Public-Private Partnerships (PPP) in Transportation: An Analysis of Alternatives

Public-Private Partnerships (PPP) are in the forefront of approaches to funding transportation infrastructure improvements. Highlighted in the highway area by long-term leases of the Chicago Skyway and Indiana Toll Road, a variety of states are investigating the use of public private partnerships either as “Brownfield” leases like the Chicago and Indiana cases, or “Greenfield” Design, Build, Operate, Transfer arrangements. These and other PPP projects raise a variety of issues, including the length of the lease, toll escalation permitted, and use of funds. This paper develops a rationale for PPPs in transportation, evaluates several approaches to PPPs using this rationale, and analyzes some of the difficult issues that can surface

Efficiency and Effectiveness Impacts of a Computer-Assisted Scheduling and Dispatching System Implementation

Computer-assisted scheduling and dispatch (CASD) systems have been implemented in many paratransit systems in the United States to improve the effectiveness and efficiency of operations. This paper contributes to the limited literature of studies documenting the impact of such systems on paratransit operations based on the implementation of such a system in a small city in Illinois. The analysis provides evidence of small but measurable efficiency and effectiveness gains. This paper also provides evidence that proper CASD evaluation efforts should allow enough time after implementation so that not only familiarity with the system has been established, but also most or all of the necessary organizational changes related to the new technology have been completed

Efficiency and Effectiveness Impacts of a Computer-Assisted Scheduling and Dispatching System Implementation

Computer-assisted scheduling and dispatch (CASD) systems have been implemented in many paratransit systems in the United States to improve the effectiveness and efficiency of operations. This paper contributes to the limited literature of studies documenting the impact of such systems on paratransit operations based on the implementation of such a system in a small city in Illinois. The analysis provides evidence of small but measurable efficiency and effectiveness gains. This paper also provides evidence that proper CASD evaluation efforts should allow enough time after implementation so that not only familiarity with the system has been established, but also most or all of the necessary organizational changes related to the new technology have been completed

Reset dynamics and latching in niobium superconducting nanowire single-photon detectors

We study the reset dynamics of niobium (Nb) superconducting nanowire single-photon detectors (SNSPDs) using experimental measurements and numerical simulations. The numerical simulations of the detection dynamics agree well with experimental measurements, using independently determined parameters in the simulations. We find that if the photon-induced hotspot cools too slowly, the device will latch into a dc resistive state. To avoid latching, the time for the hotspot to cool must be short compared to the inductive time constant that governs the resetting of the current in the device after hotspot formation. From simulations of the energy relaxation process, we find that the hotspot cooling time is determined primarily by the temperature-dependent electron-phonon inelastic time. Latching prevents reset and precludes subsequent photon detection. Fast resetting to the superconducting state is therefore essential, and we demonstrate experimentally how this is achieved

The Acute Physiological Response of Polar Bears to Helicopter Capture

Many wildlife species are live captured, sampled, and released; for polar bears (Ursus maritimus) capture often requires chemical immobilization via helicopter darting. Polar bears reduce their activity for approximately 4 days after capture, likely reflecting stress recovery. To better understand this stress, we quantified polar bear activity (via collar‐mounted accelerometers) and body temperature (via loggers in the body core [Tabd] and periphery [Tper]) during 2–6 months of natural behavior, and during helicopter recapture and immobilization. Recapture induced bouts of peak activity higher than those that occurred during natural behavior for 2 of 5 bears, greater peak Tper for 3 of 6 bears, and greater peak Tabd for 1 of 6 bears. High body temperature (\u3e39.0°C) occurred in Tper for 3 of 6 individuals during recapture and 6 of 6 individuals during natural behavior, and in Tabd for 2 of 6 individuals during recapture and 3 of 6 individuals during natural behavior. Measurements of Tabd and Tper correlated with rectal temperatures measured after immobilization, supporting the use of rectal temperatures for monitoring bear response to capture. Using a larger dataset (n = 66 captures), modeling of blood biochemistry revealed that maximum ambient temperature during recapture was associated with a stress leukogram (7–26% decline in percent lymphocytes, 12–21% increase in percent neutrophils) and maximum duration of helicopter operations had a similar but smaller effect. We conclude that polar bear activity and body temperature during helicopter capture are similar to that which occurs during the most intense events of natural behavior; high body temperature, especially in warm capture conditions, is a key concern; additional study of stress leukograms in polar bears is needed; and additional data collection regarding capture operations would be useful

Rapid impact of effective treatment on transmission of multidrug-resistant tuberculosis

BACKGROUND: Effective treatment for drug-susceptible tuberculosis (TB) rapidly renders patients noninfectious, long before conversion of sputum acid-fast smear or culture to negative. Multidrug-resistant TB (MDR-TB) patients on treatment are currently assumed to remain infectious for months. While the resources required for prolonged hospitalization are a barrier to the scale-up of MDR-TB treatment, the safety of community treatment is clear. OBJECTIVES : To estimate the impact of treatment on infectiousness among MDR-TB patients. METHODS: A series of five human-to-guinea pig TB transmission studies was conducted to test various interventions for infection control. Guinea pigs in adjacent chambers were exposed to exhaust air from a hospital ward occupied by mostly sputum smear- and culture-positive MDR-TB patients. The guinea pigs then underwent tuberculin skin testing for infection. Only the control groups of guinea pigs from each study (no interventions used) provide the data for this analysis. The number of guinea pigs infected in each study is reported and correlated with Mycobacterium tuberculosis drug susceptibility relative to treatment. RESULTS : Despite exposure to presumably infectious MDR-TB patients, infection percentages among guinea pigs ranged from 1% to 77% in the five experiments conducted. In one experiment in which guinea pigs were exposed to 27 MDR-TB patients newly started on effective treatment for 3 months, there was minimal transmission. In four other experiments with greater transmission, guinea pigs had been exposed to patients with unsuspected extensively drug-resistant tuberculosis who were not on effective treatment. CONCLUSIONS : In this model, effective treatment appears to render MDR-TB patients rapidly noninfectious. Further prospective studies on this subject are needed.NIOSH R01OH009050http://www.ingentaconnect.com/content/iuatld/ijtldhb201

The Deuteron Spin-dependent Structure Function g1d and its First Moment

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation matrix adde

Mercury DPM: fast, flexible particle simulations in complex geometries part II: applications

MercuryDPM is a particle-simulation software developed open-source by a global network of researchers. It was designed ​ab initio to simulate realistic geometries and materials, thus it contains several unique features not found in any other particle simulation software. These features have been discussed in a companion paper published in the DEM7 conference proceedings; here we present several challenging setups implemented in MercuryDPM ​ . Via these setups, we demonstrate the unique capability of the code to simulate and analyse highly complex geotechnical and industrial applications.These tups implemented include complex geometries such as (i) a screw conveyor, (ii) steady-state inflow conditions for chute flows, (iii) a confined conveyor belt to simulate a steady-state breaking wave, and(iii)aquasi-2D cylindrical slice to efficiently study shear flows.​MercuryDPM is also parallel, which we showcase via a multi-million particle simulations of a rotating drum. We further demonstrate how to simulate complex particle interactions, including: (i)deformable, charged clay particles; and (ii) liquid bridges and liquid migration in wet particulates, (iii) non-spherical particles implemented via superquadrics. Finally, we show how to analyse and complex systems using the unique micro-macro mapping (coarse-graining) tool MercuryCG

Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure

Measurement of the Spin Structure of the Deuteron in the DIS Region

We present a new measurement of the longitudinal spin asymmetry A_1^d and the spin-dependent structure function g_1^d of the deuteron in the range 1 GeV^2 < Q^2 < 100 GeV^2 and 0.004< x <0.7. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarised muon beam and a large polarised 6-LiD target. The results are in agreement with those from previous experiments and improve considerably the statistical accuracy in the region 0.004 < x < 0.03.Comment: 10 pages, 6 figures, subm. to PLB, revised: author list, Fig. 4, details adde