Formation mechanism of the O-induced added-row reconstruction on Ag(110): A low-temperature STM study

The formation of the O-induced added-row reconstruction on Ag(110) was studied by scanning tunneling microscopy at 190 K. At this temperature critical surface processes are slow enough to be followed on the atomic scale. Ag atoms, which are required for the formation of the reconstruction, detach from steps in a row-wise fashion, starting from kink sites. The growth rate of the added rows is constant and controlled by the detachment rate of Ag atoms from the steps. The data provide evidence for a reconstruction mechanism in which the release of the metal atoms from the steps and the formation of lateral oxygen metal bonds are independent processes

Momentum transferred to a trapped Bose-Einstein condensate by stimulated light scattering

The response of a trapped Bose-Einstein condensed gas to a density perturbation generated by a two-photon Bragg pulse is investigated by solving the time-dependent Gross-Pitaevskii equation. We calculate the total momentum imparted to the condensate as a function of both the time duration of the pulse and the frequency difference of the two laser beams. The role of the dynamic response function in characterizing the time evolution of the system is pointed out, with special emphasis to the phonon regime. Numerical simulations are compared with the predictions of local density approximation. The relevance of our results for the interpretation of current experiments is also discussed.Comment: 7 pages, 3 postscript figure

Physical properties, starspot activity, orbital obliquity, and transmission spectrum of the Qatar-2 planetary system from multi-colour photometry

We present seventeen high-precision light curves of five transits of the planet Qatar-2b, obtained from four defocussed 2m-class telescopes. Three of the transits were observed simultaneously in the SDSS griz passbands using the seven-beam GROND imager on the MPG/ESO 2.2-m telescope. A fourth was observed simultaneously in Gunn grz using the CAHA 2.2-m telescope with BUSCA, and in r using the Cassini 1.52-m telescope. Every light curve shows small anomalies due to the passage of the planetary shadow over a cool spot on the surface of the host star. We fit the light curves with the prism+gemc model to obtain the photometric parameters of the system and the position, size and contrast of each spot. We use these photometric parameters and published spectroscopic measurements to obtain the physical properties of the system to high precision, finding a larger radius and lower density for both star and planet than previously thought. By tracking the change in position of one starspot between two transit observations we measure the orbital obliquity of Qatar-2 b to be 4.3 \pm 4.5 degree, strongly indicating an alignment of the stellar spin with the orbit of the planet. We calculate the rotation period and velocity of the cool host star to be 11.4 \pm 0.5 d and 3.28 \pm 0.13 km/s at a colatitude of 74 degree. We assemble the planet's transmission spectrum over the 386-976 nm wavelength range and search for variations of the measured radius of Qatar-2 b as a function of wavelength. Our analysis highlights a possible H2/He Rayleigh scattering in the blue.Comment: 20 pages, 14 figures, to appear in Monthly Notices of the Royal Astronomical Societ

Diffusion and Atomic Hopping of N Atoms on Ru(0001) Studied by Scanning Tunneling Microscopy

The dynamic behavior of N atoms adsorbed on a Ru(0001) surface was studied by scanning tunneling microscopy. N atoms formed by dissociation of NO molecules show an initial sharp concentration profile at atomic steps. Its decay was followed as a function of time, providing a quasicontinuum diffusion constant; the activation energy is 0.94 eV and the prefactor is 2×10−2cm2s−1. The diffusion constant was determined also at equilibrium, from statistical jumps of individual N atoms in a uniform overlayer, and is found to be identical to the Fickian value

Adsorbate-adsorbate interactions from statistical analysis of STM images: N/Ru(0001)

Atomic nitrogen on Ru(0001) was prepared by dissociative chemisorption of N2 and studied by scanning tunneling microscopy (STM) at 300 K. Nitrogen occupies the hcp threefold hollow site and is imaged as a depression with a diameter of about 5 Å. Interactions between the adsorbed nitrogen atoms were obtained by statistical analysis of STM images, by extraction of the two-dimensional pair distribution function from the arrangement of the N atoms. Since the nearest-neighbor separations could be identified with atomic precision, the pair distribution function g and hence the potential of mean force Veff were obtained as a function of the discrete neighbor sites j up to the tenth nearest neighbor. A comparison with Monte Carlo calculations for balls with a hard-sphere potential provides information about the pair potential Vpair(j): The nearest-neighbor site is strongly repulsive, the second-neighbor site is weakly repulsive, and the third-neighbor site is weakly attractive. These findings rationalize the absence of island formation and of a well-ordered 2×2 phase for the N/Ru(0001) system: At temperatures ≥300 K the attractive interaction on the third-neighbor site is too weak, while at lower temperatures the diffusion barrier of 0.9 eV represents a kinetic obstacle. The fact that the range of the interaction is identical to the diameter of the N-atom features in the STM topographs is taken as evidence that the interaction is caused by substrate-mediated electronic forces

Good Sleep Quality Improves the Relationship Between Pain and Depression Among Individuals With Chronic Pain

Individuals with chronic pain often experience co-existing sleep problems and depression-related states. Chronic pain, sleep problems, and depression interrelate, and have been shown to exacerbate one another, which negatively impacts quality of life. This study explored the relationships between pain severity, pain interference, sleep quality, and depression among individuals with chronic pain. Secondly, we tested whether sleep quality may moderate the relationship between pain and depression. A cross-sectional survey was completed by 1,059 adults with non-malignant chronic pain conditions (Mage 43 years, 88% identified as women) and collected measures related to pain severity, pain interference, sleep quality and depression. Multiple regression analyses found that pain severity, pain interference and sleep quality are all significantly associated with depression. Secondly, moderated regression analyses revealed that sleep quality moderates the relationship between pain interference and depression among individuals with chronic pain such that good sleep quality attenuates the effect of pain interference on depression, and poor sleep quality amplifies the effect of pain interference on depression. These findings suggest that sleep quality may be a relevant therapeutic target for individuals with chronic pain and co-existing depression

Acute impact of a national lockdown during the COVID-19 pandemic on wellbeing outcomes among individuals with chronic pain

Changes to wellbeing in a community- based sample of 638 adults with non-malignant chronic pain were assessed during a period of mandated lockdown measures in the UK to control the COVID-19 outbreak. Participants completed an online survey pre-lockdown and were followed up during lockdown. Multivariate analysis demonstrate that decreased ability to self-manage, restricted access to healthcare and increased dependence on others were associated with negative wellbeing outcomes related to sleep, anxiety and depression. Essential but nonurgent services are required during periods of lockdown to maintain independence and self-management in order to preserve wellbeing in this population

Direct observation of mobility and interactions of oxygen molecules chemisorbed on the Ag(110) surface

The energetics of thermal motions and interactions of oxygen molecules chemisorbed on a Ag(110) surface were investigated by scanning tunneling microscopy at 60–100 K. Surface mobility is anisotropic, preferably in the [1̅10] direction with an activation energy of 0.22±0.05 eV and a preexponential factor of 1×1013±3 s−1. Along the [1̅10] direction a repulsive interaction between nearest neighbors of about 0.02 eV and an attraction of 0.04±0.01 eV between next nearest neighbors were derived. Along [001] appreciable repulsion exists between nearest neighbors, while a ''diagonal'' arrangement of molecules is associated with an attraction of 0.02±0.01 eV. The data are indicative for the operation of indirect, substrate-mediated molecule-molecule interactions

The 2021 NICE guidelines for assessment and management of chronic pain: A cross-sectional study mapping against a sample of 1,000* in the community

Objectives To characterise the prevailing pharmacological and non-pharmacological pain management strategies among adults with chronic pain, comparing these against the newly published NICE guidelines NG-193, and examine these pre-NG-193 pain management strategies in relation to pain severity, pain interference, sleep quality and mental health outcomes. Design This study was conducted using a cross-sectional online survey study design. Setting This study was conducted on a community-dwelling cohort. Participants Adults aged 18+, living in the UK, with diagnosis of chronic pain by a health care professional. Main outcome measures Primary outcomes were characterisation of the pain management strategies utilised. Secondary outcomes were related to pain severity, pain interference, sleep quality, depression and anxiety via validated self-report measures. Results Several strategies were employed by respondents to manage their chronic pain condition including physical therapy, exercise, psychological therapy and pharmacological therapy. The data also indicated a high level of joint-care planning among patients and their clinicians. Some group differences were found in relation to pain, sleep and mental health outcomes. Conclusion This study set a comparative starting baseline to which the efficacy of the NG-193 may be compared in future years. There is evidence that NICE recommendations are being followed for the management of chronic primary pain conditions; however, pharmacological use of opioid drugs is still reported by 47%. Despite the confirmed evidence in this study of small efficacy of chronic pain by pharmacological agent, the reduction in the use of pain relief medications be it over the counter medications or prescription opioids, as recommended by NG-193, may be slow to be adopted. The data suggest that more care provision is needed to meet the recommendations around pharmacological management and review

The Insulin Receptor Substrate 1 Associates With Phosphotyrosine Phosphatase Shptp2 In Liver And Muscle Of Rats.

Insulin stimulates the tyrosine kinase activity of its receptor resulting in the phosphorylation of its cytosolic substrate, insulin receptor substrate-1 (IRS-1) which, in turn, associates with proteins containing SH2 domains. It has been shown that IRS-1 associates with the tyrosine phosphatase SHPTP2 in cell cultures. While the effect of the IRS-1/SHPTP2 association on insulin signal transduction is not completely known, this association may dephosphorylate IRS-1 and may play a critical role in the mitogenic actions of insulin. However, there is no physiological demonstration of this pathway of insulin action in animal tissues. In the present study we investigated the ability of insulin to induce association between IRS-1 and SHPTP2 in liver and muscle of intact rats, by co-immunoprecipitation with anti-IRS-1 antibody and anti-SHPTP2 antibody. In both tissues there was an increase in IRS-1 association with SHPTP2 after insulin stimulation. This association occurred when IRS-1 had the highest level of tyrosine phosphorylation and the decrease in this association was more rapid than the decrease in IRS-1 phosphorylation levels. The data provide evidence against the participation of SHPTP2 in IRS-1 dephosphorylation in rat tissues, and suggest that the insulin signal transduction pathway in rat tissues is related mainly to the mitogenic effects of the hormone.311409-1