A nonseparable method for time-dependent quantum simulations of large polyatomic systems is presented and applied to the dynamics of the I2Ar17 cluster, following electronic excitation of the iodine molecule. The new method is an extension of the classical separable potential (CSP) approximation, in which the evolution of each mode is governed by a time-dependent mean potential due to the other modes and the total wave packet is a product of single mode wave functions. The computational effectiveness of the CSP approach stems from the use of classical molecular dynamics (MD) trajectories, carried out at the outset of the procedure, for obtaining the effective single-mode potentials. The present method generalizes the CSP scheme by a configuration interaction (CI) treatment, in which the total wave packet is represented as a linear combination of separable terms with coefficients determined from the time-dependent Schrodinger equation. The single mode wave functions for each configuration are propagated along effective potentials that are generated using individual classical trajectories. The classical MD simulation is also used for simplifying the dynamical equations for the CI coefficients. Thus, the selection of correlations that are included quantum mechanically is guided by classical mechanics, which is the basis for the computational efficiency of this approach. The CI wave packet for the I2Ar17 system with 51 vibrational degrees of freedom was propagated for 500 fs following I-2 (B<–X) excitation. About 1500 configurations proved sufficient for convergence of the CI series. The separable approximation to the wave function holds for 60 fs and begins to break down upon the first collision of the iodine atoms with argons. After the second iodine-argon collision this breakdown is almost complete, and at t = 500 fs the CSP term represents less than 5% of the correlated wave packet. Both absorption and resonance Raman spectra are, however, well described by the separable CSP method, since they are determined within the first 60 fs. The CI-CSP method offers very good accuracy due to inclusion of important correlation effects between different modes, while remaining computationally feasible for systems up to 100 degrees of freedom and more. (C) 1997 American Institute of Physics.
A time-dependent self-consistent field approach is used to simulate a He atom colliding with an Ar-13 cluster. Direct energy transfer during the collision, and energy redistribution among the vibrational degrees of freedom of the anharmonic cluster following the collision, are studied. An important advantage of the method used is that quantum state-to-state transition cross sections can be computed for large systems. The following main results are obtained: (1) The process can be interpreted in terms of a direct collision, followed by post-collision energy redistribution in Ar-13, a description that appears only when the cluster vibrations are not described by the eigenstates of this system. A time scale of one picosecond is found for the post-collision intracluster energy distribution. (2) The long-time final state distribution of Ar-13 is less state selective than the distribution immediately after the impact, but it is also not completely statistical. (3) There are state-to-state transitions having cross sections of observable magnitude. (4) The dominant transitions are those involving zero, one, and two `'phonon'' excitations. Some of the `'two phonon'' excitations have cross sections comparable to strong `'single phonon'' transitions. (5) Different types of modes show different propensities for excitations in the collision, in close relation to the geometric character of the modes. The results show that the TDSCF approximation is a powerful tool for treating both direct collision dynamics and collision-induced dynamics in scattering of large anharmonic systems. (C) 1997 American Institute of Physics.
The authors have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels ≥1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the anal. performance of these electrodes were studied in detail and optimized. The organization of the monolayers was examd. by a variety of surface techniques such as XPS, FTIR, and electrochem. Structuring and understanding the solid-liq. interface at the mol. level are essential for designing probes with superior anal. characteristics. [on SciFinder(R)]
We have developed a selective electrode for chromium(VI), based on a self-assembled monolayer of 4-(mercapto-n-alkyl)pyridinium on gold surfaces, which exhibits unique speciation capabilities. Cr(VI) levels as low as 1 parts per trillion can be detected using a 4-(mercaptoethyl)pyridinium monolayer. The different parameters that govern the analytical performance of these electrodes have been studied in detail and optimized. In addition, the organization of the monolayers has been examined by a variety of surface techniques such as XPS, FT-IR, and electrochemistry. Our results show that structuring and understanding the solid-liquid interface at the molecular level are essential for designing probes with superior analytical characteristics.[on SciFinder (R)]
A disorganized monolayer of ω-mercaptoalkanesulfonic acid, HS(CH2)nSO3H, serves as selective mol. sieve, which is selectively permeable to electroactive species. Due to the strong acidity of the sulfonic acid moiety the monolayers are highly charged in aq. soln. throughout most of the pH range. Cyclic voltammetry of neg. charged inorg. species, such as hexacyanoferrate, clearly shows the repulsion of these species from the solid-liq. interface. Cyclic voltammetry of pos. charged ions, e.g., hexaammineruthenium(III), is not influenced at all by the presence of a mercaptodecanesulfonic acid monolayer, suggesting a partial coverage of the gold substrate by the monolayer. Fe(III) ions were detd. by Osteryoung square wave voltammetry in the presence of both inorg. anions and sol. org. species. [on SciFinder(R)]
On the Measurement of Inequality under Uncertainty
with Itzhak Gilboa and David Schmeidler
To take into account both ex ante and ex post inequality considerations, one has to deal with inequality and uncertainty simultaneously. Under certainty, much of the literature has focused on "comonotonically linear" indices: functionals that are linear on cones of income profiles that agree on the social ranking of the individuals. This family generalizes both the Gini index and the egalitarian index(minimal income). However, it does not include functionals such as the average of expected-Gini and Gini-of-expectation. In contrast, the family of min-of-means functionals is rich enough for this purpose.
Rationality, Nash Equilibrium and Backward Induction in Perfect Information Games
We say that a player is certain of an event A if she assigns probability 1 to A. There is common certainty (CC) of A if the event A occurred, each player is certain of A, each player is certain that every other player is certain of A, and so forth. It is shown that in a generic perfect-information game the set of outcomes that are consistent with common certainty of rationality (CCR) at the beginning of the game coincides with the set of outcomes that survive one deletion of weakly dominated strategies and then iterative deletion of strongly dominated strategies. Thus, the backward induction outcome is not the only outcome that is consistent with CCR. In particular, cooperation in Rosenthal's (1981) centipede game, and fighting in Selten's (1978) chainstore game are consistent with CCR at the beginning of the game. Next, it is shown that, if in addition to CCR, there is CC that each player assigns a positive probability to the true strategies and beliefs of the other players, and if there is CC of the support of the beliefs of each player, then the outcome of the game is a Nash equilibrium outcome.
Thirty years ago, Samuel Huntington criticized Western aid policy toward new states that assumed that economic improvement in the standard of living coupled with democratic institutions would yield a more stable and democratic state-building process. An extensive political economic literature on the developmental state has since emerged that explores the complex relationship between state capacity, economic development and democracy, much of it critical of both the economist assumption, and the importance of democracy in achieving sustainable growth, at least in the initial stages of statehood. This literature. however, does not specifically relate to the impact of international aid affects state consolidation despite its critical role in the initial stages of new states. The paper explores how international aid affects on new state formation in the 1990s as reflected by the Palestinian experience, and more specifically whether Huntington's criticism is valid today regarding the international aid regime toward the Palestinian Authority established in May 1994. It shows that international aid was initially based on economist assumptions, changed course to reflect the importance of the state, and now must seek a better balance between the centralization of power, developing state capacity, and promoting civil society. Key words - democracy, economic development, international aid, state-building, Palestinian Authority, World Bank
Thirty years ago, Samuel Huntington criticized Western aid policy toward new states that assumed that economic improvement in the standard of living coupled with democratic institutions would yield a more stable and democratic state-building process. An extensive political economic literature on the developmental state has since emerged that explores the complex relationship between state capacity, economic development and democracy, much of it critical of both the economist assumption, and the importance of democracy in achieving sustainable growth, at least in the initial stages of statehood. This literature, however, does not specifically relate to the impact of international aid affects state consolidation despite its critical role in the initial stages of new states. The paper explores how international aid affects on new state formation in the 1990s as reflected by the Palestinian experience, and more specifically whether Huntington's criticism is valid today regarding the international aid regime toward the Palestinian Authority established in May 1994. It shows that international aid was initially based on economist assumptions, changed course to reflect the importance of the state, and now must seek a better balance between the centralization of power, developing state capacity, and promoting civil society.
Bite wounds of the chest wall in small dogs can extend into the thorax and can be associated with severe damage to chest wall muscles, ribs, and lungs. Two major problems associated with the management of these wounds are lack of sufficient muscle tissue for chest wall reconstruction, and difficulty draining the extensive dead space created in the chest wall. We describe a simple method to overcome these problems. The bite wound areas were surgically explored and all devitalized soft tissue was debrided. The pleural cavity was explored, intrathoracic injuries repaired, and a thoracic drainage tube was placed. Ribs in the injured area were stabilized in anatomic position by means of heavy gauge sutures passed around pairs of adjacent ribs, thus creating a scaffolding for soft tissues. Viable muscle and subcutaneous tissues were apposed as much as possible and the skin closed over the defect. Eleven small dogs were treated using this technique. All dogs had severe injuries to the thoracic wall muscles and eight dogs had multiple rib fractures. There was no evidence of chest wall instability in any of the dogs after surgery. Nine dogs survived the injury and were reevaluated 3 to 32 months after surgery. All were clinically normal. One dog developed wound infection and pyothorax, caused by insufficient debridement of injured muscle tissue, and died 10 days after surgery. A second dog died 24 hours postoperatively of undetermined causes. (C) Copyright 1997 by The American College of Veterinary Surgeons
Monoclonal antibody (MAb) CC49 binds to human tumour-associated glycoprotein termed TAG-72. CC49 is a second-generation MAb with higher affinity to TAG-72 than the original MAb B72.3. CC49 was applied to 42 samples from different canine mammary tumours, belonging to seven different histopathological types. Immunoreactivity was detected by the use of an avidin-biotin complex immunoperoxidase method. Most sections from all types of mammary neoplasm reacted with this MAb. Normal tissue did not stain or stained only weakly. The results of this study suggest CC49 has selective immunoreactivity for a variety of canine mammary tumours, which seems superior to that reported with MAb 72.3. These results support the proposal for further study of diagnostic and therapeutic uses of CC49 in the management of canine mammary tumours.
Recently the Jahn-Teller model was extended to treat (reactive) scattering processes. The present study is devoted to possible effects of a degenerate vibronic coupling (DVC) on resonances. The main conclusions are: (a) The DVC affects dramatically the state-to-state transition processes and as a result it shuffles resonances attached to given transitions and may cause existing resonances to be masked by other processes. (b) The DVC may affect the widths and the heights of resonances but change only slightly their position.
