4,596 research outputs found
OS diversity for intrusion tolerance: Myth or reality?
One of the key benefits of using intrusion-tolerant systems is the possibility of ensuring correct behavior in the presence of attacks and intrusions. These security gains are directly dependent on the components exhibiting failure diversity. To what extent failure diversity is observed in practical deployment depends on how diverse are the components that constitute the system. In this paper we present a study with operating systems (OS) vulnerability data from the NIST National Vulnerability Database. We have analyzed the vulnerabilities of 11 different OSes over a period of roughly 15 years, to check how many of these vulnerabilities occur in more than one OS. We found this number to be low for several combinations of OSes. Hence, our analysis provides a strong indication that building a system with diverse OSes may be a useful technique to improve its intrusion tolerance capabilities
Infantile Cystinosis
Infantile cystinosis is a rare disorder which leftuntreated results in end -stage renal disease early in life. Together with dehydration and electrolyte imbalance
due to renal tubular Fanconi syndrome, endstage renal disease used to be the leading cause of death in children with cystinosis. Specific therapy with cysteamine (cystine -depleting agent) has changed the course of this disease. Instead of being
fatal in childhood, it can nowadays be considered a multisystemic adult disorder. The authors report a case of a child diagnosed with Fanconi syndrome at 14 months of age and infantile cystinosis at 19
months of age in whom oral cysteamine treatment led to a good outcome during childhood
Imunodeficiência Combinada Grave – O Diagnóstico Precoce é Importante?
Introdução: Os doentes com Imunodeficiência Combinada Grave (SCID) não diagnosticados evoluem inexoravelmente para a morte no primeiro ano de vida. Um elevado índice de suspeição é fundamental para o diagnóstico precoce, o factor mais importante para a sobrevida destas crianças.
Objectivo: Apresentam-se três casos clínicos ilustrativos da importância da precocidade
diagnóstica no prognóstico final.
Casos clínicos: Caso clínico 1: Lactente do sexo masculino, com antecedentes de
infecções respiratórias de repetição, internado aos sete meses na UCIP do HDE por
pneumonia a Adenovírus com insuficiência respiratória. Necessitou de ventilação
mecânica e de duas transfusões de concentrado eritrocitário na primeira semana de internamento. Teve exantema exuberante, interpretado como toxidermia. Evoluiu para
doença pulmonar sequelar grave. Aos nove meses foi feito o diagnóstico de SCID
hipomorfa com doença do enxerto contra o hospedeiro pós-transfusional, controlada
com imunossupressão (ciclosporina e glucocorticoides). Não foi transplantado com
células progenitoras hematopoiéticas por não reunir condições clínicas. Na sequência de
uma intercorrência respiratória veio a falecer aos 14 meses. Caso clínico 2: Lactente do sexo masculino, internado aos 6 meses no HDE por pneumonia intersticial
hipoxemiante. Isolado P. jiroveci no lavado bronco-alveolar e feito o diagnóstico
presuntivo de BCGite disseminado em criança com SCID T-B+NK-. Após estabilização
clínica e esplenectomia foi transplantado com células progenitoras hematopoiéticas de
dador fenoidêntico não aparentado. Dada a BCGite disseminada necessitou de vários
ciclos de infusão de células do dador para uma reconstituição imunitária lenta e
progressiva. Seis meses pós-transplante está clinicamente bem, com quimerismo
linfóide T e NK completo. Caso clínico 3: Lactente do sexo masculino, internado aos
17 dias de vida por infecção respiratória alta e bacteriémia a M. catarrhalis. Reinternado quinze dias depois por sépsis a MRSA e linfopénia. A avaliação efectuada
permitiu o diagnóstico de SCID T-B+NK- por defeito na cadeia gamma comum.
Transplantado com células progenitoras hematopoiéticas de dador genoidêntico aos 4
meses, sem condicionamento. Clinicamente bem, seis meses pós-transplante, com
reconstituição imunitária satisfatória.
Conclusão: Esta doença tem uma prevalência não negligenciável e apenas com elevado
indice de suspeição se pode estabelecer um plano de tratamento eficaz
Strategic thinking: The construction and validation of an instrument
The lack of instruments that evaluate strategic thinking and the fact that it is positively related to high levels of professional performance has led us to the development and validation of a questionnaire that allows us to measure it in an organizational context. This was done through three studies. First an exploratory study, in which 272 Human Resources (HR) professionals participated, allowed us to develop its items and analyze its psychometric properties. From it three factors were extracted: (1) systemic thinking, (2) vision towards the future and, (3) identification of new opportunities. Also, the results indicated the existence of a latent overall model of strategic thinking. Secondly, a confirmatory study, where 352 Human Resources professionals participated, intended to validate the results of the previous study. The same three factors, and a latent factor were replicated revealing that the model presented had an excellent adjustment. Furthermore, a third study was carried out in order to study the perceived relationship between strategic thinking, satisfaction, trust and customers’ retention. This study counted with the participation of 273 professionals who held positions of middle and upper management, key employees regarding the use of ST in organizations. The results of the three studies allow us to conclude that the Strategic Thinking Questionnaire is a valid instrument to analyze strategic thinking.info:eu-repo/semantics/publishedVersio
Supersymmetrization of the Radiation Damping
We construct a supersymmetrized version of the model to the radiation damping
\cite{03} introduced by the present authors \cite{ACWF}. We dicuss its
symmetries and the corresponding conserved Noether charges. It is shown this
supersymmetric version provides a supersymmetric generalization of the Galilei
algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action
can be splited into dynamically independent external and internal sectors.Comment: 9 page
Metastability and Nucleation for the Blume-Capel Model. Different mechanisms of transition
We study metastability and nucleation for the Blume-Capel model: a
ferromagnetic nearest neighbour two-dimensional lattice system with spin
variables taking values in -1,0,+1. We consider large but finite volume, small
fixed magnetic field h and chemical potential "lambda" in the limit of zero
temperature; we analyze the first excursion from the metastable -1
configuration to the stable +1 configuration. We compute the asymptotic
behaviour of the transition time and describe the typical tube of trajectories
during the transition. We show that, unexpectedly, the mechanism of transition
changes abruptly when the line h=2*lambda is crossed.Comment: 96 pages, 44 tex-figures, 7 postscript figure
Hamiltonian symplectic embedding of the massive noncommutative U(1) Theory
We show that the massive noncommutative U(1) theory is embedded in a gauge
theory using an alternative systematic way, which is based on the symplectic
framework. The embedded Hamiltonian density is obtained after a finite number
of steps in the iterative symplectic process, oppositely to the result proposed
using the BFFT formalism. This alternative formalism of embedding shows how to
get a set of dynamically equivalent embedded Hamiltonian densities.Comment: 16 pages, no figures, revtex4, corrected version, references
additione
Design of nano- and microfiber combined scaffolds by electrospinning of collagen onto starch-based fiber meshes : a man-made equivalent of natural extracellular matrix
Mimicking the structural organization and biologic function of natural extracellular matrix has been one of the
main goals of tissue engineering. Nevertheless, the majority of scaffolding materials for bone regeneration
highlights biochemical functionality in detriment of mechanical properties. In this work we present a rather
innovative construct that combines in the same structure electrospun type I collagen nanofibers with starchbased
microfibers. These combined structures were obtained by a two-step methodology and structurally consist
in a type I collagen nano-network incorporated on a macro starch-based support. The morphology of the
developed structures was assessed by several microscopy techniques and the collagenous nature of the nanonetwork
was confirmed by immunohistochemistry. In addition, and especially regarding the requirements of
large bone defects, we also successfully introduced the concept of layer by layer, as a way to produce thicker
structures. In an attempt to recreate bone microenvironment, the design and biochemical composition of the
combined structures also envisioned bone-forming cells and endothelial cells (ECs). The inclusion of a type I
collagen nano-network induced a stretched morphology and improved the metabolic activity of osteoblasts.
Regarding ECs, the presence of type I collagen on the combined structures provided adhesive support and
obviated the need of precoating with fibronectin. It was also importantly observed that ECs on the nano-network
organized into circular structures, a three-dimensional arrangement distinct from that observed for osteoblasts
and resembling the microcappillary-like organizations formed during angiogenesis. By providing simultaneously
physical and chemical cues for cells, the herein-proposed combined structures hold a great potential in
bone regeneration as a man-made equivalent of extracellular matrixK. Tuzlakoglu and M. I. Santos thank the Portuguese Foundation for Science and Technology for their Ph.D. scholarship (SFRH/BD/8502/2002 and SFRH/BD/13428/2003). This work was partially supported by FCT Foundation for Science and Technology, through funds from the POCTI and/or FEDER programs and by the European Union funded STREP Project HIPPOCRATES (NMP3-CT-2003-505758). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283). Work developed under the cooperation agreement between UM-3B's research group and the Hospital de S. Marcos, Braga. The authors thank to L. Goreti Pinto for her help on confocal microscopy studies
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