We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

2004아테네 올림픽대회출전 한국레슬링 대표선수의 무산소성 운동능력 및 등속성 근력

[발표] 2015개정 실과 교육과정 ‘가정생활’ 영역 개발 방향

Mothers and Others: The Evolutionary Origins of Mutual Understanding

https://re.public.polimi.it/bitstream/11311/1088976/2/11311-1088976_Metrangolo.pdf

A halogen bond-donor amino acid for organocatalysis in water

This communication reports experimental and theoretical evidences of σ-hole interactions in adducts between nitrogen or oxygen nucleophiles and tetroxides of osmium or other group 8 elements. Cocrystals between pyridine or pyridine N-oxide derivatives and osmium tetroxide are characterized through various techniques and rationalized as σ-hole interactions using DFT calculations and several other computational tools. We propose the term "osme bond" (OmB, Om=Fe, Ru, Os, (Hs)) for naming the noncovalent interactions wherein group 8 elements have the role of the electrophile. The word osme is the transcription of ὀσμή, the ancient Greek word for smell that was used to name the heaviest group 8 element in relation to the smoky odor of its tetroxide.

Molecular Electrostatic Potential and Noncovalent Interactions in Derivatives of Group 8 Elements

In this communication experimental and theoretical results are reported affording strong evidence that interactions between electron rich atoms and the metal of tetroxide anions of group 7 elements are a new case of attractive and σ-hole interactions. Single crystal X-ray analyses, molecular electrostatic potentials, quantum theory of atoms-in-molecules, and noncovalent interaction plot analyses show that in crystalline permanganate and perrhenate salts the metal in Mn/ReO4- anion can act as electron acceptors, the oxygen of another Mn/ReO4- anion can act as the donor and supramolecular anionic dimers or polymers are formed. The name matere bond (MaB) is proposed to categorize these noncovalent interactions and to differentiate them from the classical metal-ligand coordination bond.

Anion⋅⋅⋅Anion Interactions Involving σ-Holes of Perrhenate, Pertechnetate and Permanganate Anions.

The single crystal X-ray structures of a series of p-halogenated Fmoc phenylalanines highlight the role of halogen bonding in their supramolecular organization in the solid state. The amino acids showing the occurrence of halogen bonding resulted in gels with the strongest mechanical properties. All gelation parameters could be ranked according to halogen atom polarizability, i.e., halogen bond strength.

/pdf/halogen-bonding-modulates-hydrogel-formation-from-fmoc-amino-2eyhae4fls.pdf

Halogen bonding modulates hydrogel formation from Fmoc amino acids

Interactions in crystalline tetrachloridoaurates of acetylcholine and dimethylpropiothetine are characterized by Au⋅⋅⋅Cl and Au⋅⋅⋅O short contacts. The former interactions assemble the AuCl4- units into supramolecular anionic polymers, while the latter interactions append the acetylcholine and propiothetine units to the polymer. The distorted octahedral geometry of the bonding pattern around the gold center is rationalized on the basis of the anisotropic distribution of the electron density, which enables gold to behave as an electrophile (π-hole coinage-bond donor). Computational studies prove that gold atoms in negatively charged species can function as acceptors of electron density. The attractive nature of the Au⋅⋅⋅Cl/O interactions described here complement the known aurophilic bonds involved in gold-centered interactions.

Andrea Pizzi

Papers

A halogen bond-donor amino acid for organocatalysis in water

Molecular Electrostatic Potential and Noncovalent Interactions in Derivatives of Group 8 Elements

Anion⋅⋅⋅Anion Interactions Involving σ-Holes of Perrhenate, Pertechnetate and Permanganate Anions.

Halogen bonding modulates hydrogel formation from Fmoc amino acids

Anion⋅⋅⋅Anion Coinage Bonds: The Case of Tetrachloridoaurate