Impacto do robustecimento de sistemas no desempenho de serviços Internet

O recurso a medidas preventivas, no âmbito da Segurança de Sistemas Informáticos, tem uma importância cada vez maior. Neste contexto, os mecanismos do tipo Role-Based Access Control - RBAC representam uma das abordagens mais promissoras. Todavia, para que sejam largamente aceites, é desejável que: i) tenham um impacto reduzido no desempenho dos sistemas e aplicações, ii) sejam escaláveis e iii) sejam facilmente administráveis. Para além da abordagem RBAC, existem outros mecanismos complementares, para a detecção e contenção de erros. Por exemplo, mecanismos como o - PAX intervêm ao nível da gestão de memória efectuada pelo núcleo do sistema operativo, tornando um sistema virtualmente imune a situações do tipo buffer overflow. Neste artigo descreve-se uma aplicação (e respectiva avaliação) do mecanismo RBAC da plataforma grsecurity, baseado em listas de controle de acesso (ACLs), em conjunção com a plataforma PAX. Em traços gerais, e para a gama de testes utilizada, concluímos que, para serviços nos quais a memória é partilhada entre os vários fios de execução que fazem o atendimento dos pedidos, o impacto do hardening no desempenho dos serviços é mínimo; já em situações em que a memória não é partilhada, a intervenção dos mecanismos de validação PAX torna-se evidente, prejudicando o desempenho global dos serviços

Characterization of Fungal Melanins from Black Stains on Paper Artefacts

This work was supported by Portuguese funds from FCT/MCTES through the CleanART research project (PTDC/EPH-PAT/0224/2014); the Associate Laboratory for Green Chemistry— LAQV (UIDB/50006/2020 and UIDP/50006/2020); the i3N Associate Laboratory and PTNMR (POCI01-0145-FEDER-007688; UIDB/50025/2020-2023, ROTEIRO/0031/2013–PINFRA/22161/2016); the iMed.ULisboa (UIDB/04138/2020), the fellowship number SFRH/BD/133447/2017 (T.G.P.) and the researcher contracts CEECIND/01474/2018 (S.O.S.) and 2021.03255.CEECIND (M.C.C).Melanins play a fundamental role in the biology and ecology of several fungal species. Unfortunately, this group of amorphous macromolecules also severely (and most times irreversibly) stains cultural heritage objects. Despite efforts made throughout the years, knowledge of the chemical composition and structure of melanins is still insufficient, which hampers the task of safely cleaning these colourants from cultural heritage materials in a targeted way without causing further deterioration. This work aimed therefore to contribute towards enlightening the characteristics of fungal melanins from three fungi that are common paper colonizers: Aspergillus niger, Chaetomium globosum and Cladosporium cladosporioides. The extracted melanins were characterized by FTIR, Raman, UV-vis, Solid-State NMR and MALDI-TOF MS spectroscopies and the effect of inhibitors of DHN-melanin and DOPA-melanin pathways on colony pigmentation and growth was evaluated. Although all the extracted colourants show a predominantly aromatic structure with carbonyl and phenolic groups, some differences between the melanins can be highlighted. Melanins obtained from Ch. globosum and Cl. cladosporioides exhibited similar structures and composition and both presented DHN-melanin characteristics, while A. niger’s melanins revealed a more complex and ordered structure, with a higher prevalence of highly conjugated carbonyls than the others, besides the additional presence of a yellow/green component. These conclusions cannot be overlooked while selecting targeted cleaning methodologies for melanin stains on cultural heritage materials.publishersversionpublishe

The influence of the coaches’ demographics on young swimmers’ performance and technical determinants

The purpose of this study was to understand the relationship between the coaches’ demographics (academic degree and/or coaching level and/or coaching experience) and young swimmers’ performance and technical ability. The sample was composed by 151 young swimmers (75 boys and 76 girls: 13.02 1.19 years old, 49.97 8.77 kg of body mass, 1.60 0.08 m of height, 1.66 0.09 m of arm span), from seven different clubs. Seven coaches (one per club) were responsible for the training monitoring. Performance and a set of biomechanical variables related to swim technique and efficiency were assessed. The swimmers’ performance was enhanced according to the increase in the coaches’ academic degree (1: 75.51 10.02 s; 2: 74.55 9.56 s; 3: 73.62 7.64 s), coaching level (1: 76.79 11.27 s; 2: 75.06 9.31 s; 3: 73.65 8.43 s), and training experience ( 5-y training experience: 75.44 9.57 s; >5- y training experience: 74.60 9.54 s). Hierarchical linear modeling retained all coaches’ demographics characteristics as main predictors (being the academic degree the highest: estimate = -1.51, 95% confidence interval = -0.94 to -2.08, p = 0.014). Hence, it seems that an increase in the demographics of the coaches appears to provide them with a training perspective more directed to the efficiency of swimming. This also led to a higher performance enhancementThis work was supported by the National Funds (FCT – Portuguese Foundation for Science and Technology) under the project UIDB/DTP/04045/2020.info:eu-repo/semantics/publishedVersio

Molecular Interactions in Ionic Liquids: The NMR Contribution towards Tailored Solvents

Ionic liquids have been on the spotlight of chemical research field in the last decades. Their physical properties (low vapor pressure, thermal stability, and conductivity) and the possibility of fine tuning make them a versatile class of compounds for a wide range of applications, such as catalysis, energy, and material sciences. Ionic liquids can establish multiple intermolecular interactions with solutes such as electrostatic, van der Waals, or hydrogen bonds. The prospect of designing ionic liquid structures toward specific applications has attracted the attention to these alternative solvents. However, their rational design demands a molecular detailed view, and Nuclear Magnetic Resonance is a unique and privileged technique for this purpose, as it provides atomic resolution and at the same time enables the study of dynamic information. In this chapter, we provide an overview about the application of Nuclear Magnetic Resonance spectroscopy techniques as a methodology for the rational design of ionic liquids as solvents for small organic compounds, CO2 capture, and polymers such as cellulose focusing mainly in the last 10 years

Neural gliding and neural tensioning differently impact flexibility, heat and pressure pain thresholds in asymptomatic subjects: a randomized, parallel and double-blind study

Objective: To compare the effect of neural gliding and tensioning on hamstring flexibility, nerve function (heat and cold thresholds) and pain sensitivity (pain intensity and pressure pain threshold) of the mobilized and non-mobilized lower limbs at post-intervention and 24 h follow up. Design: Randomized, parallel and double blinded trial. Setting/participants: Forty-eight asymptomatic participants. Intervention(s): Participants received neural gliding (n ¼ 23) or tensioning (n ¼ 25). Main Outcome Measures e Straight leg raising (SLR; in degrees), heat and cold threshold (ºC), pressure pain threshold (PPT; in Kgf) and pain intensity (visual analogue scale), taken at baseline, post- intervention and at 24 h follow up. Results: There was a significant interaction between time, intervention and limb for SLR (F2,45 ¼ 3.83; p ¼ 0.029). A significant interaction between time and intervention for PPT (F2,45 ¼ 3.59; p ¼ 0.036) and heat threshold (F2,45 ¼ 5.10; p ¼ 0.01). A significant effect of time (F2,45 ¼ 9.42; p < 0.001) and of limb (F1,46 ¼ 4.78; p ¼ 0.035) for pain intensity during SLR, and a significant effect of time (F2,45 ¼ 3.65; p ¼ 0.034) for pain intensity during PPT. Conclusion: Gliding and tensioning had similar and positive effects for flexibility in the mobilized limb, but tensioning was superior for the non-mobilized limb. Gliding was superior to tensioning for pressure pain and heat thresholds.publishe

Systems analysis of iron metabolism: the network of iron pools and fluxes

<p>Abstract</p> <p>Background</p> <p>Every cell of the mammalian organism needs iron as trace element in numerous oxido-reductive processes as well as for transport and storage of oxygen. The very versatility of ionic iron makes it a toxic entity which can catalyze the production of radicals that damage vital membranous and macromolecular assemblies in the cell. The mammalian organism maintains therefore a complex regulatory network of iron uptake, excretion and intra-body distribution. Intracellular regulation in different cell types is intertwined with a global hormonal signalling structure. Iron deficiency as well as excess of iron are frequent and serious human disorders. They can affect every cell, but also the organism as a whole.</p> <p>Results</p> <p>Here, we present a kinematic model of the dynamic system of iron pools and fluxes. It is based on ferrokinetic data and chemical measurements in C57BL6 wild-type mice maintained on iron-deficient, iron-adequate, or iron-loaded diet. The tracer iron levels in major tissues and organs (16 compartment) were followed for 28 days. The evaluation resulted in a whole-body model of fractional clearance rates. The analysis permits calculation of absolute flux rates in the steady-state, of iron distribution into different organs, of tracer-accessible pool sizes and of residence times of iron in the different compartments in response to three states of iron-repletion induced by the dietary regime.</p> <p>Conclusions</p> <p>This mathematical model presents a comprehensive physiological picture of mice under three different diets with varying iron contents. The quantitative results reflect systemic properties of iron metabolism: dynamic closedness, hierarchy of time scales, switch-over response and dynamics of iron storage in parenchymal organs.</p> <p>Therefore, we could assess which parameters will change under dietary perturbations and study in quantitative terms when those changes take place.</p

Gas tungsten arc welding of as-cast AlCoCrFeNi2.1 eutectic high entropy alloy

Funding Information: JS, JGL and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges the funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD. TAR acknowledges FCT – MCTES for funding the Ph.D. grant SFRH/BD/144202/2019. Publisher Copyright: © 2022 The AuthorsThe AlCoCrFeNi2.1 eutectic high entropy alloy is of great interest due to its unique mechanical properties combining both high strength and plasticity. Here, gas tungsten arc welding was performed for the first time on an as-cast AlCoCrFeNi2.1 alloy. The microstructural evolution of the welded joints was assessed by combining electron microscopy with electron backscatter diffraction, synchrotron X-ray diffraction analysis and thermodynamic calculations. Microhardness mapping and tensile testing coupled with digital image correlation were used to investigate the strength distribution across the joint. The base material, heat affected zone and fusion zone are composed of an FCC + B2 BCC eutectic structure, although the relative volume fractions vary across the joint owing to the weld thermal cycle. The BCC nanoprecipitates that existed in the base material started to dissolve into the matrix in the heat affected zone and closer to the fusion zone boundary. Compared to the as-cast base material, the fusion zone evidenced grain refinement owing to the higher cooling rate experienced during solidification. This translates into an increased hardness in this region. The joints exhibit good strength/ductility balance with failure occurring in the base material. This work establishes the potential for using arc-based welding for joining eutectic high entropy alloys.publishersversionpublishe

Eyes with Large Disc Cupping and Normal Intraocular Pressure: Using Optical Coherence Tomography to Discriminate Those With and Without Glaucoma

We evaluated the ability of spectral-domain optic coherence tomography (SD-OCT) to differentiate large physiological optic disc cupping (LPC) from glaucomatous cupping in eyes with intraocular pressure (IOP) within the normal range.  We prospectively enrolled patients with glaucoma or presumed LPC. Participants  had optic discs with confirmed or suspected glaucomatous damage (defined as a vertical cup-to-disc ratio≥0.6), and all eyes had known untreated IOP&lt;21 mmHg. For glaucomatous eyes, a reproducible glaucomatous visual field (VF) defect was required. LPC eyes required normal VF and no evidence of progressive glaucomatous neuropathy (follow-up≥30 months). Peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell complex (GCC) thicknesses were obtained using SD-OCT. For all studied parameters of pRNFL and GCC thicknesses, eyes with glaucoma (n=36) had significantly thinner values compared to eyes with LPC (n=71; P&lt;0.05 for all comparisons). In addition, pRNFL parameters had sensitivity of 66.7% and specificity of 83.1%, and GCC parameters had sensitivity of 61.2% and specificity of 81.7%. The combination of the two analyses increased the sensitivity to 80.6%. In conclusion, while evaluating patients with large optic disc cupping and IOP in the statistically normal range, SD-OCT had only limited diagnostic ability to differentiate those with and without glaucoma. Although the diagnostic ability of the pRNFL and the GCC scans were similar, these parameters yielded an increase in sensitivity when combined, suggesting that both parameters could be considered simultaneously in these cases