Occupancies and flows were jointly sampled from numerous freeway segments in nearly stationary, unqueued traffic. The data from one segment were typically averaged across all lanes there and plotted. ...Each plot was compared with one sampled at a neighboring freeway segment, with the two segments differing only in their number of travel lanes. Such comparisons were repeated for a total of five pairs of segments on five freeways in and near Toronto, Canada and in California. All occupancy-flow relations were piece-wise linear in form for average flows up to about 2,000 vehicles per hour per lane. Only when traffic became moderately dense did average vehicle speeds diminish with increasing occupancies. The occupancy above which these speed diminutions occurred was the same for both segments in a pair. Notable, however, the average vehicle speed corresponding to a given occupancy was always higher on the segment with the larger number of lanes. The driver psychology that can explain some of these findings is discussed. Findings are also contrasted with information currently provided in traffic handbooks.
Summary form only given. Asymmetric multiple-quantum-well (AMQW) InGaAsP lasers have been designed and fabricated which exhibit broad gain profiles and a significantly increased tuning range due to ...equal contributions to the gain from the various QWs in the active region. The device structure is a Fabry-Perot (FP) ridge waveguide with 3 /spl mu/m ridge width, and no facet coatings. The active region consists of two 50 /spl Aring/ and two 100 /spl Aring/ QWs separated by 30 /spl Aring/ barriers. A diffractive optical element (DOE) was used in an external cavity to tune the output wavelength of the AMQW lasers. The DOE was designed to replace the combination of a grating and lens in the Littrow configuration and is a reflective Fresnel phase element which provides a strong wavelength dependent focal length. This tunable laser system was used experimentally as a broadband absorption spectrometer. Sensitive detection of trace-gas spectra was performed.
Five bioassays were used to measure toxicity during bioremediation of a soil contaminated with pentachlorophenol (PCP; 335 ppm), polycyclic aromatic hydrocarbons (PAHs; 1225 ppm) and petroleum ...hydrocarbons (19 125 ppm). Different bioremediation treatments were tested in soil microcosms including amendment with phosphorus and/or PCP-degrading Pseudomonas sp. UG30, either as free cells or encapsulated in -carrageenan. Soil toxicity was monitored using the solid-phase Microtox test, SOS-chromotest, lettuce seed germination, earthworm survival and sheep red blood cell (RBC) haemolysis assays. PCP levels were reduced in all treatments after 210 days. The RBC lysis assay, Microtox test and SOS-chromotest indicated reduced toxicity in most of the microcosms by day 210. Trends depicted by lettuce seed germination and earthworm survival LC50 values varied with each treatment. For example, in soil amended with phosphorus, both the seed germination and earthworm survival LC50 data suggested increased soil toxicity. However, for soil treated with encapsulated Pseudomonas sp. UG30 cells, the earthworm survival LC50 data indicated reduced toxicity while seed germination LC50 values showed little change from values obtained prior to bioremediation. Our results show that toxicity trends in a contaminated soil during bioremediation differ according to the assay used.
This paper develops a model of the factors that effect an employee's choice to keep coverage under two health insurance plans or opt for coverage under one plan and use the benefit dollars for ...additional benefits. The results of the decision process underlying the analysis in this paper are similar to those needed to consider a list of benefits such as in a cafeteria benefit plan. While the overall model was significant, the variables representing education and those currently covered by two health insurance plans were the only significant variables.
Brachial plexus neuropathy Hubka, Michael J; King, Laurie; Cassidy, J David ...
Journal of the Canadian Chiropractic Association,
12/1992, Letnik:
36, Številka:
4
Journal Article
Recenzirano
Branchial plexus neuropathy is characterized by acute onset of intense pain in the shoulder or arm followed shortly by focal muscle weakness. This presentation may mislead the clinician into ...diagnosing shoulder or cervical spine pathology. Although brachial plexus neuropathy is not common, it should be considered in the differential diagnosis of pain and weakness of the arm. We present a patient with brachial plexus neuropathy who was originally misdiagnosed as having a cervical disc herniation.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
An earlier empirical study of San Francisco Bay Area freeways concluded that HOV lanes unfavorably affect freeway traffic by creating congestion. That study attributed the observed congestion to HOV ...lanes and tentatively recommended their elimination over the full lengths of the freeways it examined; and even from all Bay Area freeways. It recognized, however, that its analysis is fragmentary and recommended further work to solidify its conclusions. This is logical since the study lacks a spatiotemporal analysis to pinpoint where and how congestion first forms (at bottlenecks). The present report re-examines the same set of freeway sites in spatiotemporal detail to understand more deeply how HOV lanes are affecting traffic. It enriches the data from the original study with data from neighboring detector stations, to identify: first the locations (bottlenecks) where queues are triggered; and second the role that HOV lanes play in this phenomenon. This study includes an even more detailed analysis of high-resolution video data from a bottleneck where the HOV lane initially seemed to be having an unfavorable effect. To our surprise, we found no compelling evidence that the HOV lanes were triggering delays and queues on the freeway sites in the earlier study. In all cases queues formed first at bottlenecks and, save for one questionable case, formed for reasons unrelated to the HOV lanes. This was true even on additional days that we studied. Moreover, data did not conclusively show that HOV lanes were reducing bottleneck flows or prolonging the queues; no adverse effects could be confirmed. To the contrary, and quite remarkably, the HOV lane seemed to increase the capacity of the bottleneck that was videotaped, even though that lane was underutilized. (The video data show that higher than normal discharge flows arose in the remaining lanes when the HOV lane was underutilized âeuro" enough even to compensate for that laneâeuro(TM)s underutilization. Reassuringly, this effect had been predicted in earlier simulations.) Although the sites assessed in this and the original study may not contain bottlenecks where the HOV lane is contributing to problems, the present study recognizes that such bottlenecks exist. They are just less prevalent than originally suspected. Fortunately for society, an HOV lane can be useful in most of these cases: theory and simulations indicate that if an HOV lane is rescinded near a problematic bottleneck but is preserved on the entire queued freeway stretch upstream, the lane will neither affect the bottleneckâeuro(TM)s discharge flow nor the delay to vehicles that pass through the bottleneck. For typical freeways with four or more lanes, delay to all vehicles would change little. The HOV lane would allow HOVs to bypass most of the congestion without significantly increasing total vehicle-hours of travel. This means that even in problematic cases, HOV lanes can usually be preserved and allowed to perform their intended societal function: reducing people-hours of travel without significantly increasing vehicle-hours of travel by favoring HOVs where freeway queues arise. To avoid increased vehicle delays, however, and perhaps even to increase bottleneck capacities, some HOV-lane installations should be modestly altered near bottlenecks. This report also describes field studies necessary to determine where and how such alterations should be deployed.
A macroscopic modeling approach is proposed for allocating a city’s road space among competing transport modes. In this approach, a city or neighborhood street network is viewed as a reservoir with ...aggregated traffic. Taking the number of vehicles (accumulation) in a reservoir as input, we show how one can reliably predict system performance in terms of person and vehicle hours spent in the system and person and vehicle kilometers traveled. The approach is used here to unveil two important results: first, that restricting access to a city’s congested areas can improve mobility for all travelers; and second, that dedicating street space to more sustainable modes like buses can improve accessibility for all modes, even if space is taken from cars. In this way, we show that this reservoir approach can determine the level of accessibility that can be sustained by a city of given structure, and can furnish insights into how city space should be allocated between various modes to improve accessibility for all travelers. We end the paper by discussing the value of expanding the approach so that neighborhood street networks can be modeled using systems of multiple, multimodal reservoirs.
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