476 research outputs found
An algebro-geometric proof of Witten's conjecture
We present a new proof of Witten's conjecture. The proof is based on the
analysis of the relationship between intersection indices on moduli spaces of
complex curves and Hurwitz numbers enumerating ramified coverings of the
2-sphere.Comment: 12 pages, no figure
A 14-day ground-based hypokinesia study in nonhuman primates: A compilation of results
A 14 day ground based hypokinesia study with rhesus monkeys was conducted to determine if a spaceflight of similar duration might affect bone remodeling and calcium homeostatis. The monkeys were placed in total body casts and sacrificed either immediately upon decasting or 14 days after decasting. Changes in vertebral strength were noted and further deterioration of bone strength continued during the recovery phase. Resorption in the vertebrae increased dramatically while formation decreased. Cortical bone formation was impaired in the long bones. The immobilized animals showed a progressive decrease in total serum calcium which rebounded upon remobilization. Most mandibular parameters remained unchanged during casting except for retardation of osteon birth or maturation rate and density distribution of matrix and mineral moieties
Attenuated total reflection-FT-IR spectroscopic imaging of protein crystallization
Protein crystallization is of strategic and commercial relevance in the post-genomic era because of its pivotal role in structural proteomics projects. Although protein structures are crucial for understanding the function of proteins and to the success of rational drug design and other biotechnology applications, obtaining high quality crystals is a major bottleneck to progress. The major means of obtaining crystals is by massive-scale screening of a target protein solution with numerous crystallizing agents. However, when crystals appear in these screens, one cannot easily know if they are crystals of protein, salt, or any other molecule that happens to be present in the trials. We present here a method based on Attenuated Total Reflection (ATR)-FT-IR imaging that reliably identifies protein crystals through a combination of chemical specificity and the visualizing capability of this approach, thus solving a major hurdle in protein crystallization. ATR-FT-IR imaging was successfully applied to study the crystallization of thaumatin and lysozyme in a high-throughput manner, simultaneously from six different solutions. This approach is fast as it studies protein crystallization in situ and provides an opportunity to examine many different samples under a range of conditions
From Hurwitz numbers to Kontsevich-Witten tau-function: a connection by Virasoro operators
In this letter,we present our conjecture on the connection between the
Kontsevich--Witten and the Hurwitz tau-functions. The conjectural formula
connects these two tau-functions by means of the group element. An
important feature of this group element is its simplicity: this is a group
element of the Virasoro subalgebra of . If proved, this conjecture
would allow to derive the Virasoro constraints for the Hurwitz tau-function,
which remain unknown in spite of existence of several matrix model
representations, as well as to give an integrable operator description of the
Kontsevich--Witten tau-function.Comment: 13 page
Models of Neutrino Masses and Baryogenesis
Majorana masses of the neutrino implies lepton number violation and is
intimately related to the lepton asymmetry of the universe, which gets related
to the baryon asymmetry of the universe in the presence of the sphalerons
during the electroweak phase transition. Assuming that the baryon asymmetry of
the universe is generated before the electroweak phase transition, it is
possible to dicriminate different classes of models of neutrino masses. While
see-saw mechanism and the triplet higgs mechanism are preferred, the Zee-type
radiative models and the R-parity breaking models requires additional inputs to
generate baryon asymmetry of the universe during the electroweak phase
transition.Comment: 27 pages including 5 figures; Review article for Pramana: the Indian
Journal of Physic
High Resolution CO Imaging of the Molecular Disk around the jets in KjPN 8
We report high resolution (2.5 arcsec) CO J=1-0 line imaging which confirms
the presence of a molecular disk around the origin of the spectacular, 14
arcmin times 4 arcmin, episodic jets in the planetary nebula KjPn 8. The disk
is 30 arcsec in diameter with an expansion velocity of approximately 7 km/s.
The axis of the disk is aligned with the youngest and fastest (approximately
300 km/s) of the bipolar jets, and there is evidence for interaction between
the jets and the disk material. The inner 4 arcsec of the disk are
photo-ionized by the central star. The disk-jet system dominates the
environment of this young nebula, and should govern the morphology of KjPn 8 as
it evolves to become fully ionized.Comment: 15 pages, 4 figures, accepted for publication in Astrophysical
Journal Letter
Baryogenesis through R-parity violation
We consider generation of baryon asymmetry of the universe through parity
violation in a scenario in which out-of-equilibrium condition is satisfied by
making the electroweak phase transition to be first order. We study all the
parity violating interaction which can generate asymmetry which
then converts to baryon asymmetry of the universe. We demonstrate that
CP--violating sfermion deudy all the parity violating interaction which can
generate asymmetry which then converts to baryon asymmetry of the
universe. We demonstrate that CP--violating sfermion decays contribute more
than that of the neutralino decays in the generation of asymmetry.Comment: 25 pages latex file (containing six eps files
BGWM as Second Constituent of Complex Matrix Model
Earlier we explained that partition functions of various matrix models can be
constructed from that of the cubic Kontsevich model, which, therefore, becomes
a basic elementary building block in "M-theory" of matrix models. However, the
less topical complex matrix model appeared to be an exception: its
decomposition involved not only the Kontsevich tau-function but also another
constituent, which we now identify as the Brezin-Gross-Witten (BGW) partition
function. The BGW tau-function can be represented either as a generating
function of all unitary-matrix integrals or as a Kontsevich-Penner model with
potential 1/X (instead of X^3 in the cubic Kontsevich model).Comment: 42 page
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