261 research outputs found
Privacy Preserving Auction Based Virtual Machine Instances Allocation Scheme for Cloud Computing Environment
Cloud Computing Environment provides computing resources in the form of Virtual Machines (VMs), to the cloud users through Internet. Auction-based VM instances allocation allows different cloud users to participate in an auction for a bundle of Virtual Machine instances where the user with the highest bid value will be selected as the winner by the auctioneer (Cloud Service Provider) to gain more. In this auction mechanism, individual bid values are revealed to the auctioneer in order to select the winner as a result of which privacy of bid values are lost. In this paper, we proposed an auction scheme to select the winner without revealing the individual bid values to the auctioneer to maintain privacy of bid values. The winner will get the access to the bundle of VM instances. This  scheme relies on a set of cryptographic protocols including Oblivious Transfer (OT) protocol and Yao’s protocol to maintain privacy of bid values
Determination of the Weak Axial Vector Coupling from a Measurement of the Beta-Asymmetry Parameter A in Neutron Beta Decay
We report on a new measurement of the neutron beta-asymmetry parameter
with the instrument \perkeo. Main advancements are the high neutron
polarization of from a novel arrangement of super mirror
polarizers and reduced background from improvements in beam line and shielding.
Leading corrections were thus reduced by a factor of 4, pushing them below the
level of statistical error and resulting in a significant reduction of
systematic uncertainty compared to our previous experiments. From the result
, we derive the ratio of the axial-vector to the vector
coupling constant Comment: 5 pages, 4 figure
On V_ud determination from kaon decays
The pion beta decay pi^+ -> pi^0 e^+ nu proceeds through pure weak vector
hadronic currents and, therefore, the theoretical prediction for it is more
reliable than for the processes with axial-vector current contribution. For
example, recently the pion beta decay has been used for V_ud determination. The
main aim of this letter is to point that kaon beta decay K^0 -> K^+(pi^+ pi^0)
e^- nu-bar analogously can be used for this purpose.Comment: 3 pages, no figures, one reference adde
An alternative to the gauge theoretic setting
The standard formulation of gauge theories results from the Lagrangian
(functional integral) quantization of classical gauge theories. A more
intrinsic qunantum theoretical access in the spirit of Wigner's representation
theory shows that there is a fundamental clash between the pointlike
localization of zero mass (vector, tensor) potentials and the Hilbert space
(positivity, unitarity) structure of QT. The quantization approach has no other
way than to stay with pointlike localization and sacrifice the Hilbert space
whereas the approach build on the intrinsic quantum concept of modular
localization keeps the Hilbert space and trades the conflict creating pointlike
generation with the tightest consistent localization:: semiinfinite spacelike
string localization. Whereas these potentials in the presence of interactions
stay quite close to associated pointlike field strength, the interacting matter
fields to which they are coupled bear the brunt of the nonlocal aspect in that
they are string.generated in a way which cannot be undone by any
differentiation. The new stringlike approach to gauge theory also revives the
idea of a Schwinger-Higgs screening mechanism as a deeper and less metaphoric
description of the Higgs spontaneous symmetry breaking and its accompanying
tale about "God's particle" and its mass generation for all other particles.Comment: 26 page
Mixing of mineral dust with urban pollution aerosol over Dakar (Senegal): Impact on dust physico-chemical and radiative properties.
In the framework of the Saharan Mineral Dust Experiment (SAMUM) in 2008, the mixing of the urban pollution
plume of Dakar (Senegal) with mineral dust was studied in detail using the German research aircraft Falcon which was
equipped with a nadir-looking high spectral resolution lidar (HSRL) and extensive aerosol in situ instrumentation. The
mineral dust layer as well as the urban pollution plume were probed remotely by the HSRL and in situ. Back trajectory
analyses were used to attribute aerosol samples to source regions.We found that the emission from the region of Dakar
increased the aerosol optical depth (532 nm) from approximately 0.30 over sea and over land east of Dakar to 0.35 in the city outflow. In the urban area, local black carbon (BC) emissions, or soot respectively, contributed more than 75% to aerosol absorption at 530 nm. In the dust layer, the single-scattering albedo at 530 nm was 0.96 � 0.99, whereas
we found a value of 0.908 �± 0.018 for the aerosol dominated by urban pollution. After 6h of transport over the North
Atlantic, the externally mixed mode of secondary aerosol particles had almost completely vanished, whereas the BC
agglomerates (soot) were still externally mixed with mineral dust particles
Warped Convolutions, Rieffel Deformations and the Construction of Quantum Field Theories
Warped convolutions of operators were recently introduced in the algebraic
framework of quantum physics as a new constructive tool. It is shown here that
these convolutions provide isometric representations of Rieffel's strict
deformations of C*-dynamical systems with automorphic actions of R^n, whenever
the latter are presented in a covariant representation. Moreover, the device
can be used for the deformation of relativistic quantum field theories by
adjusting the convolutions to the geometry of Minkowski space. The resulting
deformed theories still comply with pertinent physical principles and their
Tomita-Takesaki modular data coincide with those of the undeformed theory; but
they are in general inequivalent to the undeformed theory and exhibit different
physical interpretations.Comment: 34 page
A Chern-Simons approach to Galilean quantum gravity in 2+1 dimensions
We define and discuss classical and quantum gravity in 2+1 dimensions in the
Galilean limit. Although there are no Newtonian forces between massive objects
in (2+1)-dimensional gravity, the Galilean limit is not trivial. Depending on
the topology of spacetime there are typically finitely many topological degrees
of freedom as well as topological interactions of Aharonov-Bohm type between
massive objects. In order to capture these topological aspects we consider a
two-fold central extension of the Galilei group whose Lie algebra possesses an
invariant and non-degenerate inner product. Using this inner product we define
Galilean gravity as a Chern-Simons theory of the doubly-extended Galilei group.
The particular extension of the Galilei group we consider is the classical
double of a much studied group, the extended homogeneous Galilei group, which
is also often called Nappi-Witten group. We exhibit the Poisson-Lie structure
of the doubly extended Galilei group, and quantise the Chern-Simons theory
using a Hamiltonian approach. Many aspects of the quantum theory are determined
by the quantum double of the extended homogenous Galilei group, or Galilei
double for short. We study the representation theory of the Galilei double,
explain how associated braid group representations account for the topological
interactions in the theory, and briefly comment on an associated
non-commutative Galilean spacetime.Comment: 38 pages, 1 figure, references update
Tensionless strings, correspondence with SO(D,D) sigma model
String theory with perimeter action is tensionless by its geometrical nature
and has pure massless spectrum of higher spin gauge particles. I demonstrate
that liner transformation of the world-sheet fields defines a map to the
SO(D,D) sigma model equipped by additional Abelian constraint, which breaks
SO(D,D) to a diagonal SO(1,D-1). The effective tension is equal to the square
of the dimensional coupling constant of the perimeter action. This
correspondence allows to view the perimeter action as a "square root" of the
Nambu-Goto area action. The aforementioned map between tensionless strings and
SO(D,D) sigma model allows to introduce the vertex operators in full analogy
with the standard string theory and to confirm the form of the vertex operators
introduced earlier.Comment: Latex, 9 page
Topological data analysis quantifies biological nano-structure from single molecule localization microscopy
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