1,354 research outputs found

    Electromagnetically induced transparency in cold 85Rb atoms trapped in the ground hyperfine F = 2 state

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    We report electromagnetically induced transparency (EIT) in cold 85Rb atoms, trapped in the lower hyperfine level F = 2, of the ground state 52S1/2^{2}S_{1/2} (Tiwari V B \textit{et al} 2008 {\it Phys. Rev.} A {\bf 78} 063421). Two steady state Λ\Lambda-type systems of hyperfine energy levels are investigated using probe transitions into the levels F^{\prime} = 2 and F^{\prime} = 3 of the excited state 52P3/2^{2}P_{3/2} in the presence of coupling transitions F = 3 \to F^{\prime} = 2 and F = 3 \to F^{\prime} = 3, respectively. The effects of uncoupled magnetic sublevel transitions and coupling field's Rabi frequency on the EIT signal from these systems are studied using a simple theoretical model.Comment: 12 pages, 7 figure

    Multiple scattering approach to low-energy electron collisions with the water dimer

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    Multiple scattering theory is applied to low-energy electron collisions with a complex target formed of two molecular scatterers. The total T-matrix is expressed in terms of the T-matrix for each isolated molecule. We apply the approach to elastic electron-(H2O)2 collisions. Following the method developed in our previous work on crystalline ice, we impose a cut-off on the dipole outside the R-matrix sphere and an energy dependent cut-off on the angular momentum components of the monomer T-matrix. An R-matrix calculation of electron-dimer collisions is performed in order to evaluate the accuracy of the multiple scattering approach. The agreement between the two calculations is very good.Comment: 15 pages, 4 figures New submission: Added references Included PACS numbers Figure 3 slightly changed Additions made to the Conclusions and Discussion sectio

    Advances on Network Protocols and Algorithms for Vehicular Ad Hoc Networks

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    Vehicular Ad Hoc Network (VANET) is an emerging area of wireless ad hoc networks that facilitates ubiquitous connectivity between smart vehicles through Vehicle-to-Vehicle (V2V) or Vehicle-to-Roadside (V2R) and Roadside-to- Vehicle (R2V) communications. This emerging field of technology aims to improve safety of passengers and traffic flow, reduces pollution to the environment and enables in-vehicle entertainment applications. The safety-related applications could reduce accidents by providing drivers with traffic information such as collision avoidances, traffic flow alarms and road surface conditions. Moreover, the passengers could exploit an available infrastructure in order to connect to the internet for infomobility and entertainment applications.Lloret, J.; Ghafoor, KZ.; Rawat, DB.; Xia, F. (2013). Advances on Network Protocols and Algorithms for Vehicular Ad Hoc Networks. Mobile Networks and Applications. 18(6):749-754. doi:10.1007/s11036-013-0490-7S749754186Lloret J, Canovas A, Catalá A, Garcia M (2013) Group-based protocol and mobility model for VANETs to offer internet access. J Netw Comput Appl 36(3):1027–1038. doi: 10.1016/j.jnca.2012.02.009Khokhar RH, Zia T, Ghafoor KZ, Lloret J, Shiraz M (2013) Realistic and efficient radio propagation model for V2X communications. KSII Trans Internet Inform Syst 7(8):1933–1953. doi: 10.3837/tiis.2013.08.011Ghafoor KZ (2013) Routing protocols in vehicular ad hoc networks: survey and research challenges, Netw Protocol Algorithm 5(4). doi: 10.5296/npa.v5i4.4134Ghafoor KZ, Bakar KA, Lloret J, Ke C-H, Lee KC (2013) Intelligent beaconless geographical routing for urban vehicular environments. Wirel Netw 19(3):345–362. doi: 10.1007/s11276-012-0470-zGhafoor KZ, Bakar KA, Lee K, AL-Hashimi H (2010) A novel delay- and reliability- aware inter-vehicle routing protocol. Netw Protocol Algorithms 2(2):66–88. doi: 10.5296/npa.v2i2.427Dias JAFF, Rodrigues JJPC, Isento JN, Pereira PRBA, Lloret J (2011) Performance assessment of fragmentation mechanisms for vehicular delay-tolerant networks. EURASIP J Wirel Commun Netw 2011(195):1–14. doi: 10.1186/1687-1499-2011-195Zhang D, Yang Z, Raychoudhury V, Chen Z, Lloret J (2013) An energy-efficient routing protocol using movement trend in vehicular Ad-hoc networks. Comput J 58(8):938–946. doi: 10.1093/comjnl/bxt028Ghafoor KZ, Lloret J, Bakar KA, Sadiq AS, Mussa SAB (2013) Beaconing approaches in vehicular Ad Hoc networks: a survey. Wirel Pers Commun. doi: 10.1007/s11277-013-1222-9Sadiq AS, Bakar KA, Ghafoor KZ, Lloret J (2013) An intelligent vertical handover scheme for audio and video streaming in heterogeneous vehicular networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0465-8Khamayseh YM (2013) Network size estimation in VANETs. Netw Protocol Algorithm 5(3):136–152. doi: 10.5296/npa.v5i6.3838Rawat DB, Popescu DC, Yan G, Olariu S (2011) Enhancing VANET performance by joint adaptation of transmission power and contention window size. IEEE Trans Parallel Distrib Syst 22(9):1528–1535Yan G, Rawat DB, Bista BB. Provisioning vehicular ad hoc networks with quality of services. Int J Space-Based Situated Comput 2(2):104–111Rawat DB, Bista BB, Yan G, Weigle MC (2011) Securing vehicular ad-hoc networks against malicious drivers: a probabilistic approach, International Conference on Complex, Intelligent, and Software Intensive Systems Pp. 146–151. June 30, 2011Sun W, Xia F, Ma J, Fu T, Sun Y. An optimal ODAM-based broadcast algorithm for vehicular Ad-Hoc Networks. KSII Trans Internet Inform Syst 6(12): 3257–3274Vinel AV, Dudin AN, Andreev SD, Xia F (2010) Performance modeling methodology of emergency dissemination algorithms for vehicular ad-hoc networks, 6th Communication Systems, Networks & Digital Signal Processing (CSNDSP 2010), Pp. 397–400AL-Hashimi HN, Bakar KA, Ghafoor KZ (2010) Inter-domain proxy mobile IPv6 based vehicular network. Netw Protocol Algorithm 2(4):1–15. doi: 10.5296/npa.v2i4.488Ghafoor KZ, Bakar KA, Mohammed MA, Lloret J (2013) Vehicular cloud computing: trends and challenges, in the book “mobile computing over cloud: technologies, services, and applications”. IGI GlobalYan G, Rawat DB, Bista BB (2012) Towards secure vehicular clouds, Sixth International Conference on Complex, Intelligent and Software Intensive Systems (CISIS 2012), Pp. 370–375Fernández H, Rubio L, Reig J, Rodrigo-Peñarrocha VM, Valero A (2013) Path loss modeling for vehicular system performance and communication protocols evaluation. Mobile Netw Appl. doi: 10.1007/s11036-013-0463-xAllouche Y, Segal M (2013) A cluster-based beaconing approach in VANETs: near optimal topology via proximity information. Mobile Netw Appl. doi: 10.1007/s11036-013-0468-5Merah AF, Samarah S, Boukerche A, Mammeri A (2013) A sequential patterns data mining approach towards vehicular route prediction in VANETs. Mobile Netw Appl. doi: 10.1007/s11036-013-0459-6Zhang D, Huang H, Zhou J, Xia F, Chen Z (2013) Detecting hot road mobility of vehicular Ad Hoc Networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0467-6El Ajaltouni H, Boukerche A, Mammeri A (2013) A multichannel QoS MAC with dynamic transmit opportunity for. Mobile Netw Appl. doi: 10.1007/s11036-013-0475-6Reñé S, Esparza O, Alins J, Mata-Díaz J, Muñoz JL (2013) VSPLIT: a cross-layer architecture for V2I TCP services over. Mobile Netw Appl. doi: 10.1007/s11036-013-0473-8Blanco B, Liberal F (2013) Amaia Aguirregoitia, application of cognitive techniques to adaptive routing for VANETs in city environments. Mobile Netw Appl. doi: 10.1007/s11036-013-0466-7Kim J, Krunz M (2013) Spectrum-aware beaconless geographical routing protocol for cognitive radio enabled vehicular networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0476-5Dias JAFF, Rodrigues JJPC, Isento JNG, Niu J (2013) The impact of cooperative nodes on the performance of vehicular delay-tolerant networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0464-9Sadiq AS, Bakar KA, Ghafoor KZ, Lloret J, Khokhar R (2013) An intelligent vertical handover scheme for audio and video streaming in heterogeneous vehicular networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0465-8Machado S, Ozón J, González AJ, Ghafoor KZ (2013) Structured peer-to-peer real time video transmission over vehicular Ad Hoc networks. Mobile Netw Appl. doi: 10.1007/s11036-013-0461-zLin C, Wu G, Xia F, Yao L (2013) Enhance the attacking efficiency of the node compromise attack in vehicular Ad-hoc network using connected dominating set. Mobile Netw Appl. doi: 10.1007/s11036-013-0469-

    Quaternion Gravi-Electromagnetism

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    Defining the generalized charge, potential, current and generalized fields as complex quantities where real and imaginary parts represent gravitation and electromagnetism respectively, corresponding field equation, equation of motion and other quantum equations are derived in manifestly covariant manner. It has been shown that the field equations are invariant under Lorentz as well as duality transformations. It has been shown that the quaternionic formulation presented here remains invariant under quaternion transformations.Comment: Key Words: Quaternion, dyons, gravito-dyons, gravi-electromagnetism. PACS No.: 04.90. +e ; 14.80. H

    CAPRG: Sequence Assembling Pipeline for Next Generation Sequencing of Non-Model Organisms

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    Our goal is to introduce and describe the utility of a new pipeline “Contigs Assembly Pipeline using Reference Genome” (CAPRG), which has been developed to assemble “long sequence reads” for non-model organisms by leveraging a reference genome of a closely related phylogenetic relative. To facilitate this effort, we utilized two avian transcriptomic datasets generated using ROCHE/454 technology as test cases for CAPRG assembly. We compared the results of CAPRG assembly using a reference genome with the results of existing methods that utilize de novo strategies such as VELVET, PAVE, and MIRA by employing parameter space comparisons (intra-assembling comparison). CAPRG performed as well or better than the existing assembly methods based on various benchmarks for “gene-hunting.” Further, CAPRG completed the assemblies in a fraction of the time required by the existing assembly algorithms. Additional advantages of CAPRG included reduced contig inflation resulting in lower computational resources for annotation, and functional identification for contigs that may be categorized as “unknowns” by de novo methods. In addition to providing evaluation of CAPRG performance, we observed that the different assembly (inter-assembly) results could be integrated to enhance the putative gene coverage for any transcriptomics study

    IMAGES II. A surprisingly low fraction of undisturbed rotating spiral disks at z~0.6: The morpho-kinematical relation 6 Gyrs ago

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    We present a first combined analysis of the morphological and dynamical properties for the Intermediate MAss Galaxy Evolution Sequence (IMAGES) sample. It is a representative sample of 52 z~0.6 galaxies with Mstell from 1.5 to 15 10^10Msun and possessing 3D resolved kinematics and HST deep imaging in at least two broad band filters. We aim at evaluate robustly the evolution of rotating spirals since z~0.6, as well as to test the different schemes for classifying galaxies morphologically. We used all the information provided by multi-band images, color maps and 2 dimensional light fitting to assign to each object a morphological class. We divided our sample between spiral disks, peculiar objects, compact objects and mergers. Using our morphological classification scheme, 4/5 of identified spirals are rotating disks and more than 4/5 of identified peculiar galaxies show complex kinematics, while automatic classification methods such as Concentration-Asymmetry and GINI-M20 severely overestimate the fraction of relaxed disk galaxies. Using this methodology, we find that the fraction of rotating spirals has increased by a factor ~ 2 during the last 6 Gyrs, a much higher fraction that found previously based on morphologies alone. These rotating spiral disks are forming stars very rapidly, doubling their stellar masses over the last 6 Gyrs, while most of their stars have been formed few Gyrs earlier, which reveals the presence of a large gas supply. Because they are likely the progenitors of local spirals, we can conjecture how their properties are evolving. Their disks show some evidence for an inside-out growth and the gas supply/accretion is not made randomly as the disk need to be stable in order to match the local disk properties.Comment: Typos corrected, reference adde

    IMAGES I. Strong evolution of galaxy kinematics since z=1

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    (abbreviated) We present the first results of the ESO large program, ``IMAGES'' which aims at obtaining robust measurements of the kinematics of distant galaxies using the multi-IFU mode of GIRAFFE on the VLT. 3D spectroscopy is essential to robustly measure the often distorted kinematics of distant galaxies (e.g., Flores et al. 2006). We derive the velocity fields and σ\sigma-maps of 36 galaxies at 0.4<z<0.75 from the kinematics of the [OII] emission line doublet, and generate a robust technique to identify the nature of the velocity fields based on the pixels of the highest signal-to-noise ratios (S/N). We have gathered a unique sample of 63 velocity fields of emission line galaxies (W0([OII]) > 15 A) at z=0.4-0.75, which are a representative subsample of the population of M_stellar>1.5x10^{10} M_sun emission line galaxies in this redshift range, and are largely unaffected by cosmic variance. Taking into account all galaxies -with or without emission lines- in that redshift range, we find that at least 41+/-7% of them have anomalous kinematics, i.e., they are not dynamically relaxed. This includes 26+/-7% of distant galaxies with complex kinematics, i.e., they are not simply pressure or rotationally supported. Our result implies that galaxy kinematics are among the most rapidly evolving properties, because locally, only a few percent of the galaxies in this mass range have complex kinematics.Comment: 17 pages, 6 figures, Accepted by A&

    Monitoring global protein thiol-oxidation and protein S-mycothiolation in Mycobacterium smegmatis under hypochlorite stress.

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    Hillion M, Bernhardt J, Busche T, et al. Monitoring global protein thiol-oxidation and protein S-mycothiolation in Mycobacterium smegmatis under hypochlorite stress. Sci Rep. 2017;7(1): 1195.Mycothiol (MSH) is the major low molecular weight (LMW) thiol in Actinomycetes. Here, we used shotgun proteomics, OxICAT and RNA-seq transcriptomics to analyse protein S-mycothiolation, reversible thiol-oxidations and their impact on gene expression in Mycobacterium smegmatis under hypochlorite stress. In total, 58 S-mycothiolated proteins were identified under NaOCl stress that are involved in energy metabolism, fatty acid and mycolic acid biosynthesis, protein translation, redox regulation and detoxification. Protein S-mycothiolation was accompanied by MSH depletion in the thiol-metabolome. Quantification of the redox state of 1098 Cys residues using OxICAT revealed that 381 Cys residues (33.6%) showed >10% increased oxidations under NaOCl stress, which overlapped with 40 S-mycothiolated Cys-peptides. The absence of MSH resulted in a higher basal oxidation level of 338 Cys residues (41.1%). The RseA and RshA anti-sigma factors and the Zur and NrdR repressors were identified as NaOCl-sensitive proteins and their oxidation resulted in an up-regulation of the SigH, SigE, Zur and NrdR regulons in the RNA-seq transcriptome. In conclusion, we show here that NaOCl stress causes widespread thiol-oxidation including protein S-mycothiolation resulting in induction of antioxidant defense mechanisms in M. smegmatis. Our results further reveal that MSH is important to maintain the reduced state of protein thiols

    Supersymmetrization of Quaternion Dirac Equation for Generalized Fields of Dyons

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    The quaternion Dirac equation in presence of generalized electromagnetic field has been discussed in terms of two gauge potentials of dyons. Accordingly, the supersymmetry has been established consistently and thereafter the one, two and component Dirac Spinors of generalized quaternion Dirac equation of dyons for various energy and spin values are obtained for different cases in order to understand the duality invariance between the electric and magnetic constituents of dyons.Comment: Key words: Supersymmetry, quaternion, Dirac equation, dyons PACS No.: 11.30.Pb, 14.80.Ly, 03.65.G
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