1,375 research outputs found
The Effect of Magnification Loupes on Posture During Instrumentation by Dental Hygienists
Purpose: The purpose of this study was to determine the effects of dental magnification loupes on posture during instrumentation. Methods: A convenience sample of twenty-seven righthanded dental hygienists with no history of injuries or disabilities of the head, neck, and trunk regions was enrolled. Baseline posture calibration was taken. Accelerometers were placed on four locations of the head and trunk (occipital pole of head, cervical vertebrae: C5, thoracic vertebrae: T5, lumbar vertebrae: L1) to measure changes in posture. Accelerations in three axes were recorded (anterior/posterior (AP), medial/lateral (ML), vertical (VT)). Mean accelerations of the three axes were used to compute average forward tilt (APangle) and sideways tilt (MLangle) of each sensor. For each axis, root mean square (rms) was also calculated to determine the magnitude of tremor fluctuations (i.e., APrms, MLrms and VTrms). Chair mounted typodonts with artificial calculus represented a simulated oral environment. Subjects were randomly assigned to wear loupes during the first or second half of the experiment and instructed to instrument all areas of the mouth with an ODU 11/12 explorer. An end user opinion survey was completed by participants. Results: Twenty seven participants (26 female and 1 male) completed the study. Results revealed no statistically significant differences between loupes and no loupes in the tilt angle of each sensor location in the AP or ML planes. In contrast, a statistically significant difference in mean fluctuations while wearing loupes (M=.215152, SD=.0741530) (rms) in AP at C5; t(24)=2.63, p=.015, compared to not wearing loupes (M=.261028, SD=.1379292) indicated posture fluctuations decreased while wearing loupes. APrms was only significant at C5; for ML and VT axes and sensor positions (head, C5, T5, L1) there were no statistically significant differences in mean fluctuations (rms) between wearing loupes and not. Overall, 74% of the participants strongly agreed that magnification loupes made exploring easier and 67% of participants strongly agreed that magnification loupes improved their posture. Conclusion: While participants perceived that magnification loupes enhanced their posture, the study provided little evidence that wearing loupes leads to changes in body orientation; only to reduced postural tremors at C5 in the AP axis
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Spectroscopic evidence of 'jumping and pecking' of cholinium and H-bond enhanced cation-cation interaction in ionic liquids
The subtle energy-balance between Coulomb-interaction, hydrogen bonding and dispersion forces governs the unique properties of ionic liquids. To measure weak interactions is still a challenge. This is in particular true in the condensed phase wherein a melange of different strong and directional types of interactions is present and cannot be detected separately. For the ionic liquids (2-hydroxyethyl)-trimethylammonium (cholinium) bis(trifluoro-methylsulfonyl)amide and N,N,N-trimethyl-N-propylammonium bis(trifluoromethylsulfonyl)amide which differ only in the 2-hydroxyethyl and the propyl groups of the cations, we could directly observe distinct vibrational signatures of hydrogen bonding between the cation and the anion indicated by âjumping and peckingâ motions of cholinium. The assignment could be confirmed by isotopic substitution H/D at the hydroxyl group of cholinium. For the first time we could also find direct spectroscopic evidence for H-bonding between like-charged ions. The repulsive Coulomb interaction between the cations is overcome by cooperative hydrogen bonding between the 2-hydroxyethyl functional groups of cholinium. This H-bond network is reflected in the properties of protic ionic liquids (PILs) such as viscosities and conductivities
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Like-likes-Like: Cooperative Hydrogen Bonding Overcomes Coulomb Repulsion in Cationic Clusters with Net Charges up to Q=+6e
Quantum chemical calculations have been employed to study kinetically stable cationic clusters, wherein the monovalent cations are trapped by hydrogen bonding despite strongly repulsive electrostatic forces. We calculated linear and cyclic clusters of the hydroxy-functionalized cation N-(3-hydroxypropyl) pyridinium, commonly used as cation in ionic liquids. The largest kinetically stable cluster was a cyclic hexamer that very much resembles the structural motifs of molecular clusters, as known for water and alcohols. Surprisingly, strong cooperative hydrogen bonds overcome electrostatic repulsion and result in cationic clusters with a high net charge up to Q=+6e. The structural, spectroscopic, and electronic signatures of the cationic and related molecular clusters of 3-phenyl-1-propanol could be correlated to NBO parameters, supporting the existence of âanti-electrostaticâ hydrogen bonds (AEHB), as recently suggested by Weinhold. We also showed that dispersion forces enhance the cationic cluster formation and compensate the electrostatic repulsion of one additional positive charge
The effect of brumation on memory retention
Long-term torpor is an adaptive strategy that allows animals to survive harsh winter conditions. However, the impact that prolonged torpor has on cognitive function is poorly understood. Hibernation causes reduced synaptic activity and experiments with mammals reveal that this can have adverse effects on memories formed prior to hibernation. The impact of brumation, the winter dormancy that is observed in ectotherms, on memory remains unknown. The aim of this study was to examine whether an amphibian, the fire salamander (Salamandra salamandra), was able to retain learned spatial information after a period of brumation. Twelve fire salamanders were trained to make a simple spatial discrimination using a T-maze. All subjects learned the initial task. Upon reaching criterion, half of the subjects were placed into brumation for 100 days while the other half served as controls and were maintained under normal conditions. A post-brumation memory retention test revealed that animals from both conditions retained the learned response. Control tests showed that they solved the task using learned information and not olfactory cues. This finding contrasts with much of the mammalian research and suggests that the processes involved in prolonged torpor may have a fundamentally different impact on memory in mammals and amphibians
The Error is the Feature: how to Forecast Lightning using a Model Prediction Error
Despite the progress within the last decades, weather forecasting is still a
challenging and computationally expensive task. Current satellite-based
approaches to predict thunderstorms are usually based on the analysis of the
observed brightness temperatures in different spectral channels and emit a
warning if a critical threshold is reached. Recent progress in data science
however demonstrates that machine learning can be successfully applied to many
research fields in science, especially in areas dealing with large datasets. We
therefore present a new approach to the problem of predicting thunderstorms
based on machine learning. The core idea of our work is to use the error of
two-dimensional optical flow algorithms applied to images of meteorological
satellites as a feature for machine learning models. We interpret that optical
flow error as an indication of convection potentially leading to thunderstorms
and lightning. To factor in spatial proximity we use various manual convolution
steps. We also consider effects such as the time of day or the geographic
location. We train different tree classifier models as well as a neural network
to predict lightning within the next few hours (called nowcasting in
meteorology) based on these features. In our evaluation section we compare the
predictive power of the different models and the impact of different features
on the classification result. Our results show a high accuracy of 96% for
predictions over the next 15 minutes which slightly decreases with increasing
forecast period but still remains above 83% for forecasts of up to five hours.
The high false positive rate of nearly 6% however needs further investigation
to allow for an operational use of our approach.Comment: 10 pages, 7 figure
Spectroscopic Evidence for Clusters of Like-Charged Ions in Ionic Liquids Stabilized by Cooperative Hydrogen Bonding
Infrared spectroscopy and density functional theory calculations provide strong evidence for the formation of clusters of like-charged ions in ionic liquids. With decreasing temperature, cooperative hydrogen bonding overcomes repulsive electrostatic interaction. The resulting cyclic tetramers nicely resemble well-known molecular clusters of alcohols
Integrating Oceanographic Research Into High School Curricula: Achieving Broader Impacts Through Systems Education Experiences Modules
We describe a framework for incorporating cross-disciplinary oceanographic research into high school curriculum modules and discuss how this framework could be adopted broadly by ocean scientists to build cohesive broader impacts programs nested within individual oceanographic research programs
Mesenchymal Stem Cells Promote Oligodendroglial Differentiation in Hippocampal Slice Cultures
We have previously shown that soluble factors derived from mesenchymal stem cells (MSCs) induce oligodendrogenic fate and differentiation in adult rat neural progenitors (NPCs) in vitro. Here, we investigated if this pro-oligodendrogenic effect is maintained after cells have been transplanted onto rat hippocampal slice cultures, a CNS-organotypic environment. We first tested whether NPCs, that were pre-differentiated in vitro by MSC-derived conditioned medium, would generate oligodendrocytes after transplantation. This approach resulted in the loss of grafted NPCs, suggesting that oligodendroglial pre-differentiated cells could not integrate in the tissue and therefore did not survive grafting. However, when NPCs together with MSCs were transplanted in situ into hippocampal slice cultures, the grafted NPCs survived and the majority of them differentiated into oligodendrocytes. In contrast to the prevalent oligodendroglial differentiation in case of the NPC/MSC co-transplantation, naive NPCs transplanted in the absence of MSCs differentiated predominantly into astrocytes. In summary, the pro-oligodendrogenic activity of MSCs was maintained only after co-transplantation into hippocampal slice cultures. Therefore, in the otherwise astrogenic milieu, MSCs established an oligodendrogenic niche for transplanted NPCs, and thus, co-transplantation of MSCs with NPCs might provide an attractive approach to re-myelinate the various regions of the diseased CNS. Copyright (C) 2009 S. Karger AG, Base
Effective Gender Equality in Research and the Academia (EGERA)
EGERA brings together eight research and higher education institutions in seven EU member states (Belgium, the Czech Republic, France, Germany, the Netherlands, Portugal and Spain) + Turkey, bound by a same commitment to the dual objective of achieving gender equality in research, and strengthening the gender dimension in research. Made up of five universities covering an ample array of disciplines, from social sciences to STEM, a research centre on climate change belonging to the Czech Academy of Science, an independent evaluation structure specialized in the design and monitoring of gender equality plans, EGERA is coordinated by Sciences Po, a leading institution in social sciences in Europe. With view to bring about sustainable and measurable cultural and organizational changes to promote gender equality, EGERA has secured the full support of the top management structures of its respective partner institutions. Fully-fledged Gender Equality Action Plans (GEAPs) will be implemented and continuously enhanced along this four-yearlong project by the seven implementing partners. GEAPs will articulate a structural understanding of gender inequalities and bias in research with a set of actions covering the most salient issues with respect to the recruitment, retention, appraisal and empowerment of women in research, and to the mainstreaming of gender knowledge across disciplinary fields. Drawing upon innovative methods, of which some have been experimented and evaluated under previous/on-going FP7 projects, our cumulative and inclusive approach will notably support the operationalization of structural changes with both an intensive and extensive use of gender training, as an instrument for effective gender mainstreaming strategies. Mobilizing considerable gender expertise and relying upon multi-level women in science policy networks, EGERA will also put efforts into the dissemination of its outputs and achievements across the European Research Area.FP7-SCIENCE-IN-SOCIETY-2013-1 (FP7-SIS
Addressing researcher degrees of freedom through minP adjustment
When different researchers study the same research question using the same dataset they may obtain different and potentially even conflicting results. This is because there is often substantial flexibility in researchersâ analytical choices, an issue also referred to as âresearcher degrees of freedomâ. Combined with selective reporting of the smallest p-value or largest effect, researcher degrees of freedom may lead to an increased rate of false positive and overoptimistic results. In this paper, we address this issue by formalizing the multiplicity of analysis strategies as a multiple testing problem. As the test statistics of different analysis strategies are usually highly dependent, a naive approach such as the Bonferroni correction is inappropriate because it leads to an unacceptable loss of power. Instead, we propose using the âminPâ adjustment method, which takes potential test dependencies into account and approximates the underlying null distribution of the minimal p-value through a permutation-based procedure. This procedure is known to achieve more power than simpler approaches while ensuring a weak control of the family-wise error rate. We illustrate our approach for addressing researcher degrees of freedom by applying it to a study on the impact of perioperative paO2 on post-operative complications after neurosurgery. A total of 48 analysis strategies are considered and adjusted using the minP procedure. This approach allows to selectively report the result of the analysis strategy yielding the most convincing evidence, while controlling the type 1 errorâand thus the risk of publishing false positive results that may not be replicable
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