The Neural Representation of Concepts at the Sensor Level

This report presents a mathematical model of the semantics, or meaning, of the connec-tionist structure and stimulus activity of a neural network, whether artificial or biologi-cal. The mathematical model associates concepts about sensed objects with the neuron-like nodes in a neural network and composable concept relationships with the connec-tion pathways in the network. Category-theoretic constructs, specifically colimits, limits, and functors, organize the concept structure and map it to a formal neural network in a structure-preserving manner. Starting with a simple example of a neural vision system, we show that this mathematical model of neural network structure and activity can be used to derive connectionist architectures that work as intended. We also claim an additional advantage of this approach: A properly-functioning connectionist architecture has an ac-companying concept representation and this representation is both local and distributed. These properties are derived from the category-theoretic formalism described here

Alignment verification for electron beam lithography

Alignment between lithography layers is essential for device fabrication. A minor defect in a single marker can lead to incorrect alignment and this can be the source of wafer reworks. In this paper we show that this can be prevented by using extra alignment markers to check the alignment during patterning, rather than inspecting vernier patterns after the exposure is completed. Accurate vernier patterns can often only be read after pattern transfer has been carried out. We also show that by using a Penrose tile as a marker it is possible to locate the marker to about 1 nm without fully exposing the resist. This means that the marker can be reused with full accuracy, thus improving the layer to layer alignment accuracy. Lithography tool noise limits the process

Understanding Student Computational Thinking with Computational Modeling

Recently, the National Research Council's framework for next generation science standards highlighted "computational thinking" as one of its "fundamental practices". 9th Grade students taking a physics course that employed the Modeling Instruction curriculum were taught to construct computational models of physical systems. Student computational thinking was assessed using a proctored programming assignment, written essay, and a series of think-aloud interviews, where the students produced and discussed a computational model of a baseball in motion via a high-level programming environment (VPython). Roughly a third of the students in the study were successful in completing the programming assignment. Student success on this assessment was tied to how students synthesized their knowledge of physics and computation. On the essay and interview assessments, students displayed unique views of the relationship between force and motion; those who spoke of this relationship in causal (rather than observational) terms tended to have more success in the programming exercise.Comment: preprint to submit to PERC proceedings 201

An Archaeological Survey of a Portion of the Choke Canyon Reservoir Area in McMullen and Live Oak Counties, Texas

An intensive cultural resource survey was carried out on approximately 2544 hectares (6285 acres) of the proposed Choke Canyon Reservoir by the Cultural Resources Institute (CRI) of Texas Tech University from August through October 1977. The project was undertaken in response to needs of the Bureau of Reclamation. This report is one of a multivolume study.\u27concerning the area\u27s cultural resources. During the 1977 survey, 113 archaeological sites, 42 low density artifact scatters, and five isolated finds were located and recorded. A no-collection policy was maintained, except isolated finds. In the late fall 1977, 15 of the recorded sites were subjected to limited testing activities. The cultural resources recorded during the survey document the presence of human groups in the reservoir beginning in late Paleo-Indian times and extending to the present. Based upon the limited occurrence of diagnostic artifacts, most of the prehistoric occupation occurred during the Archaic. Historic sites recorded were occupied primarily during the last quarter of the 19th century and the first quarter of the 20th century. This report documents the research design and particularly the methodology utilized during the project. Special emphasis is given to describing the systematic and intensive survey, as well as to the random/judgmental approach of selecting the various sites for limited testing. Cultural material recovered during testing activities are described in techno-morphological terms. The nature of survey projects in general and the paucity of reliable time markers recovered during field work severely limited the development of a cultural chronology for the study area. Research efforts resulted in the developmert of a model of lithic technology based on the ready availability of raw materials. Also presented is a settlement and subsistence pattern model which is based primarily on a rainy and dry season dichotomy and the availability of food resources.

Peer Evaluation of Video Lab Reports in a Blended Introductory Physics Course

The Georgia Tech blended introductory calculus-based mechanics course emphasizes scientific communication as one of its learning goals, and to that end, we gave our students a series of four peer-evaluation assignments intended to develop their abilities to present and evaluate scientific arguments. Within these assignments, we also assessed students' evaluation abilities by comparing their evaluations to a set of expert evaluations. We summarize our development efforts and describe the changes we observed in student evaluation behavior.Comment: 4 pages, 1 table, 2 figures, submitted to Summer 2014 PERC Proceeding

The Initial State of Students Taking an Introductory Physics MOOC

As part of a larger research project into massively open online courses (MOOCs), we have investigated student background, as well as student participation in a physics MOOC with a laboratory component. Students completed a demographic survey and the Force and Motion Conceptual Evaluation at the beginning of the course. While the course is still actively running, we have tracked student participation over the first five weeks of the eleven-week course.Comment: Accepted to PERC Proceedings 201

Doubling Down on Wicked Problems: Ocean ArtScience Collaborations for a Sustainable Future

The UN Decade of Ocean Science for Sustainable Development recognizes the current ocean sustainability crisis and calls for a transformation of ocean science. Many of the key challenges recognized by the UN Decade are examples of wicked problems: intractable and messy situations with high stakeholder divergence. Addressing wicked ocean sustainability problems requires adaptable, iterative, and participatory approaches that can embrace multiple ways of knowing. It also requires a re-imagining of our relationship with the Ocean from extraction and resulting environmental degradation, towards the building of a sense of connection and stewardship. We propose ArtScience as a means to this end by highlighting how transdisciplinary collaborations can help create sustainable ocean futures. We reflect on a recent ArtScience event emerging from Ocean Networks Canada’s Artist-in-Residence programme. By situating ArtScience in a broader context of inter- and transdisciplinary collaborations, we demonstrate how ArtScience collaborations can help transform ocean science by envisioning previously unimagined possibilities, and establishing and strengthening relationships with diverse stakeholders through long-term mission-driven or place-based inquiry. We conclude with a call to action to acknowledge the potential these collaborations hold for addressing the challenges of the UN Ocean Decade

Functional Mutations Form at CTCF-Cohesin Binding Sites in Melanoma Due to Uneven Nucleotide Excision Repair across the Motif

© 2016 The Author(s) CTCF binding sites are frequently mutated in cancer, but how these mutations accumulate and whether they broadly perturb CTCF binding are not well understood. Here, we report that skin cancers exhibit a highly specific asymmetric mutation pattern within CTCF motifs attributable to ultraviolet irradiation and differential nucleotide excision repair (NER). CTCF binding site mutations form independently of replication timing and are enriched at sites of CTCF/cohesin complex binding, suggesting a role for cohesin in stabilizing CTCF-DNA binding and impairing NER. Performing CTCF ChIP-seq in a melanoma cell line, we show CTCF binding site mutations to be functional by demonstrating allele-specific reduction of CTCF binding to mutant alleles. While topologically associating domains with mutated CTCF anchors in melanoma contain differentially expressed cancer-associated genes, CTCF motif mutations appear generally under neutral selection. However, the frequency and potential functional impact of such mutations in melanoma highlights the need to consider their impact on cellular phenotype in individual genomes.Link_to_subscribed_fulltex