A Note on the Relationship Between Branch- and Stemwood Properties of Selected Hardwoods Growing in the Mid-South

Specific gravity and fiber length values are reported for both stemwood and branchwood of eight southern hardwoods. Branchwood fibers are significantly shorter than stemwood fibers of each species. Branchwood specific gravity is higher than stemwood specific gravity for some species and lower for other species. The only statistically significant difference was in red oak which had higher specific gravity wood in branches than in stems.No statistically significant differences in either fiber length or specific gravity were found between branches from the top and bottom of the crown, nor between sampling points within branches

Wood Property Difference Between Two Stands of Sycamore and Black Willow

Wood properties of natural stands of willow and sycamore growing along the southern reaches of the Mississippi River were investigated. Properties of mature wood measured were specific gravity, fiber dimensions, and the proportional volume of xylem tissue composed of vessels, fibers and parenchyma.There are no statistically significant differences between measured properties of sycamore stands, and willow stands vary significantly only in fiber length and the proportion of vessels and ray tissue present.Correlation analysis revealed that there is no significant relationship between diameter growth rate and specific gravity for either species. Specific gravity is positively related to fiber wall thickness in willow, but there is little relationship among these properties in sycamore. The specific gravity of sycamore is, however, positively related to ray content. This relationship is important to tree breeders, because selection of high specific gravity phenotypes may result in an increase of ray tissue in select material

Wood Property Variation of Mississippi Delta Hardwoods

Variation in specific gravity, fiber length, fiber dimensions, and volumetric composition were investigated for selected heights and growth rings of five Mississippi Delta hardwood species: black willow, willow oak, sycamore, pecan, and sugarberry. Variation of specific gravity with age of the cambium was not only different from species to species, but was also different at different sampling heights. The fiber length-age relationship in study trees conformed to the general pattern of large increases in fiber length with age in rings near the pith, followed by a more gradual increase until a maximum was reached. Variations in fiber diameter were not great, but in all species, cell diameter decreased as height in the stem increased. Thin-walled fibers were found near the pith and thick-walled fibers developed in the outermost growth increments.Volumetric composition data revealed large variations between sampling points. The general pattern with age was a linear or curvilinear increase in vessel volume with a corresponding decrease in fiber volume, while ray volume remained constant or increased slightly with age.Correlation analysis was used to evaluate the interrelationships of measured properties in three different species (willow, sugarberry, and pecan). Wide growth rings in these species contained proportionately fewer vessels and more fibers than narrow growth rings as well as shorter fibers. High specific gravity was associated with increased fiber volume. However, the analysis showed no significant differences in specific gravity resulting from variations in growth rate

Growth Ring Characteristics, Specific Gravity, and Fiber Length of Rapidly Grown Loblolly Pine

Intensive thinning, understory control, and green pruning of loblolly pine trees growing on a test area near Crossett, Arkansas, have produced trees with a diameter of 18.9 inches at breast heights in 35 years. Large increment borings extracted from experimental trees and control trees were examined for growth patterns and wood properties alternations related to growth rate differences.During some growth periods, radial growth of test trees was almost three times as great as radial growth of control trees. In the outer juvenile wood formed after the first thinning, growth rate differences were greatest between experimental trees. During the last 10 years of the study (mature wood zone), growth rate differences between treated and control trees were not as great, and there were no significant differences in latewood percentage or tracheid length. Specific gravity was not significantly influenced by growth rate differences in any growth zone. This result leads to the conclusion that trees can be rapidly grown without affecting specific gravity

A Comparison Of Earlywood and Latewood Tracheid Lengths of Loblolly Pine

Literature reports on the relationship of earlywood and latewood tracheid length within individual growth rings of pine trees are contradictory and confusing. Latewood tracheids have been reported to be longer or shorter than, and the same length as, earlywood tracheids. This study compares earlywood and latewood tracheids of both juvenile and mature wood of trees in a loblolly pine plantation (phase 1) and reports tracheid length variation from first-formed earlywood to last-formed latewood at several sampling locations of one tree (phase 2).For the plantation-grown trees, earlywood and latewood were compared for ring 5 (juvenile wood) and ring 15 (mature wood) of 18 trees. In juvenile wood, first-formed earlywood cells were shorter than either last-formed earlywood or latewood tracheids. There was, however, little difference between last-formed earlywood and latewood. In mature wood, first-formed earlywood and last-formed latewood tracheids were the same average length. However, both earlywood and latewood tracheids formed near the transition zone were slightly longer.Measurement of tracheids, obtained by macerating serial microtome sections taken from earlywood to latewood of individual rings (phase 2), revealed large variations of tracheid length within rings. In some rings, tracheid length increased from earlywood to latewood, in others it decreased, and in others it was unchanged.The conclusion is that tracheid length is neither consistently longer nor shorter in the latewood portion of loblolly pine growth rings

Teaching IS Ethics: Applying A Research Technique For Classroom Use

The nature of IS technologies and the range of their appropriate and inappropriate uses continue to evolve and expand. MIS educational programs have a challenge to provide both the appropriate content to introduce students to classic information ethics problems, as well as the methods for analyzing possible actions within a complex realistic situation. This research paper describes the application to educational activities of a research technique pioneered by Donn Parker using scenarios and Likert scale values choices pertaining to IS ethical issues. The recommended method for application in the education setting is described. Key findings in terms of ethical themes that permeated surveys and discussions by students are also presented and discussed

An Application of Finite Element Analysis to Wood Drying

Because of the nonhomogeneous and nonlinear properties of wood, exact solutions for heat and mass transfer are difficult to obtain by current methods of analysis. This work presents a numerical solution for the analysis of drying wood using the finite element method. A nonlinear model was established on a two-dimensional finite element grid structure that considers local density variation. Through the finite element method of analysis of unsteady-state heat and moisture transfer in wood, the dynamic profiles of temperature and moisture content were determined at a series of drying times. The resulting numerical solutions match well with experimental results and with published results. The results will help to extend understanding of wood-water and temperature relations. In future studies, these data can be incorporated into drying stress analysis to analyze checking or warping

Expression of monolysocardiolipin acyltransferase activity is regulated in concert with the level of cardiolipin and cardiolipin biosynthesis in the mammalian heart

BACKGROUND: Monolysocardiolipin acyltransferase (MLCL AT) catalyzes the acylation of monolysocardiolipin to cardiolipin in mammalian tissues. We previously reported that cardiac cardiolipin levels, MLCL AT and cardiolipin synthase activities were all elevated in rats made hyperthyroid by thyroxine treatment. In this study, we examined if cardiac mitochondrial MLCL AT activity was dependent upon the biosynthesis and level of cardiolipin in the heart. Rat heart mitochondrial MLCL AT activity was determined under conditions in which the levels of cardiac cardiolipin and cardiolipin synthase activity were either reduced or unaltered using four different disease models in the rat. In addition, these parameters were examined in a murine model of cardiac cell differentiation. RESULTS: In rats made hypothyroid by treatment with 6-n-propyl-2-thiouracil in the drinking water for 34 days, cardiac cardiolipin content was decreased 29% (p < 0.025) and this was associated with a 32% decrease (p < 0.025) in cardiolipin synthase and a 35% reduction (p < 0.025) in MLCL AT activities. Streptozotocin-induced diabetes or hyperinsulinemia in rats did not affect cardiac cardiolipin content nor MLCL AT and cardiolipin synthase activities. Finally, cardiolipin content, MLCL AT and cardiolipin synthase activities were unaltered during murine P19 teratocarcinoma cell differentiation into cardiac myocytes. In all models, phospholipase A(2) activities were unaltered compared with controls. CONCLUSION: We propose a general model in which the expression of MLCL AT activity is regulated in concert with the biosynthesis and level of cardiolipin in the heart

Treatment of co-infection with bancroftian filariasis and onchocerciasis: a safety and efficacy study of albendazole with ivermectin compared to treatment of single infection with bancroftian filariasis

BACKGROUND: In order to use a combination of ivermectin and albendazole for the elimination of lymphatic filariasis, it is important to assess the potential risk of increased adverse events in individuals infected with both lymphatic filariasis and onchocerciasis. We compared the safety and efficacy of albendazole (400 mg) in combination with ivermectin (150 micrograms/kg), for the treatment of co-infections of Wuchereria bancrofti and Onchocerca volvulus with single infection of W. bancrofti. METHODS: The safety study on co-infections was a crossover, double blind design, while for the single infection of bancroftian filariasis an open design comparing two treatments was used. For co-infection, one group was allocated a single dose of ivermectin (150 micrograms/kg) plus albendazole (400 mg) (Group A). The other group received placebo (Group B). Five days later the treatment regime was reversed, with the Group A receiving placebo and Group B receiving treatment. For the single bancroftian filariasis infection, one group received a single dose of albendazole (400 mg) plus ivermectin (150 μg/kg) (Group C) while the other group received a single dose of albendazole (400 mg) alone (Group D). Blood and skin specimens were collected on admission day, day 0, and on days 2, 3, and 7 to assess drug safety and efficacy. Thereafter, blood and skin specimens were collected during the 12 months follow up for the assessment of drug efficacy. Study individuals were clinically monitored every six hours during the first 48 hours following treatment, and routine clinical examinations were performed during the hospitalisation period and follow-up. RESULTS: In individuals co-infected with bancroftian filariasis and onchocerciasis, treatment with ivermectin and albendazole was safe and tolerable. Physiological indices showed no differences between groups with co-infection (W. bancrofti and O. volvulus) or single infection (W. bancrofti). The frequency of adverse events in co-infected individuals was 63% (5/8, Group A, albendazole + ivermectin) and 57% (4/7, Group B, placebo) and of mild or moderate intensity. In single W. bancrofti infection the frequency of adverse events was 50% (6/12, Group C, albendazole + ivermectin) and 38% (5/13, Group D, albendazole) and of a similar intensity to those experienced with co-infection. There were no differences in adverse events between treatment groups. There was no significant difference in the reduction of microfilaraemia following treatment with albendazole and ivermectin in groups with single or co-infection. CONCLUSION: Our findings suggest that ivermectin plus albendazole is a safe and tolerable treatment for co-infection of bancroftian filariasis and onchocerciasis

‘Priming’ exercise and O2 uptake kinetics during treadmill running

We tested the hypothesis that priming exercise would speed kinetics during treadmill running. Eight subjects completed a square-wave protocol, involving two bouts of treadmill running at 70% of the difference between the running speeds at lactate threshold (LT) and max, separated by 6-min of walking at 4 km h−1, on two occasions. Oxygen uptake was measured breath-by-breath and subsequently modelled using non-linear regression techniques. Heart rate and blood lactate concentration were significantly elevated prior to the second exercise bout compared to the first. However, kinetics was not significantly different between the first and second exercise bouts (mean ± S.D., phase II time constant, Bout 1: 16 ± 3 s vs. Bout 2: 16 ± 4 s; slow component amplitude, Bout 1: 0.24 ± 0.10 L min−1vs. Bout 2: 0.20 ± 0.12 L min−1; mean response time, Bout 1: 34 ± 4 s vs. Bout 2: 34 ± 6 s; P > 0.05 for all comparisons). These results indicate that, contrary to previous findings with other exercise modalities, priming exercise does not alter kinetics during high-intensity treadmill running, at least in physically active young subjects. We speculate that the relatively fast kinetics and the relatively small slow component in the control (‘un-primed’) condition negated any enhancement of kinetics by priming exercise in this exercise modality