9,838 research outputs found

    From Finite to Linear Elastic Fracture Mechanics by Scaling

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    In the setting of finite elasticity we study the asymptotic behaviour of a crack that propagates quasi-statically in a brittle material. With a natural scaling of size and boundary conditions we prove that for large domains the evolution with finite elasticity converges to the evolution with linearized elasticity. In the proof the crucial step is the (locally uniform) convergence of the non-linear to the linear energy release rate, which follows from the combination of several ingredients: the Γ\Gamma-convergence of re-scaled energies, the strong convergence of minimizers, the Euler-Lagrange equation for non-linear elasticity and the volume integral representation of the energy release

    Surface Electrical Resistivity Tomography: a non-invasive tool to assess the compaction in paddy soils

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    S oil compaction has direct effects on soil physical properties (increase in soil strength, bulk density, decrease in total porosity, soil aeration, water infiltration rate, and saturated hydraulic conductivity) often reducing root penetration and plant growth, thereby causing a reduction of soil productivity. However, the presence of compacted layers in rice paddy fields increases the efficiency of the traditional flooding irrigation method. For this reason, the use of monitoring tools to detect depth, thickness and lateral continuity of compacted soil layers in paddy fields is of crucial importance for the assessment of their irrigation efficiency. Electrical Resistivity Tomography (ERT) is a non-invasive geophysical method which allows to detect soil horizons with different degrees of compaction. Particularly, arrays constituted of short electrodes spaced a few centimeters can be used to investigate with high vertical resolution the soil profile. In a sandy loam paddy field located in the Lomellina region (PV; RISTEC project, RDP-EU, Lombardy Region), a surface ERT survey was conducted in February 2019 to verify the effectiveness of this technique in assessing soil compaction. The ERT was carried out with Wenner arrays of 48 electrodes spaced 0.1 m along a 5 m transect, to investigate the soil profile up to about 1 m depth in proximity of a soil profile trench dug for soil description and sampling. The results of the traditional soil survey (accurate description of soil horizons, including the compacted layer) were considered as reference data to evaluate the reliability of ERT results. During the ERT survey, soil samples were collected at different depths and distances along the ERT transect: texture, bulk density and porosity were successively measured in laboratory. Moreover, the volumetric soil water content was measured with a probe (ML2 ThetaProbe, Delta-T Devices). Main results show that the correlation between electrical resistivity (ER) and bulk density, soil porosity and volumetric water content is well in line with those observed in recent studies. Data points in the scatter plots are clustered based on the bulk density values; particularly, the cluster corresponding to high bulk density values (i.e. compacted soil) includes the measurement points at the depth where the ERT image shows a greater ER gradient. This depth also corresponds to the compacted layer observed during the investigation of soil profile with traditional methods. These results confirm that compacted layers can be effectively detected in ERT images by identifying depths characterized by higher ER gradients in soils with a relatively homogeneous soil texture. Consequently, an integrated approach combining surface ERT and soil sampling with a hand auger at a few depths to check the texture homogeneity and eventually collect a few soil samples for further analysis (e.g., bulk density, volumetric water content, soil hydraulic conductivity) could be explored to assess the presence and continuity of compacted layers in paddy soils, instead of intensive and extremely invasive surveys

    Oral contraceptives and primary liver cancer.

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    The relative risk for developing primary liver cancer in northern Italian users of oral contraceptives, compared to matched controls was calculated based on reported cases in hospitals in the greater Milan area from 1984-1987. The incidence of and mortality from primary liver cancer, as well as the prevalence of oral contraceptive usage, have both been rising to Italy since the late 1950s. 21 cases of liver cancer, in women aged 32-59 (median 50), occurred in the Milan area during the study period. These women, and 145 controls matched for age but admitted to hospitals for a variety of non-neoplastic diseases, were interviewed with a structured questionnaire covering socio-demographics, life style, diet, medical history, and history of use of oral contraceptives and other drugs. 19.0% of the cases had used oral contraceptives compared to 7.6% of controls, a relative risk of 1.8 for up to 5 years' use, and 8.3 for 5 years. History of hepatitis was associated with 14% of cases and 7% of controls. Italians have a higher incidence of liver neoplasms that northern Europeans and Americans, probably because of higher incidence of risk factors, such as hepatitis and alcohol use. The attributable risk for oral contraception, however, is lower in this population

    Prevalence of COVID 19 like symptoms in Italy and Lombardy, March-April 2020, and their implications on cancer prevention, diagnosis and management

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    Two population-based surveys on coronavirus disease-2019 (Covid-19)-like symptoms were conducted by BVA-Doxa on representative samples of the general population from Italy and its largest region, Lombardy, with over 10 million inhabitants and heavily struck by Covid-19, on 27-30 March and 3-7 April, on a total of 2000 individuals - 353 from Lombardy. Overall, 14.2% of Italians - and 19.6% in Lombardy - reported Covid-19-like symptoms. The estimated prevalence was higher in the young, in smokers, and in Lombardy over the period 20 March to 7 April. Although the influenza season was ended by mid-March, at least part of the symptoms may be not Covid-19 related. Even assuming that only half are, at least 7% of Italians and 10% in Lombardy had been affected by Covid-19. To these, asymptomatic or paucisymptomatic cases have to be added. These estimates are at least one or two orders of magnitude larger than official registered cases. This has major implications for cancer prevention, management and treatment

    Sc substitution for Mg in MgB2: effects on Tc and Kohn anomaly

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    Here we report synthesis and characterization of Mg_{1-x}Sc_{x}B_{2} (0.12T_{c}>6 K. We find that the Sc doping moves the chemical potential through the 2D/3D electronic topological transition (ETT) in the sigma band where the ``shape resonance" of interband pairing occurs. In the 3D regime beyond the ETT we observe a hardening of the E_{2g} Raman mode with a significant line-width narrowing due to suppression of the Kohn anomaly over the range 0<q<2k_{F}.Comment: 8 pages, 4 EPS figures, to be published in Phys. Rev.

    Lung cancer mortality in European women: recent trends and perspectives

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    Background: Lung cancer mortality in men has been declining since the late 1980s in most European countries. In women, although rates are still appreciably lower than those for men, steady upward trends have been observed in most countries. To quantify the current and future lung cancer epidemic in European women, trends in lung cancer mortality in women over the last four decades were analyzed, with specific focus on the young. Patients and methods: Age-standardized (world standard) lung cancer mortality rates per 100 000 women—at all ages, and truncated 35-64 and 20-44 years—were derived from the WHO for the European Union (EU) as a whole and for 33 separate European countries. Joinpoint regression analysis was used to identify points where a significant change in trends occurred. Results: In the EU overall, female lung cancer mortality rates rose by 23.8% between 1980-1981 and 1990-1991 (from 7.8 to 9.6/100 000), and by 16.1% thereafter, to reach the value of 11.2/100 000 in 2000-2001. Increases were smaller in the last decade in several countries. Only in England and Wales, Latvia, Lithuania, Russia and Ukraine did female lung cancer mortality show a decrease over the last decade. In several European countries, a decline in lung cancer mortality in young women (20-44 years) was observed over the last decade. Conclusions: Although female lung cancer mortality is still increasing in most European countries, the more favorable trends in young women over recent calendar years suggest that if effective interventions to control tobacco smoking in women are implemented, the lung cancer epidemic in European women will not reach the levels observed in the US

    Declining mortality from kidney cancer in Europe

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    Mortality rates from kidney cancer increased throughout Europe up until the late 1980s or early 1990s. Trends in western European countries, the European Union (EU) and selected central and eastern European countries have been updated using official death certification data for kidney cancer abstracted from the World Health Organisation (WHO) database over the period 1980-1999. In EU men, death rates increased from 3.92 per 100 000 (age standardised, world standard) in 1980-81 to 4.63 in 1994-95, and levelled off at 4.15 thereafter. In women, corresponding values were 1.86 in 1980-81, 2.04 in 1994-95 and 1.80 in 1998-99. Thus, the fall in kidney cancer mortality over the last 5 years was over 10% for both sexes in the EU. The largest falls were in countries with highest mortality in the early 1990s, such as Germany, Denmark and the Netherlands. Kidney cancer rates levelled off, but remained very high, in the Czech Republic, Baltic countries, Hungary, Poland and other central European countries. Thus, in the late 1990s, a greater than three-fold difference in kidney cancer mortality was observed between the highest rates in the Czech Republic, the Baltic Republics and Hungary, and the lowest ones in Romania, Portugal and Greece. Tobacco smoking is the best recognised risk factor for kidney cancer, and the recent trends in men, mainly in western Europe, can be related to a reduced prevalence of smoking among men. Tobacco, however, cannot account for the recent trends registered in wome
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