89,398 research outputs found
The Negev Desert: a viable Israeli resettlement option?
On Feb. 9, 2004, Israeli Infrastructure Minister Yosef Paritzsky suggested that the 7,500 Israeli settlers who are to be removed from the Gaza Strip under Prime Minister Sharon’s disengagement plan could be housed in the 13,000 empty apartments available in the Negev Desert. The Negev “Desert Cities” plan isn’t a perfect option, but it will allow the settlers to move into high-quality housing rapidly. While at least some settlers will almost certainly have to live in existing apartment housing during the construction of the Negev settlements, this plan offers the best chance of ensuring that the apartment housing will be only a temporary solution
Fungal microbiota from rain water and pathogenicity of Fusarium species isolated from atmospheric dust and rainfall dust
In order to determine the presence of Fusarium spp. in atmospheric dust and rainfall dust, samples were collected during September 2007, and July, August, and October 2008. The results reveal the prevalence of airborne Fusarium species coming from the atmosphere of the South East coast of Spain. Five different Fusarium species were isolated from the settling dust: Fusarium oxysporum, F. solani, F. equiseti, F. dimerum, and F. proliferatum. Moreover, rainwater samples were obtained during significant rainfall events in January and February 2009. Using the dilution-plate method, 12 fungal genera were identified from these rainwater samples. Specific analyses of the rainwater revealed the presence of three species of Fusarium: F. oxysporum, F. proliferatum and F. equiseti. A total of 57 isolates of Fusarium spp. obtained from both rainwater and atmospheric rainfall dust sampling were inoculated onto melon (Cucumis melo L.) cv. Piñonet and tomato (Lycopersicon esculentum Mill.) cv. San Pedro. These species were chosen because they are the main herbaceous crops in Almeria province. The results presented in this work indicate strongly that spores or propagules of Fusarium are able to cross the continental barrier carried by winds from the Sahara (Africa) to crop or coastal lands in Europe. Results show differences in the pathogenicity of the isolates tested. Both hosts showed root rot when inoculated with different species of Fusarium, although fresh weight measurements did not bring any information about the pathogenicity. The findings presented above are strong indications that long-distance transmission of Fusarium propagules may occur. Diseases caused by species of Fusarium are common in these areas. They were in the past, and are still today, a problem for greenhouses crops in AlmerĂa, and many species have been listed as pathogens on agricultural crops in this region. Saharan air masses dominate the Mediterranean regions. The evidence of long distance dispersal of Fusarium spp. by atmospheric dust and rainwater together with their proved pathogenicity must be taken into account in epidemiological studies
The Vertebrate Fauna of the Upper Triassic (Revueltian: early-mid Norian) Painted Desert Member (Petrified Forest Formation: Chinle Group) in the Chama Basin, Northern New Mexico
The Upper Triassic Painted Desert Member of the Petrified Forest Formation in north-central New Mexico yields one of the most extensive and significant Revueltian (early-mid Norian) tetrapod faunas known. Particularly significant aspects of this fauna are: (1) its long history of collection and study, including designation of important type specimens; and (2) the richness
of the unit, including no fewer than three major vertebrate quarries (the Canjilon, Snyder, and Hayden quarries). Beginning with the work of Cope and extending to the present day, the bulk of the Triassic vertebrates recovered from the Chama Basin have been derived from the Painted Desert Member. This includes tetrapod faunas collected at Gallina, Orphan Mesa, and the Canjilon, Snyder, and Hayden quarries. Although any one of these localities can be exceptionally rich, the Painted Desert Member fauna in the Chama Basin is a relatively low-diversity assemblage dominated by the phytosaur Pseudopalatus and the
aetosaur Typothorax. The vast majority of the known diversity of the unit in the Chama Basin was derived from a single locality, the Snyder quarry. We also review the stratigraphic and biostratigraphic evidence that suggest that this fauna may be slightly younger (Lucianoan) than the type Revueltian (Barrancan) assemblage, although this argument is weakened by the fact that it is based at least in part on the absence of characteristic Revueltian (Barrancan) taxa such as Revueltosaurus callenderi
Secondary plant succession and vegetation recovery in two western Great Basin Desert ghost towns
Secondary succession and vegetation recovery patterns are examined in two abandoned mining camps in the western Great Basin Desert. Results from ANOVA and Tukey comparison tests indicate that, after approximately 70 years of recovery, significant differences remain in total cover, therophyte cover and species richness between disturbed sites and control plots. The outstanding difference is the dominance of the introduced annual Bromus tectorum in the disturbed areas. Because the presence of B. tectorum changes the fire, grazing and competition dynamics of the desert vegetation assemblages, complete recovery or convergence of the disturbed vegetation to that of the ambient control plots is considered improbable. The dominance of B. tectorum at the expense of the other, native, species is viewed as a permanent change
Stratigraphy and Paleontology of the Lower Chinle Group (Adamanian: latest Carnian) in the Vicinity of St. Johns, Arizona
Topographically low exposures of Upper Triassic Chinle Group strata near St. Johns, Arizona, overlie the Middle Triassic Moenkopi Formation and can be assigned to four formation-rank units. These are, in ascending order, the Zuni Mountains (= “mottled strata”), Shinarump, Bluewater Creek (= “Mesa Redondo”), and Petrifi ed Forest formations. Petrifi ed Forest Formation strata in the vicinity of St. Johns pertain to three members, the basal Blue Mesa, medial Sonsela, and upper Painted Desert members. There are two principal unconformities in this section, the Tr-3 unconformity at the base of the Chinle and the Tr-4 unconformity at the top of the Blue Mesa Member. The Sonsela Member of the Petrifi ed Forest Member disconformably overlies the Blue Mesa Member throughout this region. However, although the Sonsela consists of basal extrabasinal conglomerates overlain by coarse-grained sandstones, it does not always form a persistent bench or ledge, and often must be identifi ed by lithology alone, not merely by topographic expression. In the northern and easternmost Blue Hills northeast of St. Johns, the Painted Desert Member of the Petrifi ed Forest Formation crops out as badlands of reddish-brown, bentonitic mudstone
A study to explore the use of orbital remote sensing to determine native arid plant distribution
The author has identified the following significant results. It is possible to determine, from ERTS imagery, native arid plant distribution. Using techniques of multispectral masking and extensive fieldwork, three native vegetation communities were defined and mapped in the Avra Valley study area. A map was made of the Yuma area with the aid of ground truth correlations between areas of desert pavement visible on ERTS images and unique vegetation types. With the exception of the Yuma soil-vegetation correlation phenomena, only very gross differentiations of desert vegetation communities can be made from ERTS data. Vegetation communities with obvious vegetation density differences such as saguaro-paloverde, creosote bush, and riparian vegetation can be separated on the Avra Valley imagery while more similar communities such as creosote bush and saltbush could not be differentiated. It is suggested that large differences in vegetation density are needed before the signatures of two different vegetation types can be differentiated on ERTS imagery. This is due to the relatively insignificant contribution of vegetation to the total radiometric signature of a given desert scene. Where more detailed information concerning the vegetation of arid regions is required, large scale imagery is appropriate
Does CO trace H2 at high galactic latitude
A CO survey of 342 Infrared Excess Clouds (IRECs) distributed uniformly across the sky is presented. Following comparison of the integrated CO brightness with the 100 micron infrared brightness B(sub 4) obtained from the IRAS data, evidence was found for a threshold in B(sub 4) of 4-5 MJy sr(exp -1) below which CO does not form. Evidence is also presented that the threshold effect can be seen within an individual cloud, providing evidence for a phase transition between atomic and molecular gas. While the main thrust was to examine the CO content of the IRECs, it was also attempted to detect CO toward a number of UV stars so that CO brightness could be correlated with direct measurements of H2 column density and E(B-V). Of the 26 observed stars CO was detected toward 6. It is consistent with the results obtained using infrared data
Subjective Fatigue in A-6, F-14, and F/A-18 Aircrews During Operations Desert Shield and Storm
Fatigue occurring during naval air combat can reduce performance, impair operational effectiveness, and compromise safety. This study examines the effect of combat missions on the subjective fatigue of naval aircrews deployed aboard USS AMERICA during Desert Shield and Desert Storm. Fatigue was determined using three questionnaires that were completed before and after each mission. Although fatigue significantly increased during combat missions, it usually returned to preflight levels by the next day without noticeably increasing as the operation progressed. We feel that judicious aircrew scheduling on the part of operational planners was one of the most important factors contributing to this result. To minimize fatigue during naval air combat operations, we recommend that, as resources permit, \u27no-fly\u27 days be regularly scheduled, only one or two missions should be scheduled per day, and adequate crew rest should be planned between missions
- …