887 research outputs found
Emergence of Quantum Phase-Slip Behaviour in Superconducting NbN Nanowires: DC Electrical Transport and Fabrication Technologies
Superconducting nanowires undergoing quantum phase-slips have potential for
impact in electronic devices, with a high-accuracy quantum current standard
among a possible toolbox of novel components. A key element of developing such
technologies is to understand the requirements for, and control the production
of, superconducting nanowires that undergo coherent quantum phase-slips. We
present three fabrication technologies, based on using electron-beam
lithography or neon focussed ion-beam lithography, for defining narrow
superconducting nanowires, and have used these to create nanowires in niobium
nitride with widths in the range of 20-250 nm. We present characterisation of
the nanowires using DC electrical transport at temperatures down to 300 mK. We
demonstrate that a range of different behaviours may be obtained in different
nanowires, including bulk-like superconducting properties with critical-current
features, the observation of phase-slip centres and the observation of zero
conductance below a critical voltage, characteristic of coherent quantum
phase-slips. We observe critical voltages up to 5 mV, an order of magnitude
larger than other reports to date. The different prominence of quantum
phase-slip effects in the various nanowires may be understood as arising from
the differing importance of quantum fluctuations. Control of the nanowire
properties will pave the way for routine fabrication of coherent quantum
phase-slip nanowire devices for technology applications.Comment: 14 pages, 8 figure
Density Matrix Renormalization Group Study of the Haldane Phase in Random One-Dimensional Antiferromagnets
It is conjectured that the Haldane phase of the S=1 antiferromagnetic
Heisenberg chain and the ferromagnetic-antiferromagnetic alternating
Heisenberg chain is stable against any strength of randomness, because of
imposed breakdown of translational symmetry. This conjecture is confirmed by
the density matrix renormalization group calculation of the string order
parameter and the energy gap distribution.Comment: 4 Pages, 7 figures; Considerable revisions are made in abstract and
main text. Final accepted versio
Factor Structure, Reliability and Criterion Validity of the Autism-Spectrum Quotient (AQ): A Study in Dutch Population and Patient Groups
The factor structure of the Dutch translation of the Autism-Spectrum Quotient (AQ; a continuous, quantitative measure of autistic traits) was evaluated with confirmatory factor analyses in a large general population and student sample. The criterion validity of the AQ was examined in three matched patient groups (autism spectrum conditions (ASC), social anxiety disorder, and obsessive–compulsive disorder). A two factor model, consisting of a “Social interaction” factor and “Attention to detail” factor could be identified. The internal consistency and test–retest reliability of the AQ were satisfactory. High total AQ and factor scores were specific to ASC patients. Men scored higher than women and science students higher than non-science students. The Dutch translation of the AQ is a reliable instrument to assess autism spectrum conditions
Desenvolvimento ninfal de Edessa meditabunda e Chinavia ubica em estruturas reprodutivas.
Conteúdo do volume 2: Ácaros; Biologia, fisiologia, morfologia; Controle biológico com bactérias entomopatogênicas; Controle biológico com fungos entomopatológicos; Controle biológico com nematoides; Controle biológico com parasitoides; Controle biológico com predadores; Ecologia e biodiversidade; Educação e etnoentomologia; Entomologia florestal; Entomologia Forense; Entomologia médica e veterinária; Entomologia molecular; Manejo integrado de pragas; Organismos geneticamente modificados; Plantas inseticidas; Polinização; Pragas quarentenárias e invasivas; Resistência de insetos a táticas de controle; Resistência de plantas a insetos; Semioquímicos e comportamento; Sistemática e taxonomia; Tecnologia de aplicação; Controle biológico com vírus entomopatogênicos; Controle químico
PDD symptoms in ADHD, an independent familial trait?
The aims of this study were to investigate whether subtle PDD symptoms in the context of ADHD are transmitted in families independent of ADHD, and whether PDD symptom familiality is influenced by gender and age. The sample consisted of 256 sibling pairs with at least one child with ADHD and 147 healthy controls, aged 5-19 years. Children who fulfilled criteria for autistic disorder were excluded. The Children's Social Behavior Questionnaire (CSBQ) was used to assess PDD symptoms. Probands, siblings, and controls were compared using analyses of variance. Sibling correlations were calculated for CSBQ scores after controlling for IQ, ADHD, and comorbid anxiety. In addition, we calculated cross-sibling cross-trait correlations. Both children with ADHD and their siblings had higher PDD levels than healthy controls. The sibling correlation was 0.28 for the CSBQ total scale, with the CSBQ stereotyped behavior subscale showing the strongest sibling correlation (r = 0.35). Sibling correlations remained similar in strength after controlling for IQ and ADHD, and were not confounded by comorbid anxiety. Sibling correlations were higher in female than in male probands. The social subscale showed stronger sibling correlations in elder than in younger sibling pairs. Cross-sibling cross-trait correlations for PDD and ADHD were weak and not-significant. The results confirm that children with ADHD have high levels of PDD symptoms, and further suggest that the familiality of subtle PDD symptoms in the context of ADHD is largely independent from ADHD familiality
Infant head growth in male siblings of children with and without autism spectrum disorders
Previous research has indicated that children with autism exhibit accelerated head growth (HG) in infancy, although the timing of acceleration varies between studies. We examined infant HG trajectory as a candidate autism endophenotype by studying sibling pairs. We retrospectively obtained serial head orbitofrontal circumference measurements of: a) 48 sibling pairs in which one (n = 28) or both (n = 20) sibs were affected by an autism spectrum disorder (ASD); and b) 85 control male sibling pairs. Rate of HG of ASD subjects was slightly accelerated compared to controls, but the magnitude of difference was below the limit of reliability of standard measurement methods. Sibling intra class correlation for rate of HG was highly statistically significant; the magnitude was significantly stronger among autism-affected families (ICC = .63) than among controls (ICC = .26), p < .01. Infant HG trajectory appears familial—possibly endophenotypic—but was not a reliable marker of autism risk among siblings of ASD probands in this sample
From second to first order transitions in a disordered quantum magnet
We study the spin-glass transition in a disordered quantum model. There is a
region in the phase diagram where quantum effects are small and the phase
transition is second order, as in the classical case. In another region,
quantum fluctuations drive the transition first order. Across the first order
line the susceptibility is discontinuous and shows hysteresis. Our findings
reproduce qualitatively observations on LiHoYF. We also discuss
a marginally stable spin-glass state and derive some results previously
obtained from the real-time dynamics of the model coupled to a bath.Comment: 4 pages, 3 figures, RevTe
Precursors to social and communication difficulties in infants at-risk for autism: gaze following and attentional engagement
Whilst joint attention (JA) impairments in autism have been widely studied, little is known about the early development of gaze following, a precursor to establishing JA. We employed eye-tracking to record gaze following longitudinally in infants with and without a family history of autism spectrum disorder (ASD) at 7 and 13 months. No group difference was found between at-risk and low-risk infants in gaze following behaviour at either age. However, despite following gaze successfully at 13 months, at-risk infants with later emerging socio-communication difficulties (both those with ASD and atypical development at 36 months of age) allocated less attention to the congruent object compared to typically developing at-risk siblings and low-risk controls. The findings suggest that the subtle emergence of difficulties in JA in infancy may be related to ASD and other atypical outcomes
Stellar evolution and modelling stars
In this chapter I give an overall description of the structure and evolution
of stars of different masses, and review the main ingredients included in
state-of-the-art calculations aiming at reproducing observational features. I
give particular emphasis to processes where large uncertainties still exist as
they have strong impact on stellar properties derived from large compilations
of tracks and isochrones, and are therefore of fundamental importance in many
fields of astrophysics.Comment: Lecture presented at the IVth Azores International Advanced School in
Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars
and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta,
Azores Islands, Portugal in July 201
Prevalência e fatores de risco associados à mastite subclínica em rebanhos fornecedores de agroindústrias familiares de Rondônia.
A contagem de células somáticas (CCS) é o indicador geral da saúde do úbere e é utilizada como indicador universal da qualidade do leite. Embora vários fatores possam estar associados à variação na CCS, a ocorrência de mastite é considerada o principal fator, sendo o limite de 200.000 células/ml o mais indicado para estimar uma nova infecção intramamária. O objetivo do trabalho foi estimar a prevalência e os fatores de risco associados à mastite subclínica em rebanhos fornecedores de agroindústrias familiares com serviço de inspeção do estado de Rondônia
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