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

Nitrogen fertiliser residues for wheat cropping in subtropical Australia

Applied nitrogen (N) recovered by fertilised wheat and by successive wheat crops in a 4-crop sequence (1987-90) was studied by applying 15N-depleted ammonium nitrate (0, 2.5, and 7.5 g/m2) to a Vertisol in the summer-dominant rainfall region of northern Australia. Recoveries of applied N by each of the 4 crops in order of cropping sequence were 60.3¦ 4.2, 4.4 ¦ 2.3, 1 . 3 ¦ 0.49, and 0- 8 ¦ 0.56%, there being no effect of 2 tillage treatments, conventional tillage (CT) and no till (NT), on uptake of applied N. There was very low recovery of residual fertiliser N after the first wheat crop was harvested; usually <lo% of the applied N was recovered. There was evidence of a substantial N carryover benefit where fertiliser N (7.5 g/m2) was applied in 1987, but not when applied at the same rate in 1988 or 1989. Carryover effect was shown only when fertiliser N was applied after a long fallow when antecedent NOT-N was already high (100-150 v. 30-55 kg/ha with a normal summer fallow). Carryover of subsoil NO3 -N from a single N fertiliser application to the crop, as occurred with application in 1987, will provide useful buffer for declining N supplies of soil N in seasons of good crop response. Routine application of N at moderate rates (<75 kg/ha) provides an effective means of supplementing declining soil N reserves for winter cereals in this region of unreliable rainfall

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

Sustaining productivity of a Vertisol at Warra, Queensland, with fertilisers, no-tillage, or legumes. 1. Organic matter status

Management practices involving legume leys, grain legumes, and no-tillage and stubble retention, along with nitrogen (N) fertiliser application for wheat cropping, were examined for their effectiveness in increasing soil organic matter (0-10 cm depth) from 1986 to 1993 in a field experiment on a Vertisol at Warra, Queensland. The treatments were (i) grass + legume leys (purple pigeon grass, Setaria incrassata; Rhodes grass, Chloris gayana; lucerne, Medicago sativa; annual medics, M. scutellata and M. truncatula) of 4 years duration followed by continuous wheat; (ii) 2-year rotation of annual medics and wheat (Triticum aestivum cv. Hartog); (iii) 2-year rotation of lucerne and wheat; (iv) 2-year rotation of chickpea (Cicer arietinum cv. Barwon) and wheat; (v) no-tillage (NT) wheat; and (vi) conventional tillage (CT) wheat. Fertiliser N as urea was applied to both NT wheat and CT wheat at 0,25, and 75 kg N/ha. year. The CT wheat also received N at 12.5 and 25kg N/ha. year. After 4 years, soil organic carbon (C) concentration under grass + legume leys increased by 20% (650 kg C/ha. year) relative to that under continuous CT wheat. Soil total N increased by 11, 18, and 22% after 2, 3, and 4 years, respectively, under grass + legume leys relative to continuous CT wheat. These increases in soil organic matter were mostly confined to the 0-2.5 cm layer. After the start of wheat cropping, organic C and total N levels declined steadily but were still higher than under CT wheat and higher than initial values in December 1985. Although 2-year rotations of lucerne-wheat and medic-wheat had a small effect on soil organic C, soil total N concentrations were higher than in the chickpea-wheat rotation and continuous CT wheat from November 1990 to November 1992. Soil under chickpea-wheat rotation had organic C and total N concentrations similar to continuous CT wheat, although from the former, about 70 kg/ha. year of extra N was removed in the grain from 1989 to 1993. No-tillage practice had a small effect on soil organic C, although total N concentration was higher than under CT wheat in November 1993. These effects were mainly confined to the surface 0-2.5 cm depth. The C to N ratio was only affected in soil under grass + legume leys, and no-tillage treatments. These data show that restoration of soil organic matter in Vertisol requires grass + legume leys, primarily due to increased root biomass, although soil total N can be enhanced by including legume leys for longer duration in cropping systems in the semi-arid and subtropical environment