Measurable Consequences of the Local Breakdown of the Concept of Temperature

Local temperature defined by a local canonical state of the respective subsystem, does not always exist in quantum many body systems. Here, we give some examples of how this breakdown of the temperature concept on small length scales might be observed in experiments: Measurements of magnetic properties of an anti-ferromagnetic spin-1 chain. We show that those magnetic properties are in fact strictly local. As a consequence their measurement reveals whether the local (reduced) state can be thermal. If it is, a temperature may be associated to the measurement results, while this would lead to inconsistencies otherwise.Comment: some comments added, results remain unchange

Molecular Beams

Contains reports on four research projects.Lincoln Laboratory, Purchase Order DDL B-00283U. S. ArmyU. S. NavyU. S. Air Force under Air Force Contract AF 19(604)-520

Quasar Jets and their Fields

Observations of jets from quasars and other types of accreting black hole are briefly summarized. The importance of beaming and $\gamma$-ray observations for understanding the origin of these jets is emphasised. It is argued that both the power source and the collimation are likely to be magnetic in origin, although the details remain controversial. Ultrarelativistic jets may be formed by the spinning hole and collimated by a hydromagnetic disc wind. Progress in understanding jets has been handicapped by our inadequate knowledge of how magnetic field really behaves under cosmic conditions. Fortunately, significant insights are coming from solar observations, numerical simulation and laboratory plasma experiments. Some possible, evolutionary ramifications are briefly discussed and it is suggested that it is the mass of the black hole relative to that of the galaxy which determines the eventual galaxy morphology.Comment: Latex. 17pages Proc Discusison Meeting on Magnetic Activity in Stars, Discs and Quasars. Ed. D. Lynden-Bell, E. R. Priest and N. O. Weiss. To appear in Phil. Trans. Roy. Soc.

Medium effects in K^+ nucleus interaction from consistent analysis of integral and differential cross sections

Self consistency in the analysis of transmission measurements for K^+ on several nuclei in the momentum range of 500-700 MeV/c is achieved with a "t_{eff}(rho)rho" potential and new results are derived for total cross sections. The imaginary part of the t_{eff} amplitude is found to increase linearly with the average nuclear density in excess of a threshold value. This phenomenological density dependence of the K^+ nucleus optical potential also gives rise to good agreement with recent measurements of differential cross sections for elastic scattering of 715 MeV/c K^+ by Li^6 and C.Comment: 11 pages, RevTeX, 2 Postscript figures, submitted Phys. Lett.

Heat transport by turbulent Rayleigh-B\'enard convection for $\Pra\ \simeq 0.8and and 3\times 10^{12} \alt \Ra\ \alt 10^{15}:Aspectratio: Aspect ratio \Gamma = 0.50$

We report experimental results for heat-transport measurements, in the form of the Nusselt number \Nu, by turbulent Rayleigh-B\'enard convection in a cylindrical sample of aspect ratio $\Gamma \equiv D/L = 0.50$ ($D = 1.12$ m is the diameter and $L = 2.24$ m the height). The measurements were made using sulfur hexafluoride at pressures up to 19 bars as the fluid. They are for the Rayleigh-number range 3\times 10^{12} \alt \Ra \alt 10^{15} and for Prandtl numbers \Pra\ between 0.79 and 0.86. For \Ra < \Ra^*_1 \simeq 1.4\times 10^{13} we find \Nu = N_0 \Ra^{\gamma_{eff}} with $\gamma_{eff} = 0.312 \pm 0.002$, consistent with classical turbulent Rayleigh-B\'enard convection in a system with laminar boundary layers below the top and above the bottom plate. For \Ra^*_1 < \Ra < \Ra^*_2 (with \Ra^*_2 \simeq 5\times 10^{14}) $\gamma_{eff}$ gradually increases up to $0.37\pm 0.01$. We argue that above \Ra^*_2 the system is in the ultimate state of convection where the boundary layers, both thermal and kinetic, are also turbulent. Several previous measurements for $\Gamma = 0.50$ are re-examined and compared with the present results.Comment: 44 pages, 18 figures, submitted to NJ

Validity and Reliability of the Perceived Readiness for Discharge After Birth Scale

Objective: To assess the psychometric properties of a scale measuring mothers’ perceptions of readiness for discharge after birth. Design: Psychometric analyses including construct validity using factor analysis and known groups comparisons, predictive validity, and reliability. Data were collected at discharge and 6 weeks postdischarge. Setting: Tertiary-level perinatal center in the Midwestern United States. Participants: 1,462 postpartum mothers. Intervention: None. Main Outcome Measures: Perceived Readiness for Discharge After Birth Scale scores; subscale scores for personal status and knowledge factors.\u27 Results: Exploratory and confirmatory factor analyses indicated that the scale contained two factors. Perceived Readiness for Discharge After Birth Scale scores were lower for mothers who were breast-feeding, married, primiparous, and had a short hospital stay (less than 30 hours) than for their comparison groups. The Perceived Readiness for Discharge After Birth Scale personal status factor was predictive of self-reported physical and psychosocial problems and unscheduled utilization of health services in the first 6 weeks postpartum. The knowledge factor was predictive of postdischarge telephone calls to the pediatric provider. Reliability estimates ranged from 0.83 to 0.89 for the total scale and subscales. Conclusions: The Perceived Readiness for Discharge After Birth Scale performed well in psychometric testing. Assessing mothers’perceptions of readiness for discharge is important for measuring outcomes of hospitalization and for identifying mothers at risk for postdischarge problems

On the quantum description of Einstein's Brownian motion

A fully quantum treatment of Einstein's Brownian motion is given, showing in particular the role played by the two original requirements of translational invariance and connection between dynamics of the Brownian particle and atomic nature of the medium. The former leads to a clearcut relationship with Holevo's result on translation-covariant quantum-dynamical semigroups, the latter to a formulation of the fluctuation-dissipation theorem in terms of the dynamic structure factor, a two-point correlation function introduced in seminal work by van Hove, directly related to density fluctuations in the medium and therefore to its atomistic, discrete nature. A microphysical expression for the generally temperature dependent friction coefficient is given in terms of the dynamic structure factor and of the interaction potential describing the single collisions. A comparison with the Caldeira Leggett model is drawn, especially in view of the requirement of translational invariance, further characterizing general structures of reduced dynamics arising in the presence of symmetry under translations.Comment: 14 pages, latex, no figure

The seasonal cycle of ocean-atmosphere CO2 Flux in Ryder Bay, West Antarctic Peninsula

Approximately 15 million km2 of the Southern Ocean is seasonally ice covered, yet the processes affecting carbon cycling and gas exchange in this climatically important region remain inadequately understood. Here, 3 years of dissolved inorganic carbon (DIC) measurements and carbon dioxide (CO2) fluxes from Ryder Bay on the west Antarctic Peninsula (WAP) are presented. During spring and summer, primary production in the surface ocean promotes atmospheric CO2 uptake. In winter, higher DIC, caused by net heterotrophy and vertical mixing with Circumpolar Deep Water, results in outgassing of CO2 from the ocean. Ryder Bay is found to be a net sink of atmospheric CO2 of 0.59–0.94 mol C m−2 yr−1 (average of 3 years). Seasonal sea ice cover increases the net annual CO2 uptake, but its effect on gas exchange remains poorly constrained. A reduction in sea ice on the WAP shelf may reduce the strength of the oceanic CO2 sink in this region

Instantons and fermion condensate in adjoint QCD_2

We show that $QCD_2$ with adjoint fermions involves instantons due to nontrivial $\pi_1[SU(N)/Z_N]~=~Z_N$. At high temperatures, quasiclassical approximation works and the action and the form of effective (with account of quantum corrections) instanton solution can be evaluated. Instanton presents a localized configuration with the size $\propto g^{-1}$. At $N=2$, it involves exactly 2 zero fermion modes and gives rise to fermion condensate $_T$ which falls off $\propto \exp\{-\pi^{3/2} T/g\}$ at high $T$ but remains finite. At low temperatures, both instanton and bosonization arguments also exhibit the appearance of fermion condensate $_{T=0} ~\sim ~g$. For $N>2$, the situation is paradoxical. There are $2(N-1)$ fermion zero modes in the instanton background which implies the absence of the condensate in the massless limit. From the other hand, bosonization arguments suggest the appearance of the condensate for any $N$. Possible ways to resolve this paradox (which occurs also in some 4-dim gauge theories) are discussed.Comment: TPI-MINN-94/6-T. 37 p., 3 fig. Fig.3 and discussion around it are rectified. Bibliography update

Galaxy Evolution and Star Formation Efficiency at 0.2 < z < 0.6

We present the results of a CO line survey of 30 galaxies at moderate redshift (z \sim 0.2-0.6), with the IRAM 30m telescope, with the goal to follow galaxy evolution and in particular the star formation efficiency (SFE) as defined by the ratio between far-infrared luminosity and molecular gas mass (LFIR/M(H2)). The sources are selected to be ultra-luminous infrared galaxies (ULIRGs), with LFIR larger than 2.8 10^{12} Lsol, experiencing starbursts; adopting a low ULIRG CO-to-H2 conversion factor, their gas consumption time-scale is lower than 10^8 yr. To date only very few CO observations exist in this redshift range that spans nearly 25% of the universe's age. Considerable evolution of the star formation rate is already observed during this period. 18 galaxies out of our sample of 30 are detected (of which 16 are new detections), corresponding to a detection rate of 60%. The average CO luminosity for the 18 galaxies detected is L'CO = 2 10^{10} K km/s pc^2, corresponding to an average H2 mass of 1.6 10^{10} Msol. The FIR luminosity correlates well with the CO luminosity, in agreement with the correlation found for low and high redshift ULIRGs. Although the conversion factor between CO luminosity and H2 mass is uncertain, we find that the maximum amount of gas available for a single galaxy is quickly increasing as a function of redshift. Using the same conversion factor, the SFEs for z\sim 0.2-0.6 ULIRGs are found to be significantly higher, by a factor 3, than for local ULIRGs, and are comparable to high redshift ones. We compare this evolution to the expected cosmic H2 abundance and the cosmic star formation history.Comment: 11 pages, 13 figures, accepted in A&