7,314 research outputs found
A Twin Spiral Planar Antenna for UWB Medical Radars
A planar-spiral antenna to be used in an ultrawideband (UWB) radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation
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Quantum spin Hall effect in bound states in continuum
Moving the polarization of the incident wave along a meridian of the Poincaré sphere, experimentally we show that the coupling with the fundamental Bloch's surface waves of the mode, provide a spatially coherent, macroscopic spinmomentum locked propagation along the symmetry axes of the PhCM. This novel mechanism of light-spin manipulation enables a versatile implementation of spin-optical structures that may pave the way to novel strategies for light spin technology and photonic multiplatform implementations
Growth of ZnO nanolayers inside the capillaries of photonic crystal fibres
In this study, we describe the formation of ZnO nanolayers inside the air
capillaries of a silica photonic crystal fibre (PCF), targeting random laser
and organic vapor sensing applications. ZnO nanolayers were developed by
infiltrating the capillaries of the silica PCF with Zn-acetate/methanol
solutions of various concentrations, followed by annealing treatments. The
growth and morphology of the synthesized ZnO nanolayers were characterized by
means of scanning electron microscopy (SEM) and found to be affected by the
concentration of the Zn-acetate/methanol infiltration solution. For low
concentrations, inspection with SEM revealed the formation of 25 and
100-nm-thick ZnO nanolayers across the entire length of the infiltrated
capillaries, whereas increasing the Zn-acetate concentration resulted to the
formation of randomly placed isolated ZnO nanorods. Room temperature
photoluminescence spectra of the ZnO nanolayers inside the PCF were measured
and compared with the corresponding spectra reported for ZnO structures formed
on typical surfaces.Comment: 5 pages, 5 figures, Available online 29 June 2013, in press. Thin
Solid Film, Elsevier, Available online 29 June 201
Active macro-zone approach for incremental elastoplastic-contact analysis
The symmetric boundary element method, based on the Galerkin hypotheses, has found an application in
the nonlinear analysis of plasticity and in contact-detachment problems, but both dealt with separately. In
this paper, we want to treat these complex phenomena together as a linear complementarity problem.
A mixed variable multidomain approach is utilized in which the substructures are distinguished into
macroelements, where elastic behavior is assumed, and bem-elements, where it is possible that plastic strains
may occur. Elasticity equations are written for all the substructures, and regularity conditions in weighted
(weak) form on the boundary sides and in the nodes (strong) between contiguous substructures have to be
introduced, in order to attain the solving equation system governing the elastoplastic-contact/detachment
problem. The elastoplasticity is solved by incremental analysis, called for active macro-zones, and uses the
well-known concept of self-equilibrium stress field here shown in a discrete form through the introduction
of the influence matrix (self-stress matrix). The solution of the frictionless contact/detachment problem was
performed using a strategy based on the consistent formulation of the classical Signorini equations rewritten
in discrete form by utilizing boundary nodal quantities as check elements in the zones of potential contact
or detachment
Ketogenic diet-induced weight loss is associated with an increase in vitamin d levels in obese adults
Vitamin D is an important micronutrient involved in several processes. Evidence has shown a strong association between hypovitaminosis D and cardio-metabolic diseases, including obesity. A ketogenic diet has proven to be very effective for weight loss, especially in reducing fat mass while preserving fat-free mass. The aim of this study was to investigate the effect of a ketogenic diet-induced weight loss on vitamin D status in a population of obese adults. We enrolled 56 obese outpatients, prescribed with either traditional standard hypocaloric Mediterranean diet (SHMD) or very low-calorie ketogenic diet (VLCKD). Serum 25(OH)D concentrations were measured by chemiluminescence. The mean value of serum 25-hydroxyvitamin D (25(OH)D) concentrations in the whole population at baseline was 17.8 +/- 5.6 ng/mL, without differences between groups. After 12 months of dietetic treatment, in VLCKD patients serum 25(OH)D concentrations increased from 18.4 +/- 5.9 to 29.3 +/- 6.8 ng/mL (p < 0.0001), vs 17.5 +/- 6.1 to 21.3 +/- 7.6 ng/mL (p = 0.067) in the SHMD group (for each kilogram of weight loss, 25(OH)D concentration increased 0.39 and 0.13 ng/mL in the VLCKD and in the SHMD groups, respectively). In the VLCKD group, the increase in serum 25(OH)D concentrations was strongly associated with body mass index, waist circumference, and fatty mass variation. In a multiple regression analysis, fatty mass was the strongest independent predictor of serum 25(OH)D concentration, explaining 15.6%, 3.3%, and 9.4% of its variation in the whole population, in SHMD, and VLCKD groups, respectively. We also observed a greater reduction of inflammation (evaluated by high-sensitivity C reactive protein (hsCRP) values) and a greater improvement in glucose homeostasis, confirmed by a reduction of HOMA values, in the VLCKD versus the SHMD group. Taken together, all these data suggest that a dietetic regimen, which implies a great reduction of fat mass, can improve vitamin D status in the obese
The Effect of Advanced Traveller Information Systems (ATIS) on public transport demand and its uncertainty
Advanced Traveller Information Systems (ATISs) include a broad range of advanced computer and communication technologies. These systems are designed to provide transit riders pre-trip and real-time information, to make better
informed decisions regarding their mode of travel, planned routes and travel times. ATISs include in-vehicle displays, terminal or wayside based information centres, information by phone or mobile and internet. In this article, a Stated
Preference survey has been carried out in order to know the preferences of public transport\u2019s customers related to different ATISs and their willingness to pay in Palermo. An ordered probit demand model has been calibrated to determine the potential additional share of demand attracted by the adoption of ATISs. Finally, Monte Carlo simulation has been carried out to appraise the uncertainty on some parameters of the calibrated demand model. The results show that respondents give more importance to the type of information and its cost, whereas they are less interested in the system that provides the information
Elastoplastic analysis by active macro-zones with linear kinematic hardening and von Mises materials
In this paper a strategy to perform elastoplastic analysis with linear kinematic hardening
for von Mises materials under plane strain conditions is shown. The proposed approach
works with the Symmetric Galerkin Boundary Element Method applied to multidomain
problems using a mixed variables approach, to obtain a more stringent solution. The elastoplastic
analysis is carried out as the response to the loads and the plastic strains, the latter
evaluated through the self-equilibrium stress matrix. This matrix is used both, in the predictor
phase, for trial stress evaluation and, in the corrector phase, for solving a nonlinear
global system which provides the elastoplastic solution of the active macro-zones, i.e. those
zones collecting bem-elements where the plastic consistency condition has been violated.
The simultaneous use of active macro-zones gives rise to a nonlocal approach which is
characterized by a large decrease in the plastic iteration number, although the proposed
strategy requires the inversion and updating of Jacobian operators generally of big dimensions.
A strategy developed in order to reduce the computational efforts due to the use of
this matrix, in a recursive process, is shown
BAFF Index and CXCL13 levels in the cerebrospinal fluid associate respectively with intrathecal IgG synthesis and cortical atrophy in multiple sclerosis at clinical onset
Abstract
Background
B lymphocytes are thought to play a relevant role in multiple sclerosis (MS) pathology. The in vivo analysis of intrathecally produced B cell-related cytokines may help to clarify the mechanisms of B cell recruitment and immunoglobulin production within the central nervous system (CNS) in MS.
Methods
Paired cerebrospinal fluid (CSF) and serum specimens from 40 clinically isolated syndrome suggestive of MS or early-onset relapsing-remitting MS patients (CIS/eRRMS) and 17 healthy controls (HC) were analyzed for the intrathecal synthesis of IgG (quantitative formulae and IgG oligoclonal bands, IgGOB), CXCL13, BAFF, and IL-21. 3D-FLAIR, 3D-DIR, and 3D-T1 MRI sequences were applied to evaluate white matter (WM) and gray matter (GM) lesions and global cortical thickness (gCTh).
Results
Compared to HC, CIS/eRRMS having IgGOB (IgGOB+, 26 patients) had higher intrathecal IgG indexes ( p \u2009<\u20090.01), lower values of BAFF Index (11.9\u2009\ub1\u20096.1 vs 17.5\u2009\ub1\u20095.2, p \u2009<\u20090.01), and higher CSF CXCL13 levels (27.7\u2009\ub1\u200933.5 vs 0.9\u2009\ub1\u20091.5, p \u2009<\u20090.005). In these patients, BAFF Index but not CSF CXCL13 levels inversely correlated with the intrathecal IgG synthesis ( r \u2009>\u20090.5 and p \u2009<\u20090.05 for all correlations). CSF leukocyte counts were significantly higher in IgGOB+ compared to IgGOB\u2212 ( p \u2009<\u20090.05) and HC ( p \u2009<\u20090.01), and correlated to CSF CXCL13 concentrations ( r 0.77, p \u2009<\u20090.001).
The gCTh was significantly lower in patients with higher CSF CXCL13 levels (2.41\u2009\ub1\u20090.1 vs 2.49\u2009\ub1\u20090.1\ua0mm, p \u2009<\u20090.05), while no difference in MRI parameters of WM and GM pathology was observed between IgGOB+ and IgGOB\u2212.
Conclusions
The intrathecal IgG synthesis inversely correlated with BAFF Index and showed no correlation with CSF CXCL13. These findings seem to indicate that intrathecally synthesized IgG are produced by long-term PCs that have entered the CNS from the peripheral blood, rather than produced by PCs developed in the meningeal follicle-like structures (FLS). In this study, CXCL13 identifies a subgroup of MS patients characterized by ..
Frictionless contact-detachment analysis: iterative linear complementarity and quadratic programming approaches
The object of the paper concerns a consistent formulation
of the classical Signorini\u2019s theory regarding the frictionless
contact problem between two elastic bodies in the
hypothesis of small displacements and strains. The employment
of the symmetric Galerkin boundary element method,
based on boundary discrete quantities, makes it possible to
distinguish two different boundary types, one in contact as
the zone of potential detachment, called the real boundary,
the other detached as the zone of potential contact, called
the virtual boundary. The contact-detachment problem is
decomposed into two sub-problems: one is purely elastic,
the other regards the contact condition. Following this methodology,
the contact problem, dealtwith using the symmetric
boundary element method, is characterized by symmetry and
in sign definiteness of the matrix coefficients, thus admitting
a unique solution. The solution of the frictionless contact-
detachment problem can be obtained: (i) through an
iterative analysis by a strategy based on a linear complementarity
problem by using boundary nodal quantities as check
quantities in the zones of potential contact or detachment;
(ii) through a quadratic programming problem, based on a
boundary min-max principle for elastic solids, expressed in
terms of nodal relative displacements of the virtual boundary
and nodal forces of the real one
Immunity, Inflammation and Heart Failure: Their Role on Cardiac Function and Iron Status
Aims: Heart failure is a clinical syndrome characterized by subclinical systemic inflammation and immune system activation associated with iron deficiency. No data exist on the various activations of immune-mediated mechanisms of inflammation in heart failure patients with reduced/preserved ejection fraction. We aimed to (1) investigate possible differences in inflammatory parameters and oxidative stress, and (2) detect a different iron status between groups. Materials and Methods: We enrolled 50 consecutive Caucasian outpatients with heart failure. All patients underwent echocardiographic measurements, laboratory determinations, evaluation of iron status and Toll-like receptors, and NF-κB expression in peripheral blood mononuclear cells, as well as pro-inflammatory cytokines. All statistical calculations were made using SPSS for Mac version 21.0. Results: Patients with reduced ejection fraction showed significantly lower hemoglobin levels (12.3 ± 1.4 vs. 13.6 ± 1.4 g/dl), serum iron (61.4 ± 18.3 vs. 93.7 ± 33.7 mcg/dl), transferrin iron binding capacity (20.7 ± 8.4 vs. 31.1 ± 15.6 %), and e-GFR values (78.1 ± 36.1 vs. 118.1 ± 33.9 ml/min/1.73 m2) in comparison to patients with preserved ejection fraction, while unsaturated iron binding capacity (272.6 ± 74.9 vs. 221.7 ± 61.4 mcg/dl), hepcidin (4.61 ± 0.89 vs. 3.28 ± 0.69 ng/ml), and creatinine (1.34 ± 0.55 vs. 1.03 ± 0.25 mg/dl) were significantly higher in the same group. When considering inflammatory parameters, patients with reduced ejection fraction showed significantly higher expression of both Toll-like receptors-2 (1.90 ± 0.97 vs. 1.25 ± 0.76 MFI) and Toll-like receptors-4 (4.54 ± 1.32 vs. 3.38 ± 1.62 MFI), respectively, as well as a significantly higher activity of NF-κB (2.67 ± 0.60 vs. 1.07 ± 0.30). Furthermore, pro-inflammatory cytokines, interleukin-1, and interleukin-6, was significantly higher in patients with reduced ejection fraction, while the protective cytokine interleukin-10 was significantly lower in the same group. Correlational analyses demonstrated a significant and inverse relationship between left ventricular function and inflammatory parameters in patients with reduced ejection fraction, as well as a direct correlation between ferritin and inflammatory parameters. Conclusions: Our data demonstrate a different immune-mediated inflammatory burden in heart failure patients with reduced or preserved ejection fraction, as well as significant differences in iron status. These data contribute to further elucidate pathophysiologic mechanisms leading to cardiac dysfunction
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