1,345 research outputs found

    First clear evidence of quantum chaos in the bound states of an atomic nucleus

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    We study the spectral fluctuations of the 208^{208}Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of 6.206.20 MeV recently identified at the Maier-Leibnitz-Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of Random Matrix Theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter ω\omega, which takes the value ω=0\omega=0 for regular systems and ω1\omega \simeq 1 for chaotic systems. We obtain ω=0.85±0.02\omega=0.85 \pm 0.02 which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in 208^{208}Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition our results show that chaotic and non-chaotic nuclear states coexist in the same energy region of the spectrum.Comment: 9 pages, 1 figur

    Theoretical derivation of 1/f noise in quantum chaos

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    It was recently conjectured that 1/f noise is a fundamental characteristic of spectral fluctuations in chaotic quantum systems. This conjecture is based on the behavior of the power spectrum of the excitation energy fluctuations, which is different for chaotic and integrable systems. Using random matrix theory we derive theoretical expressions that explain the power spectrum behavior at all frequencies. These expressions reproduce to a good approximation the power laws of type 1/f (1/f^2) characteristics of chaotic (integrable) systems, observed in almost the whole frequency domain. Although we use random matrix theory to derive these results, they are also valid for semiclassical systems.Comment: 5 pages (Latex), 3 figure

    Ethical conflicts among physicians and nurses during the COVID‐19 pandemic: A qualitative study

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    Rationale, Aims and Objectives The healthcare system and professionals working in the sector have experienced a high caseload during the coronavirus disease 2019 (COVID-19) pandemic. This has increased the potential for morally harmful events that violate professionals' moral codes and values. The aim of this study was to understand and explore experiences of new moral challenges emerging among physicians and nurses caring for individuals during the COVID-19 pandemic. Method The consolidated criteria for reporting qualitative research (COREQ) checklist was used in this qualitative study based on Gadamer's phenomenology. Participants were selected using a convenience sampling method. Thirteen medicine and nursing graduates were interviewed in depth. The participants all worked on the frontline at the start of the COVID-19 pandemic. Data were gathered in two basic healthcare districts in Spain, encompassing both primary care and hospital care. Results Four main themes emerged from the data analysis: (1) Betrayal of moral and ethical values as a key source of suffering; (2) Ethical and moral sense of failure accompanying loss of meaning; (3) Lack of confidence in performance; (4) Self-demand and self-punishment as personal condemnation among healthcare workers. Conclusions Health institutions must implement interventions for health professionals to help mitigate the consequences of experiencing complex ethical scenarios during the pandemic. In addition, they should promote training in moral and ethical deliberation and prepare them to make decisions of great ethical significance

    Characterization, conservation and loss of dignity at the end-of- life in the emergency department. A qualitative protocol

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    Aims: to explore and understand the experiences of terminally-ill patients and their relatives regarding dignity during end-of-life care in the emergency department. Background: the respect given to the concept of dignity is significantly modifying the clinical relationship and the care framework involving the end-of-life patient in palliative care units, critical care units, hospices and their own homes. This situation is applicable to in-hospital emergency departments, where there is a lack of research which takes the experiences of end-of-life patients and their relatives into account. Design: a phenomenological qualitative study. Methods: the protocol was approved in December 2016 and will be carried out from December 2016 to December 2020. The Gadamer's philosophical underpinnings will be used in the design and development of the study. The data collection will include participant observation techniques in the Emergency Department, in-depth interviews with terminally-ill patients and focus groups with their relatives. For the data analysis, the field notes and verbatim transcriptions will be read and codified using ATLAS.ti software to search for emerging themes. Discussion: emerging themes that contribute to comprehending the phenomenon of dignity in end-of-life care in the Emergency Department are expected to be found. This study's results could have important implications in the implementation of new interventions in Emergency Departments. These interventions would be focused on improving: the social acceptance of death, environmental conditions, promotion of autonomy and accompaniment, and assumption (takeover) of dignified actions and attitudes (respect for human rights)

    Depth sensors-based upper limb motion capture system for functional neurorehabilitation

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    Versatile and accurate motion capture systems, with the required properties to be integrated within both clinical and domiciliary environments, would represent a significant advance in following the progress of the patients as well as in allowing the incorporation of new data exploitation and analysis methods to enhance the functional neurorehabilitation therapeutic processes. Besides, these systems would permit the later development of new applications focused on the automatization of the therapeutic tasks in order to increase the therapist/patient ratio, thus decreasing the costs [1]. However, current motion capture systems are not still ready to work within uncontrolled environments

    Kinect-based occupational therapy virtual environment for functional neurorehabilitation of the upper limb

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    The use of virtual reality technologies has attracted great interest in the area of functional neurorehabilitation [1]. These technologies have a strong ludic component that can increase motivation. Furthermore, Kinect-based motion tracking enables us to individualize the exercises and to generate knowledge [2]. The aim of this research is to perform a proof of concept test of a virtual environment for upper limb rehabilitation. To this end, we have designed two rehabilitation virtual scenarios based on occupational therapy activities. Activities are monitored by a control system based on Microsoft® Kinect sensor [3], for performing bilateral hand coordination and finger dissociation rehabilitation exercises. Both virtual scenarios have been validated by expert therapists at the Institut Guttmann of Nerurrehabilitación and a preliminary evaluation has been performed with four traumatic brain injury patients

    Brain injury MRI simulator based on theoretical models of neuroanatomic damage

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    In order to improve the body of knowledge about brain injury impairment is essential to develop image database with different types of injuries. This paper proposes a new methodology to model three types of brain injury: stroke, tumor and traumatic brain injury; and implements a system to navigate among simulated MRI studies. These studies can be used on research studies, to validate new processing methods and as an educational tool, to show different types of brain injury and how they affect to neuroanatomic structures

    Improving brain injury cognitive rehabilitation by personalized telerehabilitation services: Guttmann neuropersonal trainer

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    Cognitive rehabilitation aims to remediate or alleviate the cognitive deficits appearing after an episode of acquired brain injury (ABI). The purpose of this work is to describe the telerehabilitation platform called Guttmann Neuropersonal Trainer (GNPT) which provides new strategies for cognitive rehabilitation, improving efficiency and access to treatments, and to increase knowledge generation from the process. A cognitive rehabilitation process has been modeled to design and develop the system, which allows neuropsychologists to configure and schedule rehabilitation sessions, consisting of set of personalized computerized cognitive exercises grounded on neuroscience and plasticity principles. It provides remote continuous monitoring of patient's performance, by an asynchronous communication strategy. An automatic knowledge extraction method has been used to implement a decision support system, improving treatment customization. GNPT has been implemented in 27 rehabilitation centers and in 83 patients' homes, facilitating the access to the treatment. In total, 1660 patients have been treated. Usability and cost analysis methodologies have been applied to measure the efficiency in real clinical environments. The usability evaluation reveals a system usability score higher than 70 for all target users. The cost efficiency study results show a relation of 1-20 compared to face-to-face rehabilitation. GNPT enables brain-damaged patients to continue and further extend rehabilitation beyond the hospital, improving the efficiency of the rehabilitation process. It allows customized therapeutic plans, providing information to further development of clinical practice guidelines
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