Directed flow in non-adiabatic stochastic pumps

We analyze the operation of a molecular machine driven by the non-adiabatic variation of external parameters. We derive a formula for the integrated flow from one configuration to another, obtain a "no-pumping theorem" for cyclic processes with thermally activated transitions, and show that in the adiabatic limit the pumped current is given by a geometric expression.Comment: 5 pages, 2 figures, very minor change

Imposing Observation-Varying Equality Constraints Using Generalised Restricted Least Squares

Linear equality restrictions derived from economic theory are frequently observation-varying. Except in special cases, Restricted Least Squares (RLS) cannot be used to impose such restrictions without either underconstraining or overconstraining the parameter space. We solve the problem by developing a new estimator that collapses to RLS in cases where the restrictions are observation-invariant. We derive some theoretical properties of our so-called Generalised Restricted Least Squares (GRLS) estimator, and conduct a simulation experiment involving the estimation of a constant returns to scale production function. We find that GRLS significantly outperforms RLS in both small and large samples

Simulated Galaxy Interactions as Probes of Merger Spectral Energy Distributions

We present the first systematic comparison of ultraviolet-millimeter spectral energy distributions (SEDs) of observed and simulated interacting galaxies. Our sample is drawn from the Spitzer Interacting Galaxy Survey, and probes a range of galaxy interaction parameters. We use 31 galaxies in 14 systems which have been observed with Herschel, Spitzer, GALEX, and 2MASS. We create a suite of GADGET-3 hydrodynamic simulations of isolated and interacting galaxies with stellar masses comparable to those in our sample of interacting galaxies. Photometry for the simulated systems is then calculated with the SUNRISE radiative transfer code for comparison with the observed systems. For most of the observed systems, one or more of the simulated SEDs match reasonably well. The best matches recover the infrared luminosity and the star formation rate of the observed systems, and the more massive systems preferentially match SEDs from simulations of more massive galaxies. The most morphologically distorted systems in our sample are best matched to simulated SEDs close to coalescence, while less evolved systems match well with SEDs over a wide range of interaction stages, suggesting that an SED alone is insufficient to identify interaction stage except during the most active phases in strongly interacting systems. This result is supported by our finding that the SEDs calculated for simulated systems vary little over the interaction sequence.Comment: 24 pages, 16 figures, 2 tables, accepted for publication in ApJ. Animations of the evolution of the simulated SEDs can be found at http://www.cfa.harvard.edu/~llanz/sigs_sim.htm

Variations of the ISM Compactness Across the Main Sequence of Star-Forming Galaxies: Observations and Simulations

(abridged) The majority of star-forming galaxies follow a simple empirical correlation in the star formation rate (SFR) versus stellar mass ($M_*$) plane, usually referred to as the star formation Main Sequence (MS). Here we combine a set of hydro-dynamical simulations of interacting galactic disks with state-of-the-art radiative transfer codes to analyze how the evolution of mergers is reflected upon the properties of the MS. We present \textsc{Chiburst}, a Markov Chain Monte Carlo (MCMC) Spectral Energy Distribution (SED) code that fits the multi-wavelength, broad-band photometry of galaxies and derives stellar masses, star formation rates, and geometrical properties of the dust distribution. We apply this tool to the SEDs of simulated mergers and compare the derived results with the reference output from the simulations. Our results indicate that changes in the SEDs of mergers as they approach coalescence and depart from the MS are related to an evolution of dust geometry in scales larger than a few hundred parsecs. This is reflected in a correlation between the specific star formation rate (sSFR), and the compactness parameter $\mathcal{C}$, that parametrizes this geometry and hence the evolution of dust temperature ($T_{\rm{dust}}$) with time. As mergers approach coalescence, they depart from the MS and increase their compactness, which implies that moderate outliers of the MS are consistent with late-type mergers. By further applying our method to real observations of Luminous Infrared Galaxies (LIRGs), we show that the merger scenario is unable to explain these extreme outliers of the MS. Only by significantly increasing the gas fraction in the simulations are we able to reproduce the SEDs of LIRGs.Comment: 18 pages, 10 figures, accepted in Ap

The AGN Luminosity Fraction in Merging Galaxies

Galaxy mergers are key events in galaxy evolution, often causing massive starbursts and fueling active galactic nuclei (AGN). In these highly dynamic systems, it is not yet precisely known how much starbursts and AGN respectively contribute to the total luminosity, at what interaction stages they occur, and how long they persist. Here we estimate the fraction of the bolometric infrared (IR) luminosity that can be attributed to AGN by measuring and modeling the full ultraviolet to far-infrared spectral energy distributions (SEDs) in up to 33 broad bands for 24 merging galaxies with the Code for Investigating Galaxy Emission. In addition to a sample of 12 confirmed AGN in late-stage mergers, found in the $Infrared$ $Array$ $Satellite$ Revised Bright Galaxy Sample or Faint Source Catalog, our sample includes a comparison sample of 12 galaxy mergers from the $Spitzer$ Interacting Galaxies Survey, mostly early-stage. We perform identical SED modeling of simulated mergers to validate our methods, and we supplement the SED data with mid-IR spectra of diagnostic lines obtained with $Spitzer$ InfraRed Spectrograph. The estimated AGN contributions to the IR luminosities vary from system to system from 0% up to 91% but are significantly greater in the later-stage, more luminous mergers, consistent with what is known about galaxy evolution and AGN triggering.Comment: 26 pages, 10 figure

DYNAMIC EVALUATION OF A PINNED ANCHORING SYSTEM FOR NEW YORK STATE’S TEMPORARY CONCRETE BARRIERS

Temporary concrete barrier (TCB) systems are utilized in many circumstances, including for placement adjacent to vertical dropoffs. Free-standing TCB systems are known to have relatively large deflections when impacted, which may be undesirable when dealing with limited space behind the barrier (as seen on a bridge deck) or limited lane width in front of the barrier system. In order to allow TCB systems to be used in space-restricted locations, a variety of TCB stiffening options have been tested, including beam stiffening and pinning the barriers to the pavement. These pavement-pinning procedures have been considered time-consuming and may pose undue risk to work-zone personnel who are anchoring the barrier on the traffic-side face. Thus, a means of reducing TCB deflections while reducing risk to workers was deemed necessary. The primary research objective was to evaluate the potential for pinning alternate barrier sections on the back-side toe of the New York State’s New Jersey-shape TCBs and evaluate the barrier system according to the Test Level 3 (TL-3) criteria set forth in MASH. The research study included one 2270P full-scale vehicle crash test with a Dodge Quad Cab pickup truck. Four 151⁄2-in. (394-mm) long, vertical steel pins were placed through holes on the back-side toe of alternating barrier sections and inserted into drilled holes within the rigid concrete surface. Following the successful redirection of the pickup truck, the safety performance of the pinned anchoring system was determined to be acceptable according to the TL-3 evaluation criteria specified in MASH using the 2270P vehicle. However, it should be noted that significant barrier deflections were observed during the crash test and may be greater than those desired for work areas with restricted space

Development of mental health quality indicators (MHQIs) for inpatient psychiatry based on the interRAI mental health assessment

Abstract Background Outcome quality indicators are rarely used to evaluate mental health services because most jurisdictions lack clinical data systems to construct indicators in a meaningful way across mental health providers. As a result, important information about the effectiveness of health services remains unknown. This study examined the feasibility of developing mental health quality indicators (MHQIs) using the Resident Assessment Instrument - Mental Health (RAI-MH), a clinical assessment system mandated for use in Ontario, Canada as well as many other jurisdictions internationally. Methods Retrospective analyses were performed on two datasets containing RAI-MH assessments for 1,056 patients from 7 facilities and 34,788 patients from 70 facilities in Ontario, Canada. The RAI-MH was completed by clinical staff of each facility at admission and follow-up, typically at discharge. The RAI-MH includes a breadth of information on symptoms, functioning, socio-demographics, and service utilization. Potential MHQIs were derived by examining the empirical patterns of improvement and incidence in depressive symptoms and cognitive performance across facilities in both sets of data. A prevalence indicator was also constructed to compare restraint use. Logistic regression was used to evaluate risk adjustment of MHQIs using patient case-mix index scores derived from the RAI-MH System for Classification of Inpatient Psychiatry. Results Subscales from the RAI-MH, the Depression Severity Index (DSI) and Cognitive Performance Scale (CPS), were found to have good reliability and strong convergent validity. Unadjusted rates of five MHQIs based on the DSI, CPS, and restraints showed substantial variation among facilities in both sets of data. For instance, there was a 29.3% difference between the first and third quartile facility rates of improvement in cognitive performance. The case-mix index score was significantly related to MHQIs for cognitive performance and restraints but had a relatively small impact on adjusted rates/prevalence. Conclusions The RAI-MH is a feasible assessment system for deriving MHQIs. Given the breadth of clinical content on the RAI-MH there is an opportunity to expand the number of MHQIs beyond indicators of depression, cognitive performance, and restraints. Further research is needed to improve risk adjustment of the MHQIs for their use in mental health services report card and benchmarking activities.http://deepblue.lib.umich.edu/bitstream/2027.42/112590/1/12913_2012_Article_2419.pd

A proof by graphical construction of the no-pumping theorem of stochastic pumps

A stochastic pump is a Markov model of a mesoscopic system evolving under the control of externally varied parameters. In the model, the system makes random transitions among a network of states. For such models, a "no-pumping theorem" has been obtained, which identifies minimal conditions for generating directed motion or currents. We provide a derivation of this result using a simple graphical construction on the network of states

Inhalant withdrawal as a clinically significant feature of inhalant dependence disorder.

nhalant use is the intentional inhalation of vapors from commercial products or specific chemical agents for the purpose of achieving intoxication. Inhalants are among the most common and pernicious forms of substance use and the least studied of the major drugs. Diagnosis of inhalant dependence, according to the DSM-IV [Weintraub E, Gandhi D, Robinson C. Medical complications due to mothball abuse. South Med J 2000;93:427-9] excludes inhalant withdrawal symptoms, as expert opinion has suggested that an inhalant withdrawal syndrome is neither common nor clinically significant. This article draws from multiple sources of data to suggest that withdrawal symptoms can be part of inhalant dependence and are clinically significant. This hypothesis needs rigorous evaluation to ensure the diagnostic validity of inhalant use disorders.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78174/1/sdarticle.pd

Merger Signatures in the Dynamics of Star-forming Gas

The recent advent of integral field spectrographs and millimeter interferometers has revealed the internal dynamics of many hundreds of star-forming galaxies. Spatially resolved kinematics have been used to determine the dynamical status of star-forming galaxies with ambiguous morphologies, and constrain the importance of galaxy interactions during the assembly of galaxies. However, measuring the importance of interactions or galaxy merger rates requires knowledge of the systematics in kinematic diagnostics and the visible time with merger indicators. We analyze the dynamics of star-forming gas in a set of binary merger hydrodynamic simulations with stellar mass ratios of 1:1 and 1:4. We find that the evolution of kinematic asymmetries traced by star-forming gas mirrors morphological asymmetries derived from mock optical images, in which both merger indicators show the largest deviation from isolated disks during strong interaction phases. Based on a series of simulations with various initial disk orientations, orbital parameters, gas fractions, and mass ratios, we find that the merger signatures are visible for ~0.2–0.4 Gyr with kinematic merger indicators but can be approximately twice as long for equal-mass mergers of massive gas-rich disk galaxies designed to be analogs of z ~ 2–3 submillimeter galaxies. Merger signatures are most apparent after the second passage and before the black holes coalescence, but in some cases they persist up to several hundred Myr after coalescence. About 20%–60% of the simulated galaxies are not identified as mergers during the strong interaction phase, implying that galaxies undergoing violent merging process do not necessarily exhibit highly asymmetric kinematics in their star-forming gas. The lack of identifiable merger signatures in this population can lead to an underestimation of merger abundances in star-forming galaxies, and including them in samples of star-forming disks may bias the measurements of disk properties such as intrinsic velocity dispersion