1,228 research outputs found
Temperature effects on the magnetization of quasi-one-dimensional Peierls distorted materials
It is shown that temperature acts to disrupt the magnetization of Peierls
distorted quasi-one-dimensional materials (Q1DM). The mean-field finite
temperature phase diagram for the field theory model employed is obtained by
considering both homogeneous and inhomogeneous condensates. The tricritical
points of the second order transition lines of the gap parameter and
magnetization are explicitly calculated. It is also shown that in the absence
of an external static magnetic field the magnetization is always zero, at any
temperature. As expected, temperature does not induce any magnetization effect
on Peierls distorted Q1DM.Comment: 11 pages, 2 figure
Recommended from our members
Enigmatic persistence of dissolved organic matter in the ocean
Marine dissolved organic matter (DOM) contains more carbon than the combined stocks of Earth’s biota. Organisms in the ocean continuously release a myriad of molecules that become food for microheterotrophs, but, for unknown reasons, a residual fraction persists as DOM for millennia. In this Perspective, we discuss and compare two concepts that could explain this persistence. The long-standing ‘intrinsic recalcitrance’ paradigm attributes DOM stability to inherent molecular properties. In the ‘emergent recalcitrance’ concept, DOM is continuously transformed by marine microheterotrophs, with recalcitrance emerging on an ecosystems level. Both concepts are consistent with observations in the modern ocean, but they imply very different responses of the DOM pool to climate-related changes. To better understand DOM persistence, we propose a new overarching research strategy — the ecology of molecules — that integrates the concepts of intrinsic and emergent recalcitrance with the ecological and environmental context
Recommended from our members
Promotion of Mn(II) Oxidation and Remediation of Coal Mine Drainage in Passive Treatment Systems by Diverse Fungal and Bacterial Communities
Biologically active, passive treatment systems are commonly employed for removing high concentrations of dissolved Mn(II) from coal mine drainage (CMD). Studies of microbial communities contributing to Mn attenuation through the oxidation of Mn(II) to sparingly soluble Mn(III/IV) oxide minerals, however, have been sparse to date. This study reveals a diverse community of Mn(II)-oxidizing fungi and bacteria existing in several CMD treatment systems.Organismic and Evolutionary Biolog
Scaling and singularities in the entrainment of globally-coupled oscillators
The onset of collective behavior in a population of globally coupled
oscillators with randomly distributed frequencies is studied for phase
dynamical models with arbitrary coupling. The population is described by a
Fokker-Planck equation for the distribution of phases which includes the
diffusive effect of noise in the oscillator frequencies. The bifurcation from
the phase-incoherent state is analyzed using amplitude equations for the
unstable modes with particular attention to the dependence of the nonlinearly
saturated mode on the linear growth rate . In general
we find where is the
diffusion coefficient and is the mode number of the unstable mode. The
unusual factor arises from a singularity in the cubic term of
the amplitude equation.Comment: 11 pages (Revtex); paper submitted to Phys. Rev. Let
Stability window and mass-radius relation for magnetized strange quark stars
The stability of magnetized strange quark matter (MSQM) is investigated
within the phenomenological MIT bag model, taking into account the variation of
the relevant input parameters, namely, the strange quark mass, baryon density,
magnetic field and bag parameter. We obtain that the energy per baryon
decreases as the magnetic field increases, and its minimum value at vanishing
pressure is lower than the value found for SQM. This implies that MSQM is more
stable than non-magnetized SQM. Furthermore, the stability window of MSQM is
found to be wider than the corresponding one of SQM. The mass-radius relation
for magnetized strange quark stars is also derived in this framework.Comment: 12 pages, 6 figures, 3 table
Dynamically-Coupled Oscillators -- Cooperative Behavior via Dynamical Interaction --
We propose a theoretical framework to study the cooperative behavior of
dynamically coupled oscillators (DCOs) that possess dynamical interactions.
Then, to understand synchronization phenomena in networks of interneurons which
possess inhibitory interactions, we propose a DCO model with dynamics of
interactions that tend to cause 180-degree phase lags. Employing an approach
developed here, we demonstrate that although our model displays synchronization
at high frequencies, it does not exhibit synchronization at low frequencies
because this dynamical interaction does not cause a phase lag sufficiently
large to cancel the effect of the inhibition. We interpret the disappearance of
synchronization in our model with decreasing frequency as describing the
breakdown of synchronization in the interneuron network of the CA1 area below
the critical frequency of 20 Hz.Comment: 10 pages, 3 figure
Complete synchronization in coupled Type-I neurons
For a system of type-I neurons bidirectionally coupled through a nonlinear
feedback mechanism, we discuss the issue of noise-induced complete
synchronization (CS). For the inputs to the neurons, we point out that the rate
of change of instantaneous frequency with the instantaneous phase of the
stochastic inputs to each neuron matches exactly with that for the other in the
event of CS of their outputs. Our observation can be exploited in practical
situations to produce completely synchronized outputs in artificial devices.
For excitatory-excitatory synaptic coupling, a functional dependence for the
synchronization error on coupling and noise strengths is obtained. Finally we
report an observation of noise-induced CS between non-identical neurons coupled
bidirectionally through random non-zero couplings in an all-to- all way in a
large neuronal ensemble.Comment: 24 pages, 9 figure
Acceleration effect of coupled oscillator systems
We have developed a curved isochron clock (CIC) by modifying the radial
isochron clock to provide a clean example of the acceleration (deceleration)
effect. By analyzing a two-body system of coupled CICs, we determined that an
unbalanced mutual interaction caused by curved isochron sets is the minimum
mechanism needed for generating the acceleration (deceleration) effect in
coupled oscillator systems. From this we can see that the Sakaguchi and
Kuramoto (SK) model which is a class of non-frustrated mean feild model has an
acceleration (deceleration) effect mechanism. To study frustrated coupled
oscillator systems, we extended the SK model to two oscillator associative
memory models, one with symmetric and one with asymmetric dilution of coupling,
which also have the minimum mechanism of the acceleration (deceleration)
effect. We theoretically found that the {\it Onsager reaction term} (ORT),
which is unique to frustrated systems, plays an important role in the
acceleration (de! celeration) effect. These two models are ideal for evaluating
the effect of the ORT because, with the exception of the ORT, they have the
same order parameter equations. We found that the two models have identical
macroscopic properties, except for the acceleration effect caused by the ORT.
By comparing the results of the two models, we can extract the effect of the
ORT from only the rotation speeds of the oscillators.Comment: 35 pages, 10 figure
Alignment Dynamics of Single-Walled Carbon Nanotubes in Pulsed Ultrahigh Magnetic Fields
We have measured the dynamic alignment properties of single-walled carbon
nanotube (SWNT) suspensions in pulsed high magnetic fields through linear
dichroism spectroscopy. Millisecond-duration pulsed high magnetic fields up to
56 T as well as microsecond-duration pulsed ultrahigh magnetic fields up to 166
T were used. Due to their anisotropic magnetic properties, SWNTs align in an
applied magnetic field, and because of their anisotropic optical properties,
aligned SWNTs show linear dichroism. The characteristics of their overall
alignment depend on several factors, including the viscosity and temperature of
the suspending solvent, the degree of anisotropy of nanotube magnetic
susceptibilities, the nanotube length distribution, the degree of nanotube
bundling, and the strength and duration of the applied magnetic field. In order
to explain our data, we have developed a theoretical model based on the
Smoluchowski equation for rigid rods that accurately reproduces the salient
features of the experimental data.Comment: 20 pages, 6 figure
- …