Narrow Results

This paper defines a new concurrent logic language, Nested Guarded Horn Clauses (NGHC). The main new feature of the language is its concept of guard. In fact, an NGHC clause has several layers of (standard) guards. This syntactic innovation allows the definition of a complete (i.e. always applicable) set of unfolding rules and therefore of an unfolding semantics which is equivalent, with respect to the success set, to the operational semantics. A fixpoint semantics is also defined in the classic logic programming style and is proved equivalent to the unfolding one. Since it is possible to embed Flat GHC into NGHC, our method can be used to give a fixpoint semantics to FGHC as well.

The measurement of the transverse momentum of W bosons in hadron collisions provides not only an important test of quantum chromodynamic (QCD) calculations, but also is a crucial input for the precision measurement of the W boson mass. While the measurement of the Z boson transverse momentum is experimentally well under control, the available unfolding techniques for the W boson final states lead generically to relatively large uncertainties. In this paper, we present a new methodology to estimate the W boson transverse momentum spectrum, significantly improving the systematic uncertainties of current approaches.

In this paper we describe RooFitUnfold, an extension of the RooFit statistical software package to treat unfolding problems, and which includes most of the unfolding methods that commonly used in particle physics. The package provides a common interface to these algorithms as well as common uniform methods to evaluate their performance in terms of bias, variance and coverage. In this paper we exploit this common interface of RooFitUnfold to compare the performance of unfolding with the Richardson–Lucy, Iterative Dynamically Stabilized, Tikhonov, Gaussian Process, bin-by-bin and inversion methods on several example problems.

In this paper, we study the top quark pair events production in pp collisions in the $\ell +\mathrm{\text{jets}}$ channel at the energy of $\sqrt{s}=14$ TeV for Standard Model as well as new physics processes. We explore the usage of semi-boosted topologies where the top quark decays into a high-transverse momentum (boosted) hadronic W-jet and an isolated b-jet and study their performance in the $t\bar{t}$ events kinematic reconstruction. An important event fraction is recovered and the correlation of selected kinematic variables between the detector and particle level is studied. Quality of the reconstructed mass line shape of a hypothetical scalar resonance decaying into $t\bar{t}$ is evaluated and compared for regimes of a different degree of the transverse boost. Unfolding performance is checked in terms of comparing the excess of events in spectra before and after the unfolding, concluding with the proof of a signal significance loss after the unfolding procedure for both energy and angle related observables, with possible applications for current LHC experiments.

Modern field programmable gate arrays (FPGAs) offer built in support for efficient implementation of signal processing algorithms in the form of specialized embedded blocks such as high speed carry chains, specialized shift registers, adders, multiply accumulators (MAC) and block memories. These dedicated elements provide increased computational power and are used for efficient implementation of computationally extensive algorithms. This paper proposes a novel algorithm and architecture for the design and implementation of high performance intermediate frequency (IF) filters on FPGAs. In this research, we have proposed innovative design methodologies for generation of optimal feed forward and recursive architectures to be mapped on a family of FPGAs. Keeping in perspective the limited number of registers within the embedded blocks, the new methodology applies transformations to achieve higher throughput by applying various optimizations to the design algorithm. Implementation options include systolic MAC, transpose direct form MAC, canonic signed digit and distributed arithmetic based filters to suite the most economical FPGA implementation. The paper demonstrates the methodology and shows its applicability by synthesizing the designs and comparing the results to a number of traditional architectures and intellectual property cores. Using Xilinx Virtex-5 FPGA, our results show a throughput improvement between 7% and 30% with an average improvement of 16% over traditional implementations of these designs.

I review the early (1885–1975) and more recent history of dynamical systems theory, identifying key principles and themes, including those of dimension reduction, normal form transformation and unfolding of degenerate cases. I end by briefly noting recent extensions and applications in nonlinear fluid and solid mechanics, with a nod toward mathematical biology. I argue throughout that this essentially mathematical theory was largely motivated by nonlinear scientific problems, and that after a long gestation it is propagating throughout the sciences and technology.

The dynamics of a system defined by an endomorphism is essentially different from that of a system defined by a diffeomorphism due to interaction of invariant objects with the so-called critical locus. A planar endomorphism typically folds the phase space along curves J₀ where the Jacobian of the map is singular. The critical locus, denoted J₁, is the image of J₀. It is often only piecewise smooth due to the presence of isolated cusp points that are persistent under perturbation. We investigate what happens when the stable set W_s of a fixed point or periodic orbit interacts with J₁ near such a cusp point C₁. Our approach is in the spirit of bifurcation theory, and we classify the different unfoldings of the codimension-two singularity where the curve W_s is tangent to J₁ exactly at C₁. The analysis uses a local normal-form setup that identifies the possible local phase portraits. These local phase portraits give rise to different global manifestations of the behavior as organized by five different global bifurcation diagrams.

This paper presents results concerning bifurcations of 2D piecewise-smooth vector fields. In particular, the generic unfoldings of codimension-three fold–saddle singularities of Filippov systems, where a boundary-saddle and a fold coincide, are considered and the bifurcation diagrams exhibited.

Given an $m$-parameterized family of $n$-dimensional vector fields, with an equilibrium point with linearization of eigenvalue zero with algebraic multiplicity $k$, with $k\le m$, and geometric multiplicity one, our goal in this paper is to find sufficient conditions for the family of vector fields such that the dynamics on the $k$-dimensional $m$-parameterized center manifold around the equilibrium point becomes locally topologically equivalent to a given unfolding. Finally, the result is applied to the study of the Rössler system.

We consider the problems of straightening polygonal trees and convexifying polygons by continuous motions such that rigid edges can rotate around vertex joints and no edge crossings are allowed. A tree can be straightened if all its edges can be aligned along a common straight line such that each edge points "away" from a designated leaf node. A polygon can be convexified if it can be reconfigured to a convex polygon. A lattice tree (resp. polygon) is a tree (resp. polygon) containing only edges from a square or cubic lattice. We first show that a 2D lattice chain or a 3D lattice tree can be straightened efficiently in O(n) moves and time, where n is the number of tree edges. We then show that a 2D lattice tree can be straightened efficiently in O(n²) moves and time. Furthermore, we prove that a 2D lattice polygon or a 3D lattice polygon with simple shadow can be convexified efficiently in O(n) moves and in O(n log n) time. Finally, we show that two special classes of diameter-4 trees in two dimensions can always be straightened.

The interfacial surface activity of a protein, ovalbumin (OVA) at bare air/water interface in presence and also in absence of electrolyte (KCl) in subphase has been investigated. The surface activity was measured as a function of time. It has been found that, the presence of KCl in aqueous subphase enhances the adsorption rate of the protein. The changes of area/molecule, compressibility, rigidity and unfolding of OVA are trivial up to 10 mM KCl concentration. These properties of OVA, above 10 mM KCl concentration are significant and have been explained in the perspective of DLVO theory and many-body ion–protein dispersion potentials. The presence of high concentration of electrolyte increases the β-structure of OVA, resulting into larger unfolding as well as larger intermolecular aggregates. The overall study indicates that KCl perturbs the OVA monolayer.

We define the coordinate equations of killing magnetic curves $\gamma (s)$ in ${ℝ}_1^3$ with the magnetic vector field $V$ under the frame $\{{\gamma }^{\prime }(s),V,V\wedge {\gamma }^{\prime }(s)\}$. In particular, this yields to describe the geometrical properties and singularities of the magnetic curves and the magnetic normal binormal surfaces. Meanwhile, we establish the relationships between singularity types of the magnetic normal binormal surfaces and geometrical invariants of the magnetic curves. As an application, we give an example to explain the main results in this paper, where we give the classification of singularity types of the magnetic curves.

We reconstruct the Cartan Equations of null Killing magnetic curve $\gamma (s)$ in ${ℝ}_1^3$ with Killing magnetic vector field $V$ under the new Cartan frame $\{{\gamma }^{\prime }(s),V\wedge {\gamma }^{\prime }(s),V^{\prime }\wedge {\gamma }^{\prime }(s)-V\}$, which describe some new geometrical properties of $\gamma (s)$. The singularity properties of the rectifying surfaces and the binormal osculating surfaces of null Killing magnetic curves are given. As an application, two examples are given to explain the main results, where the singular loci of null Killing magnetic curves are obtained.

Recent NMR structural and dynamical data on partially folded forms of mono-heme cytochrome c provide a unifying picture of the behavior of the protein far from the native conditions and suggest useful hints to explain the redox dependent stability of the protein. A fragile hinge in the structure of mitochondrial cytochrome c is identified, which may not have correspondents in smaller type-1 cytochromes. Former spectroscopic and kinetic data are here discussed in terms of this new view.