Evaluating the Potential of Using 5-Azacytidine as an Epimutagen

A number of early flowering lines were induced when 5-azacytidine was applied to germinating flax (Linum usitatissimum L.) seed. The genetics of these lines indicate that the induced changes are epigenetic and probably result from demethylation of the genomic DNA at loci that affect flowering age. Although the growth and development of three stable early flowering lines are altered and the percentage of filled seed was reduced in all three lines compared with controls, measures of seed productivity demonstrated that harvest index was unaffected in two of the lines. In the third, harvest index was lower than normal and both seed set per capsule and seed mass per 100 seed were reduced. Furthermore, six generations after induction this line began to display relatively high levels of polyembryony. The late appearance of this twinning and other aspects related to working with lines induced by 5-azacytidine and using 5-azacytidine as an epimutagen are discussed

Pneumoconiosis in Great Britain

Autor daje pregled sadašnjeg stanja problema pneumokonioze u Velikoj Britaniji. Nakon kratkog historijskog uvoda opisana su zvanja, u kojima su radnici izvrgnuti opasnosti od pneumokonioze. Tu se ističe kopanje ugljena kao najvažnija industrija u Velikoj Britaniji. U toj je industriji zaposleno ukupno 600.000 ljudi, a u razdoblju od 1939.-1947. bilo je prijavljeno 19.156 profesionalnih·oboljenja. Zatim autor prelazi na opis rentgenološke klasifikacije pneumokonioza i daje pregled patologije pneumokonioze. Posebno se poglavlje bavi istraživanjem pneumokonioze, koje se danas vrši u različitim institucijama u Velikoj Britaniji. Fizikalna se istraživanja bave skupljanjem prašine, metodama za kontinuirano uzimanje uzoraka, frakcioniranjem zrakom prenošene prašine i borbom protiv prašine. U kemijskim istraživanjima glavno mjesto zauzimaju metode kemijske analize, fizikalne metode za određivanje slobodnog silicijeva dioksida, istraživanje topljivosti slobodnog silicijeva dioksida i silikatnih minerala.The author reviews the problem or pneumoconiosis in Great Britain. After a brief historical introduction the following topics are discussed: trades affected (free silica exposure, silicate exposure, mixed stone dust exposure, mixed stone and carbon coal dust exposure); classification of pneumoconiosis by X-rays (simple pneumoconiosis, progressive massive" fibrosis); pathology of pneumoconiosis: pneumoconiosis research (physical, chemical, biological and medical)

Eksperimentalna infektivna pneumokonioza

Quartz and coal-mine dusts were introduced into the lungs of rats by inhalation, in a high concentration, for four months, and then groups of these dusted animals were infected with a virulent strain of human tubercle bacillus (37 Rv). Dusting was continued for a further period of ten months in the case of coal-mine dust. No variation in lung pathology was seen in the quartz groups, although both produced classical silicotic nodules. In the coal-mine dust the infective group showed slightly more fibrosis, diffuse in nature, than either the noninfected or the tuberculous control group. These are preliminary experiments, and the results must be considered as both tentative and not very conclusive. Work is being continued.Prašina kvarca i ugljenokopna prašina bile su unesene inhalacijom u pluća štakora. Koncentracija je bila visoka, a ekspozicija je trajala 4 mjeseca Nakon toga su grupe zaprašenih životinja bile inficirane virulentnim sojom humanog tuberkuloznog bacila (H 37 Rv). Kod grupe životinja, koje su bile izvrgnute djelovanju ugljenokopne prašine, nastavljeno je zaprašivanje daljih 10 mjeseci. U kvarcnim grupama nije bilo razlike s obzirom na patologiju pluća, iako je u obje grupe došlo do stvaranja klasičnih silikotičnih čvorova. U grupi životinja, koje su bile izvrgnute ugljenokopnoj prašini, nađeno je nešto više fibroze, koja je bila difuzna, nego bilo u neinficiranoj ili tuberkuloznoj kontrolnoj grupi. Ti eksperimenti su preliminarni i ne treba ih smatrati previše konkluzivnima. Rad se nastavlja

Pre-flight characteristics of Hecht vaults

This study reports the techniques used by gymnasts to perform the Hecht vault and compares them with techniques used for the handspring somersault vault (Takei and Kim, 1990). Data were obtained on 27 elite gymnasts performing the Hecht vault at the 1993 Canadian National Championships using two-dimensional video analysis with the Direct Linear Transformation (DLT) technique. The maximum height reached by the mass centre during postflight was significantly correlated (p < 0.001) with the vertical velocity of the mass centre and the body angle at horse contact. The backwards rotation of the body was significantly correlated (p = 0.002) with the shoulder angle at horse contact. The competition score was significantly correlated (p = 0.031) with the body angle at horse contact and the maximum height of the mass centre during postflight. For the Hecht vault the gymnasts had longer, lower and faster preflights with slower rotation at horse contact compared with the handspring somersault vaults

Recent Progress in Shearlet Theory: Systematic Construction of Shearlet Dilation Groups, Characterization of Wavefront Sets, and New Embeddings

The class of generalized shearlet dilation groups has recently been developed to allow the unified treatment of various shearlet groups and associated shearlet transforms that had previously been studied on a case-by-case basis. We consider several aspects of these groups: First, their systematic construction from associative algebras, secondly, their suitability for the characterization of wavefront sets, and finally, the question of constructing embeddings into the symplectic group in a way that intertwines the quasi-regular representation with the metaplectic one. For all questions, it is possible to treat the full class of generalized shearlet groups in a comprehensive and unified way, thus generalizing known results to an infinity of new cases. Our presentation emphasizes the interplay between the algebraic structure underlying the construction of the shearlet dilation groups, the geometric properties of the dual action, and the analytic properties of the associated shearlet transforms.Comment: 28 page

Nanotube Piezoelectricity

We combine ab initio, tight-binding methods and analytical theory to study piezoelectric effect of boron nitride nanotubes. We find that piezoelectricity of a heteropolar nanotube depends on its chirality and diameter and can be understood starting from the piezoelectric response of an isolated planar sheet, along with a structure specific mapping from the sheet onto the tube surface. We demonstrate that coupling between the uniaxial and shear deformation are only allowed in the nanotubes with lower chiral symmetry. Our study shows that piezoelectricity of nanotubes is fundamentally different from its counterpart in three dimensional (3D) bulk materials.Comment: 4 pages, with 3 postscript figures embedded. Uses REVTEX4 macros. Also available at http://www.physics.upenn.edu/~nsai/preprints/bn_piezo/index.htm

Inflation from Susy quantum cosmology

We propose a realization of inverted hybrid inflation scenario in the context of n=2 supersymmetric quantum cosmology. The spectrum of density fluctuations is calculated in the de Sitter regimen as a function of the gravitino and the Planck mass, and explicit forms for the wave function of the universe are found in the WKB regimen for a FRW closed and flat universes.Comment: 9 pages, one figure, to appear in Phys. Rev.

Efficient Resolution of Anisotropic Structures

We highlight some recent new delevelopments concerning the sparse representation of possibly high-dimensional functions exhibiting strong anisotropic features and low regularity in isotropic Sobolev or Besov scales. Specifically, we focus on the solution of transport equations which exhibit propagation of singularities where, additionally, high-dimensionality enters when the convection field, and hence the solutions, depend on parameters varying over some compact set. Important constituents of our approach are directionally adaptive discretization concepts motivated by compactly supported shearlet systems, and well-conditioned stable variational formulations that support trial spaces with anisotropic refinements with arbitrary directionalities. We prove that they provide tight error-residual relations which are used to contrive rigorously founded adaptive refinement schemes which converge in $L_2$. Moreover, in the context of parameter dependent problems we discuss two approaches serving different purposes and working under different regularity assumptions. For frequent query problems, making essential use of the novel well-conditioned variational formulations, a new Reduced Basis Method is outlined which exhibits a certain rate-optimal performance for indefinite, unsymmetric or singularly perturbed problems. For the radiative transfer problem with scattering a sparse tensor method is presented which mitigates or even overcomes the curse of dimensionality under suitable (so far still isotropic) regularity assumptions. Numerical examples for both methods illustrate the theoretical findings