550 research outputs found
Oxygen Dependence of Omeprazole Clearance and Sulfone and Sulfide Metabolite Formation in the Isolated Perfused Rat Liver1
ABSTRACT and hemoglobin content of perfusate)
Understanding Determinants of Hunting Trip Productivity in an Arctic Community
We examine factors underlying hunting productivity among Inuit in Ulukhaktok, Northwest Territories, Canada. Specifically, we focus on the role of gasoline use as the main variable of interest—commonly cited as a crucial determinant of hunting participation. Over the course of 12 months, 10 hunters recorded their on-the-land activities using a GPS tracking system, participatory mapping sessions, and bi-weekly interviews. A multivariable linear regression model (MvLRM) was applied to assess whether factors such as consumables used (i.e. heating fuel, gasoline, oil, food), distances traveled, or the number of companions on a trip were associated with the mass of edible foods returned to the community. Results indicate that, despite being positively associated with hunting trip productivity when assessed through a univariable linear regression model, gasoline is not a statistically significant determinant of standalone trip yield when adjusting for other variables in a multivariable linear regression. Instead, factors relating to seasonality, number of companions, and days on the land emerged as more significant and substantive drivers of productivity while out on the land. The findings do not suggest that access to, or the availability of, gasoline does not affect whether a hunting trip commences or is planned, nor that an increase in the amount of gasoline available to a hunter might increase the frequency of trips (and therefore annual productivity). Rather, this work demonstrates that the volume of gasoline used by harvesters on standalone hunting trips represent a poor a priori predictor of the edible weight that harvesters are likely to return to the community
Effects of static and dynamic higher-order optical modes in balanced homodyne readout for future gravitational waves detectors
With the recent detection of Gravitational waves (GW), marking the start of the new field of GW astronomy, the push for building more sensitive laser-interferometric gravitational wave detectors (GWD) has never been stronger. Balanced homodyne detection (BHD) allows for a quantum noise (QN) limited readout of arbitrary light field quadratures, and has therefore been suggested as a vital building block for upgrades to Advanced LIGO and third generation observatories. In terms of the practical implementation of BHD, we develop a full framework for analyzing the static optical high order modes (HOMs) occurring in the BHD paths related to the misalignment or mode matching at the input and output ports of the laser interferometer. We find the effects of HOMs on the quantum noise limited sensitivity is independent of the actual interferometer configuration, e.g. Michelson and Sagnac interferometers are effected in the same way. We show that misalignment of the output ports of the interferometer (output misalignment) only effects the high frequency part of the quantum noise limited sensitivity (detection noise). However, at low frequencies, HOMs reduce the interferometer response and the radiation pressure noise (back action noise) by the same amount and hence the quantum noise limited sensitivity is not negatively effected in that frequency range. We show that the misalignment of laser into the interferometer (input misalignment) produces the same effect as output misalignment and additionally decreases the power inside the interferometer. We also analyze dynamic HOM effects, such as beam jitter created by the suspended mirrors of the BHD. Our analyses can be directly applied to any BHD implementation in a future GWD. Moreover, we apply our analytical techniques to the example of the speed meter proof of concept experiment under construction in Glasgow. We find that for our experimental parameters, the performance of our seismic isolation system in the BHD paths is compatible with the design sensitivity of the experiment
Demonstration of a switchable damping system to allow low-noise operation of high-Q low-mass suspension systems
Low mass suspension systems with high-Q pendulum stages are used to enable
quantum radiation pressure noise limited experiments. Utilising multiple
pendulum stages with vertical blade springs and materials with high quality
factors provides attenuation of seismic and thermal noise, however damping of
these high-Q pendulum systems in multiple degrees of freedom is essential for
practical implementation. Viscous damping such as eddy-current damping can be
employed but introduces displacement noise from force noise due to thermal
fluctuations in the damping system. In this paper we demonstrate a passive
damping system with adjustable damping strength as a solution for this problem
that can be used for low mass suspension systems without adding additional
displacement noise in science mode. We show a reduction of the damping factor
by a factor of 8 on a test suspension and provide a general optimisation for
this system.Comment: 5 pages, 5 figure
Natural growth rates in Antarctic krill (Euphausia superba): II. Predictive models based on food, temperature, body length, sex, and maturity stage
We used the instantaneous growth rate method to determine the effects of food, temperature, krill length, sex, and maturity stage on in situ summer growth of krill across the southwest Atlantic sector of the Southern Ocean. The main aims were to examine the separate effects of each variable and to generate a predictive model of growth based on satellite-derivable environmental data. Both growth increments in length on moulting (GIs) and daily growth rates (DGRs, mm d-1) ranged greatly among the 59 swarms, from 0.58–15% and 0.013–0.32 mm d-1. However, all swarms maintained positive mean growth, even those in the low chlorophyll a (Chl a) zone of the central Scotia Sea. Among a suite of indices of food quantity and quality, large-scale monthly Chl a values from SeaWiFS predicted krill growth the best. Across our study area, the great contrast between bloom and nonbloom regions was a major factor driving variation in growth rates, obscuring more subtle effects of food quality. GIs and DGRs decreased with increasing krill length and decreased above a temperature optimum of 0.5°C. This probably reflects the onset of thermal stress at the northern limit of krill’s range. Thus, growth rates were fastest in the ice edge blooms of the southern Scotia Sea and not at South Georgia as previously suggested. This reflects both the smaller size of the krill and the colder water in the south being optimum for growth. Males tended to have higher GIs than females but longer intermoult periods, leading to similar DGRs between sexes. DGRs of equivalent-size krill tended to decrease with maturity stage, suggesting the progressive allocation of energy toward reproduction rather than somatic growth. Our maximum DGRs are higher than most literature values, equating to a 5.7% increase in mass per day. This value fits within a realistic energy budget, suggesting a maximum carbon ration of ~20% d-1. Over the whole Scotia Sea/South Georgia area, the gross turnover of krill biomass was ~1% d-1
The effects of feed restriction, time of day and time since feeding on behavioral and physiological indicators of hunger in broiler breeder hens
Broiler breeder chickens are commercially feed restricted to slow their growth and improve their health and production, however, there is research demonstrating that this leads to chronic hunger resulting in poor welfare. A challenge in these studies is to account for possible daily rhythms or the effects of time since last meal on measures relating hunger. To address this, we used 3 feed treatments: AL (ad libitum fed), Ram (restricted, fed in the morning), and Rpm (restricted, fed in the afternoon) to control for diurnal effects. We then conducted foraging motivation tests and collected home pen behavior and physiological samples at 4 times relative to feeding throughout a 24-h period. The feed treatment had the largest influence on the data, with AL birds weighing more, having lower concentrations of plasma NEFA, and mRNA expression of AGRP and NPY alongside higher expression of POMC in the basal hypothalamus than Ram or Rpm birds (P < 0.001). R birds were more successful at and had a shorter latency to complete the motivation test, and did more walking and less feeding than AL birds in the home pen (P < 0.01). There was little effect of time since last meal on many measures (P > 0.05) but AGRP expression was highest in the basal hypothalamus shortly after a meal (P < 0.05), blood plasma NEFA was higher in R birds just before feeding (P < 0.001) and glucose was higher in Ram birds just after feeding (P < 0.001), and the latency to complete the motivation test was shortest before the next meal (P < 0.05). Time of day effects were mainly found in the difference in activity levels in the home pen when during lights on and lights off periods. In conclusion, many behavioral and physiological hunger measures were not significantly influenced by time of day or time since the last meal. For the measures that do change, future studies should be designed so that sampling is balanced in such a way as to minimize bias due to these effects.</p
The reintroduction of large carnivores to the Eastern Cape, South Africa: an assessment
Recently, conservation estate in South Africa's Eastern Cape Province has increased 10-fold resulting in large predators being increasingly reintroduced to restore ecological integrity and maximize tourism. We describe the reintroductions of large carnivores (>10 kg) that have occurred in the Eastern Cape and use various criteria to assess their success. Lion Panthera leo reintroduction has been highly successful with a population of 56 currently extant in the region and problems of overpopulation arising. The African wild dog Lycaon pictus population has increased to 24 from a founder population of 11. Preliminary results for spotted hyaenas Crocuta crocuta also indicate success. Wild populations of leopards Panthera pardus exist on several reserves and have been supplemented by translocated individuals, although deaths of known individuals have occurred and no estimate of reproduction is available. Cheetah Acinonyx jubatus reintroduction has also been less successful with 36 individuals reintroduced and 23 cubs being born but only 41 individuals surviving in 2005. Criteria for assessing the success of reintroductions of species that naturally occur in low densities, such as top predators, generally have limited value. Carrying capacity for large predators is unknown and continued monitoring and intensive management will be necessary in enclosed, and possibly all, conservation areas in the Eastern Cape to ensure conservation success
Update on new aspects of the renin-angiotensin system in liver disease: clinical implications and new therapeutic options
A B S T R A C T The RAS (renin-angiotensin system) is now recognized as an important regulator of liver fibrosis and portal pressure. Liver injury stimulates the hepatic expression of components of the RAS, such as ACE (angiotensin-converting enzyme) and the AT 1 receptor [AngII (angiotensin II) type 1 receptor], which play an active role in promoting inflammation and deposition of extracellular matrix. In addition, the more recently recognized structural homologue of ACE, ACE2, is also up-regulated. ACE2 catalyses the conversion of AngII into Ang-(1-7) [angiotensin-(1-7)], and there is accumulating evidence that this 'alternative axis' of the RAS has anti-fibrotic, vasodilatory and anti-proliferative effects, thus counterbalancing the effects of AngII in the liver. The RAS is also emerging as an important contributor to the pathophysiology of portal hypertension in cirrhosis. Although the intrahepatic circulation in cirrhosis is hypercontractile in response to AngII, resulting in increased hepatic resistance, the splanchnic vasculature is hyporesponsive, promoting the development of the hyperdynamic circulation that characterizes portal hypertension. Both liver fibrosis and portal hypertension represent important therapeutic challenges for the clinician, and there is accumulating evidence that RAS blockade may be beneficial in these circumstances. The present review outlines new aspects of the RAS and explores its role in the pathogenesis and treatment of liver fibrosis and portal hypertension
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