994 research outputs found

    Future Prospects: Deep Imaging of Galaxy Outskirts using Telescopes Large and Small

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    The Universe is almost totally unexplored at low surface brightness levels. In spite of great progress in the construction of large telescopes and improvements in the sensitivity of detectors, the limiting surface brightness of imaging observations has remained static for about forty years. Recent technical advances have at last begun to erode the barriers preventing progress. In this Chapter we describe the technical challenges to low surface brightness imaging, describe some solutions, and highlight some relevant observations that have been undertaken recently with both large and small telescopes. Our main focus will be on discoveries made with the Dragonfly Telephoto Array (Dragonfly), which is a new telescope concept designed to probe the Universe down to hitherto unprecedented low surface brightness levels. We conclude by arguing that these discoveries are probably only scratching the surface of interesting phenomena that are observable when the Universe is explored at low surface brightness levels.Comment: 27 pages, 10 figures, Invited review, Book chapter in "Outskirts of Galaxies", Eds. J. H. Knapen, J. C. Lee and A. Gil de Paz, Astrophysics and Space Science Library, Springer, in pres

    Centipede venoms as a source of drug leads

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    peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=iedc20© 2016 Taylor and Francis. The attached document is the authors' final submitted version of the journal article. You are advised to consult the publisher's version if you wish to cite from it

    Bi-local baryon interpolating fields with two flavours

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    We construct bi-local interpolating field operators for baryons consisting of three quarks with two flavors, assuming good isospin symmetry. We use the restrictions following from the Pauli principle to derive relations/identities among the baryon operators with identical quantum numbers. Such relations that follow from the combined spatial, Dirac, color, and isospin Fierz transformations may be called the (total/complete) Fierz identities. These relations reduce the number of independent baryon operators with any given spin and isospin. We also study the Abelian and non-Abelian chiral transformation properties of these fields and place them into baryon chiral multiplets. Thus we derive the independent baryon interpolating fields with given values of spin (Lorentz group representation), chiral symmetry (UL(2)Ă—UR(2)U_L(2) \times U_R(2) group representation) and isospin appropriate for the first angular excited states of the nucleon.Comment: 15 pages, 4 tables, accepted by EPJ

    Sedimentation record in the Konkan-Kerala Basin: implications for the evolution of the Western Ghats and the Western Indian passive margin

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    The Konkan and Kerala Basins constitute a major depocentre for sediment from the onshore hinterland of Western India and as such provide a valuable record of the timing and magnitude of Cenozoic denudation along the continental margin. This paper presents an analysis of sedimentation in the Konkan-Kerala Basin, coupledwith a mass balance study, and numerical modelling of flexural responses to onshore denudational unloading and o¡shore sediment loading in order to test competing conceptual models for the development of high-elevation passive margins. The Konkan-Kerala Basin contains an estimated 109,000 km<sup>3</sup>; of Cenozoic clastic sediment, a volume difficult to reconcile with the denudation of a downwarped rift flank onshore, and more consistent with denudation of an elevated rift flank. We infer from modelling of the isostatic response of the lithosphere to sediment loading offshore and denudation onshore that flexure is an important component in the development of the Western Indian Margin.There is evidence for two major pulses in sedimentation: an early phase in the Palaeocene, and a second beginning in the Pliocene. The Palaeocene increase in sedimentation can be interpreted in terms of a denudational response to the rifting between India and the Seychelles, whereas the mechanism responsible for the Pliocene pulse is more enigmatic

    Managing crop nutrients to achieve water quality goals

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    Landscapes and watersheds are inherently leaky and some nutrient loss can be expected with productive agricultural systems. Minimizing these losses, without undermining system sustainability is challenging and should involve an open and constructive discussion among all stakeholders as to what nutrient loss is desired, achievable, and how differences between these two endpoints can be reconciled. This is complicated by short- and long-term variations in weather/climate are a major factor influencing nutrient loss from agricultural lands. Nitrogen (N) loss tends to be spatially extensive, with management of the rate and timing of application, along with cropping systems as being important determining factors. Phosphorus (P) loss, on the other hand tends to be a function of critical sources areas, where coincident source (e.g., soil P and rate, timing, method and type of P applied) and transport factors (e.g., runoff and erosion) define losses. Despite this, legacy N and P from prior land management can mask the benefits of current and future conservation practices (CPs) to reduce losses from agricultural systems. Here, the appropriate use of calibrated and validated nonpoint source watershed models to estimate relative contributions of nutrient sources and outcomes of CP implementation can inform future strategies. However, they must be used in conjunction with and cannot replace water quality monitoring programs. Great strides have been made in nutrient use efficiency via nutrient management, crop selection, and CP adoption, which have reduced the risk of nutrient loss to surface and ground waters. Even so, additional research is needed on the areas of nutrient management on drained lands, fluvial legacies, and socio-economic factors influencing the success of conservation strategies

    Electronic patient-reported outcomes monitoring during lung cancer chemotherapy: A nested cohort within the PRO-TECT pragmatic trial (AFT-39)

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    Objectives: Patients with lung cancer have high symptom burden and diminished quality of life. Electronic patient-reported outcome (PRO) platforms deliver repeated longitudinal surveys via web or telephone to patients and alert clinicians about concerning symptoms. This study aims to determine feasibility of electronic PRO monitoring in lung cancer patients receiving treatment in community settings. Methods: Adults receiving treatment for advanced or metastatic lung cancer at 26 community sites were invited to participate in a prospective trial of weekly electronic PRO symptom monitoring for 12 months (NCT03249090). Surveys assessing patients’ satisfaction with the electronic PRO system were administered at 3 months. Descriptive statistics were generated for demographics, survey completion rates, symptom occurrence, and provider PRO alert management approaches. Pairwise relationships between symptom items were evaluated using intra-individual repeated-measures correlation coefficients. Results: Lung cancer patients (n = 118) participating in electronic PROs were older (mean 64.4 vs 61.9 years, p = 0.03), had worse performance status (p = 0.002), more comorbidities (p = 0.02), and less technology experience than patients with other cancers. Of delivered weekly PRO surveys over 12 months, 91% were completed. Nearly all (97%) patients reported concerning (i.e., severe or worsening) symptoms during participation, with 33% of surveys including concerning symptoms. Pain was the most frequent and longest lasting symptom and was associated with reduced activity level. More than half of alerts to clinicians for concerning symptoms led to intervention. The majority (87%) would recommend using electronic PRO monitoring to other lung cancer patients. Conclusions: Remote longitudinal weekly monitoring of patients with lung cancer using validated electronic PRO surveys was feasible in a multicenter, community-based pragmatic study. A high symptom burden specific to lung cancer was detected and clinician outreach in response to alerts was frequent, suggesting electronic PROs may be a beneficial strategy for identifying actionable symptoms and allow opportunities to optimize well-being in this population

    Reproductive health operations research, 1995–1998

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    This book presents in-depth reports on promising new interventions that have been developed and important programmatic changes that have been achieved by operations research in Latin America between 1995 and 1998. The INOPAL III project has made advances in five areas including access and quality of services, integration of family planning and other reproductive health services, financial sustainability, post-abortion care, and emergency contraception. Each of these topics are represented by at least three studies conducted in two or more countries. The operations research projects discussed under each topic are not replications of a single study. They use different research designs and address different questions. Nevertheless, when taken together, they provide managers and decision-makers with a body of programmatically relevant information on each broad topic covered

    Superconductivity in the two dimensional Hubbard Model.

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    Quasiparticle bands of the two-dimensional Hubbard model are calculated using the Roth two-pole approximation to the one particle Green's function. Excellent agreement is obtained with recent Monte Carlo calculations, including an anomalous volume of the Fermi surface near half-filling, which can possibly be explained in terms of a breakdown of Fermi liquid theory. The calculated bands are very flat around the (pi,0) points of the Brillouin zone in agreement with photoemission measurements of cuprate superconductors. With doping there is a shift in spectral weight from the upper band to the lower band. The Roth method is extended to deal with superconductivity within a four-pole approximation allowing electron-hole mixing. It is shown that triplet p-wave pairing never occurs. Singlet d_{x^2-y^2}-wave pairing is strongly favoured and optimal doping occurs when the van Hove singularity, corresponding to the flat band part, lies at the Fermi level. Nearest neighbour antiferromagnetic correlations play an important role in flattening the bands near the Fermi level and in favouring superconductivity. However the mechanism for superconductivity is a local one, in contrast to spin fluctuation exchange models. For reasonable values of the hopping parameter the transition temperature T_c is in the range 10-100K. The optimum doping delta_c lies between 0.14 and 0.25, depending on the ratio U/t. The gap equation has a BCS-like form and (2*Delta_{max})/(kT_c) ~ 4.Comment: REVTeX, 35 pages, including 19 PostScript figures numbered 1a to 11. Uses epsf.sty (included). Everything in uuencoded gz-compressed .tar file, (self-unpacking, see header). Submitted to Phys. Rev. B (24-2-95

    Strong-correlation effects in Born effective charges

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    Large values of Born effective charges are generally considered as reliable indicators of the genuine tendency of an insulator towards ferroelectric instability. However, these quantities can be very much influenced by strong electron correlation and metallic behavior, which are not exclusive properties of ferroelectric materials. In this paper we compare the Born effective charges of some prototypical ferroelectrics with those of magnetic, non-ferroelectric compounds using a novel, self-interaction free methodology that improves on the local-density approximation description of the electronic properties. We show that the inclusion of strong-correlation effects systermatically reduces the size of the Born effective charges and the electron localization lengths. Furthermore we give an interpretation of the Born effective charges in terms of band energy structure and orbital occupations which can be used as a guideline to rationalize their values in the general case.Comment: 10 pages, 4 postscript figure

    Particle Physics Approach to Dark Matter

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    We review the main proposals of particle physics for the composition of the cold dark matter in the universe. Strong axion contribution to cold dark matter is not favored if the Peccei-Quinn field emerges with non-zero value at the end of inflation and the inflationary scale is superheavy since, under these circumstances, it leads to unacceptably large isocurvature perturbations. The lightest neutralino is the most popular candidate constituent of cold dark matter. Its relic abundance in the constrained minimal supersymmetric standard model can be reduced to acceptable values by pole annihilation of neutralinos or neutralino-stau coannihilation. Axinos can also contribute to cold dark matter provided that the reheat temperature is adequately low. Gravitinos can constitute the cold dark matter only in limited regions of the parameter space. We present a supersymmetric grand unified model leading to violation of Yukawa unification and, thus, allowing an acceptable b-quark mass within the constrained minimal supersymmetric standard model with mu>0. The model possesses a wide range of parameters consistent with the data on the cold dark matter abundance as well as other phenomenological constraints. Also, it leads to a new version of shifted hybrid inflation.Comment: 32 pages including 6 figures, uses svmult.cls, some clarifications added, lectures given at the Third Aegean Summer School "The Invisible Universe: Dark Matter and Dark Energy", 26 September-1 October 2005, Karfas, Island of Chios, Greece (to appear in the proceedings
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