Axial GaAs/Ga(As,Bi) Nanowire Heterostructures

Bi-containing III-V semiconductors constitute an exciting class of metastable compounds with wide-ranging potential optoelectronic and electronic applications. However, the growth of III-V-Bi alloys requires group-III-rich growth conditions, which pose severe challenges for planar growth. In this work, we exploit the naturally-Ga-rich environment present inside the metallic droplet of a self-catalyzed GaAs nanowire to synthesize metastable GaAs/GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ axial nanowire heterostructures with high Bi contents. The axial GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ segments are realized with molecular beam epitaxy by first enriching only the vapor-liquid-solid (VLS) Ga droplets with Bi, followed by exposing the resulting Ga-Bi droplets to As$_2$ at temperatures ranging from 270 to 380\,^{\circ}C to precipitate GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ only under the nanowire droplets. Microstructural and elemental characterization reveals the presence of single crystal zincblende GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ axial nanowire segments with Bi contents up to (10$\pm$2)$\%$. This work illustrates how the unique local growth environment present during the VLS nanowire growth can be exploited to synthesize heterostructures with metastable compounds

What is the added sensitivity of non-lateral cervical spine radiographs in the evaluation of acute cervical spine trauma?

PurposePlain radiography of the cervical spine is used as a screening test for trauma patients. We evaluated the diagnostic yield of performing anteroposterior (AP), odontoid, and oblique views in addition to the lateral view in the current era when radiographs are performed only on low-risk patients.MethodsAll imaging reports from cervical spine radiography studies on patients aged 18 years and older in the emergency room of a major academic medical center between November 22, 2003, and January 17, 2012, were retrospectively reviewed. For the clinical workflow employed at the time of study acquisition, radiologists prospectively reviewed the lateral projection and subsequently reviewed the entirety of the images obtained. Exam reports and, when necessary, images were reviewed to determine which patients had fractures and on which projection the fractures were identified.ResultsSix fractures were detected in 7218 exams. Three of these fractures were identified on the lateral radiograph, and three of these fractures were visualized on the additional projections (two on oblique and one on odontoid views). The yield of the additional projections is one fracture per 9713 radiographic projections (90% confidence interval of one fracture per 1245-47,946 examinations). For two of the patients with fractures identified on the lateral projection, an additional fracture was seen when CT was then performed.ConclusionsPerforming additional radiographs of the cervical spine including AP, odontoid, and bilateral oblique projections in trauma patients with low pretest probability of fracture augments the diagnostic yield of lateral radiographs. Considering the potential for devastating neurological outcomes from missed cervical fractures, addition of AP, odontoid, and oblique projections continues to detect fractures at a low rate

Pseudobulges in the Disk Galaxies NGC 7690 and NGC 4593

We present Ks-band surface photometry of NGC 7690 (Hubble type Sab) and NGC 4593 (SBb). We find that, in both galaxies, a major part of the "bulge" is as flat as the disk and has approximately the same color as the inner disk. In other words, the "bulges" of these galaxies have disk-like properties. We conclude that these are examples of "pseudobulges" -- that is, products of secular dynamical evolution. Nonaxisymmetries such as bars and oval disks transport disk gas toward the center. There, star formation builds dense stellar components that look like -- and often are mistaken for -- merger-built bulges but that were constructed slowly out of disk material. These pseudobulges can most easily be recognized when, as in the present galaxies, they retain disk-like properties. NGC 7690 and NGC 4593 therefore contribute to the growing evidence that secular processes help to shape galaxies. NGC 4593 contains a nuclear ring of dust that is morphologically similar to nuclear rings of star formation that are seen in many barred and oval galaxies. The nuclear dust ring is connected to nearly radial dust lanes in the galaxy's bar. Such dust lanes are a signature of gas inflow. We suggest that gas is currently accumulating in the dust ring and hypothesize that the gas ring will starburst in the future. The observations of NGC 4593 therefore suggest that major starburst events that contribute to pseudobulge growth can be episodic.Comment: 10 pages, 3 Postscript figures; requires emulateapj.cls, apjfonts.sty, and psfig.sty; accepted for publication in ApJ; for a version with full resolution figures, see http://chandra.as.utexas.edu/~kormendy/n7690.pd

Systematic review: the diagnosis and staging of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.

Background: Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent cause of liver disease in Western countries. The development of non-alcoholic steatohepatitis (NASH) and fibrosis identifies an at-risk group with increased risk of cardiovascular and liver-related deaths. The identification and management of this at-risk group remains a clinical challenge. \ud \ud Aim: To perform a systematic review of the established and emerging strategies for the diagnosis and staging of NAFLD. \ud \ud Methods: Relevant research and review articles were identified by searching PubMed, MEDLINE and EMBASE. \ud Results: There has been a substantial development of non-invasive risk scores, biomarker panels and radiological modalities to identify at-risk patients with NAFLD without recourse to liver biopsy on a routine basis. These modalities and algorithms have improved significantly in their diagnosis and staging of fibrosis and NASH in patients with NAFLD, and will likely impact on the number of patients undergoing liver biopsy. \ud \ud Conclusions: Staging for NAFLD can now be performed by a combination of radiological and laboratory techniques, greatly reducing the requirement for invasive liver biopsy

A cognitive framework for the categorisation of auditory objects in urban soundscapes

Categorisation is a fundamental cognitive process that plays a central role in everyday behaviour and action. Whereas previous studies have investigated the categorisation of isolated everyday sounds, this paper presents an experiment to investigate the cognitive categorisation of everyday sounds within their original context. A group of eighteen expert and non-expert listeners took part in a free sorting task using 110 sounds identified within ambisonic reproductions of urban soundscapes. The participants were asked to sort the objects into groups of sounds that served a similar purpose in the overall perception of the soundscape. Following this, the participants were asked to provide descriptive labels for the groups they had formed. The results were analysed using hierarchical agglomerative clustering and non-metric multidimensional scaling (MDS) to explore both the structure and dimensionality of the data. The resulting hierarchical clustering of objects show three top level categories relating to transient sounds, continuous sounds, and speech and vocalisations. Sub-categories were identified in each of the top level categories which included harmonic and non-harmonic continuous sounds, clear speech, unintelligible speech, vocalisations, transient sounds that indicate actions, and non-salient transient sounds. The first two dimensions revealed by the MDS analysis relate to temporal extent and intelligibility respectively. Interpretation of the third dimension is less clear, but may be related to harmonic content

Fish larval nutrition and feed formulation: knowledge gaps and bottlenecks for advances in larval rearing

Despite considerable progress in recent years, many questions regarding fish larval nutrition remain largely unanswered, and several research avenues remain open. A holistic understanding of the supply line of nutrients is important for developing diets for use in larval culture and for the adaptation of rearing conditions that meet the larval requirements for the optimal presentation of food organisms and/or microdiets. The aim of the present review is to revise the state of the art and to pinpoint the gaps in knowledge regarding larval nutritional requirements, the nutritional value of live feeds and challenges and opportunities in the development of formulated larval diets.Norwegian Ministry of Fisheries; Research Council of Norway [CODE-199482, GutFeeling-190019]; Spanish Ministry of Science and Innovation MICINN + FEDER/ERDF [AGL2007-64450-C02-01, CSD2007-0002]; project HYDRAA [PTDC/MAR/71685/2006]; Fundacao para a Ciencia e a Tecnologia (FCT), Portugal; FEDER; EC [LIFECYCLE- 222719]; EU RTD [FA0801]info:eu-repo/semantics/publishedVersio

H2A.Bbd: an X-chromosome-encoded histone involved in mammalian spermiogenesis

Despite the identification of H2A.Bbd as a new vertebrate-specific replacement histone variant several years ago, and despite the many in vitro structural characterizations using reconstituted chromatin complexes consisting of this variant, the existence of H2A.Bbd in the cell and its location has remained elusive. Here, we report that the native form of this variant is present in highly advanced spermiogenic fractions of mammalian testis at the time when histones are highly acetylated and being replaced by protamines. It is also present in the nucleosomal chromatin fraction of mature human sperm. The ectopically expressed non-tagged version of the protein is associated with micrococcal nuclease-refractory insoluble fractions of chromatin and in mouse (20T1/2) cell line, H2A.Bbd is enriched at the periphery of chromocenters. The exceedingly rapid evolution of this unique X-chromosome-linked histone variant is shared with other reproductive proteins including those associated with chromatin in the mature sperm (protamines) of many vertebrates. This common rate of evolution provides further support for the functional and structural involvement of this protein in male gametogenesis in mammals

Social Class

Discussion of class structure in fifth-century Athens, historical constitution of theater audiences, and the changes in the comic representation of class antagonism from Aristophanes to Menander

Seyfert galaxies in UZC-Compact Groups

We present results concerning the occurrence of Seyfert galaxies in a new automatically selected sample of nearby Compact Groups of galaxies (UZC-CGs). Seventeen Seyferts are found, constituting ~3% of the UZC-CG galaxy population. CGs hosting and non-hosting a Seyfert member exhibit no significant differences, except that a relevant number of Sy2 is found in unusual CGs, all presenting large velocity dispersion (sigma > 400 km/s), many neighbours and a high number of ellipticals. We also find that the fraction of Seyferts in CGs is 3 times as large as that among UZC-single-galaxies, and results from an excess of Sy2s. CG-Seyferts are not more likely than other CG galaxies to present major interaction patterns, nor to display a bar. Our results indirectly support the minor-merging fueling mechanism.Comment: 12 pages, 5 figures, A&A, accepte