Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Population. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Search for gravitational waves from low mass compact binary coalescence in LIGO's sixth science run and Virgo's science runs 2 and 3

Abstract: We report on a search for gravitational waves from coalescing compact binaries using LIGO and Virgo observations between July 7, 2009, and October 20, 2010. We searched for signals from binaries with total mass between 2 and 25M(circle dot); this includes binary neutron stars, binary black holes, and binaries consisting of a black hole and neutron star. The detectors were sensitive to systems up to 40 Mpc distant for binary neutron stars, and further for higher mass systems. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass, including the results from previous LIGO and Virgo observations. The cumulative 90% confidence rate upper limits of the binary coalescence of binary neutron star, neutron star-black hole, and binary black hole systems are 1.3 x 10(-4), 3.1 x 10(-5), and 6.4 x 10(-6) Mpc(-3) yr(-1), respectively. These upper limits are up to a factor 1.4 lower than previously derived limits. We also report on results from a blind injection challenge.

Lymphoid cell growth and transformation are suppressed by a key regulatory element of the gene encoding PU.1

Abstract: Tight regulation of transcription factors, such as PU.1, is crucial for generation of all hematopoietic lineages. We previously reported that mice with a deletion of an upstream regulatory element (URE) of the gene encoding PU.1 (Sfpi1) developed acute myeloid leukemia. Here we show that the URE has an essential role in orchestrating the dynamic PU.1 expression pattern required for lymphoid development and tumor suppression. URE deletion ablated B2 cells but stimulated growth of B1 cells in mice. The URE was a PU.1 enhancer in B cells but a repressor in T cell precursors. TCF transcription factors coordinated this repressor function and linked PU.1 to Wnt signaling. Failure of appropriate PU.1 repression in T cell progenitors with URE deletion disrupted differentiation and induced thymic transformation. Genome-wide DNA methylation assessment showed that epigenetic silencing of selective tumor suppressor genes completed PU.1-initiated transformation of lymphoid progenitors with URE deletion. These results elucidate how a single transcription factor, PU.1, through the cell context-specific activity of a key cis-regulatory element, affects the development of multiple cell lineages and can induce cancer.

Taking atom interferometric quantum sensors from the laboratory to real-world applications

Abstract: Since the first proof-of-principle experiments over 25 years ago, atom interferometry has matured to a versatile tool that can be used in fundamental research in particle physics, general relativity and cosmology. At the same time, atom interferometers are currently moving out of the laboratory to be used as ultraprecise quantum sensors in metrology, geophysics, space, civil engineering, oil and minerals exploration, and navigation. This Perspective discusses the associated scientific and technological challenges and highlights recent advances. Quantum sensors based on atom interferometry are moving from fundamental research towards commercial applications in metrology, geophysics, space, civil engineering, oil and minerals exploration, and navigation, but a number of challenges need to be overcome.