564 research outputs found

    Crystal Shape-Dependent Magnetic Susceptibility and Curie Law Crossover in the Spin Ices Dy2Ti2O7 and Ho2Ti2O7

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    We present an experimental determination of the isothermal magnetic susceptibility of the spin ice materials Dy2Ti2O7 and Ho2Ti2O7 in the temperature range 1.8-300 K. The use of spherical crystals has allowed the accurate correction for demagnetizing fields and allowed the true bulk isothermal susceptibility X_T(T) to be estimated. This has been compared to a theoretical expression based on a Husimi tree approximation to the spin ice model. Agreement between experiment and theory is excellent at T > 10 K, but systematic deviations occur below that temperature. Our results largely resolve an apparent disagreement between neutron scattering and bulk measurements that has been previously noted. They also show that the use of non-spherical crystals in magnetization studies of spin ice may introduce very significant systematic errors, although we note some interesting - and possibly new - systematics concerning the demagnetizing factor in cuboidal samples. Finally, our results show how experimental susceptibility measurements on spin ices may be used to extract the characteristic energy scale of the system and the corresponding chemical potential for emergent magnetic monopoles.Comment: 11 pages, 3 figures 1 table. Manuscript submitte

    Inappropriateness in laboratory medicine: An elephant in the room?

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    Appropriateness of diagnostic testing can be conventionally described as prescription of the right test, using the right method, at the right time, to the right patient, with the right costs and for producing the right outcome. There is ongoing debate about the real burden of inappropriateness in laboratory diagnostics. The media coverage of this issue has also recently led to either over- or under-emphasizing the clinical, organizational and economic consequences. This is quite problematic, inasmuch as some reliable data are available in the current scientific literature, showing that inappropriateness of laboratory testing can be as high as 70%. This is especially evident for, though not limited to, cancer biomarkers testing, in which the practice of avoidable tests ordering is dramatically magnified. The reasons beyond inappropriateness are many and multifaceted, entailing wrong habits, resistance to changes, poor culture, insufficient education and healthcare inefficiencies. There are many unfavorable consequences attributable to avoidable testing, including unjustified incremental costs, derangement of laboratory efficiency and potential patient safety issues. The tentative solutions to this important problem necessitate that policymakers, local hospital administrators, laboratory professionals, clinicians, patients' associations and diagnostic companies join the efforts and embark in the same landmark effort for disseminating a better culture of appropriateness

    Current laboratory diagnostics of coronavirus disease 2019 (COVID-19)

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    Laboratory medicine provides an almost irreplaceable contribution to the diagnostic reasoning and managed care of most human pathologies. The novel coronavirus disease 2019 (COVID-19) is not an exception to this paradigm. Although the relatively recent emergence does not allow to draw definitive conclusions on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostics, some standpoints can be conveyed. First and foremost, it seems now clear that we will be living together with this virus for quite a long time, so that our vigilance and responsiveness against the emergence of new local outbreaks shall be maintained at the highest possible levels. The etiological diagnosis of COVID-19 is, and will remain for the foreseeable future, deeply based on direct identification of viral RNA by means of molecular biology techniques in biological materials, especially upper and lower respiratory tract specimens. Whether other materials, such as blood, urine, stools, saliva and throat washing, will become valid alternatives has not been unequivocally defined so far. As concerns serological testing, promising information can be garnered from preliminary investigations, showing that the vast majority of COVID-19 patients seem to develop a sustained immune response against the virus, characterized especially by emergence of anti-SARS-CoV-2 IgG and IgA, 1 to 2 weeks after the onset of fever and/or respiratory symptoms. Whether these antibodies will have persistent neutralizing activity against the virus is still to be elucidated on individual and general basis. The availability of rapid tests for detecting either viral antigens or anti-SARS-CoV-2 antibodies are a potentially viable opportunity for purposes of epidemiologic surveillance, though more information is needed on accuracy and reliability of these portable immunoassays

    Water-energy-ecosystem nexus in small run-of-river hydropower : Optimal design and policy

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    Acknowledgment This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Support from the Helmholtz Centre for Environmental Research - UFZ is gratefully acknowledged.Peer reviewedPublisher PD

    OPTIMAL MANAGEMENT OF FLEXIBILITY SERVICES IN LV DISTRIBUTION GRIDS

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    With the increase of intermittent and not programmable generation from clean resources and of new demand tech-nologies characterized by high coincident peaks (like heat pumps, induction cookers, etc.) the management of avail-able flexibility in distribution grids to provide network ser-vices has become very important. The paper proposes an optimization model to manage the flexibility in the LV net-work to both solve local network problems and aggregate the available flexibility for use at higher levels while sat-isfying LV network constraints. The model is a tool for the LV DSOs to optimally manage the flexibilities and its fea-tures are illustrated on the IEEE 123 test feeder

    Identification of population-informative markers from high-density genotyping data through combined feature selection and machine learning algorithms: Application to European autochthonous and cosmopolitan pig breeds

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    Large genotyping datasets, obtained from high-density single nucleotide polymorphism (SNP) arrays, developed for different livestock species, can be used to describe and differentiate breeds or populations. To identify the most discriminating genetic markers among thousands of genotyped SNPs, a few statistical approaches have been proposed. In this study, we applied the Boruta algorithm, a wrapper of the machine learning random forest algorithm, on a database of 23 European pig breeds (20 autochthonous and three cosmopolitan breeds) genotyped with a 70k SNP chip, to pre-select informative SNPs. To identify different sets of SNPs, these pre-selected markers were then ranked with random forest based on their mean decrease accuracy and mean decrease gene indexes. We evaluated the efficiency of these subsets for breed classification and the usefulness of this approach to detect candidate genes affecting breed-specific phenotypes and relevant production traits that might differ among breeds. The lowest overall classification error (2.3%) was reached with a subpanel including only 398 SNPs (ranked based on their mean decrease accuracy), with no classification error in seven breeds using up to 49 SNPs. Several SNPs of these selected subpanels were in genomic regions in which previous studies had identified signatures of selection or genes associated with morphological or production traits that distinguish the analysed breeds. Therefore, even if these approaches have not been originally designed to identify signatures of selection, the obtained results showed that they could potentially be useful for this purpose

    Relationship between the prevalence of hemoglobin S and the ethnic background of blood donors in Paraná state Relação entre prevalência da hemoglobina S e origem étnica de doadores de sangue no estado do Paraná

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    aBStRaCt Introduction: Hemoglobin S (HbS) is one of the most common inherited hematological disorders in humans. In Brazil, the sickle-cell disease (SCD) has significant epidemiological importance due to its prevalence and the morbidity-mortality and, therefore, it has been identified as a matter of public health. Objective: To determine the prevalence of HbS among Asian Brazilian, Afro Brazilian, and Euro Brazilian individuals of a blood bank in Curitiba. Material and method: The study was conducted from January 2008 to December 2009, and included 83,213 donors seen at the Instituto Paranaense de Hemoterapia e Hematologia. Results and discussion: The prevalence of HbS in the studied population was 0.9%, among them, 0% Asian Brazilians, 2.7% Afro Brazilians, and 0.7% Euro Brazilians. There was a positive association, statistically significant for the sickle cell trait in Afro-descendants, with odds ratio (OR) 4.01; confidence interval (CI) 3.42-4.72; and 95% confidence. Conclusion: This study showed higher rates of sickle cell trait in Afro Brazilians, which corroborates data published in other Brazilian regions and states

    Sindrome di charge: risultati a lungo termine della riabilitazione audiologica

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    Obiettivo del presente lavoro è valutare i risultati della riabilitazione audiologica su un gruppo, numericamente consistente, di bambini affetti da sindrome di CHARGE. Lo studio è stato eseguito retrospettivamente, utilizzando il database dei pazienti pediatrici, presso l’Audiologia dell’Azienda Ospedaliero-Universitaria di Padova e di Ferrara. Sono stati individuati 31 bambini in totale, che hanno presentato diversi gradi di disabilità uditiva associata alla sindrome di CHARGE. La valutazione audiologica è stata eseguita utilizzando i potenziali evocati uditivi (ABR) e/o l’elettrococleografia, oppure le tecniche di audiometria infantile (VRA o play audiometry). Sono stati valutati anche i risultati percettivi, in termini di capacità di comunicazione e linguaggio espressivo. Sono quindi stati studiati gli effetti della riabilitazione uditiva (con apparecchio acustico o impianto cocleare) e in particolare lo sviluppo del linguaggio nel corso di un lungo follow-up. Gli esiti degli interventi riabilitativi sono risultati diversi in relazione alle eterogenee e spesso gravi disabilità associate alla sindrome di CHARGE (ad esempio, ritardo di sviluppo psico-fisico, gravi disturbi visivi concomitanti, disfunzioni uditive retrococleari per neuropatia uditiva/dissincronia associata). Anche dopo lungo follow-up, lo sviluppo del linguaggio è risultato gravemente compromesso nella maggior parte dei casi, suggerendo quindi la necessità di sviluppare modalità di comunicazione alternative in questo gruppo di piccoli Pazienti. L’identificazione precoce della sordità neurosensoriale e l’accurata pianificazione di trattamenti riabilitativi mirati, è in ogni caso fondamentale nei bambini con sindrome di CHARGE
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