3,092 research outputs found
Comparison of The Kois Dento-Facial Analyzer System with an Earbow for Mounting a Maxillary Cast
Statement of problem: The Kois Dento-Facial Analyzer System (KDFA) is used by clinicians to mount maxillary casts and evaluate and treat patients. Limited information is available for understanding whether the KDFA should be considered as an alternative to an earbow.
Purpose: The purpose of this study was to evaluate maxillary casts mounted using the KDFA with casts mounted using Panadent\u27s Pana-Mount Facebow (PMF). Both articulation methods were compared against a lateral cephalometric radiograph.
Material and methods: Fifteen dried human skulls were used. Lateral cephalometric radiographs and 2 maxillary impressions were made of each skull. One cast from each skull was mounted on an articulator by means of the KDFA and the other by using the PMF. A standardized photograph of each articulation was made, and the distance from the articular center to the incisal edge position and the occlusal plane angle were measured. The distance from condylar center to the incisal edge and the occlusal plane angle were measured from cephalometric radiographs. Finally, the 3-dimensional position of each articulation was determined with a Panadent CPI-III. A randomized complete block design analysis of variance (RCBD) and post hoc tests (Tukey-Kramer HSD) (α=.05) were used to evaluate the occlusal plane angle and axis-central incisor distance. A paired 2-sample t test for means (α=.05) was used to compare the X, Y, and Z distance at the right and left condyle.
Results: The KDFA and PMF mounted the maxillary cast in a position that was not statistically different from the skull when comparing the occlusal plane angle (P=.165). Both the KDFA and the PMF located the maxillary central incisor edge position in a significantly different position compared with the skull (P=.001) but were not significantly different from each other. The 3-dimensional location of the maxillary casts varied at the condyles by approximately 9 to 10.3 mm.
Conclusion: The KDFA mounted the maxillary cast in a position that was not statistically different from the PMF when comparing the incisal edge position and the occlusal plane angle. Both the KDFA and the PMF located the maxillary incisal edge position in a significantly different position compared with the anatomic position on dried human skulls
Context-Dependent Memory under Stressful Conditions: The Case of Skydiving
Two experiments examined the effect of differing levels of emotional arousal on learning and memory for words in matching and mismatching contexts. In Experiment 1, experienced skydivers learned words either in the air or on the ground and recalled them in the same context or in the other context. Experiment 2 replicated the stimuli and design of the first experiment except that participants were shown a skydiving video in lieu of skydiving. Recall was poor in air-learning conditions with actual skydiving, but when lists were learned on land, recall was higher in the matching context than in the mismatching context. In the skydiving video experiment, recall was higher in matching learn-recall contexts regardless of the situation in which learning occurred. We propose that under extremely emotionally arousing circumstances, environmental and/or mood cues are unlikely to become encoded or linked to newly acquired information and thus cannot serve as cues to retrieval. Results can be applied to understanding variations in context-dependent memory in occupations (e.g., police, military special operations, and Special Weapons and Tactics teams) in which the worker experiences considerable emotional stress while learning or recalling new information
A model of actors and grey failures
Existing models for the analysis of concurrent processes tend to focus on
fail-stop failures, where processes are either working or permanently stopped,
and their state (working/stopped) is known. In fact, systems are often affected
by grey failures: failures that are latent, possibly transient, and may affect
the system in subtle ways that later lead to major issues (such as crashes,
limited availability, overload). We introduce a model of actor-based systems
with grey failures, based on two interlinked layers: an actor model, given as
an asynchronous process calculus with discrete time, and a failure model that
represents failure patterns to inject in the system. Our failure model captures
not only fail-stop node and link failures, but also grey failures (e.g.,
partial, transient). We give a behavioural equivalence relation based on weak
barbed bisimulation to compare systems on the basis of their ability to recover
from failures, and on this basis we define some desirable properties of
reliable systems. By doing so, we reduce the problem of checking reliability
properties of systems to the problem of checking bisimulation
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Mobile Device Use Among Rural, Low-Income Families and the Feasibility of an App to Encourage Preschoolers' Physical Activity: Qualitative Study.
BackgroundAs mobile devices are becoming ubiquitous, technology-based interventions provide a promising strategy to positively influence health behaviors of families with young children. However, questions remain about the feasibility and acceptability of intervention delivery via mobile apps in low-income, rural settings and among families with preschoolers.ObjectiveThe aims of this study were to understand the content and context of mobile device use for preschoolers; explore parent beliefs on this topic, including the acceptability of intervention delivery via mobile devices; and test a prototype of an app to encourage preschoolers' physical activity with both parents and children.MethodsParents (n=29) were recruited from 5 preschool centers in eastern, rural Colorado to complete a semistructured telephone interview regarding preschoolers' mobile device use. A second sample of parents (n=31) was recruited from the same preschool centers to view the app prototype independently and provide feedback. A third sample of preschool children (n=24) was videotaped using the app in small groups to measure engagement and record their responses to the app.ResultsFive key content areas emerged from the telephone interviews: (1) mobile devices are an important part of families' everyday routines, and parents have parameters governing their use; (2) parents often use mobile devices as a tool for behavior management; (3) parents clearly distinguish between mobile device use for learning versus entertainment; (4) parents have an overarching desire for balance in regard to their child's mobile device use; and (5) parents were generally supportive of the idea of using mobile apps for intervention delivery. From the app prototype testing with parents, participants reacted positively to the app and felt that it would be useful in a variety of situations. Testing with preschoolers showed the children were highly engaged with the app and a majority remained standing and/or actively moving through the entire length of the app.ConclusionsMobile devices are already integrated into most families' daily routines and appear to be an acceptable method of intervention delivery in low-income families in rural Colorado. The physical activity app represents an innovative way to reach these families and, with further improvements based on participant feedback, will provide children with a unique opportunity to practice key movement skills
On Odd Radio Circles as Supernova Remnants
The origin of arcmin-sized Odd Radio Circles (ORCs) found in modern all-sky
radio surveys remain uncertain, with explanations ranging from
starburst/AGN-driven shocks to supernova remnants (SNRs) in the low-density
ambient medium. Using well-calibrated radio light curve models, we assess the
possibility that ORCs are radio SNRs evolving in low ambient densities. Our
models imply that ORCs 1-5 and J0624-6948 (near the LMC) as SNRs must be within
200 kpc and 100 kpc from the Sun respectively, given their observed flux
densities and angular sizes. To be evolving in the circumgalactic medium of the
Milky Way, our models require ORCs 1-5 to be ejecta-dominated SNRs within 50
kpc, evolving in ambient densities of cm.
However, this is statistically unlikely because ORCs 1-5 would have ages
yrs, much smaller than their expected lifetimes of 10 yrs at these
densities, and because the low SN rate and steep profile of the stellar halo
imply a negligible number of ORC-like SNRs within 50 kpc. The circumgalactic
medium SNR scenario for J0624-6948 is more likely (though still low
probability) compared to ORCs 1-5, as our models allow J0624-6948 to be
3000 yrs. On the other hand, the interpretation of J0624-6948 as a
Sedov-Taylor SNR at 50 kpc (LMC) distance is possible for a wide range of
ambient densities ( cm) and ages
yr, while also being consistent with the local HI
environment.Comment: 9 pages, 4 figures. Submitted to MNRAA
Associative Memory In Three Aplysiids: Correlation With Heterosynaptic Modulation
Much recent research on mechanisms of learning and memory focuses on the role of heterosynaptic neuromodulatory signaling. Such neuromodulation appears to stabilize Hebbian synaptic changes underlying associative learning, thereby extending memory. Previous comparisons of three related sea-hares ( Mollusca, Opisthobranchia) uncovered interspecific variation in neuromodulatory signaling: strong in Aplysia californica, immeasureable in Dolabrifera dolabrifera, and intermediate in Phyllaplysia taylori. The present study addressed whether this interspecific variation in neuromodulation is correlated with memory of associative ( classical conditioning) learning. We differentially conditioned the tail-mantle withdrawal reflex of each of the three species: Mild touch to one side of the tail was paired with a noxious electrical stimulus to the neck. Mild touch to the other side served as an internal control. Post-training reflex amplitudes were tested 15 -30 min after training and compared with pre-test amplitudes. All three species showed conditioning: training increased the paired reflex more than the unpaired reflex. However, the temporal pattern of conditioning varied between species. Aplysia showed modest conditioning that grew across the post-test period. Dolabrifera showed distinctly short-lived conditioning, present only on the first post-test. The time course of memory in Phyllaplysia was intermediate, although not statistically distinguishable from the other two species. Taken together, these experiments suggest that evolutionary changes in nonassociative heterosynaptic modulation may contribute to evolutionary changes in the stability of the memory of classical conditioning
Cloning of the Complete Gene for Carcinoembryonic Antigen
Carcinoembryonic antigen (CEA) is a widely used tumor marker, especially in the surveillance of colonic cancer patients. Although CEA is also present in some normal tissues, it is apparently expressed at higher levels in tumorous tissues than in corresponding normal tissues. As a first step toward analyzing the regulation of expression of CEA at the transcriptional level, we have isolated and characterized a cosmid clone (cosCEA1), which contains the entire coding region of the CEA gene. A close correlation exists between the exon and deduced immunoglobulin-like domain borders. We have determined a cluster of transcriptional starts for CEA and the closely related nonspecific cross-reacting antigen (NCA) gene and have sequenced their putative promoters. Regions of sequence homology are found as far as approximately 500 nucleotides upstream from the translational starts of these genes, but farther upstream they diverge completely. In both cases we were unable to find classic TATA or CAAT boxes at their expected positions. To characterize the CEA and NCA promoters, we carried out transient transfection assays with promoter-indicator gene constructs in the CEA-producing adenocarcinoma cell line SW403, as well as in nonproducing HeLa cells. A CEA gene promoter construct, containing approximately 400 nucleotides upstream from the translational start, showed nine times higher activity in the SW403 than in the HeLa cell line. This indicates that cis-acting sequences which convey cell type-specific expression of the CEA gene are contained within this region
Background reionization history from omniscopes
The measurements of the 21-cm brightness temperature fluctuations from the
neutral hydrogen at the Epoch of Reionization (EoR) should inaugurate the next
generation of cosmological observables. In this respect, many works have
concentrated on the disambiguation of the cosmological signals from the
dominant reionization foregrounds. However, even after perfect foregrounds
removal, our ignorance on the background reionization history can significantly
affect the cosmological parameter estimation. In particular, the
interdependence between the hydrogen ionized fraction, the baryon density and
the optical depth to the redshift of observation induce nontrivial degeneracies
between the cosmological parameters that have not been considered so far. Using
a simple, but consistent reionization model, we revisit their expected
constraints for a futuristic giant 21-cm omniscope by using for the first time
Markov Chain Monte Carlo (MCMC) methods on multiredshift full sky simulated
data. Our results agree well with the usual Fisher matrix analysis on the
three-dimensional flat sky power spectrum but only when the above-mentioned
degeneracies are kept under control. In the opposite situation, Fisher results
can be inaccurate. We show that these conditions can be fulfilled by combining
cosmic microwave background measurements with multiple observation redshifts
probing the beginning of EoR. This allows a precise reconstruction of the total
optical depth, reionization duration and maximal spin temperature. Finally, we
discuss the robustness of these results in presence of unresolved ionizing
sources. Although most of the standard cosmological parameters remain weakly
affected, we find a significant degradation of the background reionization
parameter estimation in presence of nuisance ionizing sources.Comment: 22 pages, 18 figures, uses RevTex. References added, matches
published versio
Temperature and Metallicity Gradients in the Hot Gas Outflows of M82
We utilize deep Chandra X-ray Observatory imaging and spectra of M82, the
prototype of a starbursting galaxy with a multiphase wind, to map the hot
plasma properties along the minor axis of the galaxy. We extract spectra from
11 regions up to 2.5 kpc from the starbursting midplane and model the data as a
multi-temperature, optically thin thermal plasma with contributions from a
non-thermal (power-law) component and from charge exchange (CX). We examine the
gradients in best-fit parameters, including the intrinsic column density,
plasma temperature, metal abundances, and number density of the hot gas as a
function of distance from the M82 nucleus. We find that the temperatures and
number densities of the warm-hot and hot plasma peak at the starbursting ridge
and decreases along the minor axis. The temperature and density profiles are
inconsistent with spherical adiabatic expansion of a super-heated wind and
suggest mass loading and mixing of the hot phase with colder material.
Non-thermal emission is detected in all of the regions considered, and CX
comprises 8-25% of the total absorption-corrected, broad-band (0.5-7 keV) X-ray
flux. We show that the abundances of O, Ne, Mg, and Fe are roughly constant
across the regions considered, while Si and S peak within 500 pc of the central
starburst. These findings support a direct connection between the M82 superwind
and the warm-hot, metal-rich circumgalactic medium (CGM).Comment: 15 pages, 8 figures, ApJ in pres
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