The evaluation of redundancy for road traffic networks.

This paper presents two redundancy indices for road traffic network junctions and also an aggregated network redundancy index. The proposed redundancy indices could be implemented to identify optimal design alternatives during the planning stage of the network junctions whereas the aggregated network redundancy index could assess the best control and management policies under disruptive events. Furthermore, effective measures of network redundancy are important to policy makers in understanding the current resilience and future planning to mitigate the impacts of greenhouse gases. The proposed junction indices cover the static aspect of redundancy, i.e. alternative paths, and the dynamic feature of redundancy reflected by the availability of spare capacity under different network loading and service level. The proposed redundancy indices are based on the entropy concept, due to its ability to measure the system configuration in addition to being able to model the inherent uncertainty in road transport network conditions. Various system parameters based on different combinations of link flow, relative link spare capacity and relative link speed were examined. However, the two redundancy indices developed from the combined relative link speed and relative link spare capacity showed strong correlation with junction delay and volume capacity ratio of a synthetic road transport network of Delft city. Furthermore, the developed redundancy indices responded well to demand variation under the same network conditions and supply variations. Another case study on Junction 3A in M42 motorway near Birmingham demonstrated that the developed redundancy index is able to reflect the impact of the Active Traffic Management scheme introduced in 2006

Recognition of delirium in ICU patients: a diagnostic study of the NEECHAM confusion scale in ICU patients

BACKGROUND: A delirium, is a serious, high-frequency complication in intensive care unit (ICU) patients. The consequences of this complication range from high morbidity and mortality to greater need for nursing care. Despite these, delirium is often not recognized and there for not treated. In this study a nursing screening instrument, the NEECHAM confusion scale, was studied for early recognition of delirium ICU patients. This scale proved valid and reliable in several studies in the general hospital population. METHODS: In this study validity and reliability were tested in a prospective cohort of 105 patients. Gold standard for delirium was an independent DSM-IV diagnosis. User friendliness was tested by structured evaluation of nurses' experiences working with the scale. RESULTS: The NEECHAM confusion scale showed high internal consistency (Cronbach's alpha 0.88) and an interrater reliability of Cohen's Kappa 0.60. The concurrent validity with the DSM-IVcriteria showed a strong link (chi-square 67.52, p [less than or equal to] 0.001). Sensitivity was high, 97% and specificity was good 83%. ICU nurses completed the NEECHAM confusion rating in 3.69, ± 1.21 minutes average. In general the nurses were positive about the NEECHAM confusion scale. They were able to collect data during regular care, but experienced problems in rating the scale in intubated patients. The items in themselves were clear, the content validity, measured by the language used was rated good. CONCLUSION: The psychometric characteristics of the NEECHAM confusion scale of this ICU study are generally consistent with validity research previously reported for the general hospital population. The psychometric characteristics and the ease of use of the NEECHAM confusion scale enables ICU nurses to early recognize delirium. Further study, especially in intubed patients is recommended

Occurrence of delirium is severely underestimated in the ICU during daily care

Delirium is associated with prolonged intensive care unit (ICU) stay and higher mortality. Therefore, the recognition of delirium is important. We investigated whether intensivists and ICU nurses could clinically identify the presence of delirium in ICU patients during daily care. All ICU patients in a 3-month period who stayed for more than 48 h were screened daily for delirium by attending intensivists and ICU nurses. Patients were screened independently for delirium by a trained group of ICU nurses who were not involved in the daily care of the patients under study. The Confusion Assessment Method for the ICU (CAM-ICU) was used as a validated screening instrument for delirium. Values are expressed as median and interquartile range (IQR; P25-P75). During the study period, 46 patients (30 male, 16 female), median age 73 years (IQR = 64-80), with an ICU stay of 6 days (range 4-11) were evaluated. CAM-ICU scores were obtained during 425 patient days. Considering the CAM-ICU as the reference standard, delirium occurred in 50% of the patients with a duration of 3 days (range 1-9). Days with delirium were poorly recognized by doctors (sensitivity 28.0%; specificity 100%) and ICU nurses (sensitivity 34.8%; specificity 98.3%). Recognition did not differ between hypoactive or active status of the patients involved. Delirium is severely under recognized in the ICU by intensivists and ICU nurses in daily care. More attention should be paid to the implementation of a validated delirium-screening instrument during daily ICU car

The application of intelligent agents in dynamic traffic management

Increasingly traffic management measures exhibit dynamic features, taking into account dynamics in the traffic demand pattern or transport system supply pattern. Some examples are demand actuated traffic signal settings or variable message signs. In most cases these measures function as stand alone systems. This means that there is no or hardly any co-ordination between the various measures. This lack of co-ordination could make the application of dynamic traffic management measures less effective: e.g. the measures could serve opposite objectives or even generate a negative impact on traffic flows that are not in any way related to the problem. Consequently the uncoordinated application of dynamic traffic management measures can be very counter-productive. To avoid these setbacks it will be necessary to be able to control the traffic in two ways: in a detailed way by focusing on the problem(s) that need(s) to be solved (distributed control), and in a more generic way by controlling the overall traffic performance in the network (generic control)

Multi-agent dynamic traffic management for safeguarding traffic throughput and/or environmental and safety qualities

Increasingly traffic management measures exhibit dynamic features, thus taking into account dynamics in the traffic demand pattern or transport system supply pattern. Some examples are demand actuated traffic signal settings or variable message signs. In most cases these measures are functioning as stand alone systems. This means that there is no or hardly any coordination between the various measures. This lack of coordination could make the application of dynamic traffic management measures less effective: e.g. the measures could serve opposite objectives or even generate a negative impact on traffic flows that are not in any way related to the problem. Consequently the un-coordinated application of dynamic traffic management measures can be very counter-productive. To avoid these setbacks it will be necessary to be able to control the traffic in two ways: in a detailed way by focusing on the problem(s) that need(s) to be solved (distributed control), and in a more generic way by controlling the overall traffic performance in the network (generic control)

An analysis of the role of sulfate in the embryonic differentiation of the sea urchin (Paracentrotus lividus)

Volume: 71Start Page: 21End Page: 5

Nietsdoen is geen optie: Methodes voor het bepalen van de robuustheid van wegennetwerken

Verkeersnetwerken in verstedelijkte gebieden zijn kwetsbaar voor onvoorspelbare gebeurtenissen zoals incidenten. Het komt nu bijvoorbeeld al regelmatig voor dat een klein incident tot file op meerdere wegen leidt en dat het uren duurt voordat deze file weer is opgelost. In de nabije toekomst zal naar verwachting de gemiddelde impact van incidenten groter worden, omdat de belasting op de weg groter wordt en daardoor de reservecapaciteit in het netwerk per tijdstap en over de tijd afneemt. Niets doen is dus geen optie. Verschillende maatregelen kunnen genomen worden om de robuustheid van het wegennetwerk te vergroten. Om het effect van deze maatregelen in te kunnen schatten is het van belang om robuustheid te kunnen kwantificeren. In dit paper is daarom een overzicht gegeven van verschillende in Nederland gebruikte definities, indicatoren en meetmethodes voor robuustheid. Uit het overzicht blijkt dat er nog geen eenduidige beslissing is genomen over welke definities, indicatoren en meetmethodes het best gebruikt kunnen worden. Het is zelfs de vraag of een keuze gemaakt kan worden tussen alle indicatoren, omdat ze immers allemaal een ander aspect van robuustheid laten zien. In praktijk zal echter toch altijd gekozen moeten worden. Bij de keuze van indicatoren en methodes is het van belang dat zoveel mogelijk aspecten van robuustheid beschouwd worden. Fileterugslag en alternatieve routes zijn de twee belangrijkste aspecten hiervan. Bij voorkeur moeten de indicatoren en methodes rekening kunnen houden met de ontwikkeling van files over de tijd in de situatie met en zonder verstoring. De mate van file en de locatie van de file zijn hierbij van belang. Dit betekent dat de te gebruiken methode met fileterugslag rekening moet kunnen houden. De aanwezigheid en het gebruik van alternatieve routes zijn het tweede belangrijke aspect. Tot op heden is het echter heel lastig om dit goed te modelleren, omdat weinig bekend is over het gebruik van alternatieve routes bij verstoringen. Het is daarom aan te bevelen om meerdere vormen van routekeuze toe te passen, om een zo goed mogelijk beeld te krijgen van de range waarin de resultaten kunnen liggen. In de toekomst zullen de methodes voor het kwantificeren van robuustheid verder uitgewerkt moeten worden om goed onderbouwde beslissingen te kunnen nemen over de te nemen maatregelen om de robuustheid van het wegennetwerk te vergroten.Transport & PlanningCivil Engineering and Geoscience