bluuebunny/crossref_metadata_2025 huggingface dataset:
Myocardial Mechanics: Understanding and Applying Three‐Dimensional Speckle Tracking Echocardiography in Clinical Practice
Authors: Ammar Khawaja Afzal , Paterick Timothy E. , Khandheria Bijoy K. , Jan M. Fuad , Kramer Christopher , Umland Matt M. , Tercius Alix J. , Baratta Lisa , Tajik A. Jamil
Published: May 2012

Speckle tracking echocardiography (STE) is an emerging tool to characterize and quantify myocardial segmental and rotational mechanics. This literature review is aimed at clinical and academic cardiologists to provide: (1) a conceptual framework of STE to initiate understanding of myocardial mechanics; (2) evidence that three‐dimensional (3D) STE overcomes the problems of time‐consuming data acquisition and postprocessing seen with two‐dimensional STE; and (3) illustrative clinical cases with analysis of myocardial mechanics via 3D STE to show the incremental value of strain in clinical decision making.
National Study of Antibiotic Use in Emergency Department Visits for Pneumonia, 1993 Through 2008
Authors: Neuman Mark I. , Ting Sarah A. , Meydani Ahou , Mansbach Jonathan M. , Camargo Carlos A.
Published: May 2012

ACADEMIC EMERGENCY MEDICINE 2012; 19: 562–568 © 2012 by the Society for Academic Emergency Medicine

Objectives:  The Infectious Disease Society of America (IDSA) and American Thoracic Society (ATS) developed guidelines for the management of community‐acquired pneumonia (CAP); however, there are sparse data on actual rates of antibiotic use in the emergency department (ED) setting.

Methods:  Data were obtained from the National Hospital Ambulatory Medical Care Survey (NHAMCS) for ED visits during 1993 through 2008 for adults with a diagnosis of pneumonia.

Results:  During the study period there were an estimated 23,252,000 pneumonia visits, representing 1.8% of all ED visits. The visit rate for pneumonia during this 16‐year period may have increased (p trend = 0.055). Overall, 66% of adult patients with a primary diagnosis of pneumonia had documentation of an antibiotic administered while in the ED. There was an increase in antibiotic administration for adults with pneumonia from 1993 through 2008 (49% to 80%; p trend < 0.001). Specifically, there was an increase in use of macrolides from 1993 to 2006 (20% to 30%, p trend < 0.001) and a marked increase in use of quinolones from 0% to 39% from 1993 through 2008 (p trend < 0.001). Penicillin and cephalosporin use remained stable. Use of an antibiotic consistent with 2007 IDSA/ATS guidelines increased from 22% (95% confidence interval [CI] = 16% to 27%) of cases in 1993–1994 to 68% (95% CI = 63% to 73%) of cases in 2007–2008 (p trend < 0.001).

Conclusions:  ED visit rates for pneumonia increased slightly from 1993 through 2008. Although antibiotic administration in the ED has increased for adults with CAP, guideline‐concordant antibiotics may not be consistently administered.
Factors Associated With No or Delayed Linkage to Care in Newly Diagnosed Human Immunodeficiency Virus (HIV)‐1–Infected Patients Identified by Emergency Department–based Rapid HIV Screening Programs in Two Urban EDs
Authors: Rothman Richard E. , Kelen Gabor D. , Harvey Leah , Shahan Judy B. , Hairston Heather , Burah Avanthi , Moring‐Parris Daniel , Hsieh Yu‐Hsiang
Published: May 2012

ACADEMIC EMERGENCY MEDICINE 2012; 19: 497–503 © 2012 by the Society for Academic Emergency Medicine

Objectives:  The objective was to describe the proportions of successful linkage to care (LTC) and identify factors associated with LTC among newly diagnosed human immunodeficiency virus (HIV)‐positive patients, from two urban emergency department (ED) rapid HIV screening programs.

Methods:  This was a retrospective analysis of programmatic data from two established urban ED rapid HIV screening programs between November 2005 and October 2009. Trained HIV program assistants interviewed all patients tested to gather risk behavior data using a structured data collection instrument. Reactive results were confirmed by Western blot testing. Patients were provided with scheduled appointments at HIV specialty clinics at the institutions where they tested positive within 30 days of their ED visit. “Successful” LTC was defined as attendance at the HIV outpatient clinic within 30 days after HIV diagnosis, in accordance with the ED National HIV Testing Consortium metric. “Any” LTC was defined as attendance at the outpatient HIV clinic within 1 year of initial HIV diagnosis. Multivariate logistic regression was performed to determine factors associated with any LTC or successful LTC.

Results:  Of the 15,640 tests administered, 108 (0.7%) were newly identified HIV‐positive cases. Nearly half (47.2%) of the patients had been previously tested for HIV. Successful LTC occurred in 54% of cases; any LTC occurred in 83% of cases. In multivariate analysis, having public medical insurance and being self‐pay were negatively associated with successful LTC (odds ratio [OR] = 0.33, 95% confidence interval [CI] = 0.12 to 0.96; OR = 0.34, 95% CI = 0.13 to 0.89, respectively); being female and having previously tested for HIV was negatively associated with any LTC (OR = 0.30, 95% CI = 0.10 to 0.93; OR = 0.23, 95% CI = 0.07 to 0.77, respectively).

Conclusions:  In spite of dedicated resources for arranging LTC in the ED HIV testing programs, nearly 50% of patients did not have successful LTC (i.e., LTC occurred at >30 days), although >80% of patients were LTC within 1 year of initial diagnosis. Further evaluation of the barriers associated with successful LTC for those with public insurance and self‐pay is warranted.
Predicting Emergency Department Volume Using Forecasting Methods to Create a “Surge Response” for Noncrisis Events
Authors: Chase Valerie J. , Cohn Amy E. M. , Peterson Timothy A. , Lavieri Mariel S.
Published: May 2012

ACADEMIC EMERGENCY MEDICINE 2012; 19: 569–576 © 2012 by the Society for Academic Emergency Medicine

Objectives:  This study investigated whether emergency department (ED) variables could be used in mathematical models to predict a future surge in ED volume based on recent levels of use of physician capacity. The models may be used to guide decisions related to on‐call staffing in non–crisis‐related surges of patient volume.

Methods:  A retrospective analysis was conducted using information spanning July 2009 through June 2010 from a large urban teaching hospital with a Level I trauma center. A comparison of significance was used to assess the impact of multiple patient‐specific variables on the state of the ED. Physician capacity was modeled based on historical physician treatment capacity and productivity. Binary logistic regression analysis was used to determine the probability that the available physician capacity would be sufficient to treat all patients forecasted to arrive in the next time period. The prediction horizons used were 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 8 hours, and 12 hours. Five consecutive months of patient data from July 2010 through November 2010, similar to the data used to generate the models, was used to validate the models. Positive predictive values, Type I and Type II errors, and real‐time accuracy in predicting noncrisis surge events were used to evaluate the forecast accuracy of the models.

Results:  The ratio of new patients requiring treatment over total physician capacity (termed the care utilization ratio [CUR]) was deemed a robust predictor of the state of the ED (with a CUR greater than 1 indicating that the physician capacity would not be sufficient to treat all patients forecasted to arrive). Prediction intervals of 30 minutes, 8 hours, and 12 hours performed best of all models analyzed, with deviances of 1.000, 0.951, and 0.864, respectively. A 95% significance was used to validate the models against the July 2010 through November 2010 data set. Positive predictive values ranged from 0.738 to 0.872, true positives ranged from 74% to 94%, and true negatives ranged from 70% to 90% depending on the threshold used to determine the state of the ED with the 30‐minute prediction model.

Conclusions:  The CUR is a new and robust indicator of an ED system’s performance. The study was able to model the tradeoff of longer time to response versus shorter but more accurate predictions, by investigating different prediction intervals. Current practice would have been improved by using the proposed models and would have identified the surge in patient volume earlier on noncrisis days.
Prejudice in the Lives of Asian Americans
Authors: WEAVER CHARLES N.
Published: May 2012

Expressions of prejudice were compared between Asian American and Black, Hispanic, Jewish, and White respondents to social distance and stereotype items on 5 recent nationwide public opinion surveys. There was much prejudice toward Asian Americans. Their prejudice was greatest toward Blacks and Hispanics and least toward Jews and Whites. Among Asian American subgroups, prejudice toward Blacks, Hispanics, and Whites was greatest by Chinese Americans and Japanese Americans; and least by Filipino Americans and Asian Indian Americans. Suggestions are made for further research.
Influence of nanocoated calcium phosphate on two different types of implant surfaces in different bone environment: an animal study
Authors: Choi Jung‐Yoo , Jung Ui‐Won , Kim Chang‐Sung , Jung Sung‐Min , Lee In‐Seop , Choi Seong‐Ho
Published: May 2012

Objective

The purpose of this study was to evaluate the osseointegration of two different types of surfaces, smooth and roughened surface implants nanocoated with calcium phosphate (CAP) around different bone environment.

Materials and methods

Five male mongrel dogs were used in this study. The premolars and molars were extracted on both sides of the mandible. Eight weeks after extraction, implants were submerged on both sides of the mandible. On the left, CAP nanocoated roughened surface (RCAP) implants were installed whereas, the CAP nanocoated smooth surface (SCAP) implants were installed on the right side. The control group had no defect, on the other hand, three‐wall intrabony defects were surgically created adjacent to the implant in the experimental group. The dogs were sacrificed after 12 weeks.

Results

Histological and histomorphometrical analysis were performed with the specimen. The SCAP and RCAP implants showed good osseointegration with no statistical significance in the control group. Histologically, the SCAP group showed little resolution of the defect compared with the RCAP group. In the experimental groups, there was a significant difference in defect fill between SCAP and RCAP.

Conclusion

Within the limits of our study, it can be concluded that SCAP and RCAP implants show no difference in sufficient bone area whereas, CAP nanocoating on roughened implant surface may enhance osseointegration in deficient bone environment.
How sampling affects estimates of demographic parameters
Authors: Lesser Mark R. , Brewer Simon
Published: May 2012

Question

Demographic rates are often modelled using small data sets over short time frames. Here, we use fully sampled populations as a basis for testing how the intensity of two different sampling approaches (individual random‐tree andn‐tree distance plots) can affect estimates of growth parameters and the timing of population development. How do sampling method and intensity affect estimates of early stages of population growth?

Location

North‐centralWyoming,USA.

Methods

We used a data set in which every individual in each of four discrete ponderosa pine populations was mapped and aged. We calculated cumulative population growth and fitted it to a logistic regression model. Based on this model, we estimated population growth rate, first colonization, timing of population growth initiation, maximum growth rate and growth saturation. We conducted simulations for two sampling methods. First, individual trees were chosen at random, with different percentages of the full population being chosen. Second, we simulatedn‐tree distance plot sampling, where we changed the number of plots that were laid in each population. For each method and at each intensity, 10 000 simulation runs were performed. The simulation results were fitted to a logistic regression model. We then looked at the difference between the full and partially sampled population results to examine how lowering sampling intensity affected the results.

Results

Population growth rate was not significantly affected by sampling intensity except at low levels of sampling. However, first colonization and timing of population initiation were affected by sampling intensity. For both parameters, the individual random‐tree method produced more accurate results than then‐distance method as sampling intensity decreased.

Conclusions

Accurate estimation of population growth parameters is critical for both ecological understanding and resource management. Results are encouraging in that they indicate that moderate levels of sampling will reliably estimate population growth parameters. However, our results are specific to ponderosa pine and may not apply to other species with different life‐history characteristics. Our results also highlight the fact that population structure can play a major role in sampling accuracy and needs to be considered in choosing the appropriate method and intensity.
Different types of sub‐alpine grassland respond similarly to elevated nitrogen deposition in terms of productivity and sedge abundance
Authors: Bassin Seraina , Schalajda Juliane , Vogel Andreas , Suter Matthias
Published: May 2012

Question

Increasing emissions of reactive nitrogen (N) compounds threaten the composition of species‐rich communities even in remote alpine areas. In the few studies available from (sub‐)alpine grassland, N deposition altered species composition in favour of sedges, which are assumed to be less limited by phosphorus (P) compared to other species. Is the magnitude of the sedges' relative increase modified by availability of other nutrients, which is in turn influenced by site‐specific edaphic and climatic conditions?

Location

Swiss Central Alps.

Methods

We selected ten sub‐alpine sites that covered a broad range of communities and soil conditions, including both calcareous Seslerietum as well as acidic Nardetum pastures. As a model species, Carex sempervirens Vill. was present at each site. For two consecutive years, in addition to a control, two treatments were applied to the vegetation: (1) 50 kg·N·ha−1·yr−1 as NH4NO3 and (2) compound NPK fertilizer comprising the same amount of N. Total above‐ground biomass, fraction of all sedges, leaf length and leaf N, P and potassium (K) content of C. sempervirens were recorded and analysed for their responses to treatments and interaction with variables linked to productivity and nutrient availability (including soil water potential, pH and soil P).

Results

Biomass production was stimulated across all sites on average by 30% with elevated N deposition, and by 60% with NPK fertilizer application, revealing the sites to be similarly co‐limited by N and by P and K. Also across all sites, the fraction of sedges was increased on average 33% by N addition, but remained constant with NPK application, suggesting stronger P and/or K co‐limitation in non‐sedge species. N treatment effects were consistent in their direction but varied between sites; nevertheless this variation could not be explained by the measured edaphic or climatic factors. However, by trend, sedges benefited more from N fertilization on sites with higher pH, but benefited less on very dry sites.

Conclusion

Our findings reveal that the observed increase of sedges is a general response of sub‐alpine grassland to elevated N deposition and thus can be regarded as universal both for Seslerietum as well as Nardetum pastures.
Forest fire history, aspen and goat willow in a Fennoscandian old‐growth landscape: are current population structures a legacy of historical fires?
Authors: Lankia Heini , Wallenius Tuomo , Várkonyi Gergely , Kouki Jari , Snäll Tord
Published: May 2012

Questions

Is the current aspen or goat willow populations in boreal old‐growth forest a legacy of the historical fires?

Location

A middle‐boreal, old‐growth forest landscape with a large proportion of wetlands in eastern Finland.

Method

Forest fire history of a 2100‐ha area was reconstructed using fire scars, forest age estimates and the presence or absence of charred stumps and charcoal particles in the soil in 63 systematically located plots. Age and size structures of aspen and goat willow were studied in a subsample of 12 plots.

Results

During the past 400 yr, forest fires have been seven times more numerous in the study area than could be expected based on modern lightning fire statistics. The ages of mature aspens (average 177 and maximum 213 yr) and mature goat willows (average 111 and maximum 173 yr) were higher than earlier reported, strikingly so in goat willow. Aspen age structure clearly reflected the past fires. Most aspens originated from the beginning of the 19th century, during a period of frequent forest fires. The regeneration of aspen leading to mature trees has been very low since the cessation of forest fires in the late 19th century. In turn, goat willow has also regenerated in spite of the absence of fires.

Conclusions

The majority of the mature aspen trees were recruited at the time of the last fires, and there was a notable lack of middle‐aged trees. This relationship to fires was not valid for goat willow. The main reason for the lack of young aspen cohorts in aspen populations in Fennoscandian old‐growth stands is most likely the lack of forest fires. Small‐scale gap dynamics cannot offset the lack of large‐scale disturbances, such as forest fires, for the regeneration of aspen, possibly because of the prevailing herbivory and competitive effects. Hence, the population decline of aspen is likely to continue and to threaten a wealth of species specialized on aspen in boreal forests.
Functional trait state diversity of Andean forests in Venezuela changes with altitude
Authors: Duivenvoorden Joost F. , Cuello A Nidia L.
Published: May 2012

Question

It is presumed that environmental stress is more pronounced at higher altitudes in Andean forests due to lower rates of temperature‐constrained processes of growth, nutrient uptake and decomposition. Because community assembly theory predicts a low variation in viable traits under conditions of strong ecological filtering, we asked if the diversity in plant traits related to productivity and reproduction would decrease upslope.

Location

Guaramacal National Park in the Andes of Venezuela (9°05‐21′N, 70°‐20′W).

Methods

We studied altitudinal patterns in the number of trait states of seven categorical traits found among vascular plants (DBH ≥ 2.5 cm) in 35 0.1‐ha plots between 1330 and 2890 m. Information on plant traits was obtained from literature and herbaria. To test the altitudinal correlations, we permuted the plot‐to‐species matrix by randomly selecting species from the entire species pool (conserving the species richness and the species–abundance pattern in each plot), applying no restrictions and by creating plot‐wise null assemblages of species that most likely occurred near a particular plot. In addition, the altitudinal pattern of trait states was examined using fourth‐corner analysis.

Results

Both null model tests yielded similar results. The trait state diversity in fruit size decreased upslope. Plants with small fruits were mostly, but not exclusively, found at higher altitudes, whereas plants with large fruits occurred only at lower elevations. Leaf size showed more states at higher altitudes but this pattern disappeared when rare leaf size classes were down‐weighted. The upslope decrease in fruit size might be explained by the relatively low tree height of the upper montane rain forests, the increased selection for large seeds at high temperatures downslope, and the upslope decrease of large‐leaved taxa (in view of Corner's rule).

Conclusions

The functional diversity of important plant traits changed with altitude at Guaramacal. Altitudinal effects on plant trait responses should be controlled for in studies that monitor the degradation of functional diversity in Andean forests in relation to human influence.
The performance of Mediterranean subshrubs depends more on microsite than on regional climate conditions
Authors: Gazol Antonio , Julio Camarero J.
Published: May 2012

Question

To what extent do small‐scale biotic interactions and local variations determine the spatial pattern and plant performance of three Mediterranean subshrubs growing under contrasting climatic conditions?

Location

Three sites subjected to climatically contrasting conditions in Aragón (Javalambre, cold site; Bernués, mesic site; Monegros, xeric site), NE Spain.

Methods

The three species studied were Hormathophylla spinosa, Ononis fruticosa and Linum suffruticosum in the cold, mesic and xeric sites, respectively. Two transects (100 × 5 m) were located in each site, one in the upper part and another in the north‐oriented slope of a hill. All adult individuals located within each transect of each species were tagged, spatially located and their size measured (height and crown diameter). We also estimated visually the cover of other woody species around each subshrub individual to study inter‐specific interactions. We estimated the age of all subshrub individuals by counting annual rings in basal wood sections. To investigate the spatial patterns and plant performance of the three species we used spatial point pattern analyses and structural equation modelling.

Results

The density of individuals and the spatial pattern of the species varied greatly among and within sites. H. spinosa and L. suffruticosum showed higher variability in density among transects and a more aggregated spatial pattern than O. fruticosa. Similarly, the three subshrubs presented different architecture and performed differently in the two transects studied for each species. All three species presented higher growth rates in the upper part of the hill than in the north‐oriented slope. Inter‐specific interactions were more important than intra‐specific ones in determining the performance of the three subshrubs, and were more intense in the case of H. spinosa and L. suffruticosum than in the case of O. fruticosa.

Conclusions

Our results demonstrate that the spatial patterns of the three species studied varied within sites as a function of local environmental conditions. Moreover, plant–plant interactions can play an important role in explaining subshrub spatial patterns and performance in Mediterranean ecosystems. Inter‐ and intra‐specific interactions acting at local scales should be considered for understanding the responses of Mediterranean subshrubs to regional climate.
A Novel Nonsense Mutation in HSD17B3 Gene in a Tunisian Patient with Sexual Ambiguity
Authors: Ben Rhouma Bochra , Belguith Neila , Mnif Mouna Feki , Kamoun Thouraya , Charfi Nadia , Kamoun Mahdi , Abdelhedi Fatma , Hachicha Mongia , Kamoun Hassen , Abid Mohamed , Fakhfakh Faiza
Published: May 2012

Introduction

17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) isoenzyme is present almost exclusively in the testes and converts delta 4 androstenedione to testosterone. Mutations in the HSD17B3 gene cause HSD17B3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD).

Aim

This study aimed to present the clinical and biochemical features of a Tunisian patient who presented a sexual ambiguity orienting to HSD17B3 deficiency and to search for a mutation in the HSD17B3 gene by DNA sequencing.

Methods

Polymerase chain reaction (PCR) amplification and subsequent sequencing of all the coding exons of HSD17B3 gene were performed on genomic DNA from the patient, her family, and 50 controls.

Results

Genetic mutation analysis of the HSD17B3 gene revealed the presence of a novel homozygous nonsense mutation in the exon 9 (c.618 C > A) leading to the substitution p.C206X. The mutation p.C206X in the coding exons supports the hypothesis of HSD17B3 deficiency in our patient.

Conclusion

The patient described in this study represented a new case of a rare form of 46,XY DSD, associated to a novel gene mutation of HSD17B3 gene. The screening of this mutation is useful for confirming the diagnosis of HSD17B3 deficiency and for prenatal diagnosis.
Non‐alpha‐adrenergic effects on systemic vascular conductance during lower‐body negative pressure, static exercise and muscle metaboreflex activation
Authors: Kiviniemi A. M. , Frances M. F. , Rachinsky M. , Craen R. , Petrella R. J. , Huikuri H. V. , Tulppo M. P. , Shoemaker J. K.
Published: May 2012

Aim

This study tested the hypothesis that non‐α‐adrenergic mechanisms contribute to systemic vascular conductance (SVC) in a reflex‐specific manner during the sympathoexcitatory manoeuvres.

Methods

Twelve healthy subjects underwent lower‐body negative pressure (LBNP, −40 mmHg) as well as static handgrip exercise (HG, 20% of maximal force) followed by post‐exercise forearm circulatory occlusion (PECO, 5 min each) with and without α‐adrenergic blockade induced by phentolamine (PHE). Aortic blood flow, finger blood pressure and superficial femoral artery blood flow were measured to calculate cardiac output, SVC and leg vascular conductance (LVC) during the last minute of each intervention.

Results

Mean arterial pressure (MAP) decreased more during LBNP with PHE compared with saline (−7 ± 7 vs. −2 ± 5%, P = 0.016). PHE did not alter the MAP response to HG (+20 ± 12 and +24 ± 16%, respectively, for PHE and saline) but decreased the change in MAP during PECO (+12 ± 7 vs. +21 ± 14%, P = 0.005). The decrease in SVC and LVC with LBNP did not differ between saline and PHE trials (−13 ± 10 vs. −17 ± 10%, respectively, for SVC, P = 0.379). In contrast, the SVC response to HG increased from −9 ± 12 with saline to + 5 ± 15% with PHE (P = 0.002) and from −16 ± 15 with saline to +1 ± 16% with PHE during PECO (P = 0.003). LVC responses to HG or PECO were not different from saline with PHE.

Conclusions

Non‐α‐adrenergic vasoconstriction was present during LBNP. The systemic vasoconstriction during static exercise and isolated muscle metaboreflex activation, in the absence of leg vasoconstriction, was explained by an α‐adrenergic mechanism. Therefore, non‐α‐adrenergic vasoconstriction is more emphasized during baroreflex, but not metaboreflex‐mediated sympathetic activation.
A prospective study of PTSD following recovery from first‐episode psychosis: The threat from persecutors, voices, and patienthood
Authors: Brunet Kat , Birchwood Max , Upthegrove Rachel , Michail Maria , Ross Kerry
Published: May 2012

Objectives. Approximately one third of people with early psychosis report post‐traumatic symptoms, some of which are thought to arise from traumatic experiences associated with psychosis itself. This prospective study tested hypotheses based on retrospective findings that threat appraisals of voices, persecutors, or the new label of ‘mental health patient’ predict symptoms of post‐traumatic stress disorder (PTSD).

Methods. Appraisals of power and threat from voices and other persecutors and appraisals of the threat posed to identity by the diagnosis were assessed during the first acute phase of psychosis. Eighteen months later, PTSD symptom levels and diagnosis were established.

Design. Prospective.

Results. Of 39 participants who completed the follow‐up phase, 12 (31%) met criteria for PTSD diagnosis. Nineteen (49%) of the participants were still distressed by memories of their psychosis or the associated treatment. During the acute phase of psychosis, appraisals of threat from voices and persecutors were strongly associated with distress. With the exception of the perceived ability to cope with threat, none of these appraisals were predictive of subsequent post‐traumatic stress however. Similarly, only one appraisal of the diagnosis (loss of control) was predictive of PTSD.

Conclusion. It may be that retrospective studies have overestimated the influence of candidate appraisals in predicting PTSD. It might also be that assessments made during the acute phase of psychosis preceded a key phase of psychological processing that takes place during the immediate aftermath of the psychotic episode. A staged prospective design is required to uncover the true impact of psychosis on PTSD.
A Chemo-Elastoplastic Analysis of Anisotropic Swelling in an SnO2 Nanowire Under Lithiation
Authors: Yang B. , Irsa J. , He Y.-P. , Lundgren C. A. , Zhao Y.-P.
Published: May 2012

A parametric study is carried out to shed light on the elastoplastic behavior of a nanowire under lithiation. The Li-ion diffusivity is assumed to be significantly higher at near-saturation than at dilute concentration. It leads to the prediction of an Li-ion diffusion jam and consequently a topologically steep step moving along the wire. The analysis shows that the different plastic flow rates due to the different constraint conditions along the longitudinal and radial directions result in apparent anisotropic volume expansion. Either lower yield strength, smaller strain hardening ratio, or higher charging rate would cause greater swelling anisotropy. The numerical results are compared with the experimental observation of an SnO2 nanowire (Huang et al., 2011, “In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode,” Science, 330, pp. 1515–1520) to suggest its elastoplastic properties under lithiation.
The Influence of Friction Stir Welding Process Idealization on Residual Stress and Distortion Predictions for Future Airframe Assembly Simulations
Authors: McCune R. W. , Murphy A. , Price M. , Butterfield J.
Published: May 2012

The ability to accurately predict residual stresses and resultant distortions is a key product from process assembly simulations. Assembly processes necessarily consider large structural components potentially making simulations computationally expensive. The objective herein is to develop greater understanding of the influence of friction stir welding process idealization on the prediction of residual stress and distortion and thus determine the minimum required modeling fidelity for future airframe assembly simulations. The combined computational and experimental results highlight the importance of accurately representing the welding forging force and process speed. In addition, the results emphasize that increased CPU simulation times are associated with representing the tool torque, while there is potentially only local increase in prediction fidelity.
Signal detection and location‐dependent noise in cone‐beam computed tomography using the spatial definition of the Hotelling SNR
Authors: Brunner Claudia C. , Abboud Samir F. , Hoeschen Christoph , Kyprianou Iacovos S.
Published: May 2012

Purpose:

Quality assurance in computed tomography (CT) is commonly performed with the Fourier‐based modulation transfer function (MTF) and the noise variance, while more recently the noise power spectrum (NPS) has increased in popularity. The Fourier‐based methods make assumptions such as shift‐invariance and cyclostationarity. These assumptions are violated in real clinical systems and consequently are expected to result in systematic errors. A spatial approach, based on the object transfer matrix (T) and the covariance matrix (K) theory, does not require these assumptions and can provide a more general description of the imaging system. In this paper, the authors present an experimental methodology and data treatment for quality assessment of a lab cone‐beam CT system by comparing the spatial with the Fourier approach in 2D reconstructed slices.

Methods:

In order to have control over all experimental parameters and image reconstruction, a bench‐top flat‐panel‐based cone‐beam CT scanner and a cylindrical water‐filled poly(methyl methacrylate) (PMMA) phantom were used for the noise measurements. An aluminum foil inserted in the water phantom enabled the estimation of the line response function (LRF) with a limited number of assumptions. The authors evaluated the spatial blur, the noise and the signal‐to‐noise ratio (SNR) using the spatial approach as well as the Fourier‐based approach. In order to evaluate the degree of noise nonstationarity of their cone‐beam CT system, the authors evaluated both the local and global CT noise properties and compared them using both approaches.

Results:

For the laboratory cone‐beam CT, the location‐dependent noise evaluation showed that in addition to the noise variance, the NPS and covariance eigenvector symmetry depend on the location in the image. The estimated signal transfer was similar for both approaches. Unlike the Fourier approach which uses the same exponential wave function basis for both MTF and NPS, the eigenvectors ofT and K were significantly different.

Conclusions:

By using the eigenvectors of the noise and object transfer to characterize the system, the spatial approach provides additional information to the Fourier approach and is therefore an important tool for a thorough understanding of a CT system.
Evolutionary Diversity of the Mitochondrial Calcium Uniporter
Authors: Bick Alexander G. , Calvo Sarah E. , Mootha Vamsi K.
Published: May 2012

Phylogenetic analysis of the mitochondrial calcium transporter shows that it was a feature of early eukaryotes.
Warriors, Levelers, and the Role of Conflict in Human Social Evolution
Authors: Bowles Samuel
Published: May 2012

The origins of such varied features of contemporary life as the national state and the desire to uphold generous and civic social norms are to be found in a combination of conflict between groups and attenuation of both inequalities and conflicts within groups. In contrast to the adoption of a better tool or a more productive crop, which can be adopted by a single individual, a new institution works only if most people adopt it. This explains why collective action against those benefitting from the status quo at the expense of others, as well as conflict between groups governed by different norms and institutions, figures so prominently in our capacity to adapt to changing circumstances and to harness new knowledge for human benefit.
Modeling Armed Conflicts
Authors: Kress Moshe
Published: May 2012

Armed conflicts have been prevalent throughout history, in some cases having very great consequences. To win, one needs to understand the characteristics of an armed conflict and be prepared with resources and capabilities for responding to its specific challenges. An important tool for understanding these characteristics and challenges is a model—an abstraction of the field of conflict. Models have evolved through the years, addressing different conflict scenarios with varying techniques.
Life Without War
Authors: Fry Douglas P.
Published: May 2012

An emerging evolutionary perspective suggests that nature and human nature are less “red in tooth and claw” than generally acknowledged by a competition-based view of the biological world. War is not always present in human societies. Peace systems, defined as groups of neighboring societies that do not make war on each other, exist on different continents. A comparison of three peace systems—the Upper Xingu River basin tribes of Brazil, the Iroquois Confederacy of upper New York State, and the European Union—highlight six features hypothesized to be important in the creation and maintenance of intersocietal peace: (i) an overarching social identity, (ii) interconnections among subgroups, (iii) interdependence, (iv) nonwarring values, (v) symbolism and ceremonies that reinforce peace, and (vi) superordinate institutions for conflict management. The existence of peace systems demonstrates that it is possible to create social systems free of war.
How Hibernation Factors RMF, HPF, and YfiA Turn Off Protein Synthesis
Authors: Polikanov Yury S. , Blaha Gregor M. , Steitz Thomas A.
Published: May 2012

The Hibernating Ribosome

When bacteria enter stationary phase, their ribosomes are inactivated. In
Escherichia coli
, ribosome modulation factor (RMF) causes dimerization of the 70S ribosome and the dimer is stabilized by, hibernation promotion factor (HPF). Alternately, the stationary phase protein, YfiA, inactivates 70S ribosomes.

Polikanov
et al.

(p.
915
) present high-resolution structures of the
Thermus thermophilus
70S ribosome bound to each of these three factors. The structures suggest that RMF binding inhibits protein synthesis by preventing initial messenger RNA (mRNA) binding and that HPF and YfiA have overlapping binding sites and would both interfere with binding of mRNA, transfer RNA, and initiation factors.
Cost-Benefit Tradeoffs in Engineered
lac
Operons
Authors: Eames Matt , Kortemme Tanja
Published: May 2012

Accounting for
Lac

When
Escherichia coli
expresses the
lac
operon, it needs to balance the potential increase in growth rate conferred through having the encoded proteins (which help it to take up and metabolize lactose) with the potential reduction in growth rate because of the resources needed to express and fold the encoded proteins. To investigate these inherent tradeoffs,
Eames and Kortemme
(p.
911
) investigated the costs and benefits associated with the
lac
operon and surprisingly found that the main constraint on the system is not caused by the manufacture of the proteins themselves but by the lactose permease activity encoded by the
LacY
gene.
Water-Mediated Proton Hopping on an Iron Oxide Surface
Authors: Merte Lindsay R. , Peng Guowen , Bechstein Ralf , Rieboldt Felix , Farberow Carrie A. , Grabow Lars C. , Kudernatsch Wilhelmine , Wendt Stefan , Lægsgaard Erik , Mavrikakis Manos , Besenbacher Flemming
Published: May 2012

Water-Assisted Proton Diffusion

Proton diffusion on metal oxide surfaces can play an important role in many catalytic processes. The presence of water is thought to accelerate proton diffusion.

Merte
et al.

(p.
889
) used high-speed, high-resolution scanning tunneling microscopy to study proton diffusion on an iron oxide. On oxygen-terminated FeO monolayer films formed on Pt, molecular water accelerated proton diffusion. Density function theory calculations implicated a H
3
O
+
transition state in the diffusion process.
Conspecific Negative Density Dependence and Forest Diversity
Authors: Johnson Daniel J. , Beaulieu Wesley T. , Bever James D. , Clay Keith
Published: May 2012

Keep Your Distance

Conspecific negative density dependence (CNDD), whereby the abundance of a species is limited by negative interactions between individuals of the same species, is thought to have an important influence on the composition and dynamics of forest communities, but studies have generally been limited to few species and small areas.

Johnson
et al.

(p.
904
) analyzed CNDD in over 200,000 plots from a database of more than 3 million individuals of 151 species spanning 4 million square kilometers across forests in the eastern United States and found that the strength of CNDD strongly predicted the relative abundance of tree species. Because tree seedlings are unlikely to become established where conspecific adults are common, CNDD may provide a general mechanism maintaining diversity in forests.
Violence Tamed
A History of Violence
From the End of the Middle Ages to the Present

by Robert Muchembled; Jean Birrell, Translator

Polity, Cambridge, 2011. 383 pp. S79.95, £60, €72. ISBN 9780745647463. Paper, $29.95, £19.99, €24. ISBN 9780745647470.
Authors: Hechter Michael
Published: May 2012

Examining patterns of violence in Europe, Muchembled finds that brutality and homicide have declined from the 13th century to the present and considers explanations for that change.
Schooling Violence?
Educations in Ethnic Violence
Identity, Educational Bubbles, and Resource Mobilization

by Matthew Lange

Cambridge University Press, Cambridge, 2012. 254 pp. $90, £55. ISBN 9781107016293. Paper, $26.99, £16.99. ISBN 9781107602373.
Authors: Adida Claire L.
Published: May 2012

Challenging claims that education promotes tolerance and peace, Lange argues that it instead often---especially in settings with ethnic divisions, limited resources, and ineffective political institutions---contributes to violence.
Structures of Cage, Prism, and Book Isomers of Water Hexamer from Broadband Rotational Spectroscopy
Authors: Pérez Cristóbal , Muckle Matt T. , Zaleski Daniel P. , Seifert Nathan A. , Temelso Berhane , Shields George C. , Kisiel Zbigniew , Pate Brooks H.
Published: May 2012

Cage, Book, and Prism

The array of hydrogen bonds governing the extended structure of liquid water is so intricate that chemists have often sought to understand it by studying simpler clusters. Even so, it has been challenging to get a handle on the preferred arrangement adopted by just six water molecules. Interdependent theoretical and spectroscopic studies have narrowed down the lowest-energy hexamer structures to three isomers—respectively designated the cage, the book, and the prism—but their relative energies remain uncertain. Now,

Pérez
et al.

(p.
897
; see the Perspective by

Saykally and Wales

) have observed all three isomers in a single experiment, using Fourier transform microwave spectroscopy, and were able to establish definitively their energy ordering.
Pinning Down the Water Hexamer
Authors: Saykally Richard J. , Wales David J.
Published: May 2012

An experimental study resolves a long-standing controversy about isomeric forms of the water hexamer.
Room for Just One Photon
Authors: Grangier Philippe
Published: May 2012

Ensembles of cold atoms excited up to Rydberg states can be used to manipulate and control interactions between single photons.
Active Site of an Industrial Catalyst
Authors: Greeley Jeffrey P.
Published: May 2012

Surface steps caused by stacking faults or twin boundaries in copper nanoparticles are key to the activity of the methanol synthesis catalyst.
Ancient Sensor for Ancient Drug
Authors: Shaw Reuben J. , Cantley Lewis C.
Published: May 2012

A common drug has an unexpected effect on a metabolic enzyme that stimulates fat utilization.
Preventing Mass Violence
Authors: Hamburg David
Published: May 2012

Our Species has a long history of distrusting strangers, despising outgroups, and fighting each other in many ways and many places, using the most damaging technology available at the time. This special issue of
Science
on Human Conflict illustrates the role of the scientific community in achieving deep insights into the evolutionary history of human conflict and, most importantly, demonstrates how science can help to clarify the major factors that affect the risk of mass violence (see p. 818). Such understandings are critical to develop education that decreases the probability of conflicts, to provide early and active help to countries having trouble with intergroup relations, to help foster equitable democratic development, to protect and promote human rights, and to place constraints on weaponry.
Robert R. Sokal (1926–2012)
Authors: Futuyma Douglas J.
Published: May 2012

An ecologist and evolutionary biologist brought a quantitative approach to classification through statistics and morphometric analysis.
FDA Panel Recommends Anti-HIV Drug for Prevention
Authors: Cohen Jon
Published: May 2012

On 10 May, the Antiviral Drugs Advisory Committee of the U.S. Food and Drug Administration debated whether an anti-HIV drug should receive approval as a preventive for uninfected people.
Coalition Begins Push for U.S. Schools to Adopt Voluntary Science Standards
Authors: Mervis Jeffrey
Published: May 2012

Stephen Pruitt is trying to coax states to adopt a set of standards for teaching science in their elementary and secondary schools. He offers a tutorial on the new standards in an interview with
Science
.
Near Eastern Archaeology Works to Dig Out of a Crisis
Authors: Lawler Andrew
Published: May 2012

In the wake of the Arab Spring, archaeologists in the Near East are locked in a struggle for the survival of their field.
Parsing Terrorism
Authors: Marshall Eliot
Published: May 2012

Terrorism research has expanded rapidly since 9/11, shifting its focus from human pathology to the analysis of how rational people interact with violent groups.
Fighting Rituals
Authors: Pennisi Elizabeth
Published: May 2012

Humans aren't the only species to engage in ritual combat. Honeypot ants of the U.S. Southwest stage elaborate, ritualistic face-offs against nearby nests that can involve hundreds of ants and last for days.
From War to Peace
Authors: Pennisi Elizabeth
Published: May 2012

The ability to reconcile differences after a spat was once considered a uniquely human trait, but researchers have since observed it in more than 30 primate species—and even among birds.
Analysis of Variola and Vaccinia Virus Neutralization Assays for Smallpox Vaccines
Authors: Hughes Christine M. , Newman Frances K. , Davidson Whitni B. , Olson Victoria A. , Smith Scott K. , Holman Robert C. , Yan Lihan , Frey Sharon E. , Belshe Robert B. , Karem Kevin L. , Damon Inger K.
Published: May 2012

Possible smallpox reemergence drives research for third-generation vaccines that effectively neutralize variola virus. A comparison of neutralization assays using different substrates, variola and vaccinia (Dryvax and modified vaccinia Ankara [MVA]), showed significantly different 90% neutralization titers; Dryvax underestimated while MVA overestimated variola neutralization. Third-generation vaccines may rely upon neutralization as a correlate of protection.
Molecular Epidemiologic Analysis and Antimicrobial Resistance of Helicobacter cinaedi Isolated from Seven Hospitals in Japan
Authors: Rimbara Emiko , Mori Shigetarou , Matsui Mari , Suzuki Satowa , Wachino Jun-ichi , Kawamura Yoshiaki , Shen Zeli , Fox James G. , Shibayama Keigo
Published: May 2012

Helicobacter cinaedi
colonizes the colons of human and animals and can cause colitis, cellulitis, and sepsis in humans, with infections in immunocompromised patients being increasingly recognized. However, methods for analyzing the molecular epidemiology of
H. cinaedi
are not yet established. A genotyping method involving multilocus sequence typing (MLST) was developed and used to analyze 50
H. cinaedi
isolates from Japanese hospitals in addition to 6 reference strains. Pulsed-field gel electrophoresis (PFGE) results were also compared with the MLST results. Based on the genomic information from strain CCUG18818, 21 housekeeping genes were selected as candidates for MLST and were observed to have high homology (96.5 to 100%) between isolates. Following a comparison of the 21 housekeeping genes from 8
H. cinaedi
isolates, 7 genes were chosen for MLST, revealing 14 sequence types (STs). The isolates from 3 hospitals belonged to the same STs, but the isolates from the other 4 hospitals belonged to different STs. Isolates belonging to ST6 were analyzed by PFGE and showed similar, but not identical, patterns between isolates. Isolates belonging to ST9, ST10, and ST11, which belonged to the same clonal complex, had the same pattern. All isolates were found to contain mutations in GyrA and the 23S rRNA gene that confer ciprofloxacin and clarithromycin resistance, respectively, in
H. cinaedi
. These results raise concerns about the increase in
H. cinaedi
isolates resistant to clarithromycin and ciprofloxacin in Japan.
The Structure of an Archaeal Viral Integrase Reveals an Evolutionarily Conserved Catalytic Core yet Supports a Mechanism of DNA Cleavage in
trans
Authors: Eilers Brian J. , Young Mark J. , Lawrence C. Martin
Published: May 2012

The first structure of a catalytic domain from a hyperthermophilic archaeal viral integrase reveals a minimal fold similar to that of bacterial HP1 integrase and defines structural elements conserved across three domains of life. However, structural superposition on bacterial Holliday junction complexes and similarities in the C-terminal tail with that of eukaryotic Flp suggest that the catalytic tyrosine and an additional active-site lysine are delivered to neighboring subunits in
trans
. An intramolecular disulfide bond contributes significant thermostability
in vitro
.