Prediction of the Spectrum of a Digital Delta–Sigma Modulator Followed by a Polynomial Nonlinearity

This paper presents a mathematical analysis of the power spectral density of the output of a nonlinear block driven by a digital delta-sigma modulator. The nonlinearity is a memoryless third-order polynomial with real coefficients. The analysis yields expressions that predict the noise floor caused by the nonlinearity when the input is constant

Variability in spawning frequency and reproductive development of the narrow-barred Spanish mackerel (Scomberomorus commerson) along the west coast of Australia

The narrow-barred Spanish mackerel (Scomberomorus commerson) is widespread throughout the Indo-West Pacific region. This study describes the reproductive biology of S. commerson along the west coast of Australia, where it is targeted for food consumption and sports fishing. Development of testes occurred at a smaller body size than for ovaries, and more than 90% of males were sexually mature by the minimum legal length of 900 mm TL compared to 50% of females. Females dominated overall catches although sex ratios within daily catches vary considerably and females were rarely caught when spaw n ing. Scomberomorus commerson are seasonally abundant in coastal waters and most of the commercial catch is taken prior to the reproductive season. Spawning occurs between about August and November in the Kimberley region and between October and January in the Pilbara region. No spawning activity was recorded in the more southerly West Coast region, and only in the north Kimberley region were large numbers of fish with spawning gonads collected. Catches dropped to a minimum when spawning began in the Pilbara region, when fish became less abundant in inshore waters and inclement weather conditions limited fishing on still productive offshore reefs. Final maturation and ovulation of oocytes took place within a 24-hour period, and females spawned in the afternoon-evening every three days. A third of these spawning females released batches of eggs on consecutive days. Relationships between length, weight, and batch fecundity are presented

Forecasting Spanish Elections

The behavior of the individual Spanish voter has come to be rather well-understood, thanks to a growing research literature. However, no models have appeared to explain, or to forecast, national election outcomes. The presence of this research gap contrasts sharply with the extensive election forecasting work done on other leading Western democracies. Here we fill this gap. The model, developed from core political economy theory, is parsimonious but statistically robust. Further, it promises considerable prediction accuracy of Spanish general election outcomes, six months before the contest actually occurs. After presenting the model, and carrying out extensive regression diagnostics, we offer an ex ante forecast of the 2012 general election.

Deuterium Abundance in the Most Metal-Poor Damped Lyman alpha System: Converging on Omega_baryons

The most metal-poor DLA known to date, at z = 2.61843 in the spectrum of the QSO Q0913+072, with an oxygen abundance only about 1/250 of the solar value, shows six well resolved D I Lyman series transitions in high quality echelle spectra recently obtained with the ESO VLT. We deduce a value of the deuterium abundance log (D/H) = -4.56+/-0.04 which is in good agreement with four out of the six most reliable previous determinations of this ratio in QSO absorbers. We find plausible reasons why in the other two cases the 1 sigma errors may have been underestimated by about a factor of two. The addition of this latest data point does not change significantly the mean value of the primordial abundance of deuterium, suggesting that we are now converging to a reliable measure of this quantity. We conclude that = -4.55+/-0.03 and Omega_b h^2 (BBN) = 0.0213+/-0.0010 (68% confidence limits). Including the latter as a prior in the analysis of the five year data of WMAP leads to a revised best-fitting value of the power-law index of primordial fluctuations n_s = 0.956+/-0.013 (1 sigma) and n_s < 0.990 with 99% confidence. Considering together the constraints provided by WMAP 5, (D/H)_p, baryon oscillations in the galaxy distribution, and distances to Type Ia supernovae, we arrive at the current best estimates Omega_b h^2 = 0.0224+/-0.0005 and n_s = 0.959+/-0.013.Comment: 13 pages, 8 Figures. Revised version following referee's comments. Accepted for publication in Monthly Notices of the Royal Astronomical Society. A few typos correcte

Growth of vertically aligned Si wire arrays over large areas (>1 cm^2) with Au and Cu catalysts

Arrays of vertically oriented Si wires with diameters of 1.5 µm and lengths of up to 75 µm were grown over areas >1 cm^2 by photolithographically patterning an oxide buffer layer, followed by vapor-liquid-solid growth with either Au or Cu as the growth catalyst. The pattern fidelity depended critically on the presence of the oxide layer, which prevented migration of the catalyst on the surface during annealing and in the early stages of wire growth. These arrays can be used as the absorber material in novel photovoltaic architectures and potentially in photonic crystals in which large areas are needed

Defect-Seeded Atomic Layer Deposition of Metal Oxides on the Basal Plane of 2D Layered Materials

Atomic layer deposition (ALD) on mechanically exfoliated 2D layered materials spontaneously produces network patterns of metal oxide nanoparticles in triangular and linear deposits on the basal surface. The network patterns formed under a range of ALD conditions and were independent of the orientation of the substrate in the ALD reactor. The patterns were produced on MoS2 or HOPG when either tetrakis(dimethylamido)titanium or bis(ethylcyclopentadienyl)manganese were used as precursors, suggesting that the phenomenon is general for 2D materials. Transmission electron microscopy revealed the presence, prior to deposition, of dislocation networks along the basal plane of mechanically exfoliated 2D flakes, indicating that periodical basal plane defects related to disruptions in the van der Waals stacking of layers, such as perfect line dislocations and triangular extended stacking faults networks, introduce a surface reactivity landscape that leads to the emergence of patterned deposition

A Reconnaissance Geophysical Survey of the Kawartha Lakes and Lake Simcoe, Ontario

A marine geophysical survey program has been conducted in lakes of southern Ontario. The survey was designed to detect neotectonic features, if they exist, and to evaluate their geological importance. High-resolution single- and multichannel seismic reflection profiling were used to delineate late- and post-glacial sedimentary strata and structures, as well as the sediment/bedrock interface, in the Kawartha Lakes and Lake Simcoe. Results show that two seismostratigraphic sequences are common within the unconsolidated overburden. The lower unit exhibits a parallel reflection configuration having strong reflection amplitudes, whereas the upper unit is acoustically transparent and overlies the lower unit conformably in some places and unconformably in others. Both units vary in thickness within lakes and from lake to lake. Typical subbottom profiles of Precambrian rock surfaces are rolling; those of Paleozoic rock surfaces are smooth. At one location in Lower Buckhorn Lake, tilted rock surfaces may be faulted but disturbance of overlying glacioge-nic sediments was not observed. In western Lake Simcoe and Kempenfelt Bay, slumping into graben-like features was observed. Also in Lake Simcoe, a diapiric feature was documented. It is speculated that these disturbances most likely result from glacier ice block melting and fluid migration. A tectonic origin, however, cannot be discounted at this stage of investigation. Additional systematic marine geophysical surveys are required in the future to map features in detail to determine whether they are of neotectonic or glaciotectonic origin.Le levé a été mené afin de déceler les éléments néotectoniques et d'évaluer leur importance géologique. Des profils de sismique réflexion de haute résolution ont servi à déterminer les couches et les structures sédimentaires tardi- et postglaciaires ainsi que l'interface sédiment-roche en place dans les lacs Kawartha et le lac Simcoe. Les résultats montrent qu'il y a deux séquences sismostratigraphiques communes dans la couverture de dépôts meubles. L'unité inférieure présente une configuration de réflexion parallèle avec de fortes amplitudes, alors que l'unité supérieure est transparente du point de vue acoustique et recouvre l'unité inférieure parfois en concordance, parfois en discordance. L'épaisseur des deux unités varie à l'intérieur d'un lac et d'un lac à l'autre. Les profils caractéristiques des surfaces précambriennes sont ondulés, tandis que ceux des surfaces paléozoïques sont plats. En un site du Lower Buckhorn Lake, Ia surface de roches basculées est peut être faillée, mais on n'a observé aucune perturbation dans les sédiments glaciaires sus-jacents. Dans la partie ouest du lac Simcoe et la Kempenfelt Bay, on a observé des glissements dans des formes ressemblant à des grabens. On a également relevé une forme diapirique dans le lac Simcoe. On croit que ces perturbations sont probablement le résultat de la fonte de blocs glaciaires et de la migration de fluides. À ce stade des recherches, on ne peut toutefois pas écarter une origine tectonique. On devra effectuer un levé géophysique systématique afin de cartographier toutes les formes et de déterminer leur origine néotectonique ou glaciotectonique.Ein marines geophysikalisches Vermessungsprogramm wurde in Seen von Sùdontario durchgefuhrt. Die Vermessung war angelegt, um eventuell vorhandene neotektonische Elemente zu entdecken und ihre geologische Bedeutung zu bestimmen. Seismische Reflexionsprofile einfacher oder mehrfacher Frequenz mit hoher Auflôsung wurden benutzt, um die spàt- und postglazia-len Sedimentschichten undstrukturen sowie das Interface Sediment/anstehendes Gestein in den Kawarthaseen und dem Simcoesee zu bestimmen. Die Ergebnisse zeigen, dafî es zwei gemeinsame seismos-tratigraphische Sequenzen innerhalb der nicht verfestigten Uberlastung gibt. Die untere Einheit zeigt eine Paralell-Reflektorstruktur mit starken Reflexion-sweiten, wohingegen die hôhere Einheit akustisch transparent ist und die untere Einheit an einigen Stellen gleichgelagert und an anderen ungleich gelagert bedeckt. Die Dicke der beiden Einheiten variiert innerhalb der Seen und von einem See zum anderen. Die typischen Unterbauprofile der pràkam-brischen Felsoberflachen sind wellig, die der palàozoischen Felsoberflachen glatt. An einer Stelle im unteren Buckhornsee sind die gekippten Felsoberflachen vielleicht verworfen, doch beobachtet man keine Stôrung der darùbergelagerten glaziogenen Sedimente. Im westlichen Simcoesee und der Kempenfelt Bay hat man Abrutschungen in gra-benartige Formen festgestellt. AuBerdem ist im Simcoesee eine diapire Form dokumen-tiert. Man vermutet, dafî dièse Stôrungen hôchstwahrscheinlich auf das Schmelzen von Gletschereisblôcken und flùssige Wanderungen zurùckzufùhren sind. Indessen kann in diesem Stadium der Forschung ein tektonischer Ursprung nicht ausgeschlossen werden

Data assimilation for the Martian atmosphere using MGS Thermal Emission Spectrometer observations

From the introduction: Given the quantity of data expected from current and forthcoming spacecraft missions to Mars, it is now possible to use data assimilation as a means of atmospheric analysis for the first time for a planet other than the Earth. Several groups have described plans to develop assimilation schemes for Mars [Banfield et al., 1995; Houben, 1999; Lewis and Read, 1995; Lewis et al., 1996, 1997; Zhang et al., 2001]. Data assimilation is a technique for the analysis of atmospheric observations which combines currently valid information with prior knowledge from previous observations and dynamical and physical constraints, via the use of a numerical model. Despite the number of new missions, observations of the atmosphere of Mars in the near future are still likely to be sparse when compared to those of the Earth, perhaps comprising one orbiter and a few surface stations at best at any one time. Data assimilation is useful as a means to extract the maximum information from such observations, both by a form of interpolation in space and time using model constraints and by the combination of information from different observations, e.g. temperature profiles and surface pressure measurements which may be irregularly distributed. The procedure can produce a dynamically consistent set of meteorological fields and can be used directly to test and to refine an atmospheric model against observations

Assimilation of TES data from the Mars Global Surveyor scientifc mapping phase

The Thermal Emission Spectrometer (TES)aboard Mars Global Surveyor has produced data which cover almost two Martian years so far (during its scientific mapping phase). Thermal profiles for the atmosphere below 40 km and total dust opacities can be retrieved from TES nadir spectra and assimilated into a Mars general circulation model (MGCM), by using the assimilation techniques described in detail by Lewis et al. (2002). This paper describes some preliminary results from assimilations of temperature data from the period Ls=141°- 270° corresponding to late northern summer until winter solstice on Mars. Work in progress is devoted to assimilate both temperature and total dust opacity data for the full period for which they are already available

Secondary ion mass spectrometry of vapor−liquid−solid grown, Au-catalyzed, Si wires

Knowledge of the catalyst concentration within vapor-liquid-solid (VLS) grown semiconductor wires is needed in order to assess potential limits to electrical and optical device performance imposed by the VLS growth mechanism. We report herein the use of secondary ion mass spectrometry to characterize the Au catalyst concentration within individual, VLS-grown, Si wires. For Si wires grown by chemical vapor deposition from SiCl_4 at 1000 °C, an upper limit on the bulk Au concentration was observed to be 1.7 x 10^16 atoms/cm^3, similar to the thermodynamic equilibrium concentration at the growth temperature. However, a higher concentration of Au was observed on the sidewalls of the wires