4,917 research outputs found
Laterally pumped GaAs/AlGaAs quantum wells as sources of broadband terahertz radiation
In this work we consider lateral current pumped GaAs/AlGaAs quantum wells as sources of incoherent terahertz radiation. The lateral field heats the electrons in a two-dimensional quantum layer and increases the population of higher subbands, hence also increasing the radiation power generated in spontaneous intersubband emission processes. Digitally graded quasi-parabolic and simple square quantum wells are considered, and the advantages of both types are discussed. Calculations at lattice temperatures of 77 K and 300 K, for electric fields up to 10 kV/cm, show that the optical output power of ~100−200 W/m2 may be achieved for the 7 THz source. The main peak of the spectrum, at 7 THz, of the quasi-parabolic quantum well exceeds the black body radiation at 300 K by approximately a factor of two and by two orders of magnitude at 77 K
Detecting early signs of depressive and manic episodes in patients with bipolar disorder using the signature-based model
Recurrent major mood episodes and subsyndromal mood instability cause
substantial disability in patients with bipolar disorder. Early identification
of mood episodes enabling timely mood stabilisation is an important clinical
goal. Recent technological advances allow the prospective reporting of mood in
real time enabling more accurate, efficient data capture. The complex nature of
these data streams in combination with challenge of deriving meaning from
missing data mean pose a significant analytic challenge. The signature method
is derived from stochastic analysis and has the ability to capture important
properties of complex ordered time series data. To explore whether the onset of
episodes of mania and depression can be identified using self-reported mood
data.Comment: 12 pages, 3 tables, 10 figure
STIMULUS-RESPONSE IN THE MIXED LYMPHOCYTE REACTION
Mixed lymphocyte reactions occur when mouse spleen cell populations depleted of thymus-derived (T) lymphocytes are cultured with allogeneic target cells inactivated by mitomycin C or X irradiation, and when F1 hybrid responder cells are cultured with inactivated parental target cells. These responses might be interpreted as indicating that T lymphocytes are not required for responsiveness and that F1 lymphocytes recognize parental alloantigens. Data reported here indicate that the more likely explanation for these surprising results is that inactivated target cells recognize the "responding" cells and this recognition leads to the response observed
Restoration of Cervical and Lumbar Lordosis: CBP® Methods Overview
Low back and neck pain disorders are among the leading causes for work loss, suffering, and health care expenditures throughout the industrialized world. It has been extensively demonstrated that sagittal plane alignment of the cervical and lumbar spines impacts human health and well-being. Today there are reliable and predictable means through the application of extension spinal traction as part of comprehensive rehabilitation programs to restore the natural curvatures of the spine. High-quality evidence points to Chiropractic BioPhysics® (CBP®) methods offering superior long-term outcomes for treating patients with various craniocervical and lumbosacral disorders. CBP technique is a full spine and posture rehabilitation approach that incorporates mirror image® exercises, spinal and postural adjustments, and unique traction applications in the restoration of normal/ideal spinal alignment. Recent randomized controlled trials using CBP’s unique extension traction methods in conjunction with various conventional physiotherapeutic methods have demonstrated those who restore normal lordosis (cervical or lumbar) get symptomatic relief that lasts up to 2 years after treatment. Comparative groups receiving various ‘cookie-cutter’ conventional treatments experience only temporary symptomatic relief that regresses as early as 3 months after treatment. The economic impact/benefit of CBPs newer sagittal spine rehabilitation treatments demand continued attention from clinicians and researchers alike
Experimentally verified parameter sets for modelling heterogeneous neocortical pyramidal-cell populations
Models of neocortical networks are increasingly including the diversity of excitatory and inhibitory neuronal classes. Significant variability in cellular properties are also seen within a nominal neuronal class and this heterogeneity can be expected to influence the population response and information processing in networks. Recent studies have examined the population and network effects of variability in a particular neuronal parameter with some plausibly chosen distribution. However, the empirical variability and covariance seen across multiple parameters are rarely included, partly due to the lack of data on parameter correlations in forms convenient for model construction. To addess this we quantify the heterogeneity within and between the neocortical pyramidal-cell classes in layers 2/3, 4, and the slender-tufted and thick-tufted pyramidal cells of layer 5 using a combination of intracellular recordings, single-neuron modelling and statistical analyses. From the response to both square-pulse and naturalistic fluctuating stimuli, we examined the class-dependent variance and covariance of electrophysiological parameters and identify the role of the h current in generating parameter correlations. A byproduct of the dynamic I-V method we employed is the straightforward extraction of reduced neuron models from experiment. Empirically these models took the refractory exponential integrate-and-fire form and provide an accurate fit to the perisomatic voltage responses of the diverse pyramidal-cell populations when the class-dependent statistics of the model parameters were respected. By quantifying the parameter statistics we obtained an algorithm which generates populations of model neurons, for each of the four pyramidal-cell classes, that adhere to experimentally observed marginal distributions and parameter correlations. As well as providing this tool, which we hope will be of use for exploring the effects of heterogeneity in neocortical networks, we also provide the code for the dynamic I-V method and make the full electrophysiological data set available
A Preliminary Annotated Checklist of Mississippi Mecoptera (Insecta)
We summarize distribution records for 22 Mecoptera species known to occur in Mississippi. These include the fi rst specimens of Bittacus occidentis Walker, B. strigosus Hagen, Hylobittacus apicalis (Hagen) and Panorpa insolens Carpenter to be recorded from the state
A Preliminary Annotated Checklist of Mississippi Mecoptera (Insecta)
We summarize distribution records for 22 Mecoptera species known to occur in Mississippi. These include the fi rst specimens of Bittacus occidentis Walker, B. strigosus Hagen, Hylobittacus apicalis (Hagen) and Panorpa insolens Carpenter to be recorded from the state
A Preliminary Annotated Checklist of Mississippi Mecoptera (Insecta)
We summarize distribution records for 22 Mecoptera species known to occur in Mississippi. These include the fi rst specimens of Bittacus occidentis Walker, B. strigosus Hagen, Hylobittacus apicalis (Hagen) and Panorpa insolens Carpenter to be recorded from the state
Anthropogenic nutrients and harmful algae in coastal waters
© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Environmental Management 146 (2014): 206-216, doi:10.1016/j.jenvman.2014.07.002.Harmful algal blooms (HABs) are thought to be increasing in coastal waters worldwide. Anthropogenic nutrient enrichment has been proposed as a principal causative factor of this increase through elevated inorganic and/or organic nutrient concentrations and modified nutrient ratios. We assess: 1) the level of understanding of the link between the amount, form and ratio of anthropogenic nutrients and HABs; 2) the evidence for a link between anthropogenically generated HABs and negative impacts on human health; and 3) the economic implications of anthropogenic nutrient/HAB interactions. We demonstrate that an anthropogenic nutrient-HAB link is far from universal, and where it has been demonstrated, it is most frequently associated with high biomass rather than low biomass (biotoxin producing) HABs. While organic nutrients have been shown to support the growth of a range of HAB species, insufficient evidence exists to clearly establish if these nutrients specifically promote the growth of harmful species in preference to benign ones, or if/how they influence toxicity of harmful species. We conclude that the role of anthropogenic nutrients in promoting HABs is site-specific, with hydrodynamic processes often determining whether blooms occur. We also find a lack of evidence of widespread significant adverse health impacts from anthropogenic nutrient-generated HABs, although this may be partly due to a lack of human/animal health and HAB monitoring. Detailed economic evaluation and cost/benefit analysis of the impact of anthropogenically generated HABs, or nutrient reduction schemes to alleviate them, is also frequently lacking.The work described here is based in part on a project ‘Harmful Algae, Nuisance Blooms and Anthropogenic Nutrient Enrichment’ funded by the UK Department for Environment, Food and Rural Affairs (contract ME2208). In addition KD was supported by the FP7 project Asimuth and funding from the NERC Shelf Seas Biogeochemistry and PURE Associates programmes. PJH was supported by University Grants Council of Hong Kong AoE project (AoE/P-04/0401). PH and LEF were funded by the US National Science Foundation (NSF) Award 1009106; LEF was funded in part by the European Regional Development Fund and European Social Fund (University of Exeter, Truro, Cornwall, UK). GM was supported by a NERC PhD studentship
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Prevalence of iron deficiency in 62,685 women of seven race/ethnicity groups: The HEIRS Study.
BackgroundFew cross-sectional studies report iron deficiency (ID) prevalence in women of different race/ethnicity and ages in US or Canada.Materials and methodsWe evaluated screening observations on women who participated between 2001-2003 in a cross-sectional, primary care-based sample of adults ages ≥25 y whose observations were complete: race/ethnicity; age; transferrin saturation; serum ferritin; and HFE p.C282Y and p.H63D alleles. We defined ID using a stringent criterion: combined transferrin saturation <10% and serum ferritin <33.7 pmol/L (<15 μg/L). We compared ID prevalence in women of different race/ethnicity subgrouped by age and determined associations of p.C282Y and p.H63D to ID overall, and to ID in women ages 25-44 y with or without self-reported pregnancy.ResultsThese 62,685 women included 27,079 whites, 17,272 blacks, 8,566 Hispanics, 7,615 Asians, 449 Pacific Islanders, 441 Native Americans, and 1,263 participants of other race/ethnicity. Proportions of women with ID were higher in Hispanics and blacks than whites and Asians. Prevalence of ID was significantly greater in women ages 25-54 y of all race/ethnicity groups than women ages ≥55 y of corresponding race/ethnicity. In women ages ≥55 y, ID prevalence did not differ significantly across race/ethnicity. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy.ConclusionsID prevalence was greater in Hispanic and black than white and Asian women ages 25-54 y. p.C282Y and p.H63D prevalence did not differ significantly in women with or without ID, regardless of race/ethnicity, age subgroup, or pregnancy
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