Temperature distribution in a stellar atmosphere diagnostic basis

A stellar chromosphere is considered a region where the temperature increases outward and where the temperature structure of the gas controls the shape of the spectral lines. It is shown that lines which have collision-dominated source sink terms, like the Ca(+) and Mg(+) H and K lines, can be used to obtain the distribution of temperature with height from observed line profiles. Intrinsic emission lines and geometrical emission lines are found in spectral regions where the continuum is depressed. In visual regions, where the continuum is not depressed, emission core in absorption lines are attributed to reflections of intrinsic emission lines

Linguistic Reflection in Java

Reflective systems allow their own structures to be altered from within. Here we are concerned with a style of reflection, called linguistic reflection, which is the ability of a running program to generate new program fragments and to integrate these into its own execution. In particular we describe how this kind of reflection may be provided in the compiler-based, strongly typed object-oriented programming language Java. The advantages of the programming technique include attaining high levels of genericity and accommodating system evolution. These advantages are illustrated by an example taken from persistent programming which shows how linguistic reflection allows functionality (program code) to be generated on demand (Just-In-Time) from a generic specification and integrated into the evolving running program. The technique is evaluated against alternative implementation approaches with respect to efficiency, safety and ease of use.Comment: 25 pages. Source code for examples at http://www-ppg.dcs.st-and.ac.uk/Java/ReflectionExample/ Dynamic compilation package at http://www-ppg.dcs.st-and.ac.uk/Java/DynamicCompilation

A Five-year Spectroscopic and Photometric Campaign on the Prototypical alpha Cygni Variable and A-type Supergiant Star Deneb

Deneb is often considered the prototypical A-type supergiant, and is one of the visually most luminous stars in the Galaxy. A-type supergiants are potential extragalactic distance indicators, but the variability of these stars needs to be better characterized before this technique can be considered reliable. We analyzed 339 high resolution echelle spectra of Deneb obtained over the five-year span of 1997 through 2001 as well as 370 Stromgren photometric measurements obtained during the same time frame. Our spectroscopic analysis included dynamical spectra of the H-alpha profile, H-alpha equivalent widths, and radial velocities measured from Si II 6347, 6371. Time-series analysis reveals no obvious cyclic behavior that proceeds through multiple observing seasons, although we found a suspected 40 day period in two, non-consecutive observing seasons. Some correlations are found between photometric and radial velocity data sets, and suggest radial pulsations at two epochs. No correlation is found between the variability of the H-alpha profiles and that of the radial velocities or the photometry. Lucy (1976) found evidence that Deneb was a long period single-lined spectroscopic binary star, but our data set shows no evidence for radial velocity variations caused by a binary companion.Comment: 49 pages, 9 figures, 5 tables, accepted for publication in the Astronomical Journa

Stretching Homopolymers

Force induced stretching of polymers is important in a variety of contexts. We have used theory and simulations to describe the response of homopolymers, with $N$ monomers, to force ($f$) in good and poor solvents. In good solvents and for {{sufficiently large}} $N$ we show, in accord with scaling predictions, that the mean extension along the $f$ axis $\sim f$ for small $f$, and $\sim f^{{2/3}}$ (the Pincus regime) for intermediate values of $f$. The theoretical predictions for \la Z\ra as a function of $f$ are in excellent agreement with simulations for N=100 and 1600. However, even with N=1600, the expected Pincus regime is not observed due to the the breakdown of the assumptions in the blob picture for finite $N$. {{We predict the Pincus scaling in a good solvent will be observed for $N\gtrsim 10^5$}}. The force-dependent structure factors for a polymer in a poor solvent show that there are a hierarchy of structures, depending on the nature of the solvent. For a weakly hydrophobic polymer, various structures (ideal conformations, self-avoiding chains, globules, and rods) emerge on distinct length scales as $f$ is varied. A strongly hydrophobic polymer remains globular as long as $f$ is less than a critical value $f_c$. Above $f_c$, an abrupt first order transition to a rod-like structure occurs. Our predictions can be tested using single molecule experiments.Comment: 24 pages, 7 figure

A community pharmacy weight management programme: an evaluation of effectiveness

<p>Background: Community pharmacies may offer an accessible way of delivering weight-management programmes but there have been few trials that use clinically significant weight loss outcomes, objective measures of weight and follow-up to 12 months. We aimed to evaluate weight change among patients who used the Counterweight weight management programme delivered by community pharmacies.</p> <p>Methods: The Counterweight Programme was introduced into community pharmacies in Fife, Scotland in 2009 for patients with a BMI ≥ 30 kg/m2 or a BMI ≥ 28 kg/m2 with a co-morbidity in localities in which Counterweight was not available at GP practices. The aim was to achieve an energy deficit of 500-600 kcal per day. Counterweight specialist dietitians delivered training, support and patient information materials to community pharmacies. Patient weight was measured by pharmacy staff at each weight management session. Weight data recorded at each weight management session were used to estimate weight change and attendance at 3, 6 and 12 months.</p> <p>Results: Between March 2009 and July 2012, 458 patients were enrolled by the community pharmacies. Three-quarters of patients were women, mean age was 54 (SD 7.4) years and mean BMI 36.1 (SD 5.9) kg/m2. Of 314 patients enrolled for at least 12 months, 32 (10.2% on an intention to treat basis) had achieved the target weight loss of ≥5%; this was 41.6% of those who attended at 12 months representing a mean weight loss of 4.1 kg. Using Last Observation Carried Forward, 15.9% achieved the target weight loss within 12 months of enrolling. There was no significant effect of sex, baseline BMI or age on weight loss.</p> <p>Conclusions: The Counterweight pharmacy programme has a similar effectiveness to other primary care based weight management programmes and should be considered as part of a range of services available to a community to manage overweight and obesity.</p&gt

Compaction and tensile forces determine the accuracy of folding landscape parameters from single molecule pulling experiments

We establish a framework for assessing whether the transition state location of a biopolymer, which can be inferred from single molecule pulling experiments, corresponds to the ensemble of structures that have equal probability of reaching either the folded or unfolded states (Pfold = 0.5). Using results for the forced-unfolding of a RNA hairpin, an exactly soluble model and an analytic theory, we show that Pfold is solely determined by s, an experimentally measurable molecular tensegrity parameter, which is a ratio of the tensile force and a compaction force that stabilizes the folded state. Applications to folding landscapes of DNA hairpins and leucine zipper with two barriers provide a structural interpretation of single molecule experimental data. Our theory can be used to assess whether molecular extension is a good reaction coordinate using measured free energy profiles.Comment: 6 pages, 4 figures, Phys. Rev. Lett. (in press

Nearby Microlensing Events - Identification of the Candidates for the SIM

The Space Interferometry Mission (SIM) is the instrument of choice when it comes to observing astrometric microlensing events where nearby, usually high-proper-motion stars (``lenses''), pass in front of more distant stars (``sources''). Each such encounter produces a deflection in the source's apparent position that when observed by SIM can lead to a precise mass determination of the nearby lens star. We search for lens-source encounters during the 2005-2015 period using Hipparcos, ACT and NLTT to select lenses, and USNO-A2.0 to search for the corresponding sources, and rank these by the SIM time required for a 1% mass measurement. For Hipparcos and ACT lenses, the lens distance and lens-source impact parameter are precisely determined so the events are well characterized. We present 32 candidates beginning with a 61 Cyg A event in 2012 that requires only a few minutes of SIM time. Proxima Centauri and Barnard's star each generate several events. For NLTT lenses, the distance is known only to a factor of 3, and the impact parameter only to 1''. Together, these produce uncertainties of a factor ~10 in the amount of SIM time required. We present a list of 146 NLTT candidates and show how single-epoch CCD photometry of the candidates could reduce the uncertainty in SIM time to a factor of ~1.5.Comment: ApJ accepted, 31 pages (inc. 5 tables), 5 figures. t SIM refine