bluuebunny/crossref_metadata_2025 huggingface dataset:
Hurricane potential intensity from an energetics point of view
Authors: Shen Weixing
Published: November 2004

This article describes an approach to hurricane potential intensity with a model that considers total kinetic energy balance within a hurricane. The major kinetic energy source and sink are the kinetic energy converted from sea surface entropy flux and the surface dissipation, respectively, but the conversion efficiency is radius‐dependent in this model. Also, the internal conversion due to convectively available potential energy (CAPE) as a source is considered. In contrast to previous potential intensity models, energy balance in the entire hurricane is used to get its steady state. With this model, the roles of environmental sea surface temperature (SST), CAPE and some features of the hurricane itself in determining hurricane potential intensity are investigated. The results indicate that existence of CAPE may lead to the steady state (or potential intensity) appreciably different from the otherwise surface entropy flux conversion and surface dissipation balanced state, although CAPE contribution to kinetic energy generation is usually much smaller than that of the surface flux. It is interesting that hurricane potential intensity seems less dependent on the underlying SST than was shown with previous theoretical models. The results also suggest that hurricane size may affect its potential intensity in that larger‐sized hurricanes tend to have higher potential intensities. Copyright © 2004 Royal Meteorological Society
Can we believe predictions of climate change?
Authors: Mitchell John F. B.
Published: November 2004

Methods used to evaluate the ability of climate models to produce reliable estimates of future climate change are examined and assessed. © Crown copyright, 2004. Royal Meteorological Society
Subnucleolar distribution and organization of Vicia faba L. rDNA in situ
Authors: Long Hong , Sun Haijing , Zeng Xianlu , Hao Shui , Jiao Mingda
Published: November 2004

The distribution and organization of nucleolar DNA in Vicia faba L. was analyzed by specific cytochemical staining using NAMA‐Ur. The results showed that nucleolar DNA was distributed in the FCs and at the FC/DFC junctions. Statistical analysis showed that the rRNA genes occupied about one‐third of the total dense fibrillar component region. The rDNA was condensed in some regions and uncondensed in others. Nucleolus‐associated chromatin extended from outside the nucleolus to the periphery of the FCs via nucleolar channels, suggesting a possible origin for nucleolar DNA.
Review and proposed action of alpha‐fetoprotein growth inhibitory peptides as estrogen and cytoskeleton‐associated factors
Authors: Mizejewski Gerald , Smith George , Butterstein George
Published: November 2004

The (H) human growth‐promoting factor, alpha‐fetoprotein (AFP), has been reported to possess a growth inhibitory motif as an occult epitope in the compactly folded circulating form of the protein. Intermediate unfolded forms of the human HAFP molecule induced by stress, shock, and high ligand concentrations have revealed the presence of an encrypted growth‐suppressive segment on the third domain of HAFP. A purified linear synthetic 34‐mer segment termed the “growth inhibitory peptide” (GIP) exhibits various oligomeric forms with complex aggregation behaviors, in which dominant trimeric forms were found to be suppressive in assays of estrogen‐induced growth. While several amino acid analogs of the cysteines of the GIP retained inhibitory activity, heavy metal binding and pre‐incubation of the peptides with a variety of cations and hormone ligands were found to influence the outcomes of growth bioassays. Smaller segments of the original 34‐mer were each found to display growth activities of their own, with the middle segment (P149b) also showing hydrophobic dye‐binding properties. Studies of amino acid sequence identity further revealed that the GIP sequences displayed identity/similarity matches to both cytoplasmic and nucleus‐cytoskeleton‐associated proteins, and experimental evidence served to support these findings. That is, the peptide was capable of modulating tubulin polymerization, cell shape, and cell‐surface aggregation phenomena reminiscent of a microtubule‐associated protein. Immunofluorescence studies further pinpointed the localization of the GIP to cytoplasmic regions of high cytoskeletal density in the cell. Because of the involvement of the GIP in experimental models of the estrogen receptor/cytoskeleton, a mechanism of action is forwarded in which the linear GIP is proposed to be a G‐coupled receptor binding ligand that is translocated across the plasma membrane via receptor‐mediated endocytosis. Thus, it was predicted that the linear GIP and possibly its peptidic segments serve as decoy ligands to cell‐surface receptors in order to gain access to the cytoplasmic compartment of the cell.
Operational, economic and mission elements in not‐for‐profit organizations: the case of the Chicago Symphony Orchestra
Authors: Olson John R. , Belohlav James A. , Boyer Kenneth K.
Published: November 2004

The term not‐for‐profit often brings to mind the idea of an altruistic organization serving society. The reality is that the not‐for‐profit is a far more complex organization that is responsible to diverse groups of stakeholders. Unlike for‐profit organizations, not‐for‐profit (NFP) organizations have to focus on dual, and often conflicting, goals relating to fulfilling their overall mission while also generating enough revenue to maintain their operating structures. In order to better understand the nature of the dual orientation of the NFP organization, the behavior of Chicago Symphony Orchestra (CSO) patrons using the CSO website is viewed. Specifically, this study examines data for individuals purchasing CSO concert tickets on‐line during an 8‐month period in 2000–2001. MANOVA and ANOVA statistical procedures are used to analyze the effects of both the economic and mission related orientations operationalized through the e‐service encounter. Further, we view data from the on‐line ticketing function relative to the labor costs of the Chicago Symphony Orchestra.
Anchoring world and time in biblical Hebrew
Authors: HATAV GALIA
Published: November 2004

One of the most puzzling issues in biblical Hebrew has been its verbal system. In this article, I deal with one of the forms, namely wayyiqtol, suggesting that its meaning is compositional, calculated from three components: a verbal base and two morphemes. The verbal base is shown to be modal, involving quantification over possible worlds. The two morphemes prefixed to the verbal base restrict its modal nature. One morpheme functions like the definite article in a noun phrase; it picks out one of the possible worlds, the familiar actual world (Wo), and anchors the event into it. The other morpheme builds a reference-time, locating the event in time.
Twelve-year course and outcome of bulimia nervosa
Authors: FICHTER MANFRED M. , QUADFLIEG NORBERT
Published: November 2004

Background. Since little is known about the long-term course and outcome of bulimia nervosa, the authors designed a 12-year prospective longitudinal study with five cross-sectional assessments based on a large sample of consecutively treated females with bulimia nervosa (purging type) (BN-P).

Method. One hundred and ninety-six females with BN-P were assessed (1) at the beginning of treatment, (2) at the end of treatment, (3) at 2-year follow-up, (4) at 6-year follow-up, and (5) at 12-year follow-up. In self-ratings as well as expert ratings based on interviews we assessed specific eating-disorder and general psychopathology.

Results. The general pattern of results over time showed substantial improvement during treatment, slight (in most cases non-significant) decline during the first two years after the end of treatment, and further improvement and stabilization until 12-year follow-up. At that point the majority of patients (70·1%) showed no major DSM-IV eating disorder, 13·2% had eating disorders not otherwise specified, 10·1% had BN-P and 2% had died. Very few had undergone transition to anorexia nervosa or binge-eating disorders. Logistic regression analyses showed that psychiatric co-morbidity was the best and most stable predictor for eating-disorder outcome at 2, 6 and 12 years.

Conclusions. Course and outcome of BN-P was generally more favourable than for anorexia nervosa.
Impaired divided attention predicts delayed response and risk to relapse in subjects with depressive disorders
Authors: MAJER M. , ISING M. , KÜNZEL H. , BINDER E. B. , HOLSBOER F. , MODELL S. , ZIHL J.
Published: November 2004

Background. This study addresses the complex relationship between cognitive function and the course of depression.

Method. A sample of patients (n=73) in a depressive episode (major depression or bipolar disorder) was tested with a comprehensive battery of attention and executive tasks at both admission and discharge. In addition, response to pharmacological treatment and remission was assessed with standardized rating scales. Nineteen patients, recovered from depression, were re-investigated 6 months after discharge to determine whether specific cognitive parameters were related to subsequent relapse.

Results. On admission, patients were impaired in almost all cognitive tasks. At discharge, we found a significant reduction in psychopathology, but only marginal cognitive improvements. Non-responders after 4 weeks of antidepressive medication and subjects who did not achieve remission prior to discharge were specifically impaired in divided attention on admission (p<0·05). In addition, a trend was found for the association between impaired divided attention at discharge and an elevated risk to relapse (p<0·10).

Conclusions. We observed generalized cognitive impairment in most cognitive domains in acute depression. Cognitive impairments were still within abnormal ranges at discharge but less distinct. Divided attention performance predicted response to treatment, remission of symptoms, and risk to relapse. Impaired divided attention capacity can be explained either by reduced attentional resources or impaired activation and/or top-down control of attentional resources by the central executive.
Genetic effects on alcohol dependence risk: re-evaluating the importance of psychiatric and other heritable risk factors
Authors: KNOPIK VALERIE S. , HEATH ANDREW C. , MADDEN PAMELA A. F. , BUCHOLZ KATHLEEN K. , SLUTSKE WENDY S. , NELSON ELLIOT C. , STATHAM DIXIE , WHITFIELD JOHN B. , MARTIN NICHOLAS G.
Published: November 2004

Background. Genetic influences have been shown to play a major role in determining the risk of alcohol dependence (AD) in both women and men; however, little attention has been directed to identifying the major sources of genetic variation in AD risk.

Method. Diagnostic telephone interview data from young adult Australian twin pairs born between 1964 and 1971 were analyzed. Cox regression models were fitted to interview data from a total of 2708 complete twin pairs (690 MZ female, 485 MZ male, 500 DZ female, 384 DZ male, and 649 DZ female/male pairs). Structural equation models were fitted to determine the extent of residual genetic and environmental influences on AD risk while controlling for effects of sociodemographic and psychiatric predictors on risk.

Results. Risk of AD was increased in males, in Roman Catholics, in those reporting a history of major depression, social anxiety problems, and conduct disorder, or (in females only) a history of suicide attempt and childhood sexual abuse; but was decreased in those reporting Baptist, Methodist, or Orthodox religion, in those who reported weekly church attendance, and in university-educated males. After allowing for the effects of sociodemographic and psychiatric predictors, 47% (95% CI 28–55) of the residual variance in alcoholism risk was attributable to additive genetic effects, 0% (95% CI 0–14) to shared environmental factors, and 53% (95% CI 45–63) to non-shared environmental influences.

Conclusions. Controlling for other risk factors, substantial residual heritability of AD was observed, suggesting that psychiatric and other risk factors play a minor role in the inheritance of AD.
Birth cohort studies in psychiatry: beginning at the beginning
Authors: COLMAN IAN , JONES PETER B.
Published: November 2004

Longitudinal formulations of psychiatric illness have long been familiar. In the 19th century, Thomas Clouston wrote about developmental insanity in young men, presaging modern views of schizophrenia as having some of its origins or first manifestations in early life (Clouston, 1891; O'Connell et al. 1997). At the same time, Sigmund Freud was creating his system of psychoanalysis to understand hysterical conversion and other aspects of adult psychology as sequelae of early psychological events. Now, within an epidemiological and neuroscientific framework, we are beginning to understand that a variety of psychiatric disorders, including those of later life, such as cognitive decline and dementia may be the final common pathway of a long chain of mutable events (Richards et al. 2004). Just as in clinical neurology, where one is taught to place the causal lesion as high as possible so, too, in psychiatry we should look for the seeds of causality earlier rather than later in life.
The development of discourse referencing in Cantonese-speaking children
Authors: WONG ANITA M.-Y. , JOHNSTON JUDITH R.
Published: November 2004

The ability to make clear reference in connected discourse was examined in children learning Cantonese, a Chinese language where noun phrase constituents, whatever their grammatical role, are omissible from sentences under discourse conditions that are not well-understood. Forty-three typically developing children aged 3;0, 5;0, 7;0 and 12;0 told 16 stories based on picture sequences. A panel of adult native Cantonese speakers was asked to judge the referential adequacy of each child's stories by identifying the character the child was talking about in 32 targeted referential acts. The targeted acts were of three sorts: MAINTENANCE of a known character, INTRODUCTION of a second new character, and REINTRODUCTION of a known character. Reference was judged to be adequate when 3 out of 4 ‘listeners’ could successfully identify the character. Children's referential expressions were most adequate for Maintenance, less adequate for Introduction, and least adequate for Reintroduction. The twelve- and seven-year-olds approached ceiling on all three functions. The five-year-olds scored poorly on Reintroduction, and the three-year-olds failed both Introduction and Reintroduction, despite knowledge of at least one of the possible linguistic forms required for these acts as evidenced in a sentence imitation task. Viewed within the framework of Levelt's (1989) discourse model, the data improve our understanding of the developmental period during which children learn to make appropriate presuppositions about the listener's knowledge and attentional states.
Measuring productive vocabulary of toddlers in low-income families: concurrent and predictive validity of three sources of data
Authors: ALEXANDER PAN BARBARA , ROWE MEREDITH L. , SPIER ELIZABETH , TAMIS-LEMONDA CATHERINE
Published: November 2004

This study examined parental report as a source of information about toddlers' productive vocabulary in 105 low-income families living in either urban or rural communities. Parental report using the MacArthur Communicative Development Inventory – Short Form (CDI) at child age 2;0 was compared to concurrent spontaneous speech measures and standardized language assessments, and the utility of each source of data for predicting receptive vocabulary at age 3;0 (Peabody Picture Vocabulary Test) was evaluated. Relations between language measures of interest and background variables such as maternal age, education, and race/ethnicity were also considered. Results showed that for the sample as a whole, parental report was moderately associated with other language measures at age 2;0 and accounted for unique variance in PPVT at age 3;0, controlling for child language skills derived from a standard cognitive assessment. However, predictive validity differed by community, being stronger in the rural than in the urban community. Implications of significant differences in background characteristics of mothers in the two sites are discussed.
On-line grammaticality judgments in French children and adults: a crosslinguistic perspective
Authors: KAIL MICHELE
Published: November 2004

This study examined the on-line processing of French sentences in a grammaticality judgment experiment. Three age groups of French children (mean age: 6;8, 8;6 and 10;10 years) and a group of adults were asked to detect grammatical violations as quickly as possible. Three factors were studied: the violation type: agreement violations (number and gender) vs. word order violations; the violation position: early vs. late in the sentence; the target type of the violations: intra vs. interphrasal. An example of an early interphrasal verbal agreement violation follows: ‘Chaque semaine la voisine remplissent le frigo après avoir fait les courses au marché’ (Every week the neighbour fill the fridge after shopping at the market). The main developmental results were the following: not surprisingly, children were always slower than adults in the detection of grammatical violations. At each age level, morphological violations were more rapidly detected than word order violations. Each age group was faster at judging sentences with later occurring violations and the position effect was especially strong in the youngest groups. Finally, intraphrasal violations were more rapidly detected than interphrasal ones, this effect being observed only in the oldest groups (i.e. 10;10 years and adults). The results were compared to previous on-line data obtained in modern Greek (Kail & Diakogiorgi, 1998) showing strong similarities, even though Greek is a very rich morphological language. These results are discussed within the framework of the Competition Model, outlining the necessity to incorporate new processing constraints into the model.
Acceleration sites of energetic ions upstream of the Earth's bow shock and in the magnetosheath: Statistical study on charge states of heavy ions
Authors: Keika K. , Nosé M. , Christon S. P. , McEntire R. W.
Published: November 2004

In order to identify acceleration sites of energetic ions upstream of the Earth's bow shock and in the dayside magnetosheath, we investigated energetic ion events observed by the Energetic Particles and Ion Composition (EPIC) instrument on board the Geotail spacecraft from 1995 to 2001. Energetic ion data obtained by the Ion Composition System (ICS) sensor were used to select “events,” that is, intervals when the 77–107 keV ion flux increased by more than two orders of magnitude within 10 min, and examine their spatial distribution and its geomagnetic activity dependence. Heavy ions with energy range of 9–210 keV/e detected by the Suprathermal Ion Composition Spectrometer (STICS) sensor were chosen to calculate the percentage of low‐charge‐state heavy ions (PLCS = (O+ + N+)/(O+ + N+ + O6+ + O7+)) in each event, and the events were classified into three groups: high‐charge‐state (HCS) events (PLCS ≤ 25%), intermediate (IM) events (25% < PLCS < 75%), and low‐charge‐state (LCS) events (PLCS ≥ 75%). The HCS and LCS events occurred at almost the same rate in geomagnetically quiet conditions (SYM‐H ≥ 0 nT), while the LCS events were observed more frequently than the HCS events in geomagnetically disturbed conditions (SYM‐H ≤ −30 nT). The percentage of the IM and LCS events summed was higher in disturbed conditions than in quiet conditions. The HCS and LCS events were frequently observed in the dawnside upstream region and in the duskside magnetosheath, respectively. The IM events occurred both in the dawnside upstream region and in the magnetosheath around noon. We conclude that energetic ion events including ions accelerated in the magnetosphere are dominant. Ions accelerated in the magnetosphere leak out from the duskside magnetopause, in particular when geomagnetic activity is high, and then most likely mix with ions accelerated at the bow shock on the way to the dawnside upstream region. The acceleration site of the HCS events is also discussed.
Effect of solar energetic particle (SEP) events on the radiation exposure levels to aircraft passengers and crew: Case study of 14 July 2000 SEP event
Authors: Iles R. H. A. , Jones J. B. L. , Taylor G. C. , Blake J. B. , Bentley R. D. , Hunter R. , Harra L. K. , Coates A. J.
Published: November 2004

We investigate the circumstances required for aircrew and passengers to experience an increased radiation exposure rate from a solar energetic particle (SEP) event occurring during a flight. The effects of the 14 July 2000 National Oceanic and Atmospheric Administration S3 class SEP event are examined using ground‐based and satellite measurements together with coincident measurements made using a tissue equivalent proportional counter (TEPC) on board a Virgin Atlantic Airways flight from London Heathrow to Hong Kong. In this paper we present the first measurements made during a SEP event using a TEPC at flight altitudes. Our results indicate that there were no increased radiation levels detected during the flight due to the SEPs, but the measurements agreed well with the CARI‐6 model calculations made using a heliocentric potential value derived immediately prior to the SEP event. In addition, a prolonged increase in the >85 MeV particle flux is observed for up to 2 days after the SEP onset by the SAMPEX spacecraft at latitudes >55°.
Historical burn area in western Canadian peatlands and its relationship to fire weather indices
Authors: Turetsky M. R. , Amiro B. D. , Bosch E. , Bhatti J. S.
Published: November 2004

Peatlands store the majority of soil carbon in many northern regions, yet their vulnerability to fire remains poorly understood. We used large‐scale mapping of fire and peatland distributions to explore patterns of burning at two spatial scales. On a landscape scale in central Alberta, we used spatially explicit distributions of peatlands and 50 years of fire perimeter maps to determine whether uplands burn more preferentially than peatlands. Burn area and ignition localities in central Alberta did not occur preferentially in uplands relative to bogs and fens. Extrapolating this result at a regional scale, we used the Peatlands of Canada database and 20 years of historical fire records to estimate annual burn areas for Alberta, British Columbia, Northwest Territories, and Saskatchewan peatlands. Peatland burn areas varied tremendously over time, with high fire activity in the early 1980s and mid‐1990s. On average, fires impacted 1850 km2 of peatland annually across this region of western Canada. Positive relationships between the area of peatland burned and weather variables calculated for each fire event using the Canadian Fire Weather Index, including maximum air temperatures and the duff moisture code, suggest that drier and/or warmer conditions likely would increase the burning of peatlands in western Canada.
Investigation of the North Brazil Current retroflection and North Equatorial Countercurrent variability
Authors: Fonseca Carlos A. , Goni Gustavo J. , Johns William E. , Campos Edmo J. D.
Published: November 2004

Eight years of TOPEX/Poseidon altimeter‐derived sea height anomaly and climatological hydrographic data are used to investigate the temporal and spatial variability of the North Brazil Current (NBC) retroflection and the North Equatorial Countercurrent (NECC). The NBC retroflection exhibits a mean position of 6.6°N ± 2.0°, with a strong annual signal and year‐to‐year variability. The annual cycle of its location follows the meridional migration of the ITCZ and the strength of the wind stress curl over the equatorial Atlantic. A marked shift in the annual mean location of the NBC retroflection is observed in 1998–1999 that appears to be linked to an increase in wind stress curl during this period. The mean latitude of the NECC is estimated to be 6.0°N ± 1.3°, with a semiannual cycle showing maximum northerly locations in February and August. The baroclinic transport of the NECC varies predominantly on an annual cycle with maximum transport of 12 Sv occurring in November.
WINDII thermosphere temperature perturbation for magnetically active situations
Authors: Lathuillère Chantal , Menvielle Michel
Published: November 2004

Oxygen red line data obtained by the Wind Imaging Interferometer (WINDII) on board the Upper Atmosphere Research Satellite (UARS) between 1992 and 1995 are used to retrieve thermosphere temperature perturbation associated with magnetic activity. Using a statistical approach, we found maximum temperature perturbations of ∼300 K at auroral latitudes. We show that the use of longitude sector magnetic indices allows a better characterization of the perturbation than the usual planetary indices. The magnetic activity dependence in the MSIS‐90 and DTM94 empirical models is qualitatively in excellent agreement with our results. However, empirical temperature perturbations are underestimated by ∼70%.
Rotation‐induced dust drift waves in planetary magnetospheres
Authors: Saleem H. , Haque Q.
Published: November 2004

The linear and nonlinear electrostatic waves are studied in rotating dusty plasmas. It is pointed out that rotation can introduce dust drift waves through Coriolis force in the planetary magnetospheres. This wave can couple with dust acoustic mode. Owing to Doppler shift the frequencies can be very small. Coriolis force effect may give rise to dipolar vortices in rotating dusty plasmas of planetrary magnetospheres. As an illustration, the results have been applied to Saturn's rings.
Frame transformation relations for fluxional symmetric rotor dimers
Authors: Crogman Horace T. , Harter William G.
Published: November 2004

The theory of frame transformation relation connecting body oriented angular momentum states and lab weakly coupled momentum states have been extended from rotor-electron to rotor-dimer systems. Coupling schemes are analyzed for weak and strong cases of correlation between lab and two different rotor body frames. It is shown that the frame transformation relation is a purely quantum effect at low angular momentum but an approach to a classical limit for high J. Symmetry analysis of frame transformation is compared to eigensolutions of model coupling Hamiltonian.
Photodissociation of CCH: Classical trajectory calculations involving seven electronic states
Authors: Apaydın Gökşin , Fink William H. , Jackson William M.
Published: November 2004

The photodissociation dynamics of ethynyl radical, C2H, involving seven electronic states is studied by classical trajectory calculations. Initial values of the trajectories are selected based on relative absorption intensities calculated by Mebel et al. The energies and the derivatives are interpolated by three-dimensional cubic spline interpolator using an extended data pool. Mean square errors and standard deviations in interpolation of energies for 450 data points are found to be in the range 3.1×10−6–1.4×10−5 and 1.7×10−3–3.8×10−3 hartrees, respectively. The photofragments of C2 and H are produced mainly in the X 1Σg+, a 3Πu, b 3Σg−, c 3Σu+, A 1Πu, B 1Δg electronic states of C2 as product. The avoided crossings do not appear to be in the main dissociation pathways. The internal distributions are in good accord with the experimental results where comparison is possible, suggesting that the fragmentation mechanism of C2H2 into C2 and H is a two step process involving C2H radical as an intermediate with a life time long enough to allow complete collection of the phase space in the experiments.
Atomic spectral methods for molecular electronic structure calculations
Authors: Langhoff P. W. , Boatz J. A. , Hinde R. J. , Sheehy J. A.
Published: November 2004

Theoretical methods are reported for ab initio calculations of the adiabatic (Born–Oppenheimer) electronic wave functions and potential energy surfaces of molecules and other atomic aggregates. An outer product of complete sets of atomic eigenstates familiar from perturbation-theoretical treatments of long-range interactions is employed as a representational basis without prior enforcement of aggregate wave function antisymmetry. The nature and attributes of this atomic spectral-product basis are indicated, completeness proofs for representation of antisymmetric states provided, convergence of Schrödinger eigenstates in the basis established, and strategies for computational implemention of the theory described. A diabaticlike Hamiltonian matrix representative is obtained, which is additive in atomic-energy and pairwise-atomic interaction-energy matrices, providing a basis for molecular calculations in terms of the (Coulombic) interactions of the atomic constituents. The spectral-product basis is shown to contain the totally antisymmetric irreducible representation of the symmetric group of aggregate electron coordinate permutations once and only once, but to also span other (non-Pauli) symmetric group representations known to contain unphysical discrete states and associated continua in which the physically significant Schrödinger eigenstates are generally embedded. These unphysical representations are avoided by isolating the physical block of the Hamiltonian matrix with a unitary transformation obtained from the metric matrix of the explicitly antisymmetrized spectral-product basis. A formal proof of convergence is given in the limit of spectral closure to wave functions and energy surfaces obtained employing conventional prior antisymmetrization, but determined without repeated calculations of Hamiltonian matrix elements as integrals over explicitly antisymmetric aggregate basis states. Computational implementations of the theory employ efficient recursive methods which avoid explicit construction the metric matrix and do not require storage of the full Hamiltonian matrix to isolate the antisymmetric subspace of the spectral-product representation. Calculations of the lowest-lying singlet and triplet electronic states of the covalent electron pair bond (H2) illustrate the various theorems devised and demonstrate the degree of convergence achieved to values obtained employing conventional prior antisymmetrization. Concluding remarks place the atomic spectral-product development in the context of currently employed approaches for ab initio construction of adiabatic electronic eigenfunctions and potential energy surfaces, provide comparisons with earlier related approaches, and indicate prospects for more general applications of the method.
Electric conductivities of 1:1 electrolytes in liquid methanol along the liquid-vapor coexistence curve up to the critical temperature. II. KBr and KI solutions
Authors: Hoshina Taka-aki , Tanaka Kensuke , Tsuchihashi Noriaki , Ibuki Kazuyasu , Ueno Masakatsu
Published: November 2004

The molar conductivities Λ of KBr and KI in dilute methanol solutions were measured along the liquid-vapor coexistence curve up to the critical temperature (240 °C). The concentration dependence of Λ in each condition was analyzed by the Fuoss–Chen–Justice equation to obtain the limiting molar conductivities and the molar association constants. Using the present data together with the literature ones, the validity of the Hubbard–Onsager (HO) dielectric friction theory based on the sphere-in-continuum model was examined for the translational friction coefficients ζ of the halide ions (the Cl−, Br−, and I− ions) in methanol in the density range of 2.989ρc⩾ρ⩾1.506ρc, where ρc=0.2756 g cm−3 is the critical density of methanol. For all the halide ions studied, the friction coefficient decreased with decreasing density at ρ>2.0ρc, while the nonviscous contribution Δζ/ζ increased; Δζ was defined as the difference between ζ and the friction coefficient estimated by the Stokes law. The density dependence of ζ and Δζ/ζ were well reproduced by the HO theory at ρ>2.0ρc. The HO theory also explained the ion-size dependence of Δζ/ζ which decreased with ion-size at ρ>2.0ρc. At ρ<2.0ρc, on the other hand, the HO theory could not explain the density and the ion-size dependences of ζ and Δζ/ζ. These results indicated that the application limit of the HO theory lied about ρ=2.0ρc which is the same as the application limit observed for the alkali metal ions. The present results were also compared with the results in subcritical aqueous solutions.
Cooperating or fighting with control noise in the optimal manipulation of quantum dynamics
Authors: Shuang Feng , Rabitz Herschel
Published: November 2004

This paper investigates the impact of control field noise on the optimal manipulation of quantum dynamics. Simulations are performed on several multilevel quantum systems with the goal of population transfer in the presence of significant control noise. The noise enters as run-to-run variations in the control amplitude and phase with the observation being an ensemble average over many runs as is commonly done in the laboratory. A genetic algorithm with an improved elitism operator is used to find the optimal field that either fights against or cooperates with control field noise. When seeking a high control yield it is possible to find fields that successfully fight with the noise while attaining good quality stable results. When seeking modest control yields, fields can be found which are optimally shaped to cooperate with the noise and thereby drive the dynamics more efficiently. In general, noise reduces the coherence of the dynamics, but the results indicate that population transfer objectives can be met by appropriately either fighting or cooperating with noise, even when it is intense.
Ultrafast excited-state dynamics in photochromic N-salicylideneaniline studied by femtosecond time-resolved REMPI spectroscopy
Authors: Okabe Chie , Nakabayashi Takakazu , Inokuchi Yoshiya , Nishi Nobuyuki , Sekiya Hiroshi
Published: November 2004

Ultrafast processes in photoexcited N-salicylideneaniline have been investigated with femtosecond time-resolved resonance-enhanced multiphoton ionization spectroscopy. The ion signals via the S1(n,π*) state of the enol form as well as the proton-transferred cis-keto form emerge within a few hundred femtoseconds after photoexcitation to the first S1(π,π*) state of the enol form. This reveals that two ultrafast processes, excited-state intramolecular proton transfer (ESIPT) reaction and an internal conversion (IC) to the S1(n,π*) state, occur on a time scale less than a few hundred femtoseconds from the S1(π,π*) state of the enol form. The rise time of the transient corresponding to the production of the proton-transferred cis-keto form is within 750 fs when near the red edge of the absorption is excited, indicating that the ESIPT reaction occurs within 750 fs. The decay time of the S1(π,π*) state of the cis-keto form is 8.9 ps by exciting the enol form at 370 nm, but it dramatically decreases to be 1.5–1.6 ps for the excitation at 365–320 nm. The decrease in the decay time has been attributed to the opening of an efficient nonradiative channel; an IC from S1(π,π*) to S1(n,π*) of the cis-keto form promotes the production of the trans-keto form as the final photochromic products. The two IC processes may provide opposite effect on the quantum yield of photochromic products: IC in the enol form may substantially reduce the quantum yield, but IC in the cis-keto form increase it.
Efficient calculation of potential energy surfaces for the generation of vibrational wave functions
Authors: Rauhut Guntram
Published: November 2004

An automatic procedure for the generation of potential energy surfaces based on high level ab initio calculations is described. It allows us to determine the vibrational wave functions for molecules of up to ten atoms. Speedups in computer time of about four orders of magnitude in comparison to standard implementations were achieved. Effects due to introduced approximations—within the computation of the potential—on fundamental modes obtained from vibrational self-consistent field and vibrational configuration interaction calculations are discussed. Benchmark calculations are provided for formaldehyde and 1,2,5-oxadiazole (furazan).
Density functional response theory calculations of three-photon absorption
Authors: Cronstrand Peter , Jansik Branislav , Jonsson Dan , Luo Yi , Ågren Hans
Published: November 2004

Three-photon absorption probabilities δ3PA have been calculated through application of a recently derived method for cubic response functions within density functional theory (DFT). Calculations are compared with Hartree–Fock (HF) and with a coupled cluster hierarchy of models in a benchmarking procedure. Except for cases having intermediate states near resonance, density functional theory is demonstrated to be in sufficient agreement with the highly correlated methods in order to qualify for predictions of δ3PA. For the larger systems addressed, a set of acceptor A and donor D substituted π-conjugated systems formed by trans-stilbene and dithienothiophene (DTT), we find noticeable differences in the magnitude of δ3PA between HF and DFT, although similar trends are followed. It is shown that the dipolar structures, TS-AD and DTT-AD, have substantially larger δ3PA than other types of modifications which is in accordance with observations for two-photon absorption. This is the first application of density functional theory to three-photon absorption beyond the use of few-state models.
Deformations of loop algebras and integrable systems: hierarchies of integrable equations
Authors: Skrypnyk T.
Published: November 2004

Using special quasigraded Lie algebras, that could be viewed as deformations of loop algebras, we obtain new hierarchies of integrable nonlinear equations admitting zero-curvature representations. In particular, we obtain integrable hierarchies that generalize the Heisenberg magnet, Landau–Lifshitz, and anisotropic chiral field hierarchies. We also obtain a new type of so(3) anisotropic chiral field equation along with its higher rank generalization.
A study of the correlation effects upon the modelization of the double exchange phenomenon
Authors: Carissan Yannick , Heully Jean-Louis , Guihéry Nathalie , Alary Fabienne
Published: November 2004

A previous work by the authors has shown that the usual spin Hamiltonian used to model the magnetic spectra of mixed valence compounds was not sufficient to reproduce the magnetic spectrum of the molecule [Fe2(OH)3(NH3)6]2+. In the present paper, the spin Hamiltonian is confronted to correlated ab initio calculations. The discrepancy between this Hamiltonian and the calculations is investigated and explained. It is pointed out that the multiconfigurational nature of the transition metal is responsible for this discrepancy. However, we show that this effect can easily be treated at the complete active space self-consistent field (CASSCF) level and that no further correlation treatment is needed. The spin Hamiltonian, which reproduces very well the minimal CASSCF results, could not be improved to recover the multireference effects.
Ion dynamics in mixed alkali cadmium fluoride glasses
Authors: Ghosh S. , Ghosh A.
Published: November 2004

We have investigated ion dynamics in cadmium fluoride nonoxide glasses, in the frequency range from 10 Hz to 2 MHz and in the temperature range from room temperature to just below the glass transition temperature. We have established the existence of mixed alkali effect for these glasses from different aspects of relaxation dynamics. We have observed lower dimensionality of the conduction pathways in mixed alkali cadmium fluoride glasses compared to that in the single alkali glasses. Although, both n and β represent the interaction between the charge carriers, we have not found any theoretical correlation between them. Using different scaling approaches we have shown that the relaxation dynamics in mixed alkali cadmium fluoride glasses is independent of temperatures.
Appearance of bulk properties in small tungsten oxide clusters
Authors: Sun Q. , Rao B. K. , Jena P. , Stolcic D. , Kim Y. D. , Gantefor Gerd , Castleman A. W.
Published: November 2004

Contrary to the conventional understanding that atomic clusters usually differ in properties and structure from the bulk constituents of which they are comprised, we show that even a dimer of tungsten oxide (WO3)2 possesses bulklike features and the geometry of a small cluster containing only 4 tungsten and 12 oxygen atoms bears the hallmarks of crystalline tungsten oxide, WO3. This observation, based on a synergistic approach involving mass distributions under quasisteady state conditions, photoelectron spectroscopy, and first principles molecular orbital theory, not only illustrates the existence of a class of strongly covalent or ionic materials whose embryonic forms are tiny clusters but also lends the possibility that a fundamental understanding of complex processes such as catalytic reactions on surfaces may be achieved on an atomic scale with clusters as model systems.
Ion-molecule rate constants and branching ratios for the reaction of N3++O2 from 120 to 1400 K
Authors: Popovic Svetozar , Midey Anthony J. , Williams Skip , Fernandez Abel I. , Viggiano A. A. , Zhang Peng , Morokuma K.
Published: November 2004

The kinetics of the reaction of N3+ with O2 has been studied from 120 to 1400 K using both a selected ion flow tube and high-temperature flowing afterglow. The rate constant decreases from 120 K to ∼1200 K and then increases slightly up to the maximum temperature studied, 1400 K. The rate constant compares well to most of the previous measurements in the overlapping temperature range. Comparing the results to drift tube data shows that there is not a large difference between increasing the translational energy available for reaction and increasing the internal energy of the reactants over much of the range, i.e., all types of energies drive the reactivity equally. The reaction produces both NO+ and NO2+, the latter of which is shown to be the higher energy NOO+ linear isomer. The ratio of NOO+ to NO+ decreases from a value of over 2 at 120 K to less than 0.01 at 1400 K because of dissociation of NOO+ at the higher temperatures. This ratio decreases exponentially with increasing temperature. High-level theoretical calculations have also been performed to compliment the data. Calculations using multi-reference configuration interaction theory at the MRCISD(Q)/cc-pVTZ level of theory show that singlet NOO+ is linear and is 4.5 eV higher in energy than ONO+. A barrier of 0.9 eV prevents dissociation into NO+ and O(1D); however, a crossing to a triplet surface connects to NO+ and O(3P) products. A singlet and a triplet potential energy surface leading to products have been determined using coupled cluster theory at the CCSD(T)/aug-cc-pVQZ level on structures optimized at the Becke3-Lee, Yang, and Parr (B3LYP)/aug-cc-pVTZ level of theory. The experimental results and reaction mechanism are evaluated using these surfaces.
Molecular dynamics averaging of Xe chemical shifts in liquids
Authors: Jameson Cynthia J. , Sears Devin N. , Murad Sohail
Published: November 2004

The Xe nuclear magnetic resonance chemical shift differences that afford the discrimination between various biological environments are of current interest for biosensor applications and medical diagnostic purposes. In many such environments the Xe signal appears close to that in water. We calculate average Xe chemical shifts (relative to the free Xe atom) in solution in eleven liquids: water, isobutane, perfluoro-isobutane, n-butane, n-pentane, neopentane, perfluoroneopentane, n-hexane, n-octane, n-perfluorooctane, and perfluorooctyl bromide. The latter is a liquid used for intravenous Xe delivery. We calculate quantum mechanically the Xe shielding response in Xe-molecule van der Waals complexes, from which calculations we develop Xe (atomic site) interpolating functions that reproduce the ab initio Xe shielding response in the complex. By assuming additivity, these Xe-site shielding functions can be used to calculate the shielding for any configuration of such molecules around Xe. The averaging over configurations is done via molecular dynamics (MD). The simulations were carried out using a MD technique that one of us had developed previously for the simulation of Henry’s constants of gases dissolved in liquids. It is based on separating a gaseous compartment in the MD system from the solvent using a semipermeable membrane that is permeable only to the gas molecules. We reproduce the experimental trends in the Xe chemical shifts in n-alkanes with increasing number of carbons and the large chemical shift difference between Xe in water and in perfluorooctyl bromide. We also reproduce the trend for a given solvent of decreasing Xe chemical shift with increasing temperature. We predict chemical shift differences between Xe in alkanes vs their perfluoro counterparts.
Influence of molecular adsorption on the dielectric properties of a single wall nanotube: A model sensor
Authors: Langlet R. , Arab M. , Picaud F. , Devel M. , Girardet C.
Published: November 2004

Recent measurements of the resonance frequency of a copper disk covered with carbon nanotube bundles have shown characteristic resonance shifts during exposure with various gas molecules. The shifts were interpreted as the change of the dielectric permittivity of the system forming the sensor due to the electric properties of the adsorbed molecules. Starting from a simplified sensor model formed by one single wall nanotube, we develop a self-consistent approach to describe the variation of the linear dielectric susceptibility of the tube at the atomic scale when molecules are adsorbed at its external surface. The sensitivity of this model sensor is tested as a function of the apolar or polar nature of the admolecules, their adsorption geometry, their concentration, and the characteristics of the tube (length, diameter,…). The comparison with data on dielectric constant changes vs adsorption, coming from measurements of the resonance frequency shifts, displays striking agreement for most of the molecular species considered.
Finite size effects in thermal field theory
Authors: Svaiter N. F.
Published: November 2004

We consider a neutral self-interacting massive scalar field defined in a d-dimensional Euclidean space. Assuming thermal equilibrium, we discuss the one-loop perturbative renormalization of this theory in the presence of rigid boundary surfaces (two parallel hyperplanes), which break translational symmetry. In order to identify the singular parts of the one-loop two-point and four-point Schwinger functions, we use a combination of dimensional and zeta-function analytic regularization procedures. The infinities which occur in both the regularized one-loop two-point and four-point Schwinger functions fall into two distinct classes: local divergences that could be renormalized with the introduction of the usual bulk counterterms, and surface divergences that demand counterterms concentrated on the boundaries. We present the detailed form of the surface divergences and discuss different strategies that one can assume to solve the problem of the surface divergences. We also briefly mention how to overcome the difficulties generated by infrared divergences in the case of Neumann–Neumann boundary conditions.
On a conjecture of Givental
Authors: Song Jun S. , Song Yun S.
Published: November 2004

These brief notes record our puzzles and findings surrounding Givental’s recent conjecture which expresses higher genus Gromov–Witten invariants in terms of the genus-0 data. We limit our considerations to the case of a complex projective line, whose Gromov–Witten invariants are well-known and easy to compute. We make some simple checks supporting his conjecture.