Faster Shortest Paths in Dense Distance Graphs, with Applications

We show how to combine two techniques for efficiently computing shortest paths in directed planar graphs. The first is the linear-time shortest-path algorithm of Henzinger, Klein, Subramanian, and Rao [STOC'94]. The second is Fakcharoenphol and Rao's algorithm [FOCS'01] for emulating Dijkstra's algorithm on the dense distance graph (DDG). A DDG is defined for a decomposition of a planar graph $G$ into regions of at most $r$ vertices each, for some parameter $r < n$. The vertex set of the DDG is the set of $\Theta(n/\sqrt r)$ vertices of $G$ that belong to more than one region (boundary vertices). The DDG has $\Theta(n)$ arcs, such that distances in the DDG are equal to the distances in $G$. Fakcharoenphol and Rao's implementation of Dijkstra's algorithm on the DDG (nicknamed FR-Dijkstra) runs in $O(n\log(n) r^{-1/2} \log r)$ time, and is a key component in many state-of-the-art planar graph algorithms for shortest paths, minimum cuts, and maximum flows. By combining these two techniques we remove the $\log n$ dependency in the running time of the shortest-path algorithm, making it $O(n r^{-1/2} \log^2r)$. This work is part of a research agenda that aims to develop new techniques that would lead to faster, possibly linear-time, algorithms for problems such as minimum-cut, maximum-flow, and shortest paths with negative arc lengths. As immediate applications, we show how to compute maximum flow in directed weighted planar graphs in $O(n \log p)$ time, where $p$ is the minimum number of edges on any path from the source to the sink. We also show how to compute any part of the DDG that corresponds to a region with $r$ vertices and $k$ boundary vertices in $O(r \log k)$ time, which is faster than has been previously known for small values of $k$

More about Divisible Design Graphs

Abstract: Divisible design graphs (DDG for short) have been recently defined by Kharaghani, Meulenberg and the second author as a generalization of (v, k, λ)-graphs. In this paper we give some new constructions of DDGs, most of them using Hadamard matrices and (v, k, λ)-graphs. For three parameter sets we give a nonexistence proof. Furthermore, we find conditions for a DDG to be walk-regular. It follows that most of the known examples are walk-regular, but some are not. In case walk-regularity of a DDG is forced by the parameters, necessary conditions for walk-regularity lead to new nonexistence results for DDGs. We examine all feasible parameter sets for DDGs on at most 27 vertices, establish existence in all but one cases, and decide on existence of a walk-regular DDG in all cases.divisible design graph;divisible design;walk-regular graph;(v;k;λ)-graph;Hadamard matrix

Effect of Distillers Grains Composition and Level on Steers Consuming High-Quality Forage

An experiment was conducted to determine the effects of dried distillers grains (DDG) supplementation level and composition on growing steer performance and forage intake. Factors included DDG supplementation level (0.25, 0.50, 0.75 or 1.00% of BW), and DDG solubles level (0, 5.4, 14.5, 19.1, or 22.1% DM). Final BW improved, and forage intake decreased with increasing levels of DDG. An interaction between DDG supplementation level and solubles level was observed on ADG and F:G and was likely related to supplemental fat levels. Supplementation of forages with DDG improves performance while decreasing forage intake when fat levels are not too great

Protein and Fiber Fortification of White Pan Bread Using Food-Grade Distiller’s Dried Grains

Distiller’s dried grains (DDG) are a coproduct of ethanol production. DDG has been used historically as animal feed. However, in the past decade, ethanol production has dramatically increased causing a surplus of distiller’s grains and saturating the market. The use of DDG, which is high in both protein and fiber, to fortify baked goods is one option to reduce the excess of DDG while enhancing its economic value. The purpose of this study was first, to evaluate the washing process for DDG to make it food grade, and second to evaluate the effects of incorporation of food-grade DDG from two different sources (DDGS and HP-DDG) on the quality of white pan bread (sandwich bread). HP-DDG was produced using a proprietary fractionation procedure prior to fermentation, while DDGS was produced using a conventional ethanol production procedure. Distiller’s dried grains with solubles (DDGS) and a high protein DDG (HP-DDG) were subjected to a washing process to make them food grade. Processing recovery (percent yield), color, and particle size were evaluated during the washing process. Substitutions of 5% and 10% of both DDGS and HP-DDG were used in all-purpose flour (APF). Dough rheology was tested using a Mixolab and a TA.XTPlus Texture Analyzer. Bread was baked using a modified AACC straight dough process. Loaves were then analyzed for color, volume, density, internal crumb structure and texture profile. Sensory acceptance of breads was evaluated using a seven-point hedonic scale. Yields from the washing process for the DDGS and HP-DDG, averaged 52.7% and 72%, respectively. While color of DDGS and HP-DDG was reduced through the washing process, finished products containing DDG were darker than the control. This led to visible color differences in the crumb of breads containing DDG. Significant differences were noted between washed DDG samples in relation to particle size distribution. Mycotoxins were not detected in either of the washed samples. Incorporation of food-grade DDG into breads led to smaller, denser loaves with fewer air cells. Loaves with 10% food-grade DDG were found to be significantly more firm than the 5% loaves. Substantial increases in protein content were seen at all levels of DDG inclusion, however statistically significant increases in fiber were noted only in the 10% DDGS loaves. Sensory analysis showed that all bread treatments were acceptable to consumers, and that the only significant difference in acceptability of loaves was noted in the appearance scores

Effects of Dried Distillers Grains and Equivalent Undegradable Intake Protein or Ether Extract on Performance and Forage Intake of Heifers Grazing Smooth Bromegrass Pastures

Crossbred heifers (n = 120; BW = 368 kg, SD = 39 kg) were used to determine effects of dried distillers grains (DDG) and relative contributions of undegradable intake protein (UIP) and fat (ether extract, EE) in DDG on ADG and forage intake (FI). Heifers rotationally grazed six 3.5-ha, smooth bromegrass paddocks (IVDMD = 65.7%, CP = 20.8%, UIP = 2.17%, DM basis). Heifers were blocked by previous ADG and allotted to treatments in a 3 × 3 + 1 factorial design. Factors were source and level of supplementation. Supplements were as follows: 1) DDG (UIP = 15.8%, EE = 9.67%), 2) corn gluten meal (CGM; UIP = 31.6%, EE = 0.83%), or 3) corn oil (OIL; UIP = 0.74%, EE = 19.3%). Amounts of DDG were 750, 1,500, or 2,250 g/d, whereas amounts of CGM and OIL were 375, 750, or 1,125 g/ d. Supplements containing CGM and OIL were fed in amounts that provided UIP and EE, respectively, equivalent to those of the DDG. Contrasts of interest were DDG vs. CGM and DDG vs. OIL. Control heifers were fed 250 g/d of a supplement containing corn bran and molasses (UIP = 0.92%, EE = 1.13%). Heifers were supplemented individually. Treatments were separated by regressing the response variables on grams of nutrient (DM, UIP, or EE) intake per kilogram of BW, because not all heifers consumed their allotment of supplement. Supplemental DDG resulted in a linear increase in ADG (P \u3c 0.01), whereas CGM tended to increase ADG (P = 0.14) but at a rate that was 39% of that for DDG, representing a response to MP. Supplementation of OIL did not affect ADG (P = 0.25) and tended to result in ADG less than that of DDG (P = 0.09). Supplementation with DDG had no effect (P = 0.63) on FI when predicted by the use of chromic oxide but tended (P = 0.07) to decrease FI when it was predicted from ADG using NE equations. Despite the differences between methods in the significance of the effect of DDG, the rates of substitution agreed (−0.50 and −0.45 for chromic oxide and NE equations, respectively), suggesting that the chromic oxide method was less sensitive in assessing FI. Supplementation with CGM decreased FI (P \u3c 0.01), but FI for CGM did not differ from that of DDG when the chromic oxide method was used (P = 0.19). Corn oil had no effect on FI (P = 0.42). Increased ADG and decreased FI observed from DDG supplementation is not independently explained by UIP or EE contained in DDG

Effect of Distillers Dried Grains with Solubles in Pig Starter Diets

During the past year there has been renewed interest in the feeding value of by-products of alcohol production. Previous research has dealt primarily with feeding of distillers dried grains or distillers dried grains with solubles (DDG/S) . Research conducted at South Dakota State University had shown that growing-finishing pigs could be fed diet s containing as much as 20% DDG/S without significantly affecting rate of gain. However , feed conversion was significantly poorer with this level of DDG/S in the diet . Protein and dry matter digestibility were also reduced when diets contained 20% of DDG/S. The experiment reported herein was conducted to evaluate different levels of DDG/S in pig starter diets that were equalized in lysine content

Effects of China’s Trade Policies on the U.S. Distiller’s Dried Grains

Domestic and export demand for distillers’ dried grains (DDG) has increased since the early 2000s. DDG have become an important component of livestock feed given its nutritional value and competitive price. Over the last decade, China has become one of the major export destinations for U.S. DDG. However, there have been recent changes in trade policies in China. In this thesis, we develop an inverse demand equation to analyze the impact of China’s policies on U.S. DDG prices. The model contributes to the literature by incorporating domestic and international demand through which exogenous shocks, such as China’s trade barriers, may affect U.S. DDG prices. Our results provide evidence that U.S. DDG prices are significantly lower during the time that anti-dumping and countervailing duties are in place. Advisors: Lia Nogueira and Kathleen Brook

Glycerol Monolaurate and Dodecylglycerol Effects on Staphylococcus aureus and Toxic Shock Syndrome Toxin-1 In Vitro and In Vivo

BACKGROUND:Glycerol monolaurate (GML), a 12 carbon fatty acid monoester, inhibits Staphylococcus aureus growth and exotoxin production, but is degraded by S. aureus lipase. Therefore, dodecylglycerol (DDG), a 12 carbon fatty acid monoether, was compared in vitro and in vivo to GML for its effects on S. aureus growth, exotoxin production, and stability. METHODOLOGY/PRINCIPAL FINDINGS:Antimicrobial effects of GML and DDG (0 to 500 microg/ml) on 54 clinical isolates of S. aureus, including pulsed-field gel electrophoresis (PFGE) types USA200, USA300, and USA400, were determined in vitro. A rabbit Wiffle ball infection model assessed GML and DDG (1 mg/ml instilled into the Wiffle ball every other day) effects on S. aureus (MN8) growth (inoculum 3x10(8) CFU/ml), toxic shock syndrome toxin-1 (TSST-1) production, tumor necrosis factor-alpha (TNF-alpha) concentrations and mortality over 7 days. DDG (50 and 100 microg/ml) inhibited S. aureus growth in vitro more effectively than GML (p<0.01) and was stable to lipase degradation. Unlike GML, DDG inhibition of TSST-1 was dependent on S. aureus growth. GML-treated (4 of 5; 80%) and DDG-treated rabbits (2 of 5; 40%) survived after 7 days. Control rabbits (5 of 5; 100%) succumbed by day 4. GML suppressed TNF-alpha at the infection site on day 7; however, DDG did not (<10 ng/ml versus 80 ng/ml, respectively). CONCLUSIONS/SIGNIFICANCE:These data suggest that DDG was stable to S. aureus lipase and inhibited S. aureus growth at lower concentrations than GML in vitro. However, in vivo GML was more effective than DDG by reducing mortality, and suppressing TNF-alpha, S. aureus growth and exotoxin production, which may reduce toxic shock syndrome. GML is proposed as a more effective anti-staphylococcal topical anti-infective candidate than DDG, despite its potential degradation by S. aureus lipase

Safety, Security and Socio-Economic Wellbeing in Somaliland

This report documents the findings from a study on the relationship between safety/security and socio-economic wellbeing in Somaliland. The study was conducted for the Danish Demining Group (DDG) and Geneva International Centre for Humanitarian Demining in twelve of DDG's project sites. It is based on a quantitative survey of 378 households and qualitative focus group interviews. Findings suggest a high degree of correlation between improvements in safety and security, many associated with the community safety work of DDG, and socio-economic benefits to communities. Reported benefits include fewer conflicts, more secure communities at night, fewer accidents involving small arms and explosive remnants of war, and better community-police relations. These are perceived to have contributed to improvements in access to markets, lengthening hours that businesses can remain open, improved opportunities for participating in savings activities, and generally increased household incomes. Recommendations for maximizing the benefits of improved security for socio-economic gains are provided