94,632 research outputs found
Stability of Weyl points in magnetic half-metallic Heusler compounds
We employ {\it ab-initio} fully-relativistic electronic structure
calculations to study the stability of the Weyl points in the momentum space
within the class of the half-metallic ferromagnetic full Heusler materials, by
focusing on CoTiAl as a well-established prototype compound. Here we show
that both the number of the Weyl points together with their -space
coordinates can be controlled by the orientation of the magnetization. This
alternative degree of freedom, which is absent in other topological materials
(e.g. in Weyl semimetals), introduces novel functionalities, specific for the
class of half-metallic ferromagnets. Of special interest are Weyl points which
are preserved irrespectively of any arbitrary rotation of the magnetization
axis
Noise of Kondo dot with ac gate: Floquet-Green's function and Noncrossing Approximation Approach
The transport properties of an ac-driving quantum dot in the Kondo regime are
studied by the Floquet-Green's function method with slave-boson infinite-
noncrossing approximation. Our results show that the Kondo peak of the local
density of states is robust against weak ac gate modulation. Significant
suppression of the Kondo peak can be observed when the ac gate field becomes
strong. The photon-assisted noise of Kondo resonance as a function of dc
voltage does not show singularities which are expected for noninteracting
resonant quantum dot. These findings suggest that one may make use of the
photon-assisted noise measurement to tell apart whether the resonant transport
is via noninteracting resonance or strongly-correlated Kondo resonance
Wireless sensor network for cattle monitoring system
This paper describes a cost effective Wireless Sensor Network (WSN) technology for monitoring the health of dairy cows. By monitoring and understanding the cow individual and herd behaviour, farmers can potentially identify the onset of illness, lameness or other undesirable health conditions. However, the WSN implementation needs to cope with various technical challenges before it can be suitably and routinely applied in cow management. This paper discusses results concerning data transportation (i.e. mobility) from the cow mounted sensory devices
Roles of the Bloom's syndrome helicase in the maintenance of genome stability
The RecQ family of DNA helicases is highly conserved in evolution from bacteria to humans. Of the five known human RecQ family members, three (BLM, WRN and RECQ4, which cause Bloom's syndrome, Werner's syndrome and Rothmund-Thomson syndrome respectively) are mutated in distinct clinical disorders associated with cancer predisposition and/or premature aging. BLM forms part of a multienzyme complex including topoisomerase IIIalpha, replication protein A and a newly identified factor called BLAP75. Together, these proteins play a role in the resolution of DNA structures that arise during the process of homologous recombination repair. In the absence of BLM, cells show genomic instability and a high incidence of sister-chromatid exchanges. In addition to a DNA structure-specific helicase activity, BLM also catalyses Holliday-junction branch migration and the annealing of complementary single-stranded DNA molecules
Solar total and spectral irradiance reconstruction over the last 9000 years
Changes in solar irradiance and in its spectral distribution are among the
main natural drivers of the climate on Earth. However, irradiance measurements
are only available for less than four decades, while assessment of solar
influence on Earth requires much longer records. The aim of this work is to
provide the most up-to-date physics-based reconstruction of the solar total and
spectral irradiance (TSI/SSI) over the last nine millennia. The concentrations
of the cosmogenic isotopes 14C and 10Be in natural archives have been converted
to decadally averaged sunspot numbers through a chain of physics-based models.
TSI and SSI are reconstructed with an updated SATIRE model. Reconstructions are
carried out for each isotope record separately, as well as for their composite.
We present the first ever SSI reconstruction over the last 9000 years from the
individual 14C and 10Be records as well as from their newest composite. The
reconstruction employs physics-based models to describe the involved processes
at each step of the procedure. Irradiance reconstructions based on two
different cosmogenic isotope records, those of 14C and 10Be, agree well with
each other in their long-term trends despite their different geochemical paths
in the atmosphere of Earth. Over the last 9000 years, the reconstructed secular
variability in TSI is of the order of 0.11%, or 1.5 W/m2. After the Maunder
minimum, the reconstruction from the cosmogenic isotopes is consistent with
that from the direct sunspot number observation. Furthermore, over the
nineteenth century, the agreement of irradiance reconstructions using isotope
records with the reconstruction from the sunspot number by Chatzistergos et al.
(2017) is better than that with the reconstruction from the WDC-SILSO series
(Clette et al. 2014), with a lower chi-square-value
Ferrimagnetism of the magnetoelectric compound CuOSeO probed by Se NMR
We present a thorough Se NMR study of a single crystal of the
magnetoelectric compound CuOSeO. The temperature dependence of the
local electronic moments extracted from the NMR data is fully consistent with a
magnetic phase transition from the high-T paramagnetic phase to a low-T
ferrimagnetic state with 3/4 of the Cu ions aligned parallel and 1/4
aligned antiparallel to the applied field of 14.09 T. The transition to this
3up-1down magnetic state is not accompanied by any splitting of the NMR lines
or any abrupt modification in their broadening, hence there is no observable
reduction of the crystalline symmetry from its high-T cubic \textit{P}23
space group. These results are in agreement with high resolution x-ray
diffraction and magnetization data on powder samples reported previously by Bos
{\it et al.} [Phys. Rev. B, {\bf 78}, 094416 (2008)]. We also develop a mean
field theory description of the problem based on a microscopic spin Hamiltonian
with one antiferromagnetic ( K) and one ferromagnetic
( K) nearest-neighbor exchange interaction
Combinatorial interpretation of Haldane-Wu fractional exclusion statistics
Assuming that the maximal allowed number of identical particles in state is
an integer parameter, q, we derive the statistical weight and analyze the
associated equation which defines the statistical distribution. The derived
distribution covers Fermi-Dirac and Bose-Einstein ones in the particular cases
q = 1 and q -> infinity (n_i/q -> 1), respectively. We show that the derived
statistical weight provides a natural combinatorial interpretation of
Haldane-Wu fractional exclusion statistics, and present exact solutions of the
distribution equation.Comment: 8 pages, 2 eps-figure
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