Reduction of the field-dependent microwave surface resistance in YBa_2Cu_3O_7 with sub-micrometric BaZrO_3 inclusions as a function of BaZrO_3 concentration

In order to study the vortex pinning determined by artificially introduced pinning centers in the small-vortex displacement regime, we measured the microwave surface impedance at 47.7 GHz in the mixed state of YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ thin films, where sub-micrometric BaZrO$_3$ particles have been incorporated. As a function of the BaZrO$_3$ content, we observe that the absolute losses slightly decrease up to a BaZrO$_3$ content of 5%, and then increase. We found that the magnetic-field-induced losses behave differently, in that they are not monotonic with increasing BaZrO$_3$ concentration: at small concentration (2.5%) the field-induced losses increase, but large reduction of the losses themselves, by factors up to 3, is observed upon further increasing the BaZrO$_3$ concentration in the target up to 7%. Using measurements of both surface resistance and surface reactance we estimate vortex pinning-related parameters. We find that BaZrO$_3$ inclusions introduce deep and steep pinning wells. In particular, the minimum height of the energy barrier for single vortices is raised. At larger BaZrO$_3$ content (5% and 7%) the phenomenon is at its maximum, but it is unclear whether it shows a saturation or not, thus leaving room for further improvements.Comment: 7 pages, 7 figure

Il controllo dei lavoratori dopo il Jobs Act

Il Jobs Act ha avuto come scopo quello di rivedere aggiornare e modernizzare la normtiva sul lavoro. Infatti ha razionalizzato i contratti di lavoro iniziando a svuotare il bacino delle collaborazioni “grigie” a favore del contratto subordinato. Ha creato una maggiore flessibilità in uscita con una nuova e razionale disciplina dei licenziamenti ha inoltre modificato gli ammortizzatori sociali (CIG e disoccupazione) ed ha previsto il potenziamento degli istituti per la conciliazione vita-lavoro ed anche una maggiore flessibilità del rapporto di lavoro. In una così estesa riforma non poteva mancare un miglioramento ed un aggiornamento della disciplina dei controlli, che il datore di lavoro può effettuare sul lavoratore, che tenesse conto dell’evoluzione sia tecnologica sia sociale sia giurisprudenziale. In questa tesi andremo quindi ad analizzare il nuovo art.4 dello statuto dei lavoratori cosi come modificato con il D.lgs 151/2015. Per vedere al meglio quali sono state le modifiche apportate considereremo innanzitutto il percorso storico, partendo dalla nascita dell’art.4 della legge 300/1970, considerando quali furono i fini che portarono il legislatore a scrivere l’art.4. Di conseguenza metteremo in evidenza i limiti che aveva il vecchio art.4 che, per il periodo storico in cui era stato scritto e le modalità di lavoro del momento, non andava a considerare determinate problematiche. Vedremo poi che queste lacune normative hanno portato alla creazione del filone giurisprudenziale dei c.d. “controlli difensivi” discussi e apprezzati da parte della dottrina. Con il prosieguo dell’analisi vedremo anche quali sono le novità portate dall’aggiornamento normativo nel dettaglio e se queste novità vanno effettivamente ad equilibrare il rapporto tra datore di lavoro e lavoratori in materia di controllo. Una delle novità più interessanti e che più vanno a impattare sulla normativa è l’espresso richiamo al Codice della Privacy che va a tutelare i dati del lavoratore e pone nuove restrizioni che in passato non erano considerate. Infatti nonostante la norma ponga una moderna apertura sulle modalità di controllo, soprattutto in merito agli strumenti di lavoro per i quali non è richiesto l’accordo sindacale, il Garante della privacy, a tutela del diritto costituzionale, vincola il datore di lavoro a rispettare nuove disposizioni in materia di privacy che se non applicate renderebbero sanzionabile anche penalmente il controllo del datore di lavoro evidentemente effettuanto senza ottemperare alle disposizioni del Garante. Analizzeremo quindi nel dettaglio, in riferimento a determinati strumenti di lavoro, come la nuova normativa va ad impattare nel concreto

Strong reduction of field-dependent microwave surface resistance in YBa2_{2}Cu3_{3}O7−δ_{7-\delta} with sub-micrometric BaZrO3_3 inclusions

We observe a strong reduction of the field induced thin film surface resistance measured at high microwave frequency ($\nu=$47.7 GHz) in YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ thin films grown on SrTiO$_3$ substrates, as a consequence of the introduction of sub-micrometric BaZrO$_3$ particles. The field increase of the surface resistance is smaller by a factor of $\sim$3 in the film with BaZrO$_3$ inclusions, while the zero-field properties are not much affected. Combining surface resistance and surface reactance data we conclude (a) that BaZrO$_3$ inclusions determine very deep and steep pinning wells and (b) that the pinning changes nature with respect to the pure film.Comment: RevTeX; 4 pages, 3 figures; submitted to Applied Physics Letter

Bioinspired Soft Actuation System Using Shape Memory Alloys

Soft robotics requires technologies that are capable of generating forces even though the bodies are composed of very light, flexible and soft elements. A soft actuation mechanism was developed in this work, taking inspiration from the arm of the Octopus vulgaris, specifically from the muscular hydrostat which represents its constitutive muscular structure. On the basis of the authors’ previous works on shape memory alloy (SMA) springs used as soft actuators, a specific arrangement of such SMA springs is presented, which is combined with a flexible braided sleeve featuring a conical shape and a motor-driven cable. This robot arm is able to perform tasks in water such as grasping, multi-bending gestures, shortening and elongation along its longitudinal axis. The whole structure of the arm is described in detail and experimental results on workspace, bending and grasping capabilities and generated forces are presented. Moreover, this paper demonstrates that it is possible to realize a self-contained octopus-like robotic arm with no rigid parts, highly adaptable and suitable to be mounted on underwater vehicles. Its softness allows interaction with all types of objects with very low risks of damage and limited safety issues, while at the same time producing relatively high forces when necessary

Strong Reduction of the Field-Dependent Microwave Surface Resistance in YBCO with BaZrO_3 Inclusions

We present measurements of the magnetic field dependent microwave surface resistance in laser-ablated YBa$_2$Cu$_3$O$_{7-\delta}$ films on SrTiO$_3$ substrates. BaZrO$_3$ crystallites were included in the films using composite targets containing BaZrO$_3$ inclusions with mean grain size smaller than 1 $\mu$m. X-ray diffraction showed single epitaxial relationship between BaZrO$_3$ and YBa$_2$Cu$_3$O$_{7-\delta}$. The effective surface resistance was measured at 47.7 GHz for 60$< T <$90 K and 0$< \mu_0H <$0.8 T. The magnetic field had a very different effect on pristine YBa$_2$Cu$_3$O$_{7-\delta}$ and YBa$_2$Cu$_3$O$_{7-\delta}$/BaZrO$_3$, while for $\mu_0H=$0 only a reduction of $T_c$ in the YBa$_2$Cu$_3$O$_{7-\delta}$/BaZrO$_3$ film was observed, consistent with dc measurements. At low enough $T$, in moderate fields YBa$_2$Cu$_3$O$_{7-\delta}$/BaZrO$_3$ exhibited an intrinsic thin film resistance lower than the pure film. The results clearly indicate that BaZrO$_3$ inclusions determine a strong reduction of the field-dependent surface resistance. From the analysis of the data in the framework of simple models for the microwave surface impedance in the mixed state we argue that BaZrO$_3$ inclusions determine very steep pinning potentials.Comment: LaTeX, 6 pages, 4 figures, uses jpconf.cls and jpconf11.clo class files, talk given at EUCAS 2007, submitted to J. Phys.: Conf. Serie

New Rheumatoid Arthritis Treatments for &#8216;Old&#8217; Patients : Results of a Systematic Review

Introduction: In the last 20&nbsp;years, biologic and targeted synthetic disease-modifying antirheumatic drugs (DMARDs) have become available for treating rheumatoid arthritis (RA), and a treat-to-target strategy has been introduced. We hypothesise that these advances should have resulted in changes to the characteristics of patients with RA participating in clinical trials of the newest therapies. This study determined whether the baseline characteristics of patients with RA enrolled in clinical trials have changed in the past decade versus patients participating in earlier RA studies. Methods: This secondary analysis was based on randomised controlled trials (RCTs) identified in a systematic literature review. Baseline characteristics of patients with RA with inadequate response to conventional synthetic DMARDs were compared between RCTs published in 1999\u20132009 and those published in 2010\u20132017 using random-effects meta-analyses. Results: Forty RCTs were analysed: 22 from 1999\u20132009 and 18 from 2010\u20132017. No significant difference between the two timeframes and no obvious trend over time were observed for age, gender, disease duration, rheumatoid factor status, tender and swollen joint counts, physician and patient global assessments of disease activity, and pain scores. Variability between RCTs was high. Similar results were observed for Disease Activity Scores and Health Assessment Questionnaire-Disability Index scores, but with low variability between RCTs. Conclusion: The baseline characteristics of patients with RA participating in RCTs do not appear to have changed in the last decade despite the availability of new treatments and a different treatment approach. Further research should determine the impact of baseline patient characteristics on patients\u2019 response to RA treatments

Effect of nanosize BaZrO3 inclusions on vortex parameters in YBaCuO

We report on the field dependence of the microwave complex resistivity data in YBa$_2$Cu$_3$O$_{7-x}$/BaZrO$_3$ films grown by PLD at various BaZrO$_3$ content. The data, analyzed within a recently developed general framework for the mixed-state microwave response of superconductors, yield the field dependence of the fluxon parameters such as the vortex viscosity and the pinning constant. We find that pinning undergoes a change of regime when the BaZrO$_3$ content in the target increases from 2.5 mol.% to 5 mol.%. Simultaneously, the vortex viscosity becomes an increasing function of the applied magnetic field. We propose a scenario in which flux lines are pinned as bundles, and a crossover from dilute point pins to dense c-axis correlated defects takes place between 2.5 and 5 mol.% in the BZO concentration. Our data are inconsistent with vortices occupying mainly the BaZrO$_3$ sites at low fields, and suggest instead that vortices occupy both BaZrO$_3$ sites and interstitials in the YBa$_2$Cu$_3$O$_{7-x}$ matrix, even at low fields.Comment: Presented at EUCAS 2009, to be published in J. Phys.:Conf. Serie

Efficacy and safety data based on historical or pre-existing conditions at baseline for patients with active rheumatoid arthritis who were treated with baricitinib

This study was funded by Eli Lilly and Company and Incyte Corporatio