A Comparison of PCB Congener Distributions in Two Point-Source Contaminated Lakes and One Uncontaminated Lake in Ontario

1989 ◽  
Vol 24 (1) ◽  
pp. 23-46 ◽  
Author(s):  
C. R. Macdonald ◽  
C. D. Metcalfe
Keyword(s):  
Point Source ◽  
Yellow Perch ◽  
Water Solubility ◽  
Smallmouth Bass ◽  
Physical Factors ◽  
Organic Carbon Content ◽  
Substitution Pattern ◽  
Significant Difference ◽  
The Individual ◽  
High Organic Carbon Content

Abstract PCB congener accumulation in biota and sediments involves several processes, including physical factors characterized by octanol-water partition coefficients and water solubility, and chemical factors which are influenced by the degree of chlorination and the substitution pattern of the individual congeners. The present study was conducted to determine if PCB congeners are distributed in a consistent pattern in two lakes known to have received point-source contamination with PCBs, and a control lake with no known point source. Samples of 4 groups of biota, water and sediment indicated that each lake had a unique pattern of congener distribution which was probably related to the source of the contamination. A comparison of total and individual PCB congener concentrations within each study lake showed that no one species consistently contained the highest residues of PCBs. Smallmouth bass had the highest concentration of PCBs in Rice lake while yellow perch was highest in Lakes Clear and Scugog. Sediments contained lower concentrations of PCBs than biota and did not show enrichment of higher chlorinated congeners, despite having high organic carbon content. Within the contaminated lakes, young-of-the-year (YOY) and older yellow perch had the same congener pattern, and there was no significant difference in their PCB concentration. This indicates that equilibrium concentrations of PCBs are established rapidly in the young fish and that all congeners equilibrate at the same rate.

Spatial variability of trace metals in Podzols of northern forest ecosystems: Sampling implications

2003 ◽  
Vol 83 (5) ◽  
pp. 581-587 ◽  
Author(s):  
J. D. MacDonald ◽  
W. H. Hendershot
Keyword(s):  
Trace Metals ◽  
Spatial Variability ◽  
Point Source ◽  
Forest Ecosystems ◽  
Physical Factors ◽  
Individual Plant ◽  
Forest Site ◽  
Organic Carbon Content ◽  
Metal Concentrations ◽  
Northern Forest

The concentrations of metals in soils are spatially heterogeneous and soil sampling carried out when studying metals in forest ecosystems is often inadequate. We examined the spatial variability of Cd, Cu, Mn, Ni, Pb and Zn in northern forest ecosystems on a transect with distance from two point source emitters with the goal of providing basic information about the distribution and variability of metals in these soils. Samples were taken under six sampling points at four depths from three experimental sites on each of the two transects. Soils were analysed for acid digestible metals, pH and organic carbon content. Standard deviation, coefficients of variation, mean and medians were analysed for each horizon of each site. It was observed that Cu and Mn variability is higher in closer proximity to the point source while the variability of Zn increased with decreasing soil pH. In Sudbury, emitted metals Ni and Cu accumulate together in soils, whereas in Rouyn-Noranda, with the exception of Cd and Zn, metal concentrations were not related in forest floors. Observations suggest that physical factors influencing where metals are deposited as well as the inherent variability in soil chemical characteristics, and the distance from the point source can all act together to result in high variability in soil metal concentrations in a single forest site. Sampling in the interest of relating vegetation metal concentrations or response to soil metals should be carried out on an individual plant basis with multiple samples taken for each individual. Soil samples taken at intervals of 1 to 1.7 m will provide relative error in estimating soil concentrations of 10% or 20%, respectively. Key words: Spatial variability, trace metals, podzolic soils, smelter emissions

Concentration and Distribution of PCB Congeners in Isolated Ontario Lakes Contaminated by Atmospheric Deposition

1991 ◽  
Vol 48 (3) ◽  
pp. 371-381 ◽  
Author(s):  
C. R. Macdonald ◽  
C. D. Metcalfe
Keyword(s):  
Atmospheric Deposition ◽  
Yellow Perch ◽  
General Pattern ◽  
Dry Weight ◽  
Smallmouth Bass ◽  
Trophic Levels ◽  
Pcb Congeners ◽  
Significant Difference ◽  
Golden Shiner ◽  
Wet Weight

The concentration of 19 PCB congeners was analysed in biota, sediments, water, and suspended solids in four central Ontario lakes in which atmospheric deposition was the major source of PCB contamination. Input from the atmosphere resulted in total congener concentrations of 1–2 ng∙L−1 dissolved in water, 10–50 μg∙kg−1 (dry weight} in sediment, 5–10 μg∙kg−1 (wet weight) in biota from lower trophic levels (i.e. zooplankton, golden shiner (Notemigonus crysoleucas)), and 10–30 μg∙kg−1 (wet weight) in fish from upper trophic levels (yellow perch (Perca fiavescens), smallmouth bass (Micropterus dolomieui)). The dominant PCB congeners in the lakes were the trichlorobiphenyl congeners 31(28} and the hexachlorobiphenyl congeners 153 and 138, consistent with congener distributions reported for vapour- and particulate-bound PCBs in the atmosphere. Discriminant analysis indicated slight differences in congener patterns between the study lakes, but the general pattern for isolated lakes was substantially different from point-source contaminated lakes, primarily due to the high proportion of congeners 31(28). There was no significant difference in the total PCB concentrations in biota (lipid basis) between lakes, but within the lakes, total PCB concentrations were significantly higher in yellow perch than in biota from lower trophic levels.

Writing in Aphasia Rehabilitation: Cursive vs Manuscript

1976 ◽  
Vol 41 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Daniel R. Boone ◽  
Harold M. Friedman
Keyword(s):  
Correct Response ◽  
The Other ◽  
Read Aloud ◽  
Writing Style ◽  
Reading And Writing ◽  
Manual Responses ◽  
Significant Difference ◽  
Written Form ◽  
The Individual ◽  
Read Number

Reading and writing performance was observed in 30 adult aphasic patients to determine whether there was a significant difference when stimuli and manual responses were varied in the written form: cursive versus manuscript. Patients were asked to read aloud 10 words written cursively and 10 words written in manuscript form. They were then asked to write on dictation 10 word responses using cursive writing and 10 words using manuscript writing. Number of words correctly read, number of words correctly written, and number of letters correctly written in the proper sequence were tallied for both cursive and manuscript writing tasks for each patient. Results indicated no significant difference in correct response between cursive and manuscript writing style for these aphasic patients as a group; however, it was noted that individual patients varied widely in their success using one writing form over the other. It appeared that since neither writing form showed better facilitation of performance, the writing style used should be determined according to the individual patient’s own preference and best performance.

Aftermath Effect Of GST On Consumer Purchasing Power

2019 ◽  
Vol 118 (5) ◽  
pp. 122-131
Author(s):  
S. Thowseaf ◽  
M. Ayisha Millath ◽  
K. Malik Ali
Keyword(s):  
Living Standard ◽  
Purchasing Power ◽  
Percentage Increase ◽  
Defense System ◽  
Key Factors ◽  
Predominant Role ◽  
Tax System ◽  
Significant Difference ◽  
The Individual ◽  
Taxation System

Tax is an important source of income for the country. It is through tax; country strengthens its defense system, infrastructure, and government. Hence, tax system plays a predominant role in developing country’s economy. The complication in taxation system and liberty for taxpayers are key factors generating loopholes for corruption. GST is superior taxation system over VAT but, if neither properly implemented nor scrutinized according to the economy, it is people residing get affected.  GST taxation system is capable of increasing legal transaction, reducing corruption and complexity that exists in current taxation. India is 166th country to adopt GST and GST taxation slab in India is 0%, 5%, 12%, 18% and 28%.  Although average Tax levied is 14.8750% in India, it is 28% tax that is levied for most of the commodities, which are directly or indirectly used in everyday life of common individuals. Despite, GST being favorable to distributor in-terms of profit and government to attain tax by increasing legal transaction through invoice. It is noted that for the same percentage of taxation, the amount does not vary for VAT and GST. The tax slab decreased for 71 commodities and no change in 21 commodities; there has been an increase in tax slab for 60 commodities. 26% taxation was levied for most commodities considered was currently levied by 28% taxation which is greater than before. It was found that average tax percentage reduced was calculated to be 6.07143. The average tax percentage increase was calculated to be 4.7833 percentage for the considered commodities. The overall tax average tax percentage is estimated to be 14.8750% which does not have a significant difference concerning tax levied before GST, which was calculated to be 15.7829% for considered commodities. Therefore, the consumer purchasing power and overall living standard of the individual in India will remain almost same.

Comparison of decay rates of faecal indicator organisms in recreational coastal water and sediment

2002 ◽  
Vol 2 (3) ◽  
pp. 131-138 ◽  
Author(s):  
D.L. Craig ◽  
H.J. Fallowfield ◽  
N.J. Cromar
Keyword(s):  
Water Column ◽  
Coastal Water ◽  
Decay Rates ◽  
Organic Carbon Content ◽  
Indicator Organisms ◽  
Filtration Method ◽  
E Coli ◽  
Water And Sediment ◽  
Increased Risk ◽  
High Organic Carbon Content

A laboratory based microcosm study utilising intact non-sterile sediment cores was undertaken to determine the survival of the faecal indicator organisms Escherichia coli, Enterococcus faecium and somatic coliphage in both recreational coastal water and sediment. Overlying water was inoculated with the test organisms and incubated at 10°C, 20°C or 30°C. E. coli, enterococcus and coliphage were enumerated from the water column and sediment by the membrane filtration method, Enterolert (IDEXX Laboratories) and the double-agar overlay methods respectively on days 0, 1, 2, 7, 14 and 28 following inoculation. It was demonstrated that for all organisms, greater decay (k; d-1) occurred in the water column compared to sediment. Sediment characteristics were found to influence decay, with lowest decay rates observed in sediment consisting of high organic carbon content and small particle size. Decay of E. coli was significantly greater in both the water column and sediment compared with enterococcus and coliphage under all conditions. Decay of enterococcus was found to closely resemble that of coliphage decay. Survival of all organisms was inversely related to temperature, with greatest decay at 30°C. However, increased temperature had a less significant impact on survival of enterococcus and coliphage compared with E. coli. The importance of this study for estimating risk from recreational exposure is great if some pathogenic microorganisms behave similarly to the organisms tested in this study. In particular if survival rates of pathogens are similar to enterococcus and coliphage, then their ability to accumulate in coastal sediment may lead to an increased risk of exposure if these organisms are resuspended into the water column due to natural turbulence or human recreational activity.

scholarly journals A comparison between Asians and Caucasians in the dimensions of the femoral isthmus based on a 3D-CT analysis of 1189 adult femurs

2021 ◽  
Author(s):  
Darius M. Thiesen ◽  
Dimitris Ntalos ◽  
Alexander Korthaus ◽  
Andreas Petersik ◽  
Karl-Heinz Frosch ◽  
...  
Keyword(s):  
Proximal Femur ◽  
Strong Predictor ◽  
Matched Pair ◽  
3D Ct ◽  
Femur Fractures ◽  
Matched Pair Analysis ◽  
Significant Difference ◽  
Ct Analysis ◽  
Ct Data ◽  
The Individual

Abstract Introduction For successful intramedullary implant placement at the femur, such as nailing in unstable proximal femur fractures, the use of an implant that at least reaches or exceeds the femoral isthmus and yields sufficient thickness is recommended. A number of complications after intramedullary femoral nailing have been reported, particularly in Asians. To understand the anatomical features of the proximal femur and their ethnic differences, we aimed to accurately calculate the femoral isthmus dimensions and proximal distance of Asians and Caucasians. Methods In total, 1189 Asian and Caucasian segmented 3D CT data sets of femurs were analyzed. The individual femoral isthmus diameter was precisely computed to investigate whether gender, femur length, age, ethnicity or body mass index have an influence on isthmus diameters. Results The mean isthmus diameter of all femurs was 10.71 ± 2.2 mm. A significantly larger diameter was found in Asians when compared to Caucasians (p < 0.001). Age was a strong predictor of the isthmus diameter variability in females (p < 0.001, adjusted r2 = 0.299). With every year of life, the isthmus showed a widening of 0.08 mm in women. A Matched Pair Analysis of 150 female femurs showed a significant difference between isthmus diameter in Asian and Caucasian femurs (p = 0.05). In 50% of the cases the isthmus was found in a range of 2.4 cm between 16.9 and 19.3 cm distal to the tip of the greater trochanter. The female Asian femur differs from Caucasians as it is wider at the isthmus. Conclusions In absolute values, the proximal isthmus distance did not show much variation but is more proximal in Asians. The detailed data presented may be helpful in the development of future implant designs. The length and thickness of future standard implants may be considered based on the findings.

A Comparison of Colectomy Outcomes Utilizing Open, Laparoscopic, and Robotic Techniques

2020 ◽  
pp. 000313482097338
Author(s):  
Elizabeth McCarthy ◽  
Benjamin L. Gough ◽  
Michael S. Johns ◽  
Alexandra Hanlon ◽  
Sachin Vaid ◽  
...  
Keyword(s):  
Postoperative Recovery ◽  
Logistic Regression Models ◽  
Community Institution ◽  
Physical Status Classification ◽  
Estimated Blood Loss ◽  
Comparative Review ◽  
Significant Difference ◽  
American Society ◽  
The Individual ◽  
American Society Of Anesthesiologists

Introduction Robotic colectomy could reduce morbidity and postoperative recovery over laparoscopic and open procedures. This comparative review evaluates colectomy outcomes based on surgical approach at a single community institution. Methods A retrospective review of all patients who underwent colectomy by a fellowship-trained colon and rectal surgeon at a single institution from 2015 through 2019 was performed, and a cohort developed for each approach (open, laparoscopic, and robotic). 30-day outcomes were evaluated. For dichotomous outcomes, univariate logistic regression models were used to quantify the individual effect of each predictor of interest on the odds of each outcome. Continuous outcomes received a similar approach; however, linear and Poisson regression modeling were used, as appropriate. Results 115 patients were evaluated: 14% (n = 16) open, 44% (n = 51) laparoscopic, and 42% (n = 48) robotic. Among the cohorts, there was no statistically significant difference in operative time, rate of reoperation, readmission, or major complications. Robotic colectomies resulted in the shortest length of stay (LOS) (Kruskal-Wallis P < .0001) and decreased estimated blood loss (EBL) (Kruskal-Wallis P = .0012). Median age was 63 years (interquartile range [IQR] 53-72). 54% (n = 62) were female. Median American Society of Anesthesiologists physical status classification was 3 (IQR 2-3). Median body mass index was 28.67 (IQR 25.03-33.47). A malignant diagnosis was noted on final pathology in 44% (n = 51). Conclusion Among the 3 approaches, there was no statistically significant difference in 30-day morbidity or mortality. There was a statistically significant decreased LOS and EBL for robotic colectomies.

scholarly journals Lignin-Containing Coatings for Packaging Materials—Pilot Trials

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1595
Author(s):  
Asif Javed ◽  
Peter Rättö ◽  
Lars Järnström ◽  
Henrik Ullsten
Keyword(s):  
High Speed ◽  
Water Solubility ◽  
Transmission Rate ◽  
Kraft Lignin ◽  
Packaging Materials ◽  
Water Contact ◽  
Pilot Trials ◽  
Significant Difference ◽  
Ph Level ◽  
Ammonium Zirconium Carbonate

One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples.

Safety climate and related factors in rehabilitation nurses of hospitals in Iran

Work ◽  
2021 ◽  
pp. 1-8
Author(s):  
Javad vatani ◽  
Zahra Khanikosarkhizi ◽  
Mohammad Ali Shahabi Rabori ◽  
mohammad khandan ◽  
Mohsen aminizadeh ◽  
...  
Keyword(s):  
Safety Climate ◽  
Cross Sectional Study ◽  
P Value ◽  
Related Factors ◽  
Cross Sectional ◽  
Climate Assessment ◽  
Safety Work ◽  
Significant Difference ◽  
Training Courses ◽  
The Individual

BACKGROUND: Safety climate is a common insight of staff that indicates individuals’ attitudes toward safety and priority of safety at work. OBJECTIVES: Nursing is a risky job where paying attention to safety is crucial. The assessment of the safety climate is one of the methods to measure the safety conditions in this occupation. The aim of this study was to assess the safety climate of rehabilitation nurses working in hospitals in Tehran. METHODS: This is a cross-sectional study which was carried out on 140 rehabilitation nurses selected from all hospitals and clinics in Tehran in 2019. To collect the required data, a two-section questionnaire was used. The first section was related to demographic factors and the second part (22 statements) was to measure the safety climate using nurses’ safety climate assessment questionnaire. The collected data were analyzed by SPSS V16 using independent t-test, ANOVA, Kruskal-Wallis and Mann-Whitney U test at the 5% level. RESULTS: Findings showed that the total mean of safety climate was 3.06±0.56. According to the results, a significant difference was found between the positive and negative satisfaction of nurses with safety climates (P-value = 0.03), communication with nurses (P-value = 0.01) and supervisors’ attitude (P-value = 0.02). Furthermore, a significant difference in safety climate between the individual with the second job and the individual without second could be observed (P-value = 0.01). CONCLUSIONS: The results indicated that the safety climate was not at an acceptable level. Thus, it is essential to introduce safety training courses (e.g. safety, work-rest balance, and so on) and to improve the safety performance at work.

scholarly journals Comparison of Mechanical Properties of PMMA Disks for Digitally Designed Dentures

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1745
Author(s):  
Tamaki Hada ◽  
Manabu Kanazawa ◽  
Maiko Iwaki ◽  
Awutsadaporn Katheng ◽  
Shunsuke Minakuchi
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Water Sorption ◽  
Water Solubility ◽  
Flexural Modulus ◽  
Manufacturing Method ◽  
Heat Curing ◽  
Significant Difference ◽  
Cad Cam ◽  
Curing Method

In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer’s recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials (p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

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