Studying Diquark Structure of Heavy Baryons in Relativistic Heavy Ion Collisions

We propose the enhancement of $\Lambda_c$ yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon plasma produced in these collisions as well as in the $\Lambda_c$. Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of $\Lambda_c$ would be increased by two-body collisions between $ud$ diquarks and $c$ quarks, in addition to normal three-body collisions among $u$, $d$ and $c$ quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks to $\Lambda_c$ production indeed leads to a substantial enhancement of the $\Lambda_c/D$ ratio in heavy ion collisions.Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics (Chiral07), Nov. 13-16, 2007, Osaka, Japa

Chaos at the border of criticality

The present paper points out to a novel scenario for formation of chaotic attractors in a class of models of excitable cell membranes near an Andronov-Hopf bifurcation (AHB). The mechanism underlying chaotic dynamics admits a simple and visual description in terms of the families of one-dimensional first-return maps, which are constructed using the combination of asymptotic and numerical techniques. The bifurcation structure of the continuous system (specifically, the proximity to a degenerate AHB) endows the Poincare map with distinct qualitative features such as unimodality and the presence of the boundary layer, where the map is strongly expanding. This structure of the map in turn explains the bifurcation scenarios in the continuous system including chaotic mixed-mode oscillations near the border between the regions of sub- and supercritical AHB. The proposed mechanism yields the statistical properties of the mixed-mode oscillations in this regime. The statistics predicted by the analysis of the Poincare map and those observed in the numerical experiments of the continuous system show a very good agreement.Comment: Chaos: An Interdisciplinary Journal of Nonlinear Science (tentatively, Sept 2008

Current Challenges in the Development of Quantum Dot Sensitized Solar Cells

This is the peer reviewed version of the following article: Current Challenges in the Development of Quantum Dot Sensitized Solar Cells, which has been published in final form at https://doi.org/10.1002/aenm.202001774. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Quantum dot sensitized solar cells (QDSSCs) have experienced a continuous performance growth in the past years presenting a photoconversion efficiency > 13%. QDSSCs constitute a smart approach to take advantage of the properties of semiconductor quantum dots (QDs), mitigating the transport constrains. In contrast with other QD solar cell configurations, for QDSSCs, the record efficiencies have been reported with Pb and Cd‐free based sensitizers. The development of techniques in order to provide photoanodes with very high QD loading and the discovery of new electrolytes, including all solid configurations, are the most important future challenges that this technology must address to further increase cell performance and stability

The Second Virial Coefficient of Spin-1/2 Interacting Anyon System

Evaluating the propagator by the usual time-sliced manner, we use it to compute the second virial coefficient of an anyon gas interacting through the repulsive potential of the form $g/r^2 (g > 0)$. All the cusps for the unpolarized spin-1/2 as well as spinless cases disappear in the $\omega \to 0$ limit, where $\omega$ is a frequency of harmonic oscillator which is introduced as a regularization method. As $g$ approaches to zero, the result reduces to the noninteracting hard-core limit.Comment: 9 pages, 2 figs include

Ytterbium doped nano-crystalline optical fiber for reduced photodarkening

We report suppression of photodarkening in Yb-doped nano-crystalline fibers in silica host. The photodarkening induced loss reduced by 20 times compared to Yb-doped aluminosilicate fibers. The laser efficiency of the nano-crystalline fiber was 79%

Quantum mutual entropy for Jaynes-Cummings model

The dynamics of an atom on the Jaynes-Cummings model has been studied by an atomic inversion, von Neumann entropy and so on. In this letter, we will treat the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics and apply quantum mutual entropy to study the irreversible dynamics of a state for the atom on this model.Comment: RevTeX, 4 pages with a figure(eps file), submitted to Physical Review Letter

The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds

Structure and properties of laser beam welding zone of dissimilar materials, AZ31 magnesium alloy and A5754 Aluminum alloy, are investigated. The microstructure and quality of the Mg/Al weld were studied by metallography, microhardness and optical microscopy. Differences in physical and mechanical properties of both materials, magnesium and aluminum, affect weldability and resistance of this combination, and lead to the formation of intermetallic compounds in the welded metal

New Perspective on Galaxy Clustering as a Cosmological Probe: General Relativistic Effects

We present a general relativistic description of galaxy clustering in a FLRW universe. The observed redshift and position of galaxies are affected by the matter fluctuations and the gravity waves between the source galaxies and the observer, and the volume element constructed by using the observables differs from the physical volume occupied by the observed galaxies. Therefore, the observed galaxy fluctuation field contains additional contributions arising from the distortion in observable quantities and these include tensor contributions as well as numerous scalar contributions. We generalize the linear bias approximation to relate the observed galaxy fluctuation field to the underlying matter distribution in a gauge-invariant way. Our full formalism is essential for the consistency of theoretical predictions. As our first application, we compute the angular auto correlation of large-scale structure and its cross correlation with CMB temperature anisotropies. We comment on the possibility of detecting primordial gravity waves using galaxy clustering and discuss further applications of our formalism.Comment: 10 pages, 2 figures, accepted for publication in Physical Review

Procedural Fairness in Antitrust Enforcement: The U.S. Perspective

Due process and fairness in enforcement procedures represent a critical aspect of the rule of law. Allowing greater participation by the parties and making enforcement procedures more transparent serve several functions, including better decisionmaking, greater respect for government, stronger economic growth, promotion of investment, limits corruption and politically motivated actions, regulation of bureaucratic ambition, and greater control of agency staff whose vision do not align with agency leadership or who are using an enforcement matter to advance their careers. That is why such distinguished actors as the International Competition Network (ICN), the Organization for Economic Cooperation and Development (OECD), the Association of Southeast Asian Nations (ASEAN), the International Chamber of Commerce (ICC), and the American Bar Association (ABA) have all offered frameworks for promoting greater fairness in antitrust enforcement. Because the U.S. was the first country to enact an antitrust law, it has enjoyed the longest opportunity to develop its enforcement practices. As such, after first introducing the key antitrust enforcement institutions, this chapter will explore the manner in which U.S. implements four key procedural protections (legal representation, notice of the legal basis and evidence underlying the alleged violation, engagement between the parties and the investigative staff, and internal checks and balances/judicial review) to provide insights into ways to improve U.S. law and in the hopes that other jurisdictions might benefit from the U.S. experience