254 research outputs found
Bond Strength of an Amorphous Calcium PhosphateâContaining Orthodontic Adhesive
Objective: To determine whether an amorphous calcium phosphate (ACP)-containing adhesive has an acceptable level of shear bond strength to be used as an orthodontic adhesive.
Materials and Methods: Sixty extracted premolars were randomly divided into three groups for orthodontic bonding. Group 1 used a composite resin adhesive (Transbond XT), group 2 was bonded with an ACP-containing adhesive (Aegis Ortho), and group 3 used a resin-modified glass ionomer (Fuji Ortho LC). All bonded teeth were stored in distilled water at 37°C for 40 ± 2 hours prior to debonding. Shear bond strength and adhesive remnant index (ARI) were recorded for each specimen.
Results: The mean shear bond strengths for the three test groups were: group 1 (15.2 ± 3.6 MPa), group 2 (6.6 ± 1.5 MPa), and group 3 (8.3 ± 2.8 MPa). A one-way analysis of variance showed a significant difference in bond strengths between the groups. A post hoc Tukey test showed group 1 to be significantly (P \u3c .001) greater than groups 2 and 3. A Kruskal-Wallis test and a Mann-Whitney U-test showed groups 1 and 3 exhibited lower ARI scores than group 2, but a majority of specimens in each group had greater than 50% of the cement removed along with the bracket during debonding.
Conclusions: The ACP-containing adhesive demonstrated a low, but satisfactory bond strength needed to function as an orthodontic adhesive
Business Success and Businesses' Beauty Capital
We examine whether a difference in pay for beauty is supported by different productivity of people according to looks. Using a sample of advertising firms, we find that those firms with better-looking executives have higher revenues and faster growth than do otherwise identical firms whose executives are not so good-looking. The impact on revenue far exceeds the likely effect of beauty on the executives' wages. This suggests that their beauty creates firm-specific investments, in the form of improved relationships within work groups, the returns to which are shared by the firm and the executive.
Taprootâą Technology: Tree Coring for Fast, Noninvasive Plume Delineations
In Efforts to Evaluate the Use of Plants as a Forensic Tool for Delineating Contaminated Soil and Groundwater, a Laboratory Experiment and a Field Sampling Effort Were Undertaken. Site Assessments Are Often Costly and Inaccurate, Requiring Multiple Mobilizations to Hone in on Source Areas and Getting Accurate Estimates of Contaminant Extent and Distribution. as These Extensive Site Delineations Take Place, Valuable Time and Resources Are Lost. the Findings of This Study Show that Plants Can Be Used as a Tool to Evaluate a Variety of Subsurface Contaminants, Either in the Vadose Zone or in the Saturated Zone. in the First Field Application of Taproot⹠Technology, a Large, Heavily Forested Site Was Sampled in One Day and the Contamination On-Site Was More Accurately Delineated Than Had Been Generated at the Site in over a Decade, with More Than 26 Wells Installed. New Source Zones Were Detected on the Site, and the Presence of New Waste Depositions Was Uncovered for the First Time Showing the Great Value of Tree Coring as a Contaminant Detection Tool. © 2009 Wiley Periodicals, Inc
The Epithelial Sodium Channel (ENaC) Establishes a Trafficking Vesicle Pool Responsible for Its Regulation
The epithelial sodium channel (ENaC) is the rate-limiting step for sodium reabsorption across tight epithelia. Cyclic-AMP (cAMP) stimulation promotes ENaC trafficking to the apical surface to increase channel number and transcellular Na+ transport. Removal of corticosteroid supplementation in a cultured cortical collecting duct cell line reduced ENaC expression. Concurrently, the number of vesicles trafficked in response to cAMP stimulation, as measured by a change in membrane capacitance, also decreased. Stimulation with aldosterone restored both the basal and cAMP-stimulated ENaC activity and increased the number of exocytosed vesicles. Knocking down ENaC directly decreased both the cAMP-stimulated short-circuit current and capacitance response in the presence of aldosterone. However, constitutive apical recycling of the Immunoglobulin A receptor was unaffected by alterations in ENaC expression or trafficking. Fischer Rat Thyroid cells, transfected with α,ÎČ,Îł-mENaC had a significantly greater membrane capacitance response to cAMP stimulation compared to non-ENaC controls. Finally, immunofluorescent labeling and quantitation revealed a smaller number of vesicles in cells where ENaC expression was reduced. These findings indicate that ENaC is not a passive passenger in regulated epithelial vesicle trafficking, but plays a role in establishing and maintaining the pool of vesicles that respond to cAMP stimulation. © 2012 Edinger et al
Signal averaging xâray streak camera with picosecond jitter
We have developed an averaging picosecond xâray streak camera using a dcâbiased photoconductive switch as a generator of a highâvoltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shotâtoâshot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband xâray emission from an ultrashort pulse laserâproduced plasma. Accumulation of the streaked xâray signals significantly improved the signalâtoânoise ratio of the data obtained. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69581/2/RSINAK-67-3-697-1.pd
Amplification of 1 ps pulses at 1.053 [mu]m in a Ti:Al2O3 regenerative amplifier
We demonstrate the operation of a Ti:Al2O3 regenerative amplifier tunable around 1 [mu]m. Gains up to 108 at 1.053 [mu]m without any spectral narrowing are obtained. This amplifier is designed for use in terawatt picosecond lasers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29239/1/0000294.pd
Verifying Real-Time Systems using Explicit-time Description Methods
Timed model checking has been extensively researched in recent years. Many
new formalisms with time extensions and tools based on them have been
presented. On the other hand, Explicit-Time Description Methods aim to verify
real-time systems with general untimed model checkers. Lamport presented an
explicit-time description method using a clock-ticking process (Tick) to
simulate the passage of time together with a group of global variables for time
requirements. This paper proposes a new explicit-time description method with
no reliance on global variables. Instead, it uses rendezvous synchronization
steps between the Tick process and each system process to simulate time. This
new method achieves better modularity and facilitates usage of more complex
timing constraints. The two explicit-time description methods are implemented
in DIVINE, a well-known distributed-memory model checker. Preliminary
experiment results show that our new method, with better modularity, is
comparable to Lamport's method with respect to time and memory efficiency
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The Great Trade Debate
Information about whether United States trade protectionism will help or hurt the U.S. economy was presented at a roundtable discussion. Included were the views of several business, economic and trade experts who argued both for and against the position that protectionist trade policies will backfire against U.S. consumers and workers. The panelists included Dartmouth economist Douglas Irwin, former U.S. trade representative Susan Schwab and magazine publisher John R. MacArthur
Large Language Models and Knowledge Graphs: Opportunities and Challenges
Large Language Models (LLMs) have taken Knowledge Representation -- and the
world -- by storm. This inflection point marks a shift from explicit knowledge
representation to a renewed focus on the hybrid representation of both explicit
knowledge and parametric knowledge. In this position paper, we will discuss
some of the common debate points within the community on LLMs (parametric
knowledge) and Knowledge Graphs (explicit knowledge) and speculate on
opportunities and visions that the renewed focus brings, as well as related
research topics and challenges.Comment: 30 page
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