Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line.

Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers' size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

Glacier mass loss. Dynamic thinning of glaciers on the Southern Antarctic Peninsula.

Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry is potentially unstable. We use satellite altimetry and gravity observations to show that a major portion of the region has, since 2009, destabilized. Ice mass loss of the marine-terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of -56 ± 8 gigatons per year, constituting a major fraction of Antarctica's contribution to rising sea level. The widespread, simultaneous nature of the acceleration, in the absence of a persistent atmospheric forcing, points to an oceanic driving mechanism.

Stability of gonadorelin and triptorelin in aqueous solution.

The influence of pH, temperature, various buffer species at different concentrations, and ionic strength on the stability of gonadorelin and triptorelin in aqueous solution has been studied using stability-indicating high-performance liquid chromatographic methods. The degradation behavior of both peptides is similar. The maximum stability of both peptides was shown to be at an approximate pH of 5.0. Acetate has the most favorable effect on stability, while phosphate causes higher degradation. Varying the concentration of acetate buffer does not affect the degradation behavior of the peptides. A higher phosphate concentration in buffer solutions causes higher degradation, however. The ionic strength of buffer solutions has no significant influence on stability. Solutions of gonadorelin and triptorelin, respectively, buffered with acetate (0.1 M, pH 5.0) with 3% (w/v) mannitol as an additive show a predicted t90% of 9.0 years and 7.7 years at 20 degrees C, respectively.

[Adverse medical aspects of hypnotic therapy with temazepam]. / Verkehrsmedizinische Aspekte einer Schlafmitteltherapie unter besonderer Berücksichtigung von Temazepam.

In a double blind comparison the driving ability of 32 outpatients with disomnia was investigated in psychometrical tests and standardized trial runs in road traffic every morning after a single dose and after a 7-day therapy with 20 mg temazepam compared with 2 mg flunitrazepam. As well as standardized driving performance observation a test car was fitted with a drive-recorder which synchronically recorded and digitally registered at 1 s intervals during a 60 min run the speed, the steering wheel velocity, fore-hand-aft and lateral acceleration amongst other data. The individual optimal quotient, as a measure of the degree of efficiency of the information processed in the driver-vehicle-road system, deteriorated significantly after the single dose of flunitrazepam as opposed to temazepam. In a trial run on a well defined test course under strictly standardized conditions, the steering wheel velocity, signifying the quality of steering ability, was highly significantly increased after the single dose as well as after the 7-day treatment with flunitrazepam therefore showing a distinct deterioration of steering ability compared to the temazepam group. The number of errors in technical handling was significantly highly with flunitrazepam at both control time checks than with temazepam.