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Subsampling Mathematical Relaxations and Average-case Complexity
(2010)arXivWe initiate a study of when the value of mathematical relaxations such as linear and semidefinite programs for constraint satisfaction problems (CSPs) is approximately preserved when restricting the instance to a sub-instance induced by a small random subsample of the variables. Let $C$ be a family of CSPs such as 3SAT, Max-Cut, etc., and let $\Pi$ be a relaxation for $C$, in the sense that for every instance $P\in C$, $\Pi(P)$ is an upper ...Working Paper -
First results from the GPS atmosphere sounding experiment TOR aboard the TerraSAR-X satellite
(2010)Atmospheric Chemistry and Physics DiscussionsGPS radio occultation events observed between 24 July and 17 November 2008 bythe IGOR occultation receiver aboard the TerraSAR-X satellite are processed and ana-lyzed. The comparison of 16 262 refractivity profiles with collocated ECMWF data yielda mean bias of−0.60% to+0.02% at altitudes between 5 and 30 km. Standard deviations decrease from about 0.8% to 1.8% at 5 km to about 0.5% to 0.8% at about 10kmaltitude. At low latitudes mean ...Working Paper -
The SINS survey of z~2 galaxy kinematics
(2010)arXivWe have studied the properties of giant star forming clumps in five z~2 star-forming disks with deep SINFONI AO spectroscopy at the ESO VLT. The clumps reside in disk regions where the Toomre Q-parameter is below unity, consistent with their being bound and having formed from gravitational instability. Broad H{\alpha}/[NII] line wings demonstrate that the clumps are launching sites of powerful outflows. The inferred outflow rates are ...Working Paper -
Global fungal spore emissions, review and synthesis of literature data
(2010)Biogeosciences DiscussionsThe Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from ...Working Paper -
Density of rational points on commutative group varieties and small transcendence degree
(2010)arXivThe purpose of this paper is to combine classical methods from transcendental number theory with the technique of restriction to real scalars. We develop a conceptual approach relating transcendence properties of algebraic groups to results about the existence of homomorphisms to group varieties over real fields. Our approach gives a new perspective on Mazur's conjecture on the topology of rational points. We shall reformulate and generalize ...Working Paper -
Distributed Verification and Hardness of Distributed Approximation
(2010)arXivWe study the verification problem in distributed networks, stated as follows. Let H be a subgraph of a network G where each vertex of G knows which edges incident on it are in H. We would like to verify whether H has some properties, e.g., if it is a tree or if it is connected. We would like to perform this verification in a decentralized fashion via a distributed algorithm. The time complexity of verification is measured as the number ...Working Paper -
The Financial Bubble Experiment
(2010)arXivThis is the third installment of the Financial Bubble Experiment. Here we provide the digital fingerprint of an electronic document in which we identify 27 bubbles in 27 different global assets; for 25 of these assets, we present windows of dates of the most likely ending time of each bubble. We will provide that document of the original analysis on 2 May 2011.Working Paper -
A Semigroup Point Of View On Splitting Schemes For Stochastic (Partial) Differential Equations
(2010)arXivWe construct normed spaces of real-valued functions with controlled growth on possibly infinite-dimensional state spaces such that semigroups of positive, bounded operators $(P_t)_{t\ge 0}$ thereon with $\lim_{t\to 0+}P_t f(x)=f(x)$ are in fact strongly continuous. This result applies to prove optimal rates of convergence of splitting schemes for stochastic (partial) differential equations with linearly growing characteristics and for ...Working Paper -
Locking classical information
(2010)arXivIt is known that the maximum classical mutual information that can be achieved between measurements on a pair of quantum systems can drastically underestimate the quantum mutual information between those systems. In this article, we quantify this distinction between classical and quantum information by demonstrating that after removing a logarithmic-sized quantum system from one half of a pair of perfectly correlated bitstrings, even the ...Working Paper -
Pore structure 3-D imaging by synchrotron micro-tomography of graupel grains
(2010)Atmospheric Measurement Techniques DiscussionsThree dimensional air bubble structure including size distribution, concentration andspatial distribution are important clues in identifying the growth regime of graupel andhailstone. For imaging of the bubble structure, a cryo-stage was developed to adapt tothe standard setup of the SLS X04SA tomography beamline (actually replaced by the TOMCAT beamline) at the Swiss Light Source synchrotron facility to the requirementsof ice particle ...Working Paper