Nitrogen Abundances and the Distance Moduli of the Pleiades and Hyades

Recent reanalyses of HIPPARCOS parallax data confirm a previously noted discrepancy with the Pleiades distance modulus estimated from main-sequence fitting in the color-magnitude diagram. One proposed explanation of this distance modulus discrepancy is a Pleiades He abundance that is significantly larger than the Hyades value. We suggest that, based on our theoretical and observational understanding of Galactic chemical evolution, nitrogen abundances may serve as a proxy for helium abundances of disk stars. Utilizing high-resolution near-UV Keck/HIRES spectroscopy, we determine N abundances in the Pleiades and Hyades dwarfs from NH features in the 3330 Ang region. While our Hyades N abundances show a modest 0.2 dex trend over a 800 K Teff range, we find the Pleiades N abundance (by number) is 0.13+/-0.05 dex lower than in the Hyades for stars in a smaller overlapping Teff range around 6000 K; possible systematic errors in the lower Pleiades N abundance result are estimated to be at the <0.10 dex level. Our results indicate [N/Fe]=0 for both the Pleiades and Hyades, consistent with the ratios exhibited by local Galactic disk field stars in other studies. If N production is a reliable tracer of He production in the disk, then our results suggest the Pleiades He abundance is no larger than that in the Hyades. This finding is supported by the relative Pleiades-Hyades C, O, and Fe abundances interpreted in the current context of Galactic chemical evolution, and is resistant to the effects on our derived N abundances of a He abundance difference like that needed to explain the Pleiades distance modulus discrepancy. A physical explanation of the Pleiades distance modulus discrepancy does not appear to be related to He abundance.Comment: Accepted for publication in the Publications of the Astronomical Society of the Pacifi

Beryllium and Iron Abundances of the Solar Twins 16 Cygni A and B

Red (signal-to-noise ratio of S/N ~ 1000 pixel-1) and ultraviolet (S/N 100 pixel-1) Keck High Resolution Echelle Spectrograph (HIRES) spectra (R ~ 45,000 = 3 pixels) are used to derive the iron (Fe) and beryllium (Be) abundances in each of the solar twins 16 Cygni A and B. Self-consistent spectroscopic solutions yield, for 16 Cyg A and B, respectively, Teff = 5795 ± 20 and 5760 ± 20 K, log g = 4.30 ± 0.06 and 4.40 ± 0.06, ξ = 1.25 ± 0.05 and 1.12 ± 0.05 km s-1, and [Fe/H] = 0.04 ± 0.02 and 0.06 ± 0.02. If Fe is used as a surrogate for metallicity, this represents an average metallicity of 11% ± 5% above solar. These are in excellent agreement with other recent studies of this (wide) binary. Whereas it can be argued that no single study is conclusive, the consistent findings of these various studies offer compelling evidence that these stars have just barely supersolar metallicity, that 16 Cyg A is just hotter than the Sun, and that 16 Cyg B is just cooler. We have previously reported (based on Keck HIRES data) a difference in the lithium (Li) abundances of these stars of at least a factor of 4.5; for 16 Cyg A we detected a Li abundance of a factor of ~2 above solar, and for 16 Cyg B we placed a conservative upper limit of a factor of ~3 below solar. We detect Be in both stars and find that, if there is any difference between them, it must be much smaller—conservatively no more than 0.2 dex. Evidence suggests that solar-type stars deplete their surface Li abundance during the main sequence, a feat that the standard stellar evolution theory has, thus far, been unable to accomplish. Whatever physical mechanism depletes the surface Li abundance must create far less of a spread in the Be abundances than it does in the Li abundances. We find that our Li and Be results are consistent with the predictions of Yale models that include rotationally induced mixing driven by angular momentum loss. Our results provide no evidence for a small (~0.05 dex) enhancement in the 9Be abundance of the A component relative to the B component expected if the stars\u27 Li abundance difference was due to accretion of planetary material by the A component. Given the errors, however, neither are we able to firmly preclude such a signature

Lithium in a Short-Period Tidally Locked Binary of M67: Implications for Stellar Evolution, Galactic Lithium Evolution, and Cosmology

In open clusters, late-F stars exhibit a Li maximum (the Li \u27peak\u27 region) at lower abundance with age, which could be due either to stellar depletion or Galactic Li enrichment (or some other cause). We have observed a short-period tidally locked binary (SPTLB) on the Li peak region in the old cluster M67 to distinguish between alternatives. SPTLBs which synchronized in the early pre-main sequence would avoid the rotational mixing which, according to Yale models, may be responsible for depleting Li with age in open cluster dwarfs. We find that both components of the M67 SPTLB have a Li abundance lying about a factor of 2 or more above any other M67 single star and about a factor of 3 or more above the mean Li peak region abundance in M67. Our results suggest that the initial Li abundance in M67 is at least as high as approximately 3.0 = 12 + log (NLi/NH). Our high M67 SPTLB Li abundance and those in other clusters support the combination of Zahn\u27s tidal circularization and the Yale rotational mixing theories and may indicate that the halo Li plateau (analogous to the cluster Li peak region) abundance has been depleted from a higher primordial value. Implications are discussed

Detection of Silver in Metal-Poor Stars

The resonance lines of neutral silver appearing at 3280, 3382 Å in the near-ultraviolet spectral region have been identified on Keck I HIRES spectra of four halo stars with metallicities -1.3 ≥ [Fe/H] ≥ -2.2. This represents the first detection in metal-poor stars of an element in the atomic number range 41 ≤ Z ≤ 55. The mean relative silver abundance is [Ag/Fe] +0.2, with little star-to-star variation. Silver abundance upper limits in three other metal-poor stars are consistent with this mean value. The modest overabundance of silver is similar to the overabundances in this metallicity range exhibited by other neutron-capture elements whose primary nucleosynthesis origin is the r-process (such as europium and dysprosium)

Video-Based Communication Assessment: Development of an Innovative System for Assessing Clinician-Patient Communication

Good clinician-patient communication is essential to provide quality health care and is key to patient-centered care. However, individuals and organizations seeking to improve in this area face significant challenges. A major barrier is the absence of an efficient system for assessing clinicians\u27 communication skills and providing meaningful, individual-level feedback. The purpose of this paper is to describe the design and creation of the Video-Based Communication Assessment (VCA), an innovative, flexible system for assessing and ultimately enhancing clinicians\u27 communication skills. We began by developing the VCA concept. Specifically, we determined that it should be convenient and efficient, accessible via computer, tablet, or smartphone; be case based, using video patient vignettes to which users respond as if speaking to the patient in the vignette; be flexible, allowing content to be tailored to the purpose of the assessment; allow incorporation of the patient\u27s voice by crowdsourcing ratings from analog patients; provide robust feedback including ratings, links to highly rated responses as examples, and learning points; and ultimately, have strong psychometric properties. We collected feedback on the concept and then proceeded to create the system. We identified several important research questions, which will be answered in subsequent studies. The VCA is a flexible, innovative system for assessing clinician-patient communication. It enables efficient sampling of clinicians\u27 communication skills, supports crowdsourced ratings of these spoken samples using analog patients, and offers multifaceted feedback reports

Crystallization and lamellar nanosheet formation of an aromatic dipeptoid

An aromatic peptoid analogue of the diphenylalanine dipeptide self-assembles in aqueous solution and the first crystal structure was obtained for this class of compound. This reveals molecular packing stabilized by networks of hydrogen bonds. Free-floating nanosheet lamellar structures are observed in solution, which form via cooperative intermolecular interactions driven by π stacking

Subspace Correction for Constraints

We demonstrate that it is possible to construct operators that stabilize the constraint-satisfying subspaces of computational problems in their Ising representations. We provide an explicit recipe to construct unitaries and associated measurements for some such constraints. The stabilizer measurements allow the detection of constraint violations, and provide a route to recovery back into the constrained subspace. We call this technique ``subspace correction". As an example, we explicitly investigate the stabilizers using the simplest local constraint subspace: Independent Set. We find an algorithm that is guaranteed to produce a perfect uniform or weighted distribution over all constraint-satisfying states when paired with a stopping condition: a quantum analogue of partial rejection sampling. The stopping condition can be modified for sub-graph approximations. We show that it can prepare exact Gibbs distributions on $d-$regular graphs below a critical hardness $\lambda_d^*$ in sub-linear time. Finally, we look at a potential use of subspace correction for fault-tolerant depth-reduction. In particular we investigate how the technique detects and recovers errors induced by Trotterization in preparing maximum independent set using an adiabatic state preparation algorithm.Comment: 12 + 4 pages, 6 figure

The Ursinus Weekly, December 10, 1956

Christmas parties for children given by three groups • Holy Communion to be held Dec. 13 • Class of 1959 sponsors Dogpatch drag Dec. 8 • Morning watch to be held by SWC • Weekly staffs have Christmas dinner, Dec. 4 • APO offers share-the-ride plan to students • Nineteenth annual Messiah presented Thursday, Dec. 6 • MSGA council issues warnings on speeding, parking • Y groups hear two speakers Wed. • SRC presents Coffee klatch on Fridays • Graduation programs on sale during this week • Annual Christmas ball to take place Wednesday night • UC Help Hungary drive ends Friday • Resumes for interviews due on Friday, Dec. 14 • Lantern appears tomorrow • Editorial: It\u27s an idiom; Our morality and the foreign policy • Letters to the editor • Christmas song • Old dog, new tricks • Modern Christmas carol • Intramurals move into full swing; Derr, Curtis III are teams to beat • Cubs top Pharm; Could go unbeaten • Court belles top alumni, 56-36, Sat. • Famous, Donnelly receive Eastern grid honors • Bears seek win Tues. night after dropping four straight • Grapplers to open on Jan. 12; Heavy divisions very weak • Althouse - Haverstick engagement • Inquirer releases Phila. best-selling book list • McClures to give party for Jr. and Sr. women • Ursinus Circle has Christmas music program • Twelve students to appear in 1957 college Who\u27s who • Pre-med, chem societies to have joint meeting • Schrull - Engel engagement • Curtain Club group sees Measure for measure • Class rules are published by two student councilshttps://digitalcommons.ursinus.edu/weekly/1418/thumbnail.jp

Hepatitis B assays in serum, plasma and whole blood on filter paper

BACKGROUND: Screening and determining the immune status of individuals for hepatitis B is usually done by detecting hepatitis B surface antigen (HBsAg) and hepatitis B surface antigen-specific antibodies (HBsAb). In some countries with the highest viral burden, performing these assays is currently impractical. This paper explores the use of filter paper as a blood specimen transport medium. METHODS: Samples, chosen from routine clinical laboratory pool, were applied and dried onto filter paper. Eluates, from the paper samples, were analyzed as routine clinical specimens on ADVIA Centaur 5634® immunoassay analyzers using the standard HBsAg and HBsAb kits. Dried blood samples were subjected to a range of environmental conditions in order to assess stability. RESULTS: After drying and elution the assays showed linearity and precision comparable to clinical assays performed on fresh serum. Elutions at various times during a 149 day incubation period showed very little variability in the Index numbers. All analytes were temperature stable except for a decrease in the HBsAg signal at 42°C. CONCLUSIONS: Filter paper is an acceptable storage and transport medium for serum to be used in the detection of hepatitis B markers if atmospheric variability can be controlled. HBsAg, HBsAb and HBcAb are all stable for at least five months under storage conditions below room temperature. Drying specimens, particularly serum, on filter paper at remote locations, offers a reasonable solution to the problem of hepatitis surveillance in underdeveloped regions, although some attempt at temperature control might be desirable