The 13th international workshop on the "Dark Side of the Universe 2017"
will be held at the Institute for Basic Science (IBS), S. Korea. The
Dark Side of the Universe ( DSU ) workshops bring together a wide range
of theorists and experimentalists to discuss ideas on models of the dark
side, and relate them to current and future experiments.
Topics covered include dark matter, dark energy, cosmic rays, neutrino
physics, cosmology, early Universe phenomenology and physics beyond the
standard model.
The homepage is at
http://indico.ibs.re.kr/event/
(There is no registration fee for this workshop.)
DSU2017 is supported by the Institute for Basic Science and jointly
hosted by Center for Theoretical Physics of the Universe (CTPU /
Particle Theory and Cosmology Group), Center for Axion and Precision
Physics Research (CAPP) and Center for Underground Physics (CUP).
Best wishes,
On behalf of the LOC,
Ki-Young Choi
Speaker : Shahin Sheikh-Jabbari, IPM, Tehran, Iran
Abstract
The standard classification of sciences and human knowledge is
generically a either subject-wise or based on the methodology used. In
this classification physics is one of basic, empirical sciences. Physics
is about to uncover and formulate laws of nature and natural phenomena.
Therefore, the borderline between physics and other sciences and human
knowledge is not a bold and pronounced one. Given the fast advancement
in the frontiers of human knowledge, topics which are coming to the area
of interdisciplinary sciences, especially in the recent ten-twenty
years, has been changing as fast. The relation between physics and other
sciences, depending on the topic can be different: its relation with
other basic sciences is generically two-ways, with engineering sciences
or medicine is generically one-way (applications of physics in them) and
with modern human sciences is more toward providing quantitative
formulations and setups. In this talk, I will briefly go over through
applications and relations of physics and four other branches of
science, basics sciences, engineering, medicine and human sciences
,,,,Coming Soon,,,,
The quantum structure of space-time at the Planck scale and quantum fields
,Sergio Doplicher, Klaus Fredenhagen, John E. Roberts
(Submitted on 5 Mar 2003)
We propose uncertainty relations for the different coordinates of space-time events, motivated by Heisenberg's principle and by Einstein's theory of classical gravity. A model of Quantum Space-time is then discussed where the commutation relations exactly implement our uncertainty relations.
We outline the definition of free fields and interactions over QST and take the first steps to adapting the usual perturbation theory. The quantum nature of the underlying spacetime replaces a local interaction by a specific nonlocal effective interaction in the ordinary Minkowski space. A detailed study of interacting QFT and of the smoothing of ultraviolet divergences is deferred to a subsequent paper.
In the classical limit where the Planck length goes to zero, our Quantum Spacetime reduces to the ordinary Minkowski space times a two component space whose components are homeomorphic to the tangent bundle TS^2 of the 2-sphere. The relations with Connes' theory of the standard model will be studied elsewhere
https://arxiv.org/abs/hep-th/0303037
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Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
Authors: Riess, Adam G.; Filippenko, Alexei V.; Challis, Peter; Clocchiatti, Alejandro; Diercks, Alan; Garnavich, Peter M.; Gilliland, Ron L.; Hogan, Craig J.; Jha, Saurabh; Kirshner, Robert P.; Leibundgut, B.; Phillips, M. M.; Reiss, David; Schmidt, Brian P.; Schommer, Robert A.; Smith, R. Chris; Spyromilio, J.; Stubbs, Christopher; Suntzeff, Nicholas B.; Tonry, John
Bibliographic Code: 1998AJ....116.1009R
Abstract
We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.62 ≥ z ≥ 0.16. The luminosity distances of these objects are determined by methods that employ relations between SN Ia luminosity and light curve shape. Combined with previous data from our High-z Supernova Search Team and recent results by Riess et al., this expanded set of 16 high-redshift supernovae and a set of 34 nearby supernovae are used to place constraints on the following cosmological parameters: the Hubble constant (H0), the mass density (ΩM), the cosmological constant (i.e., the vacuum energy density, Ωλ), the deceleration parameter (q0), and the dynamical age of the universe (t0). The distances of the high-redshift SNe Ia are, on average, 10%-15% farther than expected in a low mass density (ΩM = 0.2) universe without a cosmological constant. Different light curve fitting methods, SN Ia subsamples, and prior constraints unanimously favor eternally expanding models with positive cosmological constant (i.e., Ωλ > 0) and a current acceleration of the expansion (i.e., q0 < 0). With no prior constraint on mass density other than Omega_M >= 0, the spectroscopically confirmed SNe Ia are statistically consistent with q0 < 0 at the 2.8 σ and 3.9 σ confidence levels, and with Ωλ > 0 at the 3.0 σ and 4.0 σ confidence levels, for two different fitting methods, respectively. Fixing a ``minimal'' mass density, Omega_M = 0.2, results in the weakest detection, Ωλ > 0 at the 3.0 σ confidence level from one of the two methods. For a flat universe prior (ΩM + Ωλ = 1), the spectroscopically confirmed SNe Ia require Ωλ > 0 at 7 σ and 9 σ formal statistical significance for the two different fitting methods. A universe closed by ordinary matter (i.e., ΩM = 1) is formally ruled out at the 7 σ to 8 σ confidence level for the two different fitting methods. We estimate the dynamical age of the universe to be 14.2 +/- 1.7 Gyr including systematic uncertainties in the current Cepheid distance scale. We estimate the likely effect of several sources of systematic error, including progenitor and metallicity evolution, extinction, sample selection bias, local perturbations in the expansion rate, gravitational lensing, and sample contamination. Presently, none of these effects appear to reconcile the data with Ωλ = 0 and q0 >= 0.
http://www.stsci.edu/~ariess/documents/1998.pdf
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Dark energy as a kinematic effect
Hendrick Jennen_Sao Paulo, IFT
Abstract
Observations during the last three decades have confirmed that the universe
momentarily expands at an accelerated rate, which is assumed to be driven by
dark energy whose origin remains unknown. The minimal manner of modelling dark
energy is to include a positive cosmological constant in Einstein’s equations,
whose solution in vacuum is de Sitter space. This indicates that the
large-scale kinematics of spacetime is approximated by the de Sitter group
SOp1, 4q rather than the Poincaré group ISOp1, 3q. In this thesis we take this
consideration to heart and conjecture that the group governing the local
kinematics of physics is the de Sitter group, so that the amount to which it is
a deformation of the Poincaré group depends pointwise on the value of a nonconstant
cosmological function. With the objective of constructing such a framework we
study the Cartan geometry in which the model Klein space is at each point a de
Sitter space for which the combined set of pseudoradii forms a nonconstant
function on spacetime. We find that the torsion receives a contribution that is
not present for a cosmological constant. Invoking the theory of nonlinear
realizations we extend the class of symmetries from the Lorentz group SOp1, 3q
to the enclosing de Sitter group. Subsequently, we find that the geometric
structure of teleparallel gravity— a description for the gravitational
interaction physically equivalent to general relativity— is a nonlinear
Riemann–Cartan geometry. This finally inspires us to build on top of a de
Sitter–Cartan geometry with a cosmological function a generalization of
teleparallel gravity that is consistent with a kinematics locally regulated by
the de Sitter group. The cosmological function is given its own dynamics and
naturally emerges nonminimally coupled to the gravitational field in a manner
akin to teleparallel dark energy models or scalar-tensor theories in general
relativity. New in the theory here presented, the cosmological function gives
rise to a kinematic contribution in the deviation equation for the world lines
of adjacent free-falling particles. While having its own dynamics, dark energy
manifests itself in the local kinematics of spacetime.
DEADLINE: 1st MAY 2017
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/We welcome your kind assistance in sharing the attached poster within
your community. Please do print the poster and display in your
institute, and////share this email with your colleagues./
Colloquium
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Dear all, Everybody is welcome to attend.
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Speaker Dr Hossein Abbasi Affliation Amir Kabir UnivTitle of talk Influence of external white noise on the formation of non-Maxwellian velocity distribution function: A molecular dynamics study.Date and time Wednesday, 30th of Farvardin (19th of April), 4:30 pm Place Farmanieh builing, lecture room C IPM Abstract Dynamics of a dust layer suspending in a plasma and interacting through a Yukawa-type potential is considered. In the small affinity limit, the influence of an external white noise on the formation of Tsallis' velocity distribution function is studied through molecular dynamics simulation. The characteristic length of the noise is much smaller than the system size that causes a number of subsystems (islands) to be formed with the size similar to the noise one. The external noise leads to the temperature fluctuation in each island. Therefore, a stochastic formalism based on a Langevin equation for the fluctuating temperature is presented. The approach provides a dynamical reason how a fluctuating temperature takes a system to a unique class of quasi-equilibrium states. In particular, the dependence of the model systems on the noise parameters is explained. The non-extensive parameter is obtained through which the small affinity limit can be defined. |
Dear colleagues
We would like to remind you about the summer school 'QCD Masterclass', that will take place on 18-24 of June 2017
in Saint-Jacut-de-la-Mer (west of France). The school is aimed in
priority at Ph.D. students and postdocs in theoretical high energy
physics, but senior researchers can also apply. All interested
candidates should apply via the pre-registration form _before March 15, 2017_ at https://indico.cern.ch/event/
The candidates are expected to apply for the complete duration of the
school. Successful applicants will be notified shortly after the
deadline for application. The registration fee is fixed to 400 euros and
includes the full board accommodation from June 18 (evening) to June 24 (morning). The fee will be waived for selected participants from CNRS.
The program of the QCD Masterclass consists in four topical lectures in QCD (~6-8 hours each) given from Monday to Friday. Topics and lecturers are:
Resummation in QCD - Eric Laenen (NIKHEF, Amsterdam, The Netherlands)
Saturation in QCD - Alfred Mueller (Columbia University, New York, USA)
Theory of quarkonium production - Jianwei Qiu (Jefferson Lab, Newport News, USA)
Color structure of QCD - to be announced
Please forward this second circular to anyone who may be interested. For any question, feel free to contact us at qcd2017@subatech.in2p3.fr .
Best regards,
Francois Arleo, Stephane Peigne (chairs of the QCD Masterclass organizing committee)
Subject: Intl School on Hypercomplex Numbers, Lie Groups and Applications
Dear Colleague,
It is my pleasure to inform you
about the Intl Summer School on
Hypercomplex Numbers,
Lie Groups, and Applications
to be held in Varna, June 9-12, 2017.
For more detail, please visit the
webpage of the meeting at
http://www.bio21.bas.bg/
Besides the Lectures Corses that will be delivered
by the wellknown experts, there would be
some slots for talks by the participants.
We plan also to publish as a separate
volume both the Lecture Courses
and the contributed Talks before
the end of this year.
Registered participant will receive
this volume for free.
Details about the Registration are
given on the webpage of the School.
Please, notice that the School will be
preceded by the XIX-th Edition of the
annual Conference on
Geometry, Integrability and Quantization
which will take place in June 2-7, 2017.
see
http://www.bio21.bas.bg/
Looking forward to meet you in Varna,
I remain,
Sincerely yours,
Ivailo Mladenov
==============================
web: http://www.bio21.bas.bg/ibf/
==============================
PS If you prefer not to receive such
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DNA replication is an extraordinarily complex multi-step process that makes copies of the body’s genetic blueprint. It is necessary for growth and essential to life.
Now researchers at the California Institute of Technology (Caltech) and Vanderbilt University have found evidence that one of those steps may involve the telephone-like transmission of electrical signals regulated by a chemical “switch.”
Conventional telephones convert sound waves into electrical signals that can be transmitted vast distances through wire, and which are then converted back into audible sound at the receiving end.
A similar form of communication may be required to achieve DNA replication. Only in this case the telephone wire is DNA and the telephones are unique clusters of four iron and four sulfur atoms within the multi-protein “machines” that copy it in a highly coordinated fashion.
This model of replication has not yet been proven. But in a report published this week by the journal Science, the Caltech/Vanderbilt team demonstrates the existence of the chemical switch that they believe plays a central role in enabling our genes to be copied efficiently.
“We propose this as a fundamentally new transformative idea about how you could get communication between proteins over very long spatial distances using DNA as a wire,” said Walter Chazin, Ph.D., the Chancellor’s Professor of Medicine, professor of Biochemistry and Chemistry and director of the Vanderbilt Center for Structural Biology.
“This chemistry provides a means of long range, rapid communication for processing genomic DNA,” added Jacqueline K. Barton, Ph.D., the John G. Kirkwood and Arthur A. Noyes Professor of Chemistry at Caltech and the paper’s co-corresponding author with Chazin.
Barton, who chairs the Division of Chemistry and Chemical Engineering, has spent decades studying DNA charge transport — the transmission of electricity through DNA — as a verifiable and biologically important phenomenon.
In 2007, Chazin and his colleagues reported finding a cluster of four iron atoms and four sulfur atoms within the protein human DNA primase, the enzyme that “primes” or readies the DNA template before full copies of the DNA can be made.
Iron-sulfur clusters are known to drive oxidation-reduction (redox) reactions, a type of chemical reaction that involves the transfer of electrons and which provides the energy for a wide range of biochemical processes. But what role these clusters played in DNA replication and other DNA transformations was not known.
Barton believed that iron-sulfur clusters could be used for DNA charge transport in cells and teamed up with the Chazin lab to prove this is important for copying genes.
In the current study, the researchers showed that the oxidative state of DNA primase — the number of electrons held by its iron-sulfur cluster — affects how strongly it binds to DNA. The iron-sulfur cluster thus acts as a “redox switch” to coordinate one of the critical steps of DNA replication.
The next step of this research is to show that DNA charge transport driven by iron-sulfur clusters enables DNA replication proteins to communicate with each other and synchronize their actions.
Iron-sulfur clusters are found in the multi-protein machines that perform virtually all transformation of DNA. Defects in any of these machines can lead to mutation, genome instability and ultimately cancer, neurological disorders and other diseases.
Understanding how DNA processing machines work could lead to fundamentally new avenues for the development of targeted therapies.
Study co-authors were Caltech graduate student Elizabeth O’Brien, Vanderbilt graduate students Marilyn Holt and Lauren Salay and Vanderbilt postdoctoral fellows Matthew Thompson, Ph.D., and Aaron Ehlinger, Ph.D.
The research was supported in part by National Institutes of Health grants GM061077, GM120087, GM065484 and GM118089, and training grant GM08320.
Subject: Intl School on Hypercomplex Numbers, Lie Groups and Applications
Dear Colleague,
It is my pleasure to inform you
about the Intl Summer School on
Hypercomplex Numbers,
Lie Groups, and Applications
to be held in Varna, June 9-12, 2017.
For more detail, please visit the
webpage of the meeting at
http://www.bio21.bas.bg/
Besides the Lectures Corses that will be delivered
by the wellknown experts, there would be
some slots for talks by the participants.
We plan also to publish as a separate
volume both the Lecture Courses
and the contributed Talks before
the end of this year.
Registered participant will receive
this volume for free.
Details about the Registration are
given on the webpage of the School.
Please, notice that the School will be
preceded by the XIX-th Edition of the
annual Conference on
Geometry, Integrability and Quantization
which will take place in June 2-7, 2017.
see
http://www.bio21.bas.bg/
Looking forward to meet you in Varna,
I remain,
Sincerely yours,
Ivailo Mladenov
==============================
web: http://www.bio21.bas.bg/ibf/
==============================
PS If you prefer not to receive such
alerts in the future, just respond to
this message by writing
"Remove"
in the main body of the letter.
Thought your Internet speeds were slow? Try being a space scientist for a day.
The vast distances involved will throttle data rates to a trickle. You're lucky if a spacecraft can send more than a few megabits per second (Mbps).
But we might be on the cusp of a change. Just as going from dial-up to broadband revolutionized the Internet and made high-resolution photos and streaming video a given, NASA may be ready to undergo a similar "broadband" moment in coming years.
The key to that data revolution will be lasers. For almost 60 years, the standard way to "talk" to spacecraft has been with radio waves, which are ideal for long distances. But optical communications, in which data is beamed over laser light, can increase that rate by as much as 10 to 100 times.
High data rates will allow researchers to gather science faster, study sudden events like dust storms or spacecraft landings, and even send video from the surface of other planets. The pinpoint precision of laser communications is also well suited to the goals of NASA mission planners, who are looking to send spacecraft farther out into the solar system.
"Laser technology is ideal for boosting downlink communications from deep space," said Abi Biswas, the supervisor of the Optical Communications Systems group at NASA's Jet Propulsion Laboratory, Pasadena, California. "It will eventually allow for applications like giving each astronaut his or her own video feed, or sending back higher-resolution, data-rich images faster."
Science at the speed of light
Both radio and lasers travel at the speed of light, but lasers travel in a higher-frequency bandwidth. That allows them to carry more information than radio waves, which is crucial when you're collecting massive amounts of data and have narrow windows of time to send it back to Earth.
A good example is NASA's Mars Reconnaissance Orbiter, which sends science data at a blazing maximum of 6 Mbps. Biswas estimated that if the orbiter used laser comms technology with a mass and power usage comparable to its current radio system, it could probably increase the maximum data rate to 250 Mbps.
On Earth, data is sent over far shorter distances and through infrastructure that doesn't exist yet in space, so it travels even faster.
Increasing data rates would allow scientists to spend more of their time on analysis than on spacecraft operations.
"It's perfect when things are happening fast and you want a dense data set," said Dave Pieri, a JPL research scientist and volcanologist. Pieri has led past research on how laser comms could be used to study volcanic eruptions and wildfires in near real-time. "If you have a volcano exploding in front of you, you want to assess its activity level and propensity to keep erupting. The sooner you get and process that data, the better."
That same technology could apply to erupting cryovolcanoes on icy moons around other planets. Pieri noted that compared to radio transmission of events like these, "laser comms would up the ante by an order of magnitude."
Clouding the future of lasers
That's not to say the technology is perfect for every scenario. Lasers are subject to more interference from clouds and other atmospheric conditions than radio waves; pointing and timing are also challenges.
Lasers also require ground infrastructure that doesn't yet exist. NASA's Deep Space Network, a system of antenna arrays located across the globe, is based entirely on radio technology. Ground stations would have to be developed that could receive lasers in locations where skies are reliably clear.
Radio technology won't be going away. It works in rain or shine, and will continue to be effective for low-data uses like providing commands to spacecraft.
Next steps
Two upcoming NASA missions will help engineers understand the technical challenges involved in conducting laser communications in space. What they'll learn will advance lasers toward becoming a common form of space communication in the future.
The Laser Communications Relay Demonstration (LCRD), led by NASA's Goddard Space Flight Center in Greenbelt, Maryland, is due to launch in 2019. LCRD will demonstrate the relay of data using laser and radio frequency technology. It will beam laser signals almost 25,000 miles (40,000 kilometers) from a ground station in California to a satellite in geostationary orbit, then relay that signal to another ground station. JPL is developing one of the ground stations at Table Mountain in southern California. Testing laser communications in geostationary orbit, as LCRD will do, has practical applications for data transfer on Earth.
Deep Space Optical Communications (DSOC), led by JPL, is scheduled to launch in 2023 as part of an upcoming NASA Discovery mission. That mission, Psyche, will fly to a metallic asteroid, testing laser comms from a much greater distance than LCRD.
The Psyche mission has been planned to carry the DSOC laser device onboard the spacecraft. Effectively, the DSOC mission will try to hit a bullseye using a deep space laser -- and because of the planet's rotation, it will hit a moving target, as well.
UPDATED AT 10:40 a.m. PST on 2/15/17 to clarify relative data speeds.