Burst avalanches in solvable models of fibrous materials

We review limiting models for fracture in bundles of fibers, with statistically distributed thresholds for breakdown of individual fibers. During the breakdown process, avalanches consisting of simultaneous rupture of several fibers occur, and the distribution $D(\Delta)$ of the magnitude $\Delta$ of such avalanches is the central characteristics in our analysis. For a bundle of parallel fibers two limiting models of load sharing are studied and contrasted: the global model in which the load carried by a bursting fiber is equally distributed among the surviving members, and the local model in which the nearest surviving neighbors take up the load. For the global model we investigate in particular the conditions on the threshold distribution which would lead to anomalous behavior, i.e. deviations from the asymptotics $D(\Delta) \sim \Delta^{-5/2}$, known to be the generic behavior. For the local model no universal power-law asymptotics exists, but we show for a particular threshold distribution how the avalanche distribution can nevertheless be explicitly calculated in the large-bundle limit.Comment: 28 pages, RevTeX, 3 Postscript figure

Undated - E.G. Harlow requests the promotion of Isaac Virgin

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Sodium and Water Fluxes in Free-Living Crocodylus Porosus in Marine and Brackish Conditions

Radioactive sodium and water were used to determine total body water (TBW), exchangeable sodium (ExNa) and water and sodium fluxes in free-living Crocodylus porosus in marine (hyperosmotic; salinity = 250/00-350/00) and brackish (hypoosmotic; salinity = 20/00-7.50/00) sections of the Tomkinson River in northern Australia. At capture, size-corrected TBW and ExNa pools in 62 crocodiles (hatchlings, juveniles, and subadults; weight, 0.108-54.4 kg) were independent of salinity history. To determine fluxes, all animals were released at their capture sites and left undisturbed until recapture. Thirty-seven were recaptured after 7-18 days. Fifteen of the 17 hatchlings recaptured from both salinity categories grew and maintained their condition and hydration status. In contrast, all 20 juveniles and subadults lost weight in the same period, and juveniles in hyperosmotic conditions showed significantly lower hydration and condition factors. Water effluxes in hatchlings were ~80 and ~160 ml kg-0.63 day-1 in marine and brackish conditions, respectively. Comparable sodium effluxes were 7.5 and 4.4 mmol kg-0.63 day1. All crocodiles in hyperosmotic conditions had consistently lower water effluxes (~ X0.5) and higher sodium effluxes (~ X 1.6) than did crocodiles in brackish water. In both salinity categories, hatchlings had greater water turnover (~ X 1.3, X 1.6) and sodium turnover (~ X 1.5, X 1.25) than did juveniles and subadults. Interpretation of the field data is complicated by integumentary exchange of sodium and water, a size-related aphagia apparently induced by disturbance, and difficulties of adjusting for allometric differences across a wide range of sizes. Nevertheless, it is clear that C. porosus is able to effect considerable economies of water turnover in hyperosmotic salt water and that the secretory capacity of the lingual glands, as measured in the laboratory, is more than enough to account for the highest sodium effluxes that we measured in C. porosus in the field

Bounds for the time to failure of hierarchical systems of fracture

For years limited Monte Carlo simulations have led to the suspicion that the time to failure of hierarchically organized load-transfer models of fracture is non-zero for sets of infinite size. This fact could have a profound significance in engineering practice and also in geophysics. Here, we develop an exact algebraic iterative method to compute the successive time intervals for individual breaking in systems of height $n$ in terms of the information calculated in the previous height $n-1$. As a byproduct of this method, rigorous lower and higher bounds for the time to failure of very large systems are easily obtained. The asymptotic behavior of the resulting lower bound leads to the evidence that the above mentioned suspicion is actually true.Comment: Final version. To appear in Phys. Rev. E, Feb 199

Scaling in the time-dependent failure of a fiber bundle with local load sharing

We study the scaling behaviors of a time-dependent fiber-bundle model with local load sharing. Upon approaching the complete failure of the bundle, the breaking rate of fibers diverges according to $r(t)\propto (T_f-t)^{-\xi}$, where $T_f$ is the lifetime of the bundle, and $\xi \approx 1.0$ is a quite universal scaling exponent. The average lifetime of the bundle $$ scales with the system size as $N^{-\delta}$, where $\delta$ depends on the distribution of individual fiber as well as the breakdown rule.Comment: 5 pages, 4 eps figures; to appear in Phys. Rev.

Ki-67 (30-9) scoring and differentiation of Luminal A- and Luminal B-like breast cancer subtypes

INTRODUCTION: Ki-67 labeling index assessed by immunohistochemical assays has been shown useful in assessing the risk of recurrence for estrogen receptor (ER)-positive HER2-negative breast cancers (BC) and distinguishing Luminal A-like from Luminal B-like tumors. We aimed to assess the performance of the Ventana CONFIRM anti-Ki-67 (30-9) Rabbit Monoclonal Primary Antibody. METHODS: We constructed a case-cohort design based on a random sample (n\u2009=\u2009679) of all patients operated on for a first primary, non-metastatic, ER-positive, HER2-negative BC at the European Institute of Oncology (IEO) Milan, Italy during 1998-2002 and all additional patients (n\u2009=\u2009303) operated during the same period, who developed an event (metastasis in distant organs or death due to BC as primary event) and were not included in the previous subset. Multivariable Cox proportional hazards regression with inverse subcohort sampling probability weighting was used to evaluate the risk of event according to Ki-67 (30-9) and derived intrinsic molecular subtype, using previously defined cutoff values, i.e., respectively 14% and 20%. RESULTS: Ki-67 was\u2009<\u200914% in 318 patients (32.4%), comprised between 14 and 19% in 245 patients (24.9%) and\u2009 65\u200920 in 419 patients (42.7%). At multivariable analysis, the risk of developing distant disease was 1.88 (95% CI 1.20-2.93; P\u2009=\u20090.006) for those with Ki-67 comprised between 14 and 19%, and 3.06 (95% CI 1.93-4.84; P\u2009<\u20090.0001) for those with Ki-67\u2009 65\u200920% compared to those with Ki-67\u2009<\u200914%. Patients with Luminal B-like BC had an approximate twofold risk of developing distant disease (HR\u2009=\u20091.91; 95% CI 1.35-2.71; P\u2009=\u20090.0003) than patients with Luminal A-like BC defined using Ki-67 (30-9). CONCLUSIONS: Ki-67 evaluation using the 30-9 rabbit monoclonal primary antibody was able to stratify patients with ER-positive HER2-negative BC into prognostically distinct groups. Ki-67 assessment, with strict adherence to the international recommendations, should be included among the clinically useful biological parameters for the best treatment of patients with BC

The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration

This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened

Empirical Evidence on the Use of Credit Scoring for Predicting Insurance Losses with Psycho-social and Biochemical Explanations

An important development in personal lines of insurance in the United States is the use of credit history data for insurance risk classification to predict losses. This research presents the results of collaboration with industry conducted by a university at the request of its state legislature. The purpose was to see the viability and validity of the use of credit scoring to predict insurance losses given its controversial nature and criticism as redundant of other predictive variables currently used. Working with industry and government, this study analyzed more than 175,000 policyholders’ information for the relationship between credit score and claims. Credit scores were significantly related to incurred losses, evidencing both statistical and practical significance. We investigate whether the revealed relationship between credit score and incurred losses was explainable by overlap with existing underwriting variables or whether the credit score adds new information about losses not contained in existing underwriting variables. The results show that credit scores contain significant information not already incorporated into other traditional rating variables (e.g., age, sex, driving history). We discuss how sensation seeking and self-control theory provide a partial explanation of why credit scoring works (the psycho-social perspective). This article also presents an overview of biological and chemical correlates of risk taking that helps explain why knowing risk-taking behavior in one realm (e.g., risky financial behavior and poor credit history) transits to predicting risk-taking behavior in other realms (e.g., automobile insurance incurred losses). Additional research is needed to advance new nontraditional loss prediction variables from social media consumer information to using information provided by technological advances. The evolving and dynamic nature of the insurance marketplace makes it imperative that professionals continue to evolve predictive variables and for academics to assist with understanding the whys of the relationships through theory development.IC2 Institut