Indoor signal focusing by means of Fresnel zone plate lens attached to building wall

A simple inexpensive on-wall Fresnel zone plate (FZP) lens for indoor focusing of microwave signals is studied. It consists of concentric metal rings mounted on the outside of an exterior building wall. In our theoretical and empirical work the on-wall FZP lens is illuminated normally by a plane or spherical wave, of vertical or horizontal polarization, but other, more general incidence situations can be treated by similar means. The scalar quasi-optical focusing theory of the free-space zone plate has been modified and used for design and analysis of one-, two-, and three-ring on-wall FZP lenses. It is found that the presence of the wall does not change the FZP lens focusing efficiency significantly, but it has a strong axial defocusing effect. A 2-GHz FZP lens assembly consisting of three metal rings made out of thin antimosquito mesh has a focusing efficiency of about 15 dB (measured) and 14 dB (calculated), and axial defocusing of about 0.22 m. Some variations of on-wall/on-roof FZP lenses and their feasible applications in the microwave/millimeter-wave communication links are also discussed.     

Numerical analysis of greenhouse-type solar stills with high inclination

A numerical analysis has been carried out to evaluated the technical feasibility of single effect solar stills with a cover slope of up to 60°. The aim of the research is to establish the overall distillate productivity and the relative importance of the heat and mass transfer mechanisms when water diffusion is minimal and convection dominates. Experimental measurements of the distillate obtained from an already working unit are related to the numerical results by means of an “equivalent” Prandtl number that simplifies the analysis, allowing for the moist air in the inside of the cavity to be represented as a perfect gas.     

Regional dermolipectomy as treatment for sequelae of massive weight loss

Dermolipectomy is the most important procedure for treatment of the deformities engendered by massive weight loss. It remains the only treatment for excising redundant skin. Although liposuction is useful for removing fatty deposits without traditional surgical incisions, its application is limited by the ability of the skin to contract and conform to the newly sculpted figure. Thus liposuction may serve as an adjunct when treating the sequelae of weight loss but not as a primary procedure. In response to changing expectations, reconstructive surgeons have developed increasingly ingenious and specific dermolipectomy procedures to minimize or hide scars, lessen morbidity, and enhance function. Liposuction in combination with dermolipectomy has expanded the applicability of traditional procedures to a wider variety of patients. Surgical history, patient selection, surgical planning, a spectrum of regional dermolipectomy procedures, and potential complications are discussed herein.     

Comparative study of conventional and SBCI cardboard solar ovens

Two folding and light solar ovens designed and constructed by Solar Box Cookers International (SBCI), Sacramento, U.S.A., have been studied experimentally. Furthermore, their performance is compared with standard two glass solar ovens designed by one of us (S.S.N.), in the climate of Costa Rica. According to our measurements, made with and without load, taken during 30 different days, both cardboard ovens are 15–25% less efficient than the conventional oven and, secondly, the improved SBCI oven is slightly better than the previous SBCI oven.     

Primary immunosuppression with mycophenolate mofetil and antithymocyte globulin for kidney transplant recipients of a suboptimal graft

BACKGROUND: In renal transplantation the beneficial immunosuppressive effects of cyclosporin (CsA) may be curtailed by its nephrotoxicity, specially in patients receiving a cadaveric allograft from suboptimal donors or at risk of delayed graft function. Mycophenolate mofetil (MMF) and antithymocyte globulin (ATG) have each demonstrated to be potent immunosuppressants in renal transplantation. In a prospective analysis we have studied the results at 6 months of the combination of MMF, ATG and low-dose steroids in patients with low immunological risk receiving a first cadaveric renal allograft from a suboptimal donor or at risk of delayed graft function. METHODS: Patients with preformed reactive antibodies < 500% receiving a first graft from a suboptimal donor (age > or = 40 years, non-heart-beating, acute renal failure, arterial hypertension) or at risk of delayed graft function (cold ischaemia time > or = 24 h) were eligible for this open single-arm pilot trial. From September 1996 to March 1997 we recruited 17 patients. They were treated with MMF 2 g p.o. preoperatively, and after transplantation at 3 g/day; rabbit ATG i.v. at 2 mg/kg preoperatively, and 1.5 mg/kg/day the first day after transplantation, followed by four doses of 1 mg/kg on alternate days; prednisone was given at 0.25 mg/kg/day and reduced progressively to 0.1 mg/kg/day at 3 months. Primary outcomes were incidence of biopsy-proven acute rejection, delayed graft function, opportunistic infections, graft and patient survival, and the need for introduction of CsA treatment. RESULTS: delayed graft function occurred in two cases (12%). Four of 17 patients (24%) had a biopsy-proven acute rejection (2 grade I and 2 grade II) within the first 3 months after transplantation. CsA was added in two cases with grade II biopsy-proven acute rejection, and in one with grade I biopsy-proven acute rejection. In one patient MMF was replaced by CsA because of gastrointestinal intolerance. Mean serum creatinine 6 months after transplantation was 159+/-59 micromol/1. Cytomegalovirus tissue invasive disease occurred in one patient (6%). At 6 months follow-up all patients are alive with functioning allografts. CONCLUSIONS: These preliminary results suggest that in low-immunological-risk patients who receive a suboptimal renal allograft or at risk of delayed graft function, the combination of MMF, ATG, and steroids is an efficient immunosuppressive regime that may avoid the use of CsA in 70% of the recipients.     

Toxicological and kinetic study of musk xylene in rainbow trout, Oncorhynchus mykiss

In a prospective study of 6301 surgical patients in a university hospital, we examined the strength of association between ASA physical status classification and perioperative risk factors, and postoperative outcome, using both univariate analysis and calculation of the odds ratio of the risk of developing a postoperative complication by means of a logistic regression model. Univariate analysis showed a significant correlation (P < 0.05) between ASA class and perioperative variables (intraoperative blood loss, duration of postoperative ventilation and duration of intensive care stay), postoperative complications and mortality rate. Univariate analysis of individual preoperative risk factors demonstrated their importance in the development of postoperative complications in the related organ systems. Estimating the increased risk odds ratio for single variables, we found that the risk of complication was influenced mainly by ASA class IV (risk odds ratio = 4.2) and ASA class III (risk odds ratio = 2.2). We conclude that ASA physical status classification was a predictor of postoperative outcome.     

Measurement of interatomic connectivities in molecular sieves using MQMAS-based methods

The multiple-quantum magic angle spinning (MQMAS) NMR method can be extended to allow for investigation of the interatomic connectivities between quadrupolar and spin- nuclei. Several new experiments will be reviewed that combine MQMAS with cross polarization (CP) or heteronuclear recoupling via rotational echo double resonance (REDOR) in order to probe the dipolar interactions between quadrupolar and spin- nuclei under high-resolution conditions. The theoretical and experimental aspects of the spin dynamics involved in these new methods will be discussed. Examples of experimental results will be presented, involving the ¹H–²⁷Al , and ¹⁹F–²⁷Al spin pairs in fluorinated and hydrated aluminophosphates.