The Role of Hedgehog Signaling During Hemipene Development in Anolis sagrei

This project\u27s goal was to identify the role of Hedgehog signaling during hemipene development in the lizards Anolis sagrei. Hemepenes are the paired genitalia of squamates, lizards and snakes. When compared to mammals, there little known about the details of lizard genital development. Based on prior observations in mammals, we hypothesized that Sonic hedgehog (Shh) contributes to the development of hemipenes. We knocked down Hedgehog signaling during hemipene patterning to assess the function of Shh during hemipene development. Preliminary data demonstrate that Shh is critical for hemipene patterning in lizards

Infrared Emission by Dust Around lambda Bootis Stars: Debris Disks or Thermally Emitting Nebulae?

We present a model that describes stellar infrared excesses due to heating of the interstellar (IS) dust by a hot star passing through a diffuse IS cloud. This model is applied to six lambda Bootis stars with infrared excesses. Plausible values for the IS medium (ISM) density and relative velocity between the cloud and the star yield fits to the excess emission. This result is consistent with the diffusion/accretion hypothesis that lambda Bootis stars (A- to F-type stars with large underabundances of Fe-peak elements) owe their characteristics to interactions with the ISM. This proposal invokes radiation pressure from the star to repel the IS dust and excavate a paraboloidal dust cavity in the IS cloud, while the metal-poor gas is accreted onto the stellar photosphere. However, the measurements of the infrared excesses can also be fit by planetary debris disk models. A more detailed consideration of the conditions to produce lambda Bootis characteristics indicates that the majority of infrared-excess stars within the Local Bubble probably have debris disks. Nevertheless, more distant stars may often have excesses due to heating of interstellar material such as in our model.Comment: 10 pages, 5 figures, 4 tables, accepted by ApJ, emulateap

A Review of Training Methods and Instructional Techniques: Implications for Behavioral Skills Training in U.S. Astronauts (DRAFT)

Long-duration space missions (LDM) place unique physical, environmental and psychological demands on crewmembers that directly affect their ability to live and work in space. A growing body of research on crews working for extended periods in isolated, confined environments reveals the existence of psychological and performance problems in varying degrees of magnitude. The research has also demonstrated that although the environment plays a cathartic role, many of these problems are due to interpersonal frictions (Wood, Lugg, Hysong, & Harm, 1999), and affect each individual differently. Consequently, crewmembers often turn to maladaptive behaviors as coping mechanisms, resulting in decreased productivity and psychological discomfort. From this body of research, critical skills have been identified that can help a crewmember better navigate the psychological challenges of long duration space flight. Although most people lack several of these skills, most of them can be learned; thus, a training program can be designed to teach crewmembers effective leadership, teamwork, and self-care strategies that will help minimize the emergence of maladaptive behaviors. Thus, it is the purpose of this report is twofold: 1) To review the training literature to help determine the optimal instructional methods to use in delivering psychological skill training to the U.S. Astronaut Expedition Corps, and 2) To detail the structure and content of the proposed Astronaut Expedition Corps Psychological Training Program

Exotic tree plantations and avian conservation in northern Iberia: a view from a nest–box monitoring study

Plantaciones de árboles exóticos y conservación de la avifauna en el norte de la península ibérica: perspectiva de un estudio de seguimiento de cajas nido La expansión de plantaciones de árboles exóticos en la costa cantábrica de la península ibérica suscita preocupación por la conservación de la biodiversidad de aves, puesto que las tendencias actuales sugieren que esta región podría convertirse en un monocultivo de especies de eucalipto australiano. Para arrojar más luz sobre los factores que promueven las diferencias en las comunidades de aves entre y dentro de las plantaciones de árboles exóticos (pino de Monterrey Pinus radiata y Eucalyptus spp.) y los bosques nativos de la zona de Urdaibai (norte de España), el objetivo del presente estudio consistió en analizar (1) la forma en que el tipo de hábitat y las características de la vegetación afectan a la riqueza de especies de aves y el asentamiento de determinadas especies durante el período de cría; (2) si algunos parámetros reproductivos (p.ej. la fecha o el tamaño de puesta) varían entre los hábitats en una especie de ave generalista (el carbonero común, Parus major); y (3) la existencia de diferencias entre hábitats por lo que hace a la abundancia de una fuente clave de alimento de la que se prevé que las aves insectívoras dependan para la cría (las orugas). Nuestros resultados confirmaron que las poblaciones de eucalipto albergan las comunidades más pobres de aves y establecieron el desarrollo del sotobosque como un factor importante para el establecimiento de las especies de páridos. Asimismo, hallamos que los árboles exóticos presentaban una abundancia de orugas menor que la de los robles nativos (Quercus robur), lo que podría contribuir a explicar las diferencias observadas entre los hábitats en cuanto a la abundancia y la riqueza de aves de esta región. No obstante, no se hallaron diferencias entre los hábitats por lo que concierne a la fecha y el tamaño de puesta para el carbonero común, lo que sugiere que los posibles costes de criar en plantaciones de árboles exóticos se producirían en etapas posteriores del periodo reproductivo (p.ej. el número de pollos emplumados), una circunstancia que habrá que seguir investigando.Plantaciones de árboles exóticos y conservación de la avifauna en el norte de la península ibérica: perspectiva de un estudio de seguimiento de cajas nido La expansión de plantaciones de árboles exóticos en la costa cantábrica de la península ibérica suscita preocupación por la conservación de la biodiversidad de aves, puesto que las tendencias actuales sugieren que esta región podría convertirse en un monocultivo de especies de eucalipto australiano. Para arrojar más luz sobre los factores que promueven las diferencias en las comunidades de aves entre y dentro de las plantaciones de árboles exóticos (pino de Monterrey Pinus radiata y Eucalyptus spp.) y los bosques nativos de la zona de Urdaibai (norte de España), el objetivo del presente estudio consistió en analizar (1) la forma en que el tipo de hábitat y las características de la vegetación afectan a la riqueza de especies de aves y el asentamiento de determinadas especies durante el período de cría; (2) si algunos parámetros reproductivos (p.ej. la fecha o el tamaño de puesta) varían entre los hábitats en una especie de ave generalista (el carbonero común, Parus major); y (3) la existencia de diferencias entre hábitats por lo que hace a la abundancia de una fuente clave de alimento de la que se prevé que las aves insectívoras dependan para la cría (las orugas). Nuestros resultados confirmaron que las poblaciones de eucalipto albergan las comunidades más pobres de aves y establecieron el desarrollo del sotobosque como un factor importante para el establecimiento de las especies de páridos. Asimismo, hallamos que los árboles exóticos presentaban una abundancia de orugas menor que la de los robles nativos (Quercus robur), lo que podría contribuir a explicar las diferencias observadas entre los hábitats en cuanto a la abundancia y la riqueza de aves de esta región. No obstante, no se hallaron diferencias entre los hábitats por lo que concierne a la fecha y el tamaño de puesta para el carbonero común, lo que sugiere que los posibles costes de criar en plantaciones de árboles exóticos se producirían en etapas posteriores del periodo reproductivo (p.ej. el número de pollos emplumados), una circunstancia que habrá que seguir investigando.The spread of exotic tree plantations on the North Atlantic coast of the Iberian peninsula raises concern regarding the conservation of avian biodiversity as current trends suggest this region might become a monoculture of Australian Eucalyptus species. To shed more light on the factors promoting differences in avian communities between and within exotic tree (Monterey Pine Pinus radiata and Eucalyptus spp.) plantations and native forests in the Urdaibai area (northern Spain), this study aimed to explore (1) how the type of habitat and vegetation characteristics affect bird species richness and the settlement of some particular species during the breeding period, (2) if some reproductive parameters (i.e. egg–laying date and clutch size) vary among habitats in a generalist bird species (the Great Tit Parus major), and (3) the existence of differences among habitats in the abundance of a key food resource on which some insectivorous birds are expected to rely upon for breeding (i.e. caterpillars). Our results confirmed that Eucalyptus stands house the poorest bird communities, and identified understory development as an important determinant for the establishment of titmice species. Furthermore, we found that exotic trees showed lower caterpillar abundance than native Oak trees (Quercus robur), which might contribute to explain observed differences among habitats in bird abundance and richness in this region. However, we did not find differences among habitats in egg–laying date and clutch size for the Great Tit, suggesting that the potential costs of breeding in exotic tree plantations would occur in later stages of the reproductive period (e.g. number of nestlings fledged), a circumstance that will require further research

Wavelength calibration of the JWST-MIRI medium resolution spectrometer

We present the wavelength and spectral resolution characterisation of the Integral Field Unit (IFU) Medium Resolution Spectrometer for the Mid-InfraRed Instrument (MIRI), to fly onboard the James Webb Space Telescope in 2014. We use data collected using the Verification Model of the instrument and develop an empirical method to calibrate properties such as wavelength range and resolving power in a portion of the spectrometer's full spectral range (5-28 microns). We test our results against optical models to verify the system requirements and combine them with a study of the fringing pattern in the instrument's detector to provide a more accurate calibration. We show that MIRI's IFU spectrometer will be able to produce spectra with a resolving power above R=2800 in the wavelength range 6.46-7.70 microns, and that the unresolved spectral lines are well fitted by a Gaussian profile.Comment: 12 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wav

Cracking Control in Mezzanine Floor Slabs using Rice Husk Ash and Polypropylene Fibers

The continuous population increase in recent years requires a greater number of households to be built quickly, with good materials and produced under quality standards that guarantee their manufacturing process. The prefabricated concrete, produced and supplied by concrete plants, is poured into the different structural elements, the mezzanine slabs being the most careful surfaces in the appearance of fissures; because being horizontal and having larger dimensions, the dimensional changes in the concrete appear more frequently due to the rapid loss of water from the surface of the concrete before setting; which generates superior stresses to the resistant capacity of the concrete at early ages, which affect the durability and reduce the resistance of the structures, causing greater economic expenses in maintenance and repairs. In the present investigation, 5%, 10% and 15% of rice husk ash was used as a replacement for cement and 900g/m3 of polypropylene fiber; The results indicate that as the percentage of rice husk ash increases, there is a reduction in the slump and the crack fissures, and that the resistance to compression and flexion decreases, with respect to the concrete pattern

Control of Astrocyte Quiescence and Activation in a Synthetic Brain Hydrogel

Bioengineers have designed numerous instructive brain extracellular matrix (ECM) environments with tailored and tunable protein composition and biomechanical properties in vitro to study astrocyte reactivity during trauma and inflammation. However, a major limitation of both protein-based and model microenvironments is that astrocytes within fail to retain their characteristic stellate morphology and quiescent state without becoming activated under “normal” culture conditions. Here we introduce a synthetic hydrogel, that for the first time demonstrates maintenance of astrocyte quiescence and activation on demand. With this synthetic brain hydrogel, we show the brain-specific integrin-binding and matrix metalloprotease (MMP)-degradable domains of proteins control astrocyte star-shaped morphologies, and we can achieve an ECM condition that maintains astrocyte quiescence with minimal activation. In addition, we can induce activation in a dose-dependent manner via both defined cytokine cocktails and low molecular weight hyaluronic acid. We envision this synthetic brain hydrogel as a new tool to study the physiological role of astrocytes in health and disease

Control of thiol-maleimide reaction kinetics in PEG hydrogel networks

Michael-type addition reactions are widely used to polymerize biocompatible hydrogels. The thiol-maleimide modality achieves the highest macromer coupling efficiency of the reported Michael-type pairs, but the resulting hydrogel networks are heterogeneous, because polymerization is faster than the individual components can be manually mixed. The reactivity of the thiol dictates the overall reaction speed, which can be slowed in organic solvents and acidic buffers. Since these modifications also reduce the biocompatibility of resulting hydrogels, we investigated a series of biocompatible buff­ers and crosslinkers to decelerate gelation while maintaining high cell viability. We found that lowering the polymer weight percentage (wt%), buffer concentration, and pH slowed gelation kinetics, but crosslinking with an electronegative peptide was optimal for both kinetics and cell viability. Including a high glucose medium supplement in the polymer solvent buffer improved the viability of the cells being encapsulated without impacting gelation time. Slowing the speed of polymerization resulted in more uniform hydrogels, both in terms of visual inspection and the diffusion of small molecules through the network. However, reactions that were too slow resulted in non-uniform particle dispersion due to settling, thus there is a trade-off in hydrogel network uniformity versus cell distribution in the hydrogels when using these networks in cell applications

Preliminary Results from the Experimental Study of CO2-Brine-Rock Interactions at Elevated T & P: Implications for the Pilot Plant for CO2 Storage in Spain

AbstractA new experimental program has been carried out in order to study CO2-brine-rock interactions susceptible to take place in conditions close to those expected in the pilot plant that is being developed in Spain (a carbonate reservoir located at more than 800 m depth, with 15% porosity, and a salinity of the native brine between 20 – 90g/L). The combination of preliminary experimental and numerical modeling (PHREEQC) results suggests that the main geochemical processes are calcite dissolution and anhydrite precipitation