Carrier-controlled ferromagnetism in SrTiO3

Magnetotransport and superconducting properties are investigated for uniformly La-doped SrTiO3 films and GdTiO3/SrTiO3 heterostructures, respectively. GdTiO3/SrTiO3 interfaces exhibit a high-density two-dimensional electron gas on the SrTiO3-side of the interface, while for the SrTiO3 films carriers are provided by the dopant atoms. Both types of samples exhibit ferromagnetism at low temperatures, as evidenced by a hysteresis in the magnetoresistance. For the uniformly doped SrTiO3 films, the Curie temperature is found to increase with doping and to coexist with superconductivity for carrier concentrations on the high-density side of the superconducting dome. The Curie temperature of the GdTiO3/SrTiO3 heterostructures scales with the thickness of the SrTiO3 quantum well. The results are used to construct a stability diagram for the ferromagnetic and superconducting phases of SrTiO3.Comment: Revised version that is closer to the published version; Fig. 2 correcte

Gender differences in skin and core body temperature during exercise in a hot, humid environment.

Background. It is universally accepted that men and women regulate heat differently during exercise in hot, humid environments. Despite this common knowledge, little empirical data is available to explain how gender differences effect core/skin temperature changes. Further, the data that is available includes only limited measurement sites and/or time points. Methods. The purpose of this study was to measure the heat regulatory patterns for both men and women during 60-min of exercise in a hot, humid environment. Twenty aerobically fit subjects (10 men; 10 women) completed an acclimation session followed by a 60-min exercise protocol in an environmental chamber set at 39.9 ± 1.1 °C and 46.4 ± 4% relative humidity. Each exercise protocol consisted of four intervals of an 8-min walk (mean ± SD; men: 4.0 ± 0.3, women: 3.0 ± 0.2 mph) and 7-min light jog (men: 5.4 ± 0.5, women: 5.0 ± 0.3 mph). Subjects were confirmed to be euhydrated (urine specific gravity) prior to exercise and were encouraged to drink water to maintain hydration during exercise. Pre- and Post-exercise body weights did not differ, thus it appears hydration was maintained during exercise. Skin temperatures (iButton wireless loggers) were recorded every minute at seventeen sites (right and left: upper chest, mid-chest, abdomen, upper back, mid-back, lower back, upper arm, and lower arm, and back of the neck). In addition, core body temperature (rectal), rating of perceived exertion (RPE), and heart rate (wireless telemetry) were also recorded at the end of each interval of the protocol. Statistical analysis was carried out using a 2 (gender) x 60 (time) repeated measures ANOVA. Other variables were analyzed using a 2 (gender) x 8 (time) ANOVA with repeated measures on the 2nd factor. Any non-normally distributed data was log transformed. Significance was set at p\u3c0.05 and location of effects will be determined using individual t-tests with a Bonferroni correction for multiple comparisons. Results. Analysis revealed significantly higher skin temperatures in four locations on men compared to women: right upper back (p=0.048), right mid-back (p=0.001), right lower back (p=0.001), and left upper back (p\u3c0.001). Additionally, these changes were seen despite no significant differences between genders in core body temperature, RPE, and heart rate. This latter finding supports the conclusion that a similar degree of exercise, heat stress was applied to both men and women. Conclusions. We found gender differences at four different skin temperature locations. These changes might suggest that men retain more metabolic heat in various locations on the back when exercising in a hot, humid environment compared to women. Further research is needed to understand how these changes may affect post-exercise recovery return to baseline skin and core temperature values

Comparing Three Methods of Measuring Skin Temperature during Exercise in a Hot, Humid Environment

Exercise in a hot, humid environment substantially increases the physiological stress of exercise. Most of the techniques that are currently used to monitor changes in skin temperature have been in use for more than 20 years with little innovation. The purpose of the present study was two-fold: 1) to compare three techniques for measuring skin temperature (wired skin electrode, wireless temperature data logger, and thermal imaging) and 2) to compare and contrast these measures in men and women completing 45-min of cycling in a hot (39±2°C), humid (45±5% RH) environment. The CPHS committee approved all procedures described in this report and subjects gave written consent to participate. Men (N=14) and women (N=18) completed all study requirements out of 45 subjects that were enrolled. Following a baseline screening session that included a measurement of body composition (whole body DXA scan) and an aerobic fitness test (VO2peak), subjects were scheduled for an experimental exercise trial between 0500 and 0800. Subjects arrived to the laboratory and were tested for hydration using urine specific gravity and if dehydrated, they were provided water to drink before starting the exercise trial. Exercise consisted of 50-min of cycling. After 50-min, subjects were asked to continue cycling until their rectal core body temperature exceeded 39.3°C. The time they were able to exercise beyond 50-min was recorded and compared between individuals. Wired skin temperature was monitored using YSI400 banjo probes, wireless skin temperature was monitored using a data logging system (iButton), and thermal skin temperature was measured from images taken with a thermal camera (RAZR Max-IR). These skin measurements were made on the bicep and abdomen. All body temperatures were recorded at rest, every 10-min during exercise, and immediately following the end of exercise. Data was statistically analyzed using a 2 (gender: men & women) x sensor method (wired, wireless, and thermal) x time (0, 10, 20, 30, 40, 50, end) ANOVA with repeated measures on the 2nd and 3rd factors. Significance was set a

Complex Dynamics and Synchronization of Delayed-Feedback Nonlinear Oscillators

We describe a flexible and modular delayed-feedback nonlinear oscillator that is capable of generating a wide range of dynamical behaviours, from periodic oscillations to high-dimensional chaos. The oscillator uses electrooptic modulation and fibre-optic transmission, with feedback and filtering implemented through real-time digital-signal processing. We consider two such oscillators that are coupled to one another, and we identify the conditions under which they will synchronize. By examining the rates of divergence or convergence between two coupled oscillators, we quantify the maximum Lyapunov exponents or transverse Lyapunov exponents of the system, and we present an experimental method to determine these rates that does not require a mathematical model of the system. Finally, we demonstrate a new adaptive control method that keeps two oscillators synchronized even when the coupling between them is changing unpredictably.Comment: 24 pages, 13 figures. To appear in Phil. Trans. R. Soc. A (special theme issue to accompany 2009 International Workshop on Delayed Complex Systems

High-Fidelity Control, Detection, and Entanglement of Alkaline-Earth Rydberg Atoms

Trapped neutral atoms have become a prominent platform for quantum science, where entanglement fidelity records have been set using highly excited Rydberg states. However, controlled two-qubit entanglement generation has so far been limited to alkali species, leaving the exploitation of more complex electronic structures as an open frontier that could lead to improved fidelities and fundamentally different applications such as quantum-enhanced optical clocks. Here, we demonstrate a novel approach utilizing the two-valence electron structure of individual alkaline-earth Rydberg atoms. We find fidelities for Rydberg state detection, single-atom Rabi operations and two-atom entanglement that surpass previously published values. Our results pave the way for novel applications, including programmable quantum metrology and hybrid atom–ion systems, and set the stage for alkaline-earth based quantum computing architectures

A Chandrasekhar Mass Progenitor for the Type Ia Supernova Remnant 3C 397 from The Enhanced Abundances of Nickel and Manganese

Despite decades of intense efforts, many fundamental aspects of Type Ia supernova (SNe Ia) remain elusive. One of the major open questions is whether the mass of the exploding white dwarf (WD) is close to the Chandrasekhar limit. Here we report the detection of strong K-shell emission from stable Fe-peak elements in the Suzaku X-ray spectrum of the Type Ia supernova remnant (SNR) 3C 397. The high Ni/Fe and Mn/Fe mass ratios (0.11-0.24 and 0.018-0.033, respectively) in the hot plasma component that dominates the K-shell emission lines indicate a degree of neutronization in the SN ejecta which can only be achieved by electron captures in the dense cores of exploding WDs with a near-Chandrasekhar mass. This suggests a single-degenerate origin for 3C 397, since Chandrasekhar mass progenitors are expected naturally if the WD accretes mass slowly from a companion. Together with other results supporting the double-degenerate scenario, our work adds to the mounting evidence that both progenitor channels make a significant contribution to the SN Ia rate in star-forming galaxies.Comment: Accepted by ApJL; 6 pages with 4 figures and 1 tabl