Fabrication and Comprehensive Modeling of Ion-Exchanged Bragg Opitcal Add-Drop Multiplexers

Optical add–drop multiplexers (OADMs) based on asymmetric Y branches and tilted gratings offer excellent-performance in wavelength-division multiplexed systems. To simplify waveguide fabrication, ion-exchange techniques appear to be an important option in photosensitive glasses. Optimum OADM performance depends on how accurately the waveguide fabrication process and tilted Bragg grating operation are understood and modeled. Results from fabrication and comprehensive modeling are compared for ion-exchange processes that use different angles of the tilted grating. The transmission and reflection spectra for the fabricated and simulated OADMs show excellent agreement. The OADM’s performance is evaluated in terms of the measured characteristics of the Y branches and tilted gratings

Universal scaling of current fluctuations in disordered graphene

We analyze the full transport statistics of graphene with smooth disorder at low dopings. First we consider the case of 1D disorder for which the transmission probability distribution is given analytically in terms of the graphene-specific mean free path. All current cumulants are shown to scale with system parameters (doping, size, disorder strength and correlation length) in an identical fashion for large enough systems. In the case of 2D disorder, numerical evidence is given for the same kind of identical scaling of all current cumulants, so that the ratio of any two such cumulants is universal. Specific universal values are given for the Fano factor, which is smaller than the pseudodiffusive value of ballistic graphene (F=1/3) both for 1D (F=0.243) and 2D (F=0.295) disorder. On the other hand, conductivity in wide samples is shown to grow without saturation as \sqrt{L} and Log L with system length L in the 1D and 2D cases respectively.Comment: 9 pages, 7 figures. Published version, includes corrected figure for Fano facto

Mastitis diagnosis in ten Galician dairy herds (NW Spain) with automatic milking systems

Over the last few years, the adoption of automatic milking systems (AMS) has experienced significant increase. However, hardly any studies have been conducted to investigate the distribution of mastitis pathogens in dairy herds with AMS. Because quick mastitis detection in AMS is very important, the primary objective of this study was to determine operational reliability and sensibility of mastitis detection systems from AMS. Additionally, the frequency of pathogen-specific was determined. For this purpose, 228 cows from ten farms in Galicia (NW Spain) using this system were investigated. The California Mastitis Test (CMT) was considered the gold-standard test for mastitis diagnosis and milk samples were analysed from CMT-positive cows for the bacterial examination. Mean farm prevalence of clinical mastitis was 9% and of 912 milk quarters examined, 23% were positive to the AMS mastitis detection system and 35% were positive to the CMT. The majority of CMT-positive samples had a score of 1 or 2 on a 1 (lowest mastitis severity) to 4 (highest mastitis severity) scale. The average sensitivity and specificity of the AMS mastitis detection system were 58.2% and 94.0% respectively being similar to other previous studies, what could suggest limitations for getting higher values of reliability and sensibility in the current AMSs. The most frequently isolated pathogens were Streptococcus dysgalactiae (8.8%), followed by Streptococcus uberis (8.3%) and Staphylococcus aureus (3.3%). The relatively high prevalence of these pathogens indicates suboptimal cleaning and disinfection of teat dipping cups, brushes and milk liners in dairy farms with AMS in the present study

Seeking theta's desperately: Estimating the distribution of consumers under increasing block rates

This paper shows that the distribution of observed consumption is not a good proxy for the distribution of heterogeneous consumers when the current tariff is an increasing block tariff. We use a two step method to recover the "true" distribution of consumers. First, we estimate the demand function induced by the current tariff. Second, using the demand system, we specify the distribution of consumers as a function of observed consumption to recover the true distribution. Finally, we design a new two-part tariff which allows us to evaluate the equity of the existence of an increasing block tariff.Heterogeneous demand, nonlinear pricing

Matrix metalloproteinases: Targets for doxycycline to prevent the vascular alterations of hypertension

AbstractHypertension is associated with well known structural and functional alterations in both resistance and conduit arteries, which may be the result from long-lasting high blood pressure and may also be the cause of maintained hypertension and its complications. Therefore, in addition to lowering blood pressure, therapeutic strategies targeting the structural and functional modifications found in hypertensive patients may prevent the cardiovascular events and decrease the death rates associated with hypertension. Mounting evidence indicates that many vascular alterations associated with sustained hypertension are due to imbalanced matrix metalloproteinases (MMPs), a family of zinc-endopeptidases that degrade not only proteins of extracellular matrix (ECM) but several other substrates. Recent observations showed that abnormal MMP activity is a feature of the pathogenesis of hypertension and other diseases, thus justifying the development of drugs aiming at MMP downregulation. This review focuses on the extracellular actions of MMPs in hypertension-induced chronic vascular alterations. We then discuss the effects of MMP inhibitors, especially doxycycline, on the vascular changes associated with hypertension. There is now strong evidence that MMP inhibition with doxycycline (and maybe other MMP inhibitors) may attenuate the functional and structural alterations associated with hypertension, including increases in arterial stiffness. These beneficial effects may be, at least in part, independent of their antihypertensive effects

Doryctopambolus nunes & Zaldívar-Riverón (Braconidae), a new Neotropical doryctine wasp genus with propodeal spines

The new Neotropical doryctine genus Doryctopambolus gen. n. is erected to contain D. pilcomayensis (van Achterberg & Braet, 2004), comb. n., which was previously placed within Pambolus (Pambolinae), as well as three new species, D. clebschi sp. n., D. dominicanus sp. n. and D. sarochensis sp. n. Membersof this new genus are mainly characterised by the presence of at least one pair of conspicuous propodeal apico-lateral projections, which are similar to those present in all members of Pambolinae and in species of three Australasian doryctine genera. We generated DNA barcoding sequences for the three newly described species. We discuss the morphological similarity between species of the Australasian Echinodoryctes Belokobylskij, Iqbal & Austin and Doryctopambolus. A key for the described species of Doryctopambolus is provided.Fil: Nunes, Juliano Fiorelini. Universidade Federal de Minas Gerais; BrasilFil: Zaldívar Riverón, Alejandro. Universidad Nacional Autónoma de México; MéxicoFil: de Castro, Clóvis Sormus. Universidade Federal do São Carlos; BrasilFil: Marsh, Paul M.. No especifica;Fil: Penteado Dias, Angélica Maria. Universidade Federal do São Carlos; BrasilFil: Briceño, Rosa. Universidad Centroccidental Lissandro Alvarado; VenezuelaFil: Martinez, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

Planificacion y mantencion de una maquina centrifuga continua K850 S, ubicada en Planta IANSA-CURICO

178 p.La constante renovación y los continuos avances tecnológicos hacen de las máquinas un punto de vital importancia, dentro del proceso productivo de una industria. En Chile, solo las grandes industrias han dado importancia a la mantención que sus plantas productivas mediante una mantención preventiva de ellas. En cambio, en la mediana y pequeña industria se ha adaptado la modalidad de reparar cuando las fallas se presentan, sin haberlas previsto. Debido a la gran importancia que una maquinaria cumple dentro de un proceso productivo industrial, el estudio de esta tesis comprenderá las maquinas centrifugas K850 S, por ser estas de gran importancia en la elaboración del azúcar. Las Máquinas centrífugas son empleadas mundialmente en las industrias azucareras, para se-parar los cristales de azúcar del siropo madre en una masa cocida. Esta preparación se realiza mediante el uso de la fuerza centrífuga, el Tes. elegido surgió debido a la posibilidad que tuvimos de ingresar a la Planta IANSA de Curico, la que se hallaba en pleno periodo de mantención. La tesis se desarrollara en cuatro capítulos, En el primer capítulo se analiza el proceso industrial Para la elaboración del azúcar y la función de la centrífuga dentro del proceso. En el segundo capítulo se da a conocer la planificación actual en Planta IANSA Curico, y se propone además una planificación de la mantención para la Planta. El Capítulo tercero consta de un estudio de la mantención en forma teórica, describiendo los diferentes tipos de mantención. Posteriormente se da a conocer la mantención que actualmente se realiza en la Planta a la Centrífuga F850 S, y además se dan a conocer las consideraciones que se deben tomar en cuenta para implementar un Plan de Mantención preventiva. También en este capítulo se propone un nuevo plan de mantenimiento para la Centrífuga K850 S. En el capítulo cuarto se hace un estudio económico de la mantención actual y mantención propuesta; se calcula también la depreciación de la maquina por dos métodos y se compara con los costos de mantención actual y propuestas