bluuebunny/crossref_metadata_2025 huggingface dataset:
Youth Development in Europe
Authors: Salmela-Aro Katariina , Schoon Ingrid
Published: December 2009

A series of six papers on “Youth Development in Europe: Transitions and Identities” has now been published in the European Psychologist throughout 2008 and 2009. The papers aim to make a conceptual contribution to the increasingly important area of productive youth development by focusing on variations and changes in the transition to adulthood and emerging identities. The papers address different aspects of an integrative framework for the study of reciprocal multiple person-environment interactions shaping the pathways to adulthood in the contexts of the family, the school, and social relationships with peers and significant others. Interactions between these key players are shaped by their embeddedness in varied neighborhoods and communities, institutional regulations, and social policies, which in turn are influenced by the wider sociohistorical and cultural context. Young people are active agents, and their development is shaped through reciprocal interactions with these contexts; thus, the developing individual both influences and is influenced by those contexts. Relationship quality and engagement in interactions appears to be a fruitful avenue for a better understanding of how young people adjust to and tackle development to productive adulthood.
Exploring the Relations Among Executive Functions, Fluid Intelligence, and Personality
Authors: Unsworth Nash , Miller Joshua D. , Lakey Chad E. , Young Diana L. , Meeks J. Thadeus , Campbell W. Keith , Goodie Adam S.
Published: December 2009

Executive functions (EFs) are important for goal-directed behavior and have been linked with a number of important constructs like intelligence. The current study examined the link between EFs and aspects of normal and abnormal personality. Latent variables of working memory, fluency, response inhibition, and vigilance EFs were examined along with fluid intelligence (gF). It was found that the EFs were separate yet correlated, and that each was related to gF. Furthermore, it was found that aspects of personality as measured by the Five-Factor Model and the BIS/BAS were differentially related to the EFs and gF. Examination of personality disorder measures also demonstrated differential relationships with the EFs and gF. The results suggest a number of systematic and important links between EFs and personality and suggest the need for a more unified field of individual differences.
On the Social Malleability of Traits
Authors: Robinson Oliver C.
Published: December 2009

The current study investigated the effects of social context on Big 5 trait expression, and the moderating influence of social context on gender differences in personality. A short Big 5 instrument assessed trait expression in three contexts: with parents, with friends, and with work colleagues. Findings indicated significant cross-context variation in all five traits, while also showing cross-context within-trait correlations. These cross-context correlations found that Conscientiousness was the most stable of the Big 5 traits and that Extraversion the least stable across the three contexts assessed. Gender effects were found only at the trait-in-context level, suggesting a role for social context in moderating personality gender differences.
Intelligence and Specific Cognitive Abilities in Children
Authors: Tillman Carin M. , Bohlin Gunilla , Sörensen Lin , Lundervold Astri J.
Published: December 2009

This community-based study investigated the relationships between measures of specific cognitive functions (such as working memory [WM] and interference control) and intelligence in 283 8- to 11-year-old children, including 124 children who fulfilled criteria for a psychiatric diagnosis. A hierarchical regression analysis was used to overcome issues of overlapping predictor constructs. The results generally showed that measures of processing speed, WM, as well as inhibitory interference control entered in the order of presentation, each contributed uniquely to the explanation of fluid intelligence performance. The results for crystallized intelligence performance generally showed that the measures of processing speed, short-term memory (STM), WM, and sustained attention – entered in that order – made significant independent contributions. While effect sizes varied somewhat for contributions in the whole sample compared with the subgroup not meeting criteria for a psychiatric diagnosis, there were no significant differences. The findings therefore should be broadly representative in indicating that the unique aspects of these cognitive functions are important in the explanation of intelligence. The findings also demonstrate important independent features of the functions used as predictors.
Are Individual Differences in Absentmindedness Correlated with Individual Differences in Attention?
Authors: Ishigami Yoko , Klein Raymond M.
Published: December 2009

We administered the Cognitive Failures Questionnaire (CFQ) and one of two versions of the Attention Network Test (ANT) to 200 participants. Orthogonal subtraction scores based on performance (reaction time and error rate) from selected conditions of the ANT provided measures of the efficacy of three attention components: alerting, orienting, and executive control, while the total CFQ score provided a global measure of absentmindedness. Executive control was not associated with the CFQ in either experiment. When alertness was generated by a warning tone, greater alerting effects in reaction time were associated with higher CFQ scores (greater absentmindedness). The orienting effects in accuracy obtained from the two versions of the ANT varied with absentmindedness in opposite directions, suggesting that these two tests tap different aspects of orienting.
Obtaining Equations From the Proportional Odds Model to Set Multiple Cut Scores on a Test
Authors: Bersabé Rosa , Rivas Teresa , Berrocal Carmen
Published: December 2009

From the proportional odds (PO) model, we obtain general equations to compute multiple cut scores on a test score. This analytical procedure is based on the relationship between a test score (X) and an ordinal outcome variable (Y) with more than two categories. Cut scores are established at the test scores corresponding to the intersection of adjacent category distributions. The application of this procedure is illustrated by an example with data from an actual study on eating disorders (EDs). In this example, two cut scores on the Eating Attitudes Test (EAT-26) are established in order to differentiate between three ordered categories: (1) asymptomatic, (2) symptomatic, and (3) eating disorder. Diagnoses were made from the responses to a self-report (Q-EDD) that operationalizes DSM-IV criteria for EDs. Alternatives to the PO model, when the PO assumption is rejected, are discussed.
Repeated Cross-Sectional Randomized Response Data
Authors: Frank L. E. , van den Hout A. , van der Heijden P. G. M.
Published: December 2009

Randomized response (RR) is an interview technique that can be used to protect the privacy of respondents if sensitive questions are posed. This paper explains how to measure change in time if a binary RR question is posed at several time points. In cross-sectional research settings, new insights often gradually emerge. In our setting, a switch to another RR procedure necessitates the development of a trend model that estimates the effect of the covariate time if the dependent variable is measured by different RR designs. We also demonstrate that it is possible to deal with self-protective responses, thus accommodating our trend model with the latest developments in RR data analysis.
The Mere Exposure Effect and Recognition Depend on the Way You Look! *S. W. and J. D. contributed equally to this study.
Authors: Willems Sylvie , Dedonder Jonathan , Van der Linden Martial
Published: December 2009

In line with Whittlesea and Price (2001) , we investigated whether the memory effect measured with an implicit memory paradigm (mere exposure effect) and an explicit recognition task depended on perceptual processing strategies, regardless of whether the task required intentional retrieval. We found that manipulation intended to prompt functional implicit-explicit dissociation no longer had a differential effect when we induced similar perceptual strategies in both tasks. Indeed, the results showed that prompting a nonanalytic strategy ensured performance above chance on both tasks. Conversely, inducing an analytic strategy drastically decreased both explicit and implicit performance. Furthermore, we noted that the nonanalytic strategy involved less extensive gaze scanning than the analytic strategy and that memory effects under this processing strategy were largely independent of gaze movement.
Multiple-Object Tracking
Authors: Barker Kathryn , Allen Roy , McGeorge Peter
Published: December 2009

Research has demonstrated that individuals who routinely engage in complex visuospatial tasks (e.g., radar operators) show an enhanced ability to track multiple randomly moving targets. This study examined tracking expertise using members of a University Officer Training Corps (OTCs) who regularly engage in tasks requiring good dynamic spatial cognition. As expected, the results show that OTCs have enhanced tracking ability relative to other undergraduates. More importantly, they support the idea that, while one set of executive processes are involved in the moment-by-moment updating of the visuospatial representations necessary for dynamic, multiple-object tracking, other processes are activated when whole object sets disappear simultaneously, to create a long-term memory trace of the objects’ locations at the moment of their disappearance. Expertise only arose in the former processes, but was lost after a short decay period, such as occurred with a delayed response.
Does Kaniso Activate CASINO?
Authors: Acha Joana , Perea Manuel
Published: December 2009

Most recent input coding schemes in visual-word recognition assume that letter position coding is orthographic rather than phonological in nature (e.g., SOLAR, open-bigram, SERIOL, and overlap). This assumption has been drawn – in part – by the fact that the transposed-letter effect (e.g., caniso activates CASINO) seems to be (mostly) insensitive to phonological manipulations (e.g., Perea & Carreiras, 2006 , 2008 ; Perea & Pérez, 2009 ). However, one could argue that the lack of a phonological effect in prior research was due to the fact that the manipulation always occurred in internal letter positions – note that phonological effects tend to be stronger for the initial syllable ( Carreiras, Ferrand, Grainger, & Perea, 2005 ). To reexamine this issue, we conducted a masked priming lexical decision experiment in which we compared the priming effect for transposed-letter pairs (e.g., caniso-CASINO vs. caviro-CASINO) and for pseudohomophone transposed-letter pairs (kaniso-CASINO vs. kaviro-CASINO). Results showed a transposed-letter priming effect for the correctly spelled pairs, but not for the pseudohomophone pairs. This is consistent with the view that letter position coding is (primarily) orthographic in nature.
The Time Course of Direction Specification in Brief Interceptive Actions
Authors: Marinovic Welber , Plooy Annaliese M. , Tresilian James R.
Published: December 2009

In fastball sports such as baseball and tennis people are required to produce accurate responses following brief observations of the ball. This limits the time available to prepare the movement. To cope with constrained viewing periods which precede the interception of fast approaching balls, performers are likely to prepare their responses in advance. Although motor preparation may begin before the moving object is seen, accuracy requires that certain program parameters are determined from observations of the target. The aim of the experiment reported here was to determine the last moment at which information about the direction of the target can be incorporated into a motor program. The empirical protocol used in this study allowed us to examine whether new direction information is incorporated discretely or continuously into the program during short intervals prior to movement onset (MO) – the preparation interval. Participants were trained to hit moving targets at two directions with movements of a specific duration (180 ms). This method permitted an estimate of MO. Preparation intervals were controlled by issuing a stimulus cue for movement direction at various times prior to the estimated MO. Results showed that direction information could be fully incorporated into the program with a preparation interval as brief as 250 ms. In addition, the results indicated that direction was specified predominantly in a discrete fashion even at short preparation intervals.
Subjective Learning Discounts Test Type
Authors: Touron Dayna R. , Hertzog Christopher , Speagle James Z.
Published: December 2009

We evaluated the extent to which memory test format and test transfer influence the dynamics of metacognitive judgments. Participants completed two study-test phases for paired-associates, with or without transferring test type, in one of four conditions: (1) recognition then recall, (2) recall then recognition, (3) recognition throughout, or (4) recall throughout. Global judgments were made prestudy, poststudy, and posttest for each phase; judgments of learning (JOLs) following item study were also collected. Results suggest that metacognitive judgment accuracy varies substantially by memory test type. Whereas underconfidence in JOLs and global predictions increases with recall practice (Koriat’s underconfidence-with-practice effect), underconfidence decreases with recognition practice. Moreover, performance changes when transferring test type were not fully anticipated by pretest judgments.
Emotional Impact Feedback Changes How We Remember Negative Autobiographical Experiences
Authors: Takarangi Melanie K. T. , Strange Deryn
Published: December 2009

When people are told that their negative memories are worse than other people’s, do they later remember those events differently? We asked participants to recall a recent negative memory then, 24 h later, we gave some participants feedback about the emotional impact of their event – stating it was more or less negative compared to other people’s experiences. One week later, participants recalled the event again. We predicted that if feedback affected how participants remembered their negative experiences, their ratings of the memory’s characteristics should change over time. That is, when participants are told that their negative event is extremely negative, their memories should be more vivid, recollected strongly, and remembered from a personal perspective, compared to participants in the other conditions. Our results provide support for this hypothesis. We suggest that external feedback might be a potential mechanism in the relationship between negative memories and psychological well-being.
Direct Access to Working Memory Contents
Authors: Bialkova Svetlana , Oberauer Klaus
Published: December 2009

In two experiments participants held in working memory (WM) three digits in three different colors, and updated individual digits with the results of arithmetic equations presented in one of the colors. In the memory-access condition, a digit from WM had to be used as the first number in the equation; in the no-access condition, complete equations were presented so that no information from WM had to be accessed for the computation. Updating a digit not updated in the preceding step took longer than updating the same digit as in the preceding step, a time difference referred to as object-switch costs. Object-switch costs were equal in access and no-access equations, implying that they did not reflect the time to retrieve a new digit from WM. Access equations were completed as fast as no-access equations, implying that access to information in WM is as fast as reading the same information. No-access equations were slowed by a mismatch between the first digit of the presented equation and the to-be-updated digit in WM, showing that this digit is automatically accessed even when not needed. It is concluded that contents and their contexts form composites in WM that are necessarily accessed together.
Effects of Facial Identity on Age Judgments
Authors: Dagovitch Yuly , Ganel Tzvi
Published: December 2009

According to current face recognition models, facial identity is processed independently from other visually derived facial aspects, such as facial age. Here we used a repetition priming paradigm to investigate the relationship between the processing of facial identity and facial age. In Experiment 1, participants made speeded age classifications for primed and unprimed faces of famous celebrities. Performance was faster and more accurate for primed compared to unprimed faces, which indicates that the processing of facial age benefits from priming effects. In Experiment 2, priming was also found for preexperimentally unfamiliar faces which were familiarized during the experimental session. In Experiment 3, priming effects were found even when different photos of the same people were presented at study and at test. These results suggest that the processing of age is mediated by memory representations of facial identity.
The Role of a Change Heuristic in Judgments of Sound Intensity
Authors: Leboe Launa C. , Mondor Todd A.
Published: December 2009

Leboe and Mondor (2008) demonstrated that participants will apply a change heuristic when making duration judgments. In this study we investigated whether participants would apply this same change heuristic when making judgments about the perceived intensity of a sound. In two experiments, participants were presented with two consecutive sounds on each of a series of trials and their task was to judge whether the second sound was louder or quieter than the first. In Experiment 1, participants were more likely to judge sounds that increased in frequency as louder in intensity than sounds that maintained a constant frequency. In Experiment 2, participants were more likely to judge sounds that either increased or decreased in frequency as louder in intensity than sounds that maintained a constant frequency. We interpret these results as evidence that reliance on a change heuristic leads to the illusion of increased intensity.
Effects of a Priori Liking on the Elicitation of Mimicry
Authors: Stel Mariëlle , van Baaren Rick B. , Blascovich Jim , van Dijk Eric , McCall Cade , Pollmann Monique M. H. , van Leeuwen Matthijs L. , Mastop Jessanne , Vonk Roos
Published: December 2009

Mimicry and prosocial feelings are generally thought to be positively related. However, the conditions under which mimicry and liking are related largely remain unspecified. We advance this specification by examining the relationship between mimicry and liking more thoroughly. In two experiments, we manipulated an individual’s a priori liking for another and investigated whether it influenced mimicry of that person. Our experiments demonstrate that in the presence of a reason to like a target, automatic mimicry is increased. However, mimicry did not decrease when disliking a target. These studies provide further evidence of a link between mimicry and liking and extend previous research by showing that a certain level of mimicry even occurs when mimicry behavior is inconsistent with one’s goals or motivations.
The Search for Oculomotor Inhibition
Authors: Van der Stigchel Stefan
Published: December 2009

When a saccadic target is presented simultaneously with a distractor, the distractor has to be inhibited in order to successfully perform an eye movement to the target. Insufficient inhibition results in an erroneous eye movement to the distractor. This study investigated whether the influence of a distractor on eye movements is mediated by working memory. A working memory task was added to a saccadic paradigm in which an irrelevant element had to be inhibited. Results show that participants made more erroneous saccades to the distractor when working memory was occupied. This suggests that working memory is involved in the oculomotor inhibition of saccadic distractors.
Violent Content Enhances Video Game Performance
Authors: Bösche Wolfgang
Published: December 2009

This study assesses the impact of violent video game content on players’ game performance. According to the desensitization hypothesis ( Carnagey, Anderson, & Bushman, 2007 ), violent content may elicit negative affective responses and inhibitions, which in turn should interfere with performance. On the other hand, the players might understand virtual violent acts as a digital form of rough-and-tumble play, associated with positive emotions and mobilization, which in turn should raise performance. To test these competing hypotheses on game performance, N = 50 males with no prior violent gaming experience were exposed to three different versions of a custom-made video game in which the actions to be performed were identical, though they were audio-visually presented to appear either nonviolent, moderately, or extremely violent. The results show no indication of an initial inhibition of aggressive behavior, that is, performance is elevated and remains so if the action is presented audio-visually as being violent. This supports the notion that being involved in violent video game activity is perceived as an essentially harmless acting-out of playful fighting behavior.
Challenging the Frame in the News
Authors: Van Gorp Baldwin , Vettehen Paul Hendriks , Beentjes Johannes W.J.
Published: December 2009

The present study contributes to the external validity of the framing concept by studying the effects of frames actually utilized in newspaper articles. The study assesses the persuasive influence of such frames on the interpretation of news, and how issue involvement and attitude interfere in this process. A total of 282 participants were presented with one of three experimental versions of a newspaper article about asylum. In the first condition the asylum seekers were implicitly labeled as innocent victims, in the second as intruders. The third version is a mixed condition in which both competing frames were applied. In all three conditions an identical photograph was inserted. The findings indicate that the frame suggests how the photograph can be interpreted. However, no indications were found for a moderating role of the news readers’ issue involvement or attitude.
Connecting past and present climate variability to the water levels of Lakes Michigan and Huron
Authors: Hanrahan Janel L. , Kravtsov Sergey V. , Roebber Paul J.
Published: December 2009

The water levels of Lakes Michigan and Huron have been monitored since 1865, and numerous attempts have since been made to connect their variations to potentially predictable large‐scale climate modes. In the present study, the levels are analyzed after outflow‐related damping effects were removed, increasing the transparency of the lake level fluctuations and potential climate connections. This filtering exposes a large oscillation which is connected to the Atlantic Multidecadal Oscillation (AMO), and a ∼27‐yr periodicity that is likely resulting from the intermodulation of two near‐decadal cycles originating in the North Atlantic region. While the lake level fluctuations prior to 1980 were predominately driven by changes in precipitation, it is now found that for the first time in our years of record, evaporation has begun to significantly contribute to lake level changes. Summertime evaporation rates have more than doubled since 1980 as a result of increasing water‐surface temperatures, which are significantly correlated with decreasing wintertime ice cover.
Trends in tropical cyclones in the South Indian Ocean and the South Pacific Ocean
Authors: Kuleshov Y. , Fawcett R. , Qi L. , Trewin B. , Jones D. , McBride J. , Ramsay H.
Published: December 2009

The statistical significance of trends in tropical cyclones (TCs) in the South Indian Ocean (SIO) and the South Pacific Ocean (SPO) has been examined. Calculation of significance is based on nonparametric Monte Carlo methods, and in addition we explore whether a constant model, a linear model, or a simple breakpoint model represents a best fit to the data. For the 1981–1982 to 2006–2007 TC seasons, there are no apparent trends in the total numbers of TCs (by which, in this study, we mean those tropical systems attaining a minimum central pressure of 995 hPa or lower), nor in numbers of 970 hPa TCs in the SIO and the SPO (such TCs being called severe in the Southern Hemisphere). Positive trends in the numbers of 945 hPa and 950 hPa TCs in the SIO are significant but appear to be influenced to some extent by changes in data quality. In the Australian region, no significant trends in the total numbers of TCs, or in the proportion of the most intense TCs, have been found.
IUPAC-NIST Solubility Data Series. 87. Rare Earth Metal Chlorides in Water and Aqueous Systems. Part 3. Heavy Lanthanides (Gd–Lu)
Authors: Mioduski Tomasz , Gumiński Cezary , Zeng Dewen
Published: December 2009

This is the third and last part of the volume devoted to solubility data of rare earth metal chlorides in water and in ternary and quaternary aqueous systems. Compilations of all available experimental data for each rare earth metal chloride are introduced with a corresponding critical evaluation. Every such evaluation contains a tabulated collection of all solubility results in water, a scheme of the water-rich part of the equilibrium LnCl3–H2O phase diagram, solubility equation(s), a selection of suggested solubility data, and a brief discussion of the multicomponent systems. Because the ternary and quaternary systems were almost never studied more than once, no critical evaluations or systematic comparisons of such data were possible. Simple chlorides (no complexes) of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are treated as the input substances. The literature (including a thorough coverage of papers in Chinese and Russian) has been covered through the middle of 2008.
Optical Constants and Inelastic Electron-Scattering Data for 17 Elemental Metals
Authors: Werner Wolfgang S. M. , Glantschnig Kathrin , Ambrosch-Draxl Claudia
Published: December 2009

Two new sets of optical data, i.e., values for the real (ε1) and imaginary (ε2) parts of the complex dielectric constant as well as the energy loss function (ELF) (Im{−1∕ε}), are presented for 16 elemental metals (Ti, V, Fe, Co, Ni, Cu, Zn, Mo, Pd, Ag, Ta, W, Pt, Au, Pb, and Bi) and 1 semimetal (Te) and are compared to available data in the literature. One data set is obtained from density functional theory (DFT) calculations and gives ε from the infrared to the soft x-ray range of wavelengths. The other set of optical constants, derived from experimental reflection electron energy-loss spectroscopy (REELS) spectra, provides reliable optical data from the near-ultraviolet to the soft x-ray regime. The two data sets exhibit very good mutual consistency and also, overall, compare well with optical data found in the literature, most of which were determined several decades ago. However, exceptions to this rule are also found in some instances, some of them systematic, where the DFT and REELS mutually agree significantly better than with literature data. The accuracy of the experimental data is estimated to be better than 10% for the ELF and ε2 as well as for ε1 for energies above 10eV. For energies below 10eV, the uncertainty in ε1 in the experimental data may exceed 100%, which is a consequence of the fact that energy-loss measurements mainly sample the absorptive part of the dielectric constant. Electron inelastic-scattering data, i.e., the differential inverse inelastic mean free path (IMFP) as well the differential and total surface excitation probabilities are derived from the experimental data. Furthermore, the total electron IMFP is calculated from the determined optical constants by employing linear response theory for energies between 200 and 3000eV. In the latter case, the consistency between the DFT and the REELS data is excellent (better than 5% for all considered elements over the entire energy range considered) and a very good agreement with earlier results is also obtained, except for a few cases for which the earlier optical data deviate significantly from those obtained here.
Contact resistance between metal and carbon nanotube interconnects: Effect of work function and wettability
Authors: Lim Seong Chu , Jang Jin Ho , Bae Dong Jae , Han Gang Hee , Lee Sunwoo , Yeo In-Seok , Lee Young Hee
Published: January 2010

The contact resistance of 14 different electrode metals with the work function between 3.9 and 5.7 eV has been investigated for carbon nanotube (CNT) interconnects. We observed that the contact resistance was mainly influenced by the two following parameters: the wettability and the work function difference of electrode metal to CNT. Ti, Cr, and Fe with good wettability showed lower resistance than other metals. Furthermore, no dependence of the contact resistance on the work function difference has been observed. However, the contact resistance of Au, Pd, and Pt with poor wettability increased as the work function difference became larger.
Fast scanning probe for the NSTX spherical tokamak
Authors: Boedo J. A. , Crocker N. , Chousal L. , Hernandez R. , Chalfant J. , Kugel H. , Roney P. , Wertenbaker J. ,   NSTX Team
Published: January 2010

We describe a fast reciprocating Langmuir probe and drive system, which has four main new features: (1) use of high-temperature, vacuum, circuit boards instead of cables to reduce weight and increase to 21 the number of possible connections, (2) rotatable and removable shaft, (3) 10 tip construction with designed hardware bandwidth up to 10 MHz, and (4) a detachable and modular tip assembly for easy maintenance. The probe is mounted in a fast pneumatic drive capable of speeds ∼7 m/s and ∼20g’s acceleration in order to reach the scrape-off layer (SOL) and pedestal regions and remain inserted long enough to obtain good statistics while minimizing the heat deposition to the tips and head in a power density environment of 1–10 MW/m2. The National Spherical Torus Experiment SOL features electron temperature, Te∼10–30 eV, and electron density, ne∼0.1–5×1012 cm−3 while the pedestal features ne∼0.5–1.5×1013 cm−3 and Te∼30–150 eV. The probe described here has ten tips which obtain a wide spectrum of plasma parameters: electron temperature profile Te(r), electron density profile ne(r) and Mach number profile M(r), floating potential Vf(r), poloidal and radial electric field profiles Eθ(r) and Eρ(r), saturation current profile Isat(r), and their fluctuations up to 3 MHz. We describe the probe and show representative radial profiles of various parameters.
Anharmonic OH vibrations in Mg(OH)2 (brucite): Two-dimensional calculations and crystal-induced blueshift
Authors: Hermansson Kersti , Probst Michael M. , Gajewski Grzegorz , Mitev Pavlin D.
Published: January 2010

A two-dimensional quantum-mechanical vibrational model has been used to calculate the anharmonic OH vibrational frequencies in the layered Mg(OH)2 (brucite) crystal. The underlying potential energy surface was generated by density functional theory (DFT) calculations. The resulting OH frequencies are upshifted (blueshifted) by about +75 cm−1 with respect to the gas-phase OH frequency (+120 cm−1 in experiments; the discrepancy is mainly due to inadequacies in the DFT and pseudopotential models). The Raman-IR split is about 50 cm−1, both in the calculations and in experiments. We find that the blueshift phenomenon in brucite can qualitatively be explained by a parabolalike “OH frequency versus electric field” correlation curve pertaining to an OH− ion exposed to an electric field. We also find that it is primarily the neighbors within the Mg(OH)2 layer that induce the blueshift while the interlayer interaction gives a smaller (and redshifting) contribution.
Epitaxial growth of fcc-CoxNi100−x thin films on MgO(110) single-crystal substrates
Authors: Ohtake Mitsuru , Nukaga Yuri , Sato Yoichi , Kirino Fumiyoshi , Futamoto Masaaki
Published: January 2010

Co x Ni 100 − x (x=100, 80, 20, 0 at. %) epitaxial thin films were prepared on MgO(110) single-crystal substrates heated at 300 °C by ultrahigh vacuum molecular beam epitaxy. The growth mechanism is discussed based on lattice strain and crystallographic defects. CoNi(110) single-crystal films with a fcc structure are obtained for all compositions. CoxNi100−x film growth follows the Volmer–Weber mode. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of the CoxNi100−x films are in agreement within ±0.5% with the values of the respective bulk CoxNi100−x crystals, suggesting that the strain in the film is very small. High-resolution cross-sectional transmission microscopy shows that an atomically sharp boundary is formed between a Co(110)fcc film and a MgO(110) substrate, where periodical misfit dislocations are preferentially introduced in the film at the Co/MgO interface. The presence of such periodical misfit dislocations relieves the strain caused by the lattice mismatch between the film and the substrate.
Prediction of charge-transfer excitations in coumarin-based dyes using a range-separated functional tuned from first principles
Authors: Stein Tamar , Kronik Leeor , Baer Roi
Published: January 2010

We study the description of charge-transfer excitations in a series of coumarin-based donor-bridge-acceptor dyes. We show that excellent predictive power for the excitation energies and oscillator strengths in these systems is obtained by using a range-separated hybrid functional within the generalized Kohn–Sham approach to time-dependent density functional theory. Key to this success is a step for tuning the range separation parameter from first principles. We explore different methods for this tuning step, which are variants of a recently suggested approach for charge-transfer excitations [T. Stein et al., J. Am. Chem. Soc. 131, 2818 (2009)]. We assess the quality of prediction by comparing to excitation energies previously published for the same systems using the approximate coupled-cluster singles and doubles (CC2) method.
Theoretical study of one- and two-photon absorption spectra of azoaromatic compounds
Authors: Silva D. L. , Krawczyk P. , Bartkowiak W. , Mendonça C. R.
Published: January 2010

In this study, the one- and two-photon absorption spectra of seven azoaromatic compounds (five pseudostilbenes-type and two aminoazobenzenes) were theoretically investigated using the density functional theory combined with the response functions formalism. The equilibrium molecular structure of each compound was obtained at three different levels of theory: Hartree–Fock, density functional theory (DFT), and Møller–Plesset 2. The effect of solvent on the equilibrium structure and the electronic transitions of the compounds were investigated using the polarizable continuum model. For the one-photon absorption, the allowed π→π∗ transition energy showed to be dependent on the molecular structures and the effect of solvent, while the n→π∗ and π→π∗(n) transition energies exhibited only a slight dependence. An inversion between the bands corresponding to the π→π∗ and n→π∗ states due to the effect of solvent was observed for the pseudostilbene-type compounds. To characterize the allowed two-photon absorption transitions for azoaromatic compounds, the response functions formalism combined with DFT using the hybrid B3LYP and PBE0 functionals and the long-range corrected CAM-B3LYP functional was employed. The theoretical results support the previous findings based on the three-state model. The model takes into account the ground and two electronic excited states and has already been used to describe and interpret the two-photon absorption spectrum of azoaromatic compounds. The highest energy two-photon allowed transition for the pseudostilbene-type compounds shows to be more effectively affected (∼20%) by the torsion of the molecular structure than the lowest allowed transition (∼10%). In order to elucidate the effect of the solvent on the two-photon absorption spectra, the lowest allowed two-photon transition (dipolar transition) for each compound was analyzed using a two-state approximation and the polarizable continuum model. The results obtained reveal that the effect of solvent increases drastically the two-photon cross-section of the dipolar transition of the pseudostilbene-type compounds. In general, the features of both one- and two-photon absorption spectra of the azoaromatic compounds are well reproduced by the theoretical calculations.
A radio-frequency source using direct digital synthesis and field programmable gate array for nuclear magnetic resonance
Authors: Liang Xiao , Weimin Wang
Published: January 2010

A radio-frequency (rf) source for nuclear magnetic resonance (NMR) is described. With the application of direct digital synthesis (DDS), the rf source has the ability to yield rf pulses with short switching time and high resolution in frequency and phase. To facilitate the generation of a soft pulse, a field programmable gate array (FPGA) cooperating with a pulse programmer is used as the auxiliary controller of the DDS chip. Triggered by the pulse programmer, the FPGA automatically controls the DDS to generate soft pulse according to predefined parameters, and the operation mode of the pulse programmer is optimized. The rf source is suitable for being used as transmitter in low-field (<1 T) NMR applications, for example, magnetic resonance imaging and relaxation measurement. As a compact and low-cost module, the rf source is of general use for constructing low-field NMR spectrometer.
Measurement of specimen dimensions and dynamic pressure in dynamic triaxial experiments
Authors: Kabir Md. E. , Chen Weinong W.
Published: January 2010

Novel experimental techniques are developed to measure the rapid changes in specimen dimensions during dynamic triaxial experiments. A capacitance gage is designed and constructed to measure the diameter change of the specimen inside the pressure chamber at both low and high rates. The length change is determined by a linear variable differential transformer at low rates and by Kolsky bar signals at high rates. The Kolsky bar also measures the dynamic axial stress in the specimen during the high-rate phase of an experiment. A line pressure gage records the hydrostatic pressure in the chamber. The dynamic pressure variation in the chamber during axial impact loading is detected by a manganin gage placed inside the chamber. The feasibility of this new experimental setup is demonstrated by dynamic triaxial experiments on a fine dry sand.
Photoinduced long-term memory effects in n-type organic perylene transistors
Authors: Barra M. , Bloisi F. , Cassinese A. , Di Girolamo F. V. , Vicari L.
Published: January 2010

In this paper, the photoexcitation response of high mobility n-type organic field-effect transistors is analyzed. White light exposure of N,N′-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C8H) transistors is demonstrated to promote the occurrence of metastable conductance states with very long retention times, similar to what has been previously reported for p-type compounds. Even in the absence of a gate-source voltage VGS, the complete recovery of the initial electrical condition can take up to 20 days. However, the initial state restoring is electrically controllable by the application of a positive VGS. These effects suggest that PTCDI-C8H is an interesting n-type material for the development of light-sensitive organic circuitry.
Modeling the effects of microencapsulation on the electro-optic behavior of polymer cholesteric liquid crystal flakes
Authors: Cox G. P. , Marshall K. L. , Lambropoulos J. C. , Leitch M. , Fromen C. , Jacobs S. D.
Published: January 2010

A method for modeling the effect of microencapsulation on the electro-optical behavior of polymer cholesteric liquid crystal (PCLC) flakes suspended in a host fluid is introduced. Several microencapsulation configurations in an applied ac electric field are investigated using COMSOL MULTIPHYSICS software in combination with an analytical model. The field acting on the flakes is significantly altered as various encapsulant materials and boundary conditions are explored. The modeling predicts that test cells with multiple materials in the electric field path can have a wide range of electro-optic responses in ac electric fields. Both theoretical predictions and experimental evidence show that for PCLC flake reorientation to occur due to Maxwell–Wagner polarization, a reasonably strong electric field must be present along with at least moderately dissimilar PCLC flake and host fluid material dielectric constants and conductivities. For materials with low dielectric constants, electrophoretic behavior is observed under dc drive conditions at high field strengths for all evaluated microencapsulation configurations. This modeling method is shown to be a useful predictive tool for developing switchable particle devices that use microencapsulated dielectric particles in a host fluid medium.
A spin on cavity formation during water entry of hydrophobic and hydrophilic spheres
Authors: Truscott Tadd T. , Techet Alexandra H.
Published: January 2010

Surface coating and impact velocity can dramatically affect cavity formation during water entry of spheres. Duez et al. [Nat. Phys. 3, 180 (2007)] present a theoretical limit, dependent on impact velocity and surface static wetting angle, below which air cavities no longer form. We show that transverse spin alters the spheres surface velocity distribution to straddle this theoretical limit, resulting in cavity formation over half of the sphere and none on the other half, and yields similar results to the case of a sphere dropped without spin, at the same impact speed, when its surface is half hydrophilic and half hydrophobic.
Oxygen vacancies in N doped anatase TiO2: Experiment and first-principles calculations
Authors: Rumaiz Abdul K. , Woicik J. C. , Cockayne E. , Lin H. Y. , Jaffari G. Hassnain , Shah S. I.
Published: January 2010

We have determined the electronic and atomic structure of N doped TiO2 using a combination of hard x-ray photoelectron spectroscopy and first-principles density functional theory calculations. Our results reveal that N doping of TiO2 leads to the formation of oxygen vacancies and the combination of both N impurity and oxygen vacancies accounts for the observed visible light catalytic behavior of N doped TiO2.
Frequency dependence of the electromagnetic-field-induced resistance of a phase-slip line
Authors: Dmitriev V. M. , Zolochevskii I. V.
Published: January 2010

The resistance of a high-frequency phase-slip line (an ac PSL) in a wide tin film has been experimentally investigated as a function of the external irradiation frequency. It is shown that the behavior of the descending branch of the nonmonotonic frequency dependence of the ac PSL resistance agrees well with the theoretical predictions. The behavior of the ascending branch of this frequency dependence is associated with the nonlinear relaxation processes of the population imbalance of the branches of the quasi-particle spectrum under conditions of microwave pumping at irradiation frequencies greater than the inverse charge-imbalance relaxation time. Comparisons are carried out with the analogous dependences for high-frequency phase-slip centers in narrow channels. The dependences of the penetration depth of a variable longitudinal electric field into a superconductor on the frequency and mean free path of the electrons when they are scattered at impurities are obtained.
Dynamics of trapped magnetic fluxes in single-crystal YBCO in weak fields
Authors: Timofeev V. P. , Shablo A. A. , Monarkha V. Yu.
Published: January 2010

The dynamics of low-density trapped magnetic fluxes, including local fluxes, are investigated in single-crystal YBCO in the region of strong thermal fluctuations near the superconducting phase transition. A substantial difference of the isothermal magnetization-relaxation behavior from the quasi-logarithmic behavior observed earlier in strong magnetic fields is established for the first time. The effective pinning potential in the temperature interval close to the critical temperature is estimated in terms of the simplest model of thermally activated creep.
Antiferromagnetic resonance in Mn2P2S6
Authors: Kobets M. I. , Dergachev K. G. , Gnatchenko S. L. , Khats’ko E. N. , Vysochanskii Yu. M. , Gurzan M. I.
Published: January 2010

The antiferromagnetic resonance (AFMR) spectra along the principal magnetic axes x, y, z of the compound Mn2P2S6 have been investigated in detail in a wide range of frequencies (8–142GHz) and magnetic fields (up to 75kOe) at T=4.2K. It is shown that this compound is a biaxial magnetic substance. At H=0, there are two gaps in the spin-wave spectrum: (101.46±0.1) and (115.52±0.1)GHz. The AFMR data were used to determine the effective magnetic-anisotropy fields: Ha1=0.619kOe and Ha2=0.803kOe. An anomalous interaction of the AFMR branches in Mn2P2S6 has been detected, along with the appearance of coupled spin–spin oscillations of the same symmetry. An additional absorption in the AFMR spectrum is a local mode associated with breakdown of translational order in a low-dimension magnet. It is shown for the first time that the appearance of additional absorption peaks depends on the sample-cooling rate. It is proven that the observed peaks are associated with the internal modes of the domain boundaries.
Exciton-stimulated dissociation of D2 in a xenon matrix
Authors: Belov A. G. , Bludov M. A. , Tarasova E. I.
Published: January 2010

This paper presents the results of a study of the VUV and UV cathodoluminescence spectra of Xe-D2 solid mixtures as a function of the D2 concentration and the irradiation dose at T=4.2K. It is shown that a number of radiation-stimulated processes [dissociation of D2, diffusion of fragments, formation of (Xe2D)* excimer complexes, etc.] occur during irradiation in the Xe-D2 solid mixtures, caused by excitation energy transport in the Xe matrix. A mechanism is proposed for the dissociation of D2 in a Xe-D2 solid mixture, associated with the (XeD2)* intermediate complex that is formed when the matrix excitons are localized close to an impurity center.
Cluster formation in supersonic CO2 and CO2–Kr jets
Authors: Danil’chenko A. G. , Kovalenko S. I. , Samovarov V. N.
Published: January 2010

The thermodynamic relationship [V. P. Krainov and M. B. Smirnov, Phys. Rep. 370, 237 (2002)] that connects the number of clusters, the mean number of atoms in a cluster, and the gas-condensation temperature in an adiabatically expanding supersonic jet has been experimental verified for the first time. This relationship was found to be valid both for pure CO2 and for a CO2–Kr gas mixture. The gas-condensation temperatures have been determined to be 95 and 220K in a jet of pure CO2 and in a CO2–Kr mixture.
Magnetic and thermal properties of the nanocomposite compound GdNiO3
Authors: Dmitriev V. M. , Khatsko E. N. , Terekhov A. V. , Rykova A. I. , Cherny A. S. , Kondrashev D. S. , Zaleski A. , Mydlarz T. , Shevchenko A. D. , Uvarov V. N.
Published: January 2010

This paper discusses the temperature and field dependences of the magnetization of the nanocomposite compound GdNiO3 in the temperature interval 0.5–150K in magnetic fields up to 14T. The temperature dependences of the heat capacity are also investigated in magnetic fields up to 9T. Anomalies of the static susceptibility, heat capacity, and dynamic magnetization are detected at temperatures of 0.7, 1.6, and 13K, respectively. The detected anomalies are associated with magnetic phase transitions.