537 research outputs found
Genetic uniqueness and socio-cultural conservation values of the endangered Yakutian Cattle
At the local level the values of the cattle were more related to everyday livelihood strategies of single households and families, whereas the representatives of the republic, in line with the newspapers, highlighted the importance of the cattle for Sakha's food production and for national identity. Thus, individuals at different levels were in favour of conserving the cattle, but for different reasons. The local residents and experts were more concerned about developing economically sustainable cattle production, whereas the experts in Yakutsk were concerned about the conservation of genetic resources. The genetic studies have indicated that Yakutian Cattle show genetic distinctiveness and have genetic value for the maintenance of cattle diversity
Memory Effect, Rejuvenation and Chaos Effect in the Multi-layer Random Energy Model
We introduce magnetization to the Multi-layer Random Energy Model which has a
hierarchical structure, and perform Monte Carlo simulation to observe the
behavior of ac-susceptibility. We find that this model is able to reproduce
three prominent features of spin glasses, i.e., memory effect, rejuvenation and
chaos effect, which were found recently by various experiments on aging
phenomena with temperature variations.Comment: 10 pages, 14 figures, to be submitted to J. Phys. Soc. Jp
Numerical Study of Aging in the Generalized Random Energy Model
Magnetizations are introduced to the Generalized Random Energy Model (GREM)
and numerical simulations on ac susceptibility is made for direct comparison
with experiments in glassy materials. Prominent dynamical natures of spin
glasses, {\it i.e.}, {\em memory} effect and {\em reinitialization}, are
reproduced well in the GREM. The existence of many layers causing continuous
transitions is very important for the two natures. Results of experiments in
other glassy materials such as polymers, supercooled glycerol and orientational
glasses, which are contrast to those in spin glasses, are interpreted well by
the Single-layer Random Energy Model.Comment: 8 pages, 9 figures, to be submitted to J. Phys. Soc. Jp
Scaling Law and Aging Phenomena in the Random Energy Model
We study the effect of temperature shift on aging phenomena in the Random
Energy Model (REM). From calculation on the correlation function and simulation
on the Zero-Field-Cooled magnetization, we find that the REM satisfies a
scaling relation even if temperature is shifted. Furthermore, this scaling
property naturally leads to results obtained in experiment and the droplet
theory.Comment: 8 pages, 7 figures, to be submitted to J. Phys. Soc. Jp
Off-Equilibrium Dynamics in Finite-Dimensional Spin Glass Models
The low temperature dynamics of the two- and three-dimensional Ising spin
glass model with Gaussian couplings is investigated via extensive Monte Carlo
simulations. We find an algebraic decay of the remanent magnetization. For the
autocorrelation function a typical
aging scenario with a scaling is established. Investigating spatial
correlations we find an algebraic growth law of
the average domain size. The spatial correlation function scales with . The sensitivity of the
correlations in the spin glass phase with respect to temperature changes is
examined by calculating a time dependent overlap length. In the two dimensional
model we examine domain growth with a new method: First we determine the exact
ground states of the various samples (of system sizes up to )
and then we calculate the correlations between this state and the states
generated during a Monte Carlo simulation.Comment: 38 pages, RevTeX, 14 postscript figure
Relaxation of the field-cooled magnetization of an Ising spin glass
The time and temperature dependence of the field-cooled magnetization of a
three dimensional Ising spin glass, Fe_{0.5}Mn_{0.5}TiO_{3}, has been
investigated. The temperature and cooling rate dependence is found to exhibit
memory phenomena that can be related to the memory behavior of the low
frequency ac-susceptibility. The results add some further understanding on how
to model the three dimensional Ising spin glass in real space.Comment: 8 pages RevTEX, 5 figure
Short range ferromagnetism and spin glass state in
Dynamic magnetic properties of are
reported. The system appears to attain local ferromagnetic order at
K. Below this temperature the low field
magnetization becomes history dependent, i.e. the zero field cooled (ZFC) and
field cooled (FC) magnetization deviate from each other and closely logarithmic
relaxation appears at our experimental time scales (0.3- sec). The zero
field cooled magnetization has a maximum at K,
whereas the field cooled magnetization continues to increase, although less
sharply, also below this temperature. Surprisingly, the dynamics of the system
shows non-equilibrium spin glass (SG) features not only below the maximum in
the ZFC magnetization, but also in the temperature region between this maximum
and . The aging and temperature cycling experiments show only
quantitative differences in the dynamic behavior above and below the maximum in
the ZFC-magnetization; similarly, memory effects are observed in both
temperature regions. We attribute the high temperature behavior to the
existence of clusters of short range ferromagnetic order below
; the configuration evolves into a conventional spin glass
state at temperatures below .Comment: REVTeX style; 8 pages, 8 figure
Ambient-Dried, 3D-Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers
This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non-covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large-scale production of porous, light-weight materials as it does not require freeze-drying, supercritical CO2 drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent-exchange, and ambient drying of composite CNF-alginate gels. The presented findings suggest that a highly-porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23–38 kg m−3) and compressive moduli (97–275 kPa) can be prepared by using different CNF concentrations. These low-density networks have a unique combination of formability (using molding or 3D-printing) and wet-stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In-depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g−1), but also as mechanical-strain and humidity sensors
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