1,346 research outputs found
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New York Household Travel Patterns: A Comparison Analysis
In 1969, the U. S. Department of Transportation began collecting detailed data on personal travel to address various transportation planning issues. These issues range from assessing transportation investment programs to developing new technologies to alleviate congestion. This 1969 survey was the birth of the Nationwide Personal Transportation Survey (NPTS). The survey was conducted again in 1977, 1983, 1990 and 1995. Longer-distance travel was collected in 1977 and 1995. In 2001, the survey was renamed to the National Household Travel Survey (NHTS) and collected both daily and longer-distance trips in one survey. In addition to the number of sample households that the national NPTS/NHTS survey allotted to New York State (NYS), the state procured an additional sample of households in both the 1995 and 2001 surveys. In the 1995 survey, NYS procured an addition sample of more than 9,000 households, increasing the final NY NPTS sample size to a total of 11,004 households. Again in 2001, NYS procured 12,000 additional sample households, increasing the final New York NHTS sample size to a total of 13,423 households with usable data. These additional sample households allowed NYS to address transportation planning issues pertinent to geographic areas significantly smaller than for what the national NPTS and NHTS data are intended. Specifically, these larger sample sizes enable detailed analysis of twelve individual Metropolitan Planning Organizations (MPOs). Furthermore, they allowed NYS to address trends in travel behavior over time. In this report, travel data for the entire NYS were compared to those of the rest of the country with respect to personal travel behavior and key travel determinants. The influence of New York City (NYC) data on the comparisons of the state of New York to the rest of the country was also examined. Moreover, the analysis examined the relationship between population density and travel patterns, and the similarities and differences among New York MPOs. The 1995 and 2001 survey data make it possible to examine and identify travel trends over time. This report does not address, however, the causes of the differences and/or trends
Making the Traffic Operations Case for Congestion Pricing: Operational Impacts of Congestion Pricing
Congestion begins when an excess of vehicles on a segment of roadway at a given time, resulting in speeds that are significantly slower than normal or 'free flow' speeds. Congestion often means stop-and-go traffic. The transition occurs when vehicle density (the number of vehicles per mile in a lane) exceeds a critical level. Once traffic enters a state of congestion, recovery or time to return to a free-flow state is lengthy; and during the recovery process, delay continues to accumulate. The breakdown in speed and flow greatly impedes the efficient operation of the freeway system, resulting in economic, mobility, environmental and safety problems. Freeways are designed to function as access-controlled highways characterized by uninterrupted traffic flow so references to freeway performance relate primarily to the quality of traffic flow or traffic conditions as experienced by users of the freeway. The maximum flow or capacity of a freeway segment is reached while traffic is moving freely. As a result, freeways are most productive when they carry capacity flows at 60 mph, whereas lower speeds impose freeway delay, resulting in bottlenecks. Bottlenecks may be caused by physical disruptions, such as a reduced number of lanes, a change in grade, or an on-ramp with a short merge lane. This type of bottleneck occurs on a predictable or 'recurrent' basis at the same time of day and same day of week. Recurrent congestion totals 45% of congestion and is primarily from bottlenecks (40%) as well as inadequate signal timing (5%). Nonrecurring bottlenecks result from crashes, work zone disruptions, adverse weather conditions, and special events that create surges in demand and that account for over 55% of experienced congestion. Figure 1.1 shows that nonrecurring congestion is composed of traffic incidents (25%), severe weather (15%), work zones, (10%), and special events (5%). Between 1995 and 2005, the average percentage change in increased peak traveler delay, based on hours spent in traffic in a year, grew by 22% as the national average of hours spent in delay grew from 36 hours to 44 hours. Peak delay per traveler grew one-third in medium-size urban areas over the 10 year period. The traffic engineering community has developed an arsenal of integrated tools to mitigate the impacts of congestion on freeway throughput and performance, including pricing of capacity to manage demand for travel. Congestion pricing is a strategy which dynamically matches demand with available capacity. A congestion price is a user fee equal to the added cost imposed on other travelers as a result of the last traveler's entry into the highway network. The concept is based on the idea that motorists should pay for the additional congestion they create when entering a congested road. The concept calls for fees to vary according to the level of congestion with the price mechanism applied to make travelers more fully aware of the congestion externality they impose on other travelers and the system itself. The operational rationales for the institution of pricing strategies are to improve the efficiency of operations in a corridor and/or to better manage congestion. To this end, the objectives of this project were to: (1) Better understand and quantify the impacts of congestion pricing strategies on traffic operations through the study of actual projects, and (2) Better understand and quantify the impacts of congestion pricing strategies on traffic operations through the use of modeling and other analytical methods. Specifically, the project was to identify credible analytical procedures that FHWA can use to quantify the impacts of various congestion pricing strategies on traffic flow (throughput) and congestion
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Transferring 2001 National Household Travel Survey
Policy makers rely on transportation statistics, including data on personal travel behavior, to formulate strategic transportation policies, and to improve the safety and efficiency of the U.S. transportation system. Data on personal travel trends are needed to examine the reliability, efficiency, capacity, and flexibility of the Nation's transportation system to meet current demands and to accommodate future demand. These data are also needed to assess the feasibility and efficiency of alternative congestion-mitigating technologies (e.g., high-speed rail, magnetically levitated trains, and intelligent vehicle and highway systems); to evaluate the merits of alternative transportation investment programs; and to assess the energy-use and air-quality impacts of various policies. To address these data needs, the U.S. Department of Transportation (USDOT) initiated an effort in 1969 to collect detailed data on personal travel. The 1969 survey was the first Nationwide Personal Transportation Survey (NPTS). The survey was conducted again in 1977, 1983, 1990, 1995, and 2001. Data on daily travel were collected in 1969, 1977, 1983, 1990 and 1995. In 2001, the survey was renamed the National Household Travel Survey (NHTS) and it collected both daily and long-distance trips. The 2001 survey was sponsored by three USDOT agencies: Federal Highway Administration (FHWA), Bureau of Transportation Statistics (BTS), and National Highway Traffic Safety Administration (NHTSA). The primary objective of the survey was to collect trip-based data on the nature and characteristics of personal travel so that the relationships between the characteristics of personal travel and the demographics of the traveler can be established. Commercial and institutional travel were not part of the survey. Due to the survey's design, data in the NHTS survey series were not recommended for estimating travel statistics for categories smaller than the combination of Census division (e.g., New England, Middle Atlantic, and Pacific), MSA size, and the availability of rail. Extrapolating NHTS data within small geographic areas could risk developing and subsequently using unreliable estimates. For example, if a planning agency in City X of State Y estimates travel rates and other travel characteristics based on survey data collected from NHTS sample households that were located in City X of State Y, then the agency could risk developing and using unreliable estimates for their planning process. Typically, this limitation significantly increases as the size of an area decreases. That said, the NHTS contains a wealth of information that could allow statistical inferences about small geographic areas, with a pre-determined level of statistical certainty. The question then becomes whether a method can be developed that integrates the NHTS data and other data to estimate key travel characteristics for small geographic areas such as Census tract and transportation analysis zone, and whether this method can outperform other, competing methods
Superconductivity in Fluorine-Arsenide Sr_{1-x}La_xFeAsF
Since the discovery of superconductivity\cite{1} at 26 K in oxy-pnictide
, enormous interests have been stimulated in the fields of
condensed matter physics and material sciences. Among the five different
structures in this broad type of superconductors\cite{2,3,4,5,6}, the ZrCuSiAs
structure has received special attention since the has been quickly
promoted to 55-56 K\cite{7,8,9,10,11} in fluorine doped oxy-pnictides REFeAsO
(RE = rare earth elements). The superconductivity can also be induced by
applying a high pressure to the undoped samples\cite{12,13}. The mechanism of
superconductivity in the FeAs-based system remains unclear yet, but it turns
out to be clear that any change to the structure or the building blocks will
lead to a change of the superconducting transition temperatures. In this
Letter, we report the fabrication of the new family of compounds, namely
fluorine-arsenides DvFeAsF (Dv = divalent metals) with the ZrCuSiAs structure
and with the new building block DvF instead of the REO (both the layers DvF and
REO have the combined cation state of "+1"). The undoped parent phase has a
Spin-Density-Wave like transition at about 173 K for SrFeAsF, 118 K for CaFeAsF
and 153 K for EuFeAsF. By doping electrons into the system the resistivity
anomaly associated with this SDW transition is suppressed and superconductivity
appears at 32 K in the fluorine-arsenide SrLaFeAsF (x = 0.4). Our
discovery here initiates a new method to obtain superconductors in the
FeAs-based system.Comment: 11 pages, 4 figures, typos added, references added, and one figure
adde
Detecting Mutations in the Mycobacterium tuberculosis Pyrazinamidase Gene pncA to Improve Infection Control and Decrease Drug Resistance Rates in Human Immunodeficiency Virus Coinfection.
Hospital infection control measures are crucial to tuberculosis (TB) control strategies within settings caring for human immunodeficiency virus (HIV)-positive patients, as these patients are at heightened risk of developing TB. Pyrazinamide (PZA) is a potent drug that effectively sterilizes persistent Mycobacterium tuberculosis bacilli. However, PZA resistance associated with mutations in the nicotinamidase/pyrazinamidase coding gene, pncA, is increasing. A total of 794 patient isolates obtained from four sites in Lima, Peru, underwent spoligotyping and drug resistance testing. In one of these sites, the HIV unit of Hospital Dos de Mayo (HDM), an isolation ward for HIV/TB coinfected patients opened during the study as an infection control intervention: circulating genotypes and drug resistance pre- and postintervention were compared. All other sites cared for HIV-negative outpatients: genotypes and drug resistance rates from these sites were compared with those from HDM. HDM patients showed high concordance between multidrug resistance, PZA resistance according to the Wayne method, the two most common genotypes (spoligotype international type [SIT] 42 of the Latino American-Mediterranean (LAM)-9 clade and SIT 53 of the T1 clade), and the two most common pncA mutations (G145A and A403C). These associations were absent among community isolates. The infection control intervention was associated with 58-92% reductions in TB caused by SIT 42 or SIT 53 genotypes (odds ratio [OR] = 0.420, P = 0.003); multidrug-resistant TB (OR = 0.349, P < 0.001); and PZA-resistant TB (OR = 0.076, P < 0.001). In conclusion, pncA mutation typing, with resistance testing and spoligotyping, was useful in identifying a nosocomial TB outbreak and demonstrating its resolution after implementation of infection control measures
The usefulness of the electronic patient visit assessment (ePVA) as a clinical support tool for real-time interventions in head and neck cancer
Background: Patients with head and neck cancer (HNC) experience painful, debilitating symptoms and functional limitations that can interrupt cancer treatment, and decrease their health-related quality of life (HRQoL). The Electronic Patient Visit Assessment (ePVA) for head and neck is a web-based mHealth patient-reported measure that asks questions about 21 categories of symptoms and functional limitations common to HNC. This article presents the development and usefulness of the ePVA as a clinical support tool for real-time interventions for patient-reported symptoms and functional limitations in HNC. Methods: Between January 2018 and August 2019, 75 participants were enrolled in a clinical usefulness study of the ePVA. Upon signing informed consent, participants completed the ePVA and the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ) general (C30) questionnaire v3.0 (scores range from 0 to 100 with 100 representing best HRQoL). Clinical usefulness of the ePVA was defined as demonstration of reliability, convergent validity with HRQoL, and acceptability of the ePVA (i.e., >70% of eligible participants complete the ePVA at two or more visits and >70% of ePVA reports are read by providers). Formal focus group discussions with the interdisciplinary teamthat cared for patients with HNC guided the development of the ePVA as a clinical support tool. Qualitative and quantitative methods were used throughout the study. Descriptive statistics consisting of means and frequencies, Pearson correlation coefficient, and Student’s t-tests were calculated using SAS 9.4 and STATA. Results: The participants were primarily male (71%), White (76%), diagnosed with oropharyngeal or oralcavity cancers (53%), and undergoing treatment for HNC (69%). Data analyses supported the reliability (alpha =0.85), convergent validity with HRQoL scores, and acceptability of the ePVA. Participants with the highest number of symptoms and functional limitations reported significantly worse HRQoL (sumof symptoms: r=–0.50, P<0.0001; sum of function limitations: r=–0.56, P<0.0001). Ninety-two percent of participants (59 of 64) who had follow-up visits within the 6-month study period completed the ePVA at twoor more visits and providers read 89% (169 of 189) of automated ePVA reports. The use of the ePVA as aclinical support tool for real-time interventions for symptoms and functional limitations reported by patients is described in a clinical exemplar. Conclusions: This research indicates that the ePVA may be a useful mHealth tool as a clinical support tool for real-time interventions for patient-reported symptoms and functional limitations in HNC. The study findings support future translational research to enhance the usefulness of the ePVA in real world settings for early interventions that decrease symptom burden and improve the QoL of patients with HNC
Septin filaments exhibit a dynamic, paired organization that is conserved from yeast to mammals
© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Journal of Cell Biology 193 (2011): 1065-1081, doi:10.1083/jcb.201012143.The septins are conserved, GTP-binding proteins important for cytokinesis, membrane compartmentalization, and exocytosis. However, it is unknown how septins are arranged within higher-order structures in cells. To determine the organization of septins in live cells, we developed a polarized fluorescence microscopy system to monitor the orientation of GFP dipole moments with high spatial and temporal resolution. When GFP was fused to septins, the arrangement of GFP dipoles reflected the underlying septin organization. We demonstrated in a filamentous fungus, a budding yeast, and a mammalian epithelial cell line that septin proteins were organized in an identical highly ordered fashion. Fluorescence anisotropy measurements indicated that septin filaments organized into pairs within live cells, just as has been observed in vitro. Additional support for the formation of pairs came from the observation of paired filaments at the cortex of cells using electron microscopy. Furthermore, we found that highly ordered septin structures exchanged subunits and rapidly rearranged. We conclude that septins assemble into dynamic, paired filaments in vivo and that this organization is conserved from yeast to mammals.This work was supported by the National Science Foundation under
grant No. MCB-0719126 to A.S. Gladfelter, the National Institute of Biomedical
Imaging and Bioengineering under grant No. EB002583 to R. Oldenbourg,
a Drexel CURE grant from the State of Pennsylvania Tobacco Settlement Fund,
and National Institute of Neurological Disorders and Stroke grant NS48090-
06A to E.T. Spiliotis
Stratospheric AOD after the 2011 eruption of Nabro volcano measured by lidars over the Northern Hemisphere
International audienceNabro volcano (13.37°N, 41.70°E) in Eritrea erupted on 13 June 2011 generating a layer of sulfate aerosols that persisted in the stratosphere for months. For the first time we report on ground-based lidar observations of the same event from every continent in the Northern Hemisphere, taking advantage of the synergy between global lidar networks such as EARLINET, MPLNET and NDACC with independent lidar groups and satellite CALIPSO to track the evolution of the stratospheric aerosol layer in various parts of the globe. The globally averaged aerosol optical depth (AOD) due to the stratospheric volcanic aerosol layers was of the order of 0.018 ± 0.009 at 532 nm, ranging from 0.003 to 0.04. Compared to the total column AOD from the available collocated AERONET stations, the stratospheric contribution varied from 2% to 23% at 532 nm
Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton
© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Cell Biology 213 (2016): 23-32, doi: 10.1083/jcb.201512029.Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape.This work was supported by grants from the National Science Foundation (MCB-507511 to A.S. Gladfelter) and the National Institutes of Health (NIGMS-T32GM008704 to A.A. Bridges)
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