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Institution

University of Bordeaux

EducationBordeaux, France
About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.


Papers
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Journal ArticleDOI
17 May 2012-Nature
TL;DR: This approach provides a general tool for time-resolving multi-electron rearrangements in atoms and molecules—one of the key challenges in ultrafast science.
Abstract: A method of laser-induced recollision permits measurement with attosecond resolution of the times at which the electron leaves the tunnelling barrier and discriminates between the ionization times of two carbon dioxide orbitals. Tunnelling of a particle through a barrier is one of the most fundamental and ubiquitous quantum processes. One issue much debated since the early days of quantum mechanics is the link between tunnelling and the dynamics of the particle outside the barrier. Shafir et al. explore this topic by inducing electron tunnelling from atoms and molecules with a strong laser field and then using a weaker probe field to steer the tunnelled electrons in the lateral direction. The liberated electrons emit an attosecond light burst when they re-encounter their parent ions; the effect of the steering on this light burst provides a measure of the time at which the electrons first exited from the tunnelling barrier, with a sensitivity that is sufficient to resolve subtle differences. This work provides a general approach to the direct resolution of multi-electron rearrangements in atoms and molecules in both space and time. The tunnelling of a particle through a barrier is one of the most fundamental and ubiquitous quantum processes. When induced by an intense laser field, electron tunnelling from atoms and molecules initiates a broad range of phenomena such as the generation of attosecond pulses1, laser-induced electron diffraction2,3 and holography2,4. These processes evolve on the attosecond timescale (1 attosecond ≡ 1 as = 10−18 seconds) and are well suited to the investigation of a general issue much debated since the early days of quantum mechanics5,6,7—the link between the tunnelling of an electron through a barrier and its dynamics outside the barrier. Previous experiments have measured tunnelling rates with attosecond time resolution8 and tunnelling delay times9. Here we study laser-induced tunnelling by using a weak probe field to steer the tunnelled electron in the lateral direction and then monitor the effect on the attosecond light bursts emitted when the liberated electron re-encounters the parent ion10. We show that this approach allows us to measure the time at which the electron exits from the tunnelling barrier. We demonstrate the high sensitivity of the measurement by detecting subtle delays in ionization times from two orbitals of a carbon dioxide molecule. Measurement of the tunnelling process is essential for all attosecond experiments where strong-field ionization initiates ultrafast dynamics10. Our approach provides a general tool for time-resolving multi-electron rearrangements in atoms and molecules11,12,13—one of the key challenges in ultrafast science.

414 citations

Journal ArticleDOI
16 Jun 2011-PLOS ONE
TL;DR: The published evidence is not sufficiently strong to justify a recommendation for the administration of resveratrol to humans, beyond the dose which can be obtained from dietary sources, and animal data are promising in prevention of various cancer types, coronary heart diseases and diabetes which strongly indicate the need for human clinical trials.
Abstract: Background: Resveratrol is a natural compound suggested to have beneficial health effects. However, people are consuming resveratrol for this reason without having the adequate scientific evidence for its effects in humans. Therefore, scientific valid recommendations concerning the human intake of resveratrol based on available published scientific data are necessary. Such recommendations were formulated after the Resveratrol 2010 conference, held in September 2010 in Helsingor, Denmark. Methodology: Literature search in databases as PubMed and ISI Web of Science in combination with manual search was used to answer the following five questions: 1 Can resveratrol be recommended in the prevention or treatment of human diseases?; 2 Are there observed ‘‘side effects’’ caused by the intake of resveratrol in humans?; 3 What is the relevant dose of resveratrol?; 4 What valid data are available regarding an effect in various species of experimental animals?; 5 Which relevant (overall) mechanisms of action of resveratrol have been documented? Conclusions/Significance: The overall conclusion is that the published evidence is not sufficiently strong to justify a recommendation for the administration of resveratrol to humans, beyond the dose which can be obtained from dietary sources. On the other hand, animal data are promising in prevention of various cancer types, coronary heart diseases and diabetes which strongly indicate the need for human clinical trials. Finally, we suggest directions for future research in resveratrol regarding its mechanism of action and its safety and toxicology in human subjects.

413 citations

Journal ArticleDOI
TL;DR: In this article, different kinds of isotopic tracers have been used to trace dust provenance, but special attention is focused on the use of Sr, Nd and Pb isotopes.

413 citations

Book ChapterDOI
01 Jan 1975

412 citations

Journal ArticleDOI
11 Dec 2014-PLOS ONE
TL;DR: With good sensitivity and independent prognostic value on 1-year survival, the G8 questionnaire is currently one of the best screening tools available to identify older cancer patients requiring geriatric assessment, and it should be implemented broadly in daily practice.
Abstract: Background Geriatric Assessment is an appropriate method for identifying older cancer patients at risk of life-threatening events during therapy. Yet, it is underused in practice, mainly because it is time- and resource-consuming. This study aims to identify the best screening tool to identify older cancer patients requiring geriatric assessment by comparing the performance of two short assessment tools the G8 and the Vulnerable Elders Survey (VES-13). Patients and Methods The diagnostic accuracy of the G8 and the (VES-13) were evaluated in a prospective cohort study of 1674 cancer patients accrued before treatment in 23 health care facilities. 1435 were eligible and evaluable. Outcome measures were multidimensional geriatric assessment (MGA), sensitivity (primary), specificity, negative and positive predictive values and likelihood ratios of the G8 and VES-13, and predictive factors of 1-year survival rate. Results Patient median age was 78.2 years (70-98) with a majority of females (69.8%), various types of cancer including 53.9% breast, and 75.8% Performance Status 0-1. Impaired MGA, G8, and VES-13 were 80.2%, 68.4%, and 60.2%, respectively. Mean time to complete G8 or VES-13 was about five minutes. Reproducibility of the two questionnaires was good. G8 appeared more sensitive (76.5% versus 68.7%, P = 0.0046) whereas VES-13 was more specific (74.3% versus 64.4%, P<0.0001). Abnormal G8 score (HR = 2.72), advanced stage (HR = 3.30), male sex (HR = 2.69) and poor Performance Status (HR = 3.28) were independent prognostic factors of 1-year survival. Conclusion With good sensitivity and independent prognostic value on 1-year survival, the G8 questionnaire is currently one of the best screening tools available to identify older cancer patients requiring geriatric assessment, and we believe it should be implemented broadly in daily practice. Continuous research efforts should be pursued to refine the selection process of older cancer patients before potentially life-threatening therapy.

412 citations


Authors

Showing all 28995 results

NameH-indexPapersCitations
Nicholas G. Martin1921770161952
George F. Koob171935112521
Daniel J. Jacob16265676530
Arthur W. Toga1591184109343
James M. Tour14385991364
Floyd E. Bloom13961672641
Herbert Y. Meltzer137114881371
Jean-Marie Tarascon136853137673
Stanley Nattel13277865700
Michel Haïssaguerre11775762284
Liquan Chen11168944229
Marion Leboyer11077350767
Jean-François Dartigues10663146682
Alexa S. Beiser10636647457
Robert Dantzer10549746554
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202378
2022393
20213,110
20203,362
20193,245
20183,143