CONFINEMENT IN RELATIVISTIC POTENTIAL MODELS

In relativistic potential models of quarkonia based on a Dirac-type of equation with a local potential there is a sharp distinction between a linear potential V which is vector-like and one which is scalar-like: There are normalizable solutions for a scalar-like V but not for a vector-like V. It is pointed out that if instead one uses an equation of the no-pair type, which is more natural from the viewpoint of field theory, this somewhat bizarre difference disappears.Comment: LaTeX, 4 page

Lower bound for the ground state energy of the no-pair Hamiltonian

A lower bound for the ground state energy of a one particle relativistic Hamiltonian - sometimes called no-pair operator - is provided.Comment: 5 pages, 1 figure, 1 table, Latex2e (amssymb,amsmath,graphicx

Utilizing sedimentology and geochronology to resolve the architecture of paralic strata in low-accommodation systems, McMurray Formation, Canada

A combined sedimentological-geochronological approach is employed to unravel the importance of paleoenvironments landward of the shoreline in understanding the stratigraphic architecture, and chronostratigraphy of the McMurray Formation in the Alberta Foreland Basin (referred to herein as the McMurray Depocenter; MDC), Canada. Presently, the McMurray Fm is subdivided based on the presence of regionally mappable mudstones, the bases of which are interpreted as flooding surfaces. However, the McMurray Fm comprises a wide range of paleoenvironments, and the Firebag Tributary in the northeastern MDC hosts a large volume of delta and coastal plain strata, including channels, mires, and interfluves. Facies characteristics, stratigraphic architecture, and geochronology of these deposits are explored and 3 main conclusions are derived. First, petrographic trends in coals sitting at the top of the Lower McMurray formed following increasing rates (0.5-3 mmyr-1) of sea-level rise during the Early Cretaceous. These coals outline the paleo-shoreline in the Firebag Tributary during Lower McMurray times. An ash-bed situated in this coal is dated at 121.39 ± 0.20 Ma, providing the first absolute age in the McMurray Fm. Second, the absolute age at the top of the Lower McMurray is used as a reference point to subdivide the McMurray Fm chronostratigraphically using detrital zircon (DZ). In a new stratigraphic approach to DZ geochronology, DZ samples from 5 stratigraphic intervals are combined to created novel grouped DZ samples. Grouped DZ samples showcase geographical provenance variability within depositional systems of the same stratigraphic interval, and are used calculate novel grouped maximum depositional ages. Third, detailed facies analysis and stratigraphic correlation of paralic strata in the Firebag Tributary allows for the identification of 2 progradational and 2 retrogradational phases of deposition. During Lower McMurray times the paleo-shoreline resided near the western edge of the Firebag Tributary, and mature paleosols underlying coals at its top indicate a potential maximum regressive surface. During the C2-B2 depositional units (DU), regression lead to paleo-shorelines close to the Alberta-Saskatchewan border. This is followed by a phase of progradation during the B1 DU, where paralic strata capping the unit lack evidence of base-level fall and demarcate major flooding. Progressive transgression ensued during deposition of the A2-A1 DUs. An ash-bed at the top of the B1 DU (115.07 ± 0.16 Ma) reveals that Lower McMurray to B1 DUs were deposited over ~1.6 Ma each, followed by ~0.8 Ma and ~0.4 Ma for the A2 and A1 DUs, respectively

Modeling the recovery of antropogenically acidified mountain waters

Souhrn disertace Předkládanádisertačnípráce se skládá z pěti rukopisůpublikovanýchv recenzovaných odbomýchčasopisech.Tématickyje zaměřenana dopady antropogenniacidifikace na sladkovodníekosystémyv Českérepub|ice a na Slovensku' Mode|oviirrípřispívá k pochopenípruběhu procesůvedoucích k zotavováni (recoveryy) těchto lokalit z acidifikace.Studiumvlivůacidifikacena chemickéa biologickésloženivysokohors|oých jezerv Tatrácha na Šumavěmá již ďouholetoutradici.oproti tomu dopadytohotojevu na pramennétoky v horslcýcha wchovinných oblastechČn uyty rozpozniinyrelativně nedávno,a přislušnézměny ve struktuřepotoěníhomakrozoobentosua chemismuvody jsou zniírnyméně' Ve svépráci použivrí'rndynamickémodely (zahrnujícíi možnéscénďe budoucích klimatických změn) k hodnocenisouěasnéhostavu a budoucíchtrendůve zotavování acidifikovarrýchekosystémů,ke kterémunyní dochazi v důsledkusníŽeníkyselých atÍnosferickýchimisi. Prvni kapitola práceje zaměřenana vliv nizkéhopH na složení makozoobentosuv acidifikovanýchpotocíchv Českérepublice.Druhá kapitolashrnuje akturí'lniúdajeo chemickémsloŽeni vody v91 tatranslcýchjezerech: data zr.2004 zachycují situaci 15 let po ýmamném sníženíatmosférickýchimisí. Nás|edujici kapitola zahrnuje výsledky biogeochemickéhomodelu MAGIC kalibrovanéhona několika tatranskýchjezerech, a vyhodnocuje budoucí...11 Abstract In order for an economic system to function and produce goods and services necessary for meeting human needs, it behaves similarly to a living organism. It absorbs materials from the surrounding environment and transforms them into products, but ultimately all the materials are transformed into some kind of waste and emitted back into the environment. This flow of materials is referred to as industrial or socio-economic metabolism (Baccini and Brunner, 1991; Fischer-Kowalski and Haberl, 1993; Ayres and Simonis, 1994). Extraction of resources, consumption of materials and related emissions exert some pressure on the environment. So far, there has been a positive relation between meeting human needs and this pressure. The overall goal of developed countries within their strategies of sustainable development is to break the relation between pressure exerted on the environment and economic growth, which represents meeting of human needs and improvements in the standard of living. This phenomenon is called decoupling (EC, 2002, 2005, 2006; OECD, 2002; UN, 2002). One of the methods for assessing environmental pressure related to extraction and consumption of resources and materials is material flow analysis. In the case of economy- wide material flow analysis (EW-MFA), this method aims at...Katedra parazitologie a hydrobiologie (zrušena)Dep. of Parasitology and Hydrobiology (obsolete)Přírodovědecká fakultaFaculty of Scienc

PSR beam-pulse formation and control

The Proton Storage Ring (PSR) is a major addition to the Weapons Neutron Research Facility (WNR) at LAMPF. It will act as a bunch compressor for the relatively long linac macropulses from LAMPF, tailoring them into short, intense pulses ideally suited for neutron-scattering research. This paper concentrates on the methods used to form these pulses before injection into the linac, to multiplex the PSR beam with other LAMPF users, and to synchronize the storage ring with pulse arrival time at injection and with the WNR mechanical neutron chopper at extraction

Predicting long-term recovery of a strongly acidified stream using MAGIC and climate models (Litavka, Czech Republic)

Two branches forming the headwaters of a stream in the Czech Republic were studied. Both streams have similar catchment characteristics and historical deposition; however one is rain-fed and strongly affected by acid atmospheric deposition, the other spring-fed and only moderately acidified. The MAGIC model was used to reconstruct past stream water and soil chemistry of the rain-fed branch, and predict future recovery up to 2050 under current proposed emissions levels. A future increase in air temperature calculated by a regional climate model was then used to derive climate-related scenarios to test possible factors affecting chemical recovery up to 2100. Macroinvertebrates were sampled from both branches, and differences in stream chemistry were reflected in the community structures. According to modelled forecasts, recovery of the rain-fed branch will be gradual and limited, and continued high levels of sulphate release from the soils will continue to dominate stream water chemistry, while scenarios related to a predicted increase in temperature will have little impact. The likelihood of colonization of species from the spring-fed branch was evaluated considering the predicted extent of chemical recovery. The results suggest that the possibility of colonization of species from the spring-fed branch to the rain-fed will be limited to only the acid-tolerant stonefly, caddisfly and dipteran taxa in the modelled period

On the validity of the reduced Salpeter equation

We adapt a general method to solve both the full and reduced Salpeter equations and systematically explore the conditions under which these two equations give equivalent results in meson dynamics. The effects of constituent mass, angular momentum state, type of interaction, and the nature of confinement are all considered in an effort to clearly delineate the range of validity of the reduced Salpeter approximations. We find that for $J\not{\hspace*{-1.0mm}=}0$ the solutions are strikingly similar for all constituent masses. For zero angular momentum states the full and reduced Salpeter equations give different results for small quark mass especially with a large additive constant coordinate space potential. We also show that $\frac{1}{m}$ corrections to heavy-light energy levels can be accurately computed with the reduced equation.Comment: Latex (uses epsf macro), 24 pages of text, 12 postscript figures included. Slightly revised version, to appear in Phys. Rev.

Non-perturbative dynamics of the heavy-light quark system in the non-recoil limit

Starting from the relativistic gauge-invariant quark-antiquark Green function we obtain the relevant interaction in the one-body limit, which can be interpreted as the kernel of a non-perturbative Dirac equation. We study this kernel in different kinematic regions, reproducing, in particular, for heavy quark the potential case and sum rules results. We discuss the relevance of the result for heavy-light mesons and the relation with the phenomenological Dirac equations used up to now in the literature.Comment: 11 pages, LaTex, elsevier.sty, 2 figures included, minor changes, one reference added, to appear in Phys. Lett.

A Variational Approach to the Spinless Relativistic Coulomb Problem

By application of a straightforward variational procedure we derive a simple, analytic upper bound on the ground-state energy eigenvalue of a semirelativistic Hamiltonian for (one or two) spinless particles which experience some Coulomb-type interaction.Comment: 7 pages, HEPHY-PUB 606/9