584 research outputs found
Interest of site-specific pollution control policies
Owing to increasing environmental concerns the current trend is to bend technical production systems in order to adapt them to the specific characteristics of the milieu and diversify them. Inherent to such dynamics is the issue of how to design the accompanying environmental policies. Theoretically, spatially targeted environmental policies are considered optimal, since economic agents tune their efforts according to the sensitivity of the milieu where they operate. But, according to empirical analyses, this advantage is undermined by the high cost of implementation, monitoring and enforcement. This paper outlines the conditions required for site-specific policies to be effective at least cost. Our starting point is the nitrate pollution of water from agriculture, which varies according to climate, soil type and agricultural production system. Farm management practices enabling to reduce pollution depend on this variability. An interdisciplinary study of the efficiency of differentiating the way this pollution is regulated was carried out on two sites in France. It focussed on assessing the importance of spatial variability in physical parameters and in private and social costs.NONPOINT POLLUTION; SITE SPECIFIC TECHNOLOGY; SITE SPECIFIC ENVIRONMENTAL POLICY; ABATEMENT COST; TRANSACTION COST
Specific involvement of gonadal hormones in the functional maturation of growth hormone releasing hormone (GHRH) neurons
Growth hormone (GH) is the key hormone involved in the regulation of growth and metabolism, two functions that are highly modulated during infancy. GH secretion, controlled mainly by GH releasing hormone (GHRH), has a characteristic pattern during postnatal development that results in peaks of blood concentration at birth and puberty. A detailed knowledge of the electrophysiology of the GHRH neurons is necessary to understand the mechanisms regulating postnatal GH secretion. Here, we describe the unique postnatal development of the electrophysiological properties of GHRH neurons and their regulation by gonadal hormones. Using GHRH-eGFP mice, we demonstrate that already at birth, GHRH neurons receive numerous synaptic inputs and fire large and fast action potentials (APs), consistent with effective GH secretion. Concomitant with the GH secretion peak occurring at puberty, these neurons display modifications of synaptic input properties, decrease in AP duration, and increase in a transient voltage-dependant potassium current. Furthermore, the modulation of both the AP duration and voltage-dependent potassium current are specifically controlled by gonadal hormones because gonadectomy prevented the maturation of these active properties and hormonal treatment restored it. Thus, GHRH neurons undergo specific developmental modulations of their electrical properties over the first six postnatal weeks, in accordance with hormonal demand. Our results highlight the importance of the interaction between the somatotrope and gonadotrope axes during the establishment of adapted neuroendocrine functions
A Resident Perspective on Adding Value as Radiologists
During the annual 46th annual American Alliance of Academic Chief Residents in Radiology (A3CR2) meeting in New Orleans, chief residents discussed the role of residents within American College of Radiology 3.0 campaign. Our discussion was directed toward the evolving role of fourth-year radiology residents and how we might improve their training to better prepare them to add value as both leaders and radiologists. The ideas resulting from our Problem Solving session were divided into three categories: clinical presence in the wards and subspecialty clinics; visibility to clinicians and patients; and the education of medical students, residents, and advanced practice clinicians to aid in realizing the long-term goals of Imaging 3.0
Myosin5a tail associates directly with Rab3A-containing compartments in neurons
Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of American Society for Biochemistry and Molecular Biology. The definitive version was published in Journal of Biological Chemistry, 286 (2011): 14352-14361, doi:10.1074/jbc.M110.187286.Myosin-Va (Myo5a) is a motor protein
associated with synaptic vesicles (SVs) but the
mechanism by which it interacts has not yet
been identified. A potential class of binding
partners are Rab GTPases and Rab3A is known
to associate with SVs and is involved in SV
trafficking. We performed experiments to
determine whether Rab3A interacts with
Myo5a and whether it is required for transport
of neuronal vesicles. In vitro motility assays
performed with axoplasm from the squid giant
axon showed a requirement for a Rab GTPase
in Myo5a-dependent vesicle transport.
Furthermore, mouse recombinant Myo5a tail
revealed that it associated with Rab3A in rat
brain synaptosomal preparations in vitro and
the association was confirmed by
immunofluorescence imaging of primary
neurons isolated from the frontal cortex of
mouse brains. Synaptosomal Rab3A was
retained on recombinant GST-tagged Myo5a
tail affinity columns in a GTP-dependent
manner. Finally, the direct interaction of
Myo5a and Rab3A was determined by
sedimentation v e l o c i t y analytical
ultracentrifugation using recombinant mouse
Myo5a tail and human Rab3A. When both
proteins were incubated in the presence of 1
mM GTPγS, Myo5a tail and Rab3A formed a
complex and a direct interaction was observed.
Further analysis revealed that GTP-bound
Rab3A interacts with both the monomeric and
dimeric species of the Myo5a tail. However, the
interaction between Myo5a tail and nucleotidefree
Rab3A did not occur. Thus, our results
show that Myo5a and Rab3A are direct binding
partners and interact on SVs and that the
Myo5a/Rab3A complex is involved in transport
of neuronal vesicles
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Cool Roofs: High Tech Low Cost solution for energy efficiency and thermal comfort in low rise low income houses in high solar radiation countries
Cool roofs are most effective in reducing cooling loads and alleviating overheating in locations with high solar radiation and external air temperature. This paper presents results of an experimental study of a low income house in Jamaica and a computational study in three countries around the equator: Jamaica, Northeast Brazil (Recife) and Ghana. A case-study typical of single storey houses in Jamaica was monitored before and after the installation of a cool paint on the roof; on days with average solar radiation intensity of ∼420 W/m2 and ambient air temperature of ∼28 °C, internal ceiling surface temperature is reduced by an average of 6.8 °C and internal air temperature by 2.3 °C. Monitoring results were used to calibrate successfully an EnergyPlus model; similar models were developed for Ghana and Brazil differing in size and/or construction to reflect country specific practices. Annual simulations indicate that internal ceiling surface temperatures are reduced on average by 3.2–5.5 oC and internal air temperatures by 0.75–1.2 °C. Cooling demand simulations (setpoint 24 °C) indicate similar annual potential savings in the three locations (∼190 kWh/m2/year) although estimated CO2 emissions reduction differ reflecting electricity generation fuels. Aging of the cool roof has an impact reducing load savings by 22–26 kWh/m2/year.This work was carried out as part of EPSRC Global Challenges Research Fund Institutional Sponsorship Award 2016 - Brunel Uni- versity ( EP/P510749/1 )
Outcome of Ph negative myeloproliferative neoplasms transforming to accelerated or leukemic phase
Myeloproliferative neoplasms (MPN) are chronic disorders that can sometimes evolve into accelerated or leukemic phases. We retrospectively identified 122 patients with such blastic phases. The overall median survival was four months: 10.2 months for patients treated with intensive treatments compared to three months for best supportive care (p = .005). Azacytidine, intensive chemotherapies, or allogeneic stem cell transplantation gave the highest median survivals with 9, 10.2, and 19.4 months, respectively. Accelerated phases (AP) had a longer median survival compared to acute leukemia (4.8 months vs. 3.1 months; p = .02). In this retrospective and observational study, we observe that the longest survivals are seen in patients eligible for intensive treatments. Azacytidine shows interesting results in patients non-fit for intensive chemotherapy. Supportive care should probably be restricted to elderly patients and those with unfavorable karyotype. An early diagnosis of AP could also result in a better survival rate
Characterizations and first plasma operation of the WEST load-resilient actively cooled ICRF launchers
The paper discusses the characterization of the three high power steady-state and load-resilient ICRF launchers of WEST before their installation in the tokamak. These launchers have been characterized and validated in low-power experiments (milliwatt range) as well as in experiments at the nominal RF voltages and currents in the TITAN vacuum chamber (~30 kV and 915 A peak). The successful commissioning of two of the launchers during the WEST C3 campaign at ~1 MW power level is illustrated. Manual and real-time controlled impedance-matching of the launchers are discussed, as well as the validation of their load-resilience. Furthermore, several redundant and complementary protection systems have been validated and are reviewed in the paper
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Ensembles of global climate model variants designed for the quantification and constraint of uncertainty in aerosols and their radiative forcing
Tropospheric aerosol radiative forcing has persisted for many years as one of the major causes of uncertainty in global climate model simulations. To sample the range of plausible aerosol and atmospheric states and perform robust statistical analyses of the radiative forcing, it is important to account for the combined effects of many sources of model uncertainty, which is rarely done due to the high computational cost. This paper describes the designs of two ensembles of the HadGEM-UKCA global climate model and provides the first analyses of the uncertainties in aerosol radiative forcing and their causes. The first ensemble was designed to comprehensively sample uncertainty in the aerosol state, while the other samples additional uncertainties in the physical model related to clouds, humidity and radiation, thereby allowing an analysis of uncertainty in the aerosol effective radiative forcing. Each ensemble consists of around 200 simulations of the pre-industrial and present-day atmospheres. The uncertainty in aerosol radiative forcing in our ensembles is comparable to the range of estimates from multi-model intercomparison projects. The mean aerosol effective radiative forcing is –1.45 W m–2 (credible interval –2.07 to –0.81 W m–2), which encompasses but is more negative than the –1.17 W m–2 in
the 2013 Atmospheric Chemistry and Climate Model Intercomparison Project and –0.90 W m–2 in the IPCC 5th Assessment Report. The ensembles can be used to reduce aerosol radiative forcing uncertainty by challenging them with multiple measurements as well as to isolate potential causes of multi-model differences
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