76 research outputs found
Baryons and Mesons with Beauty
Recent experimental findings of several mesons and baryons with "beauty" and
"charm" as flavors remind us of the days when strangeness was discovered, and
how its inclusion led to SU(3)-flavor symmetry with enormous success in the
classification of the "proliferated" states into SU(3) multiplets. One of the
key elements was the successful application of the first order perturbation in
symmetry breaking, albeit what then appeared to be huge mass differences, and
the prediction of new states that were confirmed by experiments. In this note,
we venture into the past and, applying the same techniques, predict some new
"beauty-" and "charm-" flavored hadrons. If these new states are confirmed
experimentally, it may provide a useful phenomenological model for classifying
numerous states that are found to be in the PDG data and could invite further
theoretical challenges towards our understanding of symmetry breaking.Comment: 9 pages, 5 figures, plain Late
A Systems Biology Approach towards Deciphering the Unfolded Protein Response in Huntington's Disease
Although the disease causing gene huntingtin has been known for some time, the exact cause of neuronal cell death during _Huntington's disease_ (HD) remains unknown. One potential mechanism contributing to the massive loss of neurons in HD brains might be the _Unfolded Protein Response_ (UPR) which is activated by accumulation of misfolded proteins in the endoplasmic reticulum (ER). As an adaptive response, UPR upregulates transcription of chaperones, temporarily attenuating new translation and activates protein degradation via the proteasome. However, at high levels of ER stress, UPR signalling can contribute to neuronal apoptosis.

Our primary aims include (a) construction of the UPR signalling network, (b) curation and bioinformatical identification of UPR target genes and finally (c) examination of HD gene expression data sets for UPR transcriptional signatures and differential regulation of UPR pathways.

The UPR signalling pathway is reconstructed based on literature review and using the "Unified Interactome database":http://www.unihi.org. Lists of UPR target genes detected by previous experiments or as predicted by computational analysis are compiled. This allows us to perform enrichment analysis for differential HD gene expression and to assess whether UPR expression signatures are prominent during HD pathogenesis.

Results: The canonical UPR pathway is complemented with additional protein interaction data allowing us to assess its embedding into the cellular context and to identify potential modifiers as well as novel drug targets.

Conclusions: The in depth systems biology analysis can give us valuable insights about the involvement of the UPR in HD.

Numerical solution of the Lyapunov equation by approximate power iteration
AbstractWe present the approximate power iteration (API) algorithm for the computation of the dominant invariant subspace of the solution X of large-order Lyapunov equations AX + XAT + Q = 0 without first computing the matrix X itself. The API algorithm is an iterative procedure that uses Krylov subspace bases in computing estimates of matrix-vector products Xv in a power iteration sequence. Application of the API algorithm requires that A + AT < 0; numberical experiments indicate that, if the matrix X admits a good low-rank solution, then API provides an orthogonal basis of a subspace that closely approximates the dominant X-invariant subspace of corresponding dimension. Analytical convergence results are also presented
Wasserstein Distributionally Robust Look-Ahead Economic Dispatch
We consider the problem of look-ahead economic dispatch (LAED) with uncertain
renewable energy generation. The goal of this problem is to minimize the cost
of conventional energy generation subject to uncertain operational constraints.
The risk of violating these constraints must be below a given threshold for a
family of probability distributions with characteristics similar to observed
past data or predictions. We present two data-driven approaches based on two
novel mathematical reformulations of this distributionally robust decision
problem. The first one is a tractable convex program in which the uncertain
constraints are defined via the distributionally robust
conditional-value-at-risk. The second one is a scalable robust optimization
program that yields an approximate distributionally robust chance-constrained
LAED. Numerical experiments on the IEEE 39-bus system with real solar
production data and forecasts illustrate the effectiveness of these approaches.
We discuss how system operators should tune these techniques in order to seek
the desired robustness-performance trade-off and we compare their computational
scalability
SU(5) grand unification on a domain-wall brane from an E_6-invariant action
An SU(5) grand unification scheme for effective 3+1-dimensional fields
dynamically localised on a domain-wall brane is constructed. This is achieved
through the confluence of the clash-of-symmetries mechanism for symmetry
breaking through domain-wall formation, and the Dvali-Shifman gauge-boson
localisation idea. It requires an E_6 gauge-invariant action, yielding a
domain-wall solution that has E_6 broken to differently embedded SO(10) x U(1)
subgroups in the two bulk regions on opposite sides of the wall. On the wall
itself, the unbroken symmetry is the intersection of the two bulk subgroups,
and contains SU(5). A 4+1-dimensional fermion family in the 27 of E_6 gives
rise to localised left-handed zero-modes in the 5^* + 10 + 1 + 1 representation
of SU(5). The remaining ten fermion components of the 27 are delocalised exotic
states, not appearing in the effective 3+1-dimensional theory on the
domain-wall brane. The scheme is compatible with the type-2 Randall-Sundrum
mechanism for graviton localisation; the single extra dimension is infinite.Comment: 21 pages, 9 figures. Minor changes to text and references. To appear
in Phys. Rev.
Light-Heavy Symmetry: Geometric Mass Hierarchy for Three Families
The Universal Seesaw pattern coupled with a LightHeavy
symmetry principle leads to the Diophantine equation , where and distinct. Its unique non-trivial
solution gives rise to the geometric mass hierarchy ,
, for fermion families. This is realized in
a model where the hybrid (yet UpDown symmetric) quark mass
relations play a
crucial role in expressing the CKM mixings in terms of simple mass ratios,
notably .Comment: 12 pages, no figures, Revtex fil
Images of Energy
Six members of the Syracuse community discuss energy as it is understood in the fields of psychology, graphic arts, biology, architecture, physics, and literature. Professor Weissman provides an overview
Robust Control of Linear Time-Invariant Plants Using Periodic Compensation
©1985 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.This paper considers the use and design of linear periodic time-varying controllers for the feedback control of linear time-invariant discrete-time plants. We will show that for a large class of robustness problems, periodic compensators are superior to time-invariant ones. We will give explicit design techniques which can be easily implemented. In the context of periodic controllers, we also consider the strong and simultaneous stabilization problems. Finally, we show that for the problem of weighted sensitivity minimization for linear time-invariant plants, time-varying controllers offer no advantage over the time-invariant ones
Chiral spinors and gauge fields in noncommutative curved space-time
The fundamental concepts of Riemannian geometry, such as differential forms,
vielbein, metric, connection, torsion and curvature, are generalized in the
context of non-commutative geometry. This allows us to construct the
Einstein-Hilbert-Cartan terms, in addition to the bosonic and fermionic ones in
the Lagrangian of an action functional on non-commutative spaces. As an
example, and also as a prelude to the Standard Model that includes
gravitational interactions, we present a model of chiral spinor fields on a
curved two-sheeted space-time with two distinct abelian gauge fields. In this
model, the full spectrum of the generalized metric consists of pairs of tensor,
vector and scalar fields. They are coupled to the chiral fermions and the gauge
fields leading to possible parity violation effects triggered by gravity.Comment: 50 pages LaTeX, minor corrections and references adde
SN 1993J in M81: optical photometry and spectrophotometery during the first two months
CCD photometric and spectrophotometric data on the type IIb supernova 1993J in M 81 (NGC 3031) obtained from Vainu Bappu Observatory, Kavalur, during the first two months since the outburst are reported. The evolution of the spectrum is described. The evolution of the velocity of P-Cygni absorption dips due to different lines is presented. The photospheric temperature and radius are determined using blackbody fits to BVRIJHK photometry after correcting for interstellar extinction and contribution to the band by the net line emission. The evolution of photospheric radius implies a density variation in the progenitor ρ∝r−n with n=5-6 during the rise to the second maximum reducing to n=2 soon after. These values are comparable to the corresponding values for SN1987A. An application of the expanding photosphere method yields a distance of 2.2-5.1 Mpc for the range of E(B-V)=0.08-0.32, and the atmospheric dilution factor ζ=0-0.4. The distance estimates with the assumption of low reddening and low dilution as well as moderate reddening and moderate dilution are both consistent with the Hubble Space Telescope (HST) Cepheid distance to M 81 (3.6±0.3 Mpc)
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