Littérature scientifique sur le sujet « Magee mechanism »
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Articles de revues sur le sujet "Magee mechanism"
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Forche, Anja, Georgiana May et P. T. Magee. « Demonstration of Loss of Heterozygosity by Single-Nucleotide Polymorphism Microarray Analysis and Alterations in Strain Morphology in Candida albicans Strains during Infection ». Eukaryotic Cell 4, no 1 (janvier 2005) : 156–65. http://dx.doi.org/10.1128/ec.4.1.156-165.2005.
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ABSTRACT Candida albicans is a diploid yeast with a predominantly clonal mode of reproduction, and no complete sexual cycle is known. As a commensal organism, it inhabits a variety of niches in humans. It becomes an opportunistic pathogen in immunocompromised patients and can cause both superficial and disseminated infections. It has been demonstrated that genome rearrangement and genetic variation in isolates of C. albicans are quite common. One possible mechanism for generating genome-level variation among individuals of this primarily clonal fungus is mutation and mitotic recombination leading to loss of heterozygosity (LOH). Taking advantage of a recently published genome-wide single-nucleotide polymorphism (SNP) map (A. Forche, P. T. Magee, B. B. Magee, and G. May, Eukaryot. Cell 3:705-714, 2004), an SNP microarray was developed for 23 SNP loci residing on chromosomes 5, 6, and 7. It was used to examine 21 strains previously shown to have undergone mitotic recombination at the GAL1 locus on chromosome 1 during infection in mice. In addition, karyotypes and morphological properties of these strains were evaluated. Our results show that during in vivo passaging, LOH events occur at observable frequencies, that such mitotic recombination events occur independently in different loci across the genome, and that changes in karyotypes and alterations of phenotypic characteristics can be observed alone, in combination, or together with LOH.
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Davis, Sissmol, Dr Serene Sara John, Aditya Santoki, Sreedharan Sankaranarayanan, Pavithran Keechilat, Cherian Thampy, Yashaswini Shivashankara et al. « Correlation between Magee score and recurrence score in Indian patients with breast cancer. » Journal of Clinical Oncology 41, no 16_suppl (1 juin 2023) : e12555-e12555. http://dx.doi.org/10.1200/jco.2023.41.16_suppl.e12555.
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e12555 Background: Recurrence score (RS) from Oncotype Dx (ODx) test predict chemotherapy benefit in estrogen receptor (ER) positive, and HER2-negative patients with breast cancer. ODx is an expensive test in an Indian practice setting - cost of adjuvant chemotherapy is one-sixth of the cost of the test. Magee equations use histopathological variables, and semiquantitative results from ER, PR and Ki-67, to calculate Magee score (MS) and provide a cost-effective surrogate mechanism for predicting RS. We aimed to assess the correlation between MS and RS in an Indian setting. Methods: Pathology reports were obtained from oncologists in India. Immunohistochemistry for ER and PR were reported using the Allred system. Therefore, two methods were identified to estimate H-scores - using a calculated method (A), and using an expert-approximated (B) method. MS were calculated by a single investigator blinded to the RS. MS and RS were then assessed for correlation via the Pearson correlation method. MS were arbitrarily stratified into ≤ 15, 15 - 30, and ≥ 30, and their overall agreement (OA) or concordance with RS risk categories, ≤ 15, 15 - 30, and ≥ 30, were assessed. The OA was assessed by determining the proportion of patients in similar risk categories across low, intermediate and high-risk RS and MS. Results: Among 34 patients included in the study, 38% (13) had an RS ≤ 15, 38% (13) had an RS between 15 and 30, and 23% (8) had an RS ≥ 30. Correlation coefficient between MS and RS was 0.78 for both methods of estimation (p<0.0001). The OA between MS-A and RS, and MS-B and RS were 59% (20/34) and 47% (16/34) respectively. The concordance between low-risk MS-A and RS is 78% (n=9) and between low-risk MS-B and RS is 50% (n=20). The concordance between high-risk MS-A and RS is 100% (n=2) and high-risk MS-B and RS is 100% (n=2). Conclusions: Although there is good correlation between RS and MS, the concordance between the two in similar risk categories is not optimal. Of the two methods to estimate H-score from Allred score, the calculated method seems to be more optimal. Our pilot study shows good correlation between MS and RS. We recommend that pathologists incorporate H-score as part of the reporting of ER and PR. A larger prospective study will be useful to test our hypothesis for the use of MS as a predictive tool for adjuvant chemotherapy in breast cancer.
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Zhang, Christine R., Elizabeth Ostrander, Won Kyun Koh, Ostap kukhar, Hamza Celik, Jeffrey Magee et Grant Challen. « Abstract LB555 : Augmented Txnip-p53-p21 axis preserves Dnmt3a mutant hematopoietic stem cells during inflammatory stress ». Cancer Research 82, no 12_Supplement (15 juin 2022) : LB555. http://dx.doi.org/10.1158/1538-7445.am2022-lb555.
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Abstract Clonal hematopoiesis (CH), the age-related expansion of specific clones in the blood system has been considered as a pre-malignant condition of blood cancers. Approximately 50% of CH manifests from DNMT3A mutations acquired in the hematopoietic stem cells (HSCs), suggesting these mutations may convey a fitness advantage to HSCs during hematopoietic stress. However, a unifying molecular mechanism to illuminate how DNMT3A-mutant HSCs outcompete their counterparts is still lacking. Here, we used interferon-gamma (IFNg) as a model to study the mechanisms by which Dnmt3a mutations enhances HSC fitness under recurrent inflammatory stress. To represent the spectrum of DNMT3A variants found in humans, mouse genetic models were generated by specifically deleting Dnmt3a heterozygously (Vav-Cre;Dnmt3afl/+ = Dnmt3aHET) or homozygously (Vav-Cre;Dnmt3afl/fl = Dnmt3aKO) from the hematopoietic system. A hematopoietic system-specific knockin model analogous to the hotspot point mutation most prevalent in AML (Vav-Cre;Dnmt3aR878H/+ = Dnmt3aR878) was also included in the analysis. Competitive transplantation assays coupled with inflammatory and proliferative challenges suggested that Dnmt3aKO and Dnmt3aR878 HSCs were specifically tolerant of the deleterious effects of IFNg on HSC self-renewal and clonal expansion. When the competition between Dnmt3a-mutant and control HSCs under IFNg exposure was directly quantified in a novel mouse model, we found Dnmt3a-mutant HSCs resisted IFNg-mediated depletion due to an enhanced fitness advantage. Mechanistically, DNA hypomethylation-associated over-expression of Txnip in Dnmt3a-mutant HSCs was identified by coupling single-cell RNA-sequencing and Whole-Genome Bisulfite sequencing. The sustained Txnip levels in Dnmt3aKO HSCs lead to p53 stabilization and upregulation of p21 under IFNg challenge, further correlated with a retained quiescence due to a prolonged G0 exit in response to IFNg exposure. Implementing biochemical studies, we observed Txnip mediated an enrichment of p53 at p21 promoter under IFNg exposure in Dnmt3aKO but not control 32D cells. Knocking down Txnip by shRNA normalized p53 occupancy at p21 promoter and rescued IFNg-associated p21 upregulation in Dnmt3aKO 32D cells. Functionally, knocking down Txnip and p21 sensitized Dnmt3aKO HSCs to IFNg-induced cell cycle activation ex vivo. In vivo, down-regulation of p21 had no effect on control HSCs in response to IFNg exposure, but it completely primed Dnmt3aKO and Dnmt3aR878 HSCs to IFNg-associated exhaustion in a transplantation experiment. In summary, our data suggest an augmented Txnip-p53-p21 axis preserves the functional potential of Dnmt3a-mutant HSCs under inflammatory stress, which highlights a novel mechanism to explain the increased fitness of Dnmt3a-mutant HSCs and supports rationale for developing interventions to mitigate expansion of pre-malignant clones as a method of blood cancer prevention. Citation Format: Christine R. Zhang, Elizabeth Ostrander, Won Kyun Koh, Ostap kukhar, Hamza Celik, Jeffrey Magee, Grant Challen. Augmented Txnip-p53-p21 axis preserves Dnmt3a mutant hematopoietic stem cells during inflammatory stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB555.
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Leedom, Tom A., Barbara Muz, Jaykumar Vadakekolathu, John J. Muth, Xiao-Hua Li, Gregory Watson, Kristaan Magee et al. « Abstract 6418 : xWU-NK-101 as salvage therapy post immune checkpoint blockade (ICB) ». Cancer Research 83, no 7_Supplement (4 avril 2023) : 6418. http://dx.doi.org/10.1158/1538-7445.am2023-6418.
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Abstract ICB therapy has transformed cancer treatment; durable responses in difficult-to-treat cancers have been observed. Despite this most patients (pts) don’t respond to ICB (primary resistance), and many pts who initially respond eventually relapse (acquired resistance). Primary resistance is associated with tumor cell extrinsic factors, e.g., the immunosuppressive nature of the tumor microenvironment (TME), while acquired resistance is associated with tumor intrinsic factors, e.g., downregulation of MHC1, preventing T cell recognition. Treatments to overcome ICB resistance are necessary. WU-NK-101 is a PBMC-derived, cytokine-reprogrammed, expanded, and cryopreserved off-the-shelf memory NK cell product. WU-NK-101 cells capture the memory-like NK cell biology of cytokine-induced memory-like (CIML) NK cells, exhibiting enhanced cytotoxicity, metabolic fitness/flexibility, and resistance to TME immunosuppression (Muth et al. EHA 2022; Rutella et al. ESMO 2022). Bone marrow biopsies, collected from R/R AML pts who received CIML-NK cells (NCT01898793), were interrogated using immune gene expression (GE) profiling and spatially resolved proteomics (IO360® panel, n = 740 genes, and GeoMx® DSP; NanoString Technologies). Higher T-cell infiltration was noted post CIML-NK. CIBERSORT deconvoluted GE data inferred higher abundance of macrophages, γδT cells and activated dendritic cells on day 28 post-treatment. GE signatures showed downregulation of NFIL3 and FAM30A (log2 fold-change <1.0; p<0.05) post CIML-NK. TIDE algorithm modelling indicated that lower expression of NFIL3 and FAM30A correlated with high CTL infiltration and improved outcomes in many TCGA tumors (Jiang et al. Nat. Med. 2018). Hence, CIML-NK treatment led to modifications in the TME towards a more T-cell amenable environment. Deleting MHC1 on NALM6 cells significantly improved WU-NK-101 killing compared to WT (p<0.0001), highlighting one mechanism whereby WU-NK-101 overcomes acquired ICB resistance. In transwell assays, co-incubation of tumor cells with WU-NK-101 in the lower chamber led to dose dependent killing; in the upper chamber (tumor cells alone), viability was preserved but a dose-dependent increase of MHC1/PDL1 expression was noted. Similar results were observed using cell-free conditioned media from WU-NK-101 cytotoxicity assays, suggesting that soluble factors released from WU-NK-101 augment MHC1/PDL1 expression. Treatment of tumor cells with IFNγ alone led to similar increases in MHC1/PDL1 expression. Importantly, in vivo experiments revealed that residual tumor cells post WU-NK-101 treatment exhibited higher levels of MHC1/PDL1. Overall, these data highlight a further mechanism through which WU-NK-101 overcomes acquired ICB resistance. In summary, WU-NK-101 has the potential to reverse primary and acquired mechanisms of ICB resistance. A Phase 1b clinical trial of WU-NK-101 as salvage therapy post-ICB is in development. Citation Format: Tom A. Leedom, Barbara Muz, Jaykumar Vadakekolathu, John J. Muth, Xiao-Hua Li, Gregory Watson, Kristaan Magee, Ryan P. Sullivan, Melissa Berrien-Elliott, Todd Fenigher, Sergio Rutella, Matthew L. Cooper, Ayman Kabakibi, Jan K. Davidson-Moncada. xWU-NK-101 as salvage therapy post immune checkpoint blockade (ICB) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6418.
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Nogueira-Arjona, Raquel, Kara Thompson, Athena Milios, Alyssa Maloney, Terry Krupa, Keith S. Dobson, Shu-Ping Chen et Sherry H. Stewart. « The Mediating Effects of Protective Behavioral Strategies on the Relationship between Addiction-Prone Personality Traits and Alcohol-Related Problems among Emerging Adults ». International Journal of Environmental Research and Public Health 18, no 4 (12 février 2021) : 1814. http://dx.doi.org/10.3390/ijerph18041814.
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Alcohol consumption and associated harms are an issue among emerging adults, and protective behavioral strategies (PBS) are actions with potential to minimize these harms. We conducted two studies aimed at determining whether the associations of at-risk personality traits (sensation-seeking [SS], impulsivity [IMP], hopelessness [HOP], and anxiety-sensitivity [AS]) with increased problematic alcohol use could be explained through these variables’ associations with decreased PBS use. We tested two mediation models in which the relationship between at-risk personality traits and increased problematic alcohol use outcomes (Study 1: Alcohol volume; Study 2: Heavy episodic drinking and alcohol-related harms) was partially mediated through decreased PBS use. Two samples of college students participated (N1 = 922, Mage1 = 20.11, 70.3% female; N2 = 1625, Mage2 = 18.78, 70.3% female). Results partially supported our hypotheses, providing new data on a mechanism that helps to explain the relationships between certain at-risk personality traits and problematic alcohol use, as these personalities are less likely to use PBS. In contrast, results showed that AS was positively related to alcohol-related harms and positively related to PBS, with the mediational path through PBS use being protective against problematic alcohol use. This pattern suggests that there are other factors/mediators working against the protective PBS pathway such that, overall, AS still presents risks for alcohol-related harms.
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Hothi, Harry. « The impact and surgeon perceptions of the suspension of the CE certification of MAGEC devices on clinical practice ». Bone & ; Joint Open 3, no 2 (1 février 2022) : 155–57. http://dx.doi.org/10.1302/2633-1462.32.bjo-2021-0144.r2.
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MAGnetic Expansion Control (MAGEC) rods are used in the surgical treatment of children with early onset scoliosis. The magnetically controlled lengthening mechanism enables rod distractions without the need for repeated invasive surgery. The CE certification of these devices was suspended in March 2021 due, primarily, to performance evidence gaps in the documents provided by the manufacturer to regulators and notified bodies. MAGEC rods are therefore not permitted for use in countries requiring CE marking. This was a survey of 18 MAGEC rod surgeons in the UK about their perception of the impact of the CE suspension on the clinical management of their patients. Unsurprisingly, virtually all perceived a negative impact, reflecting the complexity of this patient group. Reassuringly, these surgeons are highly experienced in alternative treatment methods. Cite this article: Bone Jt Open 2022;3(2):155–157.
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Isaksen, Christina Vogt, Rigmor Austgulen, Lisa Chedwick, Pål Romundstad, Lars Vatten et Catherine Craven. « Maternal Smoking, Intrauterine Growth Restriction, and Placental Apoptosis ». Pediatric and Developmental Pathology 7, no 5 (septembre 2004) : 433–42. http://dx.doi.org/10.1007/s10024-004-0105-1.
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Pregnant women who smoke are at greater risk of delivering a growth-restricted infant than nonsmoking mothers. We wanted to see if apoptosis could be involved in the mechanisms behind smoke-induced growth restriction, and our aim was to compare apoptosis in the placenta of smoking mothers giving birth to growth-restricted infants and nonsmoking mothers with infants of appropriate weight. The project was conducted at the Magee—Womens Hospital and Magee—Womens Research Institute, University of Pittsburgh, PA. Histological sections from 20 placentas were selected from smoking mothers who had given birth to small-for-gestational-age infants (birth weight ≤ 2 SD). The controls were gestational-age matched nonsmoking mothers with infants having appropriate-for-gestational-age weight. The TUNEL method was used to demonstrate DNA fragmentation in nuclei, and a monoclonal antibody M30, specific for a neo-epitope on cytokeratin 18, was used to identify apoptotic epithelial cells. The positive nuclei (TUNEL) and positive cells (M30-positive cytoplasm) were counted blindly both in villous tissue and in decidual/basal plate tissue. M30-positive cells in villous tissues were significantly increased in placentas from smoking mothers compared to nonsmoking mothers. When evaluated by the TUNEL method, the difference between the two groups of women was not significant. Our study shows that apoptosis was increased in the placentas of smoking mothers with growth-restricted infants. The difference between the two groups was mainly in the syncytiotrophoblast layer and in connection with perivillous fibrin deposition. Cigarette smoke with reduction in blood flow has previously been shown to increase apoptosis, and it is possible that this could be one of the mechanisms playing a role in the growth restriction.
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Breznik, Barbara, Bernarda Majc, Anamarija Habič, Gloria Krapež, Andrej Porčnik, Jernej Mlakar, Tamara Lah Turnšek, Metka Novak et Klementina Fon Tacer. « Abstract 170 : Glioblastoma patient-derived organoids as a model for discovering novel markers of therapy resistance in the context of tumor microenvironment : potential role of melanoma antigens ». Cancer Research 83, no 7_Supplement (4 avril 2023) : 170. http://dx.doi.org/10.1158/1538-7445.am2023-170.
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Abstract Introduction: Glioblastoma is resistant to standard treatment, leading to tumor recurrence and early death of patients. Using organoid models, we aim to explore the mechanisms of resistance to cancer therapies and identify novel therapeutic vulnerabilities, including stress protecting melanoma-associated antigens (MAGEs). MAGEs are normally restricted to expression in testis but are abnormally activated in cancer and are associated with therapy resistance. Methods: Organoids have been established from fresh tumor biopsies and are stored in Gliobank, a Slovenian collection of patient tumor samples with corresponding clinical data. Organoids were first characterized and compared with the corresponding parental tumor tissue by immunofluorescence and qPCR of selected markers. Organoids were then treated with a combination of irradiation, the chemotherapeutic agent temozolomide and/or a chemokine receptor antagonist, and response to therapy was assessed by immunofluorescence, qPCR, cell viability and invasion assays, multiplex ELISA and proximity ligation assay. Results: Organoids recapitulated the gene expression profile of parental glioblastoma tissues, including expression of genes related to cancer stem cells, DNA damage response, cell cycle progression, epithelial- to- mesenchymal transition, and cytokine signaling. In addition, the organoids preserved the cellular composition of the parental glioblastoma tissues, consisting of glioblastoma (stem) cells, macrophages, microglia, lymphocytes, and endothelial cells. Standard treatment decreased viability and invasion of organoids in only 2 of 6 patients, suggesting that organoids recapitulate tumor therapy resistance. The increased expression of MDM2 and CDKN1A in organoids after treatment with irradiation and temozolomide suggests that the p53 pathway and DNA damage response mechanisms may contribute to the therapy resistance. Next, we detected high abundance of secreted cytokines in the culture medium of the organoids, including CXCL12. However, treatment of the organoids with the CXCR4 antagonist Plerixafor, which blocked the interactions between CXCL12 and CXCR4 in the organoids, had no effect on organoid viability and invasion, suggesting resistance of glioblastoma to this immunotherapy. Since high expression of several type I MAGEs correlates with poor prognosis of glioma patients based on TCGA database analysis, we investigate the role of MAGEs in therapy resistance of glioblastoma organoids. Conclusions: Patient-derived tumor organoids provide a valuable tool to 1) identify novel therapeutic vulnerabilities in the context of the tumor microenvironment, 2) evaluate the effect of novel candidate treatments including immunotherapy, and 3) discover novel markers of therapy resistance. Citation Format: Barbara Breznik, Bernarda Majc, Anamarija Habič, Gloria Krapež, Andrej Porčnik, Jernej Mlakar, Tamara Lah Turnšek, Metka Novak, Klementina Fon Tacer. Glioblastoma patient-derived organoids as a model for discovering novel markers of therapy resistance in the context of tumor microenvironment: potential role of melanoma antigens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 170.
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БАЛАБАНОВ, Р. А., В. В. ВЛАСЕНКО et А. Ю. НОЗДРАЧЕВ. « DESCRIPTION OF PREMIXED TURBULENT COMBUSTION IN A CHANNEL WITH A STEP USING PARTIALLY STIRRED REACTOR MODELS ». Физика горения и взрыва 60, no 4 (31 juillet 2024) : 44–55. http://dx.doi.org/10.15372/fgv2024.9453.
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Рассматривается дозвуковое турбулентное горение предварительно перемешанной метановоздушной смеси в модельном канале с обратным уступом (P. Magre и др., ONERA, 1975–1989). В экспериментах воспроизведены базовые физические механизмы, характерные для процессов горения в газотурбинных установках. Дан краткий обзор предыдущих работ по численному моделированию этих экспериментов. Описаны новые результаты численного исследования режима стабилизированного горения в данной установке. Проведено сравнение нескольких подходов к описанию турбулентного горения из класса PaSR (partially stirred reactor — модели реактора частичного перемешивания) с квазиламинарным подходом. Представлена модель переменных турбулентных чисел Прандтля и Шмидта, и рассмотрено ее влияние на воспроизведение данного течения в расчете. Subsonic turbulent combustion in a premixed methane—air mixture in a model channel with a backward step is considered (P. Magre et al., ONERA, 1975–1989). The main physical mechanisms characteristic of combustion in gas turbine combustors are reproduced in experiments. A brief overview of previous numerical simulations of these experiments is given. New results from a numerical study of the stabilized combustion regime in this combustor are described. Several partially stirred reactor (PaSR) models for describing turbulent combustion are compared with a quasi-laminar approach. A model of variable turbulent Prandtl and Schmidt numbers is presented, and its influence on the reproduction of this flow in calculations is considered.
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Pettigrew, Warren. « Unkonventioneller Stromsensor ohne Ringkern ». Konstruktion 70, no 10 (2018) : 54–56. http://dx.doi.org/10.37544/0720-5953-2018-10-54.
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Ein innovativer Stromsensor bietet Vorteile gegenüber konventionellen Stromwandlern. Das neusee- ländische Unternehmen Raztec Sensors, bekannt als Spezialist für Halleffekt-Stromwandler, präsentiert einen ganz und gar unkonventionellen Ansatz für die Strommessung, der ohne den üblichen magne- tischen Ringkern auskommt und damit neue Möglichkeiten in der Anwendung und Montage eröffnet.
Thèses sur le sujet "Magee mechanism"
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Jimenez, Reyes Jose. « Experimental and numerical contribution to the study of transformation induced plasticity (TRIP) ». Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR20.
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Ce travail a été réalisé dans le but d'apporter une contribution à l'étude de la plasticité induite par transformation (TRIP) à travers des analyses expérimentales et numériques. Pour ce faire, du point de vue expérimental, un programme expérimental original sur l'acier 35NCD16 observant les comportements des transformations austénite → martensite est réalisé sous différentes conditions de chargement. Les résultats indiquent que : (i) le TRIP n'a pas d'effet mémoire significatif, (ii) le matériau peut présenter une récupération de l'écrouissage pendant la transformation martensite → austénite, (iii) une dissymétrie entre les réponses du TRIP en tension et en compression a été observée, (iv) l'existence d'une contre-contrainte du TRIP a été révélée, (v) la quantité de TRIP final peut être considérée comme proportionnelle à la norme de la contrainte appliquée tant que cette dernière ne dépasse pas la limite d'élasticité, et (vi) une légère orientation physique a toutefois été observée lors de l'analyse microstructurale de notre matériau, ce qui pourrait suggérer une faible contribution du mécanisme de Magee dans le TRIP. Quant au côté numérique, les capacités prédictives du modèle Leblond – Taleb – Sidoroff (LTS) et de sa version actualisée (U – LTS) sont mises à l'épreuve en simulant les essais expérimentaux réalisés dans le cadre de cette étude. Nos résultats montrent que (i) le modèle LTS surestime les résultats expérimentaux, (ii) le modèle LTS ne parvient pas à décrire la dissymétrie entre les réponses TRIP en tension et en compression, (iii) en utilisant le modèle U – LTS, les résultats comparatifs montrent d'excellentes capacités à simuler la base de données expérimentale réalisée dans ce travail, en particulier par rapport au modèle LTS. Bien que nos résultats expérimentaux aient montré des résultats significatifs, en particulier lorsqu'ils sont comparés aux modèles observés dans notre étude, il est recommandé de poursuivre les recherches en prenant en compte d'autres aciers et d'autres transformationsThis thesis has been created with the objective of providing a contribution to the study of transformation induced plasticity (TRIP) via experimental and numerical analyses. To do so, from the experimental point of view, an original experimental program on 35NCD16 steel observing the behaviors of austenite → martensite transformations were performed under different loading conditions. The results indicate that: (i) TRIP does not hold any significant memory effect, (ii) the material may present recovery from strain hardening during the martensite → austenite transformation, (iii) a dissymmetry between the TRIP responses under tension and compression were observed, (iv) the existence of TRIP backstress was revealed, (v) the amount of final TRIP may be considered proportional to the norm of the applied stress as long as the latter does not exceed the yield stress, and (vi) a slight physical orientation has however been observed when carrying out microstructural analyses on our material, which could suggest a small contribution of the Magee mechanism in TRIP. As for the numerical side, the predictive capabilities of the Leblond – Taleb – Sidoroff (LTS) model, and its updated version (U – LTS) are put to the test by simulating the experimental tests performed for this study. Our results show that: (i) the LTS model overestimates the experimental results, (ii) the LTS model fails in describing the dissymmetry between the TRIP responses under tension and compression, (iii) when using the U – LTS model, the comparative results show excellent capabilities in simulating the experimental data base performed in this work, especially compared to the LTS model. While our experimental results showed significant results, especially when put up against to the models observed in our study, further research considering other steels and other transformations is recommended
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Ritner, Robert Kriech. « The mechanics of ancient Egyptian magical practice / ». Chicago : Oriental institute of the University of Chicago, 1993. http://catalogue.bnf.fr/ark:/12148/cb355989811.
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Legros, Hilaire. « Sur quelques problemes de dynamique planetaire ». Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13173.
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La rotation et la deformation d'une planete, sous l'action de certaines forces, interagissent entre elles: cette interaction, decrite par les nombres de love, est etudiee dans le cas d'une planete composee d'un noyau liquide, d'un manteau elastique et d'une couche fluide superficielle. L'elasticite du manteau et la geometrie du noyau fluide determinent la periode chandlerienne et la periode presque diurne associee a la rotation quasi-rigide du noyau; ils modifient les resonances associees et perturbent les rotations de l'axe de la terre dans l'espace et les mouvements de grande amplitude dans le noyau
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Aelbrecht, Denis. « Étude expérimentale de la rectification d'un écoulement alternatif pariétal en milieu tournant et de la turbulence d'une couche d'Ekman oscillante : application aux courants de marée en Manche orientale ». Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10103.
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La rectification d'un ecoulement de fluide homogene force alternativement sur un fond plat horizontal et le long d'une paroi verticale en milieu tournant est etudie experimentalement. On montre comment les echanges de quantites de mouvement entre la couche d'ekman et la couche limite contre la paroi provoquent une interaction non lineaire forte entre les composantes horizontales du courant, qui engendre un courant residuel significatif le long de la paroi. Ce courant laisse la paroi verticale sur sa droite dans le cas d'une rotation correspondant a l'hemisphere nord. Les caracteristiques de ce courant residuel, ou rectifie, sont determinees a l'aide de techniques de visualisation et de mesure velocimetrique. L'evolution parametrique du phenomene est confrontee avec une modelisation theorique de l'ecoulement et avec des simulations numeriques. L'existence d'un courant residuel cotier le long des cotes francaises de la manche orientale rend pertinente l'application de notre etude aux courants de maree de cette region. On etudie ensuite la transition vers la turbulence de la couche d'ekman presente sous l'ecoulement alternatif force. Des reseaux d'ondes d'instabilite peuvent apparaitre, puis interagir si le nombre de reynolds est grand, ou encore se detruire au moment de la renverse du courant. Ces explosions engendrent un melange vertical important. Des mesures de fluctuations des vitesses, realisees au film chaud, confirment les observations. On peut encore envisager d'appliquer ces resultats a la turbulence de fond des courants de maree dans la manche
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RAMIREZ, CAROLINE. « Contribution à l'étude des ondes internes non-linéaires en milieu tournant ». Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10221.
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Nous etudions a l'aide de la theorie de l'eau peu profonde une onde interne plane dans le contexte d'un fluide tournant stratifie en bicouche. Differents cas ont ete traites pour lesquels les hypotheses de faible ecart de densite entre les couches et de faibles epaisseurs de couches sont considerees independamment ou en meme temps. Nous apportons la demonstration qu'une equation d'ostrovsky gouverne les ondes internes non-lineaires d'interface dans le cas faiblement tournant. Nous demontrons que reduire l'ecart de densite conduit a augmenter les effets de la rotation. Enfin nous etablissons les equations qui gouvernent les ondes internes dans quelques cas particuliers et nous donnons la forme de celle-ci. Des experiences ont ete menees dans la grande cuve tournante du laboratoire coriolis pour etudier l'influence de la rotation sur des ondes internes axisymetriques. Nous avons mis en evidence quelques phenomenes interessant et les conclusions experimentales confirment nos resultats analytiques en ce qui concerne les influences respectives de l'ecart de densite et de la rotation. La rotation modifie considerablement les lois d'evolution de l'amplitude en fonction de la distance au centre de la cuve. Une autre partie de l'etude a ete consacree a la recherche experimentale de la generation des ondes internes non-lineaires par la maree en presence du talus continental ainsi que leur propagation. L'originalite de ce travail reside dans la generation d'ondes internes tridimensionnelles ainsi que dans la prise en compte des effets de la rotation sur le mecanisme de generation et la propagation des ondes. Nous avons montre que seul le jusant engendre la maree interne sur le plateau et le talus. La rotation n'agit pas sur le mecanisme de generation mais sur la propagation des ondes, de plus elle en diminue l'amplitude et en augmente la vitesse de propagation.
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Alexis, Alain. « Etude geotechnique et sedimentologique de souilles et chenaux de la rade de lorient : contribution a la stabilite des sols immerges ». Nantes, 1987. http://www.theses.fr/1987NANT2033.
Texte intégralLivres sur le sujet "Magee mechanism"
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Ritner, Robert Kriech. The Mechanics of Ancient Egyptian Magical Practice. Chicago, Ill : Oriental Institute of University of Chicago, 1993.
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Harnois, Devin. Mages & Mechanisms. CreateSpace Independent Publishing Platform, 2018.
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Mostafaei, Hossein. Axial-shear-flexure interaction approach for displacement-based evaluation of reinforced concrete elements = : Mage-sendan jukuryoku sōgo sayō moderu ni yoru tekkin konkurīto buzai no henkei seinō hyōka. 2006.
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Fleisch, Daniel. A Student's Guide to Maxwell's Equations. Cambridge University Press, 2008.
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Fleisch, Daniel. Student's Guide to Maxwell's Equations. Cambridge University Press, 2012.
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A Student's Guide to Maxwell's Equations. Cambridge University Press, 2008.
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Fleisch, Daniel. Student's Guide to Maxwell's Equations. Cambridge University Press, 2008.
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A Student's Guide to Maxwell's Equations. Cambridge University Press, 2008.
Trouver le texte intégralChapitres de livres sur le sujet "Magee mechanism"
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Wyle, F. A., K. J. Chang et A. Tarnawski. « Helicobacter pylori : pathogenetische Mechanismen ». Dans Der Magen, 217–31. Berlin, Heidelberg : Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-662-06526-6_14.
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Kiili, Kristian, Kai Ojansuu, Antero Lindstedt et Manuel Ninaus. « Exploring the Educational Potential of a Game-Based Math Competition ». Dans Research Anthology on Developments in Gamification and Game-Based Learning, 1173–89. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3710-0.ch054.
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The main aim of this article was to investigate the educational potential of a game-based math game competition to engage students in training rational numbers. Finnish fourth (n = 59; Mage = 10.36) and sixth graders (n = 105; Mage = 12.34) participated in a math game competition relying on intra-classroom cooperation and inter-classroom competition. During a three-week period, the students were allowed to play a digital rational number game, which is founded on number line estimation task mechanics. The results indicated that students benefited significantly from participating in the competition and playing behaviour could be used to assess students rational number knowledge. Moreover, students were engaged in the competition and the results revealed that intrinsically motivating factors such as enjoyment and perceived learning gains predicted students' willingness to participate in math game competitions again. This article provides empirical support that educational game competition can be an effective, engaging, and a fair instructional approach.
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Senthilkumar, Dr S., Dr S. Rajasekar et Dr S. Jeyakumar. « AN ERGONOMICS FOR PHOTOGRAPHERS WITH PREVENTION OF MUSCULOSKELETAL DISORDERS ». Dans Futuristic Trends in Medical Sciences Volume 3 Book 13, 30–37. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bdms13p1ch3.
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Photography is a visually captivating profession that requires photographers to spend extended periods in physically demanding positions. The repetitive and prolonged movements involved in capturing mages can lead to musculoskeletal disorders (MSDs) if proper ergonomic practices are not followed. This article aims to provide an overview of ergonomics for photographers and the prevention of MSDs. The key focus of ergonomics for photographers is to optimize body posture, reduce physical strain, and minimize the risk of injury. This can be achieved through various measures such as maintaining proper body alignment, using well-designed camera equipment, and creating an ergonomic workspace. Proper body alignment involves maintaining a neutral posture while shooting, avoiding excessive bending or twisting of the spine, and distributing weight evenly. Using a camera grip that fits comfortably in the hand and a padded camera strap can help reduce strain on the wrists and shoulders. Camera bags and backpacks should be designed to distribute weight evenly across the body, preventing excessive strain on specific muscle groups. Tripods with adjustable legs and quick-release mechanisms contribute to a more comfortable shooting experience. In the editing phase, photographers should pay attention to their workstation setup. A well-adjusted chair with good lumbar support and a desk at an appropriate height can help prevent neck, back, and wrist pain. Additionally, proper monitor placement, adequate lighting, and glare reduction techniques are essential to minimize eye strain and fatigue. Taking regular breaks, incorporating stretching exercises, and maintaining overall physical fitness are important aspects of preventing MSDs. Conditioning exercises that target muscles commonly used in photography, such as the core, shoulders, and wrists, can help build strength and flexibility. By implementing these ergonomic principles, photographers can reduce the risk of developing MSDs and promote a healthier and more sustainable working environment. It is crucial for photographers to prioritize their well-being and take proactive measures to prevent occupational injuries.
Actes de conférences sur le sujet "Magee mechanism"
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Xuemei, Niu, Gao Guoqin, Liu Xinjun et Bao Zhida. « Sliding Mode Control for a Novel 3-DOF Parallel Mechanism ». Dans 2013 International Conference on Mechanical and Automation Engineering (MAEE). IEEE, 2013. http://dx.doi.org/10.1109/maee.2013.56.
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Xi, Lihe, Hongwei Chen, Zhangbao Di et Xin Zhang. « Design and Analysis of HEV System Based on Ravigneaux Planetary Mechanism ». Dans 2013 International Conference on Mechanical and Automation Engineering (MAEE). IEEE, 2013. http://dx.doi.org/10.1109/maee.2013.16.
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Hadi, NSA, EE Bankoglu, O. Kelber, H. Sievers et H. Stopper. « Studies on mechanism of genotoxicity of selected pyrrolizidine alkaloids in HepG2 cells in vitro ». Dans Jubiläumskongress Phytotherapie 2021 Leib und Magen – Arzneipflanzen in der Gastroenterologie 50 Jahre Gesellschaft für Phytotherapie. Georg Thieme Verlag KG, 2021. http://dx.doi.org/10.1055/s-0041-1731499.
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Thomson, Barbara A., et Norman J. Armendariz. « X-ray Laminography Benchmarking and Failure Analysis of Solder Joint Interfaces ». Dans ISTFA 2003. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.istfa2003p0120.
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Abstract A new generation X-ray laminography (XRL) automated Xray inspection (AXI) tool was evaluated for surface mount technology (SMT) assembly defect detection and was qualified using formal “benchmark” comparative analysis processes. In addition, defect characterization was performed using the XRL AXI system in manual X-ray inspection mode to correlate various failure modes and mechanisms at SMT solder joint interfaces for selected non-destructive failure analyses and technology development. Since ball grid array (BGA) solder joint quality is a great concern in board assembly, test technology development and failure analysis teams explored the use of XRL AXI as a method to detect and monitor BGA ball abnormalities using XRL AXI-generated solder ball images and measurements. It was found that XRL AXI was able to successfully discern differences in the shape, location and diameter of the suspect BGA solder balls from XRL AXI horizontal image planes (slices) for physical failure analysis and reliability issues not previously detected using conventional X-ray transmission or electrical methods. Subsequent metallographic x-sectioning correlated the XRL AXI mages to the physical condition of the suspected second level interconnect (SLI) solder joint location.
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Berinšterová, Marianna, Miroslava Bozogáňová et Tatiana Pethö. « COPING ORIENTATION AND PROCRASTINATION AMONG MEN AND WOMEN ». Dans PSYCHOLÓGIA PRÁCE A ORGANIZÁCIE 2023. Vydavateľstvo ŠafárikPress, Univerzita Pavla Jozefa Šafárika v Košiciach, 2023. http://dx.doi.org/10.33542/ppo-0265-7-01.
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Procrastination is a dysfunctional behaviour with an impact not only on academic performance but also on job satisfaction and performance. It mainly affects the adult population and is linked to the level of autonomy. Previous research has also shown gender differences in procrastination and the association of the trait of introversion with procrastinating behaviour in women. The aim of this research is to examine the relationship between procrastination and coping strategies among men and women, as well as to explore which coping strategies predict the level of procrastination. A total of 252 undergraduate students (161 females; Mage=21.05, SD=1. 850) participated in the study. Coping strategies were monitored through the Brief Cope, personality traits through the BFI 2. Data were processed by Pearson's correlation coefficient and linear regression. It was found that procrastination was associated with problem focus coping among women but not among men. Also, facets of coping styles - active coping, positive reframing, planning, emotional support and acceptance were negatively associated to the level of procrastination among women. Linear regression model also confirm the relationship of the coping strategy of planning and the lower level of extroversion as a predictors of procrastination among woman. The results suggest a different mechanism of procrastination in men and women. Coping strategies that are differently associated with procrastination in women than in men are susceptible to change. In the context of higher education, career preparation, career counseling, training of planning competence can act as a prevention against dysfunctional procrastination.
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Falco, Caitlin, et Allison Looby. « Differential effects of urgency and sensation seeking on cannabis use and related problems via motives ». Dans 2021 Virtual Scientific Meeting of the Research Society on Marijuana. Research Society on Marijuana, 2022. http://dx.doi.org/10.26828/cannabis.2022.01.000.29.
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A reliable predictor of substance use is impulsivity, a multidimensional construct in which specific facets demonstrate differential associations with aspects of substance use. Though research has delineated the association between substance use and impulsivity generally, work examining facets and their relation to cannabis use specifically is more limited. Additionally, motivational models of substance use suggest that an individual’s reasons for use are the most proximal predictors of substance use, serving as a mediating mechanism by which other variables operate to influence use and related behaviors. To obtain a more comprehensive understanding of the mechanisms underlying cannabis use, the current study assessed the relation between three facets of impulsivity that have demonstrated compelling associations with cannabis (i.e., positive urgency, negative urgency; and sensation seeking) and their association with frequency of cannabis use and related consequences via motives. College students (N = 652, Mage = 19.59, 72.2% female) from seven universities that reported past-month cannabis use completed an online survey assessing frequency of past-month cannabis use, number of related problems, facets of impulsivity, and cannabis use motives. A bootstrapped path analysis was conducted, in which negative urgency, positive urgency, and sensation seeking were modeled as simultaneous predictors of past-month cannabis-related problems via parallel mediators of enjoyment, coping, and social anxiety motives, and via past-month days of cannabis use. Positive and negative urgency were significant mediators in the same pathways: 1) social anxiety motives positively mediated the association between urgency and frequency of past-month cannabis use (negative urgency: β=0.37, 95% CI [0.046, 0.86]; positive urgency: β=0.87, 95% CI [0.44, 1.43]); 2) coping motives positively mediated the association between urgency and cannabis-related problems (negative urgency: β=0.47, 95% CI [0.28, 0.71]; positive urgency: β=0.31, 95% CI [0.11, 0.55]; and 3) a serial mediation effect such that urgency was positively associated with anxiety motives, which in turn were associated with higher frequency of past-month use, which was associated with greater cannabis-related problems (negative urgency: β=0.05, 95% CI [0.01, 0.12]; positive urgency: β=0.12, 95% CI [0.06, 0.21]). Further, two indirect effects were found for sensation seeking: 1) enjoyment motives positively mediated the association between sensation seeking and frequency of past-month use (β=0.23, 95% CI [0.40, 0.53]); and 2) a serial mediation effect such that sensation seeking was positively associated with enjoyment motives, which in turn were associated with higher frequency of past-month use, which in turn was associated with greater cannabis-related problems (β=0.03, 95% CI [0.005, 0.01]). Results appear to suggest that individuals high in urgency using to avoid or cope with negative affect or social anxiety and individuals high in sensation seeking endorsing use to feel good or enhance mood may be at greater risk of cannabis-related problems, providing evidence that cannabis use a means of improving emotional experience may not be an adequate emotion regulation strategy.
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Wallace, Elliot, Tessa Frohe et Jason Ramirez. « The Relationship Between Mental Health Symptoms and marijuana consequences mediated by coping motives for marijuana use ». Dans 2021 Virtual Scientific Meeting of the Research Society on Marijuana. Research Society on Marijuana, 2022. http://dx.doi.org/10.26828/cannabis.2022.01.000.21.
Texte intégralRésumé :
As marijuana continues to be legalized across the United States, it is imperative to investigate risk factors and consequences related to use. Previous studies among adult samples have found that mental health symptoms, including both depression and anxiety symptoms, are significant predictors of increased frequency of marijuana use. Little is known however regarding mental health symptoms and marijuana use among adolescents. This risk is particularly salient for adolescents given that many mental health disorders, like depression and anxiety, begin to emerge during this developmental period, and because earlier of age of marijuana use onset is associated with worse prospective health outcomes. Further, coping motives for marijuana use (i.e., using marijuana as an external avoidance or escape-based strategy) may serve as a mechanism for some adolescents to avoid distressing anxiety and depressive states. To address this gap in research, the aims of the current analysis were to 1) examine associations between mental health symptoms, marijuana use, and consequences among adolescents, and 2) examine coping motives as a mediator between mental health symptoms and marijuana outcomes. The current study included 107 late adolescents (15-18 years old, Mage = 17.01, SDage = 0.92, 51% female, 85% White/Caucasian, 60% high school student, 27% college student) recruited from Washington State. The sample was stratified by gender and marijuana use such that participants ranged from reporting infrequent to daily marijuana use. Participants were asked to complete three online assessments across six months. These included the PHQ-4, a 4-item measure of depression and anxiety symptoms in the past 2 weeks, in addition to measures of marijuana use, marijuana-related consequences, and marijuana use motives. We conducted two separate mediator models to examine if baseline mental health symptoms were mediated by coping motives at month 3 on (1) marijuana use and (2) marijuana-related consequences both reported at month 6. There was no significant mediation effect for baseline mental health symptoms predicting overall marijuana use at month 6 (B = .27, SE = .25, 95% CI [-.23, .76], p = .28). For the second model, motives at month 3 fully mediated the relationship between mental health symptoms at baseline and marijuana-related consequences at month 6 (B = .71, SE = .27, 95% CI [.17, 1.24], p ≤ .01). Thus, higher levels of mental health symptoms at baseline were associated with higher marijuana-related consequences as mediated by coping motives reported at month 3. Our results suggest that adolescents who experience more mental health symptoms do not use marijuana more than others who report fewer symptoms. However, these individuals may be at greater risk for experiencing negative consequences that result from their use. Further, results also suggest that the relationship between mental health symptoms and negative consequences may be largely accounted for by stronger motives to use marijuana to cope with mental health. Screening for mental health symptoms during adolescence may be beneficial in preventing negative outcomes by providing early interventions for healthy coping strategies for anxiety and depression.