498 research outputs found

    A model of the crustal magnetic field of Mars

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    Das Magnetfeld des Mars hat seinen Ursprung v.a. in der remanenten Magnetisierung seiner Kruste und besitzt heute kein globales Dipolfeld mehr. In dieser Arbeit werden Magnetfeldmessungen des Satelliten "Mars Global Surveyor" (MGS) benutzt, um ein robustes und hochauflösendes Modell dieses Krustenfeldes abzuleiten. Dies wurde durch die Annäherung einer L1-Norm zur Regularisierung, einer robusten Norm zur Inversion, der Berücksichtigung externer Felder, sowie einer genauen Analyse und Gewichtung aller vorhandenen MGS-Magnetfelddaten erreicht. Das resultierende Modell kann zur Beantwortung offener Fragen der Evolution des Mars beitragen. Exemplarisch wurden dazu das Krustenfeld von Vulkanen und Impaktkratern analysiert, um Rückschlüsse auf den Zeitpunkt eines aktiven Kerndynamos zu schliessen. Darüber hinaus wird ein Modell der benötigten Krustenmagnetisierung vorgestellt sowie auf isolierte Anomalien eingegangen, die bei der Bestimmung von magnetischen Paleopolen eine Rolle spielen.The main source of the Martian magnetic field is of crustal origin, and Mars does not possess an internal core dynamo as of today. In this thesis, we use magnetic field data as obtained by the satellite "Mars Global Surveyor" (MGS) in order to derive a robust model of the crustal magnetic field of Mars with high resolution. For this purpose, we use an approximation to an L1 norm for regularization, a robust norm for data inversion, an external field model, and a precise analysis and weighting of all available MGS magnetic field data. The resulting model may contribute to answer open questions related to the evolution of Mars. Here, we exemplarily analyze the crustal magnetic field of volcanoes and impact craters, and this analysis is used to conclude on the timing of an ancient Martian core dynamo. Further, we present a model of the necessary magnetization of the Martian crust, and we comment on some isolated anomalies that are required to calculate magnetic paleopole positions.<br

    Effects of a dominant species on the functional diversity of coexisting species in temperate deciduous understorey

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    The herb layer plays a significant role in maintaining forest functions, and its community composition is determined by various abiotic factors and biotic interactions. This study attempted to investigate the interspecific plant–plant biotic interactions using a functional traits approach. Specifically, the effects of a dominant species coverage on the functional diversity of coexisting species in the temperate forest understory were studied. Species coverage and soil moisture data were collected using a 1 m2 quadrat couplet (2 × 1 m2) from six sites alongside a 20 m linear transect encompassing a cover gradient of Allium ursinum in southwest Hungary. Major plant functional dimensions i.e., aboveground, and clonal functional traits were considered. Linear and nonlinear mixed models to quantify the effects of biotic interaction on the functional diversity of every single trait and multiple traits were employed. Both aboveground traits and clonal traits of persistent clonal growth organs responded positively to the A. ursinum L., cover gradient. The coexistence of understory species in the presence of a monodominant species seems to be mainly influenced by aboveground traits as compared to the clonal traits suggesting, a role of niche differentiation. The consistent impact of A. ursinum coverage on coexisting species dynamics highlights a need for similar in-depth studies in various forest settings

    Controversies in the Treatment of Peripheral T-cell Lymphoma.

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    Peripheral T-cell lymphomas are a heterogeneous group of rare diseases with an aggressive behavior and dismal prognosis. Their classification is complex and still evolving, and several biomolecular markers now help refine the prognosis of specific disease entities, although still have limited impact in tailoring the treatment. First-line treatment strategies can cure only a minority of patients and relapsed-refractory disease still represents the major cause of failure. Frontline autologous transplantation may have an impact in the consolidation of response; however, its role is still questioned as far as complete responses obtained after induction chemotherapy are concerned. Newer drugs are now being evaluated in clinical trials, but effective salvage strategies for those who experience treatment failures are lacking. Here we review and discuss the most controversial aspects of diagnosis and treatment of peripheral T-cell lymphomas

    A low-power data acquisition system for geomagnetic observatories and variometer stations

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    A modern geomagnetic observatory must provide data of high stability, continuity, and resolution. The INTERMAGNET network has therefore specified quantitative criteria to ensure a high quality standard of geomagnetic observatories. Here, we present a new data acquisition system which was designed to meet these criteria, in particular with respect to 1 Hz data. This system is based on a Raspberry Pi embedded PC and runs a C+ +  data acquisition software. As a result, the data acquisition system is modular, cheap, and flexible, and it can be operated in remote areas with limited power supply. In addition, the system is capable of near-real-time data transmission, using a reverse SSH tunnel to work with any network available. The system hardware was successfully tested at the Niemegk observatory for a period of 1 year and subsequently installed at the Tatuoca observatory in Brazil

    Targeting intratumoral B cells with rituximab in addition to CHOP in angioimmunoblastic T-cell lymphoma. A clinicobiological study of the GELA.

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    Background In angioimmunoblastic T-cell lymphoma, symptoms linked to B-lymphocyte activation are common, and variable numbers of CD20(+) large B-blasts, often infected by Epstein-Barr virus, are found in tumor tissues. We postulated that the disruption of putative B-T interactions and/or depletion of the Epstein-Barr virus reservoir by an anti-CD20 monoclonal antibody (rituximab) could improve the clinical outcome produced by conventional chemotherapy. DESIGN AND METHODS: Twenty-five newly diagnosed patients were treated, in a phase II study, with eight cycles of rituximab + chemotherapy (R-CHOP21). Tumor infiltration, B-blasts and Epstein-Barr virus status in tumor tissue and peripheral blood were fully characterized at diagnosis and were correlated with clinical outcome. RESULTS: A complete response rate of 44% (95% CI, 24% to 65%) was observed. With a median follow-up of 24 months, the 2-year progression-free survival rate was 42% (95% CI, 22% to 61%) and overall survival rate was 62% (95% CI, 40% to 78%). The presence of Epstein-Barr virus DNA in peripheral blood mononuclear cells (14/21 patients) correlated with Epstein-Barr virus score in lymph nodes (P&lt;0.004) and the detection of circulating tumor cells (P=0.0019). Despite peripheral Epstein-Barr virus clearance after treatment, the viral load at diagnosis (&gt;100 copy/μg DNA) was associated with shorter progression-free survival (P=0.06). Conclusions We report here the results of the first clinical trial targeting both the neoplastic T cells and the microenvironment-associated CD20(+) B lymphocytes in angioimmunoblastic T-cell lymphoma, showing no clear benefit of adding rituximab to conventional chemotherapy. A strong relationship, not previously described, between circulating Epstein-Barr virus and circulating tumor cells is highlighted

    State-of-the-Art Management of Patients Suffering from Chronic Lymphocytic Leukemia

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    The management of chronic lymphocytic leukemia (CLL) has evolved dramatically in the last decade. For the first time, clinical intervention has been shown to alter the natural history of the disease. Considerable efforts are focussing on better patient selection and response prediction, and it is expected that the publication of the first 200 CLL genomes will spark new insights into risk stratification of CLL patients. Besides, many new agents are being evaluated on their own and in combination therapy in early and late Phase clinical studies. Here, we provide a general clinical introduction into CLL including diagnosis and prognostic markers followed by a summary of the current state-of-the-art treatment. We point to areas of continued clinical research in particular for patients with co-morbidities and highlight the challenges in managing refractory disease

    The Emerging Role of Ofatumumab in the Treatment of Chronic Lymphocytic Leukemia

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    The treatment of chronic lymphocytic leukemia (CLL) has evolved over the past decade. Our better understanding of disease biology and risk stratification has allowed delivering more effective therapies. In fact, front-line chemoimmunotherapy has demonstrated improvement in overall survival when compared to chemotherapy in randomized studies. Yet, treatment of relapsed CLL remains challenging and few agents are effective in that setting. Ofatumumab (Ofa) is a humanized monoclonal antibody targeted against CD20 with demonstrable activity in rituximab-resistant CLL cell lines. This agent was recently approved for the treatment of relapsed/refractory CLL patients who have failed fludarabine and alemtuzumab. In this review, we provide a historical perspective on approaches to CLL as front-line and in the relapsed setting. We further summarize novel anti-CD20 antibodies with specific emphasis on ofa. We review studies that led to ofatumumab’s approval including pre-clinical data, trials using ofa in combination therapies, and adverse events/toxicities reported with this agent

    Plain language summary of the TRANSFORM study primary analysis results:liso-cell as a second treatment regimen for large B-cell lymphoma following failure of the first treatment regimen

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    What is this summary about?People diagnosed with a disease called large B-cell lymphoma (LBCL) may experience return, or early relapse, of their disease within the first year after receiving and responding to their first (first-line) treatment regimen. Others may have primary refractory disease, meaning that the disease either did not respond to first-line treatment at all or only responded for a very brief period. Second (second-line) treatment includes immunotherapy followed by high-dose chemotherapy and ASCT, which has the potential to cure LBCL. However, if the disease does not respond to immunotherapy, people cannot receive ASCT, and less than 30% of people are cured.Therefore, new second-line treatment options are required, such as CAR T cell therapy, which uses a person's own genetically engineered lymphocytes, also called T cells, to fight their lymphoma. In this article, we summarize the key results of the phase 3 TRANSFORM clinical study that tested if liso-cel, a CAR T cell treatment, can safely and effectively be used as a second-line treatment for people with early relapsed or primary refractory (relapsed/refractory) LBCL.A total of 184 adults with relapsed/refractory LBCL who were able to receive ASCT were randomly treated with either liso-cel or standard of care (SOC) as second-line treatment. SOC included immunochemotherapy followed by high-dose chemotherapy and ASCT.What were the key takeaways?Almost all (97%) people in the liso-cel group completed treatment, whereas 53% of people in the SOC group did not complete treatment, mostly due to their disease not responding or relapsing, and therefore they were not able to receive ASCT. People who received liso-cel as a second-line treatment lived longer without the occurrence of an unfavorable medical event or worsening of the disease and had a better response to treatment than those who received SOC as second-line treatment. People who received liso-cel reported side effects that researchers considered to be manageable, and that were known to occur with CAR T cell treatment.What were the main conclusions reported by the researchers?Results from the TRANSFORM study support the use of liso-cel as a more effective second-line treatment compared with SOC that is safe for people with relapsed/refractory LBCL
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