Correlations in quasi-elastic proton-proton scattering at total c.m. energies of 23 and 31 GeV

Data are reported on angular and rapidity (η) distributions of a charged particle c produced in quasi-elastic proton-proton scattering (p+p→p+c+anything) at the CERN ISR.     

The use of a mannitol-derived fused oxacycle as a combinatorial scaffold

An efficient and high-yielding solid-phase synthesis of a small library of compounds containing a cis-fused pyranofuran structural motive is described. With use of the cheap and readily available D-(+)-mannitol, a highly functionalized sugar template was synthesized and immobilized on a solid support via an olefinic linker. Modification of this two-point molecular scaffold and subsequent ring-closing metathesis/cleavage gave access to a series of functionalized conformationally constrained fused oxacycles.     

Effects of central and noncentral components of the Preedom-Wildenthal interaction

The influence of the various components of the Preedom-Wildenthal interaction — viz. central, tensor, spin-orbit (LS) and antisymmetric spin-orbit (ALS) — on properties ofA=20–22 nuclei is investigated. The effects of the LS and the ALS component on spectroscopic observables are found to be very similar. It is shown that it is possible to remove the ALS component, which component is absent in the free-nucleon-nucleon interaction, in favour of an enhanced LS component, without spoiling the agreement with experiment. Furthermore it was found that a similarity of the effects of the various components on the properties of states inA=21,T=1/2 leads to a classification of these levels into groups that can be interpreted as collective bands.     

Spectroscopy of 32P

Particle-gamma angular correlations have been measured with the ²⁹Si(α,pγ)³²P reaction at bombarding energies E_α = 10.65, 10.69 and 11.00 MeV. Together with DSA lifetime measurements these experiments lead to seven unambiguous spin assignments to levels below 3.5 MeV excitation energy in ³²P. In addition, the measured mixing ratios and branching ratios yield many dipole and quadrupole transition strengths. The previously known 3.44 MeV level is a doublet with components at 3 443.0±0.6 and 3 444.0±0.9 keV.     

On the systematic energy difference between states of positive and negative parity

Comparison of the nuclear spectra in the mass region A = 10–40 shows a systematic difference between states of positive and negative parity. This systematic difference can be explained quantitatively with methods derived from statistical spectroscopy. The influence of spurious states is corrected for.     

Sampling small volumes of ambient ammonia using a miniaturized gas sampler

The development of a gas sampler for a miniaturized ambient ammonia detector is described. A micromachined channel system is realized in glass and silicon using powder blasting and anodic bonding. The analyte gas is directly mixed with purified water, dissolving the ammonia that will dissociate into ammonium ions. Carrier gas bubbles are subsequently removed from the liquid stream through a venting hole sealed with a microporous water repellent PTFE membrane. A flow restrictor is placed at the outlet of the sampler to create a small overpressure underneath the membrane, enabling the gas to leave through the membrane. Experiments with a gas flow of 1 ml min(-1), containing ammonia concentrations ranging from 9.4 ppm to 0.6 ppm in a nitrogen carrier flow have been carried out, at a water flow of 20 microl min(-1). The ammonium concentration in the sample solution is measured with an electrolyte conductivity detector. The measured values correspond with the concentration calculated from the initial ammonia concentration in the analyte gas, the fifty times concentration enhancement due to the gas-liquid volume difference and the theoretical dissociation equilibrium as a function of the resulting pH.     

Variations in substitution rate in human and mouse genomes

We present a method to quantify spatial fluctuations of the substitution rate on different length scales throughout genomes of eukaryotes. The fluctuations on large length scales are found to be predominantly a consequence of a coarse-graining effect of fluctuations on shorter length scales. This is verified for both the mouse and the human genome. We also found that the relative standard deviation of fluctuations in substitution rate is about a factor three smaller in mouse than in human. The method allows furthermore to determine time-resolved substitution rate maps of the genomes, where the corresponding autocorrelation functions quantify the velocity of spatial chromosomal reorganization.     

Phase synchronization from noisy univariate signals

We present methods for detecting phase synchronization of two unidirectionally coupled, self-sustained noisy oscillators from a signal of the driven oscillator alone. One method detects soft phase locking; another hard phase locking. Both are applied to the problem of detecting phase synchronization in von Kármán vortex flow meters.