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Oasis
Kinds of Oasis Terms modified by Oasis Selected AbstractsOASIS® wound matrix versus Hyaloskin® in the treatment of difficult-to-heal wounds of mixed arterial/venous aetiologyINTERNATIONAL WOUND JOURNAL, Issue 1 2007Marco Romanelli Abstract Mixed arterial/venous (A/V) ulcers are difficult to treat and slow to heal likely as a result of deficiencies in molecular and cellular elements in the wound bed. Recently, biomaterials have been developed that replace extracellular matrix (ECM) molecules and growth factors critical to the normal healing process. In this study, the effects of OASIS® and Hyaloskin® were evaluated to compare the effectiveness of these two ECM-based products in their ability to achieve complete wound healing of mixed A/V ulcers. After 16 weeks of treatment, patients in each group were evaluated on four criteria: complete wound healing, time to dressing change, pain and comfort. Complete wound closure was achieved in 82·6% of OASIS® -treated ulcers compared with 46·2% of Hyaloskin® -treated ulcers (P < 0·001). Statistically significant differences favouring the OASIS® treatment group were also reported for time to dressing change (P < 0·05), pain (P < 0·05) and patient comfort (P < 0·01). Overall, OASIS® was superior to Hyaloskin® for the treatment of patients with mixed A/V ulcers, a population in which standard treatment options largely consist of moist wound dressings and compression therapy is typically not an option. OASIS® is a useful and well-tolerated treatment for mixed A/V ulcers that has the potential to improve quality of life and reduce costs associated with standard of care. [source] Accuracy in the outcomes and assessment information set (OASIS): Results of a video simulationRESEARCH IN NURSING & HEALTH, Issue 4 2003Elizabeth A. Madigan Abstract There is little information regarding the accuracy of the Outcomes and Assessment Information Set (OASIS), the patient assessment tool mandated for use in Medicare-funded home health care. The purposes of this study were to evaluate the accuracy of OASIS completion by home health nurses and rehabilitation therapists, to compare responses of nurses and therapists, and to determine whether dispersion of answers would affect the home health resource group (HHRG) to which patients were assigned for Medicare home health care payments to agencies. Using a video simulation of admission and discharge visits, 436 clinicians from 29 Ohio home health care agencies scored selected OASIS items. Although the majority of the items were rated accurately, discrepancies were found between clinician responses and the "correct" answer on several items. Nurses and therapists provided similar ratings on most items studied, but for most cases in which discrepancies were found, nurses were more likely to agree with the "correct" answer. Discrepancies most often led to patients being assigned to lower-payment HHRGs. Continued monitoring of OASIS data collection accuracy is recommended to maximize the value of the OASIS instrument in home health care research, practice, and policy. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:273,283, 2003 [source] ARCHAEOMAGNETIC FIELD INTENSITY DURING THE ROMAN PERIOD AT SIWA AND BAHRYN OASIS, EGYPT: IMPLICATIONS FOR THE FIDELITY OF EGYPTIAN ARCHAEOMAGNETIC DATAARCHAEOMETRY, Issue 3 2010R. LEONHARDT A preliminary survey was conducted in Siwa and Bahryn Oasis to test the possible influence of various rock magnetic and experimental constraints on the fidelity of the Egyptian archaeomagnetic field record. Five potsherds from the Roman era, which lasted from 1981 bp to 1555 bp, have been investigated. Archaeologists dated the localities to ,1620 bp. Ten ceramic specimens, two of each potsherd, were subjected to archaeointensity determination, including tests for domain state effects, magnetic anisotropy and magnetic cooling rate dependency. Six successful archaeointensity determinations are obtained from three individual cooling units, revealing an average field value of 37.7 ,T for the late Roman period in Siwa and Bahryn oasis, which is comparable to the present-day field strength. The error propagation of the individual uncertainties related to all applied experimental techniques results in a maximum uncertainty estimate of 4.4 ,T. The obtained field value is significantly smaller than early results and slightly smaller than some more recent determinations of the field intensity in Egypt. The difference is attributed to a combined effect of alteration, magnetic anisotropy and magnetic cooling rate dependencies. Along with other high-quality data from the south-east Mediterranean, our data suggest a field intensity minimum during the Egyptian Roman era. [source] Direct-method SAD phasing of proteins enhanced by the use of intrinsic bimodal phase distributions in the subsequent phase-improvement processACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2009Li-Jie Wu A modified SAD (single-wavelength anomalous diffraction) phasing algorithm has been introduced in the latest version of the program OASIS. In addition to direct-method phases and figures of merit, Hendrickson,Lattman coefficients that correspond to the original unresolved bimodal phase distributions are also output and used in subsequent phase-improvement procedures in combination with the improved phases. This provides the possibility of rebreaking the SAD phase ambiguity using the ever-improving phases resulting from the phase-improvement process. Tests using experimental SAD data from six known proteins showed that in all cases the new treatment produced significant improved results. [source] Patterns of bacterial diversity across a range of Antarctic terrestrial habitatsENVIRONMENTAL MICROBIOLOGY, Issue 11 2007Etienne Yergeau Summary Although soil-borne bacteria represent the world's greatest source of biological diversity, it is not well understood whether extreme environmental conditions, such as those found in Antarctic habitats, result in reduced soil-borne microbial diversity. To address this issue, patterns of bacterial diversity were studied in soils sampled along a > 3200 km southern polar transect spanning a gradient of increased climate severity over 27° of latitude. Vegetated and fell-field plots were sampled at the Falkland (51°S), South Georgia (54°S), Signy (60°S) and Anchorage Islands (67°S), while bare frost-sorted soil polygons were examined at Fossil Bluff (71°S), Mars Oasis (72°S), Coal Nunatak (72°S) and the Ellsworth Mountains (78°S). Bacterial 16S rRNA gene sequences were recovered subsequent to direct DNA extraction from soil, polymerase chain reaction amplification and cloning. Although bacterial diversity was observed to decline with increased latitude, habitat-specific patterns appeared to also be important. Namely, a negative relationship was found between bacterial diversity and latitude for fell-field soils, but no such pattern was observed for vegetated sites. The Mars Oasis site, previously identified as a biodiversity hotspot within this region, proved exceptional within the study transect, with unusually high bacterial diversity. In independent analyses, geographical distance and vegetation cover were found to significantly influence bacterial community composition. These results provide insight into the factors shaping the composition of bacterial communities in Antarctic terrestrial habitats and support the notion that bacterial diversity declines with increased climatic severity. [source] A reconstruction of Quaternary pluvial environments and human occupations using stratigraphy and geochronology of fossil-spring tufas, Kharga Oasis, EgyptGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 5 2004Jennifer R. Smith We carried out a geologic survey and a preliminary archaeological survey of four fossil-spring tufa localities in Kharga Oasis, Egypt, to constrain the timing of pluvial episodes in the Western Desert, and to document prehistoric occupation contemporaneous with times of increased rainfall. Uranium-series dating of the tufas confirms that at least five episodes of tufa deposition are represented in Kharga, although not every event is represented at each locality. Across the region studied, tufas were most frequently deposited as part of a fluvial barrage system, characterized by terraced, vegetated pools impounded by arcuate tufa dams and separated by small waterfalls. Available water resources during pluvial phases would have included not only spring-fed streams but also small freshwater lakes. While Earlier Stone Age (ESA) and Middle Stone Age (MSA) lithic artifacts may be found either as surficial lags on tufas, or, less commonly, encased within tufas, Epipalaeolithic and Neolithic artifacts are generally found in or on silts within surface deflation depressions in the tufas, principally at Wadi Midauwara. © 2004 Wiley Periodicals, Inc. [source] Spinal pathological findings in ancient Egyptians of the Greco-Roman period living in Bahriyah OasisINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2009F. H. Hussien Abstract The spine can provide a large amount of information about an individual's physical condition and possible lifestyle through palaeopathological investigations. The aim of this research was to study spinal diseases among Greco-Roman ancient Egyptians from Bahriyah Oasis, and to compare them with those from Giza of the Old Kingdom. The material used in the study included 809 single vertebrae and 77 adult sacra of ancient Egyptians from the Greco-Roman period (332,30 BC) that were excavated from Bahriyah Oasis. The spinal elements were examined for pathological conditions, degenerative diseases, trauma, congenital abnormalities, infectious diseases and neoplasms. The most common lesions of the spine were those due to degenerative processes. The articular facets were more affected than the vertebral bodies. Compression fractures of the bodies, mostly due to osteoporosis, were found in 1.44% and 5.07% of thoracic and lumbar vertebrae respectively. The percentage of spina bifida occulta among ancient Egyptians from Bahriyah Oasis was 62.33%, while among those from Giza was only 3.33%. Few cases of lumbar spondylolysis and one case of DISH were recorded. No cases of infectious or neoplastic diseases were found. Copyright © 2008 John Wiley & Sons, Ltd. [source] Roman Period fetal skeletons from the East Cemetery (Kellis 2) of Kellis, EgyptINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2005M. W. Tocheri Abstract Much can be learned about the religious ideology and mortuary patterns as well as the demographic and health profiles of a population from archaeological human fetal skeletons. Fetal skeletons are rare, however, largely due to poor preservation and recovery, misidentification, or non-inclusion in general burial populations. We present an analysis of 82 fetal/perinatal skeletons recovered from Kellis 2, a Roman Period cemetery dated to the third and fourth centuries AD, located in the Dakhleh Oasis, Egypt. Most of the fetal remains were individually wrapped in linen and all were buried among the general cemetery population in a supine, east,west orientation with the head facing to the west. Gestational age estimates are calculated from diaphysis lengths using published regression and Bayesian methods. The overall similarity between the fetal age distributions calculated from the regression and Bayesian methods suggests that the correlation between diaphysis length and gestational age is typically strong enough to avoid the ,regression' problem of having the age structure of reference samples adversely affecting the age distribution of target samples. The inherent bias of the regression methods, however, is primarily reflected in the gestational age categories between 36 and 42 weeks corresponding with the expected increase in growth variation during the late third trimester. The results suggest that the fetal age distribution at Kellis 2 does not differ from the natural expected mortality distribution. Therefore, practices such as infanticide can be ruled out as having a significant effect on the observed mortality distribution. Moreover, the Kellis 2 sample is well represented in each gestational age category, suggesting that all premature stillbirths and neonatal deaths received similar burial rites. The age distribution of the Kellis 2 fetal remains suggests that emerging Christian concepts, such as the ,soul' and the ,afterlife', were being applied to everyone including fetuses of all gestational ages. Copyright © 2005 John Wiley & Sons, Ltd. [source] Oasis: Onboard autonomous science investigation system for opportunistic rover scienceJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2007Rebecca Castano The Onboard Autonomous Science Investigation System has been developed to enable a rover to identify and react to serendipitous science opportunities. Using the FIDO rover in the Mars Yard at JPL, we have successfully demonstrated a fully autonomous opportunistic science system. The closed loop system tests included the rover acquiring image data, finding rocks in the image, analyzing rock properties and identifying rocks that merit further investigation. When the system on the rover alerts the rover to take additional measurements of interesting rocks, the planning and scheduling component determines if there are enough resources to meet this additional science data request. The rover is then instructed to either turn toward the rock, or to actually move closer to the rock to take an additional, close-up image. Prototype dust devil and cloud detection algorithms were delivered to an infusion task which refined the algorithms specifically for Mars Exploration Rovers (MER). These algorithms have been integrated into the MER flight software and were recently uploaded to the rovers on Mars. © 2007 Wiley Periodicals, Inc. [source] Ground-penetrating radar and magnetic survey to the west of Al-Zayyan Temple, Kharga Oasis, Al-Wadi Al-Jadeed (New Valley), EgyptARCHAEOLOGICAL PROSPECTION, Issue 2 2002Dr. Hiroyuki Kamei Abstract Al-Zayyan Temple or Qasr Al-Zayyan might be regarded as one in a chain of several fortresses that the Romans built to secure the salver's trade caravan route between Asyut and Sudan, known as Darb Al-Arbain. Al-Zayyan temple lies about 25 km south of Al-Kharga city, the capital of the New Valley, and deviates to the east of Al-Kharga-Paris main road some 2 km along the Al-Zayyan-Aarif minor road. The background information about the temple is very scarce, and even what is known is neither clear nor accurate. Some indications have ascribed it to Amenebis and that it was restored during the reign of Emperor Antoninus (AD 138,161). An integrated ground-penetrating radar (GPR)survey using the SIR 2000 Geophysical Survey Systems, Inc. (GSSI) together with magnetic survey using FM36 (GeoScan) and the three component fluxgate gradiometer TRM-70D (Tokin) have been applied to the western side of the temple. The results show relatively large-scale buried structures in a direction intersecting that of the present temple at about 45°. Some particular features within the structure have been speculatively ascribed on the basis of comprehending their signatures in the GPR sections. The magnetic results have improved the identification of some objects revealed by the GPR and provided ideas about some of the other features. Copyright © 2002 John Wiley & Sons, Ltd. [source] ARCHAEOMAGNETIC FIELD INTENSITY DURING THE ROMAN PERIOD AT SIWA AND BAHRYN OASIS, EGYPT: IMPLICATIONS FOR THE FIDELITY OF EGYPTIAN ARCHAEOMAGNETIC DATAARCHAEOMETRY, Issue 3 2010R. LEONHARDT A preliminary survey was conducted in Siwa and Bahryn Oasis to test the possible influence of various rock magnetic and experimental constraints on the fidelity of the Egyptian archaeomagnetic field record. Five potsherds from the Roman era, which lasted from 1981 bp to 1555 bp, have been investigated. Archaeologists dated the localities to ,1620 bp. Ten ceramic specimens, two of each potsherd, were subjected to archaeointensity determination, including tests for domain state effects, magnetic anisotropy and magnetic cooling rate dependency. Six successful archaeointensity determinations are obtained from three individual cooling units, revealing an average field value of 37.7 ,T for the late Roman period in Siwa and Bahryn oasis, which is comparable to the present-day field strength. The error propagation of the individual uncertainties related to all applied experimental techniques results in a maximum uncertainty estimate of 4.4 ,T. The obtained field value is significantly smaller than early results and slightly smaller than some more recent determinations of the field intensity in Egypt. The difference is attributed to a combined effect of alteration, magnetic anisotropy and magnetic cooling rate dependencies. Along with other high-quality data from the south-east Mediterranean, our data suggest a field intensity minimum during the Egyptian Roman era. [source] PK Politics: An Oasis of Fresh Information on PakistanASIAN POLITICS AND POLICY, Issue 4 2009Gunasekara Vagisha I. [source] Rock weathering creates oases of life in a High Arctic desertENVIRONMENTAL MICROBIOLOGY, Issue 2 2010Sara Borin Summary During primary colonization of rock substrates by plants, mineral weathering is strongly accelerated under plant roots, but little is known on how it affects soil ecosystem development before plant establishment. Here we show that rock mineral weathering mediated by chemolithoautotrophic bacteria is associated to plant community formation in sites recently released by permanent glacier ice cover in the Midtre Lovénbreen glacier moraine (78°53,N), Svalbard. Increased soil fertility fosters growth of prokaryotes and plants at the boundary between sites of intense bacterial mediated chemolithotrophic iron-sulfur oxidation and pH decrease, and the common moraine substrate where carbon and nitrogen are fixed by cyanobacteria. Microbial iron oxidizing activity determines acidity and corresponding fertility gradients, where water retention, cation exchange capacity and nutrient availability are increased. This fertilization is enabled by abundant mineral nutrients and reduced forms of iron and sulfur in pyrite minerals within a conglomerate type of moraine rock. Such an interaction between microorganisms and moraine minerals determines a peculiar, not yet described model for soil genesis and plant ecosystem formation with potential past and present analogues in other harsh environments with similar geochemical settings. [source] Seamounts: identity crisis or split personality?JOURNAL OF BIOGEOGRAPHY, Issue 12 2007Craig R. McClain Abstract At present, researchers propose that over 14,000 seamounts exist and, like their terrestrial analogues, function like islands. In addition, seamounts are described as oases, biodiversity hotspots, and lush coral/sponge gardens. Here I discuss the extent to which these tenets regarding seamounts may be inappropriate, suffer from a lack of support, and be over-generalizations of a broad range of environmental types encountered on seamounts. Ultimately, for seamount science to progress, we need to challenge our conventional wisdom on these habitats and the extent to which all seamounts function in a similar manner. [source] Adaptation of Medicago sativa cv. Gabès to long-term NaCl stressJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2005Néziha Boughanmi Abstract The perennial Medicago sativa cv. Gabès is widely grown on saline soils in Tunisian oases. The mechanisms by which this NaCl-tolerant cultivar maintains a positive growth balance were analyzed. In this plant of considerable agronomic interest, biochemical analyses were conducted in order to study the effects of salinity on mature leaves. Free-radical detoxification mechanisms and changes induced by the accumulation of reactive oxygen species (ROS) in response to the NaCl stress were compared between the upper (young) and lower (old) carbohydrate source leaves. Long-term NaCl (150 mM) treatment significantly reduced the size of source leaves supporting growth. Salinity damage was greater in the lower than in the upper leaves. This damage was associated with a high Na+ : K+ ratio and a decrease in the activity of H2O2 -scavenging enzymes, leading to lipid peroxidation. In lower source leaves that were mainly affected by ionic stress, superoxide dismutase (SOD) was overexpressed and guaiacol peroxidase (GPX) activity increased. In contrast, in upper source leaves that were mainly exposed to water deficit, catalase and ascorbate peroxidase (APX) activities increased whereas GPX activity was unchanged. The upper source leaves maintained adequate ionic and water status and an efficient ROS detoxification, allowing sinks to be supplied with photoassimilates and maintaining a positive growth balance in this cultivar of alfalfa. Anpassung von Medicago sativa cv. Gabès an Langzeit-Salzstress Die perennierende Art Medicago sativa, Sorte "Gabès", wird verbreitet auf Salzböden in tunesischen Oasen angebaut. Die Mechanismen, die eine positive Wachstumsbilanz in dieser NaCl-toleranten Luzernensorte gewährleisten, wurden untersucht. In dieser agronomisch außerordentlich wichtigen Pflanze wurden biochemische Analysen durchgeführt, um Salzeffekte auf ausgewachsene Blätter zu bestimmen. Die Mechanismen zur Entgiftung freier Radikale (ROS) und die durch die ROS verursachten Veränderungen wurden in jungen und alten "Source"-Blättern vergleichend unter Salzstressbedingungen untersucht. Eine andauernde Behandlung mit NaCl (150 mM) führte zu einer signifikanten Reduzierung der Blattfläche, wobei diese Abnahme deutlicher an den älteren unteren als an den oberen jüngeren Blättern war. Sie ging einher mit einem hohen Na+:K+ -Verhältnis und einer Abnahme der Aktivität der H2O2 -abbauenden Enzyme, was zu einer Peroxidation von Lipiden führte. Besonders in den unteren "Source"-Blättern führte der Ionenstress zu einer Überexprimierung der Superoxid-Dismutase (SOD) und einer Zunahme der Guaiakol- Peroxidaseaktivität (GPX). Demgegenüber nahmen in den oberen "Source"-Blättern, die starkem Wasserdefizit ausgesetzt waren, die Aktivitäten von Katalase und Ascorbat-Peroxidase (APX) zu, während die GPX-Aktivität unverändert blieb. Die oberen "Source"-Blätter waren in der Lage, einen adäquaten Ionen- und Wasserzustand mit Hilfe einer effizienten ROS-Entgiftung aufrechtzuerhalten, und somit einen Rückgang der Bereitstellung von Photoassimilaten zu kompensieren. Dadurch wurde eine positive Wachstumsbilanz in dieser Luzernensorte unter Salinität gewährleistet. [source] Genetic structure of Euclea schimperi (Ebenaceae) populations in monsoonal fog oases of the southern Arabian PeninsulaNORDIC JOURNAL OF BOTANY, Issue 3-4 2007Jörg Meister Euclea schimperi, a widespread Afromontane shrub or tree, occurs in the Arabian Peninsula in fragmented, semi-evergreen or evergreen woodland refugia in wet escarpment localities of the western and southern mountain chains. In the southern coastal mountains, the (semi-) evergreen woodland with E. schimperi is close to its ecological limit and consequently today very rare, with the exception of the monsoonal fog oases of east Yemen and south Oman in the central south coast of the Arabian Peninsula. Due to the steep precipitation gradient from the centre to the western edge in this monsoon affected area, E. schimperi is found in two different habitat types: in continuous woodland belts in the Hawf and Dhofar mountains, and in isolated, scattered woodland patches in the Fartak Mountains. Ten populations (138 individuals) from across the southern Arabian distribution area of the species were analysed using chloroplast microsatellites and AFLP fingerprinting to a) reconstruct the phylogeographical pattern of E. schimperi on the southern Arabian Peninsula and b) to evaluate the consequences of population fragmentation on the genetic diversity harboured in isolated patches vs cohering stands. Phylogeographical reconstructions show that the distribution area of E. schimperi in the southern Arabian Peninsula is characterised by a geographical split that separates the southwestern populations (representated by material from Jabal Eraf and Jabal Uthmar), from the southcentral populations, which themselves are split from each other into a western (Ras Fartak) and an eastern refugium (Hawf/Dhofar). The analysis of the within-population genetic diversity in E. schimperi populations resulted in a slightly, but not significantly higher genetic variation in small and isolated woodland patches (HS=0.302) compared to larger, cohering stands (HS=0.291). [source] Investigating cultural heterogeneity in San Pedro de Atacama, northern Chile, through biogeochemistry and bioarchaeologyAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Kelly J. Knudson Abstract Individuals living in the San Pedro de Atacama oases and the neighboring upper Loa River Valley of northern Chile experienced the collapse of an influential foreign polity, environmental decline, and the appearance of a culturally distinct group during the Late Intermediate Period (ca. AD 1,100,1,400). We investigate cultural heterogeneity at the Loa site of Caspana through analyses of strontium and oxygen isotopes, cranial modification styles, and mortuary behavior, integrating biological aspects of identity, particularly geographic origins, with cultural aspects of identity manifested in body modification and mortuary behavior. We test the hypothesis that the Caspana population (n = 66) represents a migrant group, as supported by archeological and ethnographic evidence, rather than a culturally distinct local group. For Caspana archeological human tooth enamel, mean 87Sr/86Sr = 0.70771 ± 0.00038 (1,, n = 30) and mean ,18Oc(V-PDB) = ,3.9 ± 0.6, (1,, n = 16); these isotopic data suggest that only one individual lived outside the region. Material culture suggests that the individuals buried at Caspana shared some cultural affinity with the San Pedro oases while maintaining distinct cultural traditions. Finally, cranial modification data show high frequencies of head shaping [92.4% (n = 61/65)] and an overwhelming preference for annular modification [75.4% (n = 46/61)], contrasting sharply with practices in the San Pedro area. Based on multiple lines of evidence, we argue that, rather than representing a group of altiplano migrants, the Caspana population existed in the region for some time. However, cranial modification styles and mortuary behavior that are markedly distinct from patterns in surrounding areas raise the possibility of cultural heterogeneity and cultural fissioning. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Horse-mounted invaders from the Russo-Kazakh steppe or agricultural colonists from western Central Asia?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2004A craniometric investigation of the Bronze Age settlement of Xinjiang Abstract Numerous Bronze Age cemeteries in the oases surrounding the Täklamakan Desert of the Tarim Basin in the Xinjiang Uyghur Autonomous Region, western China, have yielded both mummified and skeletal human remains. A dearth of local antecedents, coupled with woolen textiles and the apparent Western physical appearance of the population, raised questions as to where these people came from. Two hypotheses have been offered by archaeologists to account for the origins of Bronze Age populations of the Tarim Basin. These are the "steppe hypothesis" and the "Bactrian oasis hypothesis." Eight craniometric variables from 25 Aeneolithic and Bronze Age samples, comprising 1,353 adults from the Tarim Basin, the Russo-Kazakh steppe, southern China, Central Asia, Iran, and the Indus Valley, are compared to test which, if either, of these hypotheses are supported by the pattern of phenetic affinities possessed by Bronze Age inhabitants of the Tarim Basin. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (the weighted pair average linkage method and the neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis provide little support for either the steppe hypothesis or the Bactrian oasis hypothesis. Rather, the pattern of phenetic affinities manifested by Bronze Age inhabitants of the Tarim Basin suggests the presence of a population of unknown origin within the Tarim Basin during the early Bronze Age. After 1200 B.C., this population experienced significant gene flow from highland populations of the Pamirs and Ferghana Valley. These highland populations may include those who later became known as the Saka and who may have served as "middlemen" facilitating contacts between East (Tarim Basin, China) and West (Bactria, Uzbekistan) along what later became known as the Great Silk Road. Am J Phys Anthropol, 2003. © 2003 Wiley-Liss, Inc. [source] Life on the edge , to which degree does phreatic water sustain vegetation in the periphery of the Taklamakan Desert?APPLIED VEGETATION SCIENCE, Issue 1 2010Helge Bruelheide Abstract Questions: Do the vegetation-specific patterns in the forelands of river oases of the Taklamakan Desert provide clues to the degree to which a vegetation type depends on unsaturated soil moisture, brought about by extensive floodings, or phreatic water? Location: Foreland of the Qira oasis on the southern rim of the Taklamakan Desert, Xinjiang Uygur Autonomous Region, China. Methods: A vegetation map was prepared using a SPOT satellite image and ground truthing. Measurements of soil water contents were obtained from a flooding experiment and transformed into water potentials. Sum excedance values were calculated as the percentage of days on which different thresholds of soil water potentials were transgressed. Groundwater depth was mapped by drilling 30 groundwater holes and extrapolating the distances to the whole study area. Results: The vegetation was characterized by only six dominant or codominant species: Alhagi sparsifolia, Karelinia caspia, Populus euphratica, Tamarix ramosissima, Calligonum caput-medusae and Phragmites australis. The vegetation patterns encountered lacked any linear features typical of phreatophytes, thus not allowing direct conclusions on the type of the sustaining water sources. Soil water potentials never transgressed a threshold of pF 5 (,10 MPa) in horizons above the capillary fringe during periods without inundation, thus representing water not accessible for plants. Depth to the groundwater ranged between 2.3 and 17.5 m among plots and varied between 1.7 and 8.0 m within a plot owing to dune relief. The seven main vegetation types showed distinct niches of groundwater depths, corresponding to the observed concentric arrangement of vegetation types around the oasis. Conclusions: Inundation by flooding and unsaturated soil moisture are irrelevant for the foreland vegetation water supply. Although distances to the groundwater table can reach about 20 m, which is exceptionally large for phreatophytes, groundwater is the only water source for all vegetation types in the oasis foreland. In consequence, successful maintenance of oasis foreland vegetation will crucially depend on providing non-declining ground water tables. [source] Genetic structure of Anogeissus dhofarica (Combretaceae) populations endemic to the monsoonal fog oases of the southern Arabian PeninsulaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009CHRISTOPH OBERPRIELER Anogeissus dhofarica (Combretaceae) is an endemic tree of the monsoon affected coastal mountains of the southern Arabian Peninsula, being the character species of the Hybantho durae,Anogeissetum dhofaricae association, a drought deciduous, monsoon forest community found only in the Dhofar region of southern Oman and the eastern Al-Mahra region of south-east Yemen. Due to the steep precipitation gradient from the centre to the edges in this monsoon affected area, A. dhofarica is found in two different habitat types: in continuous woodland belts of the Hawf and Dhofar mountains, and in isolated, scattered woodland patches, as found especially in the Fartak Mts (south-east Yemen). Fifteen populations (212 individuals) from across the whole distribution area of the species were analysed using amplified fragment length polymorphism fingerprinting to: (1) evaluate the consequences of population fragmentation on the genetic diversity harboured in isolated patches versus cohering stands of the species and (2) to reconstruct the phylogeographical pattern of A. dhofarica as a consequence of oscillations in the monsoon activity during the Pleistocene and Holocene. The analysis of among-population genetic differentiation and within-population genetic diversity in A. dhofarica populations resulted in a lack of genetic pauperization and genetic differentiation of populations of the distinctly isolated patches of the Fartak Mts compared to the more luxurious forests of the Hawf and Dhofar regions. This is considered to be due to the high buffer capacity against the loss of genetic diversity caused by the long-lived life-form of the species combined with the capability to propagate clonally and the relatively recent fragmentation of Anogeissus forests into the described patches rather than due to high values of gene flow among remnant populations caused by bee pollination and anemochorical and hydrochorical diaspore dispersal. The phylogeographical pattern of the species argues for a quite recent fragmentation of a once continuous forest belt of A. dhofarica that is rather connected with climate changes in the Holocene than triggered by aridity,humidity oscillations reported for the Pleistocene. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 40,51. [source] Frege and Object Dependent PropositionsDIALECTICA, Issue 4 2002Heimir Geirsson Gareth Evans and John McDowell have challenged the traditional reading of Frege according to which Frege accepted propositions that are not object dependent, i.e., propositions that can exist even though the proper names that occur in the sentences that express them do not refer. A consequence of the Evans-McDowell interpretation of Frege is that if someone hallucinates that there is an oasis in front of her, then there is no thought of an oasis but only an illusion of a thought. No reference entails no sense, and no sense entails no thought. This paper will focus on Frege's views on the issue and, in particular, whether there is any evidence that the mature Frege, i.e., after he introduced the sense/reference distinction, did not accept propositions that are not object dependent. It will also address one of the consequences of the Evans-McDowell reading of Frege, arguing that they have ignored one of his important insights into natural languages. [source] Water uptake and nutrient concentrations under a floodplain oak savanna during a non-flood period, lower Cedar River, Iowa,HYDROLOGICAL PROCESSES, Issue 21 2009Keith E. Schilling Abstract Floodplains during non-flood periods are less well documented than when flooding occurs, but non-flood periods offer opportunities to investigate vegetation controls on water and nutrient cycling. In this study, we characterized water uptake and nutrient concentration patterns from 2005 to 2007 under an oak savanna located on the floodplain of the Cedar River in Muscatine County, Iowa. The water table ranged from 0·5 to 2·5 m below ground surface and fluctuated in response to stream stage, plant water demand and rainfall inputs. Applying the White method to diurnal water table fluctuations, daily ET from groundwater averaged more than 3·5 mm/day in June and July and approximately 2 mm/day in May and August. Total annual ET averaged 404 mm for a growing season from mid-May to mid-October. Savanna groundwater concentrations of nitrate-N, ammonium-N, and phosphate-P were very low (mean <0·18, <0·14, <0·08 mg/l, respectively), whereas DOC concentrations were high (7·1 mg/l). Low concentrations of N and P were in contrast to high nutrient concentrations in the nearby Cedar River, where N and P averaged 7·5 mg/l and 0·13, respectively. In regions dominated by intensive agriculture, study results document valuable ecosystem services for native floodplain ecosystems in reducing watershed-scale nutrient losses and providing an oasis for biological complexity. Improved understanding of the environmental conditions of regionally significant habitats, including major controls on water table elevations and water quality, offers promise for better management aimed at preserving the ecology of these important habitats. Copyright © 2009 John Wiley & Sons, Ltd. [source] Darfurian Livelihoods and Libya: Trade, Migration, and Remittance Flows in Times of Conflict and Crisis1INTERNATIONAL MIGRATION REVIEW, Issue 4 2007Helen Young Labor migration and commerce between Sudan and Libya have long been features of livelihoods in Darfur. This paper describes the importance of historical trade and migration links between Darfur and Libya, and provides a background to the political and economic situation in Libya which has influenced opportunities for Sudanese migrant workers. A case study of the situation of the Darfurian migrants in Kufra (an oasis and transnational trade hub in southern Libya) illustrates how the recent Darfur conflict has affected migration patterns from Darfur and remittance flows in the opposite direction. Official estimates of Darfurian migrant workers in Libya were unavailable but were estimated to be between 150,000 and 250,000. The closure of the national border between Sudan and Libya in May 2003, largely a result of insecurity in Darfur, stopped the traffic of migrant workers between northern Darfur and southern Libya (which prevented the onward travel to Sudan of several thousand migrants in Kufra), and curtailed the well-established trade routes, communications, and remittance flows. The current limited economic prospects for migrant workers in Libya, combined with the threat of detention, difficulties of return to Sudan, and loss of contact with and uncertainty about the fate of their families in Darfur, have created a sense of despair among many Darfurians. The paper concludes with a series of recommendations to improve the conditions of the Darfurian migrants in Libya, including an amnesty for illegal migrants, and also to ease the travel of migrants, promote communications between Libya and Darfur, and support the flow of remittances. [source] Salinity patterns in irrigation systems, a threat to be demystified, a constraint to be managed: Field evidence from Algeria and Tunisia,IRRIGATION AND DRAINAGE, Issue S3 2009S. Bouarfa irrigation; gestion de la salinité; alcalinité résiduelle; perception des agriculteurs et stratégies; Maghreb Abstract Salinity problems induced by irrigation are often presented in the literature as a threat that can only be managed at the irrigation scheme scale by installing subsurface drainage. On the other hand, salinity is a constraint that has often been successfully managed locally by farmers adapting their practices. However, the continuing expansion of irrigation with related water scarcity problems plus the increasing use of groundwater of marginal quality has resulted in a new challenge that is difficult to handle at the farm level only. To assess the dynamics of soil salinity and water quality together with farmers' salinity management practices, we adapted a common approach to analyze two contrasted salinity patterns: a traditional salinity pattern in an oasis (Fatnassa, Tunisia), and a recent sodicity pattern in a large irrigation scheme (Lower Chelif, Algeria). This approach which combines surveys on farmers' perceptions and practices and salinity measurements and geochemical analysis paves the way for more integrated management of salinity problems related to water scarcity. Copyright © 2009 John Wiley & Sons, Ltd. Les problèmes de salinité en systèmes irrigués sont souvent présentés dans la littérature comme une menace dont la seule solution réside dans l'installation de systèmes de drainage. La salinité est cependant une contrainte qui peut également être gérée localement avec succès par les agriculteurs par une adaptation de leurs pratiques. Le développement continu de l'irrigation et les tensions sur l'eau qui en découlent contraignent à un usage accru d'eau de nappe de mauvaise qualité dont les conséquences sont difficilement maitrisables à la seule échelle de l'exploitation. Ce nouveau contexte nécessite le développement de nouvelles approches permettant d'appréhender à la fois les processus de salinisation et d'adaptation des agriculteurs. Nous avons adopté une démarche commune pour évaluer la dynamique d'évolution de la salinité et les pratiques des agriculteurs dans deux situations contrastées: un schéma de salinisation classique (oasis de Fatnassa, Tunisie) et un schéma récent d'évolution vers un processus de sodisation (plaine du Bas-Chelif, Algérie). L'utilisation de cette approche qui combine des enquêtes sur les perceptions et les pratiques des agriculteurs, des mesures de salinité et des analyzes géochimiques ouvre des perspectives pour une vision et une gestion plus intégrée des problèmes de salinité liés à la pénurie d'eau. Copyright © 2009 John Wiley & Sons, Ltd. [source] Vegetation Change and Soil Nutrient Distribution along an Oasis-Desert Transitional Zone in Northwestern ChinaJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2007Bao-Ming Chen Abstract Many studies have focused on soil nutrient heterogeneity and islands of fertility in arid ecosystems. However, few have been conducted on an oasis-desert transitional zone where there is a vegetation pattern changing from shrubs to annual herbs. The goal of the present study was to understand vegetation and soil nutrient heterogenity along an oasis-desert transitional zone in northwestern China. Three replicated sampling belts were selected at 200 m intervals along the transitional zone. Twenty-one quadrats (10 × 10 m) at 50 m intervals were located along each sampling belt. The vegetation cover was estimated through the quadrats, where both the soil under the canopy and the open soil were sampled simultaneously. The dominated shrub was Haloxylon ammodendron in the areas close to the oasis and Nitraria tangutorum dominated the areas close to the desert. In general, along the transitional zone the vegetation cover decreased within 660 m, increased above 660 m and decreased again above 1 020 m (close to the desert). The soil nutrients (organic matter, total N, NO3, and NH4+) showed significant differences along the zone. The soil nutrients except the soil NH4+ under the canopy were higher than those in open soil, confirming "islands of fertility" or nutrient enrichment. Only a slight downward trend of the level of "islands of fertility" for soil organic matter appeared in the area within 900 m. Soil organic matter both under canopy and in interspace showed a positive correlation with the total vegetation cover, however, there was no significant correlation between the other soil nutrients and the total vegetation cover. We also analyzed the relationship between the shrubs and annuals and the soil nutrients along the zone. Similarly, there was no significant correlation between them, except soil organic matter with the annuals. The results implied that annual plants played an important role in soil nutrient enrichment in arid ecosystem. [source] Estimating Evapotranspiration and Seepage for a Sinkhole Wetland From Diurnal Surface-Water Cycles,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2007A. Jason Hill Abstract:, This study used measured diurnal surface-water cycles to estimate daily evapotranspiration (ET) and seepage for a seasonally flooded sinkhole wetland. Diurnal surface-water cycles were classified into five categories based on the relationship between the surface-water body and the surrounding ground-water system (i.e., recharge/discharge). Only one class of diurnal cycles was found to be suitable for application of this method. This subset of diurnal cycles was used to estimate ET and seepage and the relative importance of each transfer process to the overall water budget. The method has limited utility for wetlands with erratic hydrologic regimes (e.g., wetlands in urban environments). This is due to violation of the critical assumption that the inflow/outflow rate remains constant throughout the day. For application to surface-water systems, the method is typically applied with an assumed specific yield of 1.0. This assumption was found to be invalid for application to surface-water systems with a noncylindrical pond geometry. An overestimation of ET by as much as 60% was found to occur under conditions of low pond stage and high water loss. The results demonstrate the high ET rates that can occur in isolated wetlands due to contrasting roughness and moisture conditions (oasis and clothesline effects). Estimated ET rates ranged from 4.1 to 18.7 mm/day during the growing season. Despite these large ET rates, seepage (recharge) was found to be the dominant water loss mechanism for the wetland. [source] Geological overview and cratering model for the Haughton impact structure, Devon Island, Canadian High ArcticMETEORITICS & PLANETARY SCIENCE, Issue 12 2005Gordon R. Osinski Regional geological mapping has refined the sedimentary target stratigraphy and constrained the thickness of the sedimentary sequence at the time of impact to ,1880 m. New 40Ar,39Ar dates place the impact event at ,39 Ma, in the late Eocene. Haughton has an apparent crater diameter of ,23 km, with an estimated rim (final crater) diameter of ,16 km. The structure lacks a central topographic peak or peak ring, which is unusual for craters of this size. Geological mapping and sampling reveals that a series of different impactites are present at Haughton. The volumetrically dominant crater-fill impact melt breccias contain a calcite-anhydrite-silicate glass groundmass, all of which have been shown to represent impact-generated melt phases. These impactites are, therefore, stratigraphically and genetically equivalent to coherent impact melt rocks present in craters developed in crystalline targets. The crater-fill impactites provided a heat source that drove a post-impact hydrothermal system. During this time, Haughton would have represented a transient, warm, wet microbial oasis. A subsequent episode of erosion, during which time substantial amounts of impactites were removed, was followed by the deposition of intra-crater lacustrine sediments of the Haughton Formation during the Miocene. Present-day intra-crater lakes and ponds preserve a detailed paleoenvironmental record dating back to the last glaciation in the High Arctic. Modern modification of the landscape is dominated by seasonal regional glacial and niveal melting, and local periglacial processes. The impact processing of target materials improved the opportunities for colonization and has provided several present-day habitats suitable for microbial life that otherwise do not exist in the surrounding terrain. [source] Near Eastern Neolithic genetic input in a small oasis of the Egyptian Western DesertAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Martina Kujanová Abstract The Egyptian Western Desert lies on an important geographic intersection between Africa and Asia. Genetic diversity of this region has been shaped, in part, by climatic changes in the Late Pleistocene and Holocene epochs marked by oscillating humid and arid periods. We present here a whole genome analysis of mitochondrial DNA (mtDNA) and high-resolution molecular analysis of nonrecombining Y-chromosomal (NRY) gene pools of a demographically small but autochthonous population from the Egyptian Western Desert oasis el-Hayez. Notwithstanding signs of expected genetic drift, we still found clear genetic evidence of a strong Near Eastern input that can be dated into the Neolithic. This is revealed by high frequencies and high internal variability of several mtDNA lineages from haplogroup T. The whole genome sequencing strategy and molecular dating allowed us to detect the accumulation of local mtDNA diversity to 5,138 ± 3,633 YBP. Similarly, theY-chromosome gene pool reveals high frequencies of the Near Eastern J1 and the North African E1b1b1b lineages, both generally known to have expanded within North Africa during the Neolithic. These results provide another piece of evidence of the relatively young population history of North Africa. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] The Complex and Diversified Mitochondrial Gene Pool of Berber PopulationsANNALS OF HUMAN GENETICS, Issue 2 2009C. Coudray Summary The mitochondrial DNA variation of 295 Berber-speakers from Morocco (Asni, Bouhria and Figuig) and the Egyptian oasis of Siwa was evaluated by sequencing a portion of the control region (including HVS-I and part of HVS-II) and surveying haplogroup-specific coding region markers. Our findings show that the Berber mitochondrial pool is characterized by an overall high frequency of Western Eurasian haplogroups, a somehow lower frequency of sub-Saharan L lineages, and a significant (but differential) presence of North African haplogroups U6 and M1, thus occupying an intermediate position between European and sub-Saharan populations in PCA analysis. A clear and significant genetic differentiation between the Berbers from Maghreb and Egyptian Berbers was also observed. The first are related to European populations as shown by haplogroup H1 and V frequencies, whereas the latter share more affinities with East African and Nile Valley populations as indicated by the high frequency of M1 and the presence of L0a1, L3i, L4*, and L4b2 lineages. Moreover, haplogroup U6 was not observed in Siwa. We conclude that the origins and maternal diversity of Berber populations are old and complex, and these communities bear genetic characteristics resulting from various events of gene flow with surrounding and migrating populations. [source] Life on the edge , to which degree does phreatic water sustain vegetation in the periphery of the Taklamakan Desert?APPLIED VEGETATION SCIENCE, Issue 1 2010Helge Bruelheide Abstract Questions: Do the vegetation-specific patterns in the forelands of river oases of the Taklamakan Desert provide clues to the degree to which a vegetation type depends on unsaturated soil moisture, brought about by extensive floodings, or phreatic water? Location: Foreland of the Qira oasis on the southern rim of the Taklamakan Desert, Xinjiang Uygur Autonomous Region, China. Methods: A vegetation map was prepared using a SPOT satellite image and ground truthing. Measurements of soil water contents were obtained from a flooding experiment and transformed into water potentials. Sum excedance values were calculated as the percentage of days on which different thresholds of soil water potentials were transgressed. Groundwater depth was mapped by drilling 30 groundwater holes and extrapolating the distances to the whole study area. Results: The vegetation was characterized by only six dominant or codominant species: Alhagi sparsifolia, Karelinia caspia, Populus euphratica, Tamarix ramosissima, Calligonum caput-medusae and Phragmites australis. The vegetation patterns encountered lacked any linear features typical of phreatophytes, thus not allowing direct conclusions on the type of the sustaining water sources. Soil water potentials never transgressed a threshold of pF 5 (,10 MPa) in horizons above the capillary fringe during periods without inundation, thus representing water not accessible for plants. Depth to the groundwater ranged between 2.3 and 17.5 m among plots and varied between 1.7 and 8.0 m within a plot owing to dune relief. The seven main vegetation types showed distinct niches of groundwater depths, corresponding to the observed concentric arrangement of vegetation types around the oasis. Conclusions: Inundation by flooding and unsaturated soil moisture are irrelevant for the foreland vegetation water supply. Although distances to the groundwater table can reach about 20 m, which is exceptionally large for phreatophytes, groundwater is the only water source for all vegetation types in the oasis foreland. In consequence, successful maintenance of oasis foreland vegetation will crucially depend on providing non-declining ground water tables. [source] | |||||||||||||||||||||||||