54 research outputs found
Testing a Possible Way of Geometrization of the Strong Interaction by a Kaluza-Klein Star
Geometrization of the fundamental interactions has been extensively studied
during the century. The idea of introducing compactified spatial dimensions
originated by Kaluza and Klein. Following their approach, several model were
built representing quantum numbers (e.g. charges) as compactified space-time
dimensions. Such geometrized theoretical descriptions of the fundamental
interactions might lead us to get closer to the unification of the principle
theories.
Here, we apply a dimensional theory, which contains one extra
compactified spatial dimension in connection with the flavour quantum
number in Quantum Chromodynamics. Within our model the size of the
dimension is proportional to the inverse mass-difference of the first low-mass
baryon states. We used this phenomena to apply in a compact star model -- a
natural laboratory for testing the theory of strong interaction and the
gravitational theory in parallel.
Our aim is to test the modification of the measurable macroscopical
parameters of a compact Kaluza-Klein star by varying the size of the
compactified extra dimension. Since larger the the smaller the mass
difference between the first spokes of the Kaluza-Klein ladder resulting
smaller-mass stars. Using the Tolman-Oppenheimer-Volkov equation, we
investigate the - diagram and the dependence of the maximum mass of
compact stars. Besides testing the validity of our model we compare our results
to the existing observational data of pulsar properties for constraints.Comment: 10 pages, 2 figure
Communities and beyond: mesoscopic analysis of a large social network with complementary methods
Community detection methods have so far been tested mostly on small empirical
networks and on synthetic benchmarks. Much less is known about their
performance on large real-world networks, which nonetheless are a significant
target for application. We analyze the performance of three state-of-the-art
community detection methods by using them to identify communities in a large
social network constructed from mobile phone call records. We find that all
methods detect communities that are meaningful in some respects but fall short
in others, and that there often is a hierarchical relationship between
communities detected by different methods. Our results suggest that community
detection methods could be useful in studying the general mesoscale structure
of networks, as opposed to only trying to identify dense structures.Comment: 11 pages, 10 figures. V2: typos corrected, one sentence added. V3:
revised version, Appendix added. V4: final published versio
Reconstructing social mixing patterns via weighted contact matrices from online and representative surveys
The unprecedented behavioural responses of societies have been evidently shaping the COVID-19 pandemic, yet it is a significant challenge to accurately monitor the continuously changing social mixing patterns in real-time. Contact matrices, usually stratified by age, summarise interaction motifs efficiently, but their collection relies on conventional representative survey techniques, which are expensive and slow to obtain. Here we report a data collection effort involving over 2.3% of the Hungarian population to simultaneously record contact matrices through a longitudinal online and sequence of representative phone surveys. To correct non-representative biases characterising the online data, by using census data and the representative samples we develop a reconstruction method to provide a scalable, cheap, and flexible way to dynamically obtain closer-to-representative contact matrices. Our results demonstrate that although some conventional socio-demographic characters correlate significantly with the change of contact numbers, the strongest predictors can be collected only via surveys techniques and combined with census data for the best reconstruction performance. We demonstrate the potential of combined online-offline data collections to understand the changing behavioural responses determining the future evolution of the outbreak, and to inform epidemic models with crucial data
Real-time estimation of the effective reproduction number of COVID-19 from behavioral data
Near-real time estimations of the effective reproduction number are among the
most important tools to track the progression of a pandemic and to inform
policy makers and the general public. However, these estimations rely on
reported case numbers, commonly recorded with significant biases. The epidemic
outcome is strongly influenced by the dynamics of social contacts, which are
neglected in conventional surveillance systems as their real-time observation
is challenging. Here, we propose a concept using online and offline behavioral
data, recording age-stratified contact matrices at a daily rate. Modeling the
epidemic using the reconstructed matrices we dynamically estimate the effective
reproduction number during the two first waves of the COVID-19 pandemic in
Hungary. Our results demonstrate how behavioral data can be used to build
alternative monitoring systems complementing the established public health
surveillance. They can identify and provide better signals during periods when
official estimates appear unreliable due to observational biases
Reconstructing social mixing patterns via weighted contact matrices from online and representative surveys
The unprecedented behavioural responses of societies have been evidently shaping the COVID-19 pandemic, yet it is a significant challenge to accurately monitor the continuously changing social mixing patterns in real-time. Contact matrices, usually stratified by age, summarise interaction motifs efficiently, but their collection relies on conventional representative survey techniques, which are expensive and slow to obtain. Here we report a data collection effort involving over 2.3% of the Hungarian population to simultaneously record contact matrices through a longitudinal online and sequence of representative phone surveys. To correct non-representative biases characterising the online data, by using census data and the representative samples we develop a reconstruction method to provide a scalable, cheap, and flexible way to dynamically obtain closer-to-representative contact matrices. Our results demonstrate that although some conventional socio-demographic characters correlate significantly with the change of contact numbers, the strongest predictors can be collected only via surveys techniques and combined with census data for the best reconstruction performance. We demonstrate the potential of combined online-offline data collections to understand the changing behavioural responses determining the future evolution of the outbreak, and to inform epidemic models with crucial data
Hungary in Masks/“Maszk” in Hungary
Social interactions represent one of the most important routes of transmission
of COVID-19 as they influence the potential patterns of diffusion of infection
throughout different segments of the population. Despite their utmost importance,
the scientific community is currently lacking data collection methods that
record social interactions dynamically and in detail, and in a privacy-respecting,
representative way, even on an aggregated level. Here we summarize the
motivation, methodology, and some early results of a coordinated process of
data collection in Hungary designed to track the social mixing patterns of people
in different age groups in real time during the pandemic. The Hungarian Data
Provider Questionnaire (MASZK7) was released in late March 2020 during the
initial phase of the COVID-19 outbreak in Hungary. This is an ongoing effort
to anonymously collect age contact matrices of a voluntary population online.
Moreover, it is accompanied with a nationally representative data collection
campaign via telephone survey to ensure data quality. (...
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