519 research outputs found
Emotional agents at the square lattice
We introduce and investigate by numerical simulations a number of models of
emotional agents at the square lattice. Our models describe the most general
features of emotions such as the spontaneous emotional arousal, emotional
relaxation, and transfers of emotions between different agents. Group emotions
in the considered models are periodically fluctuating between two opposite
valency levels and as result the mean value of such group emotions is zero. The
oscillations amplitude depends strongly on probability ps of the individual
spontaneous arousal. For small values of relaxation times tau we observed a
stochastic resonance, i.e. the signal to noise ratio SNR is maximal for a
non-zero ps parameter. The amplitude increases with the probability p of local
affective interactions while the mean oscillations period increases with the
relaxation time tau and is only weakly dependent on other system parameters.
Presence of emotional antenna can enhance positive or negative emotions and for
the optimal transition probability the antenna can change agents emotions at
longer distances. The stochastic resonance was also observed for the influence
of emotions on task execution efficiency.Comment: 28 pages, 19 figures, 3 table
Quantifying layer similarity in multiplex networks: A systematic study
© 2018 The Authors. Computing layer similarities is an important way of characterizing multiplex networks because various static properties and dynamic processes depend on the relationships between layers. We provide a taxonomy and experimental evaluation of approaches to compare layers in multiplex networks. Our taxonomy includes, systematizes and extends existing approaches, and is complemented by a set of practical guidelines on how to apply them
Scaling of human behavior during portal browsing
We investigate transitions of portals users between different subpages. A
weighted network of portals subpages is reconstructed where edge weights are
numbers of corresponding transitions. Distributions of link weights and node
strengths follow power laws over several decades. Node strength increases
faster than linearly with node degree. The distribution of time spent by the
user at one subpage decays as power law with exponent around 1.3. Distribution
of numbers P(z) of unique subpages during one visit is exponential. We find a
square root dependence between the average z and the total number of
transitions n during a single visit. Individual path of portal user resembles
of self-attracting walk on the weighted network. Analytical model is developed
to recover in part the collected data.Comment: 6 pages, 7 figure
A homology model of restriction endonuclease SfiI in complex with DNA
BACKGROUND: Restriction enzymes (REases) are commercial reagents commonly used in recombinant DNA technologies. They are attractive models for studying protein-DNA interactions and valuable targets for protein engineering. They are, however, extremely divergent: the amino acid sequence of a typical REase usually shows no detectable similarities to any other proteins, with rare exceptions of other REases that recognize identical or very similar sequences. From structural analyses and bioinformatics studies it has been learned that some REases belong to at least four unrelated and structurally distinct superfamilies of nucleases, PD-DxK, PLD, HNH, and GIY-YIG. Hence, they are extremely hard targets for structure prediction and homology-based inference of sequence-function relationships and the great majority of REases remain structurally and evolutionarily unclassified. RESULTS: SfiI is a REase which recognizes the interrupted palindromic sequence 5'GGCCNNNN^NGGCC3' and generates 3 nt long 3' overhangs upon cleavage. SfiI is an archetypal Type IIF enzyme, which functions as a tetramer and cleaves two copies of the recognition site in a concerted manner. Its sequence shows no similarity to other proteins and nothing is known about the localization of its active site or residues important for oligomerization. Using the threading approach for protein fold-recognition, we identified a remote relationship between SfiI and BglI, a dimeric Type IIP restriction enzyme from the PD-DxK superfamily of nucleases, which recognizes the 5'GCCNNNN^NGGC3' sequence and whose structure in complex with the substrate DNA is available. We constructed a homology model of SfiI in complex with its target sequence and used it to predict residues important for dimerization, tetramerization, DNA binding and catalysis. CONCLUSIONS: The bioinformatics analysis suggest that SfiI, a Type IIF enzyme, is more closely related to BglI, an "orthodox" Type IIP restriction enzyme, than to any other REase, including other Type IIF REases with known structures, such as NgoMIV. NgoMIV and BglI belong to two different, very remotely related branches of the PD-DxK superfamily: the α-class (EcoRI-like), and the β-class (EcoRV-like), respectively. Thus, our analysis provides evidence that the ability to tetramerize and cut the two DNA sequences in a concerted manner was developed independently at least two times in the evolution of the PD-DxK superfamily of REases. The model of SfiI will also serve as a convenient platform for further experimental analyses
Collective emotions online and their influence on community life
E-communities, social groups interacting online, have recently become an
object of interdisciplinary research. As with face-to-face meetings, Internet
exchanges may not only include factual information but also emotional
information - how participants feel about the subject discussed or other group
members. Emotions are known to be important in affecting interaction partners
in offline communication in many ways. Could emotions in Internet exchanges
affect others and systematically influence quantitative and qualitative aspects
of the trajectory of e-communities? The development of automatic sentiment
analysis has made large scale emotion detection and analysis possible using
text messages collected from the web. It is not clear if emotions in
e-communities primarily derive from individual group members' personalities or
if they result from intra-group interactions, and whether they influence group
activities. We show the collective character of affective phenomena on a large
scale as observed in 4 million posts downloaded from Blogs, Digg and BBC
forums. To test whether the emotions of a community member may influence the
emotions of others, posts were grouped into clusters of messages with similar
emotional valences. The frequency of long clusters was much higher than it
would be if emotions occurred at random. Distributions for cluster lengths can
be explained by preferential processes because conditional probabilities for
consecutive messages grow as a power law with cluster length. For BBC forum
threads, average discussion lengths were higher for larger values of absolute
average emotional valence in the first ten comments and the average amount of
emotion in messages fell during discussions. Our results prove that collective
emotional states can be created and modulated via Internet communication and
that emotional expressiveness is the fuel that sustains some e-communities.Comment: 23 pages including Supporting Information, accepted to PLoS ON
Networks of companies and branches in Poland
In this study we consider relations between companies in Poland taking into
account common branches they belong to. It is clear that companies belonging to
the same branch compete for similar customers, so the market induces
correlations between them. On the other hand two branches can be related by
companies acting in both of them. To remove weak, accidental links we shall use
a concept of threshold filtering for weighted networks where a link weight
corresponds to a number of existing connections (common companies or branches)
between a pair of nodes.Comment: 13 pages, 10 figures and 4 table
Laser induced birefringence in La–Ga–S–O–Gd glass polymer nanocomposites
In this work, we demonstrate a possibility to use La–Ga–S–O–Gd glass polymer nanocomposites as effective materials for photo-induced birefringence. Here we chose PVA as a photopolymer matrix. The photo-induced effects were studied using 8 ns Nd: YAG laser generating bicolor coherent light beams with wavelengths 1064, and 532 nm. The detection of the photo-induced birefringence was carried out using cw He–Ne laser at 1150 nm. The optimal concentration of the nanoglass favoring maximal changes of refractive indices is established. The photo-induced laser power density was changed up to 0.9 GW/cm2. The photo-induced beams were incident at angles varying within the 32° and 52° with respect to the nanocomposite planes. The polarizations of the beams did not play principal role. We discovered an appearance of maximal birefringence equal to about 0.078. The effect is strongly dependent on the nanoparticle sizes and is completely reversible after switching off the laser treatment within several milliseconds. Such features are useful for the recording of optical information and production of gratings with desirable periods
Correlation Structures of Correlated Binomial Models and Implied Default Distribution
We show how to analyze and interpret the correlation structures, the
conditional expectation values and correlation coefficients of exchangeable
Bernoulli random variables. We study implied default distributions for the
iTraxx-CJ tranches and some popular probabilistic models, including the
Gaussian copula model, Beta binomial distribution model and long-range Ising
model. We interpret the differences in their profiles in terms of the
correlation structures. The implied default distribution has singular
correlation structures, reflecting the credit market implications. We point out
two possible origins of the singular behavior.Comment: 16 pages, 7 figure
Ganciclovir/valganciclovir prophylaxis decreases cytomegalovirus-related events and bronchiolitis obliterans syndrome after lung transplantation
BACKGROUND: Until recently, cytomegalovirus (CMV) infection represented a major threat to lung transplant recipients. Preliminary studies have shown that antiviral prophylaxis might improve the outcome for these patients. METHODS: We extended our initial pilot trial of prolonged prophylaxis with either oral ganciclovir (1 g 3 times per day) or valganciclovir (450 mg twice per day). The trial included 96 patients who were at risk for CMV-related events. RESULTS: CMV prophylaxis resulted in a significant decrease in CMV-related events (i.e., active infection and disease), from 75% in a control group and for 274 cases from the literature who did not receive prophylaxis to a cumulative incidence of 27% (P < .001). Only 11% of the prophylaxis recipients experienced CMV disease (P = .002). Moreover, at 5 years, there was a significant decrease in the rate of bronchiolitis obliterans syndrome, from 60% to 43% (P = .002), and an improved rate of survival, from 47% to 73% (P= .036), irrespective of the immunosuppressive regimen received. CMV strains with UL97 mutations were recovered from 7 of 12 analyzed cases, but the presence of this mutation had no impact on the severity of CMV disease. CONCLUSIONS: A regimen of prolonged ganciclovir or valganciclovir prophylaxis decreased the rate of active CMV infection and disease, reduced the incidence of bronchiolitis obliterans syndrome, and improved the survival rate. Drug-resistant CMV strains may occur, but such strains appeared to have no impact on the outcome of CMV-related events
Enlistment standards as applied to the Navy selection process with reference to the Signalman and Radioman ratings
Ihe purpose ox this thesis is to develop manpower selection
models to improve the Navy's system of assigning
personnel tc the Signalman (Sli) and Radioman (RM) ratings.
four Eultivariate models using "success" ana "failure" as
criterion variables were developed. The criterion was
comprised of; months of total active federal military
service (lAFMSI) , achieved Z-4 (ACHVDE4) and recommended for
re-enlistment (E1IGRIUPJ . Predictor variables were derived
from personal biographical and aptitude data available at
enlistment.
Cf the models developed , one was designed for application
to the entire Signalman rating, another for the entire
Radiciai rating. The third model is for application tc the
white male segment of the Signalman rating; the fourth, to
the white male segment of the Radioman rating.
Additionally, the study highlights the link with current
seiecticc procedures and characteristics and tneir possible
effect cc manpower modeling.
The cohort used in the study entered the Navy in 1976,
1977 and 1S73. Results and recommendations for future
research are alsc presented.http://archive.org/details/enlistmentstanda00chmiLieutenant Commander, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited
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