Magnetoelectric effects in an organo-metallic quantum magnet

We observe a bilinear magnetic field-induced electric polarization of 50 $\mu C/m^2$ in single crystals of NiCl$_2$-4SC(NH$_2$)$_2$ (DTN). DTN forms a tetragonal structure that breaks inversion symmetry, with the highly polar thiourea molecules all tilted in the same direction along the c-axis. Application of a magnetic field between 2 and 12 T induces canted antiferromagnetism of the Ni spins and the resulting magnetization closely tracks the electric polarization. We speculate that the Ni magnetic forces acting on the soft organic lattice can create significant distortions and modify the angles of the thiourea molecules, thereby creating a magnetoelectric effect. This is an example of how magnetoelectric effects can be constructed in organo-metallic single crystals by combining magnetic ions with electrically polar organic elements.Comment: 3 pages, 3 figure

Are violations to temporal Bell inequalities there when somebody looks?

The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett as a mean of testing the quantum mechanical delocalization of suitably chosen macroscopic bodies, is discussed by taking into account the effect of the measurement process. A general criterion quantifying this possibility is defined and shown not to be fulfilled by the various experimental configurations proposed so far to test inequalities of different forms.Comment: 7 pages, 1 eps figure, needs europhys.sty and euromacr.tex, enclosed in the .tar.gz file; accepted for publication in Europhysics Letter

Tuning metal/superconductor to insulator/superconductor coupling via control of proximity enhancement between NbSe2_2 monolayers

The interplay between charge transfer and electronic disorder in transition-metal dichalcogenide multilayers gives rise to superconductive coupling driven by proximity enhancement, tunneling and superconducting fluctuations, of a yet unwieldy variety. Artificial spacer layers introduced with atomic precision change the density of states by charge transfer. Here, we tune the superconductive coupling between NbSe$_2$ monolayers from proximity-enhanced to tunneling-dominated. We correlate normal and superconducting properties in [(SnSe)$_{1+{\delta}}$]$_m$[NbSe$_2$]$_1$ tailored multilayers with varying SnSe layer thickness. From high-field magnetotransport the critical fields yield Ginzburg-Landau coherence lengths with an increase of 140 % cross-plane , trending towards two-dimensional superconductivity for m > 9. We show cross-over between three regimes: metallic with proximity-enhanced coupling, disordered-metallic with intermediate coupling and insulating with Josephson tunneling. Our results demonstrate that stacking metal mono- and dichalcogenides allows to convert a metal/superconductor into an insulator/superconductor system, prospecting the control of two-dimensional superconductivity in embedded layers.Comment: Revised version submitted to Journal of Physics: Condensed Matte

Tuning metal/superconductor to insulator/superconductor coupling via control of proximity enhancement between NbSe2 monolayers

The interplay between charge transfer and electronic disorder in transition-metal dichalcogenide multilayers gives rise to superconductive coupling driven by proximity enhancement, tunneling and superconducting fluctuations, of a yet unwieldy variety. Artificial spacer layers introduced with atomic precision change the density of states by charge transfer. Here, we tune the superconductive coupling between NbSe2 monolayers from proximity-enhanced to tunneling-dominated. We correlate normal and superconducting properties in [(SnSe)1+δ]m[NbSe2]1 tailored multilayers with varying SnSe layer thickness (m = 1−15). From high-field magnetotransport the critical fields yield Ginzburg–Landau coherence lengths with an increase of 140% cross-plane (m = 1−9), trending towards two-dimensional superconductivity for m > 9. We show cross-overs between three regimes: metallic with proximity-enhanced coupling (m = 1−4), disordered-metallic with intermediate coupling (m = 5−9) and insulating with Josephson tunneling (m > 9). Our results demonstrate that stacking metal mono- and dichalcogenides allows to convert a metal/superconductor into an insulator/superconductor system, prospecting the control of two-dimensional superconductivity in embedded layers.Peer Reviewe

Influenza vaccine uptake among community-dwelling Italian elderly: results from a large cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Flu vaccination significantly reduces the risk of serious complications like hospitalization and death among community-dwelling older people, therefore vaccination programmes targeting this population group represent a common policy in developed Countries. Among the determinants of vaccine uptake in older age, a growing literature suggests that social relations can play a major role.</p> <p>Methods</p> <p>Drawing on the socio-behavioral model of Andersen-Newman - which distinguishes predictors of health care use in predisposing characteristics, enabling resources and need factors - we analyzed through multilevel regressions the determinants of influenza immunization in a sample of 25,183 elderly reached by a nationally representative Italian survey.</p> <p>Results</p> <p>Being over 85-year old (OR = 1.99; 95% CI 1.77 - 2.21) and suffering from a severe chronic disease (OR = 2.06; 95% CI 1.90 - 2.24) are the strongest determinants of vaccine uptake. Being unmarried (OR = 0.81; 95% CI 0.74 - 0.87) and living in larger households (OR = 0.83; 95% CI 0.74 - 0.87) are risk factors for lower immunization rates. Conversely, relying on neighbors' support (OR = 1.09; 95% CI 1.02 - 1.16) or on privately paid home help (OR = 1.19; 95% CI 1.08 - 1.30) is associated with a higher likelihood of vaccine uptake.</p> <p>Conclusions</p> <p>Even after adjusting for socio-demographic characteristics and need factors, social support, measured as the availability of assistance from partners, neighbors and home helpers, significantly increases the odds of influenza vaccine use among older Italians.</p

Overnight Supervision of Alzheimer's Disease Patients in Nursing Homes - System Development and Field Trial

The number of patients affected by Alzheimer's disease among the population is currently growing, while the availability of resources for their assistance is decreasing. A solution for this problem is provided by the use of Ambient Assisted Living technologies, with the objectives to prolong the independent living of patients at home, to relieve assistance burden on caregivers, and to improve care effectiveness in nursing homes. This paper describes an integrated system designed to support the work of nurses during the night, to ensure comfort and safety of Alzheimer's disease patients in nursing homes. The project started from a similar solution designed for home use, suitably re-engineered for adoption in nursing homes. The system has been designed according to nurses' requirements and expectations, both by revising some existing functionalities, and by developing new components. The results gained from an experimental trial are also presented and discussed

Quantum fluctuations and strong mass renormalization in NiCl2-4SC(NH2)2

In a number of quantum paramagnets, magnetic field can induce a quantum phase transition to an antiferromagnetic state which exists for a range of fields Hc1 < H < Hc2. Generally, these compounds exhibit a significant asymmetry in their properties at low- and high-field transitions. Here we present detailed specific heat and thermal conductivity measurements in NiCl2-4SC(NH2)2 together with analytical and numerical results. We show that the asymmetry is caused by a strong renormalization of the effective mass of spin excitations due to quantum fluctuations for H<Hc1 that are absent for H<Hc2.Comment: 4 pages, 3 figures. Acepted for publication in Phy. Rev. Let