The Gettysburg Battlefield, One Century Ago

In the fall of 1899, Colonel John Nicholson reported on the recent changes being made to the Gettysburg National Military park. The park held a dedication ceremony that July for a new equestrian statue to General John Reynolds erected northwest of town. It was a shiny goldenbrown, polished-bronze statue sculpted by Henry Kirke Bush-Brown (his second equestrian statue at Gettysburg in three years). The horse and rider, balancing on two legs stood on a large pedestal near the new avenue in his name. Reynolds Avenue and adjoining Wadsworth, Doubleday, and Robinson Avenues were new to the battlefield as well. These were exciting times. The first-day\u27s battlegrounds were being made accessible to visitors and veterans. In fact, the entire battlefield was being paved, marked, and restored by the Gettysburg National Park Commission (GNPC). Colonel John Nicholson (USA), Major William Robbins (CSA), and Major Charles Richardson (USA) comprised the GNPC. Each a veteran of the battle, they had been appointed by the War Department to restore the field at Gettysburg. Former Confederate veteran Robbins was specifically appointed to oversee the placement of new markers detailing the Army of Northern Virginia\u27s role in the battle. Ever since the War Department took over care of the grounds six years prior because the local Gettysburg Battlefield Memorial Association (GBMA) could no longer afford the upkeep, signs for both Union and Confederate troop placements were ordered. Confederate markings were just one of several radical changes to the park\u27s landscape design in 1899. [excerpt

Differentiating U(1)′U(1)^\prime supersymmetric models with right sneutrino and neutralino dark matter

We perform a detailed analysis of dark matter signals of supersymmetric models containing an extra $U(1)^\prime$ gauge group. We investigate scenarios in which either the right sneutrino or the lightest neutralino are phenomenologically acceptable dark matter candidates and we explore the parameter spaces of different supersymmetric realisations featuring an extra $U(1)^\prime$. We impose consistency with low energy observables, with known mass limits for the superpartners and $Z^\prime$ bosons, as well as with Higgs boson signal strengths, and we moreover verify that predictions for the anomalous magnetic moment of the muon agree with the experimental value and require that the dark matter candidate satisfies the observed relic density and direct and indirect dark matter detection constraints. For the case where the sneutrino is the dark matter candidate, we find distinguishing characteristics among different $U(1)^\prime$ mixing angles. If the neutralino is the lightest supersymmetric particle, its mass is heavier than that of the light sneutrino in scenarios where the latter is a dark matter candidate, the parameter space is less restricted and differentiation between models is more difficult. We finally comment on the possible collider tests of these models.Comment: 21 pages, 11 figures, version accepted by PR

Evaluation of Default Risk for The Brazilian Banking Sector

This paper employs new methods to measure and monitor risk in the Brazilian banking sector. We prove that the option-based risk measure is negatively sensitive to interest rates. As this is an important issue for emerging market economies, the risk measures are built as deviations from mean. Additionally, the option-based indicator is compared with market-based financial fragility indicators. Results show that these indicators are useful for risk managers and regulators, especially during crisis. Furthermore, option-based methods are preferable to classify banks in periods of high distress, such as the banking crises that occurred in the early nineties in Brazil.

Loopholes in Z′Z^\prime searches at the LHC: exploring supersymmetric and leptophobic scenarios

Searching for heavy vector bosons $Z^\prime$, predicted in models inspired by Grand Unification Theories, is among the challenging objectives of the LHC. The ATLAS and CMS collaborations have looked for $Z^\prime$ bosons assuming that they can decay only into Standard Model channels, and have set exclusion limits by investigating dilepton, dijet and to a smaller extent top-antitop final states. In this work we explore possible loopholes in these $Z^\prime$ searches by studying supersymmetric as well as leptophobic scenarios. We demonstrate the existence of realizations in which the $Z^\prime$ boson automatically evades the typical bounds derived from the analyses of the Drell-Yan invariant-mass spectrum. Dileptonic final states can in contrast only originate from supersymmetric $Z^\prime$ decays and are thus accompanied by additional effects. This feature is analyzed in the context of judiciously chosen benchmark configurations, for which visible signals could be expected in future LHC data with a $4\sigma-7\sigma$ significance. Our results should hence motivate an extension of the current $Z^\prime$ search program to account for supersymmetric and leptophobic models.Comment: 32 pages, 15 figures. After JHEP revision. Published on 15 February 201

A comparative study of some models of incoherence at the mesoscopic scale

The pre-existing literature on phenomena at the mesoscopic scale is concerned among other things with phase coherent transport. Phase coherent transport dominates at very low temperatures. With increase in temperature, as the system size becomes comparable to the inelastic mean free path phase incoherence sets in. This incoherence further leads to dephasing, and as a consequence purely quantum effects in electron transport give way to classical macroscopic behavior. In this work we consider two distinct phenomenological models of incoherent transport, the Coherent Absorption and Wave Attenuation models. We reveal some physical problems in the Coherent Absorption model as opposed to the Wave Attenuation model. We also compare our proposed model with experiments in case of the much studied peak to valley ratios in resonant tunneling diodes, magneto-conductance oscillations and Fano resonances in case of Aharonov-Bohm rings.Comment: 20 pages, 9 figure

Detecting induced subgraphs

An s-graph is a graph with two kinds of edges : subdivisible edges and real edges. A realisation of an s-graphB is any graph obtained by subdividing subdivisible edges of B into paths of arbitrary length (at least one). Given an s-graph B, we study the decision problem Pi(B) whose instance is a graph G and whose question is "Does G contain a realisation of B as an induced subgraph ?".Detection, induced, subgraph.

Choice-induced preference: A challenge for contrast

In his target article, Zentall asks: “to experience cognitive dissonance is it necessary for one to have conflicting beliefs or even beliefs at all?” He then argues that a simple behavioral process, the Within Trial Contrast Effect, may be sufficient to explain observed cognitive dissonance effects in nonhuman animals and possibly humans as well. We agree with Zentall that this effect is sufficient to explain many reported cognitive dissonance effects in nonhuman animals, but question its sufficiency for primate behavior (both monkeys and humans)

Active surgical positioning device for a cochlear implant electrode array

Cochlear implants have been of great benefit in restoring auditory function to individuals with profound bilateral sensorineural deafness. The implants are used to directly stimulate auditory nerves and send a signal to the brain that is then interpreted as sound. This project focuses on the development of a surgical positioning tool to accurately and effectively place an array of stimulating electrodes deep within the cochlea. This will lead to improved efficiency and performance of the stimulating electrodes, reduced surgical trauma to the cochlea, and as a result, improved overall performance to the implant recipient. The positioning tool reported here consists of multiple fluidic chambers providing localized curvature control along the length of the attached silicon electrode array. The chambers consist of 200μm inner diameter PET (polyethylene therephthalate) tubes with 4μm wall thickness. The chambers are molded in a tapered helical configuration to correspond to the cochlear shape upon relaxation of the actuators. This ensures that the optimal electrode placement within the cochlea is retained after the positioning tool becomes dormant (for chronic implants). Actuation is achieved by injecting fluid into the PET chambers and regulating the fluidic pressure. The chambers are arranged in a stacked, overlapping design to provide fluid connectivity with the non-implantable pressure controller and allow for local curvature control of the device. The stacked tube configuration allows for localized curvature control of various areas along the length of the electrode and additional stiffening and actuating power towards the base. Curvature is affected along the entire length of a chamber and the result is cumulative in sections of multiple chambers. The actuating chambers are bonded to the back of a silicon electrode array