5,065 research outputs found
Magnetoelectric properties of [FeCl(HO)] with K, Rb, Cs
The compounds [FeCl(HO)] with K, Rb, Cs are identified as
new linear magnetoelectric materials. We present a detailed investigation of
their linear magnetoelectric properties by measurements of pyroelectric
currents, dielectric constants and magnetization. The anisotropy of the linear
magnetoelectric effect of the K-based and Rb-based compound is consistent with
the magnetic point group , already reported in literature. A symmetry
analysis of the magnetoelectric effect of the Cs-based compound allows to
determine the magnetic point group and to develop a model for its
magnetic structure. In addition, magnetic-field versus temperature phase
diagrams are derived and compared to the closely related multiferroic
(NH)[FeCl(HO)].Comment: 17 pages, 10 figures (updated to the weakly revised version that has
been accepted for publication
Propagating Polaritons in III-Nitride Slab Waveguides
We report on III-nitride waveguides with c-plane GaN/AlGaN quantum wells in
the strong light-matter coupling regime supporting propagating polaritons. They
feature a normal mode splitting as large as 60 meV at low temperatures thanks
to the large overlap between the optical mode and the active region, a
polariton decay length up to 100 m for photon-like polaritons and lifetime
of 1-2 ps; with the latter values being essentially limited by residual
absorption occurring in the waveguide. The fully lattice-matched nature of the
structure allows for very low disorder and high in-plane homogeneity; an
important asset for the realization of polaritonic integrated circuits that
could support nonlinear polariton wavepackets up to room temperature thanks to
the large exciton binding energy of 40 meV
Probing Transport Theories via Two-Proton Source Imaging
Imaging technique is applied to two-proton correlation functions to extract
quantitative information about the space-time properties of the emitting source
and about the fraction of protons that can be attributed to fast emission
mechanisms. These new analysis techniques resolve important ambiguities that
bedeviled prior comparisons between measured correlation functions and those
calculated by transport theory. Quantitative comparisons to transport theory
are presented here. The results of the present analysis differ from those
reported previously for the same reaction systems. The shape of the two-proton
emitting sources are strongly sensitive to the details about the in-medium
nucleon-nucleon cross sections and their density dependence.Comment: 23 pages, 11 figures. Figures are in GIF format. If you need
postscript format, please contact: [email protected]
Restructuring Programming Instruction in the Computer Information Systems Curriculum: One Department\u27s Approach
The rationale for and details of one Computer Information Systems (CIS) department\u27s plans for a drastic restructuring of the CIS curriculum are presented. The proposed approach is compared with current and developing model curricula for both computer science (CS) and computer information systems programs. The new curriculum\u27s approach to information systems construction is characterized by delivering training in the use of fourth generation development tools, the assembly of software components, event-driven programming and client/server practices. The development tools, the programming environment and the client interface are all equipped with a graphical user interface (GUI)
Purification and characterization of a calmodulin-dependent protein kinase that is highly concentrated in brain
A calcium and calmodulin-dependent protein kinase has been purified from rat brain. It was monitored during the purification by its ability to phosphorylate the synaptic vesicle-associated protein, synapsin I. A 300-fold purification was sufficient to produce kinase that is 90-95% pure as determined by scans of stained sodium dodecyl sulfate-polyacrylamide gels and has a specific activity of 2.9 mumol of 32P transferred per min/mg of protein. Thus, the kinase is a relatively abundant brain enzyme, perhaps comprising as much as 0.3% of the total brain protein. The Stokes radius (95 A) and sedimentation coefficient (16.4 S) of the kinase indicate a holoenzyme molecular weight of approximately 650,000. The holoenzyme is composed of three subunits as judged by their co-migration with kinase activity during the purification steps and co-precipitation with kinase activity by a specific anti-kinase monoclonal antibody. The three subunits have molecular weights of 50,000, 58,000, and 60,000, and have been termed alpha, beta', and beta, respectively. The alpha- and beta-subunits are distinct peptides, however, beta' may have been generated from beta by proteolysis. All three of these subunits bind calmodulin in the presence of calcium and are autophosphorylated under conditions in which the kinase is active. The subunits are present in a ratio of about 3 alpha-subunits to 1 beta/beta'-subunit. We therefore postulate that the 650,000-Da holoenzyme consists of approximately 9 alpha-subunits and 3 beta/beta'-subunits. The abundance of this calmodulin-dependent protein kinase indicates that its activation is likely to be an important biochemical response to increases in calcium ion concentration in neuronal tissue
Relaxation in the 3D ordered CoTAC spin chain by quantum nucleation of 0D domain walls
We have shown that resonant quantum tunnelling of the magnetisation (QTM),
until now observed only in 0D cluster systems (SMMs), occurs in the molecular
Ising spin chain, CoTAC ([(CH_3)_3NH]CoCl_3 - 2H_2O) which orders as a canted
3D-antiferromagnet at T_C=4.15 K. This effect was observed around a resonant
like field value of 1025 Oe. We present here measurements of the relaxation of
the magnetisation as a function of time, from the zero field cooled (ZFC)
antiferromagnet state and from the saturated ferromagnet state. We show that,
at the resonant field, the relaxation from the saturated state occurs in a
complicated process, whereas, surprisingly, in the case of the ZFC state, the
relaxation is exponential.Comment: 4 pages, 5 figures, LT25 proceeding
Synthesis and Characterization of Three-Coordinate Ni(III)-Imide Complexes
A new family of low-coordinate nickel imides supported by 1,2-bis(di-tert-butylphosphino)ethane was synthesized. Oxidation of nickel(II) complexes led to the formation of both aryl- and alkyl-substituted nickel(III)-imides, and examples of both types have been isolated and fully characterized. The aryl substituent that proved most useful in stabilizing the Ni(III)-imide moiety was the bulky 2,6-dimesitylphenyl. The two Ni(III)-imide compounds showed different variable-temperature magnetic properties but analogous EPR spectra at low temperatures. To account for this discrepancy, a low-spin/high-spin equilibrium was proposed to take place for the alkyl-substituted Ni(III)-imide complex. This proposal was supported by DFT calculations. DFT calculations also indicated that the unpaired electron is mostly localized on the imide nitrogen for the Ni(III) complexes. The results of reactions carried out in the presence of hydrogen donors supported the findings from DFT calculations that the adamantyl substituent was a significantly more reactive hydrogen-atom abstractor. Interestingly, the steric properties of the 2,6-dimesitylphenyl substituent are important not only in protecting the Ni═N core but also in favoring one rotamer of the resulting Ni(III)-imide, by locking the phenyl ring in a perpendicular orientation with respect to the NiPP plane
A Semiclassical Approach to Fusion Reactions
The semiclassical method of Alder and Winther is generalized to study fusion
reactions. As an illustration, we evaluate the fusion cross section in a
schematic two-channel calculation. The results are shown to be in good
agreement with those obtained with a quantal Coupled-Channels calculation. We
suggest that in the case of coupling to continuum states this approach may
provide a simpler alternative to the Continuum Discretized Coupled-Channels
method.Comment: 6 pages, 1 figure, invited talk at the International Symposium "A new
era of Nuclear Structure Physics", Niigata, Japan, Nov. 19-22 200
Prenatal diagnosis of trisomy 6q25.3-qter and monosomy 10q26.12-qter by array CGH in a fetus with an apparently normal karyotype.
We present the prenatal case of a 12.5-Mb duplication involving 6q25-qter and a 12.2-Mb deletion encompassing 10q26-qter diagnosed by aCGH, while conventional karyotype showed normal results. The genotype-phenotype correlation between individual microarray and clinical findings adds to the emerging atlas of chromosomal abnormalities associated with specific prenatal ultrasound abnormalities
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