Networks are widely used as a tool for describing diverse real complex systems and have been successfully applied to many fields. The distance between networks is one of the most fundamental concepts ...for properly classifying real networks, detecting temporal changes in network structures, and effectively predicting their temporal evolution. However, this distance has rarely been discussed in the theory of complex networks. Here, we propose a graph distance between networks based on a Laplacian matrix that reflects the structural and dynamical properties of networked dynamical systems. Our results indicate that the Laplacian-based graph distance effectively quantifies the structural difference between complex networks. We further show that our approach successfully elucidates the temporal properties underlying temporal networks observed in the context of face-to-face human interactions.
Online social media are increasingly facilitating our social interactions, thereby making available a massive "digital fossil" of human behavior. Discovering and quantifying distinct patterns using ...these data is important for studying social behavior, although the rapid time-variant nature and large volumes of these data make this task difficult and challenging. In this study, we focused on the emergence of "collective attention" on Twitter, a popular social networking service. We propose a simple method for detecting and measuring the collective attention evoked by various types of events. This method exploits the fact that tweeting activity exhibits a burst-like increase and an irregular oscillation when a particular real-world event occurs; otherwise, it follows regular circadian rhythms. The difference between regular and irregular states in the tweet stream was measured using the Jensen-Shannon divergence, which corresponds to the intensity of collective attention. We then associated irregular incidents with their corresponding events that attracted the attention and elicited responses from large numbers of people, based on the popularity and the enhancement of key terms in posted messages or "tweets." Next, we demonstrate the effectiveness of this method using a large dataset that contained approximately 490 million Japanese tweets by over 400,000 users, in which we identified 60 cases of collective attentions, including one related to the Tohoku-oki earthquake. "Retweet" networks were also investigated to understand collective attention in terms of social interactions. This simple method provides a retrospective summary of collective attention, thereby contributing to the fundamental understanding of social behavior in the digital era.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The circadian clock is synchronized by environmental cues, mostly by light and temperature. Explaining how the plant circadian clock responds to temperature oscillations is crucial to understanding ...plant responsiveness to the environment. Here, we found a prevalent temperature-dependent function of the Arabidopsis clock component EARLY FLOWERING 4 (ELF4) in the root clock. Although the clocks in roots are able to run in the absence of shoots, micrografting assays and mathematical analyses show that ELF4 moves from shoots to regulate rhythms in roots. ELF4 movement does not convey photoperiodic information, but trafficking is essential for controlling the period of the root clock in a temperature-dependent manner. Low temperatures favour ELF4 mobility, resulting in a slow-paced root clock, whereas high temperatures decrease movement, leading to a faster clock. Hence, the mobile ELF4 delivers temperature information and establishes a shoot-to-root dialogue that sets the pace of the clock in roots.
Single-cell analysis of the three-dimensional (3D) chromosome structure can reveal cell-to-cell variability in genome activities. Here, we propose to apply recurrence plots, a mathematical method of ...nonlinear time series analysis, to reconstruct the 3D chromosome structure of a single cell based on information of chromosomal contacts from genome-wide chromosome conformation capture (Hi-C) data. This recurrence plot-based reconstruction (RPR) method enables rapid reconstruction of a unique structure in single cells, even from incomplete Hi-C information.
Intermittent androgen suppression is becoming a standard clinical option for patients who suffer from recurrence after an initial treatment of prostate cancer such as radiation therapy and radical ...prostatectomy. In the first mathematical model of intermittent androgen suppression (Ideta et al., 2008), the authors tried to control the trajectory of the model to a periodic orbit to enable patients to coexist with prostate cancer, even if it cannot be eradicated. Recently, we proposed a mathematical model capable of improving the quantitative reproduction of the behavior of prostate cancer under intermittent androgen suppression (Hirata et al., 2010a). Here we examine whether such a stable periodic orbit can be created for patients who eventually will have to experience the relapse of cancer at a later stage. By using a mathematical analysis, we found that the above model of Hirata et al. does not contain a non-zero periodic orbit that can be targeted for such patients, namely patients of type (ii) or type (iii) for whom intermittent androgen suppression cannot stabilize the origin where no cancer cells exist. This result might suggest that the patients must seek to delay the relapse as much as possible if the cancer cannot be eradicated. We further classify type (i) into subclasses where such a non-zero periodic orbit can either be stabilized or asymptotically stabilized.
•Examined if a periodic orbit can be targeted in intermittent androgen suppression.•A periodic orbit can be targeted only when a patient is classified as type (i).•Another strategy must be sought when the relapse of prostate cancer is inevitable.
Abstract Seismicity is a complex phenomenon with a multitude of components involved. In order to perform forecasting, which has yet to be done sufficiently well, it is paramount to be in possession ...of information of all these components, and use this information effectively in a prediction model. In the literature, the influence of the Sun and the Moon in seismic activity on Earth has been discussed numerous times. In this paper we contribute to such discussion, giving continuity to a previous work. Most importantly, we instrument four earthquake catalogs from different regions, calculating the Moon tidal force at the region and time of each earthquake, which allows us to analyze the relation between the tidal forces and the earthquake magnitudes. At first, we find that the dynamical system governing Moon motion is unidirectionally coupled with seismic activity, indicating that the position of the Moon drives, to some extent, the earthquake generating process. Furthermore, we present an analysis that demonstrates a clear positive correlation between tidal force and earthquake magnitude. Finally, it is shown that the use of Moon tidal force data and sunspot number data can be used to improve next-day maximum magnitude forecasting, with the highest accuracy being achieved when using both kinds of data. We hope that our results encourage researchers to include data from Moon tidal forces and Sun activity in their earthquake forecasting models.
The drilling characteristics of alumina ceramics during through-hole drilling with a diamond-coated carbide drill were investigated experimentally. The drilling characteristics were evaluated by ...cutting edge behavior, cutting force (thrust force and torque), and chipping state at the exit side of the drilled hole in relation to the number of drilled holes. Additionally, the effects of the diamond-coating thickness and drill feed rate were investigated. The drills had a typical twist shape and were made of tungsten carbide base material with diamond coatings at 10 μm and 20 μm thick. The drilling machine was a standard machining center with a simple unidirectional drill feed without vibration. In through-hole drilling, as in blind-hole drilling, the coating on the rake face flaked during the initial stage of drilling, resulting in a sharp cutting edge on the diamond-coating ridge remaining on the flank face. However, flaking of the diamond coating on the rake face was observed earlier during through-hole drilling than in blind-hole drilling. Although the chipping area increased with increasing drill feed rate, coating flaking on the rake face significantly suppressed it at all feed rates. There was a clear correlation between the chipping area and cutting force since the chipping area decreased with decreasing thrust force. Before the theoretical hole penetration, hat-shaped chipping was observed with two crack propagation directions, accompanied by a sharp decrease in thrust force. Moreover, even after observing a sharp decrease in thrust force, a gradual decrease in thrust force was observed in the case of a good chipping state. The chipping area was significantly improved by reducing the coating thickness, and the thrust force was reduced.
Using a dataset of 150 patients treated with intermittent androgen suppression (IAS) through a fixed treatment schedule, we retrospectively designed a personalized treatment schedule mathematically ...for each patient. We estimated 100 sets of parameter values for each patient by randomly resampling each patient's time points to take into account the uncertainty for observations of prostate specific antigen (PSA). Then, we identified 3 types and classified patients accordingly: in type (i), the relapse, namely the divergence of PSA, can be prevented by IAS; in type (ii), the relapse can be delayed by IAS later than by continuous androgen suppression (CAS); in type (iii) IAS was not beneficial and therefore CAS would have been more appropriate in the long run. Moreover, we obtained a treatment schedule of hormone therapy by minimizing the PSA of 3 years later in the worst case scenario among the 100 parameter sets by searching exhaustively all over the possible treatment schedules. If the most frequent type among 100 sets was type (i), the maximal PSA tended to be kept less than 100 ng/ml longer in IAS than in CAS, while there was no statistical difference for the other cases. Thus, mathematically personalized IAS should be studied prospectively.
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