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Distribution by Scientific Domains

Medical Sciences	36%
Physics and Astronomy	16%
Earth and Environmental Science	16%
Polymers and Materials Science	8%
Humanities and Social Sciences	8%
Engineering	8%
2 Other Domains	8%

Terms modified by Selected Areas

selected area electron diffraction

Selected Abstracts

Kinematic structure in the Galactic halo at the North Galactic Pole: RR Lyrae and blue horizontal branch stars show different kinematics

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
T. D. Kinman
ABSTRACT Radial velocities and proper motions (derived from the GSC-II data base) are given for 38 RR Lyrae (RRL) stars and 79 blue horizontal branch (BHB) stars in a ,200 deg2 area around the North Galactic Pole (NGP). Both heliocentric (UVW) and galactocentric (VR, V,, Vz) space motions are derived for these stars using a homogeneous distance scale consistent with (m,M)0= 18.52 for the Large Magellanic Cloud (LMC). An analysis of the 26 RRL and 52 BHB stars whose height (Z) above the plane is less than 8 kpc shows that this halo sample is not homogeneous. Our BHB sample (like that of Sirko et al.) has a zero galactic rotation (V,) and roughly isotropic velocity dispersions. The RRL sample shows a definite retrograde rotation (V,=,95 ± 29 km s,1) and non-isotropic velocity dispersions. The combined BHB and RRL sample has a retrograde galactic rotation (V) that is similar to that found by Majewski for his sample of subdwarfs in Selected Area (SA) 57. The velocity dispersion of the RRL stars that have a positive W motion is significantly smaller than the dispersion of those ,streaming down' with a negative W. Also, the ratio of RRL to BHB stars is smaller for the sample that has positive W. Our halo sample occupies 10.4 kpc3 at a mean height of 5 kpc above the Galactic plane. In this volume, one component (rich in RRL stars) shows retrograde rotation and the streaming motion that we associate with the accretion process. The other component (traced by the BHB stars) shows essentially no rotation and less evidence of streaming. These two components have horizontal branch (HB) morphologies that suggest that they may be the field star equivalents of the young and old halo globular clusters, respectively. Clearly, it is quite desirable to use more than one tracer in any kinematic analysis of the halo. [source]

Systematic sample design for the estimation of spatial means

ENVIRONMETRICS, Issue 1 2003
Luis Ambrosio Flores
Abstract This article develops a practical approach to undertaking systematic sampling for the estimation of the spatial mean of an attribute in a selected area. A design-based approach is used to estimate population parameters, but it is combined with elements of a model-based approach in order to identify the spatial correlation structure, to evaluate the relative efficiency of the sample mean under simple random and systematic sampling, to estimate sampling error and to assess the sample size needed in order to achieve a desired level of precision. Using two case studies (land use estimation and weed seedbank in soil) it is demonstrated how the practical basis for the design of systematic samples provided in this work should be applied and it is shown that if the spatial correlation is ignored the sampling error of the sample mean and the sample size needed in order to achieve a desired level of precision with systematic sampling are overestimated. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Oral health in preschool children with asthma

INTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 4 2008
MALIN STENSSON
Objective., The aim of this study was to investigate oral health and its determinants in 3-year-old and 6-year-old children with asthma. Methods and subjects., Caries and gingivitis were examined in 127 asthmatic (all children with asthma in a selected area and born during a specific time period) and 117 matched, healthy control children. The parents were interviewed regarding various oral-health-related factors. Results., The mean dfs (± standard deviation) in the 3-year-old with asthma was 1.4 ± 3.2 compared with 0.5 ± 1.2 in the controls (P < 0.05). The corresponding figures for the 6-year-old were 2.5 ± 3.9 and 1.8 ± 2.8. The 3-year-old asthmatic children had more gingival bleeding than the healthy controls (P < 0.05). There were no significant differences in gingivitis in the 6-year-old children. Asthmatic children reported higher consumption of sugar-containing drinks and were more frequently mouthbreathers than healthy children (P < 0.05). In 3-year-old children with asthma and immigrant background, the mean dfs was higher compared with immigrant children in the control group (P < 0.01). Conclusion., The results indicate that preschool children with asthma have higher caries prevalence than healthy children. The factors discriminating for caries in asthmatic children are higher intake of sugary drinks, mouth breathing, and immigrant background. [source]

The Tagus Middle Basin (Iberian Peninsula) from the Neolithic to the Iron Age (V-I Millennium Cal.

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 3 2000
BC): The Long Way to Social Complexity
This study is the result of surveys and excavations carried out in a selected area of the middle basin of the Tagus river (Southern Meseta, Iberian Peninsula). The analysis of palaeoecological data, material assemblages, settlement patterns, domestic structures, funerary evidence and socio-economic context in the regional archaeological record from the Neolithic (5000 BC) to the beginning of the Iron Age (500 BC) allows us to identify several long-term historic processes; particularly, two habitational, demographic and socio-economic cycles, which contradict the traditional idea that the prehistory of inner Iberia presents almost no apparent change during these four millennia. [source]

Comparison of hard tissue density changes around implants assessed in digitized conventional radiographs and subtraction images

CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2006
Juliana Araujo Bittar-Cortez
Abstract Objectives: The aim of this in vivo study was to compare peri-implant bone density assessed by the mean gray value of the histogram in digitized conventional radiographs and two digital subtraction images (DSI) methods: linear and logarithmic. Material and methods: Thirty-four patients were monitored by standardized periapical radiographs 1 week after surgery and 4 months later. The radiographs were digitized and manipulated by means of EMAGO® software. Linear and logarithmic DSI were obtained, and a filter was added to the logarithmic image. Control and test regions were selected and the mean value of the gray level of the histogram of these selected areas was obtained. This process was carried out in the digitized conventional radiographs (DCR) and the two methods of DSI. After that, the images were divided into two groups, with and without bone loss, and statistical analysis was performed. Results: The results indicate that differences between the jaws did not reach significance, in all the images and in the two groups with and without bone loss. Furthermore, there was no statistically significant difference between the radiographic density assessed in the DCR and the two methods of subtraction images. Conclusions: Monitoring of peri-implant bone density by the mean gray value of the histogram in a selected area can be assessed either by linear and logarithmic DSI or by DCR. [source]

The Need to Look Beyond the Production and Provision of Relief Seed: Experiences from Southern Sudan

DISASTERS, Issue 4 2002
Richard B. Jones
Free distribution of seeds in selected areas of southern Sudan has been widespread as a way of increasing food security. Field research in areas targeted for seed relief found that farmer seed systems continue to meet the crop and varietal needs of farmers even following the 1998 famine. Donor investments in seed multiplication of improved sorghum have not been sustained due to a lack of effective demand for the improved seed beyond that created by the relief agencies. The article argues that rather than imposing outside solutions, whether through seed provisioning or seed production enterprises, greater attention needs to be given to building on the strengths of existing farmer systems and designing interventions to alleviate the weaknesses. The case is made to support dynamically the process of farmer experimentation through the informed introduction of new crops and varieties that can potentially reinforce the strength and diversity of local cropping systems. [source]

Seawater quality along the Adriatic coast, Croatia, based on toxicity data

ENVIRONMENTAL TOXICOLOGY, Issue 2 2004
Nevenka Bihari
Abstract The potential toxicity of organic extracts from 12 seawater samples from each of 24 sampling sites, collected during 1999,2001 along the Adriatic coast, Croatia, was analyzed with the Microtox toxicity bioassay. The results were consistent with the usefulness of Microtox for the detection of accidental toxic events. To determine the water quality of selected areas, cluster analysis for discrimination between groups with similar toxicity load and water quality index as a base for the ranking of sampling sites was introduced. Based on our experimental data, five classes of the quality index were defined, and so areas were ranked in five categories (excellent, good, fair, poor, and very poor) according to their potential toxic influence. The water quality of selected sites for the potential toxicity of organic extracts could be described as excellent at one sampling site, good at 15 sampling sites, and fair at eight sampling sites. Poor and very poor seawater quality was not detected. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 109,114, 2004. [source]

Nacre in Mollusk Shells as a Multilayered Structure with Strain Gradient

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Boaz Pokroy
Abstract How do living organisms attain the complicated shapes of grown bio-composites? This question is answered when studying the mechanics of the nacre layer in the bivalve mollusk shells. In this study, the internal strains/stresses across the shell thickness are profiled as a function of depth by strain gauge measurements during controlled etching in the selected areas. Measurements of stress release under etching provide clear evidence that the investigated shells, in fact, are strained multilayered structures, which are elastically bent due to the forces evolving at the organic/inorganic interfaces. The stresses are mostly concentrated in the "fresh" nacre sub-layers near the inner surface of the shell adjacent to the mollusk mantle. This analysis unexpectedly shows that the elastic bending of the nacre layer is due to strain gradients which are originated in the gradual in-depth changes of the thickness of ceramic lamellae. The changes mentioned were directly observed by scanning electron microscopy. By this sophisticated design of the ultra-structure of the nacre layer, the bowed shape of the bivalve shells is apparently achieved. [source]

Caries prevalence in Belgian children: a review

INTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 3 2001
J. Vanobbergen
A review of epidemiological surveys on dental caries prevalence, published between 1980 and 1999 in Belgian children, was compiled through a literature search. The number of studies performed in Belgium to date is limited. Methodological differences and confounding factors, especially socio-demographic influences, limit national comparisons of caries prevalence data. Although exact comparisons are difficult, data suggests a decline in caries prevalence in 5, 7 and 12 year-old Belgian schoolchildren in the last 20 years. In the primary dentition dmft values have decreased from 2·66 (1981) to 1·38 (1994) in 5-year-olds and from 4·1 (1983) to 2·24 (1996) in 7-year-olds. In 12-year-olds DMFT values in the permanent dentition have decreased from 3·9 (1983) to 1·93 (1994). WHO goals for the year 2000 appear to have been already reached in Flanders, with a recent estimate of 1·93 for DMFT in 12-year-olds and 56% of children being recorded as caries free at the age of 5. Continuing efforts are needed to screen the oral health of different age groups but standardised criteria and sampling procedures should be used if benefits are to be gained from national and international comparison. Data has often been limited to small selected areas and information representing the entire community of Flanders or Wallonia would be of particular value. [source]

Regional cerebral glucose metabolism during sevoflurane anaesthesia in healthy subjects studied with positron emission tomography

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2010
L. SCHLÜNZEN
Background: The precise mechanism by which sevoflurane exerts its effects in the human brain remains unknown. In the present study, we quantified the effects of sevoflurane on regional cerebral glucose metabolism (rGMR) in the human brain measured with positron emission tomography. Methods: Eight volunteers underwent two dynamic 18F-fluorodeoxyglucose positron emission tomography (PET) scans. One scan assessed conscious-baseline metabolism and the other scan assessed metabolism during 1 minimum alveolar concentration (MAC) sevoflurane anaesthesia. Cardiovascular and respiratory parameters were monitored and bispectral index responses were registered. Statistical parametric maps and conventional regions of interest analysis were used to determine rGMR differences. Results: All subjects were unconsciousness at 1.0 MAC sevoflurane. Cardiovascular and respiratory parameters were constant over time. In the awake state, rGMR ranged from 0.24 to 0.35 ,mol/g/min in the selected regions. Compared with the conscious state, total GMR decreased 56% in sevoflurane anaesthesia. In white and grey matter, GMR was averaged 42% and 58% of normal, respectively. Sevoflurane reduced the absolute rGMR in all selected areas by 48,71% of the baseline (P,0.01), with the most significant reductions in the lingual gyrus (71%), occipital lobe in general (68%) and thalamus (63%). No increases in rGMR were observed. Conclusions: Sevoflurane caused a global whole-brain metabolic reduction of GMR in all regions of the human brain, with the most marked metabolic suppression in the lingual gyrus, thalamus and occipital lobe. [source]

Benchmarking productive efficiency of selected wheat areas in Pakistan and India using data envelopment analysis,

IRRIGATION AND DRAINAGE, Issue 4 2006
Naeem M. Malana
MEG (/DEA); analyse comparative; productivité de l'irrigation; productivité; blé; Pakistan; Inde Abstract Food demand is bound to increase significantly in future as a result of a growing world population. As a large proportion of the available land and water resources have been developed, there is limited scope for further increase in the use of these resources. Thus future increases in food production will originate from improvements in performance of existing agriculture rather than development of new resources. It is anticipated that wheat demand in the South Asia will rise significantly in future. In order to increase production and overcome diminishing water availability for irrigation, performance of wheat farms must increase. This paper describes the process of benchmarking the productive efficiency of wheat in selected areas of Pakistan and India. Data envelopment analysis (DEA) is used to evaluate and rank productivity performance of wheat growing areas in both countries based on three inputs: irrigation (m3,ha,1), seed (kg,ha,1) and fertiliser use (kg,ha,1). The results of analysis show that DEA is an effective tool for analysing and benchmarking productive efficiency of agricultural units. Ranking of productive efficiency based on three inputs is also shown to differ significantly from that based on a single resource (irrigation). Copyright © 2006 John Wiley & Sons, Ltd. La demande de nourriture est appelée à augmenter de façon significative du fait de la croissance de la population mondiale. Une forte proportion des ressources en terre et en eau ayant déjà été utilisée, leur potentiel d'accroissement est faible. La production supplémentaire de nourriture devra donc venir de l'amélioration des performances de l'agriculture plutôt que du développement de nouvelles ressources. Il est prévu que la demande de blé en Asie du Sud-Est augmente significativement dans le future. Afin d'augmenter la production et de surmonter la raréfaction de l'eau pour l'irrigation, la performance de la culture du blé doit progresser. Cet article décrit le processus d'analyse comparative appliquée à la productivité de certaines zones à blé du Pakistan et de l'Inde. La Méthode d'Enveloppe Graphique (MEG) est utilisée pour évaluer et classer les productivités des zones à blé de ces deux pays sur la base de trois intrants: l'irrigation (m3/ha), les semences (kg/ha) et les engrais (kg/ha). Les résultats de l'analyse montrent que la MEG est un outil efficace pour l'analyse comparative des productivités d'exploitations agricoles. Le classement des productivités à partir de trois intrants est également différent de celui obtenu à partir d'une seule ressource (l'irrigation). Copyright © 2006 John Wiley & Sons, Ltd. [source]

Quantification of Mucosa oxygenation using three discrete spectral bands of visible light

JOURNAL OF BIOPHOTONICS, Issue 12 2009
2Article first published online: 10 AUG 200, Y. Fawzy
Abstract Quantification of the mucosa oxygenation levels during Endoscopic imaging provides useful physiological/diagnostic information. In this work a method for non-contact quantification of the oxygen saturation index during Endoscopic imaging using three discrete spectral-band in the blue, the green, and the red parts of the spectrum (RGB bands) has been investigated. The oxygen saturation index (TOI_rgb) was calculated from the three discrete RGB spectral bands using diffusion approximation modeling and least-square analysis. A parametric study performed to identify the optimum band width for each of the three spectral bands. The quantification algorithm was applied to in vivo images of the endobronchial mucosa to calculate (TOI_rgb) from selected areas within the image view. The results were compared to that obtained from the full visible spectral (470,700 nm, 10 nm) measurements. The analysis showed that a band width of at least 20 nm in the blue and the green is required to obtain best results. The results showed that the method provides accurate estimation of the oxygenation levels with about 90% accuracy compared to that obtained using the full spectra. The results suggest the potential of quantifying the oxygen saturation levels from the three narrow RGB spectral bands/images. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Exclusion of livestock grazing and wood collection in dryland savannah: an effect on long-term vegetation succession

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010
Pavla Hejcmanová
Abstract Sahelian savannah faces increasing pressure from human activities, leading to its degradation. The aim of this study was to investigate the possibility of restoration of dryland savannah vegetation by the elimination of disturbance factors on the ecosystem. Is degraded dryland savannah vegetation able to be restored by means of natural succession? What is the timescale for its recovery? The study took place in the Bandia Reserve, 65 km south-east of Dakar (Senegal), a unique site with two successional stages due to the elimination of uncontrolled exploitation. The vegetation structure of 15 years (15YRS) and 5 years (5YRS) after fencing was compared with vegetation exposed to continuous livestock grazing and wood collection outside the fenced area. Calculated by redundancy analysis, a significant effect of selected areas on the cover of all species was revealed and successional stage explained more than 45% of data variability. Perennial forbs, annual forbs and perennial grasses achieved the highest cover in 5YRS, woody species in 15YRS and annual grasses in the area outside of the fenced reserve. The dominant woody species Acacia seyal, A. ataxacantha, A. nilotica subsp. adstringens and Balanites aegyptiaca reconstituted the dense formation of Acacia bushland by means of natural succession in the 15YRS area. Résumé La savane sahélienne subit une pression croissante des activités humaines, qui entraînent sa dégradation. Le but de cette étude était d'étudier la possibilité de restaurer la végétation de la savane sèche en éliminant les facteurs de perturbation de l'écosystème. La végétation de savane sèche est-elle capable de se rétablir par voie de succession naturelle ? Quelle est l'échelle de temps de cette restauration ? Cette étude a eu lieu dans la Réserve de Bandia, située à 65 km au sud-est de Dakar (Sénégal), un site unique qui enclot deux stades de succession en raison de la fin de son exploitation incontrôlée. La structure de la végétation qui s'est développée quinze ans (15 A) et cinq ans (5 A) après la pose d'une clôture a été comparée à la végétation exposée au pâturage continu du bétail et à la collecte de bois, en dehors de la clôture. Une analyse de redondance a révélé un effet significatif des zones choisies sur la couverture de toutes les espèces, et le stade de succession a permis d'expliquer plus de 45% de la variabilité des données. Les dicotylédones pérennes et annuelles et les monocotylédones pérennes atteignaient la plus grande couverture en 5 A, les espèces ligneuses en 15 A, et les monocotylédones annuelles dans la zone située en dehors de l'aire clôturée. Les espèces ligneuses dominantes, Acacia seyal, A. ataxacantha, A. nilotica subsp. adstringens et Balanites aegyptiaca ont reconstitué la formation dense d'une brousse àAcacia par la succession naturelle dans la zone 15 A. [source]

Low-Temperature Preparation and Magnetic Properties of Nanoparticle Iron-Doped Anatase TiO2

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2007
Khaled Melghit
Nanoparticle iron (Fe)-doped anatase TiO2 was prepared at a low temperature (100°C) and at room pressure. The product was obtained from a boiling solution of an amorphous TiO2 gel mixed with an iron nitrate solution and stirred for 5 h. An amorphous TiO2 gel was obtained from TiCl3 solution and NH4OH as a precipitating agent stirred at room temperature for 1 day. EDAX results on different selected areas of as-prepared Fe-doped anatase TiO2 revealed a homogeneous composition of 17 at.% Fe. Fe,TiO2 has a superparamagnetic state with a possibility of antiferromagnetism at low temperatures. Fe seems to substitute titanium ions without any evidence of other impurities such as Fe nanoclusters or Fe-based oxides. [source]

Use of Synthetic Aperture Radar for Selecting Alaskan Lakes for Winter Water Use,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2008
D.M. White
Abstract:, Water resources are limited in many areas of the North Slope, Alaska, particularly during winter. Water is used by the oil industry for ice road construction and maintenance, drilling and facility operations, and potable water supplies. The coastal plain between Teshekpuk Lake, in the National Petroleum Reserve-Alaska (NPR-A) and the Colville River has numerous shallow lakes, but further south in the northern foothills of the Brooks Range, and east to the Canning River, lakes are fewer. While many oil and gas lease sales have been conducted, or are proposed, access to the leases may be limited because of the lack of available water for ice road construction. Ice roads are the main means by which exploration is conducted in the Arctic, putting a stress on freshwater bodies that do not freeze to the lakebed in winter. Lakes that do not freeze to the lakebed also serve as overwintering habitat for fish. The purpose of this paper is to report on the potential distribution of water bodies that may provide overwinter water in selected areas from Teshekpuk Lake to the Canning River. The project used synthetic aperture radar (SAR) imagery to search for the presence of water in lakes in March 2006. In the Kuparuk and Canning SAR images, 52 and 61% of lakes were frozen to their beds by March 2006, accounting for 49 and 57% of the lake area in these study regions. Conversely, only 2% of the lakes in the Teshekpuk region were frozen to the bottom by March 2006. Unfrozen water was more available because of deeper and more numerous lakes in the Teshekpuk Lake region (west) than in the Canning River area (east). While only specific SAR tiles were analyzed herein, the method will be a useful tool for land managers who seek to evaluate the potential for ice road construction across the Arctic. [source]

MELD,Moving steadily towards equality, equity, and fairness

LIVER TRANSPLANTATION, Issue 5 2005
James Neuberger
Background and aims: A consensus has been reached that liver donor allocation should be based primarily on liver disease severity and that waiting time should not be a major determining factor. Our aim was to assess the capability of the Model for End-Stage Liver Disease (MELD) score to correctly rank potential liver recipients according to their severity of liver disease and mortality risk on the OPTN liver waiting list. Methods: The MELD model predicts liver disease severity based on serum creatinine, serum total bilirubin, and INR and has been shown to be useful in predicting mortality in patients with compensated and decompensated cirrhosis. In this study, we prospectively applied the MELD score to estimate 3-month mortality to 3437 adult liver transplant candidates with chronic liver disease who were added to the OPTN waiting list at 2A or 2B status between November, 1999, and December, 2001. Results: In this study cohort with chronic liver disease, 412 (12%) died during the 3-month follow-up period. Waiting list mortality increased directly in proportion to the listing MELD score. Patients having a MELD score <9 experienced a 1.9% mortality, whereas patients having a MELD score > or =40 had a mortality rate of 71.3%. Using the c-statistic with 3-month mortality as the end point, the area under the receiver operating characteristic (ROC) curve for the MELD score was 0.83 compared with 0.76 for the Child-Turcotte-Pugh (CTP) score (P < 0.001). Conclusions: These data suggest that the MELD score is able to accurately predict 3-month mortality among patients with chronic liver disease on the liver waiting list and can be applied for allocation of donor livers.(Gastroenterology 2003;124:91,96.) Context: The Model for Endstage Liver Disease (MELD) score serves as the basis for the distribution of deceased-donor (DD) livers and was developed in response to "the final rule" mandate, whose stated principle is to allocate livers according to a patient's medical need, with less emphasis on keeping organs in the local procurement area. However, in selected areas of the United States, organs are kept in organ procurement organizations (OPOs) with small waiting lists and transplanted into less-sick patients instead of being allocated to sicker patients in nearby transplant centers in OPOs with large waiting lists. Objective: To determine whether there is a difference in MELD scores for liver transplant recipients receiving transplants in small vs large OPOs. Design and setting: Retrospective review of the US Scientific Registry of Transplant Recipients between February 28, 2002, and March 31, 2003. Transplant recipients (N = 4798) had end-stage liver disease and received DD livers. Main outcome measures: MELD score distribution (range, 6,40), graft survival, and patient survival for liver transplant recipients in small (<100) and large (> or =100 on the waiting list) OPOs. RESULTS: The distribution of MELD scores was the same in large and small OPOs; 92% had a MELD score of 18 or less, 7% had a MELD score between 19 and 24, and only 2% of listed patients had a MELD score higher than 24 (P = .85). The proportion of patients receiving transplants in small OPOs and with a MELD score higher than 24 was significantly lower than that in large OPOs (19% vs 49%; P<.001). Patient survival rates at 1 year after transplantation for small OPOs (86.4%) and large OPOs (86.6%) were not statistically different (P = .59), and neither were graft survival rates in small OPOs (80.1%) and large OPOs (81.3%) (P = .80). Conclusions: There is a significant disparity in MELD scores in liver transplant recipients in small vs large OPOs; fewer transplant recipients in small OPOs have severe liver disease (MELD score >24). This disparity does not reflect the stated goals of the current allocation policy, which is to distribute livers according to a patient's medical need, with less emphasis on keeping organs in the local procurement area. (JAMA 2004;291:1871,1874.) [source]

Silica as a shock index in shergottites: A cathodoluminescence study

METEORITICS & PLANETARY SCIENCE, Issue 7 2005
Hasnaa CHENNAOUI AOUDJEHANE
Determining its structural state as either silica glass, quartz, cristobalite, tridymite, coesite, stishovite, or post-stishovite could provide informations about their shock history. The purpose of this work is to assess the shock intensity in shergottites using two spectroscopic methods. On a conventional polished section, a scanning electron microscope (SEM) enables us to study the cathodoluminescence (CL) of silica at variable magnification. The results were crosschecked by systematic Raman spectroscopy of the selected areas. CL spectra differ substantially from one another and enable separating stishovite, high and low pressure silica glass, quartz, and cristobalite. We studied a set of five shergottites: Northwest Africa (NWA) 480, NWA 856, Zagami, Shergotty, and Los Angeles. Stishovite is common in Shergotty, Zagami, NWA 856, and NWA 480 and absent in the studied section of Los Angeles. High-pressure glass is very common, particularly in close association with stishovite. According to the textural relationship, it may be a product of the retromorphosis (amorphization during decompression) of stishovite. Large stishovite areas result from the transformation of preexisting low-pressure silica crystals, while needles result from the high-pressure transformation of pyroxene to glass (melt) and silica. In the latter case, they are found in melt pockets and represent a small fraction of areas of overall pyroxene composition. Needles exhibit square sections of about 1 ,m. Silica spots identical to those described previously as post-stishovite are found in Shergotty, Zagami, NWA 480, and NWA 856. At present, the spectroscopic distinction of post-stishovite from stishovite is difficult. Post-stishovite is destroyed under the Raman beam, and CL spectra are possible mixtures of several phases (e.g., glass and post-stishovite). It is concluded that the shock intensity is highly heterogeneous, and the pressure probably exceeded 60 GPa in all shergottites studied here. [source]

Structures of the magnetoionic media around the Fanaroff,Riley Class I radio galaxies 3C 31 and Hydra A

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2008
R. A. Laing
ABSTRACT We use high-quality Very Large Array (VLA) images of the Fanaroff,Riley Class I radio galaxy 3C 31 at six frequencies in the range 1365,8440 MHz to explore the spatial scale and origin of the rotation measure (RM) fluctuations on the line of sight to the radio source. We analyse the distribution of the degree of polarization to show that the large depolarization asymmetry between the north and south sides of the source seen in earlier work largely disappears as the resolution is increased. We show that the depolarization seen at low resolution results primarily from unresolved gradients in a Faraday screen in front of the synchrotron-emitting plasma. We establish that the residual degree of polarization in the short-wavelength limit should follow a Burn law and we fit such a law to our data to estimate the residual depolarization at high resolution. We discuss how to interpret the structure function of RM fluctuations in the presence of a finite observing beam and how to address the effects of incomplete sampling of RM distribution using a Monte Carlo approach. We infer that the observed RM variations over selected areas of 3C 31, and the small residual depolarization found at high resolution, are consistent with a power spectrum of magnetic fluctuations in front of 3C 31 whose power-law slope changes significantly on the scales sampled by our data. The power spectrum P(f) can only have the form expected for Kolmogorov turbulence [P(f) ,f,11/3] on scales ,5 kpc. On larger scales, we find . We briefly discuss the physical interpretation of these results. We also compare the global variations of RM across 3C 31 with the results of three-dimensional simulations of the magnetic-field fluctuations in the surrounding magnetoionic medium. We infer that the RM variation across 3C 31 is qualitatively as expected from relativistic-jet models of the brightness asymmetry wherein the apparently brighter jet is on the near side of the nucleus and is seen through less magnetoionic material than the fainter jet. We show that our data are inconsistent with observing 3C 31 through a spherically symmetric magnetoionic medium, but that they are consistent with a field distribution that favours the plane perpendicular to the jet axis , probably because the radio source has evacuated a large cavity in the surrounding medium. We also apply our analysis techniques to the case of Hydra A, where the shape and the size of the cavities produced by the source in the surrounding medium are known from X-ray data. We emphasize that it is essential to account for the potential exclusion of magnetoionic material from a large volume containing the radio source when using the RM variations to derive statistical properties of the fluctuations in the foreground magnetic field. [source]

Quality of life of children and adolescents after kidney or liver transplantation: Child, parents and caregiver's point of view

PEDIATRIC TRANSPLANTATION, Issue 3 2003
S. Manificat
Abstract: A cross-sectional study was performed to assess quality of life (QoL) after kidney or liver transplantation during childhood. Self-questionnaires explored children, adolescent and parent QoL. Seventy-five transplant children, 36 transplant adolescents, 67 mothers, 34 fathers and 67 caregivers filled out the questionnaires; they were compared with a reference population. Children reported a rather good QoL, but their extra-family involvement appeared not as satisfactory as that of the reference population children. Adolescents reported a very high QoL when completing the structured format scale; however, their responses to open-ended questions showed qualitative differences compared with those of a reference population: they expressed concern about their body or health, less pleasure than ordinary adolescents to manage by themselves, and a poor relationship with peers. Mothers indicated a deep impact of the child's illness on their own QoL, and the need for psychological support. In conclusion, a rather good QoL is a long-lasting feature of kidney and liver transplantation in children. Such an assessment is mandatory to identify remaining impairments in some selected areas, either in the recipient or family. [source]

Copper-filled macroporous Si and cavity underneath for microchannel heat sink technology

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008
F. Zacharatos
Abstract Thermal management in ICs becomes essential as integration density and total power consumption increase. The use of microchannels in high power density electronics cooling is a well-known technique for heat transfer. In this work we developed Cu-filled macroporous Si channels with a Cu-filled cavity underneath, which may be used as heat sinks in high power density electronics cooling. Macroporous Si is formed by electrochemical dissolution of bulk Si, while pore filling with copper is achieved by electro-deposition. Using appropriate design, the resulting composite material may be fabricated on selected areas on the silicon substrate for use as heat sink on Si. The surface area is defined by patterning. The macroporous Si structure is composed of either randomly distributed pores or pores arranged in two-dimensional (2-D) arrays, fabricated by pre-patterning the Si surface before anodization so as to form pore initiation pits. The pore size in this work was 5,m, while the porous layer and the cavity underneath had both a thickness of 40 ,m. Copper deposition proceeds first by filling the micro-cavity underneath the porous layer. This is achieved by linearly increasing the applied potential during electro-deposition. After full Cu-filling of the cavity, pore filling starts from the bottom of each pore and proceeds laterally, while no nucleation takes place on pore wall. In this way, homogeneous copper wires within pores may be fabricated. The Cu/Si composite material is appropriate for forming channels with improved heat transfer within the Si wafer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A practical approach to steam-enhanced dual-phase extraction: A case study

REMEDIATION, Issue 3 2003
David P. Bouchard
This article presents the results of a pilot test that was conducted to determine the effectiveness of using steam-enhanced dual-phase extraction (DPE) at a former industrial site in New York. The pilot test proved that steam-enhanced DPE was very effective at removing significant contaminant mass from the subsurface in a relatively short time period. Concentrations of volatile organic compounds and semivolatile organic compounds in the vapor stream and groundwater were successfully reduced, in some cases by orders of magnitude. Based on the results of the steam-enhanced DPE pilot test, the final remedy for the site includes implementing this technology at selected areas as an alternative to DPE alone or other remedial alternatives, such as excavation or groundwater pump and treat. © 2003 Wiley Periodicals, Inc. [source]

The value of observations.

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 628 2007
II: The value of observations located in singular-vector-based target areas
Abstract Data-assimilation experiments have been run in seven different configurations for two seasons to assess the value of observations taken in target regions identified either using singular vectors (SVs) or randomly, and located over the Pacific or the Atlantic Oceans. The value has been measured by the relative short-range forecast error reduction in downstream areas, specifically a North American region for observations taken in the Pacific Ocean, and a European region for observations taken in the Atlantic Ocean. Overall, results have indicated (1) that observations taken in SV-target areas are on average more valuable than observations taken in randomly selected areas, (2) that it is important that the daily set of singular vectors are used to compute the target areas, and (3) that the value of targeted observations depends on the region, the season and the baseline observing system. If the baseline observing system is data-void over the ocean, then the average value of observations taken in SV-target areas is very high. Considering for example winter 2004, SV-targeted observations over the Pacific (Atlantic) reduce the day-2 forecasts error of 500 hPa geopotential height forecasts in the verification region by 27.5% (19.1%), compared to 15.7% (14.9%) for observations taken in random areas. By contrast, if the baseline observing system is data-rich over the ocean, then the average value of observations taken in SV-target areas is rather small. Considering for example winter 2004, it has been estimated that adding SV-targeted observations over the Pacific (Atlantic) would reduce, on average, the day-2 forecasts error in the verification region by 4.0% (2.0%), compared to 0.5% (1.7%) for observations in random areas. These average results have been confirmed by single-case investigations, and by a careful examination of time series of forecast errors. These results indicate that more accurate assimilation systems that can exploit the potential value of localized observations are needed to increase the average return of investments in targeting field experiments. Copyright © 2007 Royal Meteorological Society [source]

The value of observations.

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 628 2007
III: Influence of weather regimes on targeting
Abstract This paper assesses the value of targeted observations over the North Atlantic Ocean for different meteorological flow regimes. It shows that during tropical cyclone activity and particularly tropical cyclone transition to extratropical characteristics, removing observations in sensitive regions, indicated by singular vectors optimized on the 2-day forecast over Europe, degrades the skill of a given forecast more so than excluding observations in randomly selected regions. The maximum downstream degradation computed in terms of spatially and temporally averaged root-mean-square error of 500 hPa geopotential height is about 13%, a value which is 6 times larger than when removing observations in randomly selected areas. The forecast impact for these selected periods, resulting from degrading the observational coverage in sensitive areas, was similar to the impact found (elsewhere in other weather forecast systems) for the observational targeting campaigns carried out over recent years, and it was larger than the average impact obtained by considering a larger set of cases covering various seasons. Copyright © 2007 Royal Meteorological Society [source]

Decrease in intrahepatic CD56+ lymphocytes in gastric and colorectal cancer patients with liver metastases

APMIS, Issue 12 2009
MAYA GULUBOVA
The aim of the study was to examine the main intrahepatic lymphocyte subpopulations, namely CD3+ lymphocytes, natural killer (NK)-like T lymphocytes (NKT) expressing the CD3+ CD56+ phenotype, CD56+ NK cells, CD4+, and CD8+ T cells in livers of patients with gastric and colorectal cancer with and without hepatic metastases. The proportion of each lymphocyte subset was determined in 34 patients with gastric or colorectal cancer (18 with and 16 without liver metastasis) by two-color flow cytometry after extraction of hepatic mononuclear cell fraction. The distribution of lymphocyte subpopulations in selected areas of liver metastases and adjacent liver tissue was evaluated using immunohistochemistry for CD4, CD8, and CD56. Flow cytometry analysis revealed a significant decrease in the proportion of CD3+ CD56+ cells in metastatic livers, but not in nonmetastatic livers (11.9 ± 10.3 vs 24.2 ± 13.6%, p = 0.02). The percentage of intrahepatic CD3,CD56+ cells was also decreased in patients with metastases compared to those without (10.1 ± 11.6 vs 16.6 ± 8.9%, p = 0.039). Immunohistochemically, three types of lymphocytes (CD4+, CD8+, and CD56+) were present in the metastatic tissue, although the number of CD56+ cells was almost twice lower. We found a low prevalence of tumor-infiltrating CD4+, CD8+, and CD56+ cells in livers with multiple metastases, whereas in cases with solitary metastasis a higher degree of lymphocyte infiltration was observed. The number of CD3,CD56+ and CD3+ CD56+ cells was decreased in metastatic livers compared to those unaffected by metastases. Therefore the prevalence of tumor-infiltrating lymphocytes seems to be related to the progression of metastatic liver disease. Depletion of hepatic innate lymphocytes may reveal susceptibility to metastatic liver disease and could be a reason for the escape of metastatic cells from the mechanisms of liver immune control. [source]