3,630 research outputs found
Relativistic quantum dynamics of scalar bosons under a full vector Coulomb interaction
The relativistic quantum dynamics of scalar bosons in the background of a
full vector coupling (minimal plus nonminimal vector couplings) is explored in
the context of the Duffin-Kemmer-Petiau formalism. The Coulomb phase shift is
determined for a general mixing of couplings and it is shown that the space
component of the nonminimal coupling is a {\it sine qua non} condition for the
exact closed-form scattering amplitude. It follows that the Rutherford cross
section vanishes in the absence of the time component of the minimal coupling.
Bound-state solutions obtained from the poles of the partial scattering
amplitude show that the time component of the minimal coupling plays an
essential role. The bound-state solutions depend on the nonminimal coupling and
the spectrum consists of particles or antiparticles depending on the sign of
the time component of the minimal coupling without chance for pair production
even in the presence of strong couplings. It is also shown that an accidental
degeneracy appears for a particular mixing of couplings.Comment: 8 pages, 1 table. arXiv admin note: text overlap with arXiv:1403.603
Residential Sector Energy Demand Estimation for a Single-family Dwelling: Dynamic Simulation and Energy Analysis
Detailed demand profiles for the residential sector are an important prerequisite for the improvement of building energy efficiency and the development of polygeneration systems. Therefore, the aim of this paper is to provide a generic pattern for each energy demand required for a single-family dwelling. The data of electricity, domestic hot water and freshwater were obtained through literature reported methods of demand profile estimation, whereas heating and cooling have been estimated by TRNSYS software simulation. All methods provide energy consumption profiles with 1-hour time step along 1-year period. Daily, weekly and yearly results are presented. The total dwelling consumption amounts to 3,866 kWh/y of electricity, 941 kWh/y of heating, 1,450 kWh/y of cooling, 41 m3/y or 2,090 kWh/y of domestic hot water and 110 m3/y of freshwater. Primary energy saving can achieve up to 13,917 kWh/y in case of renewable energy use and a higher comfort level is felt by the users during summer
Serological survey of bovine viral diarrhea (BVDV-1), brucellosis, and leptospirosis in captive white-lipped peccaries (Tayassu pecari) from the Midwest region in Brazil
The present study was conducted to assess the occurrence of anti-Brucella sp., anti-BVDV-1, and anti-Leptospira spp. antibodies from captive white-lipped peccary (Tayassu pecari). A cross-sectional survey was performed testing 100 serum samples collected in a commercial breeding herd. All samples were submitted to the acidified antigen test (AAT), virus neutralization test (VNT) and microscopic agglutination test (MAT) with live antigens. None of the samples tested agglutinated in the AAT screening test. In the VNT, 28 samples presented a cytotoxic effect and were excluded from the evaluation. For BVDV-1, only one sample (1/72; 1.38%) was positive, with antibody titers of 40. For leptospirosis, 9% (9/100) of the samples reacted to at least one of the 24 serovars tested, with 8% (8/100) positive for serovar Patoc and 1% (1/100) for serovar Grippotyphosa. The maximum titer observed was 100. The identification of antibodies against the serovars Patoc and Grippotyphosa suggests that the sampled individuals have been exposed to the pathogen at some point during their lifetime. Regarding BVDV-1, this may be the first serological survey to describe seropositive samples in tayassuids
Avaliação das mudanças no uso e ocupação do solo do Município de Eunápolis-BA através da análise da eficiência dos índices espectrais de NDVI, NDBI e Built-Up/ Evaluation of changes in soil use in the city of Eunápolis-BA through analysis of the efficiency of spectrical indices of NDVI, NDBI and Built-Up
Em Eunápolis, o processo de antropização das paisagens tem se intensificado e vem causando inúmeras preocupações. Dessa forma, esse trabalho tem como objetivo analisar, através de equações, as variações nos índices espectrais do NDVI (Normalized Density Vegetation Index), NDBI (Normalized Difference Built Index) e Built-Up Index para os anos de 2007 e 2021, utilizando como parâmetro as alterações no uso do solo do município nos anos de 1996, 2007 e 2018. Para elaboração dos mapas de uso e ocupação do solo, foram utilizados dados vetoriais secundários oriundos de imagens do satélite Landsat 5 para os anos de 1996 e 2007 e do satélite RapidEye para o ano de 2018, classificadas pelo Fórum Florestal do Extremo Sul da Bahia. Para avaliação dos índices espectrais, foram utilizadas imagens do satélite Landsat 5 para o ano de 2007 e do satélite Landsat 8 para o ano de 2021. Mesmo os índices espectrais de NDBI não apresentando resultados satisfatórios para o município, a elaboração dos índices de NDVI e Built-Up Index apresentou resultados compatíveis com outros estudos, confirmando assim a eficiência na aplicabilidade da técnica em sensoriamento remoto com a finalidade de análise das transformações espaciais.
High-performance removal of 2,4-dichlorophenoxyacetic acid herbicide in water using activated carbon derived from Queen palm fruit endocarp (Syagrus romanzoffiana)
In this work, an activated carbon sample with a high adsorptive performance for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared from queen palm endocarp (Syagrus romanzoffiana) by pyrolysis process. The activated carbon presented an XRD pattern related to carbon graphite and functional groups such as C–H, C˭O, O–H. The material particles presented a highly-porous structure, being beneficial to the adsorption process. The activated carbon showed a remarkable specific surface area of 782 m2 g−1 and pore volume of 0.441 cm3 g−1. The solution pH presented a strong influence on the adsorption process, with ideal pH = 2, being the best adsorbent dosage, 0.5 g L−1. The correspondent removal percentage was 95.4%. The pseudo-second-order model represented kinetic data, presenting R2 > 0.992 and MSR 0.997) and lowest values of MSR (< 92.04 (mg g−1)2), indicating a maximum capacity of 367.77 mg g−1. The thermodynamic study indicated a spontaneous operation, with ΔG0 ranging from –23.2 to −32.6 kJ mol−1 and endothermic process (ΔH0 = 67.30 kJ mol−1), involving physical interactions in the adsorbent/adsorbate system. The adsorbent could be regenerated by NaOH and used 7 times with the same adsorption capacity. Hence, overall, the activated carbon prepared from the Jerivá endocarp corresponds to a promising adsorbent in removing 2,4-D herbicide in wastewater
Simultaneous removal of o-and p-nitrophenol from contaminated water by wet peroxide oxidation using carbon-coated magnetic ferrite as catalyst
Groundwater is the most common source of drinking water worldwide and is currently facing contamination problems with the discharge of pollutants into aquatic systems through different means, namely through municipal, industrial and agricultural activities. Contaminants, such as herbicides, pharmaceuticals, phenolic compounds and personal care products are not removed by conventional treatments from wastewater treatment plants, leading to their accumulation in the environment. In this regard, o-nitrophenol (o-NP) and p-nitrophenol (p-NP), commonly used as raw materials in chemical and pharmaceutical engineering, represent a severe risk to humans and aquatic life, leading to the necessity to properly treat wastewaters containing these contaminants before discharge into the aquatic environment.
Catalytic wet peroxide oxidation (CWPO) showed promising results for removing nitrophenols from wastewater in previous works. In this technology, H2O2 is used as an oxidant, and its interaction with a suitable catalyst leads to the formation of hydroxyl radicals under determined conditions already established in literature (pH and temperature have a strong influence) [1]. Typical catalysts employed have a transition metal in its structure. Carbon-based catalysts also have activity in this technology, mostly ascribed to the electronic properties of the carbonaceous surface. Furthermore, carbon-coated metal oxide materials (hybrid) have also demonstrated potential applications in CWPO. Those structures combine carbon and metal activities with the advantage of protecting the metal core from leaching, increasing the efficiency and stability of the catalysts.Adriano S. Silva thanks his doctoral Grant with reference SFRH/BD/151346/2021 financed by the Portuguese Foundation for Science and Technology (FCT), with funds from NORTE2020, under MIT Portugal Program. This work was financially supported by UIDB/00690/2020 (CIMO), LA/P/0045/2020 (ALiCE), UIDB/50020/2020, UI-DP/50020/2020 (LSRE-LCM) and the project RTChip4Theranostics, with the reference NORTE-01-0145-FEDER-029394. Fernanda F. Roman acknowledges the national funding by FCT through the individual research grant SFRH/BD/143224/2019info:eu-repo/semantics/publishedVersio
Prediction of Early TBI Mortality Using a Machine Learning Approach in a LMIC Population.
Background: In a time when the incidence of severe traumatic brain injury (TBI) is increasing in low- to middle-income countries (LMICs), it is important to understand the behavior of predictive variables in an LMIC's population. There are few previous attempts to generate prediction models for TBI outcomes from local data in LMICs. Our study aim is to design and compare a series of predictive models for mortality on a new cohort in TBI patients in Brazil using Machine Learning. Methods: A prospective registry was set in São Paulo, Brazil, enrolling all patients with a diagnosis of TBI that require admission to the intensive care unit. We evaluated the following predictors: gender, age, pupil reactivity at admission, Glasgow Coma Scale (GCS), presence of hypoxia and hypotension, computed tomography findings, trauma severity score, and laboratory results. Results: Overall mortality at 14 days was 22.8%. Models had a high prediction performance, with the best prediction for overall mortality achieved through Naive Bayes (area under the curve = 0.906). The most significant predictors were the GCS at admission and prehospital GCS, age, and pupil reaction. When predicting the length of stay at the intensive care unit, the Conditional Inference Tree model had the best performance (root mean square error = 1.011), with the most important variable across all models being the GCS at scene. Conclusions: Models for early mortality and hospital length of stay using Machine Learning can achieve high performance when based on registry data even in LMICs. These models have the potential to inform treatment decisions and counsel family members. Level of evidence: This observational study provides a level IV evidence on prognosis after TBI
Mismatch between midline shift and hematoma thickness as a prognostic factor of mortality in patients sustaining acute subdural hematoma.
BACKGROUND: Acute subdural hematoma (ASDH) is a traumatic lesion commonly found secondary to traumatic brain injury. Radiological findings on CT, such as hematoma thickness (HT) and structures midline shift (MLS), have an important prognostic role in this disease. The relationship between HT and MLS has been rarely studied in the literature. Thus, this study aimed to assess the prognostic accuracy of the difference between MLS and HT for acute outcomes in patients with ASDH in a low-income to middle-income country. METHODS: This was a post-hoc analysis of a prospective cohort study conducted in a university-associated tertiary-level hospital in Brazil. The TRIPOD (Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis) statement guidelines were followed. The difference values between MLS and HT (Zumkeller index, ZI) were divided into three categories (3). Logistic regression analyses were performed to reveal the OR of categorized ZI in predicting primary outcome measures. A Cox regression was also performed and the results were presented through HR. The discriminative ability of three multivariate models including clinical and radiological variables (ZI, Rotterdam score, and Helsinki score) was demonstrated. RESULTS: A total of 114 patients were included. Logistic regression demonstrated an OR value equal to 8.12 for the ZI >3 category (OR 8.12, 95% CI 1.16 to 40.01; p=0.01), which proved to be an independent predictor of mortality in the adjusted model for surgical intervention, age, and Glasgow Coma Scale (GCS) score. Cox regression analysis demonstrated that this category was associated with 14-day survival (HR 2.92, 95% CI 1.38 to 6.16; p=0.005). A multivariate analysis performed for three models including age and GCS with categorized ZI or Helsinki or Rotterdam score demonstrated area under the receiver operating characteristic curve values of 0.745, 0.767, and 0.808, respectively. CONCLUSIONS: The present study highlights the potential usefulness of the difference between MLS and HT as a prognostic variable in patients with ASDH. LEVEL OF EVIDENCE: Level III, epidemiological study
Morfogênese in vitro e indução de calos embriogênicos a partir de embriões zigóticos de jarina: o marfim da Amazônia.
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