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The production of electricity from photovoltaics continues to attract worldwide interest, most recently as a power source for distributedenergy generation. Today's photovoltaic systems are already being used effectively for smaller power needs in remote applications. For both of these applications, the issues of reliability, efficiency, safety, and low cost are the principal drivers of system technology. Thisreview uses these design issues to provide a system perspective on the current status of the technology, the changes it has already experienced and the necessity for improvements, especially in tomorrow's systems. The discussion of remaining issues focuses on the reduction of area-related and collector costs, the accurate prediction of performance and lifetime, and the need for developing much better information on recurring costs for maintenance and component replacement. Copyright (c) 1999 John Wiley & Sons, Ltd. This paper was produced under the auspices of the US Government and it is therefore not subject to copyright in the US. [ABSTRACT FROM AUTHOR]

Given the heterogeneity within the γ-aminobutyric acid (GABA) receptor and transporter families, a detailed insight into the pharmacology is still relatively sparse. To enable studies of the physiological roles governed by specific receptor and transporter subtypes, a series of GABA analogues comprising five-membered nitrogen- and sulfur-containing heterocycles as amine bioisosteres were synthesized and pharmacologically characterized at native and selected recombinant GABA A receptors and GABA transporters. The dihydrothiazole and imidazoline analogues, 5-7, displayed moderate GAT activities and GABA A receptor binding affinities in the mid-nanomolar range ( K i , 90-450 nM). Moreover, they exhibited full and equipotent agonist activity compared to GABA at GABA A -αβγ receptors but somewhat lower potency as partial agonists at the GABA A -ρ 1 receptor. Stereoselectivity was observed for compounds 4 and 7 for the GABA A -αβγ receptors but not the GABA A -ρ 1 receptor. This study illustrates how subtle differences in these novel amino GABA bioisosteres result in diverse pharmacological profiles in terms of selectivity and efficacy.

Tungiasis is a neglected parasitic skin disease caused by the permanent penetration of the female sand flea Tunga penetrans (also called jigger flea) into the skin of its host. Growing urbanisation, improved housing and the use of appropriate footwear have presumably led to an overall reduction of the occurrence of this ectoparasitosis within the last few decades. However, it is still highly prevalent in regions where people live in extreme poverty, such as in many Latin American and African countries [1, 2]. We report the case of a 44-year-old woman who returned from an excursion trip to Kenya's savannah with an infection of T. penetrans located on her right big toe around the nail. The natural history, pathology, epidemiology, diagnosis, therapy and control of this parasitic skin disease are discussed [1].

Pseudomembranous colitis is an uncommon pathology although the number of cases recorded has risen steadily over the past decades. It is closely correlated with antibiotic treatment and above all affects immunodepressed subjects. It is manifested by a wide variety of clinical symptoms, ranging from simple diarrhea to acute abdomen. The latter, although fortunately extremely rare, often requires surgical therapy.

Cavernous hemangioma is the most common benign tumor of the liver. Most patients are asymptomatic and the tumor is discovered incidentally during diagnostics procedures, at laparotomy or at autopsy. Only 10% of hepatic hemangiomas reach dimensions that need surgical treatment. The role of surgical excision in their treatment has not been well defined. We report a careful examination of our casuistry and at the same time a study of the literature.

On the basis of the observation of one case of delayed presentation of traumatic diaphragmatic rupture of the left side with a late diaphragmatic hernia, the authors examine the evolution of the occurrence of this pathology during the last 20 years. The clinical signs and the modality of presentation of the lesions of delayed diagnosis appear absolutely non specific. Incorrect interpretation of the X-ray or only intermittent hernial symptoms are frequent reasons for incorrect diagnosis. Also the initially non recognition of the possible manifestation of the diaphragmatic hernia following blunt or penetrating injuries is usually because the practitioner has not sought it. The diaphragmatic domes must be systematically explored during the laparotomy or thoracotomy performed for thoraco-abdominal trauma. Surgical treatment of long-standing post-traumatic diaphragmatic hernia is the same as that applicable in the recent hernias.

Pancreaticojejunostomy is still followed by an unacceptable mortality and it warns the necessity to find and to verify more safe alternative methods in the management of pancreatic stump. In this work we analyze the results concerning 14 cases of pancreatic resections in which a pancreaticojejunostomy was not performed but the stump was closed with a mechanical stapler. Distal pancreatectomy with stapler was characterized by a low morbidity (11%) without mortality; this technique is therefore certainly reliable and it may be preferred for its facility and its rapidity. Pancreaticoduodenectomy with stapler has not appeared sufficiently sure, however, some technical improvements, as additional ligation of the pancreatic duct, the pharmacological inhibition of the exocrine secretion and a more extensive resection, seem to be able to make this technique as much reliable.

Nine patients with tumors of the duodenum and the jejunum are described herein and the Literature is reviewed. Of the six patients with a duodenal tumor, five had an adenocarcinoma and one a Brunner's gland adenoma. A predominance of inframpullary tumors was observed within the duodenum. Jaundice and abdominal pain were, respectively, the most common presenting symptoms of the tumors localized in the periampullary and inframpullary region. Treatment was curative in four and palliative in two cases. Duodenopancreatectomy was the treatment of choice for periampullary tumors whereas segmental resection was performed in the only resectable distal duodenal tumor. Of the three patients with jejunal neoplasms, one had an adenocarcinoma arising in the efferent loop of a Billroth II gastrojejunostomy performed 40 years before and two had an high malignant lymphoma. All three the tumors could be resected. According to the Literature, our results show that: 1. The diagnosis of duodeno-jejunal tumors is usually late: 2. Although of critical importance in the improvement of the overall diagnostic accuracy, endoscopy may be inconclusive or even misleading if the entire duodenum is not explored; 3. If duodenopancreatectomy is mandatory for periampullary tumors, segmental resection seems to be an adequate procedure for tumors of the distal duodenum since it does not ignore lymphatic nodes, can be easily performed and has a low postoperative complication rate.

Results concerning 819 digestive sutures and anastomoses, 376 (45.9%) of which hand sewn and 443 (54.1%) stapled, are retrospectively analyzed. Comparative evaluation of the two techniques yielded better results for oesophageal and rectal anastomoses as well as duodenal stump closure mechanically performed. For intestinal anastomoses the two techniques showed similar results when performed in election, on the contrary, mechanical sutures fared significantly worse than hand-sutures in non elective surgery, with a morbidity of 30.9% vs 10.2% (p less than 0.05) and a mortality of 4.8% vs 0%. In conclusion, for esophageal, rectal and duodenal anastomoses staplers may be preferred, while for the intestinal anastomoses in non elective surgery hand-sutures should be preferred.

A prospective study for assessment of operative risk in elderly patients was carried in 1182 adult patients, 14 yrs or more, surgically treated not for urgency during 1985 in six Italian centres. Looking for meaningful relations among prognostic factors and outcome of disease is a relevant topic in biomedical of surgical risk was the use of multiple logistic function. Anamnestic, clinical and surgical variables were "explicative" variables, while occurrence of death and postoperative complications were "response" variables. Multipathology (myocardiosclerosis, respiratory failure) frequently associated with advanced age (greater than 70 yrs) contribute to determine the prognosis in surgery of elderly patient. Stepwise logistic regression model was applied to a set of preoperative and operative factors, five of which were found to significantly correlate with death: nutritional status, renal failure, reintervention, bacterial contamination during surgery, age greater than 70 years. From our data some conclusion may be drown: it is emphasized the major role of surgical factors in affecting the postoperative risk; among clinical variables, renal failure furnishes the most relevant contribution to prognosis; advanced age itself does not substantially affect the surgical risk, its role being confounded by association with other pathologies.

In this study 8 pancreatic resections were performed using the Autosuture stapler. No fistula developed among 5 cases of distal pancreatectomy, conversely 2 pancreatic fistula occurred in 3 cases of pancreaticoduodenectomy; one patient died for fistula. It is concluded that distal pancreatectomy with staplers is a reasonable and safe alternative to pancreaticojejunostomy, and may be preferred because of its facility and rapidity. Staple closure of the transected pancreas in pancreaticoduodenectomy doesn't seem to be so safe and further evaluation is needed.