Fluctuations and noise in cancer development

This paper explores fluctuations and noise in various facets of cancer development. The three areas of particular focus are the stochastic progression of cells to cancer, fluctuations of the tumor size during treatment, and noise in cancer cell signalling. We explore the stochastic dynamics of tumor growth and response to treatment using a Markov model, and fluctutions in tumor size in response to treatment using partial differential equations. We also explore noise within gene networks in cancer cells, and noise in inter-cell signalling.Comment: 11 pages, 6 figure

Technology adoption determinants: strategic management implications for small, owner-managed travel firms in Jamaica.

This thesis begins by thoroughly reviewing classical theories of adoption such as the diffusion of innovation theory, and the technology acceptance model, and subsequently analyses literature on pertinent theories which have been highlighted as drivers of adoption such as the Resource-Based View, Firm Strategy, Culture and the Digital Divide. Prior to this however, the afore-mentioned classical adoption theories were contrasted with the Post-Internet debate which explored Information Asymetry and Disintermediation. Having conducted this review it was determined that the leadership/ownership role had not been sufficiently emphasized in technology adoption, therefore this work sought to more clearly identify these personal factors in combination with the previously explored factors. The overarching theory of Organizational Decision-Making was used to provide a framework to identify drivers of decision-making processes in general and then apply these to the internet adoption context. This thesis aims to identify the combination of antecedents of technology adoption for travel firms and distil factors to identify the key determinant of the adoption of the internet for sales and marketing purposes in small, owner-managed travel firms. It examines the firm characteristics which are associated with adoption behaviour such as strategy and resources, as well as external factors such as culture and the digital divide. In addition to external and firm factors, personal factors such as ownership and leadership are explored at various stages of adoption. A predominantly qualitative methodology was used to interview travel agencies in the context of Jamaica. All firms which have similar characteristics in terms of ownership and management structure, in particular where owners are themselves the managers and provide leadership for the organization, were interviewed. The owner-managers of these firms were interviewed to gather deep perspectives from local industry experts on industry challenges, current technology involvement and future directions. Exploratory descriptive quantitative methods were used to analyze firm characteristics and their relationships to internet adoption for sales and marketing as well as the intention to use these technologies in firms, while a deeper exploration into owner-managers was achieved through qualitative enquiry. A pilot study and 2 phases of data collection were carried out. The findings indicate that the leadership role is more significant than has been previously posited. The contribution to knowledge is new in that it takes a unique approach to an understanding of technology adoption in firms by creating a comprehensive conceptual framework for adoption based on previous research and then creates a model that shows the factors and variables that drive adoption at each stage of the adoption process from a personal leadership perspective as well as the organizational perspective. Ultimately it is hoped that this focus on each stage of adoption will provide insights into firm adoption behaviour as a consequence of leadership characteristics

Obtaining Hemocytes from the Hawaiian Bobtail Squid Euprymna scolopes and Observing their Adherence to Symbiotic and Non-Symbiotic Bacteria

Studies concerning the role of the immune system in mediating molecular signaling between beneficial bacteria and their hosts have, in recent years, made significant contributions to our understanding of the co-evolution of eukaryotes with their microbiota. The symbiotic association between the Hawaiian bobtail squid, Euprymna scolopes and the bioluminescent bacterium Vibrio fischeri has been utilized as a model system for understanding the effects of beneficial bacteria on animal development. Recent studies have shown that macrophage-like hemocytes, the sole cellular component of the squid host's innate immune system, likely play an important role in mediating the establishment and maintenance of this association. This protocol will demonstrate how to obtain hemocytes from E. scolopes and then use these cells in bacterial binding assays. Adult squid are first anesthetized before hemolymph is collected by syringe from the main cephalic blood vessel. The host hemocytes, contained in the extracted hemolymph, are adhered to chambered glass coverslips and then exposed to green fluorescent protein-labeled symbiotic Vibrio fischeri and non-symbiotic Vibrio harveyi. The hemocytes are counterstained with a fluorescent dye (Cell Tracker Orange, Invitrogen) and then visualized using fluorescent microscopy

Mapping the Integration of Sensory Information across Fingers in Human Sensorimotor Cortex

The integration of somatosensory signals across fingers is essential for dexterous object manipulation. Previous experiments suggest that this integration occurs in neural populations in the primary somatosensory cortex (S1). However, the integration process has not been fully characterized, as previous studies have mainly used 2-finger stimulation paradigms. Here, we addressed this gap by stimulating all 31 single- and multifinger combinations. We measured population-wide activity patterns evoked during finger stimulation in human S1 and primary motor cortex (M1) using 7T fMRI in female and male participants. Using multivariate fMRI analyses, we found clear evidence of unique nonlinear interactions between fingers. In Brodmann area (BA) 3b, interactions predominantly occurred between pairs of neighboring fingers. In BA 2, however, we found equally strong interactions between spatially distant fingers, as well as interactions between finger triplets and quadruplets. We additionally observed strong interactions in the hand area of M1. In both M1 and S1, these nonlinear interactions did not reflect a general suppression of overall activity, suggesting instead that the interactions we observed reflect rich, nonlinear integration of sensory inputs from the fingers. We suggest that this nonlinear finger integration allows for a highly flexible mapping from finger sensory inputs to motor responses that facilitates dexterous object manipulation.SIGNIFICANCE STATEMENT Processing of somatosensory information in primary somatosensory cortex (S1) is essential for dexterous object manipulation. To successfully handle an object, the sensorimotor system needs to detect complex patterns of haptic information, which requires the nonlinear integration of sensory inputs across multiple fingers. Using multivariate fMRI analyses, we characterized brain activity patterns evoked by stimulating all single- and multifinger combinations. We report that progressively stronger multifinger interactions emerge in posterior S1 and in the primary motor cortex (M1), with interactions arising between inputs from neighboring and spatially distant fingers. Our results suggest that S1 and M1 provide the neural substrate necessary to support a flexible mapping from sensory inputs to motor responses of the hand

Glaciers in Equilibrium, McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, ofte

A Glaciochemical Survey of the Summit Region, Greenland

Spatial representativeness and an understanding of controls on chemical species distribution are essential requirements of any significant ice core investigation. Snowpit studies provide an essential tool in this process. In preparation for the central Greenland deep drilling effort a series of snowpits was sampled in detail for oxygen isotopes, major anions, major cations, total acidity and radionuclides. The results of this sampling program are used to define: (I) the chemical composition of the snow in the region, (2) the input timing and spatial distribution of major chemical species, (3) the potential dependence of species concentration on accumulation rate, and (4) the signal characteristics identifiable in the region over the last few years

The evolution of genome size in ants

<p>Abstract</p> <p>Background</p> <p>Despite the economic and ecological importance of ants, genomic tools for this family (Formicidae) remain woefully scarce. Knowledge of genome size, for example, is a useful and necessary prerequisite for the development of many genomic resources, yet it has been reported for only one ant species (<it>Solenopsis invicta</it>), and the two published estimates for this species differ by 146.7 Mb (0.15 pg).</p> <p>Results</p> <p>Here, we report the genome size for 40 species of ants distributed across 10 of the 20 currently recognized subfamilies, thus making Formicidae the 4^thmost surveyed insect family and elevating the Hymenoptera to the 5^thmost surveyed insect order. Our analysis spans much of the ant phylogeny, from the less derived Amblyoponinae and Ponerinae to the more derived Myrmicinae, Formicinae and Dolichoderinae. We include a number of interesting and important taxa, including the invasive Argentine ant (<it>Linepithema humile</it>), Neotropical army ants (genera <it>Eciton </it>and <it>Labidus</it>), trapjaw ants (<it>Odontomachus</it>), fungus-growing ants (<it>Apterostigma</it>, <it>Atta </it>and <it>Sericomyrmex</it>), harvester ants (<it>Messor</it>, <it>Pheidole </it>and <it>Pogonomyrmex</it>), carpenter ants (<it>Camponotus</it>), a fire ant (<it>Solenopsis</it>), and a bulldog ant (<it>Myrmecia</it>). Our results show that ants possess small genomes relative to most other insects, yet genome size varies three-fold across this insect family. Moreover, our data suggest that two whole-genome duplications may have occurred in the ancestors of the modern <it>Ectatomma </it>and <it>Apterostigma</it>. Although some previous studies of other taxa have revealed a relationship between genome size and body size, our phylogenetically-controlled analysis of this correlation did not reveal a significant relationship.</p> <p>Conclusion</p> <p>This is the first analysis of genome size in ants (Formicidae) and the first across multiple species of social insects. We show that genome size is a variable trait that can evolve gradually over long time spans, as well as rapidly, through processes that may include occasional whole-genome duplication. The small genome sizes of ants, combined with their ecological, evolutionary and agricultural importance, suggest that some of these species may be good candidates for future whole-genome sequencing projects.</p