2,655 research outputs found

    Age, Growth, Life History, and Fisheries of the Sand Sole, Psettichthys melanostictus

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    Sand sole, Psettichthys melanostictus, is a small but important part of the west coast groundfish fishery. It has never been assessed and there is a limited amount of biological data for the species. We provide the first estimates of age and growth for California populations and compare them with studies from other areas. We found that sand sole is a rapidly growing species which may show a strong latitudinal gradient in growth rate. We also found evidence of a recent, strong cohortrelated shift in the sex ratio of the population towards fewer females. In addition we examined data from the Washington, Oregon, and California commercial fishery to make an initial determination of population status. We found that catch per unit of effort in commercial trawls experienced a decline over time but has rebounded in recent years, except central California (the southern part of its commercial range), where the decline has not reversed

    Velocity contrast across the San Andreas fault in central California: Small-scale variations from P-wave nodal plane distortion

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    Systematic variations in P-wave radiation patterns, evident in a data set of 400 central California earthquakes, have been analyzed for variations in velocity contrast across the San Andreas fault zone. Vertical strike-slip faulting characterizes the region, with radiation patterns well constrained by the dense local seismographic station network. A discontinuity in crustal velocity occurs across the San Andreas fault. The distribution of systematically inconsistent first motions indicates that first arrivals observed along the fault plane within the northeastern block have followed refracted paths through the higher velocity crustal rocks to the southwest, retaining P-wave polarities characteristic of the quadrant of origin, and thus appearing reversed. A simple geometrical interpretation, with P waves refracted at the fault plane near the focus, yields the velocity contrast across the fault zone; the distribution of hypocenters allows its mapping in time and space. The velocity contrast so determined ranges up to 15 per cent, for a depth range of 1 to 10 km. The observed pattern of contrast values is coherent, with the greatest contrast related apparently in space, and possibly in time, to the larger earthquakes occurring on the fault. We suggest the phenomenon reflects changes in stress state at the fault and, by virtue of its ease of measurement, offers a new and valuable technique in earthquake studies

    The ADAM environment and transputers

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    The ADAM environment is both used for data analysis by Starlink and for data acquisition by the UK-involved observatories in Australia, Hawaii, and the Canary Islands. ADAM was originally hosted under VAX/VMS but is now at an advanced stage of a Unix port. ADAM comprises a parameter system, hierarchical data system, noticeboard system, error handling system, and other components. Originally a multi-tasking single processor environment, it has been enhanced to a multiprocessor environment using local or wide area networking. The Royal Observatory Edinburgh is producing a transputer version of the ADAM kernel to allow instruments which make use of transputers for data acquisition/control to integrate more closely with the ADAM software running at the telescopes. Communication into the transputer system is based on Ethernet carrying TCP/IP, which eases development toward a network of mixed VMS/Unix/transputer Telescope systems. The transputer system is being applied to instruments under development for the UKIRT and JCMT telescopes

    To determine if there is a clinical significance in changing the sequence of the positive relative accommodation and negative relative accommodation findings in the standard optometric extension program routine

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    The purpose of this study was to determine if there was a significant difference in magnitude of the findings if the sequence of taking the positive relative accomrnodation (#20) and negative relative accommodation (#21) in the standard Optometric Extension Program routine were reversed

    Plasma modeling for a nonsymmetric capacitive discharge driven by a nonsinusoidal radio frequency current

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    An analytical solution for the sheath dynamics of an asymmetrically driven capacitively coupled plasma is obtained under the assumptions of time-independent, collisionless ion motion, inertialess electrons, and uniform current density. Modeling is performed considering that the plasma is driven by a nonsinusoidal radio frequency (rf) current which can be resolved into a finite number of harmonic components. Together with different sheath parameters the equation for the bulk plasma impedance is also obtained to calculate the overall plasma impedance and the overall rf voltage. Assuming equal plate areas the solution for a symmetric discharge is also obtainable from this model. We have found that the even harmonic components of rf voltage and impedance are always present, even in a symmetric discharge. Experimental results are shown to be in qualitative agreement with the theoretical model. The values of normalized rf voltage and impedance harmonics assume lower values as the asymmetry of the plasma chamber decreases

    Development and evaluation of a training program for pediatric residents on physical activity interventions

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    Physical activity (PA) provides numerous health benefits; however, PA levels decline as children age. Primary care-based physical activity interventions (PAI) are moderately effective in increasing youth PA levels. Medical organizations recommend that physicians provide PAI; however, physician PAI rates are low. There are several barriers to PAI, including physicians' lack of PAI knowledge and skills. PAI medical education is severely limited. Therefore, there is a need to develop and evaluate medical education PAI curricula. The primary purpose of this study was to develop, implement, and evaluate a PAI curriculum for pediatric residents; focusing on pre to posttest changes in residents' PAI knowledge, attitudes, and behaviors (KAB). The secondary purpose was to determine residents' perceptions of the instructional strategies. An embedded mixed methods design was used, with qualitative data embedded in quantitative data. Participants (n = 13) were administered the KAB Assessment before and after the program and a Participant Feedback form after the program. Additionally, instructor field notes and focus group responses were collected. A paired t test showed a significant pretest to posttest increase in PAI knowledge scores. A MANOVA indicated a significant increase in positive PAI attitudes. Follow-up univariate analyses showed significant effects and near significant effects for the attitudes constructs of perceived knowledge and feasibility, respectively. Paired t tests showed a significant increase only for the PAI behavior of PA prescription. However, participants reported higher rates of PAI behaviors than in previous literature. Most useful, least useful, and alternative instructional strategies were considered; along with limitations, strengths, and future directions for this PAI curriculum study

    Phenotypic microarrays suggest Escherichia coli ST131 is not a metabolically distinct lineage of extra-intestinal pathogenic E. coli

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    Extraintestinal pathogenic E. coli (ExPEC) are the major aetiological agent of urinary tract infections (UTIs) in humans. The emergence of the CTX-M producing clone E. coli ST131 represents a major challenge to public health worldwide. A recent study on the metabolic potential of E. coli isolates demonstrated an association between the E. coli ST131 clone and enhanced utilisation of a panel of metabolic substrates. The studies presented here investigated the metabolic potential of ST131 and other major ExPEC ST isolates using 120 API test reagents and found that ST131 isolates demonstrated a lower metabolic activity for 5 of 120 biochemical tests in comparison to non-ST131 ExPEC isolates. Furthermore, comparative phenotypic microarray analysis showed a lack of specific metabolic profile for ST131 isolates countering the suggestion that these bacteria are metabolically fitter and therefore more successful human pathogens

    Continuous data assimilation for global numerical weather prediction

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    A new configuration of the European Centre for Medium-Range Weather Forecasts (ECMWF) incremental 4D-Var data assimilation (DA) system is introduced which builds upon the quasi-continuous DA concept proposed in the mid-1990s. Rather than working with a fixed set of observations, the new 4D-Var configuration exploits the near-continuous stream of incoming observations by introducing recently arrived observations at each outer loop iteration of the assimilation. This allows the analysis to benefit from more recent observations. Additionally, by decoupling the start time of the DA calculations from the observational data cut-off time, real-time forecasting applications can benefit from more expensive analysis configurations that previously could not have been considered. In this work we present results of a systematic comparison of the performance of a Continuous DA system against that of two more traditional baseline 4D-Var configurations. We show that the quality of the analysis produced by the new, more continuous configuration is comparable to that of a conventional baseline that has access to all of the observations in each of the outer loops, which is a configuration not feasible in real-time operational numerical weather prediction. For real-time forecasting applications, the Continuous DA framework allows configurations which clearly outperform the best available affordable non-continuous configuration. Continuous DA became operational at ECMWF in June 2019 and led to significant 2 to 3% reductions in medium-range forecast root mean square errors, which is roughly equivalent to 2-3 hr of additional predictive skill.Peer reviewe
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