Alireza RafieeQuasar lifetime and Black Hole Spin Quasars seem to have a limited lifetime
They continuously accrete matter and gain angular momentum but the increase on radiative efficiency of that system remains limited to a physical upper bound. Using that physical barrier, we have estimated an upper limit for quasar lifetime.
Steve BealeMeasuring Bs mixing at the Fermilab Tevatron
Neutral Bs mesons (b-bar s) will spontaneously transform into their anti-particle (and visa versa) by a weak process known as mixing. Measurement of the mixing frequency provides an important constraint on the electroweak coupling of s and d quarks with the top quark. Presently, the only place where this measurement can be made is at the Fermilab Tevatron, a proton-antiproton collider with a center of mass energy of 1.96 TeV. The D0 detector is one of two collider detectors at Fermilab currently working to make this measurement. After a short overview of the Tevatron, the D0 Detector, and general mixing phenomenology, I will present the latest mixing measurement from D0.
Tzahi YavinModelling Markets
In the last quarter of a century or so, the sophistication of the mathematical modeling of financial markets has witnessed a tremendous increase. In this talk I will briefly discuss one of the corner stones in this field, the Black-Scholes model, and how it is used to price options for stocks trading on the stock exchange.
Yan SunDensity functional study of 13-atom transition-metal clusters and bimetallic A_4B_12 clusters
Min zhangGlobal optimization of 13-atom 5d transition metals
We did structural global optimization for six 5d transition metals(Ta-Pt). Two optimization algorithms, Tabu Search in Descriptor Space(TSDS) and Simulated annealing (SA), were used and their performances were compared. Energy evaluation was done with PBE exchange-correlation functional implemented by VASP. Due to complexity of the multiplicities of transition metals, we did calculations with full relaxation of multiplicity. Amazingly, we found none of them had an icosahedral ground state structure. We compared thoroughly our results with previously reported structures. Calculations show that our results are the best. To rule out the difference could be introduced by choice of functional, we did local optimization for our results and structures reported by other researchers with LDA and PW91. The LDA and PW91 functionals give similar results to PBE and confirm that we found the best structures to date for these clusters.
Brynle BarrettInterferometric Measurement of the Fine Structure Constant using Cold Rubidium
Atoms in an Atomic Fountain One of the most challenging questions in astrophysics today is to establish when and how the universe became (re)ionized. Although it is accepted that the overall process is well understood, and in spite of the observational and theoretical progress that have been made in the last few years, there are still many details that remain controversial and unsolved. At a redshift z ~ 6 we are approaching to the end of Epoch of Reionization, but the number of known quasars and galaxies close to this redshift is still very low, thus the uncertainties are large. To improve our knowledge of that fundamental epoch we need to find more high redshift sources. Here, I will briefly summarize some of the basic ideas on this topic and present the description of the data we are working on and the procedure we have followed.
Edward AckadSupercritical Collisions with no intial electrons Colliding two fully ionized
Uranium atoms can lead to pair creation, but solving for a collision with no initial electrons is not commonly done. I will show how it is possible to solve for this system and show results of current work were we can show the enhancement of the positron production due to the decay of supercritical resonance state for collisions with some nuclear sticking.
When: August 30th, 2007
Where: Ross S137 (Number 30 in York map)
To present a talk in the conference, please send an email to the president of the PAGE.
Attendance is free. We strongly encourage graduate students to participate this event.
Alireza Rafiee firstname.lastname@example.org
Brynle Barrett email@example.com
Carson Mok firstname.lastname@example.org
Edward Ackad email@example.com (Chair of the Organizing Committee)
10:15 Alireza Rafiee
10:30 Tzahi Yavin
10:45 Min Zhang
11:00 Coffee break
11:15 Victoria Martynenko
11:30 Yan Sun
Lunch Provided by PAGE
1:00 Steve Beale
1:30 Brynle Barrett
1:45 Edward Ackad
About the Lion Tamarins:
Lion tamarins have a mane derived from long hairs on the top of the head, cheeks and throat. The golden lion tamarin’s color is predominantly golden with occasional orange, brown or black coloration on the tail and forepaws. It weighs about 0.5 kg (1.1 lb) and averages about 25 cm (10″) in head/body length, not counting the tail. The golden lion tamarin prefers primary lowland tropical forest from sea level to 1000 m (3300′). Golden lion tamarins are omnivorous, feeding on fruits, gum, nectar, insects, and small vertebrates. The golden lion tamarin is diurnal and predominantly arboreal. It is usually found at heights of 3 – 10 m (10 – 30′) above the forest floor. It sleeps there at night in tangled vegetation or, more often, in a hole in a tree, such as an abandoned woodpecker nest. Most golden lion tamarins live in reproductive groups that occupy stable territories. The average number of individuals/group in one study was 5.4. In the wild, groups usually consist of one breeding adult of each sex and younger animals. Golden lion tamarins are cooperative breeders: all adult members of a group help to carry and feed the offspring of the group, with the adult male commonly doing the largest share. The mother only takes the babies to nurse them. In the 19th century, the golden lion tamarin occurred in Brazil in the coastal forests of the states of Rio de Janeiro and Espirito Santo. By the early 1980’s it was known only from remnant forests in the state of Rio de Janeiro in an area of occupied habitat probably totaling considerably less than 900 sq km (350 sq mi). The wild population is currently fragmented into 17 different subpopulations in isolated forest patches throughout its small range. More than 90% of the original Atlantic coastal forest, which contains the golden lion tamarin’s habitat, has been lost or fragmented to obtain lumber and charcoal and to clear out areas for plantations, cattle pasture, and development. Capture for zoos and private collections also contributed to its decline in the past. The golden lion tamarin is still under severe threat from continued deforestation, much of which is undertaken to create weekend beach properties. Less than 2% of the forest remains in the region where the golden lion tamarin lives.
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