Electron spin resonance on a 2-dimensional electron gas in a single AlAs quantum well

Direct electron spin resonance (ESR) on a high mobility two dimensional electron gas in a single AlAs quantum well reveals an electronic $g$-factor of 1.991 at 9.35 GHz and 1.989 at 34 GHz with a minimum linewidth of 7 Gauss. The ESR amplitude and its temperature dependence suggest that the signal originates from the effective magnetic field caused by the spin orbit-interaction and a modulation of the electron wavevector caused by the microwave electric field. This contrasts markedly to conventional ESR that detects through the microwave magnetic field.Comment: 4 pages, 4 figure

Micro-SQUID technique for studying the temperature dependence of switching fields of single nanoparticles

An improved micro-SQUID technique is presented allowing us to measure the temperature dependence of the magnetisation switching fields of single nanoparticles well above the critical superconducting temperature of the SQUID. Our first measurements on 3 nm cobalt nanoparticle embedded in a niobium matrix are compared to the Neel Brown model describing the magnetisation reversal by thermal activation over a single anisotropy barrier.Comment: 3 pages, 4 figures; conference proceeding: 1st Joint European Magnetic Symposia (JEMS'01), Grenoble (France), 28th August - 1st September, 200

Living IoT: A Flying Wireless Platform on Live Insects

Sensor networks with devices capable of moving could enable applications ranging from precision irrigation to environmental sensing. Using mechanical drones to move sensors, however, severely limits operation time since flight time is limited by the energy density of current battery technology. We explore an alternative, biology-based solution: integrate sensing, computing and communication functionalities onto live flying insects to create a mobile IoT platform. Such an approach takes advantage of these tiny, highly efficient biological insects which are ubiquitous in many outdoor ecosystems, to essentially provide mobility for free. Doing so however requires addressing key technical challenges of power, size, weight and self-localization in order for the insects to perform location-dependent sensing operations as they carry our IoT payload through the environment. We develop and deploy our platform on bumblebees which includes backscatter communication, low-power self-localization hardware, sensors, and a power source. We show that our platform is capable of sensing, backscattering data at 1 kbps when the insects are back at the hive, and localizing itself up to distances of 80 m from the access points, all within a total weight budget of 102 mg.Comment: Co-primary authors: Vikram Iyer, Rajalakshmi Nandakumar, Anran Wang, In Proceedings of Mobicom. ACM, New York, NY, USA, 15 pages, 201

Sustained response after a 2-year course of lamivudine treatment of hepatitis B e antigen-negative chronic hepatitis B

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72882/1/j.1365-2893.2004.00556.x.pd

Collaborative Project Across Three Hong Kong Universities: A Case Study in E-Commerce Education

This paper reports on the work undertaken by three tertiary institutions in Hong Kong to provide business students with the opportunity to experience a project-based teamwork game in learning e-commerce (EC). The teaching objective of this EC project is to develop the knowledge and skills of students, such as in the use of EC site-building tools, critical thinking, communication skills, teamwork, and entrepreneurship. This study examined student attitudes toward the learning in introductory e-commerce course via a project-based teamwork game in EC using a non-traditional teaching approach. The results ofan evaluation indicate that the project-based teamwork approach performed to expectations. Based on the feedback from students from the three tertiary institutions, the project was found to facilitate the teaching and learning of EC and to be interesting, exciting, innovative, and more worthwhile than traditional textbook-based learning

Semiclassical theory of electron drag in strong magnetic fields

We present a semiclassical theory for electron drag between two parallel two-dimensional electron systems in a strong magnetic field, which provides a transparent picture of the most salient qualitative features of anomalous drag phenomena observed in recent experiments, especially the striking sign reversal of drag at mismatched densities. The sign of the drag is determined by the curvature of the effective dispersion relation obeyed by the drift motion of the electrons in a smooth disorder potential. Localization plays a role in explaining activated low temperature behavior, but is not crucial for anomalous drag per se.Comment: 10 page

Daytime melatonin and light independently affect human alertness and body temperature

Light significantly improves alertness during the night (Cajochen, Sleep Med Rev, 11, 2007 and 453; Ruger et al., AJP Regul Integr Comp Physiol, 290, 2005 and R1413), but results are less conclusive at daytime (Lok et al., J Biol Rhythms, 33, 2018 and 589). Melatonin and core body temperature levels at those times of day may contribute to differences in alerting effects of light. In this experiment, the combined effect of daytime exogenous melatonin administration and light intensity on alertness, body temperature, and skin temperature was studied. The goal was to assess whether (a) alerting effects of light are melatonin dependent, (b) soporific effects of melatonin are mediated via the thermoregulatory system, and (c) light can improve alertness after melatonin-induced sleepiness during daytime. 10 subjects (5 females, 5 males) received melatonin (5 mg) in dim (10 lux) and, on a separate occasion, in bright polychromatic white light (2000 lux). In addition, they received placebo both under dim and bright light conditions. Subjects participated in all four conditions in a balanced order, yielding a balanced within-subject design, lasting from noon to 04:00 pm. Alertness and performance were assessed half hourly, while body temperature and skin temperature were measured continuously. Saliva samples to detect melatonin concentrations were collected half hourly. Melatonin administration increased melatonin concentrations in all subjects. Subjective sleepiness and distal skin temperature increased after melatonin ingestion. Bright light exposure after melatonin administration did not change subjective alertness scores, but body temperature and proximal skin temperature increased, while distal skin temperature decreased. Light exposure did not significantly affect these parameters in the placebo condition. These results indicate that (a) exogenous melatonin administration during daytime increases subjective sleepiness, confirming a role for melatonin in sleepiness regulation, (b) bright light exposure after melatonin ingestion significantly affected thermoregulatory parameters without altering subjective sleepiness, therefore temperature changes seem nonessential for melatonin-induced sleepiness, (c) subjective sleepiness was increased by melatonin ingestion, but bright light administration was not able to improve melatonin-induced sleepiness feelings nor performance. Other (physiological) factors may therefore contribute to differences in alerting effects of light during daytime and nighttime

Prevalence and clinical features of patients with concurrent HBsAg and anti‐HBs: Evaluation of the hepatitis B research network cohort

The prevalence of concurrent HBsAg and anti‐HBs in plasma of persons with chronic hepatitis B virus (HBV) infection is variable and its clinical significance enigmatic. We examined the prevalence and clinical and virological features of concurrent HBsAg and anti‐HBs in children and adults with chronic HBV infection living in North America. A total of 1462 HBsAg positive participants in the Hepatitis B Research Network paediatric and adult cohorts were included (median age 41 (range 4‐80) years, 48% female, 11% white, 13% black, 73% Asians). Only 18 (1.2%) were found to be anti‐HBs positive (≥10 mIU/mL) at initial study evaluation. Distributions of sex, race, HBV genotype and ALT were similar between participants with and without concurrent anti‐HBs. Those who were anti‐HBs positive appeared to be older (median age 50 vs 41 years, P = .06), have lower platelet counts (median 197 vs 222 × 103/mm3, P = .07) and have higher prevalence of HBeAg (44% vs 26%, P = .10). They also had lower HBsAg levels (median 2.0 vs 3.5 log10 IU/mL, P = .02). Testing of follow‐up samples after a median of 4 years (range 1‐6) in 12 of the 18 participants with initial concurrent anti‐HBs showed anti‐HBs became undetectable in 6, decreased to <10 mIU/mL in 1 and remained positive in 5 participants. Two patients lost HBsAg during follow‐up. In conclusion, prevalence of concurrent HBsAg and anti‐HBs was low at 1.2%, with anti‐HBs disappearing in some during follow‐up, in this large cohort of racially diverse children and adults with chronic HBV infection living in North America. Presence of concurrent HBsAg and anti‐HBs did not identify a specific phenotype of chronic hepatitis B, nor did it appear to affect clinical outcomes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156489/3/jvh13312.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156489/2/jvh13312-sup-0001-FigS1-S3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156489/1/jvh13312_am.pd

Light, alertness, and alerting effects of white light:A literature overview

Light is known to elicit non-image-forming responses, such as effects on alertness. This has been reported especially during light exposure at night. Nighttime results might not be translatable to the day. This article aims to provide an overview of (1) neural mechanisms regulating alertness, (2) ways of measuring and quantifying alertness, and (3) the current literature specifically regarding effects of different intensities of white light on various measures and correlates of alertness during the daytime. In general, the present literature provides inconclusive results on alerting effects of the intensity of white light during daytime, particularly for objective measures and correlates of alertness. However, the various research paradigms employed in earlier studies differed substantially, and most studies tested only a limited set of lighting conditions. Therefore, the alerting potential of exposure to more intense white light should be investigated in a systematic, dose-dependent manner with multiple correlates of alertness and within one experimental paradigm over the course of day