183 research outputs found
A Simulation of the Impact of Pre-emptive Cutting for Transportation on Value Recovery
Centralised processing may be an alternative to skidsite processing for some regions of New Zealand where radiata pine plantations now await harvest. However, a pre-emptive cut will generally be necessary to reduce felled stems to lengths which can be trucked to a central processing yard. There are various strategies for determining where a single pre-emptive cut should be placed. The effect on potential stem value has been compared for samples of trees using the bucking simulation program AVIS. All strategies tested reduced stem value but the amount of loss varied with the strategy chosen and the subsequent cutting pattern used in the yard
Review of Chain Flail Delimbing-Debarking
Over 200 commercially built chain flail delimber-debarkers are now in operation worldwide. These units, teamed with in woods chippers, are producing chips acceptable for pulping from many species of hardwoods and softwoods. The flails can remove the bark as well as drum debarkers in the case of southern pine species. The chips produced by these portable operations have been shown to be equal in quality to the chips produced at mill and satellite wood yards. It has been estimated that the flail-chipper system will produce up to 2.9% more clean chips than are obtained with conventional longwood harvesting and handling systems. The flails have been used to remove rot, foliage, and charcoal in specialized applications. The rejects from the flail represent a readily recoverable source of energy material, but this debris must be reduced in size to facilitate handling. Developments for reducing the size of the rejects are ongoing, especially using modified agricultural tub grinders. Chains are a major cost in the operation of the flails. Strategies have been developed which can prolong the life of the chains, and tests are ongoing with improved materials in the manufacturing of the chains. The cost of delimbing and debarking with the portable flails has been estimated to be between (US)3.30 per green tonne
Contact Sports as a Risk Factor for Amyotrophic Lateral Sclerosis: A Systematic Review.
Study Design: Systematic review.
Introduction: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease, ultimately resulting in paralysis and death. The condition is considered to be caused by a complex interaction between environmental and genetic factors. Although vast genetic research has deciphered many of the molecular factors in ALS pathogenesis, the environmental factors have remained largely unknown. Recent evidence suggests that participation in certain types of sporting activities are associated with increased risk for ALS.
Objective: To test the hypothesis that competitive sports at the highest level that involve repetitive concussive head and cervical spinal trauma result in an increased risk of ALS compared with the general population or nonsport controls.
Methods: Electronic databases from inception to November 22, 2017 and reference lists of key articles were searched to identify studies meeting inclusion criteria.
Results: Sixteen studies met the inclusion criteria. Sports assessed (professional or nonprofessional) included soccer (n = 5), American football (n = 2), basketball (n = 1), cycling (n = 1), marathon or triathlon (n = 1), skating (n = 1), and general sports not specified (n = 11). Soccer and American football were considered sports involving repetitive concussive head and cervical spinal trauma. Professional sports prone to repetitive concussive head and cervical spinal trauma were associated with substantially greater effects (pooled rate ratio [RR] 8.52, 95% CI 5.18-14.0) compared with (
Conclusions: Our review suggests that increased susceptibility to ALS is significantly and independently associated with 2 factors: professional sports and sports prone to repetitive concussive head and cervical spinal trauma. Their combination resulted in an additive effect, further increasing this association to ALS
Catastrophic Cervical Spine Injuries in Contact Sports.
Study Design Systematic review. Objectives To determine the incidence of catastrophic cervical spine injuries (CCSIs) among elite athletes participating in contact team sports and whether the incidence varies depending on the use of protective gear or by player position. Methods Electronic databases and reference lists of key articles published from January 1, 2000, to January 29, 2016, were searched. Results Fourteen studies were included that reported CCSI in rugby (n = 10), American football (n = 3), and Irish hurling (n = 1). Among Rugby Union players, incidence of CCSI was 4.1 per 100,000 player-hours. Among National Football League players, the CCSI rate was 0.6 per 100,000 player-exposures. At the collegiate level, the CCSI rate ranged from 1.1 to 4.7 per 100,000 player-years. Mixed populations of elite and recreational rugby players in four studies report a CCSI rate of 1.4 to 7.2 per 100,000 player-years. In this same population, the scrum accounted for 30 to 51% of total reported CCSIs in Rugby Union versus 0 to 4% in Rugby League. The tackle accounted for 29 to 39% of injuries in Rugby Union and 78 to 100% of injuries in Rugby League. Making a tackle was responsible for 29 to 80% of injuries in American football. Conclusion CCSIs are infrequent among elite athletes. There is insufficient evidence to determine the effect of protective gear (e.g., helmets, padding) on CCSI incidence. Scrum and tackle in rugby and tackling in American football account for the majority of CCSIs in each respective sport.This article is freely available via Open Access. Click on the Additional link above to access the full-text via the publisher's site.Published (Open Access
Tamoxifen-elicited uterotrophy: cross-species and cross-ligand analysis of the gene expression program
<p>Abstract</p> <p>Background</p> <p>Tamoxifen (TAM) is a well characterized breast cancer drug and selective estrogen receptor modulator (SERM) which also has been associated with a small increase in risk for uterine cancers. TAM's partial agonist activation of estrogen receptor has been characterized for specific gene promoters but not at the genomic level <it>in vivo</it>.Furthermore, reducing uncertainties associated with cross-species extrapolations of pharmaco- and toxicogenomic data remains a formidable challenge.</p> <p>Results</p> <p>A comparative ligand and species analysis approach was conducted to systematically assess the physiological, morphological and uterine gene expression alterations elicited across time by TAM and ethynylestradiol (EE) in immature ovariectomized Sprague-Dawley rats and C57BL/6 mice. Differential gene expression was evaluated using custom cDNA microarrays, and the data was compared to identify conserved and divergent responses. 902 genes were differentially regulated in all four studies, 398 of which exhibit identical temporal expression patterns.</p> <p>Conclusion</p> <p>Comparative analysis of EE and TAM differentially expressed gene lists suggest TAM regulates no unique uterine genes that are conserved in the rat and mouse. This demonstrates that the partial agonist activities of TAM extend to molecular targets in regulating only a subset of EE-responsive genes. Ligand-conserved, species-divergent expression of carbonic anhydrase 2 was observed in the microarray data and confirmed by real time PCR. The identification of comparable temporal phenotypic responses linked to related gene expression profiles demonstrates that systematic comparative genomic assessments can elucidate important conserved and divergent mechanisms in rodent estrogen signalling during uterine proliferation.</p
Percutaneous & Mini Invasive Achilles tendon repair
Rupture of the Achilles tendon is a considerable cause of morbidity with reduced function following injury. Recent studies have shown little difference in outcome between the techniques of open and non-operative treatment using an early active rehabilitation programme. Meta-analyses have shown that non-operative management has increased risk of re-rupture whereas surgical intervention has risks of complications related to the wound and iatrogenic nerve injury. Minimally invasive surgery has been adopted as a way of reducing infections rates and wound breakdown however avoiding iatrogenic nerve injury must be considered. We discuss the techniques and outcomes of percutaneous and minimally invasive repairs of the Achilles tendon
Global phylogeography and ancient evolution of the widespread human gut virus crAssphage
Microbiomes are vast communities of microorganisms and viruses that populate all natural ecosystems. Viruses have been considered to be the most variable component of microbiomes, as supported by virome surveys and examples of high genomic mosaicism. However, recent evidence suggests that the human gut virome is remarkably stable compared with that of other environments. Here, we investigate the origin, evolution and epidemiology of crAssphage, a widespread human gut virus. Through a global collaboration, we obtained DNA sequences of crAssphage from more than one-third of the world's countries and showed that the phylogeography of crAssphage is locally clustered within countries, cities and individuals. We also found fully colinear crAssphage-like genomes in both Old-World and New-World primates, suggesting that the association of crAssphage with primates may be millions of years old. Finally, by exploiting a large cohort of more than 1,000 individuals, we tested whether crAssphage is associated with bacterial taxonomic groups of the gut microbiome, diverse human health parameters and a wide range of dietary factors. We identified strong correlations with different clades of bacteria that are related to Bacteroidetes and weak associations with several diet categories, but no significant association with health or disease. We conclude that crAssphage is a benign cosmopolitan virus that may have coevolved with the human lineage and is an integral part of the normal human gut virome
Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A
Despite the fact that more than 5000 safety-related studies have been published on bisphenol A (BPA), there seems to be no resolution of the apparently deadlocked controversy as to whether exposure of the general population to BPA causes adverse effects due to its estrogenicity. Therefore, the Advisory Committee of the German Society of Toxicology reviewed the background and cutting-edge topics of this BPA controversy. The current tolerable daily intake value (TDI) of 0.05 mg/kg body weight [bw]/day, derived by the European Food Safety Authority (EFSA), is mainly based on body weight changes in two- and three-generation studies in mice and rats. Recently, these studies and the derivation of the TDI have been criticized. After having carefully considered all arguments, the Committee had to conclude that the criticism was scientifically not justified; moreover, recently published additional data further support the reliability of the two-and three-generation studies demonstrating a lack of estrogen-dependent effects at and below doses on which the current TDI is based. A frequently discussed topic is whether doses below 5 mg/ kg bw/day may cause adverse health effects in laboratory animals. Meanwhile, it has become clear that positive results from some explorative studies have not been confirmed in subsequent studies with higher numbers of animals or a priori defined hypotheses. Particularly relevant are some recent studies with negative outcomes that addressed effects of BPA on the brain, behavior, and the prostate in rodents for extrapolation to the human situation. The Committee came to the conclusion that rodent data can well be used as a basis for human risk evaluation. Currently published conjectures that rats are insensitive to estrogens compared to humans can be refuted. Data from toxicokinetics studies show that the half-life of BPA in adult human subjects is less than 2 hours and BPA is completely recovered in urine as BPA-conjugates. Tissue deconjugation of BPA-glucuronide and -sulfate may occur. Because of the extremely low quantities, it is only of minor relevance for BPA toxicity. Biomonitoring studies have been used to estimate human BPA exposure and show that the daily intake of BPA is far below the TDI for the general population. Further topics addressed in this article include reasons why some studies on BPA are not reproducible; the relevance of oral versus non-oral exposure routes; the degree to which newborns are at higher systemic BPA exposure; increased BPA exposure by infusions in intensive care units; mechanisms of action other than estrogen receptor activation; and the current regulatory status in Europe, as well as in the USA, Canada, Japan, New Zealand, and Australia. Overall, the Committee concluded that the current TDI for BPA is adequately justified and that the available evidence indicates that BPA exposure represents no noteworthy risk to the health of the human population, including newborns and babies
A realistic evaluation of fines for hospital discharges: Incorporating the history of programme evaluations in the analysis
Programmes and policies transform over time and locations. Evaluation projects can apprehend only temporal and contextualized sections of the social world. This article uses a realist evaluation of financial incentives in English hospital discharge policy to illustrate how previous evaluations of the same programme theory were inspected for evidence to construct context, mechanisms and outcomes. Following the discharges of a reduced number of patients with a case study approach, the preliminary programme theory ('fines reduce delays') was modified into a redefined theory on how fines operate locally in practice. This identified other mechanisms contemporaneous to the fines which are more or as likely to reduce delays. This article aims to contribute to the development of the realist evaluation strategy by introducing programme's transformations as key evidence when trying to understand how complex interventions work in particular contexts
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