768 research outputs found
Simultaneous measurements of electrophoretic and dielectrophoretic forces using optical tweezers
Herein, charged microbeads handled with optical tweezers are used as a
sensitive probe for simultaneous measurements of electrophoretic and
dielectrophoretic forces. We first determine the electric charge carried by a
single bead by keeping it in a predictable uniform electric field produced by
two parallel planar electrodes, then, we examine same bead's response in
proximity to a tip electrode. In this case, besides electric forces, the bead
simultaneously experiences non-negligible dielectrophoretic forces produced by
the strong electric field gradient. The stochastic and deterministic motions of
the trapped bead are theoretically and experimentally analysed in terms of the
autocorrelation function. By fitting the experimental data, we are able to
extract simultaneously the spatial distribution of electrophoretic and
dielectrophoretic forces around the tip. Our approach can be used for
determining actual, total force components in the presence of high-curvature
electrodes or metal scanning probe tips.Comment: 9 pages, 3 figure
Enhancement factor statistics of surface enhanced Raman scattering in multiscale heterostructures of nanoparticles
Suitable metal nanostructures may induce surface-enhanced Raman scattering (SERS) enhancement factors (EFs) large-enough to reach single-molecule sensitivity. However, the gap hot-spot EF probability density function (PDF) has the character of a long-tail distribution, which dramatically mines the reproducibility of SERS experiments. Herein, we carry out electrodynamic calculations based on a 3D finite element method of two plasmonic nanostructures, combined with Monte Carlo simulations of the EF statistics under different external conditions. We compare the PDF produced by a homodimer of nanoparticles with that provided by a self-similar trimer. We show that the PDF is sensitive to the spatial distribution of near-field enhancement specifically supported by the nanostructure geometry. Breaking the symmetry of the plasmonic system is responsible for inducing particular modulations of the PDF tail resembling a multiple Poisson distribution. We also study the influence that molecular diffusion towards the hottest hot-spot, or selective hot-spot targeting, might have on the EF PDF. Our results quantitatively assess the possibility of designing the response of a SERS substrate so as to contain the intrinsic EF PDF variance and significantly improving, in principle, the reproducibility of SERS experiments
Does it pay to be Shariah-compliant? Evidence from the European stock market
The comparison of financial results between different cultural and religious systems is still an open academic debate. There is no consensus among scholars on the existence and magnitude of financial performance differences for companies acting under diverse cultural and religious background. The aim of this paper is to compare the performance of European listed firms applying Shariah principles and those who do not act according to such guidelines. To serve such purpose we have built a sample of companies operating with Shariah-based principles of management and compared the latter with a control comprising companies that do not adopt Shariah parameters over the period 2005–2017. Results suggest that the Shariah-compliant sample performs better than the conventional one. In particular, during the recent recession, Shariah-compliant companies obtained better periodical stock market returns and even in the event of negative returns, losses posted by these companies were lower than those of conventional companies. Moreover, Shariah-compliant sample presents a lower risk-profile than conventional one
Dark spots along slowly scaling chains of plasmonic nanoparticles
We numerically investigate the optical response of slowly scaling linear
chains of mismatched silver nanoparticles. Hybridized plasmon chain resonances
manifest unusual local field distributions around the nanoparticles that result
from symmetry breaking of the geometry. Importantly, we find localization
patterns characterized by bright hot-spots alternated by what we term
\textit{dark} spots. A dark spot is associated to dark plasmons that have
collinear and antiparallel dipole moments along the chain. As a result, the
field amplification in the dark interjunction gap is extinguished for incident
polarization parallel to the chain axis. Despite the strong plasmonic coupling,
the nanoparticles on the sides of this dark gap experience a dramatic
asymmetric field amplification with amplitude gain contrast .
Remarkably, also for polarization orthogonal to the axis, gap hot-spots form on
resonance.Comment: 6 pages, 2 figure
Feasibility Study and Design of a Wearable System-on-a-Chip Pulse Radar for Contactless Cardiopulmonary Monitoring
A new system-on-a-chip radar sensor for next-generation wearable wireless interface applied to the human health care and safeguard is presented. The system overview is provided and the feasibility study of the radar sensor is presented. In detail, the overall system consists of a radar sensor for detecting the heart and breath rates and a low-power IEEE 802.15.4 ZigBee radio interface, which provides a wireless data link with remote data acquisition and control units. In particular, the pulse radar exploits 3.1–10.6 GHz ultra-wideband signals which allow a significant reduction of the transceiver complexity and then of its power consumption. The operating principle of the radar for the cardiopulmonary monitoring is highlighted and the results of the system analysis are reported. Moreover, the results obtained from the building-blocks design, the channel measurement, and the ultra-wideband antenna realization are reported
Congenital musculoskeletal abnormalities associated with aortic, pulmonary and iliac aneurysms
We present the case of a young patient with severe congenital musculoskeletal abnormalities.
associated with different pathologies, with involvement of the arterial tree on both the systemic
and pulmonary circulation, and involvement of the lungs due to thoracic hypoplasia. The
presence of such extensive pathology raises the question of the suitability of such patients to
undergo major corrective cardiac surgery procedures. (Cardiol J 2010; 17, 4: 412-414
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