6,964 research outputs found

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

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    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

    Convergence in Energy-Lowering (Disordered) Stochastic Spin Systems

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    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

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

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    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 Z2{\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<∞t< \infty, but the cluster of a fixed site diverges (in diameter) as t→∞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

    Upward Tau Air Showers from Earth

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    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

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    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

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

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    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

    Next generation bioengineering of lung tissue for transplantation

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    Lung transplantation is the only option for end-stage lung diseases, but organ shortage remains problematic. Generating lungs ex vivo could overcome shortages with current approaches being explored for lung tissue engineering utilizing a biologically derived, synthetic or hybrid scaffold which is seeded with cells and cultured ex vivo. Ideally, cells could be sourced from the transplant recipient and thus are conceptualized to reduce the long-term requirements for immunosuppressive drugs and the risk for rejection. Progenitor cell populations can be controlled more easily than induced pluripotent stem cells (IPSCs), with lower risk of tumour formation. However, as presented in this thesis, progenitor cells can be deranged in diseased lungs such as for example idiopathic pulmonary fibrosis (IPF) and are therefore unlikely candidates to generate healthy tissue. In addition to healthy cells, scaffolds with attributes known to be pro-regenerative are required to generate healthy tissues. In the thesis it is shown that both scaffold and cell age plays a role in the regenerative capacity of a tissue. From this it is clear that to generate a healthy tissue or organ, it is critical to find the appropriate scaffold and cell type. Additionally, bioengineering manufacturing methods that generate reproducible, custom-made, high resolution constructs using cytocompatible materials are ideal for tissue engineering approaches. One such method which is compatible with the criteria above and that has emerged in recent years is 3D printing. 3D printing or bioprinting (when cells are printed) can generate custom structures relevant for human lungs. In this thesis, potential bioinks for bioprinting lung tissue are investigated. A tissue-specific hybrid bioink consisting of alginate, reinforced with extracellular matrix from decellularized lung tissue (rECM) was used to 3D bioprint human airways comprised of regionally specified primary cells which remained patent over time. The biocompatibility and vascularisation of rECM hydrogels was investigated in both T-cell immunodeficient mice mimicking the clinical scenario and immunocompetent mice. Bioprinted rECM hydrogels support the formation of an intact vascular network throughout the full thickness of the graft, comprised of both large and small size blood vessels and integrate well in the surrounding tissue

    A nonmonotone GRASP

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    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)
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