3,232 research outputs found
Effect of dietary omega-3 fatty acids on castrate-resistant prostate cancer and tumor-associated macrophages.
BackgroundM2-like macrophages are associated with the pathogenesis of castrate-resistant prostate cancer (CRPC). We sought to determine if dietary omega-3 fatty acids (ω-3 FAs) delay the development and progression of CRPC and inhibit tumor-associated M2-like macrophages.MethodsMycCap cells were grown subcutaneously in immunocompetent FVB mice. Mice were castrated when tumors reached 300 mm2. To study effects of dietary ω-3 FAs on development of CRPC, ω-3 or ω-6 diets were started 2 days after castration and mice sacrificed after early regrowth of tumors. To study ω-3 FA effects on progression of CRPC, tumors were allowed to regrow after castration before starting the diets. M2 (CD206+) macrophages were isolated from allografts to examine ω-3 FA effects on macrophage function. Omega-3 fatty acid effects on androgen-deprived RAW264.7 M2 macrophages were studied by RT-qPCR and a migration/ invasion assay.ResultsThe ω-3 diet combined with castration lead to greater MycCap tumor regression (tumor volume reduction: 182.2 ± 33.6 mm3) than the ω-6 diet (tumor volume reduction: 148.3 ± 35.2; p = 0.003) and significantly delayed the time to CRPC (p = 0.006). Likewise, the ω-3 diet significantly delayed progression of established castrate-resistant MycCaP tumors (p = 0.003). The ω-3 diet (as compared to the ω-6 diet) significantly reduced tumor-associated M2-like macrophage expression of CSF-1R in the CRPC development model, and matrix metallopeptidase-9 (MMP-9) and vascular endothelial growth factor (VEGF) in the CRPC progression model. Migration of androgen-depleted RAW264.7 M2 macrophages towards MycCaP cells was reversed by addition of docosahexaenoic acid (ω-3).ConclusionsDietary omega-3 FAs (as compared to omega-6 FAs) decreased the development and progression of CRPC in an immunocompetent mouse model, and had inhibitory effects on M2-like macrophage function. Clinical trials are warranted evaluating if a fish oil-based diet can delay the time to castration resistance in men on androgen deprivation therapy, whereas further preclinical studies are warranted evaluating fish oil for more advanced CRPC
Strong tuning of Rashba spin orbit interaction in single InAs nanowires
A key concept in the emerging field of spintronics is the gate voltage or
electric field control of spin precession via the effective magnetic field
generated by the Rashba spin orbit interaction. Here, we demonstrate the
generation and tuning of electric field induced Rashba spin orbit interaction
in InAs nanowires where a strong electric field is created either by a double
gate or a solid electrolyte surrounding gate. In particular, the electrolyte
gating enables six-fold tuning of Rashba coefficient and nearly three orders of
magnitude tuning of spin relaxation time within only 1 V of gate bias. Such a
dramatic tuning of spin orbit interaction in nanowires may have implications in
nanowire based spintronic devices.Comment: Nano Letters, in pres
Development of an IS change reason - IS change type combination matrix
Firms change their information systems (IS) for various reasons, ranging from compliance with government regulations to the development of new capabilities. When making these changes a firm can choose between four different IS change types: IS introduction, IS extension, IS replacement, and IS merger. This paper proposes that change reasons and change types are interrelated, and that certain reason-type combinations are more likely than others to result in a successful IS change. To identify these combinations, an IS change reason–IS change type matrix is developed. While the matrix is created from prior IS research, we conducted a focus group study of IS professionals to further explore and refine the matrix. The findings from the focus group study reveal that some IS change reason–IS change type combinations are more appropriate than others to carry out the IS change project successfully. We also present three examples of IS change projects to illustrate the use and value of the matrix in practice
Electric Field Control of Spin Transport
Spintronics is an approach to electronics in which the spin of the electrons
is exploited to control the electric resistance R of devices. One basic
building block is the spin-valve, which is formed if two ferromagnetic
electrodes are separated by a thin tunneling barrier. In such devices, R
depends on the orientation of the magnetisation of the electrodes. It is
usually larger in the antiparallel than in the parallel configuration. The
relative difference of R, the so-called magneto-resistance (MR), is then
positive. Common devices, such as the giant magneto-resistance sensor used in
reading heads of hard disks, are based on this phenomenon. The MR may become
anomalous (negative), if the transmission probability of electrons through the
device is spin or energy dependent. This offers a route to the realisation of
gate-tunable MR devices, because transmission probabilities can readily be
tuned in many devices with an electrical gate signal. Such devices have,
however, been elusive so far. We report here on a pronounced gate-field
controlled MR in devices made from carbon nanotubes with ferromagnetic
contacts. Both the amplitude and the sign of the MR are tunable with the gate
voltage in a predictable manner. We emphasise that this spin-field effect is
not restricted to carbon nanotubes but constitutes a generic effect which can
in principle be exploited in all resonant tunneling devices.Comment: 22 pages, 5 figure
Transport properties of strongly correlated metals:a dynamical mean-field approach
The temperature dependence of the transport properties of the metallic phase
of a frustrated Hubbard model on the hypercubic lattice at half-filling are
calculated. Dynamical mean-field theory, which maps the Hubbard model onto a
single impurity Anderson model that is solved self-consistently, and becomes
exact in the limit of large dimensionality, is used. As the temperature
increases there is a smooth crossover from coherent Fermi liquid excitations at
low temperatures to incoherent excitations at high temperatures. This crossover
leads to a non-monotonic temperature dependence for the resistance,
thermopower, and Hall coefficient, unlike in conventional metals. The
resistance smoothly increases from a quadratic temperature dependence at low
temperatures to large values which can exceed the Mott-Ioffe-Regel value, hbar
a/e^2 (where "a" is a lattice constant) associated with mean-free paths less
than a lattice constant. Further signatures of the thermal destruction of
quasiparticle excitations are a peak in the thermopower and the absence of a
Drude peak in the optical conductivity. The results presented here are relevant
to a wide range of strongly correlated metals, including transition metal
oxides, strontium ruthenates, and organic metals.Comment: 19 pages, 9 eps figure
Unoccupied Band Structure of NbSe2 by Very-Low-Energy Electron Diffraction: Experiment and Theory
A combined experimental and theoretical study of very-low-energy electron
diffraction at the (0001) surface of 2H-NbSe2 is presented. Electron
transmission spectra have been measured for energies up to 50 eV above the
Fermi level with k|| varying along the GammaK line of the Brillouin zone. Ab
initio calculations of the spectra have been performed with the extended linear
augmented plane wave k-p method. The experimental spectra are interpreted in
terms of three-dimensional one-electron band structure. Special attention is
paid to the quasi-particle lifetimes: by comparing the broadening of the
spectral structures in the experimental and calculated spectra the energy
dependence of the optical potential Vi is determined. A sharp increase of Vi at
20 eV is detected, which is associated with a plasmon peak in the
Im(-1/epsilon) function. Furthermore, the electron energy loss spectrum and the
reflectivity of NbSe2 are calculated ab initio and compared with optical
experiments. The obtained information on the dispersions and lifetimes of the
unoccupied states is important for photoemission studies of the 3D band
structure of the valence band.Comment: 17 pages, 11 Postscript figures, submitted to Phys. Rev.
Strain-induced partially flat band, helical snake states, and interface superconductivity in topological crystalline insulators
Topological crystalline insulators in IV-VI compounds host novel topological
surface states consisting of multi-valley massless Dirac fermions at low
energy. Here we show that strain generically acts as an effective gauge field
on these Dirac fermions and creates pseudo-Landau orbitals without breaking
time-reversal symmetry. We predict the realization of this phenomenon in IV-VI
semiconductor heterostructures, due to a naturally occurring misfit dislocation
array at the interface that produces a periodically varying strain field.
Remarkably, the zero-energy Landau orbitals form a flat band in the vicinity of
the Dirac point, and coexist with a network of snake states at higher energy.
We propose that the high density of states of this flat band gives rise to
interface superconductivity observed in IV-VI semiconductor multilayers at
unusually high temperatures, with non-BCS behavior. Our work demonstrates a new
route to altering macroscopic electronic properties to achieve a partially flat
band, and paves the way for realizing novel correlated states of matter.Comment: Accepted by Nature Physic
Serum amyloid A primes microglia for ATP-dependent interleukin-1\u3b2 release
Acute-phase response is a systemic reaction to environmental/inflammatory insults and involves production of acute-phase proteins, including serum amyloid A (SAA). Interleukin-1\u3b2 (IL-1\u3b2), a master regulator of neuroinflammation produced by activated inflammatory cells of the myeloid lineage, in particular microglia, plays a key role in the pathogenesis of acute and chronic diseases of the peripheral nervous system and CNS. IL-1\u3b2 release is promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with toll-like receptor (TLR) ligands
Meta-analysis of binary outcomes via generalized linear mixed models: a simulation study
Background: Systematic reviews and meta-analyses of binary outcomes are widespread in all areas of application. The odds ratio, in particular, is by far the most popular effect measure. However, the standard meta-analysis of odds ratios using a random-effects model has a number of potential problems. An attractive alternative approach for the meta-analysis of binary outcomes uses a class of generalized linear mixed models (GLMMs). GLMMs are believed to overcome the problems of the standard random-effects model because they use a correct binomial-normal likelihood. However, this belief is based on theoretical considerations, and no sufficient simulations have assessed the performance of GLMMs in meta-analysis. This gap may be due to the computational complexity of these models and the resulting considerable time requirements. Methods: The present study is the first to provide extensive simulations on the performance of four GLMM methods (models with fixed and random study effects and two conditional methods) for meta-analysis of odds ratios in comparison to the standard random effects model. Results: In our simulations, the hypergeometric-normal model provided less biased estimation of the heterogeneity variance than the standard random-effects meta-analysis using the restricted maximum likelihood (REML) estimation when the data were sparse, but the REML method performed similarly for the point estimation of the odds ratio, and better for the interval estimation. Conclusions: It is difficult to recommend the use of GLMMs in the practice of meta-analysis. The problem of finding uniformly good methods of the meta-analysis for binary outcomes is still open
Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
Recent trends of ab initio studies and progress in methodologies for
electronic structure calculations of strongly correlated electron systems are
discussed. The interest for developing efficient methods is motivated by recent
discoveries and characterizations of strongly correlated electron materials and
by requirements for understanding mechanisms of intriguing phenomena beyond a
single-particle picture. A three-stage scheme is developed as renormalized
multi-scale solvers (RMS) utilizing the hierarchical electronic structure in
the energy space. It provides us with an ab initio downfolding of the global
band structure into low-energy effective models followed by low-energy solvers
for the models. The RMS method is illustrated with examples of several
materials. In particular, we overview cases such as dynamics of semiconductors,
transition metals and its compounds including iron-based superconductors and
perovskite oxides, as well as organic conductors of kappa-ET type.Comment: 44 pages including 38 figures, to appear in J. Phys. Soc. Jpn. as an
invited review pape
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