Single-vehicle data of highway traffic - a statistical analysis

In the present paper single-vehicle data of highway traffic are analyzed in great detail. By using the single-vehicle data directly empirical time-headway distributions and speed-distance relations can be established. Both quantities yield relevant information about the microscopic states. Several fundamental diagrams are also presented, which are based on time-averaged quantities and compared with earlier empirical investigations. In the remaining part time-series analyses of the averaged as well as the single-vehicle data are carried out. The results will be used in order to propose objective criteria for an identification of the different traffic states, e.g. synchronized traffic.Comment: 12 pages, 19 figures, RevTe

Cellular Automata Simulating Experimental Properties of Traffic Flows

A model for 1D traffic flow is developed, which is discrete in space and time. Like the cellular automaton model by Nagel and Schreckenberg [J. Phys. I France 2, 2221 (1992)], it is simple, fast, and can describe stop-and-go traffic. Due to its relation to the optimal velocity model by Bando et al. [Phys. Rev. E 51, 1035 (1995)], its instability mechanism is of deterministic nature. The model can be easily calibrated to empirical data and displays the experimental features of traffic data recently reported by Kerner and Rehborn [Phys. Rev. E 53, R1297 (1996)].Comment: For related work see http://www.theo2.physik.uni-stuttgart.de/helbing.html and http://traffic.comphys.uni-duisburg.de/member/home_schreck.htm

Motions and world-line deviations in Einstein-Maxwell theory

We examine the motion of charged particles in gravitational and electro-magnetic background fields. We study in particular the deviation of world lines, describing the relative acceleration between particles on different space-time trajectories. Two special cases of background fields are considered in detail: (a) pp-waves, a combination of gravitational and electro-magnetic polarized plane waves travelling in the same direction; (b) the Reissner-Nordstr{\o}m solution. We perform a non-trivial check by computing the precession of the periastron for a charged particle in the Reissner-Nordstr{\o}m geometry both directly by solving the geodesic equation, and using the world-line deviation equation. The results agree to the order of approximation considered.Comment: 23 pages, no figure

Long-lived states in synchronized traffic flow. Empirical prompt and dynamical trap model

The present paper proposes a novel interpretation of the widely scattered states (called synchronized traffic) stimulated by Kerner's hypotheses about the existence of a multitude of metastable states in the fundamental diagram. Using single vehicle data collected at the German highway A1, temporal velocity patterns have been analyzed to show a collection of certain fragments with approximately constant velocities and sharp jumps between them. The particular velocity values in these fragments vary in a wide range. In contrast, the flow rate is more or less constant because its fluctuations are mainly due to the discreteness of traffic flow. Subsequently, we develop a model for synchronized traffic that can explain these characteristics. Following previous work (I.A.Lubashevsky, R.Mahnke, Phys. Rev. E v. 62, p. 6082, 2000) the vehicle flow is specified by car density, mean velocity, and additional order parameters $h$ and $a$ that are due to the many-particle effects of the vehicle interaction. The parameter $h$ describes the multilane correlations in the vehicle motion. Together with the car density it determines directly the mean velocity. The parameter $a$, in contrast, controls the evolution of $h$ only. The model assumes that $a$ fluctuates randomly around the value corresponding to the car configuration optimal for lane changing. When it deviates from this value the lane change is depressed for all cars forming a local cluster. Since exactly the overtaking manoeuvres of these cars cause the order parameter $a$ to vary, the evolution of the car arrangement becomes frozen for a certain time. In other words, the evolution equations form certain dynamical traps responsible for the long-time correlations in the synchronized mode.Comment: 16 pages, 10 figures, RevTeX

Quantum corrections and black hole spectroscopy

In the work \cite{BRM,RBE}, black hole spectroscopy has been successfully reproduced in the tunneling picture. As a result, the derived entropy spectrum of black hole in different gravity (including Einstein's gravity, Einstein-Gauss-Bonnet gravity and Ho\v{r}ava-Lifshitz gravity) are all evenly spaced, sharing the same forms as $S_n=n$, where physical process is only confined in the semiclassical framework. However, the real physical picture should go beyond the semiclassical approximation. In this case, the physical quantities would undergo higher-order quantum corrections, whose effect on different gravity shares in different forms. Motivated by these facts, in this paper we aim to observe how quantum corrections affect black hole spectroscopy in different gravity. The result shows that, in the presence of higher-order quantum corrections, black hole spectroscopy in different gravity still shares the same form as $S_n=n$, further confirming the entropy quantum is universal in the sense that it is not only independent of black hole parameters, but also independent of higher-order quantum corrections. This is a desiring result for the forthcoming quantum gravity theory.Comment: 14 pages, no figure, use JHEP3.cls. to be published in JHE

Fermions tunnelling from the charged dilatonic black holes

Kerner and Mann's recent work shows that, for an uncharged and non-rotating black hole, its Hawking temperature can be exactly derived by fermions tunnelling from its horizons. In this paper, our main work is to improve the analysis to deal with charged fermion tunnelling from the general dilatonic black holes, specifically including the charged, spherically symmetric dilatonic black hole, the rotating Einstein-Maxwell-Dilaton-Axion (EMDA) black hole and the rotating Kaluza-Klein (KK) black hole. As a result, the correct Hawking temperatures are well recovered by charged fermions tunnelling from these black holes.Comment: 16 pages, revised version to appear in Class. Quant. Gra

Rings and rigidity transitions in network glasses

Three elastic phases of covalent networks, (I) floppy, (II) isostatically rigid and (III) stressed-rigid have now been identified in glasses at specific degrees of cross-linking (or chemical composition) both in theory and experiments. Here we use size-increasing cluster combinatorics and constraint counting algorithms to study analytically possible consequences of self-organization. In the presence of small rings that can be locally I, II or III, we obtain two transitions instead of the previously reported single percolative transition at the mean coordination number $\bar r=2.4$, one from a floppy to an isostatic rigid phase, and a second one from an isostatic to a stressed rigid phase. The width of the intermediate phase $~ \bar r$ and the order of the phase transitions depend on the nature of medium range order (relative ring fractions). We compare the results to the Group IV chalcogenides, such as Ge-Se and Si-Se, for which evidence of an intermediate phase has been obtained, and for which estimates of ring fractions can be made from structures of high T crystalline phases.Comment: 29 pages, revtex, 7 eps figure

Gauge theories as a geometrical issue of a Kaluza-Klein framework

We present a geometrical unification theory in a Kaluza-Klein approach that achieve the geometrization of a generic gauge theory bosonic component. We show how it is possible to derive the gauge charge conservation from the invariance of the model under extra-dimensional translations and to geometrize gauge connections for spinors, thus we can introduce the matter just by free spinorial fields. Then, we present the applications to i)a pentadimensional manifold $V^{4}\otimes S^{1}$, so reproducing the original Kaluza-Klein theory, unless some extensions related to the rule of the scalar field contained in the metric and the introduction of matter by spinors with a phase dependence from the fifth coordinate, ii)a seven-dimensional manifold $V^{4}\otimes S^{1}\otimes S^{2}$, in which we geometrize the electro-weak model by introducing two spinors for any leptonic family and quark generation and a scalar field with two components with opposite hypercharge, responsible of spontaneous symmetry breaking.Comment: 37 pages, no figure

Magnetska rezonancija u dijagnostici ozljeda koljenskoga zgloba

The possibilities of MR diagnosing knee pathology on high field scanners of 1T and 1.5T are well known. A sensitivity of 87%-100% and specificity of 64%-100% in diagnosing meniscal pathology are quoted in the literature. The aim of this work was to define the sensitivity and specificity of evaluation of meniscal lesions and cruciate ligament tears with a 0.2T permanent magnet of low field strength, as well as of other associated lesions of the bone, cartilage and collateral ligaments. We wished to estimate the value of particular sequences and projections of scanning chosen for certain pathology, and to recommend the type of scanning. MR findings were correlated with arthroscopy as the "gold standard method" in evaluating knee pathology. Two radiologists of different clinical experience interpreted MR findings by the principle of "interobserver difference". A total of 40 patients were examined, 32 men and 8 women, aged 17-46, mean age 27±5 years. The following sequences were used always in three projections: SE 1500/38; SE 1500/25; SE 1700/40; SE 200/38; SR 550/25; SR 550/38; GE 100/23/45; GE 100/23/60; and GE 500/23/40. We conclude that low field MRI is as sensitive and specific as diagnostic arthroscopy for traumatic meniscal lesions, yet better due to its noninvasiveness. MRI 0.2 T is of a lower specificity and sensitivity in detecting anterior cruciate ligament and chondral lesions in comparison with arthroscopy.Mogućnosti MR dijagnostike patologije koljenskoga zgloba na uređajima 1 i 1.5 T su poznate. U literaturi se navodi osjetljivost od 87%-100% i specifičnost od 64%-100% u dijagnostici patologije meniska na tim uređajima. Cilj rada bio je ustanoviti osjetljivost i specifičnost, odnosno vrijednost MR-e u pregledu meniska i ukriženih ligamenata koljenskoga zgloba MR-om 0.2T, niske jačine magnetskog polja, kao i procijeniti pridružene ozljede MR-om (ozljede hrskavice, kosti, kolateralnih ligamenata). Dobiveni MR nalazi korelirani su s artroskopijom kao zlatnim standardom. MR nalaze provjerilo je dvoje radiologa po načelu među promatračima ("interobserver difference"). Pregledano je ukupno 40 bolesnika, od toga 32 muškarca i 8 žena, u dobi od 17-46 godina, prosječne životne dobi 27±5 godina. Sljedeće sekvence su bile napravljene uvijek u tri projekcije: SE 1500/38; SE 1500/25; SE 1700/40; SE 200/38; SR 550/25; SR 550/38; GE 100/23/45; GE 100/23/60; GE 500/23/40. U zaključku: MR 0.2T je jednako osjetljiva metoda kao dijagnostička artroskopija u procjeni traumatskih ozljeda meniska, no dajemo joj prednost zbog neinvazivnosti. MR niske jačine polja slabije je osjetljiva metoda od artroskopije u procjeni lezije prednjega ukriženog ligamenta te ozljeda hrskavice