11,854 research outputs found
Controlled Environment Agriculture: A Pilot Project
The controlled-environment agricultural (CEA)
project discussed in this report was first conceived for
the Wildwood Air Force Station in Kenai, Alaska, in
1972. The region contained high unemployment and a
U.S. Air Force Station that had just closed. The Kenai
Native Association, Inc. (KNA), was to take possession
of the Air Force Station through land transfers associated
with the Alaska Native Claims Settlement Act,
and this corporation was interested in expanding
business and employment opportunities for local
people. The University of Alaska Agricultural Experiment
Station (AES) contacted KNA to determine if it
had a facility which might be adaptable for use in a
research and development program in controlled-
1
environment agriculture. It was determined that such
a facility was available. Subsequently, AES and KNA
contacted the General Electric Company (GE) in
Syracuse, New York, to determine its interest in such a
project. GE had extensive background in lighting technology
and environmental control systems and the
engineering capability to develop a total system for
CEA production. It was agreed that GE would provide
technological expertise and AES would provide horticultural
and economic expertise for the growing and
marketing of a variety of salad crops. KNA would
manage the project, employ the nontechnical people,
and provide the building.
The Wildwood site was selected because it contained
two buildings which were thought to be well
suited for CEA production. One building would provide
sufficient inside space for a 1/4-acre pilot production
plant, nine small research modules , a laboratory ,
offices, a training area, and space for preparing the
crop for shipping. A second building near the first
contained three diesel generators which were to be
converted to natural gas to provide power for the
production facility.The Controlled Environment Agriculture Project
at Wildwood Village, Kenai, Alaska, spanned a period
of five years. During that time, three agencies: Kenai
Native Association, Inc.; General Electric Company;
and University of Alaska Agricultural Experiment Station
, were responsible for the management, research,
and production activities. Many persons from these
agencies who participated in all phases of the project
are acknowledged for their participation and support.
This report summarizes work began in 1972 and
concluded in 1977 on controlled-environment agriculture
in facilities located at Wildwood Village, Kenai,
Alaska, managed by the Kenai Native Association , Inc.
The authors wish to express their appreciation to
all those who have participated in the preparation of
this bulletin. Particular acknowledgment is given to:
Dr. Gerald Carlson, U.S .D.A., Beltsville, Maryland; Dr.
Donald Dinkel, University of Alaska, Agricultural
Experiment Station; Dr. Delbert Hemphill, Oregon
State University ; John Monfor, Kenai Native Association,
Inc.; Dr. Eion Scott, General Electric Company;
and Dr. Norman Whittlesey, Washington State University,
who thoroughly reviewed the contract document
Periodicities In The X-Ray Intensity Variations of TV Columbae: An Intermediate Polar
We present results from a temporal analysis of the longest and the most
sensitive X-ray observations of TV Columbae--an intermediate polar. The
observations were carried out with the RXTE PCA, ROSAT PSPC, and ASCA. Data
were analyzed using a 1-dimensional CLEAN and Bayesian algorithms. The presence
of a nearly sinusoidal modulation due to the spin of the white dwarf is seen
clearly in all the data, confirming the previous reports based on the EXOSAT
data. An improved period of 1909.7+/-2.5s is derived for the spin from the RXTE
data.The binary period of 5.5hr is detected unambiguously in X-rays for the
first time. Several side-bands due to the interaction of these periods are
observed in the power spectra, thereby suggesting contributions from both the
disk-fed and the stream-fed accretion for TV Col. The accretion disk could
perhaps be precessing as side-bands due to the influence of 4 day period on the
orbital period are seen. The presence of a significant power at certain
side-bands of the spin frequency indicates that the emission poles are
asymmetrically located. The strong power at the orbital side-bands seen in both
the RXTE and ROSAT data gives an indication for an absorption site fixed in the
orbital frame. Both the spin and the binary modulation are found to be
energy-dependent. Increased hardness ratio during a broad dip in the intensity
at binary phase of 0.75--1.0 confirms the presence of a strong attenuation due
to additional absorbers probably from an impact site of the accretion stream
with the disk or magnetosphere. Hardness ratio variations and the energy
dependent modulation depth during the spin modulation can be explained by
partially covered absorbers in the path of X-ray emission region in the
accretion stream.Comment: 34 pages, including 12 figures, Accepted for publication in
Astronomical Journal, scheduled for January 2004 issue (vol. 127
Nanoscale Torsional Resonator for Polarization and Spectroscopy of Nuclear Spins
We propose a torsional resonator that couples to the transverse spin dipole of an attached sample. The absence of relative motion eliminates a source of friction that would otherwise hinder nanoscale implementation. Enhanced spontaneous emission induced by the resonator relaxes the longitudinal spin dipole at a rate of ~1 s^(-1) in the low-temperature limit. With signal averaging, single-proton magnetic resonance spectroscopy appears feasible at ~10 mK and a high magnetic field, while single-shot sensitivity is practical for samples with at least tens of protons in a volume of ~5 nm^3
Evidence for polar jets as precursors of polar plume formation
Observations from the Hinode/XRT telescope and STEREO/SECCHI/EUVI are
utilized to study polar coronal jets and plumes. The study focuses on the
temporal evolution of both structures and their relationship. The data sample,
spanning April 7-8 2007, shows that over 90% of the 28 observed jet events are
associated with polar plumes. EUV images (STEREO/SECCHI) show plume haze rising
from the location of approximately 70% of the polar X-ray (Hinode/XRT) and EUV
jets, with the plume haze appearing minutes to hours after the jet was
observed. The remaining jets occurred in areas where plume material previously
existed causing a brightness enhancement of the latter after the jet event.
Short-lived, jet-like events and small transient bright points are seen (one at
a time) at different locations within the base of pre-existing long-lived
plumes. X-ray images also show instances (at least two events) of
collimated-thin jets rapidly evolving into significantly wider plume-like
structures that are followed by the delayed appearance of plume haze in the
EUV. These observations provide evidence that X-ray jets are precursors of
polar plumes, and in some cases cause brightenings of plumes. Possible
mechanisms to explain the observed jet and plume relationship are discussed.Comment: 10 pages, 4 figures, accepted as APJ Lette
Matrix Adhesion Polarizes Heart Progenitor Induction In The Invertebrate Chordate Ciona Intestinalis
Cell-matrix adhesion strongly influences developmental signaling. Resulting impacts on cell migration and tissue morphogenesis are well characterized. However, the in vivo impact of adhesion on fate induction remains ambiguous. Here, we employ the invertebrate chordate Ciona intestinalis to delineate an essential in vivo role for matrix adhesion in heart progenitor induction. In Ciona pre-cardiac founder cells, invasion of the underlying epidermis promotes localized induction of the heart progenitor lineage. We found that these epidermal invasions are associated with matrix adhesion along the pre-cardiac cell/epidermal boundary. Through targeted manipulations of RAP GTPase activity, we were able to manipulate pre-cardiac cell-matrix adhesion. Targeted disruption of pre-cardiac cell-matrix adhesion blocked heart progenitor induction. Conversely, increased matrix adhesion generated expanded induction. We were also able to selectively restore cell-matrix adhesion and heart progenitor induction through targeted expression of Ci-Integrin β2. These results indicate that matrix adhesion functions as a necessary and sufficient extrinsic cue for regional heart progenitor induction. Furthermore, time-lapse imaging suggests that cytokinesis acts as an intrinsic temporal regulator of heart progenitor adhesion and induction. Our findings highlight a potentially conserved role for matrix adhesion in early steps of vertebrate heart progenitor specification
On the spectral shift and the time delay of light in a Rindler accelerated frame
We discuss two effects predicted by the general theory of relativity in the
context of Rindler accelerated observers: the gravitational spectral shift and
the time delay of light. We show that these effects also appear in a Rindler
frame in the absence of gravitational field, in accordance with the Einstein's
equivalence principle.Comment: 12 pages, 3 figure
An Observation of the Intermediate Polar XY Arietis with Chandra
Chandra serendipitously observed the eclipsing (80 deg < i < 84 deg)
intermediate polar, XY Arietis (=H0253+193), in two separate but continuous
observations five weeks apart. XY Ari was in a quiescent state during both
observations. We pursue the study of phase-resolved spectra for this system
focusing on the Fe K lines. From the combined and separate data sets, we
readily detect emission lines of iron near 6.4, 6.7, and 6.9 keV at better than
99% significance in contrast to previous results. We confirm the orbit-phased
sinusoidal absorption column behavior first observed with Ginga as well as a
sinusoid-like behavior as a function of spin phase. The presence of the 6.4,
6.7, and 6.9 keV lines requires different ionization states with xi <2 (6.4
keV) and xi \sim$3.5-4 (6.7 and 6.9 keV) that must vary with phase. We also
detect emission lines at 3.25, 4.8, and 5.4 keV that are not instrumental in
origin. The 4.8 keV line may be identified as Ca XIX (4.832 keV) and the 3.25
keV line may be Ar I K, but the 5.4 keV line has no obvious identification.Comment: 17 pages, 8 figs, accepted AJ, scheduled Septembe
Newtonian Counterparts of Spin 2 Massless Discontinuities
Massive spin 2 theories in flat or cosmological () backgrounds
are subject to discontinuities as the masses tend to zero. We show and explain
physically why their Newtonian limits do not inherit this behaviour. On the
other hand, conventional ``Newtonian cosmology'', where is a
constant source of the potential, displays discontinuities: e.g. for any finite
range, can be totally removed.Comment: 6 pages, amplifies the ``Newtonian cosmology'' analysis. To appear as
a Class. Quantum Grav. Lette
In My Dreamy Panama
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