Core Softening in Cavernously Weathered Tonalite

Tonalite exhibiting cavernous weathering at Catavina, Baja California, was investigated to determine the factors which contribute to differential hardness within the rock. Soft cores have a high degree of chemical weathering as indicated by kaolinite content. Hematite formed from the leaching of biotite occurs in coatings on rock surfaces, but the hardening effect of the coating is insignificant compared to the core-softening of the interior. The hardness, measured by an abrasion resistance hardness tester, is inversely correlated with kaolinite content in the tonalite. A one-dimensional water flow model was developed for core-softened. cavernously weathered boulders. It indicates that during infiltration and dessication the moisture flux is greatest through the cavern interior wall because of changes in the hydraulic conductivities induced by core softening. Therefore, the cavern interior wall should have the greatest weathering rate in the boulder

Radiolytic effects of plutonium.

Plutonium isotopes, most of them a-emitters, cause radiolytic changes in the matrix, in whic h they are embedded. The internal irradiation of Pu metal or its alloys results in physical changes, largel y as a result of the formation of helium bubbles, well-known to material scientists and weapons specialists . In all other media where plutonium occurs, usually as Pu'+ in an ionic form, the results of irradiation ar e chemical in nature. Homogenous media containing Pu, are often aqueous or non-aqueous solutions o f plutonium compounds, mostly originating during processing of spent nuclear fuel or from Pu processing . Heterogenous matrices containing plutonium are more complex from the point of view of radiolysis; they usually contain a variety of combinations of common materials contaminated with radionuclides . This class of radioactive materials represents a challenge for the management of plutonium waste . One has to consider a range of time scales for radiolytic effects (and consequently a several orders o f magnitude range of the cumulative dose) beginning with waste generation, through packaging, transportation, to the period of final storage . Final storage could be for thousands of years in deep geologic repositories . At every ' stage of that time scale, radiolysis proceeds continuously an d cumulative effects c an complicate operating procedures and final disposition . The results presented here have been obtained from experiments that have irradiated of model materials, which are typically the objects of contamination with plutonium . They were irradiated with linearly accelerated electrons up to very high dose rates, adjusted to simulate any contamination at any point on the time scale

The motion of a fluid-rigid disc system at the zero limit of the rigid disc radius

We consider the two-dimensional motion of the coupled system of a viscous incompressible fluid and a rigid disc moving with the fluid, in the whole plane. The fluid motion is described by the Navier-Stokes equations and the motion of the rigid body by conservation laws of linear and angular momentum. We show that, assuming that the rigid disc is not allowed to rotate, as the radius of the disc goes to zero, the solution of this system converges, in an appropriate sense, to the solution of the Navier-Stokes equations describing the motion of only fluid in the whole plane. We also prove that the trajectory of the centre of the disc, at the zero limit of its radius, coincides with a fluid particle trajectory.Comment: 29 pages, 0 figure

Association of Interprofessional Discharge Planning Using an Electronic Health Record Tool With Hospital Length of Stay Among Patients with Multimorbidity: A Nonrandomized Controlled Trial

Whether interprofessional collaboration is effective and safe in decreasing hospital length of stay remains controversial.; To evaluate the outcomes and safety associated with an electronic interprofessional-led discharge planning tool vs standard discharge planning to safely reduce length of stay among medical inpatients with multimorbidity.; This multicenter prospective nonrandomized controlled trial used interrupted time series analysis to examine medical acute hospitalizations at 82 hospitals in Switzerland. It was conducted from February 2017 through January 2019. Data analysis was conducted from March 2021 to July 2022.; After a 12-month preintervention phase (February 2017 through January 2018), an electronic interprofessional-led discharge planning tool was implemented in February 2018 in 7 intervention hospitals in addition to standard discharge planning.; Mixed-effects segmented regression analyses were used to compare monthly changes in trends of length of stay, hospital readmission, in-hospital mortality, and facility discharge after the implementation of the tool with changes in trends among control hospitals.; There were 54 695 hospitalizations at intervention hospitals, with 27 219 in the preintervention period (median [IQR] age, 72 [59-82] years; 14 400 [52.9%] men) and 27 476 in the intervention phase (median [IQR] age, 72 [59-82] years; 14 448 [52.6%] men) and 438 791 at control hospitals, with 216 261 in the preintervention period (median [IQR] age, 74 [60-83] years; 109 770 [50.8%] men) and 222 530 in the intervention phase (median [IQR] age, 74 [60-83] years; 113 053 [50.8%] men). The mean (SD) length of stay in the preintervention phase was 7.6 (7.1) days for intervention hospitals and 7.5 (7.4) days for control hospitals. During the preintervention phase, population-averaged length of stay decreased by -0.344 hr/mo (95% CI, -0.599 to -0.090 hr/mo) in control hospitals; however, no change in trend was observed among intervention hospitals (-0.034 hr/mo; 95% CI, -0.646 to 0.714 hr/mo; difference in slopes, P = .09). Over the intervention phase (February 2018 through January 2019), length of stay remained unchanged in control hospitals (slope, -0.011 hr/mo; 95% CI, -0.281 to 0.260 hr/mo; change in slope, P = .03), but decreased steadily among intervention hospitals by -0.879 hr/mo (95% CI, -1.607 to -0.150 hr/mo; change in slope, P = .04, difference in slopes, P = .03). Safety analyses showed no change in trends of hospital readmission, in-hospital mortality, or facility discharge over the whole study time.; In this nonrandomized controlled trial, the implementation of an electronic interprofessional-led discharge planning tool was associated with a decline in length of stay without an increase in hospital readmission, in-hospital mortality, or facility discharge.; isrctn.org Identifier: ISRCTN83274049