bluuebunny/crossref_metadata_2025 huggingface dataset:
Matroids over a ring
Authors: Fink Alex , Moci Luca
Published: March 2016

We introduce the notion of a matroid

M

over a commutative ring

R

, assigning to every subset of the ground set an

R

-module according to some axioms. When

R

is a field, we recover matroids. When

R = \mathbb Z

, and when

R

is a DVR, we get (structures which contain all the data of) quasi-arithmetic matroids, and valuated matroids, i.e. tropical linear spaces, respectively.

More generally, whenever

R

is a Dedekind domain, we extend all the usual properties and operations holding for matroids (e.g., duality), and we explicitly describe the structure of the matroids over

R

. Furthermore, we compute the Tutte–Grothendieck ring of matroids over

R

. We also show that the Tutte quasi-polynomial of a matroid over

\mathbb Z

can be obtained as an evaluation of the class of the matroid in the Tutte–Grothendieck ring.
Training in Dialysis Access - Charting Future Success
Authors: Davidson Ingemar , Dolmatch Bart , Gallieni Maurizio , Ho Pei , Kraines Kelly , Liew Ngoh C. , Parakh Rajiv , Ross John , Slakey Douglas
Published: March 2016

Purpose

Medical education and training in dialysis access skills remains complex and inadequate as learners come from diverse backgrounds and from various specialties so that appropriate training is limited. As a result, a system of progressive education including live lectures, and hands on training has emerged, but there is controversy as to what constitutes the best educational model.

Methods

Presently there is no recognized or structured training in vascular access during residency or fellowships. Here we present a model of dialysis access training for beginner to advanced surgeons.

Results

A structured hands-on and didactic surgery training certification course consisting of a one week curriculum with 49 hours of ACCME credit hours has been in effect for one year. The learning impact and the performance outcome are high but with limited attendance capacity. Pre- and post- training test results attest to training effectiveness. To increase access, an off-site training curriculum has been initiated, entailing 1-2 days (8-15 credit hours) consisting of didactic lectures and surgical training. This teaching module has moderate learning impact for 50-100 attendees. Finally, a tiered, web-based training curriculum (10 ACCME credit hours) can accommodate an unlimited number of learners, but has a lower skills learning impact.

Conclusions

The future dialysis access training must also accommodate learners with diverse individual backgrounds, and different levels of professional (skill) development. To be effective and accessible, a variety of educational system, for example on site or web based is needed. Collaborative initiatives for global dialysis access training are currently underway.
Arterial Disease and Vascular Access in Diabetic Patients
Authors: Baktiroglu Selcuk , Yanar Fatih , Ozata Ibrahim H. , Oner Gizem , Ercan Damla
Published: March 2016

Purpose

There are conflicting reports on the effects of diabetes on the outcomes of hemodialysis access procedures. While some found no negative effects, others reported deleterious effects of diabetes on vascular access outcomes. Why is there concern about diabetes and related vascular problems on vascular access procedures? What are the differences of diabetic patients and their vasculature from that of nondiabetics? Do they have an effect on hemodialysis vascular access outcomes? We will try to find answers to these questions in light of the available evidence.

Methods

Recent literature on arterial disease in diabetes and end-stage renal disease (ESRD), and the effects on vascular access outcomes were searched in order to find answers to above questions.

Results

There are conflicting and controversial reports on the effects of preexisting vascular problems due to diabetes and chronic kidney disease (CKD) on the outcomes of hemodialysis access procedures. Diabetic vasculature, especially in patients with ESRD, has some specific problems, the most important of which seem to be the calcification and stiffening of the arteries.

Conclusions

Although some authors report inferior outcomes of vascular access procedures in diabetic patients, there is evidence that most of the problems encountered can be dealt with by careful patient selection, surgical skill, and experience.
Urgent Peritoneal Dialysis or Hemodialysis Catheter Dialysis
Authors: Lok Charmaine E.
Published: March 2016

Worldwide, there is a steady incident rate of patients with end-stage kidney disease (ESKD) who require renal replacement therapy. Of these patients, approximately one-third have an “unplanned” or “urgent” start to dialysis. This can be a very challenging situation where patients have either not had adequate time for education and decision making regarding dialysis modality and appropriate dialysis access, or a decision was made and plans were altered due to unforeseen circumstances. Despite such unplanned starts, clinicians must still consider the patient's ESKD “life-plan”, which includes the best initial dialysis modality and access to suit the patient's individual goals and their medical, social, logistic, and facility circumstances. This paper will discuss the considerations of peritoneal dialysis and a peritoneal dialysis catheter access and hemodialysis and central venous catheter access in patients who require an urgent start to dialysis.
Access Ligation in Transplant Patients
Authors: Wilmink Teun , Hollingworth Lee , Dasgupta Indranil
Published: March 2016

Access surgeons will encounter patients with functioning transplants who want to lose their fistula, and every dialysis unit sees patients returning after a failed kidney transplant for whom an old fistula is a readily available lifeline. The decision is straightforward in patients with perfectly functioning transplants and disabling complications of their fistula, or in patients with failing transplants and a good fistula. The challenge is to make this decision in patients with good transplant function and an asymptomatic fistula. Despite improvements in one-year survival of renal grafts, the long-term graft survival has improved modestly. This means about half of the patients with a successful kidney transplant will return to dialysis within 10 years. Use of recently developed risk calculators, based on clinical parameters, may help in the decision process. A high flow fistula can lead to heart failure but most fistulae are well tolerated in asymptomatic patients and the effects of closure of the AVF on the heart are modest. Recent evidence suggests that there may be benefits of a functioning AVF that may need to be considered in this decision process. This article reviews the literature and comes to pragmatic recommendations of what to do with this conundrum.
Some Perspectives on Assessment of Student Learning
Authors: Weisler Steven
Published: March 2016

The last twenty years have seen considerable accomplishments in the area of the assessment of student learning. I discuss some of the most significant of these achievements while also considering certain open questions that have arisen over the years and that remain in need of further analysis and resolution. Remarks are structured into three sections: Past, Present, and Future. Past chronicles the progress made toward developing a culture of assessment; Present focuses on the results of current research on student learning of interest to the assessment community; and Future considers several current issues that demand our collective attention.
Overlooked but Not Unimportant: Changes in the University Landscape and Assessment Results
Authors: Cole Alexandra
Published: March 2016

Much is made about the various challenges of assessment but little is made about the changing landscape of the American university system and whether such changes have made their way into assessment results. A case study based upon assessment work undertaken over a ten-year period is used to illustrate how outside factors may influence assessment results but may not be caught in regular assessment processes. Based upon the lessons of this case study, we suggest that assessment should not only present student-learning outcomes, but seek to interpret student learning outcomes in the context of educational change over time.
Jurisprudentie inzake misbruik economische machtspositie: de stand van zaken na Intel en Post Danmark II
Authors: Pijnacker Hordijk Erik
Published: March 2016

Jurisprudentie inzake misbruik economische machtspositie: de stand van zaken na Intel en Post Danmark II

Ruim een jaar geleden wees het Gerecht zijn arrest in de Intel-zaak. In dit arrest haakte het Gerecht aan bij de aloude jurisprudentie van het Hof van Justitie over de beoordeling van conditionele kortingsregelingen onder artikel 102 VWEU. Weliswaar bleef de beschikking van de Commissie in stand, maar de beleidsvernieuwingen die de Commissie heeft geïntroduceerd met de Richtsnoeren van de Commissie uit 2009 voor handhavingsprioriteiten bij de toepassing van artikel 102 VWEU op vormen van uitsluitingsmisbruik werden door het Gerecht deels impliciet, deels zelfs expliciet terzijde geschoven. Onlangs heeft het Hof van Justitie zich in het Post Danmark II-arrest kunnen uitspreken over de toepassing van artikel 102 VWEU op een conditionele kortingsregeling. Doel van deze bijdrage is een uitvoeriger overzicht te geven van de huidige stand van zaken.
Analytical Method for Sugar Profile in Pet Food and Animal Feeds by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection
Authors: Ellingson David J , Anderson Phillip , Berg Daniel P
Published: March 2016

There is a need for a standardized, accurate, rugged, and consistent method to measure for sugars in pet foods and animal feeds. Many traditional standard sugar methods exist for other matrixes, but when applied in collaborative studies there was poor agreement and sources of error identified with those standard methods. The advancement in technology over the years has given us the ability to improve on these standard methods of analysis. A method is described here that addresses these common issues and was subjected to a single-laboratory validation to assess performance on a wide variety of pet foods and animal feeds. Of key importance to the method performance is the sample preparation before extraction, type of extraction solvent, postextraction cleanup, and, finally, optimized chromatography using high-performance anion exchange chromatography with pulsed amperometric detection. The results obtained from the validation demonstrate how typical issues seen with these matrixes can influence performance of sugar analysis. The results also demonstrate that this method is fit-for-purpose and can meet the challenges of sugar analysis in pet food and animal feeds to lay the foundation for a standardized method of analysis.
Interação didática: apontamentos (inter)culturais sobre o uso da palavra e a formação do sujeito aluno
Authors: Modl Fernanda De Castro
Published: March 2016

O objetivo deste trabalho é discutir sobre a interação didática como um dos contextos dialógicos e discursivos genuínos para a formação do sujeito em termos do uso da palavra em sociedade. Assumindo um olhar dialógico (VOLOCHÍNOV, 1929/1999) – interacional (MEAD, 1934/1962) e metodologicamente amparado em princípios da etnografia, são trazidas cenas de interação didática de dois grupos (um alemão e um brasileiro) de uma mesma etapa de escolarização, a fim de demonstrar que o uso da palavra em sala de aula, ou seja, o modo como professor e alunos se posicionam como falantes e ouvintes em seus dia a dia interacionais, está submetido a convenções culturais, tanto em termos de uma cultura escolar ocidental, quanto de uma cultura escolar local.

 
O interacionismo social de Vigotski e o constructo de crenças sobre ensino e aprendizagem de línguas
Authors: Prochnow Ana Lucia Cheloti , Vieira Ana Nelcinda Garcia , Marchesan Maria Tereza Nunes
Published: March 2016

O presente trabalho tem como objetivo estabelecer relações entre o Interacionismo social de Vigotski e os estudos de crenças sobre ensino e aprendizagem de línguas. Entende-se que o ponto de convergência entre essas formulações reside na perspectiva descendente para a explicação e a definição dos seus respectivos objetos de investigação, ou seja, de que a linguagem, o desenvolvimento das funções superiores, assim como a constituição das crenças, partem do social até atingirem o individual. Trata-se de um estudo bibliográfico, que abarca a psicologia da linguagem em consonância com os pressupostos norteadores dos estudos de crenças. Para tanto, está embasado em autores como Vigotski (2007; 2009) e Friedrich (2012), cujo aporte teórico enfatiza o processo histórico-social e o papel da linguagem no desenvolvimento do indivíduo, bem como concebe à interação social o principal fator do desenvolvimento cognitivo humano; e em Barcelos (2004; 2006; 2007) e Silva (2010), que tratam dos estudos e investigação de crenças de professores de língua.

Palavras-chave: Interacionismo. Crenças. Ensino. Aprendizagem. Línguas.
Os benefícios interacionais do uso do discurso reportado direto por uma pessoa com afasia
Authors: Oliveira Mônika Miranda
Published: March 2016

Este estudo objetiva investigar os benefícios interacionais do uso do discurso reportado direto por uma pessoa com afasia, fundamentando-se em abordagens interacionais em linguística (Tannen, 1989; Schely-Newman, 2009) e afasia (Hengst et al., 2005; Wilkinson et. al, 2010). A análise dos dados de fala revela: construção de enunciados inteligíveis, turnos sem atraso e narrativas; inclusão da fala de personagens ausentes na interação; polidez; e gerenciamento da comunicação. Conclui-se que tais benefícios interacionais poderiam não ser alcançados sem o uso do discurso reportado direto devido às limitações impostas pela afasia.
Diante das limitações linguísticas de um paciente afásico: a interlocutora-terapeuta como conarradora
Authors: Oliveira Livia Miranda , Carmo Layanne Ferreira dos Santos
Published: March 2016

O estudo aqui apresentado é informado teórica e metodologicamente pelo arcabouço da Sociolinguística Interacional e tem como objetivo investigar a participação da interlocutora-terapeuta na construção da história de AVE de um paciente afásico por meio de um olhar para as ações da interlocutora que penetram o turno a turno da narração. Os dados analisados foram gerados em vídeo, através do método de entrevista em profundidade, e transcritos de acordo com convenções dos analistas da conversa com algumas adaptações de autoras da área da interação. As análises qualitativas de cunho interpretativista nos permitiram observar que as ações da terapeuta contribuíram para o desenho/ formatação da narrativa, para sustentação dos footings operantes na interação em curso e para a manutenção da intersubjetividade. Tais ações se configuraram como cooperativas e motivadoras, além de terem possibilitado o engajamento ativo do paciente na narração.
Considerações sobre a revisão profissional de textos acadêmico-cientifícos
Authors: Gomide Renata Marques , Gomide Filho Sérgio Roberto
Published: March 2016

Este artigo propõe uma reflexão sobre a atuação do revisor de textos acadêmico-científicos, buscando contemplar tanto a questão das demandas do mercado de revisão nessa área quanto os aspectos mais amplos da prática acadêmica, que incluem não somente os procedimentos que orientam as intervenções linguístico-gramaticais dos revisores, como também as intervenções relativas à normalização e formatação dos textos – que, acredita-se, incluem um amplo conjunto de fatores, não raro, decisivos para o reconhecimento de um texto como um evento comunicativo cientificamente válido. Articulada a essa reflexão está uma breve análise dos modos como quatro revisores, todos com formação em Letras e experiência no mercado de revisão de textos, procederam suas ações em um artigo acadêmico de conclusão de curso.
Para além da normalização: aspectos discursivos das normas de padronização
Authors: Rodrigues Daniella Lopes Dias Ignácio
Published: March 2016

O objetivo deste artigo é refletir sobre as normas de padronização do texto acadêmico-científico sob o viés discursivo tomando como objeto de análise prescrições relativas ao uso de aspas e itálico, do discurso relatado e das marcas de pessoa. Toma-se como corpus orientações de duas editoras – uma de Minas Gerais e outra de São Paulo – e três manuais de normalização. A tese defendida é a de que a intervenção do revisor de textos vai além do sistema linguístico e das questões normativas.
Da interlocução à construção do ethos: a interação profissional entre autor e revisor de textos
Authors: Baptista Patrícia Rodrigues Tanuri
Published: March 2016

Este trabalho focaliza a interação entre autor e revisor de texto, entendidos como enunciador e coenunciador respectivamente, e tem como objetivo principal analisar como se engendra o processo de coconstrução do ethos dos interactantes nos processamentos da intervenção textual observada, conforme Salgado (2011), como ritos genéticos editoriais. Os dados consistem em materiais autorais submetidos ao tratamento editorial, dois de um livro de Física Quântica e dois de um livro sobre infância, adolescência e Aids, da pesquisa de Salgado (2011). Nesta análise, estamos assumindo, como Maingueneau (2008), que o ethos é construído na instância da atividade discursiva. Nesse sentido, serão também importantes as noções de face de Goffman (1981) e de face positiva e negativa de Brown e Levinson (1987). Os dados demonstram que enunciador e coenunciador são colaborativos na construção do ethos de si próprios e um do outro. Como ethos do coenunciador, evidencia-se um leitor cujo olhar é criterioso e rigoroso, que propõe o que deve ser tratado com mais acuidade pelo enunciador, pressupondo o que vai interessar ao leitor potencial. Ele demonstra conhecimento do assunto tratado, apresenta sugestões das mais variadas ordens, desde mudanças puramente estruturais a propostas de inclusões e exclusões de partes do texto, em um trabalho interacional alicerçado em demonstrações de respeito pelo enunciador. Já o enunciador corrobora o ethos do coenunciador e, ao mesmo tempo, constrói o seu próprio, não só nas demonstrações de concordância, mas também e, sobretudo, nos elogios, nos pedidos de sugestão e na validação das manobras textuais realizadas pelo coenunciador.
Dialogicidade formal como possibilidade para a liberdade da palavra em práticas de justiça
Authors: Dias Ana Beatriz Ferreira , Miotello Valdemir
Published: March 2016

Neste trabalho, analisamos elementos estruturais da comunicação ideal entre vítimas, ofensores e suas comunidades de apoio propostos pela justiça restaurativa, uma abordagem bastante recente no Brasil que vem crescendo significativamente na última década. Ao eleger o diálogo entre os sujeitos como fundamental para a resolução e prevenção de situações de violência, o movimento restaurativo surge como uma resposta contrária ao atual modelo retributivo de justiça, altamente punitivo, abstrato e monológico, vigente há séculos. Instigados com as orientações do movimento restaurativo acerca da comunicação face a face entre os sujeitos mais diretamente envolvidos no dano, problematizamos a possibilidade da liberdade da palavra em práticas restaurativas. Para tanto, buscamos compreender as orientações para a realização de uma prática de justiça restaurativa intitulada “Círculo Restaurativo”. Analisamos materiais didáticos voltados à formação de coordenadores de Círculos Restaurativos propostos pelo Programa Justiça para o Século 21, por meio de sua Central de Práticas Restaurativas do Juizado Regional da Infância e da Juventude de Porto Alegre (RS). Este trabalho de compreensão se dá fundamentado teórica e metodologicamente nos estudos bakhtinianos. Mobilizando, sobretudo, o conceito de dialogicidade formal, consideramos que o Círculo Restaurativo oferece condições técnicas que podem levar à emergência de várias vozes no processo de justiça, contribuindo com uma maior liberdade da palavra em instâncias judiciárias.
Entre ritmo e poesia: rap e literatura oral urbana
Authors: Salgado Marcus Rogerio
Published: March 2016

O objetivo do presente artigo é um estudo do rap enquanto manifestação de literatura oral urbana e forma de oralidade tecnológica. Para tanto, o artigo passará em revista as relações entre literatura e palavra falada/cantada, assim como as possibilidades de interface estética entre a literatura e a música que estão em questão quando tratamos do rap.
Pela voz de Luandino
Authors: Chaves Rita de Cássia Natal , Kaczorowski Jacqueline
Published: March 2016

Entrevista com o escritor Luandino Vieira
O leitor e o espectador nas malhas da ficção de Ressurreição, A mão e a luva e Helena.
Authors: Assmann Saraiva Juracy , Bender Debora
Published: March 2016

O artigo analisa os romances Ressurreição, A mão e a luva e Helena, publicados por Machado de Assis, entre 1872 e1876 e cuja diegese abrange o período que vai de 1850 a 1862, para apreender significações que a menção a autores, obras literárias, espetáculos teatrais e musicais agregam às narrativas e para abstrair a representação da sociedade brasileira que essas referências instalam. Elas convidam o receptor a transcender a história narrada para participar das reflexões do escritor sobre o contexto socioestéticoe a integrar a ficção ao mundo do real; simultaneamente, revelam a importância das experiências de Machado de Assis como leitor e espectador na produção de seus textos.
Drummond e o humanismo
Authors: Perius Cristiano
Published: March 2016

Este ensaio analisa aspectos da poesia de Carlos Drummond de Andrade afins com o tema do humanismo. Para tanto, vale-se das homologias entre a poesia de Drummond e a filosofia/literatura de Jean-Paul Sartre a partir do romance “A Náusea” e “O que é a literatura?”, sobretudo. A aproximação com o humanismo, no entanto, longe de ser uma relação de superveniência, ou de subsídio, é discutida no próprio terreno da literatura e problematizada a partir do eu lírico.
Simulating the development and progression of Chronic Kidney Disease and osteoporosis in people living with HIV
Authors: Adami Silvano , Maggi Paolo , Montinaro Vincenzo , Povero Massimiliano , Pradelli Lorenzo , Bellagamba Rita , Bonfanti Paolo , Di Biagio Antonio , Rusconi Stefano , Di Campli Francesco Maria , Forastieri Giuseppe , Mancini Michele
Published: March 2016

The “chronicization” of HIV infection brings about a growing necessity to attentively evaluate current and potential complications when prescribing the individual therapeutic regimen. Starting from this need, we developed two HIV-comorbidity simulators that, basing on the evidence available in medical literature and starting from the current clinical and demographic features of the individual patient, project and compare the risks of developing and worsening of nephropathy and osteopathy associated with possible ARV regimens. These simulators are embedded in a desktop, user-friendly software thought to be used by the treating physician during prescription discussion with his/her patients, in order to highlight expected clinical outcomes and healthcare resource consumption that may differ according to the therapeutic strategy selected. In this article we present the sources and methods used in developing the mathematical models, alongside a set of examples and the results of cohort-level validation runs.
The Treatment of Ipso Facto Clauses in Canada
Authors: Ho Adrienne
Published: March 2016

Whether a debtor is an individual or a sophisticated financial institution, a
common issue that arises is whether its insolvency alters the rights of the parties with
whom the debtor has entered into contracts. Could the non-defaulting party to the contract,
on the basis of the debtor’s insolvency, terminate or amend the contract? Could it demand
accelerated payment? Many parties preserve contractual rights, through what are commonly
known as ipso facto clauses, to terminate and amend contracts or to demand an
accelerated payment in the event that a counterparty to the contract becomes insolvent.
Despite recent amendments to the Bankruptcy and Insolvency Act (BIA) and
the Companies’ Creditors Arrangement Act (CCAA), the validity of ipso
facto clauses, outside the context of derivatives contracts, is an issue that has not
been thoroughly addressed in the Canadian literature. This article will trace the
anti-deprivation rule in England, culminating in the United Kingdom Supreme Court’s leading
case: Belmont Park Investments PTY Ltd. v. BNY Corporate Trustee Services Ltd.
and Lehman Brothers Special Financing Inc. It will then explore to what extent recent
amendments to the BIA and the CCAA have displaced the common law rule in
Canada. Both the BIA and the CCAA have nullified ipso facto
clauses in some but not all situations, the most notable exceptions being cases involving
corporate bankruptcies and receiverships. This article will conclude with a discussion of
the codified exceptions to the common law principles and whether the Canadian jurisprudence
might incorporate some of the modifications to the anti-deprivation rule introduced by Lord
Collins in Belmont.
Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells
Authors: Haschke Jan , Amkreutz Daniel , Rech Bernd
Published: March 2016

Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.
Impact of doping concentration on 1/f noise performances of accumulation-mode Si(100) n-MOSFETs
Authors: Gaubert Philippe , Teramoto Akinobu , Sugawa Shigetoshi
Published: March 2016

The superiority of highly doped accumulation-mode n-MOSFETs over the conventional inversion-mode ones has been acknowledged in this paper, not only in terms of electrical performances but also in terms of noise level. These results, in addition to those regarding accumulation-mode p-MOSFETs, demonstrate that an improved CMOS technology built on simultaneously high-speed and low-noise accumulation-mode MOSFETs has been achieved, paving the way towards more reliable and faster microprocessors.
Strain-induced step bunching in orientation-controlled GaN on Si
Authors: Narita Tetsuo , Iguchi Hiroko , Horibuchi Kayo , Otake Nobuyuki , Hoshi Shinichi , Tomita Kazuyoshi
Published: March 2016

We report a technique for the fabrication of high-quality GaN-on-silicon (Si) substrates for use in various power applications. GaN epitaxial layers were generated on Si(111) vicinal faces that had been previously covered with a thin coating of Al2O3 to control the orientation of the AlN seed layers. We obtained orientation-controlled GaN layers and found a linear relationship between the GaN c-axis and Si[111] tilt angles. As a result, the threading dislocation density in the AlN seed layer was reduced and high-quality GaN layers were generated. The X-ray rocking curves for these layers exhibited full width at half maximum values of 390′′ and 550′′ for the (004) and (114) reflections, respectively. Significant step bunching was observed on a GaN(0001) vicinal face produced using this technique, attributed to strain-induced attractive interactions between steps. Thus, by controlling the strain near the surface layer, we achieved the step flow growth of GaN on Si.
Formation mechanism of AlN whiskers on sapphire surfaces heat-treated in a mixed flow of H2 and N2
Authors: Takada Kazuya , Nomura Kazushiro , Togashi Rie , Murakami Hisashi , Koukitu Akinori , Kumagai Yoshinao
Published: March 2016

The formation mechanism of AlN whiskers on sapphire substrates during heat treatment in a mixed flow of H2 and N2 was investigated in the temperature range of 980–1380 °C. AlN whiskers grew above 1030 °C after covering the sapphire surface with a thin AlN layer. The existence of pits on the sapphire surface beneath the thin AlN layer was observed. Both AlN whisker and pit densities of samples were on the same order of 108 cm−2. These results suggested the following mechanism. First, the sapphire surface reacts with H2, and the generated Al gas reacts with N2 to form a thin AlN layer on sapphire. Then, the sapphire surface reacts with H2 diffusing to the AlN/sapphire interface. The Al gas escapes through dislocations in the AlN layer to leave pits on the sapphire surface, and finally reacts with N2 to form AlN whiskers on the top surface.
Structural insight into the interaction of O‐acetylserine sulfhydrylase with competitive, peptidic inhibitors by saturation transfer difference‐NMR
Authors: Benoni Roberto , Pertinhez Thelma A. , Spyrakis Francesca , Davalli Silvia , Pellegrino Sara , Paredi Gianluca , Pezzotti Angelica , Bettati Stefano , Campanini Barbara , Mozzarelli Andrea
Published: March 2016

O‐acetylserine sulfhydrylase (OASS), the enzyme catalysing the last step of cysteine biosynthesis in bacteria, is involved in antibiotic resistance and biofilm formation. Since mammals lack OASS, it is a potential target for antimicrobials. However, a limited number of inhibitors has been developed and crystallized in complex with OASS. STD‐NMR was applied to study the interaction of the inhibitory pentapeptide MNYDI with the CysK and CysM OASS isozymes from Salmonella Typhimurium. Results are in excellent agreement with docking and SAR studies and confirm the important role played by the C‐terminal Ile5 and the arylic moiety at P3 in dictating affinity.
On the formation of tropical rings of atomic halogens: Causes and implications
Authors: Saiz‐Lopez Alfonso , Fernandez Rafael P.
Published: March 2016

Halogens produced by ocean biological and photochemical processes reach the tropical tropopause layer (TTL), where cold temperatures and the prevailing low ozone abundances favor the diurnal photochemical enhancement of halogen atoms. Under these conditions atomic bromine and iodine are modeled to be the dominant inorganic halogen species in the sunlit TTL, surpassing the abundance of the commonly targeted IO and BrO radicals. We suggest that due to the rapid photochemical equilibrium between halogen oxides and halogen atoms a natural atmospheric phenomenon evolves, which we have collectively termed “tropical rings of atomic halogens.” We describe the main causes controlling the modeled appearance and variability of these superposed rings of bare bromine and iodine atoms that circle the tropics following the Sun. Some potential implications for atmospheric oxidizing capacity are also explored. Our model results suggest that if experimentally confirmed, the extent and intensity of the halogen rings would directly respond to changes in oceanic halocarbon emissions, their atmospheric transport, and photochemistry.
Lithospheric fault and kinematic decoupling of the Apennines system across the Pollino range
Authors: Chiarabba Claudio , Agostinetti Nicola Piana , Bianchi Irene
Published: March 2016

A persistent seismic gap is hypothesized in the Pollino area (southern Italy), at the boundary between the Apennines and the Calabrian arc. Presently, seismic swarms are active in the gap area, creating concerns for possible future large earthquakes. In this study, we model the deep Earth structure across the Pollino range to give new insights on the kinematics and tectonics of this enigmatic area. Migrated receiver function profiles show a subvertical lithospheric discontinuity, delineated by an abrupt change in Moho depth and mantle fabrics across the range. The lithospheric‐scale discontinuity bounds the area of earthquake swarm activity and likely decouples the delamination‐related extension of the Apennines from the extensional collapse of the Calabrian fore arc. This large‐scale discontinuity implies that the normal faults are segmented across the range, limiting the lateral extent of faults where future earthquakes might occur.
The Eastern California Shear Zone as the northward extension of the southern San Andreas Fault
Authors: Thatcher W. , Savage J. C. , Simpson R. W.
Published: March 2016

Cluster analysis offers an agnostic way to organize and explore features of the current GPS velocity field without reference to geologic information or physical models using information only contained in the velocity field itself. We have used cluster analysis of the Southern California Global Positioning System (GPS) velocity field to determine the partitioning of Pacific‐North America relative motion onto major regional faults. Our results indicate the large‐scale kinematics of the region is best described with two boundaries of high velocity gradient, one centered on the Coachella section of the San Andreas Fault and the Eastern California Shear Zone and the other defined by the San Jacinto Fault south of Cajon Pass and the San Andreas Fault farther north. The ~120 km long strand of the San Andreas between Cajon Pass and Coachella Valley (often termed the San Bernardino and San Gorgonio sections) is thus currently of secondary importance and carries lesser amounts of slip over most or all of its length. We show these first order results are present in maps of the smoothed GPS velocity field itself. They are also generally consistent with currently available, loosely bounded geologic and geodetic fault slip rate estimates that alone do not provide useful constraints on the large‐scale partitioning we show here. Our analysis does not preclude the existence of smaller blocks and more block boundaries in Southern California. However, attempts to identify smaller blocks along and adjacent to the San Gorgonio section were not successful.
The impact of the direct effects of sulfate and black carbon aerosols on the subseasonal march of the East Asian subtropical summer monsoon
Authors: Wang Dongdong , Zhu Bin , Jiang Zhihong , Yang Xiu‐Qun , Zhu Tong
Published: March 2016

Aerosol emissions have rapidly increased in East Asia since the late 1970s. During the same period, the East Asian summer monsoon has shown a weakening trend. In this work, the direct effects (DE) of sulfate and black carbon (BC) aerosols on the subseasonal (pentad mean) march of the East Asian subtropical summer monsoon (EASSM) are investigated using an interactive global climate‐chemistry model. The simulation results suggest that the DE of sulfate aerosols have a notable effect on the cooling of the low troposphere across the continent in spring and autumn, hence, changing the time of the seasonal transition of the zonal land‐sea thermal contrast (ZTC). The DE of BC result in cooling of the low troposphere and heating of the middle troposphere, leading to a different impact than that caused by sulfates. The cooling of the surface and troposphere by sulfates leads to a delay in the warming of East Asian continent in spring and the EASSM onset time; it also accelerates the process of the continent turning colder and advances the retreat of the EASSM. The deeper heating in the middle‐upper troposphere than the cooling in the low troposphere due to the DE of BC or the combination of both lead to an advance in the onset time of the monsoon caused by the continent turning warmer earlier in spring. In autumn, the same cooling effect by sulfates leads to the continent turning colder earlier, resulting in an advance in the retreat time.
Dynamical and elastic properties of MgSiO3 perovskite (bridgmanite)
Authors: Wehinger Björn , Bosak Alexeï , Nazzareni Sabrina , Antonangeli Daniele , Mirone Alessandro , Chaplot Samrath Lal , Mittal Ranjan , Ohtani Eiji , Shatskiy Anton , Saxena Surendra , Ghose Subrata , Krisch Michael
Published: March 2016

We report on the lattice dynamics of MgSiO3 perovskite (bridgmanite). Phonon spectroscopy was performed employing inelastic X‐ray scattering from single crystals, and the results were confronted to ab initio calculations. We observe a remarkable agreement between experiment and theory, and provide accurate results for phonon dispersion relations, the vibrational density of states, and the full elasticity tensor. The present work constitutes an important milestone fully validating the lattice dynamics calculation against precise experimental evidence and marks a starting point to extend this kind of combined studies to the high‐pressure and high‐temperature conditions directly relevant for the physical properties and chemical composition of Earth's lower mantle.
Future Arctic sea ice loss reduces severity of cold air outbreaks in midlatitudes
Authors: Ayarzagüena Blanca , Screen James A.
Published: March 2016

The effects of Arctic sea ice loss on cold air outbreaks (CAOs) in midlatitudes remain unclear. Previous studies have defined CAOs relative to the present‐day climate, but changes in CAOs, defined in such a way, may reflect changes in mean climate and not in weather variability, and society is more sensitive to the latter. Here we revisit this topic but applying changing temperature thresholds relating to climate conditions of the time. CAOs do not change in frequency or duration in response to projected sea ice loss. However, they become less severe, mainly due to advection of warmed polar air, since the dynamics associated with the occurrence of CAOs are largely not affected. CAOs weaken even in midlatitude regions where the winter mean temperature decreases in response to Arctic sea ice loss. These results are robustly simulated by two atmospheric models prescribed with differing future sea ice states and in transient runs where external forcings are included.
Labor unions
Authors: Fairbrother Peter
Published: March 2016

Over the past two decades, many governments have sponsored a business‐driven model of economic reform. By redefining what was meant by a model state employer, many governments have promoted a state labor market defined by flexibility, competitiveness, and individualization. In the United Kingdom, for example, Conservative governments in the 1980s and 1990s legislated for and promoted these goals, continued by subsequent governments (Bowman et al. 2014).
Biomimetic High‐Valent Mononuclear Nonheme Iron‐Oxo Chemistry
Authors: Klein Johannes E.M.N. , Que Lawrence
Published: March 2016

Herein we summarize the current status of efforts to synthesize and characterize high‐valent mononuclear nonheme iron‐oxo complexes that serve as models for intermediates found in the catalytic cycles of dioxygen activating nonheme iron enzymes. The main focus is the description and comparison of over 70 nonheme Fe
IV
(O) complexes synthesized thus far, and also included are few examples of Fe
III
(O), Fe
III
(OX), and Fe
V
(O) complexes, which are often generated with related or identical ligand frameworks as the Fe
IV
(O) complexes. Structural and spectroscopic parameters, as well as basic trends in oxygen‐ and hydrogen‐atom transfer reactivity, are described for subsets of complexes where systematic comparisons can be made.
N

‐Formimino‐
L
‐Glutamate Iminohydrolase from

P

seudomonas Aeruginosa
Authors: Martí‐Arbona Ricardo , Raushel Frank M
Published: March 2016

N
‐formimino‐
l
‐glutamate iminohydrolase, also known as
N
‐formimino‐
l
‐glutamate deiminase or
HutF
, catalyzes the hydrolysis of the imino group in
N
‐formimino‐
l
‐glutamate to produce
N
‐formyl‐
l
‐glutamate and ammonia. The enzyme from
Pseudomonas aeruginosa
is a dimer in solution and residues in the active site bind one divalent metal ion in a distorted trigonal bipyramidal coordination geometry.
Palladium‐Catalyzed Three‐Component Reaction of 3‐(Tri‐n‐ butylstannyl)allyl Acetates, Aldehydes, and Triorganoboranes: An Alternative to the Carbonyl Allylation Using α,γ‐Substituted Allylic Tin Reagents
Authors: Horino Yoshikazu , Sugata Miki , Abe Hitoshi
Published: March 2016

A three‐component reaction of 3‐(tri‐n‐butylstannyl)allyl acetates, aldehydes, and triorganoboranes in the presence of a palladium‐Xantphos catalyst system predominately gave (E)‐anti‐homoallylic alcohols with high diastereoselectivity and good to high levels of alkene stereocontrol. An efficient chirality transfer was observed when an enantioenriched substrate was employed. The reaction was initiated by the formation of an allylic gem‐palladium/stannyl intermediate, which subsequently underwent allylation of the aldehyde by an allyltributyltin followed by a coupling reaction of the in‐situ‐generated (E)‐vinylpalladium acetate with the triorganoborane.

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Transition Metal‐Free Approach to Propynenitriles and 3‐Chloropropenenitriles
Authors: Sharma Pawan K. , Ram Sita , Chandak Navneet
Published: March 2016

A transition metal‐free, facile and efficient one‐pot protocol for the synthesis of propynenitriles from readily available 3‐chloropropenals is disclosed. The reaction conditions have also been optimized for the exclusive formation and isolation of 3‐chloropropenenitriles which are important building blocks in general and are intermediates in the synthesis of propynenitriles. The hallmark of the methodology is the use of non‐toxic reagents, milder, metal‐free and economically benign reaction conditions avoiding a harsh dehydration step while achieving excellent yields.

magnified image
Hypertrophic neuropathy in Noonan syndrome with multiple lentigines
Authors: Maridet Claire , Sole Guilhem , Morice‐Picard Fanny , Taieb Alain
Published: March 2016

RASopathies comprise several genetic syndromes with mainly cardio–facial–cutaneous manifestations. We report a patient with Noonan syndrome with multiple lentigines (NSML) due to a PTPN11 (p.Thr468Met) mutation associated with hypertrophic neuropathy of lumbar plexus in an adult woman, initially referred for neuropathic pain. Differential diagnosis of neurofibromatosis type 1 (NF1) and other RASopathies is difficult without molecular testing. © 2016 Wiley Periodicals, Inc.
Variation in the human bicondylar angle
Authors: Waxenbaum Erin B. , Stock Michala K.
Published: March 2016

Objectives

Investigations of the human femoral bicondylar angle have largely focused on interspecific differences and intrapopulation variation. This analysis assesses the range of variation in the bicondylar angle in humans across four populations, examining the effects of population, sex and age.

Materials and Methods

The bicondylar angle was assessed in four sex‐ and age‐balanced adult skeletal samples—modern Terry Whites and Blacks and archaeological South Dakota Arikara and Native Alaskans. The overall range of variation was assessed, and variation specific to population, sex, and age analyzed through ANOVAs and post hoc Tukey's honestly significant difference tests.

Results

A one‐way ANOVA highlights a significant effect of population on bicondylar angle; however, the only significant difference occurs between the Terry White and South Dakota Arikara samples. Sex displays a significant effect for the total pooled sample; yet, within population, the effect of sex is significant only among South Dakota Arikara. Age also has a significant effect on bicondylar angle in the total sample; however, the interaction between age and population is not significant.

Conclusion

The results highlight the degree of variation in the bicondylar angle that exists intraspecifically. Differing degrees of variation due to sex suggest that sexual dimorphism is not universal in the human bicondylar angle. Furthermore, the broad impact of age on this feature is discussed, including the potential for plasticity through adulthood. By recognizing and explicitly examining morphological features that vary in human populations, we can appreciate the origins of variation and its implications for locomotor function, human diversity and evolutionary relationships. Am J Phys Anthropol 160:334–340, 2016. © 2016 Wiley Periodicals, Inc.
Solid‐State Conformational Flexibility at Work: Zipping and Unzipping within a Cyclic Peptoid Single Crystal
Authors: Meli Alessandra , Macedi Eleonora , De Riccardis Francesco , Smith Vincent J. , Barbour Leonard J. , Izzo Irene , Tedesco Consiglia
Published: March 2016

A peptidomimetic compound undergoes a reversible single‐crystal‐to‐single‐crystal transformation upon guest release/uptake with the transformation involving a drastic conformational change. The extensive and reversible alteration in the solid state is connected to the formation of an unprecedented “CH–π zipper” which can reversibly open and close (through the formation of CH–π interactions), thus allowing for guest sensing.
Polymorphismus von Amyloidfibrillen in vivo
Authors: Annamalai Karthikeyan , Gührs Karl‐Heinz , Koehler Rolf , Schmidt Matthias , Michel Henri , Loos Cornelia , Gaffney Patricia M. , Sigurdson Christina J. , Hegenbart Ute , Schönland Stefan , Fändrich Marcus
Published: March 2016

Polymorphismus ist ein weit verbreitetes Merkmal von in vitro gebildeten Amyloid‐artigen Fibrillen, doch blieb bislang unklar, ob Amyloidfibrillen in vivo ebenso von diesem Phänomen betroffen sind. Hier zeigen wir, dass sich verschiedene innerhalb eines Patienten gebildete Amyloidfibrillen erheblich in ihrer Morphologie unterscheiden können. Wir erhalten diesen Befund mit Amyloidfibrillen aus verschiedenen Organen, bestehend aus nicht‐homologen Polypeptidketten sowie aus menschlichem und tierischem Gewebe. Unabhängig von Amyloidtyp und ‐herkunft finden wir, dass in vivo gebildete Amyloidfibrillen signifikant polymorphe Eigenschaften aufweisen. Diese Daten lassen darauf schließen, dass die chemischen Grundlagen jener Reaktionen, die in der Selbstorganisation zu Fibrillen zu Polymorphismus führen, in vivo und in vitro grundsätzlich konserviert sind.
Oxidative Conversion of a Europium(II)‐Based T1 Agent into a Europium(III)‐Based paraCEST Agent that can be Detected In Vivo by Magnetic Resonance Imaging
Authors: Funk Alexander M. , Clavijo Jordan Veronica , Sherry A. Dean , Ratnakar S. James , Kovacs Zoltan
Published: March 2016

The EuII complex of 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) tetra(glycinate) has a higher reduction potential than most EuII chelates reported to date. The reduced EuII form acts as an efficient water proton T1 relaxation reagent, while the EuIII form acts as a water‐based chemical exchange saturation transfer (CEST) agent. The complex has extremely fast water exchange rate. Oxidation to the corresponding EuIII complex yields a well‐defined signal from the paraCEST agent. The time course of oxidation was studied in vitro and in vivo by T1‐weighted and CEST imaging.
Decoding the Morphological Diversity in Two Dimensional Crystalline Porous Polymers by Core Planarity Modulation
Authors: Halder Arjun , Kandambeth Sharath , Biswal Bishnu P. , Kaur Gagandeep , Roy Neha Chaki , Addicoat Matthew , Salunke Jagadish K. , Banerjee Subhrashis , Vanka Kumar , Heine Thomas , Verma Sandeep , Banerjee Rahul
Published: March 2016

Two new chemically stable triazine‐ and phenyl‐core‐based crystalline porous polymers (CPPs) have been synthesized using a single‐step template‐free solvothermal route. Unique morphological diversities were observed for these CPPs [2,3‐DhaTta (ribbon) and 2,3‐DhaTab (hollow sphere)] by simply altering the linker planarity. A detailed time‐dependent study established a significant correlation between the molecular level structures of building blocks with the morphology of CPPs. Moreover, a DFT study was done for calculating the interlayer stacking energy, which revealed that the extent of stacking efficiency is responsible for governing the morphological diversity in these CPPs.