8,302 research outputs found
A Review of the Interstate Park, Wisconsin Bison Find
In the fall of 1936, members of a C.C.C. Company engaged in excavating a ditch, uncovered the partial remains of several extinct bison in Interstate Park in Northwestern Wisconsin, about 40 miles northeast of St. Paul. The site, located in Polk County and known locally as Mountain Meadow, was a former peat bog situated in an area of drift deposited by the Grantsburg sublobe of the Keewatin ice sheet. The drift has been mapped as Mankato. The find was reported immediately to Dr. Alonzo Pond, an archeologist formerly of Beloit College, who at the time was connected with the National Park Service. Recognizing the possible importance of the discovery, Dr. Pond established an archeological dig under very difficult field conditions. The site was subject to an inflow of water which required the use of hip boots and pumps. Approximately 300 odd bones were discovered at a depth of three to four feet in the peat and close to the bottom of the bog. Three artifacts were also uncovered during the excavation. Unfortunately, they were discovered and removed during Dr. Pond\u27s absence and against his standing orders, apparently to save them from abnormal floodwater conditions
Honey bee collected pollen: forage species importance and levels of neonicotinoid contamination
Ibex lowensis, First Evidence of Fossil Goat in North America
One of the problems dealing with the migration of Quaternary Bovid stocks from Eurasia to North America via the Bering Straits, is the extreme fragmentary nature of the fossil record. A number of the dozen or so genera now recognized have been established on the basis of single fragmentary specimens. Many times these consist of isolated bone fragments such as horncores, partial crania, dentitions and even less diagnostic elements of the axial skeleton. As recently as 193 7 species of two genera mw to the North American continent were identified from Alaskan deposits on the basis of similar fragmentary remains ( l) . It is with considerable interest, therefore, that the occurrence of a member of the goat group (genus Capra), previously unknown to the American scene, is described from the Quaternary of Iowa. The specimen in question, represented by a partial cranium with horncores, appears to be that of a fossil Ibex
Photocurrent response from vertically aligned single-walled carbon nanotube arrays
Vertically-aligned arrays of single walled carbon nanotubes were created on an optically transparent electrode (FTO glass) these arrays were found to exhibit a prompt current and voltage when exposed to light. These cells were then investigated by electrochemical impedance spectroscopy and found to exhibit a dampening of the recombination reaction over the first 24 hours. Symmetrical cell modeling was successful in simulating the behavior of normal cell architecture
On the Spatial Distribution of Stellar Populations in the Large Magellanic Cloud
We measure the angular correlation function of stars in a region of the Large
Magellanic Cloud (LMC) that spans 2 degrees by 1.5 degrees. We find that the
correlation functions of stellar populations are represented well by
exponential functions of the angular separation for separations between 2 and
40 arcmin (corresponding to ~ 30 pc and 550 pc for an LMC distance of 50 kpc).
The inner boundary is set by the presence of distinct, highly correlated
structures, which are the more familiar stellar clusters, and the outer
boundary is set by the observed region's size and the presence of two principal
centers of star formation within the region. We also find that the
normalization and scale length of the correlation function changes
systematically with the mean age of the stellar population. The existence of
positive correlation at large separations (~300 pc), even in the youngest
population, argues for large-scale hierarchical structure in current star
formation. The evolution of the angular correlation toward lower normalizations
and longer scale lengths with stellar age argues for the dispersion of stars
with time. We show that a simple, stochastic, self-propagating star formation
model is qualitatively consistent with this behavior of the correlation
function.Comment: 30 pages, 13 Figures. Scheduled for publication in AJ in June 199
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A UK survey exploring the assistant practitioner role across diagnostic imaging: current practice, relationships and challenges to progression
YesObjective: Skill mix has been established as one method
of maintaining imaging service delivery, with vertical and
horizontal substitution of roles and tasks. Assistant practitioners
(APs) have been undertaking limited imaging
practice for almost two decades, but there remains a
paucity of evidence related to the impact of their roles.
Methods: This article reports on an electronic survey of
individual APs within the NHS in the UK to explore utilisation,
role scope and aspirations.
Results: Responses were analysed from APs (n = 193)
employed in 97 different organisations across the UK.
The majority work in general radiography or mammography,
with very few responses from other imaging
modalities. Training routes varied across modalities,
with most achieving Band 4 under Agenda for Change
on completion of education. Limitations on practice
vary between organisations and modalities, with many
reporting blurring of the radiographer-AP boundary.
Many aspire to continue their training to achieve registrant
radiographer status, although there were clear
frustrations from respondents over the lack of overt
career prospects.
Conclusion: Integration of the role into imaging department
practice does not appear to be universal or
consistent and further research is required to examine
the optimal skill mix composition.
Advances in knowledge: Skill mix implementation is
inconsistent across modalities and geography in the
UK. Opportunities for further workforce utilisation and
expansion are evident
Assistant radiographer practitioners: Creating capacity or challenging professional boundaries?
YesIntroduction
Over the last 2 decades the assistant radiographer practitioner (ARP) role has been introduced into NHS diagnostic imaging departments as a strategy to expand the workforce and create capacity. This skill mix initiative has not been implemented in a standardised way and there is limited knowledge of the current role scope within general radiography (X-Ray).
Method
An electronic survey of ARPs working within UK diagnostic imaging departments was conducted. Both open and closed questions sought information regarding basic demographic data (age category; gender; geographic region), scope of practice (patient groups; anatomical regions; imaging outside of the diagnostic imaging department), limitations placed on practice, supervision and additional roles.
Results
A total of 108 responses, including 13 trainees, were received. Most sites employ three or less ARPs in general radiography (n = 43/66; 65.2%), although 11 sites have five (range 1–15). The majority undertake imaging of both adults and children (n = 85/108; 78.7%), although limitations on age were described. Their scope of practice covers a broad anatomical range and included some non-ambulant patients. The level of supervision varied with some sites empowering ARPs to check the referral prior to examination (n = 25) or images post acquisition (n = 32) (both n = 20/66; χ2 = 16.003; 1df; p = 0.000).
Conclusion
ARPs are helping to maintain capacity in imaging departments but we suggest there is further scope for expansion. The practice described by the post holders suggests that many are working beyond the scope envisaged by the radiography professional body
Transient Gamma Ray Spectrometer Measurements of Gamma-Ray Lines from Novae. II. Constraining the Galactic Nova Rate from a Survey of the Southern Sky during 1995-1997
The good energy resolution (3--4 keV FWHM) of the Transient Gamma Ray
Spectrometer (TGRS) on board the WIND spacecraft makes it sensitive to
Doppler-shifted outbursts of 511 keV electron-positron annihilation radiation,
the reason being that the Doppler shift causes the cosmic line to be slightly
offset from a strong instrumental background 511 keV line at rest, which is
ubiquitous in space environments. Such a cosmic line (blueshifted) is predicted
to arise in classical novae due to the annihilation of positrons from
-decay on a timescale of a few hours in an expanding envelope. A further
advantage of TGRS - its broad field of view, containing the entire southern
ecliptic hemisphere - has enabled us to make a virtually complete and unbiased
3-year search for classical novae at distances up to ~1 kpc. We present
negative results of this search, and estimate its implications for the
highly-uncertain Galactic classical nova rate and for future space missions.Comment: 22 pp. + 3 fig
Order induced by dipolar interactions in a geometrically frustrated antiferromagnet
We study the classical Heisenberg model for spins on a pyrochlore lattice
interacting via long range dipole-dipole forces and nearest neighbor exchange.
Antiferromagnetic exchange alone is known not to induce ordering in this
system. We analyze low temperature order resulting from the combined
interactions, both by using a mean-field approach and by examining the energy
cost of fluctuations about an ordered state. We discuss behavior as a function
of the ratio of the dipolar and exchange interaction strengths and find two
types of ordered phase. We relate our results to the recent experimental work
and reproduce and extend the theoretical calculations on the pyrochlore
compound, GdTiO, by Raju \textit{et al.}, Phys. Rev. B {\bf 59},
14489 (1999).Comment: 5 pages, 5 figures, AMSLaTe
Transient Gamma Ray Spectrometer Measurements of Gamma-Ray Lines from Novae. I. Limits on the Positron Annihilation Line in Five Individual Novae
The Transient Gamma Ray Spectrometer (TGRS) on board the WIND spacecraft has
spent most of the interval 1995-1997 in a high-altitude orbit where gamma-ray
backgrounds are low. Its high-resolution Ge spectrometer is thus able to detect
weak lines which are slightly offset from stronger background features. One
such line is predicted from nucleosynthesis in classical novae, where
beta-decays on a time-scale of a few hours in an expanding envelope produce
positrons that annihilate to generate a line which is blueshifted by a few keV
away from the background annihilation line at 511 keV. The broad TGRS field of
view contained five known Galactic novae during 1995 January - 1997 June, and
we have searched the spectra taken around the times of these events for the
blueshifted nova annihilation line. Although no definite detections were made,
the method is shown to be sensitive enough to detect novae occurring on
ONeMg-rich white dwarfs out to about 2.5 kpc.Comment: 27 pp. + 10 figs., or offprint mailed by request to
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