988 resultados para Temps de fixation
Resumo:
Un bon sistema d’il.luminació juga un paper molt important per tal que els videojocs siguin realistes i atractius per a l’usuari. El projecte intenta optimitzar el sistema d’il.luminació de manera que la càrrega que representa per al sistema sigui inferior, sense haver de renunciar a la qualitat que tindríem sense fer servir aquest sistema. Amb dos objectius molt concrets: entendre i implementar l’algoritme de lightcuts i aconseguir una optimització en una escena utilitzant aquest algoritme
Resumo:
Els riscos ètics als serveis socials en temps de crisi es multipliquen i s’intensifiquen, però en essència no es tracta de riscos nous ni diferents dels que es podien produir en temps de bonança econòmica i social. No obstant, la cruesa del context dels serveis socials bàsics (freqüència de les situacions límit que s'han d'atendre, les qüestions internes i externes de la pràctica professional, el malestar i desencant dels professionals) pot suposar una oportunitat de visibilitat i prendre consciència d'aquests riscos ètics. A la vegada, l'anàlisi i l'abordatge d'aquest nou context des d'una perspectiva ètica pot suposar un antídot que permeti ressituar la pràctica professional (amb els seus límits, però també amb les seves possibilitats), millorar-ne la qualitat i la transparència, i, de retruc, trencar amb la dinàmica de cronificació de la insatisfacció i queixa professional. És a dir, la perspectiva ètica pot ajudar a aixecar la moral dels professionals. Així doncs, amb aquesta recerca pretenem assolir els següents objectius: Identificar els riscos ètics de la intervenció als serveis socials bàsics en relació als efectes i l'impacte de la crisi econòmica; analitzar els diferents riscos ètics identificats i efectuar propostes d'abordatge i minimització d'aquests riscos ètics
Resumo:
Cranial bone reconstructions are necessary for correcting large skull bone defects due to trauma, tumors, infections and craniotomies. Traditional synthetic implant materials include solid or mesh titanium, various plastics and ceramics. Recently, biostable glass-fiber reinforced composites (FRC), which are based on bifunctional methacrylate resin, were introduced as novel implant solution. FRCs were originally developed and clinically used in dental applications. As a result of further in vitro and in vivo testing, these composites were also approved for clinical use in cranial surgery. To date, reconstructions of large bone defects were performed in 35 patients. This thesis is dedicated to the development of a novel FRC-based implant for cranial reconstructions. The proposed multi-component implant consists of three main parts: (i) porous FRC structure; (ii) bioactive glass granules embedded between FRC layers and (iii) a silver-polysaccharide nanocomposite coating. The porosity of the FRC structure should allow bone ingrowth. Bioactive glass as an osteopromotive material is expected to stimulate the formation of new bone. The polysaccharide coating is expected to prevent bacterial colonization of the implant. The FRC implants developed in this study are based on the porous network of randomly-oriented E-glass fibers bound together by non-resorbable photopolymerizable methacrylate resin. These structures had a total porosity of 10–70 volume %, of which > 70% were open pores. The pore sizes > 100 μm were in the biologically-relevant range (50-400 μm), which is essential for vascularization and bone ingrowth. Bone ingrowth into these structures was simulated by imbedding of porous FRC specimens in gypsum. Results of push-out tests indicated the increase in the shear strength and fracture toughness of the interface with the increase in the total porosity of FRC specimens. The osteopromotive effect of bioactive glass is based on its dissolution in the physiological environment. Here, calcium and phosphate ions, released from the glass, precipitated on the glass surface and its proximity (the FRC) and formed bone-like apatite. The biomineralization of the FRC structure, due to the bioactive glass reactions, was studied in Simulated Body Fluid (SBF) in static and dynamic conditions. An antimicrobial, non-cytotoxic polysaccharide coating, containing silver nanoparticles, was obtained through strong electrostatic interactions with the surface of FRC. In in vitro conditions the lactose-modified chitosan (chitlac) coating showed no signs of degradation within seven days of exposure to lysozyme or one day to hydrogen peroxide (H2O2). The antimicrobial efficacy of the coating was tested against Staphylococcus aureus and Pseudomonas aeruginosa. The contact-active coating had an excellent short time antimicrobial effect. The coating neither affected the initial adhesion of microorganisms to the implant surface nor the biofilm formation after 24 h and 72 h of incubation. Silver ions released to the aqueous environment led to a reduction of bacterial growth in the culture medium.
Resumo:
Plants were regenerated from leaf-derived callus culture of Stylosanthes scabra, a polyploid legume tolerant to drought and adapted to acid soils. A total of 168 regenerants were planted out in Leonard jars in a complete randomized design. Nitrogen fixation and vegetative growth were indirectly evaluated by shoot dry weight, root dry weight, shoot N content and acetylene reduction activity. The results showed higher variation in the regenerants than in controls not submitted to tissue culture. Significant differences were found for all nitrogen fixation related-traits
Resumo:
NifA protein activates transcription of nitrogen fixation operons by the alternative sigma54 holoenzyme form of RNA polymerase. This protein binds to a well-defined upstream activator sequence (UAS) located at the -200/-100 position of nif promoters with the consensus motif TGT-N10-ACA. NifA of Azospirillum brasilense was purified in the form of a glutathione-S-transferase (GST)-NifA fusion protein and proteolytic release of GST yielded inactive and partially soluble NifA. However, the purified NifA was able to induce the production of specific anti-A. brasilense NifA-antiserum that recognized NifA from A. brasilense but not from K. pneumoniae. Both GST-NifA and NifA expressed from the E. coli tac promoter are able to activate transcription from the nifHDK promoter but only in an A. brasilense background. In order to investigate the mechanism that regulates NifA binding capacity we have used E. coli total protein extracts expressing A. brasilense nifA in mobility shift assays. DNA fragments carrying the two overlapping, wild-type or mutated UAS motifs present in the nifH promoter region revealed a retarded band of related size. These data show that the binding activity present in the C-terminal domain of A. brasilense NifA protein is still functional even in the presence of oxygen.
Resumo:
1880 (A8).
Resumo:
1879 (A7).
Resumo:
1882 (A10).
Resumo:
1881 (A9).
Resumo:
1877/12 (A5).
Resumo:
1876 (A4).
Resumo:
1883 (A11).
Resumo:
1878 (A6).
Resumo:
1884 (A12).
