Concentrated suspensions of Brownian beads in water: dynamic heterogeneities trough a simple experimental technique

Concentrated suspensions of Brownian hard-spheres in water are an epitome for understanding the glassy dynamics of both soft materials and supercooled molecular liquids. From an experimental point of view, such systems are especially suited to perform particle tracking easily, and, therefore, are a benchmark for novel optical techniques, applicable when primary particles cannot be resolved. Differential Variance Analysis (DVA) is one such novel technique that simplifies significantly the characterization of structural relaxation processes of soft glassy materials, since it is directly applicable to digital image sequences of the sample. DVA succeeds in monitoring not only the average dynamics, but also its spatio-temporal fluctuations, known as dynamic heterogeneities. In this work, we study the dynamics of dense suspensions of Brownian beads in water, imaged through digital video-microscopy, by using both DVA and single-particle tracking. We focus on two commonly used signatures of dynamic heterogeneities: the dynamic susceptibility, $\chi_4$, and the non-Gaussian parameter, $\alpha_2$. By direct comparison of these two quantities, we are able to highlight similarities and differences. We do confirm that $\chi_4$ and $\alpha_2$ provide qualitatively similar information, but we find quantitative discrepancies in the scalings of characteristic time and length scale on approaching the glass transition.Comment: The original publication is available at http://www.scichina.com and http://www.springerlink.com http://engine.scichina.com/publisher/scp/journal/SCPMA/doi/10.1007/s11433-019-9401-x?slug=abstrac

An investigation on the structural integrity of network arch bridges subjected to cable loss under the action of moving loads

Abstract A numerical study is developed to investigate the structural behavior of network arch bridges subjected to the cable loss of hanger elements of the cable system under the action of moving loads. The main aim of the paper is to analyze the effects produced by potential cable loss scenarios on the main kinematic design variables of the structure. The structural behavior is investigated by means of a refined FE nonlinear geometric formulation, in which the influence of large displacements and local vibrations of cable elements are taken into account. The loss of a cable is properly reproduced by means of a damage law consistently with Continuum Damage Mechanics theory. Moreover, a refined formulation is implemented with the aim to reproduce the inertial characteristics of the moving loads, by accounting for the coupling effects arising from the interaction between bridge deformations and moving system parameters. Numerical analyses are performed by means of both nonlinear dynamic analyses and simplified methodologies proposed by existing codes on cable supported bridges. In this framework, the applicability of such simplified methodologies in the case of the network arch bridges is discussed

Anisotropic tunneling in {InGaAsP}/{InP} multi-quantum barrier structure

We present magneto-photoluminescence experiments on a multi-quantum-barrier structure consisting of 31 period of wide (58 nm) quaternary wells of InGaAsP with the same lattice parameter as InP separated by thin (8 nm) InP barriers. The anomalous diamagnetic shift and the asymmetric broadening of the luminescence spectra evidence strong band filling in the tail of the density of states of the quaternary alloy, suggesting that tunneling transport through the InP barrier is anisotropic along the growth axis, due to different band lineups for the direct (InGaAsP-on-InP) and inverse (InP-on-InGaAsP) interfaces. This finding is supported by high resolution X-ray patterns, yielding evidence that the direct and inverse interfaces are smooth and display different chemical compositions

Resistance traits and AFLP characterization of diploid primitive tuber-bearing potatoes.

ISSN: 0925-986

Strategies to improve the structural integrity of tied-arch bridges affected by instability phenomena

Abstract A numerical study is proposed to investigate the nonlinear behavior of steel tied-arch bridges, whose arch ribs are inclined inwardly. The main aim of the paper is to assess if the arch rib inclination may be an effective strategy to enhance the structural integrity of the bridge structure against out-of-plane buckling mechanisms. The nonlinear behavior of the structure is investigated throughout an advanced 3D finite element model, which accurately reproduces nonlinear sources involved in the cable system and structural elements. An analysis that combines results obtained by traditional elastic buckling analysis and incremental nonlinear elastic analysis is employed to properly evaluate the maximum capacity of the structure. Comparisons between bridge structures with inclined and vertical ribs configurations are proposed focusing attention on both structural and economic aspects. Results show that rib inclination provides several structural benefits to the bridge while reducing overall construction costs

Zespół padaczkowy z drgawkami połowiczymi i porażeniem połowiczym. Wyniki badania za pomocą rezonansu magnetycznego u trzyletniego chłopca

The term ‘hemiconvulsion-hemiplegia-epilepsy syndrome’ (HHE) was first used by Gastaut et al. to describe the sequential combination of unilateral or predominandy unilateral clonic seizures (hemiconvulsion), occurring during the first 2 years of life, immediately followed by an ipsilateral flaccid hemiplegia lasting 7 or more days. In the following phase partial epileptic seizures occur. We report a case of HHE syndrome in a 3-year-old boy with partial seizures (hemiconvulsion lasting 15–30 minutes) followed by left hemiplegia and hyporeflexia. Magnetic resonance imaging showed diffuse and high signal hyperintensity of the whole right cerebral hemisphere. Diffusion-weighted images showed a reduction of the apparent diffusion coefficient in the subcortical region. Magnetic resonance arteriography showed a narrow flow signal in the distal territory of the right middle cerebral artery. The authors emphasize the importance of neuroradiological findings in early diagnosis and in the follow-up of HHE syndrome.Określenia zespół padaczkowy z drgawkami połowiczymi i z porażeniem połowiczym” (hemiconvulsion-hemiplegia epilepsy – HHE) użyli po raz pierwszy Gastaut i wsp., aby opisać połączenie jednostronnych lub głównie jednostronnych drgawek klonicznych, pojawiających się w pierwszych dwóch latach życia, po których następuje tożstronne wiotkie porażenie połowicze utrzymujące się przez co najmniej tydzień. Następnie występują napady padaczkowe częściowe. W artykule przedstawiono przypadek zespołu HHE u trzyletniego chłopca z napadami częściowymi (drgawki połowicze trwające 15–30 minut), po których nastąpiło lewostronne porażenie połowicze z osłabionymi odruchami głębokimi. W badaniu za pomocą rezonansu magnetycznego uwidoczniono rozlane zmiany hiperintensywne w całej prawej półkuli mózgu. W obrazowaniu dyfuzji stwierdzono zmniejszenie współczynnika dyfuzji w obszarach podkorowych. W arteriografii rezonansu magnetycznego uwidoczniono wąski sygnał przepływu w dystalnych gałęziach prawej tętnicy środkowej mózgu. Autorzy podkreślają znaczenie wyników badań obrazowych układu nerwowego we wczesnym rozpoznaniu i obserwacji chorych na HHE

Design and Prototyping of Miniaturized Straight Bevel Gears for Biomedical Applications

This paper presents a semi-automated design algorithm for computing straight bevel gear involute profiles. The proposed formulation is based on the Tredgold approximation method. It allows the design of a pair of bevel gears with any desired number of teeth and relative axes inclination angles by implementing additive manufacturing technology. A specific case study is discussed to calculate the profiles of two straight bevel gears of a biomedical application. Namely, this paper illustrates the design of the bevel gears for a new laparoscopic robotic system, EasyLap, under development with a grant from POR Calabria 2014–2020 Fesr-Fse. A meshing analysis is carried out to identify potential design errors. Moreover, finite element-based tooth contact analysis is fulfilled for determining the vibrational performances of the conjugate tooth profiles throughout a whole meshing cycle. Simulation results and a built prototype are reported to show the engineering feasibility and effectiveness of the proposed design approach

Obstructive Sleep Apnea (OSA), an emerging health problem

Obstructive Sleep Apnea (OSA) is the most common respiratory disorder in Western societies: according to a first recent worldwide epidemiological study, it was estimated that 936 million patients aged 30-69 years with mild to moderate OSA and 425 million patients aged 30-69 years with severe OSA requiring CPAP treatment. Recently, the Centre for Research on Health and Social Care Management (CERGAS) at the Bocconi University of Milan has estimated that in Italy, the prevalence of moderate to severe OSA occurs in the 27% of the general population, with an overall prevalence of mild to medium-severe OSA of more than 24 million people aged between 15 and 74 years (54% of the adult population), while from a practical point of view, Italian doctors diagnosed only 460.000 moderate-severe patients (4 per cent of the estimated prevalence) and 230,000 patients were treated (2 per cent of the estimated prevalence), highlighting a substantial gap between diagnosis and treatment. In addition, OSA patients are often obese and the close correlation between the two conditions suggests that the prevalence of OSA will increase in the short term as obesity increases. At the individual level, OSA leads to a significant decrease in quality of life (HRQoL) and intellectual and mechanical/functional capacities with reduced physical activity, as well as a marked increase in sudden death and risk of cardiovascular and metabolic diseases. Emerging epidemiological data also suggest that the severity of OSA associated with the severity of chronic nocturnal hypoxemia (CIH) correlates with an increased risk of diabetes mellitus, metabolic syndrome (MS) and cancer. OSA is also an important risk factor for high blood pressure, acute and chronic atrial fibrillation (FAC), chronic coronary artery disease (CAD) and stroke. It is therefore intuitive that at the social level, OSA also leads to a decline in economic productivity. This article addresses OSA from a new epidemiological perspective, according to the latest prevalence studies, and addresses emerging problems related to the diagnosis

Calibration of Elekta aSi EPIDs used as transit dosimeter.

The transit in vivo dosimetry performed by the Electronic Portal Imaging Device (EPID), avoids the problem of solid-state detector positioning on the patient. Moreover, the dosimetric characterization of the recent Elekta aSi EPIDs in terms of signal stability and linearity enables these detectors adaptable for the transit in vivo dosimetry with 6, 10 and 15 MV photon beams. However, the implementation of the EPID transit dosimetry requires several measurements. Recently, the present authors have developed an in vivo dosimetry method for the 3D CRT based on correlation functions defined by the ratios between the transit signal, st (w,L), by the EPID and the phantom mid-plane dose, Dm(w,L), at the Source to Axis Distance (SAD) as a function of the phantom thickness, w, and the square field dimensions, L. When the phantom mid-plane was positioned at distance d from the SAD, the ratios st(w,L)/s't(d,w,L), were used to take into account the variation of the scattered photon contributions on the EPID as a function of, d and L. The aim of this paper was the implementation of a procedure that uses generalized correlation functions obtained by nine Elekta Precise linac beams. The procedure can be used by other Elekta Precise linacs equipped with the same aSi EPIDs assuring the stabilities of the beam output factors and the EPID signals. The calibration procedure of the aSi EPID here reported avoids measurements in solid water equivalent phantoms needed to implement the in vivo dosimetry method in the radiotherapy center. A tolerance level ranging between ±5% and ±6% (depending on the type of tumor) was estimated for the comparison between the reconstructed isocenter dose, Diso and the computed dose Diso, TPS by the treatment planning system (TPS)