The puzzle of 90 degree reorientation in the vortex lattice of borocarbide superconductors

We explain 90 degree reorientation in the vortex lattice of borocarbide superconductors on the basis of a phenomenological extension of the nonlocal London model that takes full account of the symmetry of the system. We propose microscopic mechanisms that could generate the correction terms and point out the important role of the superconducting gap anisotropy.Comment: 4 pages, 2 eps figure

Influence of nonlocal electrodynamics on the anisotropic vortex pinning in YNi2B2CYNi_2B_2C

We have studied the pinning force density Fp of YNi_2B_2C superconductors for various field orientations. We observe anisotropies both between the c-axis and the basal plane and within the plane, that cannot be explained by usual mass anisotropy. For magnetic field $H \parallel c$, the reorientation structural transition in the vortex lattice due to nonlocality, which occurs at a field $H_1 \sim 1kOe$, manifests itself as a kink in Fp(H). When $H \bot c$, Fp is much larger and has a quite different H dependence, indicating that other pinning mechanisms are present. In this case the signature of nonlocal effects is the presence of a fourfold periodicity of Fp within the basal plane.Comment: 4 pages, 3 figure

Tunneling spectroscopy in the magnetic superconductor TmNi2B2C

We present new measurements about the tunneling conductance in the borocarbide superconductor TmNi$_2$B$_2$C. The results show a very good agreement with weak coupling BCS theory, without any lifetime broadening parameter, over the whole sample surface. We detect no particular change of the tunneling spectroscopy below 1.5K, when both the antiferromagnetic (AF) phase and the superconducting order coexist.Comment: Submitted to Phys. Rev. B, Rapid Communication

Heat Transport and the Nature of the Order Parameter in Superconducting UPt3UPt_3

Recent thermal conductivity data on the heavy fermion superconductor $UPt_3$ have been interpreted as offering support for an $E_{2u}$ model of the order parameter as opposed to an $E_{1g}$ model. In this paper, we analyze this issue from a theoretical standpoint including the detailed effects of Fermi surface and gap anisotropy. Our conclusion is that although current data put strong constraints on the gap anisotropy, they cannot definitively distinguish between these two models. Measurements on samples of varying quality could be decisive in this regard, however.Comment: 8 pages, revtex, 15 uunencoded postscript figure

Ginzburg-Landau theory of vortices in a multi-gap superconductor

The Ginzburg-Landau functional for a two-gap superconductor is derived within the weak-coupling BCS model. The two-gap Ginzburg-Landau theory is, then, applied to investigate various magnetic properties of MgB2 including an upturn temperature dependence of the transverse upper critical field and a core structure of an isolated vortex. Orientation of vortex lattice relative to crystallographic axes is studied for magnetic fields parallel to the c-axis. A peculiar 30-degree rotation of the vortex lattice with increasing strength of an applied field observed by neutron scattering is attributed to the multi-gap nature of superconductivity in MgB2.Comment: 11 page

Complex relationships among personality traits, job characteristics, and work behaviors

The aim of the study was to investigate the additive, mediating, and moderating effects of personality traits and job characteristics on work behaviors. Job applicants (N = 161) completed personality questionnaires measuring extraversion, neuroticism, achievement motivation, and experience seeking. One and a half years later, supervisors rated the applicants' job performance, and the job incumbents completed questionnaires about skill variety, autonomy, and feedback, work stress, job satisfaction, work self-efficacy, and propensity to leave. LISREL was used to test 15 hypotheses. Perceived feedback mediated the relationship between achievement motivation and job performance. Extraversion predicted work self-efficacy and job satisfaction. Work stress mediated the relationship between neuroticism and job satisfaction. Job satisfaction and experience seeking were related to propensity to leave. Autonomy, skill variety, and feedback were related to job satisfaction

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307

Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

The yield of charged particles associated with high-$p_{\rm T}$ trigger particles ($8 < p_{\rm T} < 15$ GeV/$c$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jet-like correlation peaks in azimuthal di-hadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_{\rm T}> 3$ GeV/$c$ on the away-side drops to about 60% of that observed in pp collisions, while on the near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/350

Environmental baseline monitoring : Phase III final report (2017-2018)

High-quality environmental baseline monitoring data are being collected in areas around two proposed shale gas sites near Kirby Misperton, North Yorkshire and Little Plumpton Lancashire. Monitoring has now been on-going for over two years and has produced an internationally unique data set that will allow any future changes that arise from industrial activities at either or both shale gas sites to be detected and characterised, as well as providing a significant resource for future research. The monitoring includes: water quality, air quality, seismicity, ground motion, soil gas and radon in air. This report presents the results of monitoring in the Vale of Pickering, within which the Kirby Misperton shale gas site (KM8) is located, for the period April 2017–March 2018. It also includes the results of atmospheric composition measurements made near the Little Plumpton (Preston New Road) site. Earlier results and other monitoring in Lancashire are reported elsewhere and can be accessed from the British Geological Survey’s website1. As well as providing valuable insight into the importance of establishing robust information on the conditions before shale gas operations start, it also highlights the challenges in establishing effective monitoring and producing reliable results. For groundwater, this includes the importance of: developing and flushing newly installed boreholes; the spatial variation in water quality and; the selection of monitoring and measuring techniques. Having two years of data has allowed comparison between years. The preliminary analysis reported here has shown that sample populations were not significantly different between the two years. This is directly relevant to the duration of monitoring required by legislation, with the evidence supporting a baseline monitoring period of at least 12 months before any site operations start. The seismic monitoring network installed for measuring background seismicity has operated successfully throughout the reporting period. All but one station show levels of data completeness over 90% which represents a high-quality dataset. There has been no significant change in recorded noise levels at any of the stations in the network. This combined with instrument performance means the network is capable of detecting seismic events with magnitudes of 0.5 ML or less around Kirby Misperton. The monitoring has detected successfully a number of earthquakes around both the Vale of Pickering and the Fylde peninsula. However, all of these are at some distance from the shale gas sites. The Vale of Pickering network has also detected a number of other seismic events that have been attributed to quarry blasts. The magnitudes of these events range from 0.7 ML to 1.6 ML. We have also developed and applied a new magnitude scale to correct for overestimation of magnitudes at small epicentral distances. This results in a significant reduction of the magnitudes of quarry blasts in the Vale of Pickering by over 0.5 magnitude units in some cases. The variance in the magnitude estimates is also slightly reduced. This issue is critical for correct estimation of the magnitudes of any earthquakes that might be induced by hydraulic fracturing. The greenhouse gas monitoring continues to reinforce the conclusion that a baseline at one location is not applicable to other locations. However, the consistency of the baseline measurements (and baseline variability within each year) at both sites clearly suggests that 12 months of baseline monitoring is sufficient to establish a meaningful climatology to compare with analogous climatologies during the operational lifetime of the shale gas sites. Twelve months of data allow differentiation of local and long-range sources of greenhouse gases. At both sites, local (<10 km) sources dominate the contribution to statistically elevated concentration observations. We conclude that: the consistency of the baseline statistics year-to-year at each site separately, strongly validates the utility of these statistics in future comparative work; repeatability and similarity in both mean and statistical variability at each individual site across both annual periods suggests that 12 months of monitoring is sufficient to characterise the baseline at future sites usefully and; the large differences between the baselines at both sites, due to influence of local sources, demonstrate that careful thought and further work may be required to assess the spatial scale over which baselines can be usefully applicable. The baseline distribution of air pollutants measured at the Lancashire site has been broadly similar in 2017 to previous years, but there have been substantial changes observed at Kirby Misperton. There was a noticeable increase in NOx from Autumn 2017 as the site was prepared for hydraulic fracturing operations to begin. The high level of vehicle movements and operation of equipment during this period led to enhanced local NOx emissions. The equipment was removed after operations were suspended and the NOx concentrations returned to broadly the same concentrations seen previously during the baseline period. This highlights the importance of measuring the whole shale-gas operational cycle for air quality as the preparative operations can have a substantial impact on air pollution. In the Vale of Pickering, 133 households volunteered to have detectors for measuring indoor radon concentrations. The results were consistent with the usual log-normal distribution for indoor radon and reflected the locations of the monitoring with respect to whether they were in Radon Affected Areas or not, i.e. radon levels above 200 Bq/m3 were measured in homes in Malton which confirmed the PHE/BGS classification of this location as a Radon Affected Area. Outdoor radon was also measured. There is no indication of elevated outdoor radon concentrations in either the Pickering or Malton Radon Affected Areas, or elsewhere. Results from an active monitor and passive detectors, placed on the Kirby Misperton well site were in good agreement with the average outdoor radon concentrations for the area around Kirby Misperton. The active monitoring showed significant short-term variations over time. However the annual average was consistent, whichever of the techniques was used. Seasonal variability in baseline soil gas and flux values continues to be observed as well as shorter-term diurnal changes and event-driven variations, for example related to the passage of weather systems. The longer-time-series data and the preliminary geostatistical appraisal of selected data suggest that any emissions related to shale gas operations will be easiest to detect in the autumn when baseline biological activity is lower and the soil remains dry. Saturation of the ground in the winter months precludes free gas measurements. A further component of the study is to characterise ground motion (subsidence and/or uplift) in the study areas using satellite data. The objective being to determine what the current situation is, so that any changes that might be caused by hydraulic fracturing, if it takes place, can be identified. The baseline conditions have previously been reported (Ward et al, 2018) and as now hydraulic fracturing has yet taken place, no further analysis has been carried out during this reporting period