496 research outputs found

    Evaluation of a new wideband slot array for MIMO performance enhancement in indoor WLANs

    Get PDF
    WOS:000289205200016 (Nº de Acesso Web of Science)“Prémio Científico ISCTE-IUL 2012”A new wideband compact slot antenna array for indoor WLAN access points (AP) is described, covering several wireless communication services from 2.4 to 4.8 GHz, that is especially designed to enhance MIMO system capacity. The array topology provides both spatial and polarization diversity. Despite very close packing of the array elements, these exhibit very low mutual coupling and low cross-polarization, greatly favoring MIMO diversity gain. A detailed MIMO performance comparison is conducted against a common array of patches in indoor environment, based both on simulation and indoor measurements: the new antenna shows a clear improvement in terms of channel capacity

    Wideband slot antenna for WLAN access points

    Get PDF
    WOS:000275560600001 (Nº de Acesso Web of Science)“Prémio Científico ISCTE-IUL 2011”This letter presents a new printed slot antenna with cavity back for wireless local area network (WLAN) access points (base stations) providing wideband operation bandwidth at least from 2.5 to 4.8 GHz. The design is based upon an ultrawideband (UWB) antenna configuration modified with the inclusion of a cavity back in order to produce stable unidirectional radiation pattern. The new configuration also ensures a stable linear polarization with cross-polarization level below 20 dB. Results are confirmed with measurements. Not disregarding other applications, the new design is especially adequate for multiple-input–multiple-output (MIMO) space and polarization diversity arrangements, presenting low cross polarization and very low coupling to adjacent elements

    Detecting retinal nerve fibre layer segmentation errors on spectral domain-optical coherence tomography with a deep learning algorithm

    Get PDF
    In this study we developed a deep learning (DL) algorithm that detects errors in retinal never fibre layer (RNFL) segmentation on spectral-domain optical coherence tomography (SDOCT) B-scans using human grades as the reference standard. A dataset of 25,250 SDOCT B-scans reviewed for segmentation errors by human graders was randomly divided into validation plus training (50%) and test (50%) sets. The performance of the DL algorithm was evaluated in the test sample by outputting a probability of having a segmentation error for each B-scan. The ability of the algorithm to detect segmentation errors was evaluated with the area under the receiver operating characteristic (ROC) curve. Mean DL probabilities of segmentation error in the test sample were 0.90 +/- 0.17 vs. 0.12 +/- 0.22 (P < 0.001) for scans with and without segmentation errors, respectively. The DL algorithm had an area under the ROC curve of 0.979 (95%CI: 0.974 to 0.984) and an overall accuracy of 92.4%. For the B-scans with severe segmentation errors in the test sample, the DL algorithm was 98.9% sensitive. This algorithm can help clinicians and researchers review images for artifacts in SDOCT tests in a timely manner and avoid inaccurate diagnostic interpretations9COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESSem informaçã

    Influence of Distinct Curing Environments on the Compressive Strength of Concrete

    Get PDF
    This paper discusses the influence of different curing conditions on the compressive strength of concrete test specimens monitored for 365 days. Five cures were analyzed. Statistical tests were applied (variance analysis and Fisher’s) in order to evaluate the data. According to results, different curing conditions influence the compressive strength of concrete. The main novelty of this article is that the curing conditions affect the concrete compressive strength significantly only for ages over 28 days. Furthermore, this study shows that concrete specimens saturated with water have superior strength to concrete cured in a standard environment (moist chamber). The compressive strength of concrete decreases, respectively, with the following types of curing investigated: water tank, moist chamber, tank with water and lime, laboratory internal environment and external environment. The compressive strength gain over time also varies for each condition. The lower values found for the external environment confirm the greater difficulty of controlling the water loss on this environment, resulting in decrease of compressive strength

    Diversidade da fauna de insectos fitófagos e de inimigos naturais em culturas frutícolas da ilha Terceira, Açores: a importância do maneio e da heterogeneidade ambiental

    Get PDF
    "A evidência mostra que os artrópodes constituem uma fracção importante da biodiversidade estrutural e funcional dos habitats terrestres (Kim, 1993). Por outro lado, só é possível conservar os processos ecológicos associados aos artrópodes promovendo a gestão correcta dos seus habitats. Para tal, é necessária uma correcta identificação e caracterização das suas comunidades de forma a promover a sua boa gestão. Durante os últimos anos têm sido realizados nos Açores vários estudos de inventariação e caracterização ecológica dos artrópodes em alguns dos habitats mais importantes destas ilhas: i) habitat cavernícola (Borges & Oromí, 1994); ii) pastagens semi-naturais e intensivas (Borges & Brown, 2001, 2003, 2004); iii) florestas nativas dos Açores (Borges et al., 2000, 2005a, b, 2006; Ribeiro et al., 2005). No entanto, na diversidade de usos do solo das ilhas açoreanas, as fruteiras constituem um habitat mal estudado em termos da cadeia trófica de artrópodes (contudo ver Oliveira, 2002). […]" (da Introdução)

    The Prevalence of Thyroid Dysfunction in Elderly Cardiology Patients with Mild Excessive Iodine Intake in the Urban Area of São Paulo

    Get PDF
    OBJECTIVES: To evaluate the prevalence of thyroid dysfunction in elderly cardiac patients in an outpatient setting. SUBJECTS AND METHODS: A total of 399 consecutive patients (268 women, age range 60-92 years) who were followed at Heart Institute were evaluated for thyroid dysfunction with serum free T4, TSH, anti-Peroxidase antibodies, urinary iodine excretion measurements and thyroid ultrasound. RESULTS: Hyperthyroidism (overt and subclinical) was present in 29 patients (6.5%), whereas hypothyroidism (overt and subclinical) was found in 32 individuals (8.1%). Cysts were detected in 11 patients (2.8%), single nodules were detected in 102 (25.6%), and multinodular goiters were detected in 34 (8.5%). Hashimoto's thyroiditis was present in 16.8% patients, most of whom were women (83.6%). The serum TSH increased with age and was significantly higher (p= <0.01) in patients, compared to the normal control group. No significant differences in serum TSH and free T4 values were observed when patients with atrial fibrillation (AF) where compared with those without arrhythmia. The median urinary iodine levels were 210 µg/L (40-856 µg/L), and iodine levels were higher in men than in women (p<0.01). Excessive iodine intake (urinary iodine >300 µg/L) was observed in one-third of patients (30.8%). CONCLUSIONS: Elderly patients have a higher prevalence of both hypo- and hyperthyroidism as well as thyroid nodules when compared with the general population. About one-third of the older patients had elevated urinary secretion of iodine and a higher prevalence of chronic Hashimoto's thyroiditis. It is recommended that ultrasonographic studies, tests for thyroid function and autoimmunity should be evaluated in elderly patients

    TEMPERATURA, LUMINOSIDADE E MEIO DE CULTURA AFETANDO A PRODUÇÃO DE ESCLERÓCIOS DE Sclerotium rolfsii E Sclerotinia sclerotiorum

    Get PDF
    This study evaluated in vitro production of sclerotia of Sclerotium rolfsii and Sclerotinia sclerotiorum in different culture media, temperatures, and light conditions. This kind of standardization is necessary for the production of pure inoculum, that could be used for tests of pathogenicity and plant resistance to diseases. These experiments were conducted under standard laboratory conditions in a completely randomized experimental design. The results of the trials showed that S. rolfsii produced more sclerotia on PDA (potato-dextrose-agar) at 27ºC under 24 h of fluorescent white-light. However, S. sclerotiorum produced more sclerotia on PDA at 21ºC independent of light condition (light or darkness). PEGA (peptona, yeast extract, glucose, agar), NA (nutrient agar), and FA (potato starch, dextrose, agar) media did not induce any production of a significant amount of sclerotia.Neste estudo avaliou-se as condições ideais para a produção in vitro de inóculo de Sclerotium rolfsii e Sclerotinia sclerotiorum. Quantificou-se, em placas de petri com meio de cultura artificial, a produção de esclerócios destes fungos sob diferentes regimes de temperatura, luminosidade e meios de cultura. Esta padronização é necessária quando se deseja produzir inóculo puro e em quantidade elevada, para testes de patogenicidade e de resistência de plantas à doenças. Os experimentos foram conduzidos sob condições controladas de laboratório em um delineamento inteiramente casualizado. Nos testes executados verificou-se que S. rolfsii desenvolveu-se melhor e produziu mais esclerócios em meio BDA (batata, dextrose, ágar) tradicional, a 27ºC e com 24 h de luz branca fluorescente. Todavia, S. sclerotiorum produziu mais esclerócios em BDA, a 21ºC com ou sem luz. Os meios PEGA (peptona, extrato de levedura, glucose e ágar), NA (nutriente ágar) e FA (fécula ou amido de batata, glucose e ágar) não induziram uma formação significativa de esclerócios

    Cytogenetic analysis of baryancistrus xanthellus (Siluriformes: Loricariidae: Ancistrini), an ornamental fish endemic to the Xingu river, Brazil

    Get PDF
    Baryancistrus xanthellus is a species from the Ancistrini tribe known commonly as “amarelinho” or “golden nugget pleco”. It is one of the most popular and valued ornamental fishes due to its color pattern. Also, it is an endemic species from the Xingu River occurring from Volta Grande do Xingu, region where the Belo Monte Hydropower Dam is being built, to São Félix do Xingu. The current study aimed to cytogenetically characterize B. xanthellus. Results point to the maintenance of 2n=52, which is considered the most common condition for the tribe, and a single nucleolus organizer region (NOR). Mapping of the 18S rDNA confirmed the NOR sites, and the 5S rDNA was mapped in the interstitial position of a single chromosome pair. The 18S and 5S rDNA located in different pairs constitute an apomorphy in Loricariidae. Large blocks of heterochromatin are present in pairs 1 and 10 and in the regions equivalent to NOR and the 5S rDNA. Data obtained in this study corroborated with the currently accepted phylogenetic hypothesis for the Ancistrini and demonstrate evidence that the genus Baryancistrus occupies a basal position in the tribe. © 2016, Sociedade Brasileira de Ictiologia. All rights reserved

    Tuberculosis among HIV-1-infected subjects in a tertiary out-patient service in São Paulo city, Brazil

    Get PDF
    Atualmente, a tuberculose (TB) é considerada a doença infecciosa mais importante entre os pacientes infectados pelo HIV-1 nos países em desenvolvimento, como o Brasil. Análise retrospectiva dos casos de tuberculose ocorridos a partir de janeiro 1995 até dezembro de 2010 foi realizada em nossa coorte de 599 pacientes HIV positivos. O desfecho primário foi a ocorrência de TB ativa, e 41 casos da doença foram diagnosticados durante este período de 16 anos. As contagens médias do nadir de células T CD4 e ao momento do diagnóstico de TB foram de 146 e 217 células/mm³, respectivamente. A carga viral média de HIV foi de 5,19 log10 cópias/mL, e 59% dos pacientes estavam em tratamento com ART. A incidência de TB foi de 1,47 casos por 100 pessoas-ano, para um tempo total de seguimento da coorte de 2775 pessoas-ano. A probabilidade de sobreviver até 10 anos após o diagnóstico foi de 75% para pacientes com TB, em oposição a 96% para pacientes com outras doenças oportunistas não-TB (p = 0,03). A tuberculose pode ser considerada problema de saúde pública entre as pessoas que vivem com HIV no Brasil, apesar da ampla utilização de anti-retrovirais para o tratamento da infecção pelo HIV / AIDS.TB is currently considered to be the most important infectious disease among HIV-1-infected subjects in developing countries, such as Brazil. A retrospective analysis of TB cases was performed, occurring from January 1995 to December 2010 in our cohort of 599 HIV positive patients. The primary outcome was the occurrence of active TB. Forty-one TB cases were diagnosed over this period of 16 years, among 599 HIV positive patients in an open cohort setting in the city of Sao Paulo, Brazil. All-time lowest mean CD4 T cell count at the time of TB diagnosis was 146 and 186 cells/mm³, respectively. The mean HIV viral load was 5.19 log10 copies/mL, and 59% of the patients were on HAART. TB incidence was 1.47 per 100 person-years, for a total follow-up time of 2775 person-years. The probability of surviving up to 10 years after diagnosis was 75% for TB patients as opposed to 96% for patients with other, non-TB opportunistic diseases (p = 0.03). TB can be considered a public health problem among people living with HIV in Brazil despite of the widespread use of antiretrovirals for the treatment of HIV infection/AIDS
    corecore