Mikrosystemtechnisch integriertes, optisch gepumptes Magnetometer

Die vorliegende Arbeit beinhaltet unterschiedliche Aspekte von Entwurf, Fertigung und Erforschung mikrofabrizierter Alkalidampfzellen. Alkalidampfzellen, also hermetisch versiegelte Volumina gefüllt mit Atomen eines Alkalimetalls, haben besondere Bedeutung als zentrales Element innerhalb von optisch gepumpten Magnetometern (OPM) sowie von kleinformatigen Frequenzstandards (bzw. Atomuhren). Moderne Entwicklungen in diesem Bereich gehen insbesondere zu einer Verringerung des Volumens bzw. der Größe der verwendeten Bauteile, da dies zum einen die bessere Integrierbarkeit der Sensoren gewährleistet und außerdem Probleme bei Messungen in inhomogenen Magnetfeldern (z.B. bei der Verwendung im Erdmagnetfeld) vermeidet bzw. beschränkt. Die Verringerung des Zellvolumens widerspricht jedoch gleichzeitig der Forderung an eine hohe Empfindlichkeit der Messung. Diesem aufkommenden Widerspruch zum einen, sowie dem mikrosystemtechnischen Fertigungsprozess der Zellen zum anderen ist diese Arbeit gewidmet. Hinsichtlich des Fertigungsprozesses werden Entwicklungen für die Handhabung des hier verwendeten, hochreaktiven Cäsiums sowie die Möglichkeit zur Passivierung des Zellkörpers mit dünnen Schichten aus Al2O3 , abgeschieden mittels Atomlagenabscheidung, gegen den Einfluss des verwendeten Cäsiums vorgestellt. Hervorzuheben ist eine für den hermetischen Zellverschluss entwickelte Methode, welche anodisches Bonden bei Raumtemperatur und Spannungen im Bereich von 100V erlaubt. Diese einzigartige Parameterkombination wird durch die Verwendung dünner Schichten eines lithiumhaltigen Glases mit hoher Ionenleitfähigkeit ermöglicht. Das Ergebnis dieser Arbeit besteht in einem Array aus mehreren Alkalidampfzellen, welche über Kanäle mit einer zentralen Struktur, dem Reservoir, verbunden sind. Das Reservoir dient der Aufnahme des Cäsiums. Der Aufbau des Arrays gewährleistet identische Eigenschaften bzw. Charakteristika der einzelnen Zellen. Insbesondere durch Anpassungen des verwendeten Puffergases sowie des in den Zellen herrschenden Puffergasdrucks konnte die erreichbare schrotrauschbegrenzte Empfindlichkeit der hergestellten Zellen auf Werte von ca. 150fT/ √ Hz gesteigert werden. Bringt man diesen Wert in Relation zum Zellvolumen von 50mm 3 ergibt sich für die Zellen ein Wert von 33,6 fTcm3/2 / √ Hz. Dieser stellt für Messungen im verwendeten Arbeitsregime international einen Spitzenwert dar.The present work includes different aspects of the design, fabrication and research of microfabricated atomic vapor cells. Atomic vapor cells, corresponding to hermetically sealed volumes filled with atoms of the alkali metals, have a special importance as the central element of optically pumped magnetometers (OPM) and for small frequency standards (atomic clocks respectively). Modern developments in optical magnetometry are pointing in particular to a reduction of the size and volume of the devices used. The objective of this is to achieve a better integrability of the sensors but also to prevent problems, connected with measuring in inhomogeneous magnetic fields (for instance during the application of the sensor in the earth’s magnetic field). The reduction of the cell volume counters the demand on a high resolution of the measurement, however. This work is devoted to the mentioned contradiction of using atomic vapor cells with reduced volumes on the one hand and to the fabrication process of those cells based on microsystem technology on the other. With regards to the fabrication process a new development for the handling of the highly reactive alkali metal (cesium) is presented. To prevent bothering interactions of the cesium with the cell’s body, a technique to passivate the cell walls with ultra-thin layers of Al2O3 , deposit by atomic layer deposition, is introduced. Special emphasis should be placed on a method to seal the vapor cells hermetically with an adapted anodic bonding process, carried out at room temperature and with voltages of about 100V. This unique combination in the process parameters is enabled by the application of thin, highly ion-conductive, lithium containing glass layers. The final result of this work is an array of several atomic vapor cells, connected via canals to a central structure. This so-called reservoir is used to gather the metallic cesium. The structure of this setup guarantees identical characteristics of each cell during the measurements. By adjustments of the type and especially the pressure of the buffer gas used, the shot-noise-limited sensitivity of the cells fabricated here was enhanced to values of about 150fT/ √ Hz. In relation to the cell’s volume of 50mm3 it follows a sensitivity of about 33.6 fTcm3/2 / √ Hz. With regard to the used working regime this is a peak value compared with values published to date

An optically pumped magnetometer working in the light-shift dispersed Mz mode

We present an optically pumped magnetometer working in a new operational mode— the light-shift dispersed Mz (LSD-Mz) mode. It is realized combining various features; (1) high power off-resonant optical pumping; (2) Mz configuration, where pumping light and magnetic field of interest are oriented parallel to each other; (3) use of small alkali metal vapor cells of identical properties in integrated array structures, where two such cells are pumped by circularly polarized light of opposite helicity; and (4) subtraction of the Mz signals of these two cells. The LSD-Mz magnetometer’s performance depends on the inherent and very complex interplay of input parameters. In order to find the configuration of optimal magnetometer resolution, a sensitivity analysis of the input parameters by means of Latin Hypercube Sampling was carried out. The resulting datasets of the multi-dimensional parameter space exploration were assessed by a subsequent physically reasonable interpretation. Finally, the best shot-noise limited magnetic field resolution was determined within that parameter space. As the result, using two 50 mm3 integrated vapor cells a magnetic field resolution below 10 fT/√Hz at Earth’s magnetic field strength is possible

Dissection of PIM serine/threonine kinases in FLT3-ITD–induced leukemogenesis reveals PIM1 as regulator of CXCL12–CXCR4-mediated homing and migration

FLT3-ITD–mediated leukemogenesis is associated with increased expression of oncogenic PIM serine/threonine kinases. To dissect their role in FLT3-ITD–mediated transformation, we performed bone marrow reconstitution assays. Unexpectedly, FLT3-ITD cells deficient for PIM1 failed to reconstitute lethally irradiated recipients, whereas lack of PIM2 induction did not interfere with FLT3-ITD–induced disease. PIM1-deficient bone marrow showed defects in homing and migration and displayed decreased surface CXCR4 expression and impaired CXCL12–CXCR4 signaling. Through small interfering RNA–mediated knockdown, chemical inhibition, expression of a dominant-negative mutant, and/or reexpression in knockout cells, we found PIM1 activity to be essential for proper CXCR4 surface expression and migration of cells toward a CXCL12 gradient. Purified PIM1 led to the phosphorylation of serine 339 in the CXCR4 intracellular domain in vitro, a site known to be essential for normal receptor recycling. In primary leukemic blasts, high levels of surface CXCR4 were associated with increased PIM1 expression, and this could be significantly reduced by a small molecule PIM inhibitor in some patients. Our data suggest that PIM1 activity is important for homing and migration of hematopoietic cells through modification of CXCR4. Because CXCR4 also regulates homing and maintenance of cancer stem cells, PIM1 inhibitors may exert their antitumor effects in part by interfering with interactions with the microenvironment

Arabis alpina: A perennial model plant for ecological genomics and life-history evolution

Many model organisms were chosen and achieved prominence because of an advantageous combination of their life-history characteristics, genetic properties and also practical considerations. Discoveries made in Arabidopsis thaliana, the most renowned noncrop plant model species, have markedly stimulated studies in other species with different biology. Within the family Brassicaceae, the arctic-alpine Arabis alpina has become a model complementary to Arabidopsis thaliana to study the evolution of life-history traits, such as perenniality, and ecological genomics in harsh environments. In this review, we provide an overview of the properties that facilitated the rapid emergence of A. alpina as a plant model. We summarize the evolutionary history of A. alpina, including genomic aspects, the diversification of its mating system and demographic properties, and we discuss recent progress in the molecular dissection of developmental traits that are related to its perennial life history and environmental adaptation. From this published knowledge, we derive open questions that might inspire future research in A. alpina, other Brassicaceae species or more distantly related plant families

S1

Gapped alignment of 40553 positions in length used to produce the OV alignmen

Data from: The evolutionary root of flowering plants

Correct rooting of the angiosperm radiation is both challenging and necessary for understanding the origins and evolution of physiological and phenotypic traits in flowering plants. The problem is known to be difficult due to the large genetic distance separating flowering plants from other seed plants and the sparse taxon sampling among basal angiosperms. Here we provide further evidence for concern over substitution model misspecification in analyses of chloroplast DNA sequences. We show that support for Amborella as the sole representative of the most basal angiosperm lineage is founded on sequence site patterns poorly described by time reversible substitution models. Improving the fit between sequence data and substitution model identifies Trithuria, Nymphaeales and Amborella as surviving relatives of the most basal lineage of flowering plants. This finding indicates that aquatic and herbaceous species dominate the earliest extant lineage of flowering plants

S4 - S4.txt

31674 positions long alignment, maintaining the reading fram

S6 - S6.zip

zip archive containing scripts used in the pape

S2 - S2.txt

alignment of first and the second codon positions 25246 positions in lengt