Modification of Aluminium Surface Using Picosecond Laser for Printing Applications

Ultrafast picosecond laser pulses of wavelength of 1064nm have allowed the surface modification of anodised aluminium plate for potential industrial application. The interaction of the laser with the substrate created a hydrophilic surface, giving a contact angle of less than 10 degrees. On examination under a Scanning Electron Microscope (SEM), it was observed that these surfaces have an interesting ‘lotus-leaf’ like structure. It has been found that these laser processed hydrophilic surfaces revert with time. The potential for application in the printing industry is strong due to the reusability and sustainability of the process materials; initial trials confirm this. This technology would offer extra advantages as a non-chemical process without the need for developer, thereby reducing the overall cost and time of printin

Determination of the Frequency and Cytotoxic Activity of Tnf-secreting Subpopulations of Tumor Associated Macrophages

Limiting dilution analysis was utilized as a method to estimate the frequency of murine tumor associated macrophages (TAM) and normal splenic macrophages that secrete tumor necrosis factor (TNF) before and after prestimulation with bacterial lipopolysaccharide (LPS). In addition, an MTT cytotoxicity assay utilizing anti-TNF polyclonal antibody (a-TNF) to block the TNF activity of TAM was used to determine if TNF secretion is solely responsible for the tumoricidal activity of TAM. Finally, combinations of LPS, macrophage-colony stimulating factor (M-CSF), and gamma- interferon (IFN -y) were assessed for their effects on the enhancement of the tumoricidal activtity of TNF-secreting tumor associated macrophages (TAM). Analysis of the data generated in this study show that only rare subpopulations of TAM and normal splenic macrophages can be induced to become cytotoxic. This cytotoxic activity is due to the secretion of tumor necrosis factor (1NF) and, in both cases, the frequency of these macrophages exhibiting cytotoxic activity is strikingly similar. Further analysis of data from MTT cytotoxicity assays suggest that the LPS, M-CSF and IFN-y alone or in specific combinations can significantly enhance the cytotoxic activity of 1NF-secreting subpopulations of tumor associated macrophages.Microbiolog

Comparative Feeding Ecology of Two Chimpanzee Communities in Kibale National Park (Uganda)

Several recent studies have documented considerable intraspecific and intrapopulation ecological variation in primates. However, we generally lack an understanding of how such variability may be linked to concomitant demographic variation among groups and/or populations of the same species, particularly in regards to large-bodied and wide-ranging species with high ecological flexibility, such as chimpanzees (Pan troglodytes). We compared the feeding ecology of chimpanzees inhabiting two sites in Kibale National Park, Uganda that differ three-fold in chimpanzee density and support notably different plant communities. Chimpanzees at Ngogo, a site with the largest known chimpanzee community and unusually high chimpanzee density, spent a significantly lower percentage of time resting (and pregnant and lactating females spent more time feeding), incorporated higher percentages of ripe fruit in their diet, had lower dietary diversity values, and had shorter and less variable average patch residency times than did their counterparts at the nearby Kanyawara site, which supports a relatively low density of chimpanzees. Additionally, feeding party size was significantly and positively related to feeding patch size at Ngogo, but not at Kanyawara. Together these findings aid in explaining the noted disparity in chimpanzee community size and density between Ngogo and Kanyawara by suggesting that the diet of Ngogo chimpanzees is of higher overall quality than that of Kanyawara chimpanzees. They also highlight the potentially profound influence of even small-scale habitat heterogeneity on the ecology of primates. Researchers must take such influences into account when attempting to draw conclusions about species- or population-level characteristics.Human Evolutionary Biolog

Mining Novellas from PubMed Abstracts using a Storytelling Algorithm

Motivation: There are now a multitude of articles published in a diversity of journals providing information about genes, proteins, pathways, and entire processes. Each article investigates particular subsets of a biological process, but to gain insight into the functioning of a system as a whole, we must computationally integrate information across multiple publications. This is especially important in problems such as modeling cross-talk in signaling networks, designing drug therapies for combinatorial selectivity, and unraveling the role of gene interactions in deleterious phenotypes, where the cost of performing combinatorial screens is exorbitant. Results: We present an automated approach to biological knowledge discovery from PubMed abstracts, suitable for unraveling combinatorial relationships. It involves the systematic application of a `storytelling' algorithm followed by compression of the stories into `novellas.' Given a start and end publication, typically with little or no overlap in content, storytelling identifies a chain of intermediate publications from one to the other, such that neighboring publications have significant content similarity. Stories discovered thus provide an argued approach to relate distant concepts through compositions of related concepts. The chains of links employed by stories are then mined to find frequently reused sub-stories, which can be compressed to yield novellas, or compact templates of connections. We demonstrate a successful application of storytelling and novella finding to modeling combinatorial relationships between introduction of extracellular factors and downstream cellular events. Availability: A story visualizer, suitable for interactive exploration of stories and novellas described in this paper, is available for demo/download at https://bioinformatics.cs.vt.edu/storytelling

Critical Exponents of the Four-State Potts Model

The critical exponents of the four-state Potts model are directly derived from the exact expressions for the latent heat, the spontaneous magnetization, and the correlation length at the transition temperature of the model.Comment: LaTex, 7 page

Book Reviews

Reviews of the following books: The Wilderness from Chamberlain Farm: A Story of Hope for the American Wild by Dean B. Bennett; The French Baron of Pentagouet: Baron St. Castin and the Struggle for Empire in Early New England by Ailene S. Taylor; Bold Vision: The Development of the Parks of Portland, Maine, edited by Theo H.B.M. Holtwijk and Earle G. Shettleworth, Jr.; Charles Nolcini: The Life and Music of an Italian American in the Age of Jackson by Vincent A. Lapomarda; A Most Remarkable Mix: Sketches of Notable Freeporters by John D. Davi

Pleistocene range dynamics in the eastern Greater Cape Floristic Region: A case study of the Little Karoo endemic Berkheya cuneata (Asteraceae)

AbstractThe glacial–interglacial climate cycles of the Pleistocene played a significant role in dramatically altering species distributions across the globe. However, the climate of the Greater Cape Floristic Region is thought to have been decoupled from global fluctuations and the current Mediterranean climate remained relatively buffered during this period. Here we explore the roles of climate stability and the topographic complexity of the region on the range history of an endemic Little Karoo plant, Berkheya cuneata, using ensemble species distribution modelling and multi-locus phylogeography. The species distribution models projected onto downscaled climate simulation of the Last Glacial Maximum demonstrated a considerable range contraction and fragmentation into the western and eastern Little Karoo, separated by the Rooiberg inselberg. This population fragmentation is mirrored in the phylogeographic structuring of both chloroplast and nuclear DNA. These results suggest that sufficient climatic buffering coupled with regionally complex topography ensured the localised population persistence during Pleistocene climate cycles but these features have also promoted population vicariance in this, and likely other, Little Karoo lowland species

Exact results for the zeros of the partition function of the Potts model on finite lattices

The Yang-Lee zeros of the Q-state Potts model are investigated in 1, 2 and 3 dimensions. Analytical results derived from the transfer matrix for the one-dimensional model reveal a systematic behavior of the locus of zeros as a function of Q. For 1<Q<2 the zeros in the complex $x=\exp(\beta H_q)$ plane lie inside the unit circle, while for Q>2 they lie outside the unit circle for finite temperature. In the special case Q=2 the zeros lie exactly on the unit circle as proved by Lee and Yang. In two and three dimensions the zeros are calculated numerically and behave in the same way. Results are also presented for the critical line of the Potts model in an external field as determined from the zeros of the partition function in the complex temperature plane.Comment: 15 pages, 6 figures, RevTe