232 research outputs found

    Spin dependent photoelectron tunnelling from GaAs into magnetic Cobalt

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    The spin dependence of the photoelectron tunnel current from free standing GaAs films into out-of- plane magnetized Cobalt films is demonstrated. The measured spin asymmetry (A) resulting from a change in light helicity, reaches +/- 6% around zero applied tunnel bias and drops to +/- 2% at a bias of -1.6 V applied to the GaAs. This decrease is a result of the drop in the photoelectron spin polarization that results from a reduction in the GaAs surface recombination velocity. The sign of A changes with that of the Cobalt magnetization direction. In contrast, on a (nonmagnetic) Gold film A ~ 0%

    Breastfeeding and Respiratory Tract Infections during the First 2 Years of Life.

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    Breastfeeding protects against respiratory tract infections (RTIs) in infants [1–3], but whether its effects persist beyond that age is not well understood. Some studies have reported that protection diminishes soon after weaning [2], while others have found that it extends until the age of 2 years [4] or more [5, 6]. It is noteworthy that many previous studies grouped RTIs broadly into upper or lower tract infections, rather than studying specific diseases [3, 7], and few adjusted adequately for confounding factors [5] or investigated a possible effect modification by sex, which had been suggested by several studies showing a stronger protection in girls [8, 9]. This study aimed to quantify the protective effect of breastfeeding against RTIs during the first 2 years of life, while adjusting for potential confounding factors and testing whether the effect varied by sex. We analysed data from the Leicester Respiratory Cohorts, a population-based random sample of children from Leicestershire, UK, which has been described in detail elsewhere [10]. For this analysis we included only children born between 1996 and 1997 who were aged 1–1.99 years at the date of the first survey in 1998. Parents completed a standardised questionnaire that requested detailed information on breastfeeding and respiratory symptoms. We assessed the duration of breastfeeding (no breastfeeding, â©œ6 months or >6 months), the prevalence of frequent colds (>6 episodes), ear infections and croup within the last 12 months, and any episodes of bronchiolitis or pneumonia. We extracted perinatal data and demographic information from maternity records. The Leicestershire Health Authority Research Ethics Committee approved the study. The survey requested information on a number of RTIs for each child, so we first performed an omnibus logistic regression to determine whether breastfeeding was associated with the occurrence of any RTI. By reforming the data into long format, this omnibus logistic regression also adjusted for the clustering of observations within each child [11]. Following a significant omnibus test, we performed unadjusted and adjusted logistic regressions to determine which RTIs were affected by breastfeeding practice. Adjusted models controlled for sex, ethnicity, socioeconomic status (Townsend deprivation score [12]), perinatal factors (gestational age, birthweight, birth season), environmental factors ( pre- and post-natal maternal smoking, number of older siblings, day care attendance) and parental history of asthma, hay fever and bronchitis. We tested for effect modification by sex by adding interaction terms into adjusted models. Finally, we performed a sensitivity analysis including a subgroup of children with information on exact breastfeeding duration, by using breastfeeding as a continuous exposure, rather than categorical. All analyses were performed in Stata (version 14.2, Stata Corporation, Austin, TX, USA). The survey in 1998 was sent to 5400 families with children aged between 1 and 1.99 years. Questionnaires were returned by 4100 parents (response rate of 76%). After excluding 47 children who had no breastfeeding information and 13 children born extremely prematurely (gestational age of <28 weeks [13]), 4040 children remained in the analysis. Of these, 52% were boys, 81% were white and 19% were of South Asian ethnic origin, 1659 (41%) had never been breastfed, 1639 (41%) had been breastfed for â©œ6 months and 742 (18%) for >6 months. Of the 4040 included children, 769 (19%) were reported by their parents to have had frequent colds, 1685 (42%) ear infections and 293 (7%) croup within the last 12 months. Any episodes of bronchiolitis were reported for 453 children (11%) and pneumonia for 53 (1%)Peer-reviewedPublisher Versio

    Phenotypic characteristics, healthcare use, and treatment in children with night cough compared with children with wheeze.

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    OBJECTIVES Population-based studies of children with dry night cough alone compared with those who also wheeze are few and inconclusive. We compared how children with dry night cough differ from those who wheeze. METHODS LuftiBus in the school is a population-based study of schoolchildren conducted between 2013 and 2016 in Zurich, Switzerland. We divided children into four mutually exclusive groups based on reported dry night cough (henceforth referred as "cough") and wheeze and compared parent-reported symptoms, comorbidities, exposures, FeNO, spirometry, and healthcare use and treatment. RESULTS Among 3457 schoolchildren aged 6-17 years, 294 (9%) reported "cough," 181 (5%) reported "wheeze," 100 (3%) reported "wheeze and cough," and 2882 (83%) were "asymptomatic." Adjusting for confounders in a multinomial regression, children with "cough" reported more frequent colds, rhinitis, and snoring than "asymptomatic" children; children with "wheeze" or "wheeze and cough" more often reported hay fever, eczema, and parental histories of asthma. FeNO and spirometry were similar among "asymptomatic" and children with "cough," while children with "wheeze" or "wheeze and cough" had higher FeNO and evidence of bronchial obstruction. Children with "cough" used healthcare less often than those with "wheeze," and they attended mainly primary care. Twenty-two children (7% of those with "cough") reported a physician diagnosis of asthma and used inhalers. These had similar characteristics as children with wheeze. CONCLUSION Our representative population-based study confirms that children with dry night cough without wheeze clearly differed from those with wheeze. This suggests asthma is unlikely, and they should be investigated for alternative aetiologies, particularly upper airway disease

    Phenotypic characteristics, healthcare use, and treatment in children with night cough compared with children with wheeze

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    Objectives: Population‐based studies of children with dry night cough alone compared with those who also wheeze are few and inconclusive. We compared how children with dry night cough differ from those who wheeze. Methods: LuftiBus in the school is a population‐based study of schoolchildren conducted between 2013 and 2016 in Zurich, Switzerland. We divided children into four mutually exclusive groups based on reported dry night cough (henceforth referred as “cough”) and wheeze and compared parent‐reported symptoms, comorbidities, exposures, FeNO, spirometry, and healthcare use and treatment. Results: Among 3457 schoolchildren aged 6–17 years, 294 (9%) reported “cough,” 181 (5%) reported “wheeze,” 100 (3%) reported “wheeze and cough,” and 2882 (83%) were “asymptomatic.” Adjusting for confounders in a multinomial regression, children with “cough” reported more frequent colds, rhinitis, and snoring than “asymptomatic” children; children with “wheeze” or “wheeze and cough” more often reported hay fever, eczema, and parental histories of asthma. FeNO and spirometry were similar among “asymptomatic” and children with “cough,” while children with “wheeze” or “wheeze and cough” had higher FeNO and evidence of bronchial obstruction. Children with “cough” used healthcare less often than those with “wheeze,” and they attended mainly primary care. Twenty‐two children (7% of those with “cough”) reported a physician diagnosis of asthma and used inhalers. These had similar characteristics as children with wheeze. Conclusion: Our representative population‐based study confirms that children with dry night cough without wheeze clearly differed from those with wheeze. This suggests asthma is unlikely, and they should be investigated for alternative aetiologies, particularly upper airway disease

    A d10 Ag(i) amine-borane σ-complex and comparison with a d8 Rh(i) analogue : Structures on the η1 to η2:η2 continuum

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    H3B·NMe3 σ-complexes of d8 [(L1)Rh][BArF4] and d10 [(L1)Ag][BArF4] (where L1 = 2,6-bis-[1-(2,6-diisopropylphenylimino)ethyl]pyridine) have been prepared and structurally characterised. Analysis of the molecular and electronic structures reveal important but subtle differences in the nature of the bonding in these σ-complexes, which differ only by the identity of the metal centre and the d-electron count. With Rh the amine-borane binds in an η2:η2 fashion, whereas at Ag the unsymmetrical {Ag⋯H3B·NMe3} unit suggests a structure lying between the η2:η2 and η1 extremes

    Fabry Disease Caused by the GLA p.Phe113Leu (p.F113L) Variant: Natural History in Males

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    Background, aims and methods: The α-galactosidase gene (GLA) c.337T>C/p.Phe113Leu variant was originally described in patients with late-onset cardiac forms of Fabry disease (FD), who had residual α-galactosidase activity. It has since emerged as the most commonly reported GLA variant in Portuguese subjects diagnosed with FD but is also prevalent in the Italian population, where two boys carrying the GLA Leu113 allele were identified in a large-scale newborn screening program, the variant allele segregating in both cases with the same surrounding haplotype. To further delineate the genotype-phenotype correlations of this GLA variant, we have reviewed the natural history and clinical phenotypes of 11 symptomatic Portuguese males, from 10 unrelated families originating from several different areas in mainland Portugal and Madeira Island, who were diagnosed with FD associated with the GLA Leu113 allele in a diversity of clinical and screening settings. Nine of the patients were the probands of their respective families. To test whether the GLA Leu113 allele inherited by the 10 Portuguese and the two Italian families resulted from independent mutational events, we have additionally performed a haplotype analysis with 5 highly polymorphic, closely linked microsatellite markers surrounding the GLA gene. Results and conclusions: Hemizygosity for the GLA Leu113 variant allele is associated with a late-onset form of FD, invariably presenting with severe cardiac involvement. Clinically relevant cerebrovascular and kidney involvement may also occur in some patients but the pathogenic relationship between the incomplete α-galactosidase deficiency and the risks of stroke and of chronic kidney disease is not straightforward. The observation that the Leu113 allele segregated within the same GLA microsatellite haplotype in both the Portuguese and Italian families suggests its inheritance from a common ancestor.info:eu-repo/semantics/publishedVersio

    Electronic self-doping of Mo-states in A2FeMoO6 (A=Ca, Sr and Ba) half-metallic ferromagnets - a Nuclear Magnetic Resonance study

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    A systematic study of (A,A')2FeMoO6 (A,A'=Ca, Sr, Ba) ferromagnetic oxides with double perovskite structure has been performed using 95,97Mo and 57Fe NMR spectroscopy. These oxides are isoelectronic but have substantially different Curie temperatures. The NMR analysis provides clear evidence that the magnetic moment at Mo sites is not constant but varies sensitively with the ionic size of the alkaline ions. The 95,97Mo frequency, and thus the electronic charge at Mo ions, is found to be smaller in Ba and Ca than in Sr-based oxides. The charge release from Mo sites is accompanied by an uptake at Fe sites, and thus a self-doping Fe-Mo process is observed. This process is controlled by relevant structural parameters: the Fe-O-Mo bond length and bending. A clear relationship between the Curie temperature and the magnetic moment and thus electron density at Mo sites has been disclosed. The relevance of these findings for the understanding of ferromagnetic coupling in double perovskites is discussed.Comment: 26 pages, 8 figure

    Cardiorespiratory Fitness Is Inversely Associated With the Incidence of Metabolic Syndrome: A Prospective Study of Men and Women

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    Background - Few studies have reported the relationship between cardiorespiratory fitness and metabolic syndrome incidence, particularly in women. Methods and Results - We prospectively studied 9007 men (mean±SD, age, 44±9 years; body mass index, 25±3 kg/m2) and 1491 women (age, 44±9 years; body mass index, 22±2 kg/m2) who were free of metabolic syndrome and for whom measures of waist girth, resting blood pressure, fasting lipids, and glucose were taken during baseline and follow-up examinations. Baseline cardiorespiratory fitness was quantified as duration of a maximal treadmill test. Metabolic syndrome was defined with NCEP ATP-III criteria. During a mean follow-up of 5.7 years, 1346 men and 56 women developed metabolic syndrome. Age-adjusted incidence rates were significantly lower (linear trend P\u3c0.001) across incremental thirds of fitness in men and women. After further adjustment for potential confounders, multivariable hazard ratios for incident metabolic syndrome among men in the low, middle, and upper thirds of fitness, were 1.0 (referent), 0.74 (95% CI, 0.65 to 0.84), and 0.47 (95% CI, 0.40 to 0.54) linear trend (P\u3c0.001); in women, they were 1.0 (referent), 0.80 (95% CI, 0.44 to 1.46), and 0.37 (95% CI, 0.18 to 0.80) (linear trend P=0.01), respectively. Similar patterns of significant inverse association between fitness and metabolic syndrome incidence were seen when men were stratified on categories of body mass index, age, and number of baseline metabolic risk factors, but patterns were variable in women. Conclusions - Low cardiorespiratory fitness is a strong and independent predictor of incident metabolic syndrome in women and men. Clinicians should consider the potential benefits of greater cardiorespiratory fitness in the primary prevention of metabolic syndrome, particularly among patients who have already begun to cluster metabolic syndrome components

    Age-related changes in global motion coherence: conflicting haemodynamic and perceptual responses

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    Our aim was to use both behavioural and neuroimaging data to identify indicators of perceptual decline in motion processing. We employed a global motion coherence task and functional Near Infrared Spectroscopy (fNIRS). Healthy adults (n = 72, 18-85) were recruited into the following groups: young (n = 28, mean age = 28), middle-aged (n = 22, mean age = 50), and older adults (n = 23, mean age = 70). Participants were assessed on their motion coherence thresholds at 3 different speeds using a psychophysical design. As expected, we report age group differences in motion processing as demonstrated by higher motion coherence thresholds in older adults. Crucially, we add correlational data showing that global motion perception declines linearly as a function of age. The associated fNIRS recordings provide a clear physiological correlate of global motion perception. The crux of this study lies in the robust linear correlation between age and haemodynamic response for both measures of oxygenation. We hypothesise that there is an increase in neural recruitment, necessitating an increase in metabolic need and blood flow, which presents as a higher oxygenated haemoglobin response. We report age-related changes in motion perception with poorer behavioural performance (high motion coherence thresholds) associated with an increased haemodynamic response

    Meta-heuristic algorithms for optimized network flow wavelet-based image coding

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    Optimal multipath selection to maximize the received multiple description coding (MDCs) in a lossy network model is proposed. Multiple description scalar quantization (MDSQ) has been applied to the wavelet coefficients of a color image to generate the MDCs which are combating transmission loss over lossy networks. In the networks, each received description raises the reconstruction quality of an MDC-coded signal (image, audio or video). In terms of maximizing the received descriptions, a greater number of optimal routings between source and destination must be obtained. The rainbow network flow (RNF) collaborated with effective meta-heuristic algorithms is a good approach to resolve it. Two meta-heuristic algorithms which are genetic algorithm (GA) and particle swarm optimization (PSO) have been utilized to solve the multi-objective optimization routing problem for finding optimal routings each of which is assigned as a distinct color by RNF to maximize the coded descriptions in a network model. By employing a local search based priority encoding method, each individual in GA and particle in PSO is represented as a potential solution. The proposed algorithms are compared with the multipath Dijkstra algorithm (MDA) for both finding optimal paths and providing reliable multimedia communication. The simulations run over various random network topologies and the results show that the PSO algorithm finds optimal routings effectively and maximizes the received MDCs with assistance of RNF, leading to reduce packet loss and increase throughput
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