7,162 research outputs found
Determination of the resistivity anisotropy of SrRuO by measuring the planar Hall effect
We have measured the planar Hall effect in epitaxial thin films of the
itinerant ferromagnet SrRuO3 patterned with their current paths at different
angles relative to the crystallographic axes. Based on the results, we have
determined that SrRuO3 exhibits small resistivity anisotropy in the entire
temperature range of our measurements (between 2 to 300 K); namely, both above
and below its Curie temperature (~150 K). It means that in addition to
anisotropy related to magnetism, the resistivity anisotropy of SrRuO3 has an
intrinsic, nonmagnetic source. We have found that the two sources of anisotropy
have competing effects
Detection and imaging of the oxygen deficiency in single crystalline YBaCuO thin films using a positron beam
Single crystalline YBaCuO
(YBCO) thin films were grown by pulsed laser deposition (PLD) in order to probe
the oxygen deficiency using a mono-energetic positron beam. The sample
set covered a large range of (0.191<<0.791) yielding a
variation of the critical temperature between 25 and 90\,K. We
found a linear correlation between the Doppler broadening of the positron
electron annihilation line and determined by X-ray diffraction (XRD).
Both, the origin of the found correlation and the influence of metallic
vacancies, were examined with the aid of ab-initio calculations that allowed us
(i) to exclude the presence of Y vacancies and (ii) to ensure that positrons
still probe despite the potential presence of Ba or Cu vacancies. In
addition, by scanning with the positron beam the spatial variation of
could be analyzed. It was found to fluctuate with a standard deviation of up to
within a single YBCO film
Constructions for cyclic sieving phenomena
We show how to derive new instances of the cyclic sieving phenomenon from old
ones via elementary representation theory. Examples are given involving objects
such as words, parking functions, finite fields, and graphs.Comment: 18 pages, typos fixed, to appear in SIAM J. Discrete Mat
Program for sea level test firing of rocket engines final report, 1 sep. 1964 - 1 feb. 1965
Bipropellant rocket engines with radiation cooled thrust combustion chambers of molybdenum fired for testing and material evaluatio
Uniaxial magnetocrystalline anisotropy in
is a paramagnetic metal and since its low temperature
resistivity is described by with , it
is also considered a non-Fermi liquid (NFL) metal. We have performed extensive
magnetoresistance and Hall effect measurements of untwinned epitaxial films of
. These measurements reveal that exhibits
uniaxial magnetocrystalline anisotropy. In addition, the low-temperature NFL
behavior is most effectively suppressed when a magnetic field is applied along
the easy axis, suggesting that critical spin fluctuations, possibly due to
proximity of a quantum critical phase transition, are related to the NFL
behavior.Comment: 7 figure
An immunohistochemical study of the telencephalon of the african lungfish, Protopterus annectens
The telencephalon of the African lungflsh, Protopterus annectens , was studied by immunohistochemical techniques in order to identify the major subdivisions of the telencephalon and determine the possible homologues of these subdivisions, if any, in other vertebrates. The distributions of four different neuropeptides (substance P, leucine-enkephalin, avian pancreatic polypeptide, and LANT6), a neurotransmitter (serotonin), and a neurotransmitter-related enzyme that is involved in catecholamine synthesis (tyrosine hydroxylase) were examined. The resultant labeling patterns indicated that the telencephalon of lungfish consists of three major subdivisions–a rostrally and dorsally situated olfactory bulb, a dorsally situated pallial region located caudal to the olfactory bulbs, and a ventrally situated subpallial regions. The dorsal and lateral pallial regions, which both receive secondary olfactory input, are somewhat, distinct from one another cytoarchitectonically, but their immunohistochemical, labeling characteristics did not differ. Thus, the lateral pallium and the dorsal pallium together appear to constitute an olfactory pallium in lungfishes. The medial pallium was found to consist of three immunohisthochemically distinct subdivisions–a dorsal cell group, an intermediate cell group, and a ventral cell group. These medial pallial fields extend throughout the entire rostrocaudal extent of the medial wall of the telencephalon. Although one or more of these medial pallial cell groups may be homologous to specific portions of the medial pallium in land vertebrates, no specific similarities were observed to support any proposed one-to-one correspondences. The possibility that one or more of the medial pallial cell groups of lungfishes correspond to cell groups located in the dorsal pallium of land vertebrates could not be excluded. The subpallium is divided into lateral, medial, and caudal subdivisions. The lateral subdivision appears to be homologous to the basal ganglia of land vertebrates since it contains neuropeptide/neurotransmitter-specific neuronal populations that are characterstic of the striatal and pallidal portions of the basal ganglia of amniotes. The medial subdivision of the subpallium shows the topographic and immunohistochemical characteristics of the septal region and the nucleus accumbens region of the amniote telencephalon. The caudal subpallium does not show any distinctive immunohistochemical labeling characteristics and its possible homologue in land vertebrates is unclear. The present results indicate that the evolution of the telencephalon during the transition from fish to amphibians must have been characterized by a striking conservatism in the case of the subpallium. A basal ganglia and a septal region having many of the characteristics of those of land vertebrates appear to be present in the telencephalon of lungfishes, thereby suggesting that these cell groups were already present in the brains of the earliest lobe-finned fishes. Although the present results suggest that a lateral pallium, or olfactory cortex, was present in the telencephalon of ancestral lobe-finned fish, they do not provide evidence to support the existence in lobe-finned fish of a forerunner of the dorsal pallium of land vertebrates. Further, it is unclear whether the medial pallial cell groups in lungfishes are homologous to cell groups in the medial telencephalic walls of land vertebrates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50032/1/902560313_ftp.pd
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