Isolation and characteristics of a bacteriophage for bacillus stearothermophilus

A bacteriophage (TØ3) which infects the thermophilic bacterium Bacillus stearothermophilus ATCC 8005 was isolated and characterized. Infection of the bacterium by the bacteriophage was carried out at 60°C, the optimum growth temperature of the host. At 60°C the phage has a latent period of 18 minutes and a burst size of about 200. The phage is comparatively thermostable in broth. The half life of the phage is 400 minutes at 60°C, 120 minutes at 65°C, 40 minutes at 70°C and 12 minutes at 75°C. The activation energy for the heat inactivation of TØ3 is 56,000 cal. The buoyant density of TØ3 in a cesium chloride density gradient is 1.526.

Electron micrographs of TØ3 indicate that the phage has a regular hexagonal shaped head 57 mμ long. The morphology of the head is compatible with icosahedral symmetry. Each edge of the head is 29 mμ long, and there are 6 or 7 subunits along each edge. The tail of TØ3 is 125 mμ long and 10 mμ wide. There are about 30 cross striations that are spaced at 3.9 mμ intervals along the tail.

The DNA of phage TØ3 has a melting temperature of 88.5°C. Heat denatured TØ3 DNA can be extensively annealed in a high ionic strength environment. The buoyant density of TØ3 DNA in a cesium chloride density gradient is 1.695. TØ3 DNA contains: 42.7% guanine plus cytosine, as determined from the melting temperature; 43% guanine plus cytosine, as determined from the buoyant density; and 40.2% guanine plus cytosine, as determined by chromatographic separation and spectrophotometric estimation of the bases. The molecular weight of TØ3 DNA is 16.7 X 10⁶ as determined from the band width of the TØ3 DNA concentration distribution in a cesium chloride density gradient. Electron microscopy of TØ3 DNA revealed a single linear molecule that is 11.7 μ long. This corresponds to a molecular weight of 22.5 X 10⁶.

Heat denatured TØ3 DNA forms two bands in a cesium chloride density gradient, one at a density of 1.707 and the other at a density of 1.715. After the separated bands are mixed and annealed in the centrifuge cell, the renatured TØ3 DNA forms a single band at a density of 1.699. These results indicate that the two complementary strands of TØ3 DNA have different buoyant densities in cesium chloride, presumably because they have different base compositions.

The characteristics of TØ3 are compared with those of other phages. A hypothesis is presented for a relationship between the base composition of one strand of TØ3 DNA and the amino acid composition of the proteins of TØ3.

Modeling habits as self-sustaining patterns of sensorimotor behavior

In the recent history of psychology and cognitive neuroscience, the notion of habit has been reduced to a stimulus-triggered response probability correlation. In this paper we use a computational model to present an alternative theoretical view (with some philosophical implications), where habits are seen as self-maintaining patterns of behavior that share properties in common with self-maintaining biological processes, and that inhabit a complex ecological context, including the presence and influence of other habits. Far from mechanical automatisms, this organismic and self-organizing concept of habit can overcome the dominating atomistic and statistical conceptions, and the high temporal resolution effects of situatedness, embodiment and sensorimotor loops emerge as playing a more central, subtle and complex role in the organization of behavior. The model is based on a novel "iterant deformable sensorimotor medium (IDSM)," designed such that trajectories taken through sensorimotor-space increase the likelihood that in the future, similar trajectories will be taken. We couple the IDSM to sensors and motors of a simulated robot, and show that under certain conditions, the IDSM conditions, the IDSM forms self-maintaining patterns of activity that operate across the IDSM, the robot's body, and the environment. We present various environments and the resulting habits that form in them. The model acts as an abstraction of habits at a much needed sensorimotor "meso-scale" between microscopic neuron-based models and macroscopic descriptions of behavior. Finally, we discuss how this model and extensions of it can help us understand aspects of behavioral self-organization, historicity and autonomy that remain out of the scope of contemporary representationalist frameworks.

Medieval Women's Writing

Watt, P., Medieval Women's Writing (Cambridge: Polity Press, 2007) RAE2008

AC & DC magnetic levitation and semi-levitation modelling

This work presents computation analysis of levitated liquid thermal and flow fields with free surface oscillations in AC and DC magnetic fields. The volume electromagnetic force distribution is continuously updated with the shape and position change. The oscillation frequency spectra are analysed for droplets levitation against gravity in AC and DC magnetic fields at various combinations. For larger volume liquid metal confinement and melting the semi-levitation induction skull melting process is simulated with the same numerical model. Applications are aimed at pure electromagnetic material processing techniques and the material properties measurements in uncontaminated conditions.

Vacuum arc remelting time dependent modelling

Vacuum arc remelting (VAR) aims at production of high quality, segregation-free alloys. The quality of the produced ingots depends on the operating conditions which could be monitored and analyzed using numerical modelling. The remelting process uniformity is controlled by critical medium scale time variations of the order 1-100 s, which are physically initiated by the droplet detachment and the large scale arc motion at the top of liquid pool [1,2]. The newly developed numerical modelling tools are addressing the 3-dimensional magnetohydrodynamic and thermal behaviour in the liquid zone and the adjacent ingot, electrode and crucible.

Citología de impresión para neoplasias de la superficie ocular

Se estimó la sensibilidad y especificidad de la citología de impresión como prueba diagnóstica en lesiones conjuntivales clínicamente sospechosas de neoplasia usando como patrón de oro la patología. Se estudiaron 60 pacientes, que ingresaron al azar a la Fundación Oftalmológica Nacional, con diagnóstico clínico de neoplasia de superficie ocular o lesión sospechosa de neoplasia, quienes fueron sometidos a citología de impresión y posterior resección quirúrgica completa, más estudio patológico de la lesión. Se realizó un análisis descriptivo, analizando la sensibilidad y la especificidad con el método clásico y análisis bayesiano.

From erudition to academic competence. 'De la erudición a la competencia académica'.

Monográfico con el título: 'La Universidad y el Espacio Europeo de la Educación Superior'. Resumen basado en el de la publicación

The role of obesity as a modifying factor in patients undergoing non-surgical periodontal therapy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical and microbiological effects of photodynamic therapy associated with nonsurgical periodontal treatment. A 6-month follow-up

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biometric analysis of the maxillary permanent molar teeth and its relation to furcation involvement.

A high rate of root exposure and consequently the exposure of the furcation area is usually observed in multirooted teeth. In maxillary molar teeth, this fact may endanger the three existent furcations (buccal, mesial and distal), causing serious problems. In this research, distance measures from the buccal furcation to the mesial (F1M) and distal (F1D) surfaces of the mesio-buccal and disto-buccal roots; from the mesial furcation to the buccal (F2B) and palatal (F2P) surfaces of the mesio-buccal and palatal roots and from the distal furcation to the buccal (F3B) and palatal (F3P) surfaces of the disto-buccal and palatal roots, respectively were established. One hundred maxillary first molar teeth were used, 50 of the right and 50 of the left side. Reference marks and demarcations were determined on the furcations and also on the root surfaces involved in the measures. We concluded that these measurements are important because they may effectivelly contribute to diagnosis, prevention and treatment of periodontal problems.

Sharpening of periodontal instruments with different sharpening stones and its influence upon root debridement--scanning electronic microscopy assessment

The objective of this study was to evaluate, through scanning electronic microscopy, the effect of sharpening with different sharpening stones on the cutting angle of periodontal curettes (Gracey 5-6), and the influence on root surfaces after debridement and planing. The experimental model consisted of two different phases. In the first, the cutting angles of fifteen stainless steel Gracey 5-6 curettes were analyzed under a scanning electronic microscope after being sharpened with different types of stones. In the second phase, the root surfaces of 25 newly extracted teeth were evaluated with a scanning electronic microscope after being debrided with curettes sharpened with different stones. Analysis of the results showed that the synthetic stones (aluminum oxide and carborundum) are more abrasive and produce more irregular cutting angles, whereas Arkansas stones are less abrasive and produce smoother and more defined cutting angles. There was no significant statistical differences among the five groups tested with regard to the degree of irregularity of the root surfaces after instrumentation.

Relationship between gingival clinical parameters and the reactivity of the BANA test in subgingival samples from children.

Gingivitis is the first manifestation of periodontal disease, and is characterized by painless and slow evolution. Early diagnosis and intervention must be done to avoid the possibility of precocious periodontitis during the childhood or teenage years. The enzymatic BANA test (N-benzoyl-DL-arginine-naphthylamide) was used to evaluate subgingival samples from 54 children between 6 and 9 years of age. Plaque index (PI) and gingival index (GI) were assessed according to the criteria recommended by Löe (1967). Subgingival plaque was collected from the region that featured the greatest periodontal alteration, represented by a higher gingival index. Resulting data were grouped individually according to visible and non-visible plaque and bleeding and non-bleeding gingiva. Results showed that there was no statistically significant correlation between the presence of visible plaque and the positivity of the BANA test, nor was there a statistically significant correlation between the presence of bleeding and the positivity of the BANA test in subgingival samples obtained from children. This study concluded that the BANA test is not an ideal diagnostic test to be applied to children.

Root trunk height as a risk factor for periodontal furcation involvement in maxillary first molars: an in vitro study.

The aim of this study was to correlate the root trunk height from the furcation openings on the buccal, mesial and distal surfaces to the cemento-enamel junction in upper first permanent molars in human beings with risk for periodontal disease progression. One hundred extracted maxillary first molars were used. Reference points and demarcations were determined from the entrance of the buccal (F1), mesial (F2) and distal (F3) furcations to the cemento-enamel junction in millimeters. The mean distances found were 3.50 mm, 4.44 mm and 4.26 mm for the buccal, mesial and distal furcations, respectively, in relation to the cemento-enamel junction. The statistical analyses were Student's t-test and Chi-square (X2). With periodontal disease progression, the buccal furcation presents a greater compromising risk due to its proximity to the cemento-enamel junction, while the mesial furcation is the most distant, comprising a lesser risk.

Effect of induced diabetes mellitus on alveolar bone loss after 30 days of ligature-induced periodontal disease

Several studies have shown that diabetics are more susceptible to the development of severe periodontal disease. Currently, the use of animal models can be considered a feasible alternative in radiographic assessments of these two pathologies. The purpose of this radiographic study was to evaluate the effect of induced diabetes mellitus on alveolar bone loss after 30 days of ligature-induced periodontal disease. Sixty-four Wistar rats were randomly distributed into four experimental groups. Diabetes was induced in Groups II and IV, while periodontal disease was induced in Groups III and IV; Group I was used as control. In order to perform the radiographic assessment of the specimens, the rats were killed on the 3rd and 30th days of the study. Radiographic measurements were assessed with ANOVA and Tukey's test to determine statistically significant differences (p < 0.05). It was observed that Groups III and IV featured greater bone loss when compared to Groups I and II. Only the diabetic group with periodontal disease (Group IV) featured statistically significant greater bone loss when compared to the other groups. These results suggested that the alveolar bone loss resulting from the periodontal disease installation is greater when associated to the diabetes mellitus.