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Pasture and livestock essentials
Get PDFConcise information on the basics of pasture and livestock management, including use of sound conservation practices. Particularly for the region east of the Cascade Mountains. Companion audio files describe:
audio1: Pasture Management. Ways to avoid overgrazing and balance the number of animals with available forage.
audio2: Pasture Fertility. Keep pastures and their soil healthy with soil testing, nutrients, reseeding, and weed control.
audio3: Livestock Management. Tips on weight control, shelter, and water access to keep your livestock healthy.Keywords: weeds in pasture, pasture fertility, livestock weight, water for livestock, pasture seeding, shade and shelter for livestock, pasture grazingPublished December 2010. Reviewed February 2015. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Agroforestry : a land use integration system
Get PDFPublished October 2009. Reviewed December 2013. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalogKeywords: whole farm diversification, land use, forest farming, silvopasture, riparian forest buffers, agroforestry, alley cropping, windbreak
Image processing of multiphase images obtained via X-ray microtomography: A review
Get PDFEasier access to X-ray microtomography (lCT) facilities has provided much new insight from high-resolution imaging for various problems in porous media research. Pore space analysis with respect to functional properties usually requires segmentation of the intensity data into different classes. Image segmentation
is a nontrivial problem that may have a profound impact on all subsequent image analyses. This
review deals with two issues that are neglected in most of the recent studies on image segmentation: (i)
focus on multiclass segmentation and (ii) detailed descriptions as to why a specific method may fail
together with strategies for preventing the failure by applying suitable image enhancement prior to segmentation.
In this way, the presented algorithms become very robust and are less prone to operator bias.
Three different test images are examined: a synthetic image with ground-truth information, a synchrotron
image of precision beads with three different fluids residing in the pore space, and a lCT image of a soil
sample containing macropores, rocks, organic matter, and the soil matrix. Image blur is identified as the
major cause for poor segmentation results. Other impairments of the raw data like noise, ring artifacts, and
intensity variation can be removed with current image enhancement methods. Bayesian Markov random
field segmentation, watershed segmentation, and converging active contours are well suited for multiclass
segmentation, yet with different success to correct for partial volume effects and conserve small image features
simultaneously.Keywords: X-ray tomography, Soil structure, Multiphase flow, Segmentation, structure analysis, Image processin
High-field terahertz response of graphene
Get PDFWe investigate the response of multi-layer epitaxial graphene and chemical vapor deposition (CVD)-grown single-layer graphene to strong terahertz (THz) fields. Contrary to theoretical predictions of strong nonlinear response, the transmitted fields exhibit no harmonic generation, indicating that the nonlinear response is limited by fast electron thermalization due to carrier-carrier scattering. The fast electron heating gives rise to large THz transmission enhancement (>15%) in single-layer CVD graphene at high THz fields (E-THz > 10 kV cm⁻¹). The nonlinear effects exhibit non-Drude behavior in the THz conductivity, where THz fields induce extreme non-equilibrium electron distributions.Keywords: Spectroscopy, Generation, Gas, Transistor
Radiochlorine exchange reactions with sulfuryl chloride
Get PDFAs part of a continuing study of sulfur containing non-aqueous
solvents, the present investigation was undertaken in an effort to obtain
a better understanding of the solvent sulfuryl chloride. The
primary object of the investigation involved a study of the rate of
radiochlorine exchange between sulfuryl and thionyl chloride in mixtures
of the two, the radioisotopic tracer chlorine-36 being used.
The principal motivation for such experiments rested in the hope of
being able to find some evidence relative to the possible significance
of an ionic dissociation process for sulfuryl chloride. The system
was of particular interest in presenting analogies to at least two
related types of systems previously studied, namely the thionyl
chloride-thionyl bromide system (where rapid radiosulfur exchange
was observed) and the thionyl chloride-sulfur monochloride system
(where negligible radiochlorine exchange occurred). The system
was further of interest in the light of the previous observation of a
rapid chlorine exchange between sulfuryl chloride and the solute
pyridinium chloride (in chloroform solution). Another point of
some pertinence related to the fact that earlier research had shown
that, between these two substances, little if any radiosulfur exchange
occurred, and the suggestion had been made that a rapid radiochlorine
exchange might result if the two substances interacted in an acid-base
type of ionization equilibrium, thionyl chloride acting as a basic,
chloride ion donor.
It was found in this work that radiochlorine exchange between
thionyl chloride and sulfuryl chloride was, at best, very slow, with
an exchange half time, t1/2, of at least 35 days or more. The rate of
the exchange did not appear to vary greatly, at least in apparent order
of magnitude, over the concentration range from a five fold excess of
sulfuryl chloride to a two fold excess of thionyl chloride, the value
of the order of magnitude at 25°C being 10⁻¹ g-atoms 1⁻¹day⁻¹. The
obtaining of precise rate data was, however, hampered both by the
extreme slowness of the reaction and by the considerable difficulty in
a clean cut reactant separation at the end of each experiment, a
factor which resulted in a large and rather irreproducible apparent
zero time exchange.
A single experiment was done investigating the radiochloride
exchange between sulfuryl chloride and the initially labeled solute tetramethylammonium chloride. Despite incomplete solution of the
salt in the solvent, 84% exchange occurred in the time of the experiment
(14.75 hours). It appears most likely that, if solution had been
complete, exchange would also have been complete within the period
of the experiment, and in all probability in a far shorter time, probably
less than an hour.
The results are taken to imply that sulfuryl chloride neither
undergoes any significant chloride ion dissociation, nor any acid-base ionic interaction with thionyl chloride. They further suggest
that exchange of the solvent with ionic chloride solutes probably
occurs via either a rapid association equilibrium or a bimolecular
equilibrium. The results demonstrate the hazard of a too indiscriminate
application of the solvent systems interpretation of chemical
phenomena in non-aqueous systems. Many processes can be better
understood in less restricted terms, Lewis acid-base concepts, for
example, being particularly useful. Further investigations of sulfuryl
chloride exchange reactions, particularly with other basic and
some acidic solutes appear most inviting
The biologies of two dipterous predators of Dendroctonus pseudotsugae Hopkins (Coleoptera : Scolytdae) in western Oregon and Washington
Get PDFThe objectives of this study were: 1) to learn the life history and habits of Medetera aldrichii Wheeler and a Lonchaea sp. in association with the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, in western Oregon and Washington; 2) to determine if the larvae of M. aldrichii were predaceous on the Douglas-fir beetle; and 3) to determine the effect of elevation and exposure on the emergence of M. aldrichii. Seasonal histories of M. aldrichii and the Lonchaea sp. in association with the Douglas-fir beetle in western Oregon and. Washington are presented. M. aldrichii was found to have only one generation per year while the Lonchaea sp. had one and a partial second generation. Third-instar larvae of M. aldrichii killed larvae and . pupae of the Douglas-fir beetle in the laboratory, but they would not kill adults, Third-instar larvae of the Lonchaea sp. would not kill any of the stages of the Douglas-fir beetle. The second instar of M. aldrichii is described for the first time, and all the immature stages of the Lonchaea sp. are described. Larval instars of M. aldrichii as well as the Lonchaea sp. may be separated by measuring the lengths of their cephalo-pharyngeal skeletons, which almost doubled with each succeeding instar. Emergence dates of M. aldrichii were affected by the elevation of infested trees as well as their degree of exposure to direct radiation, In an emergence study utilizing three field cages, emergence began first on May 23, 1963, in a field cage exposed to direct radiation at an elevation of 1400 feet, progressed to an unexposed cage at the same elevation, and commenced last on September 19 in an unexposed cage at an elevation of 2000 feet
Ecology and reproductive biology of Tonicella lineata (Wood, 1815) (Mollusca - Polyplacophora)
No full textAlong the central and southern Oregon coast and on San Juan Island, Washington, the lined chiton Tonicella lineata is very abundant in the lower intertidal levels on rocky shores. It is usually found on
encrusting coralline algae which, with epiphytic diatoms, make up the major portion of its diet. On the central and southern Oregon coast, T. lineata are closely associated with the purple urchin Strongylocentrotus purpuratus and are often found in the burrow of the urchin. This association, together with algal cover, protects T. lineata from desiccation during periods of tidal exposure, whereas on San Juan Island the lack of an intertidal urchin reduces the diversity of habitats available to Tonicella. The asteroids Pisaster ochraceous and Leptasterias hexactis are the most common predators of T. lineata. The average growth in length of twelve T. lineata
studied for ten and one-half months was 0.40 cm (range 0.88 to 0.06 cm) with great variation among animals 2.0 to 3.0 cm in body length. Some T. lineata exhibit a homing behavior. The reproductive cycle was studied by determination of a monthly gonad index and examination of gonad histology. In 1968 and 1969 Tonicella lineata showed a distinct annual reproductive cycle along the central Oregon coast, spawning between 1 April and 15 April in 1968 and during the middle of April in 1969. Southern Oregon coast data is inconclusive, but spawning in 1968 and 1969 probably occurred In February or March. In 1968 and 1969 spawning took place during May and June on San Juan Island. Tonicella lineata thus shows a latitudinal difference in the timing of its annual reproductive cycle. Histological examination of the gonads revealed a close correlation of gamete buildup and release with gonad index changes. Gamete production starts immediately after spawning. The gonads of T. lineata do not go through a resting period as has beenobserved for those of the chitons Katharina tunicata, Mopalia
hindsii and Cryptochiton stelleri. Comparison of gonad index and histological data with sea surface temperature data shows that gametogenic activity increases while the water temperatures are dropping.
Spawning behavior is described and data are presented which suggest that there may be a correlation between the time of spawning and the lunar phase. The development of Tonicella lineata is described from the time of fertilization through metamorphosis. The features described follow closely those which have been described for other chitons
except for the description of previously unnoted structures on the pretrochal region of the trochophore larva. In laboratory cultures the development of the trochophore stops between 110 and 160 hours post-fertilization, depending upon the temperature. Further development will take place only when the larvae are presented with the proper settling substrate of encrusting coralline algae. In substrate
choice experiments, T. lineata larvae settle only on encrusting coralline algae and on pieces of tile previously soaked in an encrusting coralline algae extract. After settling, the trochophore larvae go through a drastic metamorphosis within twelve hours, losing the apical tuft and prototroch, taking on the shape of a small chiton, and developing seven shell plates. When 30 days old the young chitons have a fully developed
radula and feed on encrusting coralline algae
Effects of estuarine circulation patterns and stress on the migratory behavior of juvenile salmonids (Oncorhynchus sp.)
Get PDFFor the first objective of this thesis, we attempt to understand the role of water flow and directionality in determining steelhead (Oncorhynchus mykiss) and spring/summer and fall Chinook (O. tschawytscha) migration patterns within the Columbia River Estuary and plume by integrating recent advances in biotelemetry and environmental observation and forecasting systems (EOFS). The underlying methodology included analysis of the spatial and temporal movements of juvenile outmigrant salmonids with hydrological data from the CORIE modeling system (http://www.ccalmr.ogi.edu/CORIE). The CORIE modeling system, an EOFS for the Columbia River and nearshore environment, integrates a real-time sensor network, data management system and advanced 3-dimensional numerical models. Numerical simulations of key physical variables (water level, velocities, and directionality) were generated for the precise time and location that individual juvenile salmonids implanted with radio transmitters were present in the Columbia River Estuary. Five general behavioral trends were evident from these simulations: i) passive movement (drifting) during ebb tides, ii) active swimming with the current during ebb tides, iii) active swimming against the current during flood tides, iv) active swimming cross current during flood tides, and v) passive drifting during flood tide. Direction of water flow had a significant effect on fish velocity. All fish types showed a positive relationship between fish velocity and simulated drifter velocity with outgoing water flow. During slack water flow (< 0.25 m/s), this relationship was only observed in barged fall Chinook. With incoming water flow, spring/summer and fall Chinook fish types showed no relationship, whereas steelhead did. Analysis over a three-year period suggested that data from the CORIE modeling system corresponded well with juvenile salmonid migratory behavior and that the model may be a useful tool for evaluating the impact of different hydrological regimes on fish movement.
The secondary objective of this thesis evaluated the effects of both acute and chronic crowding stressors on the migratory behavior of hatchery reared juvenile steelhead released into Abernathy Creek, a tributary of the Columbia River Estuary, Washington. The acute stress treatment consisted of surgical implantation of a NanoTag radio transmitter (Lotek Wireless, Canada), followed by 6 hours of crowding immediately prior to release. The chronic stress treatment consisted of surgical implantation of a PIT-tag (Digital Angel Corporation), 36 days of acclimation, followed by 3 weeks of crowding in low water conditions prior to release. Short-term migratory success of steelhead that received the acute stress treatment was determined by radio telemetry. Numbers of migrating fish that received experimental stress treatments and their speed was determined by both mobile radio telemetry and stationary PIT-tag and radio-tag interrogation systems already established on Abernathy Creek. Acute and chronic stress treatments both significantly delayed migration by 2 to 10 days, respectively, compared to controls. Furthermore, the acute stress treatment significantly decreased the both the rate of migration and numbers of juvenile steelhead that successfully migrated out of Abernathy creek.Keywords: model, migration, salmon, behavio
Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape
Get PDFFire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare.
Consequently, long-term effects of fire on soils are often hypothesized from
short-term effects. In a chronosequence study, I studied 24 western Cascades
(Oregon) forest stands thought to have been initiated in fire. Twelve of those
burned about 150 years ago (“young” sites), and the other 12 burned an
average of 550 years ago (“old” sites). I hypothesized that young stands would
have less carbon (C) and nitrogen (N) in forest floor and in 0 -10 cm mineral
soil than old stands. I found that forest floor N pools of old sites (average =
1,823 kg/ha ± s.e. = 132 kg/ha) were significantly greater than young sites
(1,450 ± 98 kg/ha). Similarly, forest floor C pools of old sites (62,980 ± 5,403
kg/ha) were significantly greater than young sites (49,032 ± 2,965 kg/ha).
Greater N and C pools in forest floor of old sites resulted from greater forest
floor mass in old sites; concentrations of both N and C, and C:N ratios, did not
differ significantly by forest age class. In mineral soil, neither concentrations
nor pools of N and C differed between young and old sites. Despite overall
similarity of C:N ratios in young versus old sites, potential N mineralization
rates were twice as high in forest floor of old sites (average = 60 ± 7.3 mg N /
g soil) than young sites (26 ± 3.5 mg N / g soil), . Nitrate accounted for only
2% or less of total N mineralized in forest floor samples. In mineral soil,
potential net N mineralization did not differ by forest age class. The pattern of
high net N mineralization and low nitrification in old forests is consistent with
other studies of fire-prone forests, yet contrasts with many studies of forests
that lack fire, and suggests that ammonium is not the sole control over
nitrification in fire-prone ecosystems. Overall, fire appears to impart a longterm
legacy of reduced forest floor N and C pools in this western Oregon
Cascades landscape, which suggests that current fire-suppression activities in
the region may increase forest floor N and C storage over historical conditions
within several centuries. The differences in forest floor and soil N cycling
processes that I observed by forest age class raise the further possibility that
fire exclusion in these forests may change the relative abundance of soil
inorganic N forms to favor ammonium over nitrate. Such changes may have
unknown consequences for relative competitive abilities of plant and microbial
species that rely preferentially on different N-forms to meet N nutrition
requirements.
While forest floor N and C pools increase from young to old stands, forest floor
and soil N and C pools are not different, or decline, between 450 year old
stands and the oldest stands at 800+ years, That, and other, anomalous
changes in values from ~450 to 800+ years, suggest possible changes in
ecosystem functions, and may indicate that this landscape could be a fruitful
study area for examinations of a mature, steady-state ecosystemKeywords: succession, nitrification, biogeochemistry, soils, nitrogen, N mineralization, carbon, forest fire, old-growt
Comparison of time-domain and frequency-domain phase noise analyses
Get PDFThis thesis presents a comparison of time-domain and frequency-domain algorithms for phase noise calculation in oscillators. Floquet theory provides the mathematical foundation for these calculations and the numerical methods employ perturbation projection vectors (PPVs). The PPVs are an estimate of an oscillator's sensitivity to noise.
The in-house circuit simulator SPICE3 has been extended to phase noise analysis based on both the time-domain and frequency-domain periodic steadystate analyses. These analysis methods have been evaluated on a wide suite of test oscillators. A detailed comparison of these methods is carried out in terms of
accuracy and computation costs. The SPICE3 version with PPV calculation and phase noise analysis is a powerful tool for design of noise tolerant oscillators.Keywords: phase noise, oscillator