Some boundary effects in quantum field theory

We have constructed a quantum field theory in a finite box, with periodic boundary conditions, using the hypothesis that particles living in a finite box are created and/or annihilated by the creation and/or annihilation operators, respectively, of a quantum harmonic oscillator on a circle. An expression for the effective coupling constant is obtained showing explicitly its dependence on the dimension of the box.Comment: 12 pages, Late

Avaliação da composição do leite de cabras Moxotó, Canindé, SRD e anglonubiana criadas no Semi-Árido do Rio Grande do Norte.

O objetivo desse estudo foi avaliar o efeito da época do ano e da raça sobre a composição do leite de cabras criadas extensivamente (pastagem nativa) em uma região semi-árida do Rio Grande do Norte. Foram utilizadas 12 cabras em lactação, sendo quatro Moxotó, quatro Canindé, quatro SRD (sem raça definida) e quatro Anglunubiana. As amostras de leite foram coletadas a cada duas semanas, na ordenha da manhã, de 27/11/2007 a 11/06/2008 (27/11/07 a 04/03/08 - estação seca e 18/03/08 a 11/06/08 - estação chuvosa). O leite foi avaliado quanto ao seu teor de gordura, proteína, lactose, estrato seco total (EST) e estrato seco desengordurado (ESD). Houve efeito significativo (P<0,05) da raça e da estação do ano na composição do leite. Em ambas as estações, o leite das cabras Canindé, Moxotó e Anglonubiana apresentou teores de gordura e proteína superiores (P<0,05) ao leite das cabras SRD, podendo ser indicados para a produção de queijo

Colorblind and multicultural diversity strategies create identity management pressure

This is the final version. Available on open access from Wiley via the DOI in this recordColorblind and multicultural diversity strategies may create identity management pressure, leading minorities to assert or distance from their racial identity. In two experiments (N = 307, 279), Asian participants in the US completed racial identification measures, contemplated employment at a company expressing a multicultural, colorblind, or control strategy, and completed measures assessing ingroup similarity and comfort in the company. In the colorblind condition, those strongly identified with their racial ingroup downplayed similarity to the ingroup and expressed less comfort relative to multicultural and control conditions. Those weakly identified reported more similarity (but inconsistently) and more comfort in the colorblind relative to multicultural and control conditions. Thus, diversity strategies convey different meanings to strongly and weakly identified Asians, with the former responding to colorblindness with identity distancing and the latter with identity assertion. Multiculturalism does not alter the typical pattern expected, with strongly identified asserting their identity more than weakly identified.Economic and Social Research Council (ESRC

Nonlinear Relativistic and Quantum Equations with a Common Type of Solution

Generalizations of the three main equations of quantum physics, namely, the Schr\"odinger, Klein-Gordon, and Dirac equations, are proposed. Nonlinear terms, characterized by exponents depending on an index $q$, are considered in such a way that the standard linear equations are recovered in the limit $q \rightarrow 1$. Interestingly, these equations present a common, soliton-like, travelling solution, which is written in terms of the $q$-exponential function that naturally emerges within nonextensive statistical mechanics. In all cases, the well-known Einstein energy-momentum relation is preserved for arbitrary values of $q$

Uso de agentes de biocontrole sobre a brusone das panículas do arroz em campo.

O objetivo foi avaliar a redução da severidade da brusone nas panículas do arroz com uso de rizobactérias Burkholderia pyrrocinia e Pseudomonas fluorensces e quatro isolados do fungo Trichoderma asperellum

Barragem subterranea: um estudo de caso.

O armazenamento de água em aquíferos artificiais, por meio de barragens subterrâneas, pode ser uma alternativa para suprir as necessidades de água no meio rural, principalmente para consumo vegetal. Em Alexandria - RN, em uma barragem subterrânea com área de 2,0 ha, verificou-se um aumento significativo na produção das culturas de milho, feijão e arroz, permitindo ao produtor comercializar o excedente da produção e aumentar a renda familiar

Exact solution for the energy density inside a one-dimensional non-static cavity with an arbitrary initial field state

We study the exact solution for the energy density of a real massless scalar field in a two-dimensional spacetime, inside a non-static cavity with an arbitrary initial field state, taking into account the Neumann and Dirichlet boundary conditions. This work generalizes the exact solution proposed by Cole and Schieve in the context of the Dirichlet boundary condition and vacuum as the initial state. We investigate diagonal states, examining the vacuum and thermal field as particular cases. We also study non-diagonal initial field states, taking as examples the coherent and Schrodinger cat states.Comment: 10 pages, 8 figure

Intake, nutrients digestibility and nitrogen balance of elephant grass silages with mango by-product addition.

The objective of this study was to evaluate the nutritive value of elephant grass silages with increasing levels of dried mango by-product (DMB). Five addition levels were studied (0, 4, 8, 12 and 16%) using 20 rams, in a randomized complete design with five treatments (addition levels) and four replications. Dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), total carbohydrates (TC), non-fibrous carbohydrates (NFC) intake and digestibility were evaluated, as well as the total digestible nutrients (TDN) and the silage nitrogen balance (NB). Mango by-product addition did not influence the DM, CP and TC intakes, the TDN level or the OM, CT and NFC digestibilities. On the other hand, DMB addition reduced the NDF and the ADF intakes, as well as the DM, CP, NDF and ADF digestibilities, and the NB of the silages. There was also a increasing linear effect of DMB addition on the EE and NFC intakes, and on EE digestibility. The elephant grass silage with DMB by-product may not be used as a single feed to ruminants because it reduces the NDF and the ADF intakes and the DM, CP, NDF and ADF digestibilities, as well as the nitrogen balance

Caracterização e avaliação da potencialidade dos solos do município de Santa Izabel do Pará - Estado do Pará.

bitstream/item/57194/1/Doc100.pdfAnexo mapas: Mapa de solos do Município de Santa Izabel do Pará - Pará; Mapa de vegetação e uso das terras do Município de Santa Izabel - Pará

Absolute Hyperglycemia versus Stress Hyperglycemia Ratio for the Prognosis of Hospitalized Patients with COVID-19 in the First Months of the Pandemic: A Retrospective Study

Diabetes is a risk factor for greater severity of coronavirus disease 2019 (COVID-19). The stress hyperglycemia ratio (SHR) is an independent predictor of critical illness, and it is reported to have a stronger association than absolute hyperglycemia. The aim of this study was to assess the relationship of absolute hyperglycemia and SHR with the severity of COVID-19, since there are no studies investigating SHR in patients with COVID-19. We conducted a retrospective observational study on hospitalized patients with COVID-19 in the first months of the pandemic, regarding absolute hyperglycemia, SHR, and severity outcomes. Of the 374 patients, 28.1% had a previous diagnosis of type 2 diabetes. Absolute hyperglycemia (64.8% versus 22.7%; p < 0.01) and SHR [1.1 (IQR 0.9-1.3) versus 1.0 (IQR 0.9-1.2); p < 0.001] showed a statistically significant association with previous diabetes. Absolute hyperglycemia showed a significant association with clinical severity of COVID-19 (79.0% versus 62.7%; p < 0.001), need for oxygen therapy (74.8% versus 54.4%; p < 0.001), invasive mechanical ventilation (28.6% versus 11.6%; p < 0.001), and intensive care unit (30.3% versus 14.9%; p = 0.002), but not with mortality; by contrast, there was no statistically significant association between SHR and all these parameters. Our results are in agreement with the literature regarding the impact of absolute hyperglycemia on COVID-19 severity outcomes, while SHR was not a significant marker. We therefore suggest that SHR should not be evaluated in all patients admitted in the hospital for COVID-19, and we encourage the standard measures at admission of blood glucose and HbA1c levels.info:eu-repo/semantics/publishedVersio