1,762 research outputs found
Comparative Studies of Some Polypores Using High Performance Liquid Chromatography
Isolates of four polypores; Ganoderma colossum, Ganoderma lucidum, Trametes cingulata and Daedalea quercina were compared using the High performance liquid chromatographic profiles of their triterpenoids. A higher abundance of colossolactone E was found in Ganoderma colossum isolate (FC 876) when compared with FC 872 obtained at different periods and dried differently and 23- hydroxycolossolactone E found in FC 876 was not observed in FC 872. Equal abundance of constituents was also found in Ganoderma lucidum isolates (FC 871 and FC 875) collected from different hosts and
geographical locations. The isolates of Trametes cingulata that were of different ages showed predominance of the major constituents in FC 873 and FC 885 isolates when compared with FC 870. The abundance of the triterpenoid in the isolates of Daedalea quercina was almost doubled in FC 882 when compared with that of FC 878. These conform with the chemical spot test results on these polypores in a previous work. The ability of the polypores to produce triterpenoids is affected by their age, period of collection, geographical location and method of drying, which also affected the High Performance Liquid
Chromatography characteristics of their secondary metabolites. African Research Review Vol. 1 (1) 2007: pp. 77-9
Dynamics of thermoelastic thin plates: A comparison of four theories
Four distinct theories describing the flexural motion of thermoelastic thin
plates are compared. The theories are due to Chadwick, Lagnese and Lions,
Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the
temperature but is considered the most accurate as the others are derivable
from it by different approximations. Attention is given to the damping of
flexural waves. Analytical and quantitative comparisons indicate that the
Lagnese and Lions model with a 2D temperature equation captures the essential
features of the thermoelastic damping, but contains systematic inaccuracies.
These are attributable to the approximation for the first moment of the
temperature used in deriving the Lagnese and Lions equation. Simmonds' model
with an explicit formula for temperature in terms of plate deflection is the
simplest of all but is accurate only at low frequency, where the damping is
linearly proportional to the frequency. It is shown that the Norris model,
which is almost as simple as Simmond's, is as accurate as the more precise but
involved theory of Chadwick.Comment: 2 figures, 1 tabl
Improved survival at low lung function in cystic fibrosis: cohort study from 1990 to 2007
Objectives To evaluate the survival of patients with cystic fibrosis whose lung function has deteriorated to a forced expiratory volume in one second (FEV1) below 30% predicted in the recent treatment era and to explore factors associated with any change in survival
Optically Selected BL Lacertae Candidates from the Sloan Digital Sky Survey Data Release Seven
We present a sample of 723 optically selected BL Lac candidates from the SDSS
DR7 spectroscopic database encompassing 8250 deg^2 of sky; our sample
constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac
candidate has a high-quality SDSS spectrum from which we determine
spectroscopic redshifts for ~60% of the objects. Redshift lower limits are
estimated for the remaining objects utilizing the lack of host galaxy flux
contamination in their optical spectra; we find that objects lacking
spectroscopic redshifts are likely at systematically higher redshifts.
Approximately 80% of our BL Lac candidates match to a radio source in
FIRST/NVSS, and ~40% match to a ROSAT X-ray source. The homogeneous
multiwavelength coverage allows subdivision of the sample into 637 radio-loud
BL Lac candidates and 86 weak-featured radio-quiet objects. The radio-loud
objects broadly support the standard paradigm unifying BL Lac objects with
beamed radio galaxies. We propose that the majority of the radio-quiet objects
may be lower-redshift (z<2.2) analogs to high-redshift weak line quasars (i.e.,
AGN with unusually anemic broad emission line regions). These would constitute
the largest sample of such objects, being of similar size and complementary in
redshift to the samples of high-redshift weak line quasars previously
discovered by the SDSS. However, some fraction of the weak-featured radio-quiet
objects may instead populate a rare and extreme radio-weak tail of the much
larger radio-loud BL Lac population. Serendipitous discoveries of unusual white
dwarfs, high-redshift weak line quasars, and broad absorption line quasars with
extreme continuum dropoffs blueward of rest-frame 2800 Angstroms are also
briefly described.Comment: 24 pages, 14 figures, 8 tables. Accepted for publication in A
Genetics, recombination and clinical features of human rhinovirus species C (HRV-C) infections; interactions of HRV-C with other respiratory viruses
To estimate the frequency, molecular epidemiological and clinical associations of infection with the newly described species C variants of human rhinoviruses (HRV), 3243 diagnostic respiratory samples referred for diagnostic testing in Edinburgh were screened using a VP4-encoding region-based selective polymerase chain reaction (PCR) for HRV-C along with parallel PCR testing for 13 other respiratory viruses. HRV-C was the third most frequently detected behind respiratory syncytial virus (RSV) and adenovirus, with 141 infection episodes detected among 1885 subjects over 13 months (7.5%). Infections predominantly targeted the very young (median age 6–12 months; 80% of infections in those <2 years), occurred throughout the year but with peak incidence in early winter months. HRV-C was detected significantly more frequently among subjects with lower (LRT) and upper respiratory tract (URT) disease than controls without respiratory symptoms; HRV-C mono-infections were the second most frequently detected virus (behind RSV) in both disease presentations (6.9% and 7.8% of all cases respectively). HRV variants were classified by VP4/VP2 sequencing into 39 genotypically defined types, increasing the current total worldwide to 60. Through sequence comparisons of the 5′untranslated region (5′UTR), the majority grouped with species A (n = 96; 68%, described as HRV-Ca), the remainder forming a phylogenetically distinct 5′UTR group (HRV-Cc). Multiple and bidirectional recombination events between HRV-Ca and HRV-Cc variants and with HRV species A represents the most parsimonious explanation for their interspersed phylogeny relationships in the VP4/VP2-encoding region. No difference in age distribution, seasonality or disease associations was identified between HRV-Ca and HRV-Cc variants. HRV-C-infected subjects showed markedly reduced detection frequencies of RSV and other respiratory viruses, providing evidence for a major interfering effect of HRV-C on susceptibility to other respiratory virus infections. HRV-C's disease associations, its prevalence and evidence for interfering effects on other respiratory viruses mandates incorporation of rhinoviruses into future diagnostic virology screening
Pinhole calculations of the Josephson effect in 3He-B
We study theoretically the dc Josephson effect between two volumes of
superfluid 3He-B. We first discuss how the calculation of the current-phase
relationships is divided into a mesoscopic and a macroscopic problem. We then
analyze mass and spin currents and the symmetry of weak links. In quantitative
calculations the weak link is assumed to be a pinhole, whose size is small in
comparison to the coherence length. We derive a quasiclassical expression for
the coupling energy of a pinhole, allowing also for scattering in the hole.
Using a selfconsistent order parameter near a wall, we calculate the
current-phase relationships in several cases. In the isotextural case, the
current-phase relations are plotted assuming a constant spin-orbit texture. In
the opposite anisotextural case the texture changes as a function of the phase
difference. For that we have to consider the stiffness of the macroscopic
texture, and we also calculate some surface interaction parameters. We analyze
the experiments by Marchenkov et al. We find that the observed pi states and
bistability hardly can be explained with the isotextural pinhole model, but a
good quantitative agreement is achieved with the anisotextural model.Comment: 20 pages, 21 figures, revtex
Effectiveness of stress control large group psychoeducation for anxiety and depression : systematic review and meta-analysis
Objectives
This review sought to evaluate the effectiveness of the ‘Stress Control’ (SC) large psychoeducational 6‐session group programme developed to increase access to treatment for patients with anxiety and depression.
Design
Systematic review and meta‐analysis (Prospero registration: CRD42020173676).
Methods
Pre–post and post‐treatment follow‐up effect sizes were extracted and synthesized in a random effects meta‐analysis, and variations in effect sizes were investigated via moderator analyses. Secondary analyses synthesized between‐group effect sizes from controlled studies containing comparator treatments and calculated the average dropout rate. The quality of the meta‐analysis was assessed using the GRADE approach.
Results
Nineteen studies with pre–post treatment outcomes were included. The average group size was N = 39, and the average dropout rate was 34%. Pooled effect sizes indicated moderate pre–post treatment reductions in anxiety (ES = 0.58; CI 0.41 to 0.75; N = 5597; Z = 7.13; p < .001), moderate reductions in depression (ES = 0.62; CI 0.44 to 0.80; N = 5538, Z = 7.30; p < .001), and large reductions in global distress (ES = 0.86; CI 0.61 to 1.11; N = 591; Z = 7.41; p < .001). At follow‐up, improvements in anxiety, depression, and global distress were maintained. When SC was compared to active and passive controls, outcomes were equivalent for anxiety (ES = 0.12, 95% CI −0.25 to 0.49, Z = −0.70; p = .482) and depression (ES = 0.15, 95% CI −0.24 to 0.54, Z = 0.84; p = .401).
Conclusions
SC appears to be a clinically effective and durable low‐intensity group intervention that facilitates access to treatment for large patient numbers. However, conclusions are limited by the low methodological quality of the evidence.
Practitioner points
- The stress control version of large group psychoeducation is appropriate and effective for mild‐to‐moderate anxiety and depression
- The evidence base for stress control is predominantly made up of practice‐based studies
- Stress control needs to form one component of the overall offer made to patients presenting with mild‐to‐moderate anxiety and depression
- The competencies required to deliver such groups need better specification
Growth variations and scattering mechanisms in metamorphic In0.75Ga0.25As/In-0.75 Al0.25As quantum wells grown by molecular beam epitaxy
Modulation doped metamorphic In0.75Ga0.25As/In0.75Al0.25As quantum wells (QW) were grown on GaAs substrates by molecular beam epitaxy (MBE) with step-graded buffer layers. The electron mobility of the QWs has been improved by varying the MBE growth conditions, including substrate temperature, arsenic over pressure and modulation doping level. By applying a bias voltage to SiO2 insulated gates, the electron density in the QW can be tuned from 1×1011 to 5.3×1011 cm−2. A peak mobility of 4.3×105 cm2V−1s−1 is obtained at 3.7×1011 cm−2 at 1.5 K before the onset of second subband population. To understand the evolution of mobility, transport data is fitted to a model that takes into account scattering from background impurities, modulation doping, alloy disorder and interface roughness. According to the fits, scattering from background impurities is dominant while that from alloy disorder becomes more significant at high carrier density
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