385 research outputs found
Sampling Distributions of Random Electromagnetic Fields in Mesoscopic or Dynamical Systems
We derive the sampling probability density function (pdf) of an ideal
localized random electromagnetic field, its amplitude and intensity in an
electromagnetic environment that is quasi-statically time-varying statistically
homogeneous or static statistically inhomogeneous. The results allow for the
estimation of field statistics and confidence intervals when a single spatial
or temporal stochastic process produces randomization of the field. Results for
both coherent and incoherent detection techniques are derived, for Cartesian,
planar and full-vectorial fields. We show that the functional form of the
sampling pdf depends on whether the random variable is dimensioned (e.g., the
sampled electric field proper) or is expressed in dimensionless standardized or
normalized form (e.g., the sampled electric field divided by its sampled
standard deviation). For dimensioned quantities, the electric field, its
amplitude and intensity exhibit different types of
Bessel sampling pdfs, which differ significantly from the asymptotic
Gauss normal and ensemble pdfs when is relatively
small. By contrast, for the corresponding standardized quantities, Student ,
Fisher-Snedecor and root- sampling pdfs are obtained that exhibit
heavier tails than comparable Bessel pdfs. Statistical uncertainties
obtained from classical small-sample theory for dimensionless quantities are
shown to be overestimated compared to dimensioned quantities. Differences in
the sampling pdfs arising from de-normalization versus de-standardization are
obtained.Comment: 12 pages, 15 figures, accepted for publication in Phys. Rev. E, minor
typos correcte
SWITCH 1/DYAD is a WINGS APART-LIKE antagonist that maintains sister chromatid cohesion in meiosis
During cell division, Soronin antagonises WAPL to prevent premature loss of sister chromatid cohesion. Here the authors show that, despite a lack of sequence similarity, the Arabidopsis SWI1 protein functions as a novel Soronin-like WAPL antagonist, suggesting convergent evolution with animals
Immunolocalization of dually phosphorylated MAPKs in dividing root meristem cells of Vicia faba, Pisum sativum, Lupinus luteus and Lycopersicon esculentum
Key message In plants, phosphorylated MAPKs display
constitutive nuclear localization; however, not all
studied plant species show co-localization of activated
MAPKs to mitotic microtubules.
Abstract The mitogen-activated protein kinase (MAPK)
signaling pathway is involved not only in the cellular
response to biotic and abiotic stress but also in the regulation
of cell cycle and plant development. The role of
MAPKs in the formation of a mitotic spindle has been
widely studied and the MAPK signaling pathway was
found to be indispensable for the unperturbed course of cell
division. Here we show cellular localization of activated
MAPKs (dually phosphorylated at their TXY motifs) in
both interphase and mitotic root meristem cells of Lupinus
luteus, Pisum sativum, Vicia faba (Fabaceae) and Lycopersicon esculentum (Solanaceae). Nuclear localization
of activated MAPKs has been found in all species. Colocalization
of these kinases to mitotic microtubules was
most evident in L. esculentum, while only about 50 % of
mitotic cells in the root meristems of P. sativum and V.
faba displayed activated MAPKs localized to microtubules
during mitosis. Unexpectedly, no evident immunofluorescence
signals at spindle microtubules and phragmoplast
were noted in L. luteus. Considering immunocytochemical
analyses and studies on the impact of FR180204 (an
inhibitor of animal ERK1/2) on mitotic cells, we hypothesize
that MAPKs may not play prominent role in the
regulation of microtubule dynamics in all plant species
Approaches to suicide prevention: Ideas and models presented by Japanese and international early career psychiatrists
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146308/1/pcn12737.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146308/2/pcn12737_am.pd
The Dark Side of the Salad: Salmonella typhimurium Overcomes the Innate Immune Response of Arabidopsis thaliana and Shows an Endopathogenic Lifestyle
Salmonella enterica serovar typhimurium contaminated vegetables and fruits are considerable sources of human infections. Bacteria present in raw plant-derived nutrients cause salmonellosis, the world wide most spread food poisoning. This facultative endopathogen enters and replicates in host cells and actively suppresses host immune responses. Although Salmonella survives on plants, the underlying bacterial infection mechanisms are only poorly understood. In this report we investigated the possibility to use Arabidopsis thaliana as a genetically tractable host system to study Salmonella-plant interactions. Using green fluorescent protein (GFP) marked bacteria, we show here that Salmonella can infect various Arabidopsis tissues and proliferate in intracelullar cellular compartments. Salmonella infection of Arabidopsis cells can occur via intact shoot or root tissues resulting in wilting, chlorosis and eventually death of the infected organs. Arabidopsis reacts to Salmonella by inducing the activation of mitogen-activated protein kinase (MAPK) cascades and enhanced expression of pathogenesis related (PR) genes. The induction of defense responses fails in plants that are compromised in ethylene or jasmonic acid signaling or in the MKK3-MPK6 MAPK pathway. These findings demonstrate that Arabidopsis represents a true host system for Salmonella, offering unique possibilities to study the interaction of this human pathogen with plants at the molecular level for developing novel drug targets and addressing current safety issues in human nutrition
Beaconing Approaches in Vehicular Ad Hoc Networks: A Survey
A Vehicular Ad hoc Network (VANET) is a type of wireless ad hoc network that facilitates
ubiquitous connectivity between vehicles in the absence of fixed infrastructure. Beaconing approaches
is an important research challenge in high mobility vehicular networks with enabling safety applications.
In this article, we perform a survey and a comparative study of state-of-the-art adaptive beaconing
approaches in VANET, that explores the main advantages and drawbacks behind their design. The
survey part of the paper presents a review of existing adaptive beaconing approaches such as adaptive
beacon transmission power, beacon rate adaptation, contention window size adjustment and Hybrid
adaptation beaconing techniques. The comparative study of the paper compares the representatives of
adaptive beaconing approaches in terms of their objective of study, summary of their study, the utilized
simulator and the type of vehicular scenario. Finally, we discussed the open issues and research
directions related to VANET adaptive beaconing approaches.Ghafoor, KZ.; Lloret, J.; Abu Bakar, K.; Sadiq, AS.; Ben Mussa, SA. (2013). Beaconing Approaches in Vehicular Ad Hoc Networks: A Survey. Wireless Personal Communications. 73(3):885-912. doi:10.1007/s11277-013-1222-9S885912733ITS-Standards (1996) Intelligent transportation systems, U.S. Department of Transportation, http://www.standards.its.dot.gov/about.aspCheng, L., Henty, B., Stancil, D., Bai, F., & Mudalige, P. (2005). Mobile vehicle-to-vehicle narrow-band channel measurement and characterization of the 5.9 Ghz dedicated short range communication (DSRC) frequency band. IEEE Transactions on Selected Areas in Communications, 25(8), 1501–1516.van Eenennaam, E., Wolterink, K., Karagiannis, G., & Heijenk, G. (2009). Exploring the solution space of beaconing in vanets. In Proceedings of the 2009 IEEE international vehicular networking conference, Tokyo (pp. 1–8).Torrent-Moreno, M. (2007). Inter-vehicle communications: Assessing information dissemination under safety constraints. In Proceedings of the 2007 IEEE conference wireless on demand network systems and services, Austria (pp. 59–64).Lloret, J., Canovas, A., Catalá, A., & Garcia, M. (2012). Group-based protocol and mobility model for vanets to offer internet access. Journal of Network and Computer Applications 2224–2245 doi: 10.1016j.jnca.2012.02.009 .Nzouonta, J., Rajgure, N., Wang, G., & Borcea, C. (2009). Vanet routing on city roads using real-time vehicular traffic information. IEEE Transactions on Vehicular Technology, 58(7), 3609–3626.Fukui, R., Koike, H., & Okada, H. (2002). Dynamic integrated transmission control(ditrac) over inter-vehicle communications. In Proceedings of the 2002 IEEE vehicular technology conference, Birmingham (pp. 483–487).Schmidt, R., Leinmuller, T., Schoch, E., Kargl, F., & Schafer, G. (2010). Exploration of adaptive beaconing for efficient intervehicle safety communication. IEEE Network, 24(1), 14–19.Ghafoor, K., Bakar, K., van Eenennaam, E., Khokhar, R., Gonzalez, A. A fuzzy logic approach to beaconing for vehicular ad hoc networks, Accepted for publication in Telecommunication Systems Journal.Ghafoor, K., & Bakar, K. (2010). A novel delay and reliability aware inter vehicle routing protocol. Network Protocols and Algorithms, 2(2), 66–88.Mittag, J., Thomas, F., Härri, J., & Hartenstein, H. (2009). A comparison of single-and multi-hop beaconing in vanets. In Proceedings of the 2009 ACM international workshop on vehicular internetworking, Beijing (pp. 69–78).Sommer, C., Tonguz, O., & Dressler, F. (2010). Adaptive beaconing for delay-sensitive and congestion-aware traffic information systems. In Proceedings of the 2010 IEEE international vehicular networking conference (VNC), New Jersey (pp. 1–8).Guan, X., Sengupta, R., Krishnan, H., & Bai, F. (2007). A feedback-based power control algorithm design for vanet. In Proceedings of the 2007 IEEE international conference on mobile networking for vehicular environments, USA (pp. 67–72).AL-Hashimi, H., Bakar, K., & Ghafoor, K. (2011). Inter-domain proxy mobile ipv6 based vehicular network. Network Protocols and Algorithms, 2(4), 1–15.Rawat, D., Popescu, D., Yan, G., & Olariu, S. (2011). Enhancing vanet performance by joint adaptation of transmission power and contention window size. Transactions on Parallel and Distributed Systems, 22(9), 1528–1535.European-ITS (2009) Eits-technical report 102 638 v1.1.1, European Telecommunications Standards Institute (ETSI), http://www.etsi.org/WebSite/homepage.aspxNHTSA, I. Joint program office”, report to congress on the national highway traffic safety administration its program, program progress during 1992–1996 and strategic plan for 1997–2002, US Department of Transportation, Washington, DC.Godbole, D., Sengupta, R., Misener, J., Kourjanskaia, N., & Michael, J. (1998). Benefit evaluation of crash avoidance systems. Transportation Research, 1621(1), 1–9.Reinders, R., van Eenennaam, M., Karagiannis, G., & Heijenk, G. (2004). Contention window analysis for beaconing in vanets. In Proceedings of the 2011 IEEE international conference on wireless communications and mobile computing (IWCMC), Istanbul (pp. 1481–1487).Yang, L., Guo, J., & Wu, Y. (2008). Channel adaptive one hop broadcasting for vanets. In Proceedings of the 2008 IEEE international conference on intelligent transportation systems, Beijing (pp. 369–374).Tseng, Y., Ni, S., Chen, Y., & Sheu, J. (2002). The broadcast storm problem in a mobile ad hoc network. Wireless Networks, 8(2), 153–167.van Eenennaam, E. M., Karagiannis, G., & Heijenk, G. (2010). Towards scalable beaconing in vanets. In Proceedings of the 2010 ERCIM workshop on eMobility, Lulea (pp. 103–108).Ros, F., Ruiz, P., & Stojmenovic, I. (2012). Acknowledgment-based broadcast protocol for reliable and efficient data dissemination in vehicular ad-hoc networks. IEEE Transactions on Mobile Computing, 11(1), 33–46.Torrent-Moreno, M., Santi, P., & Hartenstein, H. (2006). Distributed fair transmit power adjustment for vehicular ad hoc networks. In Proceedings of the 2007 IEEE international conference on sensor and ad hoc communications and networks, Reston, VA (pp. 479–488).Artimy, M. (2007). Local density estimation and dynamic transmission-range assignment in vehicular ad hoc networks. IEEE Transactions on Intelligent Transportation Systems, 8(3), 400–412.Caizzone, G., Giacomazzi, P., Musumeci, L., & Verticale, G. (2005). A power control algorithm with high channel availability for vehicular ad hoc networks. In Proceedings of the 2005 IEEE international conference on communications, Seoul (pp. 3171–3176).Torrent-Moreno, M., Santi, P., & Hartenstein, H. (2009). 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In Proceedings of the 2002 European wireless conference next generation wireless networks: technologies, protocols, Italy (pp. 1–6).Cheng, P., Lee, K., Gerla, M., & Harri, J. (2010). Geodtn+ nav: Geographic dtn routing with navigator prediction for urban vehicular environments. Mobile Networks and Applications, 15(1), 61–82.Gomez, J., & Campbell, A. (2004). A case for variable-range transmission power control in wireless multihop networks. In Proceedings twenty-third annual joint conference of the IEEE computer and communications societies, Hong kong (pp. 1425–1436).Ramanathan, R., & Rosales-Hain, R. (2000). Topology control of multihop wireless networks using transmit power adjustment. In Proceedings nineteenth annual joint conference of the IEEE computer and communications societies, Hong kong (pp. 404–413).Artimy, M., Robertson, W., & Phillips, W. (2005). Assignment of dynamic transmission range based on estimation of vehicle density. In Proceedings of the 2nd ACM international workshop on vehicular ad hoc networks, Germany (pp. 40–48).Samara, G., Ramadas, S., & Al-Salihy, W. (2010). Safety message power transmission control for vehicular ad hoc networks. Computer Science, 6(10), 1027–1032.Rezaei, S., Sengupta, R., Krishnan, H., Guan, X., & Student, P. (2008). Adaptive communication scheme for cooperative active safety system.Rezaei, S., Sengupta, R., Krishnan, H., & Guan, X. (2007). Reducing the communication required by dsrc-based vehicle safety systems. In Proceedings of the 2007 IEEE international conference on intelligent transportation systems, Bellevue, WA (pp. 361–366).Sommer, C., Tonguz, O., & Dressler, F. (2011). Traffic information systems: Efficient message dissemination via adaptive beaconing. IEEE Communications Magazine, 49(5), 173–179.Thaina, C., Nakorn, K., & Rojviboonchai, K. (2011). A study of adaptive beacon transmission on vehicular ad-hoc networks. 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In Proceeding of the 2012 IEEE conference wireless communications and networking, Paris, France (pp. 2264–2269).O. Technologies (Augast 2012) Opnet modeler, http://www.opnet.com/Huang, C., Fallah, Y., Sengupta, R., & Krishnan, H. (2010). Adaptive intervehicle communication control for cooperative safety systems. IEEE Network, 24(1), 6–13.OPNET (June 2012) Opnet modeler, http://www.opnet.com/Kerner, B. (2004). The physics of traffic: Empirical freeway pattern features, engineering applications, and theory. Berlin: Springer.Vinel, A., Vishnevsky, V., & Koucheryavy, Y. (2008). A simple analytical model for the periodic broadcasting in vehicular ad-hoc networks. In Proceedings of the 2008 IEEE international GLOBECOM workshops, Philadelphia, PA (pp. 1–5).Mariyasagayam, N., Menouar, H., & Lenardi, M. (2009). An adaptive forwarding mechanism for data dissemination in vehicular networks. In Proceedings of the 2009 IEEE Vehicular Networking Conference, Boston (pp. 1–5).Hung, C., Chan, H., & Wu, E. (2008). Mobility pattern aware routing for heterogeneous vehicular networks. In Proceedings of the 2008 international conference on wireless communications and networking, Las Vegas (pp. 2200–2205).Yang, K., Ou, S., Chen, H., & He, J. (2007). A multihop peer-communication protocol with fairness guarantee for ieee 802.16-based vehicular networks. IEEE Transactions on Vehicular Technology, 56(6), 3358–3370.Lequerica, I., Ruiz, P., & Cabrera, V. (2010). Improvement of vehicular communications by using 3G capabilities to disseminate control information. IEEE Network Magazine, 24(1), 32–38.Oh, D., Kim, P., Song, J., Jeon, S., & Lee, H. (2005). Design considerations of satellite-based vehicular broadband networks. IEEE Wireless Communications Magazine, 12(5), 91–97.Ko, Y., Sim, M., & Nekovee, M. (2006). Wi-fi based broadband wireless access for users on the road. BT Technology Journal, 24(2), 123–129.Choffnes, D., & Bustamante, F. (2005). An integrated mobility and traffic model for vehicular wireless networks. In Proceedings of the 2005 ACM international workshop on vehicular ad hoc networks, Cologne (pp. 69–78).TIGER (October 2010) Topologically integrated geographic encoding and referencing system, http://www.census.gov/geo/www/tiger/Mittag, J., Thomas, F., Harri, J., & Hartenstein, H. (2009). A comparison of single and multi-hop beaconing in vanets. In Proceedings of the 2009 ACM international workshop on vehiculaar internetworking, Beijing (pp. 69–78).Rappaport, T. (1996). Wireless communications: Principles and practice (2nd ed.). New Jersey: Prentice Hall PTR
Coronary artery disease, left ventricular hypertrophy and diastolic dysfunction are associated with stroke in patients affected by persistent non-valvular atrial fibrillation: a case-control study
Persistent non-valvular atrial fibrillation (NVAF) is associated with an increased risk of cardiovascular events such as stroke, and its rate is expected to rise because of the ageing population. The absolute rate of stroke depends on age and comorbidity. Risk stratification for stroke in patients with NVAF derives from populations enrolled in randomized clinical trials. However, participants in clinical trials are often not representative of the general population. Many stroke risk stratification scores have been used, but they do not include transthoracic echocardiogram (TTE), pulsate wave Doppler (PWD) and tissue Doppler imaging (TDI), simple and non- invasive diagnostic tools. The role of TTE, PWD and TDI findings has not been previously determined. Our study goal was to determine the association between TTE and PWD findings and stroke prevalence in a population of NVAF prone outpatients
The Asymmetry Coefficient for Interstellar Scintillation of Extragalactic Radio Sources
Comparing the asymmetry coefficients and scintillation indices for observed
time variations of the intensity of the radiation of extragalactic sources and
the predictions of theoretical models is a good test of the nature of the
observed variations. Such comparisons can be used to determine whether
flux-density variations are due to scintillation in the interstellar medium or
are intrinsic to the source. In the former case, they can be used to estimate
the fraction of the total flux contributed by the compact component (core)
whose flux-density variations are brought about by inhomogeneities in the
interstellar plasma. Results for the radio sources PKS 0405-385, B0917+624, PKS
1257-336, and J1819+3845 demonstrate that the scintillating component in these
objects makes up from 50% to 100% of the total flux, and that the intrinsic
angular sizes of the sources at 5 GHz is 10-40 microarcseconds. The
characteristics of the medium giving rise to the scintillations are presented
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