494 research outputs found
Homodyne and heterodyne X-ray photon correlation spectroscopy: latex particles and elastomers
The Upper Precambrian of South America
This paper deals with the structural organization and tectonic evolution of South American Continent basement during the Upper Precambrian. The South American Platform is the old platform of South America. It has more than half of this extension covered by sediments and volcanic rocks of Phanerozoic age; the basement is exposed in three vast shields and several little massifs. In the exposed basement some cratonic nuclei have been distinguished, with structures developed in the Middle Precambrian (Trans-Amazonic) and Lower Precambrian (Jequié and Guriense). The Lower Precambrian structures are described in small scattered nuclei, all the rest seeming to have been remobilized by tectonic, magmatic and thermal processes of Trans-Amazonic age. These processes affected large areas but are still insufficiently understood. In the Upper Precambrian, these cratonic nuclei underwent intense process of reactivation, in large areas, with formation of volcano-sedimentary covers, acid, basic and alkaline intrusive rocks, cataclastic zones and thermally affected zones. During the Upper Precambrian, geosynclinal evolution processes developed at the borders and between the cratons, generating fold belts and regions. The firstly developed belt is located in Central Brazil, related to the Uruaçuano Cycle (ca. 1300-1000 m.a.). The Espinhaço and Uruaçu Belts are attributed to this cycle. The other units are related to the Brasiliano Cycle ( 1000 m.y. to Cambro-Ordovician time). The fold belts are located in marginal position and the fold regions are between cratonic areas: both show different characteristic of organization, sedimentation, structures, tectonism, metamorphism, magmatism and metallogenesis. In the southern border of the South American Platform a fold region developed, which possibly represents the extension of the Southeastern Fold Region, and continues to the Andean Belt. The South American Platform consolidated during Cambro-Ordovician time. Its western and southern adjacent areas were places of geosynclinal evolution up to the Devonian in the Patagonian Platform and up to the Cenozoic in the Andean Chain. The eastern half of the South American Platform had a platformal evolution since the Siluria
Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering
The temperature dependence of the x-ray scattering in the region below the
first sharp diffraction peak was measured for silica glasses with low and high
OH content (GE-124 and Corning 7980). Data were obtained upon scanning the
temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements
resolve, for the first time, the hysteresis between heating and cooling through
the glass transition for silica glass, and the data have a better signal to
noise ratio than previous light scattering and differential thermal analysis
data. For the glass with the higher hydroxyl concentration the glass transition
is broader and at a lower temperature. Fits of the data to the
Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very
strong glass. The temperature derivative of the observed X-ray scattering
matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres
A fast ILP-based Heuristic for the robust design of Body Wireless Sensor Networks
We consider the problem of optimally designing a body wireless sensor
network, while taking into account the uncertainty of data generation of
biosensors. Since the related min-max robustness Integer Linear Programming
(ILP) problem can be difficult to solve even for state-of-the-art commercial
optimization solvers, we propose an original heuristic for its solution. The
heuristic combines deterministic and probabilistic variable fixing strategies,
guided by the information coming from strengthened linear relaxations of the
ILP robust model, and includes a very large neighborhood search for reparation
and improvement of generated solutions, formulated as an ILP problem solved
exactly. Computational tests on realistic instances show that our heuristic
finds solutions of much higher quality than a state-of-the-art solver and than
an effective benchmark heuristic.Comment: This is the authors' final version of the paper published in G.
Squillero and K. Sim (Eds.): EvoApplications 2017, Part I, LNCS 10199, pp.
1-17, 2017. DOI: 10.1007/978-3-319-55849-3\_16. The final publication is
available at Springer via http://dx.doi.org/10.1007/978-3-319-55849-3_1
Qualitative evaluation of a preventive intervention for the offspring of parents with a history of depression
Background:
Meta-analyses of randomised controlled trials suggest that psychological interventions to reduce children’s risk of depression are effective. Nevertheless, these effects are modest and diminish over time. The Medical Research Council recommends a mixed-methods approach to the evaluation of complex interventions. By gaining a more thorough understanding of participants’ perspectives, qualitative evaluations of preventive interventions could improve their efficacy, longevity and transfer into clinical practice.
Methods:
18 parents and 22 children who had received a 12-session family- and group-based cognitivebehavioural intervention to prevent youth depression as part of a randomised controlled trial took part in semistructured interviews or a focus group about aspects which had been perceived as helpful, elements they were still using after the intervention had ended, and suggestions they had for improving the intervention.
Results:
The chance to openly share and discuss their experiences of depression within and between families was considered helpful by both children and parents. Children benefitted the most from learning coping strategies for dealing with stress and many still used them in everyday life. Parents profited mostly from increasing positive family time, but noted that maintaining new routines after the end of the intervention proved difficult. Participants were generally content with the intervention but commented on how tiring and time consuming it was.
Conclusions:
Managing parents’ expectations of family-based interventions in terms of their own mental health needs (versus those of their children) and leaving more room for open discussions may result in interventions which are more appealing to participating families. Increasing intervals between sessions may be one means of improving the longevity of interventions.
Trial registration: The original RCT this evaluation is a part of was registered under NCT02115880
Outcome comparison between radiation therapy and surgery as primary treatment for dogs with periarticular histiocytic sarcoma: An Italian Society of Veterinary Oncology study
Localized histiocytic sarcoma may occur as a primary lesion in periarticular tissues of large appendicular joints. Treatment options for the primary lesion include radical surgical excision, radiation therapy (RT), or both, in combination with chemotherapy for potential systemic metastases. In an effort to better characterize the time to progression (TTP) following surgical vs non-surgical approaches for periarticular histiocytic sarcoma (PAHS), a contemporary European population of affected dogs was retrospectively surveyed. Medical records were queried for newly-diagnosed PAHS cases undergoing surgery (predominantly limb amputation) or RT followed by systemic chemotherapy. Of 49 dogs, 34 underwent RT and 15 underwent surgery. All dogs received adjuvant chemotherapy. There was no statistically significant difference in TTP or overall survival between groups. The median TTP was 336 days for the operated dogs and 217 days for the irradiated dogs (P =.117). The median overall survival time was 398 days for the operated dogs and 240 days for the irradiated dogs (P =.142). On multi-variable analysis, the variables significantly associated with an increased risk of both tumour progression and tumour-related death were regional lymph node and distant metastasis at admission. Survival and local control rates following RT may be comparable to radical resection. These data may better inform shared decision-making processes between multi-disciplinary care providers and owners
PYROMEMS IGNITER BASED ON A TEMPERATURE GRADIENT: CONCEPT, FABRICATION AND CHARACTERIZATION
A pyroMEMS igniter with increased combustion reliability is presented. The igniter consisted of a thin-film platinum Joule heater fabricated on a borosilicate glass substrate. Two different igniter layouts (meandering and annular) and three different binder mass fractions (5, 10 and 20 %) were evaluated. High-speed videos were used to judge the success or failure of the combustion events. Although the ignition success rate was 100 %, the combustion success rate was approximately 87.5 ± 7.1 % for the annular design versus 12.5 ± 7.1 % for the meandering layout. No effect on success rate was observed for the different binder contents tested. Rather, increasing the binder mass fraction increased the combustion duration
A Calibration Method for the Integrated Design of Finishing Robotic Workcells in the Aerospace Industry
Industrial robotics provides high flexibility and reconfigurability, cost effectiveness and user friendly programming for many applications but still lacks in accuracy. An effective workcell calibration reduces the errors in robotic manufacturing and contributes to extend the use of industrial robots to perform high quality finishing of complex parts in the aerospace industry. A novel workcell calibration method is embedded in an integrated design framework for an in-depth exploitation of CAD-based simulation and offline programming.
The method is composed of two steps: a first offline calibration of the workpiece-independent elements in the workcell layout and a final automated online calibration of workpiece-dependent elements. The method is finally applied to a robotic workcell for finishing aluminum housings of helicopter gear transmissions, characterized by complex and non-repetitive shapes, and by severe dimensional and geometrical accuracy demands. Experimental results
demonstrate enhanced performances of the robotic workcell and improved final quality of the housings
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