223,764 research outputs found
Fluvial transport of suspended sediment and organic carbon during flood events in a large agricultural catchment in southwest France.
Water draining from a large agricultural catchment of 1 110 km2 in southwest France was sampled over an 18-month period to determine the temporal variability in suspended sediment (SS) and dissolved (DOC) and particulate organic carbon (POC) transport during flood events, with quantification of fluxes and controlling factors, and to analyze the relationships between discharge and SS, DOC and POC. A total of 15 flood events were analyzed, providing extensive data on SS, POC and DOC during floods. There was high variability in SS, POC and DOC transport during different seasonal floods, with SS varying by event from 513 to 41 750 t; POC from 12 to 748 t and DOC from 9 to 218 t. Overall, 76 and 62% of total fluxes of POC and DOC occurred within 22% of the study period. POC and DOC export from the Save catchment amounted to 3090 t and 1240 t, equivalent to 1·8 t km−2 y−1 and 0·7 t km−2 y−1, respectively. Statistical analyses showed that total precipitation, flood discharge and total water yield were the major factors controlling SS, POC and DOC transport from the catchment. The relationships between SS, POC and DOC and discharge over temporal flood events resulted in different hysteresis patterns, which were used to deduce dissolved and particulate origins. In both clockwise and anticlockwise hysteresis, POC mainly followed the same patterns as discharge and SS. The DOC-discharge relationship was mainly characterized by alternating clockwise and anticlockwise hysteresis due to dilution effects of water originating from different sources in the whole catchment
Awareness, interest, and preferences of primary care providers in using point-of-care cancer screening technology
Well-developed point-of-care (POC) cancer screening tools have the potential to provide better cancer care to patients in both developed and developing countries. However, new medical technology will not be adopted by medical providers unless it addresses a population’s existing needs and end-users’ preferences. The goals of our study were to assess primary care providers’ level of awareness, interest, and preferences in using POC cancer screening technology in their practice and to provide guidelines to biomedical engineers for future POC technology development. A total of 350 primary care providers completed a one-time self-administered online survey, which took approximately 10 minutes to complete. A $50 Amazon gift card was given as an honorarium for the first 100 respondents to encourage participation. The description of POC cancer screening technology was provided in the beginning of the survey to ensure all participants had a basic understanding of what constitutes POC technology. More than half of the participants (57%) stated that they heard of the term “POC technology” for the first time when they took the survey. However, almost all of the participants (97%) stated they were either “very interested” (68%) or “somewhat interested” (29%) in using POC cancer screening technology in their practice. Demographic characteristics such as the length of being in the practice of medicine, the percentage of patients on Medicaid, and the average number of patients per day were not shown to be associated with the level of interest in using POC. These data show that there is a great interest in POC cancer screening technology utilization among this population of primary care providers and vast room for future investigations to further understand the interest and preferences in using POC cancer technology in practice. Ensuring that the benefits of new technology outweigh the costs will maximize the likelihood it will be used by medical providers and patients
Factors influencing the stable carbon isotopic composition of suspended and sinking organic matter in the coastal Antarctic sea ice environment
A high resolution time-series analysis of stable carbon isotopic signatures in particulate organic carbon (&delta;<sup>13</sup>C<sub>POC</sub>) and associated biogeochemical parameters in sea ice and surface waters provides an insight into the factors affecting &delta;<sup>13</sup>C<sub>POC</sub> in the coastal western Antarctic Peninsula sea ice environment. The study covers two austral summer seasons in Ryder Bay, northern Marguerite Bay between 2004 and 2006. A shift in diatom species composition during the 2005/06 summer bloom to near-complete biomass dominance of <i>Proboscia inermis</i> is strongly correlated with a large ~10 &permil; negative isotopic shift in &delta;<sup>13</sup>C<sub>POC</sub> that cannot be explained by a concurrent change in concentration or isotopic signature of CO<sub>2</sub>. We hypothesise that the &delta;<sup>13</sup>C<sub>POC</sub> shift may be driven by the contrasting biochemical mechanisms and utilisation of carbon-concentrating mechanisms (CCMs) in different diatom species. Specifically, very low &delta;<sup>13</sup>C<sub>POC</sub> in <i>P. inermis</i> may be caused by the lack of a CCM, whilst some diatom species abundant at times of higher &delta;<sup>13</sup>C<sub>POC</sub> may employ CCMs. These short-lived yet pronounced negative &delta;<sup>13</sup>C<sub>POC</sub> excursions drive a 4 &permil; decrease in the seasonal average &delta;<sup>13</sup>C<sub>POC</sub> signal, which is transferred to sediment traps and core-top sediments and consequently has the potential for preservation in the sedimentary record. This 4 &permil; difference between seasons of contrasting sea ice conditions and upper water column stratification matches the full amplitude of glacial-interglacial Southern Ocean &delta;<sup>13</sup>C<sub>POC</sub> variability and, as such, we invoke phytoplankton species changes as a potentially important factor influencing sedimentary &delta;<sup>13</sup>C<sub>POC</sub>. We also find significantly higher &delta;<sup>13</sup>C<sub>POC</sub> in sea ice than surface waters, consistent with autotrophic carbon fixation in a semi-closed environment and possible contributions from post-production degradation, biological utilisation of HCO<sub>3</sub><sup>&minus;</sup> and production of exopolymeric substances. This study demonstrates the importance of surface water diatom speciation effects and isotopically heavy sea ice-derived material for &delta;<sup>13</sup>C<sub>POC</sub> in Antarctic coastal environments and underlying sediments, with consequences for the utility of diatom-based &delta;<sup>13</sup>C<sub>POC</sub> in the sedimentary record
Biases in the In Situ Measurement of Particulate Organic Carbon and Its Effect on the Calibration and Validation of Ocean Color Sensors
Particulate organic carbon (POC) plays an oversize role, relative to its standing stock in the global carbon (C) cycle. Accurate measurement of POC is central to understanding the ocean C flux and its sensitivity to climate forcing. POC is a standard NASA ocean color data product, which lacks a consensus, quality-assured measurement protocol for satellite validation. Thus, algorithms based on field measurements lacking verified uncertainties have limited applicability towards climate data records. Different sampling and filtration protocols, and blank corrections, introduce biases in the magnitude of POC measured from the field. A significant filter blank attributable to dissolved organic C (DOC) adsorption that, until recently has been seldom corrected for, likely has introduced biases in POC global datasets
Temporal variation in riverine organic carbon concentrations and fluxes in two contrasting estuary systems: Geum and Seomjin, South Korea
In this study, surface water samples were collected at sites located in the lowest reaches of closed (Geum) (i.e. with an estuary dam at the river mouth) and open (Seomjin) estuary systems between May 2016 and May 2018. We analyzed concentrations and stable isotopes of particulate organic carbon (POC) and dissolved organic carbon (DOC) to assess OC sources, to estimate fluxes of riverine OC, and to assess some of the factors driving OC exports in these two contrasting Korean estuary systems. Our geochemical results suggest that the contribution of the phytoplankton-derived POC to the total POC pool was larger in the Geum River than in the Seomjin River. Notably, a heavy riverine algae bloom occurred in the Geum River in August 2016, resulting in a high carbon isotopic composition (-19.4%) together with low POC/PN ratio (˂ 10) and POC/Chl-a ratio (˂ 100). In contrast, potential DOC sources in both the Geum River and the Seomjin River were a mixture of C3-derived forest soils and cropland organic matter. During the study period, the catchment area-normalized fluxes of POC and DOC were 0.40x10(-3) tC/km(2)/yr and 6.5x10(-2) tC/km(2)/yr in the Geum River and 5.2x10(-4) tC/km(2)/yr and 8.6x10(-4) tC/km(2)/yr in the Seomjin River, respectively. It appears that the POC flux was more weakly associated with the water discharge in the Geum River than in the Seomjin River, but the DOC fluxes were in general controlled by the water discharges in both rivers. Accordingly, the estuary dam of the Geum River might be one of the most strongly influencing factors on seasonal patterns in POC fluxes into the adjacent coastal seas, strongly modifying water residence times and thus biogeochemical processes.We would like to thank Dokyun Kim, Ji Hwan Hwang, Jong-Ku Gal, Dong-Hun Lee, Dahae Kim, and Solbin Kim for their assistance during fieldwork. This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Ministry of Science and ICT (MSIT) -South Korea [NRF-2016R1A2B3015388, KOPRI-PN19100]
Physics of the atmosphere: Response of the water vapor channel of the Meteosat satellite
An accurate model of the atmospheric transmission function is used to obtain the relationship between the cloudless radiances measured by the 6-7 microns Meteosat radiometer (water vapor channel) and the numerical parameters associated to each point of an image. This relationship is compared to the temporary calibration curve published by the European Space Agency
Territorial innovation dynamics and integration of SMEs into the collaborative innovation projects of French competitiveness poles: the underlying mechanisms
Geographical clusters are nowadays considered as a relevant factor for competitiveness, thanks to their innovative capabilities. In this context, public policies based on this approach are flourishing all over the world. The French “Pole of competitiveness” (PoC) policy (Politique des pôles de compétitivité) is one of these initiatives. It is the new French industrial policy aiming at reinforcing the specializations of the economy and the attractiveness of territories by fostering the development of R&D projects, bringing together multinationals, universities, and particularly Small-Middle-Sized-Enterprises (SMEs). Precisely, significant research suggests that in order to innovate SMEs need to cooperate and they are also vital for the functioning, and survival of innovative milieux. Consequently, their integration is a key issue for French PoC' success. However, the call for projects shows that despite their efforts, French Poles of Competitiveness are not totally successful: a gap remains especially between the massive financial investments helping SMEs innovate and the expected results. Yet, this issue is only analysed by focusing on intrinsic weaknesses of SMEs' management or on the complexities of existing support programmes supporting SMEs' innovation. This is insufficient. Innovation dynamics are different from a cluster to another and many failures of innovation policies come from the lack of identification of these specificities. Therefore, this paper aims are threefold: it aims at introducing the French PoC, indeed, the French PoC policy is the main new policy gathering all the nation's innovation programmes. But few papers are explaining how they work. It aims at identifying the territorial innovation dynamics within PoC and how they work, and then combine this analysis with the intrinsic features of SMEs management, to better understand how they get involved in these dynamics. It finally aims at presenting the preliminary results of the first stage of research: the analysis of a specific French PoC, the “Secured Communicating Solutions”(SCS) PoC as well as the further research questions they raise for the next stage of research.clusters, interaction, knowledge management, SMEs
Prospective observational study of point-of-care creatinine in trauma.
Background:Patients with trauma are at risk for renal dysfunction from hypovolemia or urological injury. In austere environments, creatinine values are not available to guide resuscitation. A new portable device, the Stat Sensor Point-of-care (POC) Whole Blood Creatinine Analyzer, provides accurate results in <30 s and requires minimal training. This device has not been evaluated in trauma despite the theoretical benefit it provides. The purpose of this study is to determine the clinical impact of the POC device in trauma. Methods:40 patients with trauma were enrolled in a prospective observational study. One drop of blood was used for creatinine determination on the Statsensor POC device. POC creatinine results were compared to the laboratory. Turnaround time (TAT) for POC and laboratory methods was calculated as well as time elapsed to CT scan if applicable. Results:Patients (n=40) were enrolled between December 2014 and March 2015. POC creatinine values were similar to laboratory methods with a mean bias of 0.075±0.27 (p=0.08). Mean analytical TATs for the POC measurements were significantly faster than the laboratory method (11.6±10.0 min vs 78.1±27.9 min, n=40, p<0.0001). Mean elapsed time before arrival at the CT scanner was 52.9±34.2 min. Conclusions:The POC device reported similar creatinine values to the laboratory and provided significantly faster results. POC creatinine testing is a promising development for trauma practice in austere environments and workup of a subset of stable patients with trauma. Further study is warranted to determine clinical impact, both in hospital-based trauma and austere environments
Point-of-care C reactive protein for the diagnosis of lower respiratory tract infection in NHS primary care: a qualitative study of barriers and facilitators to adoption
OBJECTIVES: Point-of-care (POC) C reactive protein (CRP) is incorporated in National Institute of Health and Care Excellence (NICE) guidelines for the diagnosis of pneumonia, reduces antibiotic prescribing and is cost effective. AIM: To determine the barriers and facilitators to adoption of POC CRP testing in National Health Service (NHS) primary care for the diagnosis of lower respiratory tract infection. DESIGN: The study followed a qualitative methodology based on grounded theory. The study was undertaken in 2 stages. Stage 1 consisted of semistructured interviews with 8 clinicians from Europe and the UK who use the test in routine practice, and focused on their subjective experience in the challenges of implementing POC CRP testing. Stage 2 was a multidisciplinary-facilitated workshop with NHS stakeholders to discuss barriers to adoption, impact of adoption and potential adoption scenarios. Emergent theme analysis was undertaken. PARTICIPANTS: Participants included general practitioners (including those with commissioning experience), biochemists, pharmacists, clinical laboratory scientists and industry representatives from the UK and abroad. RESULTS: Barriers to the implementation of POC CRP exist, but successful adoption has been demonstrated abroad. Analysis highlighted 7 themes: reimbursement and incentivisation, quality control and training, laboratory services, practitioner attitudes and experiences, effects on clinic flow and workload, use in pharmacy and gaps in evidence. CONCLUSIONS: Successful adoption models from the UK and abroad demonstrate a distinctive pattern and involve collaboration with central laboratory services. Incorporating antimicrobial stewardship into quality improvement frameworks may incentivise adoption. Further research is needed to develop scaling-up strategies to address the resourcing, clinical governance and economic impact of widespread NHS implementation
Transport of video over partial order connections
A Partial Order and partial reliable Connection (POC) is an end-to-end transport connection authorized to deliver objects in an order that can differ from the transmitted one. Such a connection is also authorized to lose some objects. The POC concept is motivated by the fact that heterogeneous best-effort networks such as Internet are plagued by unordered delivery of packets and losses, which tax the performances of current applications and protocols. It has been shown, in several research works, that out of order delivery is able to alleviate (with respect to CO service) the use of end systems’ communication resources. In this paper, the efficiency of out-of-sequence delivery on MPEG video streams processing is studied. Firstly, the transport constraints (in terms of order and reliability) that can be relaxed by MPEG video decoders, for improving video transport, are detailed. Then, we analyze the performance gain induced by this approach in terms of blocking times and recovered errors. We demonstrate that POC connections fill not only the conceptual gap between TCP and UDP but also provide real performance improvements for the transport of multimedia streams such MPEG video
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