9,244 research outputs found
Evolutionary computation in dynamic and uncertain environments
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Editorial to special issue on evolutionary computation in dynamic and uncertain environments
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Superluminal Propagation and Acausality of Nonlinear Massive Gravity
Massive gravity is an old idea: trading geometry for mass. Much effort has
been expended on establishing a healthy model, culminating in the current
ghost-free version. We summarize here our recent findings -- that it is still
untenable -- because it is locally acausal: CTC solutions can be constructed in
a small neighborhood of any event.Comment: Contribution to Conference in Honour of the 90th Birthday of Freeman
Dyson -- To Appear in Proceeding. v2: Explicit CTC example, and other
improvements, adde
Rethinking Education Research Methodologies-Dominance of Western Perspectives?
This paper examines the different approaches and methods in comparative education research. It begins with a broad overview of the influences of Western philosophies and how Western education researchers approach social situations. Its differences with Chinese philosophies were highlighted with the concept of dao and Confucianism. More than just an epistemological discussion, this paper argues that Western researchers' biasness towards Asian researchers may be due to their failure or lack of experience in making the connections with Asian social systems. It attempts to provide some plausible explanations of the prevalence of biasness by peer reviewers of Western journals
Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator BiSe
We report a transport study of exfoliated few monolayer crystals of
topological insulator BiSe in an electric field effect (EFE) geometry.
By doping the bulk crystals with Ca, we are able to fabricate devices with
sufficiently low bulk carrier density to change the sign of the Hall density
with the gate voltage . We find that the temperature and magnetic
field dependent transport properties in the vicinity of this can be
explained by a bulk channel with activation gap of approximately 50 meV and a
relatively high mobility metallic channel that dominates at low . The
conductance (approximately 2 7), weak anti-localization, and
metallic resistance-temperature profile of the latter lead us to identify it
with the protected surface state. The relative smallness of the observed gap
implies limitations for EFE topological insulator devices at room temperature.Comment: 4 pages, 4 figures. In new version, panels have been removed from
Figures 1, 2, and 4 to improve clarity. Additional data included in Figure 4.
Introduction and discussion revised and expande
Anomalous microwave response of high-temperature superconducting thin-film microstrip resonator in weak dc magnetic fields
We have studied an anomalous microwave (mw) response of superconducting
YBa_{2}Cu_{3}O_{7-delta} (YBCO) microstrip resonators in the presence of a weak
dc magnetic field, H_{dc}. The surface resistance (R_{s}) and reactance (X_{s})
show a correlated non-monotonic behaviour as a function of H_{dc}. R_{s} and
X_{s} were found to initially decrease with elevated H_{dc} and then increase
after H_{dc} reaches a crossover field, H_{c}, which is independent of the
amplitude and frequency of the input mw signal within the measurements. The
frequency dependence of R_{s} is almost linear at fixed H_{dc} with different
magnitudes (H_{c}). The impedance plane analysis
demonstrates that r_{H}, which is defined as the ratio of the change in
R_{s}(H_{dc}) and that in X_{s}(H_{dc}), is about 0.6 at H_{dc}<H_{c} and 0.1
at H_{dc}>H_{c}. The H_{dc} dependence of the surface impedance is
qualitatively independent of the orientation of H_{dc}.Comment: REVTex 3.1, 5 pages, 6 EPS figures, submitted to Physica
The Concentration of Manganese, Copper, Zinc, Lead and Thorium in Sediments of Paka Estuary,Terengganu, Malaysia
14 cm cores sediments from the Paka River were analyzed for Mn, Cu, Zn, Pb
and Th using the inductively coupled plasma mass spectrometer (ICP-MS).
Generally, the concentrations of all elements decreased with depth and have
significantly higher concentration at the surface depth of the core. The
concentration of Mn and Cu have average value of 151.1 ± 59.1 mg/g dry
weights and 29.2 ± 6.9 mg/g dry weights, while Zn and Pb averaged at 72.5 ±
15.5 mg/g dry weights and 54.9 ± 2.5 mg/g dry weights, respectively. Th were
slightly varied widely and ranged from 0.6 mg/g dry weights to 1.4 mg/g dry
weights. In this study, only Mn and Th have enrichment factor (EF) values close
to unity and may therefore be considered to be predominantly terrigenous in
origin. On the contrary, the higher EF values found for Cu, Zn and Pb indicate
that these metals might have some influenced from the anthropogenic inpu
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