Ku-band radar threshold analysis

The statistics of the CFAR threshold for the Ku-band radar was determined. Exact analytical results were developed for both the mean and standard deviations in the designated search mode. The mean value is compared to the results of a previously reported simulation. The analytical results are more optimistic than the simulation results, for which no explanation is offered. The normalized standard deviation is shown to be very sensitive to signal-to-noise ratio and very insensitive to the noise correlation present in the range gates of the designated search mode. The substantial variation in the CFAR threshold is dominant at large values of SNR where the normalized standard deviation is greater than 0.3. Whether or not this significantly affects the resulting probability of detection is a matter which deserves additional attention

Probing confined phonon modes by transport through a nanowire double quantum dot

Strong radial confinement in semiconductor nanowires leads to modified electronic and phononic energy spectra. We analyze the current response to the interplay between quantum confinement effects of the electron and phonon systems in a gate-defined double quantum dot in a semiconductor nanowire. We show that current spectroscopy of inelastic transitions between the two quantum dots can be used as an experimental probe of the confined phonon environment. The resulting discrete peak structure in the measurements is explained by theoretical modeling of the confined phonon mode spectrum, where the piezoelectric coupling is of crucial importance.Comment: 4 pages, 4 figures; final versio

Maintaining efficiency while integrating entrants from lower-performing groups: an experimental study

Efficiently growing a group or firm often requires integration of individuals from lower-performing entities. We explore the effectiveness of two policies intended to facilitate such integration, using a laboratory experiment that models production as a coordination game with Pareto-ranked equilibria. We initially create an efficient group and an inefficient one. We then allow individuals to move into the high-performing group and vary by treatment whether movement is unrestricted, limited to one entrant per period, or subject to an entry exam. We include two additional treatments that combine the two restrictions in different ways to help understand why the institutions are effective in maintaining coordination. We find that both restrictions work to maintain efficient coordination but they are effective for different reasons.Growth, entry, coordination, experiments

THE IMPACT OF POPULATION GROWTH ON RESIDENTIAL PROPERTY TAXES

A multivariate model of the effect of population on local fiscal behavior, assessed value of property and average single family home values is estimated using cross-sectional data from Oregon. Regression results suggest that property tax levies are unit elastic with respect to population, that the total assessed value of property increases less than proportionally with population, and that the average value of a single family home increases with population. These results imply a positive relationship between population and both property tax rates and the tax bill of the average single family homeowner. Ceteris paribus, increases in average residential property taxes are associated with increases in population.Public Economics,

Observations of High Frequency, Long Range Acoustic Propagation in a Harbor Environment

The positioning and navigation of AUV\u27s in harbor environments using underwater acoustics is complicated by shallow waters, long propagation distances, and complex oceanographic features. This paper reports on high frequency (40 kHz) acoustic measurements made in Portsmouth Harbor, NH, USA, which is an estuary containing several riverine inputs and a strong tidal flow (2+ knots). A one-way propagation experiment was conducted at the mouth of the harbor for propagation distances up to 100 water depths. Strong signatures of a variety of phenomenon were observed in the acoustic signal levels, including tidal heights and currents, turbulent mixing, and wind/wave action. The relative importance of each of these will be discussed in terms of signal to noise level and the associated constraints on acoustic positioning systems

Integral representations combining ladders and crossed-ladders

We use the worldline formalism to derive integral representations for three classes of amplitudes in scalar field theory: (i) the scalar propagator exchanging N momenta with a scalar background field (ii) the "half-ladder" with N rungs in x - space (iii) the four-point ladder with N rungs in x - space as well as in (off-shell) momentum space. In each case we give a compact expression combining the N! Feynman diagrams contributing to the amplitude. As our main application, we reconsider the well-known case of two massive scalars interacting through the exchange of a massless scalar. Applying asymptotic estimates and a saddle-point approximation to the N-rung ladder plus crossed ladder diagrams, we derive a semi-analytic approximation formula for the lowest bound state mass in this model.Comment: 39 pages, 10 pdf figure