10,519 research outputs found
Holding On To History
When I searched for the story of Georges Lieber, the very man whose drive to resist inspired the concept for this essay, I could not find it. The only trace of him was his record on the Yad Vashem database which merely states that he was a student and that he was transported from Lyon, France to Auschwitz in 1944. His story, along with much of Holocaust history, remains unknown or misunderstood for many people, both from my generation and those before us. As a long-term student of history and an aspiring educator, I have chosen to resist the sliding grip that people have on history and hoist it up before the lives and lessons in it are lost
Multi-patch discontinuous Galerkin isogeometric analysis for wave propagation: explicit time-stepping and efficient mass matrix inversion
We present a class of spline finite element methods for time-domain wave
propagation which are particularly amenable to explicit time-stepping. The
proposed methods utilize a discontinuous Galerkin discretization to enforce
continuity of the solution field across geometric patches in a multi-patch
setting, which yields a mass matrix with convenient block diagonal structure.
Over each patch, we show how to accurately and efficiently invert mass matrices
in the presence of curved geometries by using a weight-adjusted approximation
of the mass matrix inverse. This approximation restores a tensor product
structure while retaining provable high order accuracy and semi-discrete energy
stability. We also estimate the maximum stable timestep for spline-based finite
elements and show that the use of spline spaces result in less stringent CFL
restrictions than equivalent piecewise continuous or discontinuous finite
element spaces. Finally, we explore the use of optimal knot vectors based on L2
n-widths. We show how the use of optimal knot vectors can improve both
approximation properties and the maximum stable timestep, and present a simple
heuristic method for approximating optimal knot positions. Numerical
experiments confirm the accuracy and stability of the proposed methods
Lexical stress information modulates the time-course of spoken-word recognition
Segmental as well as suprasegmental information is used by Dutch listeners to recognize words. The time-course of the effect of suprasegmental stress information on spoken-word recognition was investigated in a previous study, in which we tracked Dutch listeners' looks to arrays of four printed words as they listened to spoken sentences. Each target was displayed along with a competitor that did not differ segmentally in its first two syllables but differed in stress placement (e.g., 'CENtimeter' and 'sentiMENT'). The listeners' eye-movements showed that stress information is used to recognize the target before distinct segmental information is available. Here, we examine the role of durational information in this effect. Two experiments showed that initial-syllable duration, as a cue to lexical stress, is not interpreted dependent on the speaking rate of the preceding carrier sentence. This still held when other stress cues like pitch and amplitude were removed. Rather, the speaking rate of the preceding carrier affected the speed of word recognition globally, even though the rate of the target itself was not altered. Stress information modulated lexical competition, but did so independently of the rate of the preceding carrier, even if duration was the only stress cue present
Using the nonhuman primate model of HCMV to guide vaccine development.
The natural history of human cytomegalovirus (HCMV) is inextricably associated with mucosal surfaces. The vast preponderance of primary infections occur following mucosal exposure to infectious virions, and the high seroprevalence of HCMV throughout the world is due to long-term excretion of HCMV in bodily fluids from multiple mucosal sites. Accumulating evidence presents a model where the earliest virus-host interactions following infection dictate the long-term pattern of infection, alter innate immune responses that skew adaptive responses to enable persistence within an immune host, and are essential for reinfection of a host with prior immunity. HCMV has evolved a complex repertoire of viral functions fine-tuned to manipulate the immune environment both locally at the sites of infection and systemically within an infected host. Collectively, viral immune modulation represents a significant impediment for an HCMV vaccine. As HCMV can disseminate beyond mucosal surfaces to reinfect immune hosts, it may not matter whether prior immunity results from prior infection or immunization. A better understanding of the earliest virus-hosts interactions at mucosal surfaces may identify elements of the viral proteome that are especially susceptible to vaccine-mediated disruption and prevent challenge virus from disseminating to distal sites, particularly the maternal-fetal interface
First record of the agave snout weevil, Scyphophorus acupunctatusGyllenhal (Coleoptera: Curculionidae: Dryophthorinae), in Puerto Rico
The agave snout weevil, Scyphophorus acupunctatus Gyllenhal (Coleoptera: Curculionidae: Dryophthorinae), is reported from Puerto Rico for the first time. It was collected on feral sisal, Agave sisalana Perrine (Agavaceae), in the Guánica Dry Forest Reserve in the southwestern part of the island
Wage Bargaining under the National Labor Relations Act
Sections 8(a)(3) and 8(a)(5) of the National Labor Relations Act prevent a firm from unilaterally increasing the wage it pays the union during the negotiation of a new wage contract. To understand this regulation, we study a counterfactual negotiation model where the firm can temporarily increase compensation to its employees during wage negotiations. Comparing this to the case where the firm does not have this option, we show that the firm may strategically increase the union's temporary wage to upset the union's incentive to strike, decreasing the union's bargaining power, and shrinking the set of permanent wage contracts that may arise in a perfect equilibrium. As the union becomes more patient, the best possible equilibrium contract to the union gets worse. In the limit, the uniqueness and hence the full efficiency of the perfect equilibrium are restored. We also demonstrate that allowing the union to refuse the firm's temporary compensation does not affect the set of perfect equilibrium outcomesBargaining, Negotiation, Good Faith Bargaining
The goldstone and goldstino of supersymmetric inflation
We construct the minimal effective field theory (EFT) of supersymmetric
inflation, whose field content is a real scalar, the goldstone for
time-translation breaking, and a Weyl fermion, the goldstino for supersymmetry
(SUSY) breaking. The inflating background can be viewed as a single
SUSY-breaking sector, and the degrees of freedom can be efficiently
parameterized using constrained superfields. Our EFT is comprised of a chiral
superfield X_NL containing the goldstino and satisfying X_NL^2 = 0, and a real
superfield B_NL containing both the goldstino and the goldstone, satisfying
X_NL B_NL = B_NL^3 = 0. We match results from our EFT formalism to existing
results for SUSY broken by a fluid background, showing that the goldstino
propagates with subluminal velocities. The same effect can also be derived from
the unitary gauge gravitino action after embedding our EFT in supergravity. If
the gravitino mass is comparable to the Hubble scale during inflation, we
identify a new parameter in the EFT related to a time-dependent phase of the
gravitino mass parameter. We briefly comment on the leading contributions of
goldstino loops to inflationary observables.Comment: 32 pages, 2 figures. v3: clarifications and references added. Matches
JHEP version. v2: typos fixed, footnote and references adde
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