429 research outputs found
Separation of Alcohol-Ester Binary Mixtures by Pervaporation
In this study, the pervaporation behavior of azeotrope forming methanol-methyl acetate and ethanol-ethyl acetate binary mixtures at different compositions was investigated at 30 and 45 °C using PE-based films having different thickness, compositions and structures, and a PET film. Experimental fluxes and selectivities of the permeating components were determined and evaluated on the basis of the feed mixtures and membranes. In addition, sorption measurements were taken for pure permeating components to observe the interactions between the polymeric membrane and the feed component
Multiwavelength observations of the black hole transient Swift J1745-26 during the outburst decay
We characterized the broad-band X-ray spectra of Swift J1745-26 during the
decay of the 2013 outburst using INTEGRAL ISGRI, JEM-X and Swift XRT. The X-ray
evolution is compared to the evolution in optical and radio. We fit the X- ray
spectra with phenomenological and Comptonization models. We discuss possible
scenarios for the physical origin of a ~50 day flare observed both in optical
and X- rays ~170 days after the peak of the outburst. We conclude that it is a
result of enhanced mass accretion in response to an earlier heating event. We
characterized the evolution in the hard X-ray band and showed that for the
joint ISGRI-XRT fits, the e-folding energy decreased from 350 keV to 130 keV,
while the energy where the exponential cut-off starts increased from 75 keV to
112 keV as the decay progressed.We investigated the claim that high energy
cut-offs disappear with the compact jet turning on during outburst decays, and
showed that spectra taken with HEXTE on RXTE provide insufficient quality to
characterize cut-offs during the decay for typical hard X-ray fluxes. Long
INTEGRAL monitoring observations are required to understand the relation
between the compact jet formation and hard X-ray behavior. We found that for
the entire decay (including the flare), the X-ray spectra are consistent with
thermal Comptonization, but a jet synchrotron origin cannot be ruled out.Comment: Accepted for publication by MNRA
BRCA1 and BRCA2 mutations in Turkish breast/ovarian families and young breast cancer patients
To date, BRCA1 and BRCA2 mutations in breast and/or ovarian patients have not been characterized in the Turkish population. We investigated the presence of BRCA mutations in 53 individuals with a personal and family history of breast and/or ovarian cancer, and 52 individuals with a personal history of breast cancer diagnosed below age 50 without additional family history. We have identified 11 mutations (nine BRCA1 and two BRCA2) using combined techniques involving protein truncation test, direct sequencing and heteroduplex analysis. We found eight out of 53 patients (15.1%) with a family history to carry BRCA gene mutations (seven BRCA1 and one BRCA2). Of these, four were found in 43 families presenting only breast cancer histories, and four were found in families presenting ovarian cancer with or without breast cancer. We also demonstrated two BRCA1 and one BRCA2 mutations in three out of 52 (5.8%) early-onset breast cancer cases without additional family history. Three of nine BRCA1 and both BRCA2 mutations detected in this study were not reported previously. These mutations may be specific to the Turkish population. The BRCA1 5382insC mutation, specific to Ashkenazi and Russian populations, was found twice in our study group, representing a possible founder mutation in the Turkish population. © 2000 Cancer Research Campaig
A novel form of recessive limb girdle muscular dystrophy with mental retardation and abnormal expression of alpha-dystroglycan
Cataloged from PDF version of article.The limb girdle muscular dystrophies are a heterogeneous group of conditions characterized by proximal muscle weakness and disease onset ranging from infancy to adulthood. We report here eight patients from seven unrelated families affected by a novel and relatively mild form of autosomal recessive limb girdle muscular dystrophy (LGMD2) with onset in the first decade of life and characterized by severe mental retardation but normal brain imaging. Immunocytochemical studies revealed a significant selective reduction of α-dystroglycan expression in the muscle biopsies. Linkage analysis excluded known loci for both limb girdle muscular dystrophy and congenital muscular dystrophies in the consanguineous families. We consider that this represents a novel form of muscular dystrophy with associated brain involvement. The biochemical studies suggest that it may belong to the growing number of muscular dystrophies with abnormal expression of α-dystroglycan. © 2003 Published by Elsevier B.V
Lepton polarization asymmetry in radiative dileptonic B-meson decays in MSSM
In this paper we study the polarization asymmetries of the final state lepton
in the radiative dileptonic decay of B meson (\bsllg) in the framework of
Minimal Supersymmetric Standard Model (MSSM) and various other unified models
within the framework of MSSM e.g. mSUGRA, SUGRA (where condition of
universality of scalar masses is relaxed) etc. Lepton polarization, in addition
of having a longitudinal component (\pl), can have two other components, \pt
and \pn, lying in and perpendicular to the decay plane, which are proportional
to \ml and hence are significant for final state being or
. We analyse the dependence of these polarization asymmetries
on the parameters of the various models.Comment: typos corrected to match with published versio
Comparisons of observed and modelled lake δ18O variability
With the substantial number of lake sediment δ18O records published in recent decades, a quantitative, process-based understanding of these systems can increase our understanding of past climate change. We test mass balance models of lake water δ18O variability against five years of monthly monitoring data from lakes with different hydrological characteristics, in the East-Midlands region of the UK, and the local isotope composition of precipitation. These mass balance models can explain up to 74% of the measured lake water isotope variability. We investigate the sensitivity of the model to differing calculations of evaporation amount, the amount of groundwater, and to different climatic variables. We show there is only a small range of values for groundwater exchange flux that can produce suitable lake water isotope compositions and that variations in evaporation and precipitation are both required to produce recorded isotope variability in lakes with substantial evaporative water losses. We then discuss the potential for this model to be used in a long-term, palaeo-scenario. This study demonstrates how long term monitoring of a lake system can lead to the development of robust models of lake water isotope compositions. Such systematics-based explanations allow us to move from conceptual, to more quantified reconstructions of past climates and environments
Quantitative radiologic criteria for the diagnosis of lumbar spinal stenosis: a systematic literature review
Background: Beside symptoms and clinical signs radiological findings are crucial in the diagnosis of lumbar spinal stenosis (LSS). We investigate which quantitative radiological signs are described in the literature and which radilogical criteria are used to establish inclusion criteria in clincical studies evaluating different treatments in patients with lumbar spinal stenosis.
Methods: A literature search was performed in Medline, Embase and the Cochrane library to identify papers reporting on radiological criteria to describe LSS and systematic reviews investigating the effects of different treatment modalities.
Results: 25 studies reporting on radiological signs of LSS and four systematic reviews related to the evaluation of different treatments were found. Ten different parameters were identified to quantify lumbar spinal stenosis. Most often reported measures for central stenosis were antero-posterior diameter (< 10 mm) and cross-sectional area (< 70 mm2) of spinal canal. For lateral stenosis height and depth of the lateral recess, and for foraminal stenosis the foraminal diameter were typically used. Only four of 63 primary studies included in the systematic reviews reported on quantitative measures for defining inclusion criteria of patients in prognostic studies.
Conclusions: There is a need for consensus on well-defined, unambiguous radiological criteria to define lumbar spinal stenosis in order to improve diagnostic accuracy and to formulate reliable inclusion criteria for clinical studies
Serum neurofilament light chain levels are associated with white matter integrity in autosomal dominant Alzheimer's disease
Neurofilament light chain (NfL) is a protein that is selectively expressed in neurons. Increased levels of NfL measured in either cerebrospinal fluid or blood is thought to be a biomarker of neuronal damage in neurodegenerative diseases. However, there have been limited investigations relating NfL to the concurrent measures of white matter (WM) decline that it should reflect. White matter damage is a common feature of Alzheimer's disease. We hypothesized that serum levels of NfL would associate with WM lesion volume and diffusion tensor imaging (DTI) metrics cross-sectionally in 117 autosomal dominant mutation carriers (MC) compared to 84 non-carrier (NC) familial controls as well as in a subset (N = 41) of MC with longitudinal NfL and MRI data. In MC, elevated cross-sectional NfL was positively associated with WM hyperintensity lesion volume, mean diffusivity, radial diffusivity, and axial diffusivity and negatively with fractional anisotropy. Greater change in NfL levels in MC was associated with larger changes in fractional anisotropy, mean diffusivity, and radial diffusivity, all indicative of reduced WM integrity. There were no relationships with NfL in NC. Our results demonstrate that blood-based NfL levels reflect WM integrity and supports the view that blood levels of NfL are predictive of WM damage in the brain. This is a critical result in improving the interpretability of NfL as a marker of brain integrity, and for validating this emerging biomarker for future use in clinical and research settings across multiple neurodegenerative diseases
Thermoeconomic and thermoenvironomic modeling and analysis of selected gas turbine power plants in Nigeria
This study presents comprehensive thermoeconomic and thermoenvironomic
modeling and analysis of selected gas turbine power plants in Nigeria using the
first and second laws of thermodynamics (exergy) concept. Exergetic analysis
was conducted using operating data obtained from the power plants to determine
the exergy destruction and exergy efficiency of each major component of the
gas turbine in each power plant. The results of the study showed that the combustion
chamber (CC) is the most exergy destructive component compared to
other cycle components. The percentage of exergy destruction in CC varies between
86.05% and 94.6%. By increasing the gas turbine inlet temperature (GTIT),
the exergy destruction of this component can be reduced. The total exergy improvement
potential of the selected plants varies from 54.04 to 159.88 MW. The
component with the highest exergy improvement potential is the CC, which has
the value that varies from 30.21 to 88.86 MW. Thermoeconomic analysis showed
that the cost of exergy destruction is high in the CC, and an increase in the
GTIT effectively decreases this cost. The exergy costing analysis revealed that the
unit cost of electricity produced in the plants ranged from cents 1.99/kWh (N3.16/
kWh) to cents 5.65 /kWh (N8.98/kWh). Thermoenvironomic analysis showed
that the CO2 emissions varied between 100.18 and 408.78 kg CO2/MWh, while
cost rate of environmental impact varied from 40.18 /h (44, 038. 23 N/h). The results further showed that CO2 emissions
and cost of environmental impact decrease with increasing GTIT. The sustainability
index increase with increasing GTIT. Finally, this study will assist efforts
to understand the thermodynamic losses in the gas turbine cycle, and to improve
efficiency as well as provide future recommendations for better performance,
sustainability, and lessening environmental impact of power plant
Trust and Quality of Growth: A Note
The transition from Millennium Development Goals (MDGs) to Sustainable Development
Goals (SDGs) has substantially shifted the policy debate from growth to inclusive growth. In
this short note, we revisit the trust-growth nexus by exploiting a dataset on quality of growth
(QG), recently made available to the scientific community. The empirical evidence is based
on interactive contemporary and non-contemporary quantile regressions. Inequality and
human development modifying variables are used as additional controls. The findings broadly
support the positive role of trust in QG. In addition, relatively high thresholds of inequality
are needed to change this positive trust-QG nexus in some distributions.https://jpconley.wordpress.com/economics-bulletinhb2017Economic
- …