Influence of static bending stress on growth and wood characteristics of nine-year-old Douglas fir from two geographic sources

The form of a tree stem and the properties of the wood comprising a stem may be determined by the strength requirements of that stem. If this is true, a tree will react physiologically to stresses which are imposed on a stem. This study was designed to investigate the influence of static bending stress on the growth and wood characteristics of Douglas -fir. Twenty-four nine –year-old Douglas-fir trees from two geographic sources were divided into three treatments. The treatments used were control, low bending stress, and high bending stress. Trees in the low and high treatments were bent with a horizontal force at a point 4. 5 ft. from the base, so that a low and high bending stress, respectively, would be produced in the trees. Bending caused another variable to be introduced into the experiment. That variable was a transverse component of gravity which influenced the low and high treatment trees. The influence of stress and gravity was studied on the diameter, radial, and leader growth of the trees and also on the specific gravity and tracheid length of the wood which was produced. Treatments did not cause a significant change in diameter growth. Radial growth was increased in treatment trees on the side of stems which was under compressive stress. The greatest increase in radial growth occurred in the lower parts of stems from 2. 5 ft. to the base. Leader growth was significantly decreased by the treatments with the greatest decrease in high stress trees. The treatment thus caused a redistribution of wood formation from the higher parts of stems to the lower parts of stems. Stress is thought to be the factor influencing this downward redistribution of wood and causing the increase in radial growth in the lower parts of stems. Specific gravity of wood formed was increased by treatments, but only on the side of sterns containing compressive stress. The greatest increase was at 4. 5 ft. and 2. 5 ft. , with only a small increase at the base. The increase in specific gravity was associated with compression wood formation. The increase in specific gravity and associated compression wood formation is believed caused by the transverse component of gravity rather than by any stress influence. Treatments also caused a decrease in tracheid length of wood formed on the sides of stems containing compressive stress. This decrease in tracheid length appeared to be associated with the increase in radial growth which occurred on treatment trees and also with compression wood formation. This study indicates that the function of compression wood is not to resist stresses in trees, but rather possibly to cause a bent or leaning tree to reorient itself in the vertical position. In order to resist stresses in stems, trees produce increased amounts of normal wood. In this way a greater cross sectional area of a stem is available to resist the imposed stresses

Effects of the Argon Pressure on the Optical Band Gap of Zinc Oxide Thin Films Grown by Nonreactive RF Sputtering

Zinc oxide (ZnO) thin films were grown by nonreactive RF sputtering at room temperature under varying argon pressures (PAr). Their optical band gap was found to increase from 3.58 to 4.34 eV when the argon pressure increases from 2.67 to 10.66 Pa. After annealing at 200°C and 500°C, optical band gaps decrease considerably. The observed widening of the band gap with increasing PAr can be understood as being a consequence of the poorer crystallinity of films grown at higher pressures. Measurements of morphological and electrical properties of these films correlate well with this picture. Our main aim is to understand the effects of PAr on several physical properties of the films, and most importantly on its optical band gap

Growth and optical characterization of indirect-gap AlxGa1−xAs alloys

Nonintentionally doped AlxGa1−xAs layers with 0.38 x 0.84 were grown on (100) GaAs substrates by liquid phase epitaxy (LPE) under near-equilibrium conditions. The crystalline quality of the samples was studied by photoluminescence at 2 K and room temperature Raman spectroscopy. The peculiar behavior in the photoluminescence intensities of the indirect bound exciton line and the donor–acceptor pair transition is explained from the evolution of the silicon donor binding energy according to the aluminum composition. It was also possible to observe the excitonic transition corresponding to the AlxGa1−xAs/GaAs interface, despite the disorder and other factors which are normally involved when growing high-aluminum-content layers by this technique. Furthermore, Raman measurements show the quadratic variations of longitudinal optical phonon frequencies with aluminum concentration in good agreement with previous experimental results. In this work we show that high quality indirect-gap AlxGa1−xAs samples can be grown by LPE under near-equilibrium [email protected]

Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic $ep$ scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

A Search for Selectrons and Squarks at HERA

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure

Nurse academics' experience of contra-power harassment from under-graduate nursing students in Australia.

There is growing concern around inappropriate behaviour being perpetrated by under-graduate nursing students towards nursing academics. Coined contra-power harassment, is defined as the harassment of individuals in formal positions of power and authority by those that are not. The type of harassment behaviours reported include: verbal and physical violence, character assassination through social media, stalking and sexually motivated behaviours. The most often cited reasons for the escalation in these behaviours are seen with course progression and the awarding of grades. AIM: The aim of this study is to better understand the extent to which nursing academics experience contra-power harassment from under-graduate nursing students. METHOD: A convenience sample of nursing academics were in Australia were contacted and provided with an introductory letter, a participant information sheet and a link to an online questionnaire. A 41-item Likert scale (Strongly agree-strongly disagree) was used to elicit responses to statements on academics' experiences of and the contributing factors associated with contra-power harassment. RESULTS: The main contributing factor identified from this study was seen as the consumerism of higher education; in particular paying for a degree gave a sense of entitlement with academics experiencing the highest levels of student harassment around grades. CONCLUSIONS: Contra-power harassment is becoming common place in higher education especially in nursing education. The competitive nature of obtaining employment post-university has meant that some nursing student's behaviours are becoming increasingly uncivil, challenging and unprofessional

A Multicenter Evaluation of Pediatric Emergency Department Injury Visits during the COVID-19 Pandemic

BACKGROUND: Injuries, the leading cause of death in children 1-17 years old, are often preventable. Injury patterns are impacted by changes in the child\u27s environment, shifts in supervision, and caregiver stressors. The objective of this study was to evaluate the incidence and proportion of injuries, mechanisms, and severity seen in Pediatric Emergency Departments (PEDs) during the COVID-19 pandemic. METHODS: This multicenter, cross-sectional study from January 2019 through December 2020 examined visits to 40 PEDs for children \u3c 18 years old. Injury was defined by at least one International Classification of Disease-10th revision (ICD-10) code for bodily injury (S00-T78). The main study outcomes were total and proportion of PED injury-related visits compared to all visits in March through December 2020 and to the same months in 2019. Weekly injury visits as a percentage of total PED visits were calculated for all weeks between January 2019 and December 2020. RESULTS: The study included 741,418 PED visits for injuries pre-COVID-19 pandemic (2019) and during the COVID-19 pandemic (2020). Overall PED visits from all causes decreased 27.4% in March to December 2020 compared to the same time frame in 2019; however, the proportion of injury-related PED visits in 2020 increased by 37.7%. In 2020, injured children were younger (median age 6.31 years vs 7.31 in 2019), more commonly White (54% vs 50%, p \u3c 0.001), non-Hispanic (72% vs 69%, p \u3c 0.001) and had private insurance (35% vs 32%, p \u3c 0.001). Injury hospitalizations increased 2.2% (p \u3c 0.001) and deaths increased 0.03% (p \u3c 0.001) in 2020 compared to 2019. Mean injury severity score increased (2.2 to 2.4, p \u3c 0.001) between 2019 and 2020. Injuries declined for struck by/against (- 4.9%) and overexertion (- 1.2%) mechanisms. Injuries proportionally increased for pedal cycles (2.8%), cut/pierce (1.5%), motor vehicle occupant (0.9%), other transportation (0.6%), fire/burn (0.5%) and firearms (0.3%) compared to all injuries in 2020 versus 2019. CONCLUSIONS: The proportion of PED injury-related visits in March through December 2020 increased compared to the same months in 2019. Racial and payor differences were noted. Mechanisms of injury seen in the PED during 2020 changed compared to 2019, and this can inform injury prevention initiatives

Checklist of the subfamily Adoncholaiminae Gerlach and Riemann, 1974 (Nematoda: Oncholaimida: Oncholaimidae) of the world: genera, species, distribution, and reference list for taxonomists and ecologists

Adoncholaiminae is one of the seven subfamilies in the free-living aquatic nematode family Oncholaimidae. Nematodes in Adoncholaiminae are found from various water environment of the world. However, a checklist of all Adoncholaiminae species including full literature, especially information of experimental (not taxonomic) works, has not been updated for more than 40 years. A revised checklist of the subfamily Adoncholaiminae of the world is provided. It contains 31 valid and 13 invalid species names in four genera with synonyms, collection records, and full literature from 1860's to 2015 for each species. A literature survey of total 477 previous papers was conducted in this work, and 362 of them are newly added to checklist