4,101 research outputs found
Heat-kernel coefficients of the Laplace operator on the D-dimensional ball
We present a very quick and powerful method for the calculation of
heat-kernel coefficients. It makes use of rather common ideas, as integral
representations of the spectral sum, Mellin transforms, non-trivial commutation
of series and integrals and skilful analytic continuation of zeta functions on
the complex plane. We apply our method to the case of the heat-kernel expansion
of the Laplace operator on a -dimensional ball with either Dirichlet,
Neumann or, in general, Robin boundary conditions. The final formulas are quite
simple. Using this case as an example, we illustrate in detail our scheme
---which serves for the calculation of an (in principle) arbitrary number of
heat-kernel coefficients in any situation when the basis functions are known.
We provide a complete list of new results for the coefficients
, corresponding to the -dimensional ball with all the
mentioned boundary conditions and .Comment: 29 pages, LaTex, lines had been cut in the previous version by
transmission, no further change
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Appearance concerns in ophthalmic patients
Aims: This study aimed to determine the psychosocial and appearance-related concerns of a sample of ophthalmic patients by measuring a range of psychological, social, and demographic factors.
Methods: Standardized psychological measures including anxiety, depression, appearance-related distress, self-discrepancy, appearance salience and valence were administered to 98 participants attending ophthalmic outpatient clinics in either London, Bristol, Sheffield or Bradford. Differences between groups were explored using t-tests and ANOVA, relationships between all variables were investigated using Pearson's correlation coefficient.
Results: Although mean scores for psychological adjustment were within the normal range, some participants were experiencing considerable levels of generalized anxiety. Being older, male, and married or living with a partner was related to significantly better adjustment. Better adjustment was also related to a less visible area of concern, greater disguisability of the affected area, a more positive evaluation of their own appearance, less engagement in comparing themselves with others, greater feelings of being accepted by others, appearance being less important to their self-concept, and a smaller discrepancy between the persons ideal and actual appearance.
Conclusions: A majority of ophthalmic patients adjust positively to the demands placed on them. By identifying the variables that are associated with successful adaptation, the specific psychological interventions and appropriate systems of support can be put in place to help those who are adversely affected
Preclinical characterization of zuranolone (SAGE-217), a selective neuroactive steroid GABAA receptor positive allosteric modulator
Zuranolone (SAGE-217) is a novel, synthetic, clinical stage neuroactive steroid GABAA receptor positive allosteric modulator designed with the pharmacokinetic properties to support oral daily dosing. In vitro, zuranolone enhanced GABAA receptor current at nine unique human recombinant receptor subtypes, including representative receptors for both synaptic (γ subunit-containing) and extrasynaptic (δ subunit-containing) configurations. At a representative synaptic subunit configuration, α1β2γ2, zuranolone potentiated GABA currents synergistically with the benzodiazepine diazepam, consistent with the non-competitive activity and distinct binding sites of the two classes of compounds at synaptic receptors. In a brain slice preparation, zuranolone produced a sustained increase in GABA currents consistent with metabotropic trafficking of GABAA receptors to the cell surface. In vivo, zuranolone exhibited potent activity, indicating its ability to modulate GABAA receptors in the central nervous system after oral dosing by protecting against chemo-convulsant seizures in a mouse model and enhancing electroencephalogram β-frequency power in rats. Together, these data establish zuranolone as a potent and efficacious neuroactive steroid GABAA receptor positive allosteric modulator with drug-like properties and CNS exposure in preclinical models. Recent clinical data support the therapeutic promise of neuroactive steroid GABAA receptor positive modulators for treating mood disorders; brexanolone is the first therapeutic approved specifically for the treatment of postpartum depression. Zuranolone is currently under clinical investigation for the treatment of major depressive episodes in major depressive disorder, postpartum depression, and bipolar depression
The influence of 'significant others' on persistent back pain and work participation: a qualitative exploration of illness perceptions
Background
Individual illness perceptions have been highlighted as important influences on clinical outcomes for back pain. However, the illness perceptions of 'significant others' (spouse/partner/close family member) are rarely explored, particularly in relation to persistent back pain and work participation. The aim of this study was to initiate qualitative research in this area in order to further understand these wider influences on outcome.
Methods
Semi-structured interviews based on the chronic pain version of the Illness Perceptions Questionnaire-Revised were conducted with a convenience sample of UK disability benefit claimants, along with their significant others (n=5 dyads). Data were analysed using template analysis.
Results
Significant others shared, and perhaps further reinforced, claimants' unhelpful illness beliefs including fear of pain/re-injury associated with certain types of work and activity, and pessimism about the likelihood of return to work. In some cases, significant others appeared more resigned to the permanence and negative inevitable consequences of the claimant's back pain condition on work participation, and were more sceptical about the availability of suitable work and sympathy from employers. In their pursuit of authenticity, claimants were keen to stress their desire to work whilst emphasising how the severity and physical limitations of their condition prevented them from doing so. In this vein, and seemingly based on their perceptions of what makes a 'good' significant other, significant others acted as a 'witness to pain', supporting claimants' self-limiting behaviour and statements of incapacity, often responding with empathy and assistance. The beliefs and responses of significant others may also have been influenced by their own experience of chronic illness, thus participants lives were often intertwined and defined by illness.
Conclusions
The findings from this exploratory study reveal how others and wider social circumstances might contribute both to the propensity of persistent back pain and to its consequences. This is an area that has received little attention to date, and wider support of these findings may usefully inform the design of future intervention programmes aimed at restoring work participation
Solar-type dynamo behaviour in fully convective stars without a tachocline
In solar-type stars (with radiative cores and convective envelopes), the
magnetic field powers star spots, flares and other solar phenomena, as well as
chromospheric and coronal emission at ultraviolet to X-ray wavelengths. The
dynamo responsible for generating the field depends on the shearing of internal
magnetic fields by differential rotation. The shearing has long been thought to
take place in a boundary layer known as the tachocline between the radiative
core and the convective envelope. Fully convective stars do not have a
tachocline and their dynamo mechanism is expected to be very different,
although its exact form and physical dependencies are not known. Here we report
observations of four fully convective stars whose X-ray emission correlates
with their rotation periods in the same way as in Sun-like stars. As the X-ray
activity - rotation relationship is a well-established proxy for the behaviour
of the magnetic dynamo, these results imply that fully convective stars also
operate a solar-type dynamo. The lack of a tachocline in fully convective stars
therefore suggests that this is not a critical ingredient in the solar dynamo
and supports models in which the dynamo originates throughout the convection
zone.Comment: 6 pages, 1 figure. Accepted for publication in Nature (28 July 2016).
Author's version, including Method
A Geographically-Restricted but Prevalent Mycobacterium tuberculosis Strain Identified in the West Midlands Region of the UK between 1995 and 2008
Background: We describe the identification of, and risk factors for, the single most prevalent Mycobacterium tuberculosis strain in the West Midlands region of the UK.Methodology/Principal Findings: Prospective 15-locus MIRU-VNTR genotyping of all M. tuberculosis isolates in the West Midlands between 2004 and 2008 was undertaken. Two retrospective epidemiological investigations were also undertaken using univariable and multivariable logistic regression analysis. The first study of all TB patients in the West Midlands between 2004 and 2008 identified a single prevalent strain in each of the study years (total 155/3,056 (5%) isolates). This prevalent MIRU-VNTR profile (32333 2432515314 434443183) remained clustered after typing with an additional 9-loci MIRU-VNTR and spoligotyping. The majority of these patients (122/155, 79%) resided in three major cities located within a 40 km radius. From the apparent geographical restriction, we have named this the "Mercian" strain. A multivariate analysis of all TB patients in the West Midlands identified that infection with a Mercian strain was significantly associated with being UK-born (OR = 9.03, 95% CI = 4.56-17.87, p 65 years old (OR = 0.25, 95% CI = 0.09-0.67, p < 0.01). A second more detailed investigation analyzed a cohort of 82 patients resident in Wolverhampton between 2003 and 2006. A significant association with being born in the UK remained after a multivariate analysis (OR = 9.68, 95% CI = 2.00-46.78, p < 0.01) and excess alcohol intake and cannabis use (OR = 6.26, 95% CI = 1.45-27.02, p = .01) were observed as social risk factors for infection.Conclusions/Significance: The continued consistent presence of the Mercian strain suggests ongoing community transmission. Whilst significant associations have been found, there may be other common risk factors yet to be identified. Future investigations should focus on targeting the relevant risk groups and elucidating the biological factors that mediate continued transmission of this strain
Photo-antagonism of the GABAA receptor
Neurotransmitter receptor trafficking is fundamentally important for synaptic transmission and neural network activity. GABAA receptors and inhibitory synapses are vital components of brain function, yet much of our knowledge regarding receptor mobility and function at inhibitory synapses is derived indirectly from using recombinant receptors, antibody-tagged native receptors and pharmacological treatments. Here we describe the use of a set of research tools that can irreversibly bind to and affect the function of recombinant and neuronal GABAA receptors following ultraviolet photoactivation. These compounds are based on the competitive antagonist gabazine and incorporate a variety of photoactive groups. By using site-directed mutagenesis and ligand-docking studies, they reveal new areas of the GABA binding site at the interface between receptor β and α subunits. These compounds enable the selected inactivation of native GABAA receptor populations providing new insight into the function of inhibitory synapses and extrasynaptic receptors in controlling neuronal excitation
Atropselective syntheses of (-) and (+) rugulotrosin A utilizing point-to-axial chirality transfer
Chiral, dimeric natural products containing complex structures and interesting biological properties have inspired chemists and biologists for decades. A seven-step total synthesis of the axially chiral, dimeric tetrahydroxanthone natural product rugulotrosin A is described. The synthesis employs a one-pot Suzuki coupling/dimerization to generate the requisite 2,2'-biaryl linkage. Highly selective point-to-axial chirality transfer was achieved using palladium catalysis with achiral phosphine ligands. Single X-ray crystal diffraction data were obtained to confirm both the atropisomeric configuration and absolute stereochemistry of rugulotrosin A. Computational studies are described to rationalize the atropselectivity observed in the key dimerization step. Comparison of the crude fungal extract with synthetic rugulotrosin A and its atropisomer verified that nature generates a single atropisomer of the natural product.P50 GM067041 - NIGMS NIH HHS; R01 GM099920 - NIGMS NIH HHS; GM-067041 - NIGMS NIH HHS; GM-099920 - NIGMS NIH HH
Effective Lagrangian for self-interacting scalar field theories in curved spacetime
We consider a self-interacting scalar field theory in a slowly varying
gravitational background field. Using zeta-function regularization and
heat-kernel techniques, we derive the one-loop effective Lagrangian up to
second order in the variation of the background field and up to quadratic terms
in the curvature tensors. Specializing to different spacetimes of physical
interest, the influence of the curvature on the phase transition is considered.Comment: 14 pages, LaTex, UTF 29
Effects of evidence-based strategies to reduce the socioeconomic gradient of uptake in the English NHS Bowel Cancer Screening Programme (ASCEND): four cluster-randomised controlled trials
This study is funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research Programme ( RP-PG-0609-10106 ) and partly supported by the NIHR Collaboration for Leadership in Applied Health Research and Care (CLAHRC) North Thames (MCT and RR
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