Climate modification and climate change debates amongst Soviet physical geographers, 1940s-1960s

This review provides an insight into some of the main themes characterizing the work of Soviet physical geographers concerning climate during the decade following the Second World War. Post-1945, pressure was placed upon geography via the state and the Academy of Sciences to ensure that its activities were of practical use to the development of the socialist economy and this was particularly evident in the case of work related to climate and climate modification. The review is divided into four main sections. First, it provides an understanding of the range of work carried out by physical geographers with respect to climate and related phenomena in the late 1940s and 1950s. Second, it focuses on the work of geographers and climatologists in relation to the heat and water balance at the earth's surface, which attracted considerable attention within geographical circles as well as more broadly within Soviet science during the 1950s. Third, it reflects upon the way in which Soviet geography utilized its understanding of climate systems in order to participate in national schemes concerned with the modification of the climate and the transformation of nature. Finally, the review highlights the maturing of climate modification debates among geographers and cognate scientists during the late 1950s and early 1960s with the emergence of competing discussions over the potential for human activity to result in both positive and negative consequences for the global climate system

Correlating Student Beliefs With Student Learning Using The Colorado Learning Attitudes about Science Survey

A number of instruments have been designed to probe the variety of attitudes, beliefs, expectations, and epistemological frames taught in our introductory physics courses. Using a newly developed instrument -- the Colorado Learning Attitudes about Science Survey (CLASS)[1] -- we examine the relationship between students' beliefs about physics and other educational outcomes, such as conceptual learning and student retention. We report results from surveys of over 750 students in a variety of courses, including several courses modified to promote favorable beliefs about physics. We find positive correlations between particular student beliefs and conceptual learning gains, and between student retention and favorable beliefs in select categories. We also note the influence of teaching practices on student beliefs

Exact Quantum Monte Carlo Process for the Statistics of Discrete Systems

We introduce an exact Monte Carlo approach to the statistics of discrete quantum systems which does not rely on the standard fragmentation of the imaginary time, or any small parameter. The method deals with discrete objects, kinks, representing virtual transitions at different moments of time. The global statistics of kinks is reproduced by explicit local procedures, the key one being based on the exact solution for the biased two-level system.Comment: 4 pages, latex, no figures, English translation of the paper

Ion structure factors and electron transport in dense Coulomb plasmas

The dynamical structure factor of a Coulomb crystal of ions is calculated at arbitrary temperature below the melting point taking into account multi-phonon processes in the harmonic approximation. In a strongly coupled Coulomb ion liquid, the static structure factor is split into two parts, a Bragg-diffraction-like one, describing incipient long-range order structures, and an inelastic part corresponding to thermal ion density fluctuations. It is assumed that the diffractionlike scattering does not lead to the electron relaxation in the liquid phase. This assumption, together with the inclusion of multi-phonon processes in the crystalline phase, eliminates large discontinuities of the transport coefficients (jumps of the thermal and electric conductivities, as well as shear viscosity, reported previously) at a melting point.Comment: 4 pages, 2 figures, REVTeX using epsf.sty. Phys. Rev. Lett., in pres

Generalized Second Law and phantom Cosmology: accreting black holes

The accretion of phantom fields by black holes within a thermodynamic context is addressed. For a fluid violating the dominant energy condition, case of a phantom fluid, the Euler and Gibbs relations permit two different possibilities for the entropy and temperature: a situation in which the entropy is negative and the temperature is positive or vice-versa. In the former case, if the generalized second law (GSL) is valid, then the accretion process is not allowed whereas in the latter, there is a critical black hole mass below which the accretion process occurs. In a universe dominated by a phantom field, the critical mass drops quite rapidly with the cosmic expansion and black holes are only slightly affected by accretion. All black holes disappear near the big rip, as suggested by previous investigations, if the GSL is violated.Comment: 8 pp., no figure

Lowering of the Kinetic Energy in Interacting Quantum Systems

Interactions never lower the ground state kinetic energy of a quantum system. However, at nonzero temperature, where the system occupies a thermal distribution of states, interactions can reduce the kinetic energy below the noninteracting value. This can be demonstrated from a first order weak coupling expansion. Simulations (both variational and restricted path integral Monte Carlo) of the electron gas model and dense hydrogen confirm this and show that in contrast to the ground state case, at nonzero temperature the population of low momentum states can be increased relative to the free Fermi distribution. This effect is not seen in simulations of liquid He-3.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Lett., June, 200

Exact, Complete, and Universal Continuous-Time Worldline Monte Carlo Approach to the Statistics of Discrete Quantum Systems

We show how the worldline quantum Monte Carlo procedure, which usually relies on an artificial time discretization, can be formulated directly in continuous time, rendering the scheme exact. For an arbitrary system with discrete Hilbert space, none of the configuration update procedures contain small parameters. We find that the most effective update strategy involves the motion of worldline discontinuities (both in space and time), i.e., the evaluation of the Green's function. Being based on local updates only, our method nevertheless allows one to work with the grand canonical ensemble and non-zero winding numbers, and to calculate any dynamic correlation function as easily as expectation values of, e.g., total energy. The principles found for the update in continuous time generalize to any continuous variables in the space of discrete virtual transitions, and in principle also make it possible to simulate continuous systems exactly.Comment: revtex, 14 pages, 6 figures, published version (modified and extended

Takayasu arteritis presenting as cerebral aneurysms in an 18 month old: A case report

<p>Abstract</p> <p>Background</p> <p>Central nervous system involvement occurs in as many as twenty percent of Takayasu arteritis cases. When central nervous system disease is present, it typically manifests as cerebral ischemia or stroke. There are rare reports of intracranial aneurysms in adults with Takayasu arteritis, but none in children.</p> <p>Case presentation</p> <p>We describe a case of Takayasu arteritis in an 18 month old girl who presented with a ruptured cerebral aneurysm. Full body magnetic resonance angiography revealed bilateral iliac, pelvic and intragluteal aneurysms, irregular terminal aorta, and stenotic renal arteries. Iliac vessel biopsy showed a lymphocytic infiltrate and giant cells localized to the internal elastica.</p> <p>Conclusion</p> <p>This case highlights cerebral aneurysm as a highly unusual initial manifestation of Takayasu arteritis and demonstrates the challenges of diagnosis, treatment, and assessment of response to therapy in TA in children.</p

Degenerate Bose liquid in a fluctuating gauge field

We study the effect of a strongly fluctuating gauge field on a degenerate Bose liquid, relevant to the charge degrees of freedom in doped Mott insulators. We find that the superfluidity is destroyed. The resulting metallic phase is studied using quantum Monte Carlo methods. Gauge fluctuations cause the boson world lines to retrace themselves. We examine how this world-line geometry affects the physical properties of the system. In particular, we find a transport relaxation rate of the order of 2kT, consistent with the normal state of the cuprate superconductors. We also find that the density excitations of this model resemble that of the full tJ model.Comment: 4 pages. Uses RevTeX, epsf, multicols macros. 5 postscript figure