122 research outputs found
Predicting Resin Pockets in Radiata Pine Logs from Blemishes on Log Ends
More than 120 radiata pine (Pinus radiata D. Don) sawlogs, from two sites, were assessed for resin pockets and blemishes (resin streaks, bark pockets, colored marks, and other grain deviations) on the log ends. At both sites, the assessment of blemishes on the log ends improved the prediction of resin pockets on the lumber after sawing (r2 = 0.29 and 0.49), beyond the prediction achieved by assessing resin pockets on the log ends alone (r2 = 0 and 0.24). Noting only the presence or absence of blemishes on the log ends enabled explanation of half the variation between logs in loss of clear cuttings due to docking out resin pockets from the lumber (r2 = 0.50, P < 0.001). Since the log ends were assessed after ordinary chainsaw cuts were made, we believe that blemishes could be recognized by log graders, and that it should be possible to develop selection procedures for sawlogs that minimize the value losses associated with resin pockets
Inclusive School Community: Why is it so Complex?
This paper addresses the question: why is it so hard for school communities to respond to diversity in learners, staff and parents in inclusive ways? The authors draw on theory and recent professional experience in Queensland, Australia, to offer four guiding principles that address traditional assumptions about learning that result in inequality of opportunity and outcomes for students. The authors suggest these principles to support the development of a more inclusive school community: (1) develop a learning community incorporating a critical friend; (2) value and collaborate with parents and the broader community; (3) engage students as citizens in school review and developÂŹment; and (4) support teachersâ critical engagement with inclusive ideals and practices. The authors describe how the principles can work in concert in a school community
Coping with potential bi-parental inbreeding: limited pollen and seed dispersal and large genets in the dioecious marine angiosperm Thalassia testudinum
The high prevalence of dioecy in marine angiosperms or seagrasses (>50% of all species) is thought to enforce cross-fertilization. However, seagrasses are clonal plants, and they may still be subject to sibling-mating or bi-parental inbreeding if the genetic neighborhood is smaller than the size of the genets. We tested this by determining the genetic neighborhoods of the dioecious seagrass Thalassia testudinum at two sites (Back-Reef and Mid-Lagoon) in Puerto Morelos Reef Lagoon, Mexico, by measuring dispersal of pollen and seeds in situ, and by finescale spatial autocorrelation analysis with eight polymorphic microsatellite DNA markers. Prevalence of inbreeding was verified by estimating pairwise kinship coefficients; and by analysing the genotypes of seedlings grown from seeds in mesocosms. Average dispersal of pollen was 0.3â1.6 m (max. 4.8 m) and of seeds was 0.3â0.4 m (max. 1.8 m), resulting in a neighborhood area of 7.4 m² (range 3.4â11.4 m²) at Back-Reef and 1.9 (range 1.87â1.92 m²) at Mid-Lagoon. Neighborhood area (Na) derived from spatial autocorrelation was 0.1â20.5 m² at Back-Reef and 0.1â16.9 m² at Mid-Lagoon. Maximal extensions of the genets, in 19 9 30 m plots, were 19.2 m (median 7.5 m) and 10.8 m (median 4.8 m) at Back-Reef and Mid-Lagoon. There was no indication of deficit or excess of heterozygotes nor were coefficients of inbreeding (Fis) significant. The seedlings did not show statistically significant deficit of heterozygotes (except for 1 locus at Back-Reef). Contrary to our expectations, we did not find evidence of bi-parental inbreeding in this dioecious seagrass with large genets but small genetic neighborhoods. Proposed mechanisms to avoid bi-parental inbreeding are possible selection against homozygotes during fecundation or ovule development. Additionally, the genets grew highly dispersed (aggregation index Ac was 0.09 and 0.10 for Back-Reef and Mid-Lagoon, respectively); such highly dispersed guerrilla-like clonal growth form likely increases the probability of crossing between different potentially unrelated genets.Brigitta Ine Van Tussenbroek, Tania Valdivia-Carrillo, Irene Teresa RodrĂguez-Virgen, Sylvia Nashieli Marisela Sanabria-Alcaraz, Karina JimĂŠnez-Duran, Kor Jent Van Dijk, Guadalupe Judith Marquez-GuzmĂĄ
Ribosomal RNA of Hyacinthus orientalis L. female gametophyte cells before and after fertilization
The nucleolar activity of Hyacinthus orientalis L. embryo sac cells was investigated. The distributions of nascent pre-rRNA (ITS1), 26S rRNA and of the 5S rRNA and U3 snoRNA were determined using fluorescence in situ hybridization (FISH). Our results indicated the different rRNA metabolism of the H. orientalis female gametophyte cells before and after fertilization. In the target cells for the male gamete, i.e., the egg cell and the central cell whose activity is silenced in the mature embryo sac (PiÄciĹski et al. in Sex Plant Reprod 21:247â257, 2008; NiedojadĹo et al. in Planta doi:10.1007/s00425-012-1599-9, 2011), rRNA metabolism is directed at the accumulation of rRNPs in the cytoplasm and immature transcripts in the nucleolus. In both cells, fertilization initiates the maturation of the maternal pre-rRNA and the expression of zygotic rDNA. The resumption of rRNA transcription observed in the hyacinth zygote indicates that in plants, there is a different mechanism for the regulation of RNA Pol I activity than in animals. In synergids and antipodal cells, which have somatic functions, the nucleolar activity is correlated with the metabolic activity of these cells and changes in successive stages of embryo sac development
Aboriginal and Torres Strait Islander Suicide in Context
Aboriginal and Torres Strait Islander suicide has been an issue of national public health and mental health concern for only one decade, having increased dramatically from levels that were very low in the late 1980s to levels of young adult male suicide that are now substantially higher than for the non-indigenous population. In this review the authors socially and historically contextualize these changes, identifying the causal frameworks adopted in developing interventions, and present an explanation in narrative and pictorial form that draws on critical family-centered trauma
Chronic Helminth Infections Protect Against Allergic Diseases by Active Regulatory Processes
Developed countries are suffering from an epidemic rise in immunologic disorders, such as allergy-related diseases and certain autoimmunities. Several studies have demonstrated a negative association between helminth infections and inflammatory diseases (eg, allergy), providing a strong case for the involvement of helminth infections in this respect. However, some studies point in the opposite direction. The discrepancy may be explained by differences in frequency, dose, time, and type of helminth. In this review, new studies are discussed that may support the concept that chronic helminth infections in particularâbut not acute infectionsâare associated with the expression of regulatory networks necessary for downmodulating allergic immune responses to harmless antigens. Furthermore, different components of regulatory networks are highlighted, such as the role of regulatory T and B cells, modulation of dendritic cells, early innate signals from structural cells (eg, epithelial cells), and their individual contributions to protection against allergic diseases. It is of great interest to define and characterize specific helminth molecules that have profound immunomodulatory capacities as targets for therapeutic application in the treatment or prophylaxis of allergic manifestations
- âŚ