2,378 research outputs found

    Ermakov Systems with Multiplicative Noise

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    Using the Euler-Maruyama numerical method, we present calculations of the Ermakov-Lewis invariant and the dynamic, geometric, and total phases for several cases of stochastic parametric oscillators, including the simplest case of the stochastic harmonic oscillator. The results are compared with the corresponding numerical noiseless cases to evaluate the effect of the noise. Besides, the noiseless cases are analytic and their analytic solutions are briefly presented. The Ermakov-Lewis invariant is not affected by the multiplicative noise in the three particular examples presented in this work, whereas there is a shift effect in the case of the phasesComment: 12 pages, 4 figures, 22 reference

    Evolutionary Origins of Binary Neutron Star Mergers: Effects of Common Envelope Efficiency and Metallicity

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    The formation histories of compact binary mergers, especially stellar-mass binary-black hole mergers, have recently come under increased scrutiny and revision. In this paper we revisit the question of the dominant formation channel and efficiency of forming binary neutron-star mergers. We use the stellar and binary evolution code MESA and implement an up-to-date and detailed method for common envelope and mass transfer. We preform simulations for donor masses between 8-20 solar masses with a neutron star companion of 1.4 and 2.0 solar masses, at two metallicities, using varying common envelope efficiencies, and two prescriptions for electron-capture supernovae. In contrast to the case of binary-black hole mergers, for a neutron star companion of 1.4 solar masses, all binary neutron star mergers are formed following a common envelope phase, while for a neutron star mass of 2.0 solar masses we identify a small subset of mergers following only stable mass transfer if the neutron star receives a large natal kick. Regardless of neutron star companion mass, we find that large supernova natal kicks are favored in the formation of binary neutron star mergers, and find more mergers at subsolar metallicity compared to solar.Comment: accepted to Ap

    Enhancing legacy in palliative care: study protocol for a randomized controlled trial of Dignity Therapy focused on positive outcomes.

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    BackgroundDignity Therapy is a brief psychotherapy that can enhance a sense of legacy while addressing the emotional and existential needs of patients receiving hospice or palliative care. In Dignity Therapy, patients create a formalized "legacy" document that records their most cherished memories, their lessons learned in life, as well as their hopes and dreams for loved ones in the future. To date, this treatment has been studied for its impact on mitigating distress within hospice and palliative care populations and has provided mixed results. This study will instead focus on whether Dignity Therapy enhances positive outcomes in this population.Methods/designIn this study, 90 patients with cancer receiving hospice or palliative care will complete a mixed-methods randomized controlled trial of Dignity Therapy (n = 45) versus Supportive Attention (n = 45). The patients will be enrolled in the study for 3 weeks, receiving a total of six study visits. The primary outcomes examine whether the treatment will quantitatively increase levels of positive affect and a sense of life closure. Secondary outcomes focus on gratitude, hope, life satisfaction, meaning in life, resilience, and self-efficacy. Using a fixed, embedded dataset design, this study will additionally use qualitative interviews to explore patients' perceptions regarding the use of positive outcome measures and whether these outcomes are appropriately matched to their experiences in therapy.DiscussionDignity Therapy has shown mixed results when evaluating its impact on distress, although no other study to date has solely focused on the potential positive aspects of this treatment. This study is novel in its use of mixed methods assessments to focus on positive outcomes, and will provide valuable information about patients' direct experiences in this area.Trial registrationISRCTN91389194

    ‘Back to Life’—Using knowledge exchange processes to enhance lifestyle interventions for liver transplant recipients: A qualitative study

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    Interventions to prevent excessive weight gain after liver transplant are needed. The purpose of the present study was to enhance a specialist post-transplant well-being program through knowledge exchange with end-users.The study used an interactive process of knowledge exchange between researchers, clinicians and health system users. Data were collected as focus groups or telephone interviews and underwent applied thematic analysis.There were 28 participants (age 24-68 years; 64% male). The results identified experiences that may influence decisions around health behaviours during the course of transplant recovery. Three over-arching themes were identified that impact on liver transplant recipients post-transplant health behaviours. These include (i) Finding a coping mechanism which highlighted the need to acknowledge the significant emotional burden of transplant prior to addressing long-term physical wellness; (ii) Back to Life encompassing the desire to return to employment and prioritise family, while co-ordinating the burden of ongoing medical monitoring and self-management and (iii) Tailored, Personalised Care with a preference for health care delivery by transplant specialists via a range of flexible eHealth modalities.This person-centred process of knowledge exchange incorporated experiences of recipients into service design and identified life priorities most likely to influence health behaviours post-transplant. Patient co-creation of services has the potential to improve the integration of knowledge into health systems and future directions will require evaluation of effectiveness and sustainability of patient-centred multidisciplinary service development

    Self-bone graft and simultaneous application of implants in the upper jawbone. (Fit lock technique).

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    The implant-supported rehabilitation ofposterosuperior sectors may be sometimes conditioned by the pneumatization of the para-nasal sinuses, which decreases the possibility of implant placement when the bone height is < or = 4 mm. (prerequisite for primary stabilization). Sinus lift surgery with simultaneous application of implants is the procedure which provides the best chance of success compared to the application of the filling material only. There are many surgical techniques which combine autogenous bone grafting (ilium crest, calvaria,fibula) with implant placement. The objective of this report is to present a new technique which aims to minimize invasive bone grafting and patient morbidity. The authors performed a longitudinal study on 21 cases with a 94.5\% success rate, exemplified by one clinical case. The advantages of this technique are: 1) Functional and anatomical recovery of the jaw cavity. 2) Simultaneous application of implants when the bone is < or = 4mm. 3) Reduction of surgical times. 4) Reduced patient morbidity. 5) Local anesthesia

    Winds in Star Clusters Drive Kolmogorov Turbulence

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    Intermediate and massive stars drive fast and powerful isotropic winds that interact with the winds of nearby stars in star clusters and the surrounding interstellar medium (ISM). Wind-ISM collisions generate astrospheres around these stars that contain hot T∼107T\sim 10^7 K gas that adiabatically expands. As individual bubbles expand and collide they become unstable, potentially driving turbulence in star clusters. In this paper we use hydrodynamic simulations to model a densely populated young star cluster within a homogeneous cloud to study stellar wind collisions with the surrounding ISM. We model a mass-segregated cluster of 20 B-type young main sequence stars with masses ranging from 3--17 M⊙M_{\odot}. We evolve the winds for ∼\sim11 kyrs and show that wind-ISM collisions and over-lapping wind-blown bubbles around B-stars mixes the hot gas and ISM material generating Kolmogorov-like turbulence on small scales early in its evolution. We discuss how turbulence driven by stellar winds may impact the subsequent generation of star formation in the clusterComment: 12 pages, 5 figures, Accepted for publication in ApJ

    Point Source Detection using the Spherical Mexican Hat Wavelet on simulated all-sky Planck maps

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    We present an estimation of the point source (PS) catalogue that could be extracted from the forthcoming ESA Planck mission data. We have applied the Spherical Mexican Hat Wavelet (SMHW) to simulated all-sky maps that include CMB, Galactic emission (thermal dust, free-free and synchrotron), thermal Sunyaev-Zel'dovich effect and PS emission, as well as instrumental white noise. This work is an extension of the one presented in Vielva et al. (2001a). We have developed an algorithm focused on a fast local optimal scale determination, that is crucial to achieve a PS catalogue with a large number of detections and a low flux limit. An important effort has been also done to reduce the CPU time processor for spherical harmonic transformation, in order to perform the PS detection in a reasonable time. The presented algorithm is able to provide a PS catalogue above fluxes: 0.48 Jy (857 GHz), 0.49 Jy (545 GHz), 0.18 Jy (353 GHz), 0.12 Jy (217 GHz), 0.13 Jy (143 GHz), 0.16 Jy (100 GHz HFI), 0.19 Jy (100 GHz LFI), 0.24 Jy (70 GHz), 0.25 Jy (44 GHz) and 0.23 Jy (30 GHz). We detect around 27700 PS at the highest frequency Planck channel and 2900 at the 30 GHz one. The completeness level are: 70% (857 GHz), 75% (545 GHz), 70% (353 GHz), 80% (217 GHz), 90% (143 GHz), 85% (100 GHz HFI), 80% (100 GHz LFI), 80% (70 GHz), 85% (44 GHz) and 80% (30 GHz). In addition, we can find several PS at different channels, allowing the study of the spectral behaviour and the physical processes acting on them. We also present the basic procedure to apply the method in maps convolved with asymmetric beams. The algorithm takes ~ 72 hours for the most CPU time demanding channel (857 GHz) in a Compaq HPC320 (Alpha EV68 1 GHz processor) and requires 4 GB of RAM memory.Comment: 18 pages, 11 figures, revised version (minor changes). MNRAS accepted; high quality color figures upon request to the author

    Attitudes Toward COVID-19 Vaccination Among Occupational Therapy Professionals and Students in Early 2021

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    Purpose: After the widespread transmission of the novel coronavirus that causes COVID-19, the first COVID-19 vaccination received emergency use authorization in the United States in December of 2020. Current research has shown the authorized COVID-19 vaccines to be safe and effective at preventing severe illness. At the time of this study, there appears to be no published research on the attitudes and receipt of COVID-19 vaccinations among occupational therapy professionals and students. The purpose of this study is to describe the attitudes and receipt of COVID-19 vaccinations among occupational therapy professionals and students in early 2021. Methods: A total of 114 occupational therapy professionals and students (age= 41 ± 15, years of certified experience = 13 ± 13) opened the survey link and completed the instrument. Participants were sent an electronic survey via email that collected demographic information and assessed attitudes and receipt of COVID-19 vaccination. Data was downloaded and analyzed using a commercially available statistics package. Results: The majority of occupational therapy professionals in this study agreed on some level that they were comfortable (Strongly Agree = 36.0%, Agree = 16.7%, Somewhat Agree = 10.5%). Most occupational therapy professionals and students stated they had or would receive a COVID-19 vaccination. The majority of participants reported personal, household, and community safety as the primary considerations for receiving a COVID-19 vaccination. In general, these factors were a larger factor for participants than public perception or personal liberties being infringed upon. Conclusions: The findings of this study suggest a majority of occupational therapy professionals and students are comfortable with the current level of approvals for available COVID-19 vaccinations, and at the time of the survey had or intending to be vaccinated. As occupational therapy professionals and students continue to work in day-to-day patient care, it is imperative to consider the best means of educating occupational therapy professionals and students on the potential benefits of COVID-19 vaccinations

    External stimuli help restore post-partum ovarian activity in Pelibuey sheep

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    Post-partum anestrus is a problem on farms, and its duration depends on the frequency and intensity of suckling which affects reproduction and production efficiency to become a determining economic factor. The aim of this study was to determine the post-partum reproductive response in ewe to a "male effect" with an ovulation induction protocol of five days using progesterone and the application of a metabolic restorative (MR; Metabolase ®). One hundred and twenty females were randomly assigned to one of four treatments: T1: Continuous suckling (CS; n = 29), T2: CS + MR (n = 29), T3: CS + Male Effect (ME; n = 32), and T4: CS + MR + ME. The percentage of females in ovulation, weight changes among females and lambs, the onset of estrus, calving, fecundity, and prolificacy were also determined. The ovulation percentage was higher in CS + ME and CS + MR + ME (75.0 and 73.3%) than in the other treatments. Weight changes in females and lambs were different among periods. The onset of estrus was similar for CS and CS + MR (25.9 ± 1.9 and 25.7 ± 0.7 h, respectively). The calving percentage was higher for CS + MR (86.2%) than other treatments. Male presence positively affected the postpartum cyclic ovarian re-establishment and the metabolic restorative could even improve the fertility of hair ewes in continuous suckling with similar hormone protocolKeywords: Male effect, metabolic stimulation, post-partum anestru
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