1,231 research outputs found
Analysis of the coupled effect of steel studs and surface emissivity on internal insulation systems performance
Many kinds of insulation systems have been developed and applied over the years to all the constructive elements of the building, but the two most used strategies remain the external and internal insulation of vertical walls. However, about the latter often a significant issue is neglected: the overestimation of the thermal performance by disregarding the contribution of construction elements. Usually a uniform stratigraphy of the wall is considered and the evaluation of the performance of a non-uniform one leads to erroneous results about the overall behavior of the system. In this paper, we developed a different approach considering the presence of the steel studs used to attach this package to the existing wall and their influence on the thermal behavior of the structure. Through both experimental and numerical analysis, the possible application of low-e sheets inside the air cavity in various configurations and with different thicknesses of insulation is also taken into account. Results showed that neglecting the presence of the steel studs leads to an erroneous evaluation of the conductance of the refurbished wall with errors reaching up to 28.0% in low-e high-insulated cases. This work highlights how careful the designers have to be when using standard formulas to compute the thermal resistance of internal insulation wall systems
genetic optimization for economic feasibility of refurbishment in buildings
Abstract This paper investigates the possibility to enhance the thermal characteristics of a building fabric taking into account the economic feasibility in order to avoid useless expensive interventions. The problem consists in realizing an internal insulation system for a single apartment located in Trieste. A genetic optimization has been implemented in order to search a large number of solutions with multiple objects and constraints. EnergyPlus has been used for dynamic building and plant simulation and modeFRONTIER for optimization loop setup. The objectives are the used heating energy consumption and the life cycle refurbishment cost, using a net present value approach. An additional objective has been added in order to guarantee the maximization of the interior useful floor area, which is directly influenced by the internal insulation thickness. Different approaches have been compared, considering actions dealing with opaque surfaces only or considering the replacement of existing windows. The paper demonstrates that an automatic optimization approach can help designers to identify the best suited intervention for building refurbishment
Stochastic Geometric Coverage Analysis in mmWave Cellular Networks With Realistic Channel and Antenna Radiation Models
Millimeter-wave (mmWave) bands will play an important role in 5G wireless systems. The system performance can be assessed by using models from stochastic geometry that cater for the directivity in the desired signal transmissions as well as the interference, and by calculating the signal-To-interference-plus-noise ratio ( \mathsf {SINR} ) coverage. Nonetheless, the accuracy of the existing coverage expressions derived through stochastic geometry may be questioned, as it is not clear whether they would capture the impact of the detailed mmWave channel and antenna features. In this paper, we propose an \mathsf {SINR} coverage analysis framework that includes realistic channel model and antenna element radiation patterns. We introduce and estimate two parameters, aligned gain and misaligned gain, associated with the desired signal beam and the interfering signal beam, respectively. The distributions of these gains are used to determine the distribution of the \mathsf {SINR} which is compared with the corresponding \mathsf {SINR} coverage, calculated through the system-level simulations. The results show that both aligned and misaligned gains can be modeled as exponential-logarithmically distributed random variables with the highest accuracy, and can further be approximated as exponentially distributed random variables with reasonable accuracy. These approximations can be used as a tool to evaluate the system-level performance of various 5G connectivity scenarios in the mmWave band.</p
The Low Energy Tagger for the KLOE-2 experiment
The KLOE experiment at the upgraded DAFNE e+e- collider in Frascati (KLOE-2)
is going to start a new data taking at the beginning of 2010 with its detector
upgraded with a tagging system for the identification of gamma-gamma
interactions. The tagging stations for low-energy e+e- will consist in two
calorimeters The calorimeter used to detect low-energy e+e- will be placed
between the beam-pipe outer support structure and the inner wall of the KLOE
drift chamber. This calorimeter will be made of LYSO crystals readout by
Silicon Photomultipliers, to achieve an energy resolution better than 8% at 200
MeV.Comment: 4 pages, 5 figures, in the proceedings of "Frontier detectors for
frontier physics", isola d'Elba, Italy, May 200
Mapping and Monitoring Urban Environment through Sentinel-1 SAR Data: A Case Study in the Veneto Region (Italy)
Focusing on a sustainable and strategic urban development, local governments and public
administrations, such as the Veneto Region in Italy, are increasingly addressing their urban and
territorial planning to meet national and European policies, along with the principles and goals of
the 2030 Agenda for the Sustainable Development. In this regard, we aim at testing a methodology
based on a semi-automatic approach able to extract the spatial extent of urban areas, referred to as
\u201curban footprint\u201d, from satellite data. In particular, we exploited Sentinel-1 radar imagery through
multitemporal analysis of interferometric coherence as well as supervised and non-supervised
classi\ufb01cation algorithms. Lastly, we compared the results with the land cover map of the Veneto
Region for accuracy assessments. Once properly processed and classi\ufb01ed, the radar images resulted
in high accuracy values, with an overall accuracy ranging between 85% and 90% and percentages of
urban footprint di\ufb00ering by less than 1%\u20132% with respect to the values extracted from the reference
land cover map. These results provide not only a reliable and useful support for strategic urban
planning and monitoring, but also potentially identify a solid organizational data\ufb02ow process to
prepare geographic indicators that will help answering the needs of the 2030 Agenda (in particular
the goal 11 \u201cSustainable Cities and Communities\u201d)
Thoracic involvement in systemic autoimmune rheumatic diseases: pathogenesis and management.
Thoracic involvement is one of the main determinants of morbidity and mortality in patients with autoimmune rheumatic diseases (ARDs), with different prevalence and manifestations according to the underlying disease. Interstitial lung disease (ILD) is the most common pulmonary complication, particularly in patients with systemic sclerosis (SSc), idiopathic inflammatory myopathies (IIMs) and rheumatoid arthritis (RA). Other thoracic manifestations include pulmonary arterial hypertension (PAH), mostly in patients with SSc, airway disease, mainly in RA, and pleural involvement, which is common in systemic lupus erythematosus and RA, but rare in other ARDs.In this review, we summarize and critically discuss the current knowledge on thoracic involvement in ARDs, with emphasis on disease pathogenesis and management. Immunosuppression is the mainstay of therapy, particularly for ARDs-ILD, but it should be reserved to patients with clinically significant disease or at risk of progressive disease. Therefore, a thorough, multidisciplinary assessment to determine disease activity and degree of impairment is required to optimize patient management. Nevertheless, the management of thoracic involvement-particularly ILD-is challenging due to the heterogeneity of disease pathogenesis, the variety of patterns of interstitial pneumonia and the paucity of randomized controlled clinical trials of pharmacological intervention. Further studies are needed to better understand the pathogenesis of these conditions, which in turn is instrumental to the development of more efficacious therapies
Higher ventricular-arterial coupling derived from three-dimensional echocardiography is associated with a worse clinical outcome in systemic sclerosis
Primary myocardial involvement is common in systemic sclerosis (SSc). Ventricular-arterial coupling (VAC) reflecting the interplay between ventricular performance and arterial load, is a key determinant of cardiovascular (CV) performance. We aimed to investigate VAC, VAC-derived indices, and the potential association between altered VAC and survival free from death/hospitalization for major adverse CV events (MACE) in scleroderma. Only SSc patients without any anamnes-tic and echocardiographic evidence of primary myocardial involvement who underwent three-dimensional echocardiography (3DE) were included in this cross-sectional study and compared with healthy matched controls. 3DE was used for noninvasive measurements of end-systolic elastance (Ees), arterial elastance (Ea), VAC (Ea/Ees) and end-diastolic elastance (Eed); the occurrence of death/hospitalization for MACE was recorded during follow-up. Sixty-five SSc patients (54 female; aged 56 ± 14 years) were included. Ees (p = 0.04), Ea (p = 0.04) and Eed (p = 0.01) were higher in patients vs. controls. Thus, VAC was similar in both groups. Ees was lower and VAC was higher in patients with diffuse cutaneous form (dcSSc) vs. patients with limited form (lcSSc) (p = 0.001 and p = 0.02, respectively). Over a median follow-up of 4 years, four patients died for heart failure and 34 were hospitalized for CV events. In patients with VAC >0.63 the risk of MACE was higher (HR 2.5; 95% CI 1.13–5.7; p = 0.01) and survival free from death/hospitalization was lower (p = 0.005) than in those with VAC < 0.63. Our study suggests that VAC may be impaired in SSc patients without signs and symptoms of primary myocardial involvement. Moreover, VAC appears to have a prognostic role in SSc
Níveis de metano e perdas energéticas em bovinos de corte, suplementados ou não, em pastagem de capim mombaça (Panicum maximum cv. Mombaça).
Objetivou-se avaliar o impacto da suplementação protéico-energética na emissão de metano (CH4) de novilhos, durante a recria, em pastagem de capim-mombaça. Os tratamentos avaliados foram: T0 ? Apenas suplementação mineral; T1 ? Suplementação protéico-energética. Utilizou-se a técnica do gás traçador interno hexafluoreto de enxofre (SF6) para estimar a emissão diária de CH4. Foram utilizados 20 animais, sendo dez de cada tratamento, em dois ensaios, com medição de CH4 em cinco dias consecutivos. Na análise estatística dos dados de emissão de CH4 , utilizou-se a metodologia de modelos mistos para medidas repetidas do SAS. Os animais foram também avaliados quanto à eficiência de utilização do alimento, utilizando-se como critério o consumo alimentar residual (CAR). Animais suplementados e não suplementados não diferiram (P>0,05) quanto à produção diária de metano e quanto à perda total diária de energia na forma de CH4. Entretanto, quando a perda de energia foi expressa em g/kg de matéria seca consumida (21,51 vs. 29,76 g/kg) e como porcentagem da energia bruta (EB) ingerida (6,36 versus 8,59 %), os animais suplementados tiveram menores perdas (P0,05) quanto aos níveis de emissão de metano (total ou por kg de matéria seca ? MS ingerida). Assim, conclui-se que: a suplementação com concentrado age de forma efetiva na mitigação da emissão de metano; diferenças no CAR não podem ser atribuídas a diferenças nos níveis de emissão de metano
New Therapeutic Options for the Treatment of Sickle Cell Disease.
Sickle cell disease (SCD; ORPHA232; OMIM # 603903) is a chronic and invalidating disorder distributed worldwide, with high morbidity and mortality. Given the disease complexity and the multiplicity of pathophysiological targets, development of new therapeutic options is critical, despite the positive effects of hydroxyurea (HU), for many years the only approved drug for SCD. New therapeutic strategies might be divided into (1) pathophysiology-related novel therapies and (2) innovations in curative therapeutic options such as hematopoietic stem cell transplantation and gene therapy. The pathophysiology related novel therapies are: a) Agents which reduce sickling or prevent sickle red cell dehydration; b) Agents targeting SCD vasculopathy and sickle cell-endothelial adhesive events; c) Anti-oxidant agents. This review highlights new therapeutic strategies in SCD and discusses future developments, research implications, and possible innovative clinical trials
Nanoscale Assembly of Functional Peptides with Divergent Programming Elements
Self-assembling peptides are being applied both in the biomedical area and as building blocks in nanotechnology. Their applications are closely linked to their modes of self-assembly, which determine the functional nanostructures that they form. This work brings together two structural elements that direct nanoscale self-association in divergent directions: proline as a β-breaker and the β-structure-associated diphenylalanine motif, into a single tripeptide sequence. Amino acid chirality was found to resolve the tension inherent to these conflicting self-assembly instructions. Stereoconfiguration determined the ability of each of the eight possible Pro-Phe-Phe stereoisomers to self-associate into diverse nanostructures, including nanoparticles, nanotapes, or fibrils, which yielded hydrogels with gel-to-sol transition at a physiologically relevant temperature. Three single-crystal structures and all-atom molecular dynamics simulations elucidated the ability of each peptide to establish key interactions to form long-range assemblies (i,e., stacks leading to gelling fibrils), medium-range assemblies (i.e., stacks yielding nanotapes), or short-range assemblies (i.e., dimers or trimers that further associated into nanoparticles). Importantly, diphenylalanine is known to serve as a binding site for pathological amyloids, potentially allowing these heterochiral systems to influence the fibrillization of other biologically relevant peptides. To probe this hypothesis, all eight Pro-Phe-Phe stereoisomers were tested in vitro on the Alzheimer's disease-associated Aβ(1-42) peptide. Indeed, one nonfibril-forming stereoisomer effectively inhibited Aβ fibrillization through multivalent binding between diphenylalanine motifs. This work thus defined heterochirality as a useful feature to strategically develop future therapeutics to interfere with pathological processes, with the additional value of resistance to protease-mediated degradation and biocompatibility
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