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Journal articles on the topic "UL 3000"

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Sampogna, Francesca, Marina Frontani, Giannandrea Baliva, Damiano Abeni, Giuseppe A. Lombardo, Alessandro Monopoli, Claudio Barbieri, et al. "Characteristics and Survival of 29 Patients with Sezary Syndrome." Blood 106, no. 11 (November 16, 2005): 5587. http://dx.doi.org/10.1182/blood.v106.11.5587.5587.

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Abstract We created a relational database of patients with cutaneous T-cell lymphoma (CTCL) to collect in a standardised fashion, anagraphic variables, clinical history, clinical, histological, haematological, and immunological information on CTCL patients hospitalised at IDI-IRCCS, Rome, Italy. At present, there are data on 424 patients, hospitalised from 1983 to July 2005. Active follow-up is performed yearly to ensure a standardised ascertainment of survival time. For deceased patients, the actual date of death (for all causes) is recorded, while surviving patients are censored at the date of last contact. The database includes 29 patients with Sezary syndrome (SS). Follow-up times ranged from 0 to 105 months. At first hospitalisation the median values of cells/mL were: white blood cells (WBC) 8750, neutrophils 4250, eosinophils 140, basophils 120, lymphocytes 2760, monocytes 500, CD3+ 2780, CD4+ 2431, CD8+ 192, CD19+ 96. Seventeen patients were deceased. We included in the Kaplan-Meier survival analysis only patients who were diagnosed before July 2004 (n=26). Median survival time from diagnosis was 52 months. No significant differences were observed in mortality for WBC (cutoff 9000 cells/uL), neutrophils (cutoff 4500 cells/uL), basophils (cutoff 200 cells/uL), lymphocytes (cutoff 3000 cells/uL), monocytes (cutoff 500 cells/uL), CD3+ (cutoff 2000 cells/uL), CD4+ (cutoff 2000 cells/uL), CD8+ (cutoff 200 cells/uL), CD19+ (cutoff 70 cells/uL). A lower survival was observed for patients with eosinophils <200 cells/uL (p=.08). Survival in patients with SS does not seem to be influenced by haemathologic parameters. However, patients with long-term survival (>90 months) are observed, and their characteristics should be further investigated. Survival analysis of 26 patients with Sézary syndrome, Rome, Italy, 1991–2004. Survival analysis of 26 patients with Sézary syndrome, Rome, Italy, 1991–2004.
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Ding, Haoxuan, Jianan Han, and Jie Feng. "PSII-38 Tolerable upper intake levels of iron damage the intestine and alter the intestinal flora in weaned piglets." Journal of Animal Science 98, Supplement_4 (November 3, 2020): 381. http://dx.doi.org/10.1093/jas/skaa278.670.

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Abstract Iron supplementation has been an intervention to improve iron storage and prevent iron deficiency anaemia in weaned piglets. NRC has set recommended nutrient intake (RNI) and tolerable upper intake levels (UL). The purpose of this study was to investigate the potential harm of UL iron to the gut and microbes of weaned piglets. Thirty 23-day old weaned piglets assigned to three dietary treatments: a basal diet supplemented with 100 (RNI), 300, or 3000 (UL) mg FeSO4/kg diet for 28 days. Piglets were then euthanized, and the gut and cecum microbes were collected. UL iron significantly reduced the height of the villi in the duodenum, ileum, and jejunum of weaned piglets, and showed duodenal mitochondrial swelling (P < 0.05). The addition of UL iron to the diet significantly reduced the expression of tight junction proteins Claudin-1, Occludin, and ZO-1 in weaned piglet duodenal mucosa (P < 0.05). The protein levels of DMT1 and Zip14 decreased (P < 0.05), and the protein levels of ferritin increased in the duodenal mucosa of UL iron fed weaned piglets (P < 0.05). Moreover, UL iron also increased the content of ROS and MDA and decreased the activity of SOD in the weaned piglet duodenal mucosa (P < 0.05). Additionally, UL iron significantly increased intestinal microbial diversity and species richness in weaned piglets. At the phylum level, UL iron supplementation was associated with a significant increase in Proteobacteria relative abundance, and significantly decreased the relative abundance of Firmicutes (P < 0.05). At the genus level, the relative abundance of Clostridiales, Faecalibacterium, and Prevotellaceae decreased significantly (P < 0.05), while the relative abundance of Desulfovibrio and Anaerovibrio increased significantly (P < 0.05). In conclusion, UL iron caused damage to the intestinal villi, damaged the intestinal barrier, reduced iron absorption, induced oxidative stress, led to histopathological changes, and modified the intestinal microbial structure in weaned piglets.
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Norsiah, Wahdah. "Perbedaan Kadar Hemoglobin Metode Sianmethemoglobin dengan dan Tanpa Sentrifugasi pada Sampel Leukositosis." Medical Laboratory Technology Journal 1, no. 2 (December 1, 2015): 72. http://dx.doi.org/10.31964/mltj.v1i2.19.

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Examination of hemoglobin levels influenced leukocytosis sianmethemoglobin method that causes increased absorbance measurements of hemoglobin levels increased significantly and the false blood sample that has been diluted with a solution Drabkins in centrifugation at 3000 rpm for 10 minutes and then the absorbance of the supernatant was measured with a photometer at λ 546 nm. This study aimed to analyze the differences in hemoglobin level examination siamethemoglobin method with and without centrifugation at sample leukocytosis. This type of research is observational research laboratory. The study design was cross-sectional study. Samples were taken from the remaining blood samples of patients who have been examined leukositnya number more than 20,000 / uL with Hematology Analyzer (CEL-DYN Ruby) February-April 2014, and were divided into 4 groups based on criteria that group 1. leukocyte count of 20,000 / uL-29 999 / mL, group II. 30,000 / uL-39 999 / uL, the group III. 40,000 / uL-49,999 / uL, the group IV. More than 50,000 / uL. The number of samples taken were 20 samples of each group, a total sample of 80 samples. The analysis showed no significant difference in hemoglobin levels siamethemoglobin method with and without centrifugation at sample leukocytosis with a value of p = 0.000 less than 0.05 α. Leukocytosis Turbidity affects the difference in hemoglobin levels with and without centrifugation, the higher the number the greater the difference in leukocyte levels of hemoglobin, hemoglobin level examination results of the study based on the criteria of the number of leukocytes obtained by the difference in hemoglobin levels with and without centrifugation in group I. 0.22 ± 0.07 g / dL, group II 0.40 ± 0.22 g / dL, a group III. 0.44 ± 0.14 g / dL, Group IV. 0.85 ± 0.41 g / dL. The level of hemoglobin in the sample sianmethemoglobin method leukocytosis with more than 20,000 / uL need a centrifuge so that appropriate hemoglobin levels over the patient's clinical condition.
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Chacin Zambrano, Christian Andrei, Yessica Paola Quintero Avila, Leydy Gabriela Rodríguez González, and Johanna Alexandra Gómez Santos. "Evaluation of the in vitro growth of perolera pineapple (Ananas comosus) explants using organogenesis technique." Revista Colombiana de Investigaciones Agroindustriales 7, no. 2 (February 28, 2021): 32–39. http://dx.doi.org/10.23850/24220582.3271.

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From an economic standpoint, pineapple (Ananas comosus) is one of the most important fruits in Colombia. A decade ago, the Perolera variety was the most cropped cultivar of the Santander department, however, the variety has been displaced considerably due to the lack of technical extension services and theintroduction of new varieties. This research project was carried out with the intention to conserve the speciesthrough the development of in vitro pineapple explants using the organogenesis technique. Meristemsthat have been extracted from the crown of the Perolera pineapple variety were used for this purpose. Four disinfectant treatments were evaluated by looking at the different kinds of disinfectant exposure times.The treatment that gave the best results in terms of contaminant-free explants was the T2: Commercialdetergent + Tween 80 for 8 minutes, ethyl alcohol at 70% for 1 minute and sodium hypochlorite at 1,5% over10 minutes, with a contamination rate of 7% and 93% of the explants thriving. For the establishment phase,it was found that the medium MS MEP1 with 100% solid salts supplemented with 2000 ul/L BAP - 1000 ul/L ANA - 1000 ul/L AIA and 500 ul/L thiamine enabled 90 % of the pineapple explants to continue developing four weeks after planting. Similarly, the medium containing 3000 ul/L of BAP for the multiplication phase permitted an average proliferation of 4.62 shoots with 9.12 leaves per shoot and a length of 2.25 mm.
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Nguyen, Tuan Anh, Thi Mai Huong Pham, Thi Huong Dang, Thi Hanh Do, and Quang Tung Nguyen. "Study on Mechanical Properties and Fire Resistance of Epoxy Nanocomposite Reinforced with Environmentally Friendly Additive: Nanoclay I.30E." Journal of Chemistry 2020 (April 30, 2020): 1–13. http://dx.doi.org/10.1155/2020/3460645.

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The main purpose of this study is to complete the research process of dispersing nanoclay I.30E (montmorillonite) into epoxy Epikote 240 by mechanical method combined with energy-saving ultrasonic method. We investigate appropriate dispersion conditions such as stirring speed, mechanical stirring temperature, ultrasonic stirring time, and ultrasonic stirring capacity, which affect the mechanical properties and fire resistance of nanocomposite materials. The nanoclay contents studied were 1, 2, 3, and 4% by weight, and the methods used in this study are FE-SEM; XRD; and flame-retardant evaluation methods: LOI, UL 94HB. The mechanical properties were studied: tensile strength, flexural strength, compression strength, and impact resistance Izod. The dispersion method was recommended to stir mechanically at a speed of 3000 rpm at 80°C for 8 hours and then conduct ultrasonic vibrations for 6 hours at 65°C. The results showed that epoxy Epikote 240/nanoclay I.30E nanocomposite material had mechanical properties and improved fire retardancy with a small amount of nanoclay I.30E added (2% by weight): tensile strength of 63.5 MPa (increased by 13.59%), flexural strength of 116.80 MPa (increased by 34.63%), compressive strength of 179.67 MPa (increased by 15.11%), impact resistance Izod of 12.81 KJ/m2 (increased by 80.16%), oxygen limit of 23.7%, and combustion rate of 24.5 mm/min; according to UL 94HB, the combustion rate reached 22.59 mm/min.
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Takeshita, Masataka, Risen Hirai, Akira Tanimura, Miki Nakamura, Shotaro Hagiwara, and Akiyoshi Miwa. "Application of Hematopoietic Progenitor Cell Count: To Optimize Peripheral Blood Stem Cell Harvest." Blood 124, no. 21 (December 6, 2014): 5837. http://dx.doi.org/10.1182/blood.v124.21.5837.5837.

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Abstract background. High dose therapy and autogenic or allogeneic stem cell transplantation plays an important role in the treatment course of hematological malignancies. In some countries, major method of unrelated stem cell donation programs had shifted from bone marrow harvest (BM) to peripheral blood stem cell harvest (PBSCH). PBSCH is a heavy duty not only for donor or patient, also for medical staffs. In some cases, poor mobilization may cause poor collection of stem cells. Hemogram needs time for May-Giemsa stain, and CD34 count needs complicated technique and running cost. New simple tool to predict the count of mobilized stem cell is needed to optimize PBSCH. methods. Since 2009, we started measuring peripheral blood hematopoietic progenitor cell (HPC) with Sysmex XE-5000(R) blood cell counter. With IMI channel method, we could rapidly know the count of circulating stem cells. Daily HPC count and yielded CD 34 positive cell count were analyzed. results. 189 samples were collected from 122 donors/patients. Diagnosis of patients: malignant lymphoma (n=29), leukemia (3), multiple myeloma (74), amyloidosis (5), cryoglobulinemia (1). 10 healthy donors were also included. Age: 18-66, Sex: male 82/female 40. Mobilization regimen: G-CSF 57, chemo+G-CSF 74, G-CSF+plerixafor 1 HPC count (cells/ul) and collected CD34 positive cells (106cells/kg) had positive correlation. When HPC count was above 25/ul, collected CD34 positive cells were above 1x106/kg (positive predictive value: 80.9%). Number of PBSCH operation was 1.59 in average. We also show three cases in which HPC count was useful to make clinical decision of initiating PBSCH. discussion. HPC and CD34 had positive correlation, and HPC >25/ul seems to be appropriate cut-off to start PBSCH. With our former threshold of PBSCH (G-CSF day>4, WBC >3000/ul), 241 operations were to be planned. Including HPC count, we could reduce PBSCH operation to 204. Hematopoietic progenitor cell count is rapid and inexpensive method. Within 5 minutes, mobilized stem cells can be measured, and it may be also useful in outpatient-based harvest settings. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.
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Faso, L., E. Rappa, G. Vernon, and R. Witkus. "Site of hemocyanin synthesis in the terrestrial isopod, Armadillidiom vulgare." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 970–71. http://dx.doi.org/10.1017/s0424820100156833.

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Although hemocyanin, an oxygen binding protein, is found freely dissolved in the hemolymph of isopods its site of synthesis is still unknown.Circulating blood cel Is such as granular hemocytes have been implicated in hemocyanin synthesis in a number of arthropods including Astacus astacus and Homarus vulgaris. Circulating blood cells of Armadillidium vulgare were examined using a transmission electron microscope (TEM) for evidence of hemocyanin synthesis.For each experiment hemolymph was collected from twenty adult A. vulgare and fixed for 1 hour in 200 uL of 3.5% glutaraldehyde in 0.1M sodium cacodylate buffer pH 7.4 with 0.05% calcium chloride added. Hemolymph was then centrifuged at 3000 rpm in an IEC-DPR-6000 centrifuge for 15 minutes at 15 degrees centigrade. The supernatant was removed, and the resulting pellet was washed with three changes of sodium cacodylate buffer. Postfixation of the pellet was done in 1% osmium tetroxide for 1 hour.
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O'Brien, MM, M. Kiely, KE Harrington, PJ Robson, JJ Strain, and A. Flynn. "The North/South Ireland Food Consumption Survey: vitamin intakes in 18–64-year-old adults." Public Health Nutrition 4, no. 5a (October 2001): 1069–79. http://dx.doi.org/10.1079/phn2001188.

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AbstractObjectiveTo estimate vitamin intakes and assess the contribution of different food groups to vitamin intakes in adults aged 18–64 years in Ireland as estimated in the North/South Ireland Food Consumption Survey. Intakes are reported for retinol, carotene, total vitamin A, vitamin D, vitamin E, thiamin, riboflavin, pre-formed niacin, total niacin equivalents, vitamin B6, vitamin B12, folate, biotin, pantothenate and vitamin C. The adequacy of vitamin intakes in the population and the risk of occurrence of excessive vitamin intakes are also assessed.DesignFood consumption was estimated using a 7-day food diary for a representative sample (n = 1379; 662 men and 717 women) of 18–64-year-old adults in the Republic of Ireland and Northern Ireland selected randomly from the electoral register. Vitamin intakes were estimated using tables of food composition.ResultsIn general, the percentage of the population with vitamin intakes below the average requirement (AR) was low. Mean daily intake of total vitamin A was below the AR in 20.2% and 16.6% of men and women, respectively, and mean daily intake of riboflavin was below the AR in 12.5% and 20.6% of men and women, respectively. Mean daily folate intakes were below the AR for folate in 11.2% and 6.6% of women aged 18–35 years and 36–50 years, respectively. Only 2.2% of women aged 18–35 years and 52% of women aged 36–50 years achieved the recommended folate intake of 600 (μg day−1 for women of reproductive age for the prevention of neural tube defects. A high proportion of the population has a low dietary vitamin D intake and is largely dependent on sunlight exposure to maintain adequate vitamin D status. Except for pre-formed niacin, the 95th percentile intake of vitamins did not exceed the tolerable upper intake level (UL) for any group and was much less than the UL for most vitamins. Although 20.8% of men and 6.3% of women exceeded the UL for pre-formed niacin (which is 35 mg, based on nicotinic-acid-induced flushing), the large contribution of meat and fish to the intake of niacin (as nicotinamide) suggests that the risk of overexposure to nicotinic acid is much lower than this and is probably solely related to supplement use. A small proportion of men (4.0%) and women (1.2%) aged 51-64 years had retinol intakes that exceeded the UL (3000 μg) and while the 95th percentile intake of women in the 18–50 year age group was well below the UL, 1.5% of 18–35-year-old and 2.4% of 36–50-year-old women had mean daily retinol intakes above the UL. About 2.0% of women had intakes of vitamin B6 that exceeded the UL (25 mg). There were significant differences by age and sex in nutrient densities of vitamin intakes between men and women and between age groups, which may be explained by differences in consumption of particular food groups as well as different patterns of supplement use.ConclusionNutritional adequacy of the population for most vitamins was good. Folate intake in women of childbearing age is not meeting current recommendations for the prevention of neural tube defects. The public health significance of the relatively high proportion of men and women with inadequate intakes of vitamin A and riboflavin and with low dietary intakes of vitamin D is unclear and should be investigated further. With the possible exception of niacin (flushing) and vitamin B6 (neuropathy), there appears to be little risk of the occurrence of adverse effects due to excessive consumption of vitamins in this population, based on current dietary practices.
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Horstman, Larry Lawrence, Yeon-Soong Ahn, Jacob Esquenazi, Wenche Jy, Carlos J. Bidot, and Camile Ortega. "Elevated Cholinesterase Activity in Patients with TIA and Other Thrombotic Disorders." Blood 114, no. 22 (November 20, 2009): 2991. http://dx.doi.org/10.1182/blood.v114.22.2991.2991.

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Abstract Abstract 2991 Poster Board II-967 Background. The natural function of ACTH in blood is not well defined. However elevated plasma level was reported in patients with chronic inflammation, suggesting as one of inflammatory markers. Erythrocytes possess membrane-bound acetylcholinesterase (AChE) while plasma contains a less specific cholinesterase (ChE). We reported at a previous meeting [Blood 2008, 112(11) Abst #3849] that AChE activity of RBC-derived microparticles (RMP) is 6 times higher than those in PMP. In this study we measured plasma ACTH levels in several groups and encountered unexpectedly high plasma ChE activities in patients with TIA and other thrombosis. Methods. (i) Patient population. A series of n=108 consenting patients were recruited sequentially having various disorders For purpose of analysis, they were divided in 2 main groups: n=53 with thrombosis (TBS), F/M 27/26; and n=55 non-TBS, F/M 24/31. Thrombosis group consists of venous and arterial thrombosis including those with TIA. Non TBS group consists of anemias, thrombocytopenias including ITP, MDS. (ii) Assay was essentially by Ellman's method. In our system, milli-absorbance units/min (mA/min) x 0.065 = umols substrate cleaved/min. Values reported here are in unitsof mA/min per mL plasma. Normal controls (NC, n=14) had a cutoff of 3000 mA/min per mL plasma, = mean +2SD. (iii) Sample handling. Platelet-poor plasma (PPP) was prepared by centrifuging 10 min at 1800 xg, then frozen in aliquots. For assay, it was diluted 1:20 with saline, then 5 uL and 10 uL were used in 96-well microtiter plate. Results: (i) Significantly higher ChE activity was observed in thrombosis (TBS) patients compared to non-TBS. Mean value ±SD in TBS was 2928 ±773, and in Non-TBS was 1897 ±713 (units as above). This difference was significant, p<0.001. (ii) When analyzed elevated levels of ACTH above 2SD of normal controls (n=26) between 2 groups, the TBS group had elevated ChE (>3000) in 30% of patients, while the Non-TBS had elevated ChE in 7.8%. (iii) Further analysis among thrombosis group revealed that the subgroup with neurological TBS (TIA, minor strokes) had the most consistent elevations of ACTH; 10 of15 with TIA group (66%) had ChE activities >3000. Summary/ Discussion. Although ChE and AChE in blood has long been studied, to our knowledge, this is the first report to show a relation between plasma ChE and thrombosis. Its elevation is very pronounce in thrombosis of the CNS, manifesting as TIA. Further study is warranted to elucidate how ChE is related to AChE of the CNS and on red cells. Disclosures: No relevant conflicts of interest to declare.
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Bidot, Carlos J., Yeon-Soong Ahn, Jacob Esquenosi, Carlos Bidot, Camile Ortega, Larry Lawrence Horstman, Pamela B. Dudkiewicz, and Wenche Jy. "Plasma Cholinesterase Activity in ITP Patients with/without Thrombosis." Blood 114, no. 22 (November 20, 2009): 3997. http://dx.doi.org/10.1182/blood.v114.22.3997.3997.

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Abstract Abstract 3997 Poster Board III-933 Introduction In the process of immune mediated destruction, platelets may become activated and release procoagulant microparticles in ITP (Immune Thrombocytopenic Purpura). Although bleeding is common manifestation, some patients with ITP may suffer thrombotic complications, often presenting with TIA like syndromes. Brain MRI revealed findings consistent with ischemic small vessel disease in this subgroup (J Lab Clin Med 119: 334, 1992, Thromb Res 107:337, 2002). Recently acetylcoholinesterase (AChE) of RBC and/or non-specific plasma cholinesterase (ChE) was reported to be associated with the inflammation of blood vessels and may be a marker of some inflammatory states. In the present study we investigated plasma ChE activity in patients with ITP with or without thrombotic complication. Methods (i) Patients. We measured ChE activity in 49 patients with ITP. They were sub-grouped as having thrombosis (TBS), F/M (11/7), and non-thrombosis (Non-TBS), F/M (23/8). The TBS group included 9 with TIA like syndrome, 6 with CAD and 3 with venous thrombosis. (ii) Assay of ChE was essentially by Ellman's method. In our system, milli-absorbance units/min (mA/min) x 0.065 = umols substrate cleaved/min. Values reported here are in units of mA/min per mL plasma. Normal controls (NC, n=14) had a cutoff of 3000 mA/min per mL plasma (=mean +2SD). (iii) Sample handling. Platelet-poor plasma (PPP) was prepared by centrifuging 10 min at 1800 xg, then frozen in aliquots. For assay, it was diluted 1:20 with saline, then 5 uL and 10 uL were used in 96-well microtiter plate. Results (i) We observed higher level of ChE in the TBS group compared to Non-TBS in ITP. The TBS group (+/- SD) had mean value 2859 ±866, while the Non-TBS group had 2267 ±777 (units as above). This difference was significant, p<0.02. (ii) In TBS groups, we compared TIA subgroup with other TBS subgroup and observed that the n=9 patients with TIA had higher activity compared to the other TBS: 3250 vs 2466 mA/min per mL plasma. However, this difference did not reach significance in this small patient population. Further, 5/9 TIA patients (66%) had ChE activities >3000 (normal cutoff values) compared to only 2/9 (22%) of those with other TBS >3000. Conclusion (i) The ChE activity of ITP patients with TBS is significantly increased compared to Non-TBS in ITP patients. It has been suggested that Blood ChE/AChE may reflect some inflammatory, prothrombotic states. (ii) ITP patients with TIA exhibited higher ChE activity among TBS subgroups in ITP, suggesting that ChE activity may serve as a useful biomarker in TIA like syndrome associated with ITP. However, further study in a larger number of patients is needed to confirm these preliminary findings. Disclosures: No relevant conflicts of interest to declare.
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Dissertations / Theses on the topic "UL 3000"

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Chabot, Jacques. "Étude des artéfacts en pierre taillée découverts à tell 'Atij et Tell Gudeda en Mésopotamie septentrionale (Syrie du nord-est, âge du bronze ancien : 3000-2500 av. J.-C.)." Doctoral thesis, Université Laval, 1998. http://hdl.handle.net/20.500.11794/28495.

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Salas-Illanes, Nora. "Electronic Structure of Selected Materials by Means of the QSGW Method within the LAPW+LO Framework." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19804.

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Materialien formen die moderne Welt: Sie umgeben uns in unserem alltäglichen Leben. Unser Ziel ist die Materialeigenschaften nach unseren Bedürfnissen maßzuschneidern. Viele Materialeigenschaften wie Bandücken und Elektronendichteverteilung werden durch elektronische Zustände bestimmt. Die meisten Vorhersagen in Bezug auf Materialien entstammen der Dichtefunktionaltheorie (DFT). Diese Theorie ermittelt Grundzustandseigenschaften und kann jedoch keine Energien von angeregten Zuständen liefern. Um angeregte Zusände zu beschreiben, bedarf es daher einer höherstufigen Theorie: die Vielteilchen-Störungstheorie (MBPT) . Im Rahmen von MBPT ist das üblichste Verfahren die GW-Näherung (GWA), worin Elektronen als Quasiteilchen (QP) beschrieben werden. Der Energieunterschied zwischen einem nicht-wechselwirkenden Teilchen und einem QP ist die Selbstenergie. In GWA ergibt sich die Selbsenergie als Produkt aus die Einteilchen-Greenfunktion, G, und die abgeschirmte Coulomb-Wechselwirkung, W, und führt zu der wahren Anregungsenergie von QP. Diese Doktorarbeit beinhaltet die Implementierung von selbstkonsistentem Quasiteilchen-GW (QSGW) im exciting Code. Dieses Software-Paket benutzt die Linearized-Augmented-Plane-Wave-Methode (LAPW), welche alle Elektronen gleichberechtigt behandelt. Beginnend mit DFT optimiert die QSGW-Methode den Einteilchen-Hamiltonoperator durch eine selbstkonsistente Suche eines optimierten Austausch-Korrelationspotentials. Am Ende des iterativen Prozesses liefert die QSGW-Methode Eigenfunktionen und Eigenwerte der QP. Wir präsentieren mit QSGW ermittelte elektronische Strukturen von neun kristallinen Festkörpern. Wir präsentieren die zugehörigen Bandstrukturen und Zustandsdichtediagramme und vergleichen anhand dieser die QSGW-Ergebnisse mit Ergebnissen von DFT und G0W0. Zusätzlich untersuchen wir die elektronische Ladungsdichte und Wellenfunktion in ausgewählten Materialien.
Materials shape the modern world: they appear everywhere in our daily life. We investigate what governs the material's properties, in order to tailor them to meet our needs. Properties, e.g., bandgaps, and electronic density distribution are determined by the electronic structure. Most predictions on materials follow from computational physics, in particular density-functional theory (DFT). This scheme returns ground-state properties, but it fails to provide excited-state energies. To find the latter, we have to recourse to a higher degree of theory, namely many-body perturbation theory (MBPT). Within MBPT, the most popular framework is the GW approximation (GWA) which describes electrons as quasiparticles (QP). The difference in energy between a non-interacting particle and a QP is called the self-energy. In GWA, the product of the Green function G and W, the screened Coulomb interaction, returns the self-energy. GWA is in principle self-consistent, but is mostly implemented as a perturbative correction to DFT results, known as G0W0. Unfortunately, the electronic structure given by G0W0 depends on the initial DFT results. This PhD project consists in the implementation of the self-consistent quasiparticle GW (QSGW) in the exciting code. This software package uses the all-electron linearized augmented planewave (LAPW) method, treating every electron on equal footing. Starting from DFT, the QSGW method (based in the GWA) optimizes the one-particle Hamiltonian through a self-consistent search for an optimized exchange-correlation potential. At the end of the iterative process, the QSGW method provides eigenfunctions and eigenvalues of the QPs. Considering nine crystalline solids, we present their electronic structure by means of QSGW. We present the bandstructures and density of state diagrams, comparing QSGW results to DFT and G0W0 results. In addition, we study the electronic charge density and wavefunction in selected materials.
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Pelletier, Vincent. "Irrigation de la canneberge basée sur des seuils de tension de l'eau dans le sol." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30006/30006.pdf.

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Le démarrage de l’irrigation basé sur un seuil de tension de l’eau dans le sol (SWTI) permet à la canneberge de se maintenir dans une zone de confort hydrique idéale à sa croissance. Ce seuil pourrait atteindre 6.5 voire 8.0 kPa selon différents auteurs. Afin de valider ces recommandations, une étude au champ était nécessaire. L’objectif principal de ce projet était de déterminer la valeur de SWT¬I permettant de maximiser la productivité de l’eau (WP) sans affecter le rendement. En 2011-2012, un dispositif expérimental aléatoire en blocs complets a été mis en place dans trois sites au Québec et dans un site au Wisconsin. Le sol des quatre sites était un sable fin. Ce dispositif a permis de tester des valeurs de SWTI variant de 5.5 à 10.0 kPa. Des traitements humides et des traitements secs ont été comparés à des traitements témoins. Les précipitations ont maintenu la tension de l’eau dans le sol inférieure à 8,5 kPa dans le site où ce traitement était prévu, l’empêchant ainsi d’être testé. La WP a été significativement supérieure de 15 à 79 % dans les traitements secs et significativement inférieure de 21 à 50 % dans les traitements humides. Le traitement sec ayant une valeur SWTI de 10.0 kPa a connu une baisse de rendement significative de 11 %. Aucun autre traitement n’a présenté de différence significative au niveau du rendement. Le sol peut fournir l’eau nécessaire aux besoins de la canneberge jusqu’à une tension de 8.0 kPa. Lorsque ce seuil est dépassé, le flux capillaire ne semble pas suffisant pour combler les besoins de la plante, ce qui entraîne une baisse de rendement. Basée sur les présents résultats, la valeur SWTI recommandée pour démarrer l’irrigation dans les sables fins est de 8.0 kPa afin de maximiser la productivité de l’eau sans affecter le rendement. En utilisant ce seuil, les producteurs de canneberge pourraient augmenter leur productivité en économisant de l’énergie et en réduisant les coûts de main d’œuvre associés à l’irrigation.
The onset of irrigation based on a soil water tension threshold (SWTI) allows cranberry plants to grow in a comfort zone. According to different authors, this threshold could be 6.5 kPa, or 8.0 kPa. A field study was required to confirm these recommendations. This study was conducted to determine the optimum SWTI value that would optimize water productivity (WP) without decreasing yield. A randomize complete block design has been set up during the 2011 and 2012 growing seasons in three sites in Québec and one site in Wisconsin. In all cases the soil was fine sand. Values of SWTI ranged from 5.5 to 10.0 kPa and dry and wet treatments were compared to control treatments. The treatment with a SWTI value of 8.5 kPa has never been irrigated because the rain kept soil water tension under this threshold. The WP was significantly greater from 15 to 79 % in dry treatments and significantly lower from 21 to 50 % in wet treatments. The dry treatment with a SWTI value of 10.0 kPa had a significant yield depletion of 11 %. It was the only treatment with a significant yield difference. Fine sands seem to have sufficient capillary flux to the cranberry uptake for a soil water tension up to 8.0 kPa. After this threshold, capillary flux seems to be too low to feed cranberry plants and results in yield depletion. Based on the current results, a SWTI value of 8.0 is recommended to maximise water productivity without affecting yield. With this threshold, cranberry growers could improve their productivity with energy and labor savings.
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4

Hamel, Emmanuel. "Un modèle d’évaluation des coûts agrégés liés aux assurances pour les professionnels de la santé." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30040/30040.pdf.

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Dans ce mémoire, un processus d’évaluation des coûts agrégés liés aux assurances pour les professionnels de la santé est considéré. Au chapitre 1, nous décrivons les principales caractéristiques de l’assurance pour les professionnels de la santé : l’environnement, les types de couverture d’assurance, la prime, les coûts liés aux réclamations, les types de dépendances stochastiques dans le processus des coûts et dans les taux d’actualisation du processus des coûts. Au chapitre 2, une description des concepts théoriques préalables à l’élaboration et à l’application du modèle mathématique est faite : la dépendance (avec copules), le processus de renouvellement, la force d’intérêt et les méthodes numériques utilisées. Au chapitre 3, le modèle théorique du processus des coûts est établi et les premiers moments de ce processus sont obtenus, par des calculs numériques déterministes et par simulations. Au chapitre 4, plusieurs applications du modèle sont présentées : moments avec force d’intérêt stochastique (Vasicek), incidences de la dépendance sur le modèle, calculs de primes, mesures de risque (VaR et TVaR). Au chapitre 5, nous concluons ce mémoire.
In this master’s degree thesis, an aggregate loss model for health professionals is considered. The introduction describes some characteristics related to the insurance for health professionals: environment, type of insurance coverage, premium, cost of a claim, stochastic dependencies in the claim process and discount rate. In chapter 2, a description of theoretical concepts related to the proposed mathematical model is done: stochastic dependence (by copulas), renewal processes, discount rate (i.e. stochastic differential equations) and numerical methods. In chapter 3, the theoretical model is presented and the first moments are obtained, with deterministic numerical calculations and simulations. In chapter 4, some applications of the model are presented: first moments calculations with stochastic interest rate (Vasicek), impact of dependence on the model, premium calculations, risk measures (VaR and TVaR). In chapter 5, the conclusion follows.
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5

Rhéaume, Michel. "Le langage comme habitus chez Husserl." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30007/30007.pdf.

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La question qui nous intéresse est celle de savoir si et comment le langage peut avoir une influence sur la manière dont le monde se « donne » à une conscience. La phénoménologie développée par Husserl au début de son œuvre permet d’expliquer comment le langage est employé pour fixer et articuler la manière dont une conscience intentionnelle s’ouvre au monde et se rapporte à lui. Par contre, Husserl ne se donne pas encore les moyens de penser l’importance de l’ancrage historique des langues réelles, c’est-à-dire leur caractère irréductiblement situé, facticiel. Nous soutiendrons qu’il est possible d’élaborer, à partir des œuvres tardives de Husserl, un concept de langage comme « habitus », qui permettra de comprendre la manière dont le langage évolue, se modifie et se transmet au sein d’une tradition. La maîtrise parfaite et la transparence du langage apparaîtront au bout du compte comme des idéaux, possibles seulement pour une conscience radicalement auto-responsable.
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6

Soucy, Patrick. "Structuration de verres de chalcogénures par impulsions femtoseconde." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30003/30003.pdf.

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Les structures périodiques induites par laser sont étudiées depuis plusieurs années et sont présentes sur des matériaux très variés : métaux, verres, céramiques, matériaux cristallins, semi-conducteurs. Elles sont un phénomène générique mais elles ont leurs particularités pour chaque type de matériau. La plupart des modèles développés n’expliquent qu’une partie des résultats et ne s’étendent pas à tous les types de matériaux. Les modèles se basent généralement sur l’hypothèse d’une interférence du laser avec une onde créée subséquemment; elle peut être d’origine plasmonique si le matériau le permet. Ce mémoire a pour but de présenter les résultats de l’interaction d’un laser femtoseconde avec des verres de chalcogénure, en fonction des différents paramètres du laser.
Laser induced periodic surfaces structures have been the subject of studies for many years and are present on very different materials: metals, glasses, ceramics, crystalline materials, semiconductors. They are a generic phenomenon but each material has its distinctive features. The majority of the models developed only explain part of the results and do not extend over to all types of materials. They are generally based on the hypothesis of interference from the laser with a wave created subsequently; they can be of plasmonic nature if the material allows it. The purpose of this report is to present the results of femtosecond laser interaction with chalcogenide glasses, as a function of the various laser parameters.
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7

Grégoire, Caroline. "Caractérisation du mécanisme d'absorption du silicium par Equisetum arvense." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30060/30060.pdf.

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Le silicium (Si) est un élément ubiquiste et abondant dans l’environnement. L'absorption de Si par les plantes leur confère une résistance accrue à différents stress. Il y a une corrélation positive entre les effets bénéfiques observés et la quantité de Si absorbée via des transporteurs racinaires. Deux groupes de transporteurs d’influx et d’efflux ont été identifiés récemment dans les racines de certaines plantes supérieures. Afin de mieux utiliser le potentiel du Si, il est essentiel d’élargir le spectre des espèces végétales étudiées. Cette thèse utilise comme modèle une plante primitive fortement accumulatrice de Si : la prêle des champs (Equisetum arvense). L’objectif principal des travaux était d’identifier et de caractériser les transporteurs de Si de la prêle. Une approche utilisant le séquençage du transcriptome racinaire de la prêle a d’abord permis d’identifier chez cette plante une famille multigénique de transporteurs d’influx de Si : des aquaporines du sous-groupe des NIP. Une analyse phylogénétique ainsi qu’une comparaison des domaines fonctionnels ont permis de découvrir que les transporteurs de prêle appartiennent à un groupe de transporteurs distinct de celui des plantes supérieures. Les NIP de prêle ont un pore STAR, versus le pore GSGR commun à tous les autres transporteurs d’influx de Si. Afin d’en déterminer la fonction, les protéines de prêle ont été exprimées de façon hétérologue dans des ovocytes de Xenopus et chez Arabidopsis. Les résultats démontrent un influx élevé de Si. Les travaux ont ensuite permis d’identifier deux transporteurs Lsi2 d’efflux de Si chez la prêle, partageant une faible identité avec leurs homologues des plantes supérieures. Afin d’en déterminer la fonction, un des Lsi2 de prêle a également subi une expression hétérologue dans des ovocytes de Xenopus, confirmant qu’il s’agit d’un transporteur d’efflux de Si. Il est probable que l’absorption élevée de Si par la prêle soit due à l’abondance du nombre de gènes codant pour des transporteurs d’influx et d’efflux, mais aussi par l’activité spécifique élevée de ces transporteurs. Les travaux sur les transporteurs de Si chez la prêle permettent une comparaison entre les plantes primitives et les plantes agricoles modernes, afin d’optimiser l’usage du Si contre les stress.
Silicon (Si) is an abundant element in the environment. Plants benefit greatly from Si absorption, which results in increased resistance to stresses. There appears to be a link between high Si absorption via specific transporters, and the beneficial effects linked to this element. Recently, two groups of Si influx and efflux transporter were identified in the roots of Si-accumulating higher plants. Horsetail (Equisetum arvense) is a primitive plant and one of the strongest Si accumulators in the plant kingdom. The main objective of this thesis was to identify and characterize horsetail Si transporters. By sequencing the horsetail root transcriptome, we identified a multigene family of aquaporin Si influx transporters: aquaporins of the subgroup NIP. Comparison of known functional domains and phylogenetic analysis of sequences revealed that the horsetail proteins belong to a different group than higher-plant Si transporters. The horsetail proteins contain a STAR pore as opposed to the GSGR pore common to all previously identified Si influx transporters. In order to determine its functionality, the proteins were heterologously expressed in both Xenopus oocytes and Arabidopsis, and the results showed high Si influx activity. We also identified in horsetail two homologues of Lsi2 Si efflux transporters that share low sequence identity with their higher plant homologues. In order to determine its functionality, one of the horsetail Lsi2 was heterologously expressed in Xenopus oocytes, confirming its Si efflux activity. Overall, high Si accumulation by horsetail may be linked to the number of Si influx and efflux transporter, but also to their high transport activity. These findings on horsetail Si transporters allow a comparison between primitive plants and agronomic species, to optimize the use of Si against stresses.
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8

Dhital, Narayan Prasad. "Feasibility of an ecosystem-based management in an eastern Canadian boreal forest : testing for ecological suitability, economic viability, social acceptability and adaptability to wildfire and climate change." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30010/30010.pdf.

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Dans la quête de la mise en place d’une stratégie d’aménagement écosystémique (AE) dans la forêt boréale de l’est du Canada, nous avons réalisé une étude de faisabilité sur la viabilité économique, l’acceptabilité sociale et la pertinence écologique. À l’aide de modèles d’approvisionnement en bois, nous avons comparé une stratégie AE à une stratégie de normalisation des forêts (status quo) afin d’en évaluer sa robustesse et son l’adaptabilité face à l'augmentation du taux de brûlage et des anomalies de croissance induites par les changements climatiques. Les modèles d'approvisionnement en bois utilisent le plus souvent un modèle de croissance et de rendement calibré à l'échelle du peuplement (tables de production) pour projeter l’évolution du volume marchand des strates d’aménagement. Puisque les stratégies d'aménagement écosystémique ont tendance à repousser l'âge d'exploitabilité, il est pertinent d'évaluer jusqu'à quel degré les tables de production actuelles peuvent être utilisées comme intrant dans un contexte d'aménagement écosystémique. Lorsqu’une table de production est évaluée relativement à un modèle de croissance calibré à l’échelle de l’arbre, nous montrons que bien que le modèle à l’échelle d'arbre semble moins biaisé, aucun modèle performe de manière adéquate pour prédire la croissance en volume marchand dans notre aire d’étude, particulièrement lorsque nous subdivisons les données par les attributs qui peuvent jouer un rôle pendant la mise en place d’AÉ. Pour les deux modèles, la source majeure d’erreur est liée à la densité du peuplement. Grâce à leur simplicité relative, nous avons préféré utiliser les tables de production pour élaborer nos modèles d’approvisionnement en bois. La programmation linéaire standard a été utilisée pour tester les effets de quatre enjeux clefs sur le niveau d’approvisionnement en bois: (1) tendre vers une structure d’âge forestière établie à partir du régime naturel des feux et de la dynamique forestière, (2) agglomérer les blocs de récolte dans des chantiers de récolte afin de reproduire les patrons de perturbation naturelle à l’échelle du paysage, (3) maintenir les taux cumulés de coupe totale et de perturbation naturelle à l’intérieur du domaine historique de variabilité, et (4) exclure de la récolte les aires d’intérêt potentiel pour les peuples autochtones. Comparé à un scénario de status quo, l’inclusion des trois premiers enjeux résulte en une baisse de 3 à 22% de l’approvisionnement périodique et une période de restauration requérant que la coupe totale soit exclue sur 43 à 67% de la superficie productive pour les prochains 50 ans. Une validation des filtres bruts utilisés dans cette étude (les trois premiers enjeux) a été faite en utilisant les besoins en habitats du caribou des bois (Rangifer tarandus caribou). Pratiquement tous les scénarios induisaient un taux de perturbation susceptible de permettre le maintien du caribou des bois d’ici 25 ans. Enfin, nous avons intégré le taux de brûlage et la sensibilité des tables de production au climat dans nos modèles d’approvisionnement afin de quantifier les incertitudes induites par le climat et les feux pour les deux stratégies d’aménagements. Les deux modèles suggèrent une réduction de l’approvisionnement périodique en bois entre 13 et 79%. Même si les indicateurs écologiques favorisent l’AE par rapport la normalisation des forêts, juste un changement de stratégie n’est pas suffisant faire face aux impacts du risque de feu et des changements climatiques en forêt boréale. Mots clefs: Forêt boréale, aménagement écosystémique, croissance et rendement, faisabilité, adaptation, feux de la forêt, changements climatiques
In the quest of implementing an ecosystem-based management (EBM) in a boreal forest in eastern Canada, we conducted a feasibility study focusing on ecological suitability, economic viability and social acceptability. Through timber supply models, we compared the outputs of EBM with a business as usual (BAU) management to determine former’s robustness and adaptability to the increase in wildfire and growth anomalies induced by climate changes. Timber supply analyses use yield models, most often at the stand-level to project harvestable volume over the planning horizon. Since EBM tend to delay harvesting age, the question may be raised on to what extent existing yield tables can be used with such strategies. When a yield table is rated against a tree-level model, we show that although the tree-level model is less biased, none of the models performed adequately to predict the volume growth of our study area, especially when subdividing the data by attributes that may have an important role while implementing EBM. For both models, the major source of error was related to stand density. Due to its relative simplicity, we chose stand-level yield tables to build our timber supply models. We then carried out a feasibility study of implementing an EBM strategy in a boreal forest in eastern Canada. With standard linear programming, we tested four policy issues; age structure, harvest agglomeration; limit of cumulative disturbance, and land base of aboriginal interest. These issues were dealt with 3% – 22% reduction in periodic wood supply and a transition period of 50 years where clear-cut needs to be excluded in 43% – 67% of the productive area. Validation of the outputs through habitat requirement of woodland caribou (Rangifer tarandus caribou) as a fine filter showed that most of the scenarios should likely allow a self-sustaining caribou population within next 25-years. Finally, we integrated climate sensitive fire burn rates and yield tables in the timber supply models to quantify the uncertainty induced by climate and fire under both management strategies. Both models responded with a reduction of periodic wood supply by 13% – 79%. Although ecological indicators are relatively better under EBM, merely switching the management strategy is not enough to address the impacts of fire and climate change in the boreal forests. Key words: Boreal forest, ecosystem-based management, growth and yield, feasibility, adaptation, wildfire, climate change
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9

Landry, Sarah. "Contribution de la responsabilité des entreprises dans la construction de l'image organisationnelle : évolution sur dix ans pour dix entreprises canadiennes." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30090/30090.pdf.

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Les changements qui s’opèrent, depuis l’avènement du 21e siècle, dans la société, et qui en influencent les paramètres, notamment, l’intensification de la concurrence, la démocratisation des technologies de la communication ainsi que la multiplication des préoccupations collectives, favorisent la prise de responsabilités sociales par les organisations. Cet intérêt qu’expriment les organisations pour les pratiques de relations publiques axées sur la promotion de comportements socialement responsables donne lieu à l’élaboration de diverses stratégies d’image organisationnelle qui contribuent à maintenir un climat de confiance, à légitimer la place qu’occupent les organisations dans la société, et donc, à gérer les relations qu’entretiennent ces dernières avec leurs parties prenantes. À la lumière des différents travaux portant sur la responsabilité sociale des entreprises (RSE) dans un cadre de communication stratégique, mais aussi, de la présence non négligeable des stratégies d’image de cette nature et de la diversité qu’elles présentent au sein des organisations depuis le début des années 2000, notre intuition doublée de nos recherches préalables sur le sujet nous incitent à croire que ce type de stratégie organisationnelle est élaboré en fonction de différents indicateurs. Ainsi, nous avons analysé, en vue de confirmer ou d’infirmer cette hypothèse, des bilans sociaux, des revues de responsabilité sociale, etc., tirés de 20 rapports organisationnels produits au cours de la première décennie du siècle actuel, par dix entreprises canadiennes. Par cette étude de nature descriptive, nous souhaitons contribuer à l’avancement des connaissances au sujet des stratégies d’image de responsabilité sociale dans la discipline des relations publiques contemporaines.
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10

Laouati, Atmane. "Modélisation de problèmes thermoélectriques non linéaires dans un milieu fissuré par la méthode XFEM." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30001/30001.pdf.

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L’objectif principal de cette thèse est le développement d’un outil numérique, en utilisant l’approche XFEM, permettant la simulation des problèmes transitoires non linéaires thermoélectriques dans un milieu fissuré en deux dimensions, avec prise en compte des échanges thermiques et électriques entre les lèvres de la fissure. La simulation numérique de la propagation de fissures présente un grand intérêt pour de nombreux secteurs industriels (production d’aluminium, aéronautique, nucléaire, etc.). De plus, c’est un problème complexe sur le plan numérique. La méthode d’éléments finis classiques présentent des contraintes importantes de raffinement de maillage en fond de fissure, de remaillage pendant la propagation de la fissure avec la projection des champs, ce qui a pour effet d’augmenter le temps de calcul et de dégrader la précision des résultats. D’autre part, la méthode des éléments finis étendue XFEM, a reçu un succès grandissant pour le traitement de problèmes avec fissures durant la dernière quinzaine d’années. Elle permet d’utiliser un maillage qui ne se conforme pas à la géométrie des fissures, ceci grâce à un enrichissement de l’approximation éléments finis. Dans cette thèse, on s’intéresse à étendre le champ d’application de la méthode XFEM pour les problèmes non linéaires thermoélectriques avec fissures. En effet, le problème thermique transitoire est couplé avec le problème électrique par la génération de la chaleur dans le solide, et la génération de chaleur à la fissure à cause de la résistance de l’interface. Les échanges thermiques et électriques entre les lèvres de la fissure sont aussi considérés, et dépendent, respectivement, du saut de la température et du potentiel électrique à la fissure. En raison de la génération de la chaleur dans le solide et aux lèvres L’objectif principal de cette thèse est le développement d’un outil numérique, en utilisant l’approche XFEM, permettant la simulation des problèmes transitoires non linéaires thermoélectriques dans un milieu fissuré en deux dimensions, avec prise en compte des échanges thermiques et électriques entre les lèvres de la fissure. La simulation numérique de la propagation de fissures présente un grand intérêt pour de nombreux secteurs industriels (production d’aluminium, aéronautique, nucléaire, etc.). De plus, c’est un problème complexe sur le plan numérique. La méthode d’éléments finis classiques présentent des contraintes importantes de raffinement de maillage en fond de fissure, de remaillage pendant la propagation de la fissure avec la projection des champs, ce qui a pour effet d’augmenter le temps de calcul et de dégrader la précision des résultats. D’autre part, la méthode des éléments finis étendue XFEM, a reçu un succès grandissant pour le traitement de problèmes avec fissures durant la dernière quinzaine d’années. Elle permet d’utiliser un maillage qui ne se conforme pas à la géométrie des fissures, ceci grâce à un enrichissement de l’approximation éléments finis. Dans cette thèse, on s’intéresse à étendre le champ d’application de la méthode XFEM pour les problèmes non linéaires thermoélectriques avec fissures. En effet, le problème thermique transitoire est couplé avec le problème électrique par la génération de la chaleur dans le solide, et la génération de chaleur à la fissure à cause de la résistance de l’interface. Les échanges thermiques et électriques entre les lèvres de la fissure sont aussi considérés, et dépendent, respectivement, du saut de la température et du potentiel électrique à la fissure. En raison de la génération de la chaleur dans le solide et aux lèvres
The main objective of this thesis is the development of a numerical tool, using the XFEM approach, for the simulation of transient nonlinear thermoelectrical problems in fractured media in two dimensions, taking into account thermal and electrical exchanges between the crack’s lips. Numerical simulations of crack propagation are of great interest for many industrial sectors (aluminum production, aerospace, nuclear, etc.). In addition, this is a numerically complex problem. The classical finite element method has important constraints of mesh refinement at the crack tip, remeshing during crack propagation and field projections, which has the effect of increasing the computation time and degrading the accuracy. On the other hand, the eXtended Finite Element Method (XFEM), has received a growing success for the treatment of the problems containing cracks in the last fifteen years. It allows using a mesh that does not conform to the geometry of the crack; this is possible by the enrichment of the finite element approximation. In this thesis, we are interested in extending application field of the XFEM method to the nonlinear thermoelectrical problems with cracks. Indeed, the transient thermal problem is coupled to the electrical problem by the heat generation in the solid, and the heat generation at the crack’s lips due to the interface resistance. The heat and electrical exchanges between the crack’s lips are also considered, and depend, respectively, on the temperature and the voltage jump at the crack. Due to the heat generation in the solid and in crack’s lips (Joule effect), and the temperature dependence of the physical parameters of the material, the problem is nonlinear and fully coupled. The discretized nonlinear system by the XFEM method is solved using the Newton-Raphson algorithm. The robustness of the proposed technique is demonstrated through the simulation of different examples, and the results shows an excellent agreement with the analytical solution, or with the finite element solution using a refined mesh.
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