2,711 research outputs found

    Entropy, time irreversibility and Schroedinger equation in a primarily discrete space-time

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    In this paper we show that the existence of a primarily discrete space-time may be a fruitful assumption from which we may develop a new approach of statistical thermodynamics in pre-relativistic conditions. The discreetness of space-time structure is determined by a condition that mimics the Heisenberg uncertainty relations and the motion in this space-time model is chosen as simple as possible. From these two assumptions we define a path-entropy that measures the number of closed paths associated with a given energy of the system preparation. This entropy has a dynamical character and depends on the time interval on which we count the paths. We show that it exists an like-equilibrium condition for which the path-entropy corresponds exactly to the usual thermodynamic entropy and, more generally, the usual statistical thermodynamics is reobtained. This result derived without using the Gibbs ensemble method shows that the standard thermodynamics is consistent with a motion that is time-irreversible at a microscopic level. From this change of paradigm it becomes easy to derive a H−theoremH-theorem. A comparison with the traditional Boltzmann approach is presented. We also show how our approach can be implemented in order to describe reversible processes. By considering a process defined simultaneously by initial and final conditions a well defined stochastic process is introduced and we are able to derive a Schroedinger equation, an example of time reversible equation.Comment: latex versio

    Erratum to: An Entropy Functional for Riemann-Cartan Space-Times

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    We correct the entropy functional constructed in Int. J. Theor. Phys. 51:362 (2012). The 'on-shell' functional one obtains from this correct functional possesses a holographic structure without imposing any constraint on the spin-angular momentum tensor of matter, in contrast to the conclusion made in the above paper.Comment: 15 pages. These are the preprints of the original paper and its erratum published in Int. J. Theor. Phy

    Crystal structure of 4,6-di­methyl-2-{[3,4,5-trihy­dr­oxy-6-(hy­dr­oxy­meth­yl)tetra­hydro-2H-pyran-2-yl]sulfan­yl}nicotino­nitrile

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    In the title compound, C14H18N2O5S, the C—S bond lengths are unequal, with S—Cglucose = 1.8016 (15) Å and S—Cpyrid­yl = 1.7723 (13) Å. The hydro­philic glucose residues lie in the regions z ≃ 0.25 and 0.75. Four classical hydrogen bonds link the mol­ecules to form layers parallel to the ab plane, from which the pyridyl rings project; pyridyl ring stacking parallel to the a axis links adjacent layers

    A haystack full of needles: scalable detection of IoT devices in the wild

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    Consumer Internet of Things (IoT) devices are extremely popular, providing users with rich and diverse functionalities, from voice assistants to home appliances. These functionalities often come with significant privacy and security risks, with notable recent large scale coordinated global attacks disrupting large service providers. Thus, an important first step to address these risks is to know what IoT devices are where in a network. While some limited solutions exist, a key question is whether device discovery can be done by Internet service providers that only see sampled flow statistics. In particular, it is challenging for an ISP to efficiently and effectively track and trace activity from IoT devices deployed by its millions of subscribers --all with sampled network data. In this paper, we develop and evaluate a scalable methodology to accurately detect and monitor IoT devices at subscriber lines with limited, highly sampled data in-the-wild. Our findings indicate that millions of IoT devices are detectable and identifiable within hours, both at a major ISP as well as an IXP, using passive, sparsely sampled network flow headers. Our methodology is able to detect devices from more than 77% of the studied IoT manufacturers, including popular devices such as smart speakers. While our methodology is effective for providing network analytics, it also highlights significant privacy consequences

    On a (\beta,q)-generalized Fisher information and inequalities involving q-Gaussian distributions

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    In the present paper, we would like to draw attention to a possible generalized Fisher information that fits well in the formalism of nonextensive thermostatistics. This generalized Fisher information is defined for densities on Rn.\mathbb{R}^{n}. Just as the maximum R\'enyi or Tsallis entropy subject to an elliptic moment constraint is a generalized q-Gaussian, we show that the minimization of the generalized Fisher information also leads a generalized q-Gaussian. This yields a generalized Cram\'er-Rao inequality. In addition, we show that the generalized Fisher information naturally pops up in a simple inequality that links the generalized entropies, the generalized Fisher information and an elliptic moment. Finally, we give an extended Stam inequality. In this series of results, the extremal functions are the generalized q-Gaussians. Thus, these results complement the classical characterization of the generalized q-Gaussian and introduce a generalized Fisher information as a new information measure in nonextensive thermostatistics.Comment: v2: corrected equation (A5

    Avaliação da resistência ao cisalhamento da união entre duas ligas a base de CoCr e uma cerâmica

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    INTRODUCTION: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum) combined with Omega 900 ceramic (Vita Zahnfabrik). MATERIAL and METHOD: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer’s recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC), with the aid of a device developed for such intention, and constant speed of 0.5mm/min. RESULTS and CONCLUSIONS: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys. ______________________________________________________________________________________________________________ RESUMOINTRODUÇÃO: Baseados na importância da integridade da interface metal-cerâmica, este trabalho tem como objetivo avaliar a resistência ao cisalhamento da união metal-cerâmica de duas ligas de Co-Cr (Wirobond C, Bego; Remanium 2000, Dentaurum) combinadas com a cerâmica Omega 900 (Vita Zahnfabrik). MATERIAIS E MÉTODOS: Foram confeccionados 11 corpos-de-prova cilíndricos para cada liga utilizada, sendo que a porção metálica foi obtida por fundição pela técnica da cera perdida, através de enceramentos padronizados com 4mm de altura por 4mm de diâmetro. A aplicação da cerâmica foi realizada segundo recomendações do fabricante, com auxílio de uma matriz de teflon que permitia sua padronização com as mesmas dimensões da porção metálica. Os corpos-de-prova foram submetidos ao ensaio de resistência ao cisalhamento em máquina de ensaios universal (EMIC), com auxílio de dispositivo desenvolvido para tal propósito, sob velocidade constante de 0,5mm/ min. RESULTADOS E CONCLUSÕES: As médias de resistência obtidas foram 48,387 MPa para a liga Wirobond C, com desvio padrão de 17,718, e 55,956 MPa para a Remanium 2000, com desvio padrão de 17,198. Após análise de variância foi possível observar que não há diferença estatisticamente significante entre os valores de resistência ao cisalhamento das duas ligas metalocerâmicas

    The Data Quality Monitoring for the CMS Silicon Strip Tracker

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    The CMS Silicon Strip Tracker (SST), consisting of more than 10 million channels, is organized in about 15,000 detector modules and it is the largest silicon strip tracker ever built for high energy physics experiments. The Data Quality Monitoring system for the Tracker has been developed within the CMS Software framework. More than 100,000 monitorable quantities need to be managed by the DQM system that organizes them in a hierarchical structure reflecting the detector arrangement in subcomponents and the various levels of data processing. Monitorable quantities computed at the level of individual detectors are processed to extract automatic quality checks and summary results that can be visualized with specialized graphical user interfaces. In view of the great complexity of the CMS Tracker detector the standard visualization tools based on histograms have been complemented with 2 and 3 dimensional graphical images of the subdetector that can show the whole detector down to single channel resolution. The functionalities of the CMS Silicon Strip Tracker DQM system and the experience acquired during the SST commissioning will be described

    Tillage versus no-tillage. soil properties and hydrology in an organic persimmon farm in eastern Iberian Peninsula

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    There is an urgent need to implement environmentally friendly agriculture management practices to achieve the Sustainable Goals for Development (SDGs) of the United Nations by 2030. Mediterranean agriculture is characterized by intense and millennia-old tillage management and as a consequence degraded soil. No-Tillage has been widely examined as a solution for soil degradation but No-Tillage relies more on the application of herbicides that reduce plant cover, which in turn enhances soil erosion. However, No-Tillage with weed cover should be researched to promote organic farming and sustainable agriculture. Therefore, we compare Tillage against No-Tillage using weed cover as an alternative strategy to reduce soil losses in persimmon plantations, both of them under organic farming management. To achieve these goals, two plots were established at "La Canyadeta" experimental station on 25-years old Persimmon plantations, which are managed with Tillage and No-Tillage for 3 years. A survey of the soil cover, soil properties, runoff generation and initial soil losses using rainfall simulation experiments at 55 mm h-1 in 0.25 m2 plot was carried out. Soils under Tillage are bare (96.7%) in comparison to the No-Tillage (16.17% bare soil), with similar organic matter (1.71 vs. 1.88%) and with lower bulk densities (1.23 vs. 1.37 g cm3). Tillage induces faster ponding (60 vs. 92 s), runoff (90 vs. 320 s) and runoff outlet (200 vs. 70 s). The runoff discharge was 5.57 times higher in the Tillage plots, 8.64 for sediment concentration and 48.4 for soil losses. We conclude that No-tillage shifted the fate of the tilled field after 3 years with the use of weeds as a soil cover conservation strategy. This immediate effect of No-Tillage under organic farming conditions is very promising to achieve the SDGs

    Insights into the role of natural products in the control of the honey bee gut parasite (Nosema spp.)

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    The honey bee is an important economic insect due to its role in pollinating many agricultural plants. Unfortunately, bees are susceptible to many pathogens, including pests, parasites, bacteria, and viruses, most of which exert a destructive impact on thousands of colonies. The occurrence of resistance to the therapeutic substances used against these organisms is rising, and the residue from these chemicals may accumulate in honey bee products, subsequently affecting the human health. There is current advice to avoid the use of antibiotics, antifungals, antivirals, and other drugs in bees, and therefore, it is necessary to develop alternative strategies for the treatment of bee diseases. In this context, the impact of nosema diseases (nosemosis) on bee health and the negative insults of existing drugs are discussed. Moreover, attempts to combat nosema through the use of alternative compounds, including essential oils, plant extracts, and microbes in vitro and in vivo, are documented.Plan of High end Foreign Experts of the Ministry of Science and Technology | Ref. G2022016009
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