476 research outputs found
Design, manufacture and characterization of compact filter assemblies for radiofrequency applications
This paper presents the use of additive manufacturing in the design and fabrication of a non-planar fully 3Dprinted low-pass filter. The process implements stereolithographic 3D printing and copper electroplating to produce the necessary parts and their casing. The filter we produce acts as a demonstrator: we present the possibility of constructing building blocks and combining different elements into a full assembly for system integration. We introduce the "drop-and-screw" concept, which is implemented to mount the parts into a single connectorized assembly without the need for welding. The method we propose may be suitable for building other components by simply changing the building blocks. We pay special attention to the design of the constituent parts of the filter (a 3D conical inductor and a 3D capacitor), exploring new geometries to reduce the size of the final filter prototypes. The results demonstrate the potential of additive manufacturing in the construction of high-performance RF components and assemblies, and we present a modular prototype with a high degree of reconfigurability and multifunctionality
Monte Carlo simulation of damage and amorphization induced by swift-ion irradiation in LiNbO3
This paper presents a Monte Carlo (MC) simulation tool which is applied to describe the ion beam induced damage generated by electronic excitation in LiNbO3. Based on a previously published thermal spike based analytical model, the MC technique allows for a more flexible and accurate treatment of the problem. A main advantage of this approach with respect to the analytical one is the possibility of studying the role of statistical fluctuations, relevant at low fluences. The paper recalls the main features of the physical model, describes the MC algorithm, and compares simulation results to experimental data (irradiations of LiNbO3 using silicon ions at 5 and 7.5 MeV and oxygen ions at 5 MeV). © 2006 American Institute of Physics.Peer Reviewe
Monte Carlo simulation of damage and amorphization induced by swift-ion irradiation in LiNbO3
This paper presents a Monte Carlo (MC) simulation tool which is applied to describe the ion beam induced damage generated by electronic excitation in LiNbO3. Based on a previously published thermal spike based analytical model, the MC technique allows for a more flexible and accurate treatment of the problem. A main advantage of this approach with respect to the analytical one is the possibility of studying the role of statistical fluctuations, relevant at low fluences. The paper recalls the main features of the physical model, describes the MC algorithm, and compares simulation results to experimental data (irradiations of LiNbO3 using silicon ions at 5 and 7.5 MeV and oxygen ions at 5 MeV). © 2006 American Institute of Physics.Peer Reviewe
Analysis and Optimization of Multi-Winding Toroidal Inductors for Use in Multilayered Technologies
The aim of this paper is to compare the performance of planar toroidal inductors and circular spiral inductors in multilayered technologies, in terms of achievable inductance density. New multi-winding toroidal inductor geometry is proposed to cover as much of the integration area as possible with the component footprint. The optimization of planar multi-winding toroidal inductors in multilayered substrates is investigated theoretically, and closed formulae are derived for their inductances as a function of geometrical parameters for any given value of the number of windings in the coil. The model obtained is validated experimentally and through electromagnetic simulation. Comparing the inductance of multi-winding toroidal inductors and compact spiral inductors allows us to update previously reported selection rules for the most suitable topology that leads to the most compact design
Generation of high-confinement step-like optical waveguides in LiNbO3 by swift heavy ion-beam irradiation
3 pages, 4 figures, 1 table.We demonstrate a swift ion-beam irradiation procedure based on electronic (not nuclear) excitation to generate a large index jump step-like optical waveguide (În0 â 0.2,âÎne â 0.1) in LiNbO3. The method uses medium-mass ions with a kinetic energy high enough to assure that their electronic stopping power Se(z) reaches a maximum value close to the amorphous (latent) track threshold inside the crystal. Fluorine ions of 20 and 22âMeV and fluences in the range (1â30)Ă1014 are used for this work. A buried amorphous layer having a low refractive index (2.10 at a wavelength of 633ânm) is then generated at a controlled depth in LiNbO3, whose thickness is also tuned by irradiation fluence. The layer left at the surface remains crystalline and constitutes the core of the optical waveguide which, moreover, is several microns far from the end of the ion range. The waveguides show, after annealing at 300â°C, low propagation losses ( â 1âdB/cm) and a high second-harmonic generation coefficient (50%â80% of that for bulk unirradiated LiNbO3, depending on the fluence). The formation and structure of the amorphous layer has been monitored by additional Rutherford backscattering/channeling experiments.We acknowledge the funding of the project MAT2002â
03220 (MEC). A. GarcĂa-Navarro acknowledges the financial
support of the MEC through a FPU Fellowship and of
the Madrid City Hall-Residencia de Estudiantes.Peer reviewe
Distribution of melanopsin positive neurons in pigmented and albino mice: evidence for melanopsin interneurons in the mouse retina.
Here we have studied the population of intrinsically photosensitive retinal ganglion cells (ipRGCs) in adult pigmented and albino mice. Our data show that although pigmented (C57Bl/6) and albino (Swiss) mice have a similar total number of ipRGCs, their distribution is slightly different: while in pigmented mice ipRGCs are more abundant in the temporal retina, in albinos the ipRGCs are more abundant in superior retina. In both strains, ipRGCs are located in the retinal periphery, in the areas of lower Brn3a(+)RGC density. Both strains also contain displaced ipRGCs (d-ipRGCs) in the inner nuclear layer (INL) that account for 14% of total ipRGCs in pigmented mice and 5% in albinos. Tracing from both superior colliculli shows that 98% (pigmented) and 97% (albino) of the total ipRGCs, become retrogradely labeled, while double immunodetection of melanopsin and Brn3a confirms that few ipRGCs express this transcription factor in mice. Rather surprisingly, application of a retrograde tracer to the optic nerve (ON) labels all ipRGCs, except for a sub-population of the d-ipRGCs (14% in pigmented and 28% in albino, respectively) and melanopsin positive cells residing in the ciliary marginal zone (CMZ) of the retina. In the CMZ, between 20% (pigmented) and 24% (albino) of the melanopsin positive cells are unlabeled by the tracer and we suggest that this may be because they fail to send an axon into the ON. As such, this study provides the first evidence for a population of melanopsin interneurons in the mammalian retina
Innovation capabilities in health organizations. Proposal of a model through structural equation models
El presente trabajo pretende encontrar los determinantes de las capacidades de innovaciĂłn en las organizaciones dedicadas al cuidado de la salud. En primer lugar, se elaborĂł el modelo estructural y de medida que diera cuenta de las relaciones entre las variables latentes y las manifiestas. Como segundo aspecto se identificĂł el modelo. Posteriormente se procediĂł a calcular los Ăndices de ajuste y mediante algunas tĂ©cnicas de mĂ©todos multivariados; se analizaron las ĂĄreas del mismo que no se ajustaban adecuadamente para intervenirlas y asĂ conseguir un Ăłptimo ajuste. TambiĂ©n se plantearon algunas hipĂłtesis que nos permitieran probar las relaciones de causalidad positiva entre las Capacidades de InnovaciĂłn y las variables. Respecto a la muestra, se logrĂł tener un total de 283 observaciones extraĂdas de la red de hospitales de alta complejidad en Colombia durante los años 2016 y 2017. Se obtuvo un modelo con un ajuste significativo y que diera cuenta de los detonantes de las Capacidades de InnovaciĂłn en las organizaciones de salud. Finalmente se demostrĂł la incidencia positiva que tiene la gestiĂłn del conocimiento, del talento humano, las capacidades directivas, la cultura organizacional y algunos factores asociados a la organizaciĂłn de salud sobre dichas capacidadesIn the present work, we try to find the determinants of innovation capabilities in the health care organizations. Firstly, the structural and measurement model was elaborated to account the relations between the latent variables and the manifest ones. Secondly, the model was identified; subsequent to this, we proceeded to calculate the adjustment indexes and using some techniques of multivariate methods. Then, we analyzed the areas of the model that did not fit properly to intervene them and thus achieve an optimal adjustment. We proposed some hypothesis that allowed us to prove positive causal relationships between the Innovation Capabilities and the variables. We had 283 observations extracted from the network of high complexity hospitals in Colombia during the years 2016 and 2017. A model with a significant adjustment that would account for the triggers of Innovation Capabilities in health care organizations was obtained. Finally, the positive impact of knowledge management, human resource management, management capabilities, organizational culture, and some factors associated with the health care Organizations on Innovation Capabilities was demonstratedUniversidad Pablo de Olavid
Use of antifungal Saponin SC-2 of Solanum chrysotrichum for the treatment of vulvovaginal candidiasis: in vitro studies and clinical experiences
Saponin SC-2 from Solanum chrysotrichum showed antifungal activity, demonstrated in vitro, which inhibited the growth of dermatophytes, and in vivo, to be effective in the treatment against tinea pedis and pityriasis capitis. Fungistatic and fungicidal activity of saponin SC-2 on Candida albicans and other Candida species, fluconazole and ketoconazole resistaent strains was demostrated. SC-2-associated ultrastructural alterations in several Candida species were observed. An exploratoryclinical, randomized, double-blind, and controlled ketoconazole study of ketoconazole was conducted with the aim of assessing the effectiveness and tolerability of an herbal medicinal product containing SC-2, on women with Vulvovaginal candidiasis (VVC). The results exhibited a percentage of therapeutic clinical effectiveness similar to that of ketoconazole (X2, p .0.30), but obtained a smaller percentage of mycological effectiveness, and 100% tolerability. In conclusion, saponin SC-2 possesses fungicidale and fungistatic activity on Candida albicans and other multi resistant Candida species, causes morphological changes and fungal death, and it is an alternative therapy for the treatment of VVC.Key words: Solanum chrysotrichum, saponins, antifungal activity, vulvovaginal candidiasis, alternative therapy
VP2 potentiates the proteccion induced by VP6 against the rotavirus infection in a DNA vaccine model
Viruses like particles (VLPs) composed of VP2/VP6 are very effective in inducing protection against the rotavirus infection in animal models. Individually, VP6 also can induce protection against the infection; however, there is no information about the immunogenicity of VP2. The aim of this work was to evaluate the efficacy of DNA vaccines that codify for VP2 and VP6 alone or combined to induce protection against the rotavirus infection. Murine rotavirus VP2 and VP6 genes were cloned into the pCDNA-3 vector. Adult BALB/c mice were inoculated 3 times by intramuscular injections with 100 or 200 mg of pCDNA-3VP2 and pCDNA-3VP6, alone or combined. Two weeks after the last inoculation, mice were challenged with the murine rotavirus EDIM. We found that both plasmids pCDNA-3VP2 and pCDNA-3VP6 were able to induce rotavirus-specific serum antibodies, but not intestinal rotavirus-specific IgA. Only pCDNA-3VP6 at 200 mg could induce 30 % protection against the infection. Co-administration of 100 mg of pCDNA-3VP2 with 100 mg of pCDNA-3VP6 induced 35 % protection. When different ratios of pCDNA-3VP2/pCDNA-3VP6 were used, it was found that the co-administration of 10 ”g pCDNA-3VP2/ 100 ”g pCDNA-3VP6 gave the best result with up to 55 % protection. These results indicate that the DNA plasmid expressing VP6 is a better vaccine candidate that the one expressing VP2 but co-administration of both plasmids is a good alternative to potentiate the protection induced by VP6, probably by the formation of VLPs VP2/VP6 in vivo
Geomagnetic anomalies observed at volcano Popocatepetl, Mexico
International audienceResults of the ULF geomagnetic monitoring of the volcano Popocatepetl (Mexico) and their analysis are summarized and presented for the period 2003?2006. Our analysis reveals some anomalies which are considered to be of local volcanic origin: the EM background in the vicinity of the volcano was found to be significantly noisier than at other reference stations; sporadic strong noise-like geomagnetic activity was observed in the H-component; some geomagnetic pulsations were observed only at the Tlamacas station (located at 4 km near the volcano). The results are discussed in terms of a physical mechanism involving the presence of a second magmatic chamber within the volcano and, finally, further perspective directions to study volcanic geodynamical processes besides the traditional ones are given
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