4,190 research outputs found

    All-optical modulation in wavelength-sized epsilon-near-zero media

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    We investigate the interaction of two pulses (pump and probe) scattered by a nonlinear epsilon-near-zero (ENZ) slab whose thickness is comparable with the ENZ wavelength. We show that when the probe has a narrow spectrum localized around the ENZ wavelength its transmission is dramatically affected by the intensity of the pump. Conversely, if the probe is not in the ENZ regime, its propagation is not noticeably affected by the pump. Such all-optical modulation is due to the oversensitive character of the ENZ regime and it is so efficient to even occur in a wavelength thick slab.Comment: 4 pages, 2 figure

    Polariton excitation in epsilon-near-zero slabs: transient trapping of slow light

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    We numerically investigate the propagation of a spatially localized and quasi-monochromatic electromagnetic pulse through a slab with Lorentz dielectric response in the epsilon-near-zero regime, where the real part of the permittivity vanishes at the pulse carrier frequency. We show that the pulse is able to excite a set of virtual polariton modes supported by the slab, the excitation undergoing a generally slow damping due to absorption and radiation leakage. Our numerical and analytical approaches indicate that in its transient dynamics the electromagnetic field displays the very same enhancement of the field component perpendicular to the slab, as in the monochromatic regime. The transient trapping is inherently accompanied by a significantly reduced group velocity ensuing from the small dielectric permittivity, thus providing a novel platform for achieving control and manipulation of slow light

    EOLO: Sistema per la regolazione controllata di gas ad uso medico per terapia e diagnosi

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    not availableIl progetto riguarda principalmente l\u27ossigeno terapia e la somministrazione di ossido nitrico per terapia e diagnostica La somministrazione controllata di gas ad uso terapeutico ? oggi una pratica clinica consolidata in special modo nella ossigeno terapia per patologie quali le broncopneumopatie croniche ostruttive (BPCO). Nuove terapie con altri gas quali l\u27ossido nitrico NO rappresentano metodiche in corso di validazione clinica ma gi? accettate da organismi di controllo quali FDA, soprattutto nei casi di ipertensione polmonare primitiva. Ci si riferisce quindi a sistemi di somministrazione di gas, come quelli rammentati, mettendo a punto metodiche originarie di "feedback" su parametri fisiologici, misurati durante la terapia in modo incruento, per gestire i relativi dispositivi di erogazione del gas stesso e al monitoraggio delle variabili biologiche rilevanti da parte di centri opportuni. Le malattie respiratorie, dopo le malattie cardiocircolatorie ed i tumori, sono tra le maggiori cause di morte nel mondo. Il loro trend ? crescente, essendo esse causate, fra l\u27altro, da fattori come il fumo e l\u27inquinamento, che sono a loro volta in crescita. Da qui la necessit? di realizzare sistemi semplici ed efficaci per il controllo della strumentazione di ossigenoterapia in una vasta popolazione, anche per gli usi domiciliari. Non ultimo diventa importante con questi numeri, pensare ad una razionalizzazione automatica dei consumi di ossigeno. Per quel che riguarda l\u27ipertensione polmonare, altra patologia verso cui EOLO ? rivolto, un potenziale rimedio ? costituito dalla somministrazione in dosi terapeutiche di Ossido Nitrico in sostituzione ad esempio delle prostacicline con il vantaggio di non ricorrere ad applicazioni invasive cruente e di evitare effetti collaterali sistemici. L\u27uso di questo gas medicale ? per? limitata in quanto il mercato non propone dispositivi per la somministrazione di ossido nitrico ottimizzati alle sue indicazioni d\u27uso. Le indicazione d\u27uso prevedono, infatti, la somministrazione di ossido nitrico a bassi dosaggi(5-40 ppm) e la limitazione del tempo di contatto tra l\u27ossido nitrico e i gas inalatori che il paziente deve respirare. Tale metodologia di somministrazione ? requisito essenziale per il suo impiego, in quanto questo gas si combina molto velocemente con l\u27ossigeno formando Biossido d\u27Azoto (NO2), un gas altamente nocivo. Il biossido di azoto reagendo a sua volta con l\u27acqua forma acido nitrico (HNO3), che ? un acido particolarmente reattivo quindi pericoloso

    Measurement of the thermal expansion coefficient of an Al-Mg alloy at ultra-low temperatures

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    We describe a result coming from an experiment based on an Al-Mg alloy (~ 5% Mg) suspended bar hit by an electron beam and operated above and below the termperature of transition from superconducting to normal state of the material. The amplitude of the bar first longitudinal mode of oscillation, excited by the beam interacting with the bulk, and the energy deposited by the beam in the bar are the quantities measured by the experiment. These quantities, inserted in the equations describing the mechanism of the mode excitation and complemented by an independent measurement of the specific heat, allow us to determine the linear expansion coefficient of the material.Comment: 13 pages, 4 figure

    Fundamental material properties of the 2LiBH4-MgH2 reactive hydride composite for hydrogen storage: (II) Kinetic properties

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    Reaction kinetic behaviour and cycling stability of the 2LiBH4-MgH2 reactive hydride composite (Li-RHC) are experimentally determined and analysed as a basis for the design and development of hydrogen storage tanks. In addition to the determination and discussion about the properties; different measurement methods are applied and compared. The activation energies for both hydrogenation and dehydrogenation are determined by the Kissinger method and via the fitting of solid-state reaction kinetic models to isothermal volumetric measurements. Furthermore, the hydrogen absorption-desorption cycling stability is assessed by titration measurements. Finally, the kinetic behaviour and the reversible hydrogen storage capacity of the Li-RHC are discussed.Fil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Milanese, Chiara. Università degli Studi di Pavia; ItaliaFil: Puszkiel, Julián Atilio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Girella, Alessandro. Università degli Studi di Pavia; ItaliaFil: Schiavo, Benedetto. Università degli Studi di Palermo; ItaliaFil: Lozano, Gustavo A.. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Capurso, Giovanni. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Von Colbe, José M. Bellosta. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Marini, Amedeo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Kabelac, Stephan. Leibniz Universität Hannover; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; Alemani

    Preoperative staging of colorectal cancer using virtual colonoscopy: correlation with surgical results

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    The aim of this study was to evaluate the clinical usefulness of computed tomography colonography (CTC) in the preoperative staging in patients with abdominal pain for occlusive colorectal cancer (CRC) and to compare the results of CTC with the surgical ones

    Fundamental material properties of the 2LiBH4-MgH2 reactive hydride composite for hydrogen storage: (I) Thermodynamic and heat transfer properties

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    Thermodynamic and heat transfer properties of the 2LiBH4-MgH2 composite (Li-RHC) system are experimentally determined and studied as a basis for the design and development of hydrogen storage tanks. Besides the determination and discussion of the properties, different measurement methods are applied and compared to each other. Regarding thermodynamics, reaction enthalpy and entropy are determined by pressure-concentration-isotherms and coupled manometric-calorimetric measurements. For thermal diffusivity calculation, the specific heat capacity is measured by high-pressure differential scanning calorimetry and the effective thermal conductivity is determined by the transient plane source technique and in situ thermocell. Based on the results obtained from the thermodynamics and the assessment of the heat transfer properties, the reaction mechanism of the Li-RHC and the issues related to the scale-up for larger hydrogen storage systems are discussed in detail.Fil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Milanese, Chiara. University of Pavia; ItaliaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Girella, Alessandro. University of Pavia; ItaliaFil: Schiavo, Benedetto. Universidad de Palermo; Argentina. Istituto per le Tecnologie Avanzate; ItaliaFil: Lozano, Gustavo A.. Helmholtz-Zentrum Geesthacht; Alemania. BASF; AlemaniaFil: Capurso, Giovanni. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Von Colbe, José M. Bellosta. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Marini, Amedeo. University of Pavia; ItaliaFil: Kabelac, Stephan. Leibniz Universität Hannover; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht; Alemani

    Consensus communication strategies to improve doctor-patient relationship in paediatric severe asthma

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    Background: Asthma is a chronic inflammatory disease that is very common among youth worldwide. The burden of this illness is very high not only considering financial costs but also on emotional and social functioning. Guidelines and many researches recommend to develop a good communication between physicians and children/caregiver and their parents. Nevertheless, a previous Italian project showed some criticalities in paediatric severe asthma management. The consensus gathered together experts in paediatric asthma management, experts in narrative medicine and patient associations with the aim of identify simple recommendation to improve communication strategies. Methods: Participants to the consensus received the results of the project and a selection of narratives two weeks before the meeting. The meeting was structured in plenary session and in three working groups discussing respectively about communication strategies with children, adolescents and parents. The task of each working group was to identify the most effective (DO) and least effective practices (DON' T) for 5 phases of the visit: welcome, comprehension of the context, emotions management, duration and end of the visit and endurance of the relationship. Results: Participants agreed that good relationships translate into positive outcomes and reached consensus on communication strategies to implement in the different phase of relationships. Conclusions: The future challenges identified by the participants are the dissemination of this Consensus document and the implementation of effective communication strategies to improve the management of pediatric asthma
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