Unavoidable induced subgraphs in large graphs with no homogeneous sets

A homogeneous set of an $n$-vertex graph is a set $X$ of vertices ($2\le |X|\le n-1$) such that every vertex not in $X$ is either complete or anticomplete to $X$. A graph is called prime if it has no homogeneous set. A chain of length $t$ is a sequence of $t+1$ vertices such that for every vertex in the sequence except the first one, its immediate predecessor is its unique neighbor or its unique non-neighbor among all of its predecessors. We prove that for all $n$, there exists $N$ such that every prime graph with at least $N$ vertices contains one of the following graphs or their complements as an induced subgraph: (1) the graph obtained from $K_{1,n}$ by subdividing every edge once, (2) the line graph of $K_{2,n}$, (3) the line graph of the graph in (1), (4) the half-graph of height $n$, (5) a prime graph induced by a chain of length $n$, (6) two particular graphs obtained from the half-graph of height $n$ by making one side a clique and adding one vertex.Comment: 13 pages, 3 figure

Memory for biopsychology material presented in comic book format.

This study investigated the influence of format of presentation on memory for undergraduate level Biopsychology material. Ninety participants read either seven comic book pages from Aleixo and Baillon (2008) explaining the rudiments of sleep, the same material presented in text only format or seven pages where the original images were replaced with random incongruous images. Participants were tested on the material using ten multiple-choice questions. Results showed significantly higher memory scores in the comic book condition compared to both the text only and the incongruous comic condition. Furthermore, the text only version showed significantly higher memory scores than the incongruous comic condition. It was concluded that while there were some limitations with the study, the findings provided preliminary evidence to support the general idea of using comic books to create instructional materials. Results also provided some support for dual coding theory (Paivio, 1969, 1972, 1975) as a theoretical basis for the use of comics in educational contexts. Keywords: Comics, Comic Books, Graphic Novels, Memory, Education, Dual-Coding Theory

Seasonal and interannual variability of North American isoprene emissions as determined by formaldehyde column measurements from space

Formaldehyde (HCHO) columns measured from space by solar UV backscatter allow mapping of reactive hydrocarbon emissions. The principal contributor to these emissions during the growing season is the biogenic hydrocarbon isoprene, which is of great importance for driving regional and global tropospheric chemistry. We present seven years (1995-2001) of HCHO column data for North America from the Global Ozone Monitoring Experiment (GOME), and show that the general seasonal and interannual variability of these data is consistent with knowledge of isoprene emission. There are some significant regional discrepancies with the seasonal patterns predicted from current isoprene emission models, and we suggest that these may reflect flaws in the models. The interannual variability of HCHO columns observed by GOME appears to follow the interannual variability of surface temperature, as expected from current isoprene emission models

Calorimetric determination of the heat of solution of calcium in liquid ammonia and the heat of reaction of calcium with the ammonium ion in liquid ammonia

Thesis (M.A.)--Boston University, 1949. This item was digitized by the Internet Archive

Rates and controls of footpath erosion in Giant's Castle Game Reserve, KwaZulu / Natal Drakensberg.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.The Drakensberg is an important ecological and recreational resource area within southern Africa, yet little knowledge exists concerning the factors controlling soil erosion in the region. The two most important anthropogenic modifiers of natural erosion processes in the areas beyond the: Drakensberg Park main camps and access roads are vegetation burning and the erosion associated with footpaths. This dissertation investigates the rates and controls of footpath erosion in Giant's Castle Game Reserve in the KwaZulu/Natal Drakensberg. Two measurement techniques are employed. Sediment yield and runoff were monitored from six runoff plots installed on different gradients on a high user-intensity footpath. Runoff is found to increase linearly with increasing footpath gradient. Sediment yield increases gradually with increasing footpath gradient to a threshold path gradient of 13.36°, after which sediment yield increases rapidly. Soil eroded from the runoff plots has a finer particle size distribution than the footpath tread surfaces within the plots. Rates of sediment generated from the runoff plots is dependant on the rainfall intensity index (I60), as opposed to rainfall kinetic energy or total rainfall related indices, while runoff is dependant on the El60 index. A 100m point-based survey of footpath attributes, totalling a distance of21km along four paths in the Reserve was undertaken. Where footpath gradients are low and user-intensity is high, path morphometry is dependant on orientation to the slope. Morphology of footpaths with both higher gradients and user-intensities show a dependence on path gradient. The degree of compaction of the footpath tread decreases away from the main camp and is positively related to user-intensity. Multiple path development is. associated with the path width to maximum depth ratios and a threshold ratio range of 4. 0 I to 4. 50 is established for the initiation of secondary path routes. A comparison of the survey data with a survey conducted in 1989 indicate erosion rates between 3.24 and 13. 0 tons/km/a over a four year period. Erosion rates for the runoff plots and for the surveys indicate that the values obtained for the two techniques of measurement utilised in the study approximate each other. Path erosion rates, while still presenting a prnblem, are not uncharacteristically high in Giant's Castle. Game Reserve in comparison to the scarce data available on rates of path erosion within and beyond southern Africa

The thermochemistry of calcium strontium and barium in liquid ammonia at -33°C.

Thesis (Ph.D.)--Boston UniversityThe solutions of the alkali and alkaline earth metals in liquid ammonia are characterized by certain anomalous properties which are generally similar for these groups of metals. The similarity of the properties of these metal-ammonia solutions has been found to be due to the presence of a common negative species, the electron associated with the solvent in some undetermined manner (the "solvated" electron). In this dissertation the investigations of the ammonia solutions of the alkaline earth metals have been reviewed. Early studies have indicated that calcium, strontium, and barium metals combine with ammonia to form their respective hexammoniates, M(NH3)6. The heats of formation of these compounds, as determined from vapor pressure data, are: - 10.3 kcal.,- 9.9 kcal., and - 9.6 kcal., respectively. Magnesium metal, which is only sparingly soluble in liquid ammonia, also forms a hexammoniate. The following general remarks can be applied to all the alkaline earth metal ammoniates: the compounds a re identical in appearance with the solutions from which they are precipitated; the optical and electrical properties are the same for both the solid and the solution, therefore being independent of the physical state of the system and probably being determined by the same factors

Arrangement for interfacing a telephone device with a personal computer

An arrangement provides an interface between a telephone device and a personal computer in such a manner that enhanced capability for both the telephone device and the computer in processing information in an analog telephone environment is provided. The telephone device attaches to an analog telephone line and advantageously operates either as a stand-alone device when the computer is powered-off or in tandem with the computer when the computer is powered-on. A user is able to access any of the available telephony features from the telephone device at all times and from the computer when it is powered-on. Such available telephony features include, by way of example, Caller ID for decoding available information presented on the analog telephone line and an integrated telephone answering system, which provides for reception, transmission, and storage of voice, facsimile, and electronic mail messages.Published versio

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation