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Core Zone (core + zone)

Distribution by Scientific Domains
Polymers and Materials Science40%

Selected Abstracts

Characterizing Core and Corridor Use by Nubian Ibex in the Negev Desert, Israel

CONSERVATION BIOLOGY, Issue 1 2000
Yehoshua Shkedy
To identify and characterize corridors used by Nubian ibex (Capra ibex nubiana), we analyzed sighting data recorded for the past 20 years in the Israel Nature Reserves Authority data banks. We categorized each recorded sighting as belonging to a corridor or a core zone based on the total number of sightings in its vicinity. We identified three main core populations, a natural corridor connecting two of them, and a corridor that was not evident connecting the third population. Ibex inside and outside core zones were sighted on steeper terrain than expected by chance; this was more pronounced inside the core zones than outside them. We hypothesize that because ibex outside core zones must move rapidly and directionally across unfamiliar habitats, they must use more moderate terrain. Although ibex sightings in core zones were mostly in the vicinity of water, we found no relationship between the location of the sightings and proximity to water sources in the corridor. Hence, water does not appear to be an important factor in movement through corridors. It was more common to observe ibex out of the core zones during the summer. Males, which can be twice the size of females, were found traveling alone in corridors more often than in core zones. There was no difference between males and females in the steepness of terrain in which they were sighted outside core zones. Our data show that protecting ibex habitat in core zones and corridors is important to ibex conservation in Israel's arid zones. In addition, protecting this habitat may benefit other rock-dwelling species in the area. Resumen: Los corredores son un factor clave en esfuerzos de conservación. Para identificar y caracterizar el uso de corredores por el íbice de Nubia (Capra ibex nubiana) analizamos datos de avistamiento de los últimos 20 años en las bases de datos de la Autoridad Israelí de Reservas Naturales. Categorizamos cada registro asignándolo a un corredor o a una zona núcleo basándonos en el total de registros cercanos. Identificamos tres poblaciones en zona núcleo, un corredor natural que conectaba a dos de ellas y un corredor, no muy evidente, conectando a la tercera población. Se registraron íbices en terrenos inclinados dentro y fuera de zonas núcleo más de lo esperado al azar; esto fue más marcado dentro de las zonas núcleo que afuera. Hipotetizamos que deben utilizar terrenos más moderados, debido a que los íbices fuera de las zonas núcleo deben moverse rápida y direccionalmente a través de hábitats no familiares. Aunque los registros de íbices en zonas núcleo estuvieron cercanos a agua, no encontramos relación entre la localización de los registros y la cercanía a fuentes de agua en el corredor. Por tanto, el agua no parece ser un factor importante en el movimiento en los corredores. Fue más común observar íbices afuera de las zonas núcleo en el verano. Los machos, que pueden ser dos veces más grandes que hembras, fueron registrados desplazándose solos en los corredores más a menudo que en las zonas núcleo. No hubo diferencia entre machos y hembras en la pendiente del terreno en que fueron registrados fuera de las zonas núcleo. Nuestros resultados indican que la protección del hábitat de íbices en zonas núcleo y corredores es importante para la conservación de íbices en las zonas áridas de Israel. Además, la protección de este hábitat puede beneficiar a otras especies en el área. [source]

Hierarchy crystallization structure of a polypropylene random copolymer injection-molded bar induced by a nucleating agent

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
Yong Wang
Abstract In this work, the effect of a nucleating agent on the crystallization structure of an injection-molded bar of a polypropylene random copolymer (PPR) with sorbitol derivatives [1,2,3,4-dibenzylidene sorbitol (DBS)] has been studied. The results show that pure PPR forms a simple skin,core crystallization structure. However, PPR/DBS forms an interesting and complicated hierarchy crystallization structure: there is a transition layer between the skin layer and the core zone. In this transition layer, the crystallization structure consists of some perfect spherulites and many tiny crystallites. Further research suggests that the formation of the hierarchy crystallization structure depends on not only the content of the nucleating agent in the PPR matrix but also the mold temperature during the injection-molding processing. The crystallization behavior of PPR/DBS during the cooling process has been characterized with polarization optical microscopy and differential scanning calorimetry. The results suggest that there are different mechanisms in the crystallization process of PPR/DBS. The formation of a three-dimensional DBS network under a certain condition might be the main reason for the complicated hierarchy crystallization structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

The impact of climate variability on soybean yields in Argentina.

METEOROLOGICAL APPLICATIONS, Issue 1 2007
Multivariate regression
Abstract Climate variability is examined and discussed in this work, emphasizing its influence over the fluctuation of soybean yield in the Pampas (central-eastern Argentina). Monthly data of rainfall, maximum and minimum temperatures, thermal range and seasonal rainfall were analysed jointly with the soybean yield in the period 1973-2000. Low-frequency variability was significant only in the minimum temperature during November in almost all the stations. This situation is favourable to the crop since during this month, seed germination, a growth stage sensitive to low temperatures, takes place. In the crop's core production region, 72% of the series of soybean yield presented a positive trend. Except in years with extreme rainfall situations, interannual variability of the soybean yield is in phase with the seasonal rainfall interannual variability. During these years, losses in the soybean crop occurred, with yield negative anomalies greater than one standard deviation. Soybean yield showed spatial coherence at the local scale, except in the crop's core zone. The association between each climate variable and yield did not show a defined regional pattern. Summer high temperature and rainfall excesses during the period of maturity and harvest have the greatest negative impact on the crop, whilst higher minimum temperatures during the growing season favour high yields. The joint effect of climate variables over yield was studied with multivariate statistical models, assuming that the effect of other factors (such as soil, technology, pests) is contained in the residuals. The regression models represent the estimates of the yield satisfactorily (high percentage of explained variance) and can be used to assess expected anomalies of mean soybean yield for a particular year. However, the predictor variables of the yield depend on the region. Copyright © 2007 Royal Meteorological Society [source]

Characterizing Core and Corridor Use by Nubian Ibex in the Negev Desert, Israel

CONSERVATION BIOLOGY, Issue 1 2000
Yehoshua Shkedy
To identify and characterize corridors used by Nubian ibex (Capra ibex nubiana), we analyzed sighting data recorded for the past 20 years in the Israel Nature Reserves Authority data banks. We categorized each recorded sighting as belonging to a corridor or a core zone based on the total number of sightings in its vicinity. We identified three main core populations, a natural corridor connecting two of them, and a corridor that was not evident connecting the third population. Ibex inside and outside core zones were sighted on steeper terrain than expected by chance; this was more pronounced inside the core zones than outside them. We hypothesize that because ibex outside core zones must move rapidly and directionally across unfamiliar habitats, they must use more moderate terrain. Although ibex sightings in core zones were mostly in the vicinity of water, we found no relationship between the location of the sightings and proximity to water sources in the corridor. Hence, water does not appear to be an important factor in movement through corridors. It was more common to observe ibex out of the core zones during the summer. Males, which can be twice the size of females, were found traveling alone in corridors more often than in core zones. There was no difference between males and females in the steepness of terrain in which they were sighted outside core zones. Our data show that protecting ibex habitat in core zones and corridors is important to ibex conservation in Israel's arid zones. In addition, protecting this habitat may benefit other rock-dwelling species in the area. Resumen: Los corredores son un factor clave en esfuerzos de conservación. Para identificar y caracterizar el uso de corredores por el íbice de Nubia (Capra ibex nubiana) analizamos datos de avistamiento de los últimos 20 años en las bases de datos de la Autoridad Israelí de Reservas Naturales. Categorizamos cada registro asignándolo a un corredor o a una zona núcleo basándonos en el total de registros cercanos. Identificamos tres poblaciones en zona núcleo, un corredor natural que conectaba a dos de ellas y un corredor, no muy evidente, conectando a la tercera población. Se registraron íbices en terrenos inclinados dentro y fuera de zonas núcleo más de lo esperado al azar; esto fue más marcado dentro de las zonas núcleo que afuera. Hipotetizamos que deben utilizar terrenos más moderados, debido a que los íbices fuera de las zonas núcleo deben moverse rápida y direccionalmente a través de hábitats no familiares. Aunque los registros de íbices en zonas núcleo estuvieron cercanos a agua, no encontramos relación entre la localización de los registros y la cercanía a fuentes de agua en el corredor. Por tanto, el agua no parece ser un factor importante en el movimiento en los corredores. Fue más común observar íbices afuera de las zonas núcleo en el verano. Los machos, que pueden ser dos veces más grandes que hembras, fueron registrados desplazándose solos en los corredores más a menudo que en las zonas núcleo. No hubo diferencia entre machos y hembras en la pendiente del terreno en que fueron registrados fuera de las zonas núcleo. Nuestros resultados indican que la protección del hábitat de íbices en zonas núcleo y corredores es importante para la conservación de íbices en las zonas áridas de Israel. Además, la protección de este hábitat puede beneficiar a otras especies en el área. [source]

Comparison of structure development in injection molding of isotactic and syndiotactic polypropylenes

POLYMER ENGINEERING & SCIENCE, Issue 8 2002
Dongman Choi
A comparative study of the crystallization and orientation development in injection molding isotactic and syndiotactic polypropylenes was made. The injection molded samples were characterized using wide angle X-ray diffraction (WAXD) techniques and birefringence. The injection molded isotactic polypropylene samples formed well-defined sublayers (skin, shear and core zones) and exhibited polymorphic crystal structures of the monoclinic ,-form and the hexagonal ,-form. Considerable amounts of ,-form crystal were formed in the shear and core zones, depending on the injection pressure or on the packing pressure. The isotactic polypropylene samples had relatively high frozen-in orientations in the skin layer and the shear zone. The injection molded syndiotactic polypropylene exhibited the disordered Form I structure, but it did not appear to crystallize during the mold-filling stage because of its slow crystallization rate and to develop a distinct shear zone. The core zone orientation was greatly increased by application of high packing pressure. The isotactic polypropylene samples exhibited much higher birefringence than the syndiotactic polypropylene samples at the skin and shear layers, whereas both materials exhibited similar levels of crystalline orientation in these layers. [source]