Effects of different powder to liquid ratios on the push out bond strength of CEM cement on simulated perforations in the furcal area

Proper bond strength to dentin is one of the properties of biomaterials used for therapeutic purposes such as repair of furcal perforations. The aim of the present study to evaluate the effects of different powder to liquid ratios of Calcium-enriched mixture (CEM) on the push-out bond strengths in simulated perforations in the furcal area and compare it with Mineral trioxide aggregate (MTA). Furcal perforations, measuring 1.3 mm in diameter and 2 mm in height, were prepared in 120 mandibular first molars. Then the samples were randomly assigned to two groups (n=60). MTA and CEM cement were used for the repair of perforations in groups 1 and 2, respectively. Each group was divided into 3 subgroups based on the powder to liquid rations as follows: subgroup 1 (W/P) , 1:2; subgroup 2, 1:3; and subgroup 3, 1:4. After mixing and placing the materials in the perforation area, the samples were placed in closed containers at 37°C and 100% relative humidity for one week. A universal testing machine was used to determine the bond strength values. After recording the standard deviations, data were analyzed with two-way ANOVA. Statistical significance was set at P<0.05. In the MTA and CEM groups the highest push-out bond strength values were recorded in the third (W/P: 1:4) and first (W/P: 1:2) subgroups, respectively. There were significant differences in both groups between the ratios mentioned above and the other ratios (P<0.05). Under the limitations of the present study, an increase in the powder-to-liquid ratio in CEM cement resulted in a decrease in bond strength, contrary to MTA

Classifying Objects in 3D Point Clouds Using Recurrent Neural Network: A GRU LSTM Hybrid Approach

Accurate classification of objects in 3D point clouds is a significant problem in several applications, such as autonomous navigation and augmented/virtual reality scenarios, which has become a research hot spot. In this paper, we presented a deep learning strategy for 3D object classification in augmented reality. The proposed approach is a combination of the GRU and LSTM. LSTM networks learn longer dependencies well, but due to the number of gates, it takes longer to train; on the other hand, GRU networks have a weaker performance than LSTM, but their training speed is much higher than GRU, which is The speed is due to its fewer gates. The proposed approach used the combination of speed and accuracy of these two networks. The proposed approach achieved an accuracy of 0.99 in the 4,499,0641 points dataset, which includes eight classes (unlabeled, man-made terrain, natural terrain, high vegetation, low vegetation, buildings, hardscape, scanning artifacts, cars). Meanwhile, the traditional machine learning approaches could achieve a maximum accuracy of 0.9489 in the best case. Keywords: Point Cloud Classification, Virtual Reality, Hybrid Model, GRULSTM, GRU, LST

LTE handover design for cellular-connected aircraft

Ubiquitous accessibility worldwide and superior performance of cellular networks of communication like 4G and 5G make them a perfect candidate for air to ground (A2G) communications for low to medium altitude aircraft systems such as unmanned aerial vehicles (UAVs) and urban air mobility (UAM). However, cellular networks are designed and optimized for terrestrial users, and employing them communication of cellular connected aerial vehicles such as electric vertical take-off and landing (eVTOL) aircraft flying at higher altitudes and faster speeds is accompanied with some issues which should be resolved prior to application. Too many handovers and following consequences such as radio link failures, longer delays, and degraded throughput are major issues in wider employment of cellular networks for A2G communications. In this paper we have considered two main issues of handover in LTE networks when used for A2G communications of cellular-connected aircraft and have proposed novel handover algorithms addressing these issues which will decrease the number of unnecessary and ping pong handovers, as well as radio link failure rate for cellular connected aircraft. The improved performance of the proposed algorithms has been verified by extensive simulations in a bespoke designed simulation model for cellular connected aircraft served by LTE networks

Investigating the effects of strategic positioning for development of modern banking services

During the past few years, there have been tremendous changes on banking services and many bank customers are able to do their daily banking activities using recent advances of technology such as internet banking, telephone banking, etc. In this paper, we present an empirical investigation on the effects of strategic positioning for development of modern banking services. The proposed study designs a questionnaire in Likert scale and distributes it among some 385 randomly selected people who live in Tehran in 2013. The questionnaire consists of seven factors including property positioning, advantage positioning, consumer positioning, user positioning, competitive advantage positioning, quality positioning and merchandise category positioning. Using Spearman correlation as well as stepwise regression technique, the study has determined positive and meaningful relationships between different components of strategy positioning development of modern banking services

Effects of Adding Non-viable Lacticaseibacillus casei and Lactobacillus acidophilus on Physicochemical, Microbial, Chemical and Sensory Attributes of Probiotic Doogh

  Background and Objective: Inactivated probiotics provide various health and technological benefits, making them appropriate for the production of functional dairy products. The aim of this study was to investigate effects of adding nonviable probiotics (Lactobacillus acidophilus LA-5 and Lacticaseibacillus casei 431) to doogh (a typical Iranian fermented milk drink). Material and Methods: Probiotics were inactivated by heat or sonication and added to the samples before or after fermentation. Various parameters such as pH, titratable acidity, redox potential, antioxidant capacity, color, viscosity, and phase separation, viability of traditional starter bacteria and probiotics and sensory characteristics were assessed during fermentation and refrigerated storage at 5 °C. Results and Conclusion: Sonicated probiotic-containing treatments included the highest pH decrease rate (0.011 pH min-1) during fermentation, as well as the highest antioxidant capacity (16.45%) and viscosity (35.15 mPa.s), while heat-inactivated probiotic- containing treatments included the lowest viscosity (17.60 mPa.s). Treatments with viable probiotics reasonably included the highest post-acidification rate during storage (4.14 °D d-1), compared to those containing nonviable cells, as well as the minimum phase separation rate. The b* and L* values of color did not differ significantly within treatments, but the highest a* value was observed in the treatments with sonication. The highest populations of Lactobacillus delbrueckii ssp. bulgaricus (log 11,891 cfu ml-1) and Streptococcus thermophilus (log 14,977 cfu ml-1) at the end of the storage were observed in treatments with heated probiotics (compared to viable probiotics) and treatments with sonicated probiotics, respectively. In addition, Lactobacillus acidophilus was more susceptible than Lacticaseibacillus case and included lower viability. Taste, mouth feeling and total acceptance of all samples did not differ significantly within treatments. The present study suggests that inactivated probiotics can successfully be used for the production of fermented milk beverages with appropriate sensory characteristics and higher antioxidant capacity, compared to the control group. Conflict of interest: The authors declare no conflict of interest.   Introduction   Recently, it has been suggested that probiotics, viable or non-viable, are bacterial cells that include positive effects on human health. By this general definition, probiotics are divided into two categories of viable and non-viable probiotics [1, 2]. The idea of using non-viable probiotics in food industries is originated from the fact that probiotic bacteria are susceptible to environmental conditions during passage through the gastrointestinal tract (GIT), include limited stability over a wide range of pH and temperature, include a shorter shelf-life and need refrigerated storage. Therefore, their use in various industries is further technologically and economically feasible [3-6]. Additionally, it has been verified that non-viable probiotics include beneficial effects for humans such as immunostimulating activity [7], cholesterol decrease [8], anticancer characteristics [9], healing gastrointestinal disorders [10] and suppression of pro-inflammatory cytokine production [11]. There are several available methods to inactivate probiotics, including heat treatment, ultraviolet (UV) irradiation, irradiation, sonication (ultrasound), high pressure, ionizing radiation, pulsed electric field (PEF), supercritical CO2, drying and changes in pH [8,12]. Sonication and heating are the most commonly used methods for inactivating probiotics, majorly because they are cost-effective and time-efficient. Ultrasound at frequencies of 20–40 kHz can be lethal to microorganisms by creating acoustic cavities on their cell membrane (CM), leading to the release of their contents [13]. In contrast, during heating, intracellular contents are not released. Doogh is a fermented beverage whose major ingredients include yogurt, water, salt and flavoring agents [14]. However, studies on adding non-viable probiotics to fermented foods are limited. Parvayi et al. studied effects of inactivated Lactobacillus acidophilus ATCC SD 5221 and Bifidobacterium lactis BB-12 on yogurt characteristics and reported that incorporation of heat-inactivated probiotics to yogurts included less technological challenges and could be deliberated as an appropriate alternative for probiotics in functional yogurts [15]. Overall, there is still a research gap in the development and commercialization of inactivated probiotic dairy products in food industries. While interests in probiotics and prebiotics are increasing, inactivated probiotics have not received much attention for product development and market availability. In addition, knowledge on specific inactivated probiotic compounds in dairy products and their potential effects on human health is limited. Further research are needed to identify and characterize these compounds and assess their potential health benefits and uses in functional foods [16,17]. Moreover, there is a lack of standardized methods for the production and quality control of inactivated probiotic dairy products, which limits their widespread commercialization. Research in this area is essential to establish industry standards and guidelines for the production and commercialization of inactivated probiotic dairy products. The aim of this study was to assess effects of adding non-viable forms of Lacticaseibacillus casei 431 and lactobacillus acidophilus LA-5 probiotics inactivated by heating or sonication on the quality characteristics of doogh, a traditional fermented milk beverage from Iran. Probiotics were added before or after the milk fermentation processes. Materials and Methods Materials Skim milk powder was purchased from Pegah, Tehran, Iran. Starter culture included Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus (YF-3331) and the probiotics (Lacticaseibacillus casei 431 and Lactobacillus acidophilus LA-5) were provided by Chr. Hansen, Copenhagen, Denmark. De Man-Rogosa-Sharpe (MRS) agar and M17 agar were purchased from Quelab, Montreal, Canada, and salt from a local market. Preparation of nonviable probiotics Probiotic suspension was subjected to thermal inactivation by heating at 121 °C for 15 min [18]. To achieve ultrasound inactivation, probiotic suspension was exposed to ultrasound waves at a frequency of 250 kHz for 25 min [19]. Preparation of doogh To prepare doogh, skim milk powder was reconstituted and diluted to a total solid content of 3.5%. Mixture was heated to 90 °C and set for 15 min before cooling down to 45 °C. Probiotics in viable or nonviable form were added before heat treatment (B) or after fermentation (A). Mixture was incubated at 42 °C until the pH reached 4.5, cooled down to 5 °C and stored in refrigerator for 28 d, as presented in Fig. 1. Assessment of pH, redox potential and titratable acidity The pH, RP (redox potential) and titratable acidity of the doogh samples were checked every 30 min during fermentation. After fermentation, doogh samples were cooled and stored in refrigerator for 28 d, during which, pH, RP (redox potential) and titratable acidity were assessed every 7 d to monitor the shelf life. The pH and RP were assessed using pH meter at room temperature (RM). Titratable acidity was assessed by titrating with 0.1 M NaOH solution and 0.5% phenolphthalein indicator [20]. Increase in acidity, decrease in pH value (pH value min-1) and increase in redox potential (mV min-1) were calculated using Eqs. 1, 2 and 3: Figure 1. Study design of the present study.   Serum separation analysis After cooling down, samples were stored in 10 ml vials and incubated at 5 ºC to assess serum separation. During the shelf-life period, height of the supernatant was assessed every 7 d to assess degrees of serum separation that were expressed as proportions using the following Eq. 4 [21]:                   Eq. 4 Rheological assessment Rheological assessments were carried out using Brookfield viscometer at refrigerator temperature, one day after the samples were prepared [22]. Briefly, no. 2 cylindrical spindle and spindle speeds of 0.3, 0.6, 1.5, 3, 6, 12, 30 and 60 rpm were used during 90 s if the torque to rotate the spindle in the samples was between the 15.0 and 85.0% of the maximum torque. Assessment of antioxidant capacity To assess antioxidant capacity of the samples, a method was used based on the ability of antioxidants to scavenge the stable radical DPPH (1,1-diphenyl2-picrylhydrazyl). This method was described by Farahmandfar et al. essentially, sample ability to reduce the concentration of DPPH was assessed by measuring absorbance of the solution before and after exposure to the samples [23]. Antioxidant capacity of all samples and inactivated bacterial suspension were assessed on two occasions. The first assessment was carried out on the day of production, while the second assessment was carried out on Day 28 of the shelf-life.        Eq. 5 Color assessment Color characteristics of doogh were assessed using Hunter Lab Color Flex EZ explained by Milovanovic et al. [24]. Color parameters were L* (brightness, white = 100, black = 0), a* (+, red; -, green) and b* (+, yellow; -, blue). Bacterial enumeration Pour plate method was used to count numbers of L. delbrueckii subsp. bulgaricus, S. thermophilus and L. casei [25]. The L. bulgaricus, starter bacteria of doogh, was cultured in MRS-bile agar at 42 ºC for 72 h under anaerobic conditions using Gas Pac system. Enumeration of S. thermophilus was carried out using M17 agar at 37 ºC for 24 h under aerobic conditions [26]. Lactobacillus acidophilus LA-5 and L casei were cultured in MRS agar with added bile (0.15% w w-1) to prepare selective media of probiotic enumeration at 37 ºC for 72 h under aerobic conditions [27, 28]. The initial counts of L. acidophilus and L. casei were 107 CFU ml-1. To calculate the viability proportion index, final cell population of the microorganisms was divided into the initial cell population based on the Eq. 6 [25].                                                            Eq. 6 Sensory evaluation Taste, mouth feel and overall acceptance of doogh were assessed using 5-point hedonic scale rating test (with 5 excellent, 4 good, 3 acceptable, 2 bad and 1 very bad) [29]. Twenty consumers assessed the sensory attributes of doogh samples after the first day of preparation. Statistical analysis All experiments were carried out in triplicate and expressed as mean ±SD (standard deviation) (n = 3). Data were analyzed using univariate analysis of variance (Tukey test) AND SPSS statistical software v.26 (SPSS, Chicago, USA). Generally, p &lt; 0.05 was addressed as the significance threshold. Results and Discussion Assessments of pH, redox potential and titratable acidity During milk fermentation, growth of starter bacteria leads to the conversion of lactose into various compounds such as lactic acid, acetate, formate, acetaldehyde and ethanol. This process results in lactic acid production, causing decreases in pH and increases in redox potential and titratable acidity [30]. Figure 2 illustrates changes in pH, redox potential and titratable acidity during the fermentation process. The initial pH of milk at the beginning of fermentation was 6.8, dropping to 4.5 by the end of fermentation. As shown in Fig. 2, and Table 1 fermentation process included three distinct phases of lag, log and constant phases. During the first 30 min, the lag phase, no significant changes were seen, possibly due to the adaptation of the starter bacteria and buffering characteristics of milk [31]. The fastest decrease in pH and increase in redox potential were observed in sample with ultrasound-inactived L. casei. This might be attributed to the ultrasound treatment, which caused puncturing of the membrane of the probiotics, resulting in the release of their cell contents into doogh [5,13]. Feeding the starter bacteria resulted in decreases in the rate of pH and pH of BUC reached 4.5 as the fastest rate (after 210 min). However, BUA included the highest titratable acidity, indicating that the type of probiotic bacteria included major effects on the rate of pH drop and acidity increase. Similarly, Tian and colleagues (2017) reported that the type of bacteria included effects on the quantification of organic acids [32]. In addition, postbiotics produced from L. acidophilus LA-5, L. casei 431 and L. salivarius included 62 vrious components, including alcohols, terpenes, norisoprenoids, acids, ketones and esters [33]. Hence, these compounds were available in the environment and might improve the fermentation stage. Based on Fig. 2, BHC included similar rates of pH decrease and increase in redox potential through the fermentation process as the sample without probiotics. However, BHA showed the lowest rate of acid increase at the end of the fermentation, indicating that the starter bacteria alone were responsible for lactic acid production and the intact cells of the probiotic bacteria included no significant effects on acid production. Furthermore, heat-inactivated L acidophilus demonstrated the antibacterial activity [34]. Samples containing live probiotics needed longer times (240 min) to reach pH 4.5. This finding was similar to the finding of Parvayi (2021), who reported that live probiotic samples needed longer times to reach pH 4.5, compared to paraprobiotic samples [15]. Based on a study by Vinderola et al. (2002), adding L. casei and L. acidophilus to the media with the starter bacteria included negative effects on the growth of the starter bacteria, resulting in decreases in lactic acid production [35]. Statistical analysis showed no significant differences in redox potential between various types of bacteria (p&gt;0.05). However, L. acidophilus resulted in further decreases in pH and increases in titratable acidity during the storage, compared to that L. casei did (p&lt;0.05) as represented in Table 2. These results suggested that the selection of probiotic bacteria should carefully be considered based on the specific goals of the fermentation process [36]. Throughout the storage, the highest level of titratable acidity was seen in sample containing live probiotics of L. acidophilus (181AD∘), which could be attributed to the ongoing acid production by the live probiotics at the refrigerated storage. In contrast, BUC sample included the lowest acidity (117A∘), suggesting that the addition of probiotics after the fermentation process could lead to uncontrolled increases in acidity and continued fermentation during cold storage [15]. Moreover, samples containing sonicated and live probiotics included the maximum and the minimum RP increasing rates because of producing the minimum and the maximum lactic acid quantities during storage (p&lt;0.05). Serum separation The study detected that the activity of starter bacteria and their ability to generate acids included significant effects on the separation of serum in the samples [37]. Data of Table 3 show increases in serum separation values for all samples during the storage. The initial and the final separation rates of BUC were the highest (32.4%), suggesting that the released intracellular contents were heavier than the whole bacterial cells, causing further sedimentations. In addition, Samples containing live probiotics included smaller serum separation ratios at the end of storage, indicating that they frequently produced lactic acid and their pH was further different from the isoelectric pH [38]. Relatively, Amani et al. reported effects of the activity of starters during storage due to their protein hydrolyzing characteristics on phase separation [37]. In addition, L. casei was reported to include lower serum separation ratios than that L. acidophilus did (p&lt;0.05). This suggested that the type of bacteria in the samples played important roles in the serum separation rate because various strains of probiotic bacteria included various abilities to ferment and break down organic compounds and producing exo-endo polysaccharides as discussed in viscosity section [39]. However, np statistically significant differences were detected between the sequences of probiotic additions (p&gt; 0.05). Viscosity Naturally, acidification and lowering of pH during fermentation cause milk casein proteins to clump, affecting viscosity of the final products. Figure 3 shows assessed viscosity of the samples. Sonicated probiotic-containing treatments (BUC and BUA) included the highest viscosity (3.083 ±0.6 and 3.515 ±0.5, respectively). Additionally, addition of live probiotics during fermentation led to increased viscosity, compared to samples without probiotics. It was reported that the release of exopolysaccharides and intracellular polysaccharides from the probiotics significantly increased viscosity [40, 41]. Exopolysaccharides secreted by Lactobacillus spp. during their growth affect viscosity of dairy products [42]. Moreover, "intracellular polysaccharides" are polysaccharides that accumulate within cells. The intracellular biosynthetic process involves transferring sugar residues into the cell, converting them into various monomeric units, partially polymerizing them and attaching them to isoprenoid lipid carriers [43]. Viscosity of heat-inactivated treatments was similar to that of control treatment, possibly because intact cells of probiotic bacteria did not release biopolysaccharides into doogh samples. Furthermore, type of bacteria significantly affected the viscosity (p&lt;0.05). It was previously reported that variations in the viscosity values could be affected by characteristics of the probiotics cultures as well as adaptability of the bacteria [44]. Antioxidant activity assessment The DPPH radical scavenging method, widely used to assess antioxidant activities, is simple, rapid, sensitive and reproducible compared to other methods [45]. Figure 4 shows antioxidant capacities of the samples on Days 1 and 28. Antioxidant capacity of the samples decreased significantly during the storage due to inappropriate sealing, oxygen entry into the samples and uncontrolled bacterial activity. Sonicated probiotic-containing treatments increased the antioxidant capacity, as the intracellular content of lactic acid bacteria (LAB) demonstrated greater antioxidant characteristics than that the whole cell or the extracellular metabolites did [46,47]. Antioxidant activity of the intracellular contents of LAB was linked to the activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), nicotinamide adeninedinucleotide (NADH)-oxidase, NADH-peroxide and glutathione (GSH) enzymes [48]. In addition, use of live or heat-inactivated probiotics did not result in significant differences (p&gt;0.05). This was due to the cell contents that were not released. Relatively, lyophilized cells of Lactococcus lactis subsp. cremorishave included the highest antioxidant capacity, compared to those the heat-killed and intact cells did [49]. In contrast, use of L. acidophilus rather than L. casei significantly increased the antioxidant capacity (p&lt;0.01). Amdekar et al. assessed antioxidant and anti-inflammatory potentials of L. casei and L. acidophilus in in-vitro models of arthritis. Results indicated that arthritic rats treated with L. acidophilus included higher glutathione peroxidase and decreased glutathione concentration, compared to that arthritic rats treated with L. casei did [50]. Additionally, adding probiotics before fermentation improved the antioxidant capacity of doogh samples (p&gt;0.05). Color analysis   Color is a critical characteristic in assessing quality of products such as yogurts and doughs. The L* parameter indicates lightness or darkness of the color, the a* parameter shows redness or greenness of the color and the b* parameter represents yellow or blueness of the color [51]. The color values are shown in Fig. 5. Integration of probiotics inactivated using ultrasound resulted in increases in a* value, indicating release of probiotic contents into the doogh sample (p&lt;0.05) and showing that green pigment substances such as thiamine were present in intracellular probiotics [52]. However, no significant differences were reported between the paraprobiotics and probiotics in a* value (p&gt;0.05). Additionally, no significant differences were demonstrated between the sequential additions of probiotics in a* value (p &gt; 0.05). Type of the probiotics in doogh samples included significant effects on a* value (p &lt; 0.05). It has previously been suggested that various types of bacteria with special characteristics can affect color of the products [53]. In L* and b* values, no differences were observed within the addition of active/inactivated probiotics into doogh samples (p&gt;0.05). Furthermore, types of probiotic bacteria (L. casei or L. acidophilus) and probiotic adding sequences did not include significant effects on L* and b* values (p &gt; 0.05). Viable counts of the starter bacteria and probiotics The L. bulgaricus and S. thermophilus are critical for acidification and production of doogh [54]. Survival of the starter and probiotic bacteria in yogurts depends on various factors such as the specific strains, interactions between the species, chemical compositions of the yogurts, the culture conditions, production of hydrogen peroxide during bacterial metabolism, final acidity of the yogurts, rates of lactic and acetic acids, nutrient availability and the storage temperature [46]. Table 4 shows the number of L. delbrueckii subsp. bulgaricus and S. thermophilus for all samples during the st

Global, regional, and national burden of colorectal cancer and its risk factors, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Funding: F Carvalho and E Fernandes acknowledge support from Fundação para a Ciência e a Tecnologia, I.P. (FCT), in the scope of the project UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences UCIBIO and the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy i4HB; FCT/MCTES through the project UIDB/50006/2020. J Conde acknowledges the European Research Council Starting Grant (ERC-StG-2019-848325). V M Costa acknowledges the grant SFRH/BHD/110001/2015, received by Portuguese national funds through Fundação para a Ciência e Tecnologia (FCT), IP, under the Norma Transitória DL57/2016/CP1334/CT0006.proofepub_ahead_of_prin

An agent-based supply chain model for strategic analysis in forestry

An agent-based forest sector model, CAMBIUM 2.0, is developed and applied to case studies of the forest industry in the coastal British Columbia (BC). By combining optimization and simulation, this model allows policy makers and managers to examine the impact of different supply chain (SC) configurations (e.g. establishing new facilities), and changing forest management policies (e.g. harvest restrictions). The forest sector structure and the state of the forest resources that develop over time are a result of autonomous agents interacting with each other while competing for available forest resources needed to manufacture forest products. The thesis is presented in four chapters. In chapter 1, I introduce SC modelling concepts and techniques and identify research objectives and methods. Chapter 2 presents and discusses the structure of the agent-based simulation model and the formulation of the facility location problem, presenting a novel algorithm for integrating the optimization problem with the simulation model. The model is applied to the case of a forest industry SC to establish a new agent. The predictions of the new agent about its profits are not strongly affected by higher levels of information about the cost structure of its competitors, while improving the accuracy of market predictions has a noticeable impact on such predictions. Chapter 3 evaluates the impact of establishing a log sort yard on the profitability of the forest products SC. Considering different market price scenarios, establishing a sort yard does not seem to benefit the forest products SC, mainly because of intense competition for timber. In Chapter 4, CAMBIUM 2.0 is used to investigate the impact of harvest policy changes on the SC performance and the timber supply sustainability. Alternative harvest priorities (e.g. harvesting stands with highest value first) and modifying the harvesting preference of the mills (i.e. harvesting a mix of high and low value stands) improves the timber supply sustainability with less negative economic impacts compared to lowering the harvest limit. The modelling framework developed in my research can be extended to address other research questions such as changing log export policies, setting stumpage prices, or encouraging replanting of economically desirable species.Forestry, Faculty ofGraduat

Efficiency and productivity measurement of the Canadian manufacturing sector : 1994-2002

Performance assessment has been gaining increasing attention in different sectors, including the manufacturing industries. The need for assessing the performance of firms has increased as a result of growing competition and globalization. Information technology advances along with changes in political and economic conditions have promoted industrial globalization. While a global marketplace means more customers, at the same time, companies face intense competition when they produce and sell their products globally. Companies need to learn about foreign societies and understand foreign customers; they also need to have long term plans on how to remain competitive. Evaluating and monitoring the performance and increasing productivity and efficiency are important issues for competitive companies and their investors. The Canadian manufacturing industries, which are important building blocks of our economy, face similar challenges since they are mainly export oriented. New countries, such as China or other South East Asian countries are currently exporting their manufactured products globally. These emerging exporters have greatly increased their market share in recent years, mainly because they have access to cheap resources and can offer their products with lower prices compared to other industrialized countries. This has created a major challenge for Canadian manufacturers. In Canada, forest industries contribute greatly to the economy by contributing to the country's trade surplus and by creating jobs in rural areas. Wood products manufacturing is the second largest forest sector in Canada and is also classified under the manufacturing sector. The same issues faced by other manufacturing industries apply to wood industry as well. Considering the importance of manufacturing sector and the wood industry in particular, it would be useful to study their performance over time. Therefore, the intent of this research was to evaluate the performance of the manufacturing sector in Canada and in the United States, Canada's major trading partner. Productivity growth of the industries was studied separately for each country, using a non-parametric productivity measure, Malmquist Productivity Index. The results showed that both countries had an overall growth in Total Factor Productivity (TFP) during the study period. However, their growth was mainly due to the technological progress (frontier shift) rather than the efficiency improvements. In both countries, TFP of the wood products manufacturing was below the average for the sector and technical efficiency decreased over the study period. In order to obtain a complete understanding of the wood products manufacturing sector's performance, the efficiency changes of its sub-sectors were studied. These subsectors were sawmilling and wood preservation, veneer, plywood, and engineered wood products, and other wood products manufacturing. Data Envelopment Analysis, a nonparametric efficiency measurement method, was utilized for the analysis. Sawmilling and wood preservation showed the highest efficiency, on average, during the study period, while other wood products manufacturing was identified with the lowest efficiency. The results of the study suggest that wood products manufacturing needs to direct its strategies mainly towards improving the technical efficiency of the whole industry as well as its sub-sectors. This includes better managerial knowledge, labour training, and investment in machinery and equipment among other things. The wood industry can follow examples of the best practices in the manufacturing sector and identify improvement possibilities for its performance.Forestry, Faculty ofGraduat

Optimization of Coagulation-Flocculation Process in Efficient Arsenic Removal from Highly Contaminated Groundwater by Response Surface Methodology

Elevated arsenic (As) contamination in water, especially groundwater, has been recognized as a major problem of catastrophic proportions. This work explores As(V) removal via the coagulation-flocculation process by use of ferric chloride coagulant and polyacrylamide k16 co-coagulant as a first time. The effects of major operating variables such as coagulant dosing (50, 125 and 200 mg/L), co-coagulant dosing (5, 12.5 and 20 mg/L), pH (6, 7and 8), fast mixing time (1, 2 and 3 min), and fast mixing speed (110, 200 and 300 rpm) on As(V) removal efficiency were investigated by a Box-Behnken statistical experiment design (BBD) and response surface methodology (RSM). According to factors F values, coagulant dosing, rapid mixing speed, pH, and co-coagulant dosing showed the most effect on As(V) removal efficiency, and the rapid mixing time factor indicated the slightest effect. The proposed quadratic model was significant with a p value R2 and adjusted R2 values of 0.9855 and 0.9738, respectively. Predicted model optimal conditions with target of complete As(V) removal were coagulant dosing = 197.63 ppm, co-coagulant dosing = 19.55 ppm, pH = 7.37, fast mixing time = 1.43 min and fast mixing speed = 286.77 rpm. The treatment of Nazarabad well water sample with an initial As(V) concentration of 5 mg/L under the optimal conditions removed 100% As(V) with the volume of produced sludge of 10.7 mL/200 mL. Increasing coagulant dosing, co-coagulant dosing, fast mixing time and fast mixing speed operation parameters from low-level to high-level values indicated 78%, 20%, 10.52% and 9.47% increases in volume of the produced sludge, respectively. However, a reduction of 13.63% in volume of the produced sludge resulted via pH increases

Comparison of recurrent rate of gingival pigmentation after treatment by liquid nitrogen and cryoprob in 18 months follows-up

Background: Cryosurgery is one of the simplest, most effective gingival depigmentation methods. Repigmentation may happen after a while in each method. The aim of this study is to compare the recurrence rate after treatment by liquid nitrogen swap and a cryoprob in 18 months. Materials and Methods: A total of 26 patients with physiologic gingival pigmentation were selected. The anterior sextant was divided into left and right segments; each segment was treated randomly by swap technique or cryoprob. Standard photos were evaluated with photoshop software (Red, Green, Blue, Cyan, Magenta, Yellow, Black [RGB, CMYK]) before and at 2 week, 1, 3, 6, 9, 12, 15, 18 months after the treatment. The results were compared, by the independent t-test and repeated measure ANOVA thereafter least significant difference post-hoc. The viewpoints of patients and physicians regarding the treatment outcomes were obtained by a questionnaire and consequently evaluated qualitatively by McNemar test (P < 0.05 was considered as significant level). Results: The statistical analysis showed a significant difference in color change after the treatment during 18 months, in each group (P 0.05). The mean values of CMYK significantly decreased after 2 weeks in both methods (P 0.05). Qualitative evaluation showed the preference of the cryosurgery with swap method (P < 0.001). No significant recurrence was observed during 18 months follow-up. Conclusion: Both methods of cryosurgery are appropriate in treatment of gingival depigmentation because no significant recurrence was observed during 18 months follow-up