216,722 research outputs found
On the foundations of cancer modelling: selected topics, speculations, & perspectives
This paper presents a critical review of selected topics related to the modelling of cancer onset, evolution and growth, with the aim of illustrating, to a wide applied mathematical readership, some of the novel mathematical problems in the field. This review attempts to capture, from the appropriate literature, the main issues involved in the modelling of phenomena related to cancer dynamics at all scales which characterise this highly complex system: from the molecular scale up to that of tissue. The last part of the paper discusses the challenge of developing a mathematical biological theory of tumour onset and evolution
Geometry and the anomalous Hall effet in ferromagnets
The geometric ideas underlying the Berry phase and the modern viewpoint of
Karplus and Luttinger's theory of the anomalous Hall effect are discussed in an
elementary way. We briefly review recent Hall and Nernst experiments which
support the dominant role of the KL velocity term in ferromagnets.Comment: 6 pages, 4 figures, conference proceedings, tutorial revie
Ratcheting Heat Flux against a Thermal Bias
Merely rocking the temperature in one heat bath can direct a steady heat flux
from cold to hot against a non-zero thermal bias in stylized nonlinear lattice
junctions that are sandwiched between two heat baths. Likewise, for an average
zero-temperature difference between the two contacts a net, ratchet-like heat
flux emerges. Computer simulations show that this very heat flux can be
controlled and reversed by suitably tailoring the frequency ( 100
MHz) of the alternating temperature field.Comment: 5 pages, 6 figure
and dibaryons in SU(3) chiral quark model
The binding energy of the six quark system with strangeness s=-3 is
investigated under the chiral SU(3) constituent quark model in the framework of
. The calculations of the single channel with spin S=2 and the
single channel with spin S=3 are performed. The results show
that both systems could be dibaryons and the interaction induced by the chiral
field plays a very important role on forming bound states in the systems
considered.
The phase shifts and scattering lengths in corresponding channels are also
given.Comment: LaTex file with 5 figure
Phase fluctuations versus Gaussian fluctuations in optimally-doped YBaCuO
We analyze recent torque measurements of the magnetization vs. magnetic
field in optimally doped YBaCuO (OPT YBCO) to argue against
a recent proposal by Rey et al that the magnetization results above are
consistent with Gaussian fluctuations. We find that, despite its strong
interlayer coupling, OPT YBCO displays an anomalous non-monotonic dependence of
on which represents direct evidence for the locking of the pair
wavefunction phase at and the subsequent unlocking by a
relatively weak . These unusual features characterize the unusual nature of
the transition to the Meissner state in cuprate superconductors. They are
absent in low- superconductors to our knowledge. We also stress the
importance of the vortex liquid state, as well as the profiles of the melting
field and the upper critical field curve in the -
plane. Contrary to the claims of Rey et al, we show that the curves of the
magnetization and the Nernst signal illustrate the inaccessibility of the
line near . The prediction of the line by Rey et al is
shown to be invalid in OPT YBCO.Comment: 6 pages, 6 figure
The zero-energy state in graphene in a high magnetic field
The fate of the charge-neutral Dirac point in graphene in a high magnetic
field has been investigated at low temperatures ( 0.3 K). In samples
with small (the gate voltage needed to access the Dirac point), the
resistance at the Dirac point diverges steeply with , signalling a
crossover to an insulating state in intense field. The approach to the
insulating state is highly unusual. Despite the steep divergence in , the
profile of vs. in fixed saturates to a -independent value
below 2 K, consistent with charge carrying gapless excitations.Comment: 4 pages, 4 figures. Four new sub-figures have been added. Text
expanded to discuss data from more sample
Consequences of Cadmium exposure on growth and reproduction across three generations of earthworm
Heavy metal pollution disturbs the soil ecosystem by negatively affecting soil fauna and flora. In term of biomass and activity Annelids are a very important part of the soil invertebrate community. They are one of the first organisms affected by heavy metal contamination in soil and as such are good model organisms for assessing soil contamination. The aim of this research is to observe how Cd impacts on health and reproduction in three consecutive generations of E. fetida. [...]falseOnlin
Symmetry breaking and manipulation of nonlinear optical modes in an asymmetric double-channel waveguide
We study light-beam propagation in a nonlinear coupler with an asymmetric
double-channel waveguide and derive various analytical forms of optical modes.
The results show that the symmetry-preserving modes in a symmetric
double-channel waveguide are deformed due to the asymmetry of the two-channel
waveguide, yet such a coupler supports the symmetry-breaking modes. The
dispersion relations reveal that the system with self-focusing nonlinear
response supports the degenerate modes, while for self-defocusingmedium the
degenerate modes do not exist. Furthermore, nonlinear manipulation is
investigated by launching optical modes supported in double-channel waveguide
into a nonlinear uniform medium.Comment: 10 page
Study of 0- phase transition in hybrid superconductor-InSb nanowire quantum dot devices
Hybrid superconductor-semiconducting nanowire devices provide an ideal
platform to investigating novel intragap bound states, such as the Andreev
bound states (ABSs), Yu-Shiba-Rusinov (YSR) states, and the Majorana bound
states. The competition between Kondo correlations and superconductivity in
Josephson quantum dot (QD) devices results in two different ground states and
the occurrence of a 0- quantum phase transition. Here we report on
transport measurements on hybrid superconductor-InSb nanowire QD devices with
different device geometries. We demonstrate a realization of continuous
gate-tunable ABSs with both 0-type levels and -type levels. This allow us
to manipulate the transition between 0 and junction and explore charge
transport and spectrum in the vicinity of the quantum phase transition regime.
Furthermore, we find a coexistence of 0-type ABS and -type ABS in the same
charge state. By measuring temperature and magnetic field evolution of the
ABSs, the different natures of the two sets of ABSs are verified, being
consistent with the scenario of phase transition between the singlet and
doublet ground state. Our study provides insights into Andreev transport
properties of hybrid superconductor-QD devices and sheds light on the crossover
behavior of the subgap spectrum in the vicinity of 0- transition
Unusual Nernst effect suggestive of time-reversal violation in the striped cuprate LaBaCuO
The striped cuprate LaBaCuO ( undergoes several
transitions below the charge-ordering temperature = 54 K. From Nernst
experiments, we find that, below , there exists a large, anomalous
Nernst signal that is symmetric in field , and remains
finite as . The time-reversal violating signal suggests that, below
, vortices of one sign are spontaneously created to relieve interlayer
phase frustration.Comment: 5 pages, 4 figure
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