26,495 research outputs found
Enhanced dielectrophoresis of nanocolloids by dimer formation
We investigate the dielectrophoretic motion of charge-neutral, polarizable
nanocolloids through molecular dynamics simulations. Comparison to analytical
results derived for continuum systems shows that the discrete charge
distributions on the nanocolloids have a significant impact on their coupling
to the external field. Aggregation of nanocolloids leads to enhanced
dielectrophoretic transport, provided that increase in the dipole moment upon
aggregation can overcome the related increase in friction. The dimer
orientation and the exact structure of the nanocolloid charge distribution are
shown to be important in the enhanced transport
Experimental investigation of the asymmetric spectroscopic characteristics of electron- and hole-doped cuprates
Quasiparticle tunneling spectroscopic studies of electron- (n-type) and hole-doped (p-type) cuprates reveal that the pairing symmetry, pseudogap phenomenon and spatial homogeneity of the superconducting order parameter are all non-universal. We compare our studies of p-type YBa2Cu3O7-delta and n-type infinite-layer Sr(0.9)Ln(0.1)CuO(2) (Ln = La, Gd) systems with results from p-type Bi2Sr2CaCu2Ox and n-type one-layer Nd1.85Ce0.15CuO4 cuprates, and attribute various non-universal behavior to different competing orders in p-type and n-type cuprates
Understanding World Heritage from the local perspective on the Ningaloo Coast, Western Australia
The remote Ningaloo Coast region, the location of Australia’s largest fringing coral reef, was designated as World Heritage in 2011 because of its outstanding natural values
Simulation of a finishing operation : milling of a turbine blade and influence of damping
Milling is used to create very complex geometries and thin parts, such as turbine blades. Irreversible geometric defects may appear during finishing operations when a high surface quality is expected. Relative vibrations between the tool and the workpiece must be as small as possible, while tool/workpiece interactions can be highly non-linear. A general virtual machining approach is presented and illustrated. It takes into account the relative motion and vibrations of the tool and the workpiece. Both deformations of the tool and the workpiece are taken into account. This allows predictive simulations in the time domain. As an example the effect of damping on the behavior during machining of one of the 56 blades of a turbine disk is analysed in order to illustrate the approach potential
Three-dimensional mortar-based frictional contact treatment in isogeometric analysis with NURBS
Cataloged from PDF version of article.A three-dimensional mortar-based frictional contact treatment in isogeometric analysis with NURBS is presented in the finite deformation regime. Within a setting where the NURBS discretization of the contact surface is inherited directly from the NURBS discretization of the volume, the contact integrals are evaluated through a mortar approach where the geometrical and frictional contact constraints are treated through a projection to control point quantities. The formulation delivers a non-negative pressure distribution and minimally oscillatory local contact interactions with respect to alternative Lagrange discretizations independent of the discretization order. These enable the achievement of improved smoothness in global contact forces and moments through higher-order geometrical descriptions. It is concluded that the presented mortar-based approach serves as a common basis for treating isogeometric contact problems with varying orders of discretization throughout the contact surface and the volume. (C) 2011 Elsevier B.V. All rights reserved
First passage time for subdiffusion: The nonextensive entropy approach versus the fractional model
We study the similarities and differences between different models concerning
subdiffusion. More particularly, we calculate first passage time (FPT)
distributions for subdiffusion, derived from Greens' functions of nonlinear
equations obtained from Sharma-Mittal's, Tsallis's and Gauss's nonadditive
entropies. Then we compare these with FPT distributions calculated from a
fractional model using a subdiffusion equation with a fractional time
derivative. All of Greens' functions give us exactly the same standard relation
which characterizes subdiffusion
(), but generally FPT's are not equivalent to one another. We will
show here that the FPT distribution for the fractional model is asymptotically
equal to the Sharma--Mittal model over the long time limit only if in the
latter case one of the three parameters describing Sharma--Mittal entropy
depends on , and satisfies the specific equation derived in this paper,
whereas the other two models mentioned above give different FTPs with the
fractional model. Greens' functions obtained from the Sharma-Mittal and
fractional models - for obtained from this particular equation - are very
similar to each other. We will also discuss the interpretation of subdiffusion
models based on nonadditive entropies and the possibilities of experimental
measurement of subdiffusion models parameters.Comment: 12 pages, 8 figure
Thigh fat and muscle each contribute to excess cardiometabolic risk in South Asians, independent of visceral adipose tissue.
OBJECTIVE: To compare fat distribution and associations between fat depots and cardiometabolic traits in South Asians and Europeans.
METHODS: Five hundred and fourteen South Asians and 669 Europeans, aged 56-86. Questionnaires, record review, blood testing, and coronary artery calcification scores provided diabetes and clinical plus subclinical coronary heart disease (CHD) diagnoses. Abdominal visceral (VAT) and subcutaneous adipose tissue, thigh subcutaneous adipose tissue (TSAT), intermuscular and intramuscular thigh fat and thigh muscle were measured by CT.
RESULTS: Accounting for body size, South Asians had greater VAT and TSAT than Europeans, but less thigh muscle. Associations between depots and disease were stronger in South Asians than Europeans. In multivariable analyses in South Asians, VAT was positively associated with diabetes and CHD, while TSAT and thigh muscle were protective for diabetes, and thigh muscle for CHD. Differences in VAT and thigh muscle only partially explained the excess diabetes and CHD in South Asians versus Europeans. Insulin resistance did not account for the effects of TSAT or thigh muscle.
CONCLUSIONS: Greater VAT and TSAT and lesser thigh muscle in South Asians contributed to ethnic differences in cardiometabolic disease. Effects of TSAT and thigh muscle were independent of insulin resistance
The contribution of 211 particles to the mechanical reinforcement mechanism of 123 superconducting single domains
Hardness and fracture toughness of Dy-123 single-domains were studied by
Vickers micro-indentation. A significant anisotropy of the mechanical
properties was observed. Hardness tests give higher values when performed in
(001) planes rather than in planes parallel to the c-axis. Moreover cracks
pattern around the indentation follows preferential orientation in planes
parallel to the c-axis whereas a classical ''four-cracks'' pattern is observed
in the (001) planes. It has been possible to show the crucial role played by
the 211-particles in the deviating mechanism of cracks and the relevance of the
211-particle distribution high homogeneity in the material.Comment: 14 pages, including 5 figures and 1 Table. submitted to Supercond.
Sci. Techno
Trends in HIV testing and recording of HIV status in the UK primary care setting: a retrospective cohort study 1995-2005
Objectives: To provide nationally representative data on trends in HIV testing in primary care and to estimate the proportion of diagnosed HIV positive individuals known to general practitioners (GPs). Methods: We undertook a retrospective cohort study between 1995 and 2005 of all general practices contributing data to the UK General Practice Research Database (GPRD), and data on persons accessing HIV care (Survey of Prevalent HIV Infections Diagnosed). We identified all practice-registered patients where an HIV test or HIV positive status is recorded in their general practice records. HIV testing in primary care and prevalence of recorded HIV positive status in primary care were estimated. Results: Despite 11-fold increases in male testing and 19-fold increases in non-pregnant female testing between 1995 and 2005, HIV testing rates remained low in 2005 at 71.3 and 61.2 tests per 100 000 person years for males and females, respectively, peaking at 162.5 and 173.8 per 100 000 person years at 25–34 years of age. Inclusion of antenatal tests yielded a 129-fold increase in women over the 10-year period. In 2005, 50.7% of HIV positive individuals had their diagnosis recorded with a lower proportion in London (41.8%) than outside the capital (60.1%). Conclusion: HIV testing rates in primary care remain low. Normalisation of HIV testing and recording in primary care in antenatal testing has not been accompanied by a step change in wider HIV testing practice. Recording of HIV positive status by GPs remains low and GPs may be unaware of HIV-related morbidity or potential drug interactions
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