Musical Instruments of Malaysia and the West Coast of America

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Seed kikuyu performs well

The kikuya variety, Whittet, which can be established from seed has performed well in a trial at Denmark

Hydrodynamical Non-radiative Accretion Flows in Two-Dimensions

Two-dimensional (axially symmetric) numerical hydrodynamical calculations of accretion flows which cannot cool through emission of radiation are presented. The calculations begin from an equilibrium configuration consisting of a thick torus with constant specific angular momentum. Accretion is induced by the addition of a small anomalous azimuthal shear stress which is characterized by a function \nu. We study the flows generated as the amplitude and form of \nu are varied. A spherical polar grid which spans more than two orders of magnitude in radius is used to resolve the flow over a wide range of spatial scales. We find that convection in the inner regions produces significant outward mass motions that carry away both the energy liberated by, and a large fraction of the mass participating in, the accretion flow. Although the instantaneous structure of the flow is complex and dominated by convective eddies, long time averages of the dynamical variables show remarkable correspondence to certain steady-state solutions. Near the equatorial plane, the radial profiles of the time-averaged variables are power-laws with an index that depends on the radial scaling of the shear stress. We find that regardless of the adiabatic index of the gas, or the form or magnitude of the shear stress, the mass inflow rate is a strongly increasing function of radius, and is everywhere nearly exactly balanced by mass outflow. The net mass accretion rate through the disc is only a fraction of the rate at which mass is supplied to the inflow at large radii, and is given by the local, viscous accretion rate associated with the flow properties near the central object.Comment: 33 pages, 12 figures, accepted by MNRA

Helical Magnetorotational Instability in Magnetized Taylor-Couette Flow

Hollerbach and Rudiger have reported a new type of magnetorotational instability (MRI) in magnetized Taylor-Couette flow in the presence of combined axial and azimuthal magnetic fields. The salient advantage of this "helical'' MRI (HMRI) is that marginal instability occurs at arbitrarily low magnetic Reynolds and Lundquist numbers, suggesting that HMRI might be easier to realize than standard MRI (axial field only). We confirm their results, calculate HMRI growth rates, and show that in the resistive limit, HMRI is a weakly destabilized inertial oscillation propagating in a unique direction along the axis. But we report other features of HMRI that make it less attractive for experiments and for resistive astrophysical disks. Growth rates are small and require large axial currents. More fundamentally, instability of highly resistive flow is peculiar to infinitely long or periodic cylinders: finite cylinders with insulating endcaps are shown to be stable in this limit. Also, keplerian rotation profiles are stable in the resistive limit regardless of axial boundary conditions. Nevertheless, the addition of toroidal field lowers thresholds for instability even in finite cylinders.Comment: 16 pages, 2 figures, 1 table, submitted to PR

Numerical simulations of the Accretion-Ejection Instability in magnetised accretion disks

The Accretion-Ejection Instability (AEI) described by Tagger & Pellat (1999) is explored numerically using a global 2d model of the inner region of a magnetised accretion disk. The disk is initially currentless but threaded by a vertical magnetic field created by external currents, and frozen in the flow. In agreement with the theory a spiral instability, similar in many ways to those observed in self-gravitating disks, develops when the magnetic field is, within a factor of a few, at equipartition with the disk thermal pressure. Perturbations in the flow build up currents and create a perturbed magnetic field within the disk. The present non-linear simulations give good evidence that such an instability can occur in the inner region of accretion disks, and generate accretion of gas and vertical magnetic flux toward the central object, if the equilibrium radial profiles of density and magnetic flux exceed a critical threshold.Comment: single tar file with GIF figure

Observation of Buried Phosphorus Dopants near Clean Si(100)-(2x1) with Scanning Tunneling Microscopy

We have used scanning tunneling microscopy to identify individual phosphorus dopant atoms near the clean silicon (100)-(2x1) reconstructed surface. The charge-induced band bending signature associated with the dopants shows up as an enhancement in both filled and empty states and is consistent with the appearance of n-type dopants on compound semiconductor surfaces and passivated Si(100)-(2x1). We observe dopants at different depths and see a strong dependence of the signature on the magnitude of the sample voltage. Our results suggest that, on this clean surface, the antibonding surface state band acts as an extension of the bulk conduction band into the gap. The positively charged dimer vacancies that have been observed previously appear as depressions in the filled states, as opposed to enhancements, because they disrupt these surface bands.Comment: 4 pages, 3 figures. TeX for OSX from Wierde

Effects of Time-Restricted Feeding and Whey Protein Isolate Supplementation on Dietary Intake, Mood, and Sleep in a 12-Week Randomized Controlled Trial

Obesity affects adults in the United States, leading to chronic diseases and reduced well-being. Time-Restricted Feeding (TRF) is a type of dietary intervention lacking current data regarding the effectiveness on facets of well-being. This study’s objective was to determine the effect of time-restricted feeding supplemented with whey protein isolate on food intake, sleep, and mood in overweight or obese adults. Nineteen participants were randomly assigned to the control or experimental group: 1) control, TRF, and 2) experimental, TRF with whey protein supplementation. Participants followed the assigned dietary intervention for 12 weeks. Every 4 weeks (baseline, week 4, week 8, and week 12), anthropometrics, including height and weight, were measured along with the Pittsburg Sleep Quality Index (PSQI) questionnaire, Profile of Mood States (POMS) questionnaire, and dietary record results. Additionally, ActiGraphy measured objective sleep quality at week 1 and week 12. There were no differences between the control and protein groups regarding sleep and mood parameters. The PSQI results indicated no difference in sleep between groups. The POMS subscores for tension-anxiety, when controlled for baseline, were different, with a decrease in the protein group compared to the control at week 12 (P \u3c 0.01). Total food consumption was similar between groups. The results suggested whey protein isolate supplementation with TRF may improve outcomes of mood with no effect on sleep. Therefore, a need for further research to investigate the benefits of TRF and protein supplementation on sleep and mood is necessary