14,091 research outputs found

    Unidentified Galactic High-Energy Sources as Ancient Pulsar Wind Nebulae in the light of new high energy observations and the new code

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    In a Pulsar Wind Nebula (PWN), the lifetime of inverse Compton (IC) emitting electrons exceeds the lifetime of its progenitor pulsar (as well as its shell-type remnant), but it also exceeds the age of those that emit via synchrotron radiation. Therefore, during its evolution, the PWN can remain bright in IC so that its GeV-TeV gamma-ray flux remains high for timescales much larger (for 10^5 - 10^6 yrs) than the pulsar lifetime and the X-ray PWN lifetime. In this scenario, the magnetic field in the cavity induced by the wind of the progenitor star plays a crucial role. This scenario is in line with the discovery of several unidentified or "dark" sources in the TeV gamma-ray band without X-ray counterparts; and it is also finding confirmation in the recent discoveries at GeV gamma rays. Moreover, these consequences could be also important for reinterpreting the detection of starburst galaxies in the TeV gamma-ray band when considering a leptonic origin of the gamma-ray signal. Both theoretical aspects and their observational proofs will be discussed, as well as the first results of our new modeling code.Comment: Proceedings of the 5th International Symposium on High-Energy Gamma-Ray Astronomy (Gamma2012

    Lorentz-breaking effects in scalar-tensor theories of gravity

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    In this work, we study the effects of breaking Lorentz symmetry in scalar-tensor theories of gravity taking torsion into account. We show that a space-time with torsion interacting with a Maxwell field by means of a Chern-Simons-like term is able to explain the optical activity in syncrotron radiation emitted by cosmological distant radio sources. Without specifying the source of the dilaton-gravity, we study the dilaton-solution. We analyse the physical implications of this result in the Jordan-Fierz frame. We also analyse the effects of the Lorentz breaking in the cosmic string formation process. We obtain the solution corresponding to a cosmic string in the presence of torsion by keeping track of the effects of the Chern-Simons coupling and calculate the charge induced on this cosmic string in this framework. We also show that the resulting charged cosmic string gives us important effects concerning the background radiation.The optical activity in this case is also worked out and discussed.Comment: 10 pages, no figures, ReVTex forma

    Non-collinear coupling between magnetic adatoms in carbon nanotubes

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    The long range character of the exchange coupling between localized magnetic moments indirectly mediated by the conduction electrons of metallic hosts often plays a significant role in determining the magnetic order of low-dimensional structures. In addition to this indirect coupling, here we show that the direct exchange interaction that arises when the moments are not too far apart may induce a non-collinear magnetic order that cannot be characterized by a Heisenberg-like interaction between the magnetic moments. We argue that this effect can be manipulated to control the magnetization alignment of magnetic dimers adsorbed to the walls of carbon nanotubes.Comment: 13 pages, 5 figures, submitted to PR

    Time programmable smart devices for peak demand reduction of smart homes in a microgrid

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    Abstract: Increasing electricity access through Microgrids for rural areas is often faced with the challenge of increased peak demand through increased electricity demand as more electronic devices will be acquired by the consumers and more small businesses will spring up in the community. If not taken care of, this leads to additional cost of incurring higher peaker plants to meet the peak demand, and the burden of the cost of peaker plants are consequentially transferred to the consumers. Since this load is generated by the consumers, it is most desirable to control the peak demand from the consumers’ side. Therefore, a method of Time Programmable Smart Devices (TPSD) with an efficient Electricity Use Plan (EUP) is proposed in this paper by introducing appliance working knowledge and improving load shifting technique of Demand Side Management for peak demand reduction in a rural Microgrid. This method yielded lower morning and evening peaks, a lower peak-to-peak difference than those available in literature, and a peak period shift from the traditional peak period to traditional off-peak period. These lead to financial savings, reduced cost of peaker plants and a safer environment from less greenhouse gases emissions

    Asymmetric exclusion model with several kinds of impurities

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    We formulate a new integrable asymmetric exclusion process with N1=0,1,2,...N-1=0,1,2,... kinds of impurities and with hierarchically ordered dynamics. The model we proposed displays the full spectrum of the simple asymmetric exclusion model plus new levels. The first excited state belongs to these new levels and displays unusual scaling exponents. We conjecture that, while the simple asymmetric exclusion process without impurities belongs to the KPZ universality class with dynamical exponent 3/2, our model has a scaling exponent 3/2+N13/2+N-1. In order to check the conjecture, we solve numerically the Bethe equation with N=3 and N=4 for the totally asymmetric diffusion and found the dynamical exponents 7/2 and 9/2 in these cases.Comment: to appear in JSTA

    Fontes de crescimento das exportações de castanha-do-brasil (1970-1988).

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    Effective energy consumption scheduling in smart homes

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    Abstract: Monthly expenditure on electricity by most households in South Africa take beyond acceptable percentage of their income. In order to keep the household energy expenditure below the energy poverty threshold, a daily electricity optimization problem is formulated using mixed integer linear programming (MILP) method. The energy optimization scheduling was carried out by a device called the Daily Maximum Energy Scheduling (DMES) device proposed to be incorporated into smart meters of households. The DMES algorithm was tested with household data set and was shown to be capable of ensuring that households spend less than 10% of their income on electricity bill monthly. This technique therefore, would be beneficial to consumers (for better financial savings and planning), utility (for effective energy and financial savings, and energy network planning) and cleaner environments as proposed for smart grid. Also, number of households in the nation living below the energy expenditure-based poverty threshold would increase

    Erratum to: Quantitative physiology and elemental composition of Kluyveromyces lactis CBS 2359 during growth on glucose at different specific growth rates

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    In the original publication of the article, the below mentioned errors have appeared. The correct text is provided in this erratum. In the abstract section, the sentence ‘‘This dataset serve’’ should be replaced as ‘‘This dataset serves’’. Also, the reference ‘‘Basso TO, Gomes FS, Lopes ML, et al (2014) Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation.Antonie Van Leeuwenhoek105:169–177. doi:10.1007/s10482-013-0063-6’’ should be replaced as ‘‘Basso TO, Dario MG, Tonso A, Stambuk BU, GombertAK(2010)Insufficienturacilsupplyinfullyaerobic chemostat cultures of Saccharomyces cerevisiae leads torespiro-fermentative metabolism anddouble nutrientlimitation. Biotechnol Lett 32:973–977. doi: 10.1007/ s10529-010-0248-2’’. Finally, in the Table 2 footnote, ‘‘according to (Heijnen 1981)’’ should be replaced as ‘‘according to Heijnen (1981)’’.info:eu-repo/semantics/publishedVersio

    Quantitative physiology and elemental composition of Kluyveromyces lactis CBS 2359 during growth on glucose at different specific growth rates

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    The yeast Kluyveromyces lactis has received attention both from academia and industry due to some important features, such as its capacity to grow in lactose-based media, its safe status, its suitability for large-scale cultivation and for heterologous protein synthesis. It has also been considered as a model organism for genomics and metabolic regulation. Despite this, very few studies were carried out hitherto under strictly controlled conditions, such as those found in a chemostat. Here we report a set of quantitative physiological data generated during chemostat cultivations with the K. lactis CBS 2359 strain, obtained under glucose-limiting and fully aerobic conditions. This dataset serve as a basis for the comparison of K. lactis with the model yeast Saccharomyces cerevisiae in terms of their elemental compositions, as well as for future metabolic flux analysis and metabolic modelling studies with K. lactis.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. T.O.B. would like to express his gratitude for funds provided by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brasília, Brazil).info:eu-repo/semantics/publishedVersio
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