2,947 research outputs found
Clinical relevance of soluble c-erbB-2 for patients with metastatic breast cancer predicting the response to second-line hormone or chemotherapy
Concentrations of soluble c-erbB-2 were determined in the sera of 64 patients with distant metastasis from advanced breast cancer receiving second-line hormone or chemotherapy in comparison to 35 breast cancer patients without detectable recurrent disease and 17 healthy blood donors. The sera of non-metastatic breast cancer patients contained s-erbB-2 concentrations similar to those of healthy blood donors. Patients with distant metastasis from advanced breast cancer had significantly higher values of s-erbB-2 in comparison to patients with non-disseminated disease (mean: 59.6 vs. 11.6 U/ml; p = 0.022). A significant correlation was observed between s-erbB-2 serum levels and serum LDH concentrations (p < 0.001), levels of alkaline phosphatase (p < 0.001), and the presence of hepatic metastasis (p = 0.001). Time to tumor progression was significantly shorter in patients with s-erbB-2 levels above 40 U/ml (mean: 23.4 vs. 56.7 months; p = 0.002). Furthermore, breast cancer patients with hepatic metastasis and those with elevated s-erbB-2 serum levels above 40 U/ml had limited response to hormone or chemotherapy. Non-responders had significantly higher s-erbB-2 levels (mean: 270.3, range: 42-500 U/ml;) compared with the responder group (mean: 23.1, range: 0-149 U/ml; p < 0.001). Logistic regression analysis indicated that elevated s-erbB-2 serum levels above 40 U/ml independently predicted an unfavorable response to second-line hormone or chemotherapy in patients with advanced metastatic breast cancer. Copyright (C) 2002 S. KargerAG, Basel
Interaction-induced charge and spin pumping through a quantum dot at finite bias
We investigate charge and spin transport through an adiabatically driven,
strongly interacting quantum dot weakly coupled to two metallic contacts with
finite bias voltage. Within a kinetic equation approach, we identify
coefficients of response to the time-dependent external driving and relate
these to the concepts of charge and spin emissivities previously discussed
within the time-dependent scattering matrix approach. Expressed in terms of
auxiliary vector fields, the response coefficients allow for a straightforward
analysis of recently predicted interaction-induced pumping under periodic
modulation of the gate and bias voltage [Phys. Rev. Lett. 104, 226803 (2010)].
We perform a detailed study of this effect and the related adiabatic Coulomb
blockade spectroscopy, and, in particular, extend it to spin pumping. Analytic
formulas for the pumped charge and spin in the regimes of small and large
driving amplitude are provided for arbitrary bias. In the absence of a magnetic
field, we obtain a striking, simple relation between the pumped charge at zero
bias and at bias equal to the Coulomb charging energy. At finite magnetic
field, there is a possibility to have interaction-induced pure spin pumping at
this finite bias value, and generally, additional features appear in the pumped
charge. For large-amplitude adiabatic driving, the magnitude of both the pumped
charge and spin at the various resonances saturate at values which are
independent of the specific shape of the pumping cycle. Each of these values
provide an independent, quantitative measurement of the junction asymmetry.Comment: 17 pages, 8 figure
Low temperature acoustic properties of amorphous silica and the Tunneling Model
Internal friction and speed of sound of a-SiO(2) was measured above 6 mK
using a torsional oscillator at 90 kHz, controlling for thermal decoupling,
non-linear effects, and clamping losses. Strain amplitudes e(A) = 10^{-8} mark
the transition between the linear and non-linear regime. In the linear regime,
excellent agreement with the Tunneling Model was observed for both the internal
friction and speed of sound, with a cut-off energy of E(min) = 6.6 mK. In the
non-linear regime, two different behaviors were observed. Above 10 mK the
behavior was typical for non-linear harmonic oscillators, while below 10 mK a
different behavior was found. Its origin is not understood.Comment: 1 tex file, 6 figure
Lattice-mismatch-induced granularity in CoPt-NbN and NbN-CoPt superconductor-ferromagnet heterostructures: Effect of strain
The effect of strain due to lattice mismatch and of ferromagnetic (FM)
exchange field on superconductivity (SC) in NbN-CoPt bilayers is investigated.
Two different bilayer systems with reversed deposition sequence are grown on
MgO (001) single crystals. While robust superconductivity with high critical
temperature (T_c ~ 15.3 K) and narrow transition width DelT_c ~ 0.4 K) is seen
in two types of CoPt-NbN/MgO heterostructures where the magnetic anisotropy of
CoPt is in-plane in one case and out-of-plane in the other, the NbN-CoPt/MgO
system shows markedly suppressed SC response. The reduced SC order parameter of
this system, which manifests itself in Tc, temperature dependence of critical
current density J_c (T), and angular (Phi) variation of flux-flow resistivity
Rho_f is shown to be a signature of the structure of NbN film and not a result
of the exchange field of CoPt. The Rho_f (H,T,Phi) data further suggest that
the domain walls in the CoPt film are of the Neel type and hence do not cause
any flux in the superconducting layer. A small, but distinct increase in the
low-field critical current of the CoPt-NbN couple is seen when the magnetic
layer has perpendicular anisotropy.Comment: 9 figure
Resonant interaction between runaway electrons and the toroidal magnetic field ripple in TCV
This work explains the anomalously high runaway electron (RE) pitch angles inferred in the flat-top of dedicated Tokamak Ă Configuration Variable (TCV) experiments. Kinetic modelling shows that the resonant interaction between the gyromotion of the electrons and the toroidal magnetic field ripple will give rise to strong pitch angle scattering in TCV. The resulting increase in synchrotron radiation power losses acts as a RE energy barrier. These observations are tested experimentally by a magnetic field ramp-down, which gradually reduces the resonant parallel momentum at which the REs interact with the ripple. Resulting changes in synchrotron emission geometry and intensity are observed using three multi-spectral camera imaging systems, viewing the RE beam at distinct spatial angles in multiple wavelength ranges. Experimental reconstructions of the RE distribution in momentum- and real-space are consistent with kinetic model predictions.</p
Modeling of field singularities at dielectric edges using grid based methods
Electric field singularities at sharp metallic edges or at a dielectric
contact line can be described analytically by asymptotic expressions. The a
priori known form of the field distribution in the vicinity of these edges
can be used to construct numerical methods with improved accuracy. This
contribution focuses on a modified Finite Integration Technique and on a
Discontinuous Galerkin Method with singular approximation functions. Both
methods are able to handle field singularities at perfectly electric
conducting as well as at dielectric edges. The numerical accuracy of these
methods is investigated in a number of simulation examples including static
and dynamic field problems
Iron bioavailability in low phytate pea
Non-Peer ReviewedThe objectives of this study are to determine the effect of genotype and environment on iron
bioavailability in a set of five pea varieties differing in phytate concentration using the in vitro
digestion/Caco-2 human cell assay (Glahn 2009), to determine whether iron bioavailability in
field pea is heritable by evaluating recombinant inbred lines (RILs) differing in phytate
concentration using in vitro digestion/Caco-2 human cell assay, and to determine the effect of
the pea low phytate trait on chicken performance and iron bioavailability in chicken. In a
previous study, two low phytate pea lines (1-2347-144 and 1-150-81) were developed from
CDC Bronco at the Crop Development Centre, University of Saskatchewan (Warkentin et al.
2012). As a powerful chelator of iron, phytate can reduce the iron bioavailability in diets. The
low phytate peas may have increased iron bioavailability compared to the normal phytate
peas. In the first objective of this project, the iron bioavailability of pea seeds of the two low
phytate lines, their parent CDC Bronco and two other popular pea varieties in western Canada
(CDC Meadow and CDC Golden), derived from 3 replicate field experiments conducted in
2009 and 2010 at SPG (Saskatchewan Pulse Growers land), Outlook and Rosthern, were
assessed using the in vitro digestion/Caco-2 cell culture. The result shows that the iron
bioavailability of the two low phytate lines is significantly higher than the other three normal
phytate varieties, although their iron concentrations have not significant difference. The low
phytate line 1-2347-144 and CDC Meadow were crossed to develop RILs
Iron bioavailability in low-phytate pea
Non-Peer ReviewedPhytate is the main storage form of phosphorus in the seeds of most crops. Phytate is not well digested by monogastrics and it chelates iron, zinc and some other micronutrients. To increase the nutritional value of pea seeds, two low phytate lines (1-150-81 and 1-2347-144) were developed from CDC Bronco in previous research. In this study, an in vitro digestion/Caco-2 cell culture bioassay was used to simulate the iron absorption of peas in humans, as the cell line originated from human colon adenocarcinoma cells. The iron bioavailability of the two low-phytate lines was 1.4 to 1.9 times higher than that of three normal phytate varieties, while having the same total iron concentration. In vivo studies were used to evaluate iron absorption of chickens fed low phytate and normal phytate pea diets. The diets containing the two low-phytate pea lines had no significant effect on chicken body weight and hemoglobin level, compared with the diets containing normal phytate pea cultivars, however, iron deficiency was suspected in all diets used
A Microfluidic Device for Kinetic Optimization of Protein Crystallization and In Situ Structure Determination
The unprecedented economies of scale and unique mass transport properties of microfluidic devices made them viable nano-volume protein crystallization screening platforms. However, realizing the full potential of microfluidic crystallization requires complementary technologies for crystal optimization and harvesting. In this paper, we report a microfluidic device which provides a link between chip-based nanoliter volume crystallization screening and structure analysis through “kinetic optimization” of crystallization reactions and in situ structure determination. Kinetic optimization through systematic variation of reactor geometry and actuation of micromechanical valves is used to screen a large ensemble of kinetic trajectories that are not practical with conventional techniques. Using this device, we demonstrate control over crystal quality, reliable scale-up from nanoliter volume reactions, facile harvesting and cryoprotectant screening, and protein structure determination at atomic resolution from data collected in-chip
Local Properties of the Potential Energy Landscape of a Model Glass: Understanding the Low Temperature Anomalies
Though the existence of two-level systems (TLS) is widely accepted to explain
low temperature anomalies in the sound absorption, heat capacity, thermal
conductivity and other quantities, an exact description of their microscopic
nature is still lacking. We performed computer simulations for a binary
Lennard-Jones system, using a newly developed algorithm to locate double-well
potentials (DWP) and thus two-level systems on a systematic basis. We show that
the intrinsic limitations of computer simulations like finite time and finite
size problems do not hamper this analysis. We discuss how the DWP are embedded
in the total potential energy landscape. It turns out that most DWP are
connected to the dynamics of the smaller particles and that these DWP are
rather localized. However, DWP related to the larger particles are more
collective
- …