An evaluation of the learning ability during the various periods of the school day.

Thesis (M.S.

The design and construction of a pneumatic harvester for crimson clover seed

The current problem in harvesting crimson clover seed is not new. As early as 1915, Mr. J. M. Westgate recognized the shattering tendency of the plant as the principal drawback in harvesting the seed crop. The problem is to reduce or to eliminate the possibility of an appreciable loss of seed caused by shattering both before and during the harvesting process. The problem can be approached in two ways. First, a shatter-resistant strain of crimson clover, which would be well adapted to direct combine harvesting, might be developed through plant breeding; this method of approach, however, would probably require several years of breeding and might even then not be successful. Secondly, as this study proposes to show, a satisfactory solution to the problem can be reached by making a change in the harvesting machinery. The purpose of this study is to arrive at a design for an attachment to be used on a combine. The function of this attachment will be to recover shattered crimson clover seed during the direct combining process and to deliver the recovered seed to the threshing cylinder of the combine. In an effort to evaluate the design, an experimental attachment has been constructed and tested both in the laboratory and in the field

The concept of man in the philosophy of Sri Aurobindo

Not availabl

The Multi-Epoch Nearby Cluster Survey: type Ia supernova rate measurement in z~0.1 clusters and the late-time delay time distribution

We describe the Multi-Epoch Nearby Cluster Survey (MENeaCS), designed to measure the cluster Type Ia supernova (SN Ia) rate in a sample of 57 X-ray selected galaxy clusters, with redshifts of 0.05 < z < 0.15. Utilizing our real time analysis pipeline, we spectroscopically confirmed twenty-three cluster SN Ia, four of which were intracluster events. Using our deep CFHT/Megacam imaging, we measured total stellar luminosities in each of our galaxy clusters, and we performed detailed supernova detection efficiency simulations. Bringing these ingredients together, we measure an overall cluster SN Ia rate within R_{200} (1 Mpc) of 0.042^{+0.012}_{-0.010}^{+0.010}_{-0.008} SNuM (0.049^{+0.016}_{-0.014}^{+0.005}_{-0.004} SNuM) and a SN Ia rate within red sequence galaxies of 0.041^{+0.015}_{-0.015}^{+0.005}_{-0.010} SNuM (0.041^{+0.019}_{-0.015}^{+0.005}_{-0.004} SNuM). The red sequence SN Ia rate is consistent with published rates in early type/elliptical galaxies in the `field'. Using our red sequence SN Ia rate, and other cluster SNe measurements in early type galaxies up to $z\sim1$, we derive the late time (>2 Gyr) delay time distribution (DTD) of SN Ia assuming a cluster early type galaxy star formation epoch of z_f=3. Assuming a power law form for the DTD, \Psi(t)\propto t^s, we find s=-1.62\pm0.54. This result is consistent with predictions for the double degenerate SN Ia progenitor scenario (s\sim-1), and is also in line with recent calculations for the double detonation explosion mechanism (s\sim-2). The most recent calculations of the single degenerate scenario delay time distribution predicts an order of magnitude drop off in SN Ia rate \sim 6-7 Gyr after stellar formation, and the observed cluster rates cannot rule this out.Comment: 35 pages, 14 figures, ApJ accepte

Intracluster supernovae in the Multi-epoch Nearby Cluster Survey

The Multi-Epoch Nearby Cluster Survey (MENeaCS) has discovered twenty-three cluster Type Ia supernovae (SNe) in the 58 X-ray selected galaxy clusters (0.05 < z < 0.15) surveyed. Four of our SN Ia events have no host galaxy on close inspection, and are likely intracluster SNe. Deep image stacks at the location of the candidate intracluster SNe put upper limits on the luminosities of faint hosts, with M_{r} > -13.0 mag and M_{g} > -12.5 mag in all cases. For such limits, the fraction of the cluster luminosity in faint dwarfs below our detection limit is <0.1%, assuming a standard cluster luminosity function. All four events occurred within ~600 kpc of the cluster center (projected), as defined by the position of the brightest cluster galaxy, and are more centrally concentrated than the cluster SN Ia population as a whole. After accounting for several observational biases that make intracluster SNe easier to discover and spectroscopically confirm, we calculate an intracluster stellar mass fraction of 0.16^{+0.13}_{-0.09} (68% CL) for all objects within R_{200}. If we assume that the intracluster stellar population is exclusively old, and the cluster galaxies themselves have a mix of stellar ages, we derive an upper limit on the intracluster stellar mass fraction of <0.47 (84% one-sided CL). When combined with the intragroup SNe results of McGee & Balogh, we confirm the declining intracluster stellar mass fraction as a function of halo mass reported by Gonzalez and collaborators. (Abridged)Comment: 24 pages, 8 figures, ApJ publishe

Do imitation problems reflect a core characteristic in autism? Evidence from a literature review

A

Calibration and performance of the Galileo solid-state imaging system in Jupiter orbit

The solid-state imaging subsystem (SSI) on the National Aeronautics and Space Administration’s (NASA’s) Galileo Jupiter orbiter spacecraft has successfully completed its 2-yr primary mission exploring the Jovian system. The SSI has remained in remarkably stable calibration during the 8-yr flight, and the quality of the returned images is exceptional. Absolute spectral radiometric calibration has been determined to 4 to 6% across its eight spectral filters. Software and calibration files are available to enable radiometric, geometric, modulation transfer function (MTF), and scattered light image calibration. The charge-coupled device (CCD) detector endured the harsh radiation environment at Jupiter without significant damage and exhibited transient image noise effects at about the expected levels. A lossy integer cosine transform (ICT) data compressor proved essential to achieving the SSI science objectives given the low data transmission rate available from Jupiter due to a communication antenna failure. The ICT compressor does introduce certain artifacts in the images that must be controlled to acceptable levels by judicious choice of compression control parameter settings. The SSI team’s expertise in using the compressor improved throughout the orbital operations phase and, coupled with a strategy using multiple playback passes of the spacecraft tape recorder, resulted in the successful return of 1645 unique images of Jupiter and its satellites

Human genomic Z-DNA segments probed by the Zα domain of ADAR1

Double-stranded DNA is a dynamic molecule that adopts different secondary structures. Experimental evidence indicates Z-DNA plays roles in DNA transactions such as transcription, chromatin remodeling and recombination. Furthermore, our computational analysis revealed that sequences with high Z-DNA forming potential at moderate levels of DNA supercoiling are enriched in human promoter regions. However, the actual distribution of Z-DNA segments in genomes of mammalian cells has been elusive due to the unstable nature of Z-DNA and lack of specific probes. Here we present a first human genome map of most stable Z-DNA segments obtained with A549 tumor cells. We used the Z-DNA binding domain, Zα, of the RNA editing enzyme ADAR1 as probe in conjunction with a novel chromatin affinity precipitation strategy. By applying stringent selection criteria, we identified 186 genomic Z-DNA hotspots. Interestingly, 46 hotspots were located in centromeres of 13 human chromosomes. There was a very strong correlation between these hotspots and high densities of single nucleotide polymorphism. Our study indicates that genetic instability and rapid evolution of human centromeres might, at least in part, be driven by Z-DNA segments. Contrary to in silico predictions, however, we found that only two of the 186 hotspots were located in promoter regions

Developmental pathways to autism: a review of prospective studies of infants at risk

Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders characterized by impairments in social interaction and communication, and the presence of restrictive and repetitive behaviors. Symptoms of ASD likely emerge from a complex interaction between pre-existing neurodevelopmental vulnerabilities and the child's environment, modified by compensatory skills and protective factors. Prospective studies of infants at high familial risk for ASD (who have an older sibling with a diagnosis) are beginning to characterize these developmental pathways to the emergence of clinical symptoms. Here, we review the range of behavioral and neurocognitive markers for later ASD that have been identified in high-risk infants in the first years of life. We discuss theoretical implications of emerging patterns, and identify key directions for future work, including potential resolutions to several methodological challenges for the field. Mapping how ASD unfolds from birth is critical to our understanding of the developmental mechanisms underlying this disorder. A more nuanced understanding of developmental pathways to ASD will help us not only to identify children who need early intervention, but also to improve the range of interventions available to them