SURFSAT: Supporting Deep-Space-Network Research and Development with a Student-Designed Small Satellite

SURFSAT is a small satellite designed primarily by students at the California Institute of Technology under Caltech\u27s Summer Undergraduate Research Fellowship (SURF) program and is sponsored by the Telecommunications and Data Acquisition Office at JPL, the research and development arm for the Deep Space Network (DSN). The project was initiated in the summer of 1987 and has involved several dozen undergraduate students. SURFSAT is designed to radiate at either the milliwatt or microwatt level in four bands: Sband (2.29 GHz), X-band (8.45 GHz), Ku-band (15.33 GHz) and Ka-band (32 GHz). The signals will be received by a new 34-meter DSN research antenna at Goldstone, California. Performance of the new Ku-band link will be analyzed and compared to the performance of the more standard X-band link. The S-band and Ku-band signals will be used to support DSN spacecraft acquisition tests and training. Other experiment objectives have also been identified, including spacecraft position and orbit determination demonstrations utilizing ground-based connected-element interferometers. It will also carry an optical beacon to demonstrate the possibility of communicating at infra-red wavelengths. The basic SURFSAT satellite is a solar powered cube, 12 inches on each side, that will tumble through space. Attitude stabilization is not required, and the satellites will not have a propulsion subsystem or batteries. Signals are to be radiated in all directions. Redundant command receivers will enable transmit modes of one milliwatt, one microwatt, and OFF. At least two SURFSATs are scheduled for launch as secondary payloads on a Delta rocket in May 1994; the primary payload for this mission is LAGEOS III

EXAMINING MEMORY CONSOLIDATION AND RECONSOLIDATION IN AN APPETITIVE PAVLOVIAN TASK

Memory plays an important role in defining how one behaves. The neurobiological mechanisms of memory have been studied extensively in animal models and the NMDA glutamate receptor has been identified to play an important role in the consolidation and reconsolidation of appetitive memories. Certain memories, depending on what was learned, can function differently and can be more difficult to disrupt based on a number of factors. Currently, no study has examined whether or not a reward-predictive stimulus attributed with incentive value is more difficult to disrupt than a stimulus that functions as a general reward-predictor. To determine the role of the NMDA receptor on memory consolidation with different functioning reward-predictive stimuli rats underwent a Pavlovian conditioned approach, where a post-session NMDA receptor antagonist was administered daily. Furthermore, to determine the role of the NMDA receptor on memory reconsolidation, another set of rats were trained on a Pavlovian conditioned approach task, after training was complete rats were presented with a reward-predictive stimuli followed by an administration of a NMDA receptor antagonist and then re-tested

The Effects of Choice and Ego-Involvement on Confidence Judgments

Studies on confidence judgments have generally shown that people are overconfident about their abilities or knowledge, and their confidence judgments are not well calibrated. The purpose of this study was to contribute toward a more precise and defensible version of how motivational factors interact with cognitive biases to influence confidence judgments. Review of the effect of choice on confidence judgments suggests an avenue to study the joint effect of motivational factors and cognitive biases on confidence judgments. In particular, the study investigated how motivational factors such as ego-involvement interact with cognitive biases involved in making choices to increase overconfidence in general knowledge questions. In the present study, the degree of egoinvolvement was manipulated through information provided about the nature of the task. Participants either assessed confidence judgments on their chosen alternatives (choice condition) or assessed confidence judgments on the precircled alternatives (arbitrary cue condition). Results indicated that arbitrary cue participants were more overconfident than choice participants. The influence of ego-involvement, however, was undetectable. Egoinvolvement was found to moderate the effect of choice on confidence judgments, however, in the opposite direction of the prediction. In the high ego-involvement condition, arbitrary cue participants exhibited higher overconfidence than choice participants. There was no significant difference between arbitrary cue participants and choice participants in the low ego-involvement condition. Implications of the findings and suggestions for future research are discussed

Generalised Rado and Roth criteria

We study the Ramsey properties of equations $a_1P(x_1) + \cdots + a_sP(x_s) = b$, where $a_1,\ldots,a_s,b$ are integers, and $P$ is an integer polynomial of degree $d$. Provided there are at least $(1+o(1))d^2$ variables, we show that Rado's criterion and an intersectivity condition completely characterise which equations of this form admit monochromatic solutions with respect to an arbitrary finite colouring of the positive integers. Furthermore, we obtain a Roth-type theorem for these equations, showing that they admit non-constant solutions over any set of integers with positive upper density if and only if $b= a_1 + \cdots + a_s = 0$. In addition, we establish sharp asymptotic lower bounds for the number of monochromatic/dense solutions (supersaturation).Comment: 36 page

COCAINE CHOICE: A NOVEL PROCEDURE FOR INVESTIGATING NEURONAL ACTIVATION MEDIATING COCAINE PREFERENCE

Cocaine use disorder is a significant health problem, negatively impacting individuals afflicted. While preclinical self-administration research has provided invaluable insight into the neurobehavioral mechanisms that underlie cocaine abuse, cocaine use outside of the laboratory occurs within an environment where other goods are also available ubiquitously. Although there is an ever-increasing literature investigating drug vs. non-drug choice in rodent models and how alternative goods can compete with the subjective value of cocaine, the neurobiological mechanisms that are associated with cocaine preference remains largely unknown. Additionally, current drug vs. non-drug choice studies use procedures that confound preference with intake, such that preference measures are directly reflective of individual experience with drug and non-drug reinforcers earned through the choices that are made; simply, preference and intake are the same. Moreover, differences in cocaine experience can result in differential neural adaptations, thus making it difficult to determine if the neurobiological mechanisms underlying choice are related to preference or drug intake. Herein a novel choice procedure, which controls for reinforcer intake (controlled reinforcer ratio; CRR), was used to explore how certain reinforcer dimensions (i.e., magnitude and frequency) influence cocaine preference. In addition, neuronal activity, measured via c-fos expression, in the orbitofrontal cortex and nucleus accumbens, areas associated with decision-making and valuation, for cocaine and food were independently targeted and labeled using fluorescent in situ hybridization and fluorescent immunohistochemistry. First, unlike prototypical choice procedures where preference and intake are confounded, the CRR choice procedure was able to dissociate the two. Under the CRR choice procedure, it was revealed that both magnitude and frequency, independent dimensions of reinforcement, greatly influence preference for cocaine. Furthermore, the CRR choice procedure was sensitive to manipulations known to influence cocaine preference while keeping reinforcer intake constant. When neuronal activity was examined after CRR training, the number of cocaine activated cells, relative to food activated cells, did not correlate with individual preferences for cocaine despite overall reinforcer intake being held constant. Instead, results suggest neuronal activity for cocaine was related to overall cocaine intake. Overall, these results give impetus for utilizing the CRR choice procedure to better investigate how drug and non-drug reinforcers are afforded differential subjective value and compete for preference. Moreover, use of a CRR choice procedure may lead to identification of specific neurobehavioral mechanisms and lead toward future development of more effective pharmacological and behavioral treatments to ameliorate substance use disorders

PRRs are watching you: Localization of innate sensing and signaling regulators

AbstractTo prevent the spread of infection, an invading pathogen must first be recognized by the innate immune system. Host pattern recognition receptors detect distinct pathogen-associated molecules and induce the transcription and release of interferon and inflammatory molecules to resolve infection. Unlike infections with pathogens that replicate autonomously from the host, viral infections blur the boundaries of self and non-self. Differentiation of host from virus is achieved by restricting localization of host nucleic acids and by placing pattern recognition receptors in specific subcellular compartments. Within this review, we discuss how several families of pattern recognition receptors act to provide a comprehensive surveillance network that has the potential to induce interferon expression in response to any viral infection

NMDA Receptor Blockade Specifically Impedes the Acquisition of Incentive Salience Attribution

Glutamatergic signaling plays an important role in learning and memory. Using Pavlovian conditioned approach procedures, the mechanisms that drive stimulus-reward learning and memory have been investigated. However, there are instances where reward-predictive stimuli can function beyond being solely predictive and can be attributed with “motivational value” or incentive salience. Using a Pavlovian conditioned approach procedure consisting of two different but equally predictive stimuli (lever vs. tone) we investigated the role NMDA receptor function has in the attribution of incentive salience. The results revealed that the administration of MK-801, an NMDA receptor antagonist, during acquisition of Pavlovian conditioned approach promoted goal-tracking to a lever stimulus, while control animals learned to sign-track. Moreover, within the same animals, the use of a tone stimulus elicited goal-tracking responses that were unaffected by MK-801 pretreatments. Furthermore, a lever CS that elicited sign-tracking served as a more robust conditioned reinforcer than a tone CS that elicited goal-tracking or a lever CS that elicited goal-tracking via MK-801 pretreatments. Collectively, these results demonstrate that NMDA receptor antagonism can alter the stimulus-reward relationship learned and prevent the attribution of incentive salience, rather than impede general learning

Dear Incoming Graduate Student Colleague

2020. “Dear Incoming Graduate Student Colleague.” In Diversity, Decolonialization, and the German Curriculum, edited by Regine Criser and Ervin Malakaj. Palgrave, 309–326

Comportamiento agronomico y productivo de nueve leguminosas herbaceas forrajeras, en el municipio de Muy Muy, Matagalpa

Las dos grandes fuentes de alimentación animal son: energética que comúnmente esta dada por las gramíneas y proteica, la cual puede ser suplementada por diferentes vías, pero las mas simple y que la naturaleza la provee es a través de las leguminosas, producto de la asociación con bacterias del género Rhizobium, que les permite fijar nitrógeno atmosférico. Los estudio hechos de leguminosas al momento han sido muy pocos, y cuando se han hecho se ha centrado únicamente en zonas del caribe con alta precipitación y suelos ácidos. Por lo que con el objeto de conocer el comportamiento de adaptación agronómico y productivo de 9 especies de leguminosas consideradas como forrajeras en el municipio de Muy Muy, se realizó el presente estudio en la finca “La Cruz” propiedad del señor Santiago Espino, ubicada en el km 153 de la carretera Muy Muy-Matiguás, en la comunidad de “Aguas Calientes”, zona baja del municipio de Muy Muy, Matagalpa, localizado en las coordenadas geográficas 12º 45 ́48” latitud Norte y 85º 37 ́36”longitud Oeste, a una altitud de unos 286msnmy con una temperatura promedio anual de 25.0°C. se estableció el experimento de campo el 4 de Junio del 2007. Utilizándose un Diseño de Bloques Completos al Azar (BCA), con nueve tratamientos (especies evaluadas: Centrosema plumieri cv DICTA, Clitoria ternatea cv CEVAS, Canavalia brasiliensis CIAT 1700, Clitoria ternatea CV DICTA, Canavalia ensiformis, Lablab purpureus, Vigna unguiculata CIAT9611, Vigna unguiculata CIAT390-2 y Stylosanthes guianensis CIAT2243). Se midieron 9 variables: sobrevivencia, altura, vigor, cobertura, cobertura de maleza, suelo descubierto, incidencia de plagas, incidencia de enfermedades y producción de biomasa seca, además se realizó análisis de la composición química a ocho de las especies en estudio. S.guianensis 2243 presentó el mejor comportamiento agronómico, superando al resto de especies en casi todas las variables en estudio, salvo el caso de altura donde fue superada por C. brasiliensis 1700 con 95.5 cm y en suelo descubierto por C. plumieri DICTA con 4.38%. En sobrevivencia Stylo alcanzó un 100%, con cobertura de 76.25%, menor incidencia de plagas y enfermedades (0%) y ponderación en vigor de 4.9. Además S.guianensis 2243 presentó el mejor comportamiento en producción de biomasa seca con 3717.02 kg ha-1, seguida de C. plumieriDICTA con 1486.38 kg ha-1. La especie de menor comportamiento adaptativo fue V. unguiculata 9611, y en producción de biomasa L. purpureus con 206.82 kg ha-1. C. ensiformis presento mejor contenido proteico con 26.20% y C. ternateaCEVAS en la porción digerible con 85.71%, la de menor calidad fue S.guianensis 2243 con 13.26% de proteína y 54.59% de porción digerible. Aun con los resultados de calidad se considera que S. guianensis2243 es una especie promisoria para estas condiciones por su a daptabilidad y producción de biomasa, y calidad y a las especies C. plumieriDICTA y C. ternateaCEVAS por su calidad nutritiva, adaptación y producciónde biomasa