bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of Spectral Ultraviolet Doses by Different Types of Overcast Cloudiness and Atmospheric Aerosol
Authors: Aun Margit , Eerme Kalju , Ansko Ilmar , Veismann Uno , Lätt Silver
Published: January 2011

Wavelength‐dependent attenuation of ground‐level ultraviolet (UV) dose by different cloud and aerosol situations at the Tartu Observatory site (58°15′ N, 26°28′ E, 70 m a.s.l) is under scrutiny. The spectra at wavelengths ranging below 400 nm have been recorded by the simple Avantes, Inc. array spectrometer AvaSpec‐256 in 2004–2009. The spectral information was supported by the conventional broadband solar irradiance and by the necessary meteorological data. The average cloud modification factor (CMF) on overcast days from May to August has been quite low, 0.36 in UVA and 0.35 in UVB. In the UVA range, the reduction of the daily dose with increasing noon solar zenith angle (SZA) from 35–50° to 65–80° in overcast days has been about 20% more than in clear days, while in the UVB range it was 45% larger. No clear difference in the influence of SZA on CMF between low level (St, Ns) and medium level (As, Ac) overcast cloudiness has been found. The aerosol attenuation during large aerosol optical depth (AOD) episode has been comparable with that of medium level clouds with the wavelength dependency in the UVA range different from that of clouds.
Effects of Endosomal Photodamage on Membrane Recycling and Endocytosis
Authors: Andrzejak Michelle , Santiago Marie , Kessel David
Published: January 2011

The flux of receptor‐independent endocytosis can be estimated by addition of wortmannin to cell cultures. Membrane influx is unaffected but traffic out of late endosomes is impaired, resulting in a substantial enlargement of these organelles. Using the 1c1c7 murine hepatoma, we investigated the effect of endosomal photodamage on this endocytic pathway. We previously reported that photodamage catalyzed by the lysosomal photosensitizer NPe6 prevented wortmannin‐induced endosomal swelling, indicating an earlier block in the process. In this study, we show that endosomal photodamage, initiated by photodamage from an asymmetrically substituted porphine or a phthalocyanine also prevents wortmannin‐induced endosomal swelling, even when the photodynamic therapy (PDT) dose is insufficient to cause endosomal disruption. As the PDT dose is increased, endosomal breakage occurs, as does apoptosis and cell death. Very high PDT doses result in necrosis. We propose that photodamage to endosomes results in alterations in the endosomal structure such that influx of new material is inhibited and receptor‐independent endocytosis is prevented. In an additional series of studies, we found that the swollen late endosomes induced by wortmannin are unable to retain previously accumulated fluorescent probes or photosensitizers.
The Reaction Process of Firefly Bioluminescence Triggered by Photolysis of Caged‐ATP
Authors: Kageyama Takeshi , Tanaka Masatoshi , Sekiya Takao , Ohno Shin‐Ya , Wada Naohisa
Published: January 2011

The reaction process of firefly bioluminescence was studied by photolyzing caged‐ATP to adenosine triphosphate (ATP) within 100 ms. The intensity of luminescence increases markedly to reach a maximum within 1 s, maintains almost the same intensity up to 5 s and then decays monotonically. The rise γ1 and decay γ2 rate constants were determined to be about 5 s−1 and 1 × 10−2 s−1, respectively, so as to phenomenologically fit the time course. A second luminescence peak appears after around 350 s. The dependence of the rate constants on the concentrations of reactants and a viscous reagent revealed that two kinds of reaction contribute the observed time course: (1) an intrinsic reaction by ATP photolyzed from caged‐ATP that is already trapped in luciferase; and (2) a diffusion‐controlled reaction by free ATP in the buffer solution outside luciferase. Numerical analysis based on reaction kinetics related γ1 and γ2 to the rate constants of a three‐step reaction model, and accurately described the effects of concentration of reactants and a viscous reagent on the time courses of bioluminescence. Thus, it has been clearly concluded that the binding mode of caged‐ATP at the catalytic center of luciferase is very different from that of ATP.
What's worrying young Australians and where do they go for advice and support? Policy and practice implications for their well‐being
Authors: Hampshire Anne , Di Nicola Kathryn
Published: January 2011

Aim: The Mission Australia annual National Survey of Young Australians aims to generate insights into what young people think on a range of issues, including what they value, what issues are of concern to them, and where they go for advice and support.

Methods: A two‐page opt‐in questionnaire was distributed to a very broad range of organisations across Australia, and was available in both an online and paper‐based format. Responses to the survey were anonymous. Respondents were asked to rank items from the lists provided, and results are reported on the basis of items ranked one, two or three by respondents. Responses were disaggregated by age, gender, cultural background and living arrangements.

Results: Close to 48 000 young people participated in the 2009 survey, and the data confirms the importance of relationships to young people, as well as the diversity of concerns they may have, including drugs, suicide, mental health and body image. While concerns tended to vary with age and to some extent gender, what is valued by young people tends to be consistent across age and genders, namely family and friends.

Conclusions: Implications for policy making and service delivery are drawn with a focus on the issues of relationships, drugs and mental health. In particular, the need for early intervention, evidence‐based drug education programs, and initiatives that support those closest to young people, to assist them when they have concerns, are highlighted.
Navigating complex lives: a longitudinal, comparative perspective on young people's trajectories
Authors: Wyn Johanna , Andres Lesley
Published: January 2011

Background: Drawing on a sociological analysis that brings the prevailing social and economic policies into the frame of this analysis, this article focuses on the relationship between the social conditions faced by young people in the 1990s and early 2000s, the opportunities and constraints that these conditions presented to them, and patterns of mental health.

Method: The article presents an analysis of selected data from two longitudinal cohort studies. One is the Paths on Life's Way cohort study by Andres, based in British Columbia, Canada, and the other is the Life‐Patterns cohort by Wyn, based in Victoria, Australia. These cohort studies have tracked the lives of young people who entered the labour market in the early 1990s. The longitudinal analysis is based on the data available for 733 participants in the Canadian study in 2003, and 625 participants in the Australian study in 2004, which remains representative of the larger original samples. The data were collected through a mixed‐method approach of surveys and interviews. As part of the study, education and employment policies in Australia and Canada during the 1990 s were also analysed.

Results: The data reveal that it took 14 years from the time of leaving secondary school for the majority of Australians and Canadians to find a degree of employment security. Young Australians had lower rates of marriage and fertility, and assessed their mental health as being worse than their Canadian peers. Education and labour market policies aimed to increase human capital to ensure global competitiveness and to increase the flexibility of labour for employers.

Conclusion: Social policies matter. In both countries, the creation of higher levels of human capital through increasing young people's participation in education, combined with labour market policies that increased job uncertainty and labour market precariousness meant that young people found it difficult to achieve their goals of modest affluence and security. The policies had an impact on young people's marriage rates and fertility, particularly for the Australians. These social conditions also had the effect of increasing young people's assessments of their mental health as poor. Greater attention needs to be paid to the impact of social policies on areas that lie outside their immediate domain. Addressing young people's mental health requires an awareness of the inter‐connections across policy areas, and the recognition that mental health is an outcome of social conditions.
Promoting youth mental health: priorities for policy from an Australian perspective
Authors: Rickwood Debra J.
Published: January 2011

Aim: This paper considers the priorities for policy to promote youth mental health in Australia. The Ottawa Charter is applied as a conceptual framework to determine current strengths and future priorities across the entire spectrum of interventions for mental health promotion.

Methods: The five platforms of the Ottawa Charter are used to categorize some of the major initiatives that promote youth mental health. Areas of strength and major gaps within each platform are identified.

Results: Australia was shown to be at the forefront of many youth mental health promotion initiatives, particularly in the service reorientation and personal skills platforms of the Ottawa Charter.

Conclusions: While significant progress has been made in some areas of youth mental health promotion, areas of critical need for policy focus were: oversight of all public policies for their impact on youth mental health; more supportive environments for youth and better interconnection with mental health care; community action to support the youth voice; investment in resources for parents and families; ensuring quality inreach and outreach to provide young people with positive mental health messages and improve mental health literacy; and embedding and expanding effective innovations in youth mental health services reorientation.
Evaluating population‐level interventions for young people's mental health: challenges and opportunities
Authors: Sawyer Michael Gifford , Borojevic Nina , Lynch John
Published: January 2011

Aim: To identify key issues relevant to the delivery and evaluation of population‐level mental health interventions for children and adolescents.

Methods: The benefits and limitations of clinical, targeted and universal interventions were initially reviewed. Subsequently, experience gained in evaluations of targeted and universal interventions was utilized to identify key challenges that must be addressed by researchers responsible for evaluating population‐level interventions and potential solutions to these challenges.

Results: To be effective, population‐level interventions must engage large numbers of individuals in community or regional areas. Successfully evaluating population‐level interventions delivered in routine services requires a clear agreement about outcomes, use of strong research methodologies, and the availability of adequate research funding. Sustaining service‐research partnerships over the several‐year life of typical population interventions requires careful attention to these issues. Electronic databases with the capacity to efficiently collect, store and allow retrieval of large amounts of data in electronic format are also an essential component of population‐level interventions. Finally, research leaders need high‐quality administrative skills to manage research teams responsible for evaluating large‐scale population‐level interventions delivered at a regional or national level.

Conclusion: Population‐level interventions have the potential to play an important role in reducing the incidence and prevalence of mental health problems experienced by young people in the community. However, if they are to achieve their full effectiveness, ongoing evaluations are needed.
Young people at ultra high risk for psychosis: a research update
Authors: Yung Alison R. , Nelson Barnaby
Published: January 2011

Aim: Over the last fifteen years attempts have been made to prospectively identify individuals in the prodromal phase of schizophrenia and other psychotic disorders. The ‘ultra high risk’ approach, based on a combination of known trait and state risk factors, has been the main strategy used. The validation of the ultra high risk criteria led to a series of intervention studies in this population. The aim of this paper is to provide an overview of ultra high risk research.

Method: We review studies in this area, focusing on intervention research. Intervention studies have included the use of low dose antipsychotic medication, cognitive therapy, and omega‐3 fatty acids.

Results: The evidence for specific intervention strategies for this population is moderate and requires replication with larger samples.

Conclusion: Recently, it has been proposed to include an adaption of the ultra high risk criteria in the next version of the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition). This has raised some controversy in the field. The authors conclude that it would be premature to include the Risk Syndrome in the Diagnostic and Statistical Manual of Mental Disorders at this stage.
Transcriptional response of methanogen mcrA genes to oxygen exposure of rice field soil
Authors: Yuan Yanli , Conrad Ralf , Lu Yahai
Published: January 2011

Methane production in paddy soil is substantially suppressed after even a brief exposure of soil to oxygen. We hypothesized that the strong response of methanogen activity is reflected in the transcription of functional genes rather than in the composition of the community of methanogens. Therefore, we determined the community composition and the transcriptional response of methanogens in a rice field soil by targeting the mcrA gene (encoding the α subunit of methyl‐coenzyme M reductase). Transcription of mcrA genes measured by quantitative PCR decreased by an order of magnitude after brief exposure to O2. Terminal restriction fragment length polymorphism of mcrA genes and gene transcripts showed that although the community structure of methanogens did not change, the composition of transcripts dramatically responded to O2 exposure. In the beginning, transcripts of Methanocellales were the relatively most abundant, indicating resistance of these hydrogenotrophic methanogens against O2 stress. Later on, mcrA transcripts of acetoclastic methanogens became relatively more abundant coinciding with the turnover of acetate. The transcription of Methanosarcinaceae was relatively greater when acetate accumulated while Methanosaetaceae became more active when acetate concentrations decreased. In the presence of methyl fluoride, a specific inhibitor of acetoclastic methanogenesis, mcrA transcription by Methanosaetaceae was greatly suppressed while that of Methanosarcinaceae was less affected. Our study showed that in contrast to constant community structure as revealed by DNA‐based fingerprinting the transcription of functional mcrA genes strongly responded to O2 stress and the presence of inhibitor CH3F. The response patterns reflected the genomic and physiological traits of individual methanogens.
Staphylococcus aureus virulence and metabolism are dramatically affected by Lactococcus lactis in cheese matrix
Authors: Cretenet Marina , Nouaille Sébastien , Thouin Jennifer , Rault Lucie , Stenz Ludwig , François Patrice , Hennekinne Jacques‐Antoine , Piot Michel , Maillard Marie Bernadette , Fauquant Jacques , Loubière Pascal , Le Loir Yves , Even Sergine
Published: January 2011

In complex environments such as cheeses, the lack of relevant information on the physiology and virulence expression of pathogenic bacteria and the impact of endogenous microbiota has hindered progress in risk assessment and control. Here, we investigated the behaviour of Staphylococcus aureus, a major foodborne pathogen, in a cheese matrix, either alone or in the presence of Lactococcus lactis, as a dominant species of cheese ecosystems. The dynamics of S. aureus was explored in situ by coupling a microbiological and, for the first time, a transcriptomic approach. Lactococcus lactis affected the carbohydrate and nitrogen metabolisms and the stress response of S. aureus by acidifying, proteolysing and decreasing the redox potential of the cheese matrix. Enterotoxin expression was positively or negatively modulated by both L. lactis and the cheese matrix itself, depending on the enterotoxin type. Among the main enterotoxins involved in staphylococcal food poisoning, sea expression was slightly favoured in the presence of L. lactis, whereas a strong repression of sec4 was observed in cheese matrix, even in the absence of L. lactis, and correlated with a reduced saeRS expression. Remarkably, the agr system was downregulated by the presence of L. lactis, in part because of the decrease in pH. This study highlights the intimate link between environment, metabolism and virulence, as illustrated by the influence of the cheese matrix context, including the presence of L. lactis, on two major virulence regulators, the agr system and saeRS.
The influences of course effort, mastery and performance goals, grade expectancies, and earned course grades on student ratings of course satisfaction
Authors: Svanum Soren , Aigner Carrie
Published: January 2011

Background.  The positive relation between course grades and student ratings of course satisfaction is well established but controversy continues concerning the magnitude, interpretation, and implications of this association.

Aims.  This study examined the within course relations of a set of variables often implicated as potential contributors to the grade‐student rating relation.

Sample.  Two‐hundred and twenty students enrolled in an internet‐based university course.

Method.  Measures of course mastery and performance goals, expected grades, course effort, cumulative GPA, and final course grade were prospectively collected. The dependent variable was a global measure of course satisfaction obtained at the end of the semester.

Results.  A path model fit the data very well and all study variables directly or indirectly predicted course satisfaction. Grades had a moderately strong effect, half of which was independent of other model variables. Adjusting for all model variables, students high on mastery course goals evaluated the course more positively whereas students high on performance goals provided less favourable evaluations.

Conclusions.  Students can assess the same course and instructor in different ways depending upon such factors as their degree of success, their motivations for taking the course, and the amount of effort invested. Course satisfaction, then, can be substantially influenced by factors loosely or unrelated to course or teacher effectiveness.
The cognitive underpinnings of emerging mathematical skills: Executive functioning, patterns, numeracy, and arithmetic
Authors: Lee Kerry , Ng Swee Fong , Pe Madeline Lee , Ang Su Yin , Hasshim Muhammad Nabil Azhar Mohd , Bull Rebecca
Published: January 2011

Background: Exposure to mathematical pattern tasks is often deemed important for developing children's algebraic thinking skills. Yet, there is a dearth of evidence on the cognitive underpinnings of pattern tasks and how early competencies on these tasks are related to later development.

Aims: We examined the domain‐specific and domain‐general determinants of performances on pattern tasks by using (a) a standardized test of numerical and arithmetic proficiency and (b) measures of executive functioning, respectively.

Sample: Participants were 163 6‐year‐olds enrolled in primary schools that typically serve families from low to middle socioeconomic backgrounds.

Method: Children were administered a battery of executive functioning (inhibitory, switching, updating), numerical and arithmetic proficiency (the Numerical Operations task from the Wechsler Individual Achievement Test‐II), and three types of pattern tasks.

Results: Contrary to findings from the adult literature, we found all the executive functioning measures coalesced into two factors: updating and an inhibition/switch factor. Only the updating factor predicted performances on the pattern tasks. Although performance on the pattern tasks were correlated with numerical and arithmetic proficiency, findings from structural equation modelling showed that there were no direct or independent relationships between them.

Conclusions: The findings suggest that the bivariate relationships between pattern, numeracy, and arithmetic tasks are likely due to their shared demands on updating resources. Unlike older children, these findings suggest that for 6‐year‐olds, better numerical and arithmetic proficiency, without accompanying advantages in updating capacities, will no more likely lead to better performance on the pattern tasks.
Correcting an analysis of variance for clustering
Authors: Hedges Larry V. , Rhoads Christopher H.
Published: January 2011

A great deal of educational and social data arises from cluster sampling designs where clusters involve schools, classrooms, or communities. A mistake that is sometimes encountered in the analysis of such data is to ignore the effect of clustering and analyse the data as if it were based on a simple random sample. This typically leads to an overstatement of the precision of results and too liberal conclusions about precision and statistical significance of mean differences. This paper gives simple corrections to the test statistics that would be computed in an analysis of variance if clustering were (incorrectly) ignored. The corrections are multiplicative factors depending on the total sample size, the cluster size, and the intraclass correlation structure. For example, the corrected F statistic has Fisher's F distribution with reduced degrees of freedom. The corrected statistic reduces to the F statistic computed by ignoring clustering when the intraclass correlations are zero. It reduces to the F statistic computed using cluster means when the intraclass correlations are unity, and it is in between otherwise. A similar adjustment to the usual statistic for testing a linear contrast among group means is described.
Social identity, peer group rejection, and young children's reactive, displaced, and proactive aggression
Authors: Nesdale Drew , Duffy Amanda
Published: January 2011

The effects of peer group rejection on 7‐ and 9‐year‐old children's (N= 192) reactive, displaced, and proactive aggression were examined in a group simulation study. Children were assigned membership in a pretend social group for a drawing competition and were then rejected or accepted by their group. Their direct and indirect aggressive intentions towards either the ingroup or outgroup were assessed. Analysis of their aggressive intentions revealed enhanced indirect aggression but less direct aggression. Peer group rejection, in comparison with acceptance, instigated reactive aggression towards the ingroup, and displaced reactive aggression towards the outgroup. Accepted children displayed proactive aggression towards the outgroup but not the ingroup. The implications of the findings for peer group rejection and aggression research are discussed.
Developmental changes in the engagement of episodic retrieval processes and their relationship with working memory during the period of middle childhood
Authors: Rhodes Sinéad M. , Murphy Derek , Hancock Peter J. B.
Published: January 2011

We examined the development of children's engagement of the episodic retrieval processes of recollection and familiarity and their relationship with working memory (WM). Ninety‐six children (24 in four groups aged 8, 9, 10, and 11 years) and 24 adults performed an episodic memory (EM) task involving old/new, remember/know (R/K), and source memory judgements and numerous WM tasks that assessed verbal and spatial components of WM and delayed short‐term memory (STM). Developmental changes were observed in EM with younger children (8‐, 9‐, 10‐year‐olds) making fewer remember responses than 11‐year‐olds and adults while 11‐year‐olds did not differ from adults. Only children aged 10 years plus showed a relationship between EM and WM. EM was related to verbal executive WM in 10‐ and 11‐year‐old children suggesting that children at this stage use verbal strategies to aid EM. In contrast, EM was related to spatial executive WM in adults. The engagement of episodic retrieval processes appears to be selectively related to executive components of verbal and spatial WM, the pattern of which differs in children and adults.
Variability and standardized test profiles in typically developing children and children with Williams Syndrome
Authors: Van Herwegen Jo , Rundblad Gabriella , Davelaar Eddy J. , Annaz Dagmara
Published: January 2011

Williams Syndrome (WS) is a developmental disorder, which due to its specific cognitive profile, has been of interest to multidisciplinary research in order to study the pathways between cognition, brain, and genes. Previous studies investigating individual performance on cognitive tasks have reported large variability within the WS cognitive profile, which has encouraged the investigation of WS subgroups. The current study compared the variability in performance scores on five verbal and non‐verbal standardized tests in 33 children with WS and in 33 typically developing (TD) children of a similar chronological age (CA). In contrast to previous studies, the current study did not find significant differences in variability in performance on British Picture Vocabulary scale, Test Reception of Grammar and Digit span Forward between WS and TD groups when CA was controlled for. However, there was significantly less variability in younger WS participants for performance scores on Pattern Construction compared to the TD group. In light of these results, methodological issues and the importance of taking CA into account in analyses will be discussed.
Heat Transfer From Freely Suspended Bimaterial Microcantilevers
Authors: Narayanaswamy Arvind , Gu Ning
Published: January 2011

Bimaterial atomic force microscope cantilevers have been used extensively over the last 15 years as physical, chemical, and biological sensors. As a thermal sensor, the static deflection of bimaterial cantilevers, due to the mismatch of the coefficient of thermal expansion between the two materials, has been used to measure temperature changes as small as 10−6 K, heat transfer rate as small as 40 pW, and energy changes as small as 10 fJ. Bimaterial cantilevers have also been used to measure “heat transfer-distance” curves—a heat transfer analogy of the force-distance curves obtained using atomic force microscopes. In this work, we concentrate on the characterization of heat transfer from the microcantilever. The thermomechanical response of a bimaterial cantilever is used to determine the (1) thermal conductance of a bimaterial cantilever, and (2) overall thermal conductance from the cantilever to the ambient. The thermal conductance of a rectangular gold coated silicon nitride cantilever is Gc=4.09±0.04 μW K−1. The overall thermal conductance from the cantilever to the ambient (at atmospheric pressure) is Ga=55.05±0.69 μW K−1. The effective heat transfer coefficient from the cantilever to the ambient (at atmospheric pressure) is determined to be ≈3400 W m−2 K−1.
Resonance of Natural Convection Inside a Bidisperse Porous Medium Enclosure
Authors: Narasimhan Arunn , Reddy B. V. K.
Published: January 2011

An enclosure filled with blocks made of a microscale porous medium, separated by macrosize pores, can be treated as a bidisperse porous medium (BDPM) enclosure. This study investigates natural convection resonance inside such a BDPM enclosure subjected to time-periodic heat flux at a side wall, with the opposite wall kept isothermal while the top and bottom walls are adiabatic. The BDPM enclosure is made from uniformly spaced, disconnected, square, porous blocks that form the microporous medium saturated with a fluid of Pr=0.7. For Rayleigh numbers, Ra=108 and 107, the pulsating wall heat flux is varied over a frequency range of 0.01≤f≤0.1, and the bidispersion effect is induced by varying both the internal (micropore) Darcy number (DaI) and external (macropore) Darcy number DaE. Natural convection resonance is observed in the BDPM enclosure and the resonance heating frequency fr increases with Ra, DaI, and DaE. However, fr of the BDPM enclosure is always less than that of the corresponding clear fluid enclosure limit (at DaI→∞). Predictions of fr using a modified scale analysis incorporating BDPM effects agree well with that arrived by numerical methods.
Efficiency Comparison Between Circular and Semicircular Fins Circumscribing Circular Pipes
Authors: Chakraborty R. , Sirkar A.
Published: January 2011

A new design of fin has been conceived, which is in the shape of a semicircular strip. A step-by-step straightforward detailed derivation of the governing equations for two-dimensional temperature distribution in a semicircular fin has been presented, assuming a third degree polynomial. Numerical results are presented to illustrate the effects of pipe size and the number of semicircular fins on the thermal performance of the fin. It has been shown mathematically that the efficiency of a semicircular fin can be greater than that of a circular fin, having same total volume of fin material when employed over the circumference of a circular pipe.
Thermal Design Criteria for Extraordinary Performance of Devices Cooled by Microchannel Heat Sink
Authors: Farnam Dylan , Sammakia Bahgat , Ghose Kanad
Published: January 2011

Increasing power dissipation in microprocessors and other devices is leading to the consideration of more capable thermal solutions than the traditional air-cooled fin heat sinks. Microchannel heat sinks (MHSs) are promising candidates for long-term thermal solution given their simplicity, performance, and the development of MHS-compatible 3D device architecture. As the traditional methods of cooling generally have uniform heat removal on the contact area with the device, thermal consequences of design have traditionally been considered only after the layout of components on a device is finalized in accordance with connection and other criteria. Unlike traditional cooling solutions, however, microchannel heat sinks provide highly nonuniform heat removal on the contact area with the device. This feature is of utmost importance and can actually be used quite advantageously, if considered during the design phase of a device. In this study, simple thermal design criteria governing the general placement of components on devices to be cooled by microchannel heat sink are developed and presented. These thermal criteria are not meant to supersede connection and other important design criteria but are intended as a necessary and valuable supplement. Full-scale numerical simulations of a device with a realistic power map cooled by microchannel heat sink prove the effectiveness of the criteria, showing large reduction in maximum operating temperature and harmful temperature gradients. The simulations further show that the device and microchannel heat sink can dissipate a comparatively high amount of power, with little thermal danger, when design considers the criteria developed herein.
Design of an Ankle Rehabilitation Device Using Compliant Mechanisms
Authors: Sung Edward , Slocum Alexander H. , Ma Raymond , Bean Jonathan F. , Culpepper Martin L.
Published: January 2011

In this paper, we present the design, analysis, and testing of an ankle rehabilitation device (ARD), the purpose of which is to improve the efficacy of ankle joint complex (AJC) injury diagnosis and treatment. The ARD enables physicians to quantitatively measure the severity of an injury. This is done by measuring deficiencies in the joint’s range of motion, as well as force, torque, and power output. Evaluation of the relative degree of recovery over time can also reduce the error associated with current methodologies for rehabilitation, which rely on measurements based on the patient’s verbal response. A Wheatstone bridge circuit is used for the measurement of the various parameters as applied to the blades of complementary rotational flexures; the device is designed to measure motion about three axes of rotation in the ankle joint: pitch, roll, and yaw. A full bridge circuit is applied to each axis of rotation, and the use of multiple axes increases anatomically accurate measurement, enabling characterization of coupled motions. The device has flexibility and a range of motion such that it can be adjusted to take measurements of multiple different degrees of plantar or dorsiflexion of the AJC. The ARD is able to measure both range of motion, force, and torque output simultaneously. Experimental results show that there is significant coupled motion among the ankle joint rotations but that it is highly dependent on a subject’s own physical development.
A Scalable Model for Human Scala-Tympani Phantoms
Authors: Clark James R. , Warren Frank M. , Abbott Jake J.
Published: January 2011

In cochlear-implant (CI) insertion experiments, scala-tympani (ST) phantoms are often used in place of in vivo studies or cadaver studies. During the development of novel CI technology, a scaled-up phantom is often desirable. In this paper, we create a scalable model of the human ST by synthesizing published anatomical data and images. We utilize the model to fabricate an accurate, inexpensive, and reproducible ST phantom at a 3:1 scale.
A Note on the Screw Triangle
Authors: Zarrouk David , Shoham Moshe
Published: January 2011

This paper derives the expressions of an equivalent finite screw of two successive screw motions in a simplified form using purely vectorial analysis. This is achieved by tracing the trajectories of specific points on the moving body, which together with the known axis and angle of combined rotation, yield the expressions of the screw triangle. This paper also gives a short overview of different known expressions of the screw triangle and shows that the one given in this paper reduces the number of arithmetic operations by about a third compared with the most efficient algorithm in the literature.
Hydrogen Use in an Urban District: Energy and Environmental Comparisons
Authors: Vellini Michela , Tonziello Jacopo
Published: January 2011

Hydrogen technology is becoming ever more relevant because hydrogen use can help in containing greenhouse gas emission if CO2 capture and storage technologies are implemented in the hydrogen production pathway (when hydrogen is produced from fossil fuels). This work aims at carrying out a comparative analysis of possible energy scenarios in urban districts. A medium-small Italian city is considered as a reference case, and its energy consumption both for domestic and industrial use is evaluated. The current situation in which conventional technologies meet the energy needs is compared with a hypothetical scenario where hydrogen is largely used. Two options of hydrogen production from commercially ready technologies are investigated: coal gasification and steam methane reforming, as well as hydrogen use in advanced energy systems for transports and for thermal and electric energy generations. Also, the environmental impacts are evaluated. This study is particularly focused on greenhouse gas emissions with specific reference to carbon dioxide. The final goal is to define an alternative scenario, quantifying the energy needs and the relative environmental impacts in order to obtain quantitative information on the environmental benefits of the hydrogen scenario, as well as to identify its possible structural and functional criticalities.
Topology Synthesis of Multicomponent Structural Assemblies in Continuum Domains
Authors: Yildiz Ali R. , Saitou Kazuhiro
Published: January 2011

This paper presents a new method for synthesizing structural assemblies directly from the design specifications, without going through the two-step process. Given an extended design domain with boundary and loading conditions, the method simultaneously optimizes the topology and geometry of an entire structure and the location and configuration of joints, considering structural performance, manufacturability, and assembleability. As a relaxation of our previous work utilizing a beam-based ground structure, this paper presents a new formulation in a continuum design domain, which enhances the ability to represent complex structural geometry observed in real-world products. A multiobjective genetic algorithm is used to obtain Pareto optimal solutions that exhibit trade-offs among stiffness, weight, manufacturability, and assembleability. Case studies with a cantilever and a simplified automotive floor frame under multiple loadings are examined to show the effectiveness of the proposed method. Representative designs are selected from the Pareto front and trade-offs among the multiple criteria are discussed.
Kinematic Fundamentals of Planar Harmonic Drives
Authors: Dong Huimin , Ting Kwun-Lon , Wang Delun
Published: January 2011

This paper presents the kinematic model and offers a rigorous analysis and description of the kinematics of planar harmonic drives. In order to reflect the fundamental kinematic principle of harmonic drives, the flexspline of a harmonic drive is assumed to be a ring without a cup. A tooth on the flexspline is a rigid body, and the motion of the tooth is fully governed by the wave generator and the nominal transmission ratio of the harmonic drive. The proposed model depicts the flexspline tooth and the wave generator as a cam-follower mechanism, with the follower executing a combined translating and oscillating motion. With the rigid tooth motion obtained, the conjugate condition between the flexspline and the circular spline is determined, from which the conjugate tooth profile can be derived. In this paper, the motion is governed by geometry, and the flexibility of the flexspline only serves as a spring to maintain the contact between the cam and the follower. For any wave generator and any transmission ratio, the explicit expression of the conjugate condition is presented. For a given circular or flexspline tooth profile, the exact conjugate tooth profile can be obtained. The phenomenon of twice engagement is discussed for the first time.
Interfacial properties of HfO2 dielectric film on Ge substrate
Authors: He Dawei , Cheng Xinhong , Xu Dawei , Wang Zhongjian , Yu Yuehui , Sun Qingqing , Zhang David Wei
Published: January 2011

HfO 2 dielectric films were grown on Ge substrate and annealed. High resolution transmission electron microscopy indicated that postdeposition annealing promoted further crystallization of HfO2 films and aggravated interfacial roughness. X-ray reflectivity measurements suggested that the total thickness of the dielectric stacks was 6.5 nm. X-ray photoelectron spectra indicated further oxidization of Ge substrate. The interface layer between HfO2 and Ge was mainly composed of GeO2. The valence band offset between HfO2 and Ge interface was calculated to be 2.0 eV. The electrical measurements indicated that the leakage current density was 10 mA/cm2 at a gate bias of 2 V. The equivalent oxide thickness was 1.9 nm and the dielectric constant was 13 for the annealed film.
Thermally induced phase separation in supported bilayers of glycosphingolipid and phospholipid mixtures
Authors: Szmodis Alan W. , Blanchette Craig D. , Longo Marjorie L. , Orme Christine A. , Parikh Atul N.
Published: January 2011

The authors have studied microstructure evolution during thermally induced phase separation in a class of binary supported lipid bilayers using a quantitative application of imaging ellipsometry. The bilayers consist of binary mixtures consisting of a higher melting glycosphingolipid, galactosylceramide (GalCer), which resides primarily in the outer leaflet, and a lower melting, unsaturated phospholipid, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). Three different bilayer compositions of GalCer/DLPC mixtures at 35:65, 20:80, and 10:90 molar ratios were cooled at controlled rates from their high-temperature homogeneous phase to temperatures corresponding to their phase coexistence regime and imaged in real time using imaging ellipsometry. During the thermotropic course of GalCer gelation, we find that two distinct types of morphological features modulate. First, the formation and growth of chain and fractal-like defects ascribed to the net change in molecular areas during the phase transition. The formation of these defects is consistent with the expected contraction in the molecular area during the liquid crystalline to gel-phase transition. Second, the nucleation and growth of irregularly shaped gel-phase domains, which exhibit either line-tension dominated compact shape or dendritic domains with extended interfaces. Quantifying domain morphology within the fractal framework reveals a close correspondence, and the quantization of the transition width confirms previous estimates of reduced phase transition cooperativity in supported bilayers. A comparison of domain properties indicates that thermal history, bilayer composition, and cooling rate all influence microstructure details including shapes, sizes, and distributions of domains and defects: At lower cooling rates and lower GalCer fractions compact domains form and at higher GalCer fractions (or at higher cooling rates) dendritic domains are evident. This transition of domain morphology from compact shapes to dendritic shapes at higher cooling rates and higher relative fractions of GalCer suggests kinetic control of shape equilibration in these phospho- and glycolipid mixtures.
Surface-modified nanofibrous biomaterial bridge for the enhancement and control of neurite outgrowth
Authors: Zander Nicole E. , Orlicki Joshua A. , Rawlett Adam M. , Beebe Thomas P.
Published: January 2011

Biomaterial bridges constructed from electrospun fibers offer a promising alternative to traditional nerve tissue regeneration substrates. Aligned and unaligned polycaprolactone (PCL) electrospun fibers were prepared and functionalized with the extracellular matrix proteins collagen and laminin using covalent and physical adsorption attachment chemistries. The effect of the protein modified and native PCL nanofiber scaffolds on cell proliferation, neurite outgrowth rate, and orientation was examined with neuronlike PC12 cells. All protein modified scaffolds showed enhanced cellular adhesion and neurite outgrowth compared to unmodified PCL scaffolds. Neurite orientation was found to be in near perfect alignment with the fiber axis for cells grown on aligned fibers, with difference angles of less than 7o from the fiber axis, regardless of the surface chemistry. The bioavailability of PCL fibers with covalently attached laminin was found to be identical to that of PCL fibers with physically adsorbed laminin, indicating that the covalent chemistry did not change the protein conformation into a less active form and the covalent attachment of protein is a suitable method for enhancing the biocompatibility of tissue engineering scaffolds. a) Electronic mail: nicole.zander@arl.army.mil
Molecularly selective nanopatterns using nanoimprint lithography: A label-free sensor architecture
Authors: Forchheimer Daniel , Luo Gang , Ye Lei , Montelius Lars
Published: January 2011

Nanoimprint lithography (NIL) can generate well defined nanostructures with high efficiency and at very low cost. Molecular imprinting (MIP) is a “bottom-up” technique creating a polymer layer exhibiting structures with a molecular selectivity. Such polymer structures may be employed as molecular recognition sites for sensing applications. In this work, the authors combine NIL with MIP and they are able to obtain micro- and nanopatterns of polymer with features down to 100 nm that show high molecular selectivity.
Bad Science Used to Support Torture and Human Experimentation
Authors: Iacopino Vincent , Allen Scott A. , Keller Allen S.
Published: January 2011

Despite prior U.S. recognition of “enhanced interrogation” techniques as torture, science was misrepresented to support their use.
Spontaneous Cortical Activity Reveals Hallmarks of an Optimal Internal Model of the Environment
Authors: Berkes Pietro , Orbán Gergő , Lengyel Máté , Fiser József
Published: January 2011

Internal models of the environment optimize as the brain develops.
The Chlorine Dilemma
Authors: Sedlak David L. , von Gunten Urs
Published: January 2011

Chlorination of drinking water and municipal wastewater can create toxic chemical by-products, but alternatives pose their own set of hazards.
Freshwater Methane Emissions Offset the Continental Carbon Sink
Authors: Bastviken David , Tranvik Lars J. , Downing John A. , Crill Patrick M. , Enrich-Prast Alex
Published: January 2011

Inland freshwaters, which include lakes, reservoirs, streams, and rivers, may emit far more methane than previously thought.
Structure of Precursor-Bound NifEN: A Nitrogenase FeMo Cofactor Maturase/Insertase
Authors: Kaiser Jens T. , Hu Yilin , Wiig Jared A. , Rees Douglas C. , Ribbe Markus W.
Published: January 2011

A metalloprotein structure involved in nitrogen fixation offers insight into metal-cluster insertion in nitrogenase.
Developmental Plasticity in Sexual Roles of Butterfly Species Drives Mutual Sexual Ornamentation
Authors: Prudic Kathleen L. , Jeon Cheonha , Cao Hui , Monteiro Antónia
Published: January 2011

A butterfly switches sexual signaling and mate preferences depending on environmental temperatures during development.
Small Interannual Variability of Global Atmospheric Hydroxyl
Authors: Montzka S. A. , Krol M. , Dlugokencky E. , Hall B. , Jöckel P. , Lelieveld J.
Published: January 2011

The abundance of the highly reactive hydroxyl radical is well buffered against perturbations.
The Origins of Hot Plasma in the Solar Corona
Authors: De Pontieu B. , McIntosh S. W. , Carlsson M. , Hansteen V. H. , Tarbell T. D. , Boerner P. , Martinez-Sykora J. , Schrijver C. J. , Title A. M.
Published: January 2011

The solar corona is heated by jets of plasma propelled upward from the region immediately above the Sun’s surface.
Spin Crossover in Ferropericlase at High Pressure: A Seismologically Transparent Transition?
Authors: Antonangeli Daniele , Siebert Julien , Aracne Chantel M. , Farber Daniel L. , Bosak A. , Hoesch M. , Krisch M. , Ryerson Frederick J. , Fiquet Guillaume , Badro James
Published: January 2011

An iron spin transition has no effect on the seismologic properties of lower-mantle minerals.
Commerce at the Helm?
The Commodification of Academic Research
Science and the Modern University

Hans Radder, Ed.

University of Pittsburgh Press, Pittsburgh, 2010. 360 pp. $50. ISBN 9780822943969.
Authors: Shapin Steven
Published: January 2011

The contributors offer a philosophical perspective on "the current large-scale economic shaping of academic scientific research."
The Role of Ammonites in the Mesozoic Marine Food Web Revealed by Jaw Preservation
Authors: Kruta Isabelle , Landman Neil , Rouget Isabelle , Cecca Fabrizio , Tafforeau Paul
Published: January 2011

Analysis of x-ray microtomographic reconstructions of ammonite fossils reveal their feeding habits.
Getting a Better Estimate of an Atmospheric Radical
Authors: Isaksen I. S. A. , Dalsøren S. B.
Published: January 2011

Better measures of how global levels of OH vary from year to year will improve climate science.
More Intense, Shorter Pulses
Authors: Mourou Gerard , Tajima Toshiki
Published: January 2011

Large-scale laser facilities may also provide the ultimate source of ultrashort laser pulses.
Formin Tip Tracking
Authors: Pollard Thomas D.
Published: January 2011

A simple protein machine tracks the tip of a growing actin filament.
When Vernalization Makes Sense
Authors: Turck Franziska , Coupland George
Published: January 2011

A noncoding RNA molecule is required for plants to become competent to flower after a period of cold.
The Feeding Habits of Ammonites
Authors: Tanabe Kazushige
Published: January 2011

Synchrotron x-ray observations of ammonite fossils reveal the diet of Cretaceous organisms.