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Wednesday, 26.11.2014, 10.00 Uhr (WIAS-HVP-4.13)
Forschungsseminar Mathematische Statistik
Prof. U. Schneider, Wirtschaftsuniversität Wien, Austria:
On distributional properties of Lasso-type estimators noise
more ... Location
Weierstraß-Institut, Hausvogteiplatz 11A, 10117 Berlin, 4. Etage, Raum: 4.13

Abstract
Penalized least-squares estimators, such as the famous Lasso estimator, have been studied intensively in the statistics literature in the past decade. While many aspects of these estimators are well-understood, still, relatively little is known about their distributional properties, such as nite- and large-sample distributions, uniform convergence rates and, in particular, con dence sets. We present exemplary results for the adaptive Lasso estimator and discuss why the approach often taken in the literature only gives partial answers.

Further Informations
Forschungsseminar ``Mathematische Statistik''

Host
WIAS Berlin
Humboldt-Universität zu Berlin
Universität Potsdam
Thursday, 27.11.2014, 16.00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
J. Javaloyes, University of Balearic Island, Department of Physics:
Temporal localized structures in vertical-cavity surface-emitting lasers
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
Localized structures are nonlinear inhomogeneous states of dissipative extended systems characterized by a correlation range much shorter than the size of the system, thus allowing for individual addressing. In this presentation we will review the results recently obtained on Temporal Localized Structures (TLS) in VCSELs coupled to an external cavity. We show that, when the cavity round-trip is much larger than the medium timescales, this system exhibits a temporal aspect-ratio large enough to host TLS. Three con?gurations will be considered. In the ?rst one the system is submitted to cross-polarization reinjection which leads to the formation of vectorial TLS. Here the TLS are interpreted as topological kinks in the polarisation that is circling around the equator of the Stokes Sphere. In the second one the external cavity is closed by a Resonant Saturable Absorber Mirror, a scheme conventionally used to obtain mode-locked pulses. Here we will show how TLS can be obtained from the well known regime of mode-locking. The third seyup combines optical feedback and optical injection with leads to the regeneration of optical phase slips that we interpret as overdamped Sine-Gordon Solitons.

Further Informations
Forschungsseminar Mathematische Modelle der Photonik

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Wednesday, 03.12.2014, 10.00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Statistik
D. Chetverikov, University of California, Los Angeles, USA:
Nonparametric instrumental variable estimation under monotonicity
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Further Informations
Forschungsseminar ``Mathematische Statistik''

Host
WIAS Berlin
Humboldt-Universität zu Berlin
Universität Potsdam
Wednesday, 03.12.2014, 15.15 Uhr (WIAS-ESH)
BERLINER OBERSEMINAR Nichtlineare partielle Differentialgleichungen (Langenbach-Seminar)
Dr. M. Liero, WIAS Berlin:
On the geometry of reaction-diffusion --- The Hellinger-Kantorovich distance
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Further Informations
Berliner Oberseminar ``Nichtlineare Partielle Differentialgleichungen'' (Langenbach Seminar)

Host
WIAS Berlin
Humboldt-Universität zu Berlin
Thursday, 04.12.2014, 16.00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
M. Hofmann, WIAS Berlin:
Saturation of the all-optical Kerr effect by resonance-enhanced multiphoton ionization
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Tuesday, 09.12.2014, 15.00 Uhr (WIAS-406)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
M. Malioutov, Northeastern University, Massachusetts, USA:
SCOT modeling, training and homogeneity testing
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Weierstraß-Hörsaal (Raum: 406)

Host
WIAS Berlin
Wednesday, 10.12.2014, 15.15 Uhr (WIAS-ESH)
BERLINER OBERSEMINAR Nichtlineare partielle Differentialgleichungen (Langenbach-Seminar)
Prof. J. Naumann, Humboldt-Universität zu Berlin:
On the existence of weak solutions to Prandtl's (1945) one-equation model of turbulence
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Further Informations
Berliner Oberseminar ``Nichtlineare Partielle Differentialgleichungen'' (Langenbach Seminar)

Host
WIAS Berlin
Humboldt-Universität zu Berlin
Monday, 15.12.2014, 14.00 Uhr (WIAS-ESH)
INSTITUTSKOLLOQUIUM
Prof. Dr. S. Christiansen, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH:
Advanced nano- patterned composite materials and their application in energy harvesting and sensing
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstract
We will report on novel nano-patterned composite materials for sensing and energy harvesting. We rely on a wealth of nano-composites composed of silicon (Si) as well as GaN nanowires (NWs) from chemical vapor deposition (CVD) based processing including NW shaping based on reactive ion etching, plasmonic nano-structures realized by patterning with focused ion beam microscopes (FIB) of thin metal layer or particle (silver, gold) and few layer graphene from CVD processing. The NWs show large surface areas that can chemically be functionalized to account for sensing functionality. The graphene requires proper chemical treatment to permit attachment of functional groups. The chemical routes to nano-materials functionalization will be reported. Sensing mechanisms with functional nano-materials can be e.g. of electrical, optical or mechanical nature. Examples will be given for selected cases. Emphasis will reside on optical detection based on the surface-enhanced Raman scattering (SERS) effect. We will report SERS of graphene layers transferred on arrays of split ring resonators (SRRs). Raman enhancement factors per area up to 75 demonstrate the strong plasmonic coupling between graphene and the metamaterial resonances. The SRR/graphene material offers a perspective to control SERS and may pave the way towards advanced SERS substrates that could lead to the detection of single molecules attached to graphene for bio-chemical sensing. For energy harvesting applications we develop Si and GaN nanowires with which Mie modes can be controlled and efficient absorption of solar light can be tuned. The integration of NWs in thin film solarcell concepts with efficiency potential >>15% will be demonstrated. The same type of Si NWs and their applicability to solarfuels generation will be shown.

Host
WIAS Berlin
Thursday, 18.12.2014, 16.00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
R. M. Arkhipov, WIAS Berlin:
Modeling of mode-locking regimes in lasers
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
WIAS Berlin
January 27 – 29, 2015 (WIAS-ESH)
Workshop/Konferenz: 3rd Annual ERC Berlin-Oxford Young Researchers Meeting on Applied Stochastic Analysis
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin
European Research Council
Thursday, 29.01.2015, 16.15 Uhr (WIAS-405-406)
Forschungsseminar Mathematische Modelle der Photonik
M. Kantner, WIAS Berlin:
t.b.a.
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406

Host
Humboldt-Universität zu Berlin
WIAS Berlin
Thursday, 05.02.2015, 16.00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Modelle der Photonik
Dr. A. Pimenov, WIAS Berlin:
Dynamics of passively mode-locked inhomogeneously broadened lasers
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
Humboldt-Universität zu Berlin
WIAS Berlin
March 11 – 13, 2015 (WIAS-ESH)
Workshop/Konferenz: Applied Mathematics and Simulation for Semiconductors
more ... Location
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Host
WIAS Berlin