63 research outputs found
Direct measurement of antiferromagnetic domain fluctuations
Measurements of magnetic noise emanating from ferromagnets due to domain
motion were first carried out nearly 100 years ago and have underpinned much
science and technology. Antiferromagnets, which carry no net external magnetic
dipole moment, yet have a periodic arrangement of the electron spins extending
over macroscopic distances, should also display magnetic noise, but this must
be sampled at spatial wavelengths of order several interatomic spacings, rather
than the macroscopic scales characteristic of ferromagnets. Here we present the
first direct measurement of the fluctuations in the nanometre-scale spin-
(charge-) density wave superstructure associated with antiferromagnetism in
elemental Chromium. The technique used is X-ray Photon Correlation
Spectroscopy, where coherent x-ray diffraction produces a speckle pattern that
serves as a "fingerprint" of a particular magnetic domain configuration. The
temporal evolution of the patterns corresponds to domain walls advancing and
retreating over micron distances. While the domain wall motion is thermally
activated at temperatures above 100K, it is not so at lower temperatures, and
indeed has a rate which saturates at a finite value - consistent with quantum
fluctuations - on cooling below 40K. Our work is important because it provides
an important new measurement tool for antiferromagnetic domain engineering as
well as revealing a fundamental new fact about spin dynamics in the simplest
antiferromagnet.Comment: 19 pages, 4 figure
On products of long cycles: short cycle dependence and separation probabilities
We present various results on multiplying cycles in the symmetric group. One result is a generalisation
of the following theorem of Boccara (1980): the number of ways of writing an odd permutation
in the symmetric group on n symbols as a product of an n-cycle and an (n - 1)-cycle is independent of
the permutation chosen. We give a number of different approaches of our generalisation. One partial proof
uses an inductive method which we also apply to other problems. In particular, we give a formula for the
distribution of the number of cycles over all products of cycles of fixed lengths. Another application is related
to the recent notion of separation probabilities for permutations introduced by Bernardi, Du, Morales
and Stanley (2014)
Neuronal circuitry for pain processing in the dorsal horn
Neurons in the spinal dorsal horn process sensory information, which is then transmitted to several brain regions, including those responsible for pain perception. The dorsal horn provides numerous potential targets for the development of novel analgesics and is thought to undergo changes that contribute to the exaggerated pain felt after nerve injury and inflammation. Despite its obvious importance, we still know little about the neuronal circuits that process sensory information, mainly because of the heterogeneity of the various neuronal components that make up these circuits. Recent studies have begun to shed light on the neuronal organization and circuitry of this complex region
Microbiological profiles of sputum and gastric juice aspirates in Cystic Fibrosis patients.
Gastro-Oesophageal Reflux (GOR) is a key problem in Cystic Fibrosis (CF), but the relationship between lung and gastric microbiomes is not well understood. We hypothesised that CF gastric and lung microbiomes are related. Gastric and sputum cultures were obtained from fifteen CF patients receiving percutaneous endoscopic gastrostomy feeding. Non-CF gastric juice data was obtained through endoscopy from 14 patients without lung disease. Bacterial and fungal isolates were identified by culture. Molecular bacterial profiling used next generation sequencing (NGS) of the 16S rRNA gene. Cultures grew bacteria and/or fungi in all CF gastric juice and sputa and in 9/14 non-CF gastric juices. Pseudomonas aeruginosa(Pa) was present in CF sputum in 11 patients, 4 had identical Pa strains in the stomach. NGS data from non-CF gastric juice samples were significantly more diverse compared to CF samples. NGS showed CF gastric juice had markedly lower abundance of normal gut bacteria; Bacteroides and Faecalibacterium, but increased Pseudomonas compared with non-CF. Multivariate partial least squares discriminant analysis demonstrated similar bacterial profiles of CF sputum and gastric juice samples, which were distinct from non-CF gastric juice. We provide novel evidence suggesting the existence of an aerodigestive microbiome in CF, which may have clinical relevance
Incidence of Schizophrenia and Other Psychoses in England, 1950–2009: A Systematic Review and Meta-Analyses
Background
We conducted a systematic review of incidence rates in England over a sixty-year period to determine the extent to which rates varied along accepted (age, sex) and less-accepted epidemiological gradients (ethnicity, migration and place of birth and upbringing, time).
Objectives
To determine variation in incidence of several psychotic disorders as above.
Data Sources
Published and grey literature searches (MEDLINE, PSycINFO, EMBASE, CINAHL, ASSIA, HMIC), and identification of unpublished data through bibliographic searches and author communication.
Study Eligibility Criteria
Published 1950–2009; conducted wholly or partially in England; original data on incidence of non-organic adult-onset psychosis or one or more factor(s) pertaining to incidence.
Participants
People, 16–64 years, with first -onset psychosis, including non-affective psychoses, schizophrenia, bipolar disorder, psychotic depression and substance-induced psychosis.
Study Appraisal and Synthesis Methods
Title, abstract and full-text review by two independent raters to identify suitable citations. Data were extracted to a standardized extraction form. Descriptive appraisals of variation in rates, including tables and forest plots, and where suitable, random-effects meta-analyses and meta-regressions to test specific hypotheses; rate heterogeneity was assessed by the I2-statistic.
Results
83 citations met inclusion. Pooled incidence of all psychoses (N = 9) was 31.7 per 100,000 person-years (95%CI: 24.6–40.9), 23.2 (95%CI: 18.3–29.5) for non-affective psychoses (N = 8), 15.2 (95%CI: 11.9–19.5) for schizophrenia (N = 15) and 12.4 (95%CI: 9.0–17.1) for affective psychoses (N = 7). This masked rate heterogeneity (I2: 0.54–0.97), possibly explained by socio-environmental factors; our review confirmed (via meta-regression) the typical age-sex interaction in psychosis risk, including secondary peak onset in women after 45 years. Rates of most disorders were elevated in several ethnic minority groups compared with the white (British) population. For example, for schizophrenia: black Caribbean (pooled RR: 5.6; 95%CI: 3.4–9.2; N = 5), black African (pooled RR: 4.7; 95%CI: 3.3–6.8; N = 5) and South Asian groups in England (pooled RR: 2.4; 95%CI: 1.3–4.5; N = 3). We found no evidence to support an overall change in the incidence of psychotic disorder over time, though diagnostic shifts (away from schizophrenia) were reported.
Limitations
Incidence studies were predominantly cross-sectional, limiting causal inference. Heterogeneity, while evidencing important variation, suggested pooled estimates require interpretation alongside our descriptive systematic results.
Conclusions and Implications of Key Findings
Incidence of psychotic disorders varied markedly by age, sex, place and migration status/ethnicity. Stable incidence over time, together with a robust socio-environmental epidemiology, provides a platform for developing prediction models for health service planning
"You feel dirty a lot of the time" : policing 'dirty work', contamination and purification rituals
Following the controversial adoption of spit-hoods by some UK police forces, most recently by the London Metropolitan Police in February 2019, this article contributes to and extends debates on physical and symbolic contamination by drawing on established considerations of ‘dirty work’. The article argues that, for police officers, cleansing rituals are personal and subjective. As a relatively high-prestige occupation, police officers occupy a unique position in that they are protected by a status shield. Reflections from this ethnographic study suggest that the police uniform can be used as a vehicle for contamination and staff employ purification rituals and methods of taint management
Supersymmetric QCD corrections to and the Bernstein-Tkachov method of loop integration
The discovery of charged Higgs bosons is of particular importance, since
their existence is predicted by supersymmetry and they are absent in the
Standard Model (SM). If the charged Higgs bosons are too heavy to be produced
in pairs at future linear colliders, single production associated with a top
and a bottom quark is enhanced in parts of the parameter space. We present the
next-to-leading-order calculation in supersymmetric QCD within the minimal
supersymmetric SM (MSSM), completing a previous calculation of the SM-QCD
corrections. In addition to the usual approach to perform the loop integration
analytically, we apply a numerical approach based on the Bernstein-Tkachov
theorem. In this framework, we avoid some of the generic problems connected
with the analytical method.Comment: 14 pages, 6 figures, accepted for publication in Phys. Rev.
Implicit Reasons for Disclosure of the Use of Complementary Health Approaches (CHA): a Consumer Commitment Perspective
Background: Disclosure of the use of complementary health approaches (CHA) is an important yet understudied health behaviour with important implications for patient care. Yet research into disclosure of CHA has been atheoretical and neglected the role of health beliefs. Purpose: Using a consumer commitment model of CHA use as a guiding conceptual framework, the current study tests the hypotheses that perceived positive CHA outcomes (utilitarian values) and positive CHA beliefs (symbolic values) are associated with disclosure of CHA to conventional-care providers in a nationally representative US sample. Methods: From a sample of 33,594 with CHA use information from the 2012 National Health Interview Survey (NHIS), a subsample of 7,348 who used CHA within the past 12 months was analysed. The 2012 NHIS is a cross-sectional survey of the non-institutionalized US adult population, which includes the most recent nationally representative CHA use data. Results: The 63.2 % who disclosed CHA use were older, less educated, and had visited a health-care provider in the past year. Weighted logistic regression analyses controlling for demographic variables revealed that those who disclosed were more likely to report experiencing positive psychological (improved coping and well-being) and physical outcomes (better sleep, improved health) from CHA, and hold positive CHA-related beliefs. Conclusions: CHA users who perceive physical and psychological benefits from CHA use, and who hold positive attitudes towards CHA are more likely to disclose their CHA use. Findings support the relevance of a consumer commitment perspective for understanding CHA disclosure, and suggest CHA disclosure as an important proactive health behaviour that warrants further attention
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