32155732
Measurement issues across different cultures.
PURPOSE
The purposes of this methodologic paper are to (1) describe theoretical background in conducting research across different cultures; (2) address measurement issues related to instrument administration; and (3) provide strategies to deal with measurement issues.


METHODS
A thorough review of the literature was conducted. A theoretical background is provided, and examples of administering instrument in studies are described.


RESULTS
When applying an instrument to different cultures, both equivalence and bias need to be established. Three levels of equivalence, i.e., construct equivalence, measurement unit equivalence, and full score comparability, need to be explained to maintain the same concept being measured. In this paper, sources of bias in construct, method, and item are discussed. Issues related to instrument administration in a cross-cultural study are described.


CONCLUSION
Researchers need to acknowledge various group differences in concept and/or language that include a specific set of symbols and norms. There is a need to question the philosophical and conceptual appropriateness of an assessment measure that has been conceptualized and operationalized in a different culture. Additionally, testing different response formats such as narrowing response range can be considered to reduce bias.
9568740
Factor structure investigation of perceived facilitators and barriers in end-of-life care among Korean nurses.
AIM
The aim of this study was to assess the validity and reliability of the Korean version of a questionnaire assessing facilitators/barriers in end-of-life care that was originally developed for nurses in the USA.


METHODS
Back-translation was undertaken to produce the Korean version. A principal component analysis with varimax rotation and Cronbach's alpha was used to test factorial validity and reliability, respectively.


RESULTS
The analysis examined data from 383 nurses in a tertiary hospital in Korea. For end-of-life care facilitators, five factors accounted for 59% of the total variance. The factors were labeled "family preparedness", "support for nurses", "nurse-patient relationship", "transition after death", and "decision-making". Six factors, explaining 59% of the variance, were extracted for end-of-life care barriers. These factors were "misunderstanding patient's will", "preoccupied nursing workload", "lack of institutional support", "dealing with family's maladaptive coping", "visiting hours", and "communication about patient's status with family members". Cronbach's alpha was 0.89 for the 23 facilitator items and 0.90 for the 24 barrier items.


CONCLUSION
Overall, the findings demonstrate that the questionnaire has measurement properties in a sample of Korean nurses. Further studies are needed with different populations to reflect end-of-life care in various clinical settings.
14664327
Protein loop modeling by using fragment assembly and analytical loop closure.
Protein loops are often involved in important biological functions such as molecular recognition, signal transduction, or enzymatic action. The three dimensional structures of loops can provide essential information for understanding molecular mechanisms behind protein functions. In this article, we develop a novel method for protein loop modeling, where the loop conformations are generated by fragment assembly and analytical loop closure. The fragment assembly method reduces the conformational space drastically, and the analytical loop closure method finds the geometrically consistent loop conformations efficiently. We also derive an analytic formula for the gradient of any analytical function of dihedral angles in the space of closed loops. The gradient can be used to optimize various restraints derived from experiments or databases, for example restraints for preferential interactions between specific residues or for preferred backbone angles. We demonstrate that the current loop modeling method outperforms previous methods that employ residue-based torsion angle maps or different loop closure strategies when tested on two sets of loop targets of lengths ranging from 4 to 12.
205354931
Heritable Imprinting Defect Caused by Epigenetic Abnormalities in Mouse Spermatogonial Stem Cells1
Abstract Male germ cells undergo dynamic epigenetic reprogramming during fetal development, eventually establishing spermatogonial stem cells (SSCs) that can convert into pluripotent stem cells. However, little is known about the developmental potential of fetal germ cells and how they mature into SSCs. We developed a culture system for fetal germ cells that proliferate for long periods of time. Male germ cells from embryos 12.5–18.5 days postcoitum could expand by glial cell line-derived neurotrophic factor, a self-renewal factor for SSCs. These cells did not form teratomas, but repopulated seminiferous tubules and produced spermatogenesis, exhibiting spermatogonia potential. However, the offspring from cultured cells showed growth abnormalities and were defective in genomic imprinting. The imprinting defect persisted in both the male and female germlines for at least four generations. Moreover, germ cells in the offspring showed abnormal histone modifications and DNA methylation patterns. These results indicate that fetal germ cells have a limited ability to become pluripotent cells and lose the ability to undergo epigenetic reprogramming by in vitro culture.
6998054
Microcanonical origin of the maximum entropy principle for open systems.
There are two distinct approaches for deriving the canonical ensemble. The canonical ensemble either follows as a special limit of the microcanonical ensemble or alternatively follows from the maximum entropy principle. We show the equivalence of these two approaches by applying the maximum entropy formulation to a closed universe consisting of an open system plus bath. We show that the target function for deriving the canonical distribution emerges as a natural consequence of partial maximization of the entropy over the bath degrees of freedom alone. By extending this mathematical formalism to dynamical paths rather than equilibrium ensembles, the result provides an alternative justification for the principle of path entropy maximization as well.
9605549
Spectrum measurement of fast optical signal of neural activity in brain tissue and its theoretical origin
Functional brain imaging technologies have enabled recent advances in understanding human brain function. In particular, a noninvasive and fast optical technique will become one of the most promising tools for future studies. As a fundamental ex vivo study for the development of such a technique, this paper demonstrates the spectral measurement of fast optical changes associated with neural activity in bulk brain tissue. For this purpose, a high-speed confocal near-infrared spectrometer was built and used. The results verified that observed transient optical responses (tORs) are associated with neural activity by showing that the following: tORs were concurrent and correlated with local field potentials (LFPs); tORs disappeared following tetrodotoxin application; and tORs were reproducibly observed across preparations. In addition, the amplitude of tORs was statistically significantly larger in longer wavelengths (approximately 1200 nm). The time course of tORs, however, is quite different from that of LFPs. Since this difference implies that tORs may originate not directly from the electric potential variation but from other neurophysiological events accompanying excitation, this paper tested the hypothesis that tORs are attributed to transient cellular volume changes (tCVCs). With no previous dynamic equation to elucidate such different temporal dynamics of the optical responses, a novel mathematical neuron model to describe tCVCs was developed. This neuron model, along with finite-difference time-domain simulations, showed that tCVCs and tORs were similar in the temporal dynamics, order of magnitude, response direction, and detectability in the bulk tissue; thus supporting the hypothesis.
23590250
Successful cyclophosphamide therapy with complete resolution of pulmonary artery aneurysm in Hughes–Stovin syndrome patient
Hughes–Stovin syndrome is an exceedingly rare disorder of unknown etiology, and it is characterized by multiple pulmonary artery aneurysms and peripheral venous thrombosis. We report a case of Hughes–Stovin syndrome with complete resolution of pulmonary artery aneurysm after treatment with cyclophosphamide. A 48-year-old man presented with massive hemoptysis, fever, and weight loss of 4-month duration. Computed tomography angiography revealed multiple pulmonary arterial aneurysms of variable sizes in both lung fields. Inferior vena caval thrombosis was also noted. Despite multiple surgical procedures including embolectomy and lobectomy combined with steroid therapy, new aneurysms continued to appear with persistent hemoptysis. Thorough history and physical examination did not suggest any evidence of Behcet’s disease. Hughes–Stovin syndrome was subsequently diagnosed. High-dose prednisolone combined with oral cyclophosphamide therapy was initiated. Chest radiography follow-up in 3 months revealed complete resolution of pulmonary aneurysm. No new aneurysm was detected at 15 months of follow-up.