14,540 research outputs found
Bromegrass in Alaska. I.Winter Survival and Forage Productivity of Bromus Species, Types, and Cultivars as Related to Latitudinal Adaptation
This report summarizes seven separate field experiments,
conducted over more than two decades at
the University of Alaska’s Matanuska Research Farm,
that compared strains within three bromegrass (Bromus)
species for winter hardiness and forage production.
Species were (a) smooth bromegrass (B. inermis Leyss.),
(b) native Alaskan pumpelly bromegrass (B.
pumpellianus Scribn.), and (c) meadow bromegrass (B.
biebersteinii Roem. and Schult.), a species native to
southwestern Asia
Relationship of Latitude-of-Origin to Winter Survival and to Forage and Seed Yields of Wheatgrass (Agropyron species) in Subarctic Alaska
Five field experiments evaluating and comparing
numerous grasses were conducted over seven years at
the Matanuska Research Farm (61.6°N) near Palmer in
southcentral Alaska. Grasses were 34 strains within 14
species of wheatgrass (Agropyron) derived from various
geographic areas spanning 32 degrees of latitude;
also included were the intergeneric hybrid Agroelymus
palmerensis Lepage, Siberian wildrye (Elymus sibiricus
L.), two bromegrass (Bromus) cultivars, and one timothy
(Phleum pratense L.) cultivar. They were grown in
broadcast-seeded plots for forage (two cuts per year),
in drilled rows for seed production, and as individual
plants in rows for winter-survival determinations
Towards the improvement of self-service systems via emotional virtual agents
Affective computing and emotional agents have been found to have a positive effect on human-computer interactions. In order to develop an acceptable emotional agent for use in a self-service interaction, two stages of research were identified and carried out; the first to determine which facial expressions are present in such an interaction and the second to determine which emotional agent behaviours are perceived as appropriate during a problematic self-service shopping task. In the first stage, facial expressions associated with negative affect were found to occur during self-service shopping interactions, indicating that facial expression detection is suitable for detecting negative affective states during self-service interactions. In the second stage, user perceptions of the emotional facial expressions displayed by an emotional agent during a problematic self-service interaction were gathered. Overall, the expression of disgust was found to be perceived as inappropriate while emotionally neutral behaviour was perceived as appropriate, however gender differences suggested that females perceived surprise as inappropriate. Results suggest that agents should change their behaviour and appearance based on user characteristics such as gender
Day-to-day Variability of Stuttering
Variability has long been known to be a primary feature of the disorder of stuttering (Bloodstein & Bernstein Ratner, 2008; Costello & Ingham, 1984; Yaruss, 1997a, 1997b). Many factors that affect variability have been investigated (Brown, 1937; Johnson & Brown, 1935; Quarrington, Conway, & Siegel, 1962) yet the typical range of variability experienced by speakers remains unknown. This study will examine the speech of six adult speakers in three spontaneous speaking situations and two reading tasks. The frequency, duration, and types of stuttered events that occur on the tasks will be compared within and between speakers. The focus will be on describing variability in stuttering frequency and duration within speakers and attempting to detect consistent patterns between speakers
Amplification of Fluctuations in a Spinor Bose Einstein Condensate
Dynamical instabilities due to spin-mixing collisions in a Rb F=1
spinor Bose-Einstein condensate are used as an amplifier of quantum spin
fluctuations. We demonstrate the spectrum of this amplifier to be tunable, in
quantitative agreement with mean-field calculations. We quantify the
microscopic spin fluctuations of the initially paramagnetic condensate by
applying this amplifier and measuring the resulting macroscopic magnetization.
The magnitude of these fluctuations is consistent with predictions of a
beyond-mean-field theory. The spinor-condensate-based spin amplifier is thus
shown to be nearly quantum-limited at a gain as high as 30 dB
Periodic spin textures in a degenerate F=1 Rb spinor Bose gas
We report on the spin textures produced by cooling unmagnetized Rb F=1
spinor gases into the regime of quantum degeneracy. At low temperatures,
magnetized textures form that break translational symmetry and display
short-range periodic magnetic order characterized by one- or two-dimensional
spatial modulations with wavelengths much smaller than the extent of the
quasi-two-dimensional degenerate gas. Spin textures produced upon cooling spin
mixtures with a non-zero initial magnetic quadrupole moment also show
ferromagnetic order that, at low temperature, coexists with the spatially
modulated structure.Comment: 6 pages, revised substantially following reviewer comments and
further analysi
Spontaneously modulated spin textures in a dipolar spinor Bose-Einstein condensate
Helical spin textures in a Rb F=1 spinor Bose-Einstein condensate are
found to decay spontaneously toward a spatially modulated structure of spin
domains. This evolution is ascribed to magnetic dipolar interactions that
energetically favor the short-wavelength domains over the long-wavelength spin
helix. This is confirmed by eliminating the dipolar interactions by a sequence
of rf pulses and observing a suppression of the formation of the short-range
domains. This study confirms the significance of magnetic dipole interactions
in degenerate Rb F=1 spinor gases
Aquaculture and marketing of the Florida Bay Scallop in Crystal River, Florida
The overall goal of this study was to develop a new fishery resource product through open-water
aquaculture for the west coast of Florida that would compete as a non-traditional product through market
development. Specific objectives were as follows:
I. To grow a minimum of 50, 000 juvenile scallops to a minimum market size of40 mm in a cage
and float system in the off-shore waters of Crystal River, Florida.
2. To determine the growth rate, survival, and time to market size for the individuals in this system
and area to other similar projects like Virginia.
3. To introduce local fishermen and the aquaculture students at Crystal River High School to the
hatchery, nursery, and grow-out techniques.
4. To determine the economic and financial characteristics of bay scallop culture in Florida and
assess the sensitivity of projected costs and earnings to changes in key technical, managerial, and
market related parameters.
5. To determine the market acceptability and necessary marketing strategy for whole bay scallop
product in Florida. (PDF has 99 pages.
A Flattened Protostellar Envelope in Absorption around L1157
Deep Spitzer IRAC images of L1157 reveal many of the details of the outflow
and the circumstellar environment of this Class 0 protostar. In IRAC band 4, 8
microns, there is a flattened structure seen in absorption against the
background emission. The structure is perpendicular to the outflow and is
extended to a diameter of 2 arcminutes. This structure is the first clear
detection of a flattened circumstellar envelope or pseudo-disk around a Class 0
protostar. Such a flattened morphology is an expected outcome for many collapse
theories that include magnetic fields or rotation. We construct an extinction
model for a power-law density profile, but we do not constrain the density
power-law index.Comment: ApJL accepte
High-Resolution Magnetometry with a Spinor Bose-Einstein Condensate
We demonstrate a precision magnetic microscope based on direct imaging of the
Larmor precession of a Rb spinor Bose-Einstein condensate. This
magnetometer attains a field sensitivity of 8.3 pT/Hz over a
measurement area of 120 m, an improvement over the low-frequency field
sensitivity of modern SQUID magnetometers. The corresponding atom shot-noise
limited sensitivity is estimated to be 0.15 pT/Hz for unity duty cycle
measurement. The achieved phase sensitivity is close to the atom shot-noise
limit suggesting possibilities of spatially resolved spin-squeezed
magnetometry. This magnetometer marks a significant application of degenerate
atomic gases to metrology
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