3,534 research outputs found
Compact surfaces with no Bonnet mate
This note gives sufficient conditions (isothermic or totally nonisothermic)
for an immersion of a compact surface to have no Bonnet mate.Comment: 7 pages, LaTeX2
Closed trajectories of a particle model on null curves in anti-de Sitter 3-space
We study the existence of closed trajectories of a particle model on null
curves in anti-de Sitter 3-space defined by a functional which is linear in the
curvature of the particle path. Explicit expressions for the trajectories are
found and the existence of infinitely many closed trajectories is proved.Comment: 12 pages, 1 figur
Binary trees, coproducts, and integrable systems
We provide a unified framework for the treatment of special integrable
systems which we propose to call "generalized mean field systems". Thereby
previous results on integrable classical and quantum systems are generalized.
Following Ballesteros and Ragnisco, the framework consists of a unital algebra
with brackets, a Casimir element, and a coproduct which can be lifted to higher
tensor products. The coupling scheme of the iterated tensor product is encoded
in a binary tree. The theory is exemplified by the case of a spin octahedron.Comment: 15 pages, 6 figures, v2: minor correction in theorem 1, two new
appendices adde
Excursion Sets and Non-Gaussian Void Statistics
Primordial non-Gaussianity (NG) affects the large scale structure (LSS) of
the universe by leaving an imprint on the distribution of matter at late times.
Much attention has been focused on using the distribution of collapsed objects
(i.e. dark matter halos and the galaxies and galaxy clusters that reside in
them) to probe primordial NG. An equally interesting and complementary probe
however is the abundance of extended underdense regions or voids in the LSS.
The calculation of the abundance of voids using the excursion set formalism in
the presence of primordial NG is subject to the same technical issues as the
one for halos, which were discussed e.g. in arXiv:1005.1203. However, unlike
the excursion set problem for halos which involved random walks in the presence
of one barrier , the void excursion set problem involves two barriers
and . This leads to a new complication introduced by what
is called the "void-in-cloud" effect discussed in the literature, which is
unique to the case of voids. We explore a path integral approach which allows
us to carefully account for all these issues, leading to a rigorous derivation
of the effects of primordial NG on void abundances. The void-in-cloud issue in
particular makes the calculation conceptually rather different from the one for
halos. However, we show that its final effect can be described by a simple yet
accurate approximation. Our final void abundance function is valid on larger
scales than the expressions of other authors, while being broadly in agreement
with those expressions on smaller scales.Comment: 28 pages (18+appendices), 7 figures; v2 -- minor changes in sec 3.2,
version published in PR
Halo statistics in non-Gaussian cosmologies: the collapsed fraction, conditional mass function, and halo bias from the path-integral excursion set method
Characterizing the level of primordial non-Gaussianity (PNG) in the initial
conditions for structure formation is one of the most promising ways to test
inflation and differentiate among different scenarios. The scale-dependent
imprint of PNG on the large-scale clustering of galaxies and quasars has
already been used to place significant constraints on the level of PNG in our
observed Universe. Such measurements depend upon an accurate and robust theory
of how PNG affects the bias of galactic halos relative to the underlying matter
density field. We improve upon previous work by employing a more general
analytical method - the path-integral extension of the excursion set formalism
- which is able to account for the non-Markovianity caused by PNG in the
random-walk model used to identify halos in the initial density field. This
non-Markovianity encodes information about environmental effects on halo
formation which have so far not been taken into account in analytical bias
calculations. We compute both scale-dependent and -independent corrections to
the halo bias, along the way presenting an expression for the conditional
collapsed fraction for the first time, and a new expression for the conditional
halo mass function. To leading order in our perturbative calculation, we
recover the halo bias results of Desjacques et. al. (2011), including the new
scale-dependent correction reported there. However, we show that the
non-Markovian dynamics from PNG can lead to marked differences in halo bias
when next-to-leading order terms are included. We quantify these differences
here. [abridged]Comment: Accepted for publication in MNRAS. Includes minor revisions
recommended by referee, slightly revised notation for clarity, and corrected
typo
Stringy Instantons in SU(N) N=2 Non-Conformal Gauge Theories
In this paper we explicitly obtain the leading corrections to the SU(N) N=2
prepotential due to stringy instantons both in flat space-time and in the
presence of a non-trivial graviphoton background field. We show that the
stringy corrections to the prepotential are expressible in terms of the
elementary symmetric polynomials. For N>2 the theory is not conformal; we
discuss the introduction of an explicit dependence on the string scale \alpha'
in the low-energy effective action through the stringy non-perturbative sector.Comment: 22 pages, 1 figur
TA treatment of depression : a hermeneutic single-case efficacy design study - ‘Caterina’
This study is the second of a series of seven, and
belongs to the second Italian systematic replication of
findings from two previous series (Widdowson 2012a,
2012b, 2012c, 2013; Benelli, 2016a, 2016b, 2016c) that
investigated the effectiveness of a manualised
transactional analysis treatment for depression through
Hermeneutic Single-Case Efficacy Design. The therapist
was a white Italian woman with 10 years of clinical
experience and the client, Caterina, was a 28-year old
white Italian woman who attended 16 sessions of
transactional analysis psychotherapy. Caterina satisfied
DSM-5 criteria for major depressive disorder with
generalized anxiety disorder. The conclusion of the
judges was that this was an outstanding good-outcome
case: the depressive symptoms showed an early clinical
and reliable improvement, maintained till the 6 months
follow-up, accompanied by reductions in anxiety
symptoms, global distress and severity of personal
problems. Adherence to the manualised treatment for
depression appears good to excellent. In this case study,
transactional analysis treatment for depression has
proven its efficacy in treating major depressive disorder
in comorbidity with anxiety disorder
Retrospective Proteomic Screening of 100 Breast Cancer Tissues
The present investigation has been conducted on one hundred tissue fragments of breast cancer, collected and immediately cryopreserved following the surgical resection. The specimens were selected from patients with invasive ductal carcinoma of the breast, the most frequent and potentially aggressive type of mammary cancer, with the objective to increase the knowledge of breast cancer molecular markers potentially useful for clinical applications. The proteomic screening; by 2D-IPG and mass spectrometry; allowed us to identify two main classes of protein clusters: proteins expressed ubiquitously at high levels in all patients; and proteins expressed sporadically among the same patients. Within the group of ubiquitous proteins, glycolytic enzymes and proteins with anti-apoptotic activity were predominant. Among the sporadic ones, proteins involved in cell motility, molecular chaperones and proteins involved in the detoxification appeared prevalent. The data of the present study indicates that the primary tumor growth is reasonably supported by concurrent events: the inhibition of apoptosis and stimulation of cellular proliferation, and the increased expression of glycolytic enzymes with multiple functions. The second phase of the evolution of the tumor can be prematurely scheduled by the occasional presence of proteins involved in cell motility and in the defenses of the oxidative stress. We suggest that this approach on large-scale 2D-IPG proteomics of breast cancer is currently a valid tool that offers the opportunity to evaluate on the same assay the presence and recurrence of individual proteins, their isoforms and short forms, to be proposed as prognostic indicators and susceptibility to metastasis in patients operated on for invasive ductal carcinoma of the breast
A Simple Operator Check of the Effective Fermion Mode Function during Inflation
We present a relatively simple operator formalism which reproduces the
leading infrared logarithm of the one loop quantum gravitational correction to
the fermion mode function on a locally de Sitter background. This rule may
serve as the basis for an eventual stochastic formulation of quantum gravity
during inflation. Such a formalism would not only effect a vast simplification
in obtaining the leading powers of at fixed loop orders, it would also
permit us to sum the series of leading logarithms. A potentially important
point is that our rule does not seem to be consistent with any simple infrared
truncation of the fields. Our analysis also highlights the importance of spin
as a gravitational interaction that persists even when kinetic energy has
redshifted to zero.Comment: 39 pages, no figuire.(1) New version has clarified the ultimate
motivation by adding sentences to the abstract and to the penultimate
paragraph of the introduction. (2) By combining a number of references and
equations we have managed to reduce the length by 2 page
Lagrangian Curves in a 4-dimensional affine symplectic space
Lagrangian curves in R4 entertain intriguing relationships with second order deformation of plane curves under the special affine group and null curves in a 3-dimensional Lorentzian space form. We provide a natural affine symplectic frame for Lagrangian curves. It allows us to classify La- grangrian curves with constant symplectic curvatures, to construct a class of Lagrangian tori in R4 and determine Lagrangian geodesic
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