Pion-mass dependence of three-nucleon observables

We use an effective field theory (EFT) which contains only short-range interactions to study the dependence of a variety of three-nucleon observables on the pion mass. The pion-mass dependence of input quantities in our ``pionless'' EFT is obtained from a recent chiral EFT calculation. To the order we work at, these quantities are the 1S0 scattering length and effective range, the deuteron binding energy, the 3S1 effective range, and the binding energy of one three-nucleon bound state. The chiral EFT input we use has the inverse 3S1 and 1S0 scattering lengths vanishing at mpi_c=197.8577 MeV. At this ``critical'' pion mass, the triton has infinitely many excited states with an accumulation point at the three-nucleon threshold. We compute the binding energies of these states up to next-to-next-to-leading order in the pionless EFT and study the convergence pattern of the EFT in the vicinity of the critical pion mass. Furthermore, we use the pionless EFT to predict how doublet and quartet nd scattering lengths depend on mpi in the region between the physical pion mass and mpi=mpi_c.Comment: 24 pages, 9 figure

Origin of the Mott Gap

We show exactly that the only charged excitations that exist in the strong-coupling limit of the half-filled Hubbard model are gapped composite excitations generated by the dynamics of the charge $2e$ boson that appears upon explicit integration of the high-energy scale. At every momentum, such excitations have non-zero spectral weight at two distinct energy scales separated by the on-site repulsion $U$. The result is a gap in the spectrum for the composite excitations accompanied by a discontinuous vanishing of the density of states at the chemical potential when $U$ exceeds the bandwidth. Consequently, we resolve the long-standing problem of the cause of the charge gap in a half-filled band in the absence of symmetry breaking.Comment: 6 pages, 2 figures: Expanded Published versio

Effect of Different Types of Physical Activity on Activities of Daily Living in Older Adults : Systematic Review and Meta-Analysis

Peer reviewedPostprin

Excluded-Volume Effects in Tethered-Particle Experiments: Bead Size Matters

The tethered-particle method is a single-molecule technique that has been used to explore the dynamics of a variety of macromolecules of biological interest. We give a theoretical analysis of the particle motions in such experiments. Our analysis reveals that the proximity of the tethered bead to a nearby surface (the microscope slide) gives rise to a volume-exclusion effect, resulting in an entropic force on the molecule. This force stretches the molecule, changing its statistical properties. In particular, the proximity of bead and surface brings about intriguing scaling relations between key observables (statistical moments of the bead) and parameters such as the bead size and contour length of the molecule. We present both approximate analytic solutions and numerical results for these effects in both flexible and semiflexible tethers. Finally, our results give a precise, experimentally-testable prediction for the probability distribution of the distance between the polymer attachment point and the center of the mobile bead.Comment: 4 pages, 3 figure

Anger, Quality of Life and Mood in Multiple Sclerosis

This research was funded by The Multiple Sclerosis Society (UK).Peer reviewedPublisher PD

Remote terminal system evaluation

An Earth Resources Data Processing System was developed to evaluate the system for training, technology transfer, and data processing. In addition to the five sites included in this project two other sites were connected to the system under separate agreements. The experience of these two sites is discussed. The results of the remote terminal project are documented in seven reports: one from each of the five project sites, Purdue University, and an overview report summarizing the other six reports

Emotion processing and social participation following stroke : study protocol

Peer reviewedPublisher PD

Unbiased estimates of galaxy scaling relations from photometric redshift surveys

Many physical properties of galaxies correlate with one another, and these correlations are often used to constrain galaxy formation models. Such correlations include the color-magnitude relation, the luminosity-size relation, the Fundamental Plane, etc. However, the transformation from observable (e.g. angular size, apparent brightness) to physical quantity (physical size, luminosity), is often distance-dependent. Noise in the distance estimate will lead to biased estimates of these correlations, thus compromising the ability of photometric redshift surveys to constrain galaxy formation models. We describe two methods which can remove this bias. One is a generalization of the V_max method, and the other is a maximum likelihood approach. We illustrate their effectiveness by studying the size-luminosity relation in a mock catalog, although both methods can be applied to other scaling relations as well. We show that if one simply uses photometric redshifts one obtains a biased relation; our methods correct for this bias and recover the true relation

Tangential Touch between the Free and the Fixed Boundary in a Semilinear Free Boundary Problem in Two Dimensions

The main result of this paper concerns the behavior of a free boundary arising from a minimization problem, close to the fixed boundary in two dimensions

Simulation studies of improved sounding systems

Two instrument designs for indirect satellite sounding of the atmosphere in the infrared are represented by the High Resolution Infra-Red Sounder, Model 2 (HIRS-2) and by the Advanced Meteorological Temperature Sounder (AMTS). The relative capabilities of the two instruments were tested by simulating satellite measurements from a group of temperature soundings, allowing the two participants to retrieve the temperature profiles from the simulated data, and comparing the results with the original temperature profiles. Four data sets were produced from radiosondes data extrapolated to a suitable altitude, representing continents and oceans, between 30S and 30N. From the information available, temperature profiles were retrieved by two different methods, statistical regression and inversion of the radiative transfer equation. Results show the consequence of greater spectral purity, concomitant increase in the number of spectral intervals, and the better spatial resolution in partly clouded areas. At the same time, the limitation of the HIRS-2 without its companion instrument leads to some results which should be ignored in comparing the two instruments. A clear superiority of AMTS results is shown