Corrección del factor de potencia, sin medida de corriente, mediante implementación en FPGA de one-cycle control

En este artículo se presenta una técnica de control digital de correctores de factor de potencia (CFP) trabajando en modo de conducción continua en la que no es necesario el uso de sensor de corriente ni de convertidor analógico-digital de alta velocidad. La corriente de entrada al CFP se estima a partir de la descripción del modelo en VHDL de un convertidor elevador y de las muestras digitales de las tensiones de entrada y salida del convertidor. El objetivo final es desarrollar un controlador universal para CFP, con posibilidad de trabajar varios convertidores idénticos en paralelo y así aumentar la potencia. En este trabajo se abordan las diferentes soluciones ante los problemas que aparecen en el desarrollo del prototipo de laboratorio y se presentan resultados en diferentes condiciones, comparando el contenido armónico de la corriente con los límites establecidos por la normativa vigente más restrictiv

Towards optimal use of antithrombotic therapy of people with cancer at the end of life: A research protocol for the development and implementation of the SERENITY shared decision support tool

Anticoagulants; Hemorrhage; ThrombosisAnticoagulantes; Hemorragia; TrombosisAnticoagulants; Hemorràgia; TrombosiBackground Even though antithrombotic therapy has probably little or even negative effects on the well-being of people with cancer during their last year of life, deprescribing antithrombotic therapy at the end of life is rare in practice. It is often continued until death, possibly resulting in excess bleeding, an increased disease burden and higher healthcare costs. Methods The SERENITY consortium comprises researchers and clinicians from eight European countries with specialties in different clinical fields, epidemiology and psychology. SERENITY will use a comprehensive approach combining a realist review, flash mob research, epidemiological studies, and qualitative interviews. The results of these studies will be used in a Delphi process to reach a consensus on the optimal design of the shared decision support tool. Next, the shared decision support tool will be tested in a randomised controlled trial. A targeted implementation and dissemination plan will be developed to enable the use of the SERENITY tool across Europe, as well as its incorporation in clinical guidelines and policies. The entire project is funded by Horizon Europe. Results SERENITY will develop an information-driven shared decision support tool that will facilitate treatment decisions regarding the appropriate use of antithrombotic therapy in people with cancer at the end of life. Conclusions We aim to develop an intervention that guides the appropriate use of antithrombotic therapy, prevents bleeding complications, and saves healthcare costs. Hopefully, usage of the tool leads to enhanced empowerment and improved quality of life and treatment satisfaction of people with advanced cancer and their care givers

Determination Of Fluid Viscosity And Femto Newton Forces Of Leishmania Amazonensis Using Optical Tweezers

The displacements of a polystyrene microsphere trapped by an optical tweezers (OT) can be used as a force transducer for mechanical measurements in life sciences such as the measurement of forces of living microorganisms or the viscosity of local fluids. The technique we used allowed us to measure forces on the 200 femto Newtons to 4 pico Newtons range of the protozoa Leishmania amazonensis, responsible for a serious tropical disease. These observations can be used to understand the infection mechanism and chemotaxis of these parasites. The same technique was used to measure viscosities of few microliters sample with agreement with known samples better than 5%. To calibrate the force as a function of the microsphere displacement we first dragged the microsphere in a fluid at known velocity for a broad range of different optical and hydrodynamical parameters. The hydrodynamical model took into account the presence of two walls and the force depends on drag velocity, fluid viscosity and walls proximities, while the optical model in the geometric optics regime depends on the particle and fluid refractive indexes and laser power. To measure the high numerical (NA) aperture laser beam power after the objective we used an integration sphere to avoid the systematic errors of usual power meters for high NA beams. After this careful laser power measurement we obtained an almost 45 degrees straight line for the plot of the optical force (calculated by the particle horizontal displacement) versus hydrodynamic force (calculated by the drag velocity) under variation of all the parameters described below. This means that hydrodynamic models can be used to calibrate optical forces, as we have done for the parasite force measurement, or vice-versa, as we did for the viscosity measurements.593017Ashkin, A., Dziedzic, J.M., Bjorkholm, J.E., Chu, S., Observation of a single-beam gradient force optical trap for dieletric particles (1986) Optics Letters, 11, pp. 288-290Ashkin, A., Dziedzic, J.M., Optical trapping and manipulation of viruses and bacteria (1987) Science, 235, pp. 1517-1520Greulich, K.O., (1999) Micromanipulation by Light in Biology and Medicine, , Basel, Boston, Berlin: BirkhäuserSakata-Sogawa, K., Direct measurement of DNA molecular length in solution using optical tweezers: Detection of looping due to binding protein interactions (1998) Eur. Biophys. J., 27, pp. 55-61Konig, K., Determination of motility forces of human spermatozoa using an 800 nm optical trap (1996) Cell. Mol. Biol., 42, pp. 501-509Barjas-Castro, M.L., Elastic properties of irradiated RBCs measured by optical tweezers (2002) Transfusion, 42, pp. 1196-1199Huruta, R.R., Mechanical properties of stored red blood cells using optical tweezers (1998) Blood, 92, pp. 2975-2977Felgner, H., Muller, O., Schliwa, M., Calibration of light forces in optical tweezers (1995) Appl. Optics, 34, pp. 977-982Svoboda, K., Block, S., Biological applications of optical forces (1994) Annu. Rev. Biophys. Biomolec. Struct., 23, pp. 247-285Henon, S., Lenormand, G., Richert, A., Gallet, F., A new determination of the shear modulus of the human erythrocyte membrane using optical tweezers (1999) Biophys. J., 76, pp. 1145-1151Konig, K., Determination of motility forces of human spermatozoa using an 800nm optical trap (1996) Cell. Mol. Biol., 42, pp. 501-509Who, Whorld Health Organization, 2001Herwaldt, B.L., Leishmanias (1999) Lancet, 354, pp. 1191-1199Killick-Kendrick, R., The life-cycle of Leishmania in the sandfly with special reference to the form infective to the vertebrate host (1990) Ann. Parasitol. Hum. Comp., 65 (1 SUPPL.), pp. 37-42Handman, E., Cell biology of Leishmania (2000) Adv. Parasitol, 44, pp. 1-39Happel, J., Brenner, H., (1991) Low Reynolds Number Hydrodynamics with Special Applications to Particulate Media, , Klumer, Dordrecht(1971) Handbook of Chemistry and Physics, , Chemical Rubber, ClevelandPurcell, E.M., Life at low Reynolds number (1977) Am. J. Phys., 45, pp. 124-13

Adatoms in Graphene

We review the problem of adatoms in graphene under two complementary points of view, scattering theory and strong correlations. We show that in both cases impurity atoms on the graphene surface present effects that are absent in the physics of impurities in ordinary metals. We discuss how to observe these unusual effects with standard experimental probes such as scanning tunneling microscopes, and spin susceptibility.Comment: For the Proceedings of the "Graphene Week 2008" at the ICTP in Trieste, Italy. 8 pages, 8 figure

Random amplification of polymorphic DNA reveals clonal relationships among enteropathogenic Escherichia coli isolated from non-human primates and humans

Enteropathogenic Escherichia coli ( EPEC) strains are important agents of infantile diarrhea all over the world, gaining even greater importance in developing countries. EPEC have also been isolated from various animal species, but most isolates belong to serotypes that differ from those recovered from humans. However, it has been demonstrated that several isolates from non- human primates belong to the serogroups and/ or serotypes related to those implicated in human disease. The objective of this study was to evaluate the genetic differences between thirteen strains isolated from non- human primates and the same number of strains isolated from human infections. Human isolates belonged to the same serogroup/ serotype as the monkey strains and the evaluation was done by analysis of random amplified polymorphic DNA. Dendrogram analysis showed that there was no clustering between human and monkey strains. Human and non- human isolates of the EPEC serotypes O127:H40 and O128:H2 shared 90 and 87% of their bands, respectively, indicating strong genomic similarity between the strains, leading to the speculation that they may have arisen from the same pathogenic clone. To our knowledge, this study is the first one comparing genomic similarity between human and non- human primate strains and the results provide further evidence that monkey EPEC strains correlate with human EPEC, as suggested in a previous investigation

Exact eigenstate analysis of finite-frequency conductivity in graphene

We employ the exact eigenstate basis formalism to study electrical conductivity in graphene, in the presence of short-range diagonal disorder and inter-valley scattering. We find that for disorder strength, $W \ge$ 5, the density of states is flat. We, then, make connection, using the MRG approach, with the work of Abrahams \textit{et al.} and find a very good agreement for disorder strength, $W$ = 5. For low disorder strength, $W$ = 2, we plot the energy-resolved current matrix elements squared for different locations of the Fermi energy from the band centre. We find that the states close to the band centre are more extended and falls of nearly as $1/E_l^{2}$ as we move away from the band centre. Further studies of current matrix elements versus disorder strength suggests a cross-over from weakly localized to a very weakly localized system. We calculate conductivity using Kubo Greenwood formula and show that, for low disorder strength, conductivity is in a good qualitative agreement with the experiments, even for the on-site disorder. The intensity plots of the eigenstates also reveal clear signatures of puddle formation for very small carrier concentration. We also make comparison with square lattice and find that graphene is more easily localized when subject to disorder.Comment: 11 pages,15 figure

Tumor testicular de saco vitelino con metástasis a pleura: primer caso reportado en la literatura

ResumenEl cáncer testicular es el tumor urológico maligno más común en hombres jóvenes. Más del 90% corresponden a tumores de células germinales. El objetivo del estudio es el reporte del primer caso de cáncer testicular de tumores de células germinales con metástasis a pleura.Paciente masculino de 21 años, inicia su padecimiento con dolor en hemitórax derecho; la radiografía de tórax presenta una radioopacidad en lóbulo medio de pulmón derecho y la tomografía de tórax detecta una masa intratorácica y extrapulmonar. La biopsia torácica guiada por ultrasonido muestra una masa sólida adosada a la pared torácica, con efecto de desplazamiento sobre la pleura, conocido como «efecto en cola de cometa». La biopsia fue positiva para lesión neoplásica maligna poco diferenciada de la pleura. A la exploración encontramos testículo derecho con tumoración en polo inferior el cual se corrobora por ultrasonido. Los marcadores tumorales solo con elevación de alfa-fetoproteína 295.87ng/dL y deshidrogenasa láctica en 2,380UI/L. En la tomografía de abdomen se identificó actividad ganglionar interaortocava. Realizamos orquiectomía radical derecha. Reporte patológico: tumor testicular de saco vitelino, pT1N2M1S2.En este caso se pudo comprobar que las metástasis fueron a nivel pleural, que lo ubica como una forma de diseminación excepcional.AbstractTesticular cancer is the most common malignant urologic tumor in young men. More than 90% are germ cell tumors. The aim of this study was to report the first case of germ cell tumor testicular cancer with metastasis to the pleura.A 21-year-old man had disease onset with pain in the right hemithorax. The chest x-ray showed radio-opacity in the middle lobe of the right lung. A chest tomography scan detected an intrathoracic and extrapulmonary mass. Ultrasound-guided thoracic biopsy revealed a solid mass attached to the thoracic wall, displaced over the pleura, known as the “comet tail effect”. The biopsy was positive for a poorly differentiated malignant neoplastic lesion of the pleura. Upon physical examination we encountered a right testis with a tumor at the lower pole; this was corroborated through ultrasound. In relation to tumor markers, only alpha-fetoprotein was elevated at 295.87ng/dl and lactate dehydrogenase at 2,380 IU/l. An abdominal tomography scan identified interaortocaval lymph node activity. We performed a right radical orchiectomy and the pathology report was testicular yolk sac tumor, pT1N2M1S2.In our patient, metastasis at the level of the pleura was confirmed, making this a case with an exceptional form of spread

Magnetic moment of the (rho) meson in light cone QCD

The magnetic moment $\mu$ of the "rho" meson is studied in QCD light cone sum rules, and it is found that "mu = (2.3 pm 0.5)". A comparison of our result on the magnetic moment of the "rho" meson with the predictions of the other approaches, is presented.Comment: 11 pages, 3 figures, LaTeX formatte

Experimental evidence of contamination on the dynamics of shrimp populations: susceptibility to spatial isolation

Landscape-scale ecology comprises complex structures where a flow of energy, materials and organisms among ecosystems conditions the dynamics of populations. Several natural and anthropogenic stressors are likely to affect the landscape composition, generally leading to the rupture of ecological connectivity among populations. Although contamination is considered one of the most threatening factors for biodiversity, its impact on spatial dynamics of populations (e.g., distribution, persistence and abundance) from an eco-toxicological perspective is still unknown. In the current study, the potential effect that contamination can exert on the loss of connectivity among populations (chemically fragmented habitats) leading to population isolation was assessed. The estuarine shrimp Palaemon varians was used as model organisms and a novel version of the HeMHAS (Heterogeneous Multi-Habitat Assay System) was used to simulate spatially heterogeneous landscapes. In order to provide more ecological relevance to the study, besides copper as stressor [at low (0.5 μg/L) and high (25 μg/L) levels], other two factors were simultaneously tested: fish kairomones (as a predation signal) and food availability. Different scenarios were simulated in the HeMHAS to create heterogeneous landscapes that vary depending on the presence or absence of these stressors. The behavior observed by the population of P. varians clearly showed that the shrimp detected copper and avoided the regions with the highest levels of contamination. However, when fish kairomones were added to previously preferred regions, the behavior of shrimp populations did a radical turn: they escape the predator signals, moving towards contaminated regions, but with a clear preference for less contaminated areas. When faced whether to stay in a clean area with no food or moving through disturbed regions to colonize a clean region with food, shrimps’ populations crossed the regions, but with a more dynamic transit in the region with kairomones and no copper. These results indicate that contamination might interfere in the spatial dynamics of shrimps’ populations by: (i) triggering avoidance, (ii) preventing colonization, (iii) isolating populations and (iv) making them more susceptible to local extinction