bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrafast Intramolecular Charge Transfer and Internal Conversion with Tetrafluoro‐aminobenzonitriles
Authors: Galievsky Victor A. , Druzhinin Sergey I. , Demeter Attila , Jiang Yun‐Bao , Kovalenko Sergey A. , Pérez Lustres Luis , Venugopal Karunakaran , Ernsting Nikolaus P. , Allonas Xavier , Noltemeyer Mathias , Machinek Reinhard , Zachariasse Klaas A. 
Published: November 2005

AbstractThe five 2,3,5,6‐tetrafluoro‐4‐aminobenzonitriles XABN4F with a dimethyl‐amino (DMABN4F), diethyl‐amino (DEABN4F), azetidinyl (AZABN4F), methyl‐amino (MABN4F) or amino (ABN4F) group undergo ultrafast intramolecular charge transfer (ICT) at room temperature, in the polar solvent acetonitrile (MeCN) as well as in the nonpolar n‐hexane. ICT also takes place with the corresponding non‐fluorinated aminobenzonitriles DMABN, DEABN and AZABN in MeCN, whereas for these molecules in n‐hexane only minor (DMABN, DEABN) or no (AZABN) ICT fluorescence is detected. For the secondary (MABN) and primary (ABN) amines, an ICT reaction does not occur, which makes ABN4F the first electron donor/acceptor molecule with an NH2 group for which ICT is observed. The ICT state of the XABN4Fs has a dipole moment of around 14 D, clearly smaller than that of DMABN (17 D). This difference is attributed to the electron withdrawing from the CN group to the phenyl ring, exerted by the four F‐substituents. The reaction from the initially prepared locally excited (LE) to the ICT state in n‐hexane proceeds in the sub‐picosecond time range: 0.35 ps (DMABN4F), 0.29 ps (DEABN4F) and 0.13 ps (AZABN4F), as determined from femtosecond transient absorption measurements. In the highly polar solvent MeCN, an ICT reaction time of around 90 fs is observed for all five XABN4Fs, irrespective of the nature of their amino group. This shows that with these molecules in MeCN the ICT reaction rate is limited by the solvent dielectric relaxation time of MeCN, for which a value of around 90 fs has been reported. It is therefore concluded that, during this ultrashort ICT reaction, a large‐amplitude motion such as a full 90° twist of the amino group is unlikely to occur in the XABN4Fs. The ICT state of the XABN4Fs is strongly quenched via internal conversion (IC), with a lifetime ${{\rm{\tau }}\prime _0 (ICT)}$ down to 3 ps, possibly by a reaction passing through a conical intersection made accessible due to a deformation of the phenyl group by out‐of‐plane motions induced by vibronic coupling between low‐lying πσ* and ππ* states in the XABN4Fs.
DFT Study of Fullerene Dimers
Authors: Bihlmeier Angela , Samson Claire C. M. , Klopper Wim 
Published: November 2005

AbstractSeveral [2+2] dimerization products of a fullerene Cn (n=50, 52, 54, 56, 58, 60) in its most stable form are presented and discussed. In total, 34 dimers are studied. Only symmetric CnCn dimers (no mixed products) are reported, and only dimers of the fullerenes C50 to C58 with bonds between C atoms in adjacent pentagons are considered. Geometries were optimized within the framework of density functional theory using the Becke–Perdew exchange‐correlation functional (BP86) in combination with an empirical dispersive energy correction, which contributes significantly to the binding energy. The results are discussed in the context of the reactivity of adjacent pentagon sites. The lateral interaction between fullerenes is found to be stronger for C50 to C58 than for C60, which is consistent with recent experimental observations. Further, the possibility of polymer formation based on the investigated [2+2] reaction is addressed.
Enhancement of Förster Energy Transfer within a Microspherical Cavity
Authors: Fujiwara Hideki , Sasaki Keiji , Masuhara Hiroshi 
Published: November 2005

AbstractEnergy transfer from pyrene to perylene molecules co‐doped within a poly(methyl methacrylate) latex microsphere was drastically accelerated relative to free space. Fluorescence spectra of the microspheres showed that the relative emission intensities of pyrene and perylene changed with the sphere diameter. Analyses of emission decay profiles clarified that Förster‐type energy‐transfer processes were induced and that the transfer rates increased within the microspherical cavity. This enhancement can be ascribed not only to the quantum electrodynamic effects on the pyrene emission rate, but also the cavity effect of increasing the overlapping factor between donor emission and acceptor absorption spectra.
Ultrafast Electron Diffraction: Dynamical Structures on Complex Energy Landscapes
Authors: Shorokhov Dmitry , Park Sang Tae , Zewail Ahmed H. 
Published: November 2005

AbstractIn this contribution, we report studies in ultrafast electron diffraction (UED), with the aim of exploring new directions. The main focus is on the determination of complex structures and their dynamics with spatial and temporal resolutions sufficient to give an atomic‐scale picture for the evolution in chemical or biological change. We also provide the theoretical framework for UED, and compare the experimental findings of UED to those predicted by density functional and charge density calculations. Selected applications are given in order to highlight phenomena related to concepts such as bifurcation of trajectories in dynamics, far‐from‐equilibrium coherent structures, and conformational robustness in biological structures. For the former two cases, we consider chemical systems, and, for the latter, we examine proteins of 200 atoms (angiotensin I) or more.
Ultrafast Electron Diffraction: Oriented Molecular Structures in Space and Time
Authors: Baskin J. Spencer , Zewail Ahmed H. 
Published: November 2005

AbstractThe technique of ultrafast electron diffraction allows direct measurement of changes which occur in the molecular structures of isolated molecules upon excitation by femtosecond laser pulses. The vectorial nature of the molecule–radiation interaction also ensures that the orientation of the transient populations created by the laser excitation is not isotropic. Here, we examine the influence on electron diffraction measurements—on the femtosecond and picosecond timescales—of this induced initial anisotropy and subsequent inertial (collision‐free) molecular reorientation, accounting for the geometry and dynamics of a laser‐induced reaction (dissociation). The orientations of both the residual ground‐state population and the excited‐ or product‐state populations evolve in time, with different characteristic rotational dephasing and recurrence times due to differing moments of inertia. This purely orientational evolution imposes a corresponding evolution on the electron scattering pattern, which we show may be similar to evolution due to intrinsic structural changes in the molecule, and thus potentially subject to misinterpretation. The contribution of each internuclear separation is shown to depend on its orientation in the molecular frame relative to the transition dipole for the photoexcitation; thus not only bond lengths, but also bond angles leave a characteristic imprint on the diffraction. Of particular note is the fact that the influence of anisotropy persists at all times, producing distinct differences between the asymptotic “static” diffraction image and the predictions of isotropic diffraction theory.
Performance of Fluorescence Correlation Spectroscopy for Measuring Diffusion and Concentration
Authors: Enderlein Jörg , Gregor Ingo , Patra Digambara , Dertinger Thomas , Kaupp U. Benjamin 
Published: November 2005

AbstractFluorescence correlation spectroscopy (FCS) has become an important tool for measuring diffusion, concentration, and molecular interactions of cellular components. The interpretation of FCS data critically depends on the measurement set‐up. Here, we present a rigorous theory of FCS based on exact wave‐optical calculations. Six of the most important optical and photophysical factors that influence FCS are studied: fluorescence anisotropy, cover‐slide thickness, refractive index of the sample, laser‐beam geometry, optical saturation, and pinhole adjustment. Our theoretical framework represents a general attempt to link all relevant parameters of the experimental set‐up with the measured correlation function.
Adaptive cross‐layer bandwidth allocation in a rain‐faded satellite environment
Authors: Celandroni Nedo , Davoli Franco , Ferro Erina , Gotta Alberto 
Published: November 2005

AbstractTwo control schemes, based on cross‐layer adaptation and a hierarchical parametric optimization of the bandwidth allocation, are described and investigated in a satellite network environment, in the presence of both real‐time and best‐effort traffic flows. A number of earth stations (traffic stations) operate in different weather conditions, with different levels of fade, which affect the transmitted signals. The call admission control policy for real‐time connections is administered locally at the traffic stations. Amaster stationis charged to manage the time division multiple access bandwidth allocation policy, by defining bandwidth partitions to the traffic stations. Upon detecting significant fade changes, the signalling from the traffic stations triggers new bandwidth redistributions. The control schemes are compared, and the effect of fade countermeasures, applied at the physical layer, on the bandwidth occupation is explicitly accounted for. For each policy, figures of merit such as loss, blocking and dropping probabilities are computed for a specific real environment, based on the Italsat satellite national coverage payload characteristics. Copyright © 2005 John Wiley & Sons, Ltd.
Managing QoS requirements for video streaming: from intra‐node to inter‐node
Authors: Bai Y. , R. Ito M. 
Published: November 2005

AbstractStreaming video over IP networks has become increasingly popular; however, compared to traditional data traffic, video streaming places different demands on quality of service (QoS) in a network, particularly in terms of delay, delay variation, and data loss. In response to the QoS demands of video applications, network techniques have been proposed to provide QoS within a network. Unfortunately, while efficient from a network perspective, most existing solutions have not provided end‐to‐end QoS that is satisfactory to users. In this paper, packet scheduling and end‐to‐end QoS distribution schemes are proposed to address this issue. The design and implementation of the two schemes are based on the active networking paradigm. In active networks, routers can perform user‐driven computation when forwarding packets, rather than just simple storing and forwarding packets, as in traditional networks. Both schemes thus take advantage of the capability of active networks enabling routers to adapt to the content of transmitted data and the QoS requirements of video users. In other words, packet scheduling at routers considers the correlation between video characteristics, available local resources and the resulting visual quality. The proposed QoS distribution scheme performs inter‐node adaptation, dynamically adjusting local loss constraints in response to network conditions in order to satisfy the end‐to‐end loss requirements. An active network‐based simulation shows that using QoS distribution and packet scheduling together increases the probability of meeting end‐to‐end QoS requirements of networked video. Copyright © 2005 John Wiley & Sons, Ltd.
Efficient medium arbitration of FSAN‐compliant GPONs
Authors: Leligou H. C. , Linardakis Ch. , Kanonakis K. , Angelopoulos J. D. , Orphanoudakis Th. 
Published: November 2005

AbstractThe steadily rising demand for multimedia and data services, the falling cost and omnipresence of Ethernet and the maturity of passive optical networks (PON) technology, promise to radically change the landscape in the local loop. The heart of a gigabit PON system (recently standardized by FSAN/ITU) is the medium access controller (MAC), which arbitrates access to the upstream link among users with fluctuating traffic demands and effects the multiplexing and concentration policy. At the same time, it has to safeguard the service quality and enforce the parameters agreed in the service level agreements (SLAs) between the users and the service provider. In this paper, a MAC protocol designed to serve any mix of services according to their quality of service (QoS) needs, employing four priority levels along with a high number of logically separate data queues is presented. The architecture and implementation in hardware of a MAC algorithm capable of allocating bandwidth down to a resolution of a byte with QoS differentiation is the focus of this paper. It employs the bandwidth arbitration tools of the FSAN/ITU G.984.3 standard and maps SLA parameters to GPON service parameters to create an efficient, fair and flexible residential access system. Copyright © 2005 John Wiley & Sons, Ltd.
It's not that bad: Error introduced by oral stimulants in salivary cortisol research
Authors: Talge Nicole M. , Donzella Bonny , Kryzer Erin M. , Gierens Andrea , Gunnar Megan R. 
Published: November 2005

AbstractEvidence that oral stimulants can produce interference effects in salivary cortisol assays has led to advice to avoid their use. However, in studies with young children, the use of these saliva‐producing substances increases compliance with collection procedures. Four experiments are described to examine the effects of two commonly used stimulants, SweetTarts™ and Koolaid™. Across these experiments, interference effects produced by different quantities of these stimulants (0.025, 0.1, and 0.2 g) and those produced in two commonly used assays, DELFIA and EIA, were explored. The impact of using cotton rolls soaked with an oral stimulant prior to saliva collection was also examined. In general, oral stimulants did not affect the rank ordering of cortisol values, as the results for stimulant‐treated samples were highly correlated with those of untreated samples (approximately .90 for serially collected samples and .95 for aliquots of the same saliva pool). Depending on which assay was used, however, oral stimulants increased or decreased the cortisol levels reported, with effects sizes in the small to medium range. Thus, oral stimulants should not be used with only a portion of the subjects in a study, nor should researchers assay stimulant‐treated samples from the same study using different assays. When used sparingly, oral stimulants can be employed without compromising the quality of salivary cortisol data. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 369–376, 2005.
Maternal influences on adult stress and anxiety‐like behavior in C57BL/6J and BALB/cJ mice: A cross‐fostering study
Authors: Priebe Kristianne , Brake Wayne G. , Romeo Russell D. , Sisti Helene M. , Mueller Astrid , McEwen Bruce S. , Francis Darlene D. 
Published: November 2005

AbstractThe quality of maternal care during early life has a dramatic impact on later stress reactivity and anxiety. Two inbred mouse strains, C57BL/6J and BALB/cJ, differ in levels of maternal care, stress reactivity, and anxiety‐like behavior in adulthood. However, the relative contribution of early environmental factors and genetic predisposition to differences in these strains is not known. Maternal care, plasma corticosterone levels, emotionality, and hippocampal and paraventricular nucleus (PVN) glucocorticoid receptor mRNA levels were measured in adult C57BL/6J and BALB/cJ mice. Litters were then cross‐fostered and anxiety‐like behavior and stress reactivity was assessed in adulthood. Significantly less maternal care and elevated stress‐induced corticosterone and emotionality was observed in BALB/cJ compared to C57BL/6J mice. Yet, no strain differences were found in hippocampal or paraventricular nucleus glucocorticoid receptor mRNA levels. Cross‐fostering did alter anxiety‐like behavior and basal corticosterone levels, which suggests that while genetic differences account for some of the variations between these two strains early rearing conditions also contribute. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 398–407, 2005.
Developmental changes in the functional brain responses of adolescents to images of high and low‐calorie foods
Authors: Killgore William D. S. , Yurgelun‐Todd Deborah A. 
Published: November 2005

AbstractWe examined cerebral responses to visually presented food images in children and adolescents. Eight healthy normal‐weight females (ages 9–15) underwent functional magnetic resonance imaging (fMRI) while viewing photographs of high‐ and low‐calorie foods and dining utensils. In general, food images yielded significant activation within the inferior orbitofrontal cortex, hippocampus, and fusiform gyri. High calorie food images activated the left hippocampus and subgenual cingulate, and age correlated positively with activity within the orbitofrontal cortex but negatively with activity within the anterior cingulate gyrus. Low‐calorie foods activated the fusiform gyrus and demonstrated age‐related increases in the left superior temporal gyrus and anterior cingulate. Utensils activated the fusiform gyrus and showed age‐related increases in the prefrontal cortex. Data were also compared statistically to a sample of adults exposed to the same stimulus conditions. Findings support a developmental model of adolescent maturation whereby age‐related changes in cerebral functioning develop from lower‐order sensory processing toward higher‐order processing of stimuli via prefrontal cortical systems involved in reward anticipation, self‐monitoring, and behavioral inhibition. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 377–397, 2005.
Childcare as a stabilizing influence on HPA axis functioning: A reevaluation of maternal occupational patterns and familial relations
Authors: Chryssanthopoulou C.C. , Turner‐Cobb J.M. , Lucas A. , Jessop D. 
Published: November 2005

AbstractThe influence of family relations, maternal occupational characteristics, and childcare1The UK terms “childcare,” childcare centres' and “nurseries” are used throughout this paper to define group care for children prior to starting their first year of formal schooling at age 4 years and are used synonymously with the American terms “day‐care” and “preschool.” This form of group care is provided in a formal setting, outside the family home and excludes “childminding” (i.e., childcare that may be group based and offered at the home of the care provider/childminder). In the UK, this form of childcare is offered from zero to 4 years old. Children are separated according to their age into small groups usually consisting of 10–15 children. In the present study, all children were in the preschool‐aged group (3–4 years old). Where childcare of a different or more generic form is referred to, then this has been made clear in the context or stated in the text.
utilization on preschool children's cortisol production were investigated in 56 mother–child dyads. Family characteristics and maternal employment, childcare and child temperament were reported by mothers. Morning and evening levels of children's salivary cortisol were obtained. Children in highly expressive or reserved families exhibited higher cortisol levels compared to children in moderately expressive families. Elevated levels of cortisol were detected in children of mothers reporting low levels of job role quality or high levels of emotional exhaustion. Frequent childcare use was found to protect children against the physiological effects of low maternal job role quality and emotional exhaustion. Findings underscore the pervasive role of the family as set within an external support system and highlight the potential physiological impact of these interacting contexts for children. Further research is needed to fully understand current findings and to develop appropriate psycho‐physiological interventions. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 354–368, 2005.
Effects of different opportunities for social interaction on the play fighting behavior in male and female golden hamsters (Mesocricetus auratus)
Authors: Vieira Mauro Luís , Garcia Murilo Pereira , Rau Débora Driemeyer Wilbert , Prado Alessandra Bonassoli 
Published: November 2005

AbstractAfter social isolation, animals play significantly more than nonisolated animals. However, it is not always possible to affirm that the effect of the social isolation is due to the lack of play. Experimentally, selective privation has been used, such as allowing the animals to play during periods of the day. In the present study, two experiments were carried out to verify the possible differences in the play fighting behavior of golden hamsters that were allowed to have different daily periods of social interaction (10 min, 1 hr, or 2 hr). Through the statistical analysis, it was shown that males play more than females and that periods of up to 2 hr daily for interaction are insufficient to avoid the short‐term effects of isolation. It is concluded that a period of daily social interaction greater than 2 hr is needed to offset the effects of social isolation in golden hamsters. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 345–353, 2005.
Conjugate limb coordination after experience with an interlimb yoke: Evidence for motor learning in the rat fetus
Authors: Robinson Scott R. 
Published: November 2005

AbstractThis study investigated the capacity of the E20 rat fetus to adaptively alter patterns of interlimb coordination in a prenatal model of motor learning. Fetal limb movement was manipulated with an interlimb yoke, consisting of a fine thread attached at the ankles, which created a physical linkage between two limbs. Exposure to the yoke resulted in a gradual increase in conjugate movements of the yoked limbs during a 30‐min training period, which persisted after removal of the yoke. Training effects were evident when the yoke was applied to two hindlimbs, two forelimbs, or a homolateral forelimb–hindlimb pair. A savings in the rate of acquisition also was observed when fetuses experienced yoke training in a second session. These data argue that the rat fetus can respond to kinesthetic feedback resulting from variation in motor performance, which suggests that experience contributes to the development of coordinated motor behavior before birth. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 328–344, 2005.
Regularities and diversity in developmental pathways: Mother–infant relationships in hamadryas baboons
Authors: Hernández‐Lloreda María Victoria , Colmenares Fernando 
Published: November 2005

AbstractChange, stasis, stability, discontinuity, orderliness, and diversity are all potential characteristics of developmental systems. This study uses multilevel modeling to characterize the normative developmental pathways of the early social relationships of 23 mother–infant pairs embedded in a multilayered colony of hamadryas baboons (Papio hamadryas hamadryas). The relationships were assessed by means of 27 behavioral measures that were collected during 100–220 focal sampling sessions per infant, from birth to 380 days of age (25 two‐week age intervals). Seventy four percent of the behavioral measures exhibited an age‐related pattern. Infant age, however, was not predictive of the rate of the behaviors relating to the management of mother–infant conflicts. This study provides empirical evidence that the development of mother–infant relationships may involve periods of change and stasis, overall orderliness, and diversity as well as canalization of developmental pathways. We believe that growth curve analysis can be useful to tackle various hot issues in the study of behavioral development. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 47: 297–317, 2005.