7,069 research outputs found
Adaptive dynamic control of a wind generator
The main aim of the present project is to obtain a better understanding of the dynamic control of a wind turbine. To accomplish this, an adaptive dynamic controller was developed and connected to a wind DFIG Simulink model. In order to demonstrate the effectiveness of the controller in question, a three phase fault in the power grid was simulated. Results showed how the implementation of the adaptive dynamic programming controller helped to improve the speed of response of the system. It also helped to reduce the magnitude of the oscillations taking place after the disturbance is removed. The non-linear systems are difficult to model and to control. New modern control techniques allow controlling these systems without having the system model, reducing the complexity. Among these techniques, it is the adaptive dynamic control that estimates the parameters of the dynamic system on-line and adapts their control to the new conditions without spreading the error throughout a feedback network
El cuestionario de actitudes hacia la igualdad de géneros (CAIG): elaboración y estudio psicométrico.
De Sola Dominguez, Maria Amelia [email protected] Melia Navarro, Jose Luis - [email protected] trabajo describe el desarrollo y análisis psicométrico de un nuevo cuestionario para la medida de las actitudes hacia la igualdad de géneros. Incluye la descripción del cuestionario, su proceso de elaboración
y su estructura factorial, asĂ como los resultados de los análisis de fiabilidad y validez realizados. Finalmente, se adjunta el texto de los treinta Ătems que componen la escala
Distinction between asymptomatic monoclonal B-cell lymphocytosis with cyclin D1 overexpression and mantle cell lymphoma: from molecular profiling to flow cytometry
PMCID: PMC4488901.-- et al.[Purpose]: According to current diagnostic criteria, mantle cell lymphoma (MCL) encompasses the usual, aggressive variants and rare, nonnodal cases with monoclonal asymptomatic lymphocytosis, cyclin D1- positive (MALD1). We aimed to understand the biology behind this clinical heterogeneity and to identify markers for adequate identification of MALD1 cases. [Experimental Design]: We compared 17 typical MCL cases with a homogeneous group of 13 untreated MALD1 cases (median follow-up, 71 months). We conducted gene expression profiling with functional analysis in five MCL and five MALD1. Results were validated in 12 MCL and 8 MALD1 additional cases by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and in 24MCLand 13MALD1 cases by flow cytometry. Classification and regression trees strategy was used to generate an algorithm based on CD38 and CD200 expression by flow cytometry. [Results]: We found 171 differentially expressed genes with enrichment of neoplastic behavior and cell proliferation signatures in MCL. Conversely, MALD1 was enriched in gene sets related to immune activation and inflammatory responses. CD38 and CD200 were differentially expressed betweenMCLandMALD1and confirmed by flow cytometry (median CD38, 89% vs. 14%; median CD200, 0% vs. 24%, respectively). Assessment of both proteins allowed classifying 85% (11 of 13) of MALD1 cases whereas 15% remained unclassified. SOX11 expression by qRT-PCR was significantly different between MCL and MALD1 groups but did not improve the classification. [Conclusion]: We show for the first time that MALD1, in contrast to MCL, is characterized by immune activation and driven by inflammatory cues. Assessment of CD38/CD200 by flow cytometry is useful to distinguish most cases of MALD1 from MCL in the clinical setting. MALD1 should be identified and segregated from the current MCL category to avoid overdiagnosis and unnecessary treatment.This work has been supported, in part, by grants from Instituto de Salud Carlos III RD07/0020/2004, RD09/0076/00036, RD12/0036/0044, (RTICC, FEDER), Generalitat de Catalunya 2009/SGR541, and the “Xarxa de Bancs de Tumors” sponsored by Pla Director d'Oncologia de Catalunya (XBTC).Peer Reviewe
The transcription factor Foxo1 controls germinal center B cell proliferation in response to T cell help
Germinal center (GC) B cells cycle between two states, the light zone (LZ) and the dark zone (DZ), and in the latter they proliferate and hypermutate their immunoglobulin genes. How this functional transition takes place is still controversial. In this study, we demonstrate that ablation of Foxo1 after GC development led to the loss of the DZ GC B cells and disruption of the GC architecture, which is consistent with recent studies. Mechanistically, even upon provision of adequate T cell help, Foxo1-deficient GC B cells showed less proliferative expansion than controls. Moreover, we found that the transcription factor BATF was transiently induced in LZ GC B cells in a Foxo1-dependent manner and that deletion of BATF similarly led to GC disruption. Thus, our results are consistent with a model where the switch from the LZ to the DZ is triggered after receipt of T cell help, and suggest that Foxo1-mediated BATF up-regulation is at least partly involved in this switch
Germinal Center Selection and Affinity Maturation Require Dynamic Regulation of mTORC1 Kinase
During antibody affinity maturation, germinal center (GC) B cells cycle between affinity-driven selection in the light zone (LZ) and proliferation and somatic hypermutation in the dark zone (DZ). Although selection of GC B cells is triggered by antigen-dependent signals delivered in the LZ, DZ proliferation occurs in the absence of such signals. We show that positive selection triggered by T cell help activates the mechanistic target of rapamycin complex 1 (mTORC1), which promotes the anabolic program that supports DZ proliferation. Blocking mTORC1 prior to growth prevented clonal expansion, whereas blockade after cells reached peak size had little to no effect. Conversely, constitutively active mTORC1 led to DZ enrichment but loss of competitiveness and impaired affinity maturation. Thus, mTORC1 activation is required for fueling B cells prior to DZ proliferation rather than for allowing cell-cycle progression itself and must be regulated dynamically during cyclic re-entry to ensure efficient affinity-based selection. During germinal center selection, signals from Tfh cells in the light zone dictate the extent of B cell proliferation in the dark zone. Ersching et al. (2017) show that Tfh help induces mTORC1 activation in light zone B cells, leading to cell growth that sustains the subsequent dark zone proliferative burst
Germinal Center Selection and Affinity Maturation Require Dynamic Regulation of mTORC1 Kinase
During antibody affinity maturation, germinal center (GC) B cells cycle between affinity-driven selection in the light zone (LZ) and proliferation and somatic hypermutation in the dark zone (DZ). Although selection of GC B cells is triggered by antigen-dependent signals delivered in the LZ, DZ proliferation occurs in the absence of such signals. We show that positive selection triggered by T cell help activates the mechanistic target of rapamycin complex 1 (mTORC1), which promotes the anabolic program that supports DZ proliferation. Blocking mTORC1 prior to growth prevented clonal expansion, whereas blockade after cells reached peak size had little to no effect. Conversely, constitutively active mTORC1 led to DZ enrichment but loss of competitiveness and impaired affinity maturation. Thus, mTORC1 activation is required for fueling B cells prior to DZ proliferation rather than for allowing cell-cycle progression itself and must be regulated dynamically during cyclic re-entry to ensure efficient affinity-based selection
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Combined Genetic Inactivation of b2-Microglobulin and CD58 Reveals Frequent Escape from Immune Recognition in Diffuse Large B Cell Lymphoma
We report that diffuse large B cell lymphoma (DLBCL) commonly fails to express cell-surface molecules necessary for the recognition of tumor cells by immune-effector cells. In 29% of cases, mutations and dele- tions inactivate the b2-Microglobulin gene, thus preventing the cell-surface expression of the HLA class-I (HLA-I) complex that is necessary for recognition by CD8+ cytotoxic T cells. In 21% of cases, analogous lesions involve the CD58 gene, which encodes a molecule involved in T and natural killer cell-mediated responses. In addition to gene inactivation, alternative mechanisms lead to aberrant expression of HLA-I and CD58 in >60% of DLBCL. These two events are significantly associated in this disease, suggesting that they are coselected during lymphomagenesis for their combined role in escape from immune-surveillance
“Breaking up is hard to do”: the formation and resolution of sister chromatid intertwines
The absolute necessity to resolve every intertwine between the two strands of the DNA double helix provides a massive challenge to the cellular processes that duplicate and segregate chromosomes. Although the overwhelming majority of intertwines between the parental DNA strands are resolved during DNA replication, there are numerous chromosomal contexts where some intertwining is maintained into mitosis. These mitotic sister chromatid intertwines (SCIs) can be found as; short regions of unreplicated DNA, fully replicated and intertwined sister chromatids—commonly referred to as DNA catenation—and as sister chromatid linkages generated by homologous recombination-associated processes. Several overlapping mechanisms, including intra-chromosomal compaction, topoisomerase action and Holliday junction resolvases, ensure that all SCIs are removed before they can prevent normal chromosome segregation. Here, I discuss why some DNA intertwines persist into mitosis and review our current knowledge of the SCI resolution mechanisms that are employed in both prokaryotes and eukaryotes, including how deregulating SCI formation during DNA replication or disrupting the resolution processes may contribute to aneuploidy in cancer
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