82 research outputs found

    “Un grand livre d’images ouvert”

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    * Mon cher Éric, L’idĂ©e de quelques remarques prĂ©liminaires m’est venue pour lancer la discussion et surtout pour gagner du temps en Ă©cartant un ou deux malentendus courants. Les voici en deux mots. L’importance du cinĂ©ma pour moi n’est pas liĂ©e Ă  la recherche de modĂšles ou d’une inspiration. En particulier, contrairement Ă  ce qu’on entend et lit beaucoup, le cinĂ©ma dominant – c’est-Ă -dire les longs mĂ©trages narratifs – n’a selon moi rien Ă  apprendre Ă  l’écriture romanesque, aucun rĂŽle Ă  joue..

    Provenance and depositional age of the Cryogenian ‘grand conglomĂ©rat’, host of the Kamoa Cu-deposit, Democratic Republic of Congo

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    The Kamoa copper deposit (759 Mt, 2.67% Cu at 1% cut-off) is one of the largest copper deposits in the central African copperbelt. Mineralisation at Kamoa is hosted by the Cryogenian ‘grand conglomĂ©rat’, which was deposited in an intracratonic rift and its sub- basins associated with the break-up of Rodinia, and is equated to the ‘Sturtian’ glaciation, the oldest of the Neoproterozoic glacial events. Using detrital zircon geochronology, the provenance of synglacial and underlying pre-glacial units is compared, to evaluate the temporal dynamics of the sediment supply at Kamoa. The detrital zircon age distributions suggest that the ‘grand conglomĂ©rat’ was derived from locally exposed basement of the Mesoproterozoic Kibaran Supergroup and from significant recycling of underlying pre-glacial units, with minor contributions from distal, primary source areas. The stratigraphic differences in the distribution of zircon age populations of the strata at Kamoa may reflect changes in glacial dynamics or of rifting during deposition of the ‘grand conglomĂ©rat’. A Neoproterozoic zircon age population ~700 Ma is probably derived from rift-related volcanic rocks and is significant because it repositions the timing of mid-Neoproterozoic rifting in the Katangan basin and the maximum depositional age of the ‘grand conglomĂ©rat’. The new age constraints suggest that the midNeoproterozoic ‘Sturtian’ glaciation was globally diachronous.Master of Science (MSc) in Geolog

    A system for exposing molecules and cells to biologically relevant and accurately controlled steady-state concentrations of nitric oxide and oxygen

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    Nitric oxide (NO) plays key roles in cell signaling and physiology, with diverse functions mediated by NO concentrations varying over three orders-of-magnitude. In spite of this critical concentration dependence, current approaches to NO delivery in vitro result in biologically irrelevant and poorly controlled levels, with hyperoxic conditions imposed by ambient air. To solve these problems, we developed a system for controlled delivery of NO and O[subscript 2] over large concentration ranges to mimic biological conditions. Here we describe the fabrication, operation and calibration of the delivery system. We then describe applications for delivery of NO and O[subscript 2] into cell culture media, with a comparison of experimental results and predictions from mass transfer models that predict the steady-state levels of various NO-derived reactive species. We also determined that components of culture media do not affect the steady-state levels of NO or O[subscript 2] in the device. This system provides critical control of NO delivery for in vitro models of NO biology and chemistry.National Cancer Institute (U.S.) (CA026731)National Cancer Institute (U.S.) (CA116318)National Institute of Environmental Health Sciences (ES002109

    The interaction between lipid derivatives of colchicine and tubulin: Consequences of the interaction of the alkaloid with lipid membranes

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    AbstractColchicine is a potent antimitotic poison which is well known to prevent microtubule assembly by binding tubulin very tightly. Colchicine also possesses anti-inflammatory properties which are not well understood yet. Here we show that colchicine tightly interacts with lipid layers. The physical and biological properties of three different lipid derivatives of colchicine are investigated parallel to those of membrane lipids in the presence of colchicine. Upon insertion in the fatty alkyl chains, colchicine rigidifies the lipid monolayers in a fluid phase and fluidifies rigid monolayers. Similarly X-ray diffraction data show that lecithin–water phases are destabilized by colchicine. In addition, an unexpectedly drastic enhancement of the photoisomerization rate of colchicine into lumicolchicine in the lipid environment is observed and further supports insertion of the alkaloid in membranes. Finally the interaction of colchicine with lipids makes the drug inaccessible to tubulin. The possible in vivo significance of these results is discussed

    Design of Functionalized Lipids and Evidence for Their Binding to Photosystem II Core Complex by Oxygen Evolution Measurements, Atomic Force Microscopy, and Scanning Near-Field Optical Microscopy

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    AbstractPhotosystem II core complex (PSII CC) absorbs light energy and triggers a series of electron transfer reactions by oxidizing water while producing molecular oxygen. Synthetic lipids with different alkyl chains and spacer lengths bearing functionalized headgroups were specifically designed to bind the QB site and to anchor this large photosynthetic complex (240 kDa) in order to attempt two-dimensional crystallization. Among the series of different compounds that have been tested, oxygen evolution measurements have shown that dichlorophenyl urea (DCPU) binds very efficiently to the QB site of PSII CC, and therefore, that moiety has been linked covalently to the headgroup of synthetic lipids. The analysis of the monolayer behavior of these DCPU-lipids has allowed us to select ones bearing long spacers for the anchoring of PSII CC. Oxygen evolution measurements demonstrated that these long-spacer DCPU-lipids specifically bind to PSII CC and inhibit electron transfer. With the use of atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM), it was possible to visualize domains of PSII CC bound to DCPU-lipid monolayers. SNOM imaging has enabled us to confirm that domains observed by AFM were composed of PSII CC. Indeed, the SNOM topography images presented similar domains as those observed by AFM, but in addition, it allowed us to determine that these domains are fluorescent. Electron microscopy of these domains, however, has shown that the bound PSII CC was not crystalline

    Socioeconomic status, education, and aortic stiffness progression over 5 years: the Whitehall II prospective cohort study.

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    OBJECTIVE: The inverse association between socioeconomic status (SES) and cardiovascular disease (CVD) risk is well documented. Aortic stiffness assessed by aortic pulse wave velocity (PWV) is a strong predictor of CVD events. However, no previous study has examined the effect of SES on arterial stiffening over time. The present study examines this association, using several measures of SES, and attained education level in a large ageing cohort of British men and women. METHODS: Participants were drawn from the Whitehall II study. The sample was composed of 3836 men and 1406 women who attended the 2008-2009 clinical examination (mean age = 65.5 years). Aortic PWV was measured in 2008-2009 and in 2012-2013 by applanation tonometry. A total of 3484 participants provided PWV measurements on both occasions. The mean difference in 5-year PWV change was examined according to household income, education, employment grade, and father's social class, using linear mixed models. RESULTS: PWV increase [mean: confidence interval (m/s)] over 5 years was higher among participants with lower employment grade (0.38: 0.11-0.65), household income (0.58, 95%: 0.32-0.85), and education (0.30: 0.01, 0.58), after adjusting for sociodemographic variables, BMI, alcohol consumption, smoking, and other cardiovascular risk factors, namely SBP, mean arterial pressure, heart rate, cholesterol, diabetes, and antihypertensive use. CONCLUSION: The present study supports the presence of robust socioeconomic disparities in aortic stiffness progression. Our findings suggest that arterial aging could be an important pathophysiological pathway explaining the impact of lower SES on CVD risk

    Interventions to Modify Psychological Well-Being: Progress, Promises, and an Agenda for Future Research

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    Psychological well-being, characterized by feelings, cognitions, and strategies that are associated with positive functioning (including hedonic and eudaimonic well-being), has been linked with better physical health and greater longevity. Importantly, psychological well-being can be strengthened with interventions, providing a strategy for improving population health. But are the effects of well-being interventions meaningful, durable, and scalable enough to improve health at a population-level? To assess this possibility, a cross-disciplinary group of scholars convened to review current knowledge and develop a research agenda. Here we summarize and build on the key insights from this convening, which were: (1) existing interventions should continue to be adapted to achieve a large-enough effect to result in downstream improvements in psychological functioning and health, (2) research should determine the durability of interventions needed to drive population-level and lasting changes, (3) a shift from individual-level care and treatment to a public-health model of population-level prevention is needed and will require new infrastructure that can deliver interventions at scale, (4) interventions should be accessible and effective in racially, ethnically, and geographically diverse samples. A discussion examining the key future research questions follows

    Inactivation of foodborne viruses by UV light: a review

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    Viruses on some foods can be inactivated by exposure to ultraviolet (UV) light. This green technology has little impact on product quality and, thus, could be used to increase food safety. While its bactericidal effect has been studied extensively, little is known about the viricidal effect of UV on foods. The mechanism of viral inactivation by UV results mainly from an alteration of the genetic material (DNA or RNA) within the viral capsid and, to a lesser extent, by modifying major and minor viral proteins of the capsid. In this review, we examine the potential of UV treatment as a means of inactivating viruses on food processing surfaces and different foods. The most common foodborne viruses and their laboratory surrogates; further explanation on the inactivation mechanism and its efficacy in water, liquid foods, meat products, fruits, and vegetables; and the prospects for the commercial application of this technology are discussed. Lastly, we describe UV’s limitations and legislation surrounding its use. Based on our review of the literature, viral inactivation in water seems to be particularly effective. While consistent inactivation through turbid liquid food or the entire surface of irregular food matrices is more challenging, some treatments on different food matrices seem promising.Ciencias de la Alimentació

    Integration of a Raman spectroscopy system to a robotic-assisted surgical system for real-time tissue characterization during radical prostatectomy procedures

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    Surgical excision of the whole prostate through a radical prostatectomy procedure is part of the standard of care for prostate cancer. Positive surgical margins (cancer cells having spread into surrounding nonresected tissue) occur in as many as 1 in 5 cases and strongly correlate with disease recurrence and the requirement of adjuvant treatment. Margin assessment is currently only performed by pathologists hours to days following surgery and the integration of a real-time surgical readout would benefit current prostatectomy procedures. Raman spectroscopy is a promising technology to assess surgical margins: its in vivo use during radical prostatectomy could help insure the extent of resected prostate and cancerous tissue is maximized. We thus present the design and development of a dual excitation Raman spectroscopy system (680- and 785-nm excitations) integrated to the robotic da Vinci surgical platform for in vivo use. Following validation in phantoms, spectroscopic data from 20 whole human prostates immediately following radical prostatectomy are obtained using the system. With this dataset, we are able to distinguish prostate from extra prostatic tissue with an accuracy, sensitivity, and specificity of 91%, 90.5%, and 96%, respectively. Finally, the integrated Raman spectroscopy system is used to collect preliminary spectroscopic data at the surgical margin in vivo in four patients

    Current recommendations on the selection of measures for well-being

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    Measures of well-being have proliferated over the past decades. Very little guidance has been available as to which measures to use in what contexts. This paper provides a series of recommendations, based on the present state of knowledge and the existing measures available, of what measures might be preferred in which contexts. The recommendations came out of an interdisciplinary workshop on the measurement of well-being. The recommendations are shaped around the number of items that can be included in a survey, and also based on the differing potential contexts and purposes of data collection such as, for example, government surveys, or multi-use cohort studies, or studies specifically about psychological well-being. The recommendations are not intended to be definitive, but to stimulate discussion and refinement, and to provide guidance to those relatively new to the study of well-being
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