Fragmentation Experiment and Model for Falling Mercury Drops

The experiment consists of counting and measuring the size of the many fragments observed after the fall of a mercury drop on the floor. The size distribution follows a power-law for large enough fragments. We address the question of a possible crossover to a second, different power-law for small enough fragments. Two series of experiments were performed. The first uses a traditional film photographic camera, and the picture is later treated on a computer in order to count the fragments and classify them according to their sizes. The second uses a modern digital camera. The first approach has the advantage of a better resolution for small fragment sizes. The second, although with a poorer size resolution, is more reliable concerning the counting of all fragments up to its resolution limit. Both together clearly indicate the real existence of the quoted crossover. The model treats the system microscopically during the tiny time interval when the initial drop collides with the floor. The drop is modelled by a connected cluster of Ising spins pointing up (mercury) surrounded by Ising spins pointing down (air). The Ising coupling which tends to keep the spins segregated represents the surface tension. Initially the cluster carries an extra energy equally shared among all its spins, corresponding to the coherent kinetic energy due to the fall. Each spin which touches the floor loses its extra energy transformed into a thermal, incoherent energy represented by a temperature used then to follow the dynamics through Monte Carlo simulations. Whenever a small piece becomes disconnected from the big cluster, it is considered a fragment, and counted. The results also indicate the existence of the quoted crossover in the fragment-size distribution.Comment: 6 pages, 3 figure

Cowpea symbiotic efficiency, pH and aluminum tolerance in nitrogen-fixing bacteria

Cowpea (Vigna unguiculata) cultivation in northern and northeastern Brazil provides an excellent source of nutrients and carbohydrates for the poor and underprivileged. Production surplus leads to its consumption in other regions of Brazil and also as an export commodity. Its capacity to establish relationships with atmospheric nitrogen-fixing bacteria is crucial to the reduction of production costs and the environmental impact of nitrogen fertilizers. This study assessed the symbiotic efficiency of new strains of symbiotic nitrogen-fixing bacteria with cowpea and their tolerance to pH and aluminum. Twenty-seven strains of bacteria from different soils were evaluated under axenic conditions. These strains were compared to the following inoculant strains: INPA03-11B, UFLA03-84 and BR3267 and two controls that were not inoculated (with and without mineral nitrogen). Six strains and the three strains approved as inoculants were selected to increase the dry weight production of the aerial part (DWAP) and were tested in pots with soil that had a high-density of nitrogen-fixing native rhizobia. In this experiment, three strains (UFLA03-164, UFLA03-153, and UFLA03-154) yielded higher DWAP values. These strains grow at pH levels of 5.0, 6.0, 6.8 and at high aluminum concentration levels, reaching 10(9) CFU mL-1. In particular UFLA03-84, UFLA03-153, and UFLA03-164 tolerate up to 20 mmol c dm-3 of Al+3. Inoculation with rhizobial strains, that had been carefully selected according to their ability to nodulate and fix N2, combined with their ability to compete in soils that are acidic and contain high levels of Al, is a cheaper and more sustainable alternative that can be made available to farmers than mineral fertilizers

Analysis Of Correlation Between Pseudoexfoliation Syndrome And Aneurysm Of The Abdominal Aorta [análise Da Correlação Entre Síndrome De Pseudo-exfoliação E Aneurisma De Aorta Abdominal]

Purpose: To investigate the suggested association between pseudoexfoliation syndrome and aneurysm of the abdominal aorta. Methods: 65 patients recently operated for abdominal aortic aneurysm and 51 controls with peripheral atherosclerosis, without aneurysm, underwent an ophthalmologic examination under pupillary dilatation to detect the presence of pseudoexfoliation syndrome. Results: There were no significant differences regarding mean age and distribution by gender and race between the groups (p > 0.05). Two of 65 patients with aortic aneurysm and one of 51 controls presented pseudoexfoliation syndrome (p = 1.00). Conclusion: The prevalence of pseudoexfoliation syndrome in patients operated for abdominal aortic aneurysm and in patients with peripheral atherosclerosis were similar. This finding does not support the proposed association between pseudoexfoliation syndrome and abdominal aortic aneurysm.673407410Schlötzer-Scherehardt, U., Koca, M.R., Naumann, G.O., Volkholz, H., Pseudoexfoliation syndrome: Ocular manifestation of a systemic disorder? (1992) Arch Ophthalmol, 110, pp. 1752-1756Streeten, B.W., Dark, A.J., Wallace, R.N., Li, Z.Y., Hoepner, J.A., Pseudoexfoliative fibrillopathy in the skin of patients with ocular pseudoexfoliation (1990) Am J Ophthalmol, 110, pp. 490-499Streeten, B.W., Li, Z.Y., Wallace, R.N., Eagle, R.C., Keshgegian, A.A., Pseudoexfoliative fibrillopathy in visceral organs of a patient with pseudoexfoliation syndrome (1992) Arch Ophthalmol, 110, pp. 1757-1762Cursiefen, C., Händel, A., Schönherr, U., Naumman, G.O., Das pseudoexfoliation ssyndrom bei Patienten mit retinaler Venenast-und Zentralvenenthrombose (1997) Klin Monatsbl Augenheilkd, 211, pp. 17-21Cursifen, C., Hammer, T., Kückle, M., Naumann, G.O.H., Schlötzer- Schrehardt, U., Pseudoexfoliation syndrome in eyes with ischemic central retinal vein occlusion. A histopathologic and electron microscopic study (2001) Acta Ophthalmol Scand, 79, pp. 476-478Mitchell, P., Wang, J.J., Smith, W., Association of pseudoexfoliation syndrome with increased vascular risk (1997) Am J Ophthalmol, 124, pp. 685-687Kling, F., Colin, J., Joris, A., Pseudoexfoliation syndrome (PEX): Indicator of increased cardiac and/or vascular risks? [poster] (1999) American Academy Ophthalmology, , Orlando Florida OctoberRitch, R., Exfoliation syndrome: The most common identifiable cause of openangle glaucoma (1994) J Glaucoma, 3, pp. 176-178Ritch, R., Schlötzer-Schrehardt, U., Exfoliation syndrome (2001) Surv Ophthalmol, 45, pp. 265-315Shields, M.B., Glaucomas associated with disorder of the lens (1998) Textbook of Glaucoma, pp. 252-268. , Shields MB. 5 th ed. Baltimore: Williams and WilkinsSchlötzer-Schrehardt, U., Von Der Mark, K., Sakai, Ly., Naumann, G.O., Increased extracellular deposition of fibrillin-1 containing fibrils in pseudoexfoliation syndrome (1997) Invest Ophthalmol Vis Sci, 38, pp. 970-984Schumacher, S., Schlötzer-Scherehardt, U., Martus, P., Lang, W., Naumann, G.O.H., Pseudoexfoliation syndrome and aneurysms of the abdominal aorta (2001) Lancet, 357, pp. 359-360Yüksel, N., Karabas, L., Arslan, A., Demirci, A., Çaglar, Y., Ocular hemodynamics in pseudoexfoliation syndrome and pseudoexfoliation glaucoma (2001) Ophthalmology, 108, pp. 1043-1049Ringvold, A., Pseudoexfoliation and aortic aneurysms (2001) Lancet, 357, pp. 2139-2140Hietanen, J., Soisalon-Soinimen, S., Kivelan, T., Tarkkanen, A., Evaluation the clinical association between exfoliation syndrome and abdominal aortic aneurysm (2002) Acta Ophthalmol Scand, 80, pp. 617-619Urbano, A.P., Freitas, T.G., Arcieri, E.S., Urbano, A.P., Costa, V.P., Avaliação dos tipos de glaucoma no Serviço de Oftalmologia da UNICAMP (2003) Arq Bras Oftalmol, 66, pp. 61-65Ringvold, A., Blika, S., Elsas, T., Guldahl, J., Brevik, T., Hesstvedt, P., The prevalence of pseudoexfoliation in three separate municipalities of Middle-Norway (1987) Acta Ophthalmol, (SUPPL. 182), pp. 17-2

Influência do parasitismo por nematódeos sobre o perfil hematológico de caprinos Influence of nematodes on the hematological parameters of goats

<abstract language="eng">The interaction between ivermectin-resistant and ivermectin-sensitive nematodes and the effect of this anthelmintic on the hematological status of naturally infected goats was assessed using 36 animals. Of these animals, 12 were infected by ivermectin-sensitive gastrointestinal nematodes of the superfamily Trichostrongyloidea (G1s e G1s) 12 were infected by ivermectin-resistant nematodes (G2r e G2r) and 12 uninfect goats (G3np). Six infected goats of each group (G1sm e G2rm) received oral ivermectin al the dose of 200µg/kg, while six were used as controls (G1sc e G2rc). Blood and fecal samples were collected on the day of medication (day zero), at seven, and at 14 days thereafter. The erythrocyte count and hematocrit levels in goats infected by sensitive strains of Haemonchus was greater than that of the group infected by a resistant strain. These values are lower in comparison to those observed in uninfected goats. The increase in the number of eggs per gram of feces, regardless of the strain, is inversely related to the hematocrit level. The use of ivermectin did not significantly change the hematological parameters of goats