Found 15 talks width keyword science

Video
Thursday January 28, 2016
Dr. Francisco Kitaura
AIP

Abstract

The cosmological large-scale structure encodes a wealth of information about the origin and evolution of our Universe. Galaxy redshift surveys provide a 3-dimensional picture of the luminous sources in the Universe. These are however biased tracers of the underlying dark matter field. I will discuss the different components which are relevant to model galaxy bias, ranging from deterministic nonlinear, over non-local, to stochastic components. These effective bias ingredients permit us to save computational time and memory requirements, to efficiently produce mock galaxy catalogues. These are useful to study systematics of survey, test analysis tools, and compute covariance matrices to perform a robust analysis of the data. Moreover, this description permits us to implement them in inference analysis methods to recover the dark matter field and its peculiar velocity field. I will show some examples based on the largest sample of luminous red galaxies to date based on the final BOSS SDSS-III data release.


Video
Tuesday January 26, 2016
Prof. Ron Kikinis
Harvard Medical School

Abstract

The amount of data available in image guided medical interventions and surgeries is growing at a rapid rate. More data per device and more devices present during individual procedures result in a situation, where the interventionalist is often overwhelmed by the amount and complexity of the data available. The lack of integration of the varying source of information is due to the lack of adopted standards and is accentuating this problem. The presentation will cover some of the root causes of this situation and discuss possible solutions.


Video
Tuesday December 1, 2015
Dr. Marina Manganaro
IAC

Abstract

The search for detection of gamma-rays in the very-high-energy range (VHE, >100GeV) from distant AGNs by Imaging Atmospheric Cherenkov Telescopes (IACTs) gets very complicated at high redshifts, not only because of the lower flux due to the distance of the source, but also due to the consequent absorption of gamma-rays by the extragalactic background light (EBL), affecting VHE sources at z~0.1 and beyond. The farthest source ever detected in the VHE domain was the blazar PKS1424+240, at redshift z>0.6. In the last months MAGIC, a system of two 17 m of diameter IACTs located in the Canary island of La Palma, has been able to go beyond that limit and to push the boundaries for VHE detection to redshifts z~1. The two sources detected and analyzed, blazar S30218+35 (Atel discovery #6349) and FSRQ PKS1441+25 (Atel discovery #7416) are located at redshift z=0.944 and z=0.939 respectively. S30218+35 is also the first gravitational lensed blazar ever detected in VHE. The multiwavelength dataset collected allowed us to test for the first time the present generation of EBL models at such distances. I will show results on MAGIC analysis on S30218+35 and PKS1441-25, including spectral energy distributions and EBL absorption studies, in a multi-wavelength context.


Video
Tuesday March 17, 2015
Prof. Malcolm Longair
University of Cambridge, UK

Abstract

Divulgation Lecture to Celebrate the International Year of Light and 150th Anniversary of Maxwell´s great paper on Electromagnetism of 1865.


Video
Monday November 17, 2014
Prof. Martín Rivas
Theoretical Physics Department - University of the Basque Country

Abstract

Things should be made simple, but not simpler.

What we want to show is that General Relativity, as it stands today, can be considered as a gravitational theory of low velocity spinless matter, and therefore a restricted theory of gravitation.

Gravity is understood as a geometrization of spacetime. But spacetime is also the manifold of the boundary values of the spinless point particle in a variational approach. Since all known elementary matter, baryons, leptons and gauge bosons are spinning objects, it means that the manifold, which we call the kinematical space, where we play the game of the variational formalism of a classical elementary particle must be greater than spacetime.

Mathematics shows that this manifold for any arbitrary mechanical system is always a Finsler metric space, such that the variational formalism can be interpreted as a geodesic problem on this metric space.

This manifold is just the flat Minkowski space for the free spinless particle.  Any interaction modifies its flat Finsler metric as gravitation does.

The same thing happens for the spinning objects, but now the Finsler metric space has more dimensions and its metric is modified by any interaction, so that to reduce gravity to the modification only of the metric of the spacetime submanifold is to make a simpler theory, the gravitational theory of spinless matter.

Even the usual assumption that the modification of the metric only produces a Riemannian metric of the spacetime is also a restriction because in general the coefficients for a Finsler metric, are also dependent on the velocities. Removal of the velocity dependence of metric coefficients is equivalent to consider the restriction to low velocity matter.

In the spirit of unification of all forces, gravity cannot produce, in principle, a different and simpler geometrization than any other interaction.

References: arXiv: 1203.4076


Video
Monday October 22, 2012
Dr. Seigo Miyamoto, Dr. Valeri Tioukov
ERI, University of Tokyo, Japan
INFN, Napoli, Italy

Abstract

The origin and structure of the Earth's crust is still a major question. Current measurements of the nearby crust are based largely on seismic, gravimetric and electrical  techniques. In this talk, we introduce a novel method based on cosmic-ray muons to create a direct snapshot of the density profile within a volcano (and/or other geological features).  By measuring the muon
absorption along the different paths through an object (volcano, mountain, a fault, ...), one can deduce the density profile within the object. The major feature of this
technique makes possible for us to perform a tomographic measurement by placing two or more cosmic ray detection
systems around the object. Another strong point of this technique is the possibility to carry out fulltime monitoring, since  muons are incessantly arriving, recalling they are
the most numerous energetic charged particles at sea level.


Video
Thursday October 18, 2012
Dr. Miguel Cerviño
IAA

Abstract

The basis of stellar population modeling was established around 40 years ago somehow
optimized to the technical facilities and observational data available at that epoch. Since then,
it has been used extensively in astronomy and there has been great improvements relating
their associated ingredients in concordance with the development of more powerful computational
and observational facilities.
However, there has been no similar improvements in the understanding about what is
actually modeling neither in improve the modeling itself to include the current technical advances
to obtain more accurate result in the physical inferences obtained from them.
In this talk I present some advances in the subject of stellar
population modeling and how to take advantage of current facilities to obtain more robust
and accurate inferences from stellar systems at different scales
covering the continuum between fully resolved populations to fully unresolved ones in a unified framework.


Video
Tuesday February 28, 2012
Dr. Almudena Alonso Herrero
Instituto de Astrofísica de Cantabria, Spain

Abstract

Luminous Infrared Galaxies (LIR=10^11-10^12Lsun) have star formation rates in the range of ~20-200Msun/yr. In the local Universe ~50% LIRGs show AGN or AGN/SB composite nuclear activity from optical spectroscopy. We decompose Spitzer/IRS 5-35micron spectra of a complete sample of 50 local (d<75Mpc) LIRGs using SB and AGN clumpy torus model templates. We derive a mid-IR AGN detection rate in our sample of local LIRGs of 50%. We also compare the continuum mid-IR AGN detection with other indicators in the mid-IR, optical and X-rays. We estimate for the first time the AGN bolometric contribution to the IR luminosity of the galaxies in local LIRGs. We find that one-third of local LIRGs have LAGN(bol)/LIR>0.05, with only ~10% having a significant contribution LAGN(bol)/LIR>0.25. This is in line with results of Nardini et al. (2010) that only at LIR>3x10^12Lsun the AGN starts dominating bolometrically the IR luminosity in the majority of the systems.


Video
Thursday February 3, 2011
Dr. Carlos Allende, Dr. Ismael Pérez-Fournon
Instituto de Astrofísica de Canarias, Spain

Abstract

Since June last year, the IAC is an institutional member in the third phase of the Sloan Digital Sky Survey (SDSS-III). Many of us have already got an account in the wiki, a bunch are following closely the evolution of one or more of the four surveys, BOSS, MARVELS, SEGUE-2 and APOGEE, through the mailing lists and the teleconferences, and there are even some who are already working actively on them. All this in a period of one year since the IAC´s participation was first proposed. In this seminar, we'll make a quick summary of the activities related to SDSS at the IAC, we'll present the latest news, and will make a live demonstration on how to access DR8 data.


Video
Monday March 29, 2010
Prof. Leslie Sage
Editor Senior Nature, University Maryland, USA

Abstract

Nature is one of the world's leading scientific journals, publishing many papers that receive wide attention by the general public. But, Nature is very selective —> < 7% of submitted papers are published. In order to maximize your chances of getting published, papers should present fundamental new physical insights, or startling observations/results. Theory papers pose additional problems, as we want only those papers that are likely to be the correct explanation, and not simply exploring parameter space. The writing should be clear, concise and directed at the level of a graduate course in the subject. I encourage authors to contact me in advance of submission of a paper, both to ascertain the appropriateness of the result for Nature, and to ensure that the writing is close to our standards. Posting to ArXiv is and always has been allowed, but authors should discuss the specifics with their institutional public affairs officers before doing so. Lapses in professional ethics seem to be on the rise? I will discuss some examples, and what we should be doing to keep astronomy clean.


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