A model for the quasi-static growth of brittle fractures based on local minimization

We study a variant of the variational model for the quasi-static growth of brittle fractures proposed by Francfort and Marigo. The main feature of our model is that, in the discrete-time formulation, in each step we do not consider absolute minimizers of the energy, but, in a sense, we look for local minimizers which are sufficiently close to the approximate solution obtained in the previous step. This is done by introducing in the variational problem an additional term which penalizes the $L^2$-distance between the approximate solutions at two consecutive times. We study the continuous-time version of this model, obtained by passing to the limit as the time step tends to zero, and show that it satisfies (for almost every time) some minimality conditions which are slightly different from those considered in Francfort and Marigo and in our previous paper, but are still enough to prove (under suitable regularity assumptions on the crack path) that the classical Griffith's criterion holds at the crack tips. We prove also that, if no initial crack is present and if the data of the problem are sufficiently smooth, no crack will develop in this model, provided the penalization term is large enough.Comment: 20 page

LEGAME TRA L\ubfIMMUNODEFICIENZA HIV-CORRELATA E L\ubfINSORGENZA DI TUMORI: ASPETTI DI METODOLOGIA STATISTICA

The aim of the present Ph.D. program was exploring methodological issues arising in studies of cancer incidence, relative risk, and survival in patients with HIV/AIDS (PHA). Aspects related to the first two objectives were explored in the first two years. This thesis described a record-linkage study conducted between the national Italian AIDS Registry and 24 Italian cancer registries to estimate survival after a cancer diagnosis in PHA. More than 2600 cancer cases diagnosed between 1986 and 2005 were included. Survival in PHA was compared with that reported in patients without AIDS using, as comparison group, patients matched for site (1:1 for Kaposi Sarcoma, 1:2 for non-Hodgkin lymphoma, 1:5 for other cancers), sex, age, period of diagnosis, and area of residence. Overall survival and death hazard ratios (HR) compared survival in PWA with cancer to that in cancer patients without AIDS have been calculated. Overall, the 3-year survival rate of PHA with cancer increased from 16% in 1986-1995 to 41% in 1996-2005 period, after the widespread use of antiretroviral therapy (cART). In this period, HR remained higher in PHA than in persons without AIDS (3.0, 95% confidence interval [CI]: 2.7\u20133.4), in particular for cancer with good prognosis, e.g., Hodgkin lymphomas (HR=8.6), non-melanoma skin cancer (H=5.0), and anal cancer (HR=4.0). A sensitivity analysis was performed to evaluate the impact on survival and on HR of different study designs and comparison groups

Family businesses in Eastern European countries: How informal payments affect exports

This article investigates the effect of corruption on the export share of family firms in Eastern European countries. Using the Business Environment and Enterprise Performance Survey and panel data methods, we find that, in contrast to non-family firms, family firms are rather sensitive to corruption. In particular, the export share of family firms is positively associated with informal payments that aim to facilitate business operations. There are at least three compelling explanations for these results. First, if family firms are more risk averse than non-family firms, informal payments may represent additional export risk insurance. Second, informal payments may help family firms compensate for the lack of managerial capabilities to export. Finally, when institutional inefficiencies obstruct business, corruption may be a tool for family firms to protect their socioemotional wealth

Why and when do family firms invest less in talent management? The suppressor effect of risk aversion

none4siThis article explores the complex relationship between family firms and talent management practices. We use an international sample of medium-sized manufacturing firms to show that the relationship between family-owned firms and investment in talent management practices is mediated by the firm’s level of risk aversion, which is, in turn, moderated by industry competition. Risk-averse family-owned firms tend to invest less in talent management practices when industry competition is weak. In contrast, when competition increases, family-owned firms tend to invest in talent as much as non-family-owned firms do.openBasco, Rodrigo; Bassetti, Thomas; Dal Maso, Lorenzo; Lattanzi, NicolaBasco, Rodrigo; Bassetti, Thomas; Dal Maso, Lorenzo; Lattanzi, Nicol

Is accounting enforcement related to risk-taking in the banking industry?

Using a sample of banks from 36 countries, we document that accounting enforcement is negatively related to bank risk-taking. We also provide evidence that accounting enforcement enhances bank stability during the crisis. In addition, we show that banks assume less risk through more conservative lending decisions and a reduction in complexity in jurisdictions with higher accounting enforcement. Our results show that formal institutions such as accounting enforcement are associated with bank financial decisions and risk-taking behavior

A global method for deterministic and stochastic homogenisation in BV

In this paper we study the deterministic and stochastic homogenisation of free-discontinuity functionals under linear growth and coercivity conditions. The main novelty of our deterministic result is that we work under very general assumptions on the integrands which, in particular, are not required to be periodic in the space variable. Combining this result with the pointwise Subadditive Ergodic Theorem by Akcoglu and Krengel, we prove a stochastic homogenisation result, in the case of stationary random integrands. In particular, we characterise the limit integrands in terms of asymptotic cell formulas, as in the classical case of periodic homogenisation

On weak convergence of locally periodic functions

We prove a generalization of the fact that periodic functions converge weakly to the mean value as the oscillation increases. Some convergence questions connected to locally periodic nonlinear boundary value problems are also considered.Comment: arxiv version is already officia

Comparison of the distribution of non-AIDS Kaposi's sarcoma and non-Hodgkin's lymphoma in Europe

To evaluate whether some form of mild immunosuppression may influence the geographical distribution of non-AIDS Kaposi's sarcoma (KS), we correlated incidence rates of KS and non-Hodgkin's lymphoma in individuals aged 60 or more in 18 European countries and Israel. Significant positive correlations emerged but, within highest risk countries (i.e.Italy and Israel), internal correlations were inconsistent. © 1999 Cancer Research Campaig

effects of low protein diets and rumen protected conjugated linoleic acid on production and carcass traits of growing double muscled piemontese bulls

The effects of low-protein (LP) diets and rumen-protected CLA on DMI, ADG, carcass traits, and health status of double-muscled Piemontese young bulls were investigated. Forty-eight bull calves (BW = 237 ± 24 kg) were divided in 4 groups and housed in 12 fully slatted pens. Bulls were fed 2 diets differing in CP density (high-protein (HP) diet: CP = 145 g/kg of DM; LP diet: CP = 108 g/kg of DM) and top-dressed with 80 g/d of rumen-protected CLA or 65 g/d of hydrogenated soybean oil. Orts were collected weekly and feed intake was estimated on a pen basis, with 3 replicated pens for each treatment. Each bull was weighed monthly and examined for alterations of the locomotion system by using the locomotion score as an index of lameness and by counting the number of swollen joints. Carcass quality traits were measured at slaughter, after a feeding period of 332 d. Compared with HP, LP reduced ADG only during the first 4 mo of the trial (1.30 vs. 1.53 kg/d, P = 0.003). However, be- cause of compensatory growth, over the whole trial, no significant effects attributable to CP or to additive were found on final BW (668 kg), ADG (1.19 kg/d), DMI (8.50 or 86 g/d per kg of BW 0.75 ), dressing percentage (67.3%), carcass conformation (5.2 points), and carcass fat covering (1.87 points). Feed efficiency was affected by a CP × additive interaction (P = 0.030), with CLA improving feed efficiency when added to the LP diets, whereas feed efficiency was reduced with the HP diets. The addition of both LP and CLA reduced the number of bulls presenting swollen joints (P = 0.001), and LP improved the locomotion score (P = 0.021) compared with HP. It was concluded that 10.8 g/kg of CP density in the diet is sufficient for double-muscled Piemontese bulls. The reduction in CP density from 145 to 108 g/ kg of DM, in addition to reducing the feeding cost, allows a strong reduction in N consumption without negative consequences on growth performance and car- cass traits

Effects of fat supplementations on milk production and composition, ruminal and plasma parameters of dairy cows

The effects on milk yield and quality caused by the same amount (325 g/d/cow) of lipids provided by 3 different fat sources (hydrogenate palm fat, HF; calcium salt palm fat, CaSF; full-fat toasted soybean, TS), top dressed to a common total mixed ration, were investigated. Supplementations did not affect feed intake and milk yield, but markedly changed the acidic profile of milk fat. CaSF and TS significantly increased the proportions of unsaturated fatty acids of milk fat with respect to control and to HF. The 3 fat sources did not affect the concentrations of ammonia and VFA of rumen fluid. TS only slightly increased (P<0.10) plasma urea content because of a higher dietary protein supply, with respect to the other treatments. The use of a low amount of toasted and cracked full fat soybean seem to be interesting to increase the energy concentration of diets in replacement to commercial fat products and it can be use to modify the milk fat quality increasing the fraction with benefit effects on human health