Understanding the drivers of mortality in African savannah elephants.

Populations of African savannah elephants (Loxodonta africana) have been declining due to poaching, human-elephant conflict, and habitat loss. Understanding the causes of these declines could aid in stabilizing elephant populations. We used data from the Great Elephant Census, a 19-country aerial survey of savannah elephants conducted in 2014 and 2015, to examine effects of a suite of variables on elephant mortality. Independent variables included spatially explicit measures of natural processes and human presence as well as country-level socioeconomic measures. Our dependent variable was the carcass ratio, the ratio of dead elephants to live plus dead elephants, which is an index of recent elephant mortality. Carcass ratios are inversely proportional to population growth rates of elephants over the 4 yr prior to a survey. At the scale of survey strata (n = 275, median area = 1,222 km2 ), we found strong negative associations for carcass ratios with vegetation greenness at the time of the survey, overseas development aid to the country, and distance to the nearest international border. At the scale of ecosystems (n = 42, median area = 12,085 km2 ), carcass ratios increased with drought frequency and decreased with human density and overseas development aid to the country. Both stratum- and ecosystem-scale models explained well under one-half of the variance in carcass ratios. The differences in results between scales suggest that the drivers of mortality may be scale-specific and that the corresponding solutions may vary by scale as well.

Quantum effects in intermediate-temperature dipole-dipole correlation-functions in the presence of an environment.

We study thermal dipole-dipole correlation functions and their corresponding IR spectra in the presence of an intermediate temperature bath of harmonic oscillators. Whereas for a Morse oscillator without coupling to a heat bath, the quantum level structure is displayed in the spectrum, classical calculations show a broad, smeared out spectrum. In the presence of purely Ohmic dissipation already for extremely weak relaxation rate, the classical case is recovered. Using the HEOM approach of Tanimura and Wolynes [Phys. Rev. A 43, 4131 (1991)], we show that to observe some remnants of the level structure in the spectrum for moderate damping strength as well as intermediate temperatures, the dynamics has to be non-Markovian (Ohmic dissipation with cutoff).

Production of low-Z ions in the Dresden superconducting electron ion beam source for medical particle therapy.

We report on experiments with a new superconducting electron beam ion source (EBIS-SC), the Dresden EBIS-SC, with the objective to meet the main requirements for their application in particle-therapy facilities. Synchrotrons as well as innovative accelerator concepts, such as high-gradient linacs which are driven by a large-current cyclotron (CYCLINACS) and direct drive RF linear accelerators may benefit from the advantages of EBISs in regard to their functional principle. First experimental studies of the production of low-Z ions such as H(+), H(2)(+), H(3)(+), C(4+), and C(6+) are presented. Particular attention is paid to the ion output, i.e., the number of ions per pulse and per second, respectively. Important beam parameters in this context are, among others, ion pulse shaping, pulse repetition rates, beam emittance, and ion energy spread.

Status report of the Dresden EBIS/EBIT developments.

We give an overview about latest developments and measurements with the Dresden electron beam ion source family as compact and economically working table-top sources of highly charged ions. The ion sources are potential tools for various applications such as for use in combination with accelerators in medical particle therapy, as charge breeder or ion trap injector, as ion sources for a new generation of focused ion beam devices and for applications together with time-of-flight secondary mass spectrometers.

Long-time and unitary properties of semiclassical initial value representations.

We numerically compare the semiclassical "frozen Gaussian" Herman-Kluk propagator [Chem. Phys. 91, 27 (1984)] and the "thawed Gaussian" propagator put forward recently by Baranger et al. [J. Phys. A 34, 7227 (2001)] by studying the quantum dynamics in some nonlinear one-dimensional potentials. The reasons for the lack of long-time accuracy and norm conservation in the latter method are uncovered. We amend the thawed Gaussian propagator with a global harmonic approximation for the stability of the trajectories and demonstrate that this revised propagator is a true alternative to the Herman-Kluk propagator with similar accuracy.

Intrameal hepatic-portal infusion of glucose reduces spontaneous meal size in rats.

To test whether glucose (GLC) or insulin (INS) acutely reduces spontaneous meal size, we tested the effects of remotely controlled, intrameal hepatic-portal vein infusions of GLC or INS on rats' spontaneous feeding patterns. Experiment 1 included four blocks of three test infusions and one control infusion. The test infusions in each block were 0.25, 0.5, 1.0 or 1.5 mmol GLC; 2, 4, 6, or 8 mU INS; or the four combinations with dose ratios of 1 mmol GLC/8 mU INS, respectively. Control infusions and the INS vehicle were saline infusions that were equiosmotic to the GLC infusion used in that block. Infusions (0.1 ml x 5 min) were done during the first spontaneous dark-phase meal. None of the test infusions affected meal size, meal duration or the duration of the subsequent intermeal interval. In Experiment 2, a similar design was used to test infusions of 1 mmol GLC, 2 mU INS and GLC/INS. Both GLC alone and GLC/INS reduced the size and duration of the first spontaneous dark-phase meal. The subsequent intermeal interval was unaffected, but GLC alone also increased the satiety ratio (min/g) of the meal. The size and duration of the second dark-phase meal were unaffected. INS alone did not affect any meal parameters. In Experiment 3, infusions of 1 mmol GLC and 2 mU INS were repeated during each of the first three meals of the dark phase. These infusions reduced the size and duration of each meal, as well as 6-h cumulative food intake, but did not affect any other meal parameter. These experiments demonstrate for the first time that intrameal hepatic-portal infusions of GLC or of GLC and INS is sufficient to acutely and selectively reduce spontaneous meal size in the rat. The findings are consistent with the idea that meal-contingent changes in hepatic-portal GLC concentration contribute to satiation.

Impact of the post-treatment conditions of parent silica on the silanization of n-octadecyl bonded silica packings in reversed-phase high-performance liquid chromatography.

Native mesoporous silica beads were subjected to a sequence of post-treatment procedure including hydrochloric acid treatment, calcination and subsequent rehydroxylation. The post-treated silica beads were converted into RP-18 silica by silanization with monochloro- and dimethoxy-n-octadecylsilanes, respectively. The influence of post-treatments and silanization conditions on the physico-chemical characteristics and on the chromatographic behaviour of the RP-silicas was studied. Also the changes of the pore structural parameters and the silanol group densities during the post-treatment and silanization were assessed.

Semiclassical real-time tunneling by multiple spawning of classical trajectories

We systematically extend semiclassical real-time propagation methods based on Gaussian wave packets by using the composition property of the time-dependent quantum-mechanical Green function. For the first time, in an application to the problem of barrier tunneling, a semiclassical time-domain calculation of the transmission probability exhibits good agreement with exact quantum mechanical values at energies below the barrier top. Only two insertions of unity are needed for these results in a benchmark model of reactive scattering.

Interrelations between electrical and biochemical processes in ischemic porcine livers at low temperature.

Recently it has been shown that during liver ischemia at 25 degrees C the presence of glycogen, by supporting glycolytic supply, not only retards ATP decay but also leads to a corresponding delay of the rise of the electrical impedance of the ischemic organ. A sudden rise of impedance during ischemia is supposed to indicate the closure of gap junctions. Although similar effects on energy state do exist at low temperature, the impact of glycogen on the electrical impedance under storage conditions has still to be evaluated. Therefore, in a model with protected porcine livers, we examined the intraischemic effects of a preischemic glucose and potassium feeding on impedance changes, lactate production and ATP-content at a storing temperature of 5 degrees C. Impedance was measured both in the low frequency alpha- and the higher frequency beta-dispersion range. In addition, the same parameters were determined in a group of unprotected livers. In this group all animals had received glucose and potassium orally prior to ischemia. Whereas in case of preischemic glucose feeding the rise of impedance in the range of the beta-dispersion (e.g. 5kHz) roughly coincided with the exhaustion of ATP, the corresponding impedance changes in the protected group without a glucose premedication only occurred when glycolysis had already stopped and ATP had reached basal values for some hours. In contrast, in the alpha-dispersion range the impedance changes in the latter group just began at the time when ATP became exhausted and lactate production ceased.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological investigation of the porcine liver directly following preservation with Euro-Collins, University of Wisconsin and Bretschneider's HTK solution.

In order to study perfusion effects of different liver preservation methods on liver structure, porcine livers were perfused with either Bretschneider's HTK (Histidine Tryptophane Ketoglutarat) solution, Euro-Collins (EC) solution or University of Wisconsin solution (UW) according to the respective recommended protocols. Subsequently, together with a group of unprotected livers, all organs were examined by light and electron microscopy including computer assisted morphometry. The width of the space of Disse, the continuity of endothelial cells and the ultrastructure of the hepatocytes were not impaired after cold perfusion with any of the 3 solutions. However, we found considerable differences between the groups with respect to removal of blood cells from liver sinusoids. Livers flushed according to the HTK-protocol had the lowest residual blood cell content followed by the livers of the EC- and the UW-group. Centrilobular regions of the liver lobules were generally better washed free of blood than periportal zones. Computer assisted morphometry did not reveal any significant difference between the size of hepatocytes of EC-, UW- and HTK livers. Only the hepatocytes of normothermic control livers (biopsy samples) were 10% larger than hepatocytes of cold flushed groups. None of the protective perfusion protocols showed structural signs of perfusion injury.

[Formation and degradation of triademinol after the use of triadimefon in a wheat monoculture]. / Bildung und Abbau von Triadimenol nach Anwendung von Triadimefon in einer Weizenmonokultur.

During two vegetation periods, the behaviour of the triadimefon metabolite, triadimenol, in different plant parts of winter wheat and in soil was investigated. The fungicide Bayleton DF (triadimefon + captafol) was applied at the beginning of earing. Different ratios of triadimenol-A/-B were found in individual plant parts. Triadimenol-A predominated in the two uppermost leaves, and triadimenol-B in the roots and in the soil. No residues of triadimenol were found in grain at harvest time (detection limit 0.01 mg/kg).

[Behavior of captafol residues after prolonged application in a wheat monoculture]. / Abbauverhalten von Captafol nach langjähriger Anwendung in einer Weizenmonokultur.

In a 4-year study, the behaviour of the residues of the fungicide captafol in different plant parts of winter wheat and in the soil was investigated. The fungicide Bayleton DF (captafol + triadimefon) was applied at the beginning of earing. Captafol residues clearly showed a high dependence on weather conditions in all examined aerial parts of the plant. After a 9-year application of captafol, there was no evidence of an enrichment of residues in the soil. At harvest, captafol residues in grains always were below the maximum residue limits of 0.5 mg/kg established in West Germany.

[Sonography as the basic diagnostic method in cholelithiasis]. / Sonografie jako stezejní diagnostická metoda cholelitiázy.

The author analyzes a group of 200 patients who all were indicated for operation of the gallbladder, based on ultrasonic and radiological preoperative diagnostic examinations. He draws attention to the great diagnostic accuracy of sonography, which was 96.5% in his group. Radiological methods are of equal accuracy but have a number of disadvantages. The diagnostic accuracy is enhanced by mutual combination of the two methods in controversial cases. The author concludes from his work that sonography ought to be the primary examination when disease of the gallbladder is suspected. Classical radiological methods should be a supplementary method which increases the diagnostic accuracy of biliary disease and thus reduces to a minimum incorrectly indicated surgical revisions.