DECT evaluation of noncalc fied coronary artery plaque

Purpose: Composition of the coronary artery plaque is known to have critical role in heart attack. While calcified plaque can easily be diagnosed by conventional CT, it fails to distinguish between fibrous and lipid rich plaques. In the present paper, the authors discuss the experimental techniques and obtain a numerical algorithm by which the electron density (rho(e)) and the effective atomic number (Z(eff)) can be obtained from the dual energy computed tomography (DECT) data. The idea is to use this inversion method to characterize and distinguish between the lipid and fibrous coronary artery plaques. Methods: For the purpose of calibration of the CT machine, the authors prepare aqueous samples whose calculated values of (rho(e), Z(eff)) lie in the range of (2.65 x 10(23) <= rho(e) <= 3.64 x 10(23)/cm(3)) and (6.80 <= Z(eff) <= 8.90). The authors fill the phantom with these known samples and experimentally determine HU(V-1) and HU(V-2), with V-1,V-2 = 100 and 140 kVp, for the same pixels and thus determine the coefficients of inversion that allow us to determine (rho(e), Z(eff)) from the DECT data. The HU(100) and HU(140) for the coronary artery plaque are obtained by filling the channel of the coronary artery with a viscous solution of methyl cellulose in water, containing 2% contrast. These (rho(e), Z(eff)) values of the coronary artery plaque are used for their characterization on the basis of theoretical models of atomic compositions of the plaque materials. These results are compared with histopathological report. Results: The authors find that the calibration gives Pc with an accuracy of 3.5% while Z(eff) is found within 1% of the actual value, the confidence being 95%. The HU(100) and HU(140) are found to be considerably different for the same plaque at the same position and there is a linear trend between these two HU values. It is noted that pure lipid type plaques are practically nonexistent, and microcalcification, as observed in histopathology, has to be taken into account to explain the nature of the observed (rho(e), Z(eff)) data. This also enables us to judge the composition of the plaque in terms of basic model which considers the plaque to be composed of fibres, lipids, and microcalcification. Conclusions: This simple and reliable method has the potential as an effective modality to investigate the composition of noncalcified coronary artery plaques and thus help in their characterization. In this inversion method, (rho(e), Z(eff)) of the scanned sample can be found by eliminating the effects of the CT machine and also by ensuring that the determination of the two unknowns (rho(e), Z(eff)) does not interfere with each other and the nature of the plaque can be identified in terms of a three component model. (C) 2015 American Association of Physicists in Medicine.

Seismotectonics of the April-May 2015 Nepal earthquakes: An assessment based on the aftershock patterns, surface effects and deformational characteristics

Occurrence of the April 25, 2015 (Mw 7.8) earthquake near Gorkha, central Nepal, and another one that followed on May 12 (Mw 7.3), located similar to 140 km to its east, provides an exceptional opportunity to understand some new facets of Himalayan earthquakes. Here we attempt to assess the seismotectonics of these earthquakes based on the deformational field generated by these events, along with the spatial and temporal characteristics of their aftershocks. When integrated with some of the post-earthquake field observations, including the localization of damage and surface deformation, it became obvious that although the mainshock slip was mostly limited to the Main Himalayan Thrust (MHT), the rupture did not propagate to the Main Frontal Thrust (MFT). Field evidence, supported by the available InSAR imagery of the deformation field, suggests that a component of slip could have emerged through a previously identified out-of-sequence thrust/active thrust in the region that parallels the Main Central Thrust (MCT), known in the literature as a co-linear physiographic transitional zone called PT2. Termination of the first rupture, triggering of the second large earthquake, and distribution of aftershocks are also spatially constrained by the eastern extremity of PT2. Mechanism of the 2015 sequence demonstrates that the out-of-sequence thrusts may accommodate part of the slip, an aspect that needs to be considered in the current understanding of the mechanism of earthquakes originating on the MHT. (c) 2015 Elsevier Ltd. All rights reserved.

Size Effects on Strength in the Transition from Single-to-Polycrystalline Behavior

During the transition from single crystalline to polycrystalline behavior, the available data show the strength increasing or decreasing as the number of grains in a cross section is reduced. Tensile experiments were conducted on polycrystalline Ni with grain sizes (d) between 16 and 140 mu m and varying specimen thickness (t), covering a range of lambda (-t/d) between similar to 0.5 and 20. With a decrease in lambda, the data revealed a consistent trend of strength being independent of lambda at large lambda, an increase in strength, and then a decrease in strength. Microstructural studies revealed that lower constraints enabled easier rotation of the surface grains and texture evolution, independent of the specimen thickness. In specimen interiors, there was a greater ease of rotation in thinner samples. Measurements of misorientation deviations within grains revealed important differences in the specimen interiors. A simple model is developed taking into account the additional geometrically necessary dislocations due to variations in the behavior of surface and interior grains, leading to additional strengthening. A suitable combination of this strengthening and surface weakening can give rise to wide range of possibilities with a decrease in lambda, including weakening, strengthening, and strengthening and weakening.

Phase dependent photocatalytic activity of Ag loaded TiO2 films under sun light

Well-crystallized anatase and mixed (anatase-rutile) phase TiO2 thin films were deposited by DC magnetron sputtering technique at various DC powers in the range of 80-140 W. Pure anatase phase was observed in the TiO2 films deposited at low power of 80 W. Films deposited at 120 W were composed of both anatase and rutile phases. At higher power of 140 W, the films are rutile dominated and the rutile percentage increased from 0 to 82% with increase of DC power. The same results of phase change were confirmed by Raman studies. The surface morphology of the TiO2 films showed that the density of the films increased with increase of sputter power. The optical band gap of the films varied from 3.35 to 3.14 eV with increase of DC power. The photocatalytic activity of the TiO2 films increased with increasing DC power up to 120 W and after that it decreases. We found that the TiO2 films deposited at 120 W with 48% of rutile phase, exhibited high photocatalytic activity (43% of degradation) under UV light compared with other TiO2 films. After loading the optimized Ag nanoparticles on the mixed phase TiO2 films, the photocatalytic activity shifted from UV to visible region with enhancement of photocatalytic activity (55% of degradation). (C) 2015 Elsevier B.V. All rights reserved.

Tracking the migration of the Indian continent using the carbonate clumped isotope technique on Phanerozoic soil carbonates

Approximately 140 million years ago, the Indian plate separated from Gondwana and migrated by almost 90 degrees latitude to its current location, forming the Himalayan-Tibetan system. Large discrepancies exist in the rate of migration of Indian plate during Phanerozoic. Here we describe a new approach to paleo-latitudinal reconstruction based on simultaneous determination of carbonate formation temperature and delta O-18 of soil carbonates, constrained by the abundances of C-13-O-18 bonds in palaeosol carbonates. Assuming that the palaeosol carbonates have a strong relationship with the composition of the meteoric water, delta O-18 carbonate of palaeosol can constrain paleo-latitudinal position. Weighted mean annual rainfall delta O-18 water values measured at several stations across the southern latitudes are used to derive a polynomial equation: delta(18)Ow = -0.006 x (LAT)(2) - 0.294 x (LAT) - 5.29 which is used for latitudinal reconstruction. We use this approach to show the northward migration of the Indian plate from 46.8 +/- 5.8 degrees S during the Permian (269 M. y.) to 30 +/- 11 degrees S during the Triassic (248 M. y.), 14.7 +/- 8.7 degrees S during the early Cretaceous (135 M. y.), and 28 +/- 8.8 degrees S during the late Cretaceous ( 68 M. y.). Soil carbonate delta O-18 provides an alternative method for tracing the latitudinal position of Indian plate in the past and the estimates are consistent with the paleo-magnetic records which document the position of Indian plate prior to 135 +/- 3 M. y.

Phase dependent photocatalytic activity of Ag loaded TiO2 films under sun light

Well-crystallized anatase and mixed (anatase-rutile) phase TiO2 thin films were deposited by DC magnetron sputtering technique at various DC powers in the range of 80-140 W. Pure anatase phase was observed in the TiO2 films deposited at low power of 80 W. Films deposited at 120 W were composed of both anatase and rutile phases. At higher power of 140 W, the films are rutile dominated and the rutile percentage increased from 0 to 82% with increase of DC power. The same results of phase change were confirmed by Raman studies. The surface morphology of the TiO2 films showed that the density of the films increased with increase of sputter power. The optical band gap of the films varied from 3.35 to 3.14 eV with increase of DC power. The photocatalytic activity of the TiO2 films increased with increasing DC power up to 120 W and after that it decreases. We found that the TiO2 films deposited at 120 W with 48% of rutile phase, exhibited high photocatalytic activity (43% of degradation) under UV light compared with other TiO2 films. After loading the optimized Ag nanoparticles on the mixed phase TiO2 films, the photocatalytic activity shifted from UV to visible region with enhancement of photocatalytic activity (55% of degradation). (C) 2015 Elsevier B.V. All rights reserved.

Size and temperature dependence of the photoluminescence properties of NIR emitting ternary alloyed mercury cadmium telluride quantum dots

Exciton-phonon coupling and nonradiative relaxation processes have been investigated in near-infrared (NIR) emitting ternary alloyed mercury cadmium telluride (CdHgTe) quantum dots. Organically capped CdHgTe nanocrystals of sizes varying from 2.5-4.2 nm have been synthesized where emission is in the NIR region of 650-855 nm. Temperature-dependent (15-300 K) photoluminescence (PL) and the decay dynamics of PL at 300 K have been studied to understand the photophysical properties. The PL decay kinetics shows the transition from triexponential to biexponential on increasing the size of the quantom dots (QDs), informing the change in the distribution of the emitting states. The energy gap is found to be following the Varshni relation with a temperature coefficient of 2.1-2.8 x 10(-4) eV K-1. The strength of the electron-phonon coupling, which is reflected in the Huang and Rhys factor S, is found in the range of 1.17-1.68 for QDs with a size of 2.5-4.2 nm. The integrated PL intensity is nearly constant until 50 K, and slowly decreases up to 140 K, beyond which it decreases at a faster rate. The mechanism for PL quenching with temperature is attributed to the presence of nonradiative relaxation channels, where the excited carriers are thermally stimulated to the surface defect/trap states. At temperatures of different region (<140 K and 140-300 K), traps of low (13-25 meV) and high (65-140 meV) activation energies seem to be controlling the quenching of the PL emission. The broadening of emission linewidth is found to due to exciton-acoustic phonon scattering and exciton-longitudinal optical (LO) phonon coupling. The exciton-acoustic phonon scattering coefficient is found to be enhanced up to 55 MU eV K-1 due to a stronger confinement effect. These findings give insight into understanding the photophysical properties of CdHgTe QDs and pave the way for their possible applications in the fields of NIR photodetectors and other optoelectronic devices.

Energy conversion in shape memory alloy heat engine - Part II: Simulation

In this paper, a theoretical model proposed in Part I (Zhu et al., 2001a) is used to simulate the behavior of a twin crank NiTi SMA spring based heat engine, which has been experimentally studied by Iwanaga et al. (1988). The simulation results are compared favorably with the measurements. It is found that (1) output torque and heat efficiency decrease as rotation speed increase; (2) both output torque and output power increase with the increase of hot water temperature; (3) at high rotation speed, higher water temperature improves the heat efficiency. On the contrary, at low rotation speed, lower water temperature is more efficient; (4) the effects of initial spring length may not be monotonic as reported. According to the simulation, output torque, output power and heat efficiency increase with the decrease of spring length only in the low rotation speed case. At high rotation speed, the result might be on the contrary.

Efecto de diferentes niveles de energía conservando la relación energía-proteína en piensos de inicio y finalización en pollos de engorde

En el presente estudio se compararon cuatro dietas con diferentes niveles de energía 2,940, 3,040, 3,140 y 3,240 (Kcal EM/Kg de alimento), los cuales fueron ajustados a los requerimientos nutricionales en cuanto a la relación caloría proteína recomendados por la Hubbard Farm, Inc. (1991). Durante un periodo de 56 días los broilers fueron evaluados en la granja avícola "Buenos Aires" que pertenece a la Tip Top Industrial S.A. se utilizaron 803 pollos de engorde de un día de nacidos de la línea Hubbard, los que fueron distribuidos aleatoriamente en tres unidades experimentales proporcionales a los cuatro tratamientos existentes, estos distribuidos en un diseño completamente al azar y sometidos a la prueba de Tukey el que proporciona la superioridad existente entre tratamientos. Se encontraron diferencias significativas (P<0.05) entre tratamientos en las variables peso vivo, ganancia de peso y conversión alimenticia pero no así para el consumo alimenticio. Los tratamientos T1 T2, T3 y T4 presentaron mortalidad al final del periodo de 2.57, 4.41, 7.88 y 10.89 (%) respectivamente y rendimiento en la canal del 84.45 % para todos los tratamientos. Se concluyó que las dietas más energéticas proporcionaban las mejores conversiones alimenticias y las mayores ganancias de peso. Y a medida que se incrementaba el nivel energético en las dietas los costos alimenticios también se incrementaban. La fórmula más económica es el T1 (2940 Kcal EM/Kg de alimento, 21.63 y 18.89 % de proteína para inicio y finalización) durante todas las semanas de estudio. El momento óptimo para la matanza es la sexta semana para el T 1 (2940 Kcal EM/Kg de alimento, 21.63 y 18.89 % de proteínas) y T2 (3040 Kcal EM/Kg de alimento, 22.36 y 19.15 % de proteínas) por efecto de los costos alimenticios.

Efectos de la ración de retiro sobre parámetros zootécnicos y financieros de pollos broilers

Con el objetivo de evaluar la aplicación de alimento de retiro en broilers en 5 periodos diferentes de (0,4,6,8 y 10 días) antes del sacrificio se realizó el ensayo compuesto de 4 repeticiones cada uno, distribuidas en un diseño completamente al azar, con el uso de raciones isocalóricas e isoproteicas. Se estudiaron los siguientes variables: consumo de alimento, peso vivo, ganancia de peso, conversión alimenticia, mortalidad, rendimiento en canal y análisis financiero. Los resultados, no arrojaron diferencias significativas entre los tratamientos para: consumo de alimento, conversión alimenticia, ganancia de peso y peso vivo; pero se presentaron diferencias entre los tratamientos en cuanto a los costos de producción unitaria. El porcentaje de mortalidad acumulada alcanzó el 3% y los rendimientos de la canal fueron: para el t1 (70.2%), t2 (69.7%), t3 (70.0%), t4 (10.1%) y t5 (75.2%). El t5, fue el tratamiento que obtuvo la conversión alimenticia más elevada en comparación con el testigo y los otros tratamientos experimentales. Sin embargo, el que presentó los mejores resultados en cuanto a consumo de alimentos, rendimiento en canal, ganancia de peso, y peso vivo, fue el tratamiento (t5), con un rendimiento en canal caliente de 75.2%. Este tratamiento, presentó los mayores parámetros productivos y mayor ahorro de (29.8702 U.S $) por camada de 140 pollos, utilizando la ración de retiro 10 días antes de la matanza. Esto justifica el uso de este tipo de alimento durante este período, con lo cual queda demostrado que pueden obtenerse resultados satisfactorios y que es una alternativa para disminuir los costos de alimentación en Broilers.

Comportamiento reproductivo, dinamica de produccion y calidad de la leche de genotipos lecheros bajo condiciones intensivas, en el tropico seco de Rivas, Nicaragua

Con el propósito de evaluar el comportamiento reproductivo, la dinámica de producción y calidad de la leche de genotipos lecheros en la Finca El Corpus del Meneo, manejado intensivamente, se utilizó información del periodo 1997 - 2004. Se analizaron 181 datos de edad de incorporación (EDADINC), 157 datos de edad a primer parto (EPP), 543 datos de número de servicios por concepción (NSC) y 341 datos de intervalo entre partos (IEP), 233 datos de dos pesajes de leche (diciembre 2004 y enero 2005) y sus respectivos análisis de calidad en porcentajes de grasa (%FAT), proteína (%PROT), lactosa (%LACT) y materia seca (%DRYM). Los modelos lineales aditivos incluyeron efectos de grupo racial (GRUPO), año de nacimiento (ANACV), año de incorporación (AINCV), época de incorporación (El), año de parto (APART), número de parto (NUMPA), época de parto (EP), periodo de lactancia (PERL) y sexo de la cría (SEXC) e interacciones importantes. Para EDINCV, se encontró diferencias relevantes entre GRUPOS (P<0.068), ANACV (P<0.0001), AINCV (P<0.0001) y EN (P<0.0001). Para EPP, diferencias importantes entre AINCV (P<0.0001), APART (P<0.0028) y la interacción APARTxEP (P<0.0361). Para NSC, diferencias estadísticas entre APART (P<0.0138) y NUMPA (P<0.0074). Para IEP, las diferencias importantes entre APART (P<0.0076), NUMPA (P<0.0004) y la interacción GRUPOxSEXC (P<0.0882). Se obtuvieron medias de mínimos cuadrados para EDADINC, EPP, NSC IEP de 25.75±0.72 meses, 35.71±0.88 meses, 1.34±0.11 unidades y !2.82±0.35 meses, respectivamente. Se encontró diferencias importantes entre GRUPOS (1'<0.0001 a P<0.026), NUMPA (P<0.0003 a P<0.0024), PERL (P<0.0000) y la interacción NUMPA*PERL (P<0.0000 a 0.0082), en las variables de producción y calidad, no así entre NUMPA para %DRYM. Se estimaron valores de 8.79±0.29 Kg., 4.14±0.09, 3.48±0.04, 4.31±0.02 y 12.56±0.11 para PLD, %FAT, %PROT, %LACT y %DRYM, respectivamente. GRUPOS no resulto significativo, pero se observo una tendencia marcada del GRUPO 5 (Pardo suizo) hacia una menor EDADINC, el GRUPO l (Holstein y cruces) mostró menores EPP, y los menores valores de NSC (mayor eficiencia técnica) e IEP para el GRUPO 3 (Jersey y cruces). El GRUPO con Holstein mostró mayores producciones de leche pero con menor calidad, mientras que los GRUPOS 2 y 4 (Jersey y cruces, Pardo suizo y cruces) mostraron menores producciones pero con mayor calidad general. La producción de leche por vaca promedio semanal (PLVD) a través de los años se comportó de acuerdo con algunos eventos climatológicos que determinan la disponibilidad y calidad del alimento. Se determinaron tres picos de producción (9.5, 10.0 y 9.7 kg.) y tres puntos críticos similares (9.0- 9.1 kg.). Los genotipos lecheros estudiados muestran que bajo condiciones de trópico seco y manejo intensivo es posible lograr parámetros de reproducción, producción y calidad de leche aceptable y mayores que los parámetros nacionales.

Influencia de rotación de cultivos y métodos de control sobre la dinámica de las malezas y el crecimiento, desarrollo y rendimiento de la soya (Glycine max (L) Merr.) cv. cristalina

En la estación experimental de Campos Azules, municipio de Masetepe, se inició en la época de postrera de 1987, un experimento de rotación de cultivos bajo diferentes niveles de control de malezas. El presente trabajo, evaluó el control de los cultivos antecesores Maíz y Pepinillo con tres niveles de control de malezas: químico, limpia en período crítico y limpias periódicas a la dinámica de le cenosis de malezas, crecimiento y rendimiento del cultivo sucesor soya en la postrera de 1989. Cuando antecedió el Maíz, la abundancia de malezas fue mayor con 449 individuos, reduciéndose considerablemente a le coseche, obteniendo una biomasa promedio de solo 165.48 gramos. De lo contrario con Pepinillo como antecesor, la abundancia al inicio fue menor con 231 individuos, pero se obtuvo a la cosecha la mayor biomasa promedio con 193.45 gramos. Para los caracteres de la soya a la cosecha no hubo diferencies significativas en les rotaciones. El control químico presentó mayor abundancia al inicio con 422 individuos, teniendo posteriormente une reducción hasta de 27 individuos. El control limpie en período crítico tuvo un comportamiento similar que el químico con 390 individuos, reduciéndose a lo cosecha a 140 individuos. El control limpias periódicas tuvo el inicio la menor abundancia con 218 individuos, reduciéndose a la cosecha a 100 individuos. Relacionando los caracteres de lo soya con los controles hubo diferencias significativas en: altura de planta a la cosecha y altura de inserción de la primero vaina en el control limpia en período crítico. Peso de mil semillas eh el control químico y rendimiento en el control limpias periódicas. En los demás caracteres de la soya no hubo diferencias significativas, mareándose una tendencia a favor del pepinillo como cultivo antecesor con 1018 kg/he de soya, comparado con Maíz como antecesor con solo 859 kg/ha de soya.

Efecto de arreglos topológicos (doble surco) sobre el crecimiento, desarrollo y rendimiento del maiz (Zea mays L.) como cultivo principal, en asocio con leguminosas (Vigna unguiculata L. walp)

El presente estudio se estableció en terrenos del Centro Experimental La Compañía, ubicado en el municipio de Masatepe, departamento de Carazo, durante la época de primera comprendida entre los meses de junio a octubre de 1995. Con el objetivo de estudiar el efecto de los diferentes arreglos de siembra, sobre el Crecimiento, Desarrollo y Rendimiento del maíz (Zea mays L.) como cultivo principal, en asocio con frijol (Viqna unguiculata L. Watp). Los tratamientos en estudio fueron: Tratamiento uno maíz como cultivo puro a 80 cm entre calle. Tratamiento dos maíz a 80 cm, más leguminosa de cobertura un surco de maíz y un surco de leguminosa (1:1). Tratamiento tres, maíz a doble surcos (20 cm entre surco) calle ancha a 140 cm con dos surcos de leguminosas de coberturas entre a 50 cm. Tratamiento cuatro, maíz doble surcos (40 cm entre surcos) calle ancha a 120 con dos surcos de leguminosas entre a 40 cm entre sí. Se utilizó un diseño de Bloque Completo al Azar con cuatro repeticiones. Los resultados obtenidos demuestran que el asocio de maíz-leguminosas, no afectan significativamente el crecimiento, desarrollo y rendimiento del maíz como cultivo principal. Además podemos afirmar que al comparar los rendimientos, del cultivo puro con los asocios, hay una mejor eficiencia en el aprovechamiento del uso potencial de los suelos.

Laser micromachining of thin films for optoelectronic devices and packages

Focused laser micromachining in an optical microscope system is used to prototype packages for optoelectronic devices and to investigate new materials with potential applications in packaging. Micromachined thin films are proposed as mechanical components to locate fibres and other optical and electrical components on opto-assemblies. This paper reports prototype structures which are micromachined in silicon carbide to produce beams 5 μm thick by (i) laser cutting a track in a SiC coated Si wafer, (ii) undercutting by anisotropic silicon etching using KOH in water, and (iii) trimming if necessary with the laser system. This approach has the advantage of fast turn around and proof of concept. Mechanical test data are obtained from the prototype SiC beam package structures by testing with a stylus profilometer. The Youngs modulus obtained for chemical vapour deposited silicon carbide is 360 +/- 50 GPa indicating that it is a promising material for packaging applications.