An Alternative Setup for a Base-Station Cellular Antenna

This paper proposes the use of an alternative setup of a cellular base-station antenna with the potential of reducing the cochannel interference. The setup uses a different cell antenna placement strategy where there is one base-station antenna per cell located high at its center. Unlike a traditional base-station antenna radiating in the horizontal direction, the antenna under consideration radiates downward. The beamwidth of the antenna is considered to be wide enough to match the cell diameter. In addition, the radiation pattern beyond the associated beamwidth is assumed to possess a large attenuation. This paper studies the use of the proposed antenna setup by examining the cell geometry and grouping and its effect on the antenna radiation pattern. It is shown that for a sufficiently large attenuation pattern beyond the antenna beamwidth, the corresponding signal-to-interference ratio can be made significantly larger than the one resulting from the traditional antenna setup     

Noise characteristics of oxide-confined vertical-cavitysurface-emitting lasers

We demonstrate the possibility of generating intensity squeezed light with free-running or injected multimode vertical-cavity surface-emitting laser. Sub-shot-noise operation results from very strong anticorrelations between the transverse modes. The influence of the active media diameter on the amount of squeezing is analyzed     

Deformation of concrete and cement paste loaded at constant temperatures from 140 to 724°C

Constant temperature creep of unsealed pure cement paste, gravel and lightweight concretes obtained under constant uniaxial compressive load are reported for temperatures between 140°C and 724°C. The work suggests that it is possible, within certain limits, to uncouple the time, stress and temperature functions of constant high temperature creep, which can be represented mathematically by a simple multiple of the three functions. The time functions of all three mixes were best represented by a power law with an exponent slightly influenced by temperature. It is suggested that the temperature function may not be sufficiently described by the Arrhenius relation during first heating. The temperature function indicated a sharp increase in creep for gravel concrete above 350°C caused by break-up of the aggregate. However, the sharp increase in creep for both lightweight concrete and cement paste above 600°C is seated in the cement paste and appears to be a function of “current” temperature. A rheological criterion therefore limits the structural usefulness of Portland cement concretes to temperatures below 600°C. Similarities in constant high temperature creep behaviour with other materials have been noted.     

Laboratory study of impacts of concrete fragment sizes on wetland water chemistry

This study investigated the effects of urban concrete materials, of different particle sizes, immersed in water through a laboratory-based experiment. Water was sourced from a high conservation-value wetland (Blue Mountains upland swamp). Prior to the experiment, wetland water was dilute (32.5 μS/cm), acidic (pH 5.3) and had detectable major ion concentrations of only sodium and chloride. Water was exposed to three treatments of different concrete fragment sizes (whole, crushed and fine). All treatments increased conductivity and pH and also resulted in modified ionic composition where calcium, potassium, hydroxide, carbonate and sulphate were recorded at much high levels. The extent and speed of water chemistry changes was linked to the particle size of the concrete. The results of this study support the hypothesis that concrete can be an environmentally hazardous material influencing water quality in urban catchments.     

WeBeVis: analyzing user web behavior through visual metaphors

Large wikis such as Wikipedia attract large numbers of editors continuously editing content. It is difficult to observe what editing activity goes on at any given moment, what editing patterns can be observed, and which are the currently active editors and articles. We introduce the design and implementation of an information visualization tool for data streams of recent changes in wikis that aims to address this difficulty. We also show examples of our visualizations from English Wikipedia, and present several patterns of editing activity that we have visually identified using our tool. We have evaluated our tool’s usability, accuracy and speed of task performance in comparison with Wikipedia’s recent changes page, and have obtained qualitative feedback from users on the pros and cons of our tool. We also present a review of the related literature.     

Extraction and replacement of permanent pacemaker leads through occluded vessels: use of extraction sheaths as conduits--balloon venoplasty as an adjunct

Patients (pts) may present for lead extraction with symptomatic or asymptomatic subclavian vein or superior vena cava thrombosis. Replacement of permanent pacemaker leads (PPLs) in these pts may be difficult and may require accessing a new site. We examined the utility of replacing PPLs through completely occluded vessels using extraction sheaths as conduits through the total occlusion. Over six years, a total of 210 atrial and/or ventricular PPLs were extracted from 137 pts. Two pts presented with angiographically documented thrombotic occlusion of the subclavian vein. One additional pt. who had presented with a superior vena cava (SVC) syndrome, had a totally occluded innominate vein and SVC occlusion. Balloon venoplasty was used as an adjunct to dilate the SVC. In all pts, after PPLs were removed via a subclavian extraction sheath through the occluded vessel, the retained sheath was used to place a guide wire, then a peel away dilating sheath, to insert new PPLs, in each case on the side of total venous occlusion. Seven PPLs and two lead fragments were extracted, and five new PPLs replaced, ipsilateral to the venous occlusion. These data show that extraction of PPLs through thrombosed veins may be performed successfully and may not require replacing the leads through a new site. This technique spares the pt the need to access the opposite subclavian vein, and it avoids an excessive number of PPLs in the subclavian vein and SVC. The procedure illustrates an efficient means to reintroduce new PPLs with the potential to reduce associated morbidity, since repeat puncture of the subclavian vein is not required. Safety of the procedure as a whole must be considered with regard to the known risks of lead extraction, some complications of which may be substantial using current techniques.     

Differentiation between Aspergillus flavus and Aspergillus parasiticus from pure culture and aflatoxin-contaminated grapes using PCR-RFLP analysis of aflR-aflJ intergenic spacer

Aflatoxins (AFs) represent the most important single mycotoxin-related food safety problem in developed and developing countries as they have adverse effects on human and animal health. They are produced mainly by Aspergillus flavus and A. parasiticus. Both species have different aflatoxinogenic profile. In order to distinguish between A. flavus and A. parasiticus, gene-specific primers were designed to target the intergenic spacer (IGS) for the AF biosynthesis genes, aflJ and aflR. Polymerase chain reaction (PCR) products were subjected to restriction endonuclease analysis using BglII to look for restriction fragment length polymorphisms (RFLPs). Our result showed that both species displayed different PCR-based RFLP (PCR-RFLP) profile. PCR products from A. flavus cleaved into 3 fragments of 362, 210, and 102 bp. However, there is only one restriction site for this enzyme in the sequence of A. parasiticus that produced only 2 fragments of 363 and 311 bp. The method was successfully applied to contaminated grapes samples. This approach of differentiating these 2 species would be simpler, less costly, and quicker than conventional sequencing of PCR products and/or morphological identification.     

Intraarticular foot and ankle injections to identify source of pain before arthrodesis

OBJECTIVE: The purpose of our study was to evaluate the usefulness of diagnostic joint injections in patients with foot and ankle pain when the radiologist attempts to identify the source of pain. This study also correlated the results of injection with outcome after arthrodesis. MATERIAL AND METHODS: We retrospectively reviewed the records of 22 patients who had a foot or ankle joint injected to identify a source of pain and who later underwent arthrodesis of the painful joint. All patients had long-term foot and ankle symptoms of variable causes. Twenty-four joints were assessed: 13 subtalar, five talonavicular, four ankle, one calcaneocuboid, and one metatarsocuneiform. All patients had plain radiographs, 11 had CT studies, and five had bone scans. Contrast material was used to assess adequate positioning of the needle inside the joint before injection. All joints were injected under fluoroscopic control. Steroid was added in eight joints. After injection, patients were assessed for relief of symptoms. Patients subsequently underwent arthrodesis on the basis of the results of the injection. RESULTS: In 20 patients (22 joints), long-term follow-up showed that injections allowed us to correctly identify the source of pain and successfully guide arthrodesis. Of these 20 patients, 17 had significant pain relief after injection and fusion, whereas three patients had mild or no response. With one of these patients, we injected other joints and changed surgical plans. One of the two remaining patients had more pain relief after injection than after arthrodesis. The other patient had no relief after injection, but subsequent fusion because of persistent pain was successful. We found imaging studies to be less useful than diagnostic injections when we were attempting to identify the source of pain. CONCLUSION: Intraarticular injection of anesthetic in painful foot and ankle joints helped us confirm the source of pain in 20 of 22 patients, which in turn led to successful arthrodesis and good outcomes for these patients.     

Gelatinase B and A expression after laser in situ keratomileusis and photorefractive keratectomy

OBJECTIVE: To compare the expression of gelatinases in the corneal epithelium and stroma after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS: Rabbit eyes were treated with LASIK (n=11), PRK (n=12), or corneal flap construction (n=12); 4 eyes served as unwounded controls. Zymography was performed on the central epithelium and the stroma 1, 3, and 7 days after surgery to determine the expression of gelatinases. RESULTS: Epithelial expression of gelatinase B in the LASIK group (0%-25%) was lower than that in the PRK group at all time points (50%-100%) and was identical to the corneal flap group. Stromal expression of gelatinases A and B was similar after LASIK and PRK, but was minimal after corneal flap construction at all time points. Epithelial expression of gelatinase A was similar for the first 3 days after LASIK and PRK but not thereafter. CONCLUSIONS: Gelatinase B epithelial expression was up-regulated after PRK but not after LASIK. Gelatinase B stromal expression was up-regulated after both procedures. CLINICAL RELEVANCE: Differences in wound healing and subepithelial scarring after these 2 procedures may be related to gelatinase B.     

Electromagnetic radiation and scattering at the American Universityof Beirut

This paper presents the work carried out at the American University of Beirut on electromagnetic radiation and scattering, using the characteristic-modes theory. Several problems of various two-dimensional and three-dimensional geometrics have been considered: slots in a plane, slots in a conducting cylinder, a parallel plate-fed slot antenna, an aperture-fed waveguide, a rectangular aperture in a perfectly conducting plane, a cavity-backed aperture. The characteristic modes for each geometry were first computed, and the convergence of the solution was tested for all these problems. A combined characteristic-modes formulation, for the problem of electromagnetic coupling to conducting objects behind arbitrary apertures in a conducting plane, has been developed and used to solve many of these problems