Spatio-temporal permanence and plasticity of foraging trails in young and mature leaf-cutting ant colonies (Atta spp.)

The distribution and formation of foraging trails have largely been neglected as factors explaining harvesting patterns of leaf-cutting ants.We applied fractal analysis, circular, and conventional statistics to published and newly recorded trailmaps of seven Atta colonies focusing on three aspects: permanence, spatio-temporal plasticity and colony life stage. In the long term, trail patterns of young and mature Atta colonies revealed that foraging activities were focused on distinct, static sectors that made up only parts of their potentially available foraging range. Within these foraging sectors, trails were typically ephemeral and highly variable in space and time. These ephemeral trails were concentrated around permanent trunk trails in mature and around nest entrances in young colonies. Besides these similarities, the comparison of trail systems between the two life stages indicated that young colonies exploited fewer leaf sources, used smaller and less-complex systems of foraging trails, preferred different life forms as host plants, and switched hosts more often compared with mature colonies. Based on these analyses, we propose a general hypothesis which describes the foraging pattern in Atta as a result of initial foraging experiences, spatio-temporal distribution of suitable host plants, energetic constraints, and other factors such as seasonality and interspecific predatio

February 15, 1996

The Breeze is the student newspaper of James Madison University in Harrisonburg, Virginia

Neural-Kalman Schemes for Non-Stationary Channel Tracking and Learning

This Thesis focuses on channel tracking in Orthogonal Frequency-Division Multiplexing (OFDM), a widely-used method of data transmission in wireless communications, when abrupt changes occur in the channel. In highly mobile applications, new dynamics appear that might make channel tracking non-stationary, e.g. channels might vary with location, and location rapidly varies with time. Simple examples might be the di erent channel dynamics a train receiver faces when it is close to a station vs. crossing a bridge vs. entering a tunnel, or a car receiver in a route that grows more tra c-dense. Some of these dynamics can be modelled as channel taps dying or being reborn, and so tap birth-death detection is of the essence. In order to improve the quality of communications, we delved into mathematical methods to detect such abrupt changes in the channel, such as the mathematical areas of Sequential Analysis/ Abrupt Change Detection and Random Set Theory (RST), as well as the engineering advances in Neural Network schemes. This knowledge helped us nd a solution to the problem of abrupt change detection by informing and inspiring the creation of low-complexity implementations for real-world channel tracking. In particular, two such novel trackers were created: the Simpli- ed Maximum A Posteriori (SMAP) and the Neural-Network-switched Kalman Filtering (NNKF) schemes. The SMAP is a computationally inexpensive, threshold-based abrupt-change detector. It applies the three following heuristics for tap birth-death detection: a) detect death if the tap gain jumps into approximately zero (memoryless detection); b) detect death if the tap gain has slowly converged into approximately zero (memory detection); c) detect birth if the tap gain is far from zero. The precise parameters for these three simple rules can be approximated with simple theoretical derivations and then ne-tuned through extensive simulations. The status detector for each tap using only these three computationally inexpensive threshold comparisons achieves an error reduction matching that of a close-to-perfect path death/birth detection, as shown in simulations. This estimator was shown to greatly reduce channel tracking error in the target Signal-to-Noise Ratio (SNR) range at a very small computational cost, thus outperforming previously known systems. The underlying RST framework for the SMAP was then extended to combined death/birth and SNR detection when SNR is dynamical and may drift. We analyzed how di erent quasi-ideal SNR detectors a ect the SMAP-enhanced Kalman tracker's performance. Simulations showed SMAP is robust to SNR drift in simulations, although it was also shown to bene t from an accurate SNR detection. The core idea behind the second novel tracker, NNKFs, is similar to the SMAP, but now the tap birth/death detection will be performed via an arti cial neuronal network (NN). Simulations show that the proposed NNKF estimator provides extremely good performance, practically identical to a detector with 100% accuracy. These proposed Neural-Kalman schemes can work as novel trackers for multipath channels, since they are robust to wide variations in the probabilities of tap birth and death. Such robustness suggests a single, low-complexity NNKF could be reusable over di erent tap indices and communication environments. Furthermore, a di erent kind of abrupt change was proposed and analyzed: energy shifts from one channel tap to adjacent taps (partial tap lateral hops). This Thesis also discusses how to model, detect and track such changes, providing a geometric justi cation for this and additional non-stationary dynamics in vehicular situations, such as road scenarios where re ections on trucks and vans are involved, or the visual appearance/disappearance of drone swarms. An extensive literature review of empirically-backed abrupt-change dynamics in channel modelling/measuring campaigns is included. For this generalized framework of abrupt channel changes that includes partial tap lateral hopping, a neural detector for lateral hops with large energy transfers is introduced. Simulation results suggest the proposed NN architecture might be a feasible lateral hop detector, suitable for integration in NNKF schemes. Finally, the newly found understanding of abrupt changes and the interactions between Kalman lters and neural networks is leveraged to analyze the neural consequences of abrupt changes and brie y sketch a novel, abrupt-change-derived stochastic model for neural intelligence, extract some neuro nancial consequences of unstereotyped abrupt dynamics, and propose a new portfolio-building mechanism in nance: Highly Leveraged Abrupt Bets Against Failing Experts (HLABAFEOs). Some communication-engineering-relevant topics, such as a Bayesian stochastic stereotyper for hopping Linear Gauss-Markov (LGM) models, are discussed in the process. The forecasting problem in the presence of expert disagreements is illustrated with a hopping LGM model and a novel structure for a Bayesian stereotyper is introduced that might eventually solve such problems through bio-inspired, neuroscienti cally-backed mechanisms, like dreaming and surprise (biological Neural-Kalman). A generalized framework for abrupt changes and expert disagreements was introduced with the novel concept of Neural-Kalman Phenomena. This Thesis suggests mathematical (Neural-Kalman Problem Category Conjecture), neuro-evolutionary and social reasons why Neural-Kalman Phenomena might exist and found signi cant evidence for their existence in the areas of neuroscience and nance. Apart from providing speci c examples, practical guidelines and historical (out)performance for some HLABAFEO investing portfolios, this multidisciplinary research suggests that a Neural- Kalman architecture for ever granular stereotyping providing a practical solution for continual learning in the presence of unstereotyped abrupt dynamics would be extremely useful in communications and other continual learning tasks.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Luis Castedo Ribas.- Secretaria: Ana García Armada.- Vocal: José Antonio Portilla Figuera

The Peruvian upwelling ecosystem: dynamics and interactions

Upwelling, Ecosystems, Fishery biology, Fishery oceanography, Conferences, Peru,

The Errant Labor of the Humanities: Festschrift Presented to Stipe Grgas

In preparing this Festschrift, we had in mind a specific inflection of the concept of errancy, one that comes from the rich and layered work of the American scholar and philosopher William V. Spanos, who conceived it as a way of rendering the logos and telos of the American project subject to thorough rethinking and redefinition, both in history and at present. By calling attention to the complementarity of the work of the two scholars, Grgas and Spanos, who both hone their critical skills on the theme of the logic of the American project, we do not so much intend to claim a direct influence but rather wish to highlight the confluence, commingling, and inspiration that working in the humanities may engender. This commonality is featured in the work of Spanos and in the work of Grgas as a dedicated and passionate engagement with the practices and possibilities inscribed in the discipline, which also requires the scholar to move beyond the given and inhabit what Spanos calls a meta-level of thinking. Grgas’s work, located at the intersection of several disciplines within the humanities and social sciences (which is reflected in the principal themes of this Festschrift), reveals precisely such a commitment that has in the course of his long, fruitful and versatile career charted out a scholarly position always in the process of becoming, and never quite stabilized and domesticated. Grgas’s academic career has been as diverse as the humanistic disciplinary habitus allows: a provocative and popular lecturer, a researcher of tireless intellectual curiosity, a scholar testing the boundaries of disciplines, an enthusiastic and motivating mentor, a thoughtful and sensitive translator, or, as one of the contribution shows, an unobtrusive poet, Grgas has always displayed a remarkable intellectual energy in every aspect of his engagement with the varied and nowadays often embattled debates in the humanities. However, Grgas’s work as an Americanist, cultural theorist, translator, writer, mentor, and teacher doesn’t merely reflect the exciting, if uncontainable, shifts marking the discipline in the last couple of decades; rather, his intellectual labor has been committed to offering a new way of comprehending this change, its scope, direction, and consequences, so as to create an intense web of connections and interrelations where different disciplines talk to one another, without hastening to provide answers so much as to provoke the right kind of questions. The questioning and questing nature of Grgas’s work has marked his writing from the start, but it has intensified in his later writing as the humanities find themselves facing a whole new set of questions for the new millennium. His sustained effort to bring a new awareness of economic issues to discussions of culture and literature in the recent period has been both timely and critically engaged in its reflection on why this issue is particularly significant at this point in history. The layout of the Festschrift may be said to loosely reflect and acknowledge Grgas’s scholarly interests that have charted out his career in the field of the humanities. (from the Editors’ Preface)In preparing this Festschrift, we had in mind a specific inflection of the concept of errancy, one that comes from the rich and layered work of the American scholar and philosopher William V. Spanos, who conceived it as a way of rendering the logos and telos of the American project subject to thorough rethinking and redefinition, both in history and at present. By calling attention to the complementarity of the work of the two scholars, Grgas and Spanos, who both hone their critical skills on the theme of the logic of the American project, we do not so much intend to claim a direct influence but rather wish to highlight the confluence, commingling, and inspiration that working in the humanities may engender. This commonality is featured in the work of Spanos and in the work of Grgas as a dedicated and passionate engagement with the practices and possibilities inscribed in the discipline, which also requires the scholar to move beyond the given and inhabit what Spanos calls a meta-level of thinking. Grgas’s work, located at the intersection of several disciplines within the humanities and social sciences (which is reflected in the principal themes of this Festschrift), reveals precisely such a commitment that has in the course of his long, fruitful and versatile career charted out a scholarly position always in the process of becoming, and never quite stabilized and domesticated. Grgas’s academic career has been as diverse as the humanistic disciplinary habitus allows: a provocative and popular lecturer, a researcher of tireless intellectual curiosity, a scholar testing the boundaries of disciplines, an enthusiastic and motivating mentor, a thoughtful and sensitive translator, or, as one of the contribution shows, an unobtrusive poet, Grgas has always displayed a remarkable intellectual energy in every aspect of his engagement with the varied and nowadays often embattled debates in the humanities. However, Grgas’s work as an Americanist, cultural theorist, translator, writer, mentor, and teacher doesn’t merely reflect the exciting, if uncontainable, shifts marking the discipline in the last couple of decades; rather, his intellectual labor has been committed to offering a new way of comprehending this change, its scope, direction, and consequences, so as to create an intense web of connections and interrelations where different disciplines talk to one another, without hastening to provide answers so much as to provoke the right kind of questions. The questioning and questing nature of Grgas’s work has marked his writing from the start, but it has intensified in his later writing as the humanities find themselves facing a whole new set of questions for the new millennium. His sustained effort to bring a new awareness of economic issues to discussions of culture and literature in the recent period has been both timely and critically engaged in its reflection on why this issue is particularly significant at this point in history. The layout of the Festschrift may be said to loosely reflect and acknowledge Grgas’s scholarly interests that have charted out his career in the field of the humanities. (from the Editors’ Preface

Proteomic insights into the modulation of foetal neurogenesis by the anti-retroviral efavirenz

Background: South African guidelines recommend that HIV-positive pregnant women immediately initiate antiretroviral therapy (efavirenz, emtricitabine, and tenofovir), regardless of trimester. Efavirenz causes central nervous system neuropathy and has been linked to birth defects such as encephalocoele. Cohort studies of HIV-uninfected children exposed to antiretroviral treatment in utero report minor learning delays but are inconclusive. Non-transformed human derived neuroepithelial stem (NES) represent a unique pre-clinical model in which to investigate the effects of efavirenz on the developing neural system. Efavirenz-induced global cellular molecular changes may be characterised using mass spectrometry (MS). Aims: To optimise an MS-based efavirenz extraction and detection assay, and to investigate efavirenzinduced NES proteomic responses. Methods: A TSQ Vantage triple quadrupole mass spectrometer was employed to optimise targeted detection of efavirenz extracted from cultured cells and supernatant. Cells were cultured for 72 hours, incorporating a 24-hourly efavirenz treatment. Efavirenz concentration dynamics were assessed over this period, and cells were harvested every 24 hours for discovery proteomic analysis using a Q-Exactive quadrupole-Orbitrap mass spectrometer. Results: Drug extraction with acetonitrile was selected as the optimal extraction and detection technique. In cell culture, efavirenz concentration increased after 24 hours and decreased after 48 hours. A total of 1663 protein groups were identified, with 26, 39, and 80 protein groups differentially expressed 24, 48, and 72 hours respectively post EFV treatment. The most significantly enriched deregulated pathways included cholesterol biosynthesis, mRNA splicing, and JAK/STAT and Wnt signalling. Conclusions: Efavirenz-altered protein expression reflects functional pathway perturbations, which may contribute to clinically-observed neurological effects. Orthoganal and in vivo confirmation is required

The Errant Labor of the Humanities: Festschrift Presented to Stipe Grgas

In preparing this Festschrift, we had in mind a specific inflection of the concept of errancy, one that comes from the rich and layered work of the American scholar and philosopher William V. Spanos, who conceived it as a way of rendering the logos and telos of the American project subject to thorough rethinking and redefinition, both in history and at present. By calling attention to the complementarity of the work of the two scholars, Grgas and Spanos, who both hone their critical skills on the theme of the logic of the American project, we do not so much intend to claim a direct influence but rather wish to highlight the confluence, commingling, and inspiration that working in the humanities may engender. This commonality is featured in the work of Spanos and in the work of Grgas as a dedicated and passionate engagement with the practices and possibilities inscribed in the discipline, which also requires the scholar to move beyond the given and inhabit what Spanos calls a meta-level of thinking. Grgas’s work, located at the intersection of several disciplines within the humanities and social sciences (which is reflected in the principal themes of this Festschrift), reveals precisely such a commitment that has in the course of his long, fruitful and versatile career charted out a scholarly position always in the process of becoming, and never quite stabilized and domesticated. Grgas’s academic career has been as diverse as the humanistic disciplinary habitus allows: a provocative and popular lecturer, a researcher of tireless intellectual curiosity, a scholar testing the boundaries of disciplines, an enthusiastic and motivating mentor, a thoughtful and sensitive translator, or, as one of the contribution shows, an unobtrusive poet, Grgas has always displayed a remarkable intellectual energy in every aspect of his engagement with the varied and nowadays often embattled debates in the humanities. However, Grgas’s work as an Americanist, cultural theorist, translator, writer, mentor, and teacher doesn’t merely reflect the exciting, if uncontainable, shifts marking the discipline in the last couple of decades; rather, his intellectual labor has been committed to offering a new way of comprehending this change, its scope, direction, and consequences, so as to create an intense web of connections and interrelations where different disciplines talk to one another, without hastening to provide answers so much as to provoke the right kind of questions. The questioning and questing nature of Grgas’s work has marked his writing from the start, but it has intensified in his later writing as the humanities find themselves facing a whole new set of questions for the new millennium. His sustained effort to bring a new awareness of economic issues to discussions of culture and literature in the recent period has been both timely and critically engaged in its reflection on why this issue is particularly significant at this point in history. The layout of the Festschrift may be said to loosely reflect and acknowledge Grgas’s scholarly interests that have charted out his career in the field of the humanities. (from the Editors’ Preface)In preparing this Festschrift, we had in mind a specific inflection of the concept of errancy, one that comes from the rich and layered work of the American scholar and philosopher William V. Spanos, who conceived it as a way of rendering the logos and telos of the American project subject to thorough rethinking and redefinition, both in history and at present. By calling attention to the complementarity of the work of the two scholars, Grgas and Spanos, who both hone their critical skills on the theme of the logic of the American project, we do not so much intend to claim a direct influence but rather wish to highlight the confluence, commingling, and inspiration that working in the humanities may engender. This commonality is featured in the work of Spanos and in the work of Grgas as a dedicated and passionate engagement with the practices and possibilities inscribed in the discipline, which also requires the scholar to move beyond the given and inhabit what Spanos calls a meta-level of thinking. Grgas’s work, located at the intersection of several disciplines within the humanities and social sciences (which is reflected in the principal themes of this Festschrift), reveals precisely such a commitment that has in the course of his long, fruitful and versatile career charted out a scholarly position always in the process of becoming, and never quite stabilized and domesticated. Grgas’s academic career has been as diverse as the humanistic disciplinary habitus allows: a provocative and popular lecturer, a researcher of tireless intellectual curiosity, a scholar testing the boundaries of disciplines, an enthusiastic and motivating mentor, a thoughtful and sensitive translator, or, as one of the contribution shows, an unobtrusive poet, Grgas has always displayed a remarkable intellectual energy in every aspect of his engagement with the varied and nowadays often embattled debates in the humanities. However, Grgas’s work as an Americanist, cultural theorist, translator, writer, mentor, and teacher doesn’t merely reflect the exciting, if uncontainable, shifts marking the discipline in the last couple of decades; rather, his intellectual labor has been committed to offering a new way of comprehending this change, its scope, direction, and consequences, so as to create an intense web of connections and interrelations where different disciplines talk to one another, without hastening to provide answers so much as to provoke the right kind of questions. The questioning and questing nature of Grgas’s work has marked his writing from the start, but it has intensified in his later writing as the humanities find themselves facing a whole new set of questions for the new millennium. His sustained effort to bring a new awareness of economic issues to discussions of culture and literature in the recent period has been both timely and critically engaged in its reflection on why this issue is particularly significant at this point in history. The layout of the Festschrift may be said to loosely reflect and acknowledge Grgas’s scholarly interests that have charted out his career in the field of the humanities. (from the Editors’ Preface

2014 GREAT Day Program

SUNY Geneseo’s Eighth Annual GREAT Day.https://knightscholar.geneseo.edu/program-2007/1008/thumbnail.jp