527 research outputs found
Team 3: Communication Aspects In Urban Operations
from Scythe : Proceedings and Bulletin of the International Data Farming Community, Issue 2 Workshop 14Objective: The main idea behind network centricity in military
operations is to translate information superiority into
combat effectiveness via creation and dissemination of
a valid and relevant common operational picture. In
order to achieve this goal, a number of preconditions
have to be fulfilled. First and foremost, reliable
communication lines have to be established both in
gathering information about the current situation as
well as in communicating a suitably aggregated
CROP from the headquarter to the commander in the
field. Therefore, the objective of our work is to
investigate the impact of reconnaissance and
communication quality on the outcome of a given
military operation. Due to the nature of contemporary
conflicts, we are especially interested in operations in
urban terrain, which pose special challenges to
reconnaissance as well as communication
Properties of Foreshocks and Aftershocks of the Non-Conservative SOC Olami-Feder-Christensen Model: Triggered or Critical Earthquakes?
Following Hergarten and Neugebauer [2002] who discovered aftershock and
foreshock sequences in the Olami-Feder-Christensen (OFC) discrete block-spring
earthquake model, we investigate to what degree the simple toppling mechanism
of this model is sufficient to account for the properties of earthquake
clustering in time and space. Our main finding is that synthetic catalogs
generated by the OFC model share practically all properties of real seismicity
at a qualitative level, with however significant quantitative differences. We
find that OFC catalogs can be in large part described by the concept of
triggered seismicity but the properties of foreshocks depend on the mainshock
magnitude, in qualitative agreement with the critical earthquake model and in
disagreement with simple models of triggered seismicity such as the Epidemic
Type Aftershock Sequence (ETAS) model [Ogata, 1988]. Many other features of OFC
catalogs can be reproduced with the ETAS model with a weaker clustering than
real seismicity, i.e. for a very small average number of triggered earthquakes
of first generation per mother-earthquake.Comment: revtex, 19 pages, 8 eps figure
The mechanisms of spatial and temporal earthquake clustering
The number of earthquakes as a function of magnitude decays as a power law.
This trend is usually justified using spring-block models, where slips with the
appropriate global statistics have been numerically observed. However,
prominent spatial and temporal clustering features of earthquakes are not
reproduced by this kind of modeling. We show that when a spring-block model is
complemented with a mechanism allowing for structural relaxation, realistic
earthquake patterns are obtained. The proposed model does not need to include a
phenomenological velocity weakening friction law, as traditional spring-block
models do, since this behavior is effectively induced by the relaxational
mechanism as well. In this way, the model provides also a simple microscopic
basis for the widely used phenomenological rate-and-state equations of rock
friction.Comment: 7 pages, 10 figures, comments welcom
A way to synchronize models with seismic faults for earthquake forecasting: Insights from a simple stochastic model
Numerical models are starting to be used for determining the future behaviour
of seismic faults and fault networks. Their final goal would be to forecast
future large earthquakes. In order to use them for this task, it is necessary
to synchronize each model with the current status of the actual fault or fault
network it simulates (just as, for example, meteorologists synchronize their
models with the atmosphere by incorporating current atmospheric data in them).
However, lithospheric dynamics is largely unobservable: important parameters
cannot (or can rarely) be measured in Nature. Earthquakes, though, provide
indirect but measurable clues of the stress and strain status in the
lithosphere, which should be helpful for the synchronization of the models. The
rupture area is one of the measurable parameters of earthquakes. Here we
explore how it can be used to at least synchronize fault models between
themselves and forecast synthetic earthquakes. Our purpose here is to forecast
synthetic earthquakes in a simple but stochastic (random) fault model. By
imposing the rupture area of the synthetic earthquakes of this model on other
models, the latter become partially synchronized with the first one. We use
these partially synchronized models to successfully forecast most of the
largest earthquakes generated by the first model. This forecasting strategy
outperforms others that only take into account the earthquake series. Our
results suggest that probably a good way to synchronize more detailed models
with real faults is to force them to reproduce the sequence of previous
earthquake ruptures on the faults. This hypothesis could be tested in the
future with more detailed models and actual seismic data.Comment: Revised version. Recommended for publication in Tectonophysic
On the broken gauge, conformal and discrete symmetries in particle physics
Relationships between gauge, conformal and discrete symmetries in particle
physics are analysed. We study also the effect of the electroweak mixing on the
cancellation of SU(2) anomalous actions. It is shown that the relation
theta_{W} = 2(theta_{12}+theta_{23}+theta_{13}) between the Weinberg angle and
the Cabibbo-Kobayashi-Maskawa angles should be satisfied and this effect is
completely defined by the mixing of Dirac fermions. We compare two mechanisms
of the spontaneous breaking of gauge symmetry, discuss the renormalizability of
theories, and argue for the existence of the Majorana fermions necessary to
remove the SU(2) anomalous action. The fate of the majoron and the
spontaneously broken lepton number is discussed. We also show the compatibility
of the boson and fermion mixings with Dyson-Schwinger equations.Comment: 27 pages, LaTeX style; v2: published version, two figures adde
Risk of subsequent ischemic and hemorrhagic stroke in patients hospitalized for immune-mediated diseases: a nationwide follow-up study from Sweden
Background: Certain immune-mediated diseases (IMDs) have been associated with increased risk for cardiovascular disorders. The aim of the present study was to examine whether there is an association between 32 different IMDs and first hospitalization for ischemic or hemorrhagic stroke. Methods: All individuals in Sweden hospitalized with a main diagnosis of IMD (without previous or coexisting stroke), between January 1, 1987 and December 31, 2008 (n = 216,291), were followed for first hospitalization for ischemic or hemorrhagic stroke. The reference population was the total population of Sweden. Adjusted standardized incidence ratios (SIRs) for ischemic and hemorrhagic stroke were calculated. Results: Totally 20 and 15 of the 32 IMDs studied, respectively, were associated with an increased risk of ischemic and hemorrhagic stroke during the follow-up. The overall risks of ischemic and hemorrhagic stroke during the first year after hospitalization for IMD were 2.02 (95 % CI 1.90-2.14) and 2.65 (95 % CI 2.27-3.08), respectively. The overall risk of ischemic or hemorrhagic stroke decreased over time, to 1.50 (95 % CI 1.46-1.55) and 1.83 (95 % CI 1.69-1.98), respectively, after 1-5 years, and 1.29 (95 % CI 1.23-1.35) and 1.47 (95 % CI 1.31-1.65), respectively, after 10+ years. The risk of hemorrhagic stroke was >= 2 during the first year after hospitalization for seven IMDs: ankylosing spondylitis (SIR = 8.11), immune thrombocytopenic purpura (SIR = 8.60), polymyalgia rheumatica (SIR = 2.06), psoriasis (SIR = 2.88), rheumatoid arthritis (SIR = 3.27), systemic lupus erythematosus (SIR = 8.65), and Wegener ' s granulomatosis (SIR = 5.83). The risk of ischemic stroke was >= 2 during the first year after hospitalization for twelve IMDs: Addison's disease (SIR = 2.71), Crohn's disease (SIR = 2.15), Grave's disease (SIR = 2.15), Hashimoto's thyroiditis (SIR = 2.99), immune thrombocytopenic purpura (SIR = 2.35), multiple sclerosis (SIR = 3.05), polymyositis/dermatomyositis (SIR = 3.46), rheumatic fever (SIR = 3.91), rheumatoid arthritis (SIR = 2.08), Sjgren's syndrome (SIR = 2.57), systemic lupus erythematosus (SIR = 2.21), and ulcerative colitis (SIR = 2.15). Conclusions: Hospitalization for many IMDs is associated with increased risk of ischemic or hemorrhagic stroke. The findings suggest that several IMDs are linked to cerebrovascular disease
Recommended from our members
Cardiovascular Risk Factors Associated With Venous Thromboembolism
Importance It is uncertain to what extent established cardiovascular risk factors are associated with venous thromboembolism (VTE). Objective To estimate associations between major cardiovascular risk factors and VTE, i.e., deep-vein thrombosis (DVT) and pulmonary embolism (PE). Design Analysis of individual-participant data from the Emerging Risk Factors Collaboration (ERFC; 731,728 participants; 75 cohorts; latest date of follow-up 2015), and UK Biobank (UKBB; 421,537 participants; latest date of follow-up 2016). Setting Approximately population-based prospective cohort studies. Participants Individuals without cardiovascular disease at baseline. Exposures A panel of several established cardiovascular risk factors. Main Outcomes and Measures Hazard ratios (HRs) per 1-SD higher risk factor levels (or presence/absence). Incident fatal outcomes in ERFC (n=1041 VTE, n=25,131 CHD) and incident fatal/non-fatal outcomes in UKBB (n=2321 VTE, n=3385 CHD). HRs were adjusted for age, sex, smoking status, diabetes mellitus, and body-mass index. Results Adjusted HRs for VTE were: 2.67 (2.45-2.91) in ERFC and 1.81 (1.71-1.92) in UKBB per decade older age; 1.38 (1.20-1.58) in ERFC and 1.23 (1.08-1.40) in UKBB with smoking; 1.43 (1.35-1.50) in ERFC and 1.37 (1.32-1.41) in UKBB per 1-SD higher body-mass index; and 0.75 (0.61-0.93) in ERFC and 0.82 (0.71-0.94) in UKBB with current alcohol consumption. For the preceding factors, there were similar HRs for pulmonary embolism versus deep vein thrombosis in UKBB (except adiposity was more strongly associated with PE; P<0.01), and similar HRs for unprovoked versus provoked VTE. Apart from adiposity, these risk factors were less strongly associated with VTE than coronary heart disease. We noted inconsistent associations with diabetes and blood pressure for VTEs across ERFC and UKBB, and had limited ability to study lipid and inflammation markers. Conclusions and Relevance Older age, smoking, adiposity, and lower alcohol consumption were consistently associated with higher VTE risk.A study website (http://www.phpc.cam.ac.uk/ceu/erfc/list-of-studies/) includes a list that investigators have provided of funding agencies that have supported individual cohorts in the ERFC contributing to the present consortium. This research has been conducted using the UK Biobank resource (application 26865)
The Invasion and Metastasis Promotion Role of CD97 Small Isoform in Gastric Carcinoma
CD97 is over-expressed in the majority of gastric adenocarcinomas and is associated with its dedifferentiation and aggressiveness. Our previous results demonstrated that out of three CD97 isoforms tested, only the small one was able to promote increased invasiveness in vitro. Based on these data we further aimed to investigate the role of CD97 small isoform in gastric cancer progression in vivo by employing the cells with a stable CD97 small isoform knock-down and an orthotopic gastric cancer mouse model. We could demonstrate that the knock down of CD97/EGF1,2,5, led to a significant decrease in the number of cells penetrating the gelatin coated membrane as compared with control cells. In the gastric cancer mouse model, both the hypodermic and the orthotopic yielded tumor masses of the CD97/EGF1,2,5kd group and were significantly smaller than the control. Metastatic tumor cell number in early metastatic regional lymph nodes on post-operative day 42 was distinctly decreased in the CD97/EGF1,2,5kd group as compared with the SGC-NS group, and was accompanied with the downregulation of CD44, VEGFR, CD31 and CD97. We concluded in this study that CD97 small isoform not only supported gastric cancer local growth, but also promoted metastatic spread in orthotopically implanted mouse model suggesting involvement of the CD97 small isoform in the preparation of (pre)metastatic niche
Dragon-kings: mechanisms, statistical methods and empirical evidence
This introductory article presents the special Discussion and Debate volume
"From black swans to dragon-kings, is there life beyond power laws?" published
in Eur. Phys. J. Special Topics in May 2012. We summarize and put in
perspective the contributions into three main themes: (i) mechanisms for
dragon-kings, (ii) detection of dragon-kings and statistical tests and (iii)
empirical evidence in a large variety of natural and social systems. Overall,
we are pleased to witness significant advances both in the introduction and
clarification of underlying mechanisms and in the development of novel
efficient tests that demonstrate clear evidence for the presence of
dragon-kings in many systems. However, this positive view should be balanced by
the fact that this remains a very delicate and difficult field, if only due to
the scarcity of data as well as the extraordinary important implications with
respect to hazard assessment, risk control and predictability.Comment: 20 page
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