675 research outputs found

    Bulk dynamics for interfacial growth models

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    We study the influence of the bulk dynamics of a growing cluster of particles on the properties of its interface. First, we define a {\it general bulk growth model} by means of a continuum Master equation for the evolution of the bulk density field. This general model just considers arbitrary addition of particles (though it can be easily generalized to consider substraction) with no other physical restriction. The corresponding Langevin equation for this bulk density field is derived where the influence of the bulk dynamics is explicitly shown. Finally, when it is assumed a well-defined interface for the growing cluster, the Langevin equation for the height field of this interface for some particular bulk dynamics is written. In particular, we obtain the celebrated Kardar-Parisi-Zhang (KPZ) equation. A Monte Carlo simulation illustrates the theoretical results.Comment: 6 pages, 2 figure

    Collisional rates for the inelastic Maxwell model: application to the divergence of anisotropic high-order velocity moments in the homogeneous cooling state

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    The collisional rates associated with the isotropic velocity moments andtheanisotropicmoments and the anisotropic moments and are exactly derived in the case of the inelastic Maxwell model as functions of the exponent rr, the coefficient of restitution α\alpha, and the dimensionality dd. The results are applied to the evolution of the moments in the homogeneous free cooling state. It is found that, at a given value of α\alpha, not only the isotropic moments of a degree higher than a certain value diverge but also the anisotropic moments do. This implies that, while the scaled distribution function has been proven in the literature to converge to the isotropic self-similar solution in well-defined mathematical terms, nonzero initial anisotropic moments do not decay with time. On the other hand, our results show that the ratio between an anisotropic moment and the isotropic moment of the same degree tends to zero.Comment: 7 pages, 2 figures; v2: clarification of some mathematical statements and addition of 7 new references; v3: Published in "Special Issue: Isaac Goldhirsch - A Pioneer of Granular Matter Theory

    Viability of competing field theories for the driven lattice gas

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    It has recently been suggested that the driven lattice gas should be described by a novel field theory in the limit of infinite drive. We review the original and the new field theory, invoking several well-documented key features of the microscopics. Since the new field theory fails to reproduce these characteristics, we argue that it cannot serve as a viable description of the driven lattice gas. Recent results, for the critical exponents associated with this theory, are re-analyzed and shown to be incorrect.Comment: 4 pages, revtex, no figure

    Physical activity, chronic kidney disease, and cardiovascular risk: A study in half a million adults

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    Objective: There is a growing prevalence of chronic kidney disease (CKD), a con- dition associated with a higher cardiovascular disease (CVD) risk. We assessed the association between self-reported physical activity (PA) and CKD and also studied whether PA attenuates CKD-associated CVD risk. Methods: A cohort of Spanish adults (18–64 years) participated in this nation- wide study. Participants were categorized at baseline as being either inactive (per- forming no PA), regularly, or insufficiently active (meeting or not, respectively, international PA recommendations) and were followed for up to 5 years. The presence of CKD (estimated glomerular filtration rate <60 mL/min/1.73 m2) and major CVD risk factors (diabetes, hypercholesterolemia, hypertension, obesity) was determined at baseline and at follow- up. Results: 517 917 participants (44 ± 9 years, 67% male, CKD prevalence = 7%) were studied at baseline, with prospective analyses (median follow-up = 2 years, range = 2–5) in a subcohort of 264 581 individuals. Compared to physical inactiv- ity, cross-sectional analyses at baseline showed that regular PA (odds ratio = 0.80; 95% confidence interval = 0.79–0.81), but not insufficient PA (1.02; 0.99–1.04) was associated with lower CKD prevalence. However, prospective analyses failed to confirm this association (p > 0.1). In turn, CKD was associated with a higher prev- alence of hypertension (+3%) and diabetes (+5%) at baseline and with a greater incidence of hypertension at follow-up (+37%). Among those participants with CKD, regular PA was associated with a lower prevalence (−45% to −7%) and in- cidence (−38% to −4%) of all CVD risk factors. Conclusion: Although PA might not reduce incident CKD in the middle term (~2 years), it can attenuate the CVD risk linked to this condition.Federación Española de Enfermedades Raras (España) Ministerio de Economía y Competitividad (España) Instituto de Salud Carlos III (España)10 página

    Exploring the versatile uses of triplet states: working principles, limitations, and recent progress in phosphorescence, TADF, and TTA

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    Triplet excited states in organic semiconductors are usually optically dark and long-lived as they have a spin-forbidden transition to the singlet ground state and therefore hinder processes in light-harvesting applications. Also, triplets often cause damage to the system as they can sensitize the formation of reactive singlet oxygen. Despite these unfavorable characteristics, there exist mechanisms through which we can utilize triplet states, and that constitutes the scope of this review. Commencing with an introductory short exploration of the triplet state problem, we proceed to elucidate the principal mechanisms underpinning the utilization of triplet states in organic materials: 1. Phosphorescence (PH), 2. Thermally Activated Delayed Fluorescence (TADF), and 3. Triplet-Triplet Annihilation (TTA). In each section we unveil their working principles, highlight their vast range of applications, and discuss their limitations and perspectives. We dedicate special attention to the use of these mechanisms in organic light-emitting diodes (OLEDs), given that OLEDs represent the most thriving commercial application of organic semiconductors. This review aims to provide readers with insights and opportunities to engage with and contribute to the study of photophysical properties and device physics of organic semiconductors, especially regarding harnessing the potential of triplet states

    Echovirus 13 Aseptic Meningitis, Brazil

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    Submitted by Sandra Infurna ([email protected]) on 2020-01-18T20:09:46Z No. of bitstreams: 1 GinaSantos_EdsonSilva_etal_IOC_2006.pdf: 32987 bytes, checksum: b6c0677ec11f3eeff049ee0da3872d2d (MD5)Approved for entry into archive by Sandra Infurna ([email protected]) on 2020-01-18T20:16:41Z (GMT) No. of bitstreams: 1 GinaSantos_EdsonSilva_etal_IOC_2006.pdf: 32987 bytes, checksum: b6c0677ec11f3eeff049ee0da3872d2d (MD5)Made available in DSpace on 2020-01-18T20:16:41Z (GMT). No. of bitstreams: 1 GinaSantos_EdsonSilva_etal_IOC_2006.pdf: 32987 bytes, checksum: b6c0677ec11f3eeff049ee0da3872d2d (MD5) Previous issue date: 2006Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Secretaria Municipal de Saúde do Rio Grande do Sul. Rio Grande, RS, Brasil.Instituto de Pesquisas Biológicas. Rio Grande, RS, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil

    Malware Distributed Collection And Pre-classification System Using Honeypot Technology

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    Malware has become a major threat in the last years due to the ease of spread through the Internet. Malware detection has become difficult with the use of compression, polymorphic methods and techniques to detect and disable security software. Those and other obfuscation techniques pose a problem for detection and classification schemes that analyze malware behavior. In this paper we propose a distributed architecture to improve malware collection using different honeypot technologies to increase the variety of malware collected. We also present a daemon tool developed to grab malware distributed through spam and a pre-classification technique that uses antivirus technology to separate malware in generic classes. © 2009 SPIE.7344Grossman, J., Niedzialkowski, T.C., Hacking Intranet Websites from the Outside - Javascript malware just got a lot more dangerous (2006) Black Hat, , http://www.blackhat.com/presentations/bhusa-06/BH-US-06-Grossman.pdf, USA, Las Vegas, Available atWhitehouse, O., An Analysis of Address Space Layout Randomization on Windows Vista (2007) Symantec Advanced Threat Research, , http://www.symantec.com/avcenter/reference/Address-Space-Layout-Randomization.pdf, White paper available atWhitehouse, O., Analysis of GS Protections in Microsoft Windows Vista (2007) Symantec Advanced Threat Research, , http://www.symantec.com/avcenter/reference/GS-Protections-in-Vista.pdf, White paper available atMcDermott, J., Fox, C., Using abuse cases models for security requirement analysis (1999) Proceedings of the 15th Annual Computer Security Applications Conference, p. 55. , IEEE Computer Society, ISBN:0-7695-0346-2Collection, , http://Nepenthes.carnivore.it, Available at:, Accessed on January 2009Baecher, P., The Nepenthes Platform: An Efficient Approach to Collect Malware (2006) Recent Advances in Intrusion Detection, pp. 165-184. , Springer Berlin, HeidelbergHoneytrap, , http://honeytrap.mwcollect.org, Available at:, Accessed on January 2009Zhuge, J., Holz, T., Han, X., Song, C., Zou, W., Collecting Autonomous Spreading Malware Using Highinteraction Honeypots (2007) Proceedings of 9th International Conference on Information and Communications Security (ICICS'07), , Zhengzhou, China, DecemberProvos, N., Holz, T., (2007) Virtual Honeypots: From Botnet Tracking to Intrusion Detection, , Addison Wesley, ISBN: 0-321-33632-1Seifert, C., Welch, I., Komisarczuk, P., HoneyC - The Low-Interaction Client Honeypot (2007) Proceedings of the 2007 NZCSRCS, , Waikato University, Hamilton, New Zealand, AprilNazario, J., Phoneyc, , http://svn.carnivore.it/browser/phoneyc, Accessed on January 2009Seifert, C., Steenson, R., Holz, T., Yuan, B., Davis, M.A., Know Your Enemy: Malicious Web Servers, , http://www.honeynet.org/papers/mws, Available at:, Accessed on January 2009Spitzner, L., (2002) Honeypots: Tracking Hackers, , Addison Wesley, ISBN: 0-321-10895-1http://www.honeypots-alliance.org.br, Brazilian Honeypots Alliance, Distributed Honeypots Project. Available at:, Accessed on January 200

    Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

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    The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun
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