2,371 research outputs found

    Purcell magneto-elastic swimmer controlled by an external magnetic field

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    International audienceThis paper focuses on the mechanism of propulsion of a Purcell swimmer whose segments are magnetized and react to an external magnetic field applied into the fluid. By an asymptotic analysis, we prove that it is possible to steer the swimmer along a chosen direction when the control functions are prescribed as an oscillating field. Moreover, we discuss what are the main obstructions to overcome in order to get classical controllability result for this system

    Excess length of hospital stay due to healthcare acquired infections. Methodologies evaluation

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    BACKGROUND: Healthcare acquired infections (HAI) cause an increase of burden and in particular excess length of hospital stay (LOS) accounts for approximately up to 90% of total costs. Therefore accurate estimation of extra hospital stay due to healthcare acquired infections is very important. METHODS: The authors carried out a review comparing the principal methods internationally used for estimating the excess LOS attributable to healthcare acquired infections. RESULTS: The methods described and analysed are: 1) Implicit physician assessment; 2) appropriateness evaluation protocol; 3) unmatched case-control; 4) matched case-control; 5) regression analysis; 6) multistate model. The various methodologies are described underlining advantages and limits which researchers need to know before starting any economic analysis. CONCLUSIONS: Overall, studies taking into account the time-dependent nature of HAI show to give more precise and reliable results

    Optimal projection of observations in a Bayesian setting

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    Optimal dimensionality reduction methods are proposed for the Bayesian inference of a Gaussian linear model with additive noise in presence of overabundant data. Three different optimal projections of the observations are proposed based on information theory: the projection that minimizes the Kullback-Leibler divergence between the posterior distributions of the original and the projected models, the one that minimizes the expected Kullback-Leibler divergence between the same distributions, and the one that maximizes the mutual information between the parameter of interest and the projected observations. The first two optimization problems are formulated as the determination of an optimal subspace and therefore the solution is computed using Riemannian optimization algorithms on the Grassmann manifold. Regarding the maximization of the mutual information, it is shown that there exists an optimal subspace that minimizes the entropy of the posterior distribution of the reduced model; a basis of the subspace can be computed as the solution to a generalized eigenvalue problem; an a priori error estimate on the mutual information is available for this particular solution; and that the dimensionality of the subspace to exactly conserve the mutual information between the input and the output of the models is less than the number of parameters to be inferred. Numerical applications to linear and nonlinear models are used to assess the efficiency of the proposed approaches, and to highlight their advantages compared to standard approaches based on the principal component analysis of the observations

    Evaluation of the analytical variability of dipstick protein pads in canine urine

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    BackgroundThe dipstick is a first-line and inexpensive test that can exclude the presence of proteinuria in dogs. However, no information is available about the analytical variability of canine urine dipstick analysis. ObjectivesThe aim of this study was to assess the analytical variability in 2 dipsticks and the inter-operator variability in dipstick interpretation. MethodsCanine urine supernatants (n = 174) were analyzed with 2 commercially available dipsticks. Two observers evaluated each result blinded to the other observer and to the results of the other dipstick. Intra- and inter-assay variability was assessed in 5 samples (corresponding to the 5 different semi-quantitative results) tested 10 consecutive times over 5 consecutive days. The agreement between observers and between dipsticks was evaluated with Cohen's k test. ResultsIntra-assay repeatability was good (3/10 errors), whereas inter-assay variability was higher (from 1/5 to 4/5 discordant results). The concordance between the operators (k = 0.68 and 0.79 for the 2 dipsticks) and that of the dipsticks (k = 0.66 and 0.74 for the 2 operators) was good. However, 1 observer and 1 dipstick overestimated the results compared with the second observer or dipstick. In any case, discordant results accounted for a single unit of the semi-quantitative scale. ConclusionsAs for any other method, analytic variability may affect the semi-quantitation of urinary proteins when using the dipstick method. Subjective interpretation of the pad and, to a lesser extent, intrinsic staining properties of the pads could affect the results. Further studies are warranted to evaluate the effect of this variability on clinical decisions

    Sexual distress and quality of life among women with bipolar disorder

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    Abstract Background Information on the association between bipolar disorder (BD), sexual satisfaction, sexual function, sexual distress and quality of life (QoL) is sparse. This study aims, in women with BD, to (i) investigate sexual dysfunction, sexual distress, general sexual satisfaction and QoL; (ii) explore whether sexual distress was related to affective symptoms and (iii) investigate whether QoL was associated with sexual distress. The study is a questionnaire survey in an outpatient cohort of women with BD using: Changes in Sexual Functioning Questionnaire, Female Sexual Distress Scale, Altman Self-Rating Mania Scale (ASRM), Major Depression Inventory (MDI) and The World Health Organisation Quality of Life-Brief. Results In total, 61 women (age range 19–63, mean 33.7 years) were recruited. Overall, 54% reported sexual distress (n = 33) and 39% were not satisfied with their sexual life (n = 24). Women with BD were significantly more sexually distressed in comparison with Danish women from the background population but they did not have a higher prevalence of impaired sexual function. Better sexual function was positively associated with ASRM scores while MDI scores were associated with more distress. Finally, the group of non-sexually distressed women with BD reported higher QoL scores compared with the sexually distressed group. Conclusions Women with BD exhibited a high prevalence of sexual distress and their sexual function seemed associated with their actual mood symptoms and perception of QoL

    Laccase-Carrying Polylactic Acid Electrospun Fibers, Advantages and Limitations in Bio-Oxidation of Amines and Alcohols

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    Laccases are oxidative enzymes that could be good candidates for the functionalization of biopolymers with several applications as biosensors for the determination of bioactive amine and alcohols, for bioremediation of industrial wastewater, and for greener catalysts in oxidation reactions in organic synthesis, especially used for non-phenolic compounds in combination with redox mediators in the so-called Laccase Mediator System (LMS). In this work, we describe the immobilization of Laccase from Trametes versicolor (LTv) in poly-L-lactic acid (PLLA) nanofibers and its application in LMS oxidation reactions. The PLLA-LTv catalysts were successfully produced by electrospinning of a water-in-oil emulsion with an optimized method. Different enzyme loadings (1.6, 3.2, and 5.1% (w)/(w)) were explored, and the obtained mats were thoroughly characterized. The actual amount of the enzyme in the fibers and the eventual enzyme leaching in different solvents were evaluated. Finally, the PLLA-LTv mats were successfully applied as such in the oxidation reaction of catechol, and in the LMS method with TEMPO as mediator in the oxidation of amines with the advantage of easier work-up procedures by the immobilized enzyme. However, the PLLA-LTv failed the oxidation of alcohols with respect to the free enzyme. A tentative explanation was provided

    Hematologic and biochemical reference intervals in Shetland Sheepdogs

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    Background: Several breeds have physiological peculiarities that induce variations in reference intervals (RIs) compared with the general canine population. Shetland sheepdogs (SSs) are reported to be more predisposed to different diseases (eg, hyperlipidemia, gallbladder mucocele, and hypothyroidism). Consequently, a breed-specific approach is more often required. Objectives: The aim of this study was to determine whether the RIs of the general canine population could be applied to that of SSs, and to generate breed-specific RIs, where appropriate. Methods: Sixty\ua0clinically healthy and fasted SSs (36% of the population registered at the Italian Breed association) were examined. Routine hematology and biochemistry analyses were performed. The transference method was used to compare the results of SSs with the RIs of the general canine population. When these RIs were not validated, new RIs were generated according to the guidelines of the American Society of Veterinary Clinical Pathology. Differences associated with sex, age, coat color, and whether used as a pet, a herding dog, or an agility dog were also investigated. Results: The transference method validated for 30/38 SS RIs. For 6 of the remaining 8 variables, the difference with the claimed RIs could depend on preanalytical or analytical artifacts, whereas for glucose and total cholesterol, these differences could depend on breed peculiarities. However, in all SSs, the concentration of cholesterol was <12.95\ua0mmol/L. Relevant differences associated with sex, age, coat color, and use were not found. Conclusions: This study suggests that breed-specific RIs should be used for glucose and cholesterol in SSs

    NOVEL BIOMARKER IN CATS AFFECTED WITH SPONTANEOUS CKD: FOCUS ON HYPERTENSION AND PROTEINURIA

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    Chronic kidney disease (CKD) is a common disease of elderly cats characterized by a progressive course and a high mortality rate. The development and the progression of CKD depend on the presence of complications such as proteinuria and hypertension. Hence, a correct staging of the disease based to these latter pathologic states together with serum creatinine, as suggested by the International Renal Interest Society (IRIS) guidelines, is recommended to properly treat affected cats. In this regard, hypertension is often difficult to confirm given the high frequency of white-coat hypertension in this specie. Moreover, although decisive progresses have been achieved in the last years, an early diagnosis of CKD or of hypertension and proteinuria associated with CKD is still challenging in cats. Early identification of ongoing kidney injury may allow veterinarians to prevent worsening of the disease and ultimately to improve the quality of life of affected feline patients. The first part of this thesis was focused on a preliminary evaluation of preanalytical and analytical variability of parameters used in IRIS staging of CKD: preanalytical and analytical variability of urinary protein-to-creatinine (UPC) ratio (study 1); the effect of hematuria and pyuria on UPC (study 2); and the physiologic concentration of the novel biomarker of glomerular filtration rate symmetric dimethylarginine (SDMA) in Holy Birman cats (study 3). The second main part of this thesis was aimed to assess how biomarkers such as serum big endothelin-1 (big-ET1), homocysteine (Hcy), aldosterone and urinary big-ET1, alpha-1 microglobulin (A1MG) and the presence of tubular proteins in urine (evaluated with sodium dodecyl sulfate-agarose gel electrophoresis, SDS-AGE) may allow an early diagnosis of CKD, may identify cats at risk of severe worsening of the disease, or may be a predictor of hypertension (study 4). To this aim, privately owned cats (i.e. clinically healthy cats at risk to develop CKD and cats affected with CKD) were prospectively enrolled and sampled over time. The results of study 1 demonstrated that proteinuria was stable up to to 6 hours at room temperature, 1 week at refrigeration temperature, four freeze-thaw cycles and 4 weeks at 1220\ub0C, whereas the use of different analytical methods resulted in inaccuracy and suboptimal concordance in classifying samples according to IRIS substaging, that in turn can potentially affect clinical decisions, make questionable the comparison of UPC results between different laboratories, and have significant impact in substaging cats affected by CKD. Study 2 showed that hematuria could affect proteinuria, suggesting that diagnosis and staging of renal proteinuria should be avoided or interpreted with caution in samples with high hematuria. Study 3 highlighted that SDMA may be a better marker of CKD than creatinine in Birman cats and the analysis of both creatinine and SDMA could help prevent errors in diagnosing and staging CKD in Birman cats. In study 4, different results were found with the different biomarkers. Big-ET1 did not give satisfying results in serum, whereas in urine the ELISA method yielded satisfying validation results, supporting its introduction in this specie. Urinary big-ET1 was associated with the severity of CKD and proteinuria, revealing that it could be a promising aid in nephropatic cats and could shed light on the pathogenesis of tubulo-interstitial and glomerular damage in cats with CKD. The method to measure Hcy can be considered reliable in cats according to the validation tests. Serum Hcy increased progressively with the progressive increase in severity of CKD and the detection of high Hcy in some non-azotemic patients with CKD could add this new marker to those currently available for the identification and staging of the kidney disease of the cat. Conversely, no direct relationship was found between Hcy and hypertension. Aldosterone was not associated with severity of CKD, proteinuria and SBP. Therefore, neither Hcy nor aldosterone can be considered an indicator of hypertension in cats affected with CKD. The ELISA kit used for A1MG measurement failed all the validation tests and results were considered unacceptable; further studies are therefore needed to investigate the presence of A1MG in cats with CKD and tubular damage. SDS-AGE showed the consistent presence of bands with high molecular weight in healthy cats, suggesting that this pattern is normal in this specie and has to be taken into account while evaluating proteinuria in cats; tubular bands were frequent in patients with CKD at any stage, confirming the predominant tubule-interstitial damage of this disease in cats and suggesting that SDS-AGE can be considered a valuable aid in diagnostic approach to feline CKD

    Modeling and steering magneto-elastic micro-swimmers inspired by the motility of sperm cells

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    Controlling artificial devices that mimic the motion of real microorganisms, is attracting increasing interest, both from the mathematical point of view and applications. A model for a magnetically driven slender micro-swimmer, mimicking a sperm cell is presented, supported by two examples showing how to steer it. Using the Resistive Force Theory (RTF) approach [J. Gray and J. Hancock, J. Exp. Biol. 32, 802 (1955)] to describe the hydrodynamic forces, the micro-swimmer can be described by a driftless affine control system where the control is an external magnetic field. Moreover we discuss through at first an asymptotic analysis and then by numerical simulations how to realize different kinds of paths
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