Time filter

Source Type

NJ, United States

Barak B.,Microsoft | Gopalan P.,Microsoft | Hastad J.,KTH Royal Institute of Technology | Meka R.,Institute of Advanced Study | And 2 more authors.
Proceedings - Annual IEEE Symposium on Foundations of Computer Science, FOCS | Year: 2012

The long code is a central tool in hardness of approximation, especially in questions related to the unique games conjecture. We construct a new code that is exponentially more efficient, but can still be used in many of these applications. Using the new code we obtain exponential improvements over several known results, including the following: 1) For any ε > 0, we show the existence of an n vertex graph G where every set of o(n) vertices has expansion 1-ε, but G's adjacency matrix has more than exp(logδ n) eigenvalues larger than 1 - ε, where δ depends only on ε. This answers an open question of Arora, Barak and Steurer (FOCS 2010) who asked whether one can improve over the noise graph on the Boolean hypercube that has poly(log n) such eigenvalues. 2) A gadget that reduces unique games instances with linear constraints modulo K into instances with alphabet k with a blowup of Kpolylog(K), improving over the previously known gadget with blowup of 2Ω(K). 3) An n variable integrality gap for Unique Games that survives exp(poly(log log n)) rounds of the SDP + Sherali Adams hierarchy, improving on the previously known bound of poly(log log n). We show a connection between the local testability of linear codes and small set expansion in certain related Cayley graphs, and use this connection to derandomize the noise graph on the Boolean hypercube. © 2012 IEEE.

Menard B.,University of Toronto | Scranton R.,University of California at Davis | Fukugita M.,University of Tokyo | Fukugita M.,Institute of Advanced Study | Richards G.,Drexel University
Monthly Notices of the Royal Astronomical Society | Year: 2010

We present a simultaneous detection of gravitational magnification and dust reddening effects due to galactic haloes and large-scale structure. The measurement is based on correlating the brightness of ~85 000 quasars at z > 1 with the position of 24 million galaxies at z ~ 0.3 derived from the Sloan Digital Sky Survey and is used to constrain the galaxy-mass and galaxy-dust correlation functions up to cosmological scales. The presence of dust is detected from 20 kpc to several Mpc, and we find its projected density to follow: Σdust ~ r-0.8 p , a distribution similar to mass. On large scales, its wavelength dependence is described by RV ≃ 4.9 ± 3.2, consistent with interstellar dust. This, in turn, implies a cosmic dust density of Ωdust ≃ 5 × 10-6, roughly half of which comes from dust in haloes of ~L* galaxies. We estimate the resulting opacity of the Universe for various evolutionary models and find (AV) ~ 0.03mag up to z = 0.5. We present magnification measurements, corrected for dust extinction, from which the galaxy-mass correlation function is inferred to give the mean surface mass density profile around galaxies Σ ~ 30 (θ/1 arcmin)-0.8 hM pc-2 up to a radius of 10 Mpc, in agreement with gravitational shear estimates. © 2010 The Authors. Journal compilation © 2010 RAS.

Holt G.C.,Institute of Advanced Study
Nanotechnology Perceptions | Year: 2012

The protagonists of Great Britain's Industrial Revolution were, famously, typically men without a formal education. Nevertheless, the development of ultrahigh technologies such as nanotechnology seems to demand a high level of higher education. This essay appraises the appropriate level of graduate education using the concept of the J-value. Education is discussed in the context of other government services. It is concluded that higher education is an excellent national investment provided the number of graduates is maintained at an affordable level. © 2012 Collegium Basilea.

Elliott M.A.,National University of Ireland | Elliott M.A.,Ludwig Maximilians University of Munich | Seifert D.,Ludwig Maximilians University of Munich | Poggel D.A.,Ludwig Maximilians University of Munich | And 3 more authors.
Consciousness and Cognition | Year: 2015

Three patients with visual field defects were stimulated with a square matrix pattern, either static, or flickering at frequencies that had been found to either promote or not promote blindsight performance. Comparison between pre- and post-stimulation perimetric maps revealed an increase in the size of the intact visual field but only for flicker frequencies previously found to promote blindsight. These changes were temporary but dramatic - in two instances the intact field was increased by an area of ~30deg2 of visual angle. These results indicate that not only does specific high-frequency stimulus flicker promote blindsight, but that intact visual field size may be increased by stimulation at the same frequencies. Our findings inform speculation on both the brain mechanisms and the potency of temporal modulation for altering the functional visual field. © 2014 Elsevier Inc.

Orgovan N.,Eotvos Lorand University | Orgovan N.,Institute for Technical Physics and Materials Science | Patko D.,Institute for Technical Physics and Materials Science | Patko D.,University of Pannonia | And 6 more authors.
Advances in Colloid and Interface Science | Year: 2014

This paper gives an overview of the advantages and associated caveats of the most common sample handling methods in surface-sensitive chemical and biological sensing. We summarize the basic theoretical and practical considerations one faces when designing and assembling the fluidic part of the sensor devices. The influence of analyte size, the use of closed and flow-through cuvettes, the importance of flow rate, tubing length and diameter, bubble traps, pressure-driven pumping, cuvette dead volumes, and sample injection systems are all discussed. Typical application areas of particular arrangements are also highlighted, such as the monitoring of cellular adhesion, biomolecule adsorption-desorption and ligand-receptor affinity binding. Our work is a practical review in the sense that for every sample handling arrangement considered we present our own experimental data and critically review our experience with the given arrangement. In the experimental part we focus on sample handling in optical waveguide lightmode spectroscopy (OWLS) measurements, but the present study is equally applicable for other biosensing technologies in which an analyte in solution is captured at a surface and its presence is monitored. Explicit attention is given to features that are expected to play an increasingly decisive role in determining the reliability of (bio)chemical sensing measurements, such as analyte transport to the sensor surface; the distorting influence of dead volumes in the fluidic system; and the appropriate sample handling of cell suspensions (e.g. their quasi-simultaneous deposition). At the appropriate places, biological aspects closely related to fluidics (e.g. cellular mechanotransduction, competitive adsorption, blood flow in veins) are also discussed, particularly with regard to their models used in biosensing. © 2014 Elsevier B.V.

Discover hidden collaborations