Marginal states of the resistive tearing mode with flow in cylindrical geometry

The linear stability of tearing modes in a cylindrical plasma subject to a sub-Alfvénic equilibrium shear flow along the equilibrium magnetic field is considered. The equations in the resistive boundary layer at the rational surface are solved numerically using a Fourier transform combined with a finite-element approach. The behaviour of the growth rate as a function of the flow and the various parameters (including a perpendicular fluid viscosity) is obtained. Marginal stability curves showing the dependence of the familiar matching parameter Δ' with flow and shear are also given

Observing the very low-surface brightness dwarfs in a deep field in the VIRGO cluster: constraints on Dark Matter scenarios

We report the discovery of 11 very faint (r< 23), low surface brightness ({\mu}_r< 27 mag/arcsec^2) dwarf galaxies in one deep field in the Virgo cluster, obtained by the prime focus cameras (LBC) at the Large Binocular Telescope (LBT). These extend our previous sample to reach a total number of 27 galaxies in a field of just of 0.17 deg^2 located at a median distance of 390 kpc from the cluster center. Their association with the Virgo cluster is supported by their separate position in the central surface brightness - total magnitude plane with respect to the background galaxies of similar total magnitude. For a significant fraction (26\%) of the sample the association to the cluster is confirmed by spectroscopic follow-up. We show that the mere abundance of satellite galaxies corresponding to our observed number in the target field provides extremely tight constraints on Dark Matter models with suppressed power spectrum compared to the Cold Dark Matter case, independently of the galaxy luminosity distribution. In particular, requiring the observed number of satellite galaxies not to exceed the predicted abundance of Dark Matter sub-halos yields a limit m_X >3 keV at 1-{\sigma} and m_X > 2.3 keV at 2-{\sigma} confidence level for the mass of thermal Warm Dark Matter particles. Such a limit is competitive with other limits set by the abundance of ultra-faint satellite galaxies in the Milky Way, is completely independent of baryon physics involved in galaxy formation, and has the potentiality for appreciable improvements with next observations. We extend our analysis to Dark Matter models based on sterile neutrinos, showing that our observations set tight constraints on the combination of sterile neutrino mass m_{\nu} and mixing parameter sin^2(2{\theta}). We discuss the robustness of our results with respect to systematics.Comment: Accepted for publication in Astronomy & Astrophysic

Quantum Monte Carlo Study of an Interaction-Driven Band Insulator to Metal Transition

We study the transitions from band insulator to metal to Mott insulator in the ionic Hubbard model on a two dimensional square lattice using determinant Quantum Monte Carlo. Evaluation of the temperature dependence of the conductivity demonstrates that the metallic region extends for a finite range of interaction values. The Mott phase at strong coupling is accompanied by antiferromagnetic (AF) order. Inclusion of these intersite correlations changes the phase diagram qualitatively compared to dynamical mean field theory.Comment: 4 pages, 6 figure

Understanding Japanese consumer behaviour and cultural relevance of gift giving

This study examines the consumer in the Japanese market and the importance of gift-giving in Japanese culture as a first-order social practice. Cultural connectedness and relevance represents an area of importance for the marketing of retail products, particularly related to gift-giving. The interviewing of 25 participants was used to study the Japanese consumer and their purchase behaviours for gift-giving. The exploration of the social, cultural and economic constructs in Japan shows specific patterns found which are unique to the Japanese consumer. The emergence of new categories of consumers appearing in Japan through globalization and shifting mindsets influenced by western culture, as well as recent social and economic conditions, contribute to the evolution of the business market

A Military Chronic Pain Interdisciplinary Outpatient Program’s (IOP) Approach to Reducing Pain and Disability and Increasing Functional Ability

The present study employed self-report measures to assess pain intensity, self-report perception of disability, and patient activation, and objective functional measures to explore the outcomes of a military interdisciplinary chronic pain intensive outpatient program. Seventy-three Active Duty Service Members (SM) with chronic pain completed baseline measures (pre-IOP) and graduation day measures, 60 SMs completed one-month follow-up measures, and 28 completed three-month follow-up measures. Results indicated that self-report pain levels decreased from pre-IOP to graduation day. The decrease was maintained; however, no additional significant decrease in pain occurred following program completion. Further, participant’s self-reported perception of disability due to back pain decreased from pre-IOP to graduation day. The decrease was maintained; however, no additional significant decrease in self-report perception of disability occurred following program completion. Results also indicated a significant improvement in all functional measures from pre-IOP to graduation day: maximum plank time, sit-to-stand repetitions, push-ups performed, weighted barbell deadlift, and total number of interval aerobic run. This data was not collected at the one and three month follow-up. Additionally, the Patient Activation Measure (PAM) was utilized to measure a patient’s agency in their overall health. Results showed PAM scores increased throughout the program and at follow-up; however, the only significant difference occurred between pre-IOP and the one-month follow-up. The hypothesis that PAM scores would moderate the relationship between pre-IOP and graduation functional ability was not supported. These results support the use of interdisciplinary outpatient programs in the treatment of chronic pain in military populations

Metallic phase in the two-dimensional ionic Hubbard model

We investigate the phases of the ionic Hubbard model in a two-dimensional square lattice using determinant quantum Monte Carlo (DQMC). At half-filling, when the interaction strength or the staggered potential dominate we find Mott and band insulators, respectively. When these two energies are of the same order we find a metallic region. Charge and magnetic structure factors demonstrate the presence of antiferromagnetism only in the Mott region, although the externally imposed density modulation is present everywhere in the phase diagram. Away from half-filling, other insulating phases are found. Kinetic energy correlations do not give clear signals for the existence of a bond-ordered phase

Lenses in the forest: cross-correlation of the Lyman-alpha flux with CMB lensing

We present a theoretical estimate for a new observable: the cross-correlation between the Lyman-alpha flux fluctuations in quasar (QSO) spectra and the convergence of the cosmic microwave background (CMB) as measured along the same line-of-sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line-of-sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross-correlating QSO spectra of SDSS-III with Planck and of 20 for cross-correlating with a future polarization based CMB experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross-correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed by observations.Comment: 5 pages, 4 figures, matches published versio

The detection of ultra-faint low surface brightness dwarf galaxies in the Virgo Cluster: a Probe of Dark Matter and Baryonic Physics

We have discovered 11 ultra-faint ($r\lesssim 22.1$) low surface brightness (LSB, central surface brightness $23\lesssim \mu_r\lesssim 26$) dwarf galaxy candidates in one deep Virgo field of just $576$ arcmin$^2$ obtained by the Large Binocular Camera (LBC) at the Large Binocular Telescope (LBT). Their association with the Virgo cluster is supported by their distinct position in the central surface brightness - total magnitude plane with respect to the background galaxies of similar total magnitude. They have typical absolute magnitudes and scale sizes, if at the distance of Virgo, in the range $-13\lesssim M_r\lesssim -9$ and $250\lesssim r_s\lesssim 850$ pc, respectively. Their colors are consistent with a gradually declining star formation history with a specific star formation rate of the order of $10^{-11}$ yr$^{-1}$, i.e. 10 times lower than that of main sequence star forming galaxies. They are older than the cluster formation age and appear regular in morphology. They represent the faintest extremes of the population of low luminosity LSB dwarfs that has been recently detected in wider surveys of the Virgo cluster. Thanks to the depth of our observations we are able to extend the Virgo luminosity function down to $M_r\sim -9.3$ (corresponding to total masses $M\sim 10^7$ M$_{\odot}$), finding an average faint-end slope $\alpha\simeq -1.4$. This relatively steep slope puts interesting constraints on the nature of the Dark Matter and in particular on warm Dark Matter (WDM) often invoked to solve the overprediction of the dwarf number density by the standard CDM scenario. We derive a lower limit on the WDM particle mass $>1.5$ keV.Comment: accepted for publication in ApJ, 13 pages, 6 figure