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

Faster juvenile growth promotes earlier sex change in a protandrous hermaphrodite (barramundi Lates calcarifer)

The relationship between growth and sexual maturation is central to understanding the dynamics of animal populations which exhibit indeterminate growth. In sequential hermaphrodites, which undergo post-maturation sex change, the size and age at which sex change occurs directly affects reproductive output and hence population productivity. However, these traits are often labile, and may be strongly influenced by heterogenous growth and mortality rates. We analysed otolith microstructure of a protandrous (i.e., male-to-female) fish (barramundi Lates calcarifer) to examine growth in relation to individual variation in the timing of sex change. Growth trajectories of individuals with contrasting life histories were examined to elucidate the direction and extent to which growth rate influences the size and age individuals change sex. Then, the relationships between growth rate, maturation schedules and asymptotic maximum size were explored to identify potential trade-offs between age at female maturity and growth potential. Rapid growth was strongly associated with decreased age at sex change, but this was not accompanied by a decrease in size at sex change. Individuals that were caught as large females grew faster than those caught as males, suggesting that fast-growing individuals ultimately obtain higher fitness and therefore make a disproportionate contribution to population fecundity. These results indicate that individual-level variation in maturation schedules is not reflective of trade-offs between growth and reproduction. Rather, we suggest that conditions experienced during the juvenile phase are likely to be a key determinant of post-maturation fitness. These findings highlight the vulnerability of sex-changing species to future environmental change and harvest

Majorana Neutrino Masses Can Save One Family Technicolour

We make non perturbative estimates of the electroweak radiative correction parameter $S$ in dynamical symmetry breaking models with Majorana neutrino masses. The Majorana masses are treated as perturbations to a Non Local Chiral Model of the strong interactions. We argue that parameter ranges exist that would allow realistic values of $S$ and $T$ in one family Technicolour models.Comment: 15 pages plus appended diagrams (ps), Latex, SHEP 92/93--2

Mechanical stabilization of BSCCO-2223 superconducting tapes

A system to provide mechanical stabilization to high temperature BSCCO-2223 superconducting tape by laminating 0.081 mm thick, spring hard, copper foil to both sides with lead-tin eutectic solder has been successfully optimized. This system has been applied as a method to create a strong, windable composite from pure silver BSCCO tapes with a minimum of critical current (I{sub c}) degradation. The {open_quotes}as received{close_quotes} conductor is evaluated for physical consistency of width and thickness over the 3000 meters that were later strengthened, insulated and wound into a demonstration coil. Electrical degradation in the strengthened tape as a result of lamination was found to average 24 percent with a range from 4 to 51 percent. This was less than the degradation that would have occurred in an unstrengthened tape during subsequent insulation and coil winding processes. Additional work was performed to evaluate the mechanical properties of the strengthened tapes. The copper can double the ultimate tensile strength of the pure silver tapes. Additionally, pure silver and dispersion strengthened silver matrix tapes are laminated with 0.025 mm thick copper and 304 stainless steel foil to investigate minimization of the cross sectional area of the strengthening component. The stainless steel can increase the UTS of the pure silver tapes sixfold. Metallography is used to examine the laminate and the conductor. Mechanical properties and critical currents of these tapes are also reported both before and after strengthening. The I{sub c} is also measured as a function of strain on the laminated tapes

Oscillator model for the relativistic fermion-boson system

The solvable quantum mechanical model for the relativistic two-body system composed of spin-1/2 and spin-0 particles is constructed. The model includes the oscillator-type interaction through a combination of Lorentz-vector and -tensor potentials. The analytical expressions for the wave functions and the order of the energy levels are discussed.Comment: published version, 8 pages, 2 figure

The structural analysis of Cu(111)-Te (√3 × √3) R30° and (2√3 × 2√3)R30° surface phases by quantitative LEED and DFT,

The chemisorption of tellurium on atomically clean Cu(111) surface has been studied under ultra-high vacuum conditions. At room temperature, the initial stage of growth was an ordered 23×23R30° phase (0.08 ML). An ordered 3×3R30° phase is formed at 0.33 ML coverage of Te. The adsorption sites of the Te atoms on the Cu(111) surface at 0.08 ML and 0.33 ML coverages are explored by quantitative low energy electron diffraction (LEED) and density functional theory (DFT). Our results indicate that substitutional surface alloy formation starts at very low coverages

Land resource assessment of Northern Belize (NRI Bulletin 43, Volume 1 of 2)

The land resource assessment was undertaken from July 1989 to June 1990 by the Natural Resources Institute (NRI) of the Overseas Development Administration (ODA), assisted by Mr. A. C. S. Wright, and Dr. M. Holder of Central Farm. The main object of the survey was to produce an updated land suitability assessment of Orange Walk, Corozal, Belize and Cayo districts which had not already been surveyed by Jenkin et al. (1976) and King et al. (1989). In addition, this survey would provide a land suitability assessment for the Belize Valley based on the soil mapping of )en kin et al. Thus, together with the land resource assessments of Toledo and Stann Creek districts (King et al., 1986, 1989 respectively), a land suitability assessment for the whole of Belize is now available

Land resource assessment of Northern Belize (NRI Bulletin 43, Volume 2 of 2)

The land resource assessment was undertaken from July 1989 to June 1990 by the Natural Resources Institute (NRI) of the Overseas Development Administration (ODA), assisted by Mr. A. C. S. Wright, and Dr. M. Holder of Central Farm. The main object of the survey was to produce an updated land suitability assessment of Orange Walk, Corozal, Belize and Cayo districts which had not already been surveyed by Jenkin et al. (1976) and King et al. (1989). In addition, this survey would provide a land suitability assessment for the Belize Valley based on the soil mapping of )en kin et al. Thus, together with the land resource assessments of Toledo and Stann Creek districts (King et al., 1986, 1989 respectively), a land suitability assessment for the whole of Belize is now available