bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictors of severity and mortality in children hospitalized with respiratory syncytial virus infection in a tropical region
Authors: Rodríguez Diego Andrés , Rodríguez‐Martínez Carlos E. , Cárdenas Andrea Constanza , Quilaguy Ivonne Emilce , Mayorga Leydy Yasmin , Falla Luz Marlesvy , Nino Gustavo
Published: February 2013

Introduction

Respiratory syncytial virus (RSV) is one of the leading causes of acute lower respiratory infection (ALRI) in infants and young children. Although ALRI is a major public health problem in developing countries located in tropical areas, studies about RSV epidemiology in these regions are scarce.

Methods

In a retrospective cohort study, we investigated the epidemiology and predictive variables that reflect disease severity and mortality in young children hospitalized with ALRI due to RSV in Colombia, South‐America, during a 2‐year period (2009–2011).

Results

Of a total of 6,344 children with a diagnosis of ALRI, we selected 2,147 (33.8%) that were positive for RSV. After controlling for pre‐existing conditions, we found that independent predictors of severe disease in our population included age <6 months (RR 2.01; CI 95% 1.70–2.38; P < 0.001), prematurity (RR 1.61; CI 95% 1.20–2.17; P = 0.001), congenital heart disease (RR 2.03; CI 95% 1.16–3.54; P = 0.013), and mixed RSV‐adenovirus infection (RR 2.09; CI 95% 1.60–2.73; P < 0.001). Multivariate analysis identified that cancer (RR 31.60; CI 95% 5.97–167.13; P < 0.001) is a predictor of mortality in our RSV‐infected pediatric population independently of age and other co‐morbidities.

Conclusions

RSV is an important cause of ALRI in infants and young children living in tropical regions, especially during the rainy season. The identified predictors of severe disease and mortality should be taken into account when planning interventions to reduce the burden of ALRI in young children living in these regions. Pediatr Pulmonol. 2014; 49:269–276. © 2013 Wiley Periodicals, Inc.
Quantum effects in silicon for photovoltaic applications
Authors: Ingenhoven P. , Anopchenko A. , Tengattini A. , Gandolfi D. , Sgrignuoli F. , Pucker G. , Jestin Y. , Pavesi L. , Balboni R.
Published: February 2013

Quantum confinement effects in silicon might help to overcome the theoretical efficiency limit of ∼33% of silicon cells [Shockley and Queisser, J. Appl. Phys. 32, 510 (1961)]. The dominant loss mechanism in solar cells is the thermalization of photo‐excited carriers to the band gap. Engineering of the band gap makes it in principle possible to obtain a conversion efficiency of ∼44% [Pavesi and Turan (eds.), Silicon Nanocrystals, Fundamentals Synthesis and Application (Wiley‐VCH, Berlin, 2010)]. Band gap engineering is achieved by controlling the silicon‐nanocrystal (Si‐NC) dimension. We currently use Si‐NCs in solar cells to modify the solar spectrum in a way that the incoming light is more efficiently converted into electricity and also, to realize multiple junction cells to minimize thermalization losses. The Si‐NC energy of the band gap and the Si‐NC optical properties depend strongly on the NC size, which can be controlled by the processing parameters. Therefore, light management is possible by varying the refractive index of the Si‐NCs to improve the antireflective coating (ARC) and by conversion of absorbed high energy photons re‐emitted in the red spectral region of light. Thus, in this approach Si‐NCs are used as spectral down‐shifters and for ARC optimization. Further, NCs allow the fabrication of higher band gap solar cells, to be used on top of standard silicon cells as tandem cell elements. Due to the tunability of the band gap, it is possible to construct all silicon multilayer or tandem cells. The concepts and research results for both ideas will be presented.
Objective tracking of African Easterly Waves in Met Office models
Authors: Bain C. L. , Williams K. D. , Milton S. F. , Heming J. T.
Published: February 2013

A simple and computationally efficient objective tracking technique is used to assess the representation of African Easterly Waves (AEWs) in the Met Office Unified Model (MetUM). The algorithm takes Hovmöller diagrams of curvature vorticity at 700 hPa and uses object‐orientated image processing to identify the propagating waves. We use the tracking to evaluate how well AEWs are captured by the MetUM in comparison to ERA‐Interim reanalysis and GPCP rainfall data. The waves are inspected from a dynamical perspective and also from a rainfall‐coupling perspective. The results show that the MetUM is able to capture AEW features at weather forecasting and climate time‐scales and has reasonable representation of the large‐scale dynamics. Some rainfall coupling to waves is also captured in the forecasts. However, it is found that the rainfall enhancement due to wave passage is underestimated by the models, as is the strength and frequency of AEWs. Potential causes of forecast deficiency are investigated and both resolution and changes to convective parametrisation are found to have impacts on model performance. The implications for future model development over Africa are discussed and it is suggested that good convection representation within models is of key importance to realistic simulations of AEWs and their coupling to West African rainfall.
Identification of a novel ‘aggregation‐prone’/‘amyloidogenic determinant’ peptide in the sequence of the highly amyloidogenic human calcitonin
Authors: Iconomidou Vassiliki A. , Leontis Aristeidis , Hoenger Andreas , Hamodrakas Stavros J.
Published: February 2013

TAMLGT peptide and TAMLGT peptide bind by electron microscopy (View interaction)
Negative regulation of TBK1‐mediated antiviral immunity
Authors: Zhao Wei
Published: February 2013

TANK‐binding kinase 1 (TBK1) plays pivotal roles in antiviral innate immunity. TBK1 mediates the activation of interferon regulatory factor (IRF) 3, leading to the induction of type I IFNs (IFN‐α/β) following viral infections. TBK1 must be tightly regulated to effectively control viral infections and maintain immune homeostasis. TBK1 activity can be regulated in a variety of ways, such as phosphorylation, ubiquitination, kinase activity modulation and prevention of functional TBK1‐containing complexes formation. Furthermore, multiple viruses have evolved elaborate strategies to circumvent IFN responses by targeting TBK1. Here we provide an overview of TBK1 in antiviral immunity and recent developments on the regulation of TBK1 activity.
Nested introns in an intron: Evidence of multi‐step splicing in a large intron of the human dystrophin pre‐mRNA
Authors: Suzuki Hitoshi , Kameyama Toshiki , Ohe Kenji , Tsukahara Toshifumi , Mayeda Akila
Published: February 2013

The mechanisms by which huge human introns are spliced out precisely are poorly understood. We analyzed large intron 7 (110 199 nucleotides) generated from the human dystrophin (DMD) pre‐mRNA by RT‐PCR. We identified branching between the authentic 5′ splice site and the branch point; however, the sequences far from the branch site were not detectable. This RT‐PCR product was resistant to exoribonuclease (RNase R) digestion, suggesting that the detected lariat intron has a closed loop structure but contains gaps in its sequence. Transient and concomitant generation of at least two branched fragments from nested introns within large intron 7 suggests internal nested splicing events before the ultimate splicing at the authentic 5′ and 3′ splice sites. Nested splicing events, which bring the authentic 5′ and 3′ splice sites into close proximity, could be one of the splicing mechanisms for the extremely large introns.
Inflammatory fibroid polyp of rectum mimicking rectal cancer
Authors: Jin Jong‐Shiaw , Wu Chiao‐Sen , Yeh Chih‐Haw , Huang Bee‐Piao , Tsao Tang‐Yi
Published: February 2013

Inflammatory fibroid polyps (IFPs) are rare benign tumors of the rectum. Mutation and activating platelet‐derived growth factor receptor alpha (PDGFRA) contribute to tumor development. We present a case of IFPs in the middle rectum that mimic rectal cancer. A 65‐year‐old woman presented with the symptom of fresh blood in the stool and body weight loss of 6 kg in the preceding 3 weeks. A rectal polypoid tumor was noted upon digital examination. Sigmoidoscopy showed a middle rectal tumor measuring 3 × 2.7 cm with obstruction. Computed tomography (CT) scans of the abdomen showed a rectal tumor that had invaded the sacral bone and was associated with four enlarged lymph nodes greater than 1 cm. The radiological report suggested a diagnosis of rectal cancer with lymph node metastases. To remove the obstruction, the patient was initially treated with excision of the tumor and loop sigmoidal colostomy to the abdomen wall. Total mesorectal resection of rectal and sacral tumor followed 10 days later. Histopathological examination of the rectal and sacral tumor showed proliferation of vessels, fibroblast‐like spindle cells, and mixed inflammatory cells, including the plasma cells and eosinophils. The spindle cells were diffusely positive to PDGFRA and were focal positive to CD34 and smooth muscle actin. Based on histopathological and immunohistochemical findings, the diagnosis of IFP is indicated. This was the first reported case of IFPs of the rectum presenting with lymph node enlargement and attachment to the sacrum mimicking rectal cancer.
Evaluation der Integrierten Versorgung Gesundes Kinzigtal: Bisherige Ergebnisse
Authors: Siegel Achim , Stößel Ulrich
Published: February 2013

Einleitung

Die Integrierte Versorgung Gesundes Kinzigtal (IVGK) ist ein populationsbezogenes integriertes Versorgungssystem. Hauptziel der IVGK ist es, sowohl den Gesundheitsnutzen der Versicherten als auch die Versorgungseffizienz zu erhöhen. Im Beitrag werden zunächst die Grundzüge des Versorgungssystems vorgestellt und die bisher vorliegenden finanziellen Ergebnisse der IVGK zusammengefasst. Anschließend gehen die Autoren auf die externe Evaluation der Versorgungsqualität ein und berichten bisherige Ergebnisse bzw. Ergebnistendenzen.
Non-modal stability of round viscous jets
Authors: Boronin S. A. , Healey J. J. , Sazhin S. S.
Published: February 2013

Hydrodynamic stability of round viscous fluid jets is considered within the framework of the non-modal approach. Both the jet fluid and surrounding gas are assumed to be incompressible and Newtonian; the effect of surface capillary pressure is taken into account. The linearized Navier–Stokes equations coupled with boundary conditions at the jet axis, interface and infinity are reduced to a system of four ordinary differential equations for the amplitudes of disturbances in the form of spatial normal modes. The eigenvalue problem is solved by using the orthonormalization method with Newton iterations and the system of least stable normal modes is found. Linear combinations of modes (optimal disturbances) leading to the maximum kinetic energy at a specified set of governing parameters are found. Parametric study of optimal disturbances is carried out for both an air jet and a liquid jet in air. For the velocity profiles under consideration, it is found that the non-modal instability mechanism is significant for non-axisymmetric disturbances. The maximum energy of the optimal disturbances to the jets at the Reynolds number of 1000 is found to be two orders of magnitude larger than that of the single mode. The largest growth is gained by the streamwise velocity component.
‘Threatening’ China and US security: the international politics of identity
Authors: TURNER OLIVER
Published: February 2013

China's increasing capabilities are a central focus of modern day US security concerns. The International Relations literature is a key forum for analyses of the so-called ‘China threat’ and yet it remains relatively quiet on the role of ideas in the construction and perpetuation of the dangers that country is understood to present. This article reveals that throughout history ‘threats’ from China towards the United States, rather than objectively verifiable phenomena, have always been social constructions of American design and thus more than calculations of material forces. Specifically, it argues that powerful and pervasive American representations of China have been repeatedly and purposefully responsible for creating a threatening identity. It also demonstrates that these representations have enabled and justified US China policies which themselves have reaffirmed the identities of both China and the United States, protecting the latter when seemingly threatened by the former. Three case studies from across the full duration of Sino-American relations expose the centrality of ideas to historical and contemporary understandings of China ‘threats’, and to the American foreign policies formulated in response.
Gender and agreement processing in children with Developmental Language Disorder
Authors: RAKHLIN NATALIA , KORNILOV SERGEY A. , GRIGORENKO ELENA L.
Published: February 2013

Two experiments tested whether Russian-speaking children with Developmental Language Disorder (DLD) are sensitive to gender agreement when performing a gender decision task. In Experiment 1, the presence of overt gender agreement between verbs and/or adjectival modifiers and postverbal subject nouns memory was varied. In Experiment 2, agreement violations were introduced and the targets varied between words, pseudo-words, or pseudo-words with derivational suffixes. In both experiments, children with DLD did not differ from typically developing children in their reaction time or sensitivity to agreement features. In both groups, trials with feminine gender resulted in a higher error rate. Children with DLD displayed lower overall accuracy, which was related to differences in phonological memory in both experiments. Furthermore, in Experiment 1 group differences were not maintained after phonological memory was entered as a covariate. The results are discussed with respect to various processing and linguistic theories of DLD.
Birds, Burials and Sacred Cosmology of the Indigenous Beothuk of Newfoundland, Canada
Authors: Kristensen Todd J. , Holly Donald H.
Published: February 2013

The Indigenous Beothuk of Newfoundland disappeared as a cultural entity in the early nineteenth century. Prior to this, the Beothuk had few direct interactions with Europeans, and those that occurred were generally of a hostile nature. As a result, very little is known about Beothuk religious life. Drawing on available ethnohistoric records, an analysis of burial site locations and funerary objects, we offer an interpretation of Beothuk sacred cosmology that places birds at the centre of their belief system.
Brain Disorder and Rock Art
Authors: Bednarik Robert G.
Published: February 2013

Prompted by numerous endeavours to link a variety of brain illnesses/conditions with the introduction of palaeoart, especially rock art, the author reviews these proposals in the light of the causes of these psychiatric conditions. Several of these proposals are linked to the assumption that palaeoart was introduced through shamanism. It is demonstrated that there is no simplistic link between shamanism and brain disorders, although it is possible that some of the relevant susceptibility alleles might be involved in some shamanic experiences. Similarly, no connection between rock art and shamanism has been credibly demonstrated. Moreover, the time frame applied in all these hypotheses is fallacious for several reasons. These notions are all based on the belief that palaeoart was introduced by ‘anatomically modern humans’ and on the replacement hypothesis. Finally, the assumption that neuropathologies and shamanism preceded the advent of palaeoart is also suspect. These numerous speculations derive from neglect of the relevant empirical factors, be they archaeological or neurological.
The Cognitive Implications of Controlled Fire Use by Early Humans
Authors: Twomey Terrence
Published: February 2013

This article proposes a framework for investigating the cognitive implications of controlled fire use by Middle Pleistocene humans. By identifying the simplest strategies they could have used to control fire, given the constraints individuals had to overcome, we can establish a behavioural basis for making inferences about cognition. Accessing, maintaining and benefiting from fire involved a range of behaviours that imply future-directed planning, response inhibition and group-level cooperation. I argue that we can infer human cognitive abilities such as an extended working memory, episodic memories, collective intentionality and intersubjective communication from these fire-related behaviours.
Which dimensions of food-related lifestyle are likely to be associated with obesity in Italy?
Authors: Saba Anna , Cupellaro Elena , Vassallo Marco
Published: February 2013

Objective

To compare obesev. non-obese consumers in terms of their general food-related lifestyles and to explore possible food-related factors affecting obesity in Italy.

Design

The data were collected using a self-completion questionnaire. Data included sociodemographic information, measures of the Food-Related Lifestyle scale (FRL) and self-reported weight and height. A logistic regression model was fitted for the sample with obesity as the dependent variable and sociodemographic characteristics and FRL dimensions as the independent variables.

Setting

The survey was carried out in Italy between October and November 2010.

Subjects

One thousand respondents were recruited with equal quotas for menv. women. The sample was representative of the Italian population in term of age groups and geographic areas. The participants were over 18 years of age and were solely or jointly responsible for the family's food shopping.

Results

Our analyses revealed that sociodemographic, economic and cultural variables affect the increasing rate of obesity in Italy. Obese respondents appeared to find more enjoyment from shopping and interest in cooking compared with non-obese ones. Moreover, they were more likely to find self-fulfilment in foods. However, obese respondents appeared to be less interested in the nutritional content of foods, suggesting their weak involvement in nutritional aspects when they eat. In fact, the obese respondents gave preference to snacks over meals.

Conclusions

The outcome of the study would suggest that in targeted interventions for public health purposes in order to address obesity, attention should be placed on the role that food plays in obese consumers’ lives.
SELECTIVE WITHDRAWAL OF A TWO-LAYER VISCOUS FLUID
Authors: COSGROVE JASON M. , FORBES LAWRENCE K.
Published: February 2013

Selective withdrawal of a two-layer fluid is considered. The fluid layers are weakly compressible, miscible and viscous and therefore flow rotationally. The lower, denser fluid flows with constant velocity out through one or more drain holes in the bottom of a rectangular tank. The drain is opened impulsively and the subsequent draw-down produces waves in the interface which travel outward to the edges of the tank and are reflected back with a $18{0}^{\circ } $ change of phase. The points on the interface that have the highest absolute gradient form regions of high vorticity in the tank, enabling mixing of the fluids. An inviscid linearized interface is computed and compared to contour plots of density for the viscous solution. The two agree closely at early times in the withdrawal process, but as time increases, nonlinear and viscous effects take over. The time at which the lighter fluid starts to flow out of the tank is dependent on the number of drains, their width, and the fluid flow rate and density, and is investigated here.
Hauterscheinungen bei Nierenkrankheiten
Authors: Häusermann
Published: February 2013

Les manifestations cutanées en cas de maladies des reins sont souvent spécifiques et peuvent ainsi, lors d'une analyse approfondie du tégument, signaler une pathologie des organes internes. A part un certain nombre de syndromes héréditaires et de maladies liées à des symptômes cutanés et rénaux, des anomalies de la peau spécifiques et non spécifiques sont principalement mentionnées en cas d'une insuffisance rénale chronique. Par rapport à une représentation détaillée des possibilités thérapeutiques, la priorité est accordée à la description macroscopique et microscopique des anomalies de la peau et aux mécanismes pathophysiologiques.
Ungewöhnliche Ursache von Erythema nodosum, Pleuraerguss und reaktiver Arthritis: Giardia lamblia
Authors: Steiger  , Weber
Published: February 2013

Ein 36-jähriger Mann wurde uns zugewiesen zur Abklärung von Gelenkschmerzen und indurierter Hautrötung, nachdem ein halbes Jahr zuvor ein ätiologisch unklarer Pleuraer- guss rechts diagnostiziert worden war. Bei der diagnostisch unklaren Situation führten Allgemeinsymptome wie leichter Gewichtsverlust und Subfebrilität zusammen mit der Herkunft des Patienten zu einer Stuhluntersuchung, welche die Diagnose einer Infektion mit Giardia lamblia ergab; die Behandlung mit Metronidazol war erfolgreich. Dies ist der erste beschriebene Fall einer Giardia lamblia Infektion mit gleichzeitigem Erythema nodosum, Pleuraerguss und reaktiver Arthritis.
Legionellose, ein Tourismusproblem?
Authors: Kistler  , Fleisch  , Reinhart  , Wieland
Published: February 2013

La légionellose, un problème de tourisme? La légionellose est une maladie assez rare, mais elle suit souvent un cours prolongé et compliqué, même chez des patients immunocompétents. Le diagnostic est important pour des raisons thérapeutiques et épidémiologiques. De 1998 à 2001 on a observé à l'hôpital cantonal de Coire six cas de légionellose, dont quatre étaient associés aux voyages et un autre concernait un employé d'un hôtel local. Par suite de l'augmentation de la mobilité internationale les recherches épidémiologiques sur la localisation de la source infectieuse et les procédés hygiéniques deviennent plus difficiles. Une organisation européenne, le «European Working Group for Legionella Infections» (EWGLI/www.ewgli.org) a étudié ce problème. La question de la forme sous laquelle le public doit être informé des sources de légionelles fait l'object d'une discussion.
Pränatale Stammzelltransplantation und Gentherapie zur Behandlung genetischer Krankheiten
Authors: Surbek  , Holzgreve
Published: February 2013

Die vorgeburtliche Transplantation hämatopoietischer Stammzellen ist eine neue, vielversprechende Behandlungsmöglichkeit angeborener Krankheiten, welche früh in der Schwangerschaft diagnostiziert werden können. Kürzlich wurde über die ersten klinischen Erfolge berichtet. Bei vielen genetischen Krankheiten bestehen bisher noch einige Hindernisse, die einen durchschlagenden therapeutischen Effekt verhindern. Neuere Strategien zur Verbesserung dieser Therapie wie z.B. Manipulation des Transplantats, Konditionierung des Empfängers und der gentherapeutische Ansatz wurden nun entwickelt. Die Verwendung nicht-hämatopoietischer oder pluripotenter Stammzellen wird möglicherweise in naher Zukunft zu einer weiteren Entwicklung der Möglichkeiten dieser neuen, innovativen Therapiemethode führen. Ethische Aspekte insbesondere bezüglich der fetalen Gentherapie und der Verwendung pluripotenter Stammzellen müssen begleitend dazu schwerpunktmässig evaluiert werden.
Transgene Pflanzen
Authors: Blum
Published: February 2013

Die molekularbiologische Forschung und rekombinante DNA-Technologie hat in den letzten Jahren nicht nur die Diagnostik, Therapie und Prävention in der Humanmedizin revolutioniert, sondern auch zu enormen Entwicklungen auf dem Gebiet der Pflanzenbiotechnologie geführt. So ist es heute möglich, eine Vielzahl von Antigenen, Antikörpern und Medikamenten in transgenen Pflanzen herzustellen. Neben den Grundlagen der molekularen Pflanzengenetik und der Herstellung transgener Pflanzen werden in dieser Übersicht der aktuelle Stand der Herstellung biomedizinisch relevanter «Pflanzenprodukte», deren weitere Perspektiven, aber auch die potenziellen Probleme aufgezeigt. Es ist eine der besonderen Herausforderungen der modernen Medizin, auch an den klinisch tätigen Mediziner in einem zunehmend informierten Umfeld, die neuen biotechnologischen Verfahren zu kennen und zu verstehen, um ihren aktuellen und zukünftigen Stellenwert für Klinik und Praxis qualifiziert beurteilen zu können.
Molekulare Diagnostik in der Gastroenterologie
Authors: Weizsäcker  , Blum
Published: February 2013

Molekularbiologische Methoden sind zu einem festen Bestandteil der Medizin geworden. Insbesondere im Bereich der Diagnostik haben sie neue Perspektiven für Früherkennung, Klassifizierung und Therapieplanung bei einer Vielzahl von Erkrankungen eröffnet. Der vorliegende Beitrag erörtert Prinzip und Anwendungspotential molekularer Verfahren am Beispiel des kolorektalen Karzinoms.
Benigne rekurrierende intrahepatische Cholestase
Authors: Ramseier
Published: February 2013

Vorgestellt wird ein junger türkischer Patient, welcher sich mit einer intrahepatischen Cholestase präsentierte. Er erlebte mehrere Episoden mit Ikterus und Pruritus, welche jeweils für mehrere Wochen bis Monate persistieren und spontan abklangen. Die erste Episode erlitt er im Alter von fünf Jahren. Nach ausgedehnten Abklärungen mittels Bildgebung, laborchemischen Untersuchungen und Leberbiopsie konnte die Diagnose «benigne rekurrierende intrahepatische Cholestase» gestellt werden. Dies ist eine sehr seltene benigne autosomal-rezessive Erkrankung als Folge einer genetischen Mutation. Bei rekurrierenden Cholestasen mit Beginn im Kindesalter ist an diese Diagnose zu denken.
Wirtschaftlichkeit des Einsatzes von Irbesartan bei Patienten mit Typ-2 Diabetes, Hypertonie und Nephropathie in der Schweiz
Authors: Frei  , Palmer  , Burnier  , Hess
Published: February 2013

Die IDNT-Studie (Irbesartan in Diabetic Nephropathy Trial) zeigte bei Patienten mit Typ-2 Diabetes, Hypertonie und Nephropathie eine relative Reduktion des kombinierten Endpunktes (Verdoppelung des Serumkreatinins, terminales Nierenversagen und Tod) um 20% unter Behandlung mit Irbesartan im Vergleich zu Amlodipin oder Placebo (antihypertensive Standardbehandlung) auf. Ziel dieser Studie war, die langfristigen gesundheitsökonomischen Auswirkungen dieser Behandlungsstrategie für die Schweiz zu untersuchen. Unter Verwendung eines Markov-Modells wurden für jede der drei Behandlungsoptionen aus der IDNT-Studie die Progression der Nephropathie simuliert und die gewonnene Anzahl Lebensjahre sowie die Behandlungskosten über zehn Jahre errechnet. Zusätzlich wurden verschiedene Sensitivitätsanalysen durchgeführt. Durch die Behandlung mit Irbesartan resultierten bei einer verlängerten Lebenserwartung Einsparungen von 22681 Franken pro Patient im Vergleich zu Amlodipin und von 13847 Franken im Vergleich zu einer antihypertensiven Standardtherapie.
Kirkpatrick-Baez microscope for hard X-ray imaging of fast ignition experiments
Authors: Friesen H. , Tiedje H. F. , Hey D. S. , Mo M. Z. , Beaudry A. , Fedosejevs R. , Tsui Y. Y. , Mackinnon A. , McLean H. S. , Patel P. K.
Published: February 2013

A Kirkpatrick-Baez X-ray microscope has been developed for use on the Titan laser facility at the Lawrence Livermore National Laboratory in Fast Ignition experiments. It was developed as a broadband alternative to narrow band Bragg crystal imagers for imaging Kα emission from tracer layers. A re-entrant design is employed which allows for alignment from outside the chamber. The mirrors are coated with Pt and operate at a grazing incident angle of 0.5° providing higher resolution than an equal brightness pinhole and sufficient bandwidth to image thermally shifted characteristic Kα emission from heated Cu tracer layers in Fast Ignition experiments. The superpolished substrates (<1 Å rms roughness) had a final visible wavelength roughness of 1.7 Å after coating, and exhibited a reflectivity corresponding to an X-ray wavelength roughness of 7 ± 1 Å. A unique feature of this design is that during experiments, the unfiltered direct signal along with the one-dimensional reflections are retained on the detector in order to enable a live indication of alignment and incident angle. The broad spectral window from 4 to 9 keV enables simultaneous observation of emission from several spectral regions of interest, which has been demonstrated to be particularly useful for cone-wire targets. An experimentally measured resolution of 15 μm has been obtained at the center of the field of view.
A sequence-dependent rigid-base model of DNA
Authors: Gonzalez O. , Petkevičiūtė D. , Maddocks J. H.
Published: February 2013

A novel hierarchy of coarse-grain, sequence-dependent, rigid-base models of B-form DNA in solution is introduced. The hierarchy depends on both the assumed range of energetic couplings, and the extent of sequence dependence of the model parameters. A significant feature of the models is that they exhibit the phenomenon of frustration: each base cannot simultaneously minimize the energy of all of its interactions. As a consequence, an arbitrary DNA oligomer has an intrinsic or pre-existing stress, with the level of this frustration dependent on the particular sequence of the oligomer. Attention is focussed on the particular model in the hierarchy that has nearest-neighbor interactions and dimer sequence dependence of the model parameters. For a Gaussian version of this model, a complete coarse-grain parameter set is estimated. The parameterized model allows, for an oligomer of arbitrary length and sequence, a simple and explicit construction of an approximation to the configuration-space equilibrium probability density function for the oligomer in solution. The training set leading to the coarse-grain parameter set is itself extracted from a recent and extensive database of a large number of independent, atomic-resolution molecular dynamics (MD) simulations of short DNA oligomers immersed in explicit solvent. The Kullback-Leibler divergence between probability density functions is used to make several quantitative assessments of our nearest-neighbor, dimer-dependent model, which is compared against others in the hierarchy to assess various assumptions pertaining both to the locality of the energetic couplings and to the level of sequence dependence of its parameters. It is also compared directly against all-atom MD simulation to assess its predictive capabilities. The results show that the nearest-neighbor, dimer-dependent model can successfully resolve sequence effects both within and between oligomers. For example, due to the presence of frustration, the model can successfully predict the nonlocal changes in the minimum energy configuration of an oligomer that are consequent upon a local change of sequence at the level of a single point mutation.
Simulation study for adsorption-induced structural transition in stacked-layer porous coordination polymers: Equilibrium and hysteretic adsorption behaviors
Authors: Numaguchi Ryohei , Tanaka Hideki , Watanabe Satoshi , Miyahara Minoru T.
Published: February 2013

We conduct grand canonical Monte Carlo simulations and a free-energy analysis for a simplified model of a stacked-layer porous coordination polymer to understand the gate phenomenon, which is a structural transition of a host framework induced by the adsorption of guest particles. Our calculations demonstrate that stabilization of the system due to the guest adsorption causes host deformation under thermodynamic equilibrium. We also investigate spontaneous transition behaviors (gate opening and closing under metastable conditions). The structural transition should occur when the required activation energy, which is determined using the free-energy analysis, becomes equal to the system energy fluctuation. To estimate the system energy fluctuation, we construct a kinetic transition model based on the transition state theory. In this model, the system energy fluctuation can be calculated by setting the adsorption time and transition domain size of the host framework. The model demonstrates that a smaller domain size results in a gate-opening transition at lower pressure. Furthermore, we reveal that the slope of the logarithm of the equilibrium structural transition pressure versus reciprocal temperature shows transition enthalpy, and that slopes of the gate-opening and -closing transition pressures versus reciprocal temperature show activation enthalpies.
Excitonic states in a (Ti6O12)3 nanotube
Authors: Papas B. N. , Whitten J. L.
Published: February 2013

The low-lying excited electronic states of a (Ti6O12)3 nanotube are investigated using ab initio self-consistent field configuration interaction theory. The transition energies and moments are calculated and the nature of the orbitals involved is discussed. Transitions correspond to an excitation from an O2p to a nearby Ti3d orbital and singlet-singlet transitions vary in excitation energy from 2.1 eV to 4.3 eV, depending on the oxygen site and environment of the titanium site. Two different structures for the three stacked Ti6O12 rings are found. The occluded Ti structure is lower in energy than a staggered structure by 1.25 eV, only 0.02 eV/bond. Excited electronic states are found to correspond to highly localized holes on oxygen and a highly localized electron in a d orbital on a nearest neighbor titanium. The staggered structure has four absorptions that lie within the intense portion of the solar spectrum, at 585 nm, 472 nm, 471 nm, 423 nm; the occluded structure has one strong absorption, at 532 nm.
Scaling between relaxation, transport and caged dynamics in a binary mixture on a per-component basis
Authors: Puosi F. , De Michele C. , Leporini D.
Published: February 2013

The universal scaling between the average slow relaxation/transport and the average picosecond rattling motion inside the cage of the first neighbors has been evidenced in a variety of numerical simulations and experiments. Here, we first show that the scaling does not need information concerning the arbitrarily-defined glass transition region and relies on a single characteristic length scale \documentclass[12pt]{minimal}\begin{document}$\overline{a^2}^{1/2}$\end{document}a2¯1/2 which is determined even far from that region. This prompts the definition of a novel reduced rattling amplitude \documentclass[12pt]{minimal}\begin{document}$\widehat{\langle u^2 \rangle }^{1/2}$\end{document}⟨u2⟩̂1/2 which has been investigated by extensive molecular-dynamics simulations addressing the slow relaxation, the diffusivity, and the fast cage-dynamics of both components of an atomic binary mixture. States with different potential, density, and temperature are considered. It is found that if two states exhibit coinciding incoherent van Hove function on the picosecond timescale, the coincidence is observed at long times too, including the large-distance exponential decay—a signature of heterogeneous dynamics—observed when the relaxation is slow. A major result of the present study is that the correlation plot between the diffusivity of the two components of the binary mixtures and their respective reduced rattling amplitude collapse on the same master curve. This holds true also for the structural relaxation of the two components and the unique master curve coincides with the one of the average scaling. It is shown that the breakdown of the Stokes-Einstein law exhibited by the distinct atomic species of the mixture and the monomers of a chain in a polymer melt is predicted at the same reduced rattling amplitude. Finally, we evidence that the well-known temperature/density thermodynamic scaling of the transport and the relaxation of the mixture is still valid on the picosecond timescale of the rattling motion inside the cage. This provides a link between the fast dynamics and the thermodynamic scaling of the slow dynamics.
Minimal energy packings of nearly flexible polymers
Authors: Hoy Robert S. , Harwayne-Gidansky Jared , O’Hern Corey S.
Published: February 2013

We extend recent studies of the minimal energy packings of short flexible polymers with hard-core-like repulsions and short-range attractions to include bond-angle interactions with the aim of describing the collapsed conformations of “colloidal” polymers. We find that flexible tangent sticky-hard-sphere (t-SHS) packings provide a useful perturbative basis for analyzing polymer packings with nonzero bending stiffness only for small ratios of the stiffnesses for the bond-angle (kb) and pair (kc) interactions, i.e., \documentclass[12pt]{minimal}\begin{document}$k_b^{\rm crit}/k_c \lesssim 0.01$\end{document}kb crit /kc≲0.01 for N < 10 monomers, and the critical ratio decreases with N. Below \documentclass[12pt]{minimal}\begin{document}$k_b^{crit}$\end{document}kbcrit, angular interactions give rise to an exponential (in N) increase in the number of distinct angular energies arising from the diversity of covalent backbone paths through t-SHS packings. As kb increases above \documentclass[12pt]{minimal}\begin{document}$k_b^{crit}$\end{document}kbcrit, the low-lying energy landscape changes dramatically as finite bending stiffness alters the structure of the polymer packings. This study lays the groundwork for exact-enumeration studies of the collapsed states of t-SHS-like models with larger bending stiffness.
Electrochemical hydrogen property improved in nano-structured perovskite oxide LaFeO3 for Ni/MH battery
Authors: Wang Qiang , Deng Gang , Chen Zhiqian , Chen Yungui , Cheng Nanpu
Published: February 2013

Perovskite oxide LaFeO3, as a novel candidate for the electrode of Ni/MH battery, holds high specific capacity and good cyclical durability at elevated temperatures. However, the poor electrochemical kinetics is a bottleneck for the application of this type of material. By use of nano-structured materials, there are greatly enhanced values of exchange current density I0 and hydrogen diffusion coefficient D, which resulted in an improvement of electrochemical kinetics, a much higher specific capacity and excellent stability during cycling for nano-structured LaFeO3. In theory, there is a significant possibility of further advancing the hydrogen reaction kinetics of perovskite type oxides for Ni/MH battery.
Temperature dependent reversal of voltage modulated light emission and negative capacitance in AlGaInP based multi quantum well light emitting devices
Authors: Bansal Kanika , Datta Shouvik
Published: February 2013

We report a reversal in negative capacitance (NC) and voltage modulated light emission from AlGaInP based multi-quantum well (QW) electroluminescent diodes under temperature variation. Unlike monotonically increasing continuous wave light emission with decreasing temperature, modulated electroluminescence and negative capacitance first increase to a maximum and then decrease while cooling down from room temperature. Interdependence of such electronic and optical properties is understood as a competition between defect participation in radiative recombination and field assisted carrier escape from the quantum well region during temperature variation. The temperature of maximum light emission must coincide with the operating temperature of a device for better efficiency.
Transparent ion trap with integrated photodetector
Authors: Eltony Amira M. , Wang Shannon X. , Akselrod Gleb M. , Herskind Peter F. , Chuang Isaac L.
Published: February 2013

Fluorescence collection sets the efficiency of state detection and the rate of entanglement generation between remote trapped ion qubits. Despite efforts to improve light collection using various optical elements, solid angle capture is limited to ≈10% for implementations that are scalable to many ions. We present an approach based on fluorescence detection through a transparent trap using an integrated photodetector, combining collection efficiency approaching 50% with scalability. We microfabricate transparent surface traps with indium tin oxide and verify stable trapping of single ions. The fluorescence from a cloud of ions is detected using a photodiode sandwiched with a transparent trap.
Integrated high-quality factor silicon-on-sapphire ring resonators for the mid-infrared
Authors: Shankar Raji , Bulu Irfan , Lončar Marko
Published: February 2013

We demonstrate high-quality (Q) factor grating-coupled ring resonators in a silicon-on-sapphire platform, operating at wavelengths between 4.3 and 4.6 μm. Total Q-factors of 151 000 and intrinsic Q-factors of 278 000 are measured, representing the highest Q-factors measured at the mid-infrared in Si.
Low temperature direct wafer bonding of GaAs to Si via plasma activation
Authors: Yeo C. Y. , Xu D. W. , Yoon S. F. , Fitzgerald E. A.
Published: February 2013

The present work seeks to demonstrate the elegance and simplicity of monolithic integration via plasma-activated direct wafer bonding. Two-inch gallium arsenide and silicon wafers were directly bonded through argon plasma activation. The highest specific bond energy was found for plasma conditions of 30 s, 120 mTorr, and 200 W, followed by low temperature annealing at 140 °C, and was 478 mJ/m2. Through this process, a processed silicon integrated circuit could be integrated with optoelectronics gallium arsenide on a wafer scale.
Observation of rhombohedral nanostructures in the orthorhombic phase of KNbO3 using convergent-beam electron diffraction
Authors: Tsuda Kenji , Sano Rikiya , Tanaka Michiyoshi
Published: February 2013

Symmetries of nanometer-scale local structures in the rhombohedral and orthorhombic phases of potassium niobate (KNbO3) have been examined using convergent-beam electron diffraction. Nanometer-size local structures with rhombohedral symmetry have been discovered in the orthorhombic phase of KNbO3. It has been found that the structure of the orthorhombic phase of KNbO3 is formed as an average of two variants with rhombohedral symmetry. This fact indicates that the phase transformation between the orthorhombic and rhombohedral phases has an order-disorder character. The result is analogous to the case of BaTiO3, which we already reported [Tsuda et al., Phys. Rev. B 86, 214106 (2012)].
Growth of highly near-c-axis oriented ferroelectric LiNbO3 thin films on Si with a ZnO buffer layer
Authors: You Peng , Lu Chaojing , Ye Wanneng , Hao Lanzhong , Zhu Jun , Zhou Yichun
Published: February 2013

Ferroelectric LiNbO3 thin film of high near-c-axis orientation was grown on Si by pulsed laser deposition using a thin ZnO buffer layer of high c-axis orientation. Both the LiNbO3 film and the ZnO layer consist of columnar grains with random in-plane twist relative to each other. The c axes of LiNbO3 grains tilt small angles with respect to the film growth direction and the deviation angles follow nearly Gaussian probability distribution within 5°. The out-of-plane tilt nucleation of LiNbO3 lattices on the waved surfaces of the ZnO layer leads to the near-c-axis oriented growth of the LiNbO3 film.
Animals in a bacterial world, a new imperative for the life sciences
Authors: McFall-Ngai Margaret , Hadfield Michael G. , Bosch Thomas C. G. , Carey Hannah V. , Domazet-Lošo Tomislav , Douglas Angela E. , Dubilier Nicole , Eberl Gerard , Fukami Tadashi , Gilbert Scott F. , Hentschel Ute , King Nicole , Kjelleberg Staffan , Knoll Andrew H. , Kremer Natacha , Mazmanian Sarkis K. , Metcalf Jessica L. , Nealson Kenneth , Pierce Naomi E. , Rawls John F. , Reid Ann , Ruby Edward G. , Rumpho Mary , Sanders Jon G. , Tautz Diethard , Wernegreen Jennifer J.
Published: February 2013

In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal–bacterial interactions, whether in shared ecosystems or intimate symbioses, is fundamentally altering our understanding of animal biology. Specifically, we highlight recent technological and intellectual advances that have changed our thinking about five questions: how have bacteria facilitated the origin and evolution of animals; how do animals and bacteria affect each other’s genomes; how does normal animal development depend on bacterial partners; how is homeostasis maintained between animals and their symbionts; and how can ecological approaches deepen our understanding of the multiple levels of animal–bacterial interaction. As answers to these fundamental questions emerge, all biologists will be challenged to broaden their appreciation of these interactions and to include investigations of the relationships between and among bacteria and their animal partners as we seek a better understanding of the natural world.
STAT2 deficiency and susceptibility to viral illness in humans
Authors: Hambleton Sophie , Goodbourn Stephen , Young Dan F. , Dickinson Paul , Mohamad Siti M. B. , Valappil Manoj , McGovern Naomi , Cant Andrew J. , Hackett Scott J. , Ghazal Peter , Morgan Neil V. , Randall Richard E.
Published: February 2013

Severe infectious disease in children may be a manifestation of primary immunodeficiency. These genetic disorders represent important experiments of nature with the capacity to elucidate nonredundant mechanisms of human immunity. We hypothesized that a primary defect of innate antiviral immunity was responsible for unusually severe viral illness in two siblings; the proband developed disseminated vaccine strain measles following routine immunization, whereas an infant brother died after a 2-d febrile illness from an unknown viral infection. Patient fibroblasts were indeed abnormally permissive for viral replication in vitro, associated with profound failure of type I IFN signaling and absence of STAT2 protein. Sequencing of genomic DNA and RNA revealed a homozygous mutation in intron 4 ofSTAT2that prevented correct splicing in patient cells. Subsequently, other family members were identified with the same genetic lesion. Despite documented infection by known viral pathogens, some of which have been more severe than normal, surviving STAT2-deficient individuals have remained generally healthy, with no obvious defects in their adaptive immunity or developmental abnormalities. These findings imply that type I IFN signaling [through interferon-stimulated gene factor 3 (ISGF3)] is surprisingly not essential for host defense against the majority of common childhood viral infections.
Refining Ammonia Treatments for Control of Prymnesium parvum in Striped Bass Fingerling Production Ponds
Authors: Wyatt Thomas A , Barkoh Aaron , Schlechte J Warren
Published: February 2013

Texas state fish hatcheries use un-ionized ammonia nitrogen (NH3-N) treatments of 0.14–0.25 mg/L to control Prymnesium parvum in production ponds for phase-1 Striped Bass Morone saxatilis based on a published ammonia tolerance for 4- to 6-d-old Sunshine Bass (female White Bass M. chrysops × male Striped Bass M. saxatilis). Because fingerling production has been inconsistent and the treatments require frequent reapplications to maintain control of P. parvum, we conducted this study to answer two questions: (1) are the treatments developed for Sunshine Bass appropriate for Striped Bass culture, and (2) can the maximum treatments be increased as the fish grow. Striped Bass (4, 10, 20, and 28 d old) were exposed to NH3-N concentrations up to 1.2 mg/L for 96 h. Ammonia concentrations and fish mortalities were monitored at 24-h intervals, their relationship modeled using logistic regression, and ammonia concentrations that 90% of the fish survived during the various exposure periods (maximum treatments) were estimated. The 4- to 6-d-old Striped Bass survived ammonia concentrations similar to those of Sunshine Bass of the same age-group. The 20-d-old fish were the least tolerant of NH3-N, followed by 4-d-old fish and then 10-d-old fish. The 28-d-old fish was the most tolerant of ammonia toxicity. The maximum treatment varied with fish age. Thus, the current practice of treating for concentrations between 0.14 and 0.25 mg NH3-N/L throughout production of phase-1 fish is inappropriate. Treating with 0.14- to 0.25-mg NH3-N/L can be suitable for culture of Striped Bass fry and fingerlings, except for fish in the 22–24-d age range. The upper limit of concentration may be increased up to 0.37 and 0.40 mg NH3-N/L for 10- to 12-d-old and 28- to 30-d-old Striped Bass, respectively. However, the concentration must be lowered to 0.1 mg NH3-N/L for 22- to 24-d-old Striped Bass.