Congestion in a city with a central bottleneck

International audienceWe consider dynamic congestion in an urban setting where trip origins are spatially distributed. All travelers must pass through a downtown bottleneck in order to reach their destination in the CBD. Each traveler chooses departure time to maximize general concave scheduling utility. We find that, at equilibrium, travelers sort according to their distance to the destination; the queue is always unimodal regardless of the spatial distribution of trip origins. We construct a welfare maximizing tolling regime, which eliminates congestion. All travelers located beyond a critical distance from the CBD gain from tolling, even when toll revenues are not redistributed, while nearby travelers lose. We discuss our results in the context of acceptability of tolling policies

High-Resolution Diffusion Tensor MR Imaging for Evaluating Myocardial Anisotropy and Fiber Tracking at 3T: the Effect of the Number of Diffusion-Sensitizing Gradient Directions

Objective: We wanted to evaluate the effect of the number of diffusion-sensitizing gradient directions on the image quality for evaluating myocardial anisotropy and fiber tracking by using in vitro diffusion tensor MR imaging (DT-MRI). Materials and Methods: The DT-MR images, using a SENSE-based echo-planar imaging technique, were acquired from ten excised porcine hearts by using a 3T MR scanner. With a b-value of 800 S/mm(2), the diffusion tensor images were obtained for 6,15 and 32 diffusion-sensitizing gradient directions at the mid-ventricular level. The number of tracked fibers, the fractional anisotropy (FA), and the length of the tracked fibers were measured for the quantitative analysis. Two radiologists assessed the image quality of the fiber tractography for the qualitative analysis. Results: By increasing the number of diffusion-sensitizing gradient directions from 6 to 15, and then to 32, the FA and standard deviation were significantly reduced (p < 0.01), and the number of tracked fibers and the length of the tracked fibers were significantly increased (p < 0.01). The image quality of the fiber tractography was significantly increased with the increased number of diffusion-sensitizing gradient directions (p < 0.01). Conclusion: The image quality of in vitro DT-MRI is significantly improved as the number of diffusion-sensitizing gradient directions is increased.Jiang Y, 2007, AM J PHYSIOL-HEART C, V293, pH2377, DOI 10.1152/ajpheart.00337.2007Wu EX, 2007, MAGN RESON MED, V58, P687, DOI 10.1002/mrm.21350Wu EX, 2007, MAGN RESON IMAGING, V25, P1048, DOI 10.1016/j.mri.2006.12.008Wu MT, 2006, CIRCULATION, V114, P1036, DOI 10.1161/CIRCULATIONHAHA.105.545863Lee JW, 2006, INVEST RADIOL, V41, P553Okada T, 2006, RADIOLOGY, V238, P668, DOI 10.1148/radiol.2382042192CHANG YM, 2005, J KOREAN RADIOL SOC, V52, P87Tanenbaum LN, 2004, AM J NEURORADIOL, V25, P1626Nagae-Poetscher LM, 2004, AM J NEURORADIOL, V25, P1325Jones DK, 2004, MAGNET RESON MED, V51, P807, DOI 10.1002/mrm.20033Jaermann T, 2004, MAGNET RESON MED, V51, P230, DOI 10.1002/mrm.10707Naganawa S, 2004, EUR RADIOL, V14, P234, DOI 10.1007/s00330-003-2163-6Zhai GH, 2003, RADIOLOGY, V229, P673, DOI 10.1148/radiol.2293021462Cercignani M, 2003, AM J NEURORADIOL, V24, P1254Tseng WYI, 2003, J MAGN RESON IMAGING, V17, P31, DOI 10.1002/jmri.10223Jeong AK, 2001, KOREAN J RADIOL, V2, P21Holmes AA, 2000, MAGNET RESON MED, V44, P157Choi SI, 2000, RADIOLOGY, V215, P863Spotnitz HM, 2000, J THORAC CARDIOV SUR, V119, P1053Pruessmann KP, 1999, MAGNET RESON MED, V42, P952Tseng WI, 1999, MAGNET RESON MED, V42, P393Scollan DF, 1998, AM J PHYSIOL-HEART C, V275, pH2308Pierpaoli C, 1996, MAGNET RESON MED, V36, P893Taber LA, 1996, J BIOMECH, V29, P745REESE TG, 1995, MAGNET RESON MED, V34, P786EDELMAN RR, 1994, MAGNET RESON MED, V32, P423RADEMAKERS FE, 1994, CIRCULATION, V89, P1174STREETER DD, 1969, CIRC RES, V24, P339

A Novel Application of Amniotic Membrane in Patients with Bullous Keratopathy

To evaluate the efficacy of amniotic membrane in the management of painful bullous keratopathy secondary to the intractable glaucoma and in preventing exposure of drainage devices, we inserted Ahmed valve with amniotic membrane patch graft over the implant itself, and debrided corneal epithelium with amniotic membrane graft over the exposed stroma as a single operation. During the follow-up periods, we monitored vision, intraocular pressure (IOP), presence of ocular pain, and postoperative complications associated with the implants. The mean follow up period was 8.4±3.2 months. IOP was well controlled after the intervention. The preoperative mean IOP was measured as 43.9±9.0 mmHg and lowered to 16.1±1.8 mmHg at the last visit and no complications associated with the implants were noted. Even though the improvement in vision was not prominent, the ocular surface stabilized rapidly and ocular pain associated with bullous keratopathy disappeared soon after surgery. Conclusively the use of amniotic membrane in conjunction with Ahmed valve implantation is an effective way to relieve ocular pain and lessen the chances of complications associated with the implant in patients with intractable glaucoma and bullous keratopathy

Mouse Ribosomal RNA Genes Contain Multiple Differentially Regulated Variants

Previous cytogenetic studies suggest that various rDNA chromosomal loci are not equally active in different cell types. Consistent with this variability, rDNA polymorphism is well documented in human and mouse. However, attempts to identify molecularly rDNA variant types, which are regulated individually (i.e., independent of other rDNA variants) and tissue-specifically, have not been successful. We report here the molecular cloning and characterization of seven mouse rDNA variants (v-rDNA). The identification of these v-rDNAs was based on restriction fragment length polymorphisms (RFLPs), which are conserved among individuals and mouse strains. The total copy number of the identified variants is less than 100 and the copy number of each individual variant ranges from 4 to 15. Sequence analysis of the cloned v-rDNA identified variant-specific single nucleotide polymorphisms (SNPs) in the transcribed region. These SNPs were used to develop a set of variant-specific PCR assays, which permitted analysis of the v-rDNAs' expression profiles in various tissues. These profiles show that three v-rDNAs are expressed in all tissues (constitutively active), two are expressed in some tissues (selectively active), and two are not expressed (silent). These expression profiles were observed in six individuals from three mouse strains, suggesting the pattern is not randomly determined. Thus, the mouse rDNA array likely consists of genetically distinct variants, and some are regulated tissue-specifically. Our results provide the first molecular evidence for cell-type-specific regulation of a subset of rDNA

Bone Morphogenetic Protein Signaling: Implications in Urology

The bone morphogenetic proteins (BMPs), as members of the transforming growth factor-β (TGF-β) superfamily, not only control bone formation, but also regulate multiple key steps during embryonic development and differentiation. Furthermore, BMPs play critical roles in maintaining the homeostasis of the cardiovascular, pulmonary, reproductive, urogenital, and nervous systems in adult life. Like all members of the TGF-β superfamily, BMP signaling is mediated through a heteromeric complex of type I and type II transmembrane serine/threonine kinase receptors. The subsequent signal transduction cascade includes either the canonical Smad-dependent or non-canonical Smad-independent pathways. Reflecting the critical function of BMPs, BMP signaling is tightly regulated at multiple steps by various mechanisms including extracellular endogenous antagonists, neutralizing antibodies/extracellular soluble receptor domains, small molecule inhibitors, cytoplasmic inhibitory Smads, and transcriptional co-repressors. Recently, dorsomorphin, the first small molecule inhibitor of BMP signaling, was identified and suggested as a useful tool for dissecting the mechanisms of signaling pathways and for developing novel therapeutics for diverse human diseases that are related to the BMP signaling pathways. In this article, we discuss various mechanisms involved in regulating BMP signaling pathways and their implications for urology

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≥20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≤pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≤{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal