Implicit Reaction Research Articles

Modeling Ultrafast Solvated Electronic Dynamics Using Time-Dependent Density Functional Theory and Polarizable Continuum Model

A first-principles solvated electronic dynamics method is introduced. Solvent electronic degrees of freedom are coupled to the time-dependent electronic density of a solute molecule by means of the implicit reaction field method, and the entire electronic system is propagated in time. This real-time time-dependent approach, incorporating the polarizable continuum solvation model, is shown to be very effective in describing the dynamical solvation effect in the charge transfer process and yields a consistent absorption spectrum in comparison to the conventional linear response results in solution.

Position–item associations play a role in the acquisition of order knowledge in an implicit serial reaction time task.

Knowledge of sequential regularities plays a key role in forms of explicit and implicit memory, such as working memory and motor skills. Despite important advances in the study of sequence knowledge in the past century, the theoretical development of implicit and explicit memory has occurred separately. Unlike the literature on implicit sequence learning, the explicit learning literature differentiates between 2 forms of representation of serial structure, chaining (C is the item following B in the sequence A-B-C-D) and ordinal position knowledge (C is the 3rd item). In 3 experiments, we demonstrate that these 2 forms of sequence knowledge can be acquired in implicit sequence learning. In Experiment 1, 2 trained sequences were recombined at transfer such that the strength of (a) associations between serial positions and sequence elements as well as (b) associations between successive sequence elements could be estimated. In Experiment 2, we compared sequence elements placed at the trained versus untrained serial position. Experiment 3 reduced cues that can be used to determine the start of a sequence within the stream of trials. Our results suggest that the discussion held in explicit memory research about different forms of representation of sequences knowledge also is relevant for implicit sequence learning.

The Proactive Control of Stereotype Activation

Stereotypes are typically conceived of as controlled through conscious willing. We propose that goals can lead to stereotype control even when the goals are not consciously noted. This is called proactive control since goal pursuit occurs not as a reaction to a stereotype having been activated and having exerted influence, but as an act of goal shielding that inhibits stereotypes instead of activating them. In two experiments proactive control over stereotypes toward African Americans was illustrated using a lexical decision task. In Experiment 1, participants with egalitarian goals showed slower responses to stereotypic words when following an African American male face (relative to following a White face). Experiment 2 illustrated African American faces facilitated responses to stimuli relevant to egalitarian goals; White faces did not. Together, these studies indicate that, without consciously trying, participants with egalitarian goals’ implicit reaction to African Americans included triggering fairness goals and inhibiting stereotypes.

Scales in the fine structure of the magnetic dipole resonance: A wavelet approach to the shell model

The r-process constitutes one of the major challenges in nuclear astrophysics. Its astrophysical site has not yet been identified but there is observational evidence suggesting that at least two possible sites should contribute to the solar system abundance of r-process elements and that the r-process responsible for the production of elements heavier than Z=56 operates quite robustly producing always the same relative abundances. From the nuclear-physics point of view the r-process requires the knowledge of a large number of reaction rates involving exotic nuclei. These include neutron capture rates, beta-decays and fission rates, the latter for the heavier nuclei produced in the r-process. We have developed for the first time a complete database of reaction rates that in addition to neutron-capture rates and beta-decay half-lives includes all possible reactions that can induce fission (neutron-capture, beta-decay and spontaneous fission) and the corresponding fission yields. In addition, we have implemented these reaction rates in a fully implicit reaction network. We have performed r-process calculations for the neutrino-driven wind scenario to explore whether or not fission can contribute to provide a robust r-process pattern.

Network calculations for r-process nucleosynthesis

The r-process is known to be responsible for the synthesis of about half of the elements heavier than iron, nevertheless its astrophysical site has not yet been clearly ascertained, but observations indicate that at least two possible sites should contribute to the solar system abundance of r-process elements. The r-process being responsible for the production of elements heavier than Z = 56 operates rather robustly always resulting in a similar relative abundance pattern. From the nuclear-physics point of view the r-process requires the knowledge of a large number of reaction rates involving exotic nuclei that are not accessible by experiment and data have to be provided by theoretical predictions. We have developed for the first time a complete database of reaction rates that in addition to neutron-capture rates and β-decay half-lives includes the dominant reactions that can induce fission (neutron-capture, β-decay and spontaneous fission) and the corresponding fission yields. In addition, we have implemented these reaction rates in a fully implicit reaction network. The influence of the nuclear physics input constituted in the reaction rates based on the two mass models FRDM and ETFSI and on the astrophysical conditions simulating a cold or hot environment are examined.

A fully adaptive reaction–diffusion integration scheme with applications to systems biology

Adaptive integration schemes for ODE systems typically function by adjusting the time step size so as to keep the truncation error below some desired value. For adaptive integration of PDE systems involving coupled kinetic reaction and diffusion operations, truncation error arises not only from the individual propagators but also from their method of coupling. A common second-order accurate method for coupling operators is Strang’s method of operator splitting. We derive an expression for the truncation error resulting from Strang splitting reaction and diffusion operators for an arbitrary number of spatial dimensions, and demonstrate its use in adaptive time step algorithms. In addition, we present explanations of the second order implicit reaction and diffusion operators, and their individual error calculations used in our implementation of the scheme. Finally, using example simulations we discuss the use of this calculation for problems in systems biology.

A combined explicit-implicit method for high accuracy reaction path integration

We present the use of an optimal combined explicit-implicit method for following the reaction path to high accuracy. This is in contrast to most purely implicit reaction path integration algorithms, which are only efficient on stiff ordinary differential equations. The defining equation for the reaction path is considered to be stiff, however, we show here that the reaction path is not uniformly stiff and instead is only stiff near stationary points. The optimal algorithm developed in this work is a combination of explicit and implicit methods with a simple criterion to switch between the two. Using three different chemical reactions, we combine and compare three different integration methods: the implicit trapezoidal method, an explicit stabilized third order algorithm implemented in the code DUMKA3 and the traditional explicit fourth order Runge-Kutta method written in the code RKSUITE. The results for high accuracy show that when the implicit trapezoidal method is combined with either explicit method the number of energy and gradient calculations can potentially be reduced by almost a half compared with integrating either method alone. Finally, to explain the improvements of the combined method we expand on the concepts of stability and stiffness and relate them to the efficiency of integration methods.

Introduction: Icon, Image, and Text in Modern Jewish Culture

In recent years, scholars of Judaism have increasingly turned to consider the relationship between Judaism and art. These studies include, but are by no means limited to, Richard Cohen's Jewish Icons: Art and Society in Modern Europe (California, 1998), Elliot Wolfson's Through a Speculum that Shines: Vision and Imagination in Medieval Jewish Mysticism (Princeton, 1994), Vivian Mann's Jewish Texts on the Visual Arts (Cambridge, 2000), Kaiman Bland's The Artless Jew: Medieval and Modern Affirmations of the Jew (Princeton, 2000), and Margaret Olin's, The Nation without Art: Examining Modern Discourses on Jewish Art (Nebraska, 2002). Scholarly interest in the relation between Judaism and art stems not only from a consideration of contemporary Jewish artistic expression, but perhaps even more fundamentally from an explicit or implicit reaction to nineteenth-century European musings on this relation. Particularly in the GermanJewish context, the question of Judaism's relation to art was paramount, not only within internal Jewish debates about the meanings of modern Jewish identity but also in conversations, between Jews and nonJews alike, about Judaism's compatibility with modernity in particular and the history of western civilization more generally. Contemporary scholarly attempts to retrieve strands of pre-modern Jewish theological and philosophical affirmations of vision and visuality, such as Bland's, Mann's and Wolfson's, mentioned above, are themselves predicated on the nineteenth and twentieth-century scholarly denials of visuality in Jewish thought and culture, as is Richard Cohen's attempt to detail Jewish interaction with the visual arts and the role of visual

The Compressed Hydrogen Bond in a Molecular Proton Cage

Analysis using the theory of atoms in molecules and natural bond orbital theory of the fully optimized structure of the inside-protonated form of 1,6-diazabicyclo[4.4.4]tetradecane reveals that the encapsulated proton is engaged in a short-strong though asymmetric H-bond with covalent character. The symmetric conformer with the proton in the center of the cage was found to be a transition state with a very low barrier to proton transfer along the N···N axis. Both an implicit reaction field model (IEF−PCM) and explicit placements of chloride counterions, suggested by a published X-ray crystal structure, were found to modify the position of the proton and the strength of the H-bond. An external counterion placed along the N···N axis and near one of the bridgehead nitrogens is most effective in weakening this very hydrophobically shielded diamine H-bond. The results of this study are relevant to ongoing issues about the possible participation of unusually strong H-bonds in enzymatic catalysis.

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Moral Interest and Religious Truth: On the Relationship between Morality and Religion in Novalis

Whereas it is obvious and well‐known that the relationship between morality and religion plays an important role in Enlightenment discourse, it has not yet been properly recognised that this is equally true for the view of some early Romantics such as Friedrich von Hardenberg. An investigation against the Kantian background shows the moral‐religious relationship, as established by Novalis, to be an implicit reaction to the problems which are contained in the ‘Moraltheologie’ of the Enlightenment period. Kant, largely sharing a neological approach, tends to reduce religion to morality and even to instrumentalise the former for the sake of the latter. Hardenberg responds to the difficulties implied in this conception by liberating religion from any reduction and instrumentalisation, but, remarkably, not at the expense of his moral concern, and while retaining an intimate relation between religion and morality. Novalis's view can be explained by referring to his notion of indirect pursuit of goals, through which it is also related to his Early Romantic concept of art.

The implicit reaction function of the Central Bank of the Republic of Turkey

Reviewing the implicit reaction function estimation under different specifications, it appears that the Central Bank of the Republic of Turkey (CBRT) responds to the lagged inflation rate rather than the forward one, M2Y growth is targeted on an annual basis and a serious output targeting policy was implemented while neither real nor nominal depreciation of the foreign currency basket was taken into consideration during the period 1989:07–1997:03. Also, we conclude that the CBRT does not target currency issued, M2, net domestic assets or net foreign assets nor does it take any of the budget deficit measures into account while determining its monetary policy.

Implicit but not Explicit Feature Binding in a Balint's Patient

Visual perception is often conceptualized as a process of extracting visual attributes from the stimulus, from simple features like colour and orientation to high-level identities of words and objects. However, an important further task forvision is to solve the “binding problem”—to determinewhich visual attributes go together to form one object (e.g. Treisman & Gelade, 1980). Recent evidence suggests thatthe parietal lobes are critical forfeaturebinding (e.g.Friedman-Hill, Robertson, & Treisman, 1995). We examined a patient with bilateral parietooccipital damage and found that, while he was at chance on an explicit binding task (reporting which of two words was coloured), an implicit reaction time measure showed thatcorrectcolour-word bindings were nonetheless represented in his visual system. These results (1) show a dissociation between implicit and explicit binding and (2) suggest that the parietal lobes may be critical for explicit but not implicit binding. The implications of these results for feature integration theory are discussed.