3,372 research outputs found

    Fast and broadband fiber dispersion measurement with dense wavelength sampling

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    We report on a method to obtain dispersion measurements from spectral-domain low-coherence interferograms which enables high accuracy (~ps/(nm¡km)), broadband measurements and the determination of very dense (up to 20 points/nm over 500 nm) data sets for both dispersion and dispersion slope. The method exploits a novel phase extraction algorithm which allows the phase associated with each sampling point of the interferogram to be calculated and provides for very accurate results as well as a fast measurement capability, enabling close to real time measurements. The important issue of mitigating the measurement errors due to any residual dispersion of optical elements and to environmental fluctuations was also addressed. We performed systematic measurements on standard fibers which illustrate the accuracy and precision of the technique, and we demonstrated its general applicability to challenging problems by measuring a carefully selected set of microstructured fibers: a lead silicate W-type fiber with a flat, near-zero dispersion profile; a hollow core photonic bandgap fiber with strongly wavelength dependent dispersion and dispersion slope; a small core, highly birefringent index guiding microstructured fiber, for which polarization resolved measurements over an exceptionally wide (~1000 nm) wavelength interval were obtained

    Consumer understanding of nutrition and health claims: sources of evidence

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    Provided that they are scientifically substantiated, nutrition and health (NH) claims linked to food products can help consumers make well-informed food choices. The new European legislation on NH claims made on foods entered into force on 19 January 2007. The law sets out conditions for their use, establishes a system for their scientific evaluation, and will create European lists of authorised claims. An important aspect of this proposed legislation is that it states, in article 5.2, ‘the use of nutrition and health claims shall only be permitted if the average consumer can be expected to understand the beneficial effects expressed in the claim'. The present review examines consumer understanding of NH claims from a consumer science perspective. It focuses on the type of data and information that could be needed to provide evidence that the average consumer adequately understands a particular NH claim. After exploring several different methodologies, it proposes a case-specific approach using a stepwise procedure for assessing consumer understanding of a NH clai

    A cohort study of the recovery of health and wellbeing following colorectal cancer (CREW study): protocol paper

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    Background: the number of people surviving colorectal cancer has doubled in recent years. While much of the literature suggests that most people return to near pre-diagnosis status following surgery for colorectal cancer, this literature has largely focused on physical side effects. Longitudinal studies in colorectal cancer have either been small scale or taken a narrow focus on recovery after surgery. There is a need for a comprehensive, long-term study exploring all aspects of health and wellbeing in colorectal cancer patients. The aim of this study is to establish the natural history of health and wellbeing in people who have been treated for colorectal cancer. People have different dispositions, supports and resources, likely resulting in individual differences in restoration of health and wellbeing. The protocol described in this paper is of a study which will identify who is most at risk of problems, assess how quickly people return to a state of subjective health and wellbeing, and will measure factors which influence the course of recovery. Methods: this is a prospective, longitudinal cohort study following 1000 people with colorectal cancer over a period of two years, recruiting from 30 NHS cancer treatment centres across the UK. Questionnaires will be administered prior to surgery, and 3, 9, 15 and 24 months after surgery, with the potential to return to this cohort to explore on-going issues related to recovery after cancer. Discussion: outcomes will help inform health care providers about what helps or hinders rapid and effective recovery from cancer, and identify areas for intervention development to aid this process. Once established the cohort can be followed up for longer periods and be approached to participate in related projects as appropriate and subject to funding<br/

    Quark-Antiquark Potential and Generalized Borel Transform

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    The heavy quark potential and particularly the one proposed by Richardson to incorporate both asymptotic freedom and linear confinement is analyzed in terms of a generalized Borel Transform recently proposed. We were able to obtain, in the range of physical interest, an approximate analytical expression for the potential in coordinate space valid even for intermediate distances. The deviation between our approximate potential and the numerical evaluation of the Richardson's one is much smaller than Λ\Lambda of QCD. The cc‾c\overline{c} and bb‾b\overline{b} quarkonia energy levels agree reasonably well with experimental data for cc and bb masses in good agreement with the values obtained from experiments.Comment: 9 pages, 3 Tabl

    Ultraviolet writing of channel waveguides in proton-exchanged LiNbO<sub>3</sub>

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    We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 Âľm in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented

    Representative Farms Economic Outlook for the August 2007 FAPRI/AFPC Baseline

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    The farm level economic impacts of the Farm Security and Rural Investment Act of 2002 (2002 Farm Bill) on representative crop, dairy, and livestock operations are projected in this report. The analysis was conducted over the 2007-2012 planning horizon using FLIPSIM, AFPC’s whole farm simulation model. Data to simulate agricultural operations in the nation’s major production regions came from two sources: 1) Producer panel cooperation to develop economic information to describe and simulate representative crop, livestock, and dairy farms. 2) Projected prices, policy variables, and input inflation rates from the Food and Agricultural Policy Research Institute (FAPRI) August 2007 Baseline. The FLIPSIM policy simulation model incorporates the historical risk faced by agricultural producers for prices and production. This report presents the results of the August 2007 Baseline in a risk context using selected simulated probabilities and ranges for annual net cash farm income values. The probability of a farm experiencing a negative ending cash balance and the probability of a farm losing real net worth are included as indicators of the cash flow and equity risks facing producers through the year 2012. This report is organized into ten sections. The first section summarizes the process used to develop the representative farms and the key assumptions utilized for the farm level analysis. The second section summarizes the FAPRI August 2007 Baseline and the policy and price assumptions used for the representative farm analyses. The third through sixth sections present the results of the simulation analyses for feed grain, wheat, cotton, and rice farms. The seventh and eighth sections summarize simulation results for dairy and cattle. Two appendices constitute the final sections of the report. Appendix A provides tables to summarize the physical and financial characteristics for each of the representative farms. Appendix B provides the names of producers, land grant faculty, and industry leaders who cooperated in the panel interview process to develop the representative farms.Agribusiness, Agricultural and Food Policy, Crop Production/Industries,

    Representative Farms Economic Outlook for the January 2007 FAPRI/AFPC Baseline

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    Under the January 2007 Baseline, 20 of the 64 crop farms are considered in good liquidity condition (less than a 25 percent chance of negative ending cash in 2012). Five crop farms have between a 25 percent and a 50 percent likelihood of negative ending cash. The remaining 39 crop farms have greater than a 50 percent chance of negative ending cash. Additionally, 30 of the 64 crop farms are considered in good equity position (less than a 25 percent chance of decreasing real net worth during the study period). Nine crop farms have between a 25 percent and 50 percent likelihood of losing real net worth, and 25 crop farms have greater than a 50 percent probability of decreasing real net worth. The following discussion provides an overall evaluation by commodity considering both liquidity and equity measures.Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Livestock Production/Industries,

    Discordant Immune Response with Antiretroviral Therapy in HIV-1: A Systematic Review of Clinical Outcomes.

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    BACKGROUND A discordant immune response (DIR) is a failure to satisfactorily increase CD4 counts on ART despite successful virological control. Literature on the clinical effects of DIR has not been systematically evaluated. We aimed to summarise the risk of mortality, AIDS and serious non-AIDS events associated with DIR with a systematic review. METHODS The protocol is registered with the Centre for Review Dissemination, University of York (registration number CRD42014010821). Included studies investigated the effect of DIR on mortality, AIDS, or serious non-AIDS events in cohort studies or cohorts contained in arms of randomised controlled trials for adults aged 16 years or older. DIR was classified as a suboptimal CD4 count (as defined by the study) despite virological suppression following at least 6 months of ART. We systematically searched PubMed, Embase, and the Cochrane Library to December 2015. Risk of bias was assessed using the Cochrane tool for assessing risk of bias in cohort studies. Two authors applied inclusion criteria and one author extracted data. Risk ratios were calculated for each clinical outcome reported. RESULTS Of 20 studies that met the inclusion criteria, 14 different definitions of DIR were used. Risk ratios for mortality in patients with and without DIR ranged between 1.00 (95% CI 0.26 to 3.92) and 4.29 (95% CI 1.96 to 9.38) with the majority of studies reporting a 2 to 3 fold increase in risk. CONCLUSIONS DIR is associated with a marked increase in mortality in most studies but definitions vary widely. We propose a standardised definition to aid the development of management options for DIR

    Representative Farms Economic Outlook for the January 2006 FAPRI/AFPC Baseline

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    The farm level economic impacts of the Farm Security and Rural Investment Act of 2002 (2002 Farm Bill) on representative crop and livestock operations are projected in this report. The analysis was conducted over the 2006-2010 planning horizon using FLIPSIM, AFPC’s whole farm simulation model. Data to simulate farming and ranching operations in the nation’s major production regions came from two sources: - Producer panel cooperation to develop economic information to describe and simulate representative crop, livestock, and dairy farms. - Projected prices, policy variables, and input inflation rates from the Food and Agricultural Policy Research Institute (FAPRI) January 2006 Baseline. The primary objective of the analysis is to determine the farms’ economic viability by region and commodity through the life of the 2002 Farm Bill. The FLIPSIM policy simulation model incorporates the historical risk faced by farmers and ranchers for prices and production. This report presents the results of the January 2006 Baseline in a risk context using selected simulated probabilities and ranges for annual net cash farm income values. The probability of a farm experiencing a negative ending cash balance and the probability of a farm losing real net worth are included as indicators of the cash flow and equity risks facing farms through the year 2010. This report is organized into ten sections. The first section summarizes the process used to develop the representative farms and the key assumptions utilized for the farm level analysis. The second section summarizes the FAPRI January 2006 Baseline and the policy and price assumptions used for the representative farm analyses. The third through sixth sections present the results of the simulation analyses for feed grain, wheat, cotton, and rice farms. The seventh and eighth sections summarize simulation results for dairy and cattle. Two appendices constitute the final section of the report. Appendix A provides tables to summarize the physical and financial characteristics for each of the representative farms. Appendix B provides the names of producers, land grant faculty, and industry leaders who cooperated in the panel interview process to develop the representative farms.Agribusiness, Agricultural and Food Policy, Crop Production/Industries, Livestock Production/Industries,
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