Evaluation of evapotranspiration methods for model validation in a semi-arid watershed in northern China

International audienceThis study evaluates the performance of four evapotranspiration methods (Priestley-Taylor, Penman-Monteith, Hargreaves and Makkink) of differing complexity in a semi-arid environment in north China. The results are compared to observed water vapour fluxes derived from eddy flux measurements. The analysis became necessary after discharge simulations using an automatically calibrated version of the Soil and Water Assessment Tool (SWAT) failed to reproduce runoff measurements. Although the study area receives most of the annual rainfall during the vegetation period, high temperatures can cause water scarcity. We investigate which evapotranspiration method is most suitable for this environment and whether the model performance of SWAT can be improved with the most adequate evapotranspiration method. The evapotranspiration models were tested in two consecutive years with different rainfall amounts. In general, the simple Hargreaves and Makkink equations outmatch the more complex Priestley-Taylor and Penman-Monteith methods, although their performance depended on water availability. Effects on the quality of SWAT runoff simulations, however, remained minor. Although evapotranspiration is an important process in the hydrology of this steppe environment, our analysis indicates that other driving factors still need to be identified to improve SWAT simulations

Spontaneous intratumoral bleeding and rupture of giant gastric stromal tumor (> 30 cm) in a young patient

<p>Abstract</p> <p>Background</p> <p>Few cases of GIST bigger than 15 cm have been reported in medical literature, all primarily in elderly patients. We report an unusual case, in which a giant gastric GIST – in a young patient – presented as spontaneous intratumoral bleeding followed by intraluminal rupture.</p> <p>Case presentation</p> <p>A 37-year-old man was admitted with an acute onset of abdominal pain. CT showed a 32 × 25 cm mass with some cystic lesions and areas of calcification. Twelve hours after admission the patient presented with an episode of upper GI bleeding, and a significant decrease of tumor size and hemoglobin level. An upper endoscopy showed a large bulge in the posterior aspect of the gastric wall, and a small ulcer with continuous bleeding coming from a central orifice. A subtotal gastrectomy was carried out. Pathological examination showed a giant gastric GIST measuring 32 × 25 × 21 cm and weighing 3.750 g. Immunohistochemical staining demonstrated positive reactivity to C-kit protein, CD34, and α-smooth muscle actin; but negative reactivity to S-100 protein.</p> <p>Conclusion</p> <p>Intratumoral bleeding is a very rare presentation of GIST; preoperative diagnosis is always made difficult by the absence of pathognomonic signs or symptoms. Emergency local excision with negative margins associated with adjuvant therapy with imatinib mesylate remains the main modality of treatment for high risk GISTs.</p

Charge carrier transfer in the gas electron multiplier at low gas gains

Connected to the Linear Collider project TESLA at DESY, studies on the readout of TPCs based on the GEM-technology are ongoing. For particle identication via dE/dx - measurement, a good energy resolution is indispensable, and therefore losses of primary electrons have to be avoided. It turned out, that in the GEM transverse diffusion inside or close to the holes is a not negligible reason for these losses. For Ar-CH4 90:10 and TPC-like field configurations it was found, that when operated in normal amplification mode, the Standard Geometry GEM should not lose primaries, whereas for low gains, also when operated in magnetic fields up to 5T, a GEM with larger pitch and hole diameter would be necessary

Complementary activity of tyrosine kinase inhibitors against secondary kit mutations in imatinib-resistant gastrointestinal stromal tumours

Predictive markers; Sarcoma; Gastrointestinal stromal tumoursMarcadores predictivos; Sarcoma; Tumores del estroma gastrointestinalMarcadors predictius; Sarcoma; Tumors estromals gastrointestinalsBackground Most patients with KIT-mutant gastrointestinal stromal tumours (GISTs) benefit from imatinib, but treatment resistance results from outgrowth of heterogeneous subclones with KIT secondary mutations. Once resistance emerges, targeting KIT with tyrosine kinase inhibitors (TKIs) sunitinib and regorafenib provides clinical benefit, albeit of limited duration. Methods We systematically explored GIST resistance mechanisms to KIT-inhibitor TKIs that are either approved or under investigation in clinical trials: the studies draw upon GIST models and clinical trial correlative science. We subsequently modelled in vitro a rapid TKI alternation approach against subclonal heterogeneity. Results Each of the KIT-inhibitor TKIs targets effectively only a subset of KIT secondary mutations in GIST. Regorafenib and sunitinib have complementary activity in that regorafenib primarily inhibits imatinib-resistance mutations in the activation loop, whereas sunitinib inhibits imatinib-resistance mutations in the ATP-binding pocket. We find that rapid alternation of sunitinib and regorafenib suppresses growth of polyclonal imatinib-resistant GIST more effectively than either agent as monotherapy. Conclusions Our data highlight that heterogeneity of KIT secondary mutations is the main mechanism of tumour progression to KIT inhibitors in imatinib-resistant GIST patients. Therapeutic combinations of TKIs with complementary activity against resistant mutations may be useful to suppress growth of polyclonal imatinib-resistance in GIST.This work was supported in part by an ASCO Young Investigator Award (CS), a Spanish Society of Medical Oncology Translational Award (CS), Río Hortega-ISCIII CM14/00241 (CS) FERO Foundation (CS), US National Institutes of Health grants 1P50CA127003 (GDD, ES, JAF), 1P50CA168512 (JAF, AME), GIST Cancer Research Fund (JAF, MCH), Life Raft Group (JAF, MCH, SB), V Foundation Translational Grant (MCH), VA Merit Review Award (2I01BX000338–05) (MCH) and the Deutsche Krebshilfe (SB). CS acknowledges to the Cellex Foundation for providing facilities and equipment

Development and applications of the Gas Electron Multiplier

The Gas Electron Multiplier (GEM) has been recently developed to cope with the severe requirements of high luminosity particle physics experimentation. With excellent position accuracy and very high rate capability, GEM devices are robust and easy to manufacture. The possibility of cascading two or more multipliers permits to achieve larger gains and more stable operation. We discuss major performances of the new detectors, particularly in view of possible use for high rate portal imaging and medical diagnostics

Information on antiprotonic atoms and the nuclear periphery from the PS209 experiment

In the PS209 experiments at CERN two kinds of measurements were performed: the in-beam measurement of X-rays from antiprotonic atoms and the radiochemical, off-line determination of the yield of annihilation products with mass number A_t -1 (less by 1 than the target mass). Both methods give observables which allows to study the peripheral matter density composition and distribution.Comment: LaTeX (espcrc1 style), 6 pages, 3 EPS figures, 1 table, Proceedings of the Sixth Biennal Conference on Low-Energy Antiproton Physics LEAP 2000, Venice, Ital

Neutron density distributions from antiprotonic 208Pb and 209Bi atoms

The X-ray cascade from antiprotonic atoms was studied for 208Pb and 209Bi. Widths and shifts of the levels due to the strong interaction were determined. Using modern antiproton-nucleus optical potentials the neutron densities in the nuclear periphery were deduced. Assuming two parameter Fermi distributions (2pF) describing the proton and neutron densities the neutron rms radii were deduced for both nuclei. The difference of neutron and proton rms radii /\r_np equal to 0.16 +-(0.02)_{stat} +- (0.04)_{syst} fm for 208Pb and 0.14 +- (0.04)_{stat} +- (0.04)_{syst} fm for 209Bi were determined and the assigned systematic errors are discussed. The /\r_np values and the deduced shapes of the neutron distributions are compared with mean field model calculations.Comment: 22 pages, 8 tables, 15 figure