297 research outputs found
Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acousticâtrawl surveys
The abundances and distributions of coastal pelagic fish
species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were
unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the ânorthern stockâ since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was
low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased
from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California
Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target
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Proximate analysis of Lentinus squarrosulus (Mont.) Singer and Psathyrella atroumbonata Pegler
Lentinus squarrosulus and Psathyrella atroumbonata, two mushroom species commonly found
growing on dead leaves and logs, were collected from the Zaria environ and taken to the laboratory for
further studies. Each of the mushroom species was separated into its stipe and pileus and used for
proximate analysis. There was a highly significant difference (p<0.01) in the proximate composition of
the two species. P. atroumbonata had significantly higher crude protein, crude fibre and moisture
content than L. squarrosulus while the reverse was the case for ash, dry matter, crude fat and soluble
carbohydrates. In addition, there was a highly significant difference (p<0.01) in the proximate
composition of the different mushroom parts. The pilei contained significantly higher amounts of crude
protein, crude fibre, ash, and dry matter than the stipes while the converse was the case for moisture,
crude fat and soluble carbohydrates. There was also a highly significant difference (p<0.01) in the
interaction of species by part
Data Fusion Tool for Spiral Bevel Gear Condition Indicator Data
Tests were performed on two spiral bevel gear sets in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig to simulate the fielded failures of spiral bevel gears installed in a helicopter. Gear sets were tested until damage initiated and progressed on two or more gear or pinion teeth. During testing, gear health monitoring data was collected with two different health monitoring systems. Operational parameters were measured with a third data acquisition system. Tooth damage progression was documented with photographs taken at inspection intervals throughout the test. A software tool was developed for fusing the operational data and the vibration based gear condition indicator (CI) data collected from the two health monitoring systems. Results of this study illustrate the benefits of combining the data from all three systems to indicate progression of damage for spiral bevel gears. The tool also enabled evaluation of the effectiveness of each CI with respect to operational conditions and fault mode
Turbulent Chemical Diffusion in Convectively Bounded Carbon Flames
It has been proposed that mixing induced by convective overshoot can disrupt
the inward propagation of carbon deflagrations in super-asymptotic giant branch
stars. To test this theory, we study an idealized model of convectively bounded
carbon flames with 3D hydrodynamic simulations of the Boussinesq equations
using the pseudospectral code Dedalus. Because the flame propagation timescale
is much longer than the convection timescale, we approximate the flame as fixed
in space, and only consider its effects on the buoyancy of the fluid. By
evolving a passive scalar field, we derive a {\it turbulent} chemical
diffusivity produced by the convection as a function of height, .
Convection can stall a flame if the chemical mixing timescale, set by the
turbulent chemical diffusivity, , is shorter than the flame
propagation timescale, set by the thermal diffusivity, , i.e., when
. However, we find for most of the flame
because convective plumes are not dense enough to penetrate into the flame.
Extrapolating to realistic stellar conditions, this implies that convective
mixing cannot stall a carbon flame and that "hybrid carbon-oxygen-neon" white
dwarfs are not a typical product of stellar evolution.Comment: Accepted to Ap
Toxicity Evaluation of the Liver and in vitro Metabolism in Wistar Rat on Exposure to N-Nitrosamine Precursors
The aim of this study is to evaluate liver toxicity on exposure to n-nitrosamine precursors as well as the
effect of ultraviolet light on n-nitrosamines and its precursors. Toxicological evaluation of the liver
following single dose treatment of wistar rat with 8.2125 mg NaNO2/adult rat and in rats given a
combined dose of 50 mgDMA-HCl and 8.2125 mg NaNO2/adult rat showed a steady elevation of the
liver function enzymes. Histopathological analysis of the liver showed hepatic necrosis in the chemical
induced rats. Following UV exposure after in vitro incubation of rat liver microsomal plus soluble fraction
with NaNO2 and NaNO2 plus DMA-HCl, nitrite concentration in the NaNO2 incubation medium was 19.5
and 2.2 ÎŒg/mL before and after UV exposure respectively while the nitrite concentration in the NaNO2
plus DMA-HCl incubation medium was 23.5 and 2.5 ÎŒg/mL, respectively. Nitrite loss was significant
(p<0.05) between before and after UV exposure in all groups. UV exposure, thus degraded the
nitrosamine precursors, nitrite and DMA-HCl, thereby inhibiting possible nitrosation. The high values of
the activities of serum transaminases (AST and ALT), alkaline phosphatases (ALP) and gammaglutamyltransferses
(Îł-GT), relative to control values are indicative of severe intrahepatic cell damag
Aquifer Vulnerability Mapping in Katsina-Ala Area, Central Nigeria Using Integrated Electrical Conductivity (IEC)
The present demand for water are not only to detect and develop new groundwater systems to meet up with the millennium development goals, but also to protect existing water reservoirs against contaminants. This research work is aimed at mapping out aquifer vulnerability by integrated electrical conductivity (IEC) in Katsina-Ala area, Central Nigeria. With Schlumberger configuration, Twenty-Six (26) vertical electrical soundings (VES) were occupied in the present study using Abem terrameter SAS 300c at the peak of dry season (January to March) from which the VES data collected was interpreted for geo-electrical parameters. The parameters estimated for overburden was used to calculate the IEC and was indexed to generate a vulnerability map of the study area. The indexes revealed three strong regimes which include vulnerable ( , highly vulnerable (IEC Â and extremely vulnerable (IEC from 0 to 1240èł10-3siesmens)"> . The result will aid in the design of modalities for monitoring and protection of aquifer front against contaminants in the study area. Keywords: Aquifer, Integrated electrical conductivity, Overburden, Vulnerability, Katsina-Al
Detection of chemical warfare agent simulants and hydrolysis products in biological samples by paper spray mass spectrometry
Paper spray ionization coupled to a high resolution tandem mass spectrometer (a quadrupole orbitrap) was used to identify and quantitate chemical warfare agent (CWA) simulants and their hydrolysis products in blood and urine. Three CWA simulants, dimethyl methylphosphonate (DMMP), trimethyl phosphate (TMP), and diisopropyl methylphosphonate (DIMP), and their isotopically labeled standards were analyzed in human whole blood and urine. Calibration curves were generated and tested with continuing calibration verification standards. Limits of detection for these three compounds were in the low ng mLâ1 range for the direct analysis of both blood and urine samples. Five CWA hydrolysis products, ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA), isobutyl methylphosphonic acid (iBuMPA), cyclohexyl methylphosphonic acid (CHMPA), and pinacolyl methylphosphonic acid (PinMPA), were also analyzed. Calibration curves were generated in both positive and negative ion modes. Limits of detection in the negative ion mode ranged from 0.36 ng mLâ1 to 1.25 ng mLâ1 in both blood and urine for the hydrolysis products. These levels were well below those found in victims of the Tokyo subway attack of 2 to 135 ng mLâ1. Improved stability and robustness of the paper spray technique in the negative ion mode was achieved by the addition of chlorinated solvents. These applications demonstrate that paper spray mass spectrometry (PS-MS) can be used for rapid, sample preparation-free detection of chemical warfare agents and their hydrolysis products at physiologically relevant concentrations in biological samples
Synthesis and Antifungal Activity of Some Organotin(IV) Carboxylates
Six diorganotin(IV) carboxylates prepared by reacting diorganotin(IV) dichlorides with the
respective silver carboxylate have been tested for antifungal activity against Aspergillus. niger, Aspergilluus flavus and Pencillium. citrinum in Sabourand dextrose broth. The compounds
generally exhibit greater fungitoxicity than the diorganotin(IV) dichlorides and the carboxylic acids
from which they were synthesized. In keeping with the generally accepted notion that the
organotin moiety plays an important role in deciding the antifungal activity of an organotin
compound, the diphenyltin(IV) compounds were more active than their di-n-butyltin(IV) analogues.
However, the order of increasing fungitoxicity of the compounds parallels that of the uncomplexed
carboxylic acids. The implications of the results are discussed
Role of the cation-chloride-cotransporters in the circadian system
This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this recordâŻThe circadian system plays an immense role in controlling physiological processes in our body. The suprachiasmatic nucleus (SCN) supervises this system, regulating and harmonising the circadian rhythms in our body. Most neurons present in the SCN are GABAergic neurons. Although GABA is considered the main inhibitory neurotransmitter of the CNS, recent studies have shown that excitatory responses were recorded in this area. These responses are enabled by increase in intracellular chloride ions [Clâ]i levels. The chloride (Clâ) levels in GABAergic neurons are controlled by two solute carrier 12 (SLC12) cation-chloride-cotransporters (CCCs): Na+/K+/Clâ co-transporter (NKCC1) and K+/Clâ co-transporter (KCC2), that respectively cause an influx and efflux of Clâ. Recent works have found altered expression and/or activity of either of these co-transporters in SCN neurons have been associated with circadian rhythms. This review, we summarize and discuss the role of CCCs in circadian rhythms, and highlight these recent advances which attest to CCC's growing potential as strong research and therapeutic targets.National Institutes of Healt
Driving Habits, Cognition, and Health-Related Quality of Life in Middle-Aged and Older Adults with HIV
Cognitive impairment is known to increase with aging in people living with HIV (PLWH). Impairment in cognitive domains required for safe driving may put PLWH at risk for poor driving outcomes, decreased mobility, and health-related quality of life (HRQoL). This study described the driving behaviors of middle-aged and older PLWH and examined correlations between driving behaviors and cognitive functioning (Aim 1), and driving behaviors and HRQoL domains (Aim 2). A sample of 260 PLWH ages 40 and older completed a comprehensive assessment including a battery of cognitive tests, an HRQoL measure, and a measure of self-reported driving habits. Associations between driving habits, cognitive function, and HRQoL domains were examined. While 212 (81.54%) participants reported currently driving, only 166 (63.85%) possessed a driver\u27s license. Several significant correlations emerged between driving habits and both cognitive and HRQoL variables, with a general pattern suggesting that current greater driving exposure was associated with better cognitive functioning and HRQoL. Given consistent associations that emerged between the social functioning HRQoL domain and several driving habits, multivariable regression was conducted to examine the unique association between an index of greater driving exposure (i.e., days driven per week) and social functioning, adjusting for potential confounders (race, income, education, depression, and global cognition). Results showed that more days driven per week was a significant, independent correlate of higher social functioning. Understanding the factors underlying driving behaviors in PLWH may contribute to interventions to promote better mobility and improved access to care
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