scholarly journals Indirect inference with(out) constraints

10.3982/qe986 ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 113-159 ◽  
Author(s):  
David T. Frazier ◽  
Eric Renault
Keyword(s):  
Asymptotic Theory ◽  
Structural Parameters ◽  
Inequality Constraints ◽  
Structural Data ◽  
Statistical Information ◽  
Strict Inequality ◽  
Indirect Inference ◽  
Auxiliary Model ◽  
Binding Function

Indirect Inference (I‐I) estimation of structural parameters θ requires matching observed and simulated statistics, which are most often generated using an auxiliary model that depends on instrumental parameters β. The estimators of the instrumental parameters will encapsulate the statistical information used for inference about the structural parameters. As such, artificially constraining these parameters may restrict the ability of the auxiliary model to accurately replicate features in the structural data, which may lead to a range of issues, such as a loss of identification. However, in certain situations the parameters β naturally come with a set of q restrictions. Examples include settings where β must be estimated subject to q possibly strict inequality constraints g( β)>0, such as, when I‐I is based on GARCH auxiliary models. In these settings, we propose a novel I‐I approach that uses appropriately modified unconstrained auxiliary statistics, which are simple to compute and always exists. We state the relevant asymptotic theory for this I‐I approach without constraints and show that it can be reinterpreted as a standard implementation of I‐I through a properly modified binding function. Several examples that have featured in the literature illustrate our approach.

A Relatively Inexpensive Microprocessor-Linked Digital Plamimeter for Electron Microscopic Morphometry

1981 ◽  
Vol 39 ◽  
pp. 266-269
Author(s):  
Lee D. Peachey
Keyword(s):  
Theoretical Basis ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Structural Data ◽  
Large Set ◽  
Dimensional Electron ◽  
Electron Microscopic ◽  
Morphometric Methods ◽  
Electron Microscopic Morphometry ◽  
Separate Step

Stereology provides a theoretical basis for powerful morphometric methods for the estimation of three-dimensional structural parameters from two-dimensional electron micrographs of cells and tissues. These methods assume at the start that one has a sufficiently large set of micrographs containing valid structural data. The task of obtaining from these micrographs the large quantity of data needed to get statistically valid results has been eased in two general ways. Sampling of data in the micrograph can be done rapidly by point and intersection counting methods. An alternate method, planimetry, obtains all the data in the micrograph, but in general is more time-consuming than point and intersection counting. Some of the relative inefficiency of planimetry is compensated when a digital planimeter is coupled with a computer. Areas and lengths can be computed simultaneously as fast as profiles are traced. Furthermore, rapid and numerically accurate compilation and statistical analysis of the data can be done automatically as the planimetry is done, not as a separate step after the data have been obtained.

Atomic and Electronic Structure of Zinc and Copper Pyrovanadates with Negative Thermal Expansion

2010 ◽  
Vol 63 ◽  
pp. 358-363 ◽  
Author(s):  
Tatiana Krasnenko ◽  
Nadezhda Medvedeva ◽  
Vitalii Bamburov
Keyword(s):  
Thermal Expansion ◽  
Thermal Deformation ◽  
Structural Parameters ◽  
Negative Thermal Expansion ◽  
Structural Data ◽  
Interband Transitions ◽  
Negative Coefficient ◽  
Total Energies ◽  
Zigzag Shape ◽  
Atomic And Electronic Structure

Zinc and copper pyrovanadates are promising materials for micro- and optoelectronics due to their negative coefficient of volume thermal expansion (NTE). Besides, solid solutions on the base of these compounds can be used to obtain grade materials with variable thermal coefficients. Thermal deformation of both Zn2V2O7 and Cu2V2O7 structures was studied. According to the structural data, NTE of these substances is provided by the zigzag shape of zinc (copper) chains alongside with stable distances between layers. The structural and electronic characteristics depending on temperature were studied for α-Zn2V2O7 and α-Cu2V2O7 by using the first principle method. Our results demonstrate that the lowest total energies corresponds to the structural parameters at 400° C and 200° C for α-Zn2V2O7 and α-Cu2V2O7, respectively. We predict that α- Zn2V2O7 is a semiconductor with the band gap of 1,5 эВ and the bottom of conduction band is determined by the vanadium 3d states with small addition of antibonding oxygen 2р-states. For α- Cu2V2O7, the lowest interband transitions correspond to energy of 1,6 eV and involve also the O2p and V 3d states.

Über Hexaiodoplatinate(IV) M2PtI6 (M = K, Rb, Cs, NH4, Tl) Darstellungsverfahren, Eigenschaften und Kristallstrukturen / On Hexaiodoplatinates(IV) M2PtI6 (M = K, Rb, Cs, NH4, Tl) -Preparation, Properties and Structural Data

1983 ◽  
Vol 38 (8) ◽  
pp. 905-910 ◽  
Author(s):  
Gerhard Thiele ◽  
Christian Mrozek ◽  
Dieter Kämmerer ◽  
Kurt Wittmann
Keyword(s):  
Aqueous Solutions ◽  
Single Crystal ◽  
Structural Parameters ◽  
Structural Data ◽  
Structure Type ◽  
Water Soluble ◽  
Crystal Data ◽  
Soluble Salts ◽  
Concentrated Aqueous Solutions ◽  
Distorted Version

Crystals of hexaiodoplatinates(IV) M2PtIe (M = K, Rb, Cs, NH4, Tl) have been obtained by heating PtI4 or H2FtCl6 in highly concentrated aqueous solutions of MI in the presence of small amounts of HI and I2 in an ampoule for 24 h at 160 °C. The structural parameters were determined from single crystal data. In water less soluble compounds with M = Rb, Cs, NH4 show the cubic K2PtCl6 structure, whereas the easily water soluble salts with M = K, Tl both crystallize in a tetragonally distorted version of this structure type.

A Systematic Method for Extracting Structural Parameters from Low Angle X-Ray Reflectivity Measurements on Multilayers

1989 ◽  
Vol 160 ◽  
Author(s):  
L.M. Goldman ◽  
H.A. Atwater ◽  
F. Spaepen
Keyword(s):  
External Surface ◽  
Structural Parameters ◽  
Structural Data ◽  
X Ray Diffraction ◽  
Systematic Method ◽  
X Ray ◽  
Dynamic Scattering

AbstractX-ray diffraction is one of the main methods of determining the structure of multilayers. Low angle reflectivity measurements are particulary useful for multilayers containing polycrystalline or amorphous constituents, and for obtaining specific structural data. We present a method based on both kinematic and dynamic scattering calculations, and use it to extract specific structural parameters such as the roughness or diffuseness of the external surface, the thickness of the constituent layers, and the roughness or diffuseness of the internal interfaces. Results are given for a sputtered A1/A12O3 multilayer.

Synthesis, antiviral activity, preliminary pharmacokinetics and structural parameters of thiazolide amine salts

2021 ◽  
Vol 13 (20) ◽  
pp. 1731-1741 ◽  
Author(s):  
Andrew V Stachulski ◽  
Jean-Francois Rossignol ◽  
Sophie Pate ◽  
Joshua Taujanskas ◽  
Craig M Robertson ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Influenza A ◽  
Structural Parameters ◽  
Aqueous Solubility ◽  
Structural Data ◽  
Crystal Structural Data ◽  
Crystal Structural ◽  
Safety Indices ◽  
Amine Salts

Background: The thiazolides, typified by nitazoxanide, are an important class of anti-infective agents. A significant problem with nitazoxanide and its active circulating metabolite tizoxanide is their poor solubility. Results: We report the preparation and evaluation of a series of amine salts of tizoxanide and the corresponding 5-Cl thiazolide. These salts demonstrated improved aqueous solubility and absorption, as shown by physicochemical and in vivo measurements. They combine antiviral activity against influenza A virus with excellent cell safety indices. We also report the x-ray crystal structural data of the ethanolamine salt. Conclusion: The ethanol salt of thiazolide retains the activity of the parent together with an improved cell safety index, making it a good candidate for further evaluation.

On the relationship of thermodynamic parameters with the buried surface area in protein-ligand complex formation

1996 ◽  
Vol 16 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Netai C. Singha ◽  
Namita Surolia ◽  
A. Surolia
Keyword(s):  
Heat Capacity ◽  
High Resolution ◽  
Complex Formation ◽  
Thermodynamic Parameters ◽  
Hydrophobic Interactions ◽  
Structural Parameters ◽  
Structural Data ◽  
Rational Drug Design ◽  
Poor Correlation ◽  
Ligand Complex

Prediction of thermodynamic parameters of protein-protein and antigen-antibody complex formation from high resolution structural parameters has recently received much attention, since an understanding of the contributions of different fundamental processes like hydrophobic interactions, hydrogen bonding, salt bridge formation, solvent reorganization etc. to the overall thermodynamic parameters and their relations with the structural parameters would lead to rational drug design. Using the results of the dissolution of hydrocarbons and other model compounds the changes in heat capacity (ΔCp), enthalpy (ΔH) and entropy (ΔS) have been empirically correlated with the polar and apolar surface areas buried during the process of protein folding/unfolding and protein-ligand complex formation. In this regard, the polar and apolar surfaces removed from the solvent in a protein-ligand complex have been calculated from the experimentally observed values of changes in heat capacity (ΔCp) and enthalpy (ΔH) for protein-ligand complexes for which accurate thermodynamic and high resolution structural data are available, and the results have been compared with the x-ray crystallographic observations. Analyses of the available results show poor correlation between the thermodynamic and structural parameters. Probable reasons for this discrepancy are mostly related with the reorganization of water accompanying the reaction which is indeed proven by the analyses of the energetics of the binding of the wheat germ agglutinin to oligosaccharides.

scholarly journals Indirect Inference: Which Moments to Match?

Econometrics ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 14 ◽  
Author(s):  
David Frazier ◽  
Eric Renault
Keyword(s):  
Structural Parameters ◽  
Generalized Method Of Moments ◽  
Estimation Procedure ◽  
Efficient Estimation ◽  
Indirect Inference ◽  
General Context ◽  
Moment Matching ◽  
Parameter Matching ◽  
The Moment ◽  
Two Step Estimation

The standard approach to indirect inference estimation considers that the auxiliary parameters, which carry the identifying information about the structural parameters of interest, are obtained from some recently identified vector of estimating equations. In contrast to this standard interpretation, we demonstrate that the case of overidentified auxiliary parameters is both possible, and, indeed, more commonly encountered than one may initially realize. We then revisit the “moment matching” and “parameter matching” versions of indirect inference in this context and devise efficient estimation strategies in this more general framework. Perhaps surprisingly, we demonstrate that if one were to consider the naive choice of an efficient Generalized Method of Moments (GMM)-based estimator for the auxiliary parameters, the resulting indirect inference estimators would be inefficient. In this general context, we demonstrate that efficient indirect inference estimation actually requires a two-step estimation procedure, whereby the goal of the first step is to obtain an efficient version of the auxiliary model. These two-step estimators are presented both within the context of moment matching and parameter matching.

Analysis of crystallographic and structural data of polymeric iron-alkaline metal complexes

2011 ◽  
Vol 34 (5-6) ◽  
pp. 93-126
Author(s):  
Milan Melnik ◽  
Markku Rafael Sundberg ◽  
Rolf Uggla
Keyword(s):  
Coordination Number ◽  
Iron Atom ◽  
Structural Parameters ◽  
Structural Data ◽  
Oxidation States ◽  
Alkaline Metal ◽  
Coordination Numbers ◽  
Metal Atoms ◽  
Polymeric Chains ◽  
Group 1

Abstract The present review covers almost 100 polymeric MFe (M=Li, Na, K, Rb, and Cs) compounds. The metal atoms of group 1 as partners with iron atom build up complex polymeric chains. The iron atoms are found in the oxidation states 0, +2, and +3, of which the oxidation state +3 prevails. The coordination number of the iron atom ranges from 2 to 10 (sandwiched). The coordination sphere about the main group 1 metals varies, ranging from tetrahedral to mostly trigonal bipyramid. There are also higher coordination numbers involved, namely, from 6 to 10. The most common ligand atoms are oxygen and nitrogen. There are three compounds displaying distortion isomerism. Several relationships between structural parameters are found and discussed.

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