Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms

in New Phytologist (2012), 194

• It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not ... [more ▼]

• It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem- level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem–climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models. [less ▲]

Clinical validation of cutoff target ranges in newborn screening of metabolic disorders by tandem mass spectrometry: a worldwide collaborative project.

in Genetics in Medicine : Official Journal of the American College of Medical Genetics (2011), 13(3), 230-54

Exozodiacal Disks

in Lawson, P. R.; Traub, W. A.; Unwin, S. C. (Eds.) Exoplanet Community Report (2009)

From the viewpoint of direct imaging of exoplanets in the visible or infrared, exozodi dust disks can be both good and bad. An exozodi disk is good if it has structures (cleared regions or resonant clumps ... [more ▼]

From the viewpoint of direct imaging of exoplanets in the visible or infrared, exozodi dust disks can be both good and bad. An exozodi disk is good if it has structures (cleared regions or resonant clumps) that suggest the gravitational presence of planets, however it is bad if the dust fills the instrumental field of view with brightness that swamps the signal from a planet. Unfortunately, it takes very little dust to compete with or overwhelm the light from a planet: an Earth‐twin signal is roughly equal to a 0.1‐AU patch of Solar‐System‐twin zodi, in the visible or infrared. Thus, exozodi measurements are extremely important, but they are also difficult to make. Current limits of detection, in units of the Solar‐System brightness, are a few hundred using the Spitzer Space Telescope, about one hundred with the Keck Interferometer (KI), and about 10 expected from the Large Binocular Telescope Interferometer (LBTI). A small coronagraph or small interferometer in space is needed in order to reach the sensitivity required to detect the glow at the level of our own Solar System. [less ▲]

Using passive nonlinear targeted energy transfer to stabilize drill-stringsystems

in Mechanical Systems & Signal Processing (2009), 23

Torsional vibrations of drill strings used in drilling oil and gas wells arises from a complex interaction of the dynamics of the drilling structure with speed-dependent effective rock-cutting forces ... [more ▼]

Torsional vibrations of drill strings used in drilling oil and gas wells arises from a complex interaction of the dynamics of the drilling structure with speed-dependent effective rock-cutting forces. These forces are often difficult to model, and contribute substantially to the instability problems of controlling the drilling operation so as to produce steady cutting. In this work we show how nonlinear passive targeted energy transfer to a lightweight attachment can be used to passively control these instabilities. This is performed by means of a nonlinear energy sink (NES), a lightweight attachment which has been shown to be effective in reducing or even completely eliminating self-excited motions in aeroelastic and other systems. The NES is a completely passive, inherently broadband vibration absorber capable of attracting and dissipating vibrational energy from the primary structure to which it is attached, in this case a nonlinear discontinuous model of a drill-string system. In this paper we describe a prototypical drill string-NES system, briefly discuss some of the analytical and computational tools suitable for its analysis, and then concentrate on mathematical results on the efficacy of the NES in this application and their physical interpretation. [less ▲]

Cerebral correlates of false memories and illusory recollection after sleep and sleep deprivation.

Poster (2008, May)

The XMM-LSS Survey: about Testing the Unified Scheme upon optically identified X-ray selected AGN in the [2-10] keV Band

Poster (2007)

Information Technology - Enhancements to LOTOS (E-LOTOS)

Report (2001)

Référent hospitalier pour la continuité des soins. Etude pilote : Référent hospitalier pour la continuité des soins dans les hôpitaux généraux belges de 1998 – 1999

Report (2000)

Flexifor : vers une flexibilisation de la formation : rapport intermédiaire du projet ADAPT Flexifor

Report (1997)

Depressed Immune Surveillance against Cancer: Role of Deficient T Cell: Extracellular Matrix Interactions

in Cell Adhesion and Communication (1994), 2(3), 225-33

Although T cells infiltrate malignant tumors, the local immune response is usually inefficient and tumors escape destruction. While extracellular matrix proteins strongly costimulate T cell responses in ... [more ▼]

Although T cells infiltrate malignant tumors, the local immune response is usually inefficient and tumors escape destruction. While extracellular matrix proteins strongly costimulate T cell responses in normal individuals, our studies indicate that peripheral blood T cells from cancer patients and tumor infiltrating cells respond poorly or are resistant to stimulative signals mediated by collagen I and IV and fibronectin. Moreover, the adhesive properties of cancer T cells are markedly depressed. Those functional deficiencies are paralleled by variable deficits in integrin and non-integrin T cell receptors for extracellular matrix. Immunotherapy with BCG causes a dramatic but transient increase in T cell: ECM interactions. [less ▲]