Can the turbulent galactic dynamo generate large-scale magnetic fields?

Large-scale magnetic fields in galaxies are thought to be generated by a turbulent dynamo. However the same turbulence also leads to a small-scale dynamo which generates magnetic noise at a more rapid rate. The efficiency of the large-scale dynamo depends on how this noise saturates. We examine this issue taking into account ambipolar drift, which obtains in a galaxy with significant neutral gas. We argue that, (1) the small-scale dynamo generated field does not fill the volume, but is concentrated into intermittent rope like structures. The flux ropes are curved on the turbulent eddy scales. Their thickness is set by the diffusive scale determined by the effective ambipolar diffusion; (2) For a largely neutral galactic gas, the small-scale dynamo saturates, due to inefficient random stretching, when the peak field in a flux rope has grown to a few times the equipartition value; (3) The average energy density in the saturated small-scale field is sub equipartition, since it does not fill the volume; (4) Such fields neither drain significant energy from the turbulence nor convert eddy motion of the turbulence on the outer scale into wavelike motion. The diffusive effects needed for the large-scale dynamo operation are then preserved until the large-scale field itself grows to near equipartition levels.Comment: 11 pages LaTeX, 2 postscript figures, included. Submitted to MNRA

The Use of Poly(vinyl alcohol)-based Hydrogels in Biomedical Applications

Polymers have found increasing favor in biomedical applications due to the greater control that researchers can exert over their properties. Researchers have focused on the development of therapies using biologically compatible polymers due to their ability to limit potentially harmful interactions with the body. This research has led to advances in tissue engineering, controlled and targeted drug delivery, and other biomedical fields, with the goal of improving both the effectiveness and accessibility of health care. Poly(vinyl alcohol) (PVA) hydrogels possess several chemical properties that make them well suited for biomedical applications. These include inertness and stability, biocompatibility, and pH-responsiveness. As a result, PVA based materials have been studied for potential applications in areas of biomedicine such as targeted drug delivery, tissue engineering, and wound healing. This thesis examines the properties of PVA and seeks to understand how the chemical and physical structure affects their properties. It then examines how these properties enhance their utility in potential biomedical applications. Finally, it reviews the research into development of PVA based materials for three different biomedical applications.Chemical Engineerin

What Attracts People to the Life Sciences Industry, and What Motivates Them to Stay?

Life Sciences is seen as a hub for innovation and an industry that is working to improve the world by creating products to eradicate major diseases and improve the lives of people. One major technology company is a part of this rapidly growing industry that even in tough economic conditions provides a lot of scope for growth and development. This growth is driven, in part, by expanded consumer access to health care in the US through the 2010 Patient Protection and Affordable Care Act. Health care spending is expected to increase on average 4.9% during 2014-2018. Growth is also expected in other parts of the world, like Asia, Australia, Middle East, and Africa. This company faces challenges from competitors. As a result of mergers and consolidations between customers, this company\u27s customer base could become even more concentrated. In order to stay ahead of its competitors, this Fortune 500 company needs to spur innovation and attract and retain the best talent

Evolving turbulence and magnetic fields in galaxy clusters

We discuss, using simple analytical models and MHD simulations, the origin and parameters of turbulence and magnetic fields in galaxy clusters. Three physically distinct regimes can be identified in the evolution of cluster turbulence and magnetic fields. Firstly, the fluctuation dynamo will produce microgauss-strong, random magnetic fields during cluster formation and major mergers. Turbulent velocity of about 300 km/s can be maintained at scales 100-200 kpc. The magnetic field is intermittent, has a smaller scale of 20-30 kpc and average strength of 2 microgauss. Secondly, when major mergers end, turbulent speed and magnetic field undergo a power-law decay, decreasing in strength but increasing in scale by a factor of about two. Thirdly, smaller-mass subclusters and cluster galaxies produce turbulent wakes, with turbulent speeds and magnetic field strengths similar to those quoted above. The velocity scales are about 200 kpc and 10 kpc respectively, and the magnetic field scale is about 6 times smaller. Although these wakes may fill only a small fraction of the cluster volume, their area covering factor can be close to unity. So one can potentially reconcile observations that indicate the coexistence of turbulence with ordered filamentary gas structures, as in the Perseus cluster. Random Faraday rotation measure is estimated to be typically 100-200 rad/m^2, in agreement with observations. We predict detectable synchrotron polarization from cluster radio halos at wavelengths 3-6 cm, if observed at sufficiently high resolution (abridged).Comment: 20 pages, 9 figures, Replaced to match version accepted by MNRA

Social Groups and Economic Poverty: A Problem in Measurement

This paper points to some elementary conflicts between the claims of interpersonal and intergroup justice as they manifest themselves in the process of seeking a real-valued index of poverty which is required to satisfy certain seemingly desirable properties. It indicates how ?group-sensitive? poverty measures, similar to the Anand-Sen (1995) ?Gender Adjusted Human Development Index? and the Subramanian-Majumdar (2002) ?Group-Disparity Adjusted Deprivation Index?, may be constructed. Some properties of a specific ?group-sensitive? poverty index are appraised, and the advantage of having a ?flexible? measure which is capable of effecting a tradeoff between the claims of interpersonal and inter-group equality is spelt out. The implications of directly incorporating group disparities into the measurement of poverty for poverty comparisons and anti-poverty policy are also discussed.poverty, measurement, social groups, symmetry, transfer, subgroup sensitivity