Exploiting Spectral Leakage for Spectrogram Frequency Super-resolution

The spectrogram is a classical DSP tool used to view signals in both time and frequency. Unfortunately, the Heisenberg Uncertainty Principal limits our ability to use them for detecting and measuring narrowband signal modulation in wideband environments. On a spectrogram, instantaneous frequency can only be measured to the nearest bin without additional interpolation. This work presents a novel technique for extracting higher accuracy frequency estimates. Whereas most practitioners seek to suppress spectral leakage, we use mismatched windows to exploit such artifacts in order to produce super-resolved spectral displays. We present a derivation of our methodology and exhibit several interesting examples.Comment: Presented at the 2013 Asilomar Conference on Signals, Systems & Computer

Nesting Behavior, Ecology, Seasonal and Geographic Distribution of the Sand Wasp, Stictiella emarginata (Hymenoptera: Sphecidae)

The nesting behavior and ecology of Stictiella emarginata are documented for the first time based on field studies made mainly at Canadian Forces Base Borden, Simcoe County, Ontario. Type of soil, natural community, temporary closure, mound leveling, orientation flight, prey transport, nest structure and dimensions, and kind and number of prey per cell are defined. Museum and field collection records support a geographic bridge from northern Michigan to the Atlantic Coast and dispel the previously held notion of a disjunct distribution for this species. A late June-July-early August flight season is inferred from observations and collections made in Ontario, New York and Michigan. The nesting behavior and ecology of S. emarginata and several other Stictiella species from the western United States, Mexico and Florida are compared

Chaotic Loss Cones, Black Hole Fueling and the M-Sigma Relation

In classical loss cone theory, stars are supplied to a central black hole via gravitational scattering onto low angular momentum orbits. Higher feeding rates are possible if the gravitational potential near the black hole is non-axisymmetric and the orbits are chaotic. Motivated by recently published, self-consistent models, we evaluate rates of stellar capture and disruption in triaxial nuclei. Rates are found to substantially exceed those in collisionally-resupplied loss cones, as long as an appreciable fraction of the orbits are centrophilic. The mass captured by a black hole after a given time in a steep nucleus scales as the fifth power of the velocity dispersion, and the accumulated mass in 10^10 yr is of the correct order to reproduce the M-sigma relation. Triaxiality can solve the "final parsec problem" of decaying black hole binaries by increasing the flux of stars into the binary's loss cone.Comment: 29 pages, 6 figure

The regulation of oxygen to low concentrations in marine oxygen-minimum zones

The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygen in its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in the global ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California, as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in the Eastern Tropical North Pacific. We show here that biological controls on oxygen consumption are required to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise, only small changes in physical mixing or rates of primary production would drive the OMZ between anoxic and oxic states with potentially large swings in oxygen concentration. We propose that two controls are active: an oxygen-dependent control on oxygen respiration and an oxygen inhibition of denitrification. These controls, working alone and together, can generate low-oxygen concentrations over a wide variability in ocean mixing parameters. More broadly, we discuss the oxygen regulation of organic matter cycling and N2 production in OMZ settings. Modern biogeochemical models of nitrogen and oxygen cycling in OMZ settings do contain some of the parameterizations that we explore here. However, these models have not been applied to understanding the persistence of low, but measurable, concentrations of oxygen in settings like the Bay of Bengal, nor have they been applied to understanding what biological/physical processes control the transition from a weakly oxygenated state to a “functionally” anoxic state with implications for nitrogen cycling. Therefore, we believe that the approach here illuminates the relationship between oxygen and the biogeochemical cycling of carbon and nitrogen in settings like the Bay of Bengal. Furthermore, we believe that our results could further inform large-scale ocean models seeking to explore how global warming might influence the spread of low-oxygen waters, influencing the cycles of oxygen, carbon, and nitrogen in OMZ settings

Outlook and appraisal [June 1988]

The growth of the Scottish economy is now moving into line with the rest of the UK. Industrial production is buoyant. The growth of demand is becoming more broadly based between domestic and external sectors. Yet, construction output still remains relatively depressed, and in a significant number of other industries the ratio of Scottish to UK output remains below that of 1980. As yet there is little indication of the favourable changes in unemployment and vacancies during 1987 being reflected in the most recent employment data. But short-term prospects are more favourable than for several years, while growth forecasts for the medium term compare favourably with those for the UK as a whole

The Scottish economy [June 1988]

With the delay in the publication of this quarter's Commentary it should be borne in mind that responses to both the Scottish Chamber's Business Survey (SCBS) and CBI surveys now refer to developments of two months ago. Accordingly, responses do not take account of, or could reasonably be assumed to have anticipated, the recent increases in nominal interest rates and the depreciation of sterling

The British economy [June 1988]

The rate of growth of output in the British economy appears to be slowing down in line with earlier expectations for 1988. The rate of growth of domestic demand remains strong. Manufacturing investment is forecast to rise to record levels during 1988 and there is little evidence that the growth in consumer demand is slackening. The slow-down in the rate of growth is therefore largely a reflection of decline in the external demand for exports and buoyant import growth. The progressive upward movement of sterling in recent months and the evidence of increasing inflationary pressure, has placed the Government in a significant policy dilemma. Recent events are a clear illustration that interest rate policy cannot be used both to target the exchange rate and to regulate the expansion of domestic money and credit