Field Measurements of Ice Scraping Loads on Front Mounted Plow Blades, HR-374, 1997

Removal of ice from roads is of the more challenging task in winter highway maintenance. The best mechanical method is to use a truck with underbody plow blade, but such equipment is not available to all agencies charged with winter maintenance operations. While counties and cities often use motor graders to scrape ice, it would be of great benefit if front mounted plows could be used effectively for ice removal. To reveal and understand the factors that influence the performance of these plows, measurement of the forces experienced by the plow blades during ice scraping is desirable. This study explores the possibility of using accelerometers to determine the forces on a front-mounted plow when scraping ice. The plow was modeled by using a dynamic approach. The forces on the plow were to be determined by the measurement of the accelerations of the plow. Field tests were conducted using an "as is" front-mounted plow instrumented with accelerometers. The results of the field tests indicate that in terms of ice removal, the front-mounted plow is not favorable equipment. The major problem in this study is that the front mounted plow was not able to cut ice, and therefore experienced no significant scraping forces. However, the use of accelerometers seems to be promising for analyzing the vibration problems of the front-mounted plow.

Field Measurements of Plow Loads During Ice Removal Operations, HR-334, 1993

One of the more severe winter hazards is ice or compacted snow on roadways. While three methods are typically used to combat ice (salting, sanding and scraping), relatively little effort has been applied to improve methods of scraping ice from roads. In this project, a new test facility has been developed, comprising a truck with an underbody blade, which has been instrumented such that the forces to scrape ice from a pavement can be measured. A test site has been used, which is not accessible to the public, and ice covers have been sprayed onto the pavement and subsequently scraped from it, while the scraping loads have been recorded. Three different cutting edges have been tested for their ice scraping efficiency. Two of the blades are standard (one with a carbide insert, the other without) while the third blade was designed under the SHRP H-204A project. Results from the tests allowed two parameters to be identified. The first is the scraping efficiency which is the ratio of vertical to horizontal force. The lower this ratio, the more efficiently ice is being removed. The second parameter is the scraping effectiveness, which is related (in some as yet unspecified manner) to the horizontal load. The higher the horizontal load, the more ice is being scraped. The ideal case is thus to have as high a horizontal load as possible, combined with the lowest possible vertical load. Results indicate that the SHRP blade removed ice more effectively than the other two blades under equivalent conditions, and furthermore, did so with greater efficiency and thus more control. Furthermore, blade angles close to 0 deg provide for the most efficient scraping for all three blades. The study has shown that field testing of plow blades is possible in controlled situations, and that blades can be evaluated using this system. The system is available for further tests as are deemed appropriate.

Climate and vegetation history of western Portugal inferred from Albian near-shore deposits (Gale Formation, Lusitanian Basin)

The late Early Cretaceous greenhouse climate has been studied intensively based on proxy data derived essentially from open marine archives. In contrast, information on continental climatic conditions and on the accompanying response of vegetation is relatively scarce, most notably owing to the stratigraphic uncertainties associated with many Lower Cretaceous terrestrial deposits. Here, we present a palynological record from Albian near-shore deposits of the Lusitanian Basin of W Portugal, which have been independently dated using Sr-isotope signals derived from low-Mg oyster shell calcite. Sr-87/Sr-86 values fluctuate between 0.707373 +/- 0.00002 and 0.707456 +/- 0.00003; absolute values and the overall stratigraphic trend match well with the global open marine seawater signature during Albian times. Based on the new Sr-isotope data, existing biostratigraphic assignments of the succession are corroborated and partly revised. Spore-pollen data provide information on the vegetation community structure and are flanked by sedimentological and clay mineralogical data used to infer the overall climatic conditions prevailing on the adjacent continent. Variations in the distribution of climate-sensitive pollen and spores indicate distinct changes in moisture availability across the studied succession with a pronounced increase in hygrophilous spores in late Early Albian times. Comparison with time-equivalent palynofloras from the Algarve Basin of southern Portugal shows pronounced differences in the xerophyte/hygrophyte ratio, interpreted to reflect the effect of a broad arid climate belt covering southern and southeastern Iberia during Early Albian times.

Measurement of Ice Scraping Forces on Snow-Plow Underbody Blades, HR-372, 1997

In this study, several new cutting edges for removal of ice from the roadway were tested in a series of closed road tests. These new cutting edges consisted of a variety of serrated shapes. The study also included measurement of ice scraping forces by in-service trucks. These trucks were instrumented in a similar manner as the truck used in the closed-road tests. Results from the closed-road and in-service tests were analyzed by two parameters. The first parameter is the scraping effectiveness, which is defined as the average horizontal force experienced by a cutting edge. The amount of ice scraped from the roadway is directly proportional to the magnitude of the scraping effectiveness. Thus an increase in scraping effectiveness indicates an increase in the amount of ice being scraped from the roadway. The second parameter is force angle, which is defined as tan to the -1 power [vertical force/horizontal force]. A combination of a minimal force angle and a maximized scraping effectiveness represents a case in which the maximal amount of ice is being removed from the pavement without an exceptionally large vertical force. Results indicate that each cutting edge produced a maximal scraping effectiveness with a testing configuration of a 15 deg blade angle and a 23,000 lb. download force. Results also indicate that each cutting edge produced a minimal force angle with a testing configuration of a 15 deg blade angle and a 10,000 lb. download force. Results from the in-service trucks produced similar data and also similar trends within the data when compared to the results of the closed-road tests. This result is most important, as it suggests that the closed-road tests do provide an accurate measure of ice scraping forces for a given blade and configuration of that blade. Thus if the closed-road tests indicate that certain blades perform well, there is now excellent reason to conduct full scale tests of such blades.

Astrocyte-neuron lactate transport is required for long-term memory formation.

We report that, in the rat hippocampus, learning leads to a significant increase in extracellular lactate levels that derive from glycogen, an energy reserve selectively localized in astrocytes. Astrocytic glycogen breakdown and lactate release are essential for long-term but not short-term memory formation, and for the maintenance of long-term potentiation (LTP) of synaptic strength elicited in vivo. Disrupting the expression of the astrocytic lactate transporters monocarboxylate transporter 4 (MCT4) or MCT1 causes amnesia, which, like LTP impairment, is rescued by L-lactate but not equicaloric glucose. Disrupting the expression of the neuronal lactate transporter MCT2 also leads to amnesia that is unaffected by either L-lactate or glucose, suggesting that lactate import into neurons is necessary for long-term memory. Glycogenolysis and astrocytic lactate transporters are also critical for the induction of molecular changes required for memory formation, including the induction of phospho-CREB, Arc, and phospho-cofilin. We conclude that astrocyte-neuron lactate transport is required for long-term memory formation.

Preliminary description and slope stability analyses of the 2008 Little Salmon lake and 2007 Mt. Steele landslides, Yukon

In August 2008, reactivation of the Little Salmon Lake landslide occurred. During this event, hundreds of conical mounds of variable size and composition formed in the deposition zone. The characteristics of these landforms are described and a potential mechanism for their formation is proposed. A preliminary slope stability analysis of the 2007 Mount Steele rock and ice avalanche was also undertaken. The orientation of very high persistence (>20 m long) structural planes (e.g., faults, joints and bedding) within bedrock in the source zone was obtained using an airborne-LiDAR digital elevation model and the software COLTOP-3D. Using these discontinuity orientation measurements, kinematic, surface wedge and simple three-dimensional distinct element slope stability analyses were performed.

Traité de la construction théorique et pratique du scaphandre ou Bateau de l'homme ... par M. de La Chapelle. Nouvelle édition... Précédé du Projet de formation d'une légion nautique ou d'éclaireurs des côtes, destinée à opérer tels débarquemens qu'on avisera sans le secours de vaisseaux... par... La Reynie...

Comprend : Projet de formation d'une légion nautique ou d'éclaireurs des côtes, destinée à opérer tels débarquemens qu'on avisera sans le secours de vaisseaux, bateaux-plats, artillerie, etc.,...

Molecular genetic framework for protophloem formation.

The phloem performs essential systemic functions in tracheophytes, yet little is known about its molecular genetic specification. Here we show that application of the peptide ligand CLAVATA3/EMBRYO SURROUNDING REGION 45 (CLE45) specifically inhibits specification of protophloem in Arabidopsis roots by locking the sieve element precursor cell in its preceding developmental state. CLE45 treatment, as well as viable transgenic expression of a weak CLE45(G6T) variant, interferes not only with commitment to sieve element fate but also with the formative sieve element precursor cell division that creates protophloem and metaphloem cell files. However, the absence of this division appears to be a secondary effect of discontinuous sieve element files and subsequent systemically reduced auxin signaling in the root meristem. In the absence of the formative sieve element precursor cell division, metaphloem identity is seemingly adopted by the normally procambial cell file instead, pointing to possibly independent positional cues for metaphloem formation. The protophloem formation and differentiation defects in brevis radix (brx) and octopus (ops) mutants are similar to those observed in transgenic seedlings with increased CLE45 activity and can be rescued by loss of function of a putative CLE45 receptor, BARELY ANY MERISTEM 3 (BAM3). Conversely, a dominant gain-of-function ops allele or mild OPS dosage increase suppresses brx defects and confers CLE45 resistance. Thus, our data suggest that delicate quantitative interplay between the opposing activities of BAM3-mediated CLE45 signals and OPS-dependent signals determines cellular commitment to protophloem sieve element fate, with OPS acting as a positive, quantitative master regulator of phloem fate.

Ice-Retardant Pavement, HR-290, 1991

During 1986, the City of Des Moines placed an experimental asphaltic concrete overlay containing an ice-retardant additive (Verglimit) on Euclid Avenue (U.S. Highway 6). Verglimit is a chemical multi-component deicer which is added to the surface course of an asphalt overlay. The additive was uniformly distributed through the mix at the asphalt plant, which allows exposure of the particles as the finished surface wears under traffic. During a snowfall, the exposed particles attract and absorb moisture creating a deicing solution which dampens the pavement. The Verglimit additive used on this project cost $1,180 per metric ton. The Verglimit was added at a rate of 6.3% by weight, which was 126 pounds per ton, or $66.38 per ton of hot mix asphalt. The purchase of Verglimit additive was funded by the Iowa Department of Transportation through a research project recommended by the Highway Research Advisory Board. The pavement surface experienced severe wetting due to the additive's affinity for water immediately after the project was completed and during periods of high humidity. This wetting created slippery conditions both on the project itself and where vehicles tracked the additive. The only way to remove the slipperiness was by flushing the street with water. The ice-retardant overlay appears to perform as expected in reducing the adherence of ice and snow, especially at temperatures just below freezing. It performs better in light snowfalls than in heavy ones. The ice retardant overlay is effective in eliminating thin coatings of ice due to freezing drizzle or widespread frost. The accident data showed a reduction in the number of snow and ice related accidents but due to the low number of this type of accident the results are inconclusive.

Precision and scaling in morphogen gradient read-out.

Morphogen gradients infer cell fate as a function of cellular position. Experiments in Drosophila embryos have shown that the Bicoid (Bcd) gradient is precise and exhibits some degree of scaling. We present experimental results on the precision of Bcd target genes for embryos with a single, double or quadruple dose of bicoid demonstrating that precision is highest at mid-embryo and position dependent, rather than gene dependent. This confirms that the major contribution to precision is achieved already at the Bcd gradient formation. Modeling this dynamic process, we investigate precision for inter-embryo fluctuations in different parameters affecting gradient formation. Within our modeling framework, the observed precision can only be achieved by a transient Bcd profile. Studying different extensions of our modeling framework reveals that scaling is generally position dependent and decreases toward the posterior pole. Our measurements confirm this trend, indicating almost perfect scaling except for anterior most expression domains, which overcompensate fluctuations in embryo length.

L'arrêt cardiaque: quelle réalité et quelle formation pour le praticien [Heart arrest: which reality and which training for the practitioner?]

Sudden death related to out-of hospital cardiac arrest is an important cause of mortality, which is mainly caused by ventricular fibrillation, a potentially reversible condition. The prognosis of out-of-hospital cardiac arrest remains dismal despite well developed emergency medical services. Witnessed arrest, ventricular fibrillation as the initial arrhythmia, cardiopulmonary resuscitation and early defibrillation are systematically associated with better survival. Key interventions must therefore be enforced to improve survival from out-of-hospital cardiac, introducing the concept of a "chain of survivals". The aim of the present article, which is illustrated by local results, is to review this important public health issue, to emphasize the role of the general practitioner in the chain of survival, and to promote education and training of basic and advanced life support.