Accretion Disks Phase Transitions: 2-D or not 2-D?

We argue that the proper way to treat thin-thick accretion-disk transitions should take into account the 2-D nature of the problem. We illustrate the physical inconsistency of the 1-D vertically integrated approach by discussing a particular example of the convective transport of energy.Comment: 4 pages, 2 figure

Paravertebral Block for Post-Operative Analgesia after Breast Cancer Surgery, Effects of Adding Morphine: Double Blind, Randomised Clinical Trial

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.Introduction: Thoracic paravertebral block (PVB) block is frequently used in breast cancer surgery for postoperative pain management. Adding opioids to local anaesthetics has been shown to have beneficial effects during epidural analgesia. Our hypothesis was that adding morphine to bupivacaine for PVB would improve analgesia provided by this procedure. Methods: 60 patients (25 - 75 years) undergoing elective surgery for breast cancer were randomly assigned to one of two groups. Both groups received a single injection thoracic paravertebral block; group BAM with 20 ml 0.5% bupivacaine, epinephrine and morphine while group BA received identical block except morphine was given subcutaneously. All patients had general anaesthesia. Results: Severity of pain and nausea was low in both groups. Pain scores remained below 20/100 after the first 2 hours throughout the 72 hours of the study. There was no significant difference between the groups in pain scores, consumption of additional morphine or nausea scores. Shoulder mobility was also very good in both groups. Conclusion: Thoracic paravertebral block with bupivacaine and epinephrine was associated with good postoperative analgesic effects and low incidence of nausea and vomiting. The addition of morphine to the local anaesthetic solution in paravertebral block did not have any additional analgesic effects

Self-Organized Criticality in Compact Plasmas

Compact plasmas, that exist near black-hole candidates and in gamma ray burst sources, commonly exhibit self-organized non-linear behavior. A model that simulates the non-linear behavior of compact radiative plasmas is constructed directly from the observed luminosity and variability. The simulation shows that such plasmas self organize, and that the degree of non-linearity as well as the slope of the power density spectrum increase with compactness. The simulation is based on a cellular automaton table that includes the properties of the hot (relativistic) plasmas, and the magnitude of the energy perturbations. The plasmas cool or heat up, depending on whether they release more or less than the energy of a single perturbation. The energy release depends on the plasmas densities and temperatures, and the perturbations energy. Strong perturbations may cool the previously heated plasma through shocks and/or pair creation. New observations of some active galactic nuclei and gamma ray bursters are consistent with the simulationComment: 9 pages, 5 figures, AASTeX, Submitted to ApJ

A model of electrical resistivity beneath NE-Iceland, correlation with temperature

Short period magnetotelluric measurements (15 s–1 h) were made at 19 sites in NE-Iceland, distributed over the neovolcanic zone and the adjoining older Tertiary flood basalt areas. With model-calculations of one- and two-dimensional resistivity distributions a characteristic model was found for the lower crust and upper mantle. Beneath a thin surface layer the resistivity is 100 Ωm except within the active neovolcanic zone where it is 50 Ωm. This layer extends to a layer with low resistivity of 15 Ωm. The low-resistivity layer is about 5 km thick. The depth of its upper boundary increases from 10 km to about 20 km with increasing distance from the rift axis. The resistivity beneath the low-resistivity layer is about 100 Ωm down to at least 100 km. Comparison of field data with laboratory measurements on conductivity at high temperatures indicates that the low-resistivity layer consists of partially molten basalt at a temperature of 1,000° –1,100° C. The underlying layer very probably consists of partially molten ultramafic rocks and is presumably the uppermost part of the mantle beneath Iceland. The basaltic low-resistivity layer is interpreted as the base of the crust formed by upward movement of the basaltic melt fraction from the mantle.         ARK: https://n2t.net/ark:/88439/y021104 Permalink: https://geophysicsjournal.com/article/77 &nbsp

Boomerang returns unexpectedly

Experimental study of the anisotropy in the cosmic microwave background (CMB) is gathering momentum. The eagerly awaited Boomerang results have lived up to expectations. They provide convincing evidence in favor of the standard paradigm: the Universe is close to flat and with primordial fluctuations which are redolent of inflation. Further scrutiny reveals something even more exciting however -- two hints that there may be some unforeseen physical effects. Firstly the primary acoustic peak appears at slightly larger scales than expected. Although this may be explicable through a combination of mundane effects, we suggest it is also prudent to consider the possibility that the Universe might be marginally closed. The other hint is provided by a second peak which appears less prominent than expected. This may indicate one of a number of possibilities, including increased damping length or tilted initial conditions, but also breaking of coherence or features in the initial power spectrum. Further data should test whether the current concordance model needs only to be tweaked, or to be enhanced in some fundamental way.Comment: 11 pages, 3 figures, final version accepted by Ap

Energy Injection in GRB Afterglow Models

We extend the standard fireball model, widely used to interpret gamma-ray burst (GRB) afterglow light curves, to include energy injections, and apply the model to the afterglow light curves of GRB 990510, GRB 000301C and GRB 010222. We show that discrete energy injections can cause temporal variations in the optical light curves and present fits to the light curves of GRB 000301C as an example. A continuous injection may be required to interpret other bursts such as GRB 010222. The extended model accounts reasonably well for the observations in all bands ranging from X-rays to radio wavelengths. In some cases, the radio light curves indicate that additional model ingredients may be needed.Comment: Accepted for publication in the Astrophysical Journa

Multiple melt plumes observed at the Breioamerkurjokull ice face in the upper waters of Jokulsarlon lagoon, Iceland

Breioamerkurjokull flows from the Vatnajokull ice cap and calves into the Jokulsarlon proglacial lagoon. The lagoon is connected to the North Atlantic Ocean through a 6 m deep narrow channel. Four hydrographic surveys in spring 2012, and a 2011 4-month long temperature and salinity time series of lagoon inflow show that the lake has significantly changed since 1976. Warm saline ocean water enters each tidal cycle and descends below the maximum sampled depths. The lagoon has a surface layer of ice melt, freshwater and Atlantic derived water. Beneath 10 m depth an advective/diffusive balance is responsible for determining the temperature and salinity of the lagoon waters down to ~90 m. To maintain the observed hydrographic structure, we calculate an upwelling of deep water of ~0.2 m d−1. A survey within 30 m of Breioamerkurjokull showed that the warmest and most saline waters sampled within the lagoon below 10 m depth were adjacent to the glacier face, along with multiple interleaved warm and cold layers. A heat and salt balance model shows that submarine melting along the ice face generates multiple meltwater plumes that are mixed and diluted within 200 m of the ice face

Pi pulsation signatures at substorm onset: An analysis of the 30 September 2011 substorm event using induction magnetometer records and all-sky images obtained at the conjugate stations, Syowa in Antarctica and Husafell, Tjornes in Iceland

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月27日（火） 国立極地研究所 2階大会議