2,172 research outputs found
Quantifying geogrid reinforcement mechanism in roadway performance using Cyclic Plate Load (CPL) test
For decades, geogrids have been used successfully to improve performance in both paved and unpaved roadway construction. Even though the current state of practice differentiates between the design methodology incorporating geogrids in paved and unpaved roadways, the true improvement contribution of geogrids is to the base layer, or to the layer that is placed directly on top of it. It has been established that the three reinforcement mechanisms by which geogrids enhance roadway performance are: lateral restraint, bearing capacity increase and membrane tension support. In order to quantify these mechanisms and their contribution to the roadway performance improvement, two Cyclic Plate Load (CPL) tests were carried out, one on a paved section with a hot mix asphalt (HMA) top layer, and the second on an unpaved section. The tests included control and reinforced sections. Each test was instrumented with Linear Variable Differential Transducers (LVDTs) at the surface and subgrade levels that measured the displacements at these levels while the cyclic loads were applied. The paper presents the results in terms of the Reinforcement Improvement Ratio (RIR) which is calculated as the ratio between the number of load cycles of the reinforced section divided by the number of cycles of the control section at the same level of displacement. It was found that RIR is almost identical for surface displacements for both paved and unpaved roadway sections indicating the similar lateral restraint effect of the used product. The bearing capacity increase and membrane tension support vary between paved and unpaved sections depending on the level of displacement at the base course and subgrade contact. The results of those two tests were used to put an emphasis on quantifying the mechanism by which the geogrid contributes to the roadway performance improvement regardless whether it is paved or unpaved. The results could be used empirically to modify the current state of practice for geogrid contribution in paved and unpaved roadways. It should be noted that the terms soil reinforcement and soil stabilization have been used interchangeably to indicate the above soil improvements using geogrids
Artificially depleted plasmas are not necessarily commutable with native patient plasmas for International Sensitivity Index calibration and International Normalized Ratio derivation: a rebuttal
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Differential monocular vs. binocular pupil responses from melanopsin-based photoreception in patients with anterior ischemic optic neuropathy.
We examined the effect of anterior ischemic optic neuropathy (AION) on the activity of intrinsically photosensitive retinal ganglion cells (ipRGCs) using the pupil as proxy. Eighteen patients with AION (10 unilateral, 8 bilateral) and 29 age-matched control subjects underwent chromatic pupillometry. Red and blue light stimuli increasing in 0.5 log steps were presented to each eye independently under conditions of dark and light adaptation. The recorded pupil contraction was plotted against stimulus intensity to generate scotopic and photopic response curves for assessment of synaptically-mediated ipRGC activity. Bright blue light stimuli presented monocularly and binocularly were used for melanopsin activation. The post-stimulus pupil size (PSPS) at the 6th second following stimulus offset was the marker of intrinsic ipRGC activity. Finally, questionnaires were administered to assess the influence of ipRGCs on sleep. The pupil response and PSPS to all monocularly-presented light stimuli were impaired in AION eyes, indicating ipRGC dysfunction. To binocular light stimulation, the PSPS of AION patients was similar to that of controls. There was no difference in the sleep habits of the two groups. Thus after ischemic injury to one or both optic nerves, the summated intrinsic ipRGC activity is preserved when both eyes receive adequate light exposure
Os efeitos-colaterais psiquiátricos do rimonabanto
OBJECTIVE: Experimental evidence has suggested that drugs that enhance cannabinoid type-1 (CB1) receptor activity may induce anxiolytic and antidepressant effects, whilst the opposite has been reported with antagonists. Thus, the objective of the present review is to discuss the potential psychiatric side-effects of CB1 receptor antagonists, such as rimonabant, which has been recently marketed in several countries for the treatment of smoking cessation, obesity and associated metabolic disorders. METHOD: Literature searches were performed in PubMed and SciELO databases up to February 2009. The terms searched were "obesity", "rimonabant", "cannabinoids", "unwanted effects", "diabetes", "smoking cessation" and "side-effects". RESULTS: Clinical trials have revealed that rimonabant may promote weight loss in obese patients, although it may also induce symptoms of anxiety and depression. DISCUSSION: Patients taking CB1 receptor antagonists should be carefully investigated for psychiatric side-effects. These drugs should not be prescribed for those already suffering from mental disorders. Nevertheless, the development of new compounds targeting the endocannabinoid system for the treatment of several conditions would be necessary and opportune.OBJETIVO: Evidência experimental sugere que drogas que aumentam a atividade dos receptores canabinóides tipo 1 (CB1) podem induzir efeitos ansiolíticos ou antidepressivos, enquanto que o oposto tem sido relatado com antagonistas. Assim, o objetivo da presente revisão é discutir os potenciais efeitos-colaterais psiquiátricos de antagonistas do receptor CB1, como o rimonabanto, que foi recentemente liberado para comercialização em diversos países para o tratamento do tabagismo, obesidade e de desordens metabólicas associadas. MÉTODO: Foi realizada uma busca na literatura no PubMed e Scielo até fevereiro de 2009, com os termos "obesity", "rimonabant", "cannabinoids", "unwanted effects", "diabetes" , "smoking cessation" e "side effects". RESULTADOS: Ensaios clínicos revelaram que o rimonabanto pode produzir perda de peso em pacientes obesos, embora também possa induzir sintomas de ansiedade e depressão. DISCUSSÃO: Pacientes tomando antagonistas do receptor CB1 devem ser cuidadosamente examinados quanto aos efeitos-colaterais psiquiátricos. Estas drogas não devem ser prescritas a indivíduos que já sofrem de transtornos mentais. Entretanto, o desenvolvimento de novos compostos que atuem no sistema endocanabinóide para o tratamento das mais diversas condições parece necessário e oportuno
Some new well-posedness results for continuity and transport equations, and applications to the chromatography system
We obtain various new well-posedness results for continuity and transport
equations, among them an existence and uniqueness theorem (in the class of
strongly continuous solutions) in the case of nearly incompressible vector
fields, possibly having a blow-up of the BV norm at the initial time. We apply
these results (valid in any space dimension) to the k x k chromatography system
of conservation laws and to the k x k Keyfitz and Kranzer system, both in one
space dimension.Comment: 33 pages, minor change
Pauli spin blockade in CMOS double quantum dot devices
Silicon quantum dots are attractive candidates for the development of
scalable, spin-based qubits. Pauli spin blockade in double quantum dots
provides an efficient, temperature independent mechanism for qubit readout.
Here we report on transport experiments in double gate nanowire transistors
issued from a CMOS process on 300 mm silicon-on-insulator wafers. At low
temperature the devices behave as two few-electron quantum dots in series. We
observe signatures of Pauli spin blockade with a singlet-triplet splitting
ranging from 0.3 to 1.3 meV. Magneto-transport measurements show that
transitions which conserve spin are shown to be magnetic-field independent up
to B = 6 T.Comment: 5 pages , 4 figure
Principles of International Law for Multilateral Development Banks: The Obligation to Respect Human Rights
41 pages.
January, 2009
www.indianlaw.or
Principles of International Law for Multilateral Development Banks: The Obligation to Respect Human Rights
41 pages.
January, 2009
www.indianlaw.or
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