A study to determine the extent of instruction of individual income taxes to bookkeeping students in the secondary schools of New England

Thesis (Ed.M.)--Boston Universit

Are Drosophila telomeres an exception or the rule?

At the ends of eukaryotic chromosomes are telomeres, specialized structures with unusual properties. The repetitive structure of telomere regions makes them difficult to deal with in general genome-sequencing projects. Specific efforts to compare sequences and properties of telomeres across species can reveal the generalities of telomere properties

Spectral dimension reduction of complex dynamical networks

Dynamical networks are powerful tools for modeling a broad range of complex systems, including financial markets, brains, and ecosystems. They encode how the basic elements (nodes) of these systems interact altogether (via links) and evolve (nodes' dynamics). Despite substantial progress, little is known about why some subtle changes in the network structure, at the so-called critical points, can provoke drastic shifts in its dynamics. We tackle this challenging problem by introducing a method that reduces any network to a simplified low-dimensional version. It can then be used to describe the collective dynamics of the original system. This dimension reduction method relies on spectral graph theory and, more specifically, on the dominant eigenvalues and eigenvectors of the network adjacency matrix. Contrary to previous approaches, our method is able to predict the multiple activation of modular networks as well as the critical points of random networks with arbitrary degree distributions. Our results are of both fundamental and practical interest, as they offer a novel framework to relate the structure of networks to their dynamics and to study the resilience of complex systems.Comment: 16 pages, 8 figure

Long and short range multi-locus QTL interactions in a complex trait of yeast

We analyse interactions of Quantitative Trait Loci (QTL) in heat selected yeast by comparing them to an unselected pool of random individuals. Here we re-examine data on individual F12 progeny selected for heat tolerance, which have been genotyped at 25 locations identified by sequencing a selected pool [Parts, L., Cubillos, F. A., Warringer, J., Jain, K., Salinas, F., Bumpstead, S. J., Molin, M., Zia, A., Simpson, J. T., Quail, M. A., Moses, A., Louis, E. J., Durbin, R., and Liti, G. (2011). Genome research, 21(7), 1131-1138]. 960 individuals were genotyped at these locations and multi-locus genotype frequencies were compared to 172 sequenced individuals from the original unselected pool (a control group). Various non-random associations were found across the genome, both within chromosomes and between chromosomes. Some of the non-random associations are likely due to retention of linkage disequilibrium in the F12 population, however many, including the inter-chromosomal interactions, must be due to genetic interactions in heat tolerance. One region of particular interest involves 3 linked loci on chromosome IV where the central variant responsible for heat tolerance is antagonistic, coming from the heat sensitive parent and the flanking ones are from the more heat tolerant parent. The 3-locus haplotypes in the selected individuals represent a highly biased sample of the population haplotypes with rare double recombinants in high frequency. These were missed in the original analysis and would never be seen without the multigenerational approach. We show that a statistical analysis of entropy and information gain in genotypes of a selected population can reveal further interactions than previously seen. Importantly this must be done in comparison to the unselected population's genotypes to account for inherent biases in the original population

Two Essays in the Philosophy of Economics

This paper addresses the question of how fundamental theories in economics (e.g. game theory and general equilibrium theories) are related to theories of specific markets or market phenomena. This question arises because, in neoclassical economics, fundamental theories typically are not subjected directly to empirical tests. The argument presented here has two parts. First it is argued that, even without being directly tested itself, fundamental theory can help to refine, test and evaluate specific theories. Six ways in which this can occur are enumerated. Second, it is argued that the close relationship between fundamental and specific theories is a general feature of positive economics rather than being a special feature of neoclassical theory, and that this relationship makes it possible systematically to test or evaluate fundamental theory. Views of Friedman, Machlup and von Mises are considered

Complex networks as an emerging property of hierarchical preferential attachment

Real complex systems are not rigidly structured; no clear rules or blueprints exist for their construction. Yet, amidst their apparent randomness, complex structural properties universally emerge. We propose that an important class of complex systems can be modeled as an organization of many embedded levels (potentially infinite in number), all of them following the same universal growth principle known as preferential attachment. We give examples of such hierarchy in real systems, for instance in the pyramid of production entities of the film industry. More importantly, we show how real complex networks can be interpreted as a projection of our model, from which their scale independence, their clustering, their hierarchy, their fractality and their navigability naturally emerge. Our results suggest that complex networks, viewed as growing systems, can be quite simple, and that the apparent complexity of their structure is largely a reflection of their unobserved hierarchical nature.Comment: 12 pages, 7 figure

Phase transition of the susceptible-infected-susceptible dynamics on time-varying configuration model networks

We present a degree-based theoretical framework to study the susceptible-infected-susceptible (SIS) dynamics on time-varying (rewired) configuration model networks. Using this framework, we provide a detailed analysis of the stationary state that covers, for a given structure, every dynamic regimes easily tuned by the rewiring rate. This analysis is suitable for the characterization of the phase transition and leads to three main contributions. (i) We obtain a self-consistent expression for the absorbing-state threshold, able to capture both collective and hub activation. (ii) We recover the predictions of a number of existing approaches as limiting cases of our analysis, providing thereby a unifying point of view for the SIS dynamics on random networks. (iii) We reinterpret the concept of hub-dominated phase transition. Within our framework, it appears as a heterogeneous critical phenomenon : observables for different degree classes have a different scaling with the infection rate. This leads to the successive activation of the degree classes beyond the epidemic threshold.Comment: 14 pages, 11 figure

Exact analytical solution of irreversible binary dynamics on networks

In binary cascade dynamics, the nodes of a graph are in one of two possible states (inactive, active), andnodes in the inactive state make an irreversible transition to the active state, as soon as their precursors satisfya predetermined condition. We introduce a set of recursive equations to compute the probability of reachingany final state, given an initial state, and a specification of the transition probability function of each node.Because the naive recursive approach for solving these equations takes factorial time in the number of nodes, wealso introduce an accelerated algorithm, built around a breath-first search procedure. This algorithm solves theequations as efficiently as possible in exponential time

Experimental investigation of coolant-flow characteristics of a sintered porous turbine blade

Local cooling-air flow rates through the walls of a sintered porous-metal turbine blade were measured at room temperature for a range of pressure drops. In order to check the validity of the correlation procedure, this procedure was used to correlate air-flow rates thorough two porous disks at temperatures up to 600 degrees F.245:00:Experimental investigation of coolant Data indicate the method permits room-temperature flow data to be used for heat-transfer work at elevated temperatures with reasonable accurach. Cooling-air flow distribution around the periphery of the test blade is presented for two internal cooling air pressures with the blade in a 1000 degrees Fahrenheit gas stream at a cascade-inlet Mach number of 0.45

Variation de la masse et des caractères morphologiques des lémuriens nocturnes dans les forêts primaires et dégradées de Menabe Sud, Belo sur Mer, Madagascar

Forest structure effects primate morphology because it determines the availability and characteristics of resources, such as substrates for locomotion, sleeping trees, and trees food. However, forest degradation may alter environmental condition of habitats and influence lemur behavior and morphology. We evaluated the links between forest degradation, lemur body mass, and lemur morphometric. We surveyed red-tailed sportive lemurs (Lepilemur ruficaudatus) and gray mouse lemurs (Microcebus murinus) in the dry, deciduous forest of southern Menabe, Morondava, Madagascar. The study was conducted in the dry season in 2014 (November–December) and 2015 (July–September). Lemur captures were conducted in five forest sites: two primary forest and three disturbed forest. Sherman and Tomahawk style traps were used to capture mouse lemurs. We conducted three capture sessions in site B in 2014 and three capture sessions for each site in 2015, for a total of 5616 night traps. During each capture session, 80 Sherman traps and 24 Tomahawk traps were installed for three consecutive nights. To capture the red-tailed sportive lemur, we used a gun (Dan Inject Model JM air rifle) with a tranquillizer dart to immobilize the animal. We collected morphometric measurements from 232 mouse lemurs and 31 red-tailed sportive lemurs. Botanic plots (5m x 5m) allowed us to characterize the forest characteristics: tree diameter at breast height (DBH), tree height, tree abundance, tree crown height and diameter. Tree abundance with DBH ≥ 5 cm and trees diversity varied significantly between sites (P < 0.001). Mouse lemur body mass did not vary with seasonality of the capture (P > 0.05). For mouse lemurs, all morphometric from two populations in the pristine forest were similar (P > 0.05). Mouse lemurs in one disturbed habitat had greater body length and body mass than mouse lemurs in the pristine forest (P < 0.05). The difference may be linked with fruit abundance of two trees species (Tamarindus indica and Ziziphus mauritiana) and more insect availability in the disturbed site. In the altered habitat, mouse lemur females had longest body size and heavier than males (P < 0.05). Red-tailed sportive lemur body mass and length did not change between sites (P > 0.05). Our study is consistent with the hypothesis that lemur morphometric and body mass may change with forest degradation in southern forest of Menabe. Additionally, the range of the response varies between species and sex: mouse lemurs had a wider reaction norm to the habitat disturbance than did red-tailed sportive lemurs. Mouse lemurs may have higher ecological flexibility and tolerance for forest changes, specifically the alteration of forest habitats. Understanding how lemur morphology responds to habitat disturbance may be used as a tool to prioritize lemur conservation.   Résumé La perte d’habitat due à l’activité humaine est une menace qui affecte tous les primates à Madagascar. Les lémuriens, primates arboricoles, ont des réponses variées face au changement de leur habitat. La présente recherche vise à déterminer le lien entre la dégradation forestière, la masse et les caractères morphologiques des lémuriens nocturnes de Menabe Sud : Lepilemur ruficaudatus et Microcebus murinus. L’étude a été effectuée dans cinq sites dont deux sites sont des forêts primaires et trois autres sont des forêts perturbées. La capture et la mesure des caractères morphologiques des lémuriens ont été réalisées entre novembre et décembre 2014, puis entre juillet et septembre 2015. Des parcelles botaniques (5m x 5m) ont été utilisées pour décrire les caractéristiques des sites dont l’abondance des arbres, le diamètre à hauteur de poitrine ou la hauteur et le diamètre de la couronne. La masse de M. murinus n’était pas influencée par la saison de capture (P > 0,05), mais elle variait avec le sexe (P < 0,005) et le site (P < 0,001). Tous les caractères morphologiques de M. murinus dans les deux forêts primaires étaient similaires (P > 0,05). Par contre, dans les forêts perturbées, les femelles de M. murinus étaient plus lourdes et avaient des corps plus longs que les mâles (P < 0,05). La masse et la longueur du corps de L. ruficaudatus entre les différents sites étaient similaires (P > 0,05). Comparé à L. ruficaudatus, M. murinus répondrait davantage à la dégradation forestière. Comprendre l’étendue de la réponse morphologique des lémuriens face à la dégradation de leur habitat pourrait être utilisé comme outil pour prioriser leur conservation