Evaluation of trends in derived snowfall and rainfall across Eurasia and linkages with discharge to the Arctic Ocean

To more fully understand the role of precipitation in observed increases in freshwater discharge to the Arctic Ocean, data from a new archive of bias-adjusted precipitation records for the former USSR (TD9813), along with the CRU and Willmott-Matsuura data sets, were examined for the period 1936–1999. Across the six largest Eurasian river basins, snowfall derived from TD9813 exhibits a strongly significant increase until the late 1950s and a moderately significant decrease thereafter. A strongly significant decline in derived rainfall is also noted. Spatially, snowfall increases are found primarily across north-central Eurasia, an area where the rainfall decreases are most prominent. Although no significant change is determined in Eurasian-basin snowfall over the entire 64 year period, we note that interpolation from early, uneven station networks causes an overestimation of spatial precipitation, and that the local snowfall trends determined from gridded TD9813 data are likely underestimated. Yet, numerous uncertainties in historical Arctic climate data and the sparse, irregular nature of Arctic station networks preclude a confident assessment of precipitation-discharge linkages during the period of reported discharge trends

Flux of nutrients from Russian rivers to the Arctic Ocean: Can we establish a baseline against which to judge future changes?

Climate models predict significant warming in the Arctic in the 21st century, which will impact the functioning of terrestrial and aquatic ecosystems as well as alter land‐ocean interactions in the Arctic. Because river discharge and nutrient flux integrate large‐scale processes, they should be sensitive indicators of change, but detection of future changes requires knowledge of current conditions. Our objective in this paper is to evaluate the current state of affairs with respect to estimating nutrient flux to the Arctic Ocean from Russian rivers. To this end we provide estimates of contemporary (1970s–1990s) nitrate, ammonium, and phosphate fluxes to the Arctic Ocean for 15 large Russian rivers. We rely primarily on the extensive data archives of the former Soviet Union and current Russian Federation and compare these values to other estimates and to model predictions. Large discrepancies exist among the various estimates. These uncertainties must be resolved so that the scientific community will have reliable data with which to calibrate Arctic biogeochemical models and so that we will have a baseline against which to judge future changes (either natural or anthropogenic) in the Arctic watershed

Gain spectroscopy of a type-II VECSEL chip

Using optical pump-white light probe spectroscopy the gain dynamics is investigated for a VECSEL chip which is based on a type-II heterostructure. The active region the chip consists of a GaAs/(GaIn)As/Ga(AsSb)/(GaIn)As/GaAs multiple quantum well. For this structure, a fully microscopic theory predicts a modal room temperature gain at a wavelength of 1170 nm, which is confirmed by experimental spectra. The results show a gain buildup on the type-II chip which is delayed relative to that of a type-I chip. This slower gain dynamics is attributed to a diminished cooling rate arising from reduced electron-hole scattering.Comment: 4 pages, 4 figure

Liver failure caused by prolonged state of malnutrition following bariatric surgery

Bariatric surgery is an effective tool in the treatment of patients with morbid obesity. In these case reports we describe 2 patients who developed liver failure after currently-practiced types of bariatric surgery, caused by a prolonged state of malnutrition provoked by psychiatric problems. Despite intensive guidance of a psychologist and dieticians after surgery, our patients deteriorated psychologically, resulting in a prolonged state of severe malnutrition and anorexia. Finally, a state of starvation was reached, passing a critical level of the liver capacity. Patients who present with signs of severe protein malnutrition after bariatric surgery should be closely monitored and checked for nutritional status. Specific attention should be given to patients who develop psychiatric problems post-bariatric surgery. If refeeding does not result in clinical improvement, reversal surgery should be considered in a timely manner

Distribution of emphysema in heavy smokers: Impact on pulmonary function

SummaryPurposeTo investigate impact of distribution of computed tomography (CT) emphysema on severity of airflow limitation and gas exchange impairment in current and former heavy smokers participating in a lung cancer screening trial.Materials and MethodsIn total 875 current and former heavy smokers underwent baseline low-dose CT (30mAs) in our center and spirometry and diffusion capacity testing on the same day as part of the Dutch–Belgian Lung Cancer Screening Trial (NELSON). Emphysema was quantified for 872 subjects as the number of voxels with an apparent lowered X-ray attenuation coefficient. Voxels attenuated <−950HU were categorized as representing severe emphysema (ES950), while voxels attenuated between −910HU and −950HU represented moderate emphysema (ES910). Impact of distribution on severity of pulmonary function impairment was investigated with logistic regression, adjusted for total amount of emphysema.ResultsFor ES910 an apical distribution was associated with more airflow obstruction and gas exchange impairment than a basal distribution (both p<0.01). The FEV1/FVC ratio was 1.6% (95% CI 0.42% to 2.8%) lower for apical predominance than for basal predominance, for Tlco/VA the difference was 0.12% (95% CI 0.076–0.15%). Distribution of ES950 had no impact on FEV1/FVC ratio, while an apical distribution was associated with a 0.076% (95% CI 0.038–0.11%) lower Tlco/VA (p<0.001).ConclusionIn a heavy smoking population, an apical distribution is associated with more severe gas exchange impairment than a basal distribution; for moderate emphysema it is also associated with a lower FEV1/FVC ratio. However, differences are small, and likely clinically irrelevant

Snowmass 2001: Jet Energy Flow Project

Conventional cone jet algorithms arose from heuristic considerations of LO hard scattering coupled to independent showering. These algorithms implicitly assume that the final states of individual events can be mapped onto a unique set of jets that are in turn associated with a unique set of underlying hard scattering partons. Thus each final state hadron is assigned to a unique underlying parton. The Jet Energy Flow (JEF) analysis described here does not make such assumptions. The final states of individual events are instead described in terms of flow distributions of hadronic energy. Quantities of physical interest are constructed from the energy flow distribution summed over all events. The resulting analysis is less sensitive to higher order perturbative corrections and the impact of showering and hadronization than the standard cone algorithms.Comment: REVTeX4, 13 pages, 6 figures; Contribution to the P5 Working Group on QCD and Strong Interactions at Snowmass 200