3,931 research outputs found
Hysteretic clustering in granular gas
Granular material is vibro-fluidized in N=2 and N=3 connected compartments,
respectively. For sufficiently strong shaking the granular gas is
equi-partitioned, but if the shaking intensity is lowered, the gas clusters in
one compartment. The phase transition towards the clustered state is of 2nd
order for N=2 and of 1st order for N=3. In particular, the latter is
hysteretic. The experimental findings are accounted for within a dynamical
model that exactly has the above properties
Sudden Collapse of a Granular Cluster
Single clusters in a vibro-fluidized granular gas in N connected compartments
become unstable at strong shaking. They are experimentally shown to collapse
very abruptly. The observed cluster lifetime (as a function of the driving
intensity) is analytically calculated within a flux model, making use of the
self-similarity of the process. After collapse, the cluster diffuses out into
the uniform distribution in a self-similar way, with an anomalous diffusion
exponent 1/3.Comment: 4 pages, 4 figures. Figure quality has been reduced in order to
decrease file-siz
De bloembollenstreek : resultaten van een veldbodemkundig onderzoek in het bloembollengebied tussen Leiden en het Noordzeekanaal
The Dutch Bulb Fields are situated on the Beach-ridge landscape between the Rhine Estuary and the Y-Polders in the mid-western part of North Holland and South Holland. Culture of some horticultural crops (tulips, daffodils) is important in this area because of the special requirements of these crops: rather coarse, calcareous, deep sandy and highly porous soils easy to penetrate by roots, without organic matter, without impermeable layers and a stable watertable. Continuous deep digging is inevitable. Soil formation (mainly decalcification) in the beach ridges over some 3000 years has caused non-calcareous topsoils and a slight podsolization; the soils have been improved by digging off sand. The area has been influenced by peat growth, marine and estuarine sediments and shifting sand. The soil survey resulted in a soil map, indicating soil quality. From the results ensued the recommendation of improving soil by suction dredging. This had to be planned and carried out very carefully, because the formation of humous and clayey layers in the new profile would make the soil completely unsuitable for valuable horticultural crops. Geological studies on Middle and Late Holocene geology and stratigraphy showed that the beach ridges were formed during and after the deposition of the Atlantic Old Marine Clay (4000-2000 B.C.).<p/
Cross section normalization in proton-proton collisions at = 2.76 TeV and 7 TeV, with ALICE at LHC
Measurements of the cross sections of the reference processes seen by the
ALICE trigger system were obtained based on beam properties measured from van
der Meer scans. The measurements are essential for absolute cross section
determinations of physics processes.
The paper focuses on instrumental and technical aspects of detectors and
accelerators, including a description of the extraction of beam properties from
the van der Meer scan. As a result, cross sections of reference processes seen
by the ALICE trigger system are given for proton-proton collisions at two
energies; =2.76 TeV and 7 TeV, together with systematic uncertainties
originating from beam intensity measurements and other detector effects.
Consistency checks were performed by comparing to data from other experiments
in LHC.Comment: Quark Matter 2011 Conference Proceedings, 4 pages, 2 figure
Reducing the anticholinergic and sedative load in older patients on polypharmacy by pharmacist-led medication review: A randomised controlled trial
© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted. Objective To evaluate if a pharmacist-led medication review is effective at reducing the anticholinergic/sedative load, as measured by the Drug Burden Index (DBI). Design Randomised controlled single blind trial. Setting 15 community pharmacies in the Northern Netherlands. Participants 157 community-dwelling patients aged ≥65 years who used ≥5 medicines for ≥3 months, including at least one psycholeptic/psychoanaleptic medication and who had a DBI≥1. Intervention A medication review by the community pharmacist in collaboration with the patient's general practitioner and patient. Primary and secondary outcomes measures The primary outcome was the proportion of patients whose DBI decreased by at least 0.5. Secondary outcomes were the presence of anticholinergic/sedative side effects, falls, cognitive function, activities of daily living, quality of life, hospital admission and mortality. Data were collected at baseline and 3 months follow-up. Results Mean participant age was 75.7 (SD, 6.9) years in the intervention arm and 76.6 (SD, 6.7) years in the control arm, the majority were female (respectively 69.3% and 72.0%). Logistic regression analysis showed no difference in the proportion of patients with a≥0.5 decrease in DBI between intervention arm (17.3%) and control arm (15.9%), (OR 1.04, CI 0.47 to 2.64, p=0.927). Intervention patients scored higher on the Digit Symbol Substitution Test, measure of cognitive function (OR 2.02, CI 1.11 to 3.67, p=0.021) and reported fewer sedative side effects (OR 0.61, CI 0.40 to 0.94, p=0.024) at follow-up. No significant difference was found for other secondary outcomes. Conclusions Pharmacist-led medication review as currently performed in the Netherlands was not effective in reducing the anticholinergic/sedative load, measured with the DBI, within the time frame of 3 months. Preventive strategies, signalling a rising load and taking action before chronic use of anticholinergic/sedative medication is established may be more successful. Trial registration number NCT02317666
Micromechanical model for off-axis creep rupture in unidirectional composites undergoing finite strains
A microscale numerical framework for modeling creep rupture in unidirectional composites under off-axis loading is presented, building on recent work on imposing off-axis loading on a representative volume element. Creep deformation of the thermoplastic polymer matrix is accounted for by means of the Eindhoven Glassy Polymer material model. Creep rupture is represented with cohesive cracks, combining an energy-based initiation criterion with a time-dependent cohesive law and a global failure criterion based on the minimum in homogenized creep strain-rate. The model is compared against experiments on carbon/PEEK composite material tested at different off-axis angles, stress levels and temperatures. Creep deformation is accurately reproduced by the model, except for small off-axis angles, where the observed difference is ascribed to macroscopic variations in the experiment. Trends in rupture time are also reproduced although quantitative rupture time predictions are not for all test cases accurate.</p
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