Four Stokes parameter radio frequency polarimetry of a flare from AD Leonis

Observations of the four Stokes parameters of a 430 MHz flare from the UV Ceti-type star AD Leonis are presented. The maximum amplitude of the event was 0.52 flux units and the durations at one-half and one-tenth maximum were 12 and 40 seconds, respectively. The degree of circular polarization at maximum intensity was approximately 56 percent and was later observed to be as high as 92 percent. Linear polarization was also observed at a level of about 21 percent at flare maximum which allowed an upper limit of 440 radians - sq m to be placed on the rotation measure

An RG potential for the quantum Hall effects

The phenomenological analysis of fully spin-polarized quantum Hall systems, based on holomorphic modular symmetries of the renormalization group (RG) flow, is generalized to more complicated situations where the spin or other "flavors" of charge carriers are relevant, and where the symmetry is different. We make the simplest possible ansatz for a family of RG potentials that can interpolate between these symmetries. It is parametrized by a single number $a$ and we show that this suffices to account for almost all scaling data obtained to date. The potential is always symmetric under the main congruence group at level two, and when $a$ takes certain values this symmetry is enhanced to one of the maximal subgroups of the modular group. We compute the covariant RG $\beta$-function, which is a holomorphic vector field derived from the potential, and compare the geometry of this gradient flow with available temperature driven scaling data. The value of $a$ is determined from experiment by finding the location of a quantum critical point, i.e., an unstable zero of the $\beta$-function given by a saddle point of the RG potential. The data are consistent with $a \in \mathbb{R}$, which together with the symmetry leads to a generalized semi-circle law.Comment: 10 figures, sligthly updated discussion and refs, accepted for PR

Revised Pulsar Spindown

We address the issue of electromagnetic pulsar spindown by combining our experience from the two limiting idealized cases which have been studied in great extent in the past: that of an aligned rotator where ideal MHD conditions apply, and that of a misaligned rotator in vacuum. We construct a spindown formula that takes into account the misalignment of the magnetic and rotation axes, and the magnetospheric particle acceleration gaps. We show that near the death line aligned rotators spin down much slower than orthogonal ones. In order to test this approach, we use a simple Monte Carlo method to simulate the evolution of pulsars and find a good fit to the observed pulsar distribution in the P-Pdot diagram without invoking magnetic field decay. Our model may also account for individual pulsars spinning down with braking index n < 3, by allowing the corotating part of the magnetosphere to end inside the light cylinder. We discuss the role of magnetic reconnection in determining the pulsar braking index. We show, however, that n ~ 3 remains a good approximation for the pulsar population as a whole. Moreover, we predict that pulsars near the death line have braking index values n > 3, and that the older pulsar population has preferentially smaller magnetic inclination angles. We discuss possible signatures of such alignment in the existing pulsar data.Comment: 8 pages, 7 figures; accepted to Ap

Patterns of sea otter haul-out behavior of California tidal estuary in relation to environmental variables

This study provides the first in depth assessment of Sea Otter haul-out patterns in Elkhorn Slough, California and their relationship to environmental variables. Seasonal and daily water and air temperature fluctuations are a good predictor of Sea Otter haul-out patterns but are affected by the availability of haul-out sites at different tide levels. The cost effectiveness of this choice may be maximal at night because of lack of human disturbance. Southern Sea Otters (Enhydra lutris nereis) were observed during 50 bimonthly 24-h periods between August 2007 and July 2009 (n = 1187 h) from a shore-based observation site located above a non-territorial male resting area on the north side of Moss Landing Harbor. We counted the number of Sea Otters in the area (both in the water and on land) at 30-min intervals. We also recorded tide height, and air and water temperature. Thirty-minute counts averaged 42 Sea Otters using the area (land and water) during the day and 66 at night. The average number of Sea Otters hauled out in the study area during the same haul-out event was 22, and the maximum number was 93. Sea Otters were observed hauled out on 70% of the days surveyed, and the proportion of Sea Otters hauled out was significantly higher at night. Higher numbers of Sea Otters on land was significantly correlated with lower air and water temperature, and with mid-range tide-heights. We speculate that haul-out behavior could play an important role in energy conservation; however, human-related traffic patterns in the area may negatively affect this energy conservation strategy

Monitoring coastal dolphins within the Reef 2050 Integrated Monitoring and Reporting Program: final report of the dolphins team in the megafauna expert group

Three species of coastal dolphins are commonly found throughout the Great Barrier Reef (the Reef), the Australian snubfin dolphin, Orcaella heinsohni, the Australian humpback dolphin, Sousa sahulensis, and the Indo-Pacific bottlenose dolphin, Tursiops aduncus. This report focuses on these three species, acknowledging that many other cetacean species also inhabit the Reef. This report is a desktop study that includes current status of the relevant elements of the Reef, priority indicators for monitoring, potential sources of data, assessment of the adequacy of existing monitoring activities and recommendations for the design of an integrated monitoring program as a component of RIMReP

Polarization observations of nine southern millisecond pulsars

Mean pulse profiles and polarization properties are presented for nine southern pulsars. The observations were made using the Parkes radio telescope at frequencies near 1330 MHz; three of the nine pulsars were also observed at 660 MHz. A very high degree of circular polarization was observed in PSR J1603-7202. Complex position angle variations which are not well described by the rotating-vector model were observed in PSRs J2124-3358 and J2145-0750, both of which have very wide profiles. Rotation measures were obtained for all nine pulsars, with two implying relatively strong interstellar magnetic fields.Comment: 24 pages, 11 figs, accepted by Ap

Is pulsar B0656+14 a very nearby RRAT source?

The recently discovered RRAT sources are characterized by very bright radio bursts which, while being periodically related, occur infrequently. We find bursts with the same characteristics for the known pulsar B0656+14. These bursts represent pulses from the bright end of an extended smooth pulse-energy distribution and are shown to be unlike giant pulses, giant micropulses or the pulses of normal pulsars. The extreme peak-fluxes of the brightest of these pulses indicates that PSR B0656+14, were it not so near, could only have been discovered as an RRAT source. Longer observations of the RRATs may reveal that they, like PSR B0656+14, emit weaker emission in addition to the bursts.Comment: 4 pages, 4 figures, accepted by ApJ

Identifying important resting habitats for the protection of Hawaiian spinner dolphins

With the ever increasing intrusion of anthropogenic activities on wildlife habitats, linking environmental characteristics with behavioural activities is vital for the identification and protection of critical habitats (i.e. those supporting essential life functions such as foraging, breeding or resting)

Late Miocene to early Pliocene stratigraphic record in northern Taranaki Basin: Condensed sedimentation ahead of Northern Graben extension and progradation of the modern continental margin

The middle Pliocene-Pleistocene progradation of the Giant Foresets Formation in Taranaki Basin built up the modern continental margin offshore from western North Island. The late Miocene to early Pliocene interval preceding this progradation was characterised in northern Taranaki Basin by the accumulation of hemipelagic mudstone (Manganui Formation), volcaniclastic sediments (Mohakatino Formation), and marl (Ariki Formation), all at bathyal depths. The Manganui Formation has generally featureless wireline log signatures and moderate to low amplitude seismic reflection characteristics. Mohakatino Formation is characterised by a sharp decrease in the GR log value at its base, a blocky GR log motif reflecting sandstone packets, and erratic resistivity logs. Seismic profiles show bold laterally continuous reflectors. The Ariki Formation has a distinctive barrel-shaped to blocky GR log motif. This signature is mirrored by the SP log and often by an increase in resistivity values through this interval. The Ariki Formation comprises (calcareous) marl made up of abundant planktic foraminifera, is 109 m thick in Ariki-1, and accumulated over parts of the Western Stable Platform and beneath the fill of the Northern Graben. It indicates condensed sedimentation reflecting the distance of the northern region from the contemporary continental margin to the south