4,118 research outputs found
Revisiting the phase diagram of hard ellipsoids
In this work the well-known Frenkel-Mulder phase diagram of hard ellipsoids
of revolution [Mol. Phys. 55, 1171 (1985)] is revisited by means of replica
exchange Monte Carlo simulations. The method provides good sampling of dense
systems and so, solid phases can be accessed without the need of imposing a
given structure. At high densities, we found plastic solids and fcc-like
crystals for semi-spherical ellipsoids (prolates and oblates), and SM2
structures [Phys. Rev. E 75, 020402 (2007)] for x:1-prolates and 1:x-oblates
with x>=3. The revised fluid-crystal and isotropic-nematic transitions
reasonably agree with those presented in the Frenkel-Mulder diagram. An
interesting result is that, for small system sizes (100 particles), we obtained
2:1 and 1.5:1-prolate equations of state without transitions, while some order
is developed at large densities. Furthermore, the symmetric oblate cases are
also reluctant to form ordered phases.Comment: 8 pages, 6 figure
Spinons as Composite Fermions
We show that gauge invariant composites in the fermionic realization of
conformal field theory explicitly exhibit the holomorphic
factorization of the corresponding WZW primaries. In the case we show
that the holomorphic sector realizes the spinon algebra, thus
allowing the classification of the chiral Fock space in terms of semionic
quasi-particle excitations created by the composite fermions.Comment: SU(N)_1 case included. Final version to appear in Mod. Phys. Lett. A.
Latex, 13 page
Arbitrary Dimensional Majorana Dualities and Network Architectures for Topological Matter
Motivated by the prospect of attaining Majorana modes at the ends of
nanowires, we analyze interacting Majorana systems on general networks and
lattices in an arbitrary number of dimensions, and derive various universal
spin duals. Such general complex Majorana architectures (other than those of
simple square or other crystalline arrangements) might be of empirical
relevance. As these systems display low-dimensional symmetries, they are
candidates for realizing topological quantum order. We prove that (a) these
Majorana systems, (b) quantum Ising gauge theories, and (c) transverse-field
Ising models with annealed bimodal disorder are all dual to one another on
general graphs. As any Dirac fermion (including electronic) operator can be
expressed as a linear combination of two Majorana fermion operators, our
results further lead to dualities between interacting Dirac fermionic systems.
The spin duals allow us to predict the feasibility of various standard
transitions as well as spin-glass type behavior in {\it interacting} Majorana
fermion or electronic systems. Several new systems that can be simulated by
arrays of Majorana wires are further introduced and investigated: (1) the {\it
XXZ honeycomb compass} model (intermediate between the classical Ising model on
the honeycomb lattice and Kitaev's honeycomb model), (2) a checkerboard lattice
realization of the model of Xu and Moore for superconducting arrays,
and a (3) compass type two-flavor Hubbard model with both pairing and hopping
terms. By the use of dualities, we show that all of these systems lie in the 3D
Ising universality class. We discuss how the existence of topological orders
and bounds on autocorrelation times can be inferred by the use of symmetries
and also propose to engineer {\it quantum simulators} out of these Majorana
networks.Comment: v3,19 pages, 18 figures, submitted to Physical Review B. 11 new
figures, new section on simulating the Hubbard model with nanowire systems,
and two new appendice
Complementary weak-value amplification with concatenated postselections
We measure a transverse momentum kick in a Sagnac interferometer using
weak-value amplification with two postselections. The first postselection is
controlled by a polarization dependent phase mismatch between both paths of a
Sagnac interferometer and the second postselection is controlled by a polarizer
at the exit port. By monitoring the darkport of the interferometer, we study
the complementary amplification of the concatenated postselections, where the
polarization extinction ratio is greater than the contrast of the spatial
interference. In this case, we find an improvement in the amplification of the
signal of interest by introducing a second postselection to the system
Portrayals of The Dehumanization of The American Prisoner in Miguel Piñero\u27s “Short Eyes” and Tom Fontana\u27s “Oz”
This thesis analyzes the way in which Miguel Piñero, through his 1974 play Short Eyes, and Tom Fontana, through his television series Oz, portray the way in which American prisoners are transformed by a racially-defined code of behavior. This code of behavior, defined by Miguel Piñero as “the program” encourages inmates to over-identify themselves in terms of race and leads them to engage in behavior that contributes to their dehumanization. In the first chapter, the introduction, I establish the social, political, and theoretical concepts through which it is possible to analyze the process of prisoner identity transformation in these two works. In chapter two, I describe the process in which a prisoner’s identity is divided through a reading of the both works using social identity theory. In the third chapter, I describe the way in which the program and its emphasis on race shape the creation of prison identities
Can Anomalous Amplification be Attained Without Postselection?
We present a parameter estimation technique based on performing joint
measurements of a weak interaction away from the weak-value-amplification
approximation. Two detectors are used to collect full statistics of the
correlations between two weakly entangled degrees of freedom. Without the need
of postselection, the protocol resembles the anomalous amplification of an
imaginary-weak-value-like response. The amplification is induced in the
difference signal of both detectors allowing robustness to different sources of
technical noise, and offering in addition the advantages of balanced signals
for precision metrology. All of the Fisher information about the parameter of
interest is collected, and a phase controls the amplification response. We
experimentally demonstrate the proposed technique by measuring polarization
rotations in a linearly polarized laser pulse. The effective sensitivity and
precision of a split detector is increased when compared to a conventional
continuous-wave balanced detection technique
Explicit connection between conformal field theory and 2+1 Chern-Simons theory
We give explicit field theoretical representations for the observables of 2+1
dimensional Chern-Simons theory in terms of gauge invariant composites of 2D
WZW fields. To test our identification we compute some basic Wilson loop
correlators reobtaining known results.Comment: 13 pages, Latex file. To appear in Mod.Phys.Lett.
Genome-wide analysis of 30 -untranslated regions supports the existence of post-transcriptional regulons controlling gene expression in trypanosomes
In eukaryotic cells, a group of messenger ribonucleic acids (mRNAs) encoding functionally interrelated proteins together with the trans-acting factors that coordinately modulate their expression is termed a post-transcriptional regulon, due to their partial analogy to a prokaryotic polycistron. This mRNA clustering is organized by sequence-specific RNA-binding proteins (RBPs) that bind cis-regulatory elements in the noncoding regions of genes, and mediates the synchronized control of their fate. These recognition motifs are often characterized by conserved sequences and/or RNA structures, and it is likely that various classes of cis-elements remain undiscovered. Current evidence suggests that RNA regulons govern gene expression in trypanosomes, unicellular parasites which mainly use post-transcriptional mechanisms to control protein synthesis. In this study, we used motif discovery tools to test whether groups of functionally related trypanosomatid genes contain a common cis-regulatory element. We obtained conserved structured RNA motifs statistically enriched in the noncoding region of 38 out of 53 groups of metabolically related transcripts in comparison with a random control. These motifs have a hairpin loop structure, a preferred sense orientation and are located in close proximity to the open reading frames. We found that 15 out of these 38 groups represent unique motifs in which most 30 -UTR signature elements were group-specific. Two extensively studied Trypanosoma cruzi RBPs, TcUBP1 and TcRBP3 were found associated with a few candidate RNA regulons. Interestingly, 13 motifs showed a strong correlation with clusters of developmentally co-expressed genes and six RNA elements were enriched in gene clusters affected after hyperosmotic stress. Here we report a systematic genome-wide in silico screen to search for novel RNA-binding sites in transcripts, and describe an organized network of several coordinately regulated cohorts of mRNAs in T. cruzi. Moreover, we found that structured RNA elements are also conserved in other human pathogens. These results support a model of regulation of gene expression by multiple post-transcriptional regulons in trypanosomes.Fil: de Gaudenzi, Javier Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Carmona, Santiago Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Agüero, Fernan Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Frasch, Alberto Carlos C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin
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