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

Filtering out the Noise: Evaluating the Impact of Noise and Sound Reduction Strategies on Sleep Quality for ICU Patients

The review article by Xie and colleagues examines the impact of noise and noise reduction strategies on sleep quality for critically ill patients. Evaluating the impact of noise on sleep quality is challenging, as it must be measured relative to other factors that may be more or less disruptive to patients\u27 sleep. Such factors may be difficult for patients, observers, and polysomnogram interpreters to identify, due to our limited understanding of the causes of sleep disruption in the critically ill, as well as the challenges in recording and quantifying sleep stages and sleep fragmentation in the intensive care unit. Furthermore, most research in this field has focused on noise level, whereas acousticians typically evaluate additional parameters such as noise spectrum and reverberation time. The authors highlight the disparate results and limitations of existing studies, including the lack of attention to other acoustic parameters besides sound level, and the combined effects of different sleep disturbing factors

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

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

A CRISE DO CAPITALISMO HOJE

BRAGA, Ruy. A restauração do capital: um estudo sobre a crise contemporânea. São Paulo, Xamã, 1996

Quantifying Quantum Causal Influences

Causal influences are at the core of any empirical science, the reason why its quantification is of paramount relevance for the mathematical theory of causality and applications. Quantum correlations, however, challenge our notion of cause and effect, implying that tools and concepts developed over the years having in mind a classical world, have to be reevaluated in the presence of quantum effects. Here, we propose the quantum version of the most common causality quantifier, the average causal effect (ACE), measuring how much a target quantum system is changed by interventions on its presumed cause. Not only it offers an innate manner to quantify causation in two-qubit gates but also in alternative quantum computation models such as the measurement-based version, suggesting that causality can be used as a proxy for optimizing quantum algorithms. Considering quantum teleportation, we show that any pure entangled state offers an advantage in terms of causal effects as compared to separable states. This broadness of different uses showcases that, just as in the classical case, the quantification of causal influence has foundational and applied consequences and can lead to a yet totally unexplored tool for quantum information science.Comment: 12 pages, 3 figures. Comments welcome

EFFECTS OF RECLAIMED ASPHALT, WAX ADDITIVE, AND COMPACTION TEMPERATURE ON CHARACTERISTICS AND MECHANICAL PROPERTIES OF POROUS ASPHALT

This paper describes physical and mechanical properties of porous asphalt mixtures with various RAP amount (0%, 10%, 20%, 30%) containing one WMA additive (organic wax). The samples were prepared using the Marshall compactor at two different temperatures (125 °C, 145 °C) by fabricating six series of porous mixtures. Air void content, particle loss, stiffness modulus, indirect tensile strength, and indirect tensile strength ratio were measured and the effects of RAP, wax, and compaction temperatures were evaluated, considering the results of statistical analyses. Based on the performed tests, it has been concluded that high RAP contents (30%) in WMA-RAP PAs result in decreased porosity, permeability, and moisture resistance, and in increased cohesiveness, stiffness, and indirect tensile strength compared to the reference PAs. On the other hand, for low RAP contents (10%), WMA-RAP PAs show lower cohesiveness and indirect tensile strength, at the same time demonstrating an increase in porosity, permeability, moisture resistance, and stiffness. Reduced compaction temperatures (125 °C) particularly affect the cracking resistance

The clinical academic workforce of the future: a cross-sectional study of factors influencing career decision-making among clinical PhD students at two research-intensive UK universities

OBJECTIVES: To examine clinical doctoral students’ demographic and training characteristics, career intentions, career preparedness and what influences them as they plan their future careers. DESIGN AND SETTING: Online cross-sectional census surveys at two research-intensive medical schools in England in 2015–2016. PARTICIPANTS: All medically qualified PhD students (N=523) enrolled at the University of Oxford and University College London were invited to participate. We report on data from 320 participants (54% male and 44% female), who were representative by gender of the invited population. MAIN OUTCOME MEASURES: Career intentions. RESULTS: Respondents were mainly in specialty training, including close to training completion (25%, n=80), and 18% (n=57) had completed training. Half (50%, n=159) intended to pursue a clinical academic career (CAC) and 62% (n=198) were at least moderately likely to seek a clinical lectureship (CL). However, 51% (n=163) had little or no knowledge about CL posts. Those wanting a CAC tended to have the most predoctoral medical research experience (χ2 (2, N=305)=22.19, p=0.0005). Key reasons cited for not pursuing a CAC were the small number of senior academic appointments available, the difficulty of obtaining research grants and work-life balance. CONCLUSIONS: Findings suggest that urging predoctoral clinicians to gain varied research experience while ensuring availability of opportunities, and introducing more flexible recruitment criteria for CL appointments, would foster CACs. As CL posts are often only open to those still in training, the many postdoctoral clinicians who have completed training, or nearly done so, do not currently gain the opportunity the post offers to develop as independent researchers. Better opportunities should be accompanied by enhanced career support for clinical doctoral students (eg, to increase knowledge of CLs). Finally, ways to increase the number of senior clinical academic appointments should be explored since their lack seems to significantly influence career decisions