Bet-hedging strategies in expanding populations

In ecology, species can mitigate their extinction risks in uncertain environments by diversifying individual phenotypes. This observation is quantified by the theory of bet-hedging, which provides a reason for the degree of phenotypic diversity observed even in clonal populations. Bet-hedging in well-mixed populations is rather well understood. However, many species underwent range expansions during their evolutionary history, and the importance of phenotypic diversity in such scenarios still needs to be understood. In this paper, we develop a theory of bet-hedging for populations colonizing new, unknown environments that fluctuate either in space or time. In this case, we find that bet-hedging is a more favorable strategy than in well-mixed populations. For slow rates of variation, temporal and spatial fluctuations lead to different outcomes. In spatially fluctuating environments, bet-hedging is favored compared to temporally fluctuating environments. In the limit of frequent environmental variation, no opportunity for bet-hedging exists, regardless of the nature of the environmental fluctuations. For the same model, bet-hedging is never an advantageous strategy in the well-mixed case, supporting the view that range expansions strongly promote diversification. These conclusions are robust against stochasticity induced by finite population sizes. Our findings shed light on the importance of phenotypic heterogeneity in range expansions, paving the way to novel approaches to understand how biodiversity emerges and is maintained.This study has been partially financed by the Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucía and European Regional Development Fund (ERDF), ref. SOMM17/6105/UGR (to MAM)

Assessing housing quality: relationships between apartment quality, design, and post-occupancy evaluation

Este artigo trata da elaboração de metodologia para Avaliação Pós-Ocupação (APO) em edifícios de apartamentos destinados à classe média edificados em Ribeirão Preto – SP, a partir de 2000, visando a contribuir para a criação de ferramentas eficazes para retroalimentação destes projetos. O objetivo principal da aplicação da APO foi avaliar a qualidade dos espaços internos e coletivos dos apartamentos, buscando estabelecer uma relação entre o comportamento do usuário e o projeto idealizado pelos vários agentes do mercado imobiliário. A metodologia proposta foi elaborada a partir de ampla revisão bibliográfica sobre avaliação pós-ocupação e processo de projeto, assim como na análise crítica da produção de edifícios de apartamentos nas cidades de São Paulo e Ribeirão Preto no período proposto. A aplicação desta metodologia permitiu concluir que o projeto arquitetônico idealizado para os edifícios de apartamentos atuais não tem atendido de maneira satisfatória às reais necessidades dos usuários, destacando assim a premência de uma ampla revisão no processo de criação e de gestão do processo de projeto, ensejando que se desenvolvam procedimentos que incluam bancos de dados alimentados por APOs e também uma participação mais efetiva do arquiteto a frente deste processo. This article discusses a methodology for post-occupancy evaluation (POE) of apartment buildings for the middle class built in Ribeirão Preto, SP, after 2000, aiming at contributing for the establishment of effective feedback tools for this kind of projects. The goal of this POE application was to evaluate the quality of internal and collective spaces of those apartment buildings in an attempt to determine relationships between the user’s behavior and the design produced by different organizations involved in the real estate market. The proposed methodology was based on an extensive literature review on post-occupancy evaluation and design process, as well as on a critical analysis of the production of apartment building in the cities of São Paulo and Ribeirão Preto after 2000. The application of this methodology made it possible to conclude that the architectural design of current apartment buildings has not fulfilled users’ needs. This stresses the need to improve the creativity and the management of the design process, and to develop procedures that include building databases fed by POE and also a more effective participation of architects in this process

In-111 octreotide SPECT/CT in the early diagnosis of pulmonary sarcoidosis: A case report

Sarcoidosis is a granulomatous disease of unknown etiology. At present the best diagnostic imaging procedure to assess stage and activity of sarcoidosis is controversial. We report the case of a 50-year-old male admitted with a history of dyspnea and fatigue with past medical history negative for smoking, occupational and environmental risk factors. Physical examination, routine blood tests, and pulmonary function tests were normal except for hypercalciuria. A chest radiograph showed bilateral hilar lymphadenopathy. Single photon emission computed tomography and/or computed tomography (SPECT and/or CT) In-111 Octreotide (Octreoscan) scintigraphy confirmed morphologic involvement of bilateral hilar lymph nodes and a mediastinoscopy biopsy specimen provided diagnosis of pulmonary sarcoidosis (stage 0). This clinical case shows the effectiveness of In-111 Octreotide SPECT and/or CT in the early diagnosis of pulmonary sarcoidosis

SPAD Figures of Merit for Photon-Counting, Photon-Timing, and Imaging Applications: A Review

Single-photon avalanche diodes (SPADs) emerged as the most suitable photodetectors for both single-photon counting and photon-timing applications. Different complementary metal-oxide-semiconductor (CMOS) devices have been reported in the literature, with quite different performance and some excelling in just few of them, but often at different operating conditions. In order to provide proper criteria for performance assessment, we present some figures of merit (FoMs) able to summarize the typical SPAD performance (i.e., photon detection efficiency, dark counting rate, afterpulsing probability, hold-off time, and timing jitter) and to identify a proper metric for SPAD comparisons, when used either as single-pixel detectors or in imaging arrays. The ultimate goal is not to define a ranking list of best-in-class detectors, but to quantitatively help the end-user to state the overall performance of different SPADs in either photon-counting, timing, or imaging applications. We review many CMOS SPADs from different research groups and companies, we compute the proposed FoMs for all them and, eventually, we provide an insight on present CMOS SPAD technologies and future trends

Planar CMOS analog SiPMs: design, modeling, and characterization

Silicon photomultipliers (SiPMs) are large area detectors consisting of an array of single-photon-sensitive microcells, which make SiPMs extremely attractive to substitute the photomultiplier tubes in many applications. We present the design, fabrication, and characterization of analog SiPMs in standard planar 0.35 μm CMOS technology, with about 1 mm × 1 mm total area and different kinds of microcells, based on single-photon avalanche diodes with 30 μm diameter reaching 21.0% fill-factor (FF), 50 μm diameter (FF = 58.3%) or 50 μm square active area with rounded corner of 5 μm radius (FF = 73.7%). We also developed the electrical SPICE model for CMOS SiPMs. Our CMOS SiPMs have 25 V breakdown voltage, in line with most commercial SiPMs and higher gain (8.8 × 106, 13.2 × 106, and 15.0 × 106, respectively). Although dark count rate density is slightly higher than state-of-the-art analog SiPMs, the proposed standard CMOS processing opens the feasibility of integration with active electronics, for switching hot pixels off, drastically reducing the overall dark count rate, or for further on-chip processing

Migrants' health: Building migrant-sensitive health systems

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Automotive Three-Dimensional Vision Through a Single-Photon Counting SPAD Camera

We present an optical 3-D ranging camera for automotive applications that is able to provide a centimeter depth resolution over a mbox{40}^{\circ} \times mbox{20}^{\circ} field of view up to 45 m with just 1.5 W of active illumination at 808 nm. The enabling technology we developed is based on a CMOS imager chip of 64 \times 32 pixels, each with a single-photon avalanche diode (SPAD) and three 9-bit digital counters, able to perform lock-in time-of-flight calculation of individual photons emitted by a laser illuminator, reflected by the objects in the scene, and eventually detected by the camera. Due to the SPAD single-photon sensitivity and the smart in-pixel processing, the camera provides state-of-the-art performance at both high frame rates and very low light levels without the need for scanning and with global shutter benefits. Furthermore, the CMOS process is automotive certified

Fully CMOS analog and digital SiPMs

Silicon Photomultipliers (SiPMs) are emerging single photon detectors used in many applications requiring large active area, photon-number resolving capability and immunity to magnetic fields. We present three families of analog SiPM fabricated in a reliable and cost-effective fully standard planar CMOS technology with a total photosensitive area of 1×1 mm2. These three families have different active areas with fill-factors (21%, 58.3%, 73.7%) comparable to those of commercial SiPM, which are developed in vertical (current flow) custom technologies. The peak photon detection efficiency in the near-UV tops at 38% (fill-factor included) comparable to commercial custom-process ones and dark count rate density is just a little higher than the best-in-class commercial analog SiPMs. Thanks to the CMOS processing, these new SiPMs can be integrated together with active components and electronics both within the microcell and on-chip, in order to act at the microcell level or to perform global pre-processing. We also report CMOS digital SiPMs in the same standard CMOS technology, based on microcells with digitalized processing, all integrated on-chip. This CMOS digital SiPMs has four 32×1 cells (128 microcells), each consisting of SPAD, active quenching circuit with adjustable dead time, digital control (to switch off noisy SPADs and readout position of detected photons), and fast trigger output signal. The achieved 20% fill-factor is still very good. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only