1,721,370 research outputs found
Floquet interpretation of attosecond RABBITT traces
Full text linkOriginally proposed for the temporal characterization of train of attosecond pulses, the reconstruction of attosecond beating by interference of two-photon transitions (RABBITT), has become a wide-spread, powerful technique, capable of capturing ultrafast electron dynamics through an interferometric approach. Starting from the well-known strong-field approximation (SFA) description of a two-color photoelectron spectrum, here we develop a model that interprets a RABBITT trace as the interference of different Floquet ladder states generated in the continuum by a femtosecond infrared (IR) pulse after ionization by the attosecond radiation. In turn, this allowed us to develop an analytical model capable of predicting the amplitude and phase of the oscillating sidebands and main bands while including the effect of nonstandard interference paths and, in first approximation, of the finite IR pulse envelope. Our results thus suggest a way to extend the RABBITT model to higher intensities and beating frequencies, and disentangle different oscillating signals in a congested photoelectron spectrogram as the one associated with molecular targets
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Societal Gender Inequality as Moderator of the Relationship Between Work–Life Fit and Subjective Well-Being: A Multilevel Analysis Across European Countries.
No full textThis study investigates the relationship between perceived work–life fit and subjective well-being in a large and cross-national sample (N = 15,835) of male and female employees taken from the 2012 European Quality of Life Survey. Subjective well-being is conceptualized and operationalized through a multiple-item construct, measuring flourishing and mental health, experience of positive and negative affect, and cognitive evaluations of satisfaction with life and specific life domains. Adopting a multilevel framework, we also examine whether societal gender inequality, measured with the Gender Equality Index, moderates the relationship differently for men and women. The analyses provide robust empirical evidence that, after controlling for a broad set of confounding variables at the micro and macro levels, for both men and women: (1) perceived work–life fit is associated with greater subjective well-being; (2) higher levels of gender inequality at country level result in a weaker relationship between perceived work–life fit and subjective well-being. Based on the capability and agency framework, a plausible explanation for these findings is that when gender inequality is acute perceived work–life fit may not be a key determinant of subjective well-being; for both men and women the control over material resources may matter more for subjective well-being than the possibility of combining work with engagement in other life domains. Implications for both theory and practice are discussed
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
An experimentally validated model of a motorcycle shock absorber for studying suspension dynamics
No full textNowadays advanced shock absorbers are equipped with
hydraulic valves that offer many possibilities of adjustment of
orifices and shims. The theoretical force-velocity curve can be
accurately designed and modified by means of these
adjustments, in order to achieve the desired performance.
Actually, compressibility of gas in compensation chamber,
compressibility of oil, cavitation and compliance of seals and
cylinders can significantly alter the force-velocity diagram.
In some working conditions the behavior of the shock
absorber may differ from the optimized one, with important
consequences on the performance of the vehicle.
Therefore there is the need of mathematical models able to
predict the behavior of shock absorbers in the presence of large
hysteresis phenomena, these models cannot be too complex and
cumbersome, because they have to be implemented in multibody
models of vehicles.
The paper starts showing some experimental data collected
by testing in laboratory a motorcycle shock absorber and aims
to quantify the effect of hysteresis on performance and tuning.
Then a mathematical model of a shock absorber is
developed and presented. Valves are modeled with detail taking
into account flow through bleed orifices and shim stacks and
the effect of adjustments can be predicted. Compressibility of
oil and compliances are taken into account by means of an
equivalent compressibility coefficient.
The model has a little number of parameters and a method
is presented for identifying these parameters from laboratory
tests. Some simulations show that the model is able to predict
the behavior of the shock absorber over a wide range of
frequencies.
After validation, the shock absorber model is implemented
in a two degree of freedom model of a rear suspension of a
motorcycle. A MATLAB code is developed to solve the system of
differential equations that describe the dynamic response of the
suspension and the fluid motion inside the shock absorber. The
response of the vehicle to a road bump is simulated. Simulation
results show the effect of hysteresis and of adjustments of shock
absorber on the performance of the vehicle in terms of
acceleration of the suspended mass and of tire load
fluctuations
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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