STELAR: An experiment in the electronic distribution of astronomical literature

STELAR (Study of Electronic Literature for Astronomical Research) is a Goddard-based project designed to test methods of delivering technical literature in machine readable form. To that end, we have scanned a five year span of the ApJ, ApJ Supp, AJ and PASP, and have obtained abstracts for eight leading academic journals from NASA/STI CASI, which also makes these abstracts available through the NASA RECON system. We have also obtained machine readable versions of some journal volumes from the publishers, although in many instances, the final typeset versions are no longer available. The fundamental data object for the STELAR database is the article, a collection of items associated with a scientific paper - abstract, scanned pages (in a variety of formats), figures, OCR extractions, forward and backward references, errata and versions of the paper in various formats (e.g., TEX, SGML, PostScript, DVI). Articles are uniquely referenced in the database by journal name, volume number and page number. The selection and delivery of articles is accomplished through the WAIS (Wide Area Information Server) client/server models requiring only an Internet connection. Modest modifications to the server code have made it capable of delivering the multiple data types required by STELAR. WAIS is a platform independent and fully open multi-disciplinary delivery system, originally developed by Thinking Machines Corp. and made available free of charge. It is based on the ISO Z39.50 standard communications protocol. WAIS servers run under both UNIX and VMS. WAIS clients run on a wide variety of machines, from UNIX-based Xwindows systems to MS-DOS and macintosh microcomputers. The WAIS system includes full-test indexing and searching of documents, network interface and easy access to a variety of document viewers. ASCII versions of the CASI abstracts have been formatted for display and the full test of the abstracts has been indexed. The entire WAIS database of abstracts is now available for use by the astronomical community. Enhancements of the search and retrieval system are under investigation to include specialized searches (by reference, author or keyword, as opposed to full test searches), improved handling of word stems, improvements in relevancy criteria and other retrieval techniques, such as factor spaces. The STELAR project has been assisted by the full cooperation of the AAS, the ASP, the publishers of the academic journals, librarians from GSFC, NRAO and STScI, the Library of Congress, and the University of North Carolina at Chapel Hill

Synthesis and Hydrothermal Study of (Na,K)M2(PO4)3 (M = Ti, Zr, Hf) Solid Solutions

(Na,K)M2(PO4)3 (M = Ti, Zr, Hf) continuous solid solutions were synthesized by sol-gel and solidstate methods. Cation-exchange reactions in the NaM2(PO4)3–KM2(PO4)3–NaCl–KCl–H2O systems were studied at T = 723 – 973 K and p = 100–200 MPa. The concentration dependences of unit cell parameters of the studied phosphates were found. The sodium/potassium distribution coefficients in the phosphate-fluid systems were functions of the solid solution compositions, that is, the systems behave nonideally. The excess volumes and excess Gibbs functions of solid solutions mixing were fitted to thirdorder polynomials and described in terms of the Margules model. From the comparison of the results obtained Ti-, Zr-, and Hf-systems, we made the conclusion that the titanium phosphates show greater nonideality than zirconium and hafnium phosphates and lower thermodynamic stability to decomposition to double phosphates at high pressures and temperatures

The open XXZ and associated models at q root of unity

The generalized open XXZ model at $q$ root of unity is considered. We review how associated models, such as the $q$ harmonic oscillator, and the lattice sine-Gordon and Liouville models are obtained. Explicit expressions of the local Hamiltonian of the spin ${1 \over 2}$ XXZ spin chain coupled to dynamical degrees of freedom at the one end of the chain are provided. Furthermore, the boundary non-local charges are given for the lattice sine Gordon model and the $q$ harmonic oscillator with open boundaries. We then identify the spectrum and the corresponding Bethe states, of the XXZ and the q harmonic oscillator in the cyclic representation with special non diagonal boundary conditions. Moreover, the spectrum and Bethe states of the lattice versions of the sine-Gordon and Liouville models with open diagonal boundaries is examined. The role of the conserved quantities (boundary non-local charges) in the derivation of the spectrum is also discussed.Comment: 31 pages, LATEX, minor typos correcte

Noncompact SL(2,R) spin chain

We consider the integrable spin chain model - the noncompact SL(2,R) spin magnet. The spin operators are realized as the generators of the unitary principal series representation of the SL(2,R) group. In an explicit form, we construct R-matrix, the Baxter Q-operator and the transition kernel to the representation of the Separated Variables (SoV). The expressions for the energy and quasimomentum of the eigenstates in terms of the Baxter Q-operator are derived. The analytic properties of the eigenvalues of the Baxter operator as a function of the spectral parameter are established. Applying the diagrammatic approach, we calculate Sklyanin's integration measure in the separated variables and obtain the solution to the spectral problem for the model in terms of the eigenvalues of the Q-operator. We show that the transition kernel to the SoV representation is factorized into a product of certain operators each depending on a single separated variable.Comment: 29 pages, 12 figure

Gold-plated Mode of CP-Violation in Decays of B_c Meson from QCD Sum Rules

The model-independent method based on the triangle ideology is implemented to extract the CKM-matrix angle gamma in the decays of doubly heavy long-lived meson B_c. We analyze a color structure of diagrams and conditions to reconstruct two reference-triangles by tagging the flavor and CP eigenstates of D^0 meson in the fixed exclusive channels. The characteristic branching ratios are evaluated in the framework of QCD sum rules.Comment: 11 pages, RevTeX4 file, 4 eps-figure

Doubly heavy baryons Omega_QQ' vs. Xi_QQ' in sum rules of NRQCD

In the framework of two-point sum rules of NRQCD, the masses and couplings of doubly heavy baryons to the corresponding quark currents are evaluated with account of coulomb-like corrections in the system of doubly heavy diquark as well as the contribution of nonperturbative terms determined by the quark, gluon, mixed condensates and the product of gluon and quark condensates. The introduction of nonzero light quark mass destroys the factorization of baryon and diquark correlators even at the perturbative level and provides the better convergency of sum rules. We estimate the difference M_Omega - M_Xi = 100+/- 10 MeV. The ratio of baryonic constants |Z_Omega|^2/|Z_Xi|^2 is equal to 1.3+/-0.2 indicating the violation of SU(3) flavor symmetry for the doubly heavy baryons.Comment: 18 pages, ReVTeX file, 7 eps-figures, references adde

ПЕРСПЕКТИВЫ ПОЛУЧЕНИЯ ПРОРОСТКОВ СЕМЯН ЛУКОВЫХ КУЛЬТУР, ОБОГАЩЕННЫХ СЕЛЕНОМ

Sprouts of agricultural crops seeds are considered to be functional food products with high content of antioxidants. Though seeds of Allium species plants are used in some countries as spices the possibilities of appropriate sprouts utilization have never been investigated so far. Evaluation of perennial and A. cepa seeds biofortification with selenium revealed high nutritional value of the resulting sprouts characterized not only by high selenium content exclusively in a form of selenomethyl selenocysteine (a natural anti carcinogen) but also with high levels of antioxidant activity and high polyphenol content. It was demonstrated that among seven studied representatives of Allium species Allium cepa variety Krasnoye krugevo and perennial onion Allium fistulosum give seeds sprouts with the highest levels of selenium (10500-11000 μg/kg d.w.), polyphenols (9.3-10.8 mg-eq GA/g d.w) and the largest values of antioxidant activity (14.7-17.1 mg-eq GA/g d.w.). Utilization of one g of dried seeds sprouts powder, fortified with selenium provides up to 15.7% of the adequate consumption level of selenium exclusively in a form of selenomethyl selenocysteine possessing powerful anti carcinogenic activity.Проростки семян сельскохозяйственных культур являются функциональными продуктами питания с высоким содержанием природных антиоксидантов. Хотя семена растений рода Allium используют в ряде стран в качестве приправы, однако возможности использования соответствующих проростков в пищу ранее не исследовались. Оценка эффективности обогащения семян многолетних луков и лука репчатого селеном выявила высокую пищевую ценность получаемого продукта, отличающегося не только высоким содержанием селена, причем преимущественно в виде селенометил селеноцистеина, мощного природного антиканцерогена, но также повышенным уровнем антиоксидантной активности и высоким содержанием полифенолов. Установлено, что среди 7 исследованных представителей рода Allium наиболее перспективными являются проростки семян лука репчатого Красное кружево и многолетнего лука батуна, содержащих наиболее высокие уровни селена (10500-11000 мкг/кг с.м), полифенолов (9,3-10,8 мг-экв ГК/1 г с.м.) и имеющих наибольший уровень антиоксидантной активности (14,7-17,1 мг-экв ГК/1 г с.м.). Использование 1 г порошка высушенных проростков лука, обогащенных селеном, обеспечивает поступление в организм человека до 15,7% суточной потребности человека в селене, причем в виде селенометил селеноцистеина, обладающего высокой антиканцерогенной активностью

Identification of Molecular Pathologies Sufficient to Cause Neuropathic Excitability in Primary Somatosensory Afferents Using Dynamical Systems Theory

Pain caused by nerve injury (i.e. neuropathic pain) is associated with development of neuronal hyperexcitability at several points along the pain pathway. Within primary afferents, numerous injury-induced changes have been identified but it remains unclear which molecular changes are necessary and sufficient to explain cellular hyperexcitability. To investigate this, we built computational models that reproduce the switch from a normal spiking pattern characterized by a single spike at the onset of depolarization to a neuropathic one characterized by repetitive spiking throughout depolarization. Parameter changes that were sufficient to switch the spiking pattern also enabled membrane potential oscillations and bursting, suggesting that all three pathological changes are mechanistically linked. Dynamical analysis confirmed this prediction by showing that excitability changes co-develop when the nonlinear mechanism responsible for spike initiation switches from a quasi-separatrix-crossing to a subcritical Hopf bifurcation. This switch stems from biophysical changes that bias competition between oppositely directed fast- and slow-activating conductances operating at subthreshold potentials. Competition between activation and inactivation of a single conductance can be similarly biased with equivalent consequences for excitability. “Bias” can arise from a multitude of molecular changes occurring alone or in combination; in the latter case, changes can add or offset one another. Thus, our results identify pathological change in the nonlinear interaction between processes affecting spike initiation as the critical determinant of how simple injury-induced changes at the molecular level manifest complex excitability changes at the cellular level. We demonstrate that multiple distinct molecular changes are sufficient to produce neuropathic changes in excitability; however, given that nerve injury elicits numerous molecular changes that may be individually sufficient to alter spike initiation, our results argue that no single molecular change is necessary to produce neuropathic excitability. This deeper understanding of degenerate causal relationships has important implications for how we understand and treat neuropathic pain