Black hole shadow of a rotating polytropic black hole by the Newman--Janis algorithm without complexification

In this work, starting from a spherically symmetric polytropic black hole, a rotating solution is obtained by following the Newman--Janis algorithm without complexification. Besides studying the horizon, the static conditions and causality issues of the rotating solution, we obtain and discuss the shape of its shadow. Some other physical features as the Hawking temperature and emission rate of the rotating polytropic black hole solution are also discussed.Comment: 9 pages, 2 figures, some references adde

Radiative non-isothermal Bondi accretion onto a massive black hole

In this paper, we present the classical Bondi accretion theory for the case of non-isothermal accretion processes onto a supermassive black hole (SMBH), including the effects of X-ray heating and the radiation force due to electron scattering and spectral lines. The radiation field is calculated by considering an optically thick, geometrically thin, standard accretion disk as the emitter of UV photons and a spherical central object as a source of X-ray emission. In the present analysis, the UV emission from the accretion disk is assumed to have an angular dependence, while the X-ray/central object radiation is assumed to be isotropic. This allows us to build streamlines in any angular direction we need to. The influence of both types of radiation is evaluated for different flux fractions of the X-ray and UV emissions with and without the effects of spectral line driving. We find that the radiation emitted near the SMBH interacts with the infalling matter and modifies the accretion dynamics. In the presence of line driving, a transition resembles from pure type 1 & 2 to type 5 solutions (see Fig2.1 of Frank etal. 2002), which takes place regardless of whether or not the UV emission dominates over the X-ray emission. We compute the radiative factors at which this transition occurs, and discard type 5 solution from all our models. Estimated values of the accretion radius and accretion rate in terms of the classical Bondi values are also given. The results are useful for the construction of proper initial conditions for time-dependent hydrodynamical simulations of accretion flows onto SMBH at the centre of galaxies.Comment: 10 pages, 10 figures, Accepted to be published in A&

Beyond the software: The importance of personal communication to ensure access in complex ILL and other borrowing transactions

This paper focuses on the ILL aspects of a larger project investigating the continued availability of items identified in a 1991 bibliography (Dillard). For this stage of the research, the particular focus was on obtaining various theses and dissertations, as well as books and sheet music items. As Lowry (2006) noted, especially in the humanities and social sciences, the majority of dissertation and thesis research has traditionally not resulted in further publication, with only about 10% of this work being republished in other forms. This means that the original works are the only source of this research, and therefore there is a need for continued access. While aggregated databases such as ProQuest Dissertation and Theses Global provide instant full text access in many cases, other items are only available for separate purchase through the database, by borrowing through ILL channels, for download from individual institutional repositories, or for viewing in the library of the degree-granting institution (Smith, 2023). There are also issues in identifying more recent dissertation and theses research as there is no one universal source, but rather a proliferation of different directories and research databases where they may be listed, or they may only be listed within a single institutional repository (Center for Research Libraries, n.d.). Despite the many difficulties encountered, one theme emerged from these retrieval endeavors: the importance of personal communication in overcoming barriers and ensuring access to materials. This paper highlights the different ways in which establishing communication promoted understanding firstly between the ILL librarian and the researcher, and then at each stage of the borrowing process, resulting in mostly successful transactions. Communication was able to overcome barriers of the borrowing institution’s ILL policy that previously prevented successful transactions; it enabled navigation through complex and multi-stage digitization requests involving international universities and national libraries; it enabled direct digitization and electronic delivery of items at no cost to the borrower; and it enabled identification and retrieval of items from institutional repositories

Inclusion of Secale cereale and Pentosanases in the Ration of Laying Hens: Exploring its Effect on Egg Production and Concentrate Intake and Searching the Optimal Combination in a Diet

Background and Objective: Antinutritional factors are usually found in cereals, these correspond to molecular complexes structured by carbohydrates present in the grains, which increase the viscosity of the food bolus, resulting in diminished organic matter digestibility, food intake and egg production. These polymers are known as soluble non-starch polysaccharides (NSPs). The objective of this experiment was to assess the effect of incorporating Secale cereale (SEc) and pentosanases (EEp) in the diets of laying hens (Lohmann LSL hybrid) on their egg production (EP) and concentrate consumption (CC), optimal combination between the main factors was estimated for EP and CC. Materials and Methods: The trial was carried out on a commercial egg-producing poultry farm (Valparaíso Region, Chile). A completely randomized experimental design was used, with a 4×5 factorial arrangement of two factors (four levels for SEc and five levels for EEp). Ten repetitions were used per treatment, where each experimental unit corresponded to one cage with five hens. A contour curvature analysis was carried out to determine the optimal level of inclusion of SEc with EEp. The experimental period lasted 84 days. Results: There was an interaction effect of SEc and EEp on EP and CC. The optimum level of inclusion for EP was 200 g kg–1 SEc and 1 g kg–1 EEp, with average production of 396 units, for CC, the optimum value observed corresponded to 200 g kg–1 SEc with 0.5 g kg–1 EEp (47.56 kg). The lowest EP and CC responses, regardless of the EEp level in the diet, was observed with the inclusion of 600 g kg–1 SEc. The contour area curvature analysis for EP gave a high response curve zone between 130-390 g kg–1 SEc and 0.38-1.57 g kg–1 EEp, the highest response levels for CC were 120-350 g kg–1 SEc and 0.43-1.75 g kg–1 EEp. Conclusion: In this research it was possible to establish that high level of SEc inclusion in the diet affects negatively eggs production and concentrate intake. However, when pentosanases are included in the diet improve these variables. These results suggest possible antinutritional factors of SEc that could have caused negative effects on the hens' physiological response

Occupational Health and Safety Prevention Plan in Water Treatment Plant

The research was carried out at the "El Guarumo" drinking water plant located in Santa Ana, province of Manabí, Ecuador. The objective of the investigation was the proposal of a plan of prevention of occupational risks that allows the management of the labor risks in said plant. The main tools used were: survey, interview, checklist, LEST questionnaire for the diagnosis of the current situation in terms of working conditions, the risk identification matrix and the binary method of risk assessment. The main results obtained were the identification of the risks in their different categories, observing that the critical risk factors are related to the physical overexertion, the uncomfortable postures and the manual lifting of the load. Among the important risks are falling objects, skin contact with toxic substances and mental overwork, closely related to work pressures and job security? It was possible to carry out the proposal of preventive and corrective measures in order to properly manage the risks and contribute to the safety and health of the workers

Avaliação das parametrizações físicas do modelo WRF para a camada limite atmosférica para a região Metropolitana da Grande Vitória.

Este trabalho tem como objetivo principal avaliar o desempenho das diferentes parametrizações físicas da Camada Limite Atmosférica (CLA) disponíveis no modelo meteorológico Weather Research and Forecasting (WRF) 3.6.1., com o fim de identificar qual delas representa melhor as condições meteorológicas da Região Metropolitana da Grande Vitória (RMGV) em dois meses pertences aos dois períodos estacionais mais representativos da região, inverno e verão. Para lograr dito objetivo, foram realizadas 34 simulações, onde 17 ocorreram no período de inverno (07/2010) e 17 para o período de verão (02/2010), com as quais foram avaliadas todas as parametrizações da CLA, excetuando a QNSE (Quasinormal Scale Elimination) e as MYNN (MellorYamada Nakanishi Niino) nível 2.5 e 3, com suas respectivas parametrizações da Camada Limite Superficial (CLS) disponíveis no modelo. Nestas simulações foram utilizados dois domínios aninhados onde o domínio maior tem uma resolução espacial de 5 km, formando um domínio de 5 x 5 km com 49 x 49 células que cobre todo o estado do Espírito Santo, parte do Minas Gerais, Rio de Janeiro e Bahia e o domínio menor tem uma resolução espacial de 1 km, formando um domínio de 1 x 1 km com 120 x 120 células que compreende toda a RMGV. Ambos domínios contam com uma estrutura vertical representada por 21 camadas verticais e encontram-se centrados nas coordenadas 20,25°S e 40,29°W. Foram comparados, utilizando uma série de parâmetros estatísticos, os dados simulados pelo modelo WRF obtidos nas diferentes modelagens com as variáveis meteorológicas de temperatura superficial (2 m), velocidade e direção do vento (10 m) com os dados reais medidos pelas estações pertences a Rede Automática de Monitoramento da Qualidade do Ar (RAMQAr) e o aeroporto da RMGV. Os resultados mostraram que a parametrização que melhor representou os valores das variáveis meteorológicas anteriormente mencionadas para o período de verão foi a parametrização utilizada na modelagem M_1 que corresponde aos esquemas YSU para a CLA e a MM5 melhorado para a CLS, sendo a estação Carapina a que apresenta valores simulados mais pertos aos valores reais observados. Por outro lado, para o período de inverno, a parametrização que melhor representou os valores das variáveis meteorológicas mencionadas foi a parametrização utilizada na modelagem M_12 que corresponde aos esquemas UW para a CLA e a MM5 para a CLS, sendo Cariacica e aeroporto as estações que apresentaram uma acurácia maior entre os dados simulados e os dados reais medidos. Os resultados apresentados por ambas parametrizações mostram que os melhores resultados se apresentam para a velocidade do vento, seguida da temperatura superficial e a direção do vento. Estes resultados sugerem a necessidade de testar as outras parametrizações físicas disponíveis no modelo com o fim de melhorar os resultados das predições das variáveis meteorológicas para a RMGV e assim posteriormente ter melhores resultados no momento de utilizar estes dados em modelos de dispersão

IR Photodissociation Spectroscopy and Theory of Au+(CO)n Complexes: Nonclassical Carbonyls in the Gas Phase

Au+(CO)n complexes are produced in the gas phase via pulsed laser vaporization, expanded in a supersonic jet, and detected with a reflectron time-of-flight mass spectrometer. Complexes up to n = 12 are observed, with mass channels corresponding to the n = 2 and n = 4 showing enhanced intensity. To investigate coordination and structure, individual complexes are mass-selected and probed with infrared photodissociation spectroscopy. Spectra in the carbonyl stretching region are measured for the n = 3−7 species, but no photodissociation is observed for n = 1, 2 due to the strong metal cation-ligand binding. The carbonyl stretch in these systems is blue-shifted 50−100 cm-1 with respect to the free CO vibration (2143 cm-1), providing evidence that these species are so-called “nonclassical” metal carbonyls. Theory at the MP2 and CCSD(T) levels provides structures for these complexes and predicted spectra to compare to the experiment. Excellent agreement is obtained between experiment and theory, establishing that the n = 3 complex is trigonal planar and the n = 4 complex is tetrahedral

Isotopic δ\u3csup\u3e15\u3c/sup\u3eN Signature of Grass-Alone and Grass-Legume Tropical Pastures to Estimate Sources of Nitrogen to Grasses in Farmer Managed Pastures

Vast areas of tropical forest have been converted into pastures sown with introduced grasses (Urochloa spp.). The majority of pastures exist in some stage of degradation, which has dramatic ecological and economic consequences. Our objective was to determine isotopic 15N signature of grass alone and grass-legume pastures to estimate sources of nitrogen (N) to grasses in farmer managed pastures. This work contributes to enhancing the sustainability of tropical pastures in forest margins through the integration of legumes. The overarching hypothesis tested was that legumes associated with grasses will improve nutrient supply via symbiotic fixation and mobilization of soil phosphorus (P) reserves increasing belowground inputs and recycling of carbon (C), N and P. We have done preliminary research in ten paired plots of productive grass-alone vs. grass-legume pastures on farms located in the Caquetá region of Colombia. Pasture productivity and sources of plant N uptake using 15N isotope natural abundance methods have been analysed. The integration of legumes increased biomass production by about 74%, and N and P uptake by two-fold. The legumes derived about 80% of their N via symbiotic fixation, showing the significance of this process to N nutrition despite the acidic soil conditions. The isotopic 15N signature of grasses in grass-alone vs. grass-legume pastures suggested that sources of grass N are affected by pasture composition. Furthermore, low δ15N found in some grass-alone pastures, indicate that other N sources apart from soil mineral N are being exploited. The role of different processes like symbiosis with arbuscular mycorrhiza fungi, biological nitrification inhibition or associative N fixation need to be further studied to provide a more comprehensive interpretation of N exploitation in grass-alone pastures