Productive utilization of chlorobenzene: palladium-catalyzed selective oxidation of alcohols

[reaction: see text] The palladium/ligand-catalyzed activation of chlorobenzene provides a general, efficient, and functional group friendly method for the selective oxidation of alcohols to carbonyl compounds.     

Precision cosmology and the density of baryons in the universe

Big-bang nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropy measurements give independent, accurate measurements of the baryon density and can test the framework of the standard cosmology. Early CMB data are consistent with the long-standing conclusion from BBN that baryons constitute a small fraction of matter in the Universe, but may indicate a slightly higher value for the baryon density. We clarify precisely what the two methods determine and point out that differing values for the baryon density can indicate either an inconsistency or physics beyond the standard models of cosmology and particle physics. We discuss other signatures of the new physics in CMB anisotropy.     

Analysing the effectiveness of <Emphasis Type="Italic">Chlamydia</Emphasis> screening

Chlamydia is a highly prevalent sexually transmitted infection which is normally asymptomatic. Chlamydia is a major public health concern since it is one of the biggest causes of infertility in the UK. A screening programme has been proposed and here we analyse its potential cost-effectiveness. Previous modelling analyses for Chlamydia screening have been inadequate at representing the dynamic complexity of the impact. Most notably, the impact on the population prevalence has been overlooked as well as the possibility for an individual to become re-infected after treatment. A system dynamics model was built using the array facility in the ithink software to represent a heterogeneous population. This population was disaggregated along two dimensions: age and sexual activity levels. Results suggest that the proposed screening programme would prevent significant numbers of infertility cases annually. Additionally, it could be paying for itself after about four years and recouping the initial outlay after about twelve years.     

Psychophysical correlates of contralateral efferent suppression. I. The role of the medial olivocochlear system in "central masking" in nonhuman primates

An extensive physiological literature, including experimental and clinical studies in humans, demonstrates that activation of the medial olivocochlear (MOC) efferent system, by either contralateral sound or electrical stimulation, can produce significant alterations in cochlear function and suggests a role for the MOC system in influencing the auditory behavior of binaural hearing. The present data are from psychophysical studies in nonhuman primates which seek to determine if the noted physiological changes in response to contralateral acoustic stimulation have a perceptual counterpart. Four juvenile Japanese macaques were trained to respond to the presence of 1-s sinusoids, presented to the test ear, in an operant reinforcement paradigm. Thresholds were compared for frequencies ranging from 1.0 to 4.0 kHz in quiet, with thresholds measured when continuous, two octave-band noise, centered on the test tone frequency, was presented in the contralateral ear. Contralateral noise was presented at levels of 10-60 dB above detection threshold for the test-tone frequency. While some variability was evident across subjects, both in the frequency distribution and magnitude (as a function of contralateral noise level), all subjects exhibited an increase, or suppression of thresholds in the presence of contralateral noise. On average, thresholds increased systematically with contralateral noise level, to a peak of 7 dB. In one subject, the threshold increase seen with contralateral noise was significantly reduced when the MOC was surgically sectioned on the floor of the IVth ventricle. The characteristics of the measured shifts in behavioral thresholds, in the presence of contralateral noise reported here, are qualitatively and quantitatively similar to both efferent physiological suppression effects and psychophysical central masking threshold shifts which have been reported previously. These data suggest that at least some aspects of "central masking" are efferent-mediated peripheral processes, and that the term "central masking" may be incorrect.     

Oscillatory melting temperature of the vortex smectic phase in layered superconductors

We report on transport measurements of YBa 2Cu 3O (7-delta) single crystals with different oxygen contents in the geometry B, J ||ab (J perpendicularB). Our data show that the vortices become confined between the Cu-O planes below a well-defined temperature at which the effective size 2xi of the vortex core is approximately equal to the period of the Cu-O layers. This confinement strongly increases the vortex liquid freezing temperature. A new melting line is found separating a vortex liquid and a smectic phase, which shows an oscillatory field dependence reflecting differences between commensurate and incommensurate smectic states.     

Cryopreservation of the australian species Macropidia fuliginosa (Haemodoraceae) by vitrification

Somatic embryos were used to develop a cryopreservation protocol for Macropidia fuliginosa, a commercially-important species endemic to the south-west of Western Australia. Somatic embryos were allowed to develop from embryogenic callus for three weeks on an kinetin medium prior to processing. These were transferred and cultured on a agar solidified basal medium supplemented with 0 to 0.6 M sorbitol for 2 d prior to incubation in Plant Vitrification Solution Two (PVS2). Following this, embryos were then washed in 1 M sucrose solution (treated controls) or cooled in liquid nitrogen (LN). Cooled embryos were then warmed and washed in sucrose solution. Highest survival for cooled treatments (67.3%) was achieved by preculture with 0.4 M sorbitol, then incubation in PVS2. Further experimentation varying pre-culture duration (2 or 3 d) and incubation on either glycerol (0.8 M) or sorbitol (0.4 M) indicated that very high survival (90.6%) of embryos was achievable by adopting a 2 d preculture period on 0.8 M glycerol. The phenotype and growth rates of plants obtained using this protocol were similar to those of parent plants. This optimised procedure was then applied to tissue culture-derived shoot apices of the same clone also resulting in a high survival rate (84.4%).     

High-energy, high-power ytterbium-doped Q-switched fiber laser

We report on a Q -switched, cladding-pumped, ytterbium-doped large-mode-area fiber laser operating at 1090 nm that is capable of generating 2.3 mJ of output pulse energy at a 500-Hz repetition rate and more than 5 W of average output power at higher repetition rates in a high-brightness beam (M(2) = 3) . Using a similar fiber with a smaller core, we generated >0.5-mJ pulses in a diffraction-limited beam. Our results represent a threefold increase in pulse energy over previously published values for Q-switched fiber lasers and firmly establish fiber lasers as compact, multiwatt, multimillijoule pulse sources with large scope for both industrial and scientific applications.     

Progress toward ignition with noncryogenic double-shell capsules

Inertial confinement fusion implosions using capsules with two concentric shells separated by a low density region (double shells) are reported which closely follow one dimensional (1D) radiatively driven hydrodynamics simulations. Capsule designs which mitigate Au M-band radiation asymmetries appear to correspond more closely to 1D simulations than targets lacking mitigation of hohlraum drive M-band nonuniformities. One capsule design achieves over 50% of the unperturbed 1D calculated yield at a convergence ratio of 25.5, comparable to that of a double-shell design for an ignition capsule at the National Ignition Facility.     

Detection of the DeltaF508 mutation in the CFTR gene by means of time-resolved fluorescence methods.

A rapid recognition in the base sequence of nucleic acids is an important prerequisite toward the diagnosis of genetic diseases and their carrier states. We have developed a hybridisation method in which a fluorescently labeled oligonucleotide is used to detect point mutations in a target by a simple fluorescence lifetime analysis of the emission of the fluorescent label. We applied this method to detect the deltaF508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in a model system and with biologically derived PCR product and discuss the potential generality of this method.