Crumbling under Pressure

In order for an organism to maintain its form, it must be able to withstand physical perturbation, including the pull of gravity. A recent study in Nature from Porazinski and colleagues (2015) suggests that mechanisms promoting tissue tension are critical to resist the Earth’s downward pull

Actomyosin Pulsing in Tissue Integrity Maintenance during Morphogenesis

The actomyosin cytoskeleton is responsible for many changes in cell and tissue shape. For a long time, the actomyosin cytoskeleton has been known to exhibit dynamic contractile behavior. Recently, discrete actomyosin assembly/disassembly cycles have also been observed in cells. These so-called actomyosin pulses have been observed in a variety of contexts, including cell polarization and division, and in epithelia, where they occur during tissue contraction, folding, and extension. In epithelia, evidence suggests that actomyosin pulsing, and more generally, actomyosin turnover, is required to maintain tissue integrity during contractile processes. This review explores possible functions for pulsing in the many instances during which pulsing has been observed, and also highlights proposed molecular mechanisms that drive pulsing

Spatial Contours of Potential Biomass Crop Production: An Examination of Variations by U.S. Region

The recent and projected status of energy production and consumption in the United States, resulting in substantial dependencies upon foreign oil, has continued to provide pressure on domestic energy security. All told, bio-energy systems, and biomass crop production in particular, will be important elements of national security, economic vitality, and public policy. Using biomass crop estimates based upon models developed at the Oak Ridge National Laboratory and the Department of Energy (DOE) National Renewable Energy Laboratory, we identify potential biomass crop production zones using spatial analysis methods. The Midwest and the South are, by far, the largest regions of potential production. Once potential biomass crop yield is made proportional to estimated land and production costs, the South’s optimal crop zones fall along the Gulf Coast and Atlantic Seaboard, whereas in the Midwest, they are largely in non-metropolitan localities. The implications of these spatial contours for energy policy for alternative biomass crop production are discussed

Anticaries Potential of a Sodium Monofluorophosphate Dentifrice Containing Calcium Sodium Phosphosilicate: Exploratory in situ Randomized Trial

Calcium sodium phosphosilicate (CSPS) is a bioactive glass material that alleviates dentin hypersensitivity and is postulated to confer remineralization of caries lesions. This single-centre, randomized, single (investigator)-blind, placebo-controlled, crossover, in situ study explored whether the addition of 5% CSPS to a nonaqueous fluoride (F) such as sodium monofluorophosphate (SMFP)-containing dentifrice affects its cariostatic ability. Seventy-seven subjects wore 4 gauze-covered enamel specimens with preformed lesions (2 surface-softened and 2 subsurface) placed buccally on their mandibular bilateral dentures for up to 4 weeks. Subjects brushed twice daily with 1 of the 5 study dentifrices: 927 ppm F/5% CSPS, 927 ppm F/0% CSPS, 250 ppm F/0% CSPS, 0 ppm F/5% CSPS, or 0 ppm F/0% CSPS. Specimens were retrieved after either 21 (surface-softened lesions; analyzed by Knoop surface microhardness [SMH]) or 28 days (subsurface lesions; analyzed by transverse microradiography). The enamel fluoride uptake was determined for all specimens using a microbiopsy technique. The concentrations of fluoride and calcium in gauze-retrieved plaque were also evaluated. Higher dentifrice fluoride concentrations led to greater remineralization and fluoridation of both lesion types and increased plaque fluoride concentrations. CSPS did not improve the cariostatic properties of SMFP; there were no statistically significant differences between 927 ppm F/5% CSPS and 927 ppm F/0% CSPS in percent SMH recovery (p = 0.6788), change in integrated mineral loss (p = 0.5908), or lesion depth (p = 0.6622). Likewise, 0 ppm F/5% CSPS did not provide any benefits in comparison to 0 ppm F/0% CSPS. In conclusion, CSPS does not negatively impact nor does it improve the ability of an SMFP dentifrice to affect remineralization of caries lesions

Stability of racemic and chiral steady states in open and closed chemical systems

The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived.Comment: 25 pages, 1 figure. To appear in Physics Letters A (2008

Complete homochirality induced by the nonlinear autocatalysis and recycling

A nonlinear autocatalysis of a chiral substance is shown to achieve homochirality in a closed system, if the back-reaction is included. Asymmetry in the concentration of two enantiomers or the enantiometric excess increases due to the nonlinear autocatalysis. Furthermore, when the back-reaction is taken into account, the reactant supplied by the decomposition of the enantiomers is recycled to produce more and more the dominant one, and eventually the homochirality is established.Comment: 4 pages, 2 figure

Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector

Wind-induced pointing errors are a serious concern for large-aperture high-frequency radio telescopes. In this paper, we describe the implementation of an optical quadrant detector instrument that can detect and provide a correction signal for wind-induced pointing errors on the 100m diameter Green Bank Telescope (GBT). The instrument was calibrated using a combination of astronomical measurements and metrology. We find that the main wind-induced pointing errors on time scales of minutes are caused by the feedarm being blown along the direction of the wind vector. We also find that wind-induced structural excitation is virtually non-existent. We have implemented offline software to apply pointing corrections to the data from imaging instruments such as the MUSTANG 3.3 mm bolometer array, which can recover ~70% of sensitivity lost due to wind-induced pointing errors. We have also performed preliminary tests that show great promise for correcting these pointing errors in real-time using the telescope's subreflector servo system in combination with the quadrant detector signal.Comment: 17 pages, 11 figures; accepted for publication in PAS

CMS Search Plans and Sensitivity to New Physics using Dijets

CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 pb$^{-1}$ of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions

Chinese medical teachers' cultural attitudes influence palliative care education: a qualitative study

Background!#!China holds one fifth of the world's population and faces a rapidly aging society. In its ambition to reach a health care standard comparable to developed countries by 2030, the implementation of palliative care gains special importance. Until now, palliative care education in China is limited and disparate. This study aims to explore and determine factors that have impeded the development and implementation of palliative care education in China.!##!Methods!#!We conducted semi-structured interviews with n=28 medical teachers from seven Chinese universities. Interviews were transcribed, and thematic analysis applied.!##!Results!#!Three themes with two subthemes were constructed from data analysis. Theme 1 covers the still ambivalent perception of palliative care and palliative care education among participants. The second theme is about cultural attitudes around death and communication. The third theme reflects participants' pragmatic general understanding of teaching. All themes incorporate obstacles to further implementation of palliative care and palliative care education in China.!##!Conclusions!#!According to the study participants, palliative care implementation through palliative care education in China is hindered by cultural views of medical teachers, their perception of palliative care and palliative care education, and their understanding of teaching. The study demonstrates that current attitudes may work as an obstacle to the implementation of palliative care within the health care system. Approaches to changing medical teachers' views on palliative care and palliative care education and their cultural attitudes towards death and dying are crucial to further promote the implementation of palliative care in China

Physical changes during Z-track movement in Sco X-1 on the flaring branch

We present results of a detailed study of X-ray flaring in the Z-track source Sco X-1 in a highly super-Eddington state made using high quality Rossi-XTE data from the PCA and HEXTE instruments. The emission model successfully used to explain the dipping LMXB, and other classes of LMXB in recent years, was applied to study the physical evolution along the Z-track which remains a major problem. This model consists of blackbody emission from the neutron star plus Comptonized emission from an extended accretion disk corona. As found in earlier work, major changes take place in the neutron star blackbody emission with kT increasing in flaring, and the blackbody radius R_BB increasing substantially to a maximum value of 9.4 +/- 0.6 km, consistent with the radius of the neutron star, after which R_BB decreases. Thus this result is a measurement of neutron star radius. The behaviour of Sco X-1 in flaring is compared with our previous results for the strong flaring that takes place in the bright dipping, flaring LMXB X 1624-490. Remarkably, during movement along the Normal Branch towards the apex with the Flaring Branch, the luminosities of both spectral components decrease, suggesting the possibility that Mdot may decrease on the Normal Branch, contrary to the widely-held view that Mdot increases monotonically along the Z-track. During flaring, we detect for the first time an increase of the Comptonization cut-off energy which may suggest heating of the ADC plasma by the neutron star flare. The energy of a broad Gaussian line at 6.4 keV does not change, but the intensity of the line increases in flaring suggesting either an increase in ADC size in flaring or the effects of irradiation by the neutron star.Comment: 12 pages including 8 figures, Astronomy and Astrophysics in press; reference list correcte