609 research outputs found

    Gals Getting Reno-Vated : Individual Transformation and National Change During the Rise and Fall of the Reno Divorce Ranches

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    Divorces in the United States during the twentieth century were, to say the least, extremely difficult to obtain. Most states had few grounds for divorce, and some, like New York, only allowed divorce in the instance of proven adultery. Waiting periods could stretch from one to three years. But for some hopeful divorcees, there was another way. Nevada had nine broad grounds for divorce, among them “mental cruelty.” After 1931, anyone could become a Nevada citizen and divorce within the state after a mere six weeks of residency. Before the widespread liberalization of divorce law in the early to mid-1970s, Reno, Nevada became the divorce capital of America. Divorcees, usually women, from all over the country poured into Reno to “get Reno-vated” and quickly part with their spouses. Subsequently, a complex local economy developed to accommodate the “six-weekers” during while they established residency. For the wealthy divorce-seeking elite, luxurious “divorce ranches” offered a relaxing six-week stay complete with catered meals, horseback riding, and trips to Lake Tahoe. The ranches brought together a substantial number of women who were overtly there for the same reason: to obtain a divorce. The simple fact of this mutual understanding provided a level of closeness and openness that was very unusual for the time, facilitating commiseration, camaraderie, and friendship. The closeness of ranch relationships was amplified by their demographics; the ranches were overwhelmingly female spaces, as the majority of their guests, proprietors, and staff were women. The Reno divorce industry demonstrates that women were willing to go to great lengths, measured in miles, days, and dollars, to obtain divorces. Affirming the existence of these Reno divorcees and examining their experiences during their quickie divorces illustrates substantial shifts in marital expectations throughout the twentieth century and contextualizes the 1970s expansion of divorce rights

    Effect of mould inoculation on formation of chunky graphite in heavy section spheroidal graphite cast iron parts

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    The manufacturing process of heavy section ductile iron castings is strongly influenced by the risk of graphite degeneration under slow cooling rates. Appearance of this kind of defect is commonly linked to significant reductions in the mechanical properties of large castings. Studies on the effect of inoculation on chunky graphite formation in heavy sections have led to contradictory results in the literature and this triggered the present work. New experimental data are presented on the effect of mould inoculation on chunky graphite appearance during solidification of nodular irons which clearly demonstrate that mould inoculation increases the risk of chunky graphite formation in heavy sections. This is in agreement with some previous works which are reviewed, and it is suggested that the contradiction with other results could relate to the fact that these latter works dealt with chill casting

    Jamming during the discharge of granular matter from a silo

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    In this work we present an experimental study of the jamming that stops the free flow of grains from a silo discharging by gravity. When the outlet size is not much bigger than the beads, granular material jams the outlet of the container due to the formation of an arch. Statistical data from the number of grains fallen between consecutive jams are presented. The information that they provide can help to understand the jamming phenomenon. As the ratio between the size of the orifice and the size of the beads is increased, the probability that an arch blocks the outlet decreases. We show here that there is a power law divergence of the mean avalanche size for a finite critical radius. Beyond this critical radius no jamming can occur and the flow is never stopped. The dependence of the arch formation on the shape and the material of the grains has been explored. It has been found that the material properties of the grains do not affect the arch formation probability. On the contrary, the shape of the grains deeply influences it. A simple model to interpret the results is also discussed.Comment: Submitted to Phys. Rev.

    The shape of jamming arches in two-dimensional deposits of granular materials

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    We present experimental results on the shape of arches that block the outlet of a two dimensional silo. For a range of outlet sizes, we measure some properties of the arches such as the number of particles involved, the span, the aspect ratio, and the angles between mutually stabilizing particles. These measurements shed light on the role of frictional tangential forces in arching. In addition, we find that arches tend to adopt an aspect ratio (the quotient between height and half the span) close to one, suggesting an isotropic load. The comparison of the experimental results with data from numerical models of the arches formed in the bulk of a granular column reveals the similarities of both, as well as some limitations in the few existing models.Comment: 8 pages; submitted to Physical Review

    Transition from clogging to continuous flow in constricted particle suspensions

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    When suspended particles are pushed by liquid flow through a constricted channel, they might either pass the bottleneck without trouble or encounter a permanent clog that will stop them forever. However, they may also flow intermittently with great sensitivity to the neck-to-particle size ratio D / d . In this Rapid Communication, we experimentally explore the limits of the intermittent regime for a dense suspension through a single bottleneck as a function of this parameter. To this end, we make use of high time- and space-resolution experiments to obtain the distributions of arrest times ( T ) between successive bursts, which display power-law tails ( ∝ T − α ) with characteristic exponents. These exponents compare well with the ones found for as disparate situations as the evacuation of pedestrians from a room, the entry of a flock of sheep into a shed, or the discharge of particles from a silo. Nevertheless, the intrinsic properties of our system (i.e., channel geometry, driving and interaction forces, particle size distribution) seem to introduce a sharp transition from a clogged state ( α ≀ 2 ) to a continuous flow, where clogs do not develop at all. This contrasts with the results obtained in other systems where intermittent flow, with power-law exponents above two, were obtained

    Time-randomized stopping problems for a family of utility functions

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    This paper studies stopping problems of the form V=inf⁥0≀τ≀TE[U(max⁥0≀s≀TZsZτ)]V=\inf_{0 \leq \tau \leq T} \mathbb{E}[U(\frac{\max_{0\le s \le T} Z_s }{Z_\tau})] for strictly concave or convex utility functions U in a family of increasing functions satisfying certain conditions, where Z is a geometric Brownian motion and T is the time of the nth jump of a Poisson process independent of Z. We obtain some properties of VV and offer solutions for the optimal strategies to follow. This provides us with a technique to build numerical approximations of stopping boundaries for the fixed terminal time optimal stopping problem presented in [J. Du Toit and G. Peskir, Ann. Appl. Probab., 19 (2009), pp. 983--1014]

    Pulsed-field gel electrophoresis profile homogeneity of Mycobacterium avium subsp. paratuberculosis isolates from cattle and heterogeneity of those from sheep and goats

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    BACKGROUND: Mycobacterium avium subsp. paratuberculosis (Map) causes paratuberculosis in animals and is suspected of causing Crohn's Disease in humans. Characterization of strains led to classify paratuberculosis isolates in two main types, cattle type strains, found affecting all host species, and sheep type strains, reported affecting mainly sheep. In order to get a better understanding of the epidemiology of paratuberculosis a large set of Map isolates obtained from different species over the last 25 years have been characterized. Five-hundred and twenty isolates from different hosts (cattle, sheep, goats, bison, deer and wild boar) and origins had been cultured and typed by IS1311 restriction-endonuclease-analysis. Two-hundred and sixty-nine isolates were further characterized by pulsed-field gel electrophoresis (PFGE) using SnaBI and SpeI endonucleases. Differences in strain isolation upon various media conditions were also studied. RESULTS: All bovines, 4 and 26% of Spanish sheep and goats, respectively, and the deer and wild boar studied, carried IS1311-Cattle type strains. IS1311-Sheep type encompassed 96% and 74% of Spanish sheep and goats, and all three Portuguese sheep. Thirty-seven distinct multiplex PFGE profiles were found, giving 32 novel profiles. Profiles 2-1 and 1-1 accounted for the 85% of cattle isolates. Ten distinct profiles were detected in Spanish sheep, none of them with an incidence higher than 25%. Profile 16-11 (43%) and another three profiles were identified in Spanish caprine cultures. The hierarchical analysis, clustered all profiles found in cattle, "wild" hosts and some small ruminants within the same group. The other group included 11 profiles only found in Spanish sheep and goats, including Spanish pigmented profiles. Differences in growth requirements associated with isolate genotype were observed. CONCLUSION: Cattle in Spain are infected with cattle type strains, while sheep and goats are mainly infected with sheep type strains. Although 7H9 broth based culture media seem to broadly cover the growth requirements of most Map strains, the use of various solid media is recommended to reduce any recovery biases. High genetic homogeneity of isolates from cattle, and heterogeneity of those from sheep and goats have been detected

    Influence of the feeding mechanism on deposits of square particles

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    In a previous paper [Hidalgo et al., Phys. Rev. Lett. 103, 118001 (2009)] it was shown that square particles deposited in a silo tend to align with a diagonal parallel to the gravity, giving rise to a deposit with very particular properties. Here we explore, both experimentally and numerically, the effect on these properties of the filling mechanism. In particular, we modify the volume fraction of the initial configuration from which the grains are deposited. Starting from a very dilute case, increasing the volume fraction results in an enhancement of the disorder in the final deposit characterized by a decrease of the final packing fraction and a reduction of the number of particles oriented with their diagonal in the direction of gravity. However, for very high initial volume fractions, the final packing fraction increases again. This result implies that two deposits with the same final packing fraction can be obtained from very different initial conditions. The structural properties of such deposits are analyzed, revealing that, although the final volume fraction is the same, their micromechanical properties notably differ
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