614 research outputs found
Demonstration of Sex Pheromones in \u3ci\u3eMolanna Uniophila\u3c/i\u3e (Trichoptera: Molannidae), \u3ci\u3ePlatycentropus Radiatus, Pycnopsyche Indiana, and P. Subfasciata\u3c/i\u3e (Trichoptera: Limnephilidae), With an Assessment of Interspecific Attraction Between Four Sympatric \u3ci\u3ePycnopsyche\u3c/i\u3e Species
Evidence for sex pheromones in the caddisflies Molanna uniophila Vorhies, Platycentropus radiatus (Say), Pycnopsyche indiana (Ross), and P. subfasciata (Say) is presented here for the first time based on field studies conducted in southern Michigan. For all species, numbers of males caught in pheromone traps baited with conspecific female extracts were higher than those caught in traps with male extracts, or those without extract. Four sympatric species of Pycnopsyche: P. guttifer (Walker), P. indiana, P. lepida (Hagen), and P. subfasciata exhibited no interspecific pheromonal attraction despite a common mating season and, in the case of P. indiana and P. lepida, very similar genitalic morphology. Our results suggest the importance of pheromones in maintaining reproductive isolation between closely related species. Likewise, pheromone biology can help delineate morphologically cryptic species
The pioneer projects: Economical exploration of the solar system
The interplanetary Pioneer missions are reviewed in terms of management implications and cost control. The responsibilities, organizational structure, and management practices of the Pioneer Projects are presented. The lines of authority and areas of responsibility of the principal organizational elements supporting the Pioneer missions are identified, and the methods employed for maintaining effective and timely interactions among these elements are indicated. The technical and administrative functions of the various organizational elements of the Pioneer Project Office at Ames Research Center are described in terms of their management responsibilities and interactions with other elements of the Project Office and with external organizations having Pioneer Project responsibilities. The management and control of activities prior to and during the hardware procurement phase are described to indicate the basis for obtaining visibility of the technical progress, utilization of resources, and cost performance of the contractors and other institutions supporting the Pioneer projects
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Removing Infragravity-Wave-Induced Noise from Ocean-Bottom Seismographs (OBS) Data Deployed Offshore of Taiwan
Vertical ocean-bottom seismograph (OBS) data at frequencies below 0.05 Hz are contaminated by noise induced by infragravity waves. We constructed the transfer function between pressure and velocity data from OBSs deployed in Taiwan waters to remove the wave pressure-induced noise from seismic recordings. Data were analyzed from five portable broadband OBSs deployed each for 10 months at water depths from 1740 to 4600 m and from a cabled, shallow-buried seismograph (EOS1) installed on the seafloor at 300 m depth. Removing long-period noise from these OBS data improves the identification of teleseismic phases such as P, S, SS, Pdiff , and PKIKP that are otherwise ambiguous or unidentifiable. For EOS1, infragravity-wave signals completely mask the P and S waveforms in the 10â50 s period band suitable for centroid moment tensor (CMT) solutions for most of the local events. Application of the transfer functions to predict and remove wave deformation yielded clean prominent P and S waveforms at these periods and aided in the CMT determination for small events jointly with land stations. The relative amplitudes of the wave-number-normalized transfer function for some of the OBSs are mostly determined by the thickness of the sediment at the OBS site
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High-Resolution Seafloor Absolute Pressure Gauge Measurements Using a Better Counting Method
Vibrating quartz force transducers are the critical component of most deep-sea pressure and depth gauges in use in oceanography, producing a frequency output that varies with pressure. Accurate and low drift pressure measurements can be obtained by precisely measuring this frequency. In most imple- mentations, the frequency is determined by counting the number of cycles of a high-frequency standard oscillator occurring during a large number of cycles of the lower-frequency quartz force oscillator. Res- olution is limited by the sampling interval (length of counting) and the frequency of the frequency stan- dard. Alternative counting methods can provide significant (20â40 dB) improvements in resolution at sampling rates above 1 Hz. Each counting method can be described as a different filter applied to the output of a counter of the frequency standard gated at each transition of the transducer quartz oscillator. Improvements in resolution can be understood as the result of minimizing the aliasing of higher-frequency counting noise into the spectrum below the Nyquist frequency. A simple multipole infinite impulse re- sponse (IIR) filter designed to limit spectral leakage of high-frequency noise minimizes the noise spectrum and thereby optimizes the resolution of the pressure output. The resultant noise spectrum rises as fre- quency squared above 1 Hz, independent of the sampling rate. At frequencies below 1 Hz, it is limited by noise in the electronics driving the force transducer quartz oscillator. Resolution increases with frequency of the frequency standard up to about 200 MHz, plateauing for higher frequencies due to other noise sources (likely electronic)
Demonstration of Sex Pheromones in \u3ci\u3eMolanna Uniophila\u3c/i\u3e (Trichoptera: Molannidae), \u3ci\u3ePlatycentropus Radiatus, Pycnopsyche Indiana, and P. Subfasciata\u3c/i\u3e (Trichoptera: Limnephilidae), With an Assessment of Interspecific Attraction Between Four Sympatric \u3ci\u3ePycnopsyche\u3c/i\u3e Species
Evidence for sex pheromones in the caddisflies Molanna uniophila Vorhies, Platycentropus radiatus (Say), Pycnopsyche indiana (Ross), and P. subfasciata (Say) is presented here for the first time based on field studies conducted in southern Michigan. For all species, numbers of males caught in pheromone traps baited with conspecific female extracts were higher than those caught in traps with male extracts, or those without extract. Four sympatric species of Pycnopsyche: P. guttifer (Walker), P. indiana, P. lepida (Hagen), and P. subfasciata exhibited no interspecific pheromonal attraction despite a common mating season and, in the case of P. indiana and P. lepida, very similar genitalic morphology. Our results suggest the importance of pheromones in maintaining reproductive isolation between closely related species. Likewise, pheromone biology can help delineate morphologically cryptic species
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Determining the orientations of ocean bottom seismometers using ambient noise correlation
The cross-correlation of multicomponent ambient seismic noise can reveal both the velocity and polarization of surface waves propagating between pairs of stations. We explore this property to develop a novel method for determining the horizontal orientation of ocean bottom seismometers (OBS) by analyzing the polarization of Rayleigh waves retrieved from ambient noise cross-correlation. We demonstrate that the sensor orientations can be estimated through maximizing the correlation between the radial-vertical component and the phase-shifted vertical-vertical component of the empirical Green's tensor. We apply this new method to the ELSC (Eastern Lau Spreading Center) OBS experiment data set and illustrate its robustness by comparing the obtained orientations with results from a conventional method utilizing teleseismic P and Rayleigh wave polarizations. When applied to a large OBS array, the ambient noise method provides a larger number of orientation estimates and better azimuthal coverage than typically is possible with traditional methods
The effect of local wind on seismic noise near 1 Hz at the MELT site and in Iceland
The mantle electromagnetic and tomography (MELT) experiment on the
east Pacific rise near 17°S was the first large teleseismic experiment on a midocean
ridge. During the six-month deployment, no compressional arrivals were well recorded
above 0.5 Hz. In comparison, the ICEMELT experiment in Iceland recorded
compressional arrivals at 1-2 Hz from about 2 earthquakes per month. We compare
noise spectra from the two experiments and show that this difference in detection is
at least in part a result of noise. Near 1 Hz, seismic noise in the oceans is produced
locally by wind-generated waves. At both experiment sites, 1-Hz noise levels are
well correlated with local sea-surface-wind speeds derived from satellite observations.
For a given wind speed, 1-Hz noise levels are about 10-20 dB lower in Iceland.
At the MELT site, cross-correlations of wind speed with the logarithm of noise in a
narrow-frequency band yield correlation coefficients exceeding 0.7 at frequencies
between 0.4 Hz and 2 Hz. Noise levels at 1 Hz increase with wind by 1.3-1.4 dB
per m/sec for wind speeds less than 10 m/sec. For the ICEMELT experiment, high
correlation coefficients extend to markedly higher frequencies for coastal stations,
and there is a 10-dB drop in 1-Hz noise levels 100-km inland. Noise levels increase
by about 0.8 dB per m/sec. The strong correlation between wind speed and l-Hz
seismic noise provides justification for using satellite wind speed data to search for
locations on the global spreading system where there is a better probability of recording
high-frequency arrivals. The calmest sites are found on the northern east
Pacific rise, near the equator in all oceans, and near 34 ° N and 22 ° S on the mid-
Atlantic ridge.This study was supported by the National Science Foundation
under grant OCE-9414299.Peer Reviewe
Radiotelemetry systems for measuring body temperature
End of Project ReportThe objective of this study was to compare three methods of measuring body
temperature in the bovine and examine their relationship with ambient temperature.
The three methods used were (a) rumen bolus (b) tympanic logger and (c) rectal
Post Eruption inflation of the East Pacific Rise at 9°50ⲠN
In June 2008, we installed a geodetic network at 9°50ⲠN on the East Pacific Rise to track the longâterm movement of magma following the 2005/6 eruption. This network consists of 10 concrete benchmarks stretching from the ridge to 9 km offâaxis. During three campaignâstyle surveys, measurements of vertical seafloor motions were made at each of these benchmarks by precisely recording ambient seawater pressure as a proxy for seafloor depth with a mobile pressure recorder (MPR). The MPR was deployed using the manned submersible Alvin in 2008 and 2009 and the remotely operated vehicle Jason in 2011. The MPR observations are supplemented with data from a multiyear deployment of continuously recording bottom pressure recorders (BPRs) extending along this segment of the ridge that can record rapid changes in seafloor depth from seafloor eruptions and/or dike intrusions. These measurements show no diking events and up to 12 cm of volcanic inflation that occurred from December 2009 to October 2011 in the area of the 2005/6 eruption. These observations are fit with an inflating point source at a depth of 2.7 km and volume change of 2.3 Ă 106 m3/yr located on the ridge axis at approximately 9°51.166ⲠN, 407 m from our northernmost benchmark, suggesting that the magma chamber underlying this segment of the ridge is being recharged from a deeper source at a rate that is about half the longâterm inflation rate observed at Axial Seamount on the Juan de Fuca Ridge. These data represent the second location that active volcanic uplift has been measured on a midâocean ridge segment, and the first on a nonhotspot influenced segment
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