262 research outputs found
Laboratory predictors of uphill cycling performance in trained cyclists
This study aimed to assess the relationship between an uphill time-trial (TT) performance and both aerobic and anaerobic parameters obtained from laboratory tests. Fifteen cyclists performed a Wingate anaerobic test, a graded exercise test (GXT) and a field-based 20-min TT with 2.7% mean gradient. After a 5-week non-supervised training period, 10 of them performed a second TT for analysis of pacing reproducibility. Stepwise multiple regressions demonstrated that 91% of TT mean power output variation (W kg-1) could be explained by peak oxygen uptake (ml kg-1.min-1) and the respiratory compensation point (W kg-1), with standardised beta coefficients of 0.64 and 0.39, respectively. The agreement between mean power output and power at respiratory compensation point showed a bias ± random error of 16.2 ± 51.8 W or 5.7 ± 19.7%. One-way repeated-measures analysis of variance revealed a significant effect of the time interval (123.1 ± 8.7; 97.8 ± 1.2 and 94.0 ± 7.2% of mean power output, for epochs 0-2, 2-18 and 18-20 min, respectively; P < 0.001), characterising a positive pacing profile. This study indicates that an uphill, 20-min TT-type performance is correlated to aerobic physiological GXT variables and that cyclists adopt reproducible pacing strategies when they are tested 5 weeks apart (coefficients of variation of 6.3; 1 and 4%, for 0-2, 2-18 and 18-20 min, respectively)
Autonomous underwater gliders monitoring variability at "choke points" in our ocean system: a case study in Western Mediterranean Sea
Publicado
[omega]-Hydroxylation of Oleic Acid in Vicia sativa Microsomes (Inhibition by Substrate Analogs and Inactivation by Terminal Acetylenes)
Positive thyroid transcription factor 1 staining strongly correlates with survival of patients with adenocarcinoma of the lung
This study investigated the relation between positive thyroid transcription factor 1 (TTF1) staining and survival of patients affected by primary adenocarcinoma (ADC) of the lung. Pathological tissue from consecutive ADC patients was collected from 2002 to 2004. The anti-TTF1 antibody (8G7G3/1, dilution of 1/200) was used. Thyroid transcription factor 1 staining was assessed for each tumour as positive or negative. Probability of survival was estimated by Kaplan–Meier and difference tested by log-rank test. A Cox's regression multivariate analysis was carried out. In all, 106 patients were studied (66% male, 69% PS0–1, 83% with stage III or IV). Tumours expressed positive TTF1 staining in 66% of cases. Multivariate analysis demonstrated an independent lower risk of death for patients whose tumour expresses positive TTF1 staining (HR=0.51, 95% CI 0.30–0.85; P=0.01) and higher grade of differentiation (HR=0.40, 95% CI 0.24–0.68; P=0.001). In conclusion, positive TTF1 staining strongly and independently correlates with survival of patients with primary ADC of the lung
Using the past to constrain the future: how the palaeorecord can improve estimates of global warming
Climate sensitivity is defined as the change in global mean equilibrium
temperature after a doubling of atmospheric CO2 concentration and provides a
simple measure of global warming. An early estimate of climate sensitivity,
1.5-4.5{\deg}C, has changed little subsequently, including the latest
assessment by the Intergovernmental Panel on Climate Change.
The persistence of such large uncertainties in this simple measure casts
doubt on our understanding of the mechanisms of climate change and our ability
to predict the response of the climate system to future perturbations. This has
motivated continued attempts to constrain the range with climate data, alone or
in conjunction with models. The majority of studies use data from the
instrumental period (post-1850) but recent work has made use of information
about the large climate changes experienced in the geological past.
In this review, we first outline approaches that estimate climate sensitivity
using instrumental climate observations and then summarise attempts to use the
record of climate change on geological timescales. We examine the limitations
of these studies and suggest ways in which the power of the palaeoclimate
record could be better used to reduce uncertainties in our predictions of
climate sensitivity.Comment: The final, definitive version of this paper has been published in
Progress in Physical Geography, 31(5), 2007 by SAGE Publications Ltd, All
rights reserved. \c{opyright} 2007 Edwards, Crucifix and Harriso
Updating temperature and salinity mean values and trends in the Western Mediterranean: the RADMED project
Postprin
Physical description of an upwelling filament west of Cape St. Vincent in late October 2004
Seismic Constraints on the Thickness and Structure of the Martian Crust from InSight
NASA¿s InSight mission [1] has for
the first time placed a very broad-band seismometer on
the surface of Mars. The Seismic Experiment for
Interior Structure (SEIS) [2] has been collecting
continuous data since early February 2019. The main
focus of InSight is to enhance our understanding of the
internal structure and dynamics of Mars, which includes
the goal to better constrain the crustal thickness of the
planet [3]. Knowing the present-day crustal thickness of
Mars has important implications for its thermal
evolution [4] as well as for the partitioning of silicates
and heat-producing elements between the different
layers of Mars. Current estimates for the crustal
thickness of Mars are based on modeling the
relationship between topography and gravity [5,6], but
these studies rely on different assumptions, e.g. on the
density of the crust and upper mantle, or the bulk silicate
composition of the planet and the crust. The resulting
values for the average crustal thickness differ by more
than 100%, from 30 km to more than 100 km [7].
New independent constraints from InSight will be
based on seismically determining the crustal thickness
at the landing site. This single firm measurement of
crustal thickness at one point on the planet will allow to
constrain both the average crustal thickness of Mars as
well as thickness variations across the planet when
combined with constraints from gravity and topography
[8]. Here we describe the determination of the crustal
structure and thickness at the InSight landing site based
on seismic receiver functions for three marsquakes
compared with autocorrelations of InSight data [9].We acknowledge NASA, CNES, partner agencies and institutions (UKSA, SSO,DLR, JPL, IPGP-CNRS, ETHZ, IC, MPS-MPG) and the operators of JPL, SISMOC, MSDS, IRIS-DMC and PDS for providing SEED SEIS data. InSight data is archived in the PDS, and a full list of archives in the Geosciences, Atmospheres, and Imaging nodes is at https://pds-geosciences.wustl.edu/missions/insight/. This work was partially carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. ©2021, California Institute of Technology. Government sponsorship acknowledge
The interior of Mars as seen by InSight (Invited)
InSight is the first planetary mission dedicated to exploring the whole interior of a planet using geophysical methods, specifically seismology and geodesy. To this end, we observed seismic waves of distant marsquakes and inverted for interior models using differential travel times of phases reflected at the surface (PP, SS...) or the core mantle-boundary (ScS), as well as those converted at crustal interfaces. Compared to previous orbital observations1-3, the seismic data added decisive new insights with consequences for the formation of Mars: The global average crustal thickness of 24-75 km is at the low end of pre-mission estimates5. Together with the the thick lithosphere of 450-600 km5, this requires an enrichment of heat-producing elements in the crust by a factor of 13-20, compared to the primitive mantle. The iron-rich liquid core is 1790-1870 km in radius6, which rules out the existence of an insulating bridgmanite-dominated lower mantle on Mars. The large, and therefore low-density core needs a high amount of light elements. Given the geochemical boundary conditions, Sulfur alone cannot explain the estimated density of ~6 g/cm3 and volatile elements, such as oxygen, carbon or hydrogen are needed in significant amounts. This observation is difficult to reconcile with classical models of late formation from the same material as Earth. We also give an overview of open questions after three years of InSight operation on the surface of Mars, such as the potential existence of an inner core or compositional layers above the CM
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