Growth rates of icicles

Experimental and theoretical studies on the growth rate of an icicle were carried out as a function of temperature, water-supply rate and wind speed; the relative humidity was also taken into account. The length of an icicle increases by the downward growth of thin dendritic crystals into the supercooled pendant water drop at the tip, and thus the growth is in the crystallographic a-axis direction. The diameter, on the other hand, increases by the freezing of a water film flowing down along the icicle wall. The ratio of measured length-and diameter-growth rates was large, namely 8–32.Both growth rates increased with decreasing temperature and increasing wind speed. The increase in water-supply rate led to the decrease in the length-growth rate but no significant change in the diameter-growth rate. These results could be well described by a numerical model of icicle growth which takes account of the dendritic growth at the tip and the wall and the effective heat transfer within the turbulent boundary layer around the icicle. A formation mechanism of ribs and hollows is discussed in relation to the flowing and freezing process of water on an icicle wall

Intact carcasses as enrichment for large felids: Effects on on- and off-exhibit behaviors

Reducing stereotypic behaviors in captive animals is a goal for zoological institutions worldwide, and environmental enrichment is one tool commonly used to meet that end. Behavioral needs associated with feeding, however, are often neglected in large carnivores. To address these needs, I tested the effects of calf carcasses as enrichment for large felids. Over 14 weeks, I provided nine animals with up to seven intact carcasses. The cats were housed at Toledo Zoo, Potawatomi Zoo, and Binder Park Zoo. Animals were observed off and on exhibit for changes in feeding, natural, stereotypic, active, and inactive behaviors. I compared treatment behaviors with behaviors observed during a baseline period in which the animals were fed traditional processed diets. For these nine cats, carcass provision decreased off-exhibit stereotypic behaviors but had little impact on on-exhibit behaviors. Zoo Biol 21:37–47, 2002. © 2002 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34915/1/10033_ftp.pd

Gap Detection in Auditory Cortex

33 pages. A thesis presented to the Department of Chemistry and Biochemistry and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016.Strong evidence supports that for older adults, hearing loss and difficulty with speech comprehension in noisy environments is the result of temporal processing deficits in central auditory structures such as the auditory cortex. There is a general canonical circuit model of layer by layer serial information flow through the auditory cortex from the thalamus, before information is projected back into inferior colliculus neurons. However the specific cortical circuits and cell types which regulate temporal processing through the auditory cortex are still unknown and not linked to behavior. The auditory cortex contributes to temporal acuity in receiving auditory stimuli. Temporal acuity is used, for example, for brief noise gap detection and discriminating between similar phonemes. Impairments to temporal activity can cause speech perception deficits. In this study, I tested gap detection behavior in mice. To do this, I measured how their startle responses were modulated by gaps in continuous background noise. The presence of the gap attenuates the startle response to the stimulus, so that measuring the startle response gives a measure of temporal acuity by assessing gap detection behavior. I used a technology called optogenetics to manipulate brain activity during this behavior. Optogenetics allows for the gaps to be paired with a laser pulse that silences auditory cortex neurons and allowed me to see how gap detection is impaired by temporally precise suppression of auditory cortex. By probing cortex circuit mechanisms through layer-specific optogenetic silencing before and after gap, I found that layer-specific silencing of auditory cortex neuron populations in layers four and five suggests behavior in accordance with the canonical model

The Mountain Stairway A Translation of Alai\u27s Travelogue of Tibet

Senior Project submitted to The Division of Languages and Literature of Bard College

Alai’s The Mountain Stairway: A Grassroots Conception of Tibet

It seems that the current literature regarding Tibet is quite impoverished as a true cultural indicator of the region and its people. The West writes of Tibet as an exotic solution to its own malaise, or as the last refuge of Hermetic wisdom. The Han Chinese have used Tibet as a muse and as an antidote to materialism. The current literary criticism brushes over cultural and stylistic concerns to cut right to politics. In every case, Tibet as a cultural concept is simply used to complement something external to it, to stand in contrast to something else. The Tibetan writer Alai specifically rejects these negative and meaningless definitions of Tibet

Study of various structures of actuators for positioning in aeronautics

Pour certaines applications de positionnement dans les systèmes embarqués la puissance ou les couples mis jeu en peuvent être faibles. Les actionneurs utilisés pour ces applications sont équipés de machines pas à pas telles que les machines réluctance variable excitées ou non, ou encore des machines synchrones à aimants permanents. En aéronautique, ces actionneurs doivent être les plus compacts possibles et la continuité de service est exigée. La redondance partielle ou totale de l'actionneur est solution permettant d'assurer la continuité de service. Nous avons étudiés plusieurs structures de machines notamment les machines à deux voies d'enroulement pour leurs compacité telles les machines à reluctance variable à excitation homopolaire (MRVH-2C) et les machines synchrones à aimants permanent (MSAP-DE). Dans le but faciliter ou motiver le choix de l'une ou l'autre des structures, nous avons développé des modèles de machines capables de fournir des informations sur les grandeurs mesurables ou non, et sur le comportement des actionneurs. Ainsi à partir d'un calcul éléments finis 2D nous avons mis au point plusieurs modèles couplés EF 2D réseau de perméances de la MRVH-2C qui tiennent compte de l'état de saturation magnétique et du caractère tridimensionnel de cette machine. Ceux-ci ont été utilisés pour simuler le comportement de l'actionneur dans différents situations. Toujours pour une application de positionnement à faibles puissance et basse vitesse, nous avons dimensionné, modélisé et simulé une MSAP-DE commandée en boucle fermée et qui, de façon intrinsèque tolère le défaut de court-circuit triphasé grâce à sa résistance de phase qui est élevéeFor certain applications of positioning in embedded systems power or torque needed can be low. Actuators used for these applications can be equipped with stepper machinery such as variable reluctance machines excited (or not) or permanent magnets synchronous machine. In aeronautic these actuators should be as compact as possible and continuity of service is required. Partial or total redundancy of the actuator can ensure the continuity of service. We have studied various structures of machines particularly double channel machines for their compactness such as two channels hybrid variable reluctance machines (2C-HVRM) and double channel permanent magnets synchronous machines (DC-PMSM). In the aim of facilitating or of justifying the choice of one or the other of these structures, we have developed models of able to provide information on measurable (or non measurable) features, and the behavior of the actuators. So from a 2D finite element calculation we have developed several coupled 2D FE permeances network models of a 2C-HVRM tacking account of the magnetic saturation state of this machine and its three-dimensional character. These models were used to simulate the behavior of the actuator in different situations. Always for positioning application with low power and low speed, we sized, modeled and simulated a DC-PMSM close loop controlled. That machine is intrinsically tolerant to phase short-circuit fault, thanks to its high phase resistanc

Étude des différentes structures d'actionneurs de positionnement pour l'aéronautique

For certain applications of positioning in embedded systems power or torque needed can be low. Actuators used for these applications can be equipped with stepper machinery such as variable reluctance machines excited (or not) or permanent magnets synchronous machine. In aeronautic these actuators should be as compact as possible and continuity of service is required. Partial or total redundancy of the actuator can ensure the continuity of service. We have studied various structures of machines particularly double channel machines for their compactness such as two channels hybrid variable reluctance machines (2C-HVRM) and double channel permanent magnets synchronous machines (DC-PMSM). In the aim of facilitating or of justifying the choice of one or the other of these structures, we have developed models of able to provide information on measurable (or non measurable) features, and the behavior of the actuators. So from a 2D finite element calculation we have developed several coupled 2D FE permeances network models of a 2C-HVRM tacking account of the magnetic saturation state of this machine and its three-dimensional character. These models were used to simulate the behavior of the actuator in different situations. Always for positioning application with low power and low speed, we sized, modeled and simulated a DC-PMSM close loop controlled. That machine is intrinsically tolerant to phase short-circuit fault, thanks to its high phase resistancePour certaines applications de positionnement dans les systèmes embarqués la puissance ou les couples mis jeu en peuvent être faibles. Les actionneurs utilisés pour ces applications sont équipés de machines pas à pas telles que les machines réluctance variable excitées ou non, ou encore des machines synchrones à aimants permanents. En aéronautique, ces actionneurs doivent être les plus compacts possibles et la continuité de service est exigée. La redondance partielle ou totale de l'actionneur est solution permettant d'assurer la continuité de service. Nous avons étudiés plusieurs structures de machines notamment les machines à deux voies d'enroulement pour leurs compacité telles les machines à reluctance variable à excitation homopolaire (MRVH-2C) et les machines synchrones à aimants permanent (MSAP-DE). Dans le but faciliter ou motiver le choix de l'une ou l'autre des structures, nous avons développé des modèles de machines capables de fournir des informations sur les grandeurs mesurables ou non, et sur le comportement des actionneurs. Ainsi à partir d'un calcul éléments finis 2D nous avons mis au point plusieurs modèles couplés EF 2D réseau de perméances de la MRVH-2C qui tiennent compte de l'état de saturation magnétique et du caractère tridimensionnel de cette machine. Ceux-ci ont été utilisés pour simuler le comportement de l'actionneur dans différents situations. Toujours pour une application de positionnement à faibles puissance et basse vitesse, nous avons dimensionné, modélisé et simulé une MSAP-DE commandée en boucle fermée et qui, de façon intrinsèque tolère le défaut de court-circuit triphasé grâce à sa résistance de phase qui est élevé

Dissecting the Cortical Canonical Circuit of Auditory Cortex to Understand Gap Detection

Single page posterSpeech comprehension requires processing sound information with a high degree of temporal precision. As a standard metric for assessing temporal acuity, gap detection allows us to understand the neural circuitry involved in such everyday speech processing. Additionally, achieving the finest levels of temporal acuity requires cortical involvement. In the present study, we used a transgenic technique known as optogenetics to manipulate activity in specific subsets of cortical neurons to better understand how cells in different layers of the auditory cortex contribute to brief gap detection. We have also applied neuroanatomical techniques to better understand the position of these populations of cells within the cortical circuit. One such technique utilized fluorescent beads that were retrogradely transported from inferior colliculus and medial geniculate to auditory cortex. This study allows us to verify the cortical canonical circuit in speech processing as well as shed some light on how changes in cortical function contribute to speech pathologies

Dissecting the Cortical Canonical Circuit of Auditory Cortex to Understand Gap Detection

Single page posterSpeech comprehension requires processing sound information with a high degree of temporal precision. As a standard metric for assessing temporal acuity, gap detection allows us to understand the neural circuitry involved in such everyday speech processing. Additionally, achieving the finest levels of temporal acuity requires cortical involvement. In the present study, we used a transgenic technique known as optogenetics to manipulate activity in specific subsets of cortical neurons to better understand how cells in different layers of the auditory cortex contribute to brief gap detection. We have also applied neuroanatomical techniques to better understand the position of these populations of cells within the cortical circuit. One such technique utilized fluorescent beads that were retrogradely transported from inferior colliculus and medial geniculate to auditory cortex. This study allows us to verify the cortical canonical circuit in speech processing as well as shed some light on how changes in cortical function contribute to speech pathologies