The Effects of Object Weight and Three-Dimensional Movement on Human Movement Time and Fitts\u27 Law

The speed and accuracy of movement depend on several factors that have been previously identified including target size and movement amplitude. According to Fitts\u27 Law these variables comprise an Index of Difficulty that is directly related to the movement time. This principle of human performance has been studied extensively over a wide array of settings and contexts. The objective of this thesis was to investigate human movement time for tasks requiring precision placement of weighted objects, a task frequently encountered in industrial and occupational settings. Specifically, this thesis evaluated the effects of object weight, complexity of movement, and handedness on movement time. Complex movement in three dimensions and use of the dominant hand was found to significantly decrease movement time. It was also found that as probe weight increased, movement time increased in a logarithmic pattern. Fitts\u27 Law in its original form was found to be an accurate predictor of overall movement time for the data obtained in this study. However, Fitts\u27 original equations were improved by incorporating a term that accounted for the weight of the probe. The theoretical and practical implications of these results are discussed

The Impacts of Maturation and Experience on Volumetric Neuroplasticity in Solitary and Social Bees

Some animals are incredibly social, living and working together as one cohesive group. Alternatively, many animals are solitary, never living with and rarely interacting with others. A large body of biological research has focused on understanding the role that brains play in promoting these behavioral differences across species. Even so, it remains unclear why some brains facilitate social behavior while others do not. My dissertation aims to advance our understanding of this concept by characterizing bees’ brains and how they change over a lifetime. Bees are beneficial for investigating relationships between the brain and social behavior because some species are solitary while others are highly social. However, sociality in bees is more dynamic than that; a blending of these two extremes can also occur. This enables us to explore how brains change with social context within a single group of organisms. My first chapter uses a solitary bee to understand how simple social interactions can impact the brain. I found that—even in a solitary bee—certain brain regions grow in size in response to the presence of other bees. This trait may have been important in the evolutionary origins of social behavior. My second chapter investigated the effects of aging in the brains of two bee species, one that is sometimes social while the other is always social. I found that the brains of these species naturally change over time, a feature common to highly social species, e.g., honey bees. This suggests that having brains that change with age may be an important feature of sociality. My final research chapter made comparisons between queen and worker bees to investigate if their colony roles and behaviors dictated the relative size of different regions of their brains. I found that queen and worker brains respond differently to removing offspring care, a trait fundamental to defining their role in the colony. This highlights a potentially unique relationship between the brain and social life. Collectively, my dissertation used bees to enhance our understanding of what it means to have a social brain

Financial Literacy Initiative at a Liberal Arts College: What Student’s Want (& Need)!

The college years are an important time in the life of young adults as they are faced for the first time with important personal financial decisions. Since they have reached the legal age to enter into binding contracts, these decisions have potential long-term negative consequences. Students are graduating with large amounts of debt and starting out in their careers with very limited spending which impacts their ability to obtain car or home loans (“Financial Literacy,” 2014). Education institutions play an important role in developing financially literate citizens. This paper discusses the need and interest in a financial literacy program at a small liberal arts college in Virginia

Hypothesized Cambrian medusae from Saint John, New Brunswick, reinterpreted as sedimentary structures

More than a hundred radial and discoidal structures occur on bed tops of shales and very fine sandstones of the Cambrian (Series 3) King Square Formation in New Brunswick, Canada. These structures typically contain a central sediment plug, radial lineations that extend outward from the central plug, concentric rings, and a broad trough surrounding or underlying ring margins. Originally interpreted as fossils of scyphozoan medusae, these structures could represent one of only a half-dozen mass strandings documented from the fossil record. Instead, re-evaluation of their sedimentology and morphology suggests that they are likely sedimentary structures known as Astropolithon. These sand-volcano-like structures formed by subsurface blistering, cracking, and failure of a near-surface or surface bed, triggered by the upward movement of gases or other fluids from underlying beds. RÉSUMÉ Plus d’une centaine de structures radiales et discoïdes apparaissent au sommet des couches de schiste et de grès très fins de la formation King Square du Cambrien (Série 3), du Nouveau-Brunswick, au Canada. Ces structures contiennent généralement un culot sédimentaire central, des linéaments radiaux qui se déploient vers l’extérieur à partir du culot central, des anneaux concentriques, et une vaste cuvette qui ceinture le bord des anneaux ou qui se trouve en dessous. On estimait initialement qu’il s’agissait de méduses scyphozoaires, mais ces structures pourraient correspondre à l’une de la demi-douzaine d’échouages massifs de l’ichnofaune dont les vestiges fossiles ont été retrouvés. La réévaluation de leur contexte de sédimentation et de leur morphologie porte plutôt à croire que ce sont vraisemblablement des structures sédimentaires connues sous le nom d’astropolithon. Ces structures apparentées à un volcan de sable ont été formées par l’apparition d’alvéoles souterraines, le fendillement et la rupture d’une couche près de la surface ou à la surface, et qu’aurait provoquée le déplacement vers la surface de gaz ou d’autres fluides provenant des couches inférieures. [Traduit par la redaction

NFMA in Relation to Stewardship, Science, Community and Culture: Some Points of View from the Alaska Region

10 pages

First-principles investigation of spin polarized conductance in atomic carbon wire

We analyze spin-dependent energetics and conductance for one dimensional (1D) atomic carbon wires consisting of terminal magnetic (Co) and interior nonmagnetic (C) atoms sandwiched between gold electrodes, obtained employing first-principles gradient corrected density functional theory and Landauer's formalism for conductance. Wires containing an even number of interior carbon atoms are found to be acetylenic with sigma-pi bonding patterns, while cumulene structures are seen in wires containing odd number of interior carbon atoms, as a result of strong pi-conjugation. Ground states of carbon wires containing up to 13 C atoms are found to have anti-parallel spin configurations of the two terminal Co atoms, while the 14 C wire has a parallel Co spin configuration in the ground state. The stability of the anti-ferromagnetic state in the wires is ascribed to a super-exchange effect. For the cumulenic wires this effect is constant for all wire lengths. For the acetylenic wires, the super-exchange effect diminishes as the wire length increases, going to zero for the atomic wire containing 14 carbon atoms. Conductance calculations at the zero bias limit show spin-valve behavior, with the parallel Co spin configuration state giving higher conductance than the corresponding anti-parallel state, and a non-monotonic variation of conductance with the length of the wires for both spin configurations.Comment: revtex, 6 pages, 5 figure

Remarkable preservation of microbial mats in Neoproterozoic siliciclastic settings : Implications for Ediacaran taphonomic models

The authors thank Duncan McIlroy and Alex Liu for their discussions, help, comments and field support, the National Trust for access to Longmyndian localities, and the staff of the British Geological Survey Palaeontology unit and the Oxford University Museum of Natural History for their assistance with access to materials. The comments and suggestions of two anonymous reviewers and Nora Noffke significantly improved the manuscript.Peer reviewedPostprin

Exercise: Analyze Archival Sources

This exercise provides an opportunity for researchers to practice their skills in archival analysis

Experience, but Not Age, is Associated With Volumetric Mushroom Body Expansion in Solitary Alkali Bees

In social insects, changes in behavior are often accompanied by structural changes in the brain. This neuroplasticity may come with experience (experience-dependent) or age (experience-expectant). Yet, the evolutionary relationship between neuroplasticity and sociality is unclear, because we know little about neuroplasticity in the solitary relatives of social species. We used confocal microscopy to measure brain changes in response to age and experience in a solitary halictid bee (Nomia melanderi). First, we compared the volume of individual brain regions among newly emerged females, laboratory females deprived of reproductive and foraging experience, and free-flying, nesting females. Experience, but not age, led to significant expansion of the mushroom bodies – higher-order processing centers associated with learning and memory. Next, we investigated how social experience influences neuroplasticity by comparing the brains of females kept in the laboratory either alone or paired with another female. Paired females had significantly larger olfactory regions of the mushroom bodies. Together, these experimental results indicate that experience-dependent neuroplasticity is common to both solitary and social taxa, whereas experience-expectant neuroplasticity may be an adaptation to life in a social colony. Further, neuroplasticity in response to social chemical signals may have facilitated the evolution of sociality