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Two species of galagos (G. senegalensis moholi andG. garnettii) were subjected to dehydration and starvation stress in order to determine whether, as is common in other animals, these hypometabolic prosimians would lower their metabolic rate even further. Dehydration was confirmed by losses in body mass, a decrease in fecal water content and a rise in urine osmolality. At the height of dehydration, 20 to 25% reduction in body mass, 30 to 40% reduction in fecal water content and urine osmolality ranging from 1.8 to 3.5 Osmol kg−1 H2O, were recorded in some of the animals. Basal metabolic rate of 0.536 ml O2 (g·h)−1 inG. s. moholi and 0.302 ml O2 (g·h)−1 inG. garnettii were recorded, representing 50 to 42% reduction in metabolic rate, respectively, compared with mass specific values. In none of the tested animals did we observe significant reduction in basal metabolism during dehydration/starvation stress compared with the rates observed during the control period. Basal metabolism in the bushbabies seems to have reached the lowest level and no further adjustment is apparently possible as a strategy for energy saving during starvation and/or dehydration stress.

The sawtooth oscillations in tokamak discharges with Ohmic and neutral-beam heating could be suppressed when a large part of the plasma current was driven by lower-hybrid waves (I/sub HF//I/sub p/approx. =0.5). The stabilization is due to a flattening of the current profile j(r) and an increase of q(0) above 1. Higher central electron temperatures are obtained with neutral-beam heating if the sawteeth are stabilized. The increase in total energy content in this case was 30% higher than in the presence of sawteeth.

Neutral beam (NI), ion cyclotron resonance (ICRH) and lower hybrid resonance (LHRH) heating on ASDEX are discussed with regard to their effect on plasma confinement. Comparison of NI and ICRH shows that the L and H-regimes are universal confinement modes of auxiliary-heated tokamak plasmas (i.e. independent of the heating method), and that the edge electron temperature (or a related parameter) dictates which mode prevails. In this connection it is noted that carbonization of the vessel walls impedes transition to the H-mode in the case of NI heating. Studies of energy confinement in the intermediate regime from ohmic to NI heating reveal a gradual transition from ohmic ( approximately ne) to neutral injection L-mode ( approximately I) scaling. At the same time a remarkable invariance of electron temperature profile shape with increasing heating power is observed. Changing the NI power deposition profiles from central to off-axis leaves gross energy confinement times unchanged while central confinement is substantially improved.

Strongly peaked electron density profiles have been obtained in ASDEX by different refuelling methods: pellet fuelling (ohmic and co-injection heating), NBI counter-injection and recently by reduced gas puff fuelling scenarios. These discharges show in common increased density limits, a canonical electron temperature profile independent of the density profile and an improvement of the particle and energy confinement. Whereas the changes in particle transport are not fully understood, transport analyses point out that the improved energy transport can be explained by reduced ion conduction losses coming close to the neoclassical ones. The different results for the ion transport with flat and peaked density profiles are quantitatively consistent with that expected from eta i-driven modes. The analyses cannot yet explain the anomalous electron energy transport, apart from identified continuous trends such as inverse scaling with the isotope mass and enhancement with heating power.

Counter injection into ASDEX leads to good particle, momentum, and also energy confinement with ${\ensuremath{\tau}}_{E}$=80 ms at 1 MW (43 ms for co-injection). The improved confinement develops gradually during the heating phase and correlates with a simultaneous peaking of the density profile. The ion heat transport has to be reduced for a consistent transport analysis, in agreement with theoretical expectations. The sawtooth instability flattens the density profile and transiently reduces the energy content.

This letter reports on two experiments undertaken to evaluate the retention of gaseous and target produced impurities in the ASDEX divertor. The retention for gaseous impurities was determined by puffing Ar into the main chamber and simulating the time behaviour of the Ar XVI line intensity with a time dependent impurity transport code including a simple divertor model. During Ohmic heating a factor of 3 and 4.5 enhancement of impurity retention if found relative to the vacuum time constant (90 ms) of the divertor chamber, for ne = 2 × 1013 cm−3 and ne = 3.5 × 1013 cm−3, respectively, while a drastic breakdown of the retention occurs during high power NI heating. – To deduce the retention of impurities generated at the divertor plates, a segment (3.5%) of the plates was covered with copper, a metal previously not used in ASDEX. By measuring the Cu influx at the target plates and the line intensity of the Cu XX line (11.38 A) in the core plasma and by using the transport code, it is found that during NI heating (ne ≤ 2 × 1013 cm−3) Cu atoms originating from the target plates have a ≤ 3.5 times higher probability to penetrate into the core plasma than if they had when originating from the main chamber walls.

Theoretical models of type I and type II supernova explosions are reviewed from a computational physics point of view. After discussing briefly the underlying physics the numerical problems and challenges encountered in the simulation of type I and type II supernova are addressed.

A large fraction of core-collapse supernovae (CCSNe), 30-50%, are expected to originate from the low-mass end of progenitors with $M_{\rm ZAMS}~= 8-12~M_\odot$. However, degeneracy effects make stellar evolution modelling of such stars challenging, and few predictions for their supernova light curves and spectra have been presented. Here we calculate synthetic nebular spectra of a 9 $M_\odot$ Fe CCSN model exploded with the neutrino mechanism. The model predicts emission lines with FWHM$\sim$1000 km/s, including signatures from each deep layer in the metal core. We compare this model to observations of the three subluminous IIP SNe with published nebular spectra; SN 1997D, SN 2005cs, and SN 2008bk. The prediction of both line profiles and luminosities are in good agreement with SN 1997D and SN 2008bk. The close fit of a model with no tuning parameters provides strong evidence for an association of these objects with low-mass Fe CCSNe. For SN 2005cs, the interpretation is less clear, as the observational coverage ended before key diagnostic lines from the core had emerged. We perform a parameterised study of the amount of explosively made stable nickel, and find that none of these three SNe show the high $^{58}$Ni/$^{56}$Ni ratio predicted by current models of electron capture SNe (ECSNe) and ECSN-like explosions. Combined with clear detection of lines from O and He shell material, these SNe rather originate from Fe core progenitors. We argue that the outcome of self-consistent explosion simulations of low-mass stars, which gives fits to many key observables, strongly suggests that the class of subluminous Type IIP SNe is the observational counterpart of the lowest mass CCSNe., Resubmitted to MNRAS after referee comments

Supernovae of type II, i.e. explosions of stars which show strong Balmer lines of hydrogen in their spectra, are now generally believed to originate from massive stars, M ≳ 8M ⊙, where M ⊙ ≃ 2 1033g is the mass of the sun, at the end of their quiet hydrostatic evolution. If this interpretation is correct they cannot be powered directly by thermonuclear burning and they have to get their energy, at least partially, from another source. It is therefore intriguing to relate the type II phenomenon to the formation of neutron stars, an idea that goes back to Baade and Zwicky (1934) and is supported by the fact that several supernova remnants, including the Crab Nebula, do indeed contain neutron stars. In this picture the energy observed in the explosion must ultimately come from the gain in gravitational binding of the iron core of the star and/or from the binding energy of the newly born neutron star.

The unsaturated linear rise of the energy confinement time with density, tau/sub E/approx.n-bar/sub e/, up to the density limit is recovered in Ohmically heated, discharges in ASDEX. Improvement of a factor of 2 is reached with tau/sub E/approx. =150 ms at n-bar/sub e/ = 5 x 10/sup 13/ cm/sup -3/. The improved state is characterized by peaked density profiles. The ion heat diffusivity decreases to the neoclassical value. The parameter eta/sub i/ = L/sub =//L/sub =/, governing the onset of ion-temperature-gradient modes, falls to the stability threshold. The improvement in confinement might therefore be attributed to the stabilization of eta/sub i/ modes.

Recharging of the Ohmic-heating transformer of a tokamak by means of lower-hybrid waves is demonstrated experimentally in ASDEX. The results are analyzed on the basis of a simple transformer circuit. A recharging efficiency is defined and found to depend on rf power, plasma density, and plasma resistivity modified by the applied rf power. Up to now, we achieved in our recharging experiments in ASDEX a flux swing of FI${\ifmmode \dot{}\else \.{}\fi{}}_{\mathrm{OH}\mathrm{Mdt}=0.24}$ V sec, at an rf power of ${P}_{\mathrm{RF}}$=690 kW, with a pulse duration of 1 sec, while maintaining a plasma with n${\ifmmode\bar\else\textasciimacron\fi{}}_{e}$=4\ifmmode\times\else\texttimes\fi{}${10}^{12}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and ${I}_{p}$=290 kA.

Using a recently developed method (Erlguchl and Muller, 1985a) two kind of problems involving axisymmetric, differentially rotating degenerate configurations are investigated: (I) Equilibrium models of rotating polytropes are used to estimate the properties of the degenerate core of a massive star M>8M⊙ at the endpoint of its collapse without performing a detailed collapse calculation. Our analysis shows (Erlguchl and Muller, 1985b) that a rotating stellar core will not collapse all the way to neutron star densities on a dynamical time-scale, if Its initial ratio of rotational to gravitational energy βl is larger than some minimum value: βmin=0.01, 0.03, and 0.08 for y=1.30, 1.25, and 1.20, respectively. Instead the collapse is stopped due to rotation at an intermediate, dynamically stable, axisymmetric equilibrium state. The further evolution will proceed on a secular time-scale. (II) Rotating, completely catalyzed, zero-temperature Newtonian configurations with central densities in the range 107gcm−3

Tre of the suricates exhibits a marked diurnal rhythm (mean Tre at night 36.3 +/- 0.6 degrees C and 38.3 +/- 0.5 degrees C during the day). Oxygen consumption is lowest at Ta 30-32.5 degrees C (mean 0.365 +/- 0.022 ml O2 g-1 hr-1); this is 42% below the value expected from body mass. At Ta below the TNZ, oxygen uptake rises rapidly, minimal thermal conductance (0.040 ml O2 g-1 h-1 degrees C-1) being 18% above the mass-specific level. Lowest heart rates occur at Ta 30 degrees C (mean 109.6 +/- 9.8 beats min-1) and oxygen pulse is minimal at Ta 30-35 degrees C with 40-45 microliter O2 beat-1. At Ta 15-32.5 degrees C total evaporative water loss is between 0.46-0.63 ml H2O kg-1 hr-1 and increases markedly during heat stress (to a mean of 5.35 ml H2O kg-1 hr-1 at Ta 40 degrees C). This rise of TEWL is mainly attributable to the onset of panting at Ta above 35 degrees C.

Lower hybrid current drive can be applied in a tokamak in a number of different schemes, namely for start-up of the discharge, for plasma current ramp-up, for driving a stationary plasma current or for recharging the Ohmic heating transformer in a quasistationary tokamak operation. Recent experimental work related to these topics can be found in Refs. /1–10/. In this paper we report experiments performed in ASDEX.

We have performed high-resolution three-dimensional simulations of relativistic jets with beam-flow Lorentz factors of up to 7, a spatial resolution of 8 cells per beam radius, and up to 75 normalized time units in order to study the morphology and dynamics of three-dimensional relativistic jets. Our simulations show that the coherent fast backflows found in axisymmetric models are not present in three-dimensional models. We further find that when the jet is exposed to nonaxisymmetric perturbations, (1) it does not display the strong perturbations found for three-dimensional classical hydrodynamic and MHD jets (at least during the period of time covered by our simulations) and (2) it does propagate according to the one-dimensional estimate. Small three-dimensional effects in the relativistic beam give rise to a lumpy distribution of apparent speeds like that observed in M87. The beam is surrounded by a boundary layer of high specific internal energy. The properties of this layer are briefly discussed.

To investigate the inner regions of protoplanetary disks, we performed near-infrared interferometric observations of the classical TTauri binary system S CrA. We present the first VLTI-GRAVITY high spectral resolution ($R\sim$4000) observations of a classical TTauri binary, S CrA (composed of S CrA N and S CrA S and separated by $\sim$1.4"), combining the four 8-m telescopes in dual-field mode. Our observations in the near-infrared K-band continuum reveal a disk around each binary component, with similar half-flux radii of about 0.1 au at d$\sim$130 pc, inclinations ($i=$28$\pm$3$^o$\ and $i=$22$\pm$6$^o$), and position angles (PA=0$^o\pm$6$^o$ and PA=-2$^o\pm$12$^o$), suggesting that they formed from the fragmentation of a common disk. The S CrA N spectrum shows bright HeI and Br$\gamma$ line emission exhibiting inverse P-Cygni profiles, typically associated with infalling gas. The continuum-compensated Br$\gamma$ line visibilities of S CrA N show the presence of a compact Br$\gamma$ emitting region the radius of which is about $\sim$0.06 au, which is twice as big as the truncation radius. This component is mostly tracing a wind. Moreover, a slight radius change between the blue- and red-shifted Br$\gamma$ line components is marginally detected. The presence of an inverse P-Cygni profile in the HeI and Br$\gamma$ lines, along with the tentative detection of a slightly larger size of the blue-shifted Br$\gamma$ line component, hint at the simultaneous presence of a wind and magnetospheric accretion in S CrA N., Comment: Accepted by A&A