Convergence in Energy-Lowering (Disordered) Stochastic Spin Systems

We consider stochastic processes, S^t \equiv (S_x^t : x \in Z^d), with each S_x^t taking values in some fixed finite set, in which spin flips (i.e., changes of S_x^t) do not raise the energy. We extend earlier results of Nanda-Newman-Stein that each site x has almost surely only finitely many flips that strictly lower the energy and thus that in models without zero-energy flips there is convergence to an absorbing state. In particular, the assumption of finite mean energy density can be eliminated by constructing a percolation-theoretic Lyapunov function density as a substitute for the mean energy density. Our results apply to random energy functions with a translation-invariant distribution and to quite general (not necessarily Markovian) dynamics.Comment: 11 page

The lived experience of therapeutic work in the midst of grief: an existential phenomenological study

This dissertation explores the humanistic therapist’s lived experience of loss following bereavement and how a bereaved therapist manages their client work in the midst of their grief. This qualitative phenomenological research was conducted on the basis of semi-structured interviews with seven participants (all of them practising therapists who had experienced recent bereavement), whose accounts were then analysed using Interpretative Phenomenological Analysis. Four main themes were identified. The first highlighted the overwhelming and disorientating experience of grief on an instinctual level. The second dealt with how the participants sought to manage the therapeutic encounter by relying on technique and their professional identity. The third theme explored the positive as well as negative ways in which grief impacted participants’ work with clients. The fourth and final theme explored the expansion of self which seemed to result from participants’ experience of loss in combination with their continuing therapeutic work. This study seeks to contribute to the under-researched area of therapist bereavement and the impact of grief or vulnerability on the therapeutic encounter. Its findings suggest that therapists’ experiences of loss involve complex dynamics with important implications both for therapists themselves and for the therapeutic relationship. The study recommends that further research be undertaken into how therapists are affected by significant life crises, how they manage their own vulnerabilities, and how they navigate therapeutic processes in the midst of bereavement

Clusters and Recurrence in the Two-Dimensional Zero-Temperature Stochastic Ising Model

We analyze clustering and (local) recurrence of a standard Markov process model of spatial domain coarsening. The continuous time process, whose state space consists of assignments of +1 or -1 to each site in ${\bf Z}^2$, is the zero-temperature limit of the stochastic homogeneous Ising ferromagnet (with Glauber dynamics): the initial state is chosen uniformly at random and then each site, at rate one, polls its 4 neighbors and makes sure it agrees with the majority, or tosses a fair coin in case of a tie. Among the main results (almost sure, with respect to both the process and initial state) are: clusters (maximal domains of constant sign) are finite for times $t< \infty$, but the cluster of a fixed site diverges (in diameter) as $t \to \infty$; each of the two constant states is (positive) recurrent. We also present other results and conjectures concerning positive and null recurrence and the role of absorbing states.Comment: 16 pages, 1 figur

Data and performance of an active-set truncated Newton method with non-monotone line search for bound-constrained optimization

In this data article, we report data and experiments related to the research article entitled “A Two-Stage Active-Set Algorithm for Bound-Constrained Optimization”, by Cristofari et al. (2017). The method proposed in Cristofari et al. (2017), tackles optimization problems with bound constraints by properly combining an active-set estimate with a truncated Newton strategy. Here, we report the detailed numerical experience performed over a commonly used test set, namely CUTEst (Gould et al., 2015). First, the algorithm ASA-BCP proposed in Cristofari et al. (2017) is compared with the related method NMBC (De Santis et al., 2012). Then, a comparison with the renowned methods ALGENCAN (Birgin and Martínez et al., 2002) and LANCELOT B (Gould et al., 2003) is reported

Upward Tau Air Showers from Earth

We estimate the rate of observable Horizontal and Upward Tau Air-Showers (HORTAUs, UPTAUS) considering both the Earth opacity and the finite size of the terrestrial atmosphere. We calculate the effective target volumes and masses for Tau air-showers emerging from the Earth. The resulting model-independent masses for satellite experiments such as EUSO may encompass at E_nu_tau = 10^19 eV a very large volume, V= 1020 km^3. Adopting simple power law neutrino fluxes, E^-2 and E^-1, calibrated to GZK-like and Z-Burst-like models, we estimate that at E= 10^19 eV nearly half a dozen horizontal shower events should be detected by EUSO in three years of data collection by the "guaranteed" GZK neutrino flux. We also find that the equivalent mass for an Earth outer layer made of rock is dominant compared to the water, contrary to simplified all-rock/all-water Earth models and previous Montecarlo simulations. Therefore we expect an enhancement of neutrino detection along continental shelves nearby the highest mountain chains, also given the better geometrical acceptance for Earth skimming neutrinos. The Auger experiment might reveal such a signature at E_nu= 10^{18} eV (with 26 events in 3 yr) towards the Andes, if the angular resolution at the horizon (both in azimuth and zenith) would reach an accuracy of nearly one degree needed to disentangle tau air showers from common UHECR. The number of events increases at lower energies; therefore we suggest an extension of the EUSO and Auger sensitivity down to (or even below) E_nu = 10^19 eV and E_nu = 10^18 eV respectively.Comment: New version resubmitted to ApJ on the 6th April 2004; 55 Pages,20 figures, major changes following referee reques

Coordination defects in a-Si and a-Si:H : a characterization from first principles calculations

We study by means of first-principles pseudopotential method the coordination defects in a-Si and a-Si:H, also in their formation and their evolution upon hydrogen interaction. An accurate analysis of the valence charge distribution and of the ``electron localization function'' (ELF) allows to resolve possible ambiguities in the bonding configuration, and in particular to identify clearly three-fold (T_3) and five-fold (T_5) coordinated defects. We found that electronic states in the gap can be associated to both kind of defects, and that in both cases the interaction with hydrogen can reduce the density of states in the gap.Comment: To appear in Philos. Ma

A nonmonotone GRASP

A greedy randomized adaptive search procedure (GRASP) is an itera- tive multistart metaheuristic for difficult combinatorial optimization problems. Each GRASP iteration consists of two phases: a construction phase, in which a feasible solution is produced, and a local search phase, in which a local optimum in the neighborhood of the constructed solution is sought. Repeated applications of the con- struction procedure yields different starting solutions for the local search and the best overall solution is kept as the result. The GRASP local search applies iterative improvement until a locally optimal solution is found. During this phase, starting from the current solution an improving neighbor solution is accepted and considered as the new current solution. In this paper, we propose a variant of the GRASP framework that uses a new “nonmonotone” strategy to explore the neighborhood of the current solu- tion. We formally state the convergence of the nonmonotone local search to a locally optimal solution and illustrate the effectiveness of the resulting Nonmonotone GRASP on three classical hard combinatorial optimization problems: the maximum cut prob- lem (MAX-CUT), the weighted maximum satisfiability problem (MAX-SAT), and the quadratic assignment problem (QAP)

The role of the occupational therapist in disaster areas: systematic review

Background. Disasters are increasingly more frequent events on our planet. During disaster the role of the occupational therapist will require a more specific operative framework within nongovernmental organizations and community health services. Design. Systematic review. Objective. The aim of this study is to evaluate the evidence that highlight occupational therapist’s role in disaster area through a systematic review. Materials and Methods. Research on MEDLINE was performed. All articles from 2005 to 2015 concerning rehabilitation and occupational therapy in disaster areas were included. Results. Ten studies were selected to be included in this review. Four interesting points emerged: the importance of having rehabilitation intervention in postdisaster situations, the necessity to include a rehabilitation team in the early phase of disaster response, the need to provide a method to address the difficult evacuation, and finding the safest method of transport of people with preexisting disabilities and new injuries. Conclusions. The amount of evidence with respect to specific intervention of the occupational therapist’s role in a disaster situation is limited. However some evidence suggests that it could be a good means for reducing the number of medical complications and deaths of persons with preexisting disabilities. The evidences found highlight the necessity to create a multidisciplinary team addressing needs in disasters situation, in which the occupational therapist could certainly contribute