7 research outputs found
Instrumentation for an asteroid kinetic-impactor demonstration mission
For selecting instruments to fulfill the objectives of a mission to impact an asteroid, it is important to get an idea
of the effects of such an impact event. Therefore the expected crater and ejecta cloud have to be calculated. The
calculations need to take into consideration the properties of the asteroid as well as the impactor. The main objective of
the NEOTwIST mission is to transfer angular momentum by impacting the asteroid far from the rotation axis to change
the rotation period as well as observe the resulting ejecta cloud and possibly the crater. There are three different mission
concepts, the 1st includes only an impactor spacecraft, the 2nd adds a flyby subunit the 3rd one to two chasers. Due to
the fact that the three concepts have different mission objectives the instrumentation of the concepts are different
NEOTÏIST: A relatively Inexpensive Kinetic Impactor Demonstration Mission Concept
Mission concept: NEOTÏIST stands for Near-Earth Object Transfer of angular momentum (ÏâI) Spin Test, and is a concept for a kinetic impactor demonstration mission, which aims to change the spin rate of an asteroid by impacting it off-center (Drube et al. 2016, Engel et al. 2016). The change would be measured by means of lightcurve measurements with Earth-based telescopes. In contrast to most other kinetic impactor demonstration mission concepts, NEOTÏIST does not require a reconnaissance spacecraft to rendezvous with the target asteroid for orbit change and impact-effect measurements, and is therefore a relatively inexpensive alternative.
The NEOTÏIST mission would determine the efficiency of momentum transfer (the ÎČ-factor) during an impact, and help mature the technology required for a kinetic impactor mission, both of which are important precursor measures for a future space mission to deflect an asteroid by collisional means in an emergency impact hazard situation
Mutations in the WTX - gene are found in some high-grade microsatellite instable (MSI-H) colorectal cancers
Background: Genetically, colorectal cancers (CRCs) can be subdivided into tumors with chromosomal instability (CIN) or microsatellite instability (MSI). In both types of CRCs genes that are involved in the degradation of beta-CATENIN are frequently mutated. Whereas in CIN CRCs APC (Adenomatous Polyposis Coli) is affected in most cases, high grade MSI (MSI-H) CRCs frequently display mutations in various genes, like the APC-, AXIN2- or CTNNBI (beta-CATENIN) gene itself. Recently in Wilms tumors, WTX (Wilms tumor gene on the X-chromosome) was discovered as another gene involved in the destruction of beta-CATENIN. As the WTX-gene harbors a short T(6)-microsatellite in its N-terminal coding region, we hypothesized that frameshift-mutations might occur in MSI-H CRCs in the WTX gene, thus additionally contributing to the stabilization of beta-CATENIN in human CRCs. Methods: DNA was extracted from 632 formalin-fixed, paraffin-embedded metastatic CRCs (UICCIV) and analyzed for MSI-H by investigating the stability of the highly sensitive microsatellite markers BAT25 and BAT26 applying fluorescence capillary electrophoresis (FCE). Then, in the MSI-H cases, well described mutational hot spot regions from the APC-, AXIN2- and CTNNBI genes were analyzed for genomic alterations by didesoxy-sequencing while the WTX T(6)-microsatellite was analyzed by fragment analysis. Additionally, the PCR products of T(5)-repeats were subcloned and mutations were validated using didesoxy-sequencing. Furthermore, the KRAS and the BRAF proto-oncogenes were analyzed for the most common activating mutations applying pyro-sequencing. mRNA expression of WTX from MSI-H and MSS cases and a panel of colorectal cancer cell lines was investigated using reverse transcription (RT-) PCR and FCE. Results: In our cohort of 632 metastatic CRCs (UICCIV) we identified 41 MSI-H cases (6.5%). Two of the 41 MSI-H cases (4.8%) displayed a frameshift mutation in the T(6)-repeat resulting in a T(5) sequence. Only one case, a male patient, expressed the mutated WTX gene while being wild type for all other investigated genes. Conclusion: Mutations in the WTX-gene might compromise the function of the beta-CATENIN destruction complex in only a small fraction of MSI-H CRCs thus contributing to the process of carcinogenesis
SUSTAIN drilling at Surtsey volcano, Iceland, tracks hydrothermal and microbiological interactions in basalt 50 years after eruption
The 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative concretes (SUSTAIN) drilling project at Surtsey volcano, sponsored in part by the International Continental Scientific Drilling Program (ICDP), provides precise observations of the hydrothermal, geochemical, geomagnetic, and microbiological changes that have occurred in basaltic tephra and minor intrusions since explosive and effusive eruptions produced the oceanic island in 1963â1967. Two vertically cored boreholes, to 152 and 192âm below the surface, were drilled using filtered, UV-sterilized seawater circulating fluid to minimize microbial contamination. These cores parallel a 181âm core drilled in 1979. Introductory investigations indicate changes in material properties and whole-rock compositions over the past 38 years. A Surtsey subsurface observatory installed to 181âm in one vertical borehole holds incubation experiments that monitor in situ mineralogical and microbial alteration processes at 25â124ââC. A third cored borehole, inclined 55â in a 264â azimuthal direction to 354âm measured depth, provides further insights into eruption processes, including the presence of a diatreme that extends at least 100âm into the seafloor beneath the Surtur crater. The SUSTAIN project provides the first time-lapse drilling record into a very young oceanic basaltic volcano over a range of temperatures, 25â141ââC from 1979 to 2017, and subaerial and submarine hydrothermal fluid compositions. Rigorous procedures undertaken during the drilling operation protected the sensitive environment of the Surtsey Natural Preserve
Comprehensive genomic characterization defines human glioblastoma genes and core pathways
Human cancer cells typically harbour multiple chromosomal aberrations, nucleotide substitutions and epigenetic modifications that drive malignant transformation. The Cancer Genome Atlas ( TCGA) pilot project aims to assess the value of large- scale multi- dimensional analysis of these molecular characteristics in human cancer and to provide the data rapidly to the research community. Here we report the interim integrative analysis of DNA copy number, gene expression and DNA methylation aberrations in 206 glioblastomas - the most common type of primary adult brain cancer - and nucleotide sequence aberrations in 91 of the 206 glioblastomas. This analysis provides new insights into the roles of ERBB2, NF1 and TP53, uncovers frequent mutations of the phosphatidylinositol- 3- OH kinase regulatory subunit gene PIK3R1, and provides a network view of the pathways altered in the development of glioblastoma. Furthermore, integration of mutation, DNA methylation and clinical treatment data reveals a link between MGMT promoter methylation and a hypermutator phenotype consequent to mismatch repair deficiency in treated glioblastomas, an observation with potential clinical implications. Together, these findings establish the feasibility and power of TCGA, demonstrating that it can rapidly expand knowledge of the molecular basis of cancer