Layout of Graphs with Bounded Tree-Width

A \emph{queue layout} of a graph consists of a total order of the vertices, and a partition of the edges into \emph{queues}, such that no two edges in the same queue are nested. The minimum number of queues in a queue layout of a graph is its \emph{queue-number}. A \emph{three-dimensional (straight-line grid) drawing} of a graph represents the vertices by points in $\mathbb{Z}^3$ and the edges by non-crossing line-segments. This paper contributes three main results: (1) It is proved that the minimum volume of a certain type of three-dimensional drawing of a graph $G$ is closely related to the queue-number of $G$. In particular, if $G$ is an $n$-vertex member of a proper minor-closed family of graphs (such as a planar graph), then $G$ has a $O(1)\times O(1)\times O(n)$ drawing if and only if $G$ has O(1) queue-number. (2) It is proved that queue-number is bounded by tree-width, thus resolving an open problem due to Ganley and Heath (2001), and disproving a conjecture of Pemmaraju (1992). This result provides renewed hope for the positive resolution of a number of open problems in the theory of queue layouts. (3) It is proved that graphs of bounded tree-width have three-dimensional drawings with O(n) volume. This is the most general family of graphs known to admit three-dimensional drawings with O(n) volume. The proofs depend upon our results regarding \emph{track layouts} and \emph{tree-partitions} of graphs, which may be of independent interest.Comment: This is a revised version of a journal paper submitted in October 2002. This paper incorporates the following conference papers: (1) Dujmovic', Morin & Wood. Path-width and three-dimensional straight-line grid drawings of graphs (GD'02), LNCS 2528:42-53, Springer, 2002. (2) Wood. Queue layouts, tree-width, and three-dimensional graph drawing (FSTTCS'02), LNCS 2556:348--359, Springer, 2002. (3) Dujmovic' & Wood. Tree-partitions of $k$-trees with applications in graph layout (WG '03), LNCS 2880:205-217, 200

Comparative study of Gymnocephalus cernuus (Linnaeus, 1758) and G. baloni Holcik & Hensel, 1974 (Pisces, Percidae)

In the comparative study of Gymnocephalus cernuus and G. baloni we searched for differences in growth, habitat and feeding between the two species in support of their distinctness. significant differences were found in both habitat and feeding, whereas growth was more or less similar. G. baloni is bound to hiding places located in flowing water. In vegetative periods it occurs solitary and in generative in pairs. G. cernuus lives in shoals in the whole season, occuring mostly in the open, still parts of waters near to the bottom. The food of the two ruffe species mostly consists of the characteristic macroinvertebrates of their habitat. The body pattern, the number of opecular spines and the cut on the membrane between AI and AII were found to be the most useful characters in identification

African American women in public higher education administrative leadership in the state of Missouri: perspectives on a half century of progress

This study explores the lived experiences of six African American female administrators in Missouri public higher educational institutions. The Black Feminist Thought theory as espoused by Patricia Collins is the framework with which this research examines their leadership. The conceptual lens of race, gender, and class offers an opportunity to see strength and empowerment as these women face oppression with a conqueror's attitude. The ways in which these women are empowered to employ leadership and use their positional authority is reflected in the three themes, knowledge, consciousness, and the politics of empowerment. Interviews were conducted with the participants using open-ended questions. They were questions about their positional authority, the cultural climate, political climate, and challenges as African American female administrators. They were also asked to make recommendations to Missouri institutions. The themes that emerged where: 1) racism, 2) sexism, 3) gender equity, 4) disrespect of knowledge, 5) lack of diversity, 6) isolation, and 7) lack of recruitment and retention efforts . Yet, with these emerging themes, the participants were empowered to continue to perform their duties, because students need what they have to offer, perseverance, advocacy, and role models

Reactivity ratio estimation for co- and terpolymerization of n-butyl acrylate, methyl methacrylate and 2-ethylhexyl acrylate

N-butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) and methyl methacrylate (MMA) are commonly used as monomers in coatings, adhesives and many other applications. Our current interest is in BA/MMA/EHA terpolymer formulations for the production of pressure sensitive adhesives. For the purposes of controlling polymer adhesive performance, kinetic parameters such as the reactivity ratios, are required. Reactivity ratios for BA/MMA are available in the literature1, while that for BA/EHA and MMA/EHA are not. The bulk copolymerization reactivity ratios for BA/EHA and MMA/EHA were determined at 60 C using statistically designed free-radical polymerizations at low-conversion (\u3c10%). The estimates were then validated using high-conversion copolymerizations. These reactivity ratio estimates were used, along with the literature values for the BA/MMA system, for the prediction of BA/MMA/EHA composition in a series of high conversion bulk terpolymerizations. Please click Additional Files below to see the full abstract

An imitative hexagram of the 7th century

In a Hungarian online numismatic forum (a closed Facebook group) in August 2016 a very particular silver coin appeared as a local find, probably near to Gyula, on the Great Hungarian Plain. On the obverse the coin shows the busts of Constans II and Constantine IV with a general design very similar, for example, to the hexagram MIB 151-2-3. Constans II is draped and facing, wearing a plumed helmet with star, and Constantine IV is draped and facing, but wearing a crown; between their heads, there is a cross

A Metabolic Dependency for Host Isoprenoids in the Obligate Intracellular Pathogen Rickettsia parkeri Underlies a Sensitivity to the Statin Class of Host-Targeted Therapeutics.

Gram-negative bacteria in the order Rickettsiales have an obligate intracellular growth requirement, and some species cause human diseases such as typhus and spotted fever. The bacteria have evolved a dependence on essential nutrients and metabolites from the host cell as a consequence of extensive genome reduction. However, it remains largely unknown which nutrients they acquire and whether their metabolic dependency can be exploited therapeutically. Here, we describe a genetic rewiring of bacterial isoprenoid biosynthetic pathways in the Rickettsiales that has resulted from reductive genome evolution. Furthermore, we investigated whether the spotted fever group Rickettsia species Rickettsia parkeri scavenges isoprenoid precursors directly from the host. Using targeted mass spectrometry, we found that infection caused decreases in host isoprenoid products and concomitant increases in bacterial isoprenoid metabolites. Additionally, we report that treatment of infected cells with statins, which inhibit host isoprenoid synthesis, prohibited bacterial growth. We show that growth inhibition correlates with changes in bacterial size and shape that mimic those caused by antibiotics that inhibit peptidoglycan biosynthesis, suggesting that statins lead to an inhibition of cell wall synthesis. Altogether, our results describe a potential Achilles' heel of obligate intracellular pathogens that can potentially be exploited with host-targeted therapeutics that interfere with metabolic pathways required for bacterial growth.IMPORTANCE Obligate intracellular pathogens, which include viruses as well as certain bacteria and eukaryotes, are a subset of infectious microbes that are metabolically dependent on and unable to grow outside an infected host cell because they have lost or lack essential biosynthetic pathways. In this study, we describe a metabolic dependency of the bacterial pathogen Rickettsia parkeri on host isoprenoid molecules that are used in the biosynthesis of downstream products, including cholesterol, steroid hormones, and heme. Bacteria make products from isoprenoids, such as an essential lipid carrier for making the bacterial cell wall. We show that bacterial metabolic dependency can represent a potential Achilles' heel and that inhibiting host isoprenoid biosynthesis with the FDA-approved statin class of drugs inhibits bacterial growth by interfering with the integrity of the cell wall. This work supports the potential to treat infections by obligate intracellular pathogens through inhibition of host biosynthetic pathways that are susceptible to parasitism

Magnitude-range brightness variations of overactive K giants

We study three representative, overactive spotted K giants (IL Hya, XX Tri, and DM UMa) known to exhibit V-band light variations between 0.65-1.05 mags. Our aim is to find the origin of their large brightness variation. We employ long-term phase-resolved multicolor photometry, mostly from automatic telescopes, covering 42 yr for IL Hya, 28 yr for XX Tri, and 34 yr for DM UMa. For one target, IL Hya, we present a new Doppler image from NSO data taken in late 1996. Effective temperatures for our targets are determined from all well-sampled observing epochs and are based on a V-I_C color-index calibration. The effective temperature change between the extrema of the rotational modulation for IL Hya and XX Tri is in the range 50-200 K. The bolometric flux during maximum of the rotational modulation, i.e., the least spotted states, varied by up to 39% in IL Hya and up to 54% in XX Tri over the course of our observations. We emphasize that for IL Hya this is just about half of the total luminosity variation that can be explained by the photospheric temperature (spots/faculae) changes, while for XX Tri it is even about one third. The long-term, 0.6 mag V-band variation of DM UMa is more difficult to explain because little or no B-V color index change is observed on the same timescale. Placing the three stars with their light and color variations into H-R diagrams, we find that their overall luminosities are generally too low compared to predictions from current evolutionary tracks. A change in the stellar radius due to strong and variable magnetic fields during activity cycles likely plays a role in explaining the anomalous brightness and luminosity of our three targets. At least for IL Hya, a radius change of about 9% is suggested from m_bol and T_eff, and is supported by independent vsin(i) measurements.Comment: 13 pages, 8 figures, accepted in A&

Neoliberal and inclusive themes in European lifelong learning policy

DRAFT: not for citation. This is a pre-peer-review, pre-copy edited version of a chapter published in Sheila Riddell, Jörg Markowitsch, and Elisabet Weedon, eds., Lifelong learning in Europe: Equity and efficiency in the balance, Bristol: Policy Press (2012). Details of the definitive published version and how to purchase it are available online at: http://www.policypress.co.uk/display.asp?K=9781447300137&sf1=keyword&st1=riddell&m=1&dc=

Isolation, characterization and selection of bacterial isolates from a suppressive soil with beneficial traits to plants

Backgrounds This study focused on the characterization and selection of bacterial strains obtained from a suppressive soil displaying antifungal activity against the soilborne phytopathogenic fungi Rosellinia necatrix. Bacterial profile from this suppressive soil were first obtained by 16S rRNA gene sequencing, revealing a significant increase in the bacterial class Gammaproteobacteria, especially in some antagonistic representatives of Pseudomonas spp. Objectives To obtain and characterize a collection of 246 bacterial isolates obtained from this suppressive soil, in order to identify new strains with antifungal activity against fungal phytopathogens. Methods To obtain the bacterial collection, we performed an isolation on a selective medium for Pseudomonas-like microorganisms. Further characterization tests were used in order to analyse the bacterial collection, including identification of the general metabolic profile of glucose, the profiling of antifungals produced, including both the putative production of antifungal compounds and lytic exoenzymes, and the evaluation of traits related with beneficial effects on plants. Conclusions A final selection of representative strains resulted in antifungal isolates belonging to the genus Pseudomonas, but also some representatives of the genera Serratia and Stenotrophomonas. These selected strains were tested for plant protection by an in vivo experiment using avocado and wheat plants challenged by the pathogen R. necatrix, showing all of them an antifungal ability and plant disease protection. Pseudomonas-like strains isolated from suppressive soils constitute an excellent source for novel microbial biocontrol agents against soilborne fungal pathogens. This work was supported by grant AGL2014-52518-C2-1-R. Carmen Vida and Sandra Tienda are supported by a PhD fellowship from the FPI program of the Spanish Government.This work was supported by grant AGL2014-52518-C2-1-R. Carmen Vida and Sandra Tienda are supported by a PhD fellowship from the FPI program of the Spanish Government; Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Time-series Doppler images and surface differential rotation of the effectively-single rapidly-rotating K-giant KU Pegasi

According to most stellar dynamo theories, differential rotation (DR) plays a crucial role for the generation of toroidal magnetic fields. Numerical models predict surface differential rotation to be anti-solar for rapidly-rotating giant stars, i.e., their surface angular velocity could increase with stellar latitude. However, surface differential rotation has been derived only for a handful of individual giant stars to date. The spotted surface of the K-giant KU Pegasi is investigated in order to detect its time evolution and quantify surface differential rotation. We present altogether 11 Doppler images from spectroscopic data collected with the robotic telescope STELLA between 2006--2011. All maps are obtained with the surface reconstruction code iMap. Differential rotation is extracted from these images by detecting systematic (latitude-dependent) spot displacements. We apply a cross-correlation technique to find the best differential rotation law. The surface of KU Peg shows cool spots at all latitudes and one persistent warm spot at high latitude. A small cool polar spot exists for most but not all of the epochs. Re-identification of spots in at least two consecutive maps is mostly possible only at mid and high latitudes and thus restricts the differential-rotation determination mainly to these latitudes. Our cross-correlation analysis reveals solar-like differential rotation with a surface shear of $\alpha=+0.040\pm0.006$, i.e., approximately five times weaker than on the Sun. We also derive a more accurate and consistent set of stellar parameters for KU Peg including a small Li abundance of ten times less than solar.Comment: 13 pages, 12 figures, accepted for publication in A&