1,672 research outputs found
Numerical study of the fire behaviour of external walls in light steel framing
This study focuses on the fire behaviour of external walls in Light Steel Frame (LSF) structures. Previous investigations
have primarily addressed the fire behaviour of internal wall configurations, however, the increasing
number of fires affecting external walls shows that their behaviour must also be understood.
Therefore, this work investigates the fire behaviour of these elements, presenting a numerical study of six
different typologies usually found in LSF practice by analysing the temperature evolution across the wall and in
the steel profiles. The results show that the temperature evolution is slower when the fire is impacting the outer
side of the wall but, in these cases, the recommended critical temperature of 350 â—¦C is reached earlier in the steel
profiles. Finally, this work shows that more studies are necessary to describe the fire resistance of external walls,
in particular when these elements have a loadbearing function.Carlos Couto acknowledges the funding from FCT – Fundação para a
Ciência e a Tecnologia, I.P., under the Scientific Employment Stimulus –
Institutional Call – CEECINST/00026/2018.info:eu-repo/semantics/publishedVersio
Evaluation of the immune humoral response of Brazilian patients with Rubinstein-Taybi syndrome
Rubinstein-Taybi syndrome (RTS) is a rare developmental disorder characterized by craniofacial dysmorphisms, broad thumbs and toes, mental and growth deficiency, and recurrent respiratory infections. RTS has been associated with CREBBP gene mutations, but EP300 gene mutations have recently been reported in 6 individuals. In the present study, the humoral immune response in 16 RTS patients with recurrent respiratory infections of possible bacterial etiology was evaluated. No significant differences between patients and 16 healthy controls were detected to explain the high susceptibility to respiratory infections: normal or elevated serum immunoglobulin levels, normal salivary IgA levels, and a good antibody response to both polysaccharide and protein antigens were observed. However, most patients presented high serum IgM levels, a high number of total B cell and B subsets, and also high percentiles of apoptosis, suggesting that they could present B dysregulation. The CREBBP/p300 family gene is extremely important for B-cell regulation, and RTS may represent an interesting human model for studying the molecular mechanisms involved in B-cell development
Reactive toughening of injection-molded polylactide pieces using maleinized hemp seed oil
[EN] The present study describes the effect of maleinized hemp seed oil (MHO) on the physical performance of polylactide (PLA) pieces. To this end, PLA pieces with varying MHO contents in the 0¿10 wt% range were manufactured by twin-screw extrusion (TSE) followed by injection molding. The resultant pieces were characterized in terms of their mechanical, thermal, and thermomechanical properties. The obtained properties suggested that, unlike typical plasticizers, MHO does not only induce an increment in elongation at break and impact resistance but it also enhances both elastic modulus and tensile strength. In addition, a moderate decrease in the glass transition temperature (Tg) was observed. This was ascribed to simultaneous linear chain-extension, branching, and/or cross-linking phenomena due to the reaction of the multiple maleic anhydride (MAH) groups present in MHO with the terminal hydroxyl groups of the PLA chains. Furthermore, morphology characterization revealed that, though certain phase separation occurred at its highest content, MHO was finely dispersed as submicron droplets within the PLA matrix contributing to improving toughness. The use of multi-functionalized reactive vegetable oils thus represents a highly sustainable solution to reduce the intrinsic brittleness of PLA materials without compromising their mechanical resistance and the toughened biopolymer pieces described herein can find interesting applications in, for instance, rigid packaging.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) (projects MAT2014-59242-C2-1-R and AGL2015-63855-C2-1-R.). L. Quiles-Carrillo acknowledges Generalitat Valenciana (GV) for financial support through a FPI grant (ACIF/2016/182) and the Spanish Ministry of Education, Culture, and Sports (MECD) for his FPU grant (FPU15/03812).Quiles-Carrillo, L.; Blanes-MartÃnez, M.; Montanes, N.; Fenollar, O.; Torres-Giner, S.; Balart, R. (2018). Reactive toughening of injection-molded polylactide pieces using maleinized hemp seed oil. European Polymer Journal. 98:402-410. https://doi.org/10.1016/j.eurpolymj.2017.11.039S4024109
6Li direct breakup lifetimes
alpha-d coincidence data were studied for the 6Li + 59Co reaction at E(lab) =
29.6 MeV. By using a kinematic analysis, it was possible to identify which
process, leading to the same final state, has the major contribution for each
of the selected angular regions. Contributions of the 6Li sequential and direct
breakup to the incomplete fusion/transfer process were discussed by considering
the lifetimes obtained by using a semiclassical approach, for both breakup
components.Comment: 5 pages, 4 figures, Invited Talk (Parrallel Sessions) of A. Szanto de
Toledo, prepared for the Proccedings of the 10th International Conference on
Nucleus-Nucleus Collisions, August 16-21, 2009, Beijing, China; submitted to
Nucl. Phys. A (Proceedings of NN2009
Densidade Da Jaguatirica Em Um Ambiente Semiárido No Nordeste Do Brasil
Ocelots play a key role in ecological communities as mesopredators affecting the lower trophic level and other mesopredators. They show great variability in ecological traits across their distribution, but knowledge of this species is missing in several regions where it occurs. Here, we present the first study of ocelot in the Brazilian semiarid of Caatinga. Arid habitats might keep carnivore population density low and therefore vulnerable to environmental shocks and to human-induced changes, at risk of local extinction. To assess their population status, we used camera traps between September 2009 and January 2010. We estimated the density of ocelots using a spatially explicit capture-recapture method (SECR) to be 3.16 ± 0.46 individuals per 100 km2. This is a low-density estimate for ocelots, which might reflect the harsh conditions of the arid habitat. A longer population study of the ocelot can answer if this low population density is enough for a long-term persistence of this species in this and other arid environments. © 2016, Universidade Estadual de Campinas UNICAMP. All rights reserved.16
Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets
An experimental overview of reactions induced by the stable, but weakly-bound
nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F
on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data
on elastic scattering, total reaction cross sections, fusion processes, breakup
and transfer channels are discussed in the framework of a CDCC approach taking
into account the breakup degree of freedom.Comment: 7 pages, 6 figures, Invited Talk given by C. Beck to the 10th
International Conference on Nucleus-Nucleus Collisions, August 16-21, 2009
Beijing, China; Paper submitted to the NN2009 Proceedings, Nuclear Physics A
(to be published
Towards a population of HMXB/NS microquasars as counterparts of low-latitude unidentified EGRET sources
The discovery of the microquasar LS 5039 well within the 95% conficence
contour of the Unidentified EGRET Source (UES) 3EG J1824-1514 was a major step
towards the possible association between microquasars (MQs) and UESs. The
recent discovery of precessing relativistic radio jets in LS I +61 303, a
source associated for long time with 2CG 135+01 and with the UES 3EG
J0241+6103, has given further support to this idea. Finally, the very recently
proposed association between the microquasar candidate AX J1639.0-4642 and the
UES 3EG J1639-4702 points towards a population of High Mass X-ray Binary
(HMXB)/Neutron Star (NS) microquasars as counterparts of low-latitude
unidentified EGRET sources.Comment: 12 pages, 7 figures. Proceedings of the Conference "The
Multiwavelength Approach to Unidentified Gamma-ray Sources", to appear in the
journal Astrophysics and Space Scienc
Diagnostic yield of electromagnetic navigation bronchoscopy is highly dependent on the presence of a Bronchus sign on CT imaging: results from a prospective study
Electromagnetic navigation bronchoscopy (ENB) has been developed as a
novel ancillary tool for the bronchoscopic diagnosis of pulmonary nodules.
Despite successful navigation in 90% of patients, ENB diagnostic yield does not
generally exceed 70%. We sought to determine whether the presence of a bronchus
sign on CT imaging conditions diagnostic yield of ENB and might account for the
discrepancy between successful navigation and diagnostic yield. METHODS: We
conducted a prospective, single-center study of ENB in 51 consecutive patients
with pulmonary nodules. ENB was chosen as the least invasive diagnostic technique
in patients with a high surgical risk, suspected metastatic disease, or
advanced-stage disease, or in those who demanded a preoperative diagnosis prior
to undergoing curative resection. We studied patient and technical variables that
might condition diagnostic yield, including size, cause, location, distance to
the pleural surface, and fluorodeoxyglucose uptake of a given nodule; the
presence of a bronchus sign on CT imaging; registration point divergence; and the
minimum distance from the tip of the locatable guide to the nodule measured
during the procedure. RESULTS: The diagnostic yield of ENB was 67% (34/51). The
sensitivity and specificity of ENB for malignancy in this study were 71% and
100%, respectively. ENB was diagnostic in 79% (30/38) patients with a bronchus
sign on CT imaging but only in 4/13 (31%) with no discernible bronchus sign.
Univariate analysis identified the bronchus sign (P = .005) and nodule size (P =
.04) as statistically significant variables conditioning yield, but on
multivariate analysis, only the bronchus sign remained significant (OR, 7.6; 95%
CI, 1.8-31.7). No procedure-related complications were observed. CONCLUSIONS: ENB
diagnostic yield is highly dependent on the presence of a bronchus sign on CT
imaging
Sex differences in mortality in patients with COPD
Little is known about survival and clinical prognostic factors in females with chronic
obstructive pulmonary disease (COPD). The aim of the present study was to determine the
survival difference between males and females with COPD and to compare the value of the
different prognostic factors for the disease.
In total, 265 females and 272 males with COPD matched at baseline by BODE (body mass index,
airflow obstruction, dyspnoea, exercise capacity) and American Thoracic Society/European
Respiratory Society/Global Initiative of Chronic Obstructive Lung Disease criteria were
prospectively followed. Demographics, lung function, St George’s Respiratory Questionnaire,
BODE index, the components of the BODE index and comorbidity were determined. Survival was
documented and sex differences were determined using Kaplan–Meier analysis. The strength of
the association of the studied variables with mortality was determined using multivariate and
receiver operating curves analysis.
All-cause (40 versus 18%) and respiratory mortality (24 versus 10%) were higher in males than
females. Multivariate analysis identified the BODE index in females and the BODE index and
Charlson comorbidity score in males as the best predictors of mortality. The area under the curve
of the BODE index was a better predictor of mortality than the forced expiratory volume in one
second for both sexes.
At similar chronic obstructive pulmonary disease severity by BODE index and forced expiratory
volume in one second, females have significantly better survival than males. For both sexes the
BODE index is a better predictor of survival than the forced expiratory volume in one second
Scattering of elastic waves by periodic arrays of spherical bodies
We develop a formalism for the calculation of the frequency band structure of
a phononic crystal consisting of non-overlapping elastic spheres, characterized
by Lam\'e coefficients which may be complex and frequency dependent, arranged
periodically in a host medium with different mass density and Lam\'e
coefficients. We view the crystal as a sequence of planes of spheres, parallel
to and having the two dimensional periodicity of a given crystallographic
plane, and obtain the complex band structure of the infinite crystal associated
with this plane. The method allows one to calculate, also, the transmission,
reflection, and absorption coefficients for an elastic wave (longitudinal or
transverse) incident, at any angle, on a slab of the crystal of finite
thickness. We demonstrate the efficiency of the method by applying it to a
specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press
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