UVR sensitivity of Chaoborus larvae

In small temperate lakes, predation by fish generally regulates the species structure and abundance of larval Chaoborus. Yet, Chaoborus abundance may also vary appreciably among lakes with no fish. Many fishless lakes in Sudbury, Ontario, have transparent waters. This raises the possibility that low abundance of Chaoborus in such lakes may be attributable to UVR-induced mortality. To determine whether UVR affects Chaoborus survival, we performed 6 in situ experiments over 2 to 4 day periods at 4 depths in Ruth-Roy Lake (a clear fishless lake with few Chaoborus). Third and fourth instar C. punctipennis were randomly allocated to 3 treatments: quartz (UVR+ PAR), OP3 acrylite (PAR only) and dark controls. Survival under UVR+PAR was significantly reduced in comparison with the other treatments. Survival under PAR only was high, and did not differ from the dark controls. Time to death increased with incubation depth and larval stage. These results suggest that the small Chaoborus population in Ruth-Roy Lake, and perhaps in other fishless, clear lakes may be attributed to UVR-induced mortality.     

Investigating the influence on safety of retrofitting Italian motorways with barriers meeting a new EU standard

Objective: A new European Union (EU) regulation for safety barriers, which is based on performance, has encouraged road agencies to perform an upgrade of old barriers, with the expectation that there will be safety benefits at the retrofitted sites. The new class of barriers was designed and installed in compliance with the 1998 (European Norm) EN 1317 standards for road restraint systems, which lays down common requirements for the testing and certification of road restraint systems in all countries of the European Committee for Standardization (CEN). Both the older and new barriers are made of steel and are installed in such a way as to avoid vehicle intrusion, but the older ones are thought to be only effective at low speeds and large angles of impact. The new standard seeks to remedy this by providing better protection at higher speeds. This article seeks to quantify the effect on the frequency of fatal and injury crashes of retrofitting motorways with barriers meeting the new standards.

Methods: The estimation of the crash modification was carried out by performing an empirical Bayes before–after analysis based on data from the A18 Messina–Catania motorway in Italy. The methodology has the great advantage to account for the regression to the mean effects. Besides, to account for time trend effects and dispersion of crash data, a modified calibration methodology of safety performance was used.

Results: This study, based on data collected on 76 km of motorway in the period 2000–2012, derived Crash Modification Factor point estimates that indicate reductions of 72% for run-off-road fatal and injury crashes and 38% in total fatal and injury crashes that could be expected by upgrading an old safety barrier by complying with new EU 1317 standards. The estimated benefit-cost ratio of 5.57 for total crashes indicates that the treatment is cost effective.

Conclusions: The magnitude of this benefit indicates that the retrofits are cost-effective even for total crashes and should continue in any European country inasmuch as the estimated Crash Modification Factors are based on treatment sites that are reasonably representative of all European motorways.     

幽蚊幼虫对紫外辐射(UVR)的敏感性

在小型温带湖泊中,鱼类的捕食一般调节着幽蚊幼虫的物种结构和丰度.然而,没有鱼类的湖泊间的幽蚊丰度差别也很明显.安大略省萨德伯里的许多无鱼湖泊的湖水清澈透明.这就产生了这样的可能性:这类湖泊中幽蚊丰度低可能归因于紫外辐射(UVR)引起的死亡.为了确定UVR是否影响幽蚊存活率,我们在罗斯罗伊湖(一个几乎没有幽蚊的水清、无鱼的湖泊)4个水深处进行了为期2～4天的6个现场实验.对第3和第4龄虫C.Punctipennis随机进行3种处理:石英(UVR+PAR)控制;OP3聚丙烯酸酯塑料(只是PAR)控制以及无光控制.在UVR+PAR下的生存率大大低于其他的处理方法.在只是PAR下的生存率较高,与无光控制没有什么不同.死亡时间随着孵化深度和幼虫期的增加而增加.这些结果表明,罗斯罗伊湖,也许还有其他的无鱼、水清湖泊中幽蚊种群规模小可能是缘于UVR引起的死亡.     

MULTIFRACTAL SCALING OF DAILY RUNOFF TIME SERIES IN AGRICULTURAL WATERSHEDS1

Abstract: Multifractal scaling behavior of long-term records of daily runoff time series in 32 subwatersheds covering a wide range of sizes was examined. These subwatersheds were associated with four agricultural watersheds with different climates and topography. The empirical moment scaling curves obtained using the trace moment method showed that the runoff time series exhibited a multifractal behavior, which was valid over a time scale range from one day to about three years. The multi-fractal scaling of the runoff time series was well described by the Universal Multifractal Model. The spectral analysis (β < 1) and the order of fractional integration (H ⋍; 0) indicated that the runoff time series were conservative. The multifractal parameters, α (multifractal index) and C₁ (co-dimension), were reasonably close to each other for subwatersheds within each of the watersheds and were generally similar among the four watersheds. The α values of the four watersheds were 1.10 ± 0.13, 1.61 ± 0.06,1.61 ± 0.24, and 1.63 ± 0.19. The C₁ values of four watersheds were 0.19 ± 0.01, 0.17 ± 0.01, 0.17 ± 0.04, and 0.11 ± 0.02. The multifractal analyses provided useful insight into the runoff time series, especially the occurrence and distribution of extreme events.     

PLATE JUNCTIONS AND HYDROCARBON ACCUMULATIONS IN THE INDIAN REGION

This article relates the productive and potential oil fields in India to plate junctions and other major tectonic features. High geothermal gradients are known to accelerate the expulsion of petroleum from the source bed, as well as its migration and accumulation in favourable reservoir rocks, resulting in high yield. Some of the world's major petroleum deposits occur along ‘failed arms’ associated with the plume generated triple junctions. Seven triple junctions have been located in the Indian region, and two more are identified here. Interestingly, India's off-shore petroleum prospects coincide with some of these triple junctions. Cet article établit la relation entre les champs de pétrole en production et potentiels en Inde à la théorie des plaques et à d'autres traits tectoniques importants. L'on sait que des gradients géothermiques élevés accélèrent l'expulsion du pétrole à partir de la roche-mère et favorisent la migration et l'accumulation dans des réservoirs convenables. Quelques-uns des plus grands champs de pétrole du monde se rencontrent en liaison avec des ‘bras morts’ associés avec un système triple de fossés d'effondrement. Sept systèmes triples ont été repérés en Inde et deux autres sont reconnus ici. II est intéressant de remarquer que les possibilités pétrolières de l'offshore indien coïncide avec certains de ces systèmes triples. Este artículo establece la relación entre los campos petrolíferos en producción y potenciales de India a la teoría de placas y otros aspectos tectónicos. Es sabido que una gradiente térmica alta ascelera la expulsión del petróleo desde la roca madre y favorece su migración y acumulación en rocas reservorio favorables. Algunos de los mayores depósitos de petróleo se encuentran a lo largo de los “brazos muertos” asociados a un sistema triple de unión de placas. Siete uniones de este tipo habia sido localizadas en India y otros dos más son identificados aquí. Es interesante notar que las posibilidades petroleras en la zona marítima de India coinciden con alguna forma de sistemas triple de placas.