Millimeter-Wave Profiled Corrugated Horns for the Quad Cosmic Background Polarization Experiment

In this paper we report on the design and validation process for the profiled corrugated horn antennas, which feed the bolometer array of a cosmology experiment known as QUaD located at the South Pole. This is a cosmic background radiation polarization project, which demands precise knowledge and control of the optical coupling to the signal in order to map the feeble E- and B-polarization mode structure. The system will operate in two millimeter wavelength bands at 100 and 150 GHz. The imaging horn array collects the incoming signal via on-axis front-end optics and a Cassegrain telescope, with a cold stop in front of the array to terminate side-lobe structure at an edge taper of –20dB. The corrugated horn design process was undertaken using in-house analytical software tools, based on modal scattering, specially developed for millimeter -wave profiled horn antennas. An important part of the instrument development was the validation of the horn design, in particular to verify low edge taper levels and the required well-defined band edges. Suitable feed horn designs were measured and were found to be in excellent agreement with theoretical predictions.     

Limit distributions of sums of m-dependent Bernoulli random variables

Summary The set of limit distributions of row sums of a triangular array of Bernoulli random variables which is strictly stationary and m-dependent in each row is characterized. Necessary and sufficient conditions for the convergence of the row sums to a given limit distribution are found. The case of convergence to a Poisson distribution is given special attention.     

Coupling CMLs and the synchronization of a multilayer neural computing system

A coupled map lattice (CML) provides a mathematical model for both spatially extended physical and biological systems, and for a new type of parallel computing system. We analyse a general process to realize a multilayer structured CML by coupling m CMLs together with arbitrary coupling structure. As an application we use this coupling process in the study of a CML with multilayer planar architecture and non-symmetric hierarchical coupling between the layers. These CMLs model neural architectures and use chaotic maps as the basic elements in the lattice. We measure the complexity of the state of each layer and an increase in spatio-temporal coherence as one ascends a hierarchical feedforward layered network.     

The contribution to the specific heat from the spin-phonon interaction for (3d)n ions

The contribution, ΔC, to the specific heat arising from the spin-phonon interaction is calculated for general spin values. For a given set of spin-phonon coupling constants and cubic symmetry the ratio ΔC_max/ C(Schottky)_max for ions having S = 2 or $\text{5}\text{2}$ is one or two orders of magnitude greater than that for ions having S = 1 or $\text{3}\text{2}$. The relative low values of ΔC in the latter cases is traced to two distinct reasons, and the differences that the inclusion of a lower symmetry crystals field makes to the ratio is discussed.     

The c.hfl-value of the NO δ(0, 0) band by the line absorption method

The resonance-line absorption method has been applied to the isolated but unresolved (0, 0) band of the NO δ system, C²Π - X²Π. The light source was the N + O radiative recombination afterglow in a discharge flow system. This is an optically-thin source of δ(0, 0) emission, with known rotational temperature and Doppler width, uncontaminated with overlapping ε bands. Corrections for effects of accidental line overlap within the band and perturbation between the C and B states have been applied in comparing observed and computed band fractional absorption curves. For the δ(0, 0) band, this comparison gives c.hfl = (2·2 ± 0·3) × 10^-3. Our result is compared with previous measurements obtained by four other independent methods.     

Importance of heat capacity effects in the association of hydrocarbon moieties in aqueous solution

Values are reported for changes in heat capacity that accompany the formation of hydrocarbon-hydrocarbon dimers and hydrocarbon-polar hydrocarbon derivative dimers in dilute aqueous solution. Highly negative C _p ^o are obtained; the enthalpy changes, endothermic at room temperature, tend to decrease to zero in the range 50 to 80°C. A discussion is given of the importance of heat capacity effects in relation to the stability of hydrophobic association complexes.     

Using a nondirect product discrete variable representation for angular coordinates to compute vibrational levels of polyatomic molecules

In this paper we test a nondirect product discrete variable representation (DVR) method for solving the bend vibration problem and compare it with well-established direct product DVR and finite basis representation approaches.     

Quantitation and metabolism of mitoquinone, a mitochondria-targeted antioxidant, in rat by liquid chromatography/tandem mass spectrometry

Mitoquinone (MitoQ10 mesylate) is a mitochondria-targeted antioxidant undergoing development for the treatment of neurodegenerative diseases. The aim of this study was to develop and validate an assay based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) to determine mitoquinone and to detect and identify the metabolites of MitoQ10 in rat plasma after an oral dose. After a simple protein precipitation step, plasma samples were analyzed by reversed-phase liquid chromatography using gradient elution with acetonitrile/water/formic acid. Electrospray ionization in the positive ion mode with multiple reaction monitoring (MRM) was used to analyze mitoquinone employing the deuterated compound (d3-MitoQ10 mesylate) as internal standard. The calibration curve for mitoquinone was linear over the concentration range 0.5-250 ng/mL with a correlation coefficient>0.995. The method was sensitive (limit of quantitation 0.5 ng/mL) and had acceptable accuracy (relative error<8.7%) and precision (intra- and inter-day coefficient of variation<12.4%). Recoveries of mitoquinone at concentrations of 1.5, 20 and 200 ng/mL were in the range 87-114%. The method was successfully applied to a pharmacokinetic study in rat after a single oral dose in which four metabolites of MitoQ10 were tentatively identified as hydroxylated MitoQ10, desmethyl MitoQ10 and the glucuronide and sulfate conjugates of the quinol form of MitoQ10.     

Siegel’s theorem for Drinfeld modules

We prove a Siegel type statement for finitely generated -submodules of under the action of a Drinfeld module . This provides a positive answer to a question we asked in a previous paper. We also prove an analog for Drinfeld modules of a theorem of Silverman for nonconstant rational maps of over a number field.     

Flow-induced effects in mixed surfactant mesophases

Spatially resolved small-angle neutron scattering, SANS, has been used to investigate the response of the mixed microstructure of the dialkyl chain cationic and nonionic surfactant mixtures of (2,3-diheptadecyl ester ethoxy-n-propyl-1), 1,1,1-trimethyl ammonium chloride/octadecyl monododecyl ether, DHTAC/C18EO10, and DHTAC/dodecyl monododecadecyl ether, Coco20, over the velocity flow pattern of a crossed-slot elongational flow cell. The two different surfactant mixtures have different relative amounts of lamellar and micellar components, and this results in some differences in the flow-induced response. For the DHTAC/C18EO10, which is predominantly in the form of lamellar fragments, a complex pattern of orientational ordering is observed which reflects the competition between or demixing of the two principal flow directions in the cell.