Steady two dimensional free-surface flow over semi-infinite and finite-length corrugations in an open channel

Free-surface flow past a semi-infinite or a finite length corrugation in an otherwise flat and horizontal open channel is considered. Numerical solutions for the steady flow problem are computed using both a weakly nonlinear and fully nonlinear model. The new solutions are classified in terms of a depth-based Froude number and the four classical flow types (supercritical, subcritical, generalised hydraulic rise and hydraulic rise) for flow over a small bump. While there is no hydraulic fall solution for semi-infinite topography, we provide strong numerical evidence that such a solution does exist in the case of a finite length corrugation. Numerical solutions are also found for the other flow types for either semi-infinite or finite length corrugation. For subcritical flow over a semi-infinite corrugation, the free-surface profile is found to be quasiperiodic in nature. A discussion of the new results is made with reference to the classical problem of flow over a bump

Historical trends of airborne trace metals in Detroit from 1971 to 1992

Ambient concentrations of particulate Fe, Zn, Ph, Ni, Cr, Cd and Hg were measured at nine sites located in the metropolitan area of Detroit from 1971 to 1992. The ambient concentrations of all the trace metals were found to be generally higher at industrial and commercial sites. The concentrations show significant variations between residential and commercial areas and between residential and industrial areas; however, no significant variation was found between the industrial and commercial settings. The spatial variation of trace metal levels within the urban area was influenced by the frequency distribution of the wind direction as well as type and location of emission sources. The ambient concentrations of the trace metals during the decade of 1971–1981 declined by 37–88%. In the 1980s many of the trace metals reversed this trend with the exception of Fe and Pb which continued to decline at annual rates of 2% and 9.8%, respectively. The sharp decrease in Pb concentrations during the 1980s, reflected the significant reduction of Pb content in gasoline from 0.28 g/liter in the 1982 to 0.026 g/liter in the 1989. The ambient concentrations of Zn, Ni, Cr, Cd and Hg showed an upward trend during the 1980s with an annual rate in the range of 0.6% to 10.6%. The long-term trends of selected U.S. market parameters, analyzed as potential long-term indicators of emission sources activityies, were consistent with the changes of ambient concentrations, the correlation coefficient being in the range of 0.58 to 0.84 for most of the trace metals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43917/1/11270_2004_Article_BF00157419.pd

Hyperfine Fields in an Ag/Fe Multilayer Film Investigated with 8Li beta-Detected Nuclear Magnetic Resonance

Low energy $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) was used to investigate the spatial dependence of the hyperfine magnetic fields induced by Fe in the nonmagnetic Ag of an Au(40 \AA)/Ag(200 \AA)/Fe(140 \AA) (001) magnetic multilayer (MML) grown on GaAs. The resonance lineshape in the Ag layer shows dramatic broadening compared to intrinsic Ag. This broadening is attributed to large induced magnetic fields in this layer by the magnetic Fe layer. We find that the induced hyperfine field in the Ag follows a power law decay away from the Ag/Fe interface with power $-1.93(8)$, and a field extrapolated to $0.23(5)$ T at the interface.Comment: 5 pages, 4 figure. To be published in Phys. Rev.

Explicitly solvable cases of one-dimensional quantum chaos

We identify a set of quantum graphs with unique and precisely defined spectral properties called {\it regular quantum graphs}. Although chaotic in their classical limit with positive topological entropy, regular quantum graphs are explicitly solvable. The proof is constructive: we present exact periodic orbit expansions for individual energy levels, thus obtaining an analytical solution for the spectrum of regular quantum graphs that is complete, explicit and exact

“This Is Something That Changed My Life”: A Qualitative Study of Patients' Experiences in a Clinical Trial of Ketamine Treatment for Alcohol Use Disorders

This is the final version. Available on open access from Frontiers Media via the DOI in this recordData Availability Statement: Due to ethical concerns, the research data supporting this publication are not publicly available.Background: The therapeutic benefits of ketamine have been demonstrated for a variety of psychiatric disorders. However, the role of ketamine induced psychoactive experiences in mediating the therapeutic effects is unclear. Despite the growing quantitative research on the efficacy of ketamine treatment, very few studies examined participant experiences of ketamine infusions in a treatment setting. Aims: The current study aimed to examine participant experiences of ketamine infusions and how these relate to therapeutic mechanisms in a clinical trial setting. Methods: We conducted semi-structured interviews with 12 participants who received up to three ketamine infusions (0.8 mg/kg) as part of a Phase II double blind, randomised controlled trial. The interviews explored participants' acute experiences of ketamine infusions, experiences of psychotherapy/education, and the lasting effects of the trial. The interviews were transcribed verbatim and analysed using thematic analysis. Results: Six key themes were identified. (1) Participants reported multifaceted motivations for trial participation. (2) The set and setting was found to be influential in determining acute ketamine experiences. The acute ketamine experiences included: (3) the inherent contradictions of the experience (e.g., dissociation vs feelings of connection), (4) rapidly fluctuating and changing experiences, (5) meaningful, mystical and spiritual experiences. Finally, the final theme (6) relates to the transformational effects of the infusions and the trial. Conclusion: Provided in a supportive and professional environment, ketamine treatment led to a significant change in relationship with alcohol. Ketamine induced ego dissolution and dissociation were reported to be related to the transformational effects on relationship with alcohol. The extent to which the acute psychoactive effects of ketamine mediate therapeutic effects on drinking outcomes remain to be investigated in the trial data. The acute effects of ketamine reported by our participants transcend its traditional conceptualisation as a “dissociative anaesthetic”; therefore, we suggest the development or use of new measures alongside ketamine infusions to fully capture the spectrum of these effects which may be crucial in its therapeutic and transformative effects.Medical Research Council (MRC)Society for the Study of AddictionUniversity of Exete

Noncritical M-Theory in 2+1 Dimensions as a Nonrelativistic Fermi Liquid

We claim that the dynamics of noncritical string theories in two dimensions is related to an underlying noncritical version of M-theory, which we define in terms of a double-scaled nonrelativistic Fermi liquid in 2+1 dimensions. After reproducing Type 0A and 0B string theories as solutions, we study the natural M-theory vacuum. The vacuum energy of this solution can be evaluated exactly, its form suggesting a duality to the Debye model of phonons in a melting solid, and a possible topological nature of the theory. The physical spacetime is emergent in this theory, only for states that admit a hydrodynamic description. Among the solutions of the hydrodynamic equations of motion for the Fermi surface, we find families describing the decay of one two-dimensional string theory into another via an intermediate M-theory phase.Comment: 47 pages, 1 figure; v2: typos corrected, references adde

Localization of supersymmetric field theories on non-compact hyperbolic three-manifolds

We study supersymmetric gauge theories with an R-symmetry, defined on non-compact, hyperbolic, Riemannian three-manifolds, focusing on the case of a supersymmetry-preserving quotient of Euclidean AdS$_3$. We compute the exact partition function in these theories, using the method of localization, thus reducing the problem to the computation of one-loop determinants around a supersymmetric locus. We evaluate the one-loop determinants employing three different techniques: an index theorem, the method of pairing of eigenvalues, and the heat kernel method. Along the way, we discuss aspects of supersymmetry in manifolds with a conformal boundary, including supersymmetric actions and boundary conditions.Comment: v3:79p, minor clarifications and references adde

Atmospheric sources, transport and deposition of mercury in Michigan: Two years of event precipitation

To assess the sources, transport and deposition of atmospheric mercury (Hg) in Michigan, a multi-site network was implemented in which Hg concentrations in event precipitation and ambient samples (vapor and participate phases) were determined. Results from the analysis of 2 years of event precipitation samples for Hg are reported here. The volume-weighted average Hg concentration in precipitation was 7.9, 10.8 and 10.2 ng/L for the Pellston, South Haven and Dexter sites, respectively. Yearly wet deposition of Hg for 1992–93 and 1993–94 was 5.8 and 5.5 μg/m 2 at Pellston, 9.5 and 12.7 μg/m 2 at South Haven and 8.7 and 9.1 μg/m at Dexter. A spatial gradient in both the Hg concentration and wet deposition was observed. Northern Michigan received almost half the deposition of Hg recorded at the southern Michigan sites. The concentration of Hg in precipitation exhibited a strong seasonal behavior with low values of 1.0 to 2.0 ng/L in winter and maximum values greater than 40 ng/L in summer. The spring, summer and autumn precipitation accounted for 89 to 91% of the total yearly Hg deposition. Mixed-layer back trajectories were calculated for each precipitation event to investigate the meteorological history and transport from potential Hg source regions. Elevated Hg concentrations were observed with air mass transport from the west, southwest, south, and southeast. At each of the sites precipitation events for which the Hg concentration was in the 90th and 10th percentile were-analyzed for trace elements by ICP-MS to investigate source impacts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43912/1/11270_2005_Article_BF01189668.pd

Ambient levels and dry deposition fluxes of mercury to Lakes Huron, Erie and St. Clair

Ambient concentrations and dry deposition fluxes of Hg in the gas and particle phase to Lakes St. Clair, Erie and Huron were estimated with a hybrid receptor-deposition model (HRD). The ambient gas and particulate phase Hg concentrations were predicted to vary by a factor of 12 to 18 during the transport of air masses traversing the lakes. The ensemble average deposition fluxes of fine particle Hg ranged from 7 pg/m 2 -h to 15.3 pg/m 2 -h over Lake St. Clair, 0.5 to 4.2 pg/m 2 -h over Lake Huron and 5.1 to 20.6 pg/m 2 -h over Lake Erie. The deposition flux of coarse particle Hg was in the range of 50 to 84 pg/m 2 -h over Lake St. Clair, 4.7 to 24.2 pg/m 2 -h over Lake Huron and 5.1 to 20.6 pg/m 2 -h over Lake Erie. Gaseous Hg volatilized at a rate of 0.21 to 0.52 ng/m 2 -h from Lake Huron and 0.13 to 0.36 from Lake Erie. Gas phase Hg was deposited at a rate of 5.9 ng/m 2 -h and/or volatilized at a rate of 0.5 ng/m 2 -h from Lake St. Clair depending upon the location of the sampling site used in the HRD model. The effect of meteorological conditions, particle size distributions and type and location of the sampling sites played an important role in the transfer of atmospheric Hg to and/or from the lakes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43911/1/11270_2005_Article_BF01189666.pd

Effect of noise on coupled chaotic systems

Effect of noise in inducing order on various chaotically evolving systems is reviewed, with special emphasis on systems consisting of coupled chaotic elements. In many situations it is observed that the uncoupled elements when driven by identical noise, show synchronization phenomena where chaotic trajectories exponentially converge towards a single noisy trajectory, independent of the initial conditions. In a random neural network, with infinite range coupling, chaos is suppressed due to noise and the system evolves towards a fixed point. Spatiotemporal stochastic resonance phenomenon has been observed in a square array of coupled threshold devices where a temporal characteristic of the system resonates at a given noise strength. In a chaotically evolving coupled map lattice with logistic map as local dynamics and driven by identical noise at each site, we report that the number of structures (a structure is a group of neighbouring lattice sites for whom values of the variable follow certain predefined pattern) follow a power-law decay with the length of the structure. An interesting phenomenon, which we call stochastic coherence, is also reported in which the abundance and lifetimes of these structures show characteristic peaks at some intermediate noise strength.Comment: 21 page LaTeX file for text, 5 Postscript files for figure