift$$

set_displayside(value)

Wrapper around _DisplaySide that allows for “overloaded” calls.

If value is a boolean: all 4 sides are set to value

If value is a 2-tuple: the bottom and left sides are set to value and the other sides are set to False.

If value is a 4-tuple, then each item is set individually: (bottom, left, top, right)

Parameters

value (bool, 2-tuple of bool, or 4-tuple of bool) – Which sides to display.

Raises

TypeError if setting an invalid value.

Raises

ValueError if the tuple has incorrect length.

Return type

_DisplaySide


text:
# Anharmonicity

In classical mechanics, anharmonicity is the deviation of a system from being a harmonic oscillator. An oscillator that is not oscillating in harmonic motion is known as an anharmonic oscillator where the system can be approximated to a harmonic oscillator and the anharmonicity can be calculated using perturbation theory. If the anharmonicity is large, then other numerical techniques have to be used. In reality all oscillating systems are anharmonic, but most approximate the harmonic oscillator the smaller the amplitude of the oscillation is.

As a result, oscillations with frequencies ${\displaystyle 2\omega }$ and ${\displaystyle 3\omega }$ etc., where ${\displaystyle \omega }$ is the fundamental frequency of the oscillator, appear. Furthermore, the frequency ${\displaystyle \omega }$ deviates from the frequency ${\displaystyle \omega _{0}}$ of the harmonic oscillations. See also intermodulation and combination tones. As a first approximation, the frequency shift ${\displaystyle \Delta \omega =\omega -\omega _{0}}$ is proportional to the square of the oscillation amplitude ${\displaystyle A}$:

${\displaystyle \Delta \omega \propto A^{2}}$

In a system of oscillators with natural frequencies ${\displaystyle \omega _{\alpha }}$, ${\displaystyle \omega _{\beta }}$, ... anharmonicity results in additional oscillations with frequencies ${\displaystyle \omega _{\alpha }\pm \omega _{\beta }}$.

Anharmonicity also modifies the energy profile of the resonance curve, leading to interesting phenomena such as the foldover effect and superharmonic resonance.


text:
# 4.6 Poisson distribution  (Page 4/18)

 Page 4 / 18

## References

“ATL Fact Sheet,” Department of Aviation at the Hartsfield-Jackson Atlanta International Airport, 2013. Available online at http://www.atlanta-airport.com/Airport/ATL/ATL_FactSheet.aspx (accessed May 15, 2013).

Center for Disease Control and Prevention. “Teen Drivers: Fact Sheet,” Injury Prevention&Control: Motor Vehicle Safety, October 2, 2012. Available online at http://www.cdc.gov/Motorvehiclesafety/Teen_Drivers/teendrivers_factsheet.html (accessed May 15, 2013).

“Children and Childrearing,” Ministry of Health, Labour, and Welfare. Available online at http://www.mhlw.go.jp/english/policy/children/children-childrearing/index.html (accessed May 15, 2013).

“Eating Disorder Statistics,” South Carolina Department of Mental Health, 2006. Available online at http://www.state.sc.us/dmh/anorexia/statistics.htm (accessed May 15, 2013).

“Giving Birth in Manila: The maternity ward at the Dr Jose Fabella Memorial Hospital in Manila, the busiest in the Philippines, where there is an average of 60 births a day,” theguardian, 2013. Available online at http://www.theguardian.com/world/gallery/2011/jun/08/philippines-health#/?picture=375471900&index=2 (accessed May 15, 2013).

“How Americans Use Text Messaging,” Pew Internet, 2013. Available online at http://pewinternet.org/Reports/2011/Cell-Phone-Texting-2011/Main-Report.aspx (accessed May 15, 2013).

Lenhart, Amanda. “Teens, Smartphones&Testing: Texting volum is up while the frequency of voice calling is down. About one in four teens say they own smartphones,” Pew Internet, 2012. Available online at http://www.pewinternet.org/~/media/Files/Reports/2012/PIP_Teens_Smartphones_and_Texting.pdf (accessed May 15, 2013).

“One born every minute: the maternity unit where mothers are THREE to a bed,” MailOnline. Available online at http://www.dailymail.co.uk/news/article-2001422/Busiest-maternity-ward-planet-averages-60-babies-day-mothers-bed.html (accessed May 15, 2013).

Vanderkam, Laura. “Stop Checking Your Email, Now.” CNNMoney, 2013. Available online at http://management.fortune.cnn.com/2012/10/08/stop-checking-your-email-now/ (accessed May 15, 2013).

“World Earthquakes: Live Earthquake News and Highlights,” World Earthquakes, 2012. http://www.world-earthquakes.com/index.php?option=ethq_prediction (accessed May 15, 2013).

## Chapter review

A Poisson probability distribution of a discrete random variable gives the probability of a number of events occurring in a fixed interval of time or space, if these events happen at a known average rate and independently of the time since the last event. The Poisson distribution may be used to approximate the binomial, if the probability of success is "small" (less than or equal to 0.05) and the number of trials is "large" (greater than or equal to 20).

## Formula review

X ~ P ( μ ) means that X has a Poisson probability distribution where X = the number of occurrences in the interval of interest.

X takes on the values x = 0, 1, 2, 3, ...

The mean μ is typically given.

The variance is σ 2 = μ , and the standard deviation is
.

When P ( μ ) is used to approximate a binomial distribution, μ = np where n represents the number of independent trials and p represents the probability of success in a single trial.

Use the following information to answer the next six exercises: On average, a clothing store gets 120 customers per day.

Assume the event occurs independently in any given day. Define the random variable X .

What values does X take on?

0, 1, 2, 3, 4, …

What is the probability of getting 150 customers in one day?

What is the probability of getting 35 customers in the first four hours? Assume the store is open 12 hours each day.

0.0485

What is the probability that the store will have more than 12 customers in the first hour?

What is the probability that the store will have fewer than 12 customers in the first two hours?

0.0214

Which type of distribution can the Poisson model be used to approximate? When would you do this?

Use the following information to answer the next six exercises: On average, eight teens in the U.S. die from motor vehicle injuries per day. As a result, states across the country are debating raising the driving age.

Assume the event occurs independently in any given day. In words, define the random variable X .

X = the number of U.S. teens who die from motor vehicle injuries per day.

X ~ _____(_____,_____)

What values does X take on?

0, 1, 2, 3, 4, ...

For the given values of the random variable X , fill in the corresponding probabilities.

Is it likely that there will be no teens killed from motor vehicle injuries on any given day in the U.S? Justify your answer numerically.

No

Is it likely that there will be more than 20 teens killed from motor vehicle injuries on any given day in the U.S.? Justify your answer numerically.

#### Questions & Answers

If X is a Uniform random variable in [ -2, 2 ], find the pdf of Y X  and E Y[ ].
Kezang Reply
I want to know statistics
Okosa Reply
why is data so important in statistics
Trixie Reply
want summary statistic on gender, age group, weight, and weight loss
Trixie
are you asking question or looking for Solution
Arun
solution pls
Trixie
1st convert gender and group to factor than use summary function It will give mean median and mode with other details
Arun
its a bit complicated could u bring it to my level of under standing
Trixie
u know the question was put in a tabular form where we were to find the variable type, summary statistics and graph type of the given variables that's the gender,age group, weight and weight loss
Trixie
if you see, gender and group are not numerical due to which they will not give you correct statistics
Arun
how you denote gender m or f
Arun
or t
Arun
ok tnk u
Trixie
these are not numerical so you have to convert they as f=1; m=2; t=3 same thing you have to do with group or any variable which is character else you should drop them
Arun
from your calculation
Arun
oh OK tnk u
Trixie
so pls why is data important in statistics
Trixie
not only data correct data is imp
Arun
statistics works on data only
Arun
without data you can not summarize, can not predict future, can not establish relationship between two and more variables, can not prepare reports and make decisions on it
Arun
so I'll give example. suppose you want to open a restaurant and you have to choose one best location out of 5. then how you will decide which location is best for you
Arun
awww thank you pls
Trixie
pls I want a brief note on observation, survey and experimentation way of obtaining data
Trixie
hi
Abdiwahab
please Tell me difference parameters and non parameter
Abdiwahab
can you tell me about the scopes of statistics?
Minhal
plzzz answer me anyone .
Minhal
Methods of Collecting Data Observation Observational studies allow researchers to document behavior in a natural setting and witness events that could not be produced in a lab.
Arun
Key Points Observation differs from most other forms of data collection in that the researcher does not manipulate variables or directly question participants. The advantages of observation include observing natural behavior, refining hypotheses, and allowing for observation of behavior that canno
Arun
be produced in an artificial environment for ethical or practical reasons. The disadvantages of observation are that these studies do not produce quantitative data, do not allow for cause and effect statements, may be very time consuming, and can be prone to researcher bias.
Arun
Key Terms observational research: Research focusing on the observation of behavior outside of a laboratory setting. external validity: In research, whether or not study findings can be generalized to real world scenarios.
Arun
Surveys and Interviews Surveys are a low-cost option for gathering a large amount of data, but they are also susceptible to reporting bias.
Arun
Key Points The survey method of data collection is likely the most common of the four major research methods. The benefits of this method include low cost, large sample size, and efficiency.
Arun
The major problem with this method is accuracy: since surveys depend on subjects’ motivation, honesty, memory, and ability to respond, they are very susceptible to bias. A researcher must have a strong understanding of how to properly frame survey questions in order to gather reliable and relevant
Arun
Key Terms reliability: The degree to which a measure is likely to yield consistent results each time it is used. validity: The degree to which a measure is actually assessing the concept it was designed to measure. survey: A method for collecting qualitative and quantitative information about ind
Arun
individuals in a population.
Arun
Interviews Interviews are a type of qualitative data in which the researcher asks questions to elicit facts or statements from the interviewee. Interviews used for research can take several forms:
Arun
Informal Interview: A more conversational type of interview, no questions are asked and the interviewee is allowed to talk freely. General interview guide approach: Ensures that the same general areas of information are collected from each interviewee. Provides more focus than the conversational ap
Arun
approach, but still allows a degree of freedom and adaptability in getting the information from the interviewee. Standardized, open-ended interview: The same open-ended questions are asked to all interviewees. This approach facilitates faster interviews that can be more easily analyzed and compared
Arun
Closed, fixed-response interview (Structured): All interviewees are asked the same questions and asked to choose answers from among the same set of alternatives.
Arun
experiments An experiment involves the creation of a contrived situation in order that the researcher can manipulate one or more variables whilst controlling all of the others and measuring the resultant effects.
Arun
Boyd and Westfall1 have defined experimentation as: "...that research process in which one or more variables are manipulated under conditions which permit the collection of data which show the effects, if any, in unconfused fashion."
Arun
Experiments can be conducted either in the field or in a laboratory setting. When operating within a laboratory environment, the researcher has direct control over most, if not all, of the variables that could impact upon the outcome of the experiment
Arun
When experiments are conducted within a natural setting then they are termed field experiments. The variety test carried out by United Fruits on their Gros Michel and Valery bananas is an example of a field experiment.
Arun
parameter Parameters are factors or limits which affect the way that something can be done or made
Arun
Minhal didny get your question, can you please elaborate more
Arun
pls can u use mean n mode at the statistical summary pls
Trixie
yes, statistical summary itself gives all value
Arun
but u didn't tell me the advantage and disadvantage of the experimental method
Trixie
but you didn't tell me the advantage and disadvantage of experimental method
Trixie
by using a sampling distribution? how to estimate the population mean using a ramdom variable n?
Jade Reply
The “average increase” for all NASDAQ stocks is the:
da Reply
any video any proof...what is point of estimation in statistics
Younis Reply
Define the meaning of statistics
Robert Reply
sampli
Hidayat
roductory Statistics is intended for the one-semester introduction to statistics course for students who are not mathematics or engineering majors. It focuses on the interpretation of statistical results, especially in real world settings, and assumes that students have an understanding of intermedi
Hidayat
statistics is science collection of method planning experiment then organizing summarizing presenting analyzing and drawing conclusion.
MOVIES
uses and miss uses of statistics
Pure
Identify the population, sample, parameter, statistic, variable, and data for this example. population sample parameter statistic variable data
Woyo
kinds of probability samples and there advantage
Hajira Reply
are you going to explain it.
Anil
🙂
Meera
hy
Muhammad
what....?
Muhammad
Sampling takes on two forms in statistics: probability sampling and non-probability sampling: Probability sampling uses random sampling techniques to create a sample. Non-probability samplingtechniques use non-random processes like researcher judgment or convenience sampling.
Muhammad
Advantages Cluster sampling: convenience and ease of use. Simple random sampling: creates samples that are highly representative of the population. Stratified random sampling: creates strata or layers that are highly representative of strata or layers in the population. Systematic sampling: creates
Muhammad
any example plz?
Anil
Plz write the uses and miss uses of statistical theory
Pure
what is the difference between weighted simple price index (WSPI ) & Laspeyre's Price Index ( LPI )
Basil Reply
What are the 5 steps of hypothesis testing?
Sixolisiwe Reply
5 steps of hypothesis testing
Sixolisiwe
Make guesses (e.g., customers will leave if we raise our rates) State the null H0 and alternative H1 hypotheses (e.g., H0: there is no correlation) and alpha Select the sampling distribution and specify the test statistic Compute the test statistic Make a decision and interpret the results
Ara
.Five Steps in Hypothesis Testing: 1_Specify the Null Hypothesis. 2_Specify the Alternative Hypothesis. 3_Set the Significance Level (a) 4_Calculate the Test Statistic and Corresponding P-Value. 5_Drawing a Conclusion.
Rachel
.Econometric Results uses Multiple Regression for the basis of looking at number of casual factors (independent χ Variables) such as Employment, being Female etc., to test for any relationship with the dependent γ Variable Wages, in order to find any evidence to support the Alternative Hypothesis(Ha
Rachel
.Alternative Hypothesis (H1 or Ha) of Wage Differentials or in the extreme case, if the strength of relationship is strong enough between the dependent γ Variable, and multiple χ Variables, suggesting evidence for the Null Hypothesis ( Ho) that Wage Discrimination may exist.
Rachel
.The Significance Level which is also the Critical Value gives the maximum allowable probability of making a Type I error – the Significance Level value of which is decided upon before the data sample is collected and analysed, as a guide to avoid or control making a Type I error.
Rachel
Type I Error occurs when the Null Hypothesis (Ho) is not accepted when in reality the Null Hypothesis is true. A Type II Error however, occurs when one fails to reject the Null Hypothesis when in reality, the Null Hypothesis (Ho) is not true.
Rachel
.The #P-Value measures the likelihood of getting the sample results if the Null Hypothesis were true, and could be defined as the smallest level of significance (observed level of significance) at which the Null Hypothesis will be rejected, assuming the Null Hypothesis (Ho) is true.
Rachel
.In most cases, the research attempt is to find support for the Alternative Hypothesis (Ha or H1). Thus, the smaller the P-Value, the more the (the father out the #Test-Statistics is on the Standard Normal Distribution Diagram, and the more confident the researcher can be about rejecting the Null H
Rachel
.#Test-Statistics is on the Standard Normal Distribution Diagram, and the more confident the researcher can be about rejecting the Null Hypothesis (Ho) in support for the Alternative Hypothesis (H1 / Ha).
Rachel
.The #P-Value is less than the Critical Values (Significance Level) of 1% (0.01), 5% (0.05), and 10% (0.10) given in Table (1) in the Appendix, means the Null Hypothesis (Ho) that there is Wage Discrimination is not reflective of the population or equal to the Mean of the Population
Rachel
.Mean of the Population(data sample of Sample Mean distribution of the Population ) which confirms that the Researcher Rejects the Null Hypothesis (Ho) and Accepts the (Alternative Hypothesis).
Rachel
.See ISBN 1537512757 ; link : https://smile.amazon.co.uk/Winston-Chellie-Economics-TheBachelor-questions/dp/1537512757/ref=mp_s_a_1_1?keywords=Rachel+Adeniji&qid=1572318698&sr=8-1
Rachel
see publication ' Winston and Chellie by Rachel Adeniji '
Rachel
correction, dependent x variables such as Employment, being Female; dependent y variable Wages
Rachel
correction, Wage Differentials such as Employment, Region affecting Wages; Wage Discrimination such as being Female or Ethnicity affecting Wages
Rachel
correction_, linear regression/equation is computed as y=mx + c or y=m • x1+x2+x3+c where independent x variables eg Employment x1, Female x2 , Ethnicity x3, and dependent y variable Wages
Rachel
how do you draw a line of best fit?
Josh Reply
***youtu.be/l2BOZDosuIk
William
informal explanation:lets suppose you have 10 points and you want a line to best fit on all of them. all you need to keep in mind that the distance and error should be minimum and you will get the best fit line.
umair
how was the data collected to draw the graph
Nji
draw a straight line through the points on the graph that are most clustered with other data / points
Rachel
suppose that 30% of the employees in a large factory of smokers what is the probability that there will be exactly two smokers in a randomly-chosen five-person workgroup
rayhaanah Reply
binomialPdf(5, .3, 2) .3087
Ara
are the fraction integers
Amir Reply
The ratio of male to female nurses is 2:3 or 2/3. There are 40 nurses in the ward. For every 5 nurses, how many male and female nurses are there? How many groups can be divided into shifts. Pls show the solution and explain.
DokBads Reply
in a group of 5, the probability tbat exactly 3 of the nurses are male is .6630 or 66% calculation P(X=0)+(...)+P(X=3)=.6630
Ara
i dont think u got a correct answer. you are computing for the probability not the ratio and proportion
DokBads
(2+5)/40*2 = male , (2+5)/40*3 = female
Rachel
40/(2+3)*2 = male , 40/(2+3)*3=female, ....sorry correction
Rachel
thank you so much for the help
DokBads
x
Rachel
Iyhoo
Sixolisiwe
if x is a continuous random variable and c is a constant then p(x=c)
Neha Reply
the length of human pregnancies from conception to birth approximates a normal distribution with a mean of 266days and a standard deviation of 16days.(i) what length of time marks the shortest 10%of all pregnancies ?
Neha
27.6390625 days
festus
steps?
Neha
how can I solve a Hypothetic problem that provide sample data such as 45,3_,45,28,17 ect...what is the first step
Leticia
find the mean and standard deviation first
Kwadwo
how can I get line of best fit?
Josh

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text:
## Partial Differential Classification

$u_{x}u_{xx}+xuu_{y}=sin(y)$ in the book is classified as quasi linear

also,

$u_{x^2}+uu_{y}=1$ is classified as non-linear.

So why would the first one be quasi instead of non-linear?


text:
The Community for Technology Leaders
Issue No. 07 - July (2000 vol. 49)
ISSN: 0018-9340
pp: 659-672
ABSTRACT

Abstract—Integer addition is one of the most important operations in digital computer systems because the performance of processors is significantly influenced by the speed of their adders. This paper proposes a self-timed carry-lookahead adder in which the logic complexity is a linear function of <tmath>$n$</tmath>, the number of inputs, and the average computation time is proportional to the logarithm of the logarithm of <tmath>$n$</tmath>. To the best of our knowledge, our adder has the best area-time efficiency which is <tmath>$\Theta(n\log\log n)$</tmath>. An economic implementation of this adder in CMOS technology is also presented. SPICE simulation results show that, based on random inputs, our 32-bit self-timed carry-lookahead adder is 2.39 and 1.42 times faster than its synchronous counterpart and self-timed ripple-carry adder, respectively; and, based on statistical data gathered from a 32-bit ARM simulator, it is 1.99 and 1.83 times faster than its synchronous counterpart and self-timed ripple-carry adder, respectively.

INDEX TERMS
Self-timed circuits, delay-insenstive circuits, carry-lookahead adders, tree iterative circuits, CMOS.
CITATION
Michael Theobald, Fu-Chiung Cheng, Stephen H. Unger, "Self-Timed Carry-Lookahead Adders", IEEE Transactions on Computers, vol. 49, no. , pp. 659-672, July 2000, doi:10.1109/12.863035
FULL ARTICLE
CITATIONS
SHARE
251 ms
(Ver 3.3 (11022016))


text:
## finite math

True or false. The objective function of the primal problem can attain an optimal value that is different from the optimal value attained by the dual problem. *I know this is "true" but I want to see proof and or an explanation please.


text:
A calculator for the Kramers Kronig transform of X-ray spectra

## Project description

======
KKcalc
======

Introduction
============

KKcalc is a program to calculate the real part of the refractive index of a material in the X-ray region of the spectrum from measured absorption data via the Kramers-Kronig transform using an algorithm developed by Watts [WATTS2014]_. KKcalc boasts the following features:

- Easily extend measured spectra with published scattering factors.
- Efficient peicewise polynomial (direct integration) algorithm for Kramers-Kronig transform.
- Automatic calculation of the relativistic correction.
- Python source code is easy to read, so you can assess its correctness yourself.
- Freely available on a wide range of platforms.
- Graphical interface for easy use.

The major emphasis of this program is to provide **correct** results. I would be glad to be informed of any problems.
Please consider citing the article [WATTS2014]_ when publishing work that utilises this calculation.

PYPI Installation
============

KKcalc <https://pypi.org/project/kkcalc/>_ is included in the PyPI <https://pypi.org/>_ package management system. To automatically install KKcalc together with all the modules it depends on, simply run the command::

pip install kkcalc

Further details about pip usage can be found in the PyPI installation tutorial <https://packaging.python.org/tutorials/installing-packages/>_

Manual Installation
============
Download the software (e.g. as a zip file). The zip file contains::

kk.py
kk_gui.py
data.py
test_kk.py
PackRawData.py
ASF.json
asf/
elements.dat
h.nff
he.nff
...
u.nff

You will also need to install the following dependencies:

- Python_
- Numpy_ (Numerical Python)
- Scipy_ (Scientific Python) - optional package, needed only for the "fix distortions" option
- wxPython_ - optional package, needed only for the graphical user interface

.. _Python: http://www.python.org/
.. _Numpy: http://numpy.scipy.org/
.. _Scipy: http://scipy.org/
.. _wxPython: http://wxpython.org/

Basic Usage
===========

1. Start program by running python kk_gui.py
3. Check that the selection box knows the type of the raw data, so that it is being converted to scattering factors correctly.
4. Enter molecular formula in the "Material" section.
5. Click on the "Calculate" button. The new real scattering factors are plotted upon completion of the Kramers-Kronig transform calculation (should only take a second, idepending on the number of data points and computing power).
6. Save data by selecting: File>Save.

For more advanced usage and scripting, check out the functions provided in the kk.py module.

Details
=======

"Near-Edge Data" Section
------------------------

Here we define a detailed section of the imaginary spectrum to be inputted into the Kramers-Kronig transform. The "File:" label simply displays the currently loaded data file. To load a new set of near-edge absorption data, select: *File>Load*. Data files must be in columns, the first giving the photon energy in electron volts and the last column giving the absorption spectrum data.

The two text-boxes in the next row, initially containing "Start" and "End" control the energy points between which the loaded data will be used. Valid entries in these controls include energy values and the strings "Start" or "End", which are understood by the program to correspond to the lowest and highest energy points, respectively, in the loaded data set.

There are two further options seen as checkboxes at the bottom of the "Near-Edge Data" section of the GUI. The "Add background" checkbox is for replacing the background (by extrapolating the pre-edge region) that may have been subtracted from the user-supplied data. This function has not been reimplemented to work with the internal data format currently used by KKcalc and the checkbox is disabled. The "Fix distortions" option (whose checkbos is disabled if the program fails to load the Scipy module) will skew the data to fit the slope of the scattering factor data. This is useful for working with data recorded using detectors with an uncalibrated energy dependence. The detector energy dependence is assumed to be approximately linear (which should hold fairly well over a short energy range) and the scattering factors may not be a good reference to fit the data to, so the use of this option is definitely not encouraged (it is always better to understand and properly normalise your data before loading into KKcalc).

"Material" Section
------------------

In this section, we define the material whose optical properties are being investigated. The first textbox is for the density of the material - a value here is only needed in converting data between scattering factors and Beta (the absorption part of the refractive index). This value will have no effect unless you are working with data loaded or saved as Beta. The second textbox is for entering the elemental composition of the material. This will be plotted and used to calculate the appropriate scattering factors to extend the user-supplied near-edge imaginary spectrum as well as to calculate the relativistic correction to the Kramers-Kronig transform.

"Calculation" Section
---------------------

KKcalc implements a piecewise polynomial algorithm that performs direct integration of the area between the data-points. [WATTS2014]_ User-supplied data and the scattering factor below 30,000 eV [HENKE1993]_ is interpolated linearly, while the high energy scattering factor data is described by Laurent polynomials [BIGGS1988]_ (the scattering factor data is assembled as described by Henke et al. [HENKE1993]_). Using this piecewise-polynomial expression of the imaginary spectrum, the symbolic form of the Kramers-Kronig transform integral is precisely known and can be fully written symbolically (albeit piecewise). This form is then trivial (though tedious) to symbolically integrate in a piecewise fashion everywhere except at the singularity, which is avoided by integrating across two intervals at once (terms referencing the singularity cancel out). The only assumption of this method is that the piecewise-polynomial description of the imaginary spectrum is continuous (which is required by physics), all remaining steps are exact to machine precision. This algorithm is very efficient because it doesn't require equally spaced steps, which would correspond to a very large number of samples over the full energy range of the spectrum.

The calculation of the relativistic correction deserves some mention too, since I have seen a number of programs not calculating it correctly. Information on the types and number of atoms present are taken from the "Material" box and the equation :math:Z - (\frac{Z}{82.5})^{2.37} (as described by Henke et al. [HENKE1993]_) is applied to each atom separately and the individual corrections then summed.

References
----------

.. [WATTS2014] Benjamin Watts
"Calculation of the Kramers-Kronig transform of X-ray spectra by a piecewise Laurent polynomial method"
*Opt. Express* **22**, (2014) 23628-23639. DOI:10.1364/OE.22.023628 <https://doi.org/10.1364/OE.22.023628>_

.. [HENKE1993] B.L. Henke, E.M. Gullikson, and J.C. Davis
"X-ray interactions: photoabsorption, scattering, transmission, and reflection at E=50-30000 eV, Z=1-92"
*Atomic Data and Nuclear Data Tables* **54**\ (2) (1993) 181-342.

.. [BIGGS1988] F. Biggs, and R. Lighthill
"Analytical approximations for X-ray cross-sections III"
*Sandia Report* SAND87-0070 UC-34 (1988).


text:
# Projection along affine hull

Let n_1,...,n_r be integral points in a polyhedron P. The paper I am reading refers to "the projection of P along aff(n_1,...,n_r)". Here aff(n_1,...,n_r) is the affine hull of n_1,...,n_r. Can I accomplish this projection in sage?

edit retag close merge delete

Could we have a precise definition of what is meant by "projection of P along the affine hull"? This would make the question more precise.

( 2017-10-10 12:55:27 -0500 )edit

Sort by » oldest newest most voted

Here is an example. It requires to load the Projection function:

sage: from sage.geometry.polyhedron.plot import Projection

Let's say we have the following polytope:

sage: P = Polyhedron(vertices=[[-2,0,3],[2,0,3],[0,2,1],[0,-2,1]])

and we are interested in the affine space spanned by the points

sage: affine_basis = [vector([1,1,2]),vector([1,-1,2]),vector([-1,-1,2])]

we first get a linear subspace and create the projection matrix:

sage: linear_subspace = [ap - affine_points[0] for ap in affine_basis[1:]]
sage: VS = VectorSpace(QQ,3)
sage: proj_matrix = matrix([sum([v.inner_product(lv)*lv/(lv.inner_product(lv)) for lv in linear_subspace]) for v in VS.basis()]).transpose()

Then, we create a function that will emulate the affine projection (notice the addition of the first element of the affine basis).

sage: def my_proj(x): return proj_matrix*x + affine_basis[0]

Then, we project the polytope and use the transformed coordinates of the vertices to create a new polytope.

sage: proj_p = Projection(P,proj=my_proj)
sage: projected_P = Polyhedron(vertices=proj_p.transformed_coords)

Now, we can see the difference between

sage: P
A 3-dimensional polyhedron in ZZ^3 defined as the convex hull of 4 vertices
sage: P.vertices()
(A vertex at (-2, 0, 3),
A vertex at (0, -2, 1),
A vertex at (0, 2, 1),
A vertex at (2, 0, 3))

and the resulting polytope:

sage: projected_P
A 2-dimensional polyhedron in QQ^3 defined as the convex hull of 4 vertices
sage: projected_P.vertices()
(A vertex at (0, -2, 2),
A vertex at (0, 0, 2),
A vertex at (2, 2, 2),
A vertex at (2, 4, 2))

more


text:
# Topology ad Geometry of $\mathbb{C}^n/\mathbb{Z}_k$

I would like to know topologically what the space $(\mathbb{C}^n – \{0\})/\mathbb{Z}_k$ may be thought of as.

The paper I am reading says that we let $\mathbb{Z}_k$ act on $\mathbb{C}^n – \{0\}$ via $z \rightarrow e^{\frac{2\pi i}{k}}z$.

Perhaps I am just not thinking of this in the right way but I cannot see what the quotient space will look like. Moreover this space is then endowed with the quotient flat metric and later referred to as a metric cone. So is this a topological cone space, if so is the group action incorrect for this?

#### Solutions Collecting From Web of "Topology ad Geometry of $\mathbb{C}^n/\mathbb{Z}_k$"

Topologically it’s not so interesting, but geometrically it’s a cone. The action is rotation by $2\pi / k$. It’s what you would obtain by taking a $2\pi / k$-sector of the complex plane and gluing the ends together via rotation. This gives a nice flat metric everywhere besides for the origin, because the angle around $z=0$ is just $2 \pi / k$, which is less than the requisite $2\pi$ for $k>1$. In other words, this is just a cone with the origin being the cone point, with the cone point then being removed.


text:
# There is no Spoon — Episode 1

### The Goal

The game is played on a rectangular grid with a given size. Some cells contain power nodes. The rest of the cells are empty.

The goal is to find, when they exist, the horizontal and vertical neighbors of each node.

### Rules

To do this, you must find each $\left( x1, y1 \right)$ coordinates containing a node, and display the $\left(x2, y2\right)$ coordinates of the next node to the right, and the $\left(x3, y3\right)$ coordinates of the next node to the bottom within the grid.

If neighbor does not exist, you must output the coordinates $\left(-1, -1\right)$ instead of $\left(x2, y2\right)$ and/or $\left(x3, y3\right)$.

You lose if:

• You give an incorrect neighbor for a node.
• You give the neighbors for an empty cell.
• You compute the same node twice.
• You forget to compute the neighbors of a node.

## Game input

The program must first read the initialization data from standard input. Then, provide to the standard output one line per instruction.

### Initialization input

Line 1: one integer width for the number of cells along the x axis.

Line 2: one integer height for the number of cells along the y axis.

Next height lines: A string line containing width characters. A dot . represents an empty cell. A zero 0 represents a cell containing a node.

$0 <$ width$\le 30$
$0 <$ height$\le 30$

## Output for one game turn

One line per node. Six integers on each line: x1 y1 x2 y2 x3 y3 Where:

• ( x1, y1) the coordinates of a node.
• ( x2, y2) the coordinates the closest neighbor on the right of the node.
• ( x3, y3) the coordinates the closest bottom neighbor.
$0 \le$ x1$<$ width
$0 \le$ y2$<$ height
$-1 \le$ x2, x3$<$ width
$-1 \le$ y2, y3$<$ height
Alloted response time to first output line $\le 1$s.
Response time between two output lines $\le 100$ms.

Input Output
2 2
00
0.
0 0 1 0 0 1
1 0 -1 -1 -1 -1
0 1 -1 -1 -1 -1
4 4
.0..
.000
000.
..0.
1 0 -1 -1 1 1
1 1 2 1 1 2
2 1 3 1 2 2
3 1 -1 -1 -1 -1
0 2 1 2 -1 -1
1 2 2 2 -1 -1
2 2 -1 -1 2 3
2 3 -1 -1 -1 -1

# Solution of the task

First of all, we must pay attention, that we have to find the closest neighbor. It doesn’t mean, that if there is no neighbor on adjacent cells, then the answer will be negative, because the neighbor may be further. This leads to the fact, that the task can not be completed without memorization of the whole list of cells.

After storing every string in array, the task becomes simple: we go using the cycle through every cell, and if the cell contains a node, then we launch two cycles from it in two directions (to the right and to the bottom), and assume there are no neighbors with assigning value -1 to both variables ansX and ansY. If there will be no nodes found, the value will remain the same, otherwise variables will take values of the node coordinates. In any case, the result will be correct.

This process is optimized by usage of the following: the $x$ coordinate of the closest right neighbor (or the value of width) is saved in a variable x2. Whether we find a neighbor or no, we can start the further horizontal search right from the coordinate x2, because empty cells must be skipped anyway.


text:
## On a certain two-sided symmetric condition in magnetic field analysis and computations.(English)Zbl 0902.65078

A finite element method for solving a nonlinear boundary value problem of elliptic type with mixed boundary conditions is investigated. The problem describes the nonlinear stationary magnetic field distributed in a planar domain composed of different isotropic media. The authors introduce a special two-sided condition for the incremental magnetic reductivity which guarantees the existence and uniqueness of the weak and approximate solutions. The main theorem establishes the convergence of the finite element method in the Sobolev $$H^1(\Omega)$$-norm. A numerical example for the calculation of a magnetic potential in a synchronous rotary machine is given.

### MSC:

 65Z05 Applications to the sciences 65N30 Finite element, Rayleigh-Ritz and Galerkin methods for boundary value problems involving PDEs 65N12 Stability and convergence of numerical methods for boundary value problems involving PDEs 35Q60 PDEs in connection with optics and electromagnetic theory 78A30 Electro- and magnetostatics
Full Text:

### References:

 [1] K. Chrobáček, F. Melkes, L. Rak: Stationary magnetic field computation of electrical machines. TES 1977, theoretical number, 22-29. [2] P.G. Ciarlet: The Finite Element Method for Elliptic Problems. North-Holland, Amsterodam, 1978. · Zbl 0383.65058 [3] E.A. Erdelyi, E.F. Fuchs, (D.H. Binkley): Nonlinear magnetic field analysis of DC machines I, II, III. IEEE Trans., PAS-89 (1970), 7, 1546-1583. [4] A. Foggia, J.C. Sabonnadière, P. Silvester: Finite element solution of saturated travelling magnetic field problems. IEEE Trans., PAS-94 (1975), 866-871. [5] Glowinski, A. Marrocco: Analyse numerique du champ magnetique d’un alternateur par elements finis et sur-relaxation ponctuelle non lineaire. Comput. Methods Appl. Mech. Engrg. 3 (1974), 55-85. · Zbl 0288.65068 [6] B. Lencová, M. Lenc: A finite element method for the computation of magnetic electron lenses. Scanning Electron Microscopy 1986/III, SEM Inc., AMF O’Hare, Chicago, 1986, pp. 897-915. [7] F. Melkes: Solving the magnetic field by the finite element method. PhD. Thesis, Czechoslovak Academy of Sciences, Prague, 1970. · Zbl 0209.17201 [8] F. Melkes: The finite element method for non-linear problems. Apl. Mat. 15 (1970), 177-189. · Zbl 0209.17201 [9] F. Melkes: Magnetic energy computation using piecewise linear approximations. Acta Tech. ČSAV (1990), 365-373. [10] J. Polák: Variational Principles and Methods of Electromagnetic Theory. Academia, Prague, 1988. [11] H. Reiche: Die Ermittlung stationärer magnetischer Felder in elektrischen Maschinen. IX. Internat. Kolloquium TH, Ilmenau, 1966. [12] P. Silvester, H.S. Cabayan, B.T. Browne: Efficient techniques for finite element analysis of electric machines. IEEE Trans., PAS-92 (1973), 1274-1281. [13] H. Tsuboi, F. Kobayashi, T. Misaki: Two-dimensional magnetic field analysis using edge elements. Proc. of the Third Japanese-Czech-Slovak Joint Seminar on Applied Electromagnetics, Prague, 1995, pp. 53-56. [14] A.M. Winslow: Numerical solution of the quasilinear Poisson equation in a non-uniform triangle mesh. LRL Livermore California, 1967, pp. 149-172. · Zbl 0254.65069 [15] A. Ženíšek: The maximum angle condition in the finite element method for monotone problems with applications in magnetostatics. Numer. Math. 71 (1995), 399-417. · Zbl 0832.65124
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.


text:
# 40-bit encryption

40-bit encryption refers to a key size of forty bits, or five bytes, for symmetric encryption; this represents a relatively low level of security. A forty bit length corresponds to a total of $2^{40}$ possible keys. Although this is a large number in human terms (about a trillion, nearly two hundred times the world's human population), it is possible to break this degree of encryption using a moderate amount of computing power in a brute force attack — that is, trying out each possible key in turn.

## Description

A typical home computer in 2004 could brute-force a 40-bit key in a little under two weeks, testing a million keys per second; modern computers are able to achieve this much faster. Using free time on a large corporate network or a botnet would reduce the time in proportion to the number of computers available.[1] With dedicated hardware, a 40-bit key can be broken in seconds. The Electronic Frontier Foundation's Deep Crack, built by a group of enthusiasts for US\$250,000 in 1998, could break a 56-bit Data Encryption Standard (DES) key in days,[2] and would be able to break 40-bit DES encryption in about two seconds.[3]

40-bit encryption was common in software released before 1996, when algorithms with larger key lengths could not legally be exported from the United States without a case-by-case license. "In the early 1990s ... As a general policy, the State Department allowed exports of commercial encryption with 40-bit keys, although some software with DES could be exported to U.S.-controlled subsidiaries and financial institutions."[4][5] As a result, the "international" versions of web browsers were designed to have an effective key size of 40 bits when using Secure Sockets Layer to protect e-commerce. Similar limitations were imposed on other software packages, including early versions of Wired Equivalent Privacy. In 1992, IBM designed the CDMF algorithm to reduce the strength of 56-bit DES against brute force attack to 40 bits, in order to create exportable DES implementations.

## Obsolescence

All 40-bit and 56-bit encryption algorithms are obsolete because they are vulnerable to brute force attacks, and therefore cannot be regarded as secure. As a result, virtually all web browsers now use 128-bit keys, which are considered strong. Some web servers will not communicate with a client unless it has a 128-bit encryption capability installed on it.

Public/private key pairs used in asymmetric encryption (public key cryptography) must be much longer than 128 bits for security; see key size for more details.

As a general rule, modern symmetric encryption algorithms such as AES use key lengths of 128, 192 and 256 bits.


text:
Integrating $3\sin(x/2)$.

$$\int 3\sin\left(\frac{x}{2}\right)dx$$

can't figure this one out! I'm not sure if I'm supposed to substitute or not?

Here's where I'm at...

$$3\int\sin\left(\frac{x}{2}\right)dx$$ $$u = \frac{x}{2}$$ $$du = \frac{1}{2}dx$$ $$dx = 2du$$ $$3\int\sin\left(u\right)2du$$

and then...

$$-6cos\left(\frac{u^2}{2}\right)$$ thats not right is it..?

-
Hint. Set $u=\frac{x}{2}$ and do a substitution. –  Arturo Magidin Jul 24 '12 at 3:24
I actually just tried that before I asked this and it turned out ugly! :[ –  Kudla69 Jul 24 '12 at 3:24
Then you are doing things wrong. It doesn't "turn ugly". Post your work and we'll tell you where you are messing up. –  Arturo Magidin Jul 24 '12 at 3:26
Is this homework? –  Ian Mateus Jul 24 '12 at 3:27
And how is that "ugly"? The factor of $2$ is multiplying, so you can pull it out exactly the same way you pulled out the $3$. And surely you know what $\int\sin(u)\,du$ is! –  Arturo Magidin Jul 24 '12 at 3:30
Let $x=2t\implies dx=2dt$. Hence your problem becomes $2\int 3\sin(t)dt=-6\cos(t)+c=-6\cos(x/2)+c$ where $c$ is a constant.


text:
# test which column in multicol

How can I test whether I'm on the left or right column of multicol?

I am trying to build a two-column table of contents, where formatting depends on wether the entry is on the left or right column

Here's a mockup (code below).

\documentclass{article}
\usepackage{multicol}
\usepackage[active,tightpage]{preview}
\PreviewEnvironment{multicols}
\setlength{\PreviewBorder}{1ex}
% mock TOC commands ===================================
\newcommand{\myStrut}{%
\rule[-.3\baselineskip]{0pt}{1.4\baselineskip}}

\newcommand{\myTocEntryLeft}[2]{%
\hfill\myStrut\textbf{\large #2} \ #1\par}

\newcommand{\myTocEntryRight}[2]{%
#1 \ \myStrut\textbf{\large #2}\hfill\par}

\newcommand{\myTocEntry}[2]{%
\myTocEntryLeft{#1}{#2}}

\begin{document} % ====================================

\begin{multicols}{2}[\dotfill\textbf{Contents}\dotfill]

\myTocEntry{Preface}{i}
\myTocEntry{Introduction}{30}
\myTocEntry{Exciting discovery}{5}
\myTocEntry{Visiting Delphi}{10}

\columnbreak % new column =============================
\renewcommand{\myTocEntry}[2]{%
\myTocEntryRight{#1}{#2}}

\myTocEntry{First-order problems}{20}
\myTocEntry{The pit}{30}
\myTocEntry{Not all is lost}{35}
\myTocEntry{Breakthrough}{42}

\end{multicols}

\end{document} % ======================================

• Possible duplicate: Detecting current column in multicol Mar 8 '18 at 16:25
• Will you always create the ToC manually? Mar 8 '18 at 16:28
• @Werner no, I would like it done automatically. Your link looks perfect. Reading it now. Mar 8 '18 at 16:38

It is really part of multicol packages for quite some time: option colactionand comand \docolaction.