Unitary expansion of the time evolution operator

We propose an expansion of the unitary evolution operator, associated to a given Schr\"odinger equation, in terms of a finite product of explicit unitary operators. In this manner, this unitary expansion can be truncated at the desired level of approximation, as shown in the given examples.Comment: 6 pages, 7 figures. Updated version, minor final change

Produção de água de coco do híbrido Anão Vermelho do Brasil de Gramane x Gigante do oeste africano em função da idade de colheita do fruto.

bitstream/CPATC-2009-09/20636/1/cot_85.pdfMeta 2008

Scaling of variables and the relation between noncommutative parameters in Noncommutative Quantum Mechanics

We consider Noncommutative Quantum Mechanics with phase space noncommutativity. In particular, we show that a scaling of variables leaves the noncommutative algebra invariant, so that only the self-consistent effective parameters of the model are physically relevant. We also discuss the recently proposed relation of direct proportionality between the noncommutative parameters, showing that it has a limited applicability.Comment: Revtex4, 4 pages; version to match the published on

A New Action Principle for Witten's Topological Field Theory

In this letter a new gauge invariant, metric independent action is introduced from which Witten's Topological Quantum Field Theory may be obtained after gauge fixing using standard BRST techniques. In our model the BRST algebra of transformations, under which the effective action is invariant, close off-shell in distintion with what occurs in the one proposed by Labastida and Pernici. Our approach provides the geometrical principle for the quantum theory. We also compare our results with an alternative formulation presented by Baulieu and Singer.Comment: 8 pages, SB/F-94-22

Acceleration patterns in the perception of biological motion

A lot of natural stimuli are characterized by acceleration patterns. However, available studies are inconclusive about the importance of these patterns on visual perception. Empirical findings seems to both sustain that acceleration patterns might have, or might have not, a significant role on visual perception [Runeson, 1974 Psychological Research 37 3-23; McIntyre et al, 2001 Nature Neuroscience 4(7) 693-694]. In a recent study Chang and Troje [2009 Journal of Vision 9(1) 19-17] stressed the role of acceleration patterns for the perception of biological motion. Nevertheless, we have a limited understanding about the implications of these patterns for translational stimuli. The present study aimed to investigate how acceleration patterns influence the perception of biological translational motion. We manipulated the velocity of the translational component (maintaining spatial characteristics). This allowed us to create a continuum of stimuli that ranged from natural motion to constant velocity. When two stimuli are presented simultaneously participants are asked to choose which appears more natural. Data shows that subjects choose the stimulus closest to the natural motion—biological motion. Results reveal a great accuracy in detecting the stimulus closest to biological motion, which suggests that acceleration patterns are important in the perception of translational biological motion.Fundação para a Ciência e a Tecnologia (FCT

The impact of healthcare-associated infection on mortality: failure in clinical recognition is related with inadequate antibiotic therapy

Purpose To understand if clinicians can tell apart patients with healthcare-associated infections (HCAI) from those with community-acquired infections (CAI) and to determine the impact of HCAI in the adequacy of initial antibiotic therapy and hospital mortality. Methods One-year prospective cohort study including all consecutive infected patients admitted to a large university tertiary care hospital. Results A total of 1035 patients were included in this study. There were 718 patients admitted from the community: 225 (31%) with HCAI and 493 (69%) with CAI. Total microbiologic documentation rate of infection was 68% (n = 703): 56% in CAI, 73% in HCAI and 83% in hospital-acquired infections (HAI). Antibiotic therapy was inadequate in 27% of patients with HCAI vs. 14% of patients with CAI (p<0.001). Among patients with HCAI, 47% received antibiotic therapy in accordance with international recommendations for treatment of CAI. Antibiotic therapy was inadequate in 36% of patients with HCAI whose treatment followed international recommendations for CAI vs. 19% in the group of HCAI patients whose treatment did not follow these guidelines (p = 0.014). Variables independently associated with inadequate antibiotic therapy were: decreased functional capacity (adjusted OR = 2.24), HCAI (adjusted OR = 2.09) and HAI (adjusted OR = 2.24). Variables independently associated with higher hospital mortality were: age (adjusted OR = 1.05, per year), severe sepsis (adjusted OR = 1.92), septic shock (adjusted OR = 8.13) and inadequate antibiotic therapy (adjusted OR = 1.99). Conclusions HCAI was associated with an increased rate of inadequate antibiotic therapy but not with a significant increase in hospital mortality. Clinicians need to be aware of healthcare-associated infections among the group of infected patients arriving from the community since the existing guidelines regarding antibiotic therapy do not apply to this group and they will otherwise receive inadequate antibiotic therapy which will have a negative impact on hospital outcome.Funding: Supported by an unrestricted grant from ASSUCIP (Associação de Apoio à Unidade de Cuidados Intensivos Polivalente, Hospital de Santo António, Porto, Portugal). Teresa Cardoso is partially funded by a PhD research grant from the Teaching and Research Department (Departamento de Formação, Ensino e Investigação) of Oporto Hospital Centre (reference number 069/07(051-DEFI/084-CES)). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Cultura in vitro de embriões zigóticos de coqueiro anão verde do Brasil de Jiqui.

bitstream/CPATC/19571/1/bp-23.pdfISSN 1678-7961