2,902 research outputs found
Analysis of magnetization and a spin state crossover in the multiferroic CaCoMnO
Ca_3Co_{2-x}Mn_xO_6 (x ~ 0.96) is a multiferroic with spin-chains of
alternating Co(2+) and Mn(4+) ions. The spin state of Co(2+) remains
unresolved, due to a discrepancy between high temperature X-ray absorption
(S=3/2) and low temperature neutron (S=1/2) measurements. Using a combination
of magnetic modeling and crystal-field analysis, we show that the existing low
temperature data cannot be reconciled within a high spin scenario by invoking
spin-orbit or Jahn-Teller distortions. To unify the experimental results, we
propose a spin-state crossover with specific experimental predictions.Comment: 4 pages, 3 figure
Quantum mechanics and geodesic deviation in the brane world
We investigate the induced geodesic deviation equations in the brane world
models, in which all the matter forces except gravity are confined on the
3-brane. Also, the Newtonian limit of induced geodesic deviation equation is
studied. We show that in the first Randall-Sundrum model the Bohr-Sommerfeld
quantization rule is as a result of consistency between the geodesic and
geodesic deviation equations. This indicates that the path of test particle is
made up of integral multiples of a fundamental Compton-type unit of length
.Comment: 5 pages, no figure
Muon Simulations for Super-Kamiokande, KamLAND and CHOOZ
Muon backgrounds at Super-Kamiokande, KamLAND and CHOOZ are calculated using
MUSIC. A modified version of the Gaisser sea level muon distribution and a
well-tested Monte Carlo integration method are introduced. Average muon energy,
flux and rate are tabulated. Plots of average energy and angular distributions
are given. Implications on muon tracker design for future experiments are
discussed.Comment: Revtex4 33 pages, 16 figures and 4 table
Electromyogram (EMG) Removal by Adding Sources of EMG (ERASE) -- A novel ICA-based algorithm for removing myoelectric artifacts from EEG -- Part 2
Extraction of the movement-related high-gamma (80 - 160 Hz) in
electroencephalogram (EEG) from traumatic brain injury (TBI) patients who have
had hemicraniectomies, remains challenging due to a confounding bandwidth
overlap with surface electromyogram (EMG) artifacts related to facial and head
movements. In part 1, we described an augmented independent component analysis
(ICA) approach for removal of EMG artifacts from EEG, and referred to as EMG
Reduction by Adding Sources of EMG (ERASE). Here, we tested ERASE on EEG
recorded from six TBI patients with hemicraniectomies while they performed a
thumb flexion task. ERASE removed a mean of 52 +/- 12% (mean +/- S.E.M)
(maximum 73%) of EMG artifacts. In contrast, conventional ICA removed a mean of
27 +/- 19\% (mean +/- S.E.M) of EMG artifacts from EEG. In particular,
high-gamma synchronization was significantly improved in the contralateral hand
motor cortex area within the hemicraniectomy site after ERASE was applied. We
computed fractal dimension (FD) of EEG high-gamma on each channel. We found
relative FD of high-gamma over hemicraniectomy after applying ERASE were
strongly correlated to the amplitude of finger flexion force. Results showed
that significant correlation coefficients across the electrodes related to
thumb flexion averaged 0.76, while the coefficients across the homologous
electrodes in non-hemicraniectomy areas were nearly 0. Across all subjects, an
average of 83% of electrodes significantly correlated with force was located in
the hemicraniectomy areas after applying ERASE. After conventional ICA, only
19% of electrodes with significant correlations were located in the
hemicraniectomy. These results indicated that the new approach isolated
electrophysiological features during finger motor activation while selectively
removing confounding EMG artifacts
Detection of somatic changes in human cancer DNA by DNA fingerprint analysis.
Minisatellite DNA probes which can detect a large number of autosomal loci dispersed throughout the human genome were used to examine the constitutional and tumour DNA of 35 patients with a variety of cancers of which eight were of gastrointestinal origin. Somatic changes were seen in the tumour DNA in ten of the 35 cases. The changes included alterations in the relative intensities of hybridising DNA fragments, and, in three cases of cancers of gastrointestinal origin, the appearance of novel minisatellite fragments not seen in the corresponding constitutional DNA. The results of this preliminary study suggests that DNA fingerprint analysis provides a useful technique for identifying somatic changes in cancers
Body of evidence: forensic use of baseline health assessments to convict wildlife poachers
CONTEXT. Given the immense impact of wildlife trade, disease and repatriations on populations, health assessments can"
"provide powerful forensic material to help convict wildlife poachers and minimise risks of releasing unhealthy wildlife."
AIMS. We aimed to use reference ranges to assess the health of confiscated tortoises, to illustrate forensic application of these ranges, and to advance analyses for future applications."
METHODS. We used analyses of variance (ANOVA) and covariance (ANCOVA), and composite indices, to compare wild and confiscate tortoise body condition, haematocrit and haemoglobin concentration of males and females of three tortoise species. Subsequently, we used multivariate statistics (e.g. discriminant analyses) to evaluate the relative importance of species, sex and group (wild or confiscate) on tortoise condition and haematology."
KEY RESULTS. Our initial statistical tests demonstrated, at P < 0.05 to P < 0.0005, that confiscate body condition and haematology were compromised compared with that of wild tortoises. Subsequently, discriminant analyses strongly discriminated between most wild and confiscate groups (P < 0.0001), correctly classified individual health as wild or confiscate 80–90% of the time, indicated that species and sex effects were stronger than was the wild-confiscate category, and provided discriminant functions for use on other taxa and studies."
CONCLUSIONS. The health assessments discriminated well between wild and confiscate tortoises. The results had considerable forensic value, being relevant, quickly generated using portable field equipment, reliable, accurate, easy to explain and convey in terms of likelihood in a court of law, synergistically consistent among variables and groups, a strong rebuttal to the poachers’ specific statements, and consistent with other types of evidence. Multivariate analyses were consistent with, and more prudent and powerful than, the original statistical analyses. Discriminant functions can be applied in future studies and on other chelonian species, and should be developed for other wildlife species."
IMPLICATIONS. Reference ranges provide considerable value for forensics, diagnostics and treatment. Given the disease risks resulting from the massive scale of wildlife trade and release, reference ranges should be developed for more species."Web of Scienc
Frustration and the Kondo effect in heavy fermion materials
The observation of a separation between the antiferromagnetic phase boundary
and the small-large Fermi surface transition in recent experiments has led to
the proposal that frustration is an important additional tuning parameter in
the Kondo lattice model of heavy fermion materials. The introduction of a Kondo
(K) and a frustration (Q) axis into the phase diagram permits us to discuss the
physics of heavy fermion materials in a broader perspective. The current
experimental situation is analysed in the context of this combined "QK" phase
diagram. We discuss various theoretical models for the frustrated Kondo
lattice, using general arguments to characterize the nature of the -electron
localization transition that occurs between the spin liquid and heavy Fermi
liquid ground-states. We concentrate in particular on the Shastry--Sutherland
Kondo lattice model, for which we establish the qualitative phase diagram using
strong coupling arguments and the large- expansion. The paper closes with
some brief remarks on promising future theoretical directions.Comment: To appear in a special issue of JLT
Relative palatability and efficacy of brodifacoum-25D conservation rodenticide pellets for mouse eradication on Midway Atoll
Invasive mice (Mus spp.) can negatively impact island species and ecosystems. Because fewer island rodent eradications have been attempted for mice compared to rats (Rattus spp.), less is known about efficacy and palatability of rodenticide baits for mouse eradications. We performed a series of bait acceptance and efficacy cage trials using a standard formulation of brodifacoum-based rodenticide on wild-caught mice from Sand Island, Midway Atoll, to help inform a proposed eradication there. Mice were offered ad libitum brodifacoum pellets along with various alternative food sources, and a “no choice” treatment group received only bait pellets. Mortality in the no choice trial was 100%; however, when offered alternative foods, mice preferred the alternative diets to the bait, leading to low mortality (40%). Because there was concern that the bittering agent Bitrex® in the formulation may have reduced palatability, we conducted a subsequent trial comparing brodifacoum bait with and without Bitrex. Mortality in the with-Bitrex treatment group was slightly higher, indicating that the bittering agent was not likely responsible for low efficacy. Laboratory trials cannot account for the numerous environmental and behavioral factors that influence bait acceptance nor replicate the true availability of alternative food sources in the environment, so low efficacy results from these trials should be interpreted cautiously and not necessarily as a measure of the likelihood of success or failure of a proposed eradication
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