Experimental Verification of Dielectric Models with a Capacitive Wheatstone Bridge Biosensor for Living Cells: E. coli

Dielectric spectroscopy; E. coli bacteria; Maxwell–Garnet modelEspectroscopia dieléctrica; Bacterias E. coli; Modelo Maxwell-Garnet;Espectroscòpia dielèctrica; Bacteris E. coli; Model Maxwell-GarnetDetection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles' electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate

Clined: collaborative learning for innovative engineering design

El Projecte CLINED s’emmarca en el procés de desenvolupament del mòdul d’aprenentatge interactiu “Array Antennas” en el context de l’assignatura d’Antenes de l’Escola Tècnica Superior Enginyeria de Telecomunicació de Barcelona (ETSETB). Aquest bloc del temari suposa un crèdit ECTS sent els principals objectius en aquest procés d’adaptació: fomentar el treball progressiu de l’estudiant, el seu esperit innovador i creatiu alhora que adquireixi major capacitat de relació entre els models conceptuals explicats i les estructures reals. Per assolir aquestes fites s’ha dut a terme una experiència pilot d’aprenentatge col·laboratiu de forma que es cobreixen els punts esmentats i s’aconsegueixi que l’estudiant tingui un rol més actiu en el seu propi aprenentatge fent que aquest li resulti més atractiu. A més d’aquest pilot realitzat durant el cursos 2004/2005, 2005/2006 y el quatrimestre de tardor 2006, s’han introduït presentacions en power point del tema d’arrays i s’ha posat a disposició de tots els alumnes video-based lectures, i una eina de simulació que els permet fer tan síntesi com anàlisi per l’estudi del comportament d’antenes i les seves agrupacions

Commuting time and the gender gap in labor market participation

This paper investigates the contribution of increasing travel times to the persistent gender gap in labor market participation. In doing so, we estimate the labor supply elasticity of commuting time from a sample of men and women in US cities using microdata from the Census for the last decades. To address endogeneity concerns, we adopt an instrumental variables approach that exploits the shape of cities as an exogenous source of variation for travel times. Our estimates indicate that a 10 minutes increase in commuting decreases the probability of married women to participate in the labor market by 4.6 percentage points. In contrast, the estimated effect on men is small and statistically insignificant. We also find that women with children and immigrant women originating from countries with more gendered social norms respond the most to commuting time variations. This evidence suggests that the higher burden of family responsibilities supported by women may magnify the negative effect of commuting on their labor supply. From our findings, we conclude that the increasing trend in travel times observed in the US and in many European countries during the last decades may have contributed to the persistence of gender disparities in labor market outcomes

Phase-stable source of polarization-entangled photons in a linear double-pass configuration

We demonstrate a compact, robust, and highly efficient source of polarization-entangled photons, based on linear bi-directional down-conversion in a novel 'folded sandwich' configuration. Bi-directionally pumping a single periodically poled KTiOPO$_4$ (ppKTP) crystal with a 405-nm laser diode, we generate entangled photon pairs at the non-degenerate wavelengths 784 nm (signal) and 839 nm (idler), and achieve an unprecedented detection rate of 11.8 kcps for 10.4 $\mu$W of pump power (1.1 million pairs / mW), in a 2.9-nm bandwidth, while maintaining a very high two-photon entanglement quality, with a Bell-state fidelity of $99.3\pm0.3$%

Algoritmo iterativo de propagación espectral para el cálculo de RCS en cavidades conductoras

One of the most difficult problems in the RCS prediction of a complex target is the analysis of the cavities existing at the air inlets and outlets of engines. The geometrical complexity of these structures makes difficult the analysis by modal, ray or beam techniques, while their huge electrical size makes computationally prohibitive the analysis by matrix methods. For these reasons, we have developed an iterative spectral propagation algorithm which can be used to calculate the RCS of electrically intermediate or large cavities with certain geometrical features.Peer ReviewedPostprint (published version

High-frequency RCS of complex radar targets in real time

This paper presents a new and original approach for computing the high-frequency radar cross section (RCS) of complex radar targets in real time with a 3-D graphics workstation. The aircraft is modeled with I-DEAS solid modeling software using a parametric surface approach. High-frequency RCS is obtained through physical optics (PO), method of equivalent currents (MEC), physical theory of diffraction (PTD), and impedance boundary condition (IBC). This method is based on a new and original implementation of high-frequency techniques which the authors have called graphical electromagnetic computing (GRECO). A graphical processing approach of an image of the target at the workstation screen is used to identify the surfaces of the target visible from the radar viewpoint and obtain the unit normal at each point. High-frequency approximations to RCS prediction are then easily computed from the knowledge of the unit normal at the illuminated surfaces of the target. The image of the target at the workstation screen (to be processed by GRECO) can be potentially obtained in real time from the I-DEAS geometric model using the 3-D graphics hardware accelerator of the workstation. Therefore, CPU time for RCS prediction is spent only on the electromagnetic part of the computation, while the more time-consuming geometric model manipulations are left to the graphics hardware. This hybrid graphic-electromagnetic computing (GRECO) results in real-time RCS prediction for complex radar targets.Peer Reviewe

Planar and cylindrical active microwave temperature imaging...

A comparative study at 2.45 GHz concerning both measurement and reconstruction parameters for planar and cylindrical configurations is presented. For the sake of comparison, a numerical model consisting of two nonconcentric cylinders is considered and reconstructed using both geometries from simulated experimental data. The scattered fields and reconstructed images permit extraction of very useful information about dynamic range, sensitivity, resolution, and quantitative image accuracy for the choice of the configuration in a particular application. Both geometries can measure forward and backward scattered fields. The backscattering measurement improves the image resolution and reconstruction in lossy mediums, but, on the other hand, has several dynamic range difficulties. This tradeoff between forward only and forward-backward field measurement is analyzed. As differential temperature imaging is a weakly scattering problem, Born approximation algorithms can be used. The simplicity of Born reconstruction algorithms and the use of FFT make them very attractive for real-time biomedical imaging systems.Peer Reviewe

GRECO: graphical electromagnetic computing for RCS prediction in real time

An innovative approach to computing the high-frequency radar cross sections (RCSs) of complex radar targets in real time, using a 3-D graphics workstation, is presented. The target (typically, an aircraft) is modeled with the I-IDEAS solid-modeling software, using a parametric-surface approach. The high-frequency RCS is obtained through physical optics (PO), the method of equivalent currents (MEC), the physical theory of diffraction (PTD), and the impedance boundary condition (IBC) techniques. The CPU time for the RCS prediction is spent only on the electromagnetic part of the computation, while the more time-consuming geometric-model manipulations are left to the graphics hardware.Peer Reviewe

Sumario breue d la pratica de la arithmetica d[e] todo el curso del arte mercantiuol ...

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