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The archaeological site of Saruq al-Hadid, Dubai, United Arab Emirates, presents a long sequence of persistent temporary human occupation on the northern edge of the Rub’ al-Khali desert. The site is located in active dune fields, and evidence for human activity is stratified within a deep sequence of natural dune deposits that reflect complex taphonomic processes of deposition, erosion and reworking. This study presents the results of a program of radiocarbon (14C) and thermoluminescence dating on deposits from Saruq al-Hadid, allied with studies of material remains, which are amalgamated with the results of earlier absolute dating studies provide a robust chronology for the use of the site from the Bronze Age to the Islamic period. The results of the dating program allow the various expressions of human activity at the site—ranging from subsistence activities such as hunting and herding, to multi-community ritual activities and large scale metallurgical extraction—to be better situated chronologically, and thus in relation to current debates regarding the development of late prehistoric and early historic societies in southeastern Arabia.
Agricultural practices are likely to lower nitrogen (N) fertilization inputs for economic and ecological limitation reasons. The objective of the current study was to assess genotypic variation in nitrogen use efficiency (NUE) and related parameters of spring wheat (Triticum aestivum L.) as well as the relative grain yield performance under sandy soil conditions. A sub-set of 16 spring wheat genotypes was studied over 2 years at five N levels (0, 70, 140, 210 and 280 kg N/ha). Results indicated significant differences among genotypes and N levels for grain yield and yield components as well as NUE. Genotypes with high NUE exhibited higher plant biomass, grain and straw N concentration and grain yield than those with medium and low NUE. Utilization efficiency (grain-NUtE) was more important than uptake efficiency (total NUpE) in association with grain yield. Nitrogen supply was found to have a substantial effect on genotype; Line 6052 as well as Shandawel 1, Gemmiza 10, Gemmiza 12, Line 6078 and Line 6083 showed higher net assimilation rate, more productive tillers, increased number of spikes per unit area and grains per spike, extensive N concentration in grain and straw, heavier grains, higher biological yield and consequently maximized grain yield. The relative importance of NUE-associated parameters such as nitrogen agronomic efficiency, nitrogen physiological efficiency and apparent nitrogen recovery as potential targets in breeding programmes for increased NUE genotypes is also mentioned.
The role of tachoclines, the thin shear layers that separate solid body from differential rotation in the interior of late-type stars, in stellar dynamos is still controversial. In this work we discuss their relevance in view of recent results from global dynamo simulations performed with the EULAG-MHD code. The models have solar-like stratification and different rotation rates (i.e., different Rossby number). Three arguments supporting the key role of tachoclines are presented: the solar dynamo cycle period, the origin of torsional oscillations and the scaling law of stellar magnetic fields as function of the Rossby number. This scaling shows a regime where the field strength increases with the rotation and a saturated regime for fast rotating stars. These properties are better reproduced by models that consider the convection zone and a fraction of the radiative core, naturally developing a tachocline, than by those that consider only the convection zone.
Loop-mediated isothermal amplification (LAMP) is a simple, powerful state-of-the-art gene amplification technique used for the rapid diagnosis and early detection of microbial diseases. Many LAMP assays have been developed and validated for important epizootic diseases of livestock. We review the LAMP assays that have been developed for the detection of 18 viruses deemed notifiable of ruminants, swine and poultry by the World Organization for Animal Health (OIE). LAMP provides a fast (the assay often takes less than an hour), low cost, highly sensitive, highly specific and less laborious alternative to detect infectious disease agents. The LAMP procedure can be completed under isothermal conditions so thermocyclers are not needed. The ease of use of the LAMP assay allows adaptability to field conditions and works well in developing countries with resource-limited laboratories. However, this technology is still underutilized in the field of veterinary diagnostics despite its huge capabilities.
By conducting a case-control study in two university hospitals, we explored the association between modifiable risk behaviours and diarrhoea. Children aged <5 years attending outpatient clinics for diarrhoea were matched by age and sex with controls. Data were collected on family demographics, socioeconomic indicators, and risk behaviour practices. Two rectal swabs and a stool specimen were collected from cases and controls. Samples were cultured for bacterial pathogens using standard techniques and tested by ELISA to detect rotavirus and Cryptosporidium spp. Four hundred cases and controls were enrolled between 2007 and 2009. The strongest independent risk factors for diarrhoea were: presence of another household member with diarrhoea [matched odds ratio (mOR) 4·9, 95% CI 2·8–8·4] in the week preceding the survey, introduction to a new kind of food (mOR 3, 95% CI 1·7–5·4), and the child being cared for outside home (mOR 2·6, 95% CI 1·3–5·2). While these risk factors are not identifiable, in some age groups more easily modifiable risk factors were identified including: having no soap for handwashing (mOR 6·3, 95% CI 1·2–33·9) for children aged 7–12 months, and pacifier use (mOR 1·9, 95% CI 1·0–3·5) in children aged 0–6 months. In total, the findings of this study suggest that community-based interventions to improve practices related to sanitation and hygiene, handwashing and food could be utilized to reduce the burden of diarrhoea in Egyptian children aged <5 years.
Strain characteristics of 51 Shigella sonnei isolates obtained from children seeking medical care (MC) and 48 isolates recovered during a prospective diarrhoea birth cohort (BC) study were compared. Biochemical characterization and antibiotic susceptibility testing determined that all S. sonnei isolates were biotype g and multidrug-resistant. Plasmid profiling identified 15 closely related patterns and XbaI pulsed-field gel electrophoresis confirmed the high degree of genetic similarity between isolates. All S. sonnei isolates harboured ipaH and class II integrase genes and 84·3 and 80% of the MC and BC isolates, respectively carried the sen gene. Neither the class I integrase nor the set gene was detected. Our results indicate that S. sonnei isolates associated with severe diarrhoea were indistinguishable from those associated with mild diarrhoea. Additional genetic tests with greater discrimination might offer an opportunity to determine genetic differences within the globally disseminating biotype g clone.
The risk of developing cardiovascular diseases is known to begin before birth and the impact of the intrauterine environment on subsequent adult health is currently being investigated from many quarters. Following our studies demonstrating the impact of hypoxia in utero and consequent intrauterine growth restriction (IUGR) on the rat cardiovascular system, we hypothesized that changes extend throughout the vasculature and alter function of the renal artery. In addition, we hypothesized that hypoxia induces renal senescence as a potential mediator of altered vascular function. We demonstrated that IUGR females had decreased responses to the adrenergic agonist phenylephrine (PE; pEC50 6.50 ± 0.05 control v. 6.17 ± 0.09 IUGR, P < 0.05) and the endothelium-dependent vasodilator methylcholine (MCh; Emax 89.8 ± 7.0% control v. 41.0 ± 6.5% IUGR, P < 0.001). In IUGR females, this was characterised by increased basal nitric oxide (NO) modulation of vasoconstriction (PE pEC50 6.17 ± 0.09 IUGR v. 6.42 ± 0.08 in the presence of the NO synthase inhibitor N-nitro-l-arginine methyl ester hydrochloride (l-NAME; P < 0.01) but decreased activated NO modulation (no change in MCh responses in the presence of l-NAME), respectively. In contrast, IUGR males had no changes in PE or MCh responses but demonstrated increased basal NO (PE pEC50 6.29 ± 0.06 IUGR v. 6.42 ± 0.12 plus l-NAME, P < 0.01) and activated NO (Emax 37.8 ± 9.4% control v. −0.8 ± 13.0% plus l-NAME, P < 0.05) modulation. No significant changes were found in gross kidney morphology, proteinuria or markers of cellular senescence in either sex. In summary, renal vascular function was altered by hypoxia in utero in a sex-dependent manner but was unlikely to be mediated by premature renal senescence.
We establish a q-Titchmarsh-Weyl theory for singular q-Sturm-Liouville problems. We define q-limit-point and q-limit circle singularities, and we give sufficient conditions which guarantee that the singular point is in a limit-point case. The resolvent is constructed in terms of Green’s function of the problem. We derive the eigenfunction expansion in its series form. A detailed worked example involving Jackson q-Bessel functions is given. This example leads to the completeness of a wide class of q-cylindrical functions.
Diversity within Shigella dysenteriae (n=40) and Shigella boydii (n=30) isolates from children living in Egypt aged <5 years was investigated. Shigella-associated diarrhoea occurred mainly in summer months and in children aged <3 years, it commonly presented with vomiting and fever. Serotypes 7 (30%), 2 (28%), and 3 (23%) accounted for most of S. dysenteriae isolates; 50% of S. boydii isolates were serotype 2. S. dysenteriae and S. boydii isolates were often resistant to ampicillin, chloramphenicol and tetracycline (42%, 17%, respectively), although resistance varied among serotypes. Pulsed-field gel electrophoresis separated the isolates into distinct clusters correlating with species and serotype. Genetic differences in trimethoprim/sulfamethoxazole and β-lactam-encoding resistance genes were also evident. S. dysenteriae and S. boydii are genetically diverse pathogens in Egypt; the high level of multidrug resistance associated with both pathogens and resistance to the most available inexpensive antibiotics underlines the importance of continuing surveillance.
The fluid film thickness and drag during chemical-mechanical polishing are largely dependent on the shape of the wafer polished. In this study we use dual emission laser induced fluorescence to measure the film thickness and a strain gage, mounted on the polishing table, to measure the friction force between the wafer and the pad. All measurements are taken during real polishing processes. The trends indicate that with a convex wafer in contact with the polishing pad, the slurry layer increases with increasing platen speed and decreases with increasing downforce. The drag force decreases with increasing platen speed and increases with increasing downforce. These similarities are observed for both in-situ and ex-situ conditioning. However, these trends are significantly different for the case of a concave wafer in contact with the polishing pad. During ex-situ conditioning the trends are similar as with a convex wafer. However, in-situ conditioning decreases the slurry film layer with increasing platen speed, and increases it with increasing downforce in the case of the concave wafer. The drag force increases with increasing platen speed as well as increasing downforce. Since we are continually polishing, the wafer shape does change over the course of each experiment causing a larger error in repeatability than the measurement error itself. Different wafers are used throughout the experiment and the results are consistent with the variance of the wafer shape. Local pressure measurements on the rotating wafer help explain the variances in fluid film thickness and friction during polishing.
The effects of radiation damage on bulk laser-induced breakdown in Si02 were studied. Samples studied included Spectrasil A, B, and WF (water free). Measurements of laser-induced breakdown were conducted with 532 and 1064 nm laser pulses of approximately 30 nsec duration. Reductions of up to 50% in the laser-ind ced breakdown threshold were observed at 530 nm for samples exposed to 108 rads of γ-radiation.
A contamination control study of a Silicon Valley Group Thermco Systems Vertical Thermal Reactor(VTR) is presented. Trace elements of contaminants such as water vapor and oxygen have been shown to significantly affect the integrity of the silicon nitride film deposited by the low pressure chemical vapor deposition (LPCVD) process. This study documented the effects of process parameters on gaseous contamination levels, i.e., O2 and H2O vapor. Starting with a baseline process, the effects of an excursion of pre-deposition temperature ramp-up and stabilization condition, wafer load/unload and various post deposition conditions were explored. An axial profile of moisture and oxygen levels along the wafer load was obtained using Linde's Low Pressure Reactor Analysis(LPRAS) methodology. In addition, other process parameters such as gas flow rates during load and unload of wafers, pre-deposition N2 purge and process tube exposure time to ambient environment were- investigated. The wafers were analyzed for contaminants on the wafer surface or in the deposited silicon nitride film using FTIR and Auger spectroscopy techniques. They showed low levels of Si-O and no measurable Si-H or N-H bonds.
Thin films of Ceria, Titania and Ziroonia have been prepared using Ion Assisted Deposition(IAD). The energy of ions was varied between 0 and 1 keV and current densities up to 220 μA/cm were used. It was found that the stress behaviour is dependent on ion species, i.e. Argon or Oxygen, ion energy and current density and substrate temperature apart from the material. While oeria files showed tensile stresses under the influence of argon ion bombardment at ambient temperature, they showed a sharp transition from tensile to compressive stress with increase in substrate temperature. When bombarded with oxygen ions they showed a transition from tensile to compressive stress with increase in energy. The titania films deposited with oxygen ions, on the other hand showed purely tensile stresses. Zirconia films deposited with oxygen ions, however, showed a transition from tensile to compressive stress.
Recent progress on the use of molecular engineering approaches for the enhancement and spectral tuning of the optical limiting responses of phthalocyanine complexes is presented. Examples are given involving the use of the heavy-atom approach to enhance the limiting response of naphthalocyanines and of donor substitution of naphthalocyanines to red shift the optical limiting response, as demonstrated for indium and tin octabutoxynaphthalocyanines. These approaches have led to new materials for optical limiting with potential for high performance. An experimental demonstration of the “bottleneck” limiter concept, in which the optical-limiting material is distributed nonhomogeneously to permit strong pumping of excited-state population throughout the interaction region, is presented and shows an order-of-magnitude increase in pulse suppression compared to a homogeneous distribution, without an increase in linear absorbance.
Thin film PbZr0.55Ti0.45O3 (PZT) capacitors were observed to develop a dc voltage offset when driven with an ac applied electric field. This voltage offset displayed a strong dependence on the ambient oxygen partial pressure, PO2, of the atmosphere above the film, in addition to applied electric field and temperature dependencies. A scenario is proposed wherein a chemical potential gradient is established in the film, the magnitude of which is determined by the ambient PO2. The subsequent redistribution of oxygen vacancies is thought to create the observed voltage offset. This hypothesis was supported by the observation of similar voltage offsets in compositionally graded PZT films. This effect shows promise for novel low-temperature oxygen sensing applications.