L'hydrologie urbaine: nouvelles problématiques, nouvelles approches de solutions

La pratique de l'hydrologie, appliquée au milieu urbain, a beaucoup évolué depuis les années 1960. De nouveaux outils scientifiques, méthodologiques et technologiques ont été mis au point. En ce qui concerne les eaux pluviales urbaines, un changement de philosophie complet s'est produit. Aujourd'hui, des développements rapides continuent à se produire pour faire face de la meilleure manière possible aux graves problèmes qui se posent en zone urbaine : inondation et pollution du milieu naturel. Deux approches récentes illustrent ces développements : la gestion des risques et l'approche globale sur le bassin versant. Une évaluation de plus en plus précise de l'aléa et de la vulnérabilité s'avère nécessaire ainsi qu'une planification hydrologique bassin versant par bassin versant. Celle-ci devrait conduire à définir et à hiérarchiser les principaux objectifs que l'on se fixe dans les domaines du contrôle des inondations, du contrôle de l'érosion, de l'amélioration du milieu naturel et de la protection de l'environnement. Les actions à mener doivent utiliser les outils de modélisation des phénomènes hydrologiques sur les bassins versants. L'efficacité de ces approches est illustrée par un exemple pris sur le bassin versant de la rivière Beauport au Québec.Urban hydrology practice has evolved a great deal, keeping up with the evolution of urban problems. Thus, professional engineers have had to keep up with this evolution, in order to understand the effects of urbanization on the hydrological behavior of the systems for which they have to recommend best solutions. Engineers have also had to evolve from the traditional approach of a limited vision of the problem, of its extent and of its impacts on the system. A global vision of the entire system, grouping every watershed element, such as forestry, agriculture or urbanization, is necessary if one is to circumscribe the problem, to analyze it and to reach to the best long-lasting solution. This article represents a synthesis of the hydrological disturbance phenomenon caused by uncontrolled urbanization, not properly planned, which is often characterized by numerous short-term solutions, often ineffective in the context of a long-lasting approach.Examples of natural disasters caused by meteorological events are more and more frequent. Take the case of Vaison-la-Romaine, in September 1992, where the Groseau devastated the Vaison community. More recently, the 1996 summer floods in the Saguenay region, in Québec, demonstrate once more that water always tends to return to its original bed, now occupied by artificial structures. When these types of events are analyzed in detail, we notice that meteorological phenomena are not always the main cause of the disaster cause and that often part of the responsibility lies with the occurrence of human activity in the catchment. This observation shows the importance of using wisdom and humility towards these natural forces and of anticipating, during design, a "secure" passage for the inevitable flows that one day will exceed the structure capacity. Knowing all the interactions that exist in the heart of the stormwater management problems, it is risky to intervene in isolation without analyzing the impact of the action. The approach must then be global and coherent; the tool necessary for success is the stormwater master plan made on a watershed basis. The master plan allows us to properly describe the problematical elements, to identify the real causes and to optimize the location of the control solutions. It also allows us to manage the increase in stormwater due to urbanization, with the "flow set point" concept of each watercourse tributary.This article presents an application example where the global analysis approach is used and where the solution involves different interventions and developments, which, when combined, effectively treat backwater effects, flooding and erosion in the presented area. The master plan of the watershed containing this sector had already been conceived and the specific flows of each of its tributaries had been identified; the global approach method therefore allowed us to settle the local problems in the studied area while respecting the flow granted by the master plan. Finally, a floodable plain, containing marshes, completes the intervention plan by combining the restoration of certain watercourse ecological characteristics with the need for flood control. This example demonstrates the necessity and the advantages of approaching urban drainage problems at the watershed level. However, watershed management concepts lead planners and designers to deal with antagonisms: urbanization or renaturalization? Obviously, in urban areas, the return to natural conditions is impossible and the disturbances to watercourses generated by urbanization cannot all be compensated for. Rather, we must aspire to the establishment of a balanced environment by controlling inflows produced by the watershed and by supporting the system to receive them. The notion of feasibility must always occupy the thoughts of the master plan designers and planners. The credibility and the continuity of the master plan depend on all these considerations; any unrealistic flow order, on an implementation level, can compromise the balance of the management plan and its applicability, which in turn can lead to a confused plan, possibly having disastrous consequences. The ultimate consequence of the management plan is the protection of the watercourse, the development of which can be designed to meet different criteria, such as flood control, erosion control, ecological potential enhancement, etc. It is at this stage that management becomes most complex: flood control, for example, does not apply to the same type of events as erosion control. The former requires management of major hydrological events, whereas the second needs implies control of frequent flows, which are at the origin of bank undermining caused by differential volume excesses. The management scheme must then handle multiple events and multiple criteria; consequently, it becomes more complex but also grows in value and justifies itself more adequately. Furthermore, the whole question of watercourse quality, in the broad sense of the term, must be managed from a frequent-event point of view, as this yields the best physical, ecological and aesthetic image of the aquatic environment. To this effect, present efforts in the control of combined sewage network overflows can be seen as a predecessor of what will later be extended to the entire stormwater network. This whole aspect of management has not been treated in this paper, as many others are dedicated to doing so. The evolution of the situation is similar in France and in Québec; coherent watershed management must rest on clear political goals regarding environmental use, risk protection and urban development. The stormwater master plan must, permanently, become part of the water resource master plan for the whole watershed, with its objectives of flood control, erosion control and maintenance of acceptable physical-chemical and biochemical water quality, as well as assured resource use (drinking water--, hydroelectricity, agriculture, industrial waters, etc.). This water resource master plan will have to be integrated in the same way as the French Water Agencies do today, and as Québec is preparing to do so

Cost and Utilization of Behavioral Health Medications Associated with Rescission of an Exemption for Prior Authorization for Severe and Persistent Mental Illness in the Vermont Medicaid Program

BACKGROUND: In recent years, many state Medicaid programs have implemented preferred drug lists (PDL) to control pharmaceutical costs by generating supplemental rebate revenues and directing providers to the most cost-effective treatments. Two states, Michigan and Vermont, sought approval from the Centers for Medicare and Medicaid Services for supplemental rebates for their Medicaid fee-for-service programs in 2002. Behavioral health medications were largely excluded from PDLs and other managed care initiatives implemented by state Medicaid programs because of significant opposition to any impact on this vulnerable population. In November 2001, the Vermont Medicaid program implemented the Vermont Health Access Pharmacy Benefit Management Program, a PDL designed to promote cost-effective use of medications. Despite the potential cost savings resulting from implementation of a PDL, behavioral health providers and advocates in the state of Vermont opposed the implementation of the managed care initiative for beneficiaries with severe mental illness, and after January of 2002, Vermont\u27s program was changed to exempt beneficiaries meeting the severe and persistent mental illness (SPMI) criteria from prior authorization (PA) for behavioral health medications not on the Medicaid PDL. The SPMI exemption was phased out by June 30, 2006. OBJECTIVES: To determine the effects of the rescission of the PA exemption on utilization and costs of 3 classes of behavioral health medications (antidepressants, antipsychotics, and anxiolytics/sedatives). Secondary analyses were conducted to assess the association between rescission of the PA exemption and 2 quality measures that might be associated with pharmacy management policy: (a) behavioral health hospitalizations and (b) high-dose prescribing of antipsychotics, defined as dosing that exceeded the manufacturer-recommended maximum dose by 25%. METHODS: This was a retrospective analysis of pharmacy claims for beneficiaries of the Office of Vermont Health Access Medicaid Program for dates of service from July 1, 2005, through December 31, 2007. The 12-month PA exemption period for 3 categories of drugs (antidepressants, antipsychotics, and anxiolytics/sedatives) was July 1, 2005, through June 30, 2006; and the post-PA exemption period was the 12 months from January 1, 2007, through December 31, 2007, following rescission of the SPMI exemption. Costs in this analysis were defined as the amount paid by Medicaid, excluding federal drug rebates paid by drug manufacturers and supplemental rebates associated with the PDL program. Costs were adjusted for inflation using the Consumer Price Index for medical costs. Frequencies were used to identify trends between medication classes and time periods. Medical claims from the 2 time periods were used to assess inpatient hospitalization trends. Descriptive statistics, Pearson chi-square tests (for categorical data), and t-tests (for continuous data) were used to assess the 2 study cohorts. RESULTS: 17.8% (n=22,130) of 124,169 eligible beneficiaries in the PA exemption period had 1 or more pharmacy claims in the 3 classes of medications exempt from PA versus 19.2% (n=23,717) of 123,499 eligible beneficiaries in the post-PA exemption period. Utilization of behavioral medications per member per month (PMPM) increased by 14.3% from 0.14 claims PMPM in the PA exemption period to 0.16 claims PMPM in the post-PA exemption period, similar to the 14.1% increase in the utilization of nonbehavioral medications (from 0.64 to 0.73 claims PMPM). Utilization changed little between the PA exemption period and the post-PA exemption period for the 3 individual classes of behavioral health drugs, 0.08 claims PMPM versus 0.09 claims PMPM for antidepressants and 0.03 for both study periods for both antipsychotics and anxiolytics/sedative hypnotics. PMPM costs for the 3 drug classes exempt from PA increased by 2.1% from $12.76 to$13.03, compared with a 12.2% increase from $42.58 PMPM to$47.79 PMPM for nonbehavioral health medications. The small 2.1% increase in PMPM costs for the 3 formerly PA-exempt drug classes was attributable in part to a 12.9% reduction in average cost per pharmacy claim, from $94.05 to$81.92, including a 24.8% reduction in the average cost per antidepressant claim, from $65.59 to$49.33. For the subgroup of beneficiaries taking atypical antipsychotic medications, the percentage with high-dose prescriptions decreased from 3.1% to 2.2%. Mental health inpatient hospitalizations also decreased from 0.6% of beneficiaries in the PA exemption period to 0.4% in the post-PA exemption period. CONCLUSIONS: In a Medicaid population excluding Medicare dual-eligible beneficiaries, the rescission of a PA exemption for 3 major classes of behavioral health medications in a PDL was not associated with decreased utilization of formerly PA-exempt behavioral health medications. The increase in PMPM spending for the formerly PA-exempt behavioral health medications was small compared with the increase in PMPM cost for nonbehavioral health medications, and there were fewer beneficiaries with hospitalization for mental health reasons in the period after rescission of the PA exemption

Is there any relationship between the exposure to mycophenolic acid and the clinical status in children with lupus?

International audienc

Large-Scale Integration of Nanoelectromechanical Systems for Gas Sensing Applications

We have developed arrays of nanomechanical systems (NEMS) by large-scale integration, comprising thousands of individual nanoresonators with densities of up to 6 million NEMS per square centimeter. The individual NEMS devices are electrically coupled using a combined series-parallel configuration that is extremely robust with respect to lithographical defects and mechanical or electrostatic-discharge damage. Given the large number of connected nanoresonators, the arrays are able to handle extremely high input powers (>1 W per array, corresponding to <1 mW per nanoresonator) without excessive heating or deterioration of resonance response. We demonstrate the utility of integrated NEMS arrays as high-performance chemical vapor sensors, detecting a part-per-billion concentration of a chemical warfare simulant within only a 2 s exposure period

Piezoelectric nanoelectromechanical resonators based on aluminum nitride thin films

We demonstrate piezoelectrically actuated, electrically tunable nanomechanical resonators based on multilayers containing a 100-nm-thin aluminum nitride (AlN) layer. Efficient piezoelectric actuation of very high frequency fundamental flexural modes up to ~80 MHz is demonstrated at room temperature. Thermomechanical fluctuations of AlN cantilevers measured by optical interferometry enable calibration of the transduction responsivity and displacement sensitivities of the resonators. Measurements and analyses show that the 100 nm AlN layer employed has an excellent piezoelectric coefficient, d_(31)=2.4 pm/V. Doubly clamped AlN beams exhibit significant frequency tuning behavior with applied dc voltage

Distance-Restricted Firefighting on Finite Graphs

In the classic version of the game of firefighter, on the first turn a fire breaks out on a vertex in a graph $G$ and then $b$ firefighters protect $b$ vertices. On each subsequent turn, the fire spreads to the collective unburnt neighbourhood of all the burning vertices and the firefighters again protect $b$ vertices. Once a vertex has been burnt or protected it remains that way for the rest of the game. We previously introduced the concept of $\textit{distance-restricted firefighting}$ where the firefighters' movement is restricted so they can only move up to some fixed distance $d$ and they may or may not be permitted to move through burning vertices. In this paper we establish the NP-Completeness of the distance-restricted versions of the $\textit{Maximum Vertices Saved}$ problem and present an integer program for solving these problems. In the penultimate section we also discuss some interesting properties of the $\textit{Expected Damage}$ function

Multi-Armed Bandits for Correlated Markovian Environments with Smoothed Reward Feedback

We study a multi-armed bandit problem in a dynamic environment where arm rewards evolve in a correlated fashion according to a Markov chain. Different than much of the work on related problems, in our formulation a learning algorithm does not have access to either a priori information or observations of the state of the Markov chain and only observes smoothed reward feedback following time intervals we refer to as epochs. We demonstrate that existing methods such as UCB and $\varepsilon$-greedy can suffer linear regret in such an environment. Employing mixing-time bounds on Markov chains, we develop algorithms called EpochUCB and EpochGreedy that draw inspiration from the aforementioned methods, yet which admit sublinear regret guarantees for the problem formulation. Our proposed algorithms proceed in epochs in which an arm is played repeatedly for a number of iterations that grows linearly as a function of the number of times an arm has been played in the past. We analyze these algorithms under two types of smoothed reward feedback at the end of each epoch: a reward that is the discount-average of the discounted rewards within an epoch, and a reward that is the time-average of the rewards within an epoch.Comment: Significant revision of prior version including deeper discussion of related work, gap-independent regret bounds, and regret bounds for discounted reward

HCI as a means to prosociality in the economy

HCI research often involves intervening in the economic lives of people, but researchers only rarely give explicit consideration to what actually constitutes prosociality in the economy. Much has been said previously regarding sustainability but this has largely focused on environmental rather than interpersonal relations. This paper provides an analysis of how prosocial HCI has been discussed and continues to be defined as a research field. Based on a corpus of published works, we describe a variety of genres of work relating to prosocial HCI. Key intellectual differences are explored, including the epistemological and ethical positions involved in designing for prosocial outcomes as well as how HCI researchers posit economic decision-making. Finally, emerging issues and opportunities for further debate and collaboration are discussed in turn