Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas

We study analytically and numerically the one-dimensional quantum Frenkel-Kontorova chain in the regime when the classical model is located in the pinned phase characterized by the gaped phonon excitations and devil's staircase. By extensive quantum Monte Carlo simulations we show that for the effective Planck constant $\hbar$ smaller than the critical value $\hbar_c$ the quantum chain is in the pinned instanton glass phase. In this phase the elementary excitations have two branches: phonons, separated from zero energy by a finite gap, and instantons which have an exponentially small excitation energy. At $\hbar=\hbar_c$ the quantum phase transition takes place and for $\hbar>\hbar_c$ the pinned instanton glass is transformed into the sliding phonon gas with gapless phonon excitations. This transition is accompanied by the divergence of the spatial correlation length and appearence of sliding modes at $\hbar>\hbar_c$.Comment: revtex 16 pages, 18 figure

Hydrological (in)stability in Southern Siberia during the Younger Dryas and early Holocene

Southern Siberia is currently undergoing rapid warming, inducing changes in vegetation, loss of permafrost, and impacts on the hydrodynamics of lakes and rivers. Lake sediments are key archives of environmental change and contain a record of ecosystem variability, as well as providing proxy indicators of wider environmental and climatic change. Investigating how hydrological systems have responded to past shifts in climate can provide essential context for better understanding future ecosystem changes in Siberia. Oxygen isotope ratios within lacustrine records provide fundamental information on past variability in hydrological systems. Here we present a new oxygen isotope record from diatom silica (ẟ18Odiatom) at Lake Baunt (55°11′15″N, 113°01,45″E), in the southern part of eastern Siberia, and consider how the site has responded to climate changes between the Younger Dryas and Early to Mid Holocene (ca. 12.4 to 6.2 ka cal BP). Excursions in ẟ18Odiatom are influenced by air temperature and the seasonality, quantity, and source of atmospheric precipitation. These variables are a function of the strength of the Siberian High, which controls temperature, the proportion and quantity of winter versus summer precipitation, and the relative dominance of Atlantic versus Pacific air masses. A regional comparison with other Siberian ẟ18Odiatom records, from lakes Baikal and Kotokel, suggests that ẟ18Odiatom variations in southern Siberia reflect increased continentality during the Younger Dryas, delayed Early Holocene warming in the region, and substantial climate instability between ~10.5 to ~8.2 ka cal BP. Unstable conditions during the Early Holocene thermal optimum most likely reflect localised changes from glacial melting. Taking the profiles from three very different lakes together, highlight the influence of site specific factors on the individual records, and how one site is not indicative of the region as a whole. Overall, the study documents how sensitive this important region is to both internal and external forcing

High Precision Mass Measurements in Ψ\Psi and Υ\Upsilon Families Revisited

High precision mass measurements in $\Psi$ and $\Upsilon$ families performed in 1980-1984 at the VEPP-4 collider with OLYA and MD-1 detectors are revisited. The corrections for the new value of the electron mass are presented. The effect of the updated radiative corrections has been calculated for the $J/\Psi(1S)$ and $\Psi(2S)$ mass measurements.Comment: 5 pages, 1 table, submitted to Phys. Lett.

Oxygen isotope composition of diatoms from sediments of Lake Kotokel (Buryatia).

This is a summary of new oxygen isotope data for diatoms from Lake Kotokel sediments, with implications for responses of the lake system and its environment to global change over the past 46 kyr. Fossil diatoms in all samples are free from visible contamination signatures and contain no more than 2.5% Al2O3, which ensures reliable reconstructions. The δ18O values in diatoms vary between +23.7 and +31.2‰ over the record. The results mainly represent diatom assemblages of summer blooming periods, except for the time span between 36 and 32 kyr, when the isotopic signal rather records a shift from summer to spring blooming conditions. Possible water temperature changes only partly explain the changes in the isotopic record. The observed isotopic patterns are produced mainly by isotope changes in lake water in response to variations in air temperature, hydrology, and atmospheric circulation in the region. During Marine Isotope Stage (MIS) 2 (Last Glacial maximum), high δ18Odiatom resulted from rapid evaporation and low fluvial inputs. The high δ18O values of about +29 to +30‰ during the first half of MIS 1 (Holocene interglacial) suggest an increased share of summer rainfalls associated with southern/southeastern air transport. The δ18O decrease to +24‰ during the second half of MIS 1 is due to the overall hemispheric cooling and increased moisture supply to the area by the Atlantic transport. The record of Lake Kotokel sediments provides an example of complex interplay among several climatic controls of δ18Odiatom in the Late Pleistocene and the Holocene

New precision measurement of the J/ψJ/\psi- and ψ′\psi' -meson masses

A new high precision measurement of the $J/\psi$- and $\psi'$-meson masses has been performed at the VEPP-4M collider using the KEDR detector. The resonant depolarization method has been employed for the absolute calibration of the beam energy. The following mass values have been obtained: $M_{J/\psi} = 3096.917 \pm 0.010 \pm 0.007$ MeV, $M_{\psi'} = 3686.111 \pm 0.025 \pm 0.009$ MeV. The relative measurement accuracy has reached $4. 10^{-6}$ for $J/\psi$ and $7. 10^{-6}$ for $\psi'$, approximately 3 times better than in the previous precise experiments.Comment: 12 pages, 4 tables, 10 figure

Relation of cell mediated immunity in women with genital tract cancer to origin, histology, clinical stage and subsequent behaviour of neoplasm

A quantitative study of cell‐mediated immunological reactivity was made in patients with female genital tract cancer. Prinary reactivity was measured by contact sensitization to dinitrochlorobenzene (DNCB) and secondary reactivity by delayed cutaneous hypersensitivity to skin test antigens (STA). In general, there was an increased incidence of anergic and impaired reactivity in patients with cancer of the cervix, corpus uteri or ovary, compared with age‐matched controls; however, differences between patient‐groups, regarding organ or origin or histological type, were small and insignificant. There was a progressive increase in incidence of anergic and impaired reactivity with worsening of clinical staging of the tumour. Significant differences in reactivity were noted between patients who had remained free of disease and those who had progressive disease after 12 months of follow‐up. It is considered that impairment of cell‐mediated immunity is an unfavourable factor in host‐tumour interactions, and the possibility of augmenting immunological reactivity should be considered in management. Copyrigh

Cigarette smoking by pregnant women with particular reference to their past and subsequent breast feeding behaviour

Summary: 1,790 postpartum women were asked about their smoking habits and baby feeding practices and about a number of other attitudes and physical attributes. For those variables not concerned with baby feeding, our findings generally support previous research; for example, smokers in comparison to non‐smokers tended to have more emotional problems, more reproductive failures and babies with lower birth‐weights. For baby feeding, we found that smokers tended to (i) have little prior knowledge of breast feeding, (ii) favour bottle feeding, (iii) have been fed by bottle by their mothers, and (iv) wean earlier than non‐smokers or ex‐smokers. In fact, non‐smokers as a group were similar to breast feeders as a group, and smokers like bottle feeders for over 20 characteristics. These similarities were mostly the result of features of smoking and baby feeding behaviour being found in a common personality type; for example, use of tobacco and choice of bottle feeding are probably attributes of nervous, insecure mothers. But some similarities were the result of the influence of tobacco smoke; for example smokers who do breast feed wean earlier, probably because chemicals in tobacco smoke inhibit milk production