1-loop contribution to the dynamical exponents in spin glasses

We evaluate the corrections to the mean field values of the $x$ and the $z$ exponents at the first order in the $\epsilon$-expansion, for $T=T_c$. We find that both $x$ and $z$ are decreasing when the space dimension decreases.Comment: 12 pages 3 Postscript figure

Regulation of advance directives in Italy: a bad law in the making.

PURPOSE: The Advance Directives (ADs) have been adopted in many countries to defend patients' autonomy. In Italy, the role of ADs has recently been the subject of heated debate involving political parties and the Roman Catholic Church. In February 2009, the conservative government coalition presented a bill of law on this issue. It has been passed by the Low Chamber and is now being discussed in the Senate. The purpose of the article is to highlight any possible bill's contradiction with Italian Constitution, Italian Code of Medical Ethics (ICME), and Oviedo Convention contents, relevant for intensivists. METHODS: Analysis of bill's content in the light of Italian Constitution, ICME, Oviedo Convention articles and in comparison with French legislation regarding end of life (Leonetti law). RESULTS: In the Authors' point of view the bill's articles -limit the moral and judicial importance of four main issues as informed consent, permanent incapacity, artificial nutrition/hydration, and withdraw/withhold treatments. CONCLUSIONS: In the Authors' opinion the ADs must represent informed preferences made freely by patients within the relationship with their physicians, as part of an advance care planning. When this relationship develops in accordance with the ICME rules, it contains all of the ethical/professional dimensions to legitimate right choices in each case. The law should draw inspiration from ICME principles, assigning them a juridical power, acknowledging their validity in legitimating end-of-life decisions, and defining a framework of juridical legitimacy for these decisions without infringing on patients' right to autonomy with prescriptions on the care

Experimental observation of the optical spin transfer torque

The spin transfer torque is a phenomenon in which angular momentum of a spin polarized electrical current entering a ferromagnet is transferred to the magnetization. The effect has opened a new research field of electrically driven magnetization dynamics in magnetic nanostructures and plays an important role in the development of a new generation of memory devices and tunable oscillators. Optical excitations of magnetic systems by laser pulses have been a separate research field whose aim is to explore magnetization dynamics at short time scales and enable ultrafast spintronic devices. We report the experimental observation of the optical spin transfer torque, predicted theoretically several years ago building the bridge between these two fields of spintronics research. In a pump-and-probe optical experiment we measure coherent spin precession in a (Ga,Mn)As ferromagnetic semiconductor excited by circularly polarized laser pulses. During the pump pulse, the spin angular momentum of photo-carriers generated by the absorbed light is transferred to the collective magnetization of the ferromagnet. We interpret the observed optical spin transfer torque and the magnetization precession it triggers on a quantitative microscopic level. Bringing the spin transfer physics into optics introduces a fundamentally distinct mechanism from the previously reported thermal and non-thermal laser excitations of magnets. Bringing optics into the field of spin transfer torques decreases by several orders of magnitude the timescales at which these phenomena are explored and utilized.Comment: 11 pages, 4 figure

Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As

It has been demonstrated that magnetocrystalline anisotropies in (Ga,Mn)As are sensitive to lattice strains as small as 10^-4 and that strain can be controlled by lattice parameter engineering during growth, through post growth lithography, and electrically by bonding the (Ga,Mn)As sample to a piezoelectric transducer. In this work we show that analogous effects are observed in crystalline components of the anisotropic magnetoresistance (AMR). Lithographically or electrically induced strain variations can produce crystalline AMR components which are larger than the crystalline AMR and a significant fraction of the total AMR of the unprocessed (Ga,Mn)As material. In these experiments we also observe new higher order terms in the phenomenological AMR expressions and find that strain variation effects can play important role in the micromagnetic and magnetotransport characteristics of (Ga,Mn)As lateral nanoconstrictions.Comment: 11 pages, 4 figures, references fixe

The COVID-19 Wellbeing Study: Examining perceived coercion and psychological wellbeing during the COVID-19 pandemic by means of an online survey, asynchronous virtual focus groups and individual interviews – a protocol

Introduction: The COVID-19 pandemic has resulted in many countries applying restrictive measures, such as lockdown, to contain and prevent further spread. The psychological impact of lockdown and working as a healthcare worker on the frontline has been chronicled in studies pertaining to previous infectious disease pandemics that have reported the presence of depressive symptoms, anxiety, insomnia, and post-traumatic stress symptoms. Potentially linked to psychological well-being and not yet studied is the possibility that lockdown and working on the frontline of the pandemic are associated with perceptions of coercion. Methods and analysis: The present study aimed to examine perceived coercion in those who have experienced COVID-19-related lockdown and/or worked as a frontline healthcare worker across three European countries. It aimed to describe how such perceptions may impact on psychological well-being, coping and posttraumatic growth. It will employ an explanatory mixedmethods research methodology consisting of an online survey and online asynchronous virtual focus groups (AVFGs) and individual interviews. χ2 tests and analyses of variance will be used to examine whether participants from different countries differ according to demographic factors, whether there are differences between cohorts on perceived coercion, depression, anxiety and post-traumatic growth scores. The relationship between coercion and symptoms of distress will be assessed using multiple regression. Both the AVFGs and the narrative interviews will be analysed using thematic narrative analysis. Ethics and dissemination: The study has been approved by University College London’s Research Ethics Committee under Project ID Number 7335/004. Results will be disseminated by means of peer-reviewed publications and at national and/or international conferences

Voltage control of magnetocrystalline anisotropy in ferromagnetic - semiconductor/piezoelectric hybrid structures

We demonstrate dynamic voltage control of the magnetic anisotropy of a (Ga,Mn)As device bonded to a piezoelectric transducer. The application of a uniaxial strain leads to a large reorientation of the magnetic easy axis which is detected by measuring longitudinal and transverse anisotropic magnetoresistance coefficients. Calculations based on the mean-field kinetic-exchange model of (Ga,Mn)As provide microscopic understanding of the measured effect. Electrically induced magnetization switching and detection of unconventional crystalline components of the anisotropic magnetoresistance are presented, illustrating the generic utility of the piezo voltage control to provide new device functionalities and in the research of micromagnetic and magnetotransport phenomena in diluted magnetic semiconductors.Comment: Submitted to Physical Review Letters. Updates version 1 to include a more detailed discussion of the effect of strain on the anisotropic magnetoresistanc

Breathing rhythm variations during wash-in do not influence exhaled volatile organic compound profile analyzed by an electronic nose

E-noses are innovative tools used for exhaled volatile organic compound (VOC) analysis, which have shown their potential in several diseases. Before obtaining a full validation of these instruments in clinical settings, a number of methodological issues still have to be established. We aimed to assess whether variations in breathing rhythm during wash-in with VOC-filtered air before exhaled air collection reflect changes in the exhaled VOC profile when analyzed by an e-nose (Cyranose 320). We enrolled 20 normal subjects and randomly collected their exhaled breath at three different breathing rhythms during wash-in: (a) normal rhythm (respiratory rate (RR) between 12 and 18/min), (b) fast rhythm (RR > 25/min) and (c) slow rhythm (RR < 10/min). Exhaled breath was collected by a previously validated method (Dragonieri et al., J. Bras. Pneumol. 2016) and analyzed by the e-nose. Using principal component analysis (PCA), no significant variations in the exhaled VOC profile were shown among the three breathing rhythms. Subsequent linear discriminant analysis (LDA) confirmed the above findings, with a cross-validated accuracy of 45% (p = ns). We concluded that the exhaled VOC profile, analyzed by an e-nose, is not influenced by variations in breathing rhythm during wash-in