Multicanonical Monte Carlo Method Applied to the Investigation of Polarization Effects in Optical Fiber Communication Systems

Polarization-mode dispersion (PMD) is a major source of impairments in optical fiber com‐ munication systems. PMD causes distortion and broadens the optical pulses carrying infor‐ mation and lead to inter-symbol interference. In long-haul transmission systems it is necessary to limit the penalty caused by polarization effects [1], so that the probability of ex

Monte Carlo Methods for Simulation of Optical Coherence Tomography of Turbid Media

We describe two importance sampling techniques for a standard Monte Carlo (MC) method that could enable fast simulation of signals from optical coherence tomography (OCT) imaging systems. These OCT signals are generated due to diffusive reflections from either multilayered or arbitrary shaped, turbid media, for example, tissue. Such signals typically consist of ballistic and quasi-ballistic components, of scattered photons inside the medium, in addition to photons that undergo multiple scattering. We show that MC simulation of these OCT signals using importance sampling reduces its computation time on a serial processor by up to three orders of magnitude compared to its corresponding standard implementation. Therefore, these importance sampling techniques enable practical simulation of OCT B-scans of turbid media, for example, tissue, using commonly available workstations

A Step towards Global Engineering Education: The U.S.−Brazil Engineering Exchange Partnership

Global markets are currently dictating the way that national economies around the world design and distribute consumer goods and services. Engineers are in the midst of this dynamic development. In this context, universities around the world are increasingly making an effort to establish international partnerships in their educational and research programs. Study abroad or international programs provide students value-added technical and cultural experiences, and are recognized as high-impact educational experiences. However, engineering students typically do not have the same variety of offerings of international program as students in other disciplines, such as the humanities or social science fields. In this article, the authors provide an overview of the critical aspects of developing a consortium among two universities in the U.S. and two Brazilian universities. The goal of this consortium is establishing a self-sustainable student exchange program in undergraduate engineering education, and increasing the opportunities and participation for American engineering students in international experiences. The activities in this program include the establishment of an agreement between the institutions, the implementation of a course transfer process, and the development of a procedure for foreign language training and cultural preparation. In addition, the authors also discuss the key lessons learned over the first three years of the four-year program (October’07 to September’11)

Complete mitochondrial genomes of the freshwater mussels Amblema plicata (Say, 1817), Pleurobema oviforme (Conrad, 1834), and Popenaias popeii (Lea, 1857) (Bivalvia: Unionidae: Ambleminae)

Freshwater mussels are a critically imperiled group of mollusks that play key ecological roles and provide important services to humans. The Ambleminae is the only subfamily of these mussels, endemic to North America. Complete mitogenomes have only been sequenced for two of five tribes of the subfamily. Pleurobema oviforme, Amblema plicata, and Popenaias popeii each belong to tribes Pleurobemini, Amblemini, and Popenaidini, respectively, and have not had published mitogenomes. Thus, this study aims to present the complete mitogenomes for these species, to provide a phylogeny of the Ambleminae and confirm the gene arrangements with representation from each of its tribes. The newly sequenced mitogenomes range from 15,852 to 15,993 nucleotides, are composed of 13 PCGs, 22 tRNAs, and two rRNAs and all share the same (UF1) gene order.This work was supported by Portuguese Foundation for Science and Technology (FCT) [grant number ConBioMics/BI-Lic/2019-037 (JTT), grant number SFRH/BD/137935/2018 (AGS)]; COMPETE 2020, Portugal 2020 and the European Union through the ERDF, and by Portuguese Foundation for Science and Technology (FCT) through national funds [UID/Multi/04423/2019] under project ConBiomics: the missing approach for the Conservation of Bivalves Project, and [project number NORTE-01- 0145-FEDER-030286]. Fieldwork in Texas was funded by the U.S. Fish and Wildlife Service, and Texas Parks and Wildlife Department (TPWD) as a Joint Traditional Section 6 Project 407348.info:eu-repo/semantics/publishedVersio

Nutritional Status and Adverse Outcomes in Older Depressed Inpatients:A Prospective Study

OBJECTIVES: Significant weight loss and/or loss of appetite is a criterion of a depressive episode. While malnutrition is associated with many adverse health outcomes, the impact of malnutrition in late-life depression has hardly been examined. The present study aims to (1) evaluate the prevalence of malnutrition in depressed older inpatients, and (2) whether and which indices of malnutrition predict adverse health outcomes in late-life depression. DESIGN: A prospective study at 6 months follow-up. SETTING: A University-based psychiatric hospital. PARTICIPANTS: 105 older adults (psychiatric inpatients suffering from unipolar MDD). MEASUREMENTS: Participants were evaluated according the Mini Nutritional Assessment (MNA) and anthropometric measures to assess their nutritional status. Multiple regression analyses were used to evaluate the association between the MNA score as well as anthropometric measures with either falls or rehospitalization for any reason. RESULTS: Based on the MNA score, 78 (74.3%) patients were at risk of malnutrition and 13 (12.4%) actually presented malnutrition. Malnutrition was associated with a higher age, frailty, lower body mass index, and smaller calf circumference. During follow-up, 21 (20%) patients fell, 27 (25.7%) were rehospitalized, and 3 died (2.9%). The MNA score was associated with adverse health outcomes, but a low calf circumference predicted falling (OR 4.93 [95% CI: 1.42-17.2], p=.012) and a higher calf circumference rehospitalization (OR 1.17 [95% CI: 1.01-1.35], p=.032). CONCLUSION: Malnutrition is prevalent in older depressed inpatients. In contrast to subjective proxies for malnutrition, which are common in depression, only objective measures of malnutrition predict adverse health outcomes such as falls and rehospitalization

Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

© 2009 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Biogeosciences 6 (2009): 779-794, doi: 10.5194/bg-6-779-2009Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.This work was supported by grants from the NASA Ocean Biology and Biogeochemistry Program and the NSF Biological Oceanography Program