9,842 research outputs found
Scaling Law for Baryon Coupling to its Current and its possible applications
The baryon- coupling to its current (), in conventional QCD sum
rule calculations (QCDSR), is shown to scale as the cubic power of the baryon
mass, . Some theoretical justification for it comes from a simple
light-cone model and also general scaling arguments for QCD. But more
importantly, taken as a phenomenological ansatz for the present, this may find
very good use in current explorations of possible applications of QCDSR to
baryon physics both at temperature , and/or density , .Comment: 10 pages, 2 figures, 1 tex picture and 1 ps pictur
Phase transition between non-extremal and extremal Reissner-Nordstr\"om black holes
We discuss the phase transition between non-extremal and extremal
Reissner-Nordstr\"om black holes. This transition is considered as the
limit of the transition between the non-extremal and near-extremal
black holes.
We show that an evaporating process from non-extremal black hole to extremal
one is possible to occur, but its reverse process is not possible to occur
because of the presence of the maximum temperature.
Furthermore, it is shown that the Hawking-Page phase transition between small
and large black holes unlikely occurs in the AdS Reissner-Nordstr\"om black
holes.Comment: 12 pages, 6 figures, version to appear in MPL
Incompressibility of strange matter
Strange stars calculated from a realistic equation of state (EOS), that
incorporate chiral symmetry restoration as well as deconfinement at high
density show compact objects in the mass radius curve. We compare our
calculations of incompressibility for this EOS with that of nuclear matter. One
of the nuclear matter EOS has a continuous transition to ud-matter at about
five times normal density. Another nuclear matter EOS incorporates density
dependent coupling constants. From a look at the consequent velocity of sound,
it is found that the transition to ud-matter seems necessary.Comment: Accepted for publication in Phys Lett
The role of the immune system in brain metastasis
Metastatic brain tumors are the most common brain tumors in adults. With numerous successful advancements in systemic treatment of most common cancer types, brain metastasis is becoming increasingly important in the overall prognosis of cancer patients. Brain metastasis of peripheral tumor is the result of complex interplay of primary tumor, immune system and central nervous system microenvironment. Once formed, brain metastases hide behind the blood brain barrier and become inaccessible to chemotherapies that are otherwise successful in targeting systemic cancer. The approval of immune checkpoint inhibitors for several common cancers such as advanced melanoma and lung cancers brings with it the opportunity and obligation to further understand the mechanisms of immunosuppression by tumors that spread to the brain as well as the interaction between the brain environment and tumor microenvironment. In this review paper we define the central role of the immune system in the development of brain metastases. We performed a comprehensive review of the literature to outline the molecular mechanisms of immunosuppression used by tumors and how the immune system interacts with the central nervous system to facilitate brain metastasis. In particular we discuss the tumor-type-specific mechanisms of metastasis of cancers that preferentially metastasize to the brain as well as the therapies that effectively modulate the immune response, such as immune checkpoint inhibitors and vaccines
A Channel Coding Perspective of Collaborative Filtering
We consider the problem of collaborative filtering from a channel coding
perspective. We model the underlying rating matrix as a finite alphabet matrix
with block constant structure. The observations are obtained from this
underlying matrix through a discrete memoryless channel with a noisy part
representing noisy user behavior and an erasure part representing missing data.
Moreover, the clusters over which the underlying matrix is constant are {\it
unknown}. We establish a sharp threshold result for this model: if the largest
cluster size is smaller than (where the rating matrix is of size
), then the underlying matrix cannot be recovered with any
estimator, but if the smallest cluster size is larger than , then
we show a polynomial time estimator with diminishing probability of error. In
the case of uniform cluster size, not only the order of the threshold, but also
the constant is identified.Comment: 32 pages, 1 figure, Submitted to IEEE Transactions on Information
Theor
Signatures of two-step impurity mediated vortex lattice melting in Bose-Einstein Condensates
We simulate a rotating 2D BEC to study the melting of a vortex lattice in
presence of random impurities. Impurities are introduced either through a
protocol in which vortex lattice is produced in an impurity potential or first
creating the vortex lattice in the absence of random pinning and then cranking
up the (co-rotating) impurity potential. We find that for a fixed strength,
pinning of vortices at randomly distributed impurities leads to the new states
of vortex lattice. It is unearthed that the vortex lattice follow a two-step
melting via loss of positional and orientational order. Also, the comparisons
between the states obtained in two protocols show that the vortex lattice
states are metastable states when impurities are introduced after the formation
of an ordered vortex lattice. We also show the existence of metastable states
which depend on the history of how the vortex lattice is created.Comment: Accepted in Euro. Phys. Let
Born-Infeld black holes coupled to a massive scalar field
Born-Infeld black holes in the Scalar-Tensor Theories of Gravity, in the case
of massless scalar field, have been recently obtained. The aim of the current
paper is to study the effect from the inclusion of a potential for the scalar
field in the theory, through a combination of analytical techniques and
numerical methods. The black holes coupled to a massive scalar field have
richer causal structure in comparison to the massless scalar field case. In the
latter case, the black holes may have a second, inner horizon. The presence of
potential for the scalar field allows the existence of extremal black holes for
certain values of the mass of the scalar field and the magnetic (electric)
charge of the black hole. The linear stability against spherically symmetric
perturbations is studied. Arguments in favor of the general stability of the
solutions coming from the application of the "turning point" method are also
presented.Comment: 26 pages, 16 figure
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