scholarly journals THE EFFECT OF SEVERAL VARIABLES ON THE SPECIFIC GRAVITY OF SECOND-GROWTH DOUGLAS FIR

1952 ◽  
Vol 28 (3) ◽  
pp. 34-44 ◽  
Author(s):  
R. W. Wellwood
Keyword(s):  
Specific Gravity ◽  
Site Index ◽  
Douglas Fir ◽  
Several Variables ◽  
Second Growth ◽  
Significant Difference ◽  
Thinning Operation ◽  
The Mean ◽  
Individual Trees ◽  
The University

Second-growth stands of mixed Douglas fir and western hemlock produce wood that varies considerably in quality, expressed as specific gravity, depending upon the factors of position in the stem, crown class and site index. Data were obtained from sample Douglas fir trees removed in a thinning operation on the University Research Forest, Haney, British Columbia. Samples represent three levels in the stem (stump, one-third total height and merchantable top), three major crown classes (Dominant, Codominant and Intermediate) and site indices from 93 to 160.It was determined that wood at the base of the tree was more dense than at the higher levels, although this difference failed to show significance for the better sites. Considering the differences, at the same levels, between trees of the three crown classes, Dominants had significantly lower values of specific gravity than either the Codominants or the Intermediates. No significant differences occurred between the latter two classes. When the variable of site is tested, it is found that the "Good" sites have significantly lower specific gravities than do the "Average" sites, for comparable sections. The interaction between site and crown class reveals that the differences above hold for the mean of all sites, and for "Average" sites, but that on "Good" sites no significant difference exists between any of the crown classes.In managing second-growth stands of this nature the forester should keep in mind the variation in specific gravity that will occur. He can regulate rate of growth of individual trees and of stands, within limits, so as to produce wood of the desired quality.

A Biodegradable Formulation of MCH (3-Methylcyclohex-2-en-1-one) for Protecting Pseudotsuga menziesii from Dendroctonus pseudotsugae (Coleoptera: Curculionidae) Colonization

2020 ◽  
Vol 113 (4) ◽  
pp. 1858-1863 ◽  
Author(s):  
Gabriel G Foote ◽  
Christopher J Fettig ◽  
Darrell W Ross ◽  
Justin B Runyon ◽  
Tom W Coleman ◽  
...  
Keyword(s):  
New Mexico ◽  
Pseudotsuga Menziesii ◽  
Tree Mortality ◽  
Douglas Fir ◽  
Dendroctonus Pseudotsugae ◽  
Individual Tree ◽  
Significant Difference ◽  
Antiaggregation Pheromone ◽  
Individual Trees

Abstract Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, trees and stands can be protected from Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (DFB)-caused mortality by application of synthetic formulations of the beetle’s antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH). A biodegradable formulation of MCH, SPLAT MCH, was developed and evaluated for protecting individual Douglas-fir trees and small stands from colonization and mortality by DFB. In an individual-tree experiment in Idaho, both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of treated trees colonized and killed by DFB compared to untreated controls. SPLAT MCH was as effective as MCH bubble capsules for protecting individual trees. Both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of trees colonized and killed by DFB within 0.04-ha circular plots surrounding each treated tree compared to untreated controls. In 0.41 ha stands in New Mexico, both MCH bubble capsules and SPLAT MCH significantly reduced the proportion of trees colonized and killed by DFB compared to untreated controls, again with no differences observed between MCH treatments. In a similar stand level trial in Idaho, neither MCH treatment significantly reduced the proportion of trees colonized by DFB, and only MCH bubble capsules significantly reduced levels of tree mortality compared to untreated controls, but no significant difference was observed between SPLAT MCH and MCH bubble capsules. Overall, the results indicate that SPLAT MCH is as effective as MCH bubble capsules for protecting individual trees and small stands of Douglas-fir from DFB-caused mortality.

scholarly journals HIV Disclosure in Children in This Millenium – Should It still be an Issue?

2020 ◽  
pp. 1-11 ◽  
Author(s):  
A. U. Eneh ◽  
R. O. Ugwu ◽  
N. I. Paul
Keyword(s):  
Emotional Health ◽  
Healthcare Providers ◽  
Antiretroviral Drugs ◽  
Hiv Disclosure ◽  
Hiv Status ◽  
Care Givers ◽  
Significant Difference ◽  
Asking Questions ◽  
The Mean ◽  
The University

Background: As more children with HIV survive into adolescence and adulthood, one of the most difficult issues that families with HIV-infected children face is disclosure of their children’s status to them. Objective: To explore factors associated with disclosure or none disclosure and whether disclosure is beneficial or not. Methods: The mothers of HIV positive children who brought their children aged 5-18 years to the Paediatric Infectious Disease Clinic of the University of Port Harcourt Teaching Hospital from January to December 2015 were interviewed using a structured investigator administered questionnaire. Results: Of the 100 caregivers interviewed, 26.0% have disclosed the HIV status to the children. The mean age at disclosure was 14.42 ± 2.45 years. Care givers that have disclosed were significantly older (45.58±8.32 years vs 38.18±9.2 years; p = .0002). The mean age of children whose status have been disclosed was significantly higher than those who were yet to be aware of their status (14.42±2.45years vs 10.97±3.11 years; p = 0.00001). There was no significant difference in the mode of transmission and orphan status between the two groups. Disclosure was significantly more among children who were diagnosed between 5-10 years of age (14; 53.8%) (p=0.013), have taken antiretroviral drugs for over 24 months (22; 84.6%) (p= 0.003) and had at least one HIV-infected sibling (21; 80.8%) (p=0.00001). Among 13 (50.0%) whose status have been disclosed and 59 (79.7%) whose status had not been disclosed, the caregiver had disclosed the child’s status to others (p= 0.004). The major reason for disclosing was because the child was either asking questions on why he/she is taking drugs or he/she is refusing to take drugs (15; 57.7%) respectively. Only 6 (23.1%) caregivers disclosed because they felt the child has a right to know. Most difficult question asked by the children during disclosure was how they got the HIV (22; 84.6%). Reasons given for non-disclosure included fear of disclosure to others (74; 100%), child too young to understand (70; 94.5%) and fear of impact on child’s emotional health (42; 56.7%). Majority 20 (76.9%) of the care givers felt relieved after disclosure. Twenty-four (92.3%) caregivers felt disclosure had improved child’s adherence to antiretroviral therapy and determination to survive (22; 84.6%). Conclusion: Disclosure is beneficial to both the child and caregiver. Healthcare providers should encourage caregivers to disclose HIV status to their children as soon as possible.

scholarly journals A comparison of erythrocyte sedimentation rates of bloods anticoagulated with trisodium citrate and EDTA among TB presumptive patients at the University of Gondar comprehensive specialized hospital, northwest Ethiopia

2020 ◽  
Author(s):  
Zegeye Getaneh ◽  
Fekadu Ayelgn ◽  
Geletaw Asemahegn ◽  
Habtamu Geleta ◽  
Aregawi Yalew ◽  
...  
Keyword(s):  
Erythrocyte Sedimentation Rate ◽  
Sedimentation Rate ◽  
Sodium Citrate ◽  
Trisodium Citrate ◽  
Northwest Ethiopia ◽  
Cross Sectional ◽  
Erythrocyte Sedimentation ◽  
Significant Difference ◽  
The Mean ◽  
The University

Abstract Objective: The purpose of this study was comparing the erythrocyte sedimentation rate (ESR) results of trisodium citrate (TSC) and ethylene diamine tetra-acetic acid (EDTA) anticoagulants. A comparative cross-sectional study was conducted at the University of Gondar specialized referral hospital, northwest, Ethiopia. A total of 70 TB presumptive participants were recruited. From each of the 70 participants of the study, 3 and 1.6 ml of blood was collected in EDTA tubes and 0.4 ml of trisodium Citrate anticoagulant containing test tubes, respectively. Results: The mean ± SD values of ESR were 57.9 ± 41.45 mm/hr in EDTA and 50.99 ± 43.5 mm/hr in TSC anticoagulated blood. The mean difference of ESR values between EDTA and TSC blood (6.91 ± 13.66 mm/hr) was statistically significant. The Mean ± SD of ESR values using EDTA and TSC in males were 59.57 ± 42.31 and 53.57 ± 44.61 mm/hr while for females it was 54.71±40.44 and 46.04 ± 41.82 mm/hr, respectively. The study indicated that there was a significant difference between ESR values with EDTA and tri-sodium citrate anticoagulants. Keywords: Erythrocyte sedimentation rate, EDTA, Tri-sodium citrate, Westergren Method, Comparison

Evaluation of the Accessory Mental Foramen in a Pediatric Population Using Cone-Beam Computed Tomography

2014 ◽  
Vol 39 (1) ◽  
pp. 85-89 ◽  
Author(s):  
K Cantekin ◽  
AE Şekerci
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Pediatric Population ◽  
Mental Foramen ◽  
Cone Beam ◽  
Turkish Children ◽  
Accessory Mental Foramen ◽  
Significant Difference ◽  
The Mean ◽  
The University

Objective: The aim of the present study was to clarify the occurrence, diameter, and location of the accessory mental foramen (AMF) using cone-beam computed tomography (CBCT) images from a sample of Turkish children. Study design: This retrospective was carried out using a total of 275 CBCT images from child and adolescent patients were randomly selected from existing records in the Department of Oral and Maxillofacial Radiology at the University of Erciyes, Kayseri, Turkey. The mental foramen (MF) and AMF were assessed on axial, sagittal, and coronal CBCT slices. Results: The mean age was 10.51 ± 3.32 years, consisting of 139 males (mean age 10.64 ± 3.42) and 126 females (mean age 10.38 ± 3.18). Twenty-one AMFs were observed in 18 of 275 patients (6.5%, 10 boys and eight girls). There was no significant difference in gender in relation to the prevalence of AMF (p = 0.65). The mean area of the 21 AMFs and the MF on the side with the AMF were 0.7 mm2 (SD ± 0.5) and 3.8 mm2 (SD ± 2.2), respectively. Conclusion: It is important to stress that detecting the AMN using CBCT with 3D reconstructions may reduce the risk of paralysis, hemorrhage, and postoperative pain in this region. Our study presents the first report assessing the occurrence, diameter, and location of the AMF in the pediatric population using CBCT images. In this respect, not surprisingly, the mean size of the AMF of our population is smaller than other reports in the literature that involve adult populations.

Lateral variability of forest floor properties under second-growth Douglas-fir stands and the usefulness of composite sampling techniques

1986 ◽  
Vol 16 (5) ◽  
pp. 1128-1132 ◽  
Author(s):  
R. E. Carter ◽  
L. E. Lowe
Keyword(s):  
Bulk Density ◽  
Forest Floor ◽  
Chemical Properties ◽  
Mean Value ◽  
Douglas Fir ◽  
Mean Values ◽  
Weighted Arithmetic ◽  
Second Growth ◽  
The Mean ◽  
Composite Samples

Lateral variability of forest floor physical and chemical properties is examined in LF and H horizons under six naturally regenerated, second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands in coastal southwestern British Columbia. The number of samples required to predict a mean value at two confidence levels (P = 0.01 and 0.05) and two allowable errors (10 and 20%) are given for each variable. Total C, N, P, S, Zn, pH, and lipids were the least variable, requiring 2–13 samples to estimate a plot mean with a 10% allowable error at the 95% confidence level in LF horizons and 3–51 samples per lot in H horizons. Total K, Cu, and Mn were found to have moderately high lateral variability, while total Ca, Mn, Al, and Fe all required large numbers of samples to estimate the plot mean. In the second part of the paper, composite samples weighted by field depth and bulk density are compared with the depth and bulk density–weighted arithmetic mean of subsamples analyzed individually. Values from analysis of composite samples were within one standard deviation of the mean, with the exception of P and Cu in the LF horizons and lipids in both horizons. Composite values and mean values were significantly correlated across the six sites for all variables except lipids in LF horizons and total C and Mn in both horizons. Composite samples are suggested to provide an adequate estimate of the mean value of subsamples analyzed individually for most purposes and, for some variables (i.e., Ca, Fe, Al, and Mn), the only feasible method of obtaining an estimate of the mean.

YELLOW LAMINATED ROOT ROT OF DOUGLAS FIR

1954 ◽  
Vol 32 (1) ◽  
pp. 69-81 ◽  
Author(s):  
D. C. Buckland ◽  
A. C. Molnar ◽  
G. W. Wallis
Keyword(s):  
Root Rot ◽  
Douglas Fir ◽  
Common Occurrence ◽  
Individual Host ◽  
Second Growth ◽  
Bark Tissue ◽  
Causal Fungus ◽  
The Common ◽  
The Individual ◽  
Individual Trees

Yellow laminated root rot occurs in most native conifers throughout the range of Douglas fir in British Columbia. The cause of this disease has been ascribed to a variety of Poria weirii Murr., or a species of Poria distinct from P. weirii. The fungus grows from infected to healthy roots through physiologically weakened contacting points or fusions, and the disease is most prevalent in Douglas fir because of the common occurrence of root fusion in this species. Douglas fir is susceptible at any age over six years but individual trees show marked differences in their resistance to killing by the disease. The symptom picture varies greatly between infected trees and is directly related to the resistance shown by the individual host. Inoculum may remain viable for over 50 years in stumps and roots. The fungus does not appear to spread through the soil nor does it appear to be able to penetrate healthy bark tissue. Although the control of this disease is currently important in many localized areas, several characteristics in the behavior of the causal fungus indicate that it will become more important as management of second growth Douglas fir forests becomes more intensive.

Gender and Achievement in Mathematics by Indigenous African Students Majoring in Mathematics

1996 ◽  
Vol 78 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Varghese I. Cherian ◽  
James Siweya
Keyword(s):  
Mathematics Achievement ◽  
Female Students ◽  
First Year ◽  
Achievement Scores ◽  
Criterion Measure ◽  
African Students ◽  
The North ◽  
Significant Difference ◽  
The Mean ◽  
The University

This study investigated gender differences in mathematics achievement of first-year B.Sc. Degree (mathematics major) students at the University of the North in South Africa. They were 214 male and female students. The ages of students ranged from 17 to 66 for 178 men ( M = 22.3) and 17 to 35 years for 36 women ( M = 21.5). With their marks in mathematics as the criterion measure, no significant difference in the mean achievement scores of the two groups was noted; however, a qualitative examination of the category-wise achievement scores of the two groups suggests further study of the bases for some women's achievement to be higher than the men's.

scholarly journals Use of Multi-Temporal LiDAR to Quantify Fertilization Effects on Stand Volume and Biomass in Late-Rotation Coastal Douglas-Fir Forests

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 517
Author(s):  
Jason Kelley ◽  
John A. (Tony) Trofymow ◽  
Juha M. Metsaranta ◽  
Cosmin N. Filipescu ◽  
Christopher Bone
Keyword(s):  
Site Index ◽  
Douglas Fir ◽  
Stem Volume ◽  
Treatment Area ◽  
Forest Inventories ◽  
Silvicultural Treatments ◽  
Second Growth ◽  
Multi Temporal ◽  
Fertilization Effects ◽  
Mean Square Errors

Forest fertilization is common in coastal British Columbia as a means to increase wood production and potentially enhance carbon sequestration. Generally, the effects of fertilization are determined by measuring sample plots pre- and post-treatment, resulting in fertilization effects being determined for a limited portion of the treatment area. Applications of remote sensing-based enhanced forest inventories have allowed for estimations to expand to the wider forested area. However, these applications have not focused on monitoring the effects of silvicultural treatments. The objective of this research was to examine if a multi-temporal application of the LiDAR area-based method can be used to detect the fertilization effects on volume, biomass, and height in a second-growth Douglas-fir (Pseudotsuga menziesii) stand. The study area on Vancouver Island was fertilized in January 2007, and sample plots were established in 2011. LiDAR acquisitions were made in 2004, prior to fertilization, and in 2008, 2011, and 2016, covering both treated and untreated areas. A total of 29 paired LiDAR blocks, comprised of four 20 m resolution raster cells, were selected on either side of the fertilization boundary for analysis of the effects across several different stand types differing in the percentage of Douglas-fir, site index, and age. Random forest (RF) plot-level models were developed to estimate total stem volume and total stem biomass for each year of LiDAR acquisition using an area-based approach. Plot level results showed an increase in stem volume by 13% fertilized over control from 2005 to 2011, which was similar to a 14% increase in above-ground carbon stocks estimated using a tree-ring stand reconstruction approach. Plot-level RF models showed R2 values of 0.86 (volume) and 0.92 (biomass) with relative cross-validated root mean square errors of 12.5% (volume) and 11.9% (biomass). For both the sample plots and LiDAR blocks, statistical results indicated no significant differences in volume or biomass between treatments. However, significant differences in height increments were detected between treatments in LiDAR blocks. The results from this research highlight the promising potential for the use of enhanced forest inventory methods to rapidly expand the assessment of treatment effects beyond sample plots to the stand, block, or landscape level.

scholarly journals A comparison of erythrocyte sedimentation rates of bloods anticoagulated with trisodium citrate and EDTA among TB presumptive patients at the University of Gondar comprehensive specialized hospital, northwest Ethiopia

2020 ◽  
Author(s):  
Zegeye Getaneh ◽  
Fekadu Ayelgn ◽  
Geletaw Asemahegn ◽  
Habtamu Geleta ◽  
Aregawi Yalew ◽  
...  
Keyword(s):  
Erythrocyte Sedimentation Rate ◽  
Sedimentation Rate ◽  
Sodium Citrate ◽  
Trisodium Citrate ◽  
Northwest Ethiopia ◽  
Cross Sectional ◽  
Erythrocyte Sedimentation ◽  
Significant Difference ◽  
The Mean ◽  
The University

Abstract Objective: The purpose of this study was comparing the erythrocyte sedimentation rate (ESR) results of trisodium citrate (TSC) and ethylene diamine tetra-acetic acid (EDTA) anticoagulants. A comparative cross-sectional study was conducted at the University of Gondar specialized referral hospital, northwest, Ethiopia. A total of 70 TB presumptive participants were recruited. From each of the 70 participants of the study, 3 and 1.6 ml of blood was collected in EDTA tubes and 0.4 ml of trisodium Citrate anticoagulant containing test tubes, respectively. Results: The mean ± SD values of ESR were 57.9 ± 41.45 mm/hr in EDTA and 50.99 ± 43.5 mm/hr in TSC anticoagulated blood. The mean difference of ESR values between EDTA and TSC blood (6.91 ± 13.66 mm/hr) was statistically significant. The Mean ± SD of ESR values using EDTA and TSC in males were 59.57 ± 42.31 and 53.57 ± 44.61 mm/hr while for females it was 54.71±40.44 and 46.04 ± 41.82 mm/hr, respectively. The study indicated that there was a significant difference between ESR values with EDTA and tri-sodium citrate anticoagulants. Keywords: Erythrocyte sedimentation rate, EDTA, Tri-sodium citrate, Westergren Method, Comparison

scholarly journals ENTREPRENEURSHIP EDUCATION PROGRAMME AND ITS INFLUENCE IN DEVELOPING ENTREPRENEURSHIP KEY COMPETENCIES AMONG UNDERGRADUATE STUDENTS

2017 ◽  
Vol 75 (2) ◽  
pp. 144-156
Author(s):  
James Edomwonyi Edokpolor ◽  
Kayode Somorin
Keyword(s):  
Undergraduate Students ◽  
Survey Design ◽  
Entrepreneurship Education ◽  
Education Programme ◽  
Test Statistics ◽  
Significant Difference ◽  
Key Competencies ◽  
The Mean ◽  
The University ◽  
Research Assistants

The intent of this research is to assess the implementation state of entrepreneurship programme and its influence in developing entrepreneurship key competencies among undergraduate students. The survey design was employed for the research. A total population of 8,101 undergraduate students from University of Benin was used. A sample of 382 undergraduate students was used for the research. A structured questionnaire, validated by two experts was used for the data collection. The Cronbach alpha statistical method was employed to determine the reliability of the instrument, which yielded the coefficient alpha value of 0.87. Twenty items questionnaire was administered to the respondents with the help of two trained research assistants. The data were analyzed using the mean, standard deviation, and t-test statistics. The research revealed that entrepreneurship programme is not properly implemented particularly at the university level. It also revealed that students are not well-equipped with entrepreneurship key competencies such as creative and innovative skills that would have helped them in starting and running their own business. It also revealed that there was no significant difference between the mean responses of Science and Arts/Humanity-based students regarding the implementation state of entrepreneurship programme. It further revealed that there was no significant difference between the mean responses of Science and Arts/Humanity-based students regarding the extent to which entrepreneurship programme has equipped students with creative and innovative skills. Consequently, the authors drew a useful conclusion for the subject matter. Providing sufficient amount of financial resources, involving employers of labour, sourcing for qualified teaching and non-teaching personnel, procuring the state-of-the-art infrastructural facilities, as well as utilizing appropriate instructional methods, that would help in equipping students with creative and innovative skills for starting and operating their own businesses were further recommended. Keywords: creative skills, entrepreneurship education, innovative skills, operating business, starting business, unemployment situation.

Sign in / Sign up

Export Citation Format

Share Document