bluuebunny/crossref_metadata_2025_split huggingface dataset:
New type of 5–22 THz radiation sources based on semiconductor resonant reflectors
Authors: Požela Juras , Širmulis Edmundas , Požela Karolis , Šilėnas Aldis , Jucienė Vida 
Published: May 2012

AbstractIn polar semiconductors, the lattice dielectric function varies resonantly in the radiation frequency range ωT < ω < ωL, where ωT and ωL are the transverse and longitudinal optical phonon frequencies, respectively. The resonant reflectance spectra in the 5–22 THz range from polar semiconductors InSb, AlAs, InP, GaAs, GaN and GaAs/AlGaAs heterostructures are investigated experimentally. The semiconductor resonant reflectors are proposed, and a capability of separating a narrow spectral band from the heated‐body emission spectrum was realized. A new type of the continuous wave THz radiation source operational in the 5–22 THz range is proposed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of epitaxial layer thickness on the deep level defects in MBE grown n‐type Al0.33Ga0.67As
Authors: Mari Riaz H. , Aziz M. , Shafi M. , Khatab A. , Taylor D. , Henini M. 
Published: May 2012

AbstractThe effect of the epitaxial layer thickness on the deep level defects in MBE grown n‐Al0.33Ga0.67As is investigated for the first time using current‐voltage‐temperature (I‐V‐T), deep level transient spectroscopy (DLTS) and Laplace DLTS techniques. The epitaxial layer thickness is found to have profound effects on the room temperature I‐V characteristics, the number of defects detected by DLTS and their concentrations. In this investigation we compare n‐Al0.33Ga0.67As samples having epitaxial layer thicknesses of 2 µm and 1.5 µm. Our results reveal that by increasing the layer thickness (1) the reverse current increases; (2) the number of electrically active deep defects increases from two to six; (3) the concentration of the traps increases.The I‐V‐T and DLTS measurements carried out from 20 K to 300 K show that there is a dominant trap with an activation energy of ∼0.48 eV in both samples but with different concentrations (8.59 × 1014cm‐3 and 1.48 × 1014 cm‐3 for 2 µm and 1.5 µm samples, respectively). The reduction in the reverse current is directly related to the number of defects and their concentration. Our findings have important implications on the performances of electronic and optoelectronic devices. An attempt to explain the effect of the layer thickness on the deep traps in n‐Al0.33Ga0.67As will be given (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selective area heteroepitaxy through nanoimprint lithography for large area InP on Si
Authors: Metaferia Wondwosen , Tommila Juha , Junesand Carl , Kataria Himanshu , Hu Chen , Guina Mircea , Niemi Tapio , Lourdudoss Sebastian 
Published: May 2012

AbstractThe use of nanoimprint lithography, a low cost and time saving alternative to E‐beam lithography, for growing heteroepitaxial indium phosphide layer on silicon is demonstrated. Two types of patterns on 500 nm and 200 nm thick silicon dioxide mask either on InP substrate or InP seed layer on silicon were generated by UV nanoimprint lithography: (i) circular openings of diameter 150 nm and 200 nm and (ii) line openings of width ranging from 200 nm to 500 nm. Selective area growth and epitaxial lateral overgrowth of InP were conducted on these patterns in a low pressure hydride vapour phase epitaxy reactor. The epitaxial layers obtained were characterized by atomic force microscopy, scanning electron microscopy and micro photoluminescence. The growth from the circular openings on InP substrate and InP (seed) on Si substrate is extremely selective with similar growth morphology. The final shape has an octahedral flat top pyramid type geometry. These can be used as templates for growing InP nanostructures on silicon. The grown InP layers from the line openings on InP substrates are ∼ 2.5 μm thick with root mean square surface roughness as low as 2 nm. Completely coalesced layer of InP over an area of 1.5 mm x 1.5 mm was obtained.The room temperature photoluminescence intensity from InP layers on InP substrate is 55% of that of homoepitaxial InP layer. The decrease in PL intensity with respect to that of the homoepitaxial layer is probably due to defects associated with stacking faults caused by surface roughness of the mask surface. Thus in this study, we have demonstrated that growth of heteroepitaxial InP both homogeneously and selectively on the large area of silicon can be achieved. This opens up the feasibility of growing InP on large area silicon for several photonic applications (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
HeI2 interaction potential based on an interpolation scheme
Authors: Delgado‐Tellez Laura , Valdés Alvaro , Prosmiti Rita , Villarreal Pablo , Delgado‐Barrio Gerardo 
Published: May 2012

AbstractWe present a new CCSD(T) interaction potential for the ground state of the HeI2 complex. We used the general interpolation method for constructing smooth potential surfaces from ab initio data based on the reproducing kernel Hilbert Space and the inverse problem theory proposed by Ho and Rabitz [J. Chem. Phys. 1996, 104, 2584]. A global, full‐dimensional representation of the surface is obtained using the CCSD(T)/complete basis set ab initio data by García‐Gutierrez et al. [J. Phys. Chem. A 2009, 113, 5754]. We found that the present constructed potential represents all characteristics of the surface, and the differences with the previous analytical surface, based on the same set of ab initio data, are analyzed. Further, the influence of different generation procedures of the surface on the stability of the two, linear and T‐shaped, isomers, and vibrational states of the cluster is also discussed. © 2012 Wiley Periodicals, Inc.
System dynamics problem definition as an evolutionary process using the concept of ambiguity
Authors: Mashayekhi Ali N. , Ghili Soheil 
Published: May 2012

AbstractProblem definition is the most important phase of the system dynamics modeling process. In this paper, we propose an approach to enrich the problem definition process based on a continuous and conscious effort to elicit the hidden ambiguities of the dynamic hypothesis, and transform these ambiguities into questions. The answers to these questions would in turn sharpen the definition of the problem, and improve the dynamic hypothesis. We show how this approach can help in building models that are more suited to the real‐world dynamic problems and policy design. Finally, we proposed some guidelines for revealing ambiguities as a basis to problem definition and dynamic hypothesis in an iterative process. Copyright © 2012 System Dynamics Society.
Practical experiences of model‐based development: Case studies from the Swedish Armed Forces
Authors: Pilemalm Sofie , Hallberg Niklas , Sparf Magnus , Niclason Thomas 
Published: May 2012

AbstractThis study explores practical experiences of model‐based development and implementation, focusing on “lessons identified.” The study draws on experience from several case studies in the Swedish Defence domain using semistructured interviews as the major source of information. The study identifies several conditions as being crucial for successful implementation of model‐based development work, including an increased focus on the planning and premodeling phase, a need for interorganizational or across‐project collaboration, scalability, change management, and documentation and reuse of experiences. It was also found that most of the challenges identified in the model‐based development and implementation processes are common organizational and system development related problems such as change management, the issue of user participation, and how to carry out requirements engineering based on the models. Therefore, future research in the area should aim for a more integrative perspective, for instance, bridging the gap between information collection, models, user needs, and organizational and system requirements. © 2012 Wiley Periodicals, Inc. Syst Eng 15
Elegant systems design: Creative fusion of simplicity and power
Authors: Madni Azad M. 
Published: May 2012

AbstractElegance is a term frequently associated with aesthetics in design. It typically connotes simplicity, beauty, and grace. When it comes to complex systems, it also connotes predictable behavior, power, and creative functionality. Elegance is what separates the merely functional from the engaging. An elegant design usually has a thematic vision that drives its creation. It engages both designers and users and supports creative exploration on their part. The process of elegant design is an iterative, creative process that exploits systems thinking, probing questioning, and appropriate analogies and metaphors to gain insights that can be transformed novel solutions. This paper provides key insights into elegant systems design and characteristics of elegant systems designers. It offers a heuristics‐driven elegant systems design process along with metrics for assessing elegance. © 2012 Wiley Periodicals, Inc. Syst Eng 15
Neural tube defects—disorders of neurulation and related embryonic processes
Authors: Copp Andrew J. , Greene Nicholas D. E. 
Published: May 2012

AbstractNeural tube defects (NTDs) are severe congenital malformations affecting 1 in every 1000 pregnancies. ‘Open’ NTDs result from failure of primary neurulation as seen in anencephaly, myelomeningocele (open spina bifida), and craniorachischisis. Degeneration of the persistently open neural tube in utero leads to loss of neurological function below the lesion level. ‘Closed’ NTDs are skin‐covered disorders of spinal cord structure, ranging from asymptomatic spina bifida occulta to severe spinal cord tethering, and usually traceable to disruption of secondary neurulation. ‘Herniation’ NTDs are those in which meninges, with or without brain or spinal cord tissue, become exteriorized through a pathological opening in the skull or vertebral column (e.g., encephalocele and meningocele). NTDs have multifactorial etiology, with genes and environmental factors interacting to determine individual risk of malformation. While over 200 mutant genes cause open NTDs in mice, much less is known about the genetic causation of human NTDs. Recent evidence has implicated genes of the planar cell polarity signaling pathway in a proportion of cases. The embryonic development of NTDs is complex, with diverse cellular and molecular mechanisms operating at different levels of the body axis. Molecular regulatory events include the bone morphogenetic protein and Sonic hedgehog pathways which have been implicated in control of neural plate bending. Primary prevention of NTDs has been implemented clinically following the demonstration that folic acid (FA), when taken as a periconceptional supplement, can prevent many cases. Not all NTDs respond to FA, however, and adjunct therapies are required for prevention of this FA‐resistant category. WIREs Dev Biol 2013, 2:213–227. doi: 10.1002/wdev.71This article is categorized under:

Signaling Pathways > Global Signaling Mechanisms
Early Embryonic Development > Gastrulation and Neurulation
Birth Defects > Craniofacial and Nervous System Anomalies
Limb regeneration
Authors: Simon András , Tanaka Elly M. 
Published: May 2012

AbstractLimb regeneration is observed in certain members of the animal phyla. Some animals keep this ability during their entire life while others lose it at some time during development. How do animals regenerate limbs? Is it possible to find unifying, conserved mechanisms of limb regeneration or have different species evolved distinct means of replacing a lost limb? How is limb regeneration similar or different to limb development? Studies on many organisms, including echinoderms, arthropods, and chordates have provided significant knowledge about limb regeneration. In this focus article, we concentrate on tetrapod limb regeneration as studied in three model amphibians: newts, axolotls, and frogs. We review recent progress on tissue interactions during limb regeneration, and place those findings into an evolutionary context. WIREs Dev Biol 2013, 2:291–300. doi: 10.1002/wdev.73This article is categorized under:

Adult Stem Cells, Tissue Renewal, and Regeneration > Regeneration
Signaling and transcriptional regulation in neural crest specification and migration: lessons from xenopus embryos
Authors: Pegoraro Caterina , Monsoro‐Burq Anne H. 
Published: May 2012

AbstractThe neural crest is a population of highly migratory and multipotent cells, which arises from the border of the neural plate in vertebrate embryos. In the last few years, the molecular actors of neural crest early development have been intensively studied, notably by using the frog embryo, as a prime model for the analysis of the earliest embryonic inductions. In addition, tremendous progress has been made in understanding the molecular and cellular basis of Xenopus cranial neural crest migration, by combining in vitro and in vivo analysis. In this review, we examine how the action of previously known neural crest‐inducing signals [bone morphogenetic protein (BMP), wingless‐int (Wnt), fibroblast growth factor (FGF)] is controlled by newly discovered modulators during early neural plate border patterning and neural crest specification. This regulation controls the induction of key transcription factors that cooperate to pattern the premigratory neural crest progenitors. These data are discussed in the perspective of the gene regulatory network that controls neural and neural crest patterning. We then address recent findings on noncanonical Wnt signaling regulation, cell polarization, and collective cell migration which highlight how cranial neural crest cells populate their target tissue, the branchial arches, in vivo. More than ever, the neural crest stands as a powerful and attractive model to decipher complex vertebrate regulatory circuits in vivo. WIREs Dev Biol 2013, 2:247–259. doi: 10.1002/wdev.76This article is categorized under:

Gene Expression and Transcriptional Hierarchies > Regulatory Mechanisms
Signaling Pathways > Cell Fate Signaling
Early Embryonic Development > Gastrulation and Neurulation
Early Embryonic Development > Development to the Basic Body Plan
Preservation Versus Division of Ilioinguinal Nerve on Open Mesh Repair of Inguinal Hernia: A Meta‐analysis of Randomized Controlled Trials
Authors: Hsu Wayne , Chen Ching‐Shyang , Lee Hung‐Chia , Liang Hung‐Hua , Kuo Li‐Jen , Wei Po‐Li , Tam Ka‐Wai 
Published: May 2012

AbstractBackgroundChronic groin pain after inguinal hernia repair, a serious problem, is caused by entrapment of the ilioinguinal nerve either by mesh or development of fibrosis. Division of the ilioinguinal nerve during hernioplasty has been found to reduce the incidence of chronic groin pain. However, the traditional approach favors preservation of the ilioinguinal nerve during open hernia repair.MethodsWe conducted a systematic review and meta‐analysis of randomized controlled trials that compared the outcomes of preservation versus division of the ilioinguinal nerve during open mesh repair of inguinal hernia. The primary outcome was the incidence of groin pain; secondary outcomes were numbness and sensory loss.ResultsWe reviewed six trials with 1,286 patients. We found no difference between the groups for the incidence of groin pain or numbness at 1, 6, and 12 months after open mesh inguinal repair. The incidence of sensory loss or change was significantly higher in the division group than in the preservation group at 6 months [risk ratio (RR) 1.25; 95 % confidence interval (CI) 1.02–1.53] and at 12 months (RR 1.55; 95 % CI 1.01–2.37) postoperatively. No significant differences between the groups were noted at any other points in time.ConclusionsPreservation of the ilioinguinal nerve during open mesh repair of inguinal hernia is associated with a decreased incidence of sensory loss at 6 and 12 months postoperatively compared with that of the division technique. No significant differences were found between the groups for chronic groin pain or numbness.
Contrasting the Effects of Hydrophobicity and Counterion Size on Anionic Wormlike Micelle Growth
Authors: Han Yixiu , Wei Yongqiang , Wang Hang , Mei Yongjun , Zhou Hong 
Published: May 2012

AbstractRheological measurements were performed to understand the effect of benzyltrimethyl ammonium bromide (BTAB) and NaBr on the growth of wormlike micelles formed by sodium oleate (NaOA). Both salts can make the micellar solution viscoelastic, and the rheological responses verify the formation of wormlike micelles. The viscoelastic solution follows the Maxwell model of a single stress relaxation mode in the low‐frequency region. In comparison, the BTAB system exhibits stronger viscoelasticity than the NaBr system at constant salt concentration, but the critical overlapping concentration shows no significant difference; less BTAB can induce the solution to be more viscous than NaBr, but the viscosity maximum of the BTAB system is remarkably lower than that of NaBr at fixed NaOA content. The puzzling result is attributed to the effect of the composition on the packing parameter. In addition, it is shown that the zero‐shear viscosity of the two salt systems decreases upon heating, following the Arrhenius mode well.
Brief report: Relationships between physical activity and depressive symptoms in adolescent girls
Authors: Raudsepp Lennart , Neissaar Inga 
Published: May 2012

ABSTRACTThis study examined the relationships between changes in physical activity and depressive symptoms in adolescent girls. Participants were 277 urban adolescent girls. Physical activity was measured using the 3‐Day Physical Activity Recall and depressive symptoms were assessed using questionnaire. Data were collected on three occasions over a 3‐year period. The results of latent growth modelling indicated that initial level and change in physical activity was inversely associated with initial status and change in depressive symptoms The associations were independent of body mass index. Our results encourage the design of interventions that reduce depressive symptoms and increase physical activity of early adolescent girls.
Generalised equations for the prediction of percentage body fat by anthropometry in adult men and women aged 18–81 years
Authors: Leahy Siobhan , O'Neill Cian , Sohun Rhoda , Toomey Clodagh , Jakeman Philip 
Published: May 2012

Anthropometric data indicate that the human phenotype is changing. Today's adult is greater in stature, body mass and fat mass. Accurate measurement of body composition is necessary to maintain surveillance of obesity within the population and to evaluate associated interventions. The aim of the present study was to construct and validate generalised equations for percentage body fat (%BF) prediction from anthropometry in 1136 adult men and women. Reference values for %BF were obtained using dual-energy X-ray absorptiometry. Skinfold thickness (SF) at ten sites and girth (G) at seven sites were measured on 736 men and women aged 18–81 years (%BF 5·1–56·8 %). Quantile regression was employed to construct prediction equations from age and log-transformed SF and G measures. These equations were then cross-validated on a cohort of 400 subjects of similar age and fatness. The following generalised equations were found to most accurately predict %BF:$Men:\,(age\times 0\cdot 1) + (logtricepsSF\times 7\cdot 6) + (logmidaxillaSF\times 8\cdot 8) + (logsuprspinaleSF\times 11\cdot 9) - 11\cdot 3$(standard error of the estimate: 2·5 %, 95 % limits of agreement: − 4·8, +4·9)$Women:\,(age\times 0\cdot 1) + (logabdominalG\times 39\cdot 4) + (logmidaxillaSF\times 4\cdot 9) + (logbicepsSF\times 11\cdot 0) + (logmedialcalfSF\times 9\cdot 1) - 73\cdot 5$(standard error of the estimate: 3·0 %, 95 % limits of agreement: − 5·7, + 5·9) These generalised anthropometric equations accurately predict %BF and are suitable for the measurement of %BF in adult men and women of varying levels of fatness across the lifespan.
Objective assessment of learning curves for the Voxel-Man TempoSurg temporal bone surgery computer simulator
Authors: Nash R , Sykes R , Majithia A , Arora A , Singh A , Khemani S 
Published: May 2012

AbstractIntroduction:Simulators are becoming an increasingly important part of surgical training. Temporal bone surgery is one area in which simulators, such as the Voxel-Man TempoSurg simulator, are likely to play a significant role in training. We present learning curve data from novice trainees using this simulator to learn cortical mastoidectomy, exposure of the sigmoid sinus, and exposure of the short process of the incus.Methods:We measured the time taken to perform the procedures, the volume of reference bone removed, and the structures damaged during dissection.Results:We found improvement in a number of parameters over the course of the study. The overall scores, structural damage scores and time taken improved, to differing degrees, for each task. The volume of reference bone removed remained constant.Conclusion:These results indicate that the trainees' efficiency improved as they became more proficient at removing a given volume of reference bone.
Contracts made manifest
Authors: GREENBERG MICHAEL , PIERCE BENJAMIN C. , WEIRICH STEPHANIE 
Published: May 2012

AbstractSince Findler and Felleisen (Findler, R. B. & Felleisen, M. 2002) introducedhigher-order contracts, many variants have been proposed. Broadly, these fall into two groups: some follow Findler and Felleisen (2002) in usinglatentcontracts, purely dynamic checks that are transparent to the type system; others usemanifestcontracts, whererefinement typesrecord the most recent check that has been applied to each value. These two approaches are commonly assumed to be equivalent—different ways of implementing the same idea, one retaining a simple type system, and the other providing more static information. Our goal is to formalize and clarify this folklore understanding. Our work extends that of Gronski and Flanagan (Gronski, J. & Flanagan, C. 2007), who defined a latent calculus λCand a manifest calculus λH, gave a translation φ from λCto λH, and proved that if a λCterm reduces to a constant, so does its φ-image. We enrich their account with a translation ψ from λHto λCand prove an analogous theorem. We then generalize the whole framework todependent contracts, whose predicates can mention free variables. This extension is both pragmatically crucial, supporting a much more interesting range of contracts, and theoretically challenging. We define dependent versions of λHand two dialects (“lax” and “picky”) of λC, establish type soundness—a substantial result in itself, for λH— and extend φ and ψ accordingly. Surprisingly, the intuition that the latent and manifest systems are equivalent now breaks down: the extended translations preserve behavior in one direction, but in the other, sometimes yield terms that blame more.