675 research outputs found
Bulk dynamics for interfacial growth models
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
The collisional rates associated with the isotropic velocity moments
and
are exactly derived in the case of the
inelastic Maxwell model as functions of the exponent , the coefficient of
restitution , and the dimensionality . 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 , 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
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
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
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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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
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.
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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