Monolithic low phase noise oscillators for moderate frequency applications

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (leaves 74-75).Low noise oscillators are critical building blocks in a wide range of commercial electronics. Increased levels of integration have created a strong need for integrated oscillator solutions despite generally inferior noise performance. The development of non-linear noise models that can accurately and efficiently predict noise in ring oscillators aids designers in optimizing noise performance in integrated oscillator solutions. Extending a piecewise constant model of noise in an oscillator and the resulting timing jitter reveals how the noise at the oscillator nodes changes during each portion of the cycle. The model can then be used to examine the effects of changing various process and design parameters such as threshold voltages and the effective stage gain. This analysis tool provides a means for designers to evaluate potential improvements of their oscillator design. In some cases approximate analytic solutions can be found that provide better insight into the timing jitter. A simple differential oscillator design illustrates the use of this analysis. The oscillator achieves an analog tuning range of 259MHz-314MHz (extendable with switched capacitors) with a normalized jitter of 102ppm.by Rafael A. Medina.M.Eng

Cross-protection of commercial vaccines against Chilean swine influenza A virus using the guinea pig model as a surrogate

Influenza A virus poses a significant threat to public health and the swine industry. Vaccination is the primary measure for controlling the disease, but the effectiveness of vaccines can vary depending on the antigenic match between vaccine strains and circulating strains. In Chile, H1N1pdm09 and other lineages H1N2 and H3N2 have been detected in pigs, which are genetically distinct from the strains included in commercial vaccines. This study aimed to evaluate the cross-protection by commercial vaccines against strains circulating in Chile using the guinea pig model. For this study, four circulating strains [A/swine/Chile/H1A-7/2014(H1N2), A/swine/Chile/H1B-2/2014(H1N2), A/swine/Chile/H1P-12/2015(H1N1), and A/swine/Chile/H3-2/2015(H3N2)] were selected. Guinea pigs were divided into vaccinated and control groups. The vaccinated animals received either a multivalent antigenically heterologous or monovalent homologous vaccine, while the control animals remained unvaccinated. Following vaccination, all animals were intranasally challenged, and nasal wash samples were collected at different time points post-infection. The results showed that the homologous monovalent vaccine-induced hemagglutinin-specific antibodies against the Chilean pandemic H1N1pdm09 strain. However, the commercial heterologous multivalent vaccine failed to induce hemagglutinin-specific antibody titers against the H1N2 and H3N2 challenge strains. Furthermore, the homologous monovalent vaccine significantly reduced the duration of viral shedding and viral titers specifically against the Chilean pandemic H1N1pdm09 strain and heterologous multivalent vaccine only partial. These findings highlight the importance of regularly updating vaccine strains to match the circulating field strains for effective control of swine influenza. Further research is needed to develop vaccines that confer broader protection against diverse strains of swine influenza A virus

microRNA Expression Profiling in Young Prostate Cancer Patients

MicroRNAs (miRNAs) are small, non-coding RNA molecules with multiple roles in many biological processes. Few studies have shown the molecular characteristics in younger prostate cancer (PCa) patients. In this study, we performed miRNA profiling in young PCa (EO-PCa) cases compared with PCa arising in older men (LO-PCa).Experimental Design: Formalin-fixed, paraffin embedded tissue was used. miRNA was extracted for PCR array and NanoString methods. Relative miRNAs expression levels were obtained by comparing young vs older men, and young PCa tumor samples vs normal epithelium.Results: miRNA profiling showed a different expression pattern in PCa arising in younger men, and young PCa tumoral and its normal counterpart. Nine miRNAs (hsa-miR-140-5p, hsa-miR-146a, hsa-miR-29b, hsa-miR-9, hsa-miR-124-3p, hsa-let-7f-5p, hsa-miR-184, hsa-miR-373, hsa-miR-146b-5p) showed differences in the expression compared to LO-PCa. Fourteen miRNAs were significantly up-regulated (miR-1973, miR-663a, miR-575, miR-93-5p, miR-630, miR-600, miR-494, miR-150-5p, miR-137, miR-25-3p, miR-375, miR-489, miR-888-5p, miR-142-3p), while 9 were found down-regulated (miR-21-5p, miR-363-3p, miR-205-5p, miR-548ai, miR-3195, 145-5p, miR-143-3p, miR-222-3p, miR-221-3p) comparing young PCa tumoral tissue compared to normal counterpart. The higher expression of miR-600 and miR-137 were associated with high Gleason score, extraprostatic extension and lymphatic invasion.Conclusion: These results suggest that PCa in younger patients has a different expression profile compared to normal tissue and PCa arising in older man. Differentially expressed miRNAs provide insights of molecular mechanisms involve in this PCa subtype

Magneto-Conductance Anisotropy and Interference Effects in Variable Range Hopping

We investigate the magneto-conductance (MC) anisotropy in the variable range hopping regime, caused by quantum interference effects in three dimensions. When no spin-orbit scattering is included, there is an increase in the localization length (as in two dimensions), producing a large positive MC. By contrast, with spin-orbit scattering present, there is no change in the localization length, and only a small increase in the overall tunneling amplitude. The numerical data for small magnetic fields $B$, and hopping lengths $t$, can be collapsed by using scaling variables $B_\perp t^{3/2}$, and $B_\parallel t$ in the perpendicular and parallel field orientations respectively. This is in agreement with the flux through a `cigar'--shaped region with a diffusive transverse dimension proportional to $\sqrt{t}$. If a single hop dominates the conductivity of the sample, this leads to a characteristic orientational `finger print' for the MC anisotropy. However, we estimate that many hops contribute to conductivity of typical samples, and thus averaging over critical hop orientations renders the bulk sample isotropic, as seen experimentally. Anisotropy appears for thin films, when the length of the hop is comparable to the thickness. The hops are then restricted to align with the sample plane, leading to different MC behaviors parallel and perpendicular to it, even after averaging over many hops. We predict the variations of such anisotropy with both the hop size and the magnetic field strength. An orientational bias produced by strong electric fields will also lead to MC anisotropy.Comment: 24 pages, RevTex, 9 postscript figures uuencoded Submitted to PR

Fe-Containing MOFs as Seeds for the Preparation of Highly Active Fe/Al-SBA-15 Catalysts in the N-Alkylation of Aniline

We have successfully incorporated iron species into mesoporous aluminosilicates (AlSBA15) using a simple mechanochemical milling method. The catalysts were characterized by nitrogen physisorption, inductively coupled plasma mass spectrometry (ICP-MS), pyridine (PY) and 2,6-dimethylpyridine (DMPY) pulse chromatography titration, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The catalysts were tested in the N-alkylation reaction of aniline with benzyl alcohol for imine production. According to the results, the iron sources, acidity of catalyst and reaction conditions were important factors influencing the reaction. The catalyst showed excellent catalytic performance, achieving 97% of aniline conversion and 96% of imine selectivity under optimized conditions

Quantitative determination of amino acids in earthworm meal (Eisenia andrei) by a Surveyor HPLC system in conjunction with pre-column 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization

Aim: The objective of this study was to evaluate the integration of the AccQ•Tag derivatization system with the Finnigan Surveyor Plus HPLC system to determine the amino acids (aa) composition of earthworm meal protein post-hydrolysis. Materials and Methods: In lab cultivated earthworms (Eisenia andrei) were reduced to flour which was then hydrolyzed with 6M HCl at 110 °C for 24 hours in a closed system. The hydrolysis product was neutralized and their aa were derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). The derivatized-aa were separated by RP-HPLC and detected by fluorescence. Results and Conclusion: The proposed integration makes optimal use of both the modular design of the Surveyor Plus HPLC for versatility and flexibility and the main features of the AccQ•Tag derivatization system in terms of stability and reproducibility. Analytical validation parameters were studied both before and after derivatization with AQC. The resulting data were within acceptable ranges for this type of analysis. Pre-column derivatization with AQC yielded appropriate sensitivities within the low pmol range per injection. Earthworm meal generated the following aa; the most abundant (w/w) being: Glu, Asp, Arg, Leu, and Lys (4 % - 10 %), whereas the lowest content corresponded to Met (< 1. 5%), which is comparable to fishmeal. The analytical proposal can be used with confidence in earthworm meal quality control to guarantee the appropriate aa content to create an optimum fish diet.Objetivo. Evaluar la integración del sistema de derivatización AccQ•Tag en conjunción con el sistema de cromatografía CLAR Finnigan Surveyor Plus en la determinación de la composición de aminoácidos (aa) de las proteínas de harina de lombriz posterior a la hidrólisis. Material y Método. Las lombrices de tierra (Eisenia andrei) fueron criadas en condiciones de laboratorio, reducidas a harina e hidrolizadas con HCl 6 M a 110ºC por 24 horas en un sistema cerrado. El producto de la hidrólisis se neutralizó y los aa se derivatizaron con 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Los aminoácidos derivatizados se separaron por cromatografía liquida de alta resolución (CLAR) en FR y se detectaron por fluorescencia. Resultados y Conclusiones. La integración propuesta conformada por el diseño modular del sistema CLAR Surveyor Plus (versatilidad y flexibilidad) y las principales características del sistema de derivación AccQ•Tag (estabilidad y reproducibilidad) resultó óptima. Los parámetros analíticos de validación fueron estudiados antes y después de la derivatización con AQC originando datos dentro de los intervalos aceptables, incluyendo un límite de cuantificación en el orden de pmol por inyección. Los aminoacidos más abundantes (m/m) en la harina de lombriz fueron: Glu, Asp, Arg, Leu y Lys (4 % - 10 %), mientras que el contenido más bajo correspondió a Met (< 1,5 %), pero comparable a la harina de pescado. La propuesta de análisis se puede utilizar con seguridad en el control de calidad de la harina de lombriz de tierra con el fin de garantizar el contenido apropiado de aa para crear una dieta óptima para peces.1.- Fondo Nacional de Ciencia y Tecnología (FONACIT) del MCT de Venezuela. Proyectos: G2005000869, G2008001102 y G-2014000010.2.- El Consejo de Desarrollo Científico, Humanístico, Tecnológico y de las Artes (CDCHTA), de la Universidad de Los Andes. Mérida, Venezuela, Proyecto Nº FA-434-08-03-ED, FA-492-11-08-A y FA-511-12-08-B

Improved diagnostics and surveillance identify novel reassortant swine influenza A viruses in Chile

Influenza A Virus (IAV) circulates endemically in nature, representing a constant concern to public health and animal production systems worldwide. The emergence of the 2009 H1N1 influenza A pandemic (A(H1N1)pdm09) highlighted the need of conducting systematic surveillance studies, and evidenced the significant gap of knowledge of the swine IAVs (SwIAV) circulating in pigs worldwide at the time of the outbreak. This also highlighted the role of swine as important reservoirs for the generation of endemic strains with zoonotic and pandemic potential. Despite this, comprehensive information of SwIAV circulating in Latin America is still lacking. While Chile has strong ecological barriers and high stringency controls regarding livestock trading, IAV is endemic and has been consistently detected in pigs. This has caused great concerns for the swine industry, because of the on-going clinical and production losses. Nevertheless, few surveillance efforts have been conducted in Chile and there is limited information regarding the genetic diversity and origin of swIAVs. Determining the viral subtypes and genotypes circulating in swine is key for the development of appropriate vaccine approaches and control measures for the swine industry, and it is crucial for identifying novel strains with pandemic potential. We developed improved diagnostic tools to detect endemic viruses and characterized the diversity and origin of SwAIV and its prevalence in Chilean swine production farms. From December 2013 to June 2015, we sampled 27 farms representative of intensive swine production systems located between the Valparaiso and Araucania administrative regions. Animals were mainly found to be susceptible to IAV infection at 50 to 110 days of age. Serological analysis of 718 serum samples obtained from 3 different farms showed 91-59% prevalence to SwIAV, with 18-67% positivity to A(H1N1)pdm09-like strains and 29-58% positivity to a novel SwH1N2 virus. We also obtained a total of 1016 nasal swabs (NS, 85%) and 176 oral fluids (OF, 15%) that were tested by Real-time RT-PCR (qPCR) and virus isolation. Of these, 295 samples (25%) were positive to swIAV (23% of NS and 38% of OF). A large number of farms (21 out of 27, 78%) were positive in at least one visit, and most farms showed temporal co-circulation of at least 2 viruses or mixed infections. We subtyped selected positive samples and sequenced 51 complete viral genomes using the Illumina platform. Nineteen additional hemagglutinins (HA) genes were sequenced by Sanger. We performed Bayesian Evolutionary Analyses to reconstruct the phylogenies of the viral segments. This identified the circulation of 2 predominant swIAV genotypes in Chile, the A(H1N1)pdm09-like (35%) strain and a novel SwH1N2 virus (45%). This H1N2 virus is unique to Chile since it is genetically distinct from the H1 virus clusters seen in North America and is not related to any previously reported IAV. The genome of this swH1N1 virus contains genes from 3 different human contemporary viruses. Its H1 and N2 genes are derived from human H1N1 and H3N2 viruses from the mid 90’s, respectively, suggesting that both of these human viruses were likely introduced into the Chilean swine population during that time. All the internal genes are from the A(H1N1)pdm09 strain, indicating that multiple and recent reassortment events gave rise to this novel reassortant virus. Of interest, we identified additional reassortant viruses that also contain the internal genes derived from the A(H1N1)pdm09 strain. These included an H1N1 containing the novel SwH1 and NA gene derived from the A(H1N1)pdm09-like strain, an H1N2 virus containing an H1 derived from the A(H1N1)pdm09 strain and the novel SwN2, a SwH3N2 virus and a human-like H3N2 virus, among others. Additionally, our analyses also revealed at least 3 independent human-to-swine introductions of the A(H1N1)pdm09 strain within the last 4 years in Chile. Overall this indicates that close human-swine interactions greatly contribute to the genetic diversity and emergence of IAVs in Chilean swine. This is the first comprehensive molecular epidemiological study of swIAV in Chile demonstrating the co-circulation of multiple viral strains in intensive swine production systems. Our data emphasizes the value of conducting long-term SwIAV surveillance in Latin America, a poorly studied region of the world. Acknowledgements: CEIRS program: HHSN266200700010C, HHSN272201400008C from NIH-NIAID, FONDEF IDeA Grant ID14I10201 and Proyecto Anillo de Investigación en Ciencia y Tecnología - PIA ACT1408, both from CONICYT Chile

Sin Nombre Virus Infection in Field Workers, Colorado, USA

We report 2 cases of Sin Nombre virus (SNV) infection in field workers, possibly contracted through rodent bites. Screening for antibodies to SNV in rodents trapped in 2 seasons showed that 9.77% were seropositive. Quantitative real-time PCR showed that 2 of 79 deer mice had detectable titers of SNV RNA

Incidence of particle size distribution in peanut husks bonded panels

El propósito de esta etapa de la investigación fue conocer la influencia de la variación del tamaño y de la forma de partículas cáscaras de maní en las propiedades de paneles aglomerados encolados con resina ureica. Se formularon paneles con cáscaras molidas (densidad de las partículas: de 81 Kg/m3), paneles con cáscaras enteras (densidad de las partículas: 200 Kg/m3) y dos combinaciones de las mismas. Los resultados alcanzados demostraron que los paneles compuestos por partículas de cáscaras de maní molidas (finas) mejoraron las propiedades físicas y mecánicas respecto de las placas que incorporaron partículas de mayor tamaño. Los valores de densidad en paneles con partículas molidas fueron 628,67 Kg/m3; absorción de agua 65,3% y 79,75% a 2 h y 24 h respectivamente; e hinchamiento de 9,9% y 14,35% medidos a 2 h y 24 h respectivamente. En relación a la caracterización de propiedades mecánicas de flexión, los valores registrados en muestras elaboradas con partículas finas de cáscaras de maní resultaron en MOR: 3,58 MPa, LOP 2,26 MPa y MOE 627 MPa. Con respecto a tenacidad, el mayor valor fue observado en los tableros elaborados con partículas enteras de cáscaras de maní: 1,58 MPa. Las propiedades caracterizadas se encuentran aun por debajo de las propiedades de las placas comerciales de madera de tipo MDF y aglomerados convencionales. Ajustes al proceso de elaboración de las placas de cáscaras de maní serán incorporados en futuros trabajosThe purpose of this stage was to determine the influence of particle size and shape of peanut husks on the properties of panels made with urea resin. Panels were made with milled husks200 Kg/m3 ) and unmilled husks (81 Kg/m3 ) and two combinations thereof. The results showed that the panels made with milled husks improved physical and mechanical properties with respect to the panels that incorporated unmilled particles. The density values in panels with milled particles were 628.67 Kg / m3 ; water absorption 65.3% and 79.75% at 2 and 24 hours respectively, and swelling of 9.9% and 14.35% measured at 2 and 24 hours respectively. Regarding the characterization of mechanical properties of bending, the values recorded in samples prepared with fine particles of peanut husks resulted in MOR: 3.58 MPa, LOP 2.26 MPa and MOE 627 MPa. With respect to toughness, the highest value was observed in particle boards made from unmilled peanut husks: 1.58MPa. The characterized properties are still below the properties of commercial wood panels. Adjustments to the process of preparing the peanut husks plates will be incorporated in future experiencesFil: Granero, Ana Victoria. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Gatani, Mariana Pilar. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Medina, J. C. Universidad Nacional de Santiago del Estero. Facultad de Cs.forestales. Instituto de Tecnologia de la Madera; ArgentinaFil: Ruiz, A.. Universidad Nacional de Santiago del Estero. Facultad de Cs.forestales. Instituto de Tecnologia de la Madera; ArgentinaFil: Fiorelli, J.. Universidade de Sao Paulo; Brasil. Laboratorio de Construções e Ambiência. Faculdade de Zootecnia e Enghenaria de Alimentos; BrasilFil: Kreiker, Jeronimo Rafael. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); ArgentinaFil: Lerda, Maria Josefina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Cordoba. Centro Experimental de la Vivienda Economica(i); Argentin

Mechanochemically Synthesized Supported Magnetic Fe-Nanoparticles as Catalysts for Efficient Vanillin Production

Magnetically separable nanocatalysts were synthesized by incorporating iron nanoparticles on a mesoporous aluminosilicate (Al-SBA-15) through a mechanochemical grinding pathway in a single step. Noticeably, magnetic features were achieved by employing biomass waste as a carbon source, which additionally may confer high oxygen functionalities to the resulting material. The resulting catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, porosimetry, and magnetic susceptibility. The magnetic nanocatalysts were tested in the selective oxidative cleavage reaction of isoeugenol and vanillyl alcohol to vanillin. As a result, the magnetic nanocatalysts demonstrated high catalytic activity, chemical stability, and enormous separation/reusability qualities. The origin of catalytic properties and its relationship with the iron oxide precursor were analyzed in terms of the chemical, morphological, and structural properties of the samples. Such analysis allows, thus, to highlight the superficial concentration of the iron entities and the interaction with Al as key factors to obtain a good catalytic response