A quasi-unidimensional granular chain to attenuate impact

We study via numerical simulations a granular chain not only with decreasing radii (forward tapering) in geometric progression, but also decorated with grains positioned on the top and bottom of the chain, without altering its original length. The decorating grains act as an auxiliary chain which traps part of the energy and linear momentum, both propagating as a pulse due to disturbances produced at the end of the chain. Thus, this configuration optimizes the impact attenuation and aligns the chain naturally (by symmetry) which facilitates the construction of the experimental setup. Furtheremore, since the decorating grain radii increase along the chain, this new type of chain is necessarily short in order to avoid precompression. Nevertheless, even with short chains, it is possible to mitigate impacts almost completely.

Evidence for the Deflective Function of Eyespots in Wild Junonia evarete Cramer (Lepidoptera, Nymphalidae)

Junonia evarete Cramer is a fast-flying butterfly that perches on the ground with wings opened exhibiting four eyespots close to wing borders. These eyespots presumably function either to intimidate predators, like insectivorous birds, or to deflect bird attacks to less vital parts of the body. We assessed the form, frequency, and location of beak marks on the wings of wild butterflies in central Brazil during two not consecutive years. We found that almost 50% of males and 80% of females bore signals of predator attacks (wing tears), most of them consisting of partially or totally V-shaped forms apparently produced by birds. Males were significantly less attacked and showed a lower proportion of attacks on eyespots than females, suggesting they are better to escape bird attacks. In contrast, females were heavily attacked on eyespots. Eyespot tears in females were higher (and significant different) than expected by chance, indicating that birds do attempt to reach the eyespots when striking on these butterflies. Other comparisons involving the proportion of tears directed or not directed to eyespots in males and females are presented and discussed.

Evaluation of the courtship and of the hybrid male sterility among Drosophila buzzatii cluster species (Diptera, Drosophilidae)

In the Drosophila repleta group the establishment of subgroups and complexes made on the basis of morphological and cytological evidences is supported by tests of reproductive isolation. Among species in the repleta group, the buzzatii cluster, due to its polymorphism and polytipism, is an excellent material for ecological and speciation studies. Some interspecific crosses involving Drosophila seriema, Drosophila sp. B, D. koepferae and D. buzzatii strains were completely sterile while others involving strains from these species produced F1 hybrids that did not yield F2. In the present work, data on courtship duration and copula occurrence obtained in the analysis of flies from parental sterile crosses and on spermatozoon mobility observed in F1 hybrids that did not yield F2 are presented. Copula did not occur during one hour of observation and the spermatozoon also did not show mobility at any of the analyzed stages (3, 7, 9 and 10 days old). There was a high variation in courtship average duration and in the percentage of males that courted the females. The reproductive isolation mechanisms indicated by these observations were pre and post-zygotic, as supported by the absence of copula and male sterility. Data obtained also showed the occurrence of different degrees of reproductive compatibility among the strains classified as the same species but from distinct geographic localities.

[Herpetic esophagitis]

Herpetic esophagitis is an infrequent ulcerative infection of the esophagus caused by Herpes Virus type I. It is usually seen in immunocompromised patients though it may present in immunocompetent ones. Odynophagia and/or dysphagia associated with chest pain are the most frequent clinical symptoms. Radiology, endoscopy, biopsy and serological markers are the basis for diagnosis. We report 3 patients with herpetic esophagitis diagnosed between 1984-1989 and evaluated the clinical, endoscopic and biopsy characteristics. Certain clinical and endoscopic findings common to our patients tend to identify the disease, with biopsy and or serological markers the diagnosis may be established.

[Alcoholic liver disease in Venezuela. Clinical hepato-functional and histopathologic course]

24 patients with alcoholic intake were classified according to the amount of alcohol ingestion; clinical symptoms and signs, liver function tests (bilirubin, aminotransferases and prothrombin time) were analyzed. In all patients a percutaneous liver biopsy was performed and tissue stained by hematoxylin-eosin, wilder reticulin and Mallory trichromic. 9 Histologic criteria were analyzed. 4 groups according to the histology were identified. Group 1 (5 patients) hepatic fibrosis and/or fatty liver. Group 2 (5 patients) alcoholic hepatitis. Group 3 (10 patients) cirrhosis. Group 4 (4 patients) normal. 20% of patients with fatty liver, 80% of alcoholic hepatitis and 100% of cirrhotics referred ingestion or more than 160 g of ethanol and important correlation between liver histological damage and alcohol ingestion. Telangiectasia was the most common clinical finding and present in all hepatitis, 70% of cirrhotics and only 20% of fatty livers. Hemosiderosis was found in 60% of cirrhotics and in alcoholic hepatitis. Only 40% of patients with fatty liver and inflammatory cells while this was evident in all patients with alcoholic hepatitis and those with cirrhosis. Mallory bodies were identified in only 20% of cirrhotics and in none of the alcoholic hepatitis. The results suggest that there are significant differences from a histological and clinical point of view that distinguish alcoholic liver disease as seen in Venezuela from that reported in other countries.

[Dieulafoy's lesion as a cause of massive gastrointestinal hemorrhage]

Dieulafoy's lesion also known as exulceration simplex with submucosal arterial malformation is a rare cause of massive upper gastrointestinal hemorrhage with high mortality. Surgery that has been considered as the preferred diagnostic and therapeutic option has been supplemented by endoscopy; gastroscopy may be a valid alternative for diagnosis and therapy. Between 1981 and 1988 we report 4 cases with massive upper gastrointestinal hemorrhage, haematemesis and hemodynamic decompensation consistent with Dieulafoy's lesion. In all patients emergency gastroscopy was performed, monopolar electrocoagulation was successfully applied in two patients. One patient died during surgery and another sixteen days after surgery from multiple organ failure. Rebleeding was seen in one of the coagulated patients, the site of bleeding was identified as Dieulafoy's lesion in three patients during the first endoscopy and was arterial spurting with normal surrounding gastric mucosa. All lesions were found in the upper third of the stomach. Diagnosis is not easy, especially when the bleeding is intermittent but once identified, endoscopic treatment should be attempted and if this fails surgery may be promptly performed with possible lowering of mortality.

[Diagnosis of tumor or metastasis in the liver by means of laparoscopy and gammagraphy]

Fifty-four patients with proven malignancy of the gastrointestinal tract or suspicion of primary or metastatic hepatic carcinoma were studied to evaluate the effectiveness of different diagnostic methods. Gammagraphic and laparoscopic evaluations were emphasized. The results indicated that laparoscopy was the most effective method for diagnosing primary or metastatic neoplastic liver disease.

[Endoscopic diagnosis of stenosis of Oddi's sphincter]

Thirty-two patients with biliary or pancreatic disease were evaluated by duodenoscopy so as to establish the macroscopic characteristics of the papilla of Vater. In two cases, endoscopic pancreatography was performed as a diagnostic evaluation of the papilla, 30 patients were operated. Our results seem to indicate that the diagnosis of Odditis may be established by endoscopy.