31 resultados para Orbital transfer (Space flight)
em Université de Lausanne, Switzerland
Resumo:
We launched a cryptoendolithic habitat, made of a gneissic impactite inoculated with Chroococcidiopsis sp., into Earth orbit. After orbiting the Earth for 16 days, the rock entered the Earth's atmosphere and was recovered in Kazakhstan. The heat of entry ablated and heated the rock to a temperature well above the upper temperature limit for life to below the depth at which light levels are insufficient for photosynthetic organisms ( approximately 5 mm), thus killing all of its photosynthetic inhabitants. This experiment shows that atmospheric transit acts as a strong biogeographical dispersal filter to the interplanetary transfer of photosynthesis. Following atmospheric entry we found that a transparent, glassy fusion crust had formed on the outside of the rock. Re-inoculated Chroococcidiopsis grew preferentially under the fusion crust in the relatively unaltered gneiss beneath. Organisms under the fusion grew approximately twice as fast as the organisms on the control rock. Thus, the biologically destructive effects of atmospheric transit can generate entirely novel and improved endolithic habitats for organisms on the destination planetary body that survive the dispersal filter. The experiment advances our understanding of how island biogeography works on the interplanetary scale.
Resumo:
Forest fires are defined as uncontrolled fires often occurring in wildland areas, but that can also affect houses or agricultural resources. Causes are both natural (e.g.,lightning phenomena) and anthropogenic (human negligence or arsons).Major environmental factors influencing the fire ignition and propagation are climate and vegetation. Wildfires are most common and severe during drought period and on windy days. Moreover, under water-stress conditions, which occur after a long hot and dry period, the vegetation is more vulnerable to fire. These conditions are common in the United State and Canada, where forest fires represent a big problem. We focused our analysis on the state of Florida, for which a big dataset on forest fires detection is readily available. USDA Forest Service Remote Sensing Application Center, in collaboration with NASA-Goddard Space Flight Center and the University of Maryland, has compiled daily MODIS Thermal Anomalies (fires and biomass burning images) produced by NASA using a contextual algorithm that exploits the strong emission of mid-infrared radiation from fires. Fire classes were converted in GIS format: daily MODIS fire detections are provided as the centroids of the 1 kilometer pixels and compiled into daily Arc/INFO point coverage.
Resumo:
This paper examines theoretical and methodological implications of Clifford Geertz's approach to religion as he formulated it in 'Religion as a cultural system' (Geertz 1966), where religion and culture seem to be defined as functional equivalents. The paper considers religious symbols in the public space, using two examples from contemporary reality - one being a certain expression spoken by the copilot of Egypt Air Flight 990, the other being the headscarf controversy in France - in order to explore how the anthropologist relates the microsituations he observes to an all-embracing context
Resumo:
Purpose: Gene therapy of severe retinal dystrophies directly affecting photoreceptor is still a challenge in terms of clinical application. One of the main hurdles is to generate high transgene expression specifically in rods or cones. In the present study, we are investigating the possibility to drive hPDE6b expression in the Rd10 mouse retina using a specific sequence of the human PDE6b promoter. Methods: Two 5' flanking fragments of the human PDE6b gene: (-93 to +53 (146 bp) and -297 to +53 (350 bp, see Di Polo and Farber, 1995) were cloned in different plasmids in order to check their expression in vitro and in vivo. These elements drove the activity of either luciferase (pGL3 plasmids) or EGFP (AAV2/8 backbone). Then, an AAV2/8 vector carrying the PDE6b cDNA was tested with subretinal injections at P9 in the Rd10 eyes. Eye fundus, OCT, ERG recordings and histological investigations were performed to assess the efficacy of the gene transfer. Results: The short PDE6b promoter containing 146bp (-93 to +53) showed the highest activity in the Y-79 cells, as described previously (Di Polo and Farber, 1995). Subretinal administrations of AAV2/8-PDE6bpromoter-EGFP allowed a rapid expression specifically in rods and not in cones. The expression is faster than a vector containing the CMV promoter. The AAV2/8-PDE6bpromoter-PDE6b and the control vector were injected at P9 in the Rd10 mouse retina and investigated 5 weeks post-injection. Out of 14 eyes, 6 presented an increased rod sensitivity of about 300 fold, and increased a- and b-wave responses in ERG recordings. Flicker stimulations revealed that cones are also functional. OCT images and histological analyses revealed an increased ONL size in the injected area. The retina treated with the therapeutic vector presented 4-6 rows of photoreceptors with outersegments containing PDE6b. In the control eyes, only 2-4 rows of photoreceptors with almost no OS were observed . Conclusions: The 146 bp promoter sequence (-93 to + 53) is the shortest regulatory element described to date which allows to obtain efficient rod-specific expression in the context of somatic gene transfer. This first result is of great interest for AAV vector design in general allowing more space for the accommodation of transgenes of interest and good expression in rods. Moreover we showed the proof of principle of the efficacy of AAV2/8-PDE6bp-PDE6b vector in the Rd10 mouse model of severe photoreceptor degeneration without using neither AAV mutated capsids, nor self-complementary vectors.
Resumo:
The anti-diuretic neurohypophysial hormone Vasopressin (Vp) and its synthetic analogue Desmopressin (Dp, 1-desamino-vasopressin) have received considerable attention from doping control authorities due to their impact on physiological blood parameters. Accordingly, the illicit use of Desmopressin in elite sport is sanctioned by the World Anti-Doping Agency (WADA) and the drug is classified as masking agent. Vp and Dp are small (8-9 amino acids) peptides administered orally as well as intranasally. Within the present study a method to determine Dp and Vp in urinary doping control samples by means of liquid chromatography coupled to quadrupole high resolution time-of-flight mass spectrometry was developed. After addition of Lys-Vasopressin as internal standard and efficient sample clean up with a mixed mode solid phase extraction (weak cation exchange), the samples were directly injected into the LC-MS system. The method was validated considering the parameters specificity, linearity, recovery (80-100%), accuracy, robustness, limit of detection/quantification (20/50 pg mL(-1)), precision (inter/intra-day<10%), ion suppression and stability. The analysis of administration study urine samples collected after a single intranasal or oral application of Dp yielded in detection windows for the unchanged target analyte for up to 20 h at concentrations between 50 and 600 pg mL(-1). Endogenous Vp was detected in concentrations of approximately 20-200 pg mL(-1) in spontaneous urine samples obtained from healthy volunteers. The general requirements of the developed method provide the characteristics for an easy transfer to other anti-doping laboratories and support closing another potential gap for cheating athletes.
Resumo:
We investigated a new procedure for gene transfer into the stroma of pig cornea for the delivery of therapeutic factors. A delimited space was created at 110 mum depth with a LDV femtosecond laser in pig corneas, and a HIV1-derived lentiviral vector expressing green fluorescent protein (GFP) (LV-CMV-GFP) was injected into the pocket. Corneas were subsequently dissected and kept in culture as explants. After 5 days, histological analysis of the explants revealed that the corneal pockets had closed and that the gene transfer procedure was efficient over the whole pocket area. Almost all the keratocytes were transduced in this area. Vector diffusion at right angles to the pocket's plane encompasses four (endothelium side) to 10 (epithelium side) layers of keratocytes. After 21 days, the level of transduction was similar to the results obtained after 5 days. The femtosecond laser technique allows a reliable injection and diffusion of lentiviral vectors to efficiently transduce stromal cells in a delimited area. Showing the efficacy of this procedure in vivo could represent an important step toward treatment or prevention of recurrent angiogenesis of the corneal stroma.
Resumo:
This thesis explores the importance of literary New York City in the urban narratives of Edith Wharton and Anzia Yezierska. It specifically looks at the Empire City of the Progressive Period when the concept of the city was not only a new theme but also very much a typical American one which was as central to the American experience as had been the Western frontier. It could be argued, in fact, that the American city had become the new frontier where modern experiences like urbanization, industrialization, immigration, and also women's emancipation and suffrage, caused all kinds of sensations on the human scale from smoothly lived assimilation and acculturation to deeply felt alienation because of the constantly shifting urban landscape. The developing urban space made possible the emergence of new female literary protagonists like the working girl, the reformer, the prostitute, and the upper class lady dedicating her life to 'conspicuous consumption'. Industrialization opened up city space to female exploration: on the one hand, upper and middle class ladies ventured out of the home because of the many novel urban possibilities, and on the other, lower class and immigrant girls also left their domestic sphere to look for paid jobs outside the home. New York City at the time was not only considered the epicenter of the world at large, it was also a city of great extremes. Everything was constantly in flux: small brownstones made way for ever taller skyscrapers and huge waves of immigrants from Europe pushed native New Yorkers further uptown on the island, adding to the crowdedness and intensity of the urban experience. The city became a polarized urban space with Fifth Avenue representing one end of the spectrum and the Lower East Side the other. Questions of space and the urban home greatly mattered. It has been pointed out that the city setting functions as an ideal means for the display of human nature as well as social processes. Narrative representations of urban space, therefore, provide a similar canvas for a protagonist's journey and development. From widely diverging vantage points both Edith Wharton and Anzia Yezierska thus create a polarized city where domesticity is a primal concern. Looking at all of their New York narratives by close readings of exterior and interior city representations, this thesis shows how urban space greatly affects questions of identity, assimilation, and alienation in literary protagonists who cannot escape the influence of their respective urban settings. Edith Wharton's upper class "millionaire" heroines are framed and contained by the city interiors of "old" New York, making it impossible for them to truly participate in the urban landscape in order to develop outside of their 'Gilt Cages'. On the other side are Anzia Yezierska's struggling "immigrant" protagonists who, against all odds, never give up in their urban context of streets, rooftops, and stoops. Their New York City, while always challenging and perpetually changing, at least allows them perspectives of hope for a 'Promised Land' in the making. Central for both urban narrative approaches is the quest for a home as an architectural structure, a spiritual resting place, and a locus for identity forming. But just as the actual city embraces change, urban protagonists must embrace change also if they desire to find fulfillment and success. That this turns out to be much easier for Anzia Yezierska's driven immigrants rather than for Edith Wharton's well established native New Yorkers is a surprising conclusion to this urban theme.
Resumo:
Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced in diagnostic microbiology laboratories for the identification of bacterial and yeast strains isolated from clinical samples. In the present study, we prospectively compared MALDI-TOF MS to the conventional phenotypic method for the identification of routine isolates. Colonies were analyzed by MALDI-TOF MS either by direct deposition on the target plate or after a formic acid-acetonitrile extraction step if no valid result was initially obtained. Among 1,371 isolates identified by conventional methods, 1,278 (93.2%) were putatively identified to the species level by MALDI-TOF MS and 73 (5.3%) were identified to the genus level, but no reliable identification was obtained for 20 (1.5%). Among the 1,278 isolates identified to the species level by MALDI-TOF MS, 63 (4.9%) discordant results were initially identified. Most discordant results (42/63) were due to systematic database-related taxonomical differences, 14 were explained by poor discrimination of the MALDI-TOF MS spectra obtained, and 7 were due to errors in the initial conventional identification. An extraction step was required to obtain a valid MALDI-TOF MS identification for 25.6% of the 1,278 valid isolates. In conclusion, our results show that MALDI-TOF MS is a fast and reliable technique which has the potential to replace conventional phenotypic identification for most bacterial strains routinely isolated in clinical microbiology laboratories.
Resumo:
Mothers can improve the quality of their offspring by increasing the level of certain components in their eggs. To examine whether or not mothers increase deposition of such components in eggs as a function of food availability, we food-supplemented black-legged kittiwake females (Rissa tridactyla) before and during egg laying and compared deposition of androgens and antibodies into eggs of first and experimentally induced replacement clutches. Food-supplemented females transferred lower amounts of androgens and antibodies into eggs of induced replacement clutches than did non-food-supplemented mothers, whereas first clutches presented no differences between treatments. Our results suggest that when females are in lower condition, they transfer more androgens and antibodies into eggs to facilitate chick development despite potential long-term costs for juveniles. Females in prime condition may avoid these potential long-term costs because they can provide their chicks with more and higher quality resources.
Resumo:
PURPOSE: Orbital wall fracture may occur during endoscopic sinus surgery, resulting in oculomotor disorders. We report the management of four cases presenting with this surgical complication. METHODS: A non-comparative observational retrospective study was carried out on four patients presenting with diplopia after endoscopic ethmoidal sinus surgery. All patients underwent full ophthalmologic and orthoptic examination as well as orbital imaging. RESULTS: All four patients presented with diplopia secondary to a medial rectus lesion confirmed by orbital imaging. A large horizontal deviation as well as limitation of adduction was present in all cases. Surgical management consisted of conventional recession-resection procedures in three cases and muscle transposition in one patient. A useful field of binocular single vision was restored in two of the four patients. CONCLUSION: Orbital injury may occur during endoscopic sinus surgery and cause diplopia, usually secondary to medial rectus involvement due to the proximity of this muscle to the lamina papyracea of the ethmoid bone. Surgical management is based on orbital imaging, duration of the lesion, evaluation of anterior segment vasculature, results of forced duction testing and intraoperative findings. In most cases, treatment is aimed at the symptoms rather than the cause, and the functional prognosis remains guarded.
Resumo:
Nanoparticles (NPs) are being used or explored for the development of biomedical applications in diagnosis and therapy, including imaging and drug delivery. Therefore, reliable tools are needed to study the behavior of NPs in biological environment, in particular the transport of NPs across biological barriers, including the blood-brain tumor barrier (BBTB), a challenging question. Previous studies have addressed the translocation of NPs of various compositions across cell layers, mostly using only one type of cells. Using a coculture model of the human BBTB, consisting in human cerebral endothelial cells preloaded with ultrasmall superparamagnetic iron oxide nanoparticles (USPIO NPs) and unloaded human glioblastoma cells grown on each side of newly developed ultrathin permeable silicon nitride supports as a model of the human BBTB, we demonstrate for the first time the transfer of USPIO NPs from human brain-derived endothelial cells to glioblastoma cells. The reduced thickness of the permeable mechanical support compares better than commercially available polymeric supports to the thickness of the basement membrane of the cerebral vascular system. These results are the first report supporting the possibility that USPIO NPs could be directly transferred from endothelial cells to glioblastoma cells across a BBTB. Thus, the use of such ultrathin porous supports provides a new in vitro approach to study the delivery of nanotherapeutics to brain cancers. Our results also suggest a novel possibility for nanoparticles to deliver therapeutics to the brain using endothelial to neural cells transfer.
Resumo:
The goal of the present work was assess the feasibility of using a pseudo-inverse and null-space optimization approach in the modeling of the shoulder biomechanics. The method was applied to a simplified musculoskeletal shoulder model. The mechanical system consisted in the arm, and the external forces were the arm weight, 6 scapulo-humeral muscles and the reaction at the glenohumeral joint, which was considered as a spherical joint. The muscle wrapping was considered around the humeral head assumed spherical. The dynamical equations were solved in a Lagrangian approach. The mathematical redundancy of the mechanical system was solved in two steps: a pseudo-inverse optimization to minimize the square of the muscle stress and a null-space optimization to restrict the muscle force to physiological limits. Several movements were simulated. The mathematical and numerical aspects of the constrained redundancy problem were efficiently solved by the proposed method. The prediction of muscle moment arms was consistent with cadaveric measurements and the joint reaction force was consistent with in vivo measurements. This preliminary work demonstrated that the developed algorithm has a great potential for more complex musculoskeletal modeling of the shoulder joint. In particular it could be further applied to a non-spherical joint model, allowing for the natural translation of the humeral head in the glenoid fossa.
Resumo:
The need for better gene transfer systems towards improved risk=benefit balance for patients remains a major challenge in the clinical translation of gene therapy (GT). We have investigated the improvement of integrating vectors safety in combining (i) new short synthetic genetic insulator elements (GIE) and (ii) directing genetic integration to heterochromatin. We have designed SIN-insulated retrovectors with two candidate GIEs and could identify a specific combination of insulator 2 repeats which translates into best functional activity, high titers and boundary effect in both gammaretro (p20) and lentivectors (DCaro4) (see Duros et al, abstract ibid). Since GIEs are believed to shield the transgenic cassette from inhibitory effects and silencing, DCaro4 has been further tested with chimeric HIV-1 derived integrases which comprise C-ter chromodomains targeting heterochromatin through either histone H3 (ML6chimera) or methylatedCpGislands (ML10). With DCaro4 only and both chimeras, a homogeneous expression is evidenced in over 20% of the cells which is sustained over time. With control lentivectors, less than 2% of cells express GFP as compared to background using a control double-mutant in both catalytic and ledgf binding-sites; in addition, a two-times increase of expression can be induced with histone deacetylase inhibitors. Our approach could significantly reduce integration into open chromatin sensitive sites in stem cells at the time of transduction, a feature which might significantly decrease subsequent genotoxicity, according to X-SCIDs patients data.Work performed with the support of EC-DG research within the FP6-Network of Excellence, CLINIGENE: LSHB-CT-2006-018933