1,195 research outputs found
Dual-PEEC Modeling of a Two-Port TEM Cell for VHF Applications
Two-port TEM cells with rectangular cross section are commonly used to produce plane electromagnetic waves with high electric field. The non-uniform structure makes the use of numerical methods extremely useful in the design phase in order to achieve a very good behavior of the TEM cell over a wide frequency range of operation. In this paper an extended version of PEEC is used to study a real device and results are compared with experimental ones
2D kinematics of the edge-on spiral galaxy ESO 379-G006
We present a kinematical study of the nearly edge-on galaxy ESO 379-G006 that
shows the existence of extraplanar ionized gas. With Fabry-Perot spectroscopy
at H-alpha, we study the kinematics of ESO 379-G006 using velocity maps and
position-velocity diagrams parallel to the major and to the minor axis of the
galaxy. We build the rotation curve of the disk and discuss the role of
projection effects due to the fact of viewing this galaxy nearly edge-on. The
twisting of the isovelocities in the radial velocity field of the disk of ESO
379-G006 as well as the kinematic asymmetries found in some position-velocity
diagrams parallel to the minor axis of the galaxy suggest the existence of
deviations to circular motions in the disk that can be modeled and explained
with the inclusion of a radial inflow probably generated by a bar or by spiral
arms. We succeeded in detecting extraplanar Diffuse Ionized Gas in this galaxy.
At the same time, from the analysis of position-velocity diagrams, we found
some evidence that the extraplanar gas could lag in rotation velocity with
respect to the midplane rotation.Comment: 61 pages, 15 figures. Accepted for publication in A
Increased flexibility in lab-on-chip design with a polymer patchwork approach
Nanofluidic structures are often the key element of many lab-on-chips for biomedical and environmental applications. The demand for these devices to be able to perform increasingly complex tasks triggers a request for increasing the performance of the fabrication methods. Soft lithography and poly(dimethylsiloxane) (PDMS) have since long been the basic ingredients for producing low-cost, biocompatible and flexible devices, replicating nanostructured masters. However, when the desired functionalities require the fabrication of shallow channels, the \u201croof collapse\u201d phenomenon, that can occur when sealing the replica, can impair the device functionalities. In this study, we demonstrate that a \u201cfocused drop-casting\u201d of h-PDMS (hard PDMS) on nanostructured regions, provides the necessary stiffness to avoid roof collapse, without increasing the probability of deep cracks formation, a drawback that shows up in the peel-off step, when h-PDMS is used all over the device area. With this new approach, we efficiently fabricate working devices with reproducible sub-100 nm structures. We verify the absence of roof collapse and deep cracks by optical microscopy and, in order to assess the advantages that are introduced by the proposed technique, the acquired images are compared with those of cracked devices, whose top layer, of h-PDMS, and with those of collapsed devices, made of standard PDMS. The geometry of the critical regions is studied by atomic force microscopy of their resin casts. The electrical resistance of the nanochannels is measured and shown to be compatible with the estimates that can be obtained from the geometry. The simplicity of the method and its reliability make it suitable for increasing the fabrication yield and reducing the costs of nanofluidic polymeric lab-on-chips
A Validated Reversed-Phase HPLC Method for the Determination of Atorvastatin Calcium in Tablets
A Reversed-Phase Liquid Chromatographic (RP-LC) assay method was developed for the quantitative determination of atorvastatin calcium in the presence of its degradation products. The assay involved an isocratic elution of atorvastatin calcium in a LiChroCARTR 250*4 mm HPLC Cartridge LiChrospherR 100 RP-18 (5 ÎŒm) column using a mobile phase consisting of 0.1% acetic acid solution: acetonitrile (45:55, v/v), pH = 3.8. The flow rate was 0.8 mL/min and the analytes monitored at 246 nm. The assay method was found to be linear from 8.13 to 23.77 ÎŒg/mL. All the validation parameters were within the acceptance range. The developed method was successfully applied to estimate the amount of atorvastatin calcium in tablets.Fil: Simionato, Laura Daniela. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; ArgentinaFil: Ferello, L.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; ArgentinaFil: Stamer. S.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; ArgentinaFil: Repetto, M. F.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; ArgentinaFil: Zubata, P. D.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; ArgentinaFil: Segall, Adriana Ines. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂmica. Departamento de TecnologĂa FarmacĂ©utica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; Argentin
Energy in one dimensional linear waves in a string
We consider the energy density and energy transfer in small amplitude,
one-dimensional waves on a string, and find that the common expressions used in
textbooks for the introductory physics with calculus course give wrong results
for some cases, including standing waves. We discuss the origin of the problem,
and how it can be corrected in a way appropriate for the introductory calculus
based physics course.Comment: 5 page
An off-shell I.R. regularization strategy in the analysis of collinear divergences
We present a method for the analysis of singularities of Feynman amplitudes
based on the Speer sector decomposition of the Schwinger parametric integrals
combined with the Mellin-Barnes transform. The sector decomposition method is
described in some details. We suggest the idea of applying the method to the
analysis of collinear singularities in inclusive QCD cross sections in the
mass-less limit regularizing the forward amplitudes by an off-shell choice of
the initial particle momenta. It is shown how the suggested strategy works in
the well known case of the one loop corrections to Deep Inelastic Scattering.Comment: 25 pages, 3 figure
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