On Deriving Space-Time From Quantum Observables and States

We prove that, under suitable assumptions, operationally motivated data completely determine a space-time in which the quantum systems can be interpreted as evolving. At the same time, the dynamics of the quantum system is also determined. To minimize technical complications, this is done in the example of three-dimensional Minkowski space.Comment: 19 pages, to appear in Communications in Mathematical Physics; minor corrections mad

Remarks on Causality in Relativistic Quantum Field Theory

It is shown that the correlations predicted by relativistic quantum field theory in locally normal states between projections in local von Neumann algebras \cA(V_1),\cA(V_2) associated with spacelike separated spacetime regions $V_1,V_2$ have a (Reichenbachian) common cause located in the union of the backward light cones of $V_1$ and $V_2$. Further comments on causality and independence in quantum field theory are made.Comment: 10 pages, Latex, Quantum Structures 2002 Conference Proceedings submission. Minor revision of the order of definitions on p.

A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory

A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino factory. Eddy current losses are held to less than a megawatt by the low machine duty cycle plus 100 micron thick grain oriented silicon steel laminations and 250 micron diameter copper wires. Combined function magnets with 20 T/m gradients alternating within single magnets form the lattice. Muon survival is 83%.Comment: 4 pages, 1 figures, LaTeX, 5th International Workshop on Neutrino Factories and Superbeams (NuFact 03), 5-11 Jun 2003, New Yor

Noncommutative Common Cause Principles in Algebraic Quantum Field Theory

States in algebraic quantum field theory "typically" establish correlation between spacelike separated events. Reichenbach's Common Cause Principle, generalized to the quantum field theoretical setting, offers an apt tool to causally account for these superluminal correlations. In the paper we motivate first why commutativity between the common cause and the correlating events should be abandoned in the definition of the common cause. Then we show that the Noncommutative Weak Common Cause Principle holds in algebraic quantum field theory with locally finite degrees of freedom. Namely, for any pair of projections A, B supported in spacelike separated regions V_A and V_B, respectively, there is a local projection C not necessarily commuting with A and B such that C is supported within the union of the backward light cones of V_A and V_B and the set {C, non-C} screens off the correlation between A and B

Generic Bell correlation between arbitrary local algebras in quantum field theory

We prove that for any two commuting von Neumann algebras of infinite type, the open set of Bell correlated states for the two algebras is norm dense. We then apply this result to algebraic quantum field theory -- where all local algebras are of infinite type -- in order to show that for any two spacelike separated regions, there is an open dense set of field states that dictate Bell correlations between the regions. We also show that any vector state cyclic for one of a pair of commuting nonabelian von Neumann algebras is entangled (i.e., nonseparable) across the algebras -- from which it follows that every field state with bounded energy is entangled across any two spacelike separated regions.Comment: Third version; correction in the proof of Proposition

Diagnosing transient ionization in dynamic events

The present study aims to provide a diagnostic line ratio that will enable the observer to determine whether a plasma is in a state of transient ionization. We use the Atomic Data and Analysis Structure (ADAS) to calculate line contribution functions for two lines, Si IV 1394 A and O IV 1401 A, formed in the solar transition region. The generalized collisional-radiative theory is used. It includes all radiative and electron collisional processes, except for photon-induced processes. State-resolved direct ionization and recombination to and from the next ionization stage are also taken into account. For dynamic bursts with a decay time of a few seconds, the Si IV 1394 A line can be enhanced by a factor of 2-4 in the first fraction of a second with the peak in the line contribution function occurring initially at a higher electron temperature due to transient ionization compared to ionization equilibrium conditions. On the other hand, the O IV 1401 A does not show such any enhancement. Thus the ratio of these two lines, which can be observed with the Interface Region Imaging Spectrograph, can be used as a diagnostic of transient ionization. We show that simultaneous high-cadence observations of two lines formed in the solar transition region may be used as a direct diagnostic of whether the observed plasma is in transient ionization. The ratio of these two lines can change by a factor of four in a few seconds owing to transient ionization alone.Comment: 3 pages, in press A&

Einstein-Podolsky-Rosen correlations between two uniformly accelerated oscillators

We consider the quantum correlations, i.e. the entanglement, between two systems uniformly accelerated with identical acceleration a in opposite Rindler quadrants which have reached thermal equilibrium with the Unruh heat bath. To this end we study an exactly soluble model consisting of two oscillators coupled to a massless scalar field in 1+1 dimensions. We find that for some values of the parameters the oscillators get entangled shortly after the moment of closest approach. Because of boost invariance there are an infinite set of pairs of positions where the oscillators are entangled. The maximal entanglement between the oscillators is found to be approximately 1.4 entanglement bits.Comment: 11 page

6D Muon Ionization Cooling with an Inverse Cyclotron

A large admittance sector cyclotron filled with LiH wedges surrounded by helium or hydrogen gas is explored. Muons are cooled as they spiral adiabatically into a central swarm. As momentum approaches zero, the momentum spread also approaches zero. Long bunch trains coalesce. Energy loss is used to inject the muons into the outer rim of the cyclotron. The density of material in the cyclotron decreases adiabatically with radius. The sector cyclotron magnetic fields are transformed into an azimuthally symmetric magnetic bottle in the center. Helium gas is used to inhibit muonium formation by positive muons. Deuterium gas is used to allow captured negative muons to escape via the muon catalyzed fusion process. The presence of ionized gas in the center may automatically neutralize space charge. When a bunch train has coalesced into a central swarm, it is ejected axially with an electric kicker pulse.Comment: Five pages. LaTeX, three postscript figure files. To appear in the AIP Conference Proceedings for COOL05: International Workshop on Beam Cooling, Galena, IL, 18-23 Sept. 200

Biodegradation Behavior of Ozonated Natural Organic Matter in Sand Filters

Aujourd'hui, il est démontré que les traitements biologiques utilisés pour le traitement de l'eau potable sont des méthodes efficaces pour la réduction de la matière organique de l'eau, des sous-produits de la désinfection, ainsi que pour le contrôle de la croissance bactérienne dans les réseaux.Quelques études récentes ont tenté de modéliser ce qui se passait sur les filtres biologiques utilisés pour le traitement de l'eau potable. Les modèles de biofilms développés pour les eaux usées sont souvent utilisés pour l'eau potable. Contrairement au biofilm des eaux usées, épais et dense, celui de l'eau potable est dispersè en fraction dans le milieu du filtre ainsi que sur sa pami. Le biofilm est donc très dispersé et les paramètres importants de modélisation du biofilm en eau usée (densité, épaisseur) ne sont pas appropriés pour l'estimation du biofilm dans les filtres d'eau potable.La matière organique est constituée d'un ensemble complexe de composés organiques. Quelques-uns ne sont pas facilement biodégradables, d'autres le sont facilement et une autre fraction est récalcitrante. Dans ces conditions, un modèle utilisant un seul substrat pour représenter la cinétique de biodégradation n'est pas approprié. WANG et SUMMERS (1994) ont récemment développé un modèle mathématique utilisant plusieurs substrats pour décrire la réduction de la matière organique de l'eau dans les filtres biologiques. Le modèle suppose que la filtration biologique est composée de deux étapes : un transfert massique exteme suivi de l'utilisation du substrat à la surface du filtre. Dans ce modèle, la matière organique est divisée en trois portions: des composés facilement ou lentement biodégradables et récalcitrants. Des vitesses différentes de réaction sont utilisées pour chaque fraction. Les résultats démontrent que la diminution de la concentration de la matière organique est souvent limitée parle taux d'utilisation des substrats, et non pas par la vitesse du transfert exteme de la matière.Les objectifs de cette recherche sont d'identifier les éléments de la matière organique ainsi que les composés lentement ou rapidement biodégradables et de suivre l'évolution de ces composés dans les filtres biologiques.Une fois traitée par ozonisation, la matière organique est utilisée comme substrat dans cette recherche. La matière organique a été isolée par concentration sur résine échangeuse d'ions d'une eau souterraine prélevée en Allemagne. Le taux de traitements en ozone a été de 0,35 mg O3 par mg de carbone organique dissous (COD). Un sable bioacclimaté a été utilisé comme milieu filtrant et comme source de biomasse. Avant chaque expérience, il a été mélangé pour avoir une répartition homogène de la biomasse dans le filtre, La quantité de substrats était mesurée par les analyses du COD, du carbone organique dissous biodégradable (CODB), du carbone organique assimilable (COA), des aldéhydes et d'acides cétoniques. Les résultats, exprimés en terme du temps de contact théorique, démontrent que la vitesse de filtration dans le filtre (dans des proportions de 1,5 à 15 m/h) n'a pas d'influence sur la réduction des substrats. Le facteur limitant pour l'élimination du carbone organique par filtration est donc l'utilisation du substrat et non par le transfert externe de matière.Dans cette recherche, la fraction de la matière organique est appelée « rapidement biodégradable » si elle est éliminée dans les trois premières minutes du temps de contact. Elle constitue 15 ib du COD. La fraction du CODB de l'eau traitée par ozonisation représente environ 40 à 45 % du COD.Presqu'un tiers du CODB est rapidement biodégradé. Les résultats démontrent que 90 % du COA est utilisé par le Spirillum sp . NOX (COA-NOX), et que presque tout le COA est rapidement biodégradé et s'élimine par biofiltration en une minute de temps de contact. Le glyoxal et le méthyl glyoxal sont totalement éliminés après deux minutes de temps de contact. Par contre, seulement 60 % du formaldéhyde est éliminé dans les deux premières minutes de temps de contact et l'augmentation du temps de contact n'engendre pas une élimination supplémentaire. En outre, on n'observe pas de réduction significative de l'acétaldéhyde. Les résultats démontrent que les acides cétoniques sont rapidement et fortement dégradés. Plus de 90 % d'acide glyoxalique et d'acide pyruvique sont éliminés dans la première minute de temps de contact.Natural organic matter (NOM) in drinking water is a complex mixture of organic compounds. Some of the compounds are not biodegradable, while others are quickly biodegradable and a third group is more resistant to biodegradation. To have a better understanding of the biofiltration process in drinking water treatment, it is important to identify the elements of the quickly and slowly biodegradable NOM and to characterize the biodegradation rate of each element. In this study, an ozonated NOM solution was used as the substrate. The NOM was isolated from a groundwater in Germany using ion-exchange resins. The ozone dose was 0.35 mg O3/mg DOC (dissolved organic carbon). Previously bioacclimated sand was used as filter media and biomass source and was homogeneously distributed in the filter prior to each run. The substrate removal was evaluated by DOC, biodegradable DOC (BDOC), assimilable organic carbon (AOC), aldehyde and ketoacid analyses. When expressed in terms of the empty bed contact time (EBCT), the results showed that filter velocity in the range of 1.5 to 15 m/hr had no impact on substrate removal. This implies that substrate utilization, not external mass transfer, is the rate limiting step for substrate removal in drinking water biofilters. In this study, compounds or NOM fractions are termed quickly biodegradable if they are removed in the first three minutes of EBCT. 15% of the DOC was removed by the biofilter within three minutes of EBCT and was termed the quickly biodegradable fraction. The BDOC fraction of the ozonated solution was determined to be 40 to 45% of the DOC. In terms of BDOC, about one third of the total BDOC was quickly biodegradable. The AOC results show that about 90% of the total AOC was utilized by Spirillum sp. NOX (AOC-NOX). Most of the AOC was quickly biodegradable and was removed within one minute of EBCT. For aldehydes, glyoxal and methyl glyoxal were removed to below the detection limit after two minutes of EBCT. However, only 60% of formaldehyde removal was achieved in the first two minutes of EBCT, and no additional removal was achieved with increasing EBCT. Additionally, no significant removal of acetaldehyde was observed. The results of ketoacids show that their utilization rates were very high. More than 90% of glyoxylic acid and pyruvic acid were removed within one minute of EBCT

Neuronal convergence in early contrast vision: binocular summation is followed by response nonlinearity and area summation

We assessed summation of contrast across eyes and area at detection threshold ( C t). Stimuli were sine-wave gratings (2.5 c/deg) spatially modulated by cosine- and anticosine-phase raised plaids (0.5 c/deg components oriented at ±45°). When presented dichoptically the signal regions were interdigitated across eyes but produced a smooth continuous grating following their linear binocular sum. The average summation ratio ( C t1/([ C t1+2]) for this stimulus pair was 1.64 (4.3 dB). This was only slightly less than the binocular summation found for the same patch type presented to both eyes, and the area summation found for the two different patch types presented to the same eye. We considered 192 model architectures containing each of the following four elements in all possible orders: (i) linear summation or a MAX operator across eyes, (ii) linear summation or a MAX operator across area, (iii) linear or accelerating contrast transduction, and (iv) additive Gaussian, stochastic noise. Formal equivalences reduced this to 62 different models. The most successful four-element model was: linear summation across eyes followed by nonlinear contrast transduction, linear summation across area, and late noise. Model performance was enhanced when additional nonlinearities were placed before binocular summation and after area summation. The implications for models of probability summation and uncertainty are discussed