A Low-Cost, Rapidly Integrated Debubbler (RID) Module for Microfluidic Cell Culture Applications.

Microfluidic platforms use controlled fluid flows to provide physiologically relevant biochemical and biophysical cues to cultured cells in a well-defined and reproducible manner. Undisturbed flows are critical in these systems, and air bubbles entering microfluidic channels can lead to device delamination or cell damage. To prevent bubble entry into microfluidic channels, we report a low-cost, Rapidly Integrated Debubbler (RID) module that is simple to fabricate, inexpensive, and easily combined with existing experimental systems. We demonstrate successful removal of air bubbles spanning three orders of magnitude with a maximum removal rate (dV/dt)max = 1.5 mL min-1, at flow rates required to apply physiological wall shear stress (1-200 dyne cm-2) to mammalian cells cultured in microfluidic channels.

Significance of bending restraints for the stability of helical polymer conformations.

We performed parallel-tempering Monte Carlo simulations to investigate the formation and stability of helical tertiary structures for flexible and semiflexible polymers, employing a generic coarse-grained model. Structural conformations exhibit helical order with tertiary ordering into single helices, multiple helical segments organized into bundles, and disorganized helical arrangements. For both bending-restrained semiflexible and bending-unrestrained flexible helical polymers, the stability of the structural phases is discussed systematically by means of hyperphase diagrams parametrized by suitable order parameters, temperature, and torsion strength. This exploration lends insight into the restricted flexibility of biological polymers such as double-stranded DNA and proteins.

Foundation for a natural right to health care.

Discussions concerning whether there is a natural right to health care may occur in various forms, resulting in policy recommendations for how to implement any such right in a given society. But health care policies may be judged by international standards including the United Nations' Universal Declaration of Human Rights (UDHR). The rights enumerated in the UDHR are grounded in traditions of moral theory, a philosophical analysis of which is necessary in order to adjudicate the value of specific policies designed to enshrine rights such as a right to health care. We begin with an overview of the drafting of the UDHR and highlight the primary influence of natural law theory in validating the rights contained therein. We then provide an explication of natural law theory by reference to the writings of Thomas Aquinas, as well as elucidate the complementary "capabilities approach" of Martha Nussbaum. We conclude that a right to health care ought to be guaranteed by the state.