22 research outputs found

    Energy and volume of vector fields on spherical domains

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    We present in this paper a \boundary version" for theorems about minimality of volume and energy functionals on a spherical domain of threedimensional Euclidean sphere

    ENERGY OF GLOBAL FRAMES

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    Area minimizing unit vector fields on antipodally punctured unit 2-sphere

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    We provide a lower value for the volume of a unit vector field tangent to an antipodally punctured Euclidean sphere S2\mathbb{S}^2 depending on the length of an ellipse determined by the indexes of its singularities. We also exhibit minimizing vector fields v⃗k\vec{v}_k within each index class and show that they are the only ones that are sharp for the volume. These fields have areas given essentially by the length of ellipses depending just on the indexes in NN and SS

    An extensive reef system at the Amazon River mouth

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    Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 x 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (similar to 9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenadoria de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERS)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)BrasoilMCTIBrazilian NavyU.S. NSFGordon and Betty Moore Foundation (GBMF)Univ Fed Rio de Janeiro UFRJ, Inst Biol, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, COPPE, Inst Alberto Luiz Coimbra Posgrad & Pesquisa Engn, Lab Sistemas Avancados Gestao Prod, BR-21941972 Rio de Janeiro, RJ, BrazilInst Pesquisas Jardim Bot Rio de Janeiro, BR-22460030 Rio De Janeiro, RJ, BrazilUniv Sao Paulo, Inst Oceanog, BR-05508120 Sao Paulo, SP, BrazilUniv Fed Espirito Santo, Dept Oceanog, BR-29199970 Vitoria, ES, BrazilUniv Estadual Norte Fluminense, Lab Ciencias Ambientais, Ctr Biociencias & Biotecnol, BR-28013602 Campos Dos Goytacazes, RJ, BrazilUniv Fed Fluminense, Inst Geociencias, BR-24210346 Niteroi, RJ, BrazilUniv Fed Fluminense, Inst Biol, BR-24210130 Niteroi, RJ, BrazilUniv Fed Rio de Janeiro, Museo Nacl, BR-20940040 Rio De Janeiro, RJ, BrazilFed Univ Para, Inst Estudos Costeiros, BR-68600000 Braganca, PA, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilUniv Fed Pernambuco, Dept Oceanog, BR-50670901 Recife, PE, BrazilUniv Georgia, Dept Marine Sci, Athens, GA 30602 USAUniv Fed Paraiba, BR-58297000 Rio Tinto, PB, BrazilUniv Estadual Santa Cruz, Dept Ciencias Biol, BR-45650000 Ilheus, BA, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilU.S. NSF: OCE-0934095GBMF: 2293GBMF: 2928Web of Scienc

    Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

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    Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

    UNIT VECTOR FIELDS ON ANTIPODALLY PUNCTURED SPHERES: BIG INDEX, BIG VOLUME

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    We establish in this paper a lower bound for the volume of a unit vector field (v) over right arrow defined ou S(n) \ {+/-x}, n = 2,3. This lower bound is related to the sum of the absolute values of the indices of (v) over right arrow at x and -x.MEC/FEDER, Spain[MTM2004-04934-C04-02]MEC-FEDER, SpainUniversidade de Sao Paulo (USP), FAPESP[1999/02684-5]Universidade de Sao Paulo (USP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Lehigh UniversityLehigh Universit
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