On gravity from SST, geoid from Seasat, and plate age and fracture zones in the Pacific

A composite map produced by combining 90 passes of SST data show good agreement with conventional GEM models. The SEASAT altimeter data were deduced and found to agree with both the SST and GEM fields. The maps are dominated (especially in the east) by a pattern of roughly east-west anomalies with a transverse wavelength of about 2000 km. Comparison with regional bathymetric data shows a remarkedly close correlation with plate age. Most anomalies in the east half of the Pacific could be partly caused by regional differences in plate age. The amplitude of these geoid or gravity anomalies caused by age differences should decrease with absolute plate age, and large anomalies (approximately 3 m) over old, smooth sea floor may indicate a further deeper source within or perhaps below the lithosphere. The possible plume size and ascent velocity necessary to supply deep mantle material to the upper mantle without complete thermal equilibration was considered. A plume emanating from a buoyant layer 100 km thick and 10,000 times less viscous than the surrounding mantle should have a diameter of about 400 km and must ascend at about 10 cm/yr to arrive still anomalously hot in the uppermost mantle

Spin-resolved spectroscopy of the intermediate polar DQ Her

We present high-speed spectroscopic observations of the intermediate polar (IP) DQ Herculis. Doppler tomography of two He I lines reveals a spiral density structure in the accretion disc around the white dwarf (WD) primary. The spirals look very similar to the spirals seen in dwarf novae during outburst. DQ Her is the first well-established IP in which spirals are seen, which are in addition likely persistent because of the system's high mass transfer rate. Spiral structures give an alternative explanation for sidebands of the WD spin frequency that are found in IP light curves. The Doppler tomogram of He II lambda 4686 indicates that a large part of the emission is not disc-like. Spin trails of spectra reveal a pulsation in the He II lambda 4686 emission that is believed to result from reprocessing of X-rays from the WD's magnetic poles in the accretion flow close to the WD. We confirm the previous finding that the pulsation is only visible in the redshifted part of the line when the beam points to the back side of the disc. The absence of reprocessed light from the front side of the disc can be explained by obscuration by the front rim of the disc, but the absence of extra emission from the blueshifted back side of the disc is puzzling. Reprocessing in accretion curtains can be an answer to the problem and can also explain the highly non-Keplerian velocity components that are found in the He II lambda 4686 line. Our spin trails can form a strong test for future accretion curtain models, with the possibility of distinguishing between a spin period of 71 or 142 s. Spin trails of data taken at selected orbital phases show little evidence for a significant contribution of the bright spot to the pulsations and allow us to exclude a recent suggestion that 71 s is the beat period and 70.8 s the spin period

Fermented beverages with health-promoting potential: Past and future perspectives

peer-reviewedFermentation is an ancient form of food preservation, which also improves the nutritional content of foods. In many regions of the world, fermented beverages have become known for their health-promoting attributes. In addition to harnessing traditional beverages for commercial use, there have recently been innovative efforts to develop non-dairy probiotic fermented beverages from a variety of substrates, including soy milk, whey, cereals and vegetable and fruit juices. On the basis of recent developments, it is anticipated that fermented beverages will continue to be a significant component within the functional food market

Evidence for bimodal orbital separations of white dwarf-red dwarf binary stars

We present the results of a radial velocity survey of 20 white dwarf plus M dwarf binaries selected as a follow up to a \textit{Hubble Space Telescope} study that aimed to spatially resolve suspected binaries. Our candidates are taken from the list of targets that were spatially unresolved with \textit{Hubble}. We have determined the orbital periods for 16 of these compact binary candidates. The period distribution ranges from 0.14 to 9.16\,d and peaks near 0.6\,d. The original sample therefore contains two sets of binaries, wide orbits ($\approx100-1000$\,au) and close orbits ($\lesssim1-10$\,au), with no systems found in the $\approx10-100$\,au range. This observational evidence confirms the bimodal distribution predicted by population models and is also similar to results obtained in previous studies. We find no binary periods in the months to years range, supporting the post common envelope evolution scenario. One of our targets, WD\,1504+546, was discovered to be an eclipsing binary with a period of 0.93\,d

A Radial Velocity Study of CTCV J1300-3052

We present time-resolved spectroscopy of the eclipsing, short period cataclysmic variable CTCV J1300-3052. Using absorption features from the secondary star, we determine the radial velocity semi-amplitude of the secondary star to be K2 = 378 \pm 6 km/s, and its projected rotational velocity to be v sin i = 125 \pm 7 km/s. Using these parameters and Monte Carlo techniques, we obtain masses of M1 = 0.79 \pm 0.05 MSun for the white dwarf primary and M2 = 0.198 \pm 0.029 MSun for the M-type secondary star. These parameters are found to be in excellent agreement with previous mass determinations found via photometric fitting techniques, supporting the accuracy and validity of photometric mass determinations in short period CVs.Comment: Accepted for publication in MNRAS (24th January 2012). 10 pages, 9 figures (black and white

The Lowest Mass White Dwarf

Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low mass white dwarf candidates serendipitously discovered in a survey for hypervelocity B-type stars. One of these objects, SDSS J0917+46, has Teff= 11,288 \pm 72 K and log g = 5.48 \pm 0.03; with an estimated mass of 0.17 M_sun, it is the lowest gravity/mass white dwarf currently known. However, 40 of the low mass candidates are normal DA white dwarfs with apparently inaccurate SDSS g magnitudes. We revisit the identification of low mass white dwarf candidates previously found in the SDSS, and conclude that four objects have M < 0.2 M_sun. None of these white dwarfs show excess emission from a binary companion, and radial velocity searches will be necessary to constrain the nature of the unseen companions.Comment: ApJ, accepted versio

Time-resolved spectroscopy of the pulsating CV GW Lib

We present time-resolved optical spectroscopy of the dwarf nova GW Librae during its rare 2007 April superoutburst and compare these with quiescent epochs. The data provide the first opportunity to track the evolution of the principal spectral features. In the early stages of the outburst, the optically thick disc dominates the optical and the line components show clear orbital radial velocity excursions. In the course of several weeks, optically thin regions become more prominent as strong emission lines replace the broad disc absorption. Post-outburst spectroscopy covering the I band illustrates the advantages of Ca II relative to the commonly used Balmer lines when attempting to constrain binary parameters. Due to the lower ionization energy combined with smaller thermal and shear broadening of these lines, a sharp emission component is seen to be moving in between the accretion disc peaks in the Ca II line. No such component is visible in the Balmer lines. We interpret this as an emission component originating on the hitherto unseen mass donor star. This emission component has a mean velocity of similar to -15 +/- 5 km s(-1) which is associated with the systemic velocity., and a velocity semi-amplitude of K-em = 82.2 +/- 4.9 km s(-1). Doppler tomography reveals an asymmetric accretion disc, with the S-wave mapping to a sharp spot in the tomogram with a velocity consistent to what is obtained with line profile fitting. A centre of symmetry analysis of the disc component suggests a very small value for the WD orbital velocity K-1 as is also inferred from double Gaussian fits to the spectral lines. While our conservative dynamical limits place a hard upper limit on the binary mass ratio of q < 0.23, we favour a significantly lower value near q similar to 0.06. Pulsation modelling suggests a white dwarf mass similar to 1 M-circle dot. This, paired with a low-mass donor, near the empirical sequence of an evolved cataclysmic variable close to the period bounce, appears to be consistent with all the observational constraints to date

Pulsations of the Low Mass ZZ Ceti Star HS 1824+6000

Measuring g-mode pulsations of isolated white dwarfs can reveal their interior properties to high precision. With a spectroscopic mass of ~0.51 M_{\odot} (log g = 7.82), the DAV white dwarf HS 1824+6000 is near the transition between carbon/oxygen core and helium core white dwarfs, motivating our photometric search for additional pulsations from the Palomar 60-inch telescope. We confirmed (with much greater precision) the three frequencies: 2.751190 +/- 0.000010 mHz (363.479 sec), 3.116709 +/- 0.000006 mHz (320.851 sec), 3.495113 +/- 0.000009 mHz (286.114 sec), previously found by B. Voss and collaborators, and found an additional pulsation at 4.443120 +/- 0.000012 mHz (225.067 sec). These observed frequencies are similar to those found in other ZZ Ceti white dwarfs of comparable mass (e.g. log g < 8). We hope that future observations of much lower mass ZZ Ceti stars (< 0.4 M_{\odot}) will reveal pulsational differences attributable to a hydrogen covered helium core.Comment: 8 Pages; 4 Figures; Accepted to PASP (scheduled to appear in October issue

Sequencing-Based Analysis of the Bacterial and Fungal Composition of Kefir Grains and Milks from Multiple Sources

peer-reviewedKefir is a fermented milk-based beverage to which a number of health-promoting properties have been attributed. The microbes responsible for the fermentation of milk to produce kefir consist of a complex association of bacteria and yeasts, bound within a polysaccharide matrix, known as the kefir grain. The consistency of this microbial population, and that present in the resultant beverage, has been the subject of a number of previous, almost exclusively culture-based, studies which have indicated differences depending on geographical location and culture conditions. However, culture-based identification studies are limited by virtue of only detecting species with the ability to grow on the specific medium used and thus culture-independent, molecular-based techniques offer the potential for a more comprehensive analysis of such communities. Here we describe a detailed investigation of the microbial population, both bacterial and fungal, of kefir, using high-throughput sequencing to analyse 25 kefir milks and associated grains sourced from 8 geographically distinct regions. This is the first occasion that this technology has been employed to investigate the fungal component of these populations or to reveal the microbial composition of such an extensive number of kefir grains or milks. As a result several genera and species not previously identified in kefir were revealed. Our analysis shows that the bacterial populations in kefir are dominated by 2 phyla, the Firmicutes and the Proteobacteria. It was also established that the fungal populations of kefir were dominated by the genera Kazachstania, Kluyveromyces and Naumovozyma, but that a variable sub-dominant population also exists.The Alimentary Pharmabiotic Centre is a research centre funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan. The authors and their work were supported by SFI CSET grant APC CSET 2 grant 07/CE/B1368

Underperforming policy networks : the biopesticides network in the United Kingdom

Loosely integrated and incomplete policy networks have been neglected in the literature. They are important to consider in terms of understanding network underperformance. The effective delivery and formulation of policy requires networks that are not incomplete or underperforming. The biopesticides policy network in the United Kingdom is considered and its components identified with an emphasis on the lack of integration of retailers and environmental groups. The nature of the network constrains the actions of its agents and frustrates the achievement of policy goals. A study of this relatively immature policy network also allows for a focus on network formation. The state, via an external central government department, has been a key factor in the development of the network. Therefore, it is important to incorporate such factors more systematically into understandings of network formation. Feedback efforts from policy have increased interactions between productionist actors but the sphere of consumption remains insufficiently articulated