Classification of scale-free networks

While the emergence of a power law degree distribution in complex networks is intriguing, the degree exponent is not universal. Here we show that the betweenness centrality displays a power-law distribution with an exponent \eta which is robust and use it to classify the scale-free networks. We have observed two universality classes with \eta \approx 2.2(1) and 2.0, respectively. Real world networks for the former are the protein interaction networks, the metabolic networks for eukaryotes and bacteria, and the co-authorship network, and those for the latter one are the Internet, the world-wide web, and the metabolic networks for archaea. Distinct features of the mass-distance relation, generic topology of geodesics and resilience under attack of the two classes are identified. Various model networks also belong to either of the two classes while their degree exponents are tunable.Comment: 6 Pages, 6 Figures, 1 tabl

The size and structure of the spheroid of IC 1613

Nearby galaxies, spirals as well as irregulars, have been found to be much larger than previously believed. The structure of the huge spheroid surrounding dwarf galaxies could give clues to their past gravitational history. Thanks to wide field imagers, nearby galaxies with diameter of dozens of arcmin can be effectively surveyed. We obtain, from the CFHT archives, a series of i' and g' MegaCam images of IC 1613 in order to determine the stellar surface density of the field and determine the shape of its spheroid. From the colour magnitude diagram we select some 36,000 stars, in the first three magnitudes of the red giant branch. The spatial distribution of these stars is used to establish the structure of the spheroid. The position angle of the major axis of the stellar spheroid is found to be $\approx 90^\circ$, some 30$^\circ$ from the major axis of the HI cloud surrounding IC 1613. The surface density profile of the spheroid is not exponential over all the length of the major axis. A King profile, with a core radius of 4.5' and a tidal radius of 24' fits the data. The tidal truncation of the spheroid suggests that IC 1613 is indeed a satellite of M31.Comment: accepted : A

Role of a BRICS Bank in a multipolar world : is China establishing a new international organization to change the international order or to legitimize Chinese FDI?

published_or_final_versionInternational and Public AffairsMasterMaster of International and Public Affair

Effects of Qigong on Depression: A Systemic Review

Physical exercises and relaxation have been found to be beneficial for depression. However, there is little evidence on the use of Qigong, a mind-body practice integrating gentle exercise and relaxation, in the management of depression. The aim of this paper is to evaluate the effects of Qigong on depression. The paper examined clinical trials measuring the effect of Qigong on depression within six large-scale medical research databases (PubMed, Medline, ProQuest, Science Direct, EMBASE, and PsycInfo) till October 2011. Key words “Qigong,” “depression,” and “mood” were used. Ten studies were identified as original randomized controlled trial (RCT) studies investigating the effect of Qigong on depression as primary (n = 2) or secondary outcome (n = 8). Four studies reported positive results of the Qigong treatment on depression; two reported that Qigong effect on depression was as effective as physical exercise. One study reported that Qigong was comparable to a conventional rehabilitation program, but the remaining three studies found no benefits of Qigong on depression. While the evidence suggests the potential effects of Qigong in the treatment of depression, the review of the literature shows inconclusive results. Further research using rigorous study designs is necessary to investigate the effectiveness of Qigong in depression

A Case of Pediatric Melanoma: Treatment Considerations in Advanced Disease.

We document a 3-year-old healthy African American girl who developed malignant melanoma on her lower extremity. The clinical appearance offered little indication of the lesion’s severity (T4), and only the history of de novo presentation and disproportionate growth raised clinical suspicion. This case report highlights the subtle clinical findings of this condition and presents controversies related to surgical management of pediatric melanoma

Synchronization and modularity in complex networks

We investigate the connection between the dynamics of synchronization and the modularity on complex networks. Simulating the Kuramoto's model in complex networks we determine patterns of meta-stability and calculate the modularity of the partition these patterns provide. The results indicate that the more stable the patterns are, the larger tends to be the modularity of the partition defined by them. This correlation works pretty well in homogeneous networks (all nodes have similar connectivity) but fails when networks contain hubs, mainly because the modularity is never improved where isolated nodes appear, whereas in the synchronization process the characteristic of hubs is to have a large stability when forming its own community.Comment: To appear in the Proceedings of Workshop on Complex Systems: New Trends and Expectations, Santander, Spain, 5-9 June 200

Machine learning for modeling the progression of Alzheimer disease dementia using clinical data: A systematic literature review

OBJECTIVE: Alzheimer disease (AD) is the most common cause of dementia, a syndrome characterized by cognitive impairment severe enough to interfere with activities of daily life. We aimed to conduct a systematic literature review (SLR) of studies that applied machine learning (ML) methods to clinical data derived from electronic health records in order to model risk for progression of AD dementia. MATERIALS AND METHODS: We searched for articles published between January 1, 2010, and May 31, 2020, in PubMed, Scopus, ScienceDirect, IEEE Explore Digital Library, Association for Computing Machinery Digital Library, and arXiv. We used predefined criteria to select relevant articles and summarized them according to key components of ML analysis such as data characteristics, computational algorithms, and research focus. RESULTS: There has been a considerable rise over the past 5 years in the number of research papers using ML-based analysis for AD dementia modeling. We reviewed 64 relevant articles in our SLR. The results suggest that majority of existing research has focused on predicting progression of AD dementia using publicly available datasets containing both neuroimaging and clinical data (neurobehavioral status exam scores, patient demographics, neuroimaging data, and laboratory test values). DISCUSSION: Identifying individuals at risk for progression of AD dementia could potentially help to personalize disease management to plan future care. Clinical data consisting of both structured data tables and clinical notes can be effectively used in ML-based approaches to model risk for AD dementia progression. Data sharing and reproducibility of results can enhance the impact, adaptation, and generalizability of this research

Synchronization processes in complex networks

We present an extended analysis, based on the dynamics towards synchronization of a system of coupled oscillators, of the hierarchy of communities in complex networks. In the synchronization process, different structures corresponding to well defined communities of nodes appear in a hierarchical way. The analysis also provides a useful connection between synchronization dynamics, complex networks topology and spectral graph analysis.Comment: 16 pages, 4 figures. To appear in Physica D "Special Issue on dynamics on complex networks

Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions with Asymmetric Electrodes

We present a detailed study of the spin-torque diode effect in CoFeB/MgO/CoFe/NiFe magnetic tunnel junctions. From the evolution of the resonance frequency with magnetic field at different angles, we clearly identify the free-layer mode and find an excellent agreement with simulations by taking into account several terms for magnetic anisotropy. Moreover, we demonstrate the large contribution of the out-of-plane torque in our junctions with asymmetric electrodes compared to the in-plane torque. Consequently, we provide a way to enhance the sensitivity of these devices for the detection of microwave frequency