Physically based walking simulation

Hem realitzat l’estudi de moviments humans i hem buscat la forma de poder crear aquests moviments en temps real sobre entorns digitals de forma que la feina que han de dur a terme els artistes i animadors sigui reduïda. Hem fet un estudi de les diferents tècniques d’animació de personatges que podem trobar actualment en l’industria de l’entreteniment així com les principals línies de recerca, estudiant detingudament la tècnica més utilitzada, la captura de moviments. La captura de moviments permet enregistrar els moviments d’una persona mitjançant sensors òptics, sensors magnètics i vídeo càmeres. Aquesta informació és emmagatzemada en arxius que després podran ser reproduïts per un personatge en temps real en una aplicació digital. Tot moviment enregistrat ha d’estar associat a un personatge, aquest és el procés de rigging, un dels punts que hem treballat ha estat la creació d’un sistema d’associació de l’esquelet amb la malla del personatge de forma semi-automàtica, reduint la feina de l’animador per a realitzar aquest procés. En les aplicacions en temps real com la realitat virtual, cada cop més s’està simulant l’entorn en el que viuen els personatges mitjançant les lleis de Newton, de forma que tot canvi en el moviment d’un cos ve donat per l’aplicació d’una força sobre aquest. La captura de moviments no escala bé amb aquests entorns degut a que no és capaç de crear noves animacions realistes a partir de l’enregistrada que depenguin de l’interacció amb l’entorn. L’objectiu final del nostre treball ha estat realitzar la creació d’animacions a partir de forces tal i com ho fem en la realitat en temps real. Per a això hem introduït un model muscular i un sistema de balanç sobre el personatge de forma que aquest pugui respondre a les interaccions amb l’entorn simulat mitjançant les lleis de Newton de manera realista.

Glutamatergic regulation of mitochondrial ion dynamics in astrocytes

Résumé grand public :Le cerveau se compose de cellules nerveuses appelées neurones et de cellules gliales dont font partie les astrocytes. Les neurones communiquent entre eux par signaux électriques et en libérant des molécules de signalisation comme le glutamate. Les astrocytes ont eux pour charge de capter le glucose depuis le sang circulant dans les vaisseaux sanguins, de le transformer et de le transmettre aux neurones pour qu'ils puissent l'utiliser comme source d'énergie. L'astrocyte peut ensuite utiliser ce glucose de deux façons différentes pour produire de l'énergie : la première s'opère dans des structures appelées mitochondries qui sont capables de produire plus de trente molécules riches en énergie (ATP) à partir d'une seule molécule de glucose ; la seconde possibilité appelée glycolyse peut produire deux molécules d'ATP et un dérivé du glucose appelé lactate. Une théorie couramment débattue propose que lorsque les astrocytes capturent le glutamate libéré par les neurones, ils libèrent en réponse du lactate qui servirait de base énergétique aux neurones. Cependant, ce mécanisme n'envisage pas une augmentation de l'activité des mitochondries des astrocytes, ce qui serait pourtant bien plus efficace pour produire de l'énergie.En utilisant la microscopie par fluorescence, nous avons pu mesurer les changements de concentrations ioniques dans les mitochondries d'astrocytes soumis à une stimulation glutamatergique. Nous avons démontré que les mitochondries des astrocytes manifestent des augmentations spontanées et transitoires de leur concentrations ioniques, dont la fréquence était diminuée au cours d'une stimulation avec du glutamate. Nous avons ensuite montré que la capture de glutamate augmentait la concentration en sodium et acidifiait les mitochondries des astrocytes. En approfondissant ces mécanismes, plusieurs éléments ont suggéré que l'acidification induite diminuerait le potentiel de synthèse d'énergie d'origine mitochondriale et la consommation d'oxygène dans les astrocytes. En résumé, l'ensemble de ces travaux suggère que la signalisation neuronale impliquant le glutamate dicte aux astrocytes de sacrifier temporairement l'efficacité de leur métabolisme énergétique, en diminuant l'activité de leurs mitochondries, afin d'augmenter la disponibilité des ressources énergétiques utiles aux neurones.Résumé :La remarquable efficacité du cerveau à compiler et propager des informations coûte au corps humain 20% de son budget énergétique total. Par conséquent, les mécanismes cellulaires responsables du métabolisme énergétique cérébral se sont adéquatement développés pour répondre aux besoins énergétiques du cerveau. Les dernières découvertes en neuroénergétique tendent à démontrer que le site principal de consommation d'énergie dans le cerveau est situé dans les processus astrocytaires qui entourent les synapses excitatrices. Un nombre croissant de preuves scientifiques a maintenant montré que le transport astrocytaire de glutamate est responsable d'un coût métabolique important qui est majoritairement pris en charge par une augmentation de l'activité glycolytique. Cependant, les astrocytes possèdent également un important métabolisme énergétique de type mitochondrial. Par conséquent, la localisation spatiale des mitochondries à proximité des transporteurs de glutamate suggère l'existence d'un mécanisme régulant le métabolisme énergétique astrocytaire, en particulier le métabolisme mitochondrial.Afin de fournir une explication à ce paradoxe énergétique, nous avons utilisé des techniques d'imagerie par fluorescence pour mesurer les modifications de concentrations ioniques spontanées et évoquées par une stimulation glutamatergique dans des astrocytes corticaux de souris. Nous avons montré que les mitochondries d'astrocytes au repos manifestaient des changements individuels, spontanés et sélectifs de leur potentiel électrique, de leur pH et de leur concentration en sodium. Nous avons trouvé que le glutamate diminuait la fréquence des augmentations spontanées de sodium en diminuant le niveau cellulaire d'ATP. Nous avons ensuite étudié la possibilité d'une régulation du métabolisme mitochondrial astrocytaire par le glutamate. Nous avons montré que le glutamate initie dans la population mitochondriale une augmentation rapide de la concentration en sodium due à l'augmentation cytosolique de sodium. Nous avons également montré que le relâchement neuronal de glutamate induit une acidification mitochondriale dans les astrocytes. Nos résultats ont indiqué que l'acidification induite par le glutamate induit une diminution de la production de radicaux libres et de la consommation d'oxygène par les astrocytes. Ces études ont montré que les mitochondries des astrocytes sont régulées individuellement et adaptent leur activité selon l'environnement intracellulaire. L'adaptation dynamique du métabolisme énergétique mitochondrial opéré par le glutamate permet d'augmenter la quantité d'oxygène disponible et amène au relâchement de lactate, tous deux bénéfiques pour les neurones.Abstract :The remarkable efficiency of the brain to compute and communicate information costs the body 20% of its total energy budget. Therefore, the cellular mechanisms responsible for brain energy metabolism developed adequately to face the energy needs. Recent advances in neuroenergetics tend to indicate that the main site of energy consumption in the brain is the astroglial process ensheating activated excitatory synapses. A large body of evidence has now shown that glutamate uptake by astrocytes surrounding synapses is responsible for a significant metabolic cost, whose metabolic response is apparently mainly glycolytic. However, astrocytes have also a significant mitochondrial oxidative metabolism. Therefore, the location of mitochondria close to glutamate transporters raises the question of the existence of mechanisms for tuning their energy metabolism, in particular their mitochondrial metabolism.To tackle these issues, we used real time imaging techniques to study mitochondrial ionic alterations occurring at resting state and during glutamatergic stimulation of mouse cortical astrocytes. We showed that mitochondria of intact resting astrocytes exhibited individual spontaneous and selective alterations of their electrical potential, pH and Na+ concentration. We found that glutamate decreased the frequency of mitochondrial Na+ transient activity by decreasing the cellular level of ATP. We then investigated a possible link between glutamatergic transmission and mitochondrial metabolism in astrocytes. We showed that glutamate triggered a rapid Na+ concentration increase in the mitochondrial population as a result of plasma-membrane Na+-dependent uptake. We then demonstrated that neuronally released glutamate also induced a mitochondrial acidification in astrocytes. Glutamate induced a pH-mediated and cytoprotective decrease of mitochondrial metabolism that diminished oxygen consumption. Taken together, these studies showed that astrocytes contain mitochondria that are individually regulated and sense the intracellular environment to modulate their own activity. The dynamic regulation of astrocyte mitochondrial energy output operated by glutamate allows increasing oxygen availability and lactate production both being beneficial for neurons.

Seasonality of Lutzomyia intermedia and Lutzomyia whitmani (Diptera: Psychodidae: Phlebotominae), occurring sympatrically in area of cutaneous leishmaniasis in the State of Rio de Janeiro, Brazil

Lutzomyia intermedia and Lutzomyia whitmani occur sympatrically in the district of Posse, municipality of Petrópolis, in the State of Rio de Janeiro (114 km from the city of Rio de Janeiro), where sand flies were captured weekly for three consecutive years in both the peridomicile and forest, in two first years from 18:00 to 22:00 h, using a Shannon trap and CDC light traps. The anthropophilic habit was assessed by recording the specimens that bit the human captors. Considering the different capture types and sites, the following species were identified: Brumptomyia brumpti, B. cardosoi, B. guimaraesi, Lutzomyia amarali, L. longipalpis, L. microps, L. costalimai, L. edwardsi, L. firmatoi, L. migonei, L. termitophila, L. tupynambai, L. fischeri, L. pessoai, L. lutziana, L. shannoni, L. barrettoi, L. intermedia, L. whitmani, L. lloydi, and L. minasensis. L. intermedia (38.3%) and L. whitmani (38.6%) predominated. L. intermedia predominated in the peridomicile, where it displayed more intense anthropophily, while L. whitmani displayed greater density in the banana plantations and forest, preferential sites for biting humans. Studies on seasonality showed that while L. intermedia displayed greater density in the hottest months of the year (December, January, and February), L. whitmani was abundant in the coolest months (June, July, and August), although both occurred throughout the year.

Occurrence of Cryptosporidium (Apicomplexa, Cryptosporidiidae) in Crotalus durissus terrificus (Serpentes, Viperidae) in Brazil

The objective of the present study was to investigate the prevalence of Cryptosporidium (Apicomplexa, Cryptosporidiidae) in the snake Crotalus durissus terrificus (Serpentes, Viperidae). Fifty animals were evaluated for the presence of oocysts of Cryptosporidium sp. at the time of arrival and 30 and 60 days later. Intestinal washings with saline solution (1% body weight), fecal samples, and organ scrapings were collected during the study. Oocysts were concentrated by an ether-phosphate-buffered saline sedimentation technique and then separated by a density gradient centrifugation technique. Smears were made with the sediment and submitted to modified acid-fast and auramine-rhodamine staining. Cryptosporidium-positive smears were used as controls for the experimental findings. The overall prevalence of Cryptosporidium sp. oocysts was 14%. Among the positive snakes, oocysts were detected only in the intestinal washing in two specimens, only in the feces in four specimens, and in both materials at least once in one specimen. The positive snakes were predominantly from Santa Maria da Serra city State of São Paulo (57.1%). We also observed that all of the examinations that presented positive results were obtained at least 27 days after the capture of the animals.

Clinical and epidemiological aspects of human parvovirus B19 infection in an urban area in Brazil (Niterói city area, State of Rio de Janeiro, Brazil)

This study was designed to analyse the clinical and epidemiological data from human parvovirus B19 cases in a six-year study of rash diseases conduct in an urban area in Brazil (Niterói city area, State of Rio de Janeiro). A total of 673 patients with acute rash diseases were seen at two primary health care units and at a general hospital. A clotted blood sample was collected from all subjects at the time of consultation. Forty-nine per cent (330 cases) of the patients were negative for dengue, rubella and measles IgM or for low avidity IgG to HHV-6. Of these 330, 105 (31.8%) were identified as IgM positive to parvovirus B19 by using an antibody capture EIA. During the study period, three distinct peaks of parvovirus infection were detected, suggesting that the disease appears to cycle in approximately 4-5 years. B19 infection was characterized by variable combinations of fever, flu-like symptoms, arthropathy, and gastrointestinal symptoms. Frequency of fever and arthropathy was substantially higher in adults, 75% [chi2 (1 D.F.) = 11.39, p = 0.0007] and 62.5% [chi2 (1 D.F.) = 29.89, p = 0.0000], respectively. "Slapped-cheek" appearance and reticular or lace-like rash were seen in only 30.1% of the children. No adult presented this typical rash. The lack of the typical rash pattern in a large proportion of parvovirus B19 and the similarity of clinical manifestations to other rash diseases, specially to rubella, highlight the difficulty of diagnosing B19 infection on clinical grounds alone.

Detection of Giardia duodenalis antigen in human fecal eluates by enzyme-linked immunosorbent assay using polyclonal antibodies

The present study developed and standardized an enzime-linked immunosorbent assay (ELISA) to detect Giardia antigen in feces using rabbit polyclonal antibodies. Giardia cysts were purified from human fecal samples by sucrose and percoll gradients. Gerbils (Meriones unguiculatus) were infected to obtain trophozoites. Rabbits were inoculated with either cyst or trophozoite antigens of 14 Colombian Giardia isolates to develop antibodies against the respective stages. The IgG anti-Giardia were purified by sequential caprylic acid and ammonium sulfate precipitation. A portion of these polyclonal antibodies was linked to alkaline phosphatase (conjugate). One hundred and ninety six samples of human feces, from different patients, were tested by parasitologic diagnosis: 69 were positive for Giardia cysts, 56 had no Giardia parasites, and 71 revealed parasites other than Giardia. The optimal concentration of polyclonal antibodies for antigen capture was 40 µg/ml and the optimal conjugate dilution was 1:100. The absorbance cut-off value was 0.24. The parameters of the ELISA test for Giardia antigen detection were: sensitivity, 100% (95% CI: 93.4-100%); specificity, 95% (95% CI: 88.6-97.6%); positive predictive value, 91% (95% CI: 81.4-95.9%); and negative predictive value, 100% (95% CI: 96.1-100%). This ELISA will improve the diagnosis of Giardia infections in Colombia and will be useful in following patients after treatment.

Laboratory diagnosis of Schistosomiasis in areas of low transmission: a review of a line of research

After 57 years of successful control of schistosomiasis in Venezuela, the prevalence and intensity of infection have declined. Approximately 80% of the individuals eliminate less than 100 eggs/g of stools, therefore morbidity is mild and the majority are asymptomatic. The sensitivity of Kato-Katz decreases to approximately 60%. Available serological methods for the detection of circulating antigens only reach a 70% of sensitivity. Tests based on the detection of antibodies by immunoenzymatic assays have been improved. The circumoval precipitine test has shown a high sensitivity (97%), specificity (100%), and correlation with oviposition, being considered the best confirmatory diagnostic test. Additionally to the classical immunoenzymatic assays, the development of the alkaline phosphatase immunoassay, allowed to reach a 100% specificity with an 89% sensitivity. Recently, we have developed a modified ELISA in which the soluble egg antigen is treated with sodium metaperiodate (SMP-ELISA) in order to eliminate the glycosilated epitopes responsible for the false positive reactions. The specificity and sensitivity reaches 97% and 99%, respectively. Synthetic peptides from the excretory-secretory enzymes, cathepsin B (Sm31) legumain (Sm32) and cathepsin D (Sm45), have been synthesized. The combination of two peptides derived from the Sm31 have been evaluated, reaching a sensitivity of 96% when analyzed independently and with a 100% specificity. Antibodies raised in rabbits against peptides derived from the Sm31 and Sm32 are currently evaluated in two different antigen-capture-based assays. The development of a simple, cheap and reliable test that correlates with parasite activity is a major goal.

Time to Move On from Congregated Settings: A Strategy for Community Inclusion

19.6.2011 I am pleased to present the Report of the Working Group on Congregated Settings, which is the outcome and culmination of a very significant piece of data capture, research and analysis. The Report was initiated by the Primary, Community and Community Care Directorate in 2007 to develop a national plan and associated change programme for moving people from congregated settings to the community in line with Government policy. Click here to download the document

The 245 kb amplified chromosome of Leishmania (V.) braziliensis contains a biopterin transporter gene

Leishmania (V.) braziliensis M2903 presents a small linear and stable 245 kb chromosome originating from a genomic amplification. Similar amplifications present in other species of Leishmania contain a gene coding for a biopterin transporter. Since Leishmania is auxotrophic for this metabolite, this amplification could result from the need to better capture biotpterin from growth media under specific circumstances. In this paper we show that this gene is also present in L. (V.) braziliensis small chromosome, which shares sequences with other genomic amplifications already described.

Phenotypic divergence but not genetic distance predicts assortative mating among species of a cichlid fish radiation.

The hypothesis of ecological divergence giving rise to premating isolation in the face of gene flow is controversial. However, this may be an important mechanism to explain the rapid multiplication of species during adaptive radiation following the colonization of a new environment when geographical barriers to gene flow are largely absent but underutilized niche space is abundant. Using cichlid fish, we tested the prediction of ecological speciation that the strength of premating isolation among species is predicted by phenotypic rather than genetic distance. We conducted mate choice experiments between three closely related, sympatric species of a recent radiation in Lake Mweru (Zambia/DRC) that differ in habitat use and phenotype, and a distantly related population from Lake Bangweulu that resembles one of the species in Lake Mweru. We found significant assortative mating among all closely related, sympatric species that differed phenotypically, but none between the distantly related allopatric populations of more similar phenotype. Phenotypic distance between species was a good predictor of the strength of premating isolation, suggesting that assortative mating can evolve rapidly in association with ecological divergence during adaptive radiation. Our data also reveals that distantly related allopatric populations that have not diverged phenotypically, may hybridize when coming into secondary contact, e.g. upon river capture because of diversion of drainage systems.

The epidemiologic importance of Triatoma brasiliensis as a Chagas disease vector in Brazil: a revision of domiciliary captures during 1993-1999

To clarify the epidemiologic importance of Triatoma brasiliensis, the most important Chagas disease vector in the Northeastern of Brazil, capture data related to this species, its distribution, capture index, and percentages of natural infection by Trypanosoma cruzi were examined in 12 different Brazilian states. The Brazilian National Health Foundation collected these data from 1993 to 1999, a period during which a total of 1,591,280 triatomines (21 species) were captured in domiciles within the geographic range of T. brasiliensis. Of this total, 422,965 (26.6%) were T. brasiliensis, 99.8% of which were collected in six states, and 54% in only one state (Ceará). The percentage of bugs infected with T. cruzi varied significantly among states, ranging from 0% (Goiás, Maranhão, Sergipe, and Tocantins) to more than 3% (Alagoas, Minas Gerais, and Rio Grande do Norte) with an average of 1.3%. This latter value represents a dramatic reduction in the natural infection percentages since 1983 (6.7%) suggesting that, despite the impossibility of eradicating this native species, the control measures have significantly reduced the risk of transmission. However, the wide geographic distribution of T. brasiliensis, its high incidence observed in some states, and its variable percentages of natural infection by T. cruzi indicate the need for sustained entomological surveillance and continuous control measures against this vector.

A comparative study of congenital toxoplasmosis between public and private hospitals from Uberlândia, MG, Brazil

The main purpose of the present study was to examine if there is difference in terms of incidence rates of congenital toxoplasmosis among populations assisted in public and private hospitals from Uberlândia, state of Minas Gerais, Brazil. A total of 805 serum samples from cord blood were collected, being 500 from public hospital and 305 from private hospital, and all patients answered a questionnaire about pregnancy and newborns. An indirect enzyme linked immunosorbent assay (ELISA) was performed to detect IgG antibodies to Toxoplasma gondii and the positive samples were retested to verify the presence of specific IgM and IgA antibodies in a capture ELISA. We found significant differences among data from both hospitals with respect to maternal age, origin city, gestational age, number of visits to physicians during pregnancy, type of delivery, and birth weight. Seroprevalence of IgG antibodies against T. gondii for patients from public and private hospitals was 57.6% and 41.9% respectively, and this difference was statistically significant (P < 0.0001). In addition, the frequency of congenital toxoplasmosis measured by the presence of IgM and/or IgA antibodies toward T. gondii was exclusively located in samples from public hospital (0.8%), and no positive sample was seen in private hospital (0%). Considering that almost all babies suffering from congenital toxoplasmosis, if undiagnosed and untreated, will develop visual or neurological impairments by adulthood, the results presented herein emphasized the importance to accomplish screening programs for toxoplasmosis during pregnancy, particularly in the public hospitals, due to the expressive rate of congenital disease showed in the patients attended at these centers.

Modelling the mechanical aspects of the curing process of magneto-sensitive elastomeric materials

In this paper, a phenomenologically motivated magneto-mechanically coupled finite strain elastic framework for simulating the curing process of polymers in the presence of a magnetic load is proposed. This approach is in line with previous works by Hossain and co-workers on finite strain curing modelling framework for the purely mechanical polymer curing (Hossain et al., 2009b). The proposed thermodynamically consistent approach is independent of any particular free energy function that may be used for the fully-cured magneto-sensitive polymer modelling, i.e. any phenomenological or micromechanical-inspired free energy can be inserted into the main modelling framework. For the fabrication of magneto-sensitive polymers, micron-size ferromagnetic particles are mixed with the liquid matrix material in the uncured stage. The particles align in a preferred direction with the application of a magnetic field during the curing process. The polymer curing process is a complex (visco) elastic process that transforms a fluid to a solid with time. Such transformation process is modelled by an appropriate constitutive relation which takes into account the temporal evolution of the material parameters appearing in a particular energy function. For demonstration in this work, a frequently used energy function is chosen, i.e. the classical Mooney-Rivlin free energy enhanced by coupling terms. Several representative numerical examples are demonstrated that prove the capability of our approach to correctly capture common features in polymers undergoing curing processes in the presence of a magneto-mechanical coupled load.

Epidemiology of Chagas disease in Jaguaruana, Ceará, Brazil. I. Presence of triatomines and index of Trypanosoma cruzi infection in four localities of a rural area

In order to assay the triatomine infestation and domiciliation in the rural area of Jaguaruana district, state of Ceará, Brazil, we studied, from November 2000 to April 2002, 4 localities comprising 158 domiciles as a whole, with an average of 4 inhabitants/house, who are dwelling in there for more than 7 years. Most houses have tile-covered roofs and the walls built with plaster-covered bricks (57%), followed by bricks without plaster (33%), and mud walls (7.5%). A total of 3082 triatomines were captured from different locations, according to the following capture plan: (a) intradomiciles: 238 Triatoma brasiliensis, 6 T. pseudomaculata, 9 Rhodnius nasutus, and 2 Panstrongylus lutzi; (b) peridomiciles (annexes): 2069 T. brasiliensis, 223 T. pseudomaculata, 121 R. nasutus, and 1 P. lutzi; (c) wild, in carnauba palms (Copernicia prunifera): 413 R. nasutus. From the captured triatomines, 1773 (57.5%) were examined. The natural index of Trypanosoma cruzi infection ranged from 10.8% to 30.2% (average of 17%), depending on the species and the location from where the triatomines were captured.

Ezrin-Radixin-Moesin-binding Sequence of PSGL-1 Glycoprotein Regulates Leukocyte Rolling on Selectins and Activation of Extracellular Signal-regulated Kinases.

P-selectin glycoprotein ligand-1 (PSGL-1) mediates the capture (tethering) of free-flowing leukocytes and subsequent rolling on selectins. PSGL-1 interactions with endothelial selectins activate Src kinases and spleen tyrosine kinase (Syk), leading to α(L)β(2) integrin-dependent leukocyte slow rolling, which promotes leukocyte recruitment into tissues. In addition, but through a distinct pathway, PSGL-1 engagement activates ERK. Because ezrin, radixin and moesin proteins (ERMs) link PSGL-1 to actin cytoskeleton and because they serve as adaptor molecules between PSGL-1 and Syk, we examined the role of PSGL-1 ERM-binding sequence (EBS) on cell capture, rolling, and signaling through Syk and MAPK pathways. We carried out mutational analysis and observed that deletion of EBS severely reduced 32D leukocyte tethering and rolling on L-, P-, and E-selectin and slightly increased rolling velocity. Alanine substitution of Arg-337 and Lys-338 showed that these residues play a key role in supporting leukocyte tethering and rolling on selectins. Importantly, EBS deletion or Arg-337 and Lys-338 mutations abrogated PSGL-1-induced ERK activation, whereas they did not prevent Syk phosphorylation or E-selectin-induced leukocyte slow rolling. These studies demonstrate that PSGL-1 EBS plays a critical role in recruiting leukocytes on selectins and in activating the MAPK pathway, whereas it is dispensable to phosphorylate Syk and to lead to α(L)β(2)-dependent leukocyte slow rolling.