van der Waals epitaxy of monolayer hexagonal boron nitride on copper foil : growth, crystallography and electronic band structure

We investigate the growth of hexagonal boron nitride (h-BN) on copper foil by low pressure chemical vapour deposition (LP-CVD). At low pressure, h-BN growth proceeds through the nucleation and growth of triangular islands. Comparison between the orientation of the islands and the local crystallographic orientation of the polycrystalline copper foil reveals an epitaxial relation between the copper and h-BN, even on Cu(100) and Cu(110) regions whose symmetry is not matched to the h-BN. However, the growth rate is faster and the islands more uniformly oriented on Cu(111) grains. Angle resolved photoemission spectroscopy measurements reveal a well-defined band structure for the h-BN, consistent with a band gap of 6 eV, that is decoupled from the copper surface beneath. These results indicate that, despite a weak interaction between h-BN and copper, van der Waals epitaxy defines the long range ordering of h-BN even on polycrystalline copper foils and suggest that large area, single crystal, monolayer h-BN could be readily and cheaply produced

Visual and auditory perceptual strength norms for 3,596 French nouns and their relationship with other psycholinguistic variables

Perceptual experience plays a critical role in the conceptual representation of words. Higher levels of semantic variables such as imageability, concreteness, and sensory experience are generally associated with faster and more accurate word processing. Nevertheless, these variables tend to be assessed mostly on the basis of visual experience. This underestimates the potential contributions of other perceptual modalities. Accordingly, recent evidence has stressed the importance of providing modality-specific perceptual strength norms. In the present study, we developed French Canadian norms of visual and auditory perceptual strength (i.e., the modalities that have major impact on word processing) for 3,596 nouns. We then explored the relationship between these newly developed variables and other lexical, orthographic, and semantic variables. Finally, we demonstrated the contributions of visual and auditory perceptual strength ratings to visual word processing beyond those of other semantic variables related to perceptual experience (e.g., concreteness, imageability, and sensory experience ratings). The ratings developed in this study are a meaningful contribution toward the implementation of new studies that will shed further light on the interaction between linguistic, semantic, and perceptual systems

Microrollers Flow Uphill as Granular Media

Pour sand into a container and only the grains near the top surface move. The collective motion associated with the translational and rotational energy of the grains in a thin flowing layer is quickly dissipated as friction through multibody interactions. Alternatively, consider what will happen to a bed of particles if one applies a torque to each individual particle. In this paper, we demonstrate an experimental system where torque is applied at the constituent level through a rotating magnetic field in a dense bed of microrollers. The net result is the grains roll uphill, forming a heap with a negative angle of repose. Two different regimes have been identified related to the degree of mobility or fluidization of the particles in the bulk. Velocimetry of the near surface flowing layer reveals the collective motion of these responsive particles scales in a similar way to flowing bulk granular flows. A simple granular model that includes cohesion accurately predicts the apparent negative coefficient of friction. In contrast to the response of active or responsive particles that mimic thermodynamic principles, this system results in macroscopic collective behavior that has the kinematics of a purely dissipative granular system

Evidence For A Precessing Accretion Disk in the Nucleus of NGC 1097

We present new spectroscopic observations of the LINER (and now Seyfert 1) nucleus of NGC 1097, and discuss the evolution of its broad, double-peaked Balmer lines. When originally discovered in 1991, the red peak of the double-peaked H-alpha line was stronger than the blue, while by 1994 the H-alpha profile had become almost symmetric and the integrated line flux had decreased to half its original value. Our new spectrum, taken in 1996, shows that the broad, double-peaked lines have returned to almost their original strengths, the profiles of H-beta and H-alpha are identical to within errors, and the broad-line emitting region is unreddened. However, the profile of the Balmer lines is now such that the blue peak is stronger than the red, opposite to the asymmetry observed in 1991. Various models are considered for the observed behavior, all assuming that the emission lines originate in an accretion disk. We present a refined version of the precessing, planar, elliptical accretion ring model proposed by Storchi-Bergmann et al. and Eracleous et al. This model provides an acceptable fit to the line profiles. We also consider the possibility that the line profile evolution results from a precessing warp in the disk, induced by irradiation from the center, and show that the range of radii and precession time scales expected in this model are consistent with the observations. The sudden appearance of the "disk-like" broad line profiles in NGC 1097 could have resulted from the formation of a new accretion disk due to, for example, the tidal disruption of a star, or the illumination of a pre-existing disk by a transient ionizing source at the center of the disk.Comment: Accepted for publication in the Astrophysical Journal. TeX file with 5 postscript figures embeded using psfig.tex, 13 page

Molecular genetics and pathophysiology of 17 beta-hydroxysteroid dehydrogenase 3 deficiency.

Autosomal recessive mutations in the 17 beta-hydroxysteroid dehydrogenase 3 gene impair the formation of testosterone in the fetal testis and give rise to genetic males with female external genitalia. Such individuals are usually raised as females, but virilize at the time of expected puberty as the result of increases in serum testosterone. Here we describe mutations in 12 additional subjects/families with this disorder. The 14 mutations characterized to date include 10 missense mutations, 3 splice junction abnormalities, and 1 small deletion that results in a frame shift. Three of these mutations have occurred in more than 1 family. Complementary DNAs incorporating 9 of the 10 missense mutations have been constructed and expressed in reporter cells; 8 of the 9 missense mutations cause almost complete loss of enzymatic activity. In 2 subjects with loss of function, missense mutations testosterone levels in testicular venous blood were very low. Considered together, these findings strongly suggest that the common mechanism for testosterone formation in postpubertal subjects with this disorder is the conversion of circulating androstenedione to testosterone by one or more of the unaffected 17 beta-hydroxysteroid dehydrogenase isoenzymes

Description of a new species of the catfish genus Trichomycterus (Teleostei: Siluriformes: Trichomycteridae) from the rio de Contas basin, northeastern Brazil

> Abstract Trichomycterus tete, new species is described from the upper rio de Contas basin, northeastern Brazil. It is the fi rst record of the genus to the Caatinga semi-arid region. The new species is distinguished from all its congeners by having a combination of eight pectoral-fi n rays, the fi rst pectoral-fi n ray prolonged as a fi lament, metapterygoid deeper than wide, short maxillary barbel reaching the middle of opercular patch of odontodes, narrow head (head width 68.07 -77.5% HL), 11 dorsal-fi n rays, caudal fi n truncated, body slender (body depth 12.3 -13.6% SL), shorter dorsal-fi n base (dorsal-fi n base length 9.5 -11.4% SL), and an uncommon color pattern. In addition, T. tete differs from all the congeners from southeastern Brazil by having a deep area at the external edge of the hypobranchial 1. > Resumo Trichomycterus tete, espécie nova é descrita para a bacia do alto rio de Contas, nordeste do Brasil. Esse é o primeiro registro do gênero para a Caatinga, região do semi-árido. A nova espécie difere de todos os seus congêneres por possuir uma combinação de oito raios na nadadeira peitoral, primeiro raio da nadadeira peitoral prolongado como um fi lamento, metapterigóide mais longo que curto, barbilhão maxilar curto, atingindo o meio da placa opercular de odontódeos, cabeça estreita (largura da cabeça, 67,0 -76,2% HL), 11 raios na nadadeira dorsal, nadadeira caudal truncada, menor altura do corpo (altura do corpo, 12.3 -13.6% SL), menor base da nadadeira dorsal (base da nadadeira dorsal, 9,5 -11,4% SL), e pelo padrão de colorido incomum. Além disso, T. tete difere de todos os seus congêneres do Sudeste do Brasil por apresentar uma região muito alargada na extremidade externa do hipobranquial 1. &gt

Validade, Relações Filogenéticas e Redescrição de Eremophilus Candidus Ribeiro, 1949 (Teleostei, Siluriformes, Trichomycteridae)

Trichomycterus candidus (Ribeiro, 1949), originally described in Eremophilus Humboldt, 1805, is redescribed based on the examination of recently collected specimens and type material. The species is diagnosed based on four autapomorphies: enlarged dorsal projection of interopercular patch of odontodes, lack of pelvic fins and girdle, head small and color pattern presenting very small dark brown round spots. The new combination for T. candidus is proposed on the basis of its close relationships with a clade of Trichomycterus from southeastern Brazil, with which it shares four synapomorphies (posterior ceratohyal tip reduced in depth, ventro-posterior process of the posterior ceratohyal absent or vestigial, smaller depth of the posterior projection of opercular patch of odontodes, and color pattern presenting dark brown round spots). Trichomycterus candidus shares with E. mutisii the absence of pelvic fins and girdle, but not the apomorphic pattern of sensorial pores recently established for Eremophilus.Trichomycterus candidus (Ribeiro, 1949), descrita originalmente em Eremophilus Humboldt, 1805, é redescrita com base no exame dos tipos e material recém-coletado. A espécie é diagnosticada com base em quatro autapomorfias: placa interopercular de odontódeos com projeção dorsal alongada, cabeça reduzida, ausência de nadadeiras pélvicas e padrão de colorido apresentando pintas arredondadas castanho-escuro muito pequenas. A nova combinação T. candidus é proposta com base no seu relacionamento próximo a um clado de Trichomycterus do sudeste do Brasil, com o qual compartilha quatro sinapomorfias (extremidade do ceratohial posterior reduzida, processo póstero-ventral do ceratohial posterior ausente ou vestigial, projeção posterior da placa opercular de odontódeos com altura reduzida, padrão de colorido com pintas arredondadas castanho-escuro, sobre o corpo castanho-claro). Trichomycterus candidus compartilha com E. mutisii apenas a ausência de nadadeiras pélvicas, mas não o padrão apomórfico de poros do sistema sensorial recentemente estabelecido para o gênero

Reflections on the Implementation of Tidal Energy in Ecuador

Renewable energy is a topic frequently discussed due to the need to change the forms of generation, from the centralized to the distributed form and take advantage of the potentials that are scattered in the territory and use local resources and thereby diversify the schemes of distributed generation that allows the man in his daily work to pass from consumption of energy to generator, in this way the environmental impacts are reduced that today accelerate the change of temperature in the planet, noticing in recent years the oil and its derivatives are responsible for this phenomenon. The objective of the research is to reflect on tidal energy, knowing that the province of Manabí, is the one that has the largest coastal area and where there is a potential that can be studied for future use

Iron Status and Analysis of Efficacy and Safety of Ferric Carboxymaltose Treatment in Patients with Inflammatory Bowel Disease

Background and Aims:We analyzed iron deficiency and the therapeutic response following intravenous ferric carboxymaltose in a large single-center inflammatory bowel disease (IBD) cohort. Methods: 250 IBD patients were retrospectively analyzed for iron deficiency and iron deficiency anemia. A subgroup was analyzed regarding efficacy and side effects of iron supplementation with ferric carboxymaltose. Results: In the cohort (n = 250), 54.4% of the patients had serum iron levels 60 mu g/dl, 61.6% had ferritin >100 ng/ml, and 90.7% reached Hb >12/13 g/dl at follow-up (p < 0.0001 for all parameters vs. pretreatment values). The most frequent adverse event was a transient increase of liver enzymes with male gender as risk factor (p = 0.008, OR 8.62, 95% CI 1.74-41.66). Conclusions: Iron deficiency and anemia are frequent in IBD patients. Treatment with ferric carboxymaltose is efficious, safe and well tolerated in iron-deficient IBD patients. Copyright (C) 2011 S. Karger AG, Base