Pilot-scale Testing of Chlorite to Control Nitrification in Drinking Water Distribution Systems

The study used pilot test units to simulate a drinking water distribution system. Each test unit was dosed with chloraminated test water and ammonia-oxidizing bacteria to see if nitrification would become established in the test units. Once nitrification was established, the test units were dosed with chlorite at concentrations of 0.05, 0.1, 0.2, 0.4, 0.6, and 0.8 mg/l. Nitrite-nitrogen levels of 0.05 mg/l and higher signified a nitrification event. Nitrification did become established in all the test units. The chlorite feed stopped nitrification within 23 days in the test units with doses of 0.1, 0.2, 0.4, and 0.6 mg/l of nitrite-nitrogen. It took 43 days for nitrification to stop in the test unit with 0.05mg/l of nitrite-nitrogen. The test unit with 0.8 mg/l of chlorite never reached the nitrification threshold of 0.05 mg/l nitrite-nitrogen even though nitrite-nitrogen levels had fallen to levels of 0.09 mg/l nitrite-nitrogen by the end of the test. This test unit had a malfunctioning effluent needle valve that caused the residence time of the test water to be over 15 days whereas the other test units averaged 11 days of residence time. It can be concluded that chlorite, when used with other nitrification control strategies, can control nitrification in the City of Tulsa's drinking water distribution system. Chlorite can either be directly added to the drinking water in the form of sodium chlorite, or it can be the residual of chlorine dioxide use. It is significantly more cost effective to directly add chlorite as sodium chlorite.Biosystems and Agricultural Engineerin

Vacuum energy in a spherically symmetric background field

The vacuum energy of a scalar field in a spherically symmetric background field is considered. It is expressed through the Jost function of the corresponding scattering problem. The renormalization is discussed in detail and performed using the uniform asymptotic expansion of the Jost function. The method is demonstrated in a simple explicit example.Comment: 14 pages, 1 Postscript figur

Identifying Adolescents at Highly Elevated Risk for Suicidal Behavior in the Emergency Department

Objective: The feasibility and concurrent validity of adolescent suicide risk screening in medical emergency departments (EDs) has been documented. The objectives of this short-term prospective study of adolescents who screened positive for suicide risk in the ED were: 1) to examine adolescents' rate of suicidal behavior during the 2 months following their ED visits and compare it with reported rates for psychiatric samples; and 2) to identify possible predictors of acute risk for suicidal behavior in this at-risk sample. Method: Participants were 81 adolescents, ages 14?19 years, seeking services for psychiatric and nonpsychiatric chief complaints, who screened positive for suicide risk because of recent suicidal ideation, a suicide attempt, and/or depression plus alcohol or substance misuse. A comprehensive assessment of suicidal behavior, using the Columbia-Suicide Severity Rating Scale, was conducted at baseline and 2 month follow-up. Results: Six adolescents (7.4%) reported a suicide attempt and 15 (18.5%) engaged in some type of suicidal behavior (actual, aborted, or interrupted suicide attempt; preparatory behavior) during the 2 months following their ED visit. These rates suggest that this screen identified a high-risk sample. Furthermore, adolescents who screened positive for suicidal ideation and/or attempt plus depression and alcohol/substance misuse were most likely to engage in future suicidal behavior (38.9%). Conclusions: In this study, use of a higher screen threshold (multiple suicide risk factors) showed promise for identifying highly elevated acute risk for suicidal behavior.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140322/1/cap.2014.0049.pd

Static solitons with non-zero Hopf number

We investigate a generalized non-linear O(3) $\sigma$-model in three space dimensions where the fields are maps $S^3 \mapsto S^2$. Such maps are classified by a homotopy invariant called the Hopf number which takes integer values. The model exhibits soliton solutions of closed vortex type which have a lower topological bound on their energies. We explicitly compute the fields for topological charge 1 and 2 and discuss their shapes and binding energies. The effect of an additional potential term is considered and an approximation is given for the spectrum of slowly rotating solitons.Comment: 13 pages, RevTeX, 7 Postscript figures, minor changes have been made, a reference has been corrected and a figure replace

Implications of LEP Results for SO(10) Grandunification with Two Intermediate Stages

We consider the breaking of the grand unification group $SO(10)$ to the standard model gauge group through several chains containing two intermediate stages. Using the values of the gauge coupling constants at scale $M_Z$ derived from recent LEP data, we determine the range of their intermediate and unification scales. In particular, we identify those chains that permit new gauge structure at relatively low energy $(\sim 1\, {\rm TeV})$.Comment: (LATEX, 9 pages + 3 pages of figures not included) OITS-48

Collision-Induced Decay of Metastable Baby Skyrmions

Many extensions of the standard model predict heavy metastable particles which may be modeled as solitons (skyrmions of the Higgs field), relating their particle number to a winding number. Previous work has shown that the electroweak interactions admit processes in which these solitons decay, violating standard model baryon number. We motivate the hypothesis that baryon-number-violating decay is a generic outcome of collisions between these heavy particles. We do so by exploring a 2+1 dimensional theory which also possesses metastable skyrmions. We use relaxation techniques to determine the size, shape and energy of static solitons in their ground state. These solitons could decay by quantum mechanical tunneling. Classically, they are metastable: only a finite excitation energy is required to induce their decay. We attempt to induce soliton decay in a classical simulation by colliding pairs of solitons. We analyze the collision of solitons with varying inherent stabilities and varying incident velocities and orientations. Our results suggest that winding-number violating decay is a generic outcome of collisions. All that is required is sufficient (not necessarily very large) incident velocity; no fine-tuning of initial conditions is required.Comment: 24 pages, 7 figures, latex. Very small changes onl

CP Violation from Surface Terms in the Electroweak Theory without Fermions

We consider the effect of adding a CP-odd, theta FFdual-term to the electroweak Lagrangian without fermions. This term affects neither the classical nor perturbatively quantum physics, but can be observed through non-perturbative quantum processes. We give an example of such a process by modifying the theory so that it supports Higgs-winding solitons and showing that the rates of decay of these solitons to specific final states are CP violating. We also discuss how the CP symmetry is restored when fermions are included.Comment: 11 pages, REVTEX, final version to be published in Phys. Rev.

Molecular Population Structure for Feral Swine in the United States

Feral swine (Sus scrofa) have invaded most of the United States and continue to expand throughout North America. Given the ecological and economic threats posed by increasing feral swine abundance, it is imperative to develop an understanding of their patterns of natural range expansion and human-mediated introductions. Towards this goal, we used molecular markers to elucidate the genetic structure of feral swine populations throughout the United States and evaluated the association between historical introductions and contemporary patterns of genetic organization. We used STRUCTURE and discriminant analysis of principal components (DAPC) to delineate genetic clusters for 959 individuals genotyped at 88 single nucleotide polymorphism loci. We identified 10 and 12 genetic clusters for the 2 clustering approaches, respectively. We observed strong agreement in clusters across approaches, with both describing clusters having strong geographic association at regional levels reflecting past introduction and range expansion patterns. In addition, we evaluated patterns of isolation by distance to test for and estimate spatial scaling of population structure within western, central, and eastern regions of North America. We found contrasting spatial patterns of genetic relatedness among regions, suggesting differences in the invasion process, likely as a result of regional variation in landscape heterogeneity and the influence of human mediated introductions. Our results indicate that molecular analyses of population genetic structure can provide reliable insights into the invasion processes of feral swine, thus providing a useful basis for management focused on minimizing continued range expansion by this problematic species

Hierarchical organization of urban mobility and its connection with city livability

This is the final version. Available on open access from Nature Research via the DOI in this recordThe recent trend of rapid urbanization makes it imperative to understand urban characteristics such as infrastructure, population distribution, jobs, and services that play a key role in urban livability and sustainability. A healthy debate exists on what constitutes optimal structure regarding livability in cities, interpolating, for instance, between mono- and poly-centric organization. Here anonymous and aggregated flows generated from three hundred million users, opted-in to Location History, are used to extract global Intra-urban trips. We develop a metric that allows us to classify cities and to establish a connection between mobility organization and key urban indicators. We demonstrate that cities with strong hierarchical mobility structure display an extensive use of public transport, higher levels of walkability, lower pollutant emissions per capita and better health indicators. Our framework outperforms previous metrics, is highly scalable and can be deployed with little cost, even in areas without resources for traditional data collection.Conselleria d’Educacio, Cultura i Universitats of the Government of the Balearic IslandsEuropean Social FundSpanish Ministry of Science, Innovation and UniversitiesNational Agency for Research Funding AEIFEDER (EU)Maria de Maeztu program for Units of Excellence in R&DNYS Center of Excellence in Data Science, University of RochesterU. S. Army Research Office (ARO

Predictive fermion mass matrix ansatzes in non-supersymmetric SO(10) grand unification

We investigate the status of predictive fermion mass ansatzes which make use of the grand unification scale conditions $m_e=m_d/3$, $m_\mu =3m_s$, and $\mid V_{cb}\mid =\sqrt{m_{c}/m_{t}}$ in non-supersymmetric SO(10) grand unification. The gauge symmetry below an intermediate symmetry breaking scale $M_I$ is assumed to be that of the standard model with either one Higgs doublet or two Higgs doublets . We find in both cases that a maximum of 5 standard model parameters may be predicted within $1\sigma$ experimental ranges. We find that the standard model scenario predicts the low energy $\mid V_{cb}\mid$ to be in a range which includes its experimental mid-value 0.044 and which for a large top mass can extend to lower values than the range resulting in the supersymmetric case. In the two Higgs standard model case, we identify the regions of parameter space for which unification of the bottom quark and tau lepton Yukawa couplings is possible at grand unification scale. In fact, we find that unification of the top, bottom and tau Yukawa couplings is possible with the running b-quark mass within the $1\sigma$ preferred range $m_b=4.25\pm 0.1\, GeV$ provided $\alpha_{3c}(M_Z)$ is near the low end of its allowed range. In this case, one may make 6 predictions which include $\mid V_{cb}\mid$ within its $90\%$ confidence limits. However unless the running mass $m_b>4.4\, GeV$, third generation Yukawa coupling unification requires the top mass to be greater thanComment: 30 pages, 8 figures available on request from [email protected], Late