1,259 research outputs found
The Utilization of Time by Instructors of Vocational Agriculture in South Dakota
This thesis purports to investigate the utilization of time by instructions of vocational agriculture in south Dakota .How much time for instructors of vocational agriculture devote to various areas of their programs? What activities other than these directly related to vocational agriculture do instructions participate in and how much time do they devote to these activities? What effect does the manner in which instructors utilize their time have upon vocational agricultural instruction
Particle monolayer assembly in evaporating salty colloidal droplets
Ring-shaped deposits can be often found after a droplet evaporates on a
substrate. If the fluid in the droplet is a pure liquid and its contact line
remains pinned during the process, the mechanism behind such ring-shaped
deposition is the well-known coffee-stain effect. However, adding small amounts
of salt to such a droplet can change the internal flow dramatically and
consequently change the deposition mechanism. Due to an increase of surface
tension in the contact line region, a Marangoni flow arises which is directed
from the apex of the droplet towards the contact line. As a result, particles
arrive at the contact line following the liquid-air interface of the droplet.
Interestingly, the deposit is also ring-shaped, as in the classical
coffee-stain effect, but with a radically different morphology: particles form
a monolayer along the liquid-air interface of the droplet, instead of a compact
three-dimensional deposit. Using confocal microscopy, we study
particle-per-particle how the assembly of the colloidal monolayer occurs during
the evaporation of droplets for different initial concentration of sodium
chloride and initial particle dilution. Our results are compared with classical
diffusion-limited deposition models and open up an interesting scenario of
deposits via interfacial particle assembly, which can easily yield homogeneous
depositions by manipulating the initial salt and particle concentration in the
droplet.Comment: 15 pages, 12 figure
Diffusion due to the Beam-Beam Interaction and Fluctuating Fields in Hadron Colliders
Random fluctuations in the tune, beam offsets and beam size in the presence
of the beam-beam interaction are shown to lead to significant particle
diffusion and emittance growth in hadron colliders. We find that far from
resonances high frequency noise causes the most diffusion while near resonances
low frequency noise is responsible for the large emittance growth observed.
Comparison of different fluctuations shows that offset fluctuations between the
beams causes the largest diffusion for particles in the beam core.Comment: 5 pages, 3 postscript figure
Strontium and Oxygen Isotope Profiles of Sequentially Sampled Modern Bison (Bison bison bison) Teeth from Interior Alaska as Proxies of Seasonal Mobility
Studies addressing prehistoric mobility in animals typically use isotopic analyses of sequentially formed tissues, such as the growth layers in teeth, to infer physical movement on the landscape. Strontium isotope ratios (87Sr/86Sr values), which vary geographically, are particularly useful for this purpose, especially when paired with stable oxygen isotope ratios (δ18O), which vary seasonally. Together, these two isotope systems can provide information about past animal movement patterns on a seasonal scale. However, while many studies have used 87Sr/86Sr and δ18O values from analyses of sequentially formed tissues for this purpose, there have been limited analyses on modern animals of known movement patterns across high-latitude regions. In this pilot study, we sequentially sampled and analyzed one second molar (M2) and two third molars (M3) from two bison (Bison bison bison) from the Delta bison herd, which resides in interior Alaska and has known and documented seasonal mobility patterns. The resulting 87Sr/86Sr values from the teeth were compared to a high-resolution 87Sr/86Sr isoscape for the region and were paired with δ18O analyses to determine whether the seasonal 87Sr/86Sr values matched the predicted values for each of the seasonal bison habitat areas. The results indicate that the 87Sr/86Sr and δ18O values reliably reflected the known seasonal mobility patterns of bison and suggest that this approach could be used to investigate the mobility patterns of prehistoric bison in Alaska and surrounding high-latitude regions.En général, les études qui portent sur la mobilité des animaux préhistoriques se servent d’analyses isotopiques des tissus séquentiellement formés, y compris les couches de développement des dents, afin d’en déduire les mouvements physiques dans l’environnement. Les rapports isotopiques du strontium (87Sr/86Sr) sont particulièrement utiles à cette fin, car ils varient géographiquement, surtout lorsqu’ils sont jumelés avec les rapports isotopiques stables de l’oxygène (δ18O), dont la variabilité est saisonnière. Ensemble, ces deux isotopes peuvent fournir des informations sur les habitudes de déplacement des animaux dans un paysage en fonction des saisons. Cependant, même si plusieurs études ont utilisé les valeurs 87Sr/86Sr et δ18O découlant des analyses des tissus séquentiellement formés à cette fin, peu d’analyses ont été effectuées chez les animaux modernes dont les habitudes de déplacement sont connues dans les régions de haute latitude. Dans cette étude pilote, nous avons séquentiellement échantillonné et analysé une deuxième molaire (M2) et deux troisièmes molaires (M3) de deux bisons (Bison bison bison) du troupeau de bisons du delta, troupeau qui réside dans l’intérieur de l’Alaska et dont les modèles de mobilité saisonnière sont connus et documentés. Les valeurs 87Sr/86Sr obtenues à partir des dents ont été comparées à un paysage isotopique de haute résolution 87Sr/86Sr pour la région et ont été jumelées aux analyses δ18O pour déterminer si les valeurs 87Sr/86Sr saisonnières correspondaient aux valeurs prévues pour les zones d’habitat saisonnières du bison. Les résultats indiquent que les valeurs 87Sr/86Sr et δ18O reflètent fidèlement les modèles connus de mobilité saisonnière du bison, et suggèrent que cette méthode pourrait servir à étudier les modèles de mobilité des bisons préhistoriques en Alaska et dans les régions de haute latitude environnantes
Applying Rule Ensembles to the Search for Super-Symmetry at the Large Hadron Collider
In this note we give an example application of a recently presented
predictive learning method called Rule Ensembles. The application we present is
the search for super-symmetric particles at the Large Hadron Collider. In
particular, we consider the problem of separating the background coming from
top quark production from the signal of super-symmetric particles. The method
is based on an expansion of base learners, each learner being a rule, i.e. a
combination of cuts in the variable space describing signal and background.
These rules are generated from an ensemble of decision trees. One of the
results of the method is a set of rules (cuts) ordered according to their
importance, which gives useful tools for diagnosis of the model. We also
compare the method to a number of other multivariate methods, in particular
Artificial Neural Networks, the likelihood method and the recently presented
boosted decision tree method. We find better performance of Rule Ensembles in
all cases. For example for a given significance the amount of data needed to
claim SUSY discovery could be reduced by 15 % using Rule Ensembles as compared
to using a likelihood method.Comment: 24 pages, 7 figures, replaced to match version accepted for
publication in JHE
Descriptive Epidemiology of Bovine Tuberculosis in Michigan (1975–2010): Lessons Learned
Despite ongoing eradication efforts, bovine tuberculosis (BTB) remains a challenge in Michigan livestock and wildlife. The objectives of this study were to (1) review the epidemiology of BTB in Michigan cattle, privately owned cervids, and wildlife between 1975 and 2010 and (2) identify important lessons learned from the review and eradication strategies. BTB information was accessed from the Michigan BTB Eradication Project agencies. Cattle herds (49), privately owned deer herds (4), and wild white-tailed deer (668) were found infected with BTB during the review period. BTB has occurred primarily in counties located at the northern portion of the state's Lower Peninsula. Currently used BTB eradication strategies have successfully controlled BTB spread. However additional changes in BTB surveillance, prevention, and eradication strategies could improve eradication efforts
Variable- and person-centered approaches to examining construct-relevant multidimensionality in writing self-efficacy
Self-efficacy is an essential component of students’ motivation and success in writing. There have been great advancements in our theoretical understanding of writing self-efficacy over the past 40 years; however, there is a gap in how we empirically model the multidimensionality of writing self-efficacy. The purpose of the present study was to examine the multidimensionality of writing selfefficacy, and present validity evidence for the adapted Self-Efficacy for Writing Scale (SEWS) through a series of measurement model comparisons and person-centered approaches. Using a sample of 1,466 8th–10th graders, results showed that a bifactor exploratory structural equation model best represented the data, demonstrating that the SEWS exhibits both construct-relevant multidimensionality and the presence of a global theme. Using factor scores derived from this model, we conducted latent profile analysis to further establish validity of the measurement model and examine how students disaggregate into groups based on their response trends of the SEWS. Three profiles emerged, differentiated by global writing self-efficacy, with substantively varying factor differences among the profiles. Concurrent, divergent, and discriminant validity evidence was established through a series of analyses that assessed predictors and outcomes of the profiles (e.g., demographics, standardized writing assessments, and grades). Theoretical and practical implications and avenues for future research are discussed.
Supplement attached below
Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 6: Accelerator Capabilities
These reports present the results of the 2013 Community Summer Study of the
APS Division of Particles and Fields ("Snowmass 2013") on the future program of
particle physics in the U.S. Chapter 6, on Accelerator Capabilities, discusses
the future progress of accelerator technology, including issues for high-energy
hadron and lepton colliders, high-intensity beams, electron-ion colliders, and
necessary R&D for future accelerator technologies.Comment: 26 page
A Magnetic Transition Probed by the Ce Ion in Square-Lattice Antiferromagnet CeMnAsO
We examined the magnetic properties of the square-lattice antiferromagnets
CeMnAsO and LaMnAsO and their solid solutions La1-xCexMnAsO by resistivity,
magnetic susceptibility, and heat capacity measurements below room temperature.
A first-order phase transition is observed at 34.1 K, below which the
ground-state doublet of the Ce ion splits by 3.53 meV. It is likely that Mn
moments already ordered above room temperature are reoriented at the
transition, as reported for related compounds, such as NdMnAsO and PrMnSbO.
This transition generates a large internal magnetic field at the Ce site in
spite of the fact that simple Heisenberg interactions should be cancelled out
at the Ce site owing to geometrical frustration. The transition takes place at
nearly the same temperature with the substitution of La for Ce up to 90%. The
Ce moment does not undergo long-range order by itself, but is parasitically
induced at the transition, serving as a good probe for detecting the magnetism
of Mn spins in a square lattice.Comment: 11 pages, 5 figures, to be published in J. Phys. Soc. Jp
- …