Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

The paper presents a new concept in antenna design, whereby a photo-imageable thick-film process is used to integrate a waveguide antenna within a multilayer structure. This has yielded a very compact, high performance antenna working at high millimeter-wave (mm-wave) frequencies, with a high degree of repeatability and reliability in antenna construction. Theoretical and experimental results for 70 GHz mm-wave integrated antennas, fabricated using the new technique are presented. The antennas were formed from miniature slotted waveguide arrays using up to 18 layers of photo-imageable material. To enhance the electrical performance a novel folded waveguide array was also investigated. The fabrication process is analysed in detail and the critical issues involved in the fabrication cycle are discussed. The losses in the substrate integrated waveguide have been calculated. The performance of the new integrated antenna is compared to conventional metallic, air-filled waveguide antennas, and also to conventional microstrip antenna arrays operating at the same frequencies

Efficacy of a low-dose ferric-EDTA in reducing iron deficiency anaemia among underfive children living in malaria-holoendemic district of Mvomero, Tanzania

Iron deficiency anaemia is a public health problem in Tanzania especially among children under the age of five years. In malaria holoendemic areas, control of anaemia by supplementation with iron has been reported to increase serious adverse events. The World Health Organization recommends that, programs to control anaemia in such areas should go concurrently with malaria control programmes. The objectives of the study were to: (i) to determine if a supplement providing 2.5 mg of iron as ferric EDTA and 2.5 mg of iron as ferrous lactate (low dose) is as effective in correcting anaemia as a supplement providing the standard 10 mg of iron as ferrous lactate (high dose); and ii) determine if iron supplementation increased the risk of malaria. This study was carried out in Mvomero District of east-central Tanzania. Two groups (69 and 70 subjects per treatment) of moderately anaemic children (7.0–9.1 g of Hb/dl), received one of the two micronutrient supplements differing only in iron content for a period of 60 days. Results showed that, the average haemoglobin (Hb) concentration improved from 8.30±0.60 g/dl to 11.08±1.25 g/dl. The average weight-for-age for all children increased from 16.0 to 20.6% while their weight-for-height increased from 4.0 to 13.3%. The incidence of asymptomatic and symptomatic malaria ranged from 10.0 to 10.4% at all time points with no apparent increase in malaria severity due to iron supplementation. Overall, there was a significant reduction in anaemia during the 60 day supplementation period. This study demonstrated that, micronutrient supplements containing low-dose ferric-EDTA is just as effective as the high dose iron in reducing anaemia and can be safely utilized in malaria holoendemic areas to control iron deficiency anaemia. It is recommended that, a large study should be conducted to affirm the effectiveness of the low-dose ferric-EDTA in controlling iron deficiency anaemia among underfive children

Inland wetlands mapping and vulnerability assessment using an integrated geographic information system and remote sensing techniques

The understanding of inland wetlands’ distribution and their level of vulnerability is important to enhance management and conservation efforts. The aim of the study was to map inland wetlands and assess their distribution pattern and vulnerability to natural and human disturbances such as climate change (temperature increase) and human activities by the year 2080. Inland wetland types i.e. forested/shrub, emergent and open water bodies were classified and mapped using maximum likelihood standard algorithm. The spatial distribution pattern of inland wetlands was examined using average nearest neighbor analysis. A weighted geospatial vulnerability analysis was developed using variables such as roads, land cover/ land use (developed and agricultural areas) and climate data (temperature) to predict potentially vulnerable inland wetland types. Inland wetlands were successfully classified and mapped with overall accuracy of about 73 percent. Clustered spatial distribution pattern was found among all inland wetland types with varied degree of clustering. The study found about 13 percent of open water bodies, 11 percent of forested/shrub and 7 percent of emergent wetlands potentially most vulnerable to human and natural stressors. This information could be used to improve wetland planning and management by wetland managers and other stakeholders

A mathematical framework for critical transitions: normal forms, variance and applications

Critical transitions occur in a wide variety of applications including mathematical biology, climate change, human physiology and economics. Therefore it is highly desirable to find early-warning signs. We show that it is possible to classify critical transitions by using bifurcation theory and normal forms in the singular limit. Based on this elementary classification, we analyze stochastic fluctuations and calculate scaling laws of the variance of stochastic sample paths near critical transitions for fast subsystem bifurcations up to codimension two. The theory is applied to several models: the Stommel-Cessi box model for the thermohaline circulation from geoscience, an epidemic-spreading model on an adaptive network, an activator-inhibitor switch from systems biology, a predator-prey system from ecology and to the Euler buckling problem from classical mechanics. For the Stommel-Cessi model we compare different detrending techniques to calculate early-warning signs. In the epidemics model we show that link densities could be better variables for prediction than population densities. The activator-inhibitor switch demonstrates effects in three time-scale systems and points out that excitable cells and molecular units have information for subthreshold prediction. In the predator-prey model explosive population growth near a codimension two bifurcation is investigated and we show that early-warnings from normal forms can be misleading in this context. In the biomechanical model we demonstrate that early-warning signs for buckling depend crucially on the control strategy near the instability which illustrates the effect of multiplicative noise.Comment: minor corrections to previous versio

Catholic Healthcare Organizations and the Articulation of Their Identity

Contains fulltext : 69947.pdf (publisher's version ) (Open Access

Different W cluster deposition regimes in pulsed laser ablation observed by in situ Scanning Tunneling Microscopy

We report on how different cluster deposition regimes can be obtained and observed by in situ Scanning Tunneling Microscopy (STM) by exploiting deposition parameters in a pulsed laser deposition (PLD) process. Tungsten clusters were produced by nanosecond Pulsed Laser Ablation in Ar atmosphere at different pressures and deposited on Au(111) and HOPG surfaces. Deposition regimes including cluster deposition-diffusion-aggregation (DDA), cluster melting and coalescence and cluster implantation were observed, depending on background gas pressure and target-to-substrate distance which influence the kinetic energy of the ablated species. These parameters can thus be easily employed for surface modification by cluster bombardment, deposition of supported clusters and growth of films with different morphologies. The variation in cluster mobility on different substrates and its influence on aggregation and growth mechanisms has also been investigated.Comment: 12 pages (3 figures); Surface Science (accepted

Fruit production, migrant bird visitation, and seed dispersal of Guarea glabra in Panama

The relationship between bird visitation and the size of the available fruit crop was studied at an understory tree ( Guarea glabra Vahl, Meliaceae) in the tropical wet forest of Barro Colorado Island, Panama Canal Zone. Twelve resident species and seven North American migrant species fed on the Bright orange arilloids (seeds with arils), which were not depleted during the normal fruiting period. The number of individual visitors, the number of visiting species, and the number of seeds removed increased linearly with the size of the available fruit crop. The proportion of seeds removed did not increase with the size of the available fruit crop, indicating that dispersal is a function of the number of fruit available and not a disproportionate function of large fruit displays. Four species of North American migrants ( Myiarchus crinitus, Catharus ustulatus, Vireo olivaceus , and Vermivora peregrina ) accounted for 70% of the visits and 60% of the seeds removed from the trees. No resident species visited Guarea as frequently as any one of these migrants. There was no indication that any single visitor was dependent on this tree for nutrition, nor that the tree was dependent upon any single species for dispersal. We hypothesize that the fruiting season of G. glabra is adaptively synchronized with northward migration of opportunistically frugivorous North American birds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47724/1/442_2004_Article_BF00348067.pd