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The invasive success of Polistes dominulus in North America has been attributed to its greater productivity relative to native Polistes. Liberation from parasites and parasitoids are thought to be major factors contributing to the high productivity of P. dominulus. We analyzed historical records of colony relative abundance and productivity of P. dominulus and the sympatric, native Polistes fuscatus from 1995 to 2010 using historical data from our Michigan Polistes study site. We also analyzed evidence of parasitoids from 294 P. fuscatus and 507 P. dominulus archived combs from 2001 to 2010. Additionally, we examined field and laboratory colonies from outside of our study site for parasites and parasitoids in 2009 and 2010. We documented one parasite and three parasitoids exploiting Polistes in our Michigan study sites. Our historical records document that P. dominulus initially displaced P. fuscatus rapidly, then slowed, and finally the two populations stabilized. Furthermore, the historical pattern of decreasing displacement of P. fuscatus by P. dominulus corresponded temporally with a significant decline in the productivity and a significant increase in Dibrachys cavus infestation of P. dominulus. Our evidence indicates that the parasitoid, D. cavus, is a major factor in stabilizing the populations of the sympatric P. dominulus and P. fuscatus.

Measurements of sound propagation were made in a shallow, sloping bottomed freshwater pond. The frequency responses of the pond had a highpass characteristic with a sharp cutoff frequency. Cut-off frequency of the response was inversely related to the depth of water at the shallowest transducer (either projector or receiver) and was the same whether propagating downslope or upslope (reciprocity). The relationship between cut-off frequency and depth was significantly different from that expected for propagation in a channel with either a rigid or pressure release (gas) bottom. The highpass characteristic is due to modal propagation in the ‘waveguide’, and the effect of this environmental filtering is 30–60 dB between frequencies that propagate and those that do not. Thus, the physical constraints of this shallow-water environment on acoustic communication by aquatic animals are much greater than those measured in terrestrial environments. These constraints are discussed relative to selection for b...

SUMMARY Maize seedlings have been shown to absorb more phosphorus (P) from soil from long term zero-till plots than from the same soil after disturbance, apparently because of greater vesicular-arbuscular (VA) mycorrhizal colonization in the undisturbed soil, A growth room experiment was conducted to determine the effect of soil P availability on this phenomenon. Maize was grown for three 3-week cycles in initially disturbed soil. Phosphorus was mixed with the soil to create five P-amendment rates: 0, 40, 80, 120, and 160 μg Pg−1soil. After each growth cycle, the soil in half the pots was disturbed and replanted, whereas the other half were replanted without disturbing the soil. In the third growth cycle, shoot dry weights were greater in the undisturbed soil than in the disturbed soil at the lower P-amendment rates, but soil disturbance had no effect at the 120 and 160 μg P g−1 soil amendments. Mycorrhizal colonization was much greater in the undisturbed soil at all P amendment rates. Shoot N, P, Mg, and Zn concentrations were higher in the undisturbed than in the disturbed soil at all P amendments, but only the increased P and Zn could be directly related to increased mycorrhizal colonization. While the benefit to the plant from mycorrhizal colonization induced by lack of soil disturbance can be quite large even at high rates of P amendment to the soil, the benefit achieved depends on the balance between the carbon (C) cost and P benefit to the host and may or may not favour the host.

A simple technique has been developed for the high resolution measurement of small changes in capacitors which have one grounded electrode. The capacitor is arranged to be the tuning element in a series resonant LC tank circuit that is driven by a transistor emitter follower. Signal information is provided by observing the phase shift in the transistor collector current that results from any small change in the capacitor value. Implementation is simple, readily analyzable, provides good diagnostics, is easily multiplexed into arrays, and has potential applications in a number of areas including high resolution proximity sensing, capacitive topography, atomic force microscopy, and capacitor microphones.

We found that the majority of ballistic seeds tested [N = 74 of 78 in Vicia sativa ssp. nigra (Fabaceae); N = 25 of 27 in Croton capitatus var. capitatus (Euphorbiaceae)] were projected at angles that would yield a greater distance than the average of seeds with the same initial speed projected at random angles. In addition, the median of fractional distance error (maximum distance - seed distance)/(maximum distance), of the seeds were 0.11 and 0.04 for V. sativa and C. capitatus, respectively. Seed projection distance was modeled by using initial projection angle, initial speed, and measured drag, along with other seed data. We improved upon previous such studies by using dual-angle high-speed stroboscopic photography to determine initial projection angle and speed. We also measured seed drag in a low-turbulence wind tunnel. Seed projection positions on the plant, which also affect seed projection distance, were found to be primarily from the top of the plant, with 98 of 137 and 407 of 407 fruits in the upper half of the plant for V. sativa and C. capitatus, respectively. Our findings are significant because they suggest that in addition to the ballistic projection mechanism itself, the species studied have additional adaptations that result in enhanced seed projection distance from the parent plant.

The objective of this work was to assess the feasibility of accomplishing aqueous extracts of soil samples and determining if the extracted solution induced adverse effects in the human myelomonocytic cell line, HL60. Dosing of HL60 cells was accomplished over a 24-hour period using 100% of extracted media from standard soil samples containing known contaminants. Assessments of viability, apoptosis, reduced thiols, and mitochondrial membrane integrity were accomplished by argon-ion laser flow cytometric analysis, using chemical labels specific for each end-point. The in vitro cytotoxicity data was compared with the results of Microtox and Mutatox tests as well as earthworm and plant toxicity tests. In vitro cytotoxicity tests' results exhibited good correlation with other tests' results.

St. Augustinegrass [(Stenotaphrum secundatum (Walt.) Kuntz] and bahiagrass (Paspalum notatum Flugge) are the two dominant lawn grasses maintained in Florida. Knowledge of relative drought resistance among species and cultivars is important for selecting turfgrass that will persist during drought stress. This study was designed to monitor the rooting characteristics of three St. Augustinegrass cultivars and one bahiagrass cultivar during the year following establishment. In spring 1995, sods washed free of soil were established in clear, sand-filled lysimeters. Rooting characteristics were monitored each month. After 90 days of growth, grasses were evaluated for drought tolerance by initiating a series of soil dry-down cycles. Roots of ‘Pensacola’ bahiagrass and ‘Floratam’ St. Augustinegrass reached a 60-cm depth in 90 and 180 days following sodding, respectively. ‘Palmetto’ and ‘FX-10’ St. Augustinegrass roots did not grow below 40 cm during the first 180 days following sodding. Roots of ‘FX-10’ St. Augustinegrass extended deeper than 40 cm after 240 days of growth; whereas roots of ‘Palmetto’ St. Augustinegrass never extended below 40 cm during this study. All grasses showed a general increase in root number at 20 cm within the first 180 days of growth, but at the 30-cm depth, root numbers remained relatively constant after 90 days of growth. The greatest changes in root length density (RLD) occurred during the first 150 days following sodding. ‘Floratam’ St. Augustinegrass and ‘Pensacola’ bahiagrass consistently had greater RLD in the 20- to 40-cm range compared to ‘Palmetto’ and ‘FX-IO’ St. Augustinegrasses. The number of days before wilt for ‘Pensacola’ bahiagrass, ‘FX-lO’, ‘Floratam’, and ‘Palmetto’ St. Augustinegrasses were 9.0, 6.7, 6.0 and 4.7, days respectively. The number of days to wilt was positively correlated (P=0.05; r=0.53) with root COWlt at the 30-cm depth, but it was not correlated with root count at the 20-cm depth.

This study was designed to determine the prevalence of unsuspected renal artery stenoses (RAS) in patients undergoing arteriography for evaluation of aneurysmal or occlusive vascular disease and whether symptomatic coronary artery disease (CAD) is more prevalent among patients with unsuspected RAS.We reviewed the arteriograms and medical records of 346 consecutive patients with aortic aneurysms or occlusive disease in whom RAS was unsuspected on clinical grounds.Aortography revealed unsuspected RAS (50% or greater diameter loss) in 98 patients (28%). Patients with RAS had a higher prevalence of mild, controlled hypertension (p0.001) and mild renal insufficiency (p0.001), but in no case was arteriography obtained to diagnose renovascular hypertension or ischemic nephropathy. Fifty-seven patients (58%) with unsuspected RAS had clinically overt CAD (documented myocardial infarction, positive coronary catheterization, previous coronary revascularization, ischemic electrocardiography changes, or angina pectoris), compared with 96 patients (39%) without RAS (p = 0.002). The correlation between the prevalence of CAD and RAS severity was highly significant (p0.001), and the relative odds ratio of CAD was highest for RAS measuring 75% or greater. Stepwise logistic regression analysis demonstrated three variables to be significantly and independently associated with CAD: 75% or greater RAS (p = 0.001), aortic aneurysm disease (p = 0.01), and hypertension (p = 0.001). RAS measuring 75% or greater diameter loss was associated with the highest estimated odds ratio: patients with this degree of RAS had a fourfold increase in the prevalence of clinically overt CAD. We also evaluated the relationship between RAS, mesenteric artery stenosis, and CAD; although RAS was more frequent among patients with mesenteric artery stenoses, mesenteric artery stenoses were not associated with CAD.Unsuspected RAS is common among patients with peripheral vascular disease and should be considered an independent marker for CAD.

Sputter-deposited tungsten thin films exhibit high intrinsic stress. This stress can result in both in-plane and out-of-plane distortion when the films are deposited on thin membrane structures such as x-ray masks. To minimize these distortions, intrinsic stresses in these absorber films have to be low and reproducible. Several groups have recently reported that by precisely controlling the sputter deposition conditions, W films with low stresses can be produced. However, the reproducibility is limited. We have built a novel acoustic resonance system, in which one electrode, mounted behind the mask membrane, monitors its position and simultaneously provides an electrostatic drive to keep it vibrating at its resonant frequency. For typical membranes and deposition conditions, vibrational modes in the 1–10 kHz range are observed. During tungsten deposition, sputtering pressure is varied in response to changes in the membrane resonant frequency, so that the film stress is minimized. We have made a systematic study of the microstructure and stress of W thin films using a variety of characterization techniques. We have shown the feasibility of depositing low-stress (

Dimensional measurement of surface topography with a probe microscope requires surface proximity sensing, probe position measurement, a probe with known shape, and careful analysis of the image generated. Our probe microscope contains some novel features. The proximity detector is a magnetically constrained rocking‐beam force sensor stabilized with a capacitance‐based force‐balance system. This sensor accepts a wide range of probe tips, which are fabricated separately. The probes are either focused‐ion‐beam etched metal or chemically etched optical fibers. We show measurements of features arising from semiconductor manufacture.

Profilometry of high‐aspect‐ratio, submicron lithographic features with a scanning force microscope is possible if the instrument satisfies several requirements. The probe must be slender enough to reach into narrow holes without sacrificing stability. The force sensor must follow the surface without damaging the sample or the probe. Finally, a position monitor must measure the location of the probe. With such an instrument, high‐resolution depth measurements are straightforward. Width measurements are more difficult because of the mixing of the probe shape with sidewalls, but this problem can be overcome through careful control of the probe shape. Measurements of high‐aspect ratio features with a characteristic size less than 0.5 μm will be shown, and some of the distortions caused by the probe–sample interaction will be discussed.

Frequency responses of shallow, freshwater ponds in northern Mississippi were measured. The response has a highpass characteristic with a sharp cutoff frequency due to the modal properties of the system. The cutoff frequency of the system is inversely related to the depth of water at the shallower transducer (projector or receiver). Frequencies below the first mode are nonpropagating, and the overall effect of this environment on propagation is about 50 dB. Several species of aquatic insects communicate in these shallow‐water ponds using acoustic signals, and they must contend with the physical constraints imposed by the system. Data on the calling song (long range) of a common aquatic beetle (Tropisternus collaris, Hydrophilidae) are presented and discussed in relation to the propagation characteristics of their shallow pond habitats. [Work supported by USDA.]

A serious impediment to precision metrology with scanning probe microscopes is the unreproducible, nonlinear behavior of the piezo ceramic actuators. We have developed a simple solution to the problem by measuring the position of the scanning head with capacitors. The circuit monitoring the gap between the plates has a linear response with slope 12 μm/V and noise of 0.1 nm/(Hz)1/2. The linearity of the system is verified by comparing the capacitor output with a scan of a grating that is periodic in two dimensions. We analyze the errors associated with the technique and show how to reduce them to acceptable levels.

COMBUSTION characteristics of butanol-diesel fuel blends were compared with characteristics observed using pneumatic atomizing nozzles to supply ethanol through the intake manifold. Butanol blends produced ignition delays, rapid pressure rises and higher peak pressures. Atomized ethanol did not alter these parameters through 50% by volume operation. Engine efficiency increased significantly with ethanol dual-fuel operation.

Monitoring is critical to resistance management, but there has been very little discussion in the literature about the statistical design of monitoring programs. Some general considerations show that the LD50, a standard measure for resistance monitoring, is very inefficient compared with diagnostic tests that accurately distinguish between resistant and susceptible individuals. Even with diagnostic doses, sample sizes at any given location must often be very large (on the order of hundreds of individuals per population) to reliably detect resistance when it is present at frequencies of

A microprocessor based control system was developed to control the rate of flow of alcohol supplied by an atomizing nozzle dual-fuel system. The control system, using engine speed hand control setting, actual engine speed and desired alcohol fuel percentage, controlled the flowrate of alcohol to maintain the same engine power output as would be observed with 100 percent diesel operation.

Transversal filtering consists of forming an output signal from the suitably weighted sum of successively delayed samples of a given input waveform. Although such filters exhibit many attractive features, economic considerations have previously limited their hardware implementation to rather few areas, primarily the fields of communications and radar. However, recent technological developments have significantly reduced the cost of the multiple tapped-delay operations that are required in such filters, thereby greatly expanding their potential areas of application. The purpose of the present paper is two-fold, first to serve as a general introduction to the possibilities of transversal filters for the processing of isolated randomaly distributed pulses (such as occur in experimental nuclear physics), and second to introduce a new implementation of such filters in the form of capacitively tapped delay lines. This latter form of transversal filter is readily fabricated and is well suited for operation on pulses in the few nanosecond to few microsecond time range.

This paper describes an implementation of the UNIX™ operating system for IBM System/370 computers. In this implementation an underlying Resident Supervisor, adapted from an existing IBM control program, provides machine control and multiprogramming; while a UNIX System Supervisor, adapted from the standard UNIX system kernel, provides the UNIX system environment. This implementation supports multiprocessing, paging, and large-process, virtual address spaces. Terminal handling is done through an outboard terminal processor. This paper describes the software structure, with emphasis on unique aspects of this implementation: multiprocessing and process synchronization, process creation, and outboard terminal handling. Capacity and performance of the UNIX system on large mainframes is also discussed. The first and principle user of the UNIX system for System/370 is the development project for the 5ESS™ switching system. This paper also discusses the use of a large mainframe UNIX system for this development. Included in this discussion are the reasons for selecting this system for development, applications software porting, and general experience with mainframe UNIX systems.

We have excited the 14-keV level of the Fe/sup 57/ nucleus using synchroton radiation, and observed the conversion electrons emitted in the decay of that state. We believe this to be the first observation of nuclear excitation via synchrotron-produced x rays.

A wide variety of experiments in semiconductor physics involve the observation of a particular class of time‐dependent transient signals; namely, decaying exponentials. Such signals are characteristic of systems relaxing back to equilibrium following an abrupt change in the populations of carriers occupying the available states. The magnitudes of such signals indicate the density of states involved, while the decay time constants (as a function of temperature) provide information on the energy level of the states in question. As such, both the amplitudes and the time constants of such signals are of physical interest. The problem of processing such signals has been examined using the theory of linear filtering and as a result a special purpose signal processor has been developed. This processor performs a continuous real‐time cross correlation between the experimental signals and an appropriately synchronized locally generated exponential waveform. The resulting system has been used to process signals fro...

A new pulsed nonlinearity measurement is described and applied to the characterization of thin‐film conductor stripes. The method is based on the phenomenon of ’’baseline shift’’, and is substantially simpler than the already familiar third‐harmonic method yet, at least potentially, just as sensitive. A model is proposed in which the observed nonlinearity is attributed to the temperature rise accompanying current in conductors and the associated resistance change. Good quantitative agreement has been obtained with predictions based on the model. A specific application of this method to reliability testing has been found in magnetic bubble memories, the lifetime of which correlated closely with pulse nonlinearity measurements.

Using the magneto‐optical Kerr effect, it is shown that the surface magnetization and the bulk magnetization of both polycrystalline and single‐crystal iron plates behave quite differently. In particular, a distinctive ’’lag’’ is observed in the surface magnetization, except when the single crystal is magnetized along the easy 〈100〉 direction. The surface magnetization of the single crystal is highly anisotropic. Implantation of a dose of 1015 Fe+ ions/cm2 into a polycrystalline plate causes a change in the shape of the magnetization curve.

A set of four modular building block elements have been designed for use in a variety of satellite experiments. These elements comprise an amplifier, a zero crossing discriminator, a linear gate and a pulse shaper. The circuits are constructed in hybrid form using discrete transistors and tantalum thin film resistors on ceramic substrates. This form of construction was dictated by considerations of radiation damage, component tolerances and power consumption. An attempt has been made to design the elements so that they can be used in a variety of ways. Individual examples of these applications are given in the context of a particular space experiment. This experiment involves the use of a multielement semiconductor detector telescope and employs approximately 100 of the analog building blocks. The total transistor count is approximately 500 and the power consumption is less than 1.5 watts.

Silicon p-n junction particle detectors have been fabricated by diffusing phosphorus to various depths between 0.1 and 2.0 ? into high resistivity p-type silicon. Various base material resistivities have been employed, ranging from 100 ? cms to 13,000 ? cms. Diffusions have been carried out both by the "gaseous" and the "paint-on" process. The devices produced have ranged in area from 1 mm2 to 1 cm2, with the majority of detectors having an area of ~.2 cm2. Using 5.5 mev ? particles and a 5 × 5 mm device, the best line width that has been obtained Is 20 kev. It has been found that the 1 cm2 devices give line widths of ~ 50 kev. The effect of the thickness of the n layer forming the front surface of the junction has been investigated, and it has been shown that 0.1-? diffusions give essentially "windowless" detectors. Other properties that have been examined are space charge generation of leakage current, charge collection efficiency as a function of bias and incident particle direction, and signal rise time.

In an effort to improve the energy stability and operating convenience of the Rutgers-Bell FN Tandem, a study has been made of the processes involved in the standard Van de Graaff corona stabilization system. In the light of these observations, a terminal voltage control system has been designed using error signals derived both from the slit system and the capacity pickoff plates. The system operates using either the standard slit system, or the machines' Generating Voltmeter as the terminal voltage reference, switching automatically to the G. V. system when beam is lost for any reason.

Pulsed-photocapacitance measurements prove that an oxygen center in GaP can deeply capture two electrons and also provide strong evidence that this center is the isolated O donor. Measurements of the rates of capture of electrons by O and recombination rates of electrons bound to O with holes are presented. These rates were determined using a modification of the photocapacitance method. The O donor was prepared in specific charge states, in a diode depletion layer, and the changes in the trapped charge population resulting from appropriate pulsing of the diode bias voltage were then studied by photocapacitance. In this way the capture and recombination processes of interest always occurred in neutral material. The capture cross sections for electrons at 296 K were found to be ${\ensuremath{\sigma}}_{n1}\ensuremath{\approx}2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}18}$ ${\mathrm{cm}}^{2}$, ${\ensuremath{\sigma}}_{n2}\ensuremath{\approx}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}$ ${\mathrm{cm}}^{2}$ for $n$-type material and ${\ensuremath{\sigma}}_{p1}\ensuremath{\approx}4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}$ ${\mathrm{cm}}^{2}$, ${\ensuremath{\sigma}}_{p2}g4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}$ ${\mathrm{cm}}^{2}$ for $p$ type. (The subscripts refer to the one- and two-electron states.) The lifetimes of the bound electrons in $p$-type GaP with $p=(2.5\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ are ${\ensuremath{\tau}}_{p1}\ensuremath{\approx}46$ \ensuremath{\mu}sec and ${\ensuremath{\tau}}_{p2}l5$ nsec. The second electron recombines with a hole without any Auger effect, since the first electron remains on the center. The transition rate is very fast and must be nonradiative. Both of these facts are consistent with the electron having a level just above the valence band, as found previously. Using ${\ensuremath{\sigma}}_{n1}$, a minority carrier lifetime of 13 nsec, and an O-donor density of 2.8 \ifmmode\times\else\texttimes\fi{} ${10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}13}$, the maximum O concentration reported earlier, we calculate that only about 1.5% of the recombination current is through O in $p$-type material.

The design and calibration results of a satellite based solar-cosmic ray particle identifier system utilizing a field effect transistor analog multiplier for the IMP F and G spacecraft are described. A discussion is made of the effectiveness of particle separation by such a particle identifier used in on-board data processing.