Influence de l'altitude, de l'exposition et du climat sur la croissance du pin à crochets (Pinus uncinata Ram.) en Cerdagne (Pyrénées orientales françaises)

A dendroecological study was carried out on mountain Pine (Pinus uncinata Ram.) in the French Cerdagne (Pyrénées Orientales). It permits to analyze the influence of three environmental factors: the altitude, the exposure and the climate. 175 dominant trees were sampled between 1780 and 2120 meters on north and south slopes. At the same altitude, the pines on north facing slope are four meters higher than those growing on south slope. However, a detailed analysis of 12874 tree-rings demonstrates that the radial growth is faster on the south slope. On such exposure, the basal area of the hundred years old trees increases 43 % higher than on north slope. Both forests show a similar high mean sensitivity. However, slight differences appear on the climatical response. The rainfall plays a more important part on south exposure, whereas the snow reduces the growth on north slopes. Moreover, the influence of the temperatures is greater than those of the precipitations. Warm spring temperatures are more efficient in the South, while the North is more influenced by the temperatures in autumn.[fr] Une étude dendroécologique du Pin á crochets (Pinus uncinata Ram.) réalisée en Cerdagne française (Pyrénées Orientales) a permis de quantifier le rôle de trois facteurs stationnais sur sa croissance: l'altitude, l'exposition et le climat. 175 arbres dominants ont été échantillonnés entre 1780 et 2120 mètres d'altitude, sur deux versants exposés au Nord et au Sud encadrant le plateau de Cerdagne. A altitude égale, les Pins d'ubac mesurent en moyenne 4 mètres de plus. Cependant, l'analyse détaillée de 12874 largeurs de cernes prouve que la croissance radiale est plus rapide en adret, où la surface terrière a 100 ans augmente de 43 % plus vite qu'en ubac. Les forêts des deux versants présentent une sensibilité au climat manifeste et comparable. L'étude de la réponse au climat permet de nuancer ces résultats: en adret les précipitations ont un rôle bénéfique accru, tandis que l'impact négatif de la neige est spécifique a l'ubac. Quant aux températures, elles jouent un rôle nettement plus marqué que les précipitations. La chaleur printanière agit surtout en adret, tandis que le rôle des températures d'automne est plus manifeste en ubac. [es] Un estudio dendroecológico sobre el Pino negro (Pinus uncinata Ram.) en la Cerdaña francesa permite obtener resultados cuantitativos sobre la influencia de tres parámetros ecológicos que influyen en el crecimiento de los árboles: la altitud, la exposición y el clima. Se han muestreado 175 árboles entre 1780 y 2120 m de altitud, en dos laderas expuestas al Norte y al Sur en la Llanura de Cerdaña. A la misma altitud, los pinos son 4 metros más altos en la ladera Norte. Se han analizado también 12.874 espesores de anillos, que prueban que el crecimiento radial es más rápido en la exposición Sur. En anillos de cien años aumenta un 43% más en la exposición Sur que en la Norte. El estudio de la repuesta biológica al clima permite matizar los resultados. En la solana las precipitaciones son más beneficiosas, mientras que la nieve tiene un impacto negativo en las umbrías. La influencia de las temperaturas es más importante que la de las precipitaciones. El calor de primavera es más influyente en la solana, mientras que las temperaturas de otoño lo son en la umbría

Differential Roles of Tumor Necrosis Factor Ligand Superfamily Members as Biomarkers in Pancreatic Cancer

The tumor necrosis factor⁻related weak inducer of apoptosis (TWEAK) belongs to the tumor necrosis factor ligand superfamily, which was shown to play an important role in inflammatory and malignant gastrointestinal diseases, including colitis or colorectal cancer. However, in contrast to other members of the TNF ligand superfamily, its role as a biomarker in pancreatic cancer is currently unknown. We analyzed serum levels of A proliferation-inducing ligand (APRIL) and TWEAK in 134 patients with pancreatic cancer. Results were compared with 50 healthy controls and correlated with clinical data. Intratumoral expression of APRIL and TWEAK in pancreatic cancer was analysed using the datasets made available by the TCGA-LIHC project. APRIL serum levels were significantly elevated in patients with pancreatic cancer compared to healthy controls, which is in line with previous findings. Notably, the diagnostic accuracy of circulating APRIL levels was similar to CA19-9, an established tumor marker for pancreatic cancer. In contrast, serum concentrations of TWEAK were decreased in pancreatic cancer patients. Interestingly, no differences in TWEAK concentrations became apparent between different clinical subgroups of pancreatic cancer. Moreover, within our cohort of patients, TWEAK levels did not correlate with the patients' prognosis and the diagnostic as well as prognostic potential of TWEAK was lower than CA 19-9, when analyzed in this setting. Finally, using data from the TCGA-LIHC project, we demonstrate that expression levels of TWEAK and APRIL represent prognostic markers for patients' survival according to Kaplan-Meier curve analyses. TWEAK and APRIL serum concentrations are regulated differently in patients with pancreatic cancer, highlighting diverse roles of variant TNF ligands in this type of cancer

Hole spin dynamics and valence-band spin excitations in two-dimensional hole systems

In recent years, the spin dynamics and spin–orbit interaction in GaAs-based two-dimensional hole systems (2DHS) have created a lot of attention. This is due to the complex structure of the valence band, with its p-like character, which leads to strong spin–orbit coupling. In this paper, we review our recent studies on hole spin dynamics and valence-band spin excitations in GaAs-based, p-modulation-doped quantum wells (QWs). In 2DHS with low carrier concentration, we demonstrate that maximizing the heavy-hole–light-hole band splitting by changing the QW width leads to long hole spin dephasing times at low temperatures. Different mechanisms for initializing a resident hole spin polarization by optical excitation are presented. To accurately determine hole spin dynamics parameters, the resonant spin amplification technique is utilized. The strong anisotropy of the hole g factor, and electrical g factor control are investigated, using this technique. In highly doped 2DHS, we use resonant inelastic light scattering (RILS) to study the spin splitting of the valence band. We observe a low-energy spin-density excitation (SDE), which is a measure of the spin splitting of the hole ground state. By varying the laser energy in the RILS experiment, we can resonantly probe the k dependence of the spin splitting. The spectral shape of the SDE depends on the orientation of the light polarizations relative to the crystal axes and reflects the in-plane anisotropy of the valence-band spin splitting