Academic literature on the topic 'Gun control paradox'

<p>Many scholars and interest groups in the U.S. advocate for more gun-control in terms of restrictions on sales. Following the Sandy Hook shooting in Newtown, Connecticut in December 2012, The Obama Administration initiated legislation to restrict gun sales. Coincidentally, U.S. firearm sales surged to record levels and ammunition shortages occurred. This article examines the gun control issue in the U.S. in light of the events of 2013, demonstrating the paradox which gun-control advocates face. The authors provide background information on the gun-control debate including the social cost of gun-violence and the U.S. political battle over the issue.</p>

Ultra-low seismic frequencies less than about 7 Hz cannot be produced by conventional air gun arrays, for any configuration and for any towing depth. There is a profound difference between improving low-frequency recovery by removing source and receiver ghosts (achievable) and improving low-frequency injection on the source side (an unrealised dream). If 1–7 Hz amplitudes could be usefully injected into the earth, it would be possible to facilitate much sharper seismic representation of geological contacts and internal features, and seismic inversion would yield robust and precise predictions of reservoir properties—without well control. The net result is fewer exploration and appraisal wells, greatly reduced exploration and development risks, and optimised recoverable reserves. Furthermore, an emerging seismic pursuit known as full waveform inversion (FWI) makes the bold promise that raw seismic field gathers can be directly used to invert for the highest achievable velocity models, almost without any human intervention. These models will bypass the traditional lack of low-frequency information in band-limited seismic data, and facilitate the aforementioned ambition of seismic inversion without well control. FWI, however, is confronted by the paradox that ultra-low-frequency seismic gathers are the necessary input for stable results. This paper describes new technologies that may enable the injection of strong 2–7 Hz amplitudes into the earth, and explains in simple terms how FWI can already be pursued as a robust complement to the prediction of accurate reservoir properties. The low-frequency revolution is already here.

This is a quantitative model of control of Ca2+ release from the sarcoplasmic reticulum in skeletal muscle, based on dual control of release channels (ryanodine receptors), primarily by voltage, secondarily by Ca2+ (Ríos, E., and G. Pizarro. 1988. NIPS. 3:223–227). Channels are positioned in a double row array of between 10 and 60 channels, where exactly half face voltage sensors (dihydropyridine receptors) in the transverse (t) tubule membrane (Block, B.A., T. Imagawa, K.P. Campbell, and C. Franzini-Armstrong. 1988. J. Cell Biol. 107:2587–2600). We calculate the flux of Ca2+ release upon different patterns of pulsed t-tubule depolarization by explicit stochastic simulation of the states of all channels in the array. Channels are initially opened by voltage sensors, according to an allosteric prescription (Ríos, E., M. Karhanek, J. Ma, A. González. 1993. J. Gen. Physiol. 102:449–482). Ca2+ permeating the open channels, diffusing in the junctional gap space, and interacting with fixed and mobile buffers produces defined and changing distributions of Ca2+ concentration. These concentrations interact with activating and inactivating channel sites to determine the propagation of activation and inactivation within the array. The model satisfactorily simulates several whole-cell observations, including kinetics and voltage dependence of release flux, the “paradox of control,” whereby Ca2+-activated release remains under voltage control, and, most surprisingly, the “quantal” aspects of activation and inactivation (Pizarro, G., N. Shirokova, A. Tsugorka, and E. Ríos. 1997. J. Physiol. 501:289–303). Additionally, the model produces discrete events of activation that resemble Ca2+ sparks (Cheng, H., M.B. Cannell, and W.J. Lederer. 1993. Science (Wash. DC). 262:740–744). All these properties result from the intersection of stochastic channel properties, control by local Ca2+, and, most importantly, the one dimensional geometry of the array and its mesoscopic scale. Our calculations support the concept that the release channels associated with one face of one junctional t-tubule segment, with its voltage sensor, constitute a functional unit, termed the “couplon.” This unit is fundamental: the whole cell behavior can be synthesized as that of a set of couplons, rather than a set of independent channels.

Abstract During protein synthesis, charged tRNAs deliver amino acids to translating ribosomes, and are then re-charged by tRNA synthetases (aaRS). In humans, mutant aaRS cause a diversity of neurological disorders, but their molecular aetiologies are incompletely characterised. To understand system responses to aaRS depletion, the yeast glutamine aaRS gene (GLN4) was transcriptionally regulated using doxycycline by tet-off control. Depletion of Gln4p inhibited growth, and induced a GCN4 amino acid starvation response, indicative of uncharged tRNA accumulation and Gcn2 kinase activation. Using a global model of translation that included aaRS recharging, Gln4p depletion was simulated, confirming slowed translation. Modelling also revealed that Gln4p depletion causes negative feedback that matches translational demand for Gln-tRNAGln to aaRS recharging capacity. This maintains normal charged tRNAGln levels despite Gln4p depletion, confirmed experimentally using tRNA Northern blotting. Model analysis resolves the paradox that Gln4p depletion triggers a GCN4 response, despite maintenance of tRNAGln charging levels, revealing that normally, the aaRS population can sequester free, uncharged tRNAs during aminoacylation. Gln4p depletion reduces this sequestration capacity, allowing uncharged tRNAGln to interact with Gcn2 kinase. The study sheds new light on mutant aaRS disease aetiologies, and explains how aaRS sequestration of uncharged tRNAs can prevent GCN4 activation under non-starvation conditions.

Espagne, premier quart du XVIIe siècle : quatre hommes se rencontrent au cours d’un voyage entre Madrid et Barcelone où ils doivent partir pour l’Italie pour y tenter leur chance. Pour lutter contre la pénibilité de leur périple et éviter l’ennui, ils décident de converser. S’ensuit un échange de plus de 200 pages autour de leur destination, de leur parcours personnel respectif, de la société de l’époque au sein duquel viennent s’intercaler des récits à vocation plus ludique. Telle est l’intrigue de El Pasajero, advertencias utilísimas a la vida humana, œuvre citée par bon nombre de spécialistes du Siècle d’Or qui s’attachent tous à saluer ses qualités littéraires et à laquelle aucune étude littéraire de fond n’a été consacrée. Comment expliquer un tel paradoxe? El Pasajero propose un caléidoscope de la société de l’époque, d’où l’orientation sociologique de la plupart des études réalisées sur ce texte. La mauvaise presse de son auteur connu pour son tempérament peu amène et pour son opposition à Cervantès, a pu y contribuer également de manière plus tangentielle. Enfin et surtout, la richesse textuelle, littéraire et idéologique de El Pasajero peut avoir freiné certaines ambitions analytiques. Le texte de Figueroa est d’une nature profondément hybride, il se caractérise par un oscillement perpétuel entre inspiration italienne, accents décaméroniens, emprunts transtextuels et substrat folklorique hispanique. Il joue sur la porosité des frontières entre réalité et fiction pour élaborer un texte dont tous les éléments semblent dialoguer et entre lesquels le lecteur passe comme sur les pierres d’un gué. En fin de compte, El Pasajero est un véritable laboratoire d’expérimentation littéraire où affleurent traditions littéraires ancrées et propositions d’écriture plus innovantes. Ce dialogue perpétuel est décisif dans l’œuvre : au-delà d’un premier dialogue évident entre les personnages, le texte en propose d’autres en filigrane, entre les formes et les genres littéraires. Ils fonctionnent comme autant d’éléments structurants au sein de cette œuvre pensée comme un lieu de passage où se mêlent expérimentations littéraires et réflexions sociétales. El Pasajero peut parfois laisser le lecteur perplexe, c’est un fait. Il fait, néanmoins, partie de ces textes qui fascinent et qui n’ont pas encore révélé tous leurs secrets. Une chose est certaine : El Pasajero ne laisse pas indifférent et mérite qu’on lui consacre une étude de fond. C’est ce que se propose de faire cet ouvrage…

Do Americans Want Stricter Gun Laws? Public opinion experts have long observed that the United States has a gun control paradox: Most Americans favor all sorts of firearms regulations—sometimes overwhelmingly so—yet these regulations are not enacted into law. Four decades ago, one scholar noted...