18,473 research outputs found
The Possible Interstellar Anion CH2CN-: Spectroscopic Constants, Vibrational Frequencies, and Other Considerations
It is hypothesized that the A ^1B_1 <- X ^1A' excitation into the
dipole-bound state of the cyanomethyl anion (CH2CN-) is proposed as the carrier
for one diffuse interstellar band. However, this particular molecular system
has not been detected in the interstellar medium even though the related
cyanomethyl radical and the isoelectronic ketenimine molecule have been found.
In this study we are employing the use of proven quartic force fields and
second-order vibrational perturbation theory to compute accurate spectroscopic
constants and fundamental vibrational frequencies for ^1A' CH2CN- in order to
assist in laboratory studies and astronomical observations
The Plasma Capacitor in a Magnetic Field
Impedance computations for parallel plate and coaxial cylinder plasma capacitors in magnetic fiel
Diagrammatic Coupled Cluster Monte Carlo
We propose a modified coupled cluster Monte Carlo algorithm that
stochastically samples connected terms within the truncated
Baker--Campbell--Hausdorff expansion of the similarity transformed Hamiltonian
by construction of coupled cluster diagrams on the fly. Our new approach --
diagCCMC -- allows propagation to be performed using only the connected
components of the similarity-transformed Hamiltonian, greatly reducing the
memory cost associated with the stochastic solution of the coupled cluster
equations. We show that for perfectly local, noninteracting systems, diagCCMC
is able to represent the coupled cluster wavefunction with a memory cost that
scales linearly with system size. The favorable memory cost is observed with
the only assumption of fixed stochastic granularity and is valid for arbitrary
levels of coupled cluster theory. Significant reduction in memory cost is also
shown to smoothly appear with dissociation of a finite chain of helium atoms.
This approach is also shown not to break down in the presence of strong
correlation through the example of a stretched nitrogen molecule. Our novel
methodology moves the theoretical basis of coupled cluster Monte Carlo closer
to deterministic approaches.Comment: 31 pages, 6 figure
Scaling and singularities in the entrainment of globally-coupled oscillators
The onset of collective behavior in a population of globally coupled
oscillators with randomly distributed frequencies is studied for phase
dynamical models with arbitrary coupling. The population is described by a
Fokker-Planck equation for the distribution of phases which includes the
diffusive effect of noise in the oscillator frequencies. The bifurcation from
the phase-incoherent state is analyzed using amplitude equations for the
unstable modes with particular attention to the dependence of the nonlinearly
saturated mode on the linear growth rate . In general
we find where is the
diffusion coefficient and is the mode number of the unstable mode. The
unusual factor arises from a singularity in the cubic term of
the amplitude equation.Comment: 11 pages (Revtex); paper submitted to Phys. Rev. Let
Effect of Hydro-Resistance Training on Bat Velocity
The purpose of this study was to determine the effect of hydro-resistance training on bat velocity during mimicked baseball swings in twenty-five female college students. Subjects were pre-tested for bat velocity and assigned to dry land (n = 8), water (n = 8), and control (n = 9) groups. The dry land group swung a 737 g (26 oz) Easton T1 Thunderstick baseball bat for three sets of 15 swings, three days per week, for eight weeks. The water group performed the swings in shoulder deep water. The dry land and water groups also participated in mandatory team general resistance training three days per week. The control group performed no bat swing or resistance-training regimens. Mean bat velocity was measured with an electronic eye-timing device. A 3 x 2 (Group x Time) ANOVA with repeated measures was used for statistical analysis, followed up with Tukey’s post hoc test. Bat velocity decreased significantly for the dry land and water groups (24.0 ± 3.6 m/s to 20.6 ± 4.1 m/s and 23.8 ± 3.5 to 18.8 ± 4.1 m/s, respectively). Bat velocity did not change for the control group (21.5 ± 3.0 m/s to 20.2 ± 2.1 m/s). We speculate that the decreased bat velocity in the dry land and water groups was caused by the mandatory team general resistance-training program
Remote functionalisation via sodium alkylamidozincate intermediates : access to unusual fluorenone and pyridyl ketone reactivity patterns
Treating fluorenone or 2-benzoylpyridine with the sodium zincate [(TMEDA)center dot Na(mu-Bu-t)(mu-TMP)Zn(Bu-t)] in hexane solution, gives efficient Bu-t addition across the respective organic substrate in a highly unusual 1,6-fashion, producing isolable organometallic intermediates which can be quenched and aerobically oxidised to give 3-tert-butyl-9H-fluoren-9-one and 2-benzoyl-5-tert-butylpyridine respectively
Implications of new measurements of O-16 + p + C-12,13, N-14,15 for the abundances of C, N isotopes at the cosmic ray source
The fragmentation of a 225 MeV/n O-16 beam was investigated at the Bevalac. Preliminary cross sections for mass = 13, 14, 15 fragments are used to constrain the nuclear excitation functions employed in galactic propagation calculations. Comparison to cosmic ray isotonic data at low energies shows that in the cosmic ray source C-13/C approximately 2% and N-14/0=3-6%. No source abundance of N-15 is required with the current experimental results
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