1,396 research outputs found
How Do Informal Agreements and Renegotiation Shape Contractual Reference Points?
Previous experimental work provides encouraging support for some of the central assumptions underlying Hart and Moore (2008)ās theory of contractual reference points. However, existing studies ignore realistic aspects of trading relationships such as informal agreements and ex post renegotiation. We investigate the relevance of these features experimentally. Our evidence indicates that the central behavioral mechanism underlying the concept of contractual reference points is robust to the presence of informal agreements and ex post renegotiation. However, our data also reveal new behavioral features that suggest refinements of the theory. In particular, we find that the availability of informal agreements and ex post renegotiation changes how trading parties evaluate ex post outcomes. Interestingly, the availability of these additional options affects ex post evaluations even in situations in which the parties do not use them.
Gamma-Ray Burst Polarization: Limits from RHESSI Measurements
Using the RHESSI satellite as a Compton polarimeter, a recent study claimed
that the prompt emission of GRB021206 was almost fully linearly polarized. This
was challenged by a subsequent reanalysis. We present an novel approach,
applying our method to the same data. We identify Compton scattering candidates
by carefully filtering events in energy, time, and scattering geometry. Our
polarization search is based on time dependent scattering rates in
perpendicular directions, thus optimally excluding systematic errors. We
perform simulations to obtain the instrument's polarimetric sensitivity, and
these simulations include photon polarization. For GRB021206, we formally find
a linear polarization degree of 41% (+57% -44%), concluding that the data
quality is insufficient to constrain the polarization degree in this case. We
further applied our analysis to GRB030519B and found again a null result.Comment: 39 pages, 11 figures, accepted for publication by the Astrophysical
Journa
Dentine decalcification and smear layer removal by different ethylenediaminetetraacetic acid and 1-hydroxyethane-1,1-diphosphonic acid species
AIM
To compare solutions of di- and tetrasodium ethylenediaminetetraacetic acid (EDTA) and 1-hydroxyethane-1,1-diphosphonic acid (HEDP) regarding their ability to solubilize calcium from dentine and remove smear layer.
METHODOLOGY
Solutions with a molarity corresponding to that of 17% Na EDTA (pH adjusted to 8.5) were prepared by dissolving Na and Na salts of HEDP (etidronate), or Na EDTA in deionized water. Standardized root dentine discs covered by a smear layer were prepared from human third molars. These discs (nĀ =Ā 10 per group) were immersed in test solutions or phosphate-buffered saline for 1Ā min. The dissolved Ca was determined by atomic absorption spectroscopy, apparently opened dentinal tubules by laser scanning microscopy and automated image analysis. Ca values were compared between groups by parametric, tubular areas by nonparametric methods, Ī±Ā =Ā 0.05.
RESULTS
Solutions prepared from the tetrasodium salts were alkaline (pH 11.3-11.4), whilst counterparts made from the disodium salts were acidic. The EDTA solutions dissolved more calcium than the HEDP counterparts (PĀ <Ā 0.05); solutions prepared with the disodium salts dissolved more calcium than those made from the tetrasodium salts (PĀ <Ā 0.05). There was a high correlation between dissolved calcium and the apparently opened tubular areas (Spearman's ĻĀ =Ā 0.81). Differences between groups regarding opened tubules were similar to those observed regarding the Ca values, with a slightly reduced discerning power due to high variance.
CONCLUSION
Calcium chelation and thus smear layer removal by EDTA and HEDP are influenced by pH
A comparison of maternal effects and current environment on vital rates of Aphis nerii , the milkweedāoleander aphid
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72485/1/j.1365-2311.2007.00853.x.pd
Effects of nitrogen deposition on the interaction between an aphid and its host plant
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71607/1/j.1365-2311.2007.00945.x.pd
Spectral Analysis of GRBs Measured by RHESSI
The Ge spectrometer of the RHESSI satellite is sensitive to Gamma Ray Bursts
(GRBs) from about 40 keV up to 17 MeV, thus ideally complementing the Swift/BAT
instrument whose sensitivity decreases above 150 keV. We present preliminary
results of spectral fits of RHESSI GRB data. After describing our method, the
RHESSI results are discussed and compared with Swift and Konus.Comment: 4 pages, 4 figures, conference proceedings, 'Swift and GRBs:
Unveiling the Relativistic Universe', San Servolo, Venice, 5-9 June 2006, to
appear in Il Nouvo Ciment
Generation of three-dimensional prototype models based on cone beam computed tomography
Purpose: The purpose of this study was to generate three-dimensional models based on digital volumetric data that can be used in basic and advanced education. Methods: Four sets of digital volumetric data were established by cone beam computed tomography (CBCT) (Accuitomo, J. Morita, Kyoto, Japan). Datasets were exported as Dicom formats and imported into Mimics and Magic software programs to separate the different tissues such as nerve, tooth and bone. These data were transferred to a Polyjet 3D Printing machine (Eden 330, Object, Israel) to generate the models. Results: Three-dimensional prototype models of certain limited anatomical structures as acquired volumetrically were fabricated. Conclusions: Generating three-dimensional models based on CBCT datasets is possible. Automated routine fabrication of these models, with the given infrastructure, is too time-consuming and therefore too expensiv
Contracts as Reference Points - Experimental Evidence
In a recent paper, Hart and Moore (2008) introduce new behavioral assumptions that can explain long-term contracts and important aspects of the employment relation. However, so far there exists no direct evidence that supports these assumptions and, in particular, Hart and Moore's notion that contracts provide reference points. In this paper, we examine experimentally the behavioral forces stipulated in their theory. The evidence confirms the model's prediction that there is a tradeoff between rigidity and flexibility in a trading environment with incomplete contracts and ex ante uncertainty about the state of nature. Flexible contracts - which would dominate rigid contracts under standard assumptions - cause a significant amount of shading on ex post performance, while under rigid contracts, much less shading occurs. Thus, although rigid contracts rule out trading in some states of the world, parties frequently implement them. While our results are broadly consistent with established behavioral concepts, they cannot easily be explained by existing theories. The experiment appears to reveal a new behavioral force: ex ante competition legitimizes the terms of a contract, and aggrievement and shading occur mainly about outcomes within the contract.
Structural identifiability of surface binding reactions involving heterogeneous analyte : application to surface plasmon resonance experiments
Binding affinities are useful measures of target interaction and have an important role in understanding biochemical reactions that involve binding mechanisms. Surface plasmon resonance (SPR) provides convenient real-time measurement of the reaction that enables subsequent estimation of the reaction constants necessary to determine binding affinity. Three models are
considered for application to SPR experimentsāthe well mixed Langmuir model and two models that represent the binding reaction in the presence of transport effects. One of these models, the effective rate constant approximation, can be derived from the other by applying a quasi-steady state assumption. Uniqueness of the reaction constants with respect to SPR measurements
is considered via a structural identiļ¬ability analysis. It is shown that the models are structurally unidentiļ¬able unless the sample concentration is known. The models are also considered for analytes with heterogeneity in the binding kinetics. This heterogeneity further confounds the identiļ¬ability of key parameters necessary for reliable estimation of the binding affinit
Phase detection at the quantum limit with multi-photon Mach-Zehnder interferometry
We study a Mach-Zehnder interferometer fed by a coherent state in one input
port and vacuum in the other. We explore a Bayesian phase estimation strategy
to demonstrate that it is possible to achieve the standard quantum limit
independently from the true value of the phase shift and specific assumptions
on the noise of the interferometer. We have been able to implement the protocol
using parallel operation of two photon-number-resolving detectors and
multiphoton coincidence logic electronics at the output ports of a
weakly-illuminated Mach-Zehnder interferometer. This protocol is unbiased and
saturates the Cramer-Rao phase uncertainty bound and, therefore, is an optimal
phase estimation strategy.Comment: 4 pages, 5 figures replaced fig. 1 to correct graphics bu
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