Solving the mystery of human sleep schedules one mutation at a time.

Sleep behavior remains one of the most enigmatic areas of life. The unanswered questions range from "why do we sleep?" to "how we can improve sleep in today's society?" Identification of mutations responsible for altered circadian regulation of human sleep lead to unique opportunities for probing these territories. In this review, we summarize causative circadian mutations found from familial genetic studies to date. We also describe how these mutations mechanistically affect circadian function and lead to altered sleep behaviors, including shifted or shortening of sleep patterns. In addition, we discuss how the investigation of mutations can not only expand our understanding of the molecular mechanisms regulating the circadian clock and sleep duration, but also bridge the pathways between clock/sleep and other human physiological conditions and ailments such as metabolic regulation and migraine headaches

Particle Acceleration and Plasma Dynamics during Magnetic Reconnection in the Magnetically-dominated Regime

Magnetic reconnection is thought to be the driver for many explosive phenomena in the universe. The energy release and particle acceleration during reconnection have been proposed as a mechanism for producing high-energy emissions and cosmic rays. We carry out two- and three-dimensional kinetic simulations to investigate relativistic magnetic reconnection and the associated particle acceleration. The simulations focus on electron-positron plasmas starting with a magnetically dominated, force-free current sheet ($\sigma \equiv B^2/(4\pi n_e m_e c^2) \gg 1$). For this limit, we demonstrate that relativistic reconnection is highly efficient at accelerating particles through a first-order Fermi process accomplished by the curvature drift of particles along the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra $f \propto (\gamma-1)^{-p}$ and approaches $p = 1$ for sufficiently large $\sigma$ and system size. Eventually most of the available magnetic free energy is converted into nonthermal particle kinetic energy. An analytic model is presented to explain the key results and predict a general condition for the formation of power-law distributions. The development of reconnection in these regimes leads to relativistic inflow and outflow speeds and enhanced reconnection rates relative to non-relativistic regimes. In the three-dimensional simulation, the interplay between secondary kink and tearing instabilities leads to strong magnetic turbulence, but does not significantly change the energy conversion, reconnection rate, or particle acceleration. This study suggests that relativistic reconnection sites are strong sources of nonthermal particles, which may have important implications to a variety of high-energy astrophysical problems.Comment: 18 pages, 13 figures, slightly modified after submitted to Ap

Examining AWB’s market power in the international wheat market

The Australian wheat marketing system has been through a number of stages of deregulation in recent years. However, the AWB still maintains the monopoly selling rights of Australian wheat exports. The AWB and its supporters justify the single desk by arguing that the monopoly power enables them to gain a higher price in the export markets. Opposition to the single desk argues that Australia does not produce enough wheat to influence prices. The objective of this study is to test the market power hypothesis by examining the quantity - price relationship of Australian wheat exports and the stability of this relationship over time using annual data from 1961 to 2000.AWB, single desk, wheat marketing, national competition policy, Agricultural and Food Policy, Crop Production/Industries,