1,221 research outputs found
Quantifying how landscape composition and configuration affect urban land surface temperatures using machine learning and neutral landscapes
\ua9 2019. The urban heat island effect is an important 21st century issue because it intersects with the complex challenges of urban population growth, global climate change, public health and increasing energy demand for cooling. While the effects of urban landscape composition on land surface temperature (LST) are well-studied, less attention has been paid to the spatial arrangement of land cover types especially in smaller, often more diverse cities. Landscape configuration is important because it offers the potential to provide refuge from excessive heat for both people and buildings. We present a novel approach to quantifying how both composition and configuration affect LST derived from Landsat imagery in Southampton, UK. First, we trained a machine-learning (generalized boosted regression) model to predict LST from landscape covariates that included the characteristics of the immediate pixel and its surroundings. The model achieved a correlation between predicted and measured LST of 0.956 on independent test data (n = 102,935) and included predictors for both the immediate and adjacent land use. In contrast to other studies, we found adjacency effects to be stronger than immediate effects at 30 m resolution. Next, we used a landscape generation tool (Landscape Generator) to alter landscape configuration by varying natural and built patch sizes and arrangements while holding composition constant. The generated neutral landscapes were then fed into the machine learning model to predict patterns of LST. When we manipulated landscape configuration, the average city temperature remained the same but the local minima varied by 0.9 \ub0C and the maxima by 4.2 \ub0C. The effects on LST and heat island metrics correlated with landscape fragmentation indices. Moreover, the surface temperature of buildings could be reduced by up to 2.1 \ub0C through landscape manipulation. We found that the optimum mix of land use types is neither at the land-sharing nor land-sparing extremes, but a balance between the two. In our city, maximum cooling was achieved when ~60% of land was left natural and distributed in 7–8 patches km−2 although this could be location dependent and further work is needed. Opportunities for urban cooling should be required in the planning process and must consider both composition and configuration at the landscape scale if cities are to build capacity for a growing population and climate change
Foscarnet-induced penile ulceration
Foscarnet is used to treat infections with herpes viruses, including drug-resistant cytomegalovirus
(CMV) and infections with herpes viruses 1 and 2 (HSV-1 and HSV-2). There are some reports of
intravenous foscarnet-induced penile and vulvar ulceration. The authors report a case of severe
penile ulcers after the initiation of intravenous foscarnet therap
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Joint Analysis of the Discount Factor and Payoff Parameters in Dynamic Discrete Choice Games
Most empirical models of dynamic games assume the discount factor to be known and focus on the estimation of the payoff parameters. However, the discount factor can be identifed when the payoffs satisfy parametric or other nonparametric restrictions. We show when the payoffs take the popular linear-in-parameter specification, the joint identification of the discount factor and payoff parameters can be simplified to a one-dimensional model that is easy to analyze. We also show that switching costs (e.g. entry costs) that often feature in empirical work can be identifed in closed-form, independently of the discount factor and other specification of the payoff function. Our identification strategies are constructive. They lead to easy to compute estimands that are global solutions. Estimating the discount factor permits direct inference on borrowing rate. Our estimates of the switching costs can be used for specification testing. We illustrate with a Monte Carlo study and the dataset from Ryan (2012)
Cutaneous manifestations of antiphospholipid syndrome: a review of the clinical features, diagnosis and management
Antiphospholipid syndrome is a relatively recent systemic autoimmune disorder defined by thrombotic events and/or obstetric complications in the presence of persistent elevated antiphospholipid antibodies. It is characterized by a wide spectrum of clinical presentations
and virtually any organ system or tissue may be affected by the consequences of vascular occlusion.
Diagnosis is sometimes difficult and although classification criteria have been published and revised there remain ongoing issues regarding nomenclature, expanding clinical features, laboratory tests and management and much still has to be done. Cutaneous manifestations are common and frequently the first sign of the disease. Although extremely diverse it’s important to know which dermatological findings should prompt consideration of antiphospholipid syndrome and the appropriate management for those patients. Much has
been debated about when to consider antiphospholipid syndrome and consensus still does not exist, however in spite of being a diagnostic challenge clinicians should know when to look for antiphospholipid antibodies since an early diagnosis is important to prevent further
and serious complications. In this article we focus on the cutaneous features that should raise suspicion on the presence of antiphospholipid syndrome and on the complex management of such patients. Many other dermatological signs related to this syndrome have been described in the literature but only occasionally and without consistency or statistic impact and therefore will not be considered hereO sÃndrome antifosfolipidico é uma patologia auto-imune relativamente recente definida por eventos trombóticos e/ou complicações obstétricas na presença de anticorpos antifosfolÃpido elevados persistentes. Caracteriza-se por um vasto leque de apresentações clÃnicas e virtualmente qualquer sistema orgânico ou tecido pode ser afectado por oclusão vascular. O diagnóstico é por vezes difÃcil e, apesar de critérios de classificação terem sido publicados e revistos, muitas dúvidas persistem relativamente à nomenclatura, caracterÃsticas clÃnicas, testes laboratoriais e abordagem destes doentes. As manifestações cutâneas são comuns e, frequentemente, o primeiro sinal da doença. Apesar da grande variabilidade, é importante reconhecer os achados dermatológicos que
devem levantar a suspeita de um sÃndrome antifosfolipidico, assim como a abordagem adequada destes doentes. Muito tem sido debatido sobre quando considerar o diagnóstico desta entidade, não havendo ainda consenso neste assunto; no entanto, apesar de ser um desafio diagnóstico, é importante saber quando investigar a presença de anticorpos antifosfolÃpidos, uma vez que um diagnóstico precoce é crucial para prevenir complicações
futuras graves. No presente artigo os autores descrevem as manifestações dermatológicas que devem fazer considerar o diagnóstico com enfoque na abordagem complexa destes doentes. Têm sido descritas na literatura muitas outras alterações cutâneas relacionadas
com esta entidade, no entanto, apenas de forma ocasional e sem consistência ou impacto estatÃstico, pelo que não serão consideradas
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Joint Analysis of the Discount Factor and Payoff Parameters in Dynamic Discrete Choice Games
Most empirical and theoretical econometric studies of dynamic discrete choice models assume the discount factor to be known. We show the knowledge of the discount factor is not necessary to identify parts, or all, of the payoff function. We show the discount factor can be
generically identifed jointly with the payoff parameters. It is known the payoff function cannot nonparametrically identified without any a priori restrictions. Our identification of the discount factor is robust to any normalization choice on the payoff parameters. In IO applications normalizations are usually made on switching costs, such as entry costs and scrap values. We also show that switching costs can be nonparametrically identified, in closed-form, independently of the discount factor and other parts of the payoff function. Our identification strategies are constructive. They lead to easy to compute estimands that are global solutions. We illustrate with a Monte Carlo study and the dataset from Ryan (2012
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Vesico-bullous subacute cutaneous lupus erythematosus – An uncommon entity successfully treated with dapsone and hydroxychloroquine
Vesico-bullous subacute cutaneous lupus erythematosus is an uncommon and severe presentation. The authors report an exuberant case of vesico-bullous subacute cutaneous lupus erythematosus successfully treated with dapsone and hydroxychloroquin
Spatial variation in sound frequency components across an urban area derived from mobile surveys
\ua9 2019 The Author(s). Continuous exposure to noise can lead to premature hearing loss, reduced cognitive performance, insomnia, stress, hypertension, cardiovascular diseases and stroke. Road noise affects the health of >125 million people in the European Union and Member States are required to map major noise hotspots. These strategic noise maps are usually derived from traffic counts and propagation models because large- scale measurement of the acoustic environment using conventional methods is infeasible. In this study, the authors surveyed the entire city of Southampton, UK using a mobile survey technique, capturing spatial variations in street- level sound characteristics across multiple frequencies from all sound sources. Over 52,000 calibrated and georeferenced sound clips covering 11 Hz to 22.7 kHz are analysed here to investigate variations in sound frequency composition across urban space and then applied to two issues: the definition of naturalness in the acoustic environment; and perceptions of social inequity in sound exposure. Clusters of acoustic characteristics were identified and mapped using spectral clustering and principal components analysis based on octave bands, ecoacoustic indices and dBA. We found independent patterns in low, mid and high frequencies, and the ecoacoustic indices that related to land use. Ecoacoustic indices partially mapped onto greenspace, identifying naturalness, but not uniquely, probably because urban anthropogenic sounds occur at higher frequencies than in the natural areas where such indices were developed. There was some evidence of inequity in sound exposure according to social deprivation and ethnicity, and results differed according to frequency bands. The consequences of these findings and the benefits of city-wide sound surveys for urban planning are discussed
Tracking a city’s center of gravity over 500 years of growth from a time series of georectified historical maps
\ua9 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. It is surprising difficult to define where a city center lies, yet its location has a profound effect on a city’s structure and function. We examine whether city center typicality points can be consistently located on historical maps such that their centroid identifies a meaningful central location over a 500-year period in Southampton, UK. We compare movements of this city center centroid against changes in the geographical center of the city as defined by its boundary. Southampton’s historical maps were georectified with a mean accuracy of 21 m (range 9.9 to 47 m), and 18 to 102 typicality points were identified per map, enough to chart changes in the city center centroid through time. Over nearly 500 years, Southampton’s center has moved just 343 m, often corresponding with the key retail attractants of the time, while its population has increased 80-fold, its administrative area 60-fold and its geographical center moved 1985 m. This inertia to change in the city center presents environmental challenges for the present-day, made worse by the geography of Southampton, bounded by the sea, rivers and major roads. Geographical context, coupled with planning decisions in the past that maintain a city center in its historical location, place limits on the current sustainability of a city
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Penile Kaposi sarcoma: A case of complete resolution with highly active antiretroviral therapy alone
Kaposi sarcoma remains an important cause of morbidity in HIV-infected patients. Regardless of the recent pharmacological progress, treatment of this malignancy is still disappointing. We report the case of a patient with Kaposi sarcoma in an unusual localization, the penis, which completely resolved with highly active antiretroviral therapy alon
Rate-flexible optical CDMA networks based on coherent modulation formats
In this paper, we propose, design, and assess the performance of optical coherent access networks based on optical code-division multiple-access (OCDMA) based on three distinct coherent modulation formats, namely, BPSK, QPSK, and 16-QAM. We design a flexible network architecture based on these coherent modulation formats to provide either single data rate transmissions or multiple data rate transmissions. In this way, the network supports users with the same transmission rate, or group of users transmitting at different data rates. We derive new close-form analytical expressions for both single and multiple rate use cases to assess the performance of the coherent OCDMA network. Results shown that the multi-rate data traffic from the users can coexist almost transparently in terms of network performance. The flexible OCDMA network might be a prospective alternative for implementing coherent systems for different service provision according to traffic demand requirements while supporting with high capacity, security, and simultaneous numbers of subscribers. Keywords: BPSK, QPSK, 16-QAM, coherent network, BER, OCDM
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