Late Quaternary glacial and periglacial environments, Snake Range, Nevada

Limited research has been conducted on the paleoclimatic significance of glacial and periglacial features in the Great Basin. Glacial features in the range were first recognized and described by early explorers (Gilbert, 1875; Simpson; 1876 and Russell, 1884) and subsequent authors have continued to substantiate and elaborate on earlier reports (Heald, 1956; Kramer, 1962; Currey, 1969; Peigat, 1980; Osborn and Bevis, 2001). Since this early reconnaissance work, few studies have focused on the Late Quaternary evolution and paleoclimatic implications of glacial and periglacial landforms in the Great Basin (Wayne, 1983; Osborn, 1989; Bevis, 1995; and Osborn and Bevis, 2001). Wayne (1984) describes relict rock glaciers, sorted circles, debris islands, solifluction lobes and sorted stripes in the Ruby, Schell Creek, and Snake ranges. While Currey (1969) and Osborn and Bevis, (2001) discuss the distribution of rock glaciers in numerous ranges throughout the Great Basin, including the Snake Range, and the surrounding regions; This study presents new data on the glacial and periglacial Late Quaternary conditions in the interior Great Basin based on studies carried out in the Snake Range, located in east-central Nevada. I propose the Lehman rock glacier is an ice-cemented landform that evolved via a recessional genesis, contrary to present glacial or periglacial models that primarily propose constructional geneses for rock glaciers. Preliminary GPR evidence suggests the Lehman rock glacier may retain interstitial lenses of ice; remnant ice that has stagnated under modern climate conditions; The spatial distribution of both glacial and periglacial landforms provides paleoclimatic information derived using field evidence and computer modeling. Neoglacial temperature depression estimates calculated using modern freezing and thawing indices for relict rock glaciers, range from -0.25°C to -1.00°C while temperature estimates calculated using the methodology described by Frauenfelder and Kaab, (2000) and Frauenfelder et al., (2001) are 0.35 to 0.97 degrees lower than those calculated using freezing and thawing indices. Full Glacial MAAT depression estimates range from approximately -5.16°C to -6.61°C calculated using periglacial landforms, to approximately -4.55°C to -5.77°C, calculated from reconstructed Angel Lake equilibrium line altitudes (ELAs); Finally, using scanning electron microscopy, it is possible to differentiate between a glacial and non-glacial origin for pebbles and cobbles entrained in enigmatic sedimentary deposits is a useful tool. Each depositional environment creates distinct micro-features that can be identified and used to establish a glacial or non-glacial history

Demonstration of the Effect of Stirring on Nucleation from Experiments on the International Space Station Using the ISS-EML Facility

The effect of fluid flow on crystal nucleation in supercooled liquids is not well understood. The variable density and temperature gradients in the liquid make it difficult to study this under terrestrial gravity conditions. Nucleation experiments were therefore made in a microgravity environment using the Electromagnetic Levitation Facility on the International Space Station on a bulk glass-forming Zr57Cu15.4Ni12.6Al10Nb5 (Vit106), as well as Cu50Zr50 and the quasicrystal-forming Ti39.5Zr39.5Ni21 liquids. The maximum supercooling temperatures for each alloy were measured as a function of controlled stirring by applying various combinations of radio-frequency positioner and heater voltages to the water-cooled copper coils. The flow patterns were simulated from the known parameters for the coil and the levitated samples. The maximum nucleation temperatures increased systematically with increased fluid flow in the liquids for Vit106, but stayed nearly unchanged for the other two. These results are consistent with the predictions from the Coupled-Flux model for nucleation

Demonstration of the effect of stirring on nucleation from experiments on the International Space Station using the ISS-EML facility

The effect of fluid flow on crystal nucleation in supercooled liquids is not well understood. The variable density and temperature gradients in the liquid make it difficult to study this under terrestrial gravity conditions. Nucleation experiments were therefore made in a microgravity environment using the Electromagnetic Levitation facility on the International Space Station on a bulk glass-forming Zr57Cu15.4Ni12.6Al10Nb5 (Vit106), as well as Cu50Zr50 and the quasicrystal-forming Ti39.5Zr39.5Ni21 liquids. The maximum supercooling temperatures for each alloy were measured as a function of controlled stirring by applying various combinations of radio frequency positioner and heater voltages to the water-cooled copper coils. The flow patterns were simulated from the known parameters for the coil and the levitated samples. The maximum nucleation temperatures increased systematically with increased fluid flow in the liquids for Vit106, but stayed nearly unchanged for the other two. These results are consistent with the predictions from the coupled-flux model for nucleation.Comment: 21 pages, 2 figure

Brain multiplexes reveal morphological connectional biomarkers fingerprinting late brain dementia states

Accurate diagnosis of mild cognitive impairment (MCI) before conversion to Alzheimer\u27s disease (AD) is invaluable for patient treatment. Many works showed that MCI and AD affect functional and structural connections between brain regions as well as the shape of cortical regions. However, \u27shape connections\u27 between brain regions are rarely investigated -e.g., how morphological attributes such as cortical thickness and sulcal depth of a specific brain region change in relation to morphological attributes in other regions. To fill this gap, we unprecedentedly design morphological brain multiplexes for late MCI/AD classification. Specifically, we use structural T1-w MRI to define morphological brain networks, each quantifying similarity in morphology between different cortical regions for a specific cortical attribute. Then, we define a brain multiplex where each intra-layer represents the morphological connectivity network of a specific cortical attribute, and each inter-layer encodes the similarity between two consecutive intra-layers. A significant performance gain is achieved when using the multiplex architecture in comparison to other conventional network analysis architectures. We also leverage this architecture to discover morphological connectional biomarkers fingerprinting the difference between late MCI and AD stages, which included the right entorhinal cortex and right caudal middle frontal gyrus

Tracing of temporo-entorhinal connections in the human brain: cognitively impaired argyrophilic grain disease cases show dendritic alterations but no axonal disconnection of temporo-entorhinal association neurons

Argyrophilic grain disease (AGD), a neurodegenerative disorder, is often associated with mild to moderate Alzheimer’s disease (AD)-related pathology. The development of dementia in AGD is associated with the extent of coexisting AD-related pathology. Therefore, the question arises whether the degenerative changes in the neuronal network of demented AGD-patients represent a distinct pattern or show similar changes of disconnection as considered for AD. We were able to apply DiI-tracing in two human autopsy cases with mild AD-related pathology (controls), in one AD-patient, in one non-demented patient with advanced AD-related pathology, and in three cognitively impaired AGD-patients. DiI-crystals were injected into the entorhinal cortex. Pyramidal neurons of layers III and V of the adjacent temporal neocortex (area 35) were retrogradely marked with the tracer and analyzed. The AD case did not exhibit any retrogradely labeled neurons in the temporal neocortex. In the non-demented case with advanced AD-related pathology, the number of traced neurons was reduced as compared to that in the two controls and in the three AGD cases. In contrast, all three cognitively impaired AGD cases exhibited labeled pyramidal neurons in area 35 in an almost similar number as in the controls. However, alterations in the dendritic tree were observed in the AGD cases. These results show the existence of temporo-entorhinal connections in the adult human brain similar to those reported in animal models. Furthermore, the present study based on seven cases is the first attempt to study changes in the neuronal network in a human tauopathy with targeted axonal tracing techniques. Our findings in three cognitively impaired AGD cases suggest that AGD-related dementia constitutes a distinct disorder with a characteristic pattern of degeneration in the neuronal network

Differential Encoding of Factors Influencing Predicted Reward Value in Monkey Rostral Anterior Cingulate Cortex

Background: The value of a predicted reward can be estimated based on the conjunction of both the intrinsic reward value and the length of time to obtain it. The question we addressed is how the two aspects, reward size and proximity to reward, influence the responses of neurons in rostral anterior cingulate cortex (rACC), a brain region thought to play an important role in reward processing. Methods and Findings: We recorded from single neurons while two monkeys performed a multi-trial reward schedule task. The monkeys performed 1–4 sequential color discrimination trials to obtain a reward of 1–3 liquid drops. There were two task conditions, a valid cue condition, where the number of trials and reward amount were associated with visual cues, and a random cue condition, where the cue was picked from the cue set at random. In the valid cue condition, the neuronal firing is strongly modulated by the predicted reward proximity during the trials. Information about the predicted reward amount is almost absent at those times. In substantial subpopulations, the neuronal responses decreased or increased gradually through schedule progress to the predicted outcome. These two gradually modulating signals could be used to calculate the effect of time on the perception of reward value. In the random cue condition, little information about the reward proximity or reward amount is encoded during the course of the trial before reward delivery, but when the reward is actually delivered the responses reflect both the reward proximity and reward amount

The Emergence of Emotions

Emotion is conscious experience. It is the affective aspect of consciousness. Emotion arises from sensory stimulation and is typically accompanied by physiological and behavioral changes in the body. Hence an emotion is a complex reaction pattern consisting of three components: a physiological component, a behavioral component, and an experiential (conscious) component. The reactions making up an emotion determine what the emotion will be recognized as. Three processes are involved in generating an emotion: (1) identification of the emotional significance of a sensory stimulus, (2) production of an affective state (emotion), and (3) regulation of the affective state. Two opposing systems in the brain (the reward and punishment systems) establish an affective value or valence (stimulus-reinforcement association) for sensory stimulation. This is process (1), the first step in the generation of an emotion. Development of stimulus-reinforcement associations (affective valence) serves as the basis for emotion expression (process 2), conditioned emotion learning acquisition and expression, memory consolidation, reinforcement-expectations, decision-making, coping responses, and social behavior. The amygdala is critical for the representation of stimulus-reinforcement associations (both reward and punishment-based) for these functions. Three distinct and separate architectural and functional areas of the prefrontal cortex (dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex) are involved in the regulation of emotion (process 3). The regulation of emotion by the prefrontal cortex consists of a positive feedback interaction between the prefrontal cortex and the inferior parietal cortex resulting in the nonlinear emergence of emotion. This positive feedback and nonlinear emergence represents a type of working memory (focal attention) by which perception is reorganized and rerepresented, becoming explicit, functional, and conscious. The explicit emotion states arising may be involved in the production of voluntary new or novel intentional (adaptive) behavior, especially social behavior

South Tank Farm underground storage tank inspection using the topographical mapping system for radiological and hazardous environments

During the winter of 1997 the Topographical Mapping System (TMS) for hazardous and radiological environments and the Interactive Computer-Enhanced Remote-Viewing System (ICERVS) were used to perform wall inspections on underground storage tanks (USTs) W5 and W6 of the South Tank Farm (STF) at Oak Ridge National Laboratory (ORNL). The TMS was designed for deployment in the USTs at the Hanford Site. Because of its modular design, the TMS was also deployable in the USTs at ORNL. The USTs at ORNL were built in the 1940s and have been used to store radioactive waste during the past 50 years. The tanks are constructed with an inner layer of Gunite{trademark} that has been spalling, leaving sections of the inner wall exposed. Attempts to quantify the depths of the spalling with video inspection have proven unsuccessful. The TMS surface-mapping campaign in the STF was initiated to determine the depths of cracks, crevices, and/or holes in the tank walls and to identify possible structural instabilities in the tanks. The development of the TMS and the ICERVS was initiated by DOE for the purpose of characterization and remediation of USTs at DOE sites across the country. DOE required a three-dimensional, topographical mapping system suitable for use in hazardous and radiological environments. The intended application is mapping the interiors of USTs as part of DOE`s waste characterization and remediation efforts, to obtain both baseline data on the content of the storage tank interiors and changes in the tank contents and levels brought about by waste remediation steps. Initially targeted for deployment at the Hanford Site, the TMS has been designed to be a self-contained, compact, and reconfigurable system that is capable of providing rapid variable-resolution mapping information in poorly characterized workspaces with a minimum of operator intervention