1,941 research outputs found
Large zero-field cooled exchange-bias in bulk Mn2PtGa
We report a large exchange-bias (EB) effect after zero-field cooling the new
tetragonal Heusler compound Mn2PtGa from the paramagnetic state. The
first-principle calculation and the magnetic measurements reveal that Mn2PtGa
orders ferrimagnetically with some ferromagnetic (FM) inclusions. We show that
ferrimagnetic (FI) ordering is essential to isothermally induce the exchange
anisotropy needed for the zero-field cooled (ZFC) EB during the virgin
magnetization process. The complex magnetic behavior at low temperatures is
characterized by the coexistence of a field induced irreversible magnetic
behavior and a spin-glass-like phase. The field induced irreversibility
originates from an unusual first-order FI to antiferromagnetic transition,
whereas, the spin-glass like state forms due to the existence of anti-site
disorder intrinsic to the material.Comment: 5 pages, 4 figures, supplementary material included in a separate
file; accepted for publication in PR
Early Intervention and Prevention of Self-Injurious Behavior Exhibited by Children with Autism Spectrum Disorders (ASD)
Autism is a Neuro-Developmental Disorder affecting socialization, communication with stereotyped and repetitive behaviors. The research Scientists all over world found that Self-injurious behavior (SIB) is a serious, chronic problem influencing about 10% to 14% of children with Autism Spectrum Disorders. (Iwata & Rodgers, 1992). It occurs frequently in form of face slapping, head banging, and hand biting (Durand & Crimmins, 1988). Such aberrant behavior is so obvious and physically harmful that catches caregivers’ and special educators’ attention all the times in naturalistic settings (Durand & Crimmins, 1988). Injuries and health problems caused by this behavior could highly increase social isolation, restricted educational and vocational opportunities and costly medical and residential care (Kurtz et al., 2003). Therefore, early and appropriate intervention to decelerate such aberrant behavior is indeed needed. The purposes of this study were to assess the functions of self-injurious behavior in children with Autism Spectrum Disorders (ASD) and to explore early interventions to reduce such aberrant behavior
Linear-in-frequency optical conductivity in GdPtBi due to transitions near the triple points
The complex optical conductivity of the half-Heusler compound GdPtBi is
measured in a frequency range from 20 to 22 000 cm (2.5 meV - 2.73 eV)
at temperatures down to 10 K in zero magnetic field. We find the real part of
the conductivity, , to be almost perfectly linear in
frequency over a broad range from 50 to 800 cm ( 6 - 100 meV) for
K. This linearity strongly suggests the presence of
three-dimensional linear electronic bands with band crossings (nodes) near the
chemical potential. Band-structure calculations show the presence of triple
points, where one doubly degenerate and one nondegenerate band cross each other
in close vicinity of the chemical potential. From a comparison of our data with
the optical conductivity computed from the band structure, we conclude that the
observed nearly linear originates as a cumulative effect
from all the transitions near the triple points.Comment: 5+ pages, 5 figures, band-structure and optical-conductivity
calculations adde
Two-channel conduction in YbPtBi
We investigated transport, magnetotransport, and broadband optical properties
of the half-Heusler compound YbPtBi. Hall measurements evidence two types of
charge carriers: highly mobile electrons with a temperature-dependent
concentration and low-mobile holes; their concentration stays almost constant
within the investigated temperature range from 2.5 to 300 K. The optical
spectra (10 meV - 2.7 eV) can be naturally decomposed into contributions from
intra- and interband absorption processes, the former manifesting themselves as
two Drude bands with very different scattering rates, corresponding to the
charges with different mobilities. These results of the optical measurements
allow us to separate the contributions from electrons and holes to the total
conductivity and to implement a two-channel-conduction model for description of
the magnetotransport data. In this approach, the electron and hole mobilities
are found to be around 50000 and 10 cm/Vs at the lowest temperatures (2.5
K), respectively.Comment: 6 page
Evaluation and Management of Patients with Noncardiac Chest Pain
Up to a third of patients undergoing coronary angiography for angina-like chest pain are found to have normal coronary arteries and a substantial proportion of these individuals continue to consult and even attend emergency departments. Initially, these patients are usually seen by cardiologists but with accumulating evidence that the pain might have a gastrointestinal origin, it may be more appropriate for them to be cared for by the gastroenterologist once a cardiological cause has been excluded. This review covers the assessment and management of this challenging condition, which includes a combination of education, reassurance, and pharmacotherapy. For the more refractory cases, behavioral treatments, such as cognitive behavioral therapy or hypnotherapy, may have to be considered
Protein chaperones and non-protein substrates: on substrate promiscuity of GroEL
Chaperonins are a group of molecular chaperones that form large multi subunit structures and are found in all forms of life. Encoded by the groEL and groES genes, bacterial chaperonins are required for appropriate folding of many cellular proteins. A significant number of bacterial species are known to express multiple copies of chaperonin genes, possibly to confer redundancy of GroEL function in these species. It is also likely that the paralogous GroELs might be undergoing diversification of function as a consequence of gene duplication. We argue in this article that different chaperonins in an organism might be involved in distinct biochemical functions that remain to be discovered, some of which might be modulated by different oligomeric states of the chaperonins
Large nonlinear absorption and refraction coefficients of carbon nanotubes estimated from femtosecond Z-scan measurements
Nonlinear transmission of 80 and 140 femtosecond pulsed light with wavelength through single walled carbon nanotubes suspended in water
containing sodium dodecyl sulphate is studied. Pulse-width independent
saturation absorption and negative cubic nonlinearity are observed,
respectively, in open and closed aperture Z-scan experiments. The theoretical
expressions derived to analyze the z-dependent transmission in the saturable
limit require two photon absorption coefficient and a
nonlinear index to fit the data.Comment: 10 pages, 2 figures. Accepted and to appear in Applied Physics
Letter
Field-induced charge symmetry revealed by nuclear magnetic resonance in the topological insulator Bi<sub>2</sub>Te<sub>3</sub>
Nuclear magnetic resonance (NMR) was recently shown to measure the bulk band inversion of Bi2Se3 through changes in the Bi-209 nuclear quadrupole interaction, and the corresponding tensor of the local electric field gradient was found to follow, surprisingly, the direction of the external magnetic field if the sample is rotated. This manifests a hidden property of the charge carriers in the bulk of this topological insulator, which is explored here with another material, Bi2Te3. It is found that two electric field gradients appear to be present at Bi-209, one rests with the lattice, as usual, while a second follows the external field if it is rotated with respect to the crystal axes. These electronic degrees of freedom and their lifetime is believed to be responsible for an alternate quadrupolar relaxation that should lead to other special properties including the electronic specific heat
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