Examining bias in estimating the response variable and assessing the effect of using alternative plot designs to measure predictor variables in diameter growth modeling

Diameter growth of Douglas-fir (Pseudotsuqa menziesii (Mirb.) Franco) estimated from increment cores was compared with that obtained from repeated measurements of tree diameter on permanent plots located in two Douglas-fir study areas in the central Coast Range of Oregon. Growth was measured for a 6-year period (1979- 1985). Diameter growth measured from two increment cores taken opposite to each other, provided an unbiased estimate of the stand average diameter-growth as determined from repeated measurements of diameter. However, a statistically significant trend was found in the differences in individual tree diameter-growth between the two methods of measurements. A nonlinear model was used to characterize these differences. The practical significance of the observed trend and the use of the developed model as a calibration tool, depend upon the reliability desired by the particular user. The second part was a simulation study to examine the effect upon growth model predictions of using alternative sample plot designs to measure predictor variables. Five forest stands were generated through computer simulation by use of field data and random spatial distributions. Two variable-radius plot designs and four fixed-radius circular plots were used to sample simultaneously the generated stands . Sample data then were used to simulate diameter and gross-basal-area growth in both a single-tree/distance-independent growth model and a whole-stand/diameter-free growth model. In comparing the growth predictions of each model, the plot design used to develop the model was the standard against which alternative plot designs were evaluated. Both fixed and variable area plots provide, with varying degree of precision, unbiased estimates of stand-level predictor variables. For both models, average gross basal area growth-rate predictions from 50 samples of each alternative design were not significantly different from the standard design. However, large differences in individual predictions may occur as a result of using a different plot design. The magnitude of these differences depend on the stand size and density

Effects of stand density on site index in thinned stands of Douglas-fir in the Pacific Northwest

In site index studies, the hypothesis that height growth of most conifers is independent of stand density is commonly accepted. However, some studies have shown height growth to be influenced by density particularly on medium to poor sites. In this study two locations representing a high quality site (Hoskins area, Oregon) and a relatively lower site (Rocky Brook area, Washington) were selected to examine the effect of stand density on site index in natural stands of Douglas-fir which has been repeatedly thinned at different intensities. The data for the study were obtained from the periodic measurements of the stand characteristics at the end of each thinning treatment period. The average height of the largest 40 trees per acre was used as basis for the comparison of height growth patterns among the different thinning regimes. Simple linear regression was found adequate to describe height growth of the individual plots over the age range studied (20 to 36 years at the Hoskins and 27 to 44 years at the Rocky Brook). Covariance analysis using multiple regression was used to test differences in height growth within plots under similar thinning treatments. The coefficients of the height growth equations from individual plots were used in the analysis to test for differences in height growth among the different thinning regimes. The results of the study indicated that on both sites, site index was not influenced by density over a wide range of stocking and within the age range studied

Chemical Investigation of Some Capparis Species Growing in Egypt and their Antioxidant Activity

Capparis cartilaginea and C. deserti growing in Egypt were investigated for their glucosiolates and rutin content. From Capparis cartilaginea four isothiocynates were isolated and identified using GC and EI/MS techniques. These compounds were butyl isothiocyanate (1), 6-methylsulphonylhexyl isothiocyanate (2), 7-methylsulphonylheptyl isothiocyanate (3) and 5-benzylsulphonyl-4-pentenyl isothiocyanate (4). In addition to compounds (1) and (2), two other compounds were isolated and identified from Capparis deserti. These compounds are 3-methylthiopropyl isothiocyanate (5) and [11-(2-butenylthio)6-undecenyl isothiocyanate] (6). Compounds (1), (2), (5) and (6) are reported in this study for the first time from Capparis deserti. The main flavonoid component in the studied species was isolated and identified as rutin by comparing the data with those reported. Also, quantitative evaluation of rutin in the two species was carried out by TLC-densitometric analysis. The antioxidant activity was done using diphenylpicrylhydrazyl (DPPH) radical scavenging method. The butanol fraction from C. cartilaginea and C. deserti showed the highest antioxidant properties

YAG Laser in the Treatment of Nail Psoriasis: Clinical and Dermoscopic Assessment

Background: The Nd:YAG laser has emerged as a promising modality for the management of nail psoriasis owing to its ability for deep penetration of the skin surface, which has the advantage of destroying deep vessels. Objective: To assess the efficacy and safety of Nd:YAG laser in treating nail psoriasis. Methods: The present study was a randomized controlled study, conducted on 20 patients of both sexes (age older than 12 years) with mild to moderate psoriasis with nail involvement. We utilized facial telangiectasia parameters of Nd:YAG laser and beam diameter of 2.5 mm. Laser energy started with 110 J/cm2 in the first session and 130 J/cm2 in the rest of the sessions. Sessions were performed once monthly for up to 6 sessions. Results: We found no statistically significant difference in total Nail Psoriasis Severity Index (NAPSI) and nail bed scores before and after treatment among the treated group. However, there was statistically significant improvement in nail matrix score after treatment. On the other hand, the control group did not show any statistically significant changes for all scores throughout the study, except for the nail matrix score mean difference (0.35 ± 1.23 vs -1.00 ± 1.86 in the treated group). The degree of dermoscopic improvement was evident in the treated group (45% vs 25% in the control group). However, it was not statistically significant because of small sample size. The patients' satisfaction and the external investigator's assessment showed statistically significant negative correlation with total NAPSI mean difference in the treated group. Conclusion: The role of Nd:YAG laser in nail psoriasis is still controversial

Single-Phase Charging of Six-Phase Integrated On-Board Battery Charger using Predictive Current Control

This work was achieved by the financial support of ITIDAs ITAC collaborative funded project under the category type of advanced research projects (ARP) and Grant Number ARP2020.R29.7.This work was achieved by the financial support of ITIDAs ITAC collaborative funded project under the category type of advanced research projects (ARP) and Grant Number ARP2020.R29.7.Integrated On-Board Battery Chargers (IOBCs) have shown promise as an elegant charging solution for electric vehicles in recent literature. Although the three-phase charging technique of IOBCs has extensively been discussed in the literature, single-phase charging is still a challenging research topic. The Predictive Current Control (PCC) approach has shown many benefits, including a straightforward algorithm, simple implementation, comparatively quick response, and appropriate performance, when compared to conventional control techniques. This paper investigates the impact of single-phase charging of a six-phase-based IOBC system with different winding configurations using PCC, which, up to the best authors’ knowledge, has not been conceived thus far. Under single-phase charging, the zero-sequence current component is utilized to ensure zero torque production during charging mode. Since the impedance of the zero subspace is highly affected by the employed winding design, the performance of PCC with different winding layouts of either induction machine (IM) or permanent magnet synchronous machine (PMSM) is investigated and compared. The proposed method is experimentally validated using a 1.1kW six-phase IM and a 2 kW 12-slot/10-pole PMSM. Finite Element analysis is also carried out to investigate the effect of single-phase charging mode on the induced radial forces and vibration level when PM machine is employed

COMPARATIVE ANALYSIS OF BIOLOGICAL ACTIVITY OF SILYBUM MARIANUM L. FOOD SUPPLEMENTS AVAILABLE ON MARKET: INVITRO STUDY

Objective: Silybum marianum L. Food Supplements that contain silymarin is widely used as a therapeutic agent in liver diseases. Many brands are available on the market in USA, Egypt, Europe and other countries. The objective of this study was to compare the biological activity in different preparations of silymarin available on the market in USA and Egypt using paracetamol-induced oxidative stress injury on primary cultured rat hepatocytes. Methods: Forty four silymarin samples available on the market were collected from USA (24) and Egypt (20) and tested for hepat protective antioxidant effects on primary cultured rat hepatocytes. Cytotoxicity was measured by MTT [3-(4, 5-dimethyl-thiazol-2)-2,5-diphenyl tetrazolium bromide] assay and lactate dehydrogenase (LD) leakage into culture medium. Antioxidant effects were determined by glutathione reductase (GR), and Nitric oxide (NO) assays in silymarin, pretreated rat hepatocytes for 2 h followed by incubation with 25 mM paracetamol over a period of 1 h. Therapeutic index was calculated for each tested sample for comparative analysis. Results: Silymarin preparations significantly decreased toxicity induced by paracetamol in rat hepatocytes, decreased lactate dehydrogenase leakage and prevented GSH depletion (P<0.01) and returned NO to basal levels in rat hepatocytes. The therapeutic index was 80, 40 and 20 for samples No. 20, 19 and 5 respectively. Conclusions: The 44 different silymarin preparations tested in this study exhibited variation in antioxidant capacity and in reducing nitric oxide produced as a result of paracetamol injury. This variation in biological activity did not always correspond to the amount of silymarin recorded on samples

Detrusor wall thickness compared to other non-invasive methods in diagnosing men with bladder outlet obstruction: A prospective controlled study

AbstractIntroductionThe current study aims to compare the diagnostic accuracy of detrusor wall thickness to other noninvasive, tools, using pressure flow studies as a reference, in the assessment of bladder outlet, obstruction among men presenting with lower urinary tract symptoms.Patients and MethodsMen aged 50 or older presenting with lower urinary tract symptoms were evaluated for bladder outlet, obstruction using detrusor wall thickness (measured by a transabdominal 7.5MHz ultrasound) and, other non-invasive tools (namely uroflowmetry, post-void residual, and prostate volume), and the results were compared to pressure flow study.ResultsDetrusor wall thickness ranged from 0.7mm to 7mm (mean±SD of 2.39±1.64mm), and 21 patients, were classified as obstructed (thickness≥2mm). Based on pressure flow study 23 patients had, bladder outlet obstruction. Detrusor wall thickness had the highest accuracy (88.0%), the highest, specificity (92.6%) and the highest positive predictive value (90.5%) among the non-invasive tests.ConclusionsDetrusor wall thickness measurement can be used to diagnose and quantify bladder outlet obstruction, non-invasively in men with lower urinary tract symptoms, with an accuracy approaching that of the standard pressure flow studies

Explore the E-Learning Management System Lower usage during COVID-19 Pandemic

During the COVID-19 pandemic, several universities are finding it difficult to provide and use online and e-learning systems. Blackboard, for example, is an e-learning system with various wonderful features that would be useful during the COVID-19 pandemic. However, knowing the acceptance variables as well as the primary problems that contemporary e-learning technologies confront is crucial for efficient utilization. The growing number of students attending different instructional organizations has resulted in a greater volume of material being needed in these organizations both from the academic and professional workforce and also because learning management systems and e-learning are indeed the university prospect, several more universities and colleges have accepted them. The purpose is to analyze the most popular E-learning system, the Blackboard system, and the authors suggest a learning management control system to accommodate major e-learning features. A Blackboard system is a plethora of academic perspectives, research, ideas, theories, and affective responses to the virtual learning environment. To use it, the technology acceptance model in times of crisis (TAMTC) has been developed as a way to evaluate student acceptability. The existing literature demonstrates that the field of information administration is constantly changing due to the effect of learning technologies like the blackboard system. Given their reduced utilization of the system, the data reveal a high level of student acceptability. The conclusions of this study provide important recommendations for policymakers, managers, developers, and academics, allowing them may further understand the key factors of successfully using an e-learning system during the COVID-19 epidemic

Explore the E-Learning Management System Lower usage during COVID-19 Pandemic

During the COVID-19 pandemic, several universities are finding it difficult to provide and use online and e-learning systems. Blackboard, for example, is an e-learning system with various wonderful features that would be useful during the COVID-19 pandemic. However, knowing the acceptance variables as well as the primary problems that contemporary e-learning technologies confront is crucial for efficient utilization. The growing number of students attending different instructional organizations has resulted in a greater volume of material being needed in these organizations both from the academic and professional workforce and also because learning management systems and e-learning are indeed the university prospect, several more universities and colleges have accepted them. The purpose is to analyze the most popular E-learning system, the Blackboard system, and the authors suggest a learning management control system to accommodate major e-learning features. A Blackboard system is a plethora of academic perspectives, research, ideas, theories, and affective responses to the virtual learning environment. To use it, the technology acceptance model in times of crisis (TAMTC) has been developed as a way to evaluate student acceptability. The existing literature demonstrates that the field of information administration is constantly changing due to the effect of learning technologies like the blackboard system. Given their reduced utilization of the system, the data reveal a high level of student acceptability. The conclusions of this study provide important recommendations for policymakers, managers, developers, and academics, allowing them may further understand the key factors of successfully using an e-learning system during the COVID-19 epidemic