3,710 research outputs found
AgRISTARS: Foreign commodity production forecasting. The 1980 US corn and soybeans exploratory experiment
The U.S. corn and soybeans exploratory experiment is described which consisted of evaluations of two technology components of a production forecasting system: classification procedures (crop labeling and proportion estimation at the level of a sampling unit) and sampling and aggregation procedures. The results from the labeling evaluations indicate that the corn and soybeans labeling procedure works very well in the U.S. corn belt with full season (after tasseling) LANDSAT data. The procedure should be readily adaptable to corn and soybeans labeling required for subsequent exploratory experiments or pilot tests. The machine classification procedures evaluated in this experiment were not effective in improving the proportion estimates. The corn proportions produced by the machine procedures had a large bias when the bias correction was not performed. This bias was caused by the manner in which the machine procedures handled spectrally impure pixels. The simulation test indicated that the weighted aggregation procedure performed quite well. Although further work can be done to improve both the simulation tests and the aggregation procedure, the results of this test show that the procedure should serve as a useful baseline procedure in future exploratory experiments and pilot tests
Dome craters on Ganymede
Voyager observations reveal impact craters on Ganymede that are characterized by the presence of broad, high albedo, topographic domes situated within a central pit. Fifty-seven craters with central domes were identified in images covering approx. 50% of the surface. Owing to limitations in resolution, and viewing and illumination angles, the features identified are most likely a subset of dome craters. The sample appears to be sufficiently large to infer statistically meaningful trends. Dome craters appear to fall into two distinct populations on plots of the ratio of dome diameter to crater rim diameter, large-dome craters and small-dome craters. The two classes are morphologically distinct from one another. In general, large dome craters show little relief and their constituent landforms appear subdued with respect to fresh craters. The physical attributes of small-dome craters are more sharply defined, a characteristic they share with young impact craters of comparable size observed elsewhere in the solar system. Both types of dome craters exhibit central pits in which the dome is located. As it is difficult to produce domes by impact and/or erosional processes, an endogenic origin for the domes is reasonably inferred. Several hypotheses for their origin are proposed. These hypotheses are briefly reviewed
The Projection Postulate of Quantum Mechanics on the Lightcone
We discuss an interpretation of the projection postulate that implies
collapse of the wavefunction along the lightcone.Comment: 5 pages, LaTex, SJSU/TP-93-1
Personal Protective Equipment: The Never-ending Story
Now, as always, there is a huge debate about what protection is required and what Personal Protective Equipment (PPE) should be provided for personnel engaged in demining operations. Current opinion varies drastically between individual demining organizations, countries in which they operate and between governing bodies, which are coordinating the demining efforts
It\u27s Good to Be the Game Warden: State v. Boyer and the Erosion of Privacy Protection for Montana Sportsmen
State v. Boye
Laterality of Eye Use by Bottlenose (Tursiops truncatus) and Rough-toothed (Steno bredanensis) Dolphins While Viewing Predictable and Unpredictable Stimuli
Laterality of eye use has been increasingly studied in cetaceans. Research supports that many cetacean species keep prey on the right side while feeding and preferentially view unfamiliar objects with the right eye. In contrast, the left eye has been used more by calves while in close proximity to their mothers. Despite some discrepancies across and within species, laterality of eye use generally indicates functional specialization of brain hemispheres in cetaceans. The present study aimed to examine laterality of eye use in bottlenose dolphins (Tursiops truncatus) and rough-toothed dolphins (Steno bredanensis) under managed care. Subjects were video-recorded through an underwater window while viewing two different stimuli, one predictable and static and the other unpredictable and moving. Bottlenose dolphins displayed an overall right-eye preference, especially while viewing the unpredictable, moving stimulus. Rough-toothed dolphins did not display eye preference while viewing stimuli. No significant correlations between degree of laterality and behavioral interest in the stimuli were found. Only for bottlenose dolphins were the degree of laterality and curiosity ratings correlated. This study extends research on cetacean lateralization to a species not extensively examined and to stimuli that varied in movement and degree of predictability. Further research is needed to make conclusions regarding lateralization in cetaceans
Sample selection in foreign similarity regions for multicrop experiments
The selection of sample segments in the U.S. foreign similarity regions for development of proportion estimation procedures and error modeling for Argentina, Australia, Brazil, and USSR in AgRISTARS is described. Each sample was chosen to be similar in crop mix to the corresponding indicator region sample. Data sets, methods of selection, and resulting samples are discussed
Galaxy destruction and diffuse light in clusters
Deep images of the Centaurus and Coma clusters reveal two spectacular arcs of
diffuse light that stretch for over 100 kpc, yet are just a few kpc wide. At a
surface brightness of m_b \sim 27-28th arcsec^-2, the Centaurus arc is the most
striking example known of structure in the diffuse light component of a rich
galaxy cluster. We use numerical simulations to show that the Centaurus feature
can be reproduced by the tidal debris of a spiral galaxy that has been tidally
disrupted by the gravitational potential of NGC 4709. The surface brightness
and narrow dimensions of the diffuse light suggest that the disk was
co-rotating with its orbital path past pericentre. Features this prominent in
clusters will be relatively rare, although at fainter surface brightness levels
the diffuse light will reveal a wealth of structure. Deeper imaging surveys may
be able to trace this feature for several times its presently observed extent
and somewhere along the tidal debris, a fraction of the original stellar
component of the disk will remain bound, but transformed into a faint
spheroidal galaxy. It should be possible to confirm the galactic origin of the
Centaurus arc by observing planetary nebulae along its length with redshifts
close to that of NGC 4709.Comment: Replaced with version accepted by MNRAS (Dec. 1999): Added missing
reference (to pg. 4 & reference list). Section 3 shortened; removed three
figures. Now 8 pages long, with 8 figures. Low resolution images included,
high resolution version available at
http://star-www.dur.ac.uk:80/~calcaneo/cenarc.htm
Identification of senescence and death in Emiliania huxleyi and Thalassiosira pseudonana: Cell staining, chlorophyll alterations, and dimethylsulfoniopropionate (DMSP) metabolism
We measured membrane permeability, hydrolytic enzyme, and caspase-like activities using fluorescent cell stains to document changes caused by nutrient exhaustion in the coccolithophore Emiliania huxleyi and the diatom Thalassiosira pseudonana, during batch-culture nutrient limitation. We related these changes to cell death, pigment alteration, and concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) to assess the transformation of these compounds as cell physiological condition changes. E. huxleyi persisted for 1 month in stationary phase; in contrast, T. pseudonana cells rapidly declined within 10 d of nutrient depletion. T. pseudonana progressively lost membrane integrity and the ability to metabolize 5-chloromethylfluorescein diacetate (CMFDA; hydrolytic activity), whereas E. huxleyi developed two distinct CMFDA populations and retained membrane integrity (SYTOX Green). Caspase-like activity appeared higher in E. huxleyi than in T. pseudonana during the post-growth phase, despite a lack of apparent mortality and cell lysis. Photosynthetic pigment degradation and transformation occurred in both species after growth; chlorophyll a (Chl a) degradation was characterized by an increase in the ratio of methoxy Chl a : Chl a in T. pseudonana but not in E. huxleyi, and the increase in this ratio preceded loss of membrane integrity. Total DMSP declined in T. pseudonana during cell death and DMS increased. In contrast, and in the absence of cell death, total DMSP and DMS increased in E. huxleyi. Our data show a novel chlorophyll alteration product associated with T. pseudonana death, suggesting a promising approach to discriminate nonviable cells in nature
Facilitating research-informed educational practice for inclusion. Survey findings from 147 teachers and school leaders in England
This paper considers the engagement by teachers and school leaders in England in
educational practices that are both ‘research-informed’ and supportive of inclusive
education. We do so by seeking to understand the benefits, costs, and signifying factors
these educators associate with research-use. In undertaking the study, we first worked
to develop and refine a survey instrument (the ’Research-Use BCS survey’) that could be
used to uniquely and simultaneously measure these concepts. Our survey development
involved a comprehensive process that comprised: (1) a review of recent literature; (2)
item pre-testing; and (3) cognitive interviews. We then administered this questionnaire to
a representative sample of English educators. Although response rates were somewhat
impacted by the recent COVID-19 pandemic, we achieved a sufficient number of
responses (147 in total) to allow us to engage in descriptive analyses, as well as the
production of classification trees. Our analysis resulted in several key findings, including
that: (1) if respondents see the benefits of research, they are likely to use it (with the
converse also true); (2) if educators have the needed support of their colleagues, they are
more likely to use research; and (3) perceiving research-use as an activity that successful
teachers and schools engage in is also associated with individual-level research use. We
conclude the paper by pointing to potential interventions and strategies that might serve
(at least, in the English context) to enhance research-use, so increasing the likelihood of
the development and use of effective inclusive practices in schools
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