cssi/SciSciGPT-SciSciNet huggingface dataset:
Phase behavior, morphology, and mechanical properties of polyethylene-copolymer blends

Binary blends of unbranched polyethylene (PE) and 5-10% model ethylene-butene random copolymers are used to determine the effects of composition heterogeneity on phase separation in the melt, semicrystalline morphology, plane strain fracture toughness JC and tensile modulus and yield strength. Slowly cooled samples of melt-miscible blends are appreciably tougher (JC = 5.2 kJ/m2) than unblended PE (JC = 2.7 kJ/m2). A blend with the same average short chain branch concentration, but which is phase separated in the melt state, has JC= 3.3 kJ/m2; dispersed domains of amorphous polymer have little effect on toughness. Enhanced toughness is associated with nonuniform morphology formed on slow cooling “one phase” melts composed of chains with different amounts of branching. The relative number of chemically different chains, as opposed to absolute branch concentrations, seems most important. Tensile properties are relatively unaffected by blending at these levels. Results from these model blends are used to consider the properties of compositionally heterogeneous ethylene copolymers. © 1994 John Wiley & Sons, Inc.
The mechanism of two-dimensional pocket formation in lean premixed methane-air flames with implications to turbulent combustion

Abstract The mechanism of unburnt pocket formation in an unsteady two-dimensional premixed lean methane-air flame is investigated using direct numerical simulations. Theoretical results for nonlinear diffusion equations combined with analytical examples are used to interpret some of the results. Flame structure and propagation show three distinct stages of pocket formation: (1) flame channel closing involving head-on quenching of flames, (2) cusp recovery, and (3) pocket burnout. The flame channel closing and subsequent pocket burnout are mutual annihilation events that feature curvature, diffusion normal to the flame front, unsteady strain rate effects, and singularities in flame propagation and stretch rate. The results show that during channel closing and pocket burnout thermo-diffusive and chemical interactions result in the acceleration of the flames prior to annihilation; the time scales associated with the final stage of mutual annihilation and the initial stage of cusp recovery are significantly smaller than diffusive and convective time scales. As in earlier one-dimensional studies, the acceleration is attributed to enhanced diffusion and reaction rates, modifications to species profiles leading to shifts in balance between diffusion and reaction, and vanishing species and thermal gradients at the location in the channel where the pocket pinches off. Flame propagation and stretch rate are singular at this location. Enhanced radical production is initiated by a reversal of diffusion of H2 towards the reaction zone during the early stages of thermo-diffusive interactions. Peak radical concentrations resulting from flame channel closing and pocket burnout exceed peak laminar values by as much as 25%. After the merging of the fuel consumption layers, radical production and flame structure shifts more towards an H2/CO/O2 system at the expense of hydrocarbon reactions. Species thermodiffusive interaction times are shorter than the unstrained one-dimensional counterpart due to unsteady strain and convection. Curvature effects on the flame propagation are prominent during pocket burnout and cusp recovery. The recovery stage shows strong dependence on diffusion of radicals left from the channel closing stage. This diffusion is amplified by the strong curvature of the flame cusp.
The Value Proposition for Assurance of JPL Systems

Abstract This paper presents a value proposition for systems assurance. The need for a value proposition is motivated by common misconceptions about the definition of assurance and the value of performing systems assurance activities. The focus of the value proposition is that assurance reduces uncertainty so that projects can make more confident decisions about their systems. Applying the value proposition has led to insights into the nature of assurance and has improved the practice of software assurance, where it has been applied at the Jet Propulsion Laboratory (JPL). Ongoing work on using the value proposition for “value-based tailoring” of requirements and integrating value considerations into assurance cost models are also discussed.
Flexible Engineers: History, Challenges, and Opportunities for Engineering Education:

Flexibility is a desired characteristic that people must have to adjust to inevitable processes of economic, cultural, and political globalization. Engineering education reform is often used as a j...
Health care costs associated with traumatic brain injury and psychiatric illness in adults.

Abstract A cohort design was used to determine the contribution of traumatic brain injury (TBI) and psychiatric illness to health care costs for adolescents and adults in the 3 years following mild or moderate-to-severe TBI compared to a matched cohort without TBI, controlling for confounders. In all, 3756 subjects 15 years or older from a large health maintenance organization database were examined. We identified subjects who sustained a TBI in 1993 (n=939) and selected three control subjects per TBI-exposed subject (n=2817), matched for age, sex, and enrollment at the time of injury. Unadjusted mean costs in 2009-adjusted dollars were compared using Kruskal-Wallis tests and Mann-Whitney U tests, and adjusted mean costs were compared using gamma regression analyses. Average costs were 76% higher in the 3 years after injury for the mild TBI group, and 5.75 times greater for the moderate-to-severe TBI group compared to controls. The presence of psychiatric illness was associated with more than doubling of ...
The AST petal dedicated bifurcation stent: first-in-human experience.

The aim of this first-in-human study was to evaluate the feasibility and safety of the novel AST petal side-access bifurcation stent. Outcomes following percutaneous coronary intervention for bifurcations remain inferior to those of nonbifurcated lesions. Even with drug-eluting stents, restenosis occurs especially at the side-branch (SB) ostium. The petal stent uniquely deploys strut elements into the SB, supporting the ostium and carina. The primary endpoint of this 13-patient prospective registry was in-hospital major adverse cardiac events (MACE). Secondary end points included acute minimum lumen diameter (MLD) at the SB ostium, lesion success, device success, procedural success, 30-day MACE, and 4-month SB ostial MLD. The study lesion was successfully treated in 13 patients with the study stent being successfully implanted in 12. Target lesions were left anterior descending coronary artery in nine subjects, left circumflex in three, and right coronary artery in one. In-hospital MACE were limited to two non-Q-wave myocardial infarctions. In-stent main branch MLD increased from a mean of 0.63 ± 0.45 mm to 2.61 ± 0.47 mm at the index procedure and for this initial bare metal version of the stent, 4-month mean MLD measured 1.02 ± 0.42mm and there was target vessel revascularization on two patients. The feasibility of safely deploying this first-generation petal stent was demonstrated in selected patients with challenging coronary bifurcation lesions. It is a promising platform for drug delivery, with unique scaffolding of the side-branch ostium. © 2007 Wiley-Liss, Inc.
Development And Testing Of A Prototype Mosaic Wedge-And-Strip Anode Detector

A preliminary laboratory study of a prototype mosaic wedge-and-strip anode, a new class of readout system that will furnish large format, high resolution microchannel plate detectors with comparatively simple readout electronics is described. The goals of this study were to demonstrate the linearity of the mosaic anode algorithm, and to verify the predicted resolution performance in a realistic detector configuration. It is found that the nonlinearity introduced at the boundary between two anodes is limited to 50-100 microns. It is also shown that the spatial resolution of the detector is limited mainly by partition noise to about 35 microns (FWHM) at a gain of 2 x 10 to the 7th. A systematic investigation of the charge distribution arriving at the anode is also described. Using the relative charges arriving on the two anodes of the mosaic pattern, the detailed shape of the distribution and its dependence on MCP-anode voltage, MCP voltage, and pulse height are determined. A significant dependence of the profile on pulse height, which can introduce a pulse height dependence to the centroid calculation, particularly near the anode edges is found. Improved anode designs which will achieve the optimal performance are discussed.
Fracture Toughness and Reliability in High-Temperature Structural Ceramics and Composites: Prospects and Challenges for the 21st Century

The importance of high fracture toughness and reliability in Si3N4, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defense and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fiber into Si3N4 and SiC matrices. All toughening mechanisms, e.g. crack deflection, crack branching, crack bridging, etc., essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability. Because of flaw insensitivity, continuous fiber reinforced ceramic composite (CFCC) was found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibers should display sufficient high temperature strength and creep resistance at service temperatures above 1000 'C. The greatest challenge to date is the development of high quality ceramic fibers with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are, preparation of optimum matrix precursors, precursor infiltration into fiber array, and matrix densification at a temperature, where grain crystallization and fiber degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems.
RNA-seq analysis of early hepatic response to handling and confinement stress in rainbow trout.

Fish under intensive rearing conditions experience various stressors which have negative impacts on survival, growth, reproduction and fillet quality. Identifying and characterizing the molecular mechanisms underlying stress responses will facilitate the development of strategies that aim to improve animal welfare and aquaculture production efficiency. In this study, we used RNA-seq to identify transcripts which are differentially expressed in the rainbow trout liver in response to handling and confinement stress. These stressors were selected due to their relevance in aquaculture production. Total RNA was extracted from the livers of individual fish in five tanks having eight fish each, including three tanks of fish subjected to a 3 hour handling and confinement stress and two control tanks. Equal amount of total RNA of six individual fish was pooled by tank to create five RNA-seq libraries which were sequenced in one lane of Illumina HiSeq 2000. Three sequencing runs were conducted to obtain a total of 491,570,566 reads which were mapped onto the previously generated stress reference transcriptome to identify 316 differentially expressed transcripts (DETs). Twenty one DETs were selected for qPCR to validate the RNA-seq approach. The fold changes in gene expression identified by RNA-seq and qPCR were highly correlated (R2 = 0.88). Several gene ontology terms including transcription factor activity and biological process such as glucose metabolic process were enriched among these DETs. Pathways involved in response to handling and confinement stress were implicated by mapping the DETs to reference pathways in the KEGG database.
Arbitrary waveform generation with high repetition rate optical frequency combs

I discuss experiments in which individual spectral lines of high repetition rate optical frequency combs are independently manipulated. New characterization techniques for the resulting optical arbitrary waveforms, and applications to measurement of fiber dispersion and radio-frequency arbitrary waveform generation, are described.
Influence of Asthma or Allergies on the Utilization of Health Care Resources and Quality of Life of College Students

The objectives of this study were to describe the treatment regimens of college students with asthma or allergies, to determine how asthma or allergies affect the lives of college students, and to evaluate the health care resources utilized by college students with asthma or allergies. A mail survey was sent to 275 students who received treatment for asthma or allergies at the Thomson Student Health Center at The University of South Carolina (TSHC-USC) during the fall 1991 semester. This survey, consisting of 46 questions, covered three key areas: current asthma or allergy management, class and work days missed, and utilization of health care resources. Students with “asthma and allergy” missed on average 2.4 days of class during the fall semester, whereas those with “asthma only” and “allergy only” missed on average 0.8 day and 1.5 days of class, respectively. Students with “allergy only” appeared to have a greater interference in their daily class and academic activities than students with “asthma and a...
Posey and spiller and progressive supranuclear palsy: An incorrect attribution

In 1904 and 1905, respectively, William Campbell Posey and William Spiller both described the case of a patient with progressive ophthalmoparesis and imbalance that has come to be regarded as the earliest report of progressive supranuclear palsy. No autopsy was thought to have been performed on this patient. In this report, we review the clinical history provided by Posey and Spiller. We also report on the subsequent autopsy of their patient, which was performed by Spiller in 1906. The chief finding was a tumor involving the right cerebral peduncle and periaqueductal area. The autopsy findings prove conclusively that the patient described by Spiller and Posey had a midbrain neoplasm and not progressive supranuclear palsy.
Policy Evaluation for Policy Communities: Confronting the Utilization Problem

Essays, opinions, and professional judgments are welcome in this section of EP. Forum articles speak to and about the philosophical and ethical dilemmas of our profession. Authors are invited to express their views to encourage constructive dialogue centered on issues. To keep the dialogue substantive, other articles motivated by previous Forum presentations should have independent titles and themes. Itemslabeled "Comments on ..."and"Rejoinder to ...'will not be published inForum - suchresponses, and those notof articlelength or nature, are welcome and encouraged in the Letters section ofEP.Standard citations and reference lists should acknowledge andidentifyearlier contributions and viewpoints.Manuscripts should not exceed 10 double-spaced typewritten pages in length.
Antenatal diagnosis of congenital heart disease by fetal phonocardiography.

Abstract A case is reported wherein a fetal heart murmur and irregular fetal heart sounds were heard at the thirtieth week of gestation of a 30-year-old woman during a routine prenatal visit. Fetal phonocardiogram and ECG's were recorded; they strongly suggested the presence of congenital heart disease and frequent premature ventricular beats. After birth, both clinically and at autopsy, the presence of congenital heart disease was confirmed.
Classification of Acanthamoeba

Members of the genus Acanthamoeba are being isolated with increasing frequency from clinical specimens, especially contact lens solutions. Although the genus was first established in 1931, considerable confusion about its taxonomic classification existed in the literature until recently. A brief commentary on this confusion is provided, and the taxonomic classifications of Acanthamoeba and the three groups of species are described.
The volume and hydration of the Cryptococcus neoformans polysaccharide capsule.

Abstract We present a new method to measure capsule size in the human fungal pathogen Cryptococcus neoformans that avoids the limitations and biases inherent in India ink measurements. The method is based on the use of γ-radiation, which efficiently releases the capsule from the cell. By comparing the volume of irradiated and non-irradiated cells, one can accurately estimate the relative size of the capsule per cell. This method was also used to obtain an estimate of the capsule weight and water content. The C. neoformans capsule is a highly hydrated structure in all the conditions measured. However, after capsule enlargement, the amount of capsular polysaccharide significantly increases, suggesting a that capsule growth has a high energy cost for the cell.
HYPERFINE MAGNETIC FIELDS AT NUCLEI OF INDIUM IN IRON AND NICKEL

Hyperfine magnetic fields for In in Fe and Ni were determined by nuclear orientation of ${\mathrm{In}}^{114m}$ in Fe and Ni alloys. A ${\mathrm{Co}}^{57}$ thermometer was used in each case. The results are: ${H}_{\mathrm{hf}} (\mathrm{In}\mathrm{in}\mathrm{Fe})=\ensuremath{-}295\ifmmode\pm\else\textpm\fi{}10$ kG; ${H}_{\mathrm{hf}} (\mathrm{In}\mathrm{in}\mathrm{Ni})=\ensuremath{-}42\ifmmode\pm\else\textpm\fi{}5$ kG.
Effect of sucrose polyester on plasma lipids and cholesterol absorption in African green monkeys with variable hypercholesterolemic response to dietary cholesterol

Abstract The effect of sucrose polyester (SPE), a nonabsorbable fat, on plasma lipids and cholesterol absorption was studied in 29 adult male African green monkeys whose plasma cholesterol concentrations ranged from 133 to 358 mg/dl while consuming a diet containing 0.36 mg cholesterol/kcal. SPE was added to this diet at concentrations equivalent to doses for human beings of 15, 30, and 45 g/day. All 29 animals were fed either no SPE or one of the three concentrations of SPE for 2-mo intervals in a Latin square experimental design which ultimately allowed each animal to receive all dietary treatments. The lowest concentration of SPE reduced absorption of dietary cholesterol in all animals by an average of 16%. Increasing the concentration of SPE did not further decrease cholesterol absorption. Plasma cholesterol concentrations, however, were reduced by SPE only in the most hypercholesterolemic animals. The plasma cholesterol lowering effect was progressively less in animals that were less responsive to dietary cholesterol, such that in animals with plasma cholesterol concentrations less than 200 mg/dl there was no effect of SPE. The cholesterol lowering effect of SPE was due entirely to a lowering in LDL, with no effect on HDL cholesterol or triglycerides. Animals with the greatest plasma cholesterol response (hyperresponders) absorbed a significantly higher percentage of dietary cholesterol than did hyporesponders (56% vs. 37%). When cholesterol absorption was decreased in hyperresponders by SPE to levels equivalent to hyporesponders, the hyperresponders still maintained higher plasma cholesterol concentrations. Thus, the difference in cholesterol absorption appears to only partially explain the individuality in plasma cholesterol response to dietary cholesterol. These results also suggest that SPE may be a particularly useful drug in lowering plasma cholesterol concentrations in individuals that are hyperresponsive to dietary cholesterol.
Divergent effects of medroxyprogesterone acetate on growth hormone and prolactin in the MStTW15 tumor bearing rat.

Female Wistar Furth rats bearing the transplanted pituitary tumor MStTW15, which secretes GH and prolactin (Pr), were injected 3 times weekly for 2 or 3 weeks with medroxyprogesterone acetate (MPA). When compared to untreated tumor-bearing rats there was a dramatic rise in serum GH and little change in serum Pr. No significant alterations in tumor growth were noted. Tumor GH concentration was increased by MPA, whereas tumor Pr conconcentration was unaltered. MPA did not affect the clearance of GH from the serum after tumor removal. As previously reported, in situ pituitary content of GH and Pr were reduced in tumor bearing rats. MPA therapy further lowered pituitary Pr. Adrenal atrophy and decreased serum corticosterone levels were noted after MPA treatment, but corticosterone replacement did not alter the increased serum and tumor GH concentrations induced by MPA. It is concluded that MPA exerted a selective effect on this tumor of pituitary origin by stimulating the storage and release of GH without aff...
The distribution of 210Pb and 210Po in the surface waters of the Pacific Ocean

Abstract By modelling the observed distribution of 210 Pb and 210 Po in surface waters of the Pacific, residence times relative to particulate removal are determined. For the center of the North Pacific gyre these are τ Po = 0.6years andτ Pb = 1.7years . The surface ocean τ Pb is determined by particulate transport rather than plankton settling. The fact that it is about two orders of magnitude smaller than τ Pb for the deep ocean implies a sharp change in the adsorptive quality of particles during descent through the water column.
Cellular spectroscopy and multi-angle light scattering by flow cytometry: optical test bench as a developmental tool

We designed and fabricated a flow cytometry work bench for the purpose of testing optical schemes utilized in two specialized flow cytometry techniques. Fluorescent spectroscopy and multi-angle scattering of laser light has potential for generating novel classes of cell population information. The acquisition of full fluorescence spectrum of dye bound to living cells may associate specific function to spectral shift. Similarly, detection of 2 discrete angles of light scatter was shown to describe internal structures of cells based on refractive and diffractive properties. We utilized a flow cytometry electro- cells based on refractive and diffractive properties. We utilized a flow cytometry electro- optical test bench to develop and describe alternate light collection schemes for these two techniques. Mouse bone marrow was chosen as the subject of analysis because it contains a consistent mix of cells that possess distinct biophysical properties. More importantly, these cells are the source of various biological systems that are targeted by environmental stress and clinical disease.
Standardization of In Vitro Macrophotography for Assessment of Cutaneous Responses

The increased popularity of commercially available three-dimensional human skin equivalents in recent years has allowed for assessment of melanogenesis modulated by compounds topically applied to the skin or directly incorporated from the medium. These skin equivalents provide a suitable model for elucidating the mechanisms of action of various factors that modulate skin pigmentation or other properties of the skin. As such, researchers need to objectively quantify cutaneous responses at the macroscopic level. A simple method to standardize macrophotography images is reported that can quantify cutaneous responses in human skin equivalents of Asian, Black or African American, and Caucasian or White racial/ethnic origin. Macrophotographs are analyzed using the Commission Internationale de l'Eclairage L * a * b * color space system in combination with a personal computer and image editing software. Pigmentation changes monitored over a 9 day period showed a high correlation with melanin content evaluated in Fontana―Masson-stained sections. These results indicate the feasibility of using a macrophotography setup in a sterile tissue culture environment to objectively assess in vitro cutaneous responses in human skin equivalents. This serves as an adjunct tool to biochemical and morphological methods to effectively quantify changes in pigmentation over time.
The origin of fine scale acoustic stratigraphy in deep-sea carbonates

In this paper we investigate the origin and geologic significance of the closely spaced high-frequency subbottom acoustic reflectors characteristic of pelagic carbonates. A detailed survey was conducted of a small area in the equatorial Pacific with the Marine Physical Laboratory's Deep-Tow instrument package, providing high-resolution 4-kHz profiles and precise positioning of core samples. The cores were sampled at closely spaced intervals for sound velocity and saturated bulk density. Acoustic impedances were calculated, and a reflection coefficient log determined for the upper 10 m of the sediment column. The reflection coefficient log revealed no interfaces with large reflection coefficients that correlated with the reflectors seen on the Deep-Tow 4-kHz seismic profile. The calculated reflection coefficients were very low (typically 10−3–10−5) and varied about a wavelength that was on the order of the wavelength of the 4-kHz pulse, implying that interference plays a role in the composition of the seismic record. Convolving the outgoing 4-kHz pulse with the reflection coefficient log generated a synthetic seismogram that very closely resembled the 4-kHz reflection profile. Varying the frequency of the outgoing pulse changed the amplitude and position of the reflectors seen on the synthetic seismograms. Thus we conclude that the reflectors seen on the 4-kHz seismic profile were not caused by discrete geologic horizons but rather are the result of the interference of many small layers.
Intramolecular Electron Transfer in Donor−Spacer−Acceptor Systems with Alkylamide Spacers

Intramolecular electron transfer and exciplex formation have been investigated for a family of styrene−spacer−amine molecules in which the spacer consists of a rigid amide group in the middle of a flexible alkane chain. The amide is connected to the styrene by either one or two methylene units and to a trialkylamine by two to six methylene units. The dependence of electron-transfer kinetics and exciplex formation have been investigated as a function of the length of the spacer, the orientation of the amide, and the amine oxidation potential. Intramolecular quenching of the styrene fluorescence intensity and lifetime is observed for all of the styrene−spacer−amine molecules. Quenching of styrene fluorescence is accompanied by the appearance of intramolecular styrene−amine exciplex fluorescence in nonpolar solvents. The low energy of the exciplex fluorescence emission maximum in nonpolar solvents is attributed to internal solvation by the polar amide group. A maximum in the quantum yield for exciplex fluore...
Iosipescu Shear deformation and fracture in model thermoplastic polyolefins

Shear deformation and fracture behaviors in polypropylene (PP)-based model thermoplastic polyolefins (TPOs) were investigated with the Iosipescu shear test. The shear deformation process was monitored in situ via video camera to obtain experimental shear stress–strain curves of model TPOs. Shear fracture mechanisms were studied with optical microscopy and scanning electron microscopy. Macroscopically, the cracks in neat PP propagated along the maximum shear plane, which indicated that mode-II shear failure existed in neat PP. Microscopically, it was shown that shear fracture initiated in the form of partial, discontinuous inclined microcracks that later coalesced and formed the final continuous crack. The incorporation of rubber in PP could transform the shear fracture process into a stretching process in the shear damage zone. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3201–3214, 2001
Political and Economic Results of November 2014

In November 2014, Vladimir Putin declared that he had no intentions to become Russia’s president-for-life. In spite of Putin’s assurances, this public statement has inevitably sent an alarming signal to society. In November 2014, a court of justice seized the company Bashneft from Vladimir Yevtushenkov’s AFK Sistema, justifying its decision by the claim that twenty years ago Bashneft had been wrongfully classified not as Russia’s property, but as property of the Republic of Bashkortostan. Mr. Yevtushenkov, charged with ‘legalizing illegally acquired property’, remains under house arrest. As a result, the investment climate in Russia has significantly deteriorated. Moreover, privatization of any major state-owned assets has become impossible – at least for the time being. The RF Government is using every opportunity to increase taxes, including the introduction of trade levies, and the abolition of tax deductions. November 2014 saw a series of mass rallies of doctors, protesting against the planned personnel cuts.
Laboratory robotics-getting machines to do the hazardous work

The types of tasks for which robots are used in laboratories are identified. Two specific types of laboratory robotic systems currently in use at Los Alamos are described. One is a plutonium dissolution system. The other, dubbed ROBOCAL, loosely stands for robotic calorimetry and gamma isotopic system. Both applications involve the handling of hazardous materials. >
A comparison of two bias-corrected covariance estimators for generalized estimating equations.

SummaryMancl and DeRouen (2001, Biometrics57, 126–134) and Kauermann and Carroll (2001, JASA96, 1387–1398) proposed alternative bias-corrected covariance estimators for generalized estimating equations parameter estimates of regression models for marginal means. The finite sample properties of these estimators are compared to those of the uncorrected sandwich estimator that underestimates variances in small samples. Although the formula of Mancl and DeRouen generally overestimates variances, it often leads to coverage of 95% confidence intervals near the nominal level even in some situations with as few as 10 clusters. An explanation for these seemingly contradictory results is that the tendency to undercoverage resulting from the substantial variability of sandwich estimators counteracts the impact of overcorrecting the bias. However, these positive results do not generally hold; for small cluster sizes (e.g., <10) their estimator often results in overcoverage, and the bias-corrected covariance estimator of Kauermann and Carroll may be preferred. The methods are illustrated using data from a nested cross-sectional cluster intervention trial on reducing underage drinking.
Performance-based assessment of graduate student research skills: timing, trajectory, and potential thresholds

The development of research skills and scientific reasoning underpins the mission of graduate education in science, technology, engineering and mathematics (STEM) fields, yet our understanding of this process is mainly drawn from self-report and faculty survey data. In this study, we empirically investigate the pattern of research skill development using STEM graduate students' written research proposals. Analyses of proposal performance data suggest a potential developmental trajectory of research skills, in which the ability to effectively situate work in context using primary literature, and to generate testable hypotheses, emerge early in students' careers, while other skills, such as data analysis and forming conclusions from data, appear to develop later. We discuss these findings in relation to threshold concepts theory, a framework which posits that intellectual growth occurs in transformative leaps rather than a gradual progression, especially as it applies to graduate student research skill deve...
Probing multimodal ligand binding regions on ubiquitin using nuclear magnetic resonance, chromatography, and molecular dynamics simulations☆

Site-directed mutagenesis, nuclear magnetic resonance (NMR) chemical shift perturbation experiments, and molecular dynamics (MD) simulations are employed in concert with chromatographic experiments to provide insight into protein-ligand interactions in multimodal chromatographic systems. In previous studies, a preferred binding region was identified on the surface of the protein ubiquitin for binding with a multimodal ligand. In this study, site-directed mutagenesis is used to enable direct NMR evaluation of the mutant protein as compared to the wild type. It is found that reversing the charge of a key residue (K6E) in the proposed preferred binding region results in substantial decreases in the magnitude of the ligand-induced NMR chemical shift perturbations relative to those detected for the wild type protein, particularly for residues located within the preferred binding region. These NMR results also indicate a decrease in ligand affinity, consistent with the weaker chromatographic retention observed for the mutant as compared to the wild type on a multimodal cation exchange resin. MD simulation results provide additional insight at a molecular level and demonstrate that many residues located within the preferred binding region exhibit weaker binding interactions due to the mutation. The analysis suggests that multimodal ligand binding consists of initial localization of the ligand by long-ranged electrostatic interactions followed by multiple short-ranged synergistic interactions to attain high affinities of the ligand to specific residues.
Novel NiZnAl-ferrites and strong magnetoelectric coupling in NiZnAl-ferrite/PZT multiferroic heterostructures

Magnetic/piezoelectric multiferroic heterostructures with strong magnetoelectric (ME) coupling have recently attracted considerable interest. Since the ratio of magnetostriction ?s over saturation magnetization Ms is a key factor to achieve strong magnetoelectric coupling in ferrite/piezoelectric multiferroic heterostructures, here we find a solution to tune ?s/Ms by aluminum doping. We report aluminum-substituted NiZn-ferrites with different compositions (Ni0.65Zn0.35Fe2?xAlxO4, x?=?0, 0.1, 0.3, 0.4, 0.6, 0.8 and 1) fabricated by a solid-state sintering process. The saturation magnetization of these NiZnAl-ferrites was reduced from 6000 to 900?G with increased Al doping, which was accompanied by a significantly narrowed ferromagnetic resonance linewidth from 1870 to 340?Oe. Meanwhile, saturation magnetostriction of these NiZnAl-ferrites was reduced from 6.67 to 1.40?ppm with increased amount of Al doping. Strong ME coupling was demonstrated in the NiZnAl-ferrites/PZT multiferroic heterostructures. A large piezoelectric deformation induced ferromagnetic resonance field change up to 42?Oe was observed in Ni0.65Zn0.35Fe1.2Al0.8O4/PZT heterostructures, corresponding to a large microwave ME coefficient of 4.2?Oe?cm?kV?1. These AlNiZn-ferrites and NiZnAl-ferrites/PZT heterostructures with large ME coupling provide a great opportunity for electrical tuning microwave devices.
Inefficient lactate dehydrogenases of deep-sea fishes.

The respiratory rates of deep-sea animals are extremely low. Deep-sea fishes may consume oxygen at rates only 5–10% those characteristic of shallow-water species1–4. These low metabolic rates are probably an adaptation to the presumed scarcity of food in deeper water4. The biochemical basis of this metabolic adaptation is a low level of enzyme activity in the skeletal muscle (but not the heart or brain), mainly because of the low enzyme concentrations in that tissue5. We report here, however, that a second source of reduced enzyme activity contributes to the low metabolic rate. For muscle-type (M4) lactate dehydrogenases (LDH, EC 1.1.1.27, NAD+ :lactate oxidoreductase), the enzymes of deep-sea fishes have significantly higher activation free energy (ΔG*) and enthalpy (ΔH*) characteristics than the homologous enzymes of cold-adapted, shallow-water fishes. Because of these higher energy barriers to catalysis, pyruvate is reduced to lactate at approximately 60% of the rate observed with LDHs of shallow-water fishes. Thus, in terms of rate of function per enzyme molecule, deep-sea fishes would be at a disadvantage in shallow waters because of their relatively poor capacity for muscle glycolysis. Such enzymatic factors may help determine the upper distributions of deep-sea species, much as the relatively large pressure insensltivities of LDHs of these deep-sea fishes6,7 may enable them to tolerate high and variable pressures. We suggest that the low catalytic efficiencies of high-pressure-adapted LDHs are concomitant with their low sensitivities to pressure.
Sorting of Streptavidin Protein Coats on Phase-Separating Model Membranes

Heterogeneities in cell membranes due to the ordering of lipids and proteins are thought to play an important role in enabling protein and lipid trafficking throughout the secretory pathway and in maintaining cell polarization. Protein-coated vesicles provide a major mechanism for intracellular transport of select cargo, which may be sorted into lipid microdomains; however, the mechanisms and physical constraints for lipid sorting by protein coats are relatively unexplored. We studied the influence of membrane-tethered protein coats on the sorting, morphology, and phase behavior of liquid-ordered lipid domains in a model system of giant unilamellar vesicles composed of dioleoylphosphatidylcholine, sphingomyelin, and cholesterol. We created protein-coated membranes by forming giant unilamellar vesicles containing a small amount of biotinylated lipid, thereby creating binding sites for streptavidin and avidin proteins in solution. We found that individual tethered proteins colocalize with the liquid-disordered phase, whereas ordered protein domains on the membrane surface colocalize with the liquid-ordered phase. These observations may be explained by considering the thermodynamics of this coupled system, which maximizes its entropy by cosegregating ordered protein and lipid domains. In addition, protein ordering inhibits lipid domain rearrangement and modifies the morphology and miscibility transition temperature of the membrane, most dramatically near the critical point in the membrane phase diagram. This observation suggests that liquid-ordered domains are stabilized by contact with ordered protein domains; it also hints at an approach to the stabilization of lipid microdomains by cross-linked protein clusters or ordered protein coats.
International Organizations as Policy Advisors

How can international organizations persuade governments to adopt policy recommendations that are based on private information when their interests conflict? We develop a game-theoretic model of persuasion that applies regardless of regime type and does not rely on the existence of domestic constituency constraints. In the model, an international organization (IO) and a domestic expert have private information about a crisis, but their preferences diverge from those of the government, which must choose whether to delegate decision making to the expert. Persuasion can take place if the international institution is able to send a credible signal. We find that this can take place only if the preferences of the IO and the domestic expert diverge and the institution holds the more moderate policy position. This result contrasts with conventional wisdom, which holds that the necessary condition for IOs to exert influence is support from a domestic constituency with aligned preferences. Our model suggests that, far from being an obstacle to international cooperation, polarized domestic politics may be a necessary condition for IOs to exert effective influence.
Bridging Universal and Cultural Perspectives: A Vision for Developmental Psychology in a Global World

This article argues that now is an opportune time to draw together the accumulated bodies of knowl- edge in developmental and cultural psychology in order to build a new vision for developmental psychology scholar- ship that bridges universal and cultural perspectives. Such bridging requires rethinking (a) the entity of developmen- tal psychological analysis, (b) the scope and meaning of developmental psychology concepts, and (c) the nature of theoretical frameworks. This rethinking will render devel- opmental psychology more broadly valid across cultures and more applicable to local cultural conditions. This is imperative in an increasingly global world where diverse peoples interact more than ever. Although the present focus is on rethinking developmental psychology, conclu- sions about the implications of bridging universal and cul- tural perspectives may be of interest in other fields and disciplines addressing psychological thought and behav- ior.
Lost In Translation? Reflections On The Role Of Research In Improving Health Care For Children

While the budget of the National Institutes of Health (NIH) has grown to double its 1993 level, growing understanding of the chasm between the “health care we have and the health care we could have” has led to a stronger focus on the need to translate research into practice. Children’s health care has much to gain from this new emphasis; however, the unique features of children’s health, health services, and the history of funding for child health research are limiting our ability to make rapid progress.
Role of PC2 in Proenkephalin Processing: Antisense and Overexpression Studies

The contribution of the prohormone-processing enzyme PC2 to the proteolytic maturation of proenkephalin was examined in three sets of studies. In the first, the processing of this precursor was compared in PC2-rich (Rin5f) and PC2-lacking (AtT-20) cell lines expressing proenkephalin by virtue of stable transfection. These studies showed that the time frame for processing of this precursor is cell line specific, with AtT-20 cells processing proenkephalin to peptide B much more rapidly than Rin cells. However, the latter cell line processed proenkephalin much more extensively, i.e., produced a greater proportion of the penta- to octapeptide enkephalins. The involvement of PC2 in these later processing events was analyzed by examining the processing of proenkephalin in PC2-overexpressing AtT-20 cell lines. These experiments yielded a processing profile similar to that observed for Rin cells, although the time frame of initial processing was similar to that found in AtT-20 cells. To confirm the physiological involvement of proenkephalin in the production of the small opioid peptides, we generated a Rin cell line in which the production of PC2 was impaired due to stable expression of antisense mRNA to this enzyme. These experiments provided conclusive evidence that the generation of Met-enkephalin-Arg-Phe and Met-enkephalin-Arg-Gly-Leu, but not the larger enkephalin-containing peptides, is mediated by PC2. Taken together, our data support the idea that PC2 is physiologically capable of mediating only the later processing steps of neuropeptide precursors. PC2 thus appears to be the primary enzyme responsible for the generation of bioactive opioid peptide species from proenkephalin.
Polymers for Fabricating Nerve Conduits

Peripheral nerve regeneration is a complicated and long-term medical challenge that requires suitable guides for bridging nerve injury gaps and restoring nerve functions. Many natural and synthetic polymers have been used to fabricate nerve conduits as well as luminal fillers for achieving desired nerve regenerative functions. It is important to understand the intrinsic properties of these polymers and techniques that have been used for fabricating nerve conduits. Previously extensive reviews have been focused on the biological functions and in vivo performance of polymeric nerve conduits. In this paper, we emphasize on the structures, thermal and mechanical properties of these naturally derived synthetic polymers, and their fabrication methods. These aspects are critical for the performance of fabricated nerve conduits. By learning from the existing candidates, we can advance the strategies for designing novel polymeric systems with better properties for nerve regeneration.
Geometric feature extraction using the chord transformation

Geometric feature extraction can play an important role in the understanding of the content of an image. Methods such as the Hough transform are useful, but are subject to restrictions imposed by scale and object orientation. This paper describes the chord transform, not widely used to date, primarily due to the computational requirements. The chord transform can be used to detect geometric edge structural content within an image. Various adaptations of the chord transform, its implementation, and some practical applications in geometric feature extraction are discussed in this paper.
Comparison of methylene blue-directed biopsies and conventional biopsies in the detection of intestinal metaplasia and dysplasia in Barrett's esophagus: a preliminary study.

Abstract Background: The diagnostic advantage of methylene blue (MB) chromoendoscopy in Barrett's esophagus is unclear. Methods: Patients with columnar-lined esophagus (CLE) were enrolled into a prospective, randomized crossover trial of MB-directed biopsy versus conventional biopsy. Results: Forty-seven patients (19 long-segment CLE; 28 short-segment CLE) were enrolled and underwent MB-directed biopsy. Sensitivity and specificity of MB for specialized intestinal metaplasia were 53% and 51%, respectively. Sensitivity and specificity of MB for dysplasia were 51% and 48%, respectively. Thirty-five patients (15 long-segment CLE; 20 short-segment CLE) completed the crossover trial. Relative frequencies for specialized intestinal metaplasia were 73% and 71% from MB-directed and conventional biopsy specimens, respectively ( p = 0.73). Relative frequencies for dysplasia were 20% and 18% from MB-directed and conventional biopsy specimens, respectively ( p = 0.65). In patients with long-segment CLE, dysplasia was diagnosed in 10 patients with MB and 7 patients with conventional biopsy methods ( p = 0.25). The number of biopsy specimens per EGD was greater with MB, which may have influenced the diagnosis. Histologically, the grade of dysplasia was indefinite/low in nearly all of the dysplastic specimens. Conclusions: Results of MB-directed biopsy were similar to conventional biopsy in detecting specialized intestinal metaplasia and indefinite/low-grade dysplasia. MB was not useful in short-segment Barrett's esophagus. (Gastrointest Endosc 2001;54:294-301.)
Radiation treatment planning for head and neck cancer with PET

Radiotherapy plays an important role in the management of head and neck cancer. Intensity-modulated radiotherapy is a highly conformal radiation technique that allows delivery of high-dose of radiation to the tumor and high-risk areas while sparing the normal structure. PET scan is a useful tool in identifying the border of the tumor and small lymph nodes with metastatic disease. Future directions in dose escalation and the use of PET with new tracers other than 18F-fluoro-deoxy-D-glucose are discussed.
Normative Bias and Adaptive Challenges: A Relational Approach to Coalitional Psychology and a Critique of Terror Management Theory:

Adherence to ingroup ideology increases after exposure to death-related stimuli, a reaction that proponents of terror management theory (TMT) explain as a psychological defense against the uniquely human existential fear of death. We argue that existential concerns are not the relevant issue; rather, such concepts can be subsumed under a larger category of adaptive challenges that prime coalitional thinking. We suggest that increases in adherence to ingroup ideology in response to adaptive challenges are manifestations of normative mental representations emanating from psychological systems designed to enhance coordination and membership in social groups. In providing an alternative to TMT, we (1) explain why the theory is inconsistent with contemporary evolutionary biology, (2) demonstrate that mortality-salience does not have the unique evocative powers ascribed to it by TMT advocates, and (3) discuss our approach to coalitional psychology, a framework consistent with modern evolutionary theory and informed by a broad understanding of cultural variation, can be employed to help account for both the corpus of results in TMT research and the growing body of findings inconsistent with TMT's predictions.