758 research outputs found

    Property Rights in a Fishery: Regulatory Change and Firm Performance

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    A new method is introduced and applied to analyse changes in productivity of firms harvesting a natural capital stock. The index-number technique decomposes the contributions of output prices, variable input prices, fixed inputs and productivity to firm profits, adjusted for changes in the natural capital stock. An application of the method is given using micro-level data from a common-pool resource. The indexes provide a ready-made comparison of all firms to the most profitable firm per unit of resource stock. Benchmarking with the decompositions also allows firms and regulators to determine what components are contributing most to economic profits and improve overall industry performance.productivity,profits,natural capital,index numbers

    In-Home Counseling for Young Children Living in Poverty: An Exploration of Counseling Competencies

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    Home-based counseling is increasingly an alternative mode of providing counseling services for children and families, reduces barriers to accessing traditional counseling services, and has also been shown to be effective. As such, the purpose of this qualitative study was to explore and describe the competencies needed to provide such counseling services. This study yielded five categories of competencies—necessary knowledge sets, case conceptualization, counseling behaviors, flexibility in session, and professional dispositions and behaviors. We also outline implications for counseling practice, counselor education, and public policy

    Capacity Reduction and Productivity: The Case of Fishery

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    The paper presents the first ex-post analysis of profit and productivity of individual vessels following a vessel or licence buyback in a fishery. Using individual firm-level data for the period 1997-2000, the paper analyzes a "natural experiment" of the effects of a 1997 scheme to reduce fishing capacity in the South East trawl fishery of Australia. The scheme was unique in the sense that the buyback was implemented in a fishery managed by individual vessel tradeable harvesting rights rather than input controls. Using an innovative index method that decomposes the contributions of output prices, input prices, vessel size and productivity to relative profits, the economic performance of vessels is analyzed in the year of the buyback and for three years afterwards. Profits for all vessel classes rose over the period 1997-2000 following the 1997 buyback of 27 fishing licenses, but some of the gains were due to a rise in output prices that were independent of the adjustment program. All vessel classes (small and large) also experienced substantial productivity gains immediately following the 1997 license buyback with an average increase over all vessels of 39%. This increase, coincident with a decline in catch per unit of effort for key species, provides strong support that the buyback was successful at improving economic performance. Ongoing productivity improvements for small vessels over the period 1998-2000 following the buyback is attributed to the existence of individual tradeable harvesting rights in the fishery.productivity, capacity reduction, fishery

    Adult cortical plasticity depends on an early postnatal critical period

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    Development of the cerebral cortex is influenced by sensory experience during distinct phases of postnatal development known as critical periods. Disruption of experience during a critical period produces neurons that lack specificity for particular stimulus features, such as location in the somatosensory system. Synaptic plasticity is the agent by which sensory experience affects cortical development. Here, we describe, in mice, a developmental critical period that affects plasticity itself. Transient neonatal disruption of signaling via the C-terminal domain of "disrupted in schizophrenia 1" (DISC1)-a molecule implicated in psychiatric disorders-resulted in a lack of long-term potentiation (LTP) (persistent strengthening of synapses) and experience-dependent potentiation in adulthood. Long-term depression (LTD) (selective weakening of specific sets of synapses) and reversal of LTD were present, although impaired, in adolescence and absent in adulthood. These changes may form the basis for the cognitive deficits associated with mutations in DISC1 and the delayed onset of a range of psychiatric symptoms in late adolescence

    A retrospective study of the impact of 21-gene recurrence score assay on treatment choice in node positive micrometastatic breast cancer.

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    To assess clinical utility of the 21-gene assay (Oncotype DX® Recurrence Score®), we determined whether women with HER2(−)/ER+ pN1mi breast cancer with low ( vs. 57.9% in the intermediate-risk group and 100% in the high-risk group (p \u3c 0.001). A total of 80.2% of the low-risk group were recommended endocrine therapy alone, while 77.8% of the high-risk group were recommended both endocrine and chemotherapy (p \u3c 0.001). The Oncotype DX Recurrence Score result provides actionable information that can be incorporated into treatment planning for women with HER2(−)/ER+ pN1mi breast cancer. The Recurrence Score result has clinical utility in treatment planning for HER2(−)/ER+ pN1mi breast cancer patients

    Aberrant Neuronal Dynamics during Working Memory Operations in the Aging HIV-Infected Brain

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    Impairments in working memory are among the most prevalent features of HIV-associated neurocognitive disorders (HAND), yet their origins are unknown, with some studies arguing that encoding operations are disturbed and others supporting deficits in memory maintenance. The current investigation directly addresses this issue by using a dynamic mapping approach to identify when and where processing in working memory circuits degrades. HIV-infected older adults and a demographically-matched group of uninfected controls performed a verbal working memory task during magnetoencephalography (MEG). Significant oscillatory neural responses were imaged using a beamforming approach to illuminate the spatiotemporal dynamics of neuronal activity. HIV-infected patients were significantly less accurate on the working memory task and their neuronal dynamics indicated that encoding operations were preserved, while memory maintenance processes were abnormal. Specifically, no group differences were detected during the encoding period, yet dysfunction in occipital, fronto-temporal, hippocampal, and cerebellar cortices emerged during memory maintenance. In addition, task performance in the controls covaried with occipital alpha synchronization and activity in right prefrontal cortices. In conclusion, working memory impairments are common and significantly impact the daily functioning and independence of HIV-infected patients. These impairments likely reflect deficits in the maintenance of memory representations, not failures to adequately encode stimuli

    Aberrant Neuronal Dynamics during Working Memory Operations in the Aging HIV-Infected Brain.

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    Impairments in working memory are among the most prevalent features of HIV-associated neurocognitive disorders (HAND), yet their origins are unknown, with some studies arguing that encoding operations are disturbed and others supporting deficits in memory maintenance. The current investigation directly addresses this issue by using a dynamic mapping approach to identify when and where processing in working memory circuits degrades. HIV-infected older adults and a demographically-matched group of uninfected controls performed a verbal working memory task during magnetoencephalography (MEG). Significant oscillatory neural responses were imaged using a beamforming approach to illuminate the spatiotemporal dynamics of neuronal activity. HIV-infected patients were significantly less accurate on the working memory task and their neuronal dynamics indicated that encoding operations were preserved, while memory maintenance processes were abnormal. Specifically, no group differences were detected during the encoding period, yet dysfunction in occipital, fronto-temporal, hippocampal, and cerebellar cortices emerged during memory maintenance. In addition, task performance in the controls covaried with occipital alpha synchronization and activity in right prefrontal cortices. In conclusion, working memory impairments are common and significantly impact the daily functioning and independence of HIV-infected patients. These impairments likely reflect deficits in the maintenance of memory representations, not failures to adequately encode stimuli

    Sensitivity of fluvial sediment source apportionment to mixing model assumptions: A Bayesian model comparison

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    Mixing models have become increasingly common tools for apportioning fluvial sediment load to various sediment sources across catchments using a wide variety of Bayesian and frequentist modeling approaches. In this study, we demonstrate how different model setups can impact upon resulting source apportionment estimates in a Bayesian framework via a one-factor-at-a-time (OFAT) sensitivity analysis. We formulate 13 versions of a mixing model, each with different error assumptions and model structural choices, and apply them to sediment geochemistry data from the River Blackwater, Norfolk, UK, to apportion suspended particulate matter (SPM) contributions from three sources (arable topsoils, road verges, and subsurface material) under base flow conditions between August 2012 and August 2013. Whilst all 13 models estimate subsurface sources to be the largest contributor of SPM (median ∼76%), comparison of apportionment estimates reveal varying degrees of sensitivity to changing priors, inclusion of covariance terms, incorporation of time-variant distributions, and methods of proportion characterization. We also demonstrate differences in apportionment results between a full and an empirical Bayesian setup, and between a Bayesian and a frequentist optimization approach. This OFAT sensitivity analysis reveals that mixing model structural choices and error assumptions can significantly impact upon sediment source apportionment results, with estimated median contributions in this study varying by up to 21% between model versions. Users of mixing models are therefore strongly advised to carefully consider and justify their choice of model structure prior to conducting sediment source apportionment investigations

    Characteristics Associated With Differences in Survival Among Black and White Women With Breast Cancer

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    Importance Difference in breast cancer survival by race is a recognized problem among Medicare beneficiaries. Objective To determine if racial disparity in breast cancer survival is primarily attributable to differences in presentation characteristics at diagnosis or subsequent treatment. Design, Setting, and Patients Comparison of 7375 black women 65 years and older diagnosed between 1991 to 2005 and 3 sets of 7375 matched white control patients selected from 99 898 white potential controls, using data for 16 US Surveillance, Epidemiology and End Results (SEER) sites in the SEER-Medicare database. All patients received follow-up through December 31, 2009, and the black case patients were matched to 3 white control populations on demographics (age, year of diagnosis, and SEER site), presentation (demographics variables plus patient comorbid conditions and tumor characteristics such as stage, size, grade, and estrogen receptor status), and treatment (presentation variables plus details of surgery, radiation therapy, and chemotherapy). Main Outcomes and Measures 5-Year survival. Results The absolute difference in 5-year survival (blacks, 55.9%; whites, 68.8%) was 12.9% (95% CI, 11.5%-14.5%; P \u3c .001) in the demographics match. This difference remained unchanged between 1991 and 2005. After matching on presentation characteristics, the absolute difference in 5-year survival was 4.4% (95% CI, 2.8%-5.8%; P \u3c .001) and was 3.6% (95% CI, 2.3%-4.9%; P \u3c .001) lower for blacks than for whites matched also on treatment. In the presentation match, fewer blacks received treatment (87.4% vs 91.8%; P \u3c .001), time from diagnosis to treatment was longer (29.2 vs 22.8 days; P \u3c .001), use of anthracyclines and taxols was lower (3.7% vs 5.0%; P \u3c .001), and breast-conserving surgery without other treatment was more frequent (8.2% vs 7.3%; P = .04). Nevertheless, differences in survival associated with treatment differences accounted for only 0.81% of the 12.9% survival difference. Conclusions and Relevance In the SEER-Medicare database, differences in breast cancer survival between black and white women did not substantially change among women diagnosed between 1991 and 2005. These differences in survival appear primarily related to presentation characteristics at diagnosis rather than treatment differences

    3-manifolds which are spacelike slices of flat spacetimes

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    We continue work initiated in a 1990 preprint of Mess giving a geometric parameterization of the moduli space of classical solutions to Einstein's equations in 2+1 dimensions with cosmological constant 0 or -1 (the case +1 has been worked out in the interim by the present author). In this paper we make a first step toward the 3+1-dimensional case by determining exactly which closed 3-manifolds M^3 arise as spacelike slices of flat spacetimes, and by finding all possible holonomy homomorphisms pi_1(M^3) to ISO(3,1).Comment: 10 page
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