1,444 research outputs found

    Mechanical concept of the neurosurgical robot ‘Minerva'

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    We describe a robot capable of performing all procedures necessary to carry out a complete stereotactic neurosurgical operation under the control and supervision of a surgeon. The operation consists of the introduction of a small probe with diameter 2-3 mm through a hole without trepanation. The robot has been built and is now being tested and evaluated. The accompanying control software as well as various medical probes are either in development or partially tested. The installation will be able to carry out a complete intervention under the surveillance of a computed tomography scanner. In this article we emphasize the design choices required to eliminate gearing backlash in a crucial degree of freedo

    On the Behaviour of General-Purpose Applications on Cloud Storages

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    Managing data over cloud infrastructures raises novel challenges with respect to existing and well studied approaches such as ACID and long running transactions. One of the main requirements is to provide availability and partition tolerance in a scenario with replicas and distributed control. This comes at the price of a weaker consistency, usually called eventual consistency. These weak memory models have proved to be suitable in a number of scenarios, such as the analysis of large data with Map-Reduce. However, due to the widespread availability of cloud infrastructures, weak storages are used not only by specialised applications but also by general purpose applications. We provide a formal approach, based on process calculi, to reason about the behaviour of programs that rely on cloud stores. For instance, one can check that the composition of a process with a cloud store ensures `strong' properties through a wise usage of asynchronous message-passing

    Destructive pneumococcal septic arthritis in end-stage renal disease

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    Summary: Pneumococcal arthritis generally presents as non-destructive monoarthritis, although some underlying metabolic disorders such as liver failure and diabetes have been suggested to represent a risk factor for severe joint disease. Here we report a case of destructive pneumococcal arthritis of the left hip joint in a patient suffering from chronic renal failure treated with hemodialysis for ten years. Inspite of effective anti-pneumococcal antibiotic treatment, the patient with pre-existing renal osteopathy and a mild osteoarthritis continued to suffer from severe and disabling pain of the left hip. This case demonstrates that pneumococcal joint infection in patients with underlying uremic bone disease can lead to quick deterioration of the affected join

    Influence of anthropometric parameters and biochemical markers of bone metabolism on quantitative ultrasound of bone in the institutionalized elderly

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    The assessment of bone quality by quantitative ultrasound (QUS), a transportable and relatively cheap method, shows some correlations with bone mineral density (BMD) as measured by dual-energy X-ray absorptiometry (DXA) and with fracture risk. To examine its correlation with bone metabolism in a population of institutionalized elderly people known to be at high risk for vitamin D deficiency and secondary hyperparathyroidism, QUS of the calcaneus and biochemical parameters were measured in 264 women aged 85±7 (SD) years and in 103 men aged 81±8 years living in 19 nursing homes. Vitamin D deficiency was frequent in this population: 41.9% of the women and 31.4% of the men had a serum 25-hydroxyvitamin (25OHD) level below the 2.5th percentile level of 3276 normal Swiss adults (6.2 µg/l or 15.5 mmol/l). Hyperparathyroidism was less frequent: serum parathyroid hormone (PTH) levels were above the 97.5th percentile level of normal adults (70 pg/l) in 18.9% of women and 9.8% of men. In women, QUS data correlated significantly with age (r=−0.297), body mass index (BMI) (r=0.403), calcium (r=0.220), PTH (r=−0.296), 25OHD (r=0.298) and alkaline phosphatase (AP) (r=−0.170) for broadband ultrasound attenuation (BUA), and with age (r=−0.195), BMI (r=0.208), PTH (r=−0.174), 25OHD (r=0.140) and AP (r=−0.130) for speed of sound (SOS). In men, ultrasound data correlated with BMI (r=0.326), calcium (r=0.199), 25OHD (r=0.258) and AP (r=−0.311) for BUA, and with AP (r=−0.196) for SOS. In women, but not in men because of their smaller number, a multivariate analysis was performed to examine relationships between age, BMI, biochemical markers and QUS. Age, BMI, PTH and phosphate explained 30% of the variance of BUA and 10% for SOS. In conclusion, QUS of bone evaluates characteristics of bone that are influenced, at least partially, by age, BMI and the secondary hyperparathyroidism due to vitamin D deficienc

    Characteristics associated with inappropriate hospital use in elderly patients admitted to a general internal medicine service

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    Our objective was to identify patient characteristics associated with inappropriate hospital days in a cohort of elderly medical inpatients. This prospective cohort study included a total of 196 patients aged 75 years and older, who were consecutively admitted over eight months to the internal medicine service of a regional, non-academic public hospital located in a rural area of Western Switzerland. Patients with severe cognitive impairment, terminal disease, or previously living in a nursing home were excluded. Data on demographics, medical, physical, social and mental status were collected at admission. A blinded hospitalization review was performed concurrently using a modified version of the Appropriateness Evaluation Protocol (AEP). Subjects' mean age was 82.4 years; 63.3% were women. Median length of stay was 8 days. Overall, 68 patients (34.7%) had at least one inappropriate day during their stay, including 18 patients (9.2%) whose hospital admission and entire stay were considered inappropriate. Most inappropriate days were due to discharge delays (87.1%), primarily to nursing homes (59.3%). Univariate analysis showed that subjects with inappropriate days were more likely to be living alone (69.1 vs 48.4%, p=0.006), and receiving formal in-home help (48.5 vs 32.8%, p=0.031). In addition, they were more impaired in basic and instrumental activities of daily living BADLs, and IADLs, p<0.001 and p=0.015, respectively), and more frequently had a depressed mood [29.4 vs 10.9%, p=0.001 with a score ≥ 6 at the Geriatric Depression Scale (GDS), short form]. Using multivariate analysis, independent associations remained for patients living alone (OR 2.6, 95%CI 1.2-5.8, p=0.016), those with a depressed mood (OR 2.8, 95%CI 1.1-7.3, p=0.032), with BADL dependencies (OR 1.5, 95%CI 1.2-1.8, p=0.001), and IADL dependencies (OR 1.3, 95%CI 1.0-1.6, p=0.032). Cardiovascular (OR 0.2, 95%CI 0.1-0.7, p=0.008) and pulmonary admission diagnoses (OR 0.1, 95%CI 0.0-0.7, p=0.022) were inversely associated with inappropriate hospital days. In conclusion, patients living alone, functionally impaired and showing depressive symptoms were at increased risk for inappropriate hospital days. These characteristics might permit better targeting for early discharge planning in these at-risk subjects, and contribute to avoiding premature discharge of other vulnerable elderly patients. Whether these interventions for at-risk patients will also result in prevention of hospitalization hazards, such as deconditioning and related functional decline, will require further stud

    Reasoning algebraically about refinement on TSO architectures

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    The Total Store Order memory model is widely implemented by modern multicore architectures such as x86, where local buffers are used for optimisation, allowing limited forms of instruction reordering. The presence of buffers and hardware-controlled buffer flushes increases the level of non-determinism from the level specified by a program, complicating the already difficult task of concurrent programming. This paper presents a new notion of refinement for weak memory models, based on the observation that pending writes to a process' local variables may be treated as if the effect of the update has already occurred in shared memory. We develop an interval-based model with algebraic rules for various programming constructs. In this framework, several decomposition rules for our new notion of refinement are developed. We apply our approach to verify the spinlock algorithm from the literature

    Verifying linearizability on TSO architectures

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    Linearizability is the standard correctness criterion for fine-grained, non-atomic concurrent algorithms, and a variety of methods for verifying linearizability have been developed. However, most approaches assume a sequentially consistent memory model, which is not always realised in practice. In this paper we define linearizability on a weak memory model: the TSO (Total Store Order) memory model, which is implemented in the x86 multicore architecture. We also show how a simulation-based proof method can be adapted to verify linearizability for algorithms running on TSO architectures. We demonstrate our approach on a typical concurrent algorithm, spinlock, and prove it linearizable using our simulation-based approach. Previous approaches to proving linearizabilty on TSO architectures have required a modification to the algorithm's natural abstract specification. Our proof method is the first, to our knowledge, for proving correctness without the need for such modification

    An annotated checklist of the jumping plant-lice (Insecta: Hemiptera: Psylloidea) from the Mercantour National Park, with seven new records for France and one new synonymy

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    A total of 68 psyllid species are listed from the Mercantour National Park in Southeast France, where a targeted collecting campaign was conducted between 2009 and 2012, as part of the project "ATBI+M" Mercantour. The insects were collected using Malaise traps, flight intercept traps and sweep nets to sample in the vegetation. Additional information on distribution, biology and host-plants is provided for each species. Seven species are recorded for the first time from France: Craspedolepta artemisiae (Foerster, 1848), Craspedolepta nebulosa (Zetterstedt, 1828), Cacopsylla propinqua (Schaefer, 1949), Cyamophila prohaskai (Priesner, 1927), Eryngiofaga cf. refuga (Loginova, 1966), Bactericera parastriola Conci, Ossiannilsson & Tamanini, 1988 and Trioza flixiana Burckhardt & Lauterer, 2002. Trioza (Trioza) rapisardai Conci & Tamanini, 1984 is a new subjective synonym of Trioza brachyceraea Hodkinson & White, 1979, which was previously known only from the male holotype. The abundance, distribution and introduction status of some species are discussed

    Locality and Singularity for Store-Atomic Memory Models

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    Robustness is a correctness notion for concurrent programs running under relaxed consistency models. The task is to check that the relaxed behavior coincides (up to traces) with sequential consistency (SC). Although computationally simple on paper (robustness has been shown to be PSPACE-complete for TSO, PGAS, and Power), building a practical robustness checker remains a challenge. The problem is that the various relaxations lead to a dramatic number of computations, only few of which violate robustness. In the present paper, we set out to reduce the search space for robustness checkers. We focus on store-atomic consistency models and establish two completeness results. The first result, called locality, states that a non-robust program always contains a violating computation where only one thread delays commands. The second result, called singularity, is even stronger but restricted to programs without lightweight fences. It states that there is a violating computation where a single store is delayed. As an application of the results, we derive a linear-size source-to-source translation of robustness to SC-reachability. It applies to general programs, regardless of the data domain and potentially with an unbounded number of threads and with unbounded buffers. We have implemented the translation and verified, for the first time, PGAS algorithms in a fully automated fashion. For TSO, our analysis outperforms existing tools

    Prevention of recurrent hip fracture

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    Our objective was to describe the interventions aimed at preventing a recurrent hip fracture, and other injurious falls, which were provided during hospitalization for a first hip fracture and during the two following years. A secondary objective was to study some potential determinants of these preventive interventions. The design of the study was an observational, two-year follow-up of patients hospitalized for a first hip fracture at the University Hospital of Lausanne, Switzerland. The participants were 163 patients (median age 82 years, 83% women) hospitalized in 1991 for a first hip fracture, among 263 consecutively admitted patients (84 did not meet inclusion criteria, e.g., age >50, no cancer, no high energy trauma, and 16 refused to participate). Preventive interventions included: medical investigations performed during the first hospitalization and aimed at revealing modifiable pathologies that raise the risk of injurious falls; use of medications acting on the risk of falls and fractures; preventive recommendations given by medical staff; suppression of environmental hazards; and use of home assistance services. The information was obtained from a baseline questionnaire, the medical record filled during the index hospitalization, and an interview conducted 2 years after the fracture. Potential predictors of the use of preventive interventions were: age; gender; destination after discharge from hospital; comorbidity; cognitive functioning; and activities of daily living. Bi- and multivariate associations between the preventive interventions and the potential predictors were measured. Inhospital investigations to rule out medical pathologies raising the risk of fracture were performed in only 20 patients (12%). Drugs raising the risk of falls were reduced in only 17 patients (16%). Preventive procedures not requiring active collaboration by the patient (e.g., modifications of the environment) were applied in 68 patients (42%), and home assistance was provided to 67 patients (85% of the patients living at home). Bivariate analyses indicated that prevention was less often provided to patients in poor general conditions, but no ascertainment of this association was found in multivariate analyses. In conclusion, this study indicates that, in the study setting, measures aimed at preventing recurrent falls and injuries were rarely provided to patients hospitalized for a first hip fracture at the time of the study. Tertiary prevention could be improved if a comprehensive geriatric assessment were systematically provided to the elderly patient hospitalized for a first hip fracture, and passive preventive measures implemente
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