Is My Exercise Partner Similar Enough? Partner Characteristics as a Moderator of the Köhler Effect in Exergames

Objective: Recent research has shown the Köhler motivation gain effect (working at a task with a more capable partner where one's performance is indispensable to the group) leads to greater effort in partnered exercise videogame play. The purpose of this article was to examine potential moderators of the Köhler effect by exploring dissimilarities in one's partner's appearance, namely, having an older partner (compared with a same-age partner) and having a heavier-weight partner (compared with a same-weight partner). Subjects and Methods: One hundred fifty-three male and female college students completed a series of plank exercises using the “EyeToy: Kinetic™” for the PlayStation® 2 (Sony, Tokyo, Japan). Participants first completed the exercises individually and, after a rest, completed the same exercises with a virtually present partner. Exercise persistence, subjective effort, self-efficacy beliefs, enjoyment, and intentions to exercise were recorded and analyzed. Results: A significant Köhler motivation gain was observed in all partner conditions (compared with individual controls) such that participants with a partner held the plank exercises longer (P<0.001) and reported higher subjective effort (P<0.01). These results were unmoderated by partner's age and weight, with one exception: Males tended to persist longer when paired with an obese partner (P=0.08). Conclusions: These results suggest that differences in age and weight do not attenuate the Köhler effect in exergames and may even strengthen it

A quantitative analysis of grid-related systematic errors in oxidising capacity and ozone production rates in chemistry transport models

Limited resolution in chemistry transport models (CTMs) is necessarily associated with systematic errors in the calculated chemistry, due to the artificial mixing of species on the scale of the model grid (grid-averaging). Here, the errors in calculated hydroxyl radical (OH) concentrations and ozone production rates 3 are investigated quantitatively using both direct observations and model results. Photochemical steady-state models of radical chemistry are exploited in each case to examine the effect on both OH and 3 of averaging relatively long-lived precursor species, such as O3, NOx, CO, H2O, etc. over different spatial scales. Changes in modelled 3 are estimated, independently of other model errors, by calculating the systematic effect of spatial averaging on the ozone production efficiency 1, defined as the ratio of ozone molecules produced per NOx molecule destroyed. Firstly, an investigation of in-flight measurements suggests that, at least in the northern midlatitude upper-troposphere/lower stratosphere, averaging precursor species on the scale of a T42 grid (2.75° x 2.75°) leads to a 15-20% increase in OH concentrations and a 5-10% increase in 1. Secondly, results from CTM model experiments are compared at different horizontal resolutions. Low resolution experiments are found to have significantly higher [OH] and 3 compared with high resolution experiments. The extent to which these differences may be explained by the systematic error in the model chemistry associated with grid size is estimated by degrading the high resolution data onto a low resolution grid and then recalculating 1 and [OH]. The change in calculated 1 is found to be significant and can account for much of the difference in 3 between the high and low resolution experiments. The calculated change in [OH] is less than the difference in [OH] found between the experiments, although the shortfall is likely to be due to the indirect effect of the change in modelled NOx, which is not accounted for in the calculation. It is argued that systematic errors caused by limited resolution need to be considered when evaluating the relative impacts of different pollutant sources on tropospheric ozone

The Nucleon Spectral Function at Finite Temperature and the Onset of Superfluidity in Nuclear Matter

Nucleon selfenergies and spectral functions are calculated at the saturation density of symmetric nuclear matter at finite temperatures. In particular, the behaviour of these quantities at temperatures above and close to the critical temperature for the superfluid phase transition in nuclear matter is discussed. It is shown how the singularity in the thermodynamic T-matrix at the critical temperature for superfluidity (Thouless criterion) reflects in the selfenergy and correspondingly in the spectral function. The real part of the on-shell selfenergy (optical potential) shows an anomalous behaviour for momenta near the Fermi momentum and temperatures close to the critical temperature related to the pairing singularity in the imaginary part. For comparison the selfenergy derived from the K-matrix of Brueckner theory is also calculated. It is found, that there is no pairing singularity in the imaginary part of the selfenergy in this case, which is due to the neglect of hole-hole scattering in the K-matrix. From the selfenergy the spectral function and the occupation numbers for finite temperatures are calculated.Comment: LaTex, 23 pages, 21 PostScript figures included (uuencoded), uses prc.sty, aps.sty, revtex.sty, psfig.sty (last included

TRADEOFFs in climate effects through aircraft routing: forcing due to radiatively active gases

We have estimated impacts of alternative aviation routings on the radiative forcing. Changes in ozone and OH have been estimated in four Chemistry Transport Models (CTMs) participating in the TRADEOFF project. Radiative forcings due to ozone and methane have been calculated accordingly. In addition radiative forcing due to CO2 is estimated based on fuel consumption. Three alternative routing cases are investigated; one scenario assuming additional polar routes and two scenarios assuming aircraft cruising at higher (+2000 ft) and lower (−6000 ft) altitudes. Results from the base case in year 2000 are included as a reference. Taking first a steady state backward looking approach, adding the changes in the forcing from ozone, CO2 and CH4, the ranges of the models used in this work are −0.8 to −1.8 and 0.3 to 0.6 m Wm−2 in the lower (−6000 ft) and higher (+2000 ft) cruise levels, respectively. In relative terms, flying 6000ft lower reduces the forcing by 5–10% compared to the current flight pattern, whereas flying higher, while saving fuel and presumably flying time, increases the forcing by about 2–3%. Taking next a forward looking approach we have estimated the integrated forcing (m Wm−2 yr) over 20 and 100 years time horizons. The relative contributions from each of the three climate gases are somewhat different from the backward looking approach. The differences are moderate adopting 100 year time horizon, whereas under the 20 year horizon CO2 naturally becomes less important relatively. Thus the forcing agents impact climate differently on various time scales. Also, we have found significant differences between the models for ozone and methane. We conclude that we are not yet at a point where we can include non-CO2 effects of aviation in emission trading schemes. Nevertheless, the rerouting cases that have been studied here yield relatively small changes in the radiative forcing due to the radiatively active gases

Structure of boson systems beyond the mean-field

We investigate systems of identical bosons with the focus on two-body correlations. We use the hyperspherical adiabatic method and a decomposition of the wave function in two-body amplitudes. An analytic parametrization is used for the adiabatic effective radial potential. We discuss the structure of a condensate for arbitrary scattering length. Stability and time scales for various decay processes are estimated. The previously predicted Efimov-like states are found to be very narrow. We discuss the validity conditions and formal connections between the zero- and finite-range mean-field approximations, Faddeev-Yakubovskii formulation, Jastrow ansatz, and the present method. We compare numerical results from present work with mean-field calculations and discuss qualitatively the connection with measurements.Comment: 26 pages, 6 figures, submitted to J. Phys. B. Ver. 2 is 28 pages with modified figures and discussion

Rapid adaptation drives invasion of airway donor microbiota by Pseudomonas after lung transplantation.

In cystic fibrosis (CF) patients, chronic airway infection by Pseudomonas leads to progressive lung destruction ultimately requiring lung transplantation (LT). Following LT, CF-adapted Pseudomonas strains, potentially originating from the sinuses, may seed the allograft leading to infections and reduced allograft survival. We investigated whether CF-adapted Pseudomonas populations invade the donor microbiota and adapt to the non-CF allograft. We collected sequential Pseudomonas isolates and airway samples from a CF-lung transplant recipient during two years, and followed the dynamics of the microbiota and Pseudomonas populations. We show that Pseudomonas invaded the host microbiota within three days post-LT, in association with a reduction in richness and diversity. A dominant mucoid and hypermutator mutL lineage was replaced after 11 days by non-mucoid strains. Despite antibiotic therapy, Pseudomonas dominated the allograft microbiota until day 95. We observed positive selection of pre-LT variants and the appearance of novel mutations. Phenotypic adaptation resulted in increased biofilm formation and swimming motility capacities. Pseudomonas was replaced after 95 days by a microbiota dominated by Actinobacillus. In conclusion, mucoid Pseudomonas adapted to the CF-lung remained able to invade the allograft. Selection of both pre-existing non-mucoid subpopulations and of novel phenotypic traits suggests rapid adaptation of Pseudomonas to the non-CF allograft

1/N_c Corrections to the Hadronic Matrix Elements of Q_6 and Q_8 in K --> pi pi Decays

We calculate long-distance contributions to the amplitudes A(K^0 --> pi pi, I) induced by the gluon and the electroweak penguin operators Q_6 and Q_8, respectively. We use the 1/N_c expansion within the effective chiral lagrangian for pseudoscalar mesons. In addition, we adopt a modified prescription for the identification of meson momenta in the chiral loop corrections in order to achieve a consistent matching to the short-distance part. Our approach leads to an explicit classification of the loop diagrams into non-factorizable and factorizable, the scale dependence of the latter being absorbed in the low-energy coefficients of the effective theory. Along these lines we calculate the one-loop corrections to the O(p^0) term in the chiral expansion of both operators. In the numerical results, we obtain moderate corrections to B_6^(1/2) and a substantial reduction of B_8^(3/2).Comment: 32 pages, LaTeX, 8 eps figures. One reference added, to appear in Phys. Rev.

Energy scales of Lu(1-x)Yb(x)Rh2Si2 by means of thermopower investigations

We present the thermopower S(T) and the resistivity rho(T) of Lu(1-x)Yb(x)Rh2Si2 in the temperature range 3 K < T < 300 K. S(T) is found to change from two minima for dilute systems (x < 0.5) to a single large minimum in pure YbRh2Si2. A similar behavior has also been found for the magnetic contribution to the resistivity rho_mag(T). The appearance of the low-T extrema in S(T) and rho_mag(T) is attributed to the lowering of the Kondo scale with decreasing x. The evolution of the characteristic energy scales for both the Kondo effect and the crystal electric field splitting are deduced. An extrapolation allows to estimate the Kondo temperature of YbRh2Si2 to 29 K.Comment: 15 pages, 4 figures, accepted in Phys. Rev.

Momentum Distribution in Nuclear Matter and Finite Nuclei

A simple method is presented to evaluate the effects of short-range correlations on the momentum distribution of nucleons in nuclear matter within the framework of the Green's function approach. The method provides a very efficient representation of the single-particle Green's function for a correlated system. The reliability of this method is established by comparing its results to those obtained in more elaborate calculations. The sensitivity of the momentum distribution on the nucleon-nucleon interaction and the nuclear density is studied. The momentum distributions of nucleons in finite nuclei are derived from those in nuclear matter using a local-density approximation. These results are compared to those obtained directly for light nuclei like $^{16}O$.Comment: 17 pages REVTeX, 10 figures ps files adde