Conserved Dynamics and Interface Roughening in Spontaneous Imbibition : A Critical Overview

Imbibition phenomena have been widely used experimentally and theoretically to study the kinetic roughening of interfaces. We critically discuss the existing experiments and some associated theoretical approaches on the scaling properties of the imbibition front, with particular attention to the conservation law associated to the fluid, to problems arising from the actual structure of the embedding medium, and to external influences such as evaporation and gravity. Our main conclusion is that the scaling of moving interfaces includes many crossover phenomena, with competition between the average capillary pressure gradient and its fluctuations setting the maximal lengthscale for roughening. We discuss the physics of both pinned and moving interfaces and the ability of the existing models to account for their properties.Comment: 9 pages, Late

Comment on: `Pipe Network Model for Scaling of Dynamic Interfaces in Porous Media'

We argue that a proposed exponent identity [Phys. Rev. Lett 85, 1238 (2000)] for interface roughening in spontaneous imbibition is wrong. It rests on the assumption that the fluctuations are controlled by a single time scale, but liquid conservation imposes two distinct time scales.Comment: 1 page, to appear in Phys. Rev. Let

An Observational Evaluation of Safety Resulting from Driver Distraction

Distracted driving is a dangerous activity that continues to claim lives on roadways throughout the United States. A goal of this research was to collect distracted driving behavior data through observation in the field. A methodological approach was devised to keep data collection consistent across the observation periods. Analysis of the data provided information regarding trends in distraction type or driving behavior while engaging in a secondary activity. In combination with the observational portion of this research, another key component to understanding distracted driving was the crash report narrative key word search. By searching through the crash reports, it was determined which key words have high discriminating powers that indicate distraction was a key component to a crash. Additionally, the key word search demonstrated how accurately distraction related crashes are reported via the crash report form. This research contributed to the existing literature regarding distracted driving and also expanded the methods of research that are currently in use

CENTRAL NORTH ATLANTIC PALEOCEANOGRAPHY DURING THE LATE EARLY PLEISTOCENE (SPANNING MARINE ISOTOPE STAGE 21) BASED ON A HIGH-RESOLUTION DINOFLAGELLATE CYST RECORD

A high-resolution dinoflagellate cyst record from Integrated Ocean Drilling Program Site U1313, constrained by an ultra-high resolution δ18O record from the same sample set, is established to enhance our understanding of the paleoceanography and structure of Marine Isotope Stage (MIS) 21 in the central North Atlantic. Changes in cyst abundance, composition of cyst assemblages, and their diversity reflect major regional shifts in climate and ocean circulation for this time interval (866–814 ka). The following paleoenvironmental indicators are used: Operculodinium centrocarpum sensu Wall & Dale (North Atlantic Current), Nematosphaeropsis labyrinthus and Impagidinium pallidum (subpolar gyre), total Impagidinium species (subtropical gyre), and protoperidiniacean cysts (biological productivity). The integration of stable isotope and the generated dinoflagellate cyst data shows MIS 21 to have been climatically unstable and interrupted between 830 and 840 ka by two significant cool episodes. These are resolved using the relative abundance of cooler-water species and by tracking the abundance of O. centrocarpum. During MIS 21, Site U1313 was predominantly under the influence of the subtopical gyre until after 835 ka when the NAC was re-established until the end of MIS 21. This study also extends the stratigraphic range of Fibrocysta? fusiforma from its previously documented range top in the Lower Pleistocene at 2.3 Ma to ~812 ka in the present study. An unnamed Spiniferites species (Spiniferites sp. 1) is confined to the latest phase of MIS 22. Two unidentified acritarchs (Acritarch spp. 1 and 2) occur throughout MIS 21 and merit further investigation

COLLECTORS FOR ENABLING FLOTATION OF OXIDIZED COAL

The coalburg seam coal is an example of difficult to float bituminous coal. Laboratory tests conducted on coalburg flotation feed sample revealed recovery values around 28% with 15% product ash when using fuel oil as collector under natural pH conditions. A detailed study showed that increasing pH from natural value of 5.6 to 7.5 provided a significant improvement in recovery of approximately 32 absolute percentage points. The improvement is believed to be result of the release of humic acids from the surface and the dispersion of clay particles thereby leaving a more hydrophobic surface. Based on the tests conducted with various commercially available collectors, oleic acid was selected as a model collector for oxidized coals. Conventional flotation tests found an increase in combustible recovery of 10 absolute percentage points above the pH improvement using 4:1 blend of fuel oil and oleic acid. The problem of higher ash in conventional cell product due to entrainment was minimized by the use of wash water in a flotation column. A flotation concentrate containing less than 7.5% ash was produced while recovering around 75% of the combustible material. Further testing using fatty acids-fuel oil blend also showed evidence of a near 200% increase in flotation rate

Significance of sweet sorghum as a multi-purpose crop for sub-Saharan Africa

There is great interest in sweet sorghum (Sorghum bicolor L.) for promoting resilience in rural livelihoods in Sub- Saharan Africa (SSA). Unlike other crops, sweet sorghum is a multi-purpose crop for grain, feed, fodder, chewing, syrup and biofuel production. The objective of this paper is to analyse information on the diversity within the crop, its adaptation and plant breeding efforts in SSA. We also discuss opportunities that exist in SSA that make the crop an attractive alternative. It is clear from the review that the crop has a wide genetic base, hence significant improvements can be made on a number of preferred traits. The review further outlines four possible production models for the economic development of the sweet sorghum industry in Sub-Saharan Africa; which are (i) production for supply to urban chewing markets, (ii) syrup production, (iii) biofuel production and (iv) fodder production. Although current research focuses on production of ethanol for biofuel, other potential uses such as production for chewing, syrup and fodder cannot be overlooked for most SSA farmers. A lot has to be done on the research front before biofuel production from sweet sorghum can be profitable and technically feasible. Future plant breeding efforts can be tailor made to deliver cultivars with peculiar traits for various end-uses