bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcome of Vaginoplasty in Male-to-Female Transgenders: A Systematic Review of Surgical Techniques
Authors: Horbach Sophie E.R. , Bouman Mark-Bram , Smit Jan Maerten , Özer Müjde , Buncamper Marlon E. , Mullender Margriet G.
Published: March 2015

Introduction

Gender reassignment surgery is the keystone of the treatment of transgender patients. For male-to-female transgenders, this involves the creation of a neovagina. Many surgical methods for vaginoplasty have been opted. The penile skin inversion technique is the method of choice for most gender surgeons. However, the optimal surgical technique for vaginoplasty in transgender women has not yet been identified, as outcomes of the different techniques have never been compared.

Aim

With this systematic review, we aim to give a detailed overview of the published outcomes of all currently available techniques for vaginoplasty in male-to-female transgenders.

Methods

A PubMed and EMBASE search for relevant publications (1995–present), which provided data on the outcome of techniques for vaginoplasty in male-to-female transgender patients.

Main Outcome Measures

Main outcome measures are complications, neovaginal depth and width, sexual function, patient satisfaction, and improvement in quality of life (QoL).

Results

Twenty-six studies satisfied the inclusion criteria. The majority of these studies were retrospective case series of low to intermediate quality. Outcome of the penile skin inversion technique was reported in 1,461 patients, bowel vaginoplasty in 102 patients. Neovaginal stenosis was the most frequent complication in both techniques. Sexual function and patient satisfaction were overall acceptable, but many different outcome measures were used. QoL was only reported in one study. Comparison between techniques was difficult due to the lack of standardization.

Conclusions

The penile skin inversion technique is the most researched surgical procedure. Outcome of bowel vaginoplasty has been reported less frequently but does not seem to be inferior. The available literature is heterogeneous in patient groups, surgical procedure, outcome measurement tools, and follow-up. Standardized protocols and prospective study designs are mandatory for correct interpretation and comparability of data.
“Ah, I know why…”: children developing understandings through engaging with a picture book
Authors: Braid Christine , Finch Brian
Published: March 2015

This article describes part of a study that explored the responses of nine‐ and ten‐year‐old children during a picturebook read aloud in a small group setting in a New Zealand classroom. The read aloud was interactive, where the participants were encouraged to respond to the book and to each other throughout the session. The authors created a framework for analysing the responses, adapting the model of Lawrence Sipe (2008) with its five categories of literary understanding, by expanding on the analytical category to enable a finer analysis of the responses. This article discusses the children's depth of thinking and the understandings they developed as they engaged with the read aloud. It also describes how the adapted framework allowed a closer analysis of these understandings, including the way the elements of art used in the illustrations contributed to the children's ideas. The findings suggest ways picturebooks can be used to promote children's thinking and how teachers can guide discussion about a complex text. Implications for use of the framework in further research are discussed.
Strategic Capacity Investment under Hold‐up Threats: The Role of Contract Length and Width
Authors: Durand‐Viel Laure , Villeneuve Bertrand
Published: March 2015

We analyze the impact of the length of incomplete contracts on investment and surplus sharing. In the bilateral relationship explored, the seller controls the input and the buyer invests. With two‐part tariffs, the length of the contract is irrelevant: the surplus is maximal and goes to the seller. In linear contracts, the seller prefers the shortest contract and the buyer the longest one. Further, the commitment period concentrates the incentives, whereas afterwards there is rent extraction. The socially efficient contract is as short as possible; yet, long contracts can be promoted because of the surplus they allocate to the buyer.
Drought‐related tree mortality: addressing the gaps in understanding and prediction
Authors: Meir Patrick , Mencuccini Maurizio , Dewar Roderick C.
Published: March 2015

Increased tree mortality during and after drought has become a research focus in recent years. This focus has been driven by: the realisation that drought‐related tree mortality is more widespread than previously thought; the predicted increase in the frequency of climate extremes this century; and the recognition that current vegetation models do not predict drought‐related tree mortality and forest dieback well despite the large potential effects of these processes on species composition and biogeochemical cycling. To date, the emphasis has been on understanding the causal mechanisms of drought‐related tree mortality, and on mechanistic models of plant function and vegetation dynamics, but a consensus on those mechanisms has yet to emerge. In order to generate new hypotheses and to help advance the modelling of vegetation dynamics in the face of incomplete mechanistic understanding, we suggest that general patterns should be distilled from the diverse and as‐yet inconclusive results of existing studies, and more use should be made of optimisation and probabilistic modelling approaches that have been successfully applied elsewhere in plant ecology. The outcome should inform new empirical studies of tree mortality, help improve its prediction and reduce model complexity.

Contents

Summary
28

I.
Introduction
28

II.
Gaps in our mechanistic understanding of drought‐related tree mortality
29

III.
Modelling mortality in the face of incomplete mechanistic understanding
30

IV.
Conclusion
31

Acknowledgements
31

References
31
Biomass allocation and long‐term growth patterns of temperate lianas in comparison with trees
Authors: Ichihashi Ryuji , Tateno Masaki
Published: March 2015

The host‐dependent support habit of lianas is generally interpreted as a strategy designed to reduce resource investment in mechanical tissues; this allows preferential allocation to leaf and stem extension, thereby enhancing productivity and competitive abilities. However, this hypothesis has not been rigorously tested.

We examined the aboveground allometries regarding biomass allocation (leaf mass and current‐year stem mass (approximated as biomass allocated to extension growth) vs total aboveground mass) and long‐term apparent growth patterns (height and aboveground mass vs age, i.e. numbers of growth rings) for nine deciduous liana species in Japan.

Lianas had, on average, three‐ and five‐fold greater leaf and current‐year stem mass, respectively, than trees for a given aboveground mass, whereas the time course to reach the forest canopy was comparable and biomass accumulation during that period was only one‐tenth that of co‐occurring canopy trees. The balance between the lengths of yearly stem extension and existing older stems indicated that lianas lostc. 75% of stem length during growth to the canopy, which is probably a consequence of the host‐dependent growth.

Our observations suggest that, although lianas rely on hosts mechanically, allowing for short‐term vigorous growth, this habit requires a large cost and could limit plant growth over protracted periods.
Policing and punishment across the domains of social evolution
Authors: Singh Manvir , Boomsma Jacobus J.
Published: March 2015

Several decades of research in humans, other vertebrates, and social insects have offered fascinating insights into the dynamics of punishment (and its subset, policing), but authors have only rarely addressed whether there are fundamental joint principles underlying the maintenance of these behaviors. Here we present a punisher/bystander approach rooted in inclusive fitness logic to predict which individuals should take on punishing roles in animal societies. We apply our scheme to societies of eusocial Hymenoptera and nonhuman vertebrate social breeders, and we outline potential extensions for understanding conflict regulation among cells in metazoan bodies and unrelated individuals in human societies. We highlight that: 1) no social unit is expected to express punishment behavior unless it collects positive inclusive fitness benefits that surpass alternative benefits of bystanding; 2) punishment with public good benefits can be maintained through either direct fitness benefits (coercion) or indirect fitness benefits (correction) or both; 3) differences across social systems in the distributions of power, relatedness, and reproductive options drive variation in the extent to which individuals actively punish; and 4) inclusive fitness logic captures many punishment‐relevant evolutionary and ecological variables in a single framework that appears to apply across very different types of social arrangements.

Synthesis

Researchers have long observed that individuals in animal societies punish (and by extension, police) each other, but they have rarely investigated whether general principles underlie this behavior across social arrangements. In this paper, we present a punisher/bystander approach rooted in inclusive fitness logic to predict which individuals should take on punisher roles in animal societies. We apply the approach to eusocial insects and cooperatively breeding vertebrates and outline extensions towards the control of cancer cell lineages and punishment in human groups. We highlight how variation in specific social variables may drive differences in punishing/policing across the social domains.
Role of atopy patch test for diagnosis of food allergy‐related gastrointestinal symptoms in children
Authors: Boonyaviwat Onsuree , Pacharn Punchama , Jirapongsananuruk Orathai , Vichyanond Pakit , Visitsunthorn Nualanong
Published: March 2015

Background

Double‐blind, placebo‐controlled food challenge is the gold standard for diagnosing food allergy. However, it is a time‐consuming procedure and requires onsite medical supervision and resuscitating medicines and devices on hand. The objective of this study was to compare the atopy patch test (APT) with the oral food challenge test (OFC) in children with suspected food allergy‐related gastrointestinal (GI) symptoms.

Methods

A prospective self‐controlled study enrolled children with a history of suspected food allergy‐related GI symptoms. Skin prick test (SPT) and APT using lyophilized and commercial allergen extracts for cow's milk, egg, wheat, soy, and shrimp were evaluated, and OFC was performed.

Results

Thirty‐nine patients (25 boys, median age 2.4 yrs) with 76 events of suspected food allergy‐related GI symptoms were enrolled. SPT was positive in 11/76 events (14.5%). Sensitivity, specificity, predictive values, and likelihood ratio were calculated related to the food challenge outcome. Of 41 OFC, 30 (73.2%) were positive. APT using lyophilized allergen extracts yielded high sensitivity (80%) and high positive predictive value (85.7%). APT using commercial allergen extracts yielded low sensitivity (30%) but high specificity (90%). The negative predictive value of APT using lyophilized and commercial allergen extracts was 53.8% and 32.2%, respectively. All cases with positive APT using lyophilized allergen extracts together with positive SPT also had positive OFC.

Conclusion

In contrast to commercial extracts, APT with lyophilized allergen extracts is reliable, safe, and maybe useful for the diagnosis of suspected food allergy‐related GI symptoms in children. OFC is still needed in most of the cases.
Functional dissection of a strong and specific microbe‐associated molecular pattern‐responsive synthetic promoter
Authors: Lehmeyer Mona , Kanofsky Konstantin , Hanko Erik K. R. , Ahrendt Sarah , Wehrs Maren , Machens Fabian , Hehl Reinhard
Published: March 2015

Synthetic promoters are important for temporal and spatial gene expression in transgenic plants. To identify novel microbe‐associated molecular pattern (MAMP)‐responsive cis‐regulatory sequences for synthetic promoter design, a combination of bioinformatics and experimental approaches was employed. One cis‐sequence was identified which confers strong MAMP‐responsive reporter gene activity with low background activity. The 35‐bp‐long cis‐sequence was identified in the promoter of the Arabidopsis thaliana DJ1E gene, a homologue of the human oncogene DJ1. In this study, this cis‐sequence is shown to be a tripartite cis‐regulatory module (CRM). A synthetic promoter with four copies of the CRM linked to a minimal promoter increases MAMP‐responsive reporter gene expression compared to the wild‐type DJ1E promoter. The CRM consists of two WT‐boxes (GGACTTTT and GGACTTTG) and a variant of the GCC‐box (GCCACC), all required for MAMP and salicylic acid (SA) responsivity. Yeast one‐hybrid screenings using a transcription factor (TF)‐only prey library identified two AP2/ERFs, ORA59 and ERF10, interacting antagonistically with the CRM. ORA59 activates reporter gene activity and requires the consensus core sequence GCCNCC for gene expression activation. ERF10 down‐regulates MAMP‐responsive gene expression. No TFs interacting with the WT‐boxes GGACTTTT and GGACTTTG were selected in yeast one‐hybrid screenings with the TF‐only prey library. In transgenic Arabidopsis, the synthetic promoter confers strong and specific reporter gene activity in response to biotrophs and necrotrophs as well as SA.
Prognostic and predictive significance of immune cells infiltrating cutaneous melanoma
Authors: Ladányi Andrea
Published: March 2015

The tumor microenvironment is shaped by interactions between malignant cells and host cells representing an integral component of solid tumors. Host cells, including elements of the innate and adaptive immune system, can exert both positive and negative effects on the outcome of the disease. In melanoma, studies on the prognostic impact of the lymphoid infiltrate in general, and that of T cells, yielded controversial results. According to our studies and data in the literature, a high peritumoral density of activated T cells, increased amount of B lymphocytes and mature dendritic cells (DCs) predicted longer survival, while intense infiltration by plasmacytoid DCs or neutrophil granulocytes could be associated with poor prognosis. Besides its prognostic value, evaluation of the components of immune infiltrate could provide biomarkers for predicting the efficacy of the treatment and disease outcome in patients treated with immunotherapy or other, non‐immune‐based modalities as chemo‐, radio‐, or targeted therapy.
Pediatric Dermatology Training During Residency: A Survey of the 2014 Graduating Residents
Authors: Akhavan Alaleh , Murphy‐Chutorian Blair , Friedman Adam
Published: March 2015

Background

Knowledge of pediatric dermatology is considered a core competency of dermatology training and should be expected of all practicing dermatologists. While the numbers of both pediatric dermatology fellowships and board certified pediatric dermatologists in the workforce have increased over the years, recent reports suggest that there is a gap in pediatric dermatology education during dermatology residency. The goal of this study is to assess the current state of pediatric education during residency, as well as the clinical experience, satisfaction and expectations of graduating dermatology residents.

Methods

A 31‐question self‐report survey was distributed electronically to 294 third‐year dermatology residents with questions pertaining to demographics, didactic education, resident experience in pediatric dermatology training, satisfaction with pediatric training and future plans.

Results

One hundred and twenty‐three residents responded (41.8% response rate) representing approximately 29.1% of the total number of graduating residents. 69 (56.1%) residents reported academic time specifically devoted to pediatric dermatology, the majority (79.7%) of which was led by pediatric dermatologists. 82% of residents reported dedicated pediatric dermatology clinics at their program. 86.8% of respondents felt that their training in pediatric dermatology will allow them to confidently see pediatric dermatology patients in practice.

Conclusions

This survey highlights a promising state of pediatric dermatology training among current graduating dermatology residents. The majority of current graduating dermatology residents are satisfied with their pediatric dermatology education, feel confident treating pediatric patients, and plan to see pediatric patients in clinical practice.
Intimacy, communication, and aggressive behaviors: Variations by phases of romantic relationship development
Authors: REESE‐WEBER MARLA
Published: March 2015

This study examined how phases of romantic relationship development (honeymoon, defining, and established) were related to positive and negative relationship qualities. Participants (N = 136) completed self‐report measures. Results found significant differences between phases of romantic relationship development for all three positive relationship qualities, but each had a unique pattern of variation: (a) levels of intimacy had a linear increase across phases, (b) constructive communication strategies were higher in the established phase as compared with the earlier phases, and (c) negotiation was higher in both the defining and established phases as compared to the honeymoon phase. Results for negative relationships qualities found an inverted U‐shaped pattern for both destructive communication strategies and psychological aggression.
Insecure attachment and depressive symptoms: Forgiveness of self and others as moderators
Authors: LIAO KELLY YU‐HSIN , WEI MEIFEN
Published: March 2015

Most of the research on forgiveness has examined forgiveness of others, but not forgiveness of self even though researchers have argued that the latter deserves more attention. To fill this gap in the literature, and based on attachment theory's internal working models of self and others, this study examined forgiveness of self and others as moderators in the association between insecure attachment and depressive symptoms. A total of 403 undergraduate students participated in the study. Results supported the moderator role of forgiveness of self. Specifically, at high levels of forgiveness of self, the association between insecure attachment (i.e., anxiety and avoidant attachment) and depressive symptoms was not significant. The results did not support forgiveness of others as a moderator.
The use of renal replacement therapy in critically ill pediatric small bowel transplantation candidates and recipients: Experience from one center
Authors: Pineda Carol , Grogan Tristan , Lin James A. , Zaritsky Joshua J. , Venick Robert , Farmer Douglas G. , Kelly Robert B.
Published: March 2015

Outcomes for pediatric SBT patients requiring perioperative RRT in the PICU remain unknown. The objectives were to document our center's experience with PICU SBT patients receiving perioperative RRT and to identify variables predictive of survival to discharge. A retrospective chart review of patients (ages, 0–18 yr) between January 1, 2000 and December 31, 2011 that received RRT within a SBT perioperative period and were transplanted at our university‐affiliated, tertiary care children's hospital was performed. Six SBT patients received perioperative RRT (ages, 5–12 yr). Three patients (50%) survived to hospital discharge. Among survivors, RRT was required for a total of 1–112 days (mean, 49.7 days). All three survivors survived to hospital discharge without renal transplantation and free of RRT. There was a trend toward increased survival among older patients receiving RRT (p = 0.05). Survivors had a higher I‐125 GFR prior to PICU admission (p = 0.045). A higher I‐125 GFR prior to PICU admission among survivors may support this test's utility during SBT evaluation. In our experience, a high survival rate and freedom from RRT at the time of discharge support RRT use in the SBT population.
Testing cognitive predictors of individual differences in the sexual psychophysiological responses of sexually functional women
Authors: Clifton Jessica , Seehuus Martin , Rellini Alessandra H.
Published: March 2015

The literature on sexual responses shows a large and not fully understood between‐women variance in sexual responses and in strength of coherence between physiological and subjective sexual responses. This study investigated cognitive factors theorized to be associated with sexual responses that could explain such variance. Specifically, we investigated the predictive value of sexual excitation/inhibition and sexual schemas on sexual response and coherence. Vaginal photoplethysmography and continuous subjective sexual arousal were collected from 29 young women while they watched a control/erotic video sequence. Hierarchical linear modeling revealed that high sexual excitation and schemas related to passion and romance were related to higher coherence. These findings support the notion that cognitive factors that enhance sexual arousal contribute to the large variation seen in the coherence of sexual response as measured in the laboratory.
Recent Research Developments Affecting Nonlife Insurance—The CAS Risk Premium Project 2013 Update
Authors: Biener Christian , Eling Martin , Pradhan Shailee
Published: March 2015

This article reports the main results of the 2013 Risk Premium Project update, a yearly review of actuarial and finance literature on the theory and empirics of risk assessment for property–casualty insurance. The literature review reveals a broad variety of topics, with a strong leaning toward catastrophe risk, market efficiency, and new valuation techniques. Within the field of catastrophe risk, the role of weather and climate‐related risks for the insurance sector is reviewed and both the threats and the opportunities arising from the changing risk landscape are discussed.
Flood 2013: When Leaders Emerged and Risk Management Evolved at the University of Calgary
Authors: Nielson Norma
Published: March 2015

This article, organized as a teaching case, relates a small portion of the story that emerged when 2013 brought Calgary the most severe floods in living memory. The article first provides the reader with a bit of background on the topography, hydrology, and general risk exposure of the Bow River Valley in general and Calgary in particular. The next section provides some detail about The University of Calgary and its risk management structure. The article then looks at the Flood of 2013, describing the extent and phases of the disaster and the biggest challenges faced at the University. The article illustrates how important risk management processes can be even when an organization does not experience a disaster. The article concludes with a set of questions and answers that can be used to structure either a written assignment or an in‐class discussion. The key lessons that emerged for risk managers are presented in the answers to those questions.
Reforms, Finance, and Current Accounts
Authors: Bertola Giuseppe , Lo Prete Anna
Published: March 2015

We analyze the implications of labor market reforms for an open economy's human capital investment and future production. A stylized model shows that labor market deregulation can imply more positive current‐account balances if financial markets are imperfect and labor market institutions not only distort labor allocation, but also smooth income. Empirically, in Organisation for Economic Co‐operation and Development (OECD) country‐level panel data, we find that labor market deregulation has been positively related to current‐account surpluses on average and more strongly so when and where financial market access was more limited. These results are robust to inclusion of standard determinants of current‐account imbalances, and do not appear to be driven by cyclical phenomena.
Urbanicity Moderates Associations between Family Income and Adolescent Academic Achievement
Authors: Miller Portia , Votruba‐Drzal Elizabeth
Published: March 2015

Research has shown that family income's relations to early childhood achievement is stronger in large inner cities and weaker in less urbanized areas. Research has not yet considered whether links between family income and achievement in adolescence differ across the urban to rural landscape. Using nationally representative data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999 (N ≈ 9,350), this study examines differences in family income's links with eighth‐grade achievement across large urban, small urban, suburban, and rural communities. The point at which income‐achievement links plateau occurs later in the income distribution in less urbanized areas. The magnitude of the association between family income and reading and science skills also differs across the urban‐rural continuum, such that family income has stronger relations to reading and science achievement in urban cities and weaker links in suburban and rural communities.
On the Economic Geography of International Migration
Authors: Özden Çağlar , Parsons Christopher
Published: March 2015

We exploit the bilateral and skill dimensions from recent data sets of international migration to test for the existence of Zipf's and Gibrat's laws in the context of aggregate and high‐skilled international immigration and emigration using graphical, parametric and non‐parametric analysis. The top tails of the distributions of aggregate and high‐skilled immigrants and emigrants adhere to a Pareto distribution with an exponent of unity, that is Zipf's law holds. We find some evidence in favour of Gibrat's law holding for immigration stocks, such that the growth in stocks is independent of their initial values and stronger evidence that immigration densities are diverging over time. Conversely, emigrant stocks are converging in the sense that countries with smaller emigrant stocks are growing faster than their larger sovereign counterparts. Lastly, high‐skilled immigration and emigration stocks expressed in levels or as densities all exhibit signs of convergence. We conclude by discussing some competing mechanisms that could be driving the observed patterns including differing fertility rates, reductions in emigration restrictions, migrant sorting and selective immigration policies, immigrant networks and persisting wage differentials.
Effect of Dispersion Conditions on the Thermal and Mechanical Properties of Carbon Nanofiber–Polyester Nanocomposites
Authors: Hossain M. E. , Hossain M. K. , Hosur M. V. , Jeelani S.
Published: March 2015

In this study, sonication dispersion technique was employed to infuse 0.1–0.4 wt.% carbon nanofibers (CNFs) into polyester matrix to enhance thermomechanical properties of resulting nanocomposites. The effect of dispersion conditions has been investigated with regard to the CNF content and the sonication time. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) micrographs revealed excellent dispersion of 0.2 wt.% CNF infused in polyester, resulting in enhanced mechanical responses. Polyester with 0.2 wt.% CNF samples resulted in 88% and 16% increase in flexural strength and modulus, respectively, over the neat one. Quasi-static compression tests showed similar increasing trend with addition of CNF. Fracture morphology study of tested samples revealed relatively rougher surface in CNF-loaded polyester compared to the neat due to better interaction between the fiber and the matrix. Dynamic mechanical analysis (DMA) study exhibited about 35% increase in the storage modulus and about 5 °C increase in the glass transition temperature (Tg). A better thermal stability in the CNF-loaded polyester was observed from the thermogravimetric analysis (TGA) studies. Best results were obtained for the 0.2 wt.% CNF loading with 90 mins of sonication and 50% sonication amplitude. It is recommended that this level of sonication facilitates suitable dispersion of the CNF into polyester matrices without destroying the CNF's structure.
Study on the Air Core Formation of a Gas–Liquid Separator
Authors: Yin Junlian , Li Jingjing , Ma Yanfei , Li Hua , Liu Wei , Wang Dezhong
Published: March 2015

The gas–liquid separator is a key component in the gas removal system in thorium molten salt reactor (TMSR). In this paper, an experimental study focusing on the gas core formation in the gas–liquid separator was carried out. We observed that formation of the air core depends primarily on the back pressure in the separator. Gas core formation was visualized for a range of back pressures, swirl numbers, and Reynolds numbers. Analysis of flow patterns indicated that gas core formation may be defined as four stages: “air core with suction,” “tadpole-shaped core,” “cloudy core,” and “rod core.” When rod core is achieved, gas bubbles will be separated completely and that particular back pressure is defined as critical back pressure. The critical back pressure depends on swirl number and Reynolds number. The trends how the critical back pressures vary with the Reynolds number and the swirl number were analyzed.
Influence of Installation Tension on Transmission Error Due to Resonance in a Synchronous Belt
Authors: Kagotani Masanori , Ueda Hiroyuki
Published: March 2015

In synchronous belt drives, a transmission error is generated due to resonance of the belt spanning the driving and driven pulleys when the transverse natural frequency of the belt approaches the meshing frequency of the belt and the pulley teeth. The behavior of this transmission error has been assumed to be dependent on the installation tension. In the present study, the influence of the installation tension on the transmission error in a synchronous belt drive under no transmitted load was experimentally investigated for the case in which first mode vibration due to resonance was induced in both the upper and lower spans. In addition, an analysis of the transmission error based on the experimental results was carried out. A method for reducing the error was also investigated. The transmission error contains two components: one with a period equal to the pitch of the pulley, and the other with a period of half the pulley pitch. Good agreement was found between the calculation and experimental results, thus confirming the validity of the analysis method. For a fixed pulley speed, the transmission error was largest when the installation tension was applied at a position where the displacement of the upper span was equal to that of the lower span. It was found that the transmission error could be reduced by pushing an idler lightly against the center of the span of the belt that was undergoing the largest displacement.
Multiscale Study of Gas Slip Flows in Nanochannels
Authors: To Quy Dong , Pham Thanh Tung , Brites Vincent , Léonard Céline , Lauriat Guy
Published: March 2015

A multiscale modeling of the anisotropic slip phenomenon for gas flows is presented in a tree-step approach: determination of the gas–wall potential, simulation and modeling of the gas–wall collisions, simulation and modeling of the anisotropic slip effects. The density functional theory (DFT) is used to examine the interaction between the Pt–Ar gas–wall couple. This potential is then passed into molecular dynamics (MD) simulations of beam scattering experiments in order to calculate accommodation coefficients. These coefficients enter in an effective gas–wall interaction model, which is the base of efficient MD simulations of gas flows between anisotropic surfaces. The slip effects are quantified numerically and compared with simplified theoretical models derived in this paper. The paper demonstrates that the DFT potential is in good agreement with empirical potentials and that an extension of the Maxwell model can describe anisotropic slip effects due to surface roughness, provided that two tangential accommodation parameters are introduced. MD data show excellent agreement with the tensorial slip theory, except at large Kundsen numbers (for example, Kn ≃0.2) and with an analytical expression which predicts the ratio between transverse and longitudinal slip velocity components.
High-Speed Subsonic Compressible Lubrication
Authors: Dupuy Florence , Bou-Saïd Benyebka , Tichy John
Published: March 2015

The present study extends the scope of compressible lubrication theory (CLT) by considering a more complete formulation of compressible flow in a thin film. A one-dimensional (1D) approximation is obtained, which is common in basic studies of compressible flow. A dimensionless formulation of the thin film compressible flow equations (continuity, momentum, energy, and perfect gas) is derived. There are three dimensionless governing parameters, the Mach number M, the compressibility or bearing number Λ, and a heat transfer number H (a sort of inverse Péclet number). The classical theory assumes isothermal conditions (a consequence of a large heat transfer number) and implicitly assumes low Mach number conditions. It turns out that neither of these conditions are met in high-speed applications such as foil bearings. Results are calculated by varying M and H in a parametric fashion. We find that the influence of Mach number is small (at least up to M = 0.5) but the influence of heat transfer is large: the classical predicted results are in error by a factor of four or so. The improved theory predicts much greater load than the traditional. This means that high-speed air bearing design based on CLT would function satisfactorily, as born out by their successful application; however, such bearings would be significantly over-designed.
Analysis of Galinstan-Based Microgap Cooling Enhancement Using Structured Surfaces
Authors: Lam Lisa Steigerwalt , Hodes Marc , Enright Ryan
Published: March 2015

Analyses of microchannel and microgap cooling show that galinstan, a recently developed nontoxic liquid metal that melts at −19 °C, may be more effective than water for direct liquid cooling of electronics. The thermal conductivity of galinstan is nearly 28 times that of water. However, since the volumetric specific heat of galinstan is about half that of water and its viscosity is 2.5 times that of water, caloric, rather than convective, resistance is dominant. We analytically investigate the effect of using structured surfaces (SSs) to reduce the overall thermal resistance of galinstan-based microgap cooling in the laminar flow regime. Significantly, the high surface tension of galinstan, i.e., 7 times that of water, implies that it can be stable in the nonwetting Cassie state at the requisite pressure differences for driving flow through microgaps. The flow over the SS encounters a limited liquid–solid contact area and a low viscosity gas layer interposed between the channel walls and galinstan. Consequent reductions in friction factor result in decreased caloric resistance, but accompanying reductions in Nusselt number increase convective resistance. These are accounted for by expressions in the literature for apparent hydrodynamic and thermal slip. We develop a dimensionless expression to evaluate the tradeoff between the pressure stability of the liquid–solid–gas system and hydrodynamic slip. We also consider secondary effects including entrance effects and temperature dependence of thermophysical properties. Results show that the addition of SSs enhances heat transfer.
Cloud Computing for Cloud Manufacturing: Benefits and Limitations
Authors: Wang Peng , Gao Robert X. , Fan Zhaoyan
Published: March 2015

Cloud computing, as a new paradigm for aggregating computing resources and delivering services over the Internet, is of considerable interest to both academia and the industry. In this paper, the main characteristics of cloud computing are summarized, in view of its application to the manufacturing industry. Analytic models such as analytic hierarchy process (AHP) method for selecting appropriate cloud services are analyzed, with respect to computational cost and network communication that present a bottleneck for effective utilization of this new infrastructure. The review presented in this paper aims to assist academic researchers and manufacturing enterprises in obtaining an overview of the state-of-the-knowledge of cloud computing when exploring this emerging platform for service.
Improved Treatment of Anisotropic Scattering for Ultrafast Radiative Transfer Analysis
Authors: Hunter Brian , Guo Zhixiong
Published: March 2015

The necessity of conserving both scattered energy and asymmetry factor for ballistic incidence after finite volume method (FVM) or discrete-ordinates method (DOM) discretization is shown. A phase-function normalization technique introduced previously by the present authors is applied to scattering of ballistic incidence in 3D FVM/DOM to improve treatment of anisotropic scattering through reduction of angular false scattering errors. Ultrafast radiative transfer predictions generated using FVM and DOM are compared to benchmark Monte Carlo to illustrate the necessity of ballistic phase-function normalization. Proper ballistic phase-function treatment greatly improves predicted heat fluxes and energy deposition for anisotropic scattering and for situations where accurate numerical modeling is crucial.
Fast and Robust Full-Quadrature Triangular Elements for Thin Plates/Shells With Large Deformations and Large Rotations
Authors: Ren Hui
Published: March 2015

A new formulation for plates/shells with large deformations and large rotations is derived from the principles of continuum mechanics and calculated using the absolute nodal coordinate formulation (ANCF) techniques. A class of triangular elements is proposed to discretize the plate/shell formulation, which does not suffer from shear locking or membrane locking issue, and full quadrature can be performed to evaluate the integrals of each element. The adaptability of triangular elements enables the current approach to be applied to plates and shells with complicated shapes and variable thicknesses. The discretized mass matrix is constant, and the elastic force and stiffness matrix are polynomials of the generalized coordinates with constant coefficients. All the coefficients can be evaluated accurately beforehand, and numerical quadrature is not required in each time step of the simulation, which makes the current approach superior in numerical efficiency to most other approaches. The accuracy, robustness, and adaptability of the current approach are validated using both finite element benchmarks and multibody system standard tests.
Thermal Electrical Property Effects of Bone Structure on the Magnetic-Nanoparticle Enhanced Hyperthermia Targeting Tumor Underneath the Ribs
Authors: Jin Chao , He Zhi-Zhu , Liu Jing
Published: March 2015

Bone has very different thermal and electrical properties with the surrounding tissues. Misjustification of the heating dosage during an electromagnetic (EM) hyperthermia may lead to the failure of the treatment. Here aiming to disclose such clinically important issue, the present study presented a theoretical evaluation on the heating effects of magnetic-nanoparticles (MNPs) enhanced hyperthermia on the liver tumor underneath the ribs with bone features particularly addressed. The results revealed the following factors: (1) The existence of bone structure, i.e., ribs has an inevitable effect on the distribution of EM field; specifically, due to its lower dielectric property, the bone structure served as a barrier to attenuate the transport of EM energy and conversion of heat into the tissues, especially the tumor in the deep body. (2) Applying higher dosage or larger size MNPs would significantly enhance the temperature elevation at the target tumor tissues and thereby guarantee the performance of the hyperthermia. (3) Further parametric studies indicated that a higher frequency EM field would result in a worse heating effect; while stronger EM field will evidently enhance the heating effects of the hyperthermia process. This study promoted the better understanding of the EM heating on the bone structured tissues, and the findings are expected to provide valuable reference for planning an accurate surgery in future clinical liver tumor EM ablation.
Determination of the Free-Field Acoustic Radiation Characteristics of the Vibrating Plate Structures With Arbitrary Boundary Conditions
Authors: Nowak Łukasz J. , Zieliński Tomasz G.
Published: March 2015

The paper presents the developed algorithm which implements the indirect variational boundary element method (IVBEM) for computation of the free-field acoustic radiation characteristics of vibrating rectangle-shaped plate structures with arbitrary boundary conditions. In order to significantly reduce the computational time and cost, the algorithm takes advantage of simple geometry of the considered problem and symmetries between the elements. The procedure of determining the distribution of acoustic pressure is illustrated on the example of thin, rectangular plate with a part of one edge clamped and all other edges free. The eigenfrequencies and the corresponding vibrational mode shapes of the plate are computed using the finite element method (FEM). The results of the numerical simulations are compared to the results of the experiments carried out in an anechoic chamber, proving good agreement between the predictions and the observations. The reliability of simulations and high computational efficiency make the developed algorithm a useful tool in analysis of the acoustic radiation characteristics of vibrating plate structures.
Pool Boiling Enhancement by Electrohydrodynamic Force and Diamond Coated Surfaces
Authors: Kano Ichiro
Published: March 2015

Boiling heat transfer enhancement via compound effect of the electrohydrodynamic (EHD) effect and microstructured surfaces has been experimentally and analytically investigated. A fluorinated dielectric liquid (Asahi Glass Co., Ltd., AE-3000) was selected as the working fluid. Pool boiling heat transfer in the saturated liquid was measured at atmospheric pressure. Microstructured surfaces, which are mainly used for cutting tools, were developed with diamond particles using electrodeposition technique. Four different particle diameters were prepared: 5, 10, 15, and a mixture of 5 and 1.5 μm. The critical heat flux (CHF) for diamond particle surfaces showed 27–30 W/cm2 which was 26–40% increase for comparing with a noncoated surface (21.5 W/cm2). Upon application of a −5 kV/mm electric field to the microstructured surface (a mixture of 5 and 1.5 μm particles), a CHF of 70.2 W/cm2 at a superheat of 21.7 K was obtained. The previous theoretical equation of pool boiling predicted the CHF with electric field and without the electrode within 10%. Also, the CHF enhanced by the diamond coated surfaces was correlated well with the contact angle.
Cardiorespiratory motion‐compensated micro‐CT image reconstruction using an artifact model‐based motion estimation
Authors: Brehm Marcus , Sawall Stefan , Maier Joscha , Sauppe Sebastian , Kachelrieß Marc
Published: March 2015

Purpose:

Cardiac in vivo micro‐CT imaging of small animals typically requires double gating due to long scan times and high respiratory rates. The simultaneous respiratory and cardiac gating can either be done prospectively or retrospectively. In any case, for true 5D imaging, i.e., three spatial dimensions plus one respiratory‐temporal dimension plus one cardiac temporal dimension, the amount of information corresponding to a given respiratory and cardiac phase is orders of magnitude lower than the total amount of information acquired. Achieving similar image quality for 5D than for usual 3D investigations would require increasing the amount of data and thus the applied dose to the animal. Therefore, the goal is phase‐correlated imaging with high image quality but without increasing the dose level.

Methods:

To achieve this, the authors propose a new image reconstruction algorithm that makes use of all available projection data, also of that corresponding to other motion windows. In particular, the authors apply a motion‐compensated image reconstruction approach that sequentially compensates for respiratory and cardiac motion to decrease the impact of sparsification. In that process, all projection data are used no matter which motion phase they were acquired in. Respiratory and cardiac motion are compensated for by using motion vector fields. These motion vector fields are estimated from initial phase‐correlated reconstructions based on a deformable registration approach. To decrease the sensitivity of the registration to sparse‐view artifacts, an artifact model‐based approach is used including a cyclic consistent nonrigid registration algorithm.

Results:

The preliminary results indicate that the authors’ approach removes the sparse‐view artifacts of conventional phase‐correlated reconstructions while maintaining temporal resolution. In addition, it achieves noise levels and spatial resolution comparable to that of nongated reconstructions due to the improved dose usage. By using the proposed motion estimation, no sensitivity to streaking artifacts has been observed.

Conclusions:

Using sequential double gating combined with artifact model‐based motion estimation allows to accurately estimate respiratory and cardiac motion from highly undersampled data. No sensitivity to streaking artifacts introduced by sparse angular sampling has been observed for the investigated dose levels. The motion‐compensated image reconstruction was able to correct for both, respiratory and cardiac motion, by applying the estimated motion vector fields. The administered dose per animal can thus be reduced for 5D imaging allowing for longitudinal studies at the highest image quality.
Nutrient Intake by Ultramarathon Runners: Can They Meet Recommendations?
Authors: Wardenaar Floris C. , Dijkhuizen Rianne , Ceelen Ingrid J.M. , Jonk Emma , De Vries Jeanne H.M. , Witkamp Renger F. , Mensink Marco
Published: March 2015

Purpose:

The objective of this study was to investigate whether ultramarathon runners were able to meet nutrition recommendations during a training period and on a competition day.

Methods:

In preparation for a 60 or 120 km ultramarathon covering a varied terrain, male and female ultramarathon runners (n = 68, age 46.5 ± 7.1 y) reported habitual dietary intake during three independent days using a web-based 24-hr recall and questionnaires. The diet was assessed using probability of inadequacy or by qualitative evaluation using reference dietary intakes or sports nutrition recommendations. A small group of 120 km runners (n = 4) was observed continuously during the race. After the race, 60 km runners (n = 41) received a questionnaire to assess dietary intake and gastrointestinal (GI) distress on the race day. Spearman rank correlation coefficients (r) were applied to investigate the association between intake and general GI distress symptoms.

Results:

In men and women, habitual mean carbohydrate (CHO) intake was lower than recommended, as was mean protein intake by women. CHO intake during the race was <60 g/h in 75% of the athletes. A large variation of nutrient and fluid intake was seen. GI distress during the race was reported in 82% of the runners; severe GI distress was low. In general, moderate, mostly negative, correlations with nutrient intake were seen for GI distress.

Conclusions:

Sports nutrition recommendations for the habitual diet were not achieved. During a competition day, a large variation was found in nutrient intake; this may be related to a high incidence of GI distress.