Angular Distribution of the Protons from the Deuteron - Deuteron Reaction

A collimated beam of deuterons, of accurately controlled energy, has been directed into a chamber filled with deuterium gas at a pressure of 0.5 mm. of Mercury. High Energy protons are produced in the well-known nuclear reaction: H2+H2→H1+H3. The number of such protons ejected per unit solid angle from disintegrations occurring in a selected volume has been measured as a function of angle with the incident beam. For a bombarding energy of 325 kilovolts we find the angular distribution to be represented by 1 + 1.35 cos2 ϑ, where ϑ is the angle with the beam as assigned by an observer at rest with respect to the center of mass of the colliding deuterons. The theoretical significance of the result will be discussed. Data for 250 and 400 kilovolts should also be available for presentation at the meeting

High Voltage Apparatus for Nuclear Physics

The design and performance of a transformer-rectifier voltage quadrupling installation for potentials up to 600 KV will be described

Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector

Wind-induced pointing errors are a serious concern for large-aperture high-frequency radio telescopes. In this paper, we describe the implementation of an optical quadrant detector instrument that can detect and provide a correction signal for wind-induced pointing errors on the 100m diameter Green Bank Telescope (GBT). The instrument was calibrated using a combination of astronomical measurements and metrology. We find that the main wind-induced pointing errors on time scales of minutes are caused by the feedarm being blown along the direction of the wind vector. We also find that wind-induced structural excitation is virtually non-existent. We have implemented offline software to apply pointing corrections to the data from imaging instruments such as the MUSTANG 3.3 mm bolometer array, which can recover ~70% of sensitivity lost due to wind-induced pointing errors. We have also performed preliminary tests that show great promise for correcting these pointing errors in real-time using the telescope's subreflector servo system in combination with the quadrant detector signal.Comment: 17 pages, 11 figures; accepted for publication in PAS

Morphogenesis underlying the development of the everted teleost telencephalon

Background: Although the mechanisms underlying brain patterning and regionalization are very much conserved, the morphology of different brain regions is extraordinarily variable across vertebrate phylogeny. This is especially manifest in the telencephalon, where the most dramatic variation is seen between ray-finned fish, which have an everted telencephalon, and all other vertebrates, which have an evaginated telencephalon. The mechanisms that generate these distinct morphologies are not well understood. Results: Here we study the morphogenesis of the zebrafish telencephalon from 12 hours post fertilization (hpf) to 5 days post fertilization (dpf) by analyzing forebrain ventricle formation, evolving patterns of gene and transgene expression, neuronal organization, and fate mapping. Our results highlight two key events in telencephalon morphogenesis. First, the formation of a deep ventricular recess between telencephalon and diencephalon, the anterior intraencephalic sulcus (AIS), effectively creates a posterior ventricular wall to the telencephalic lobes. This process displaces the most posterior neuroepithelial territory of the telencephalon laterally. Second, as telencephalic growth and neurogenesis proceed between days 2 and 5 of development, the pallial region of the posterior ventricular wall of the telencephalon bulges into the dorsal aspect of the AIS. This brings the ventricular zone (VZ) into close apposition with the roof of the AIS to generate a narrow ventricular space and the thin tela choroidea (tc). As the pallial VZ expands, the tc also expands over the upper surface of the telencephalon. During this period, the major axis of growth and extension of the pallial VZ is along the anteroposterior axis. This second step effectively generates an everted telencephalon by 5 dpf. Conclusion: Our description of telencephalic morphogenesis challenges the conventional model that eversion is simply due to a laterally directed outfolding of the telencephalic neuroepithelium. This may have significant bearing on understanding the eventual organization of the adult fish telencephalon

Educational outcomes in extremely preterm children : neuropsychological correlates and predictors of attainment

This study assessed the impact of extremely preterm birth on academic attainment at 11 years of age, investigated neuropsychological antecedents of attainment in reading and mathematics, and examined early predictors of educational outcomes. Children born extremely preterm had significantly poorer academic attainment and a higher prevalence of learning difficulties than their term peers. General cognitive ability and specific deficits in visuospatial skills or phoneme deletion at 6 years were predictive of mathematics and reading attainment at 11 years in both extremely preterm and term children. Phonological processing, attention, and executive functions at 6 years were also associated with academic attainment in children born extremely preterm. Furthermore, social factors, neonatal factors (necrotizing enterocolitis, breech delivery, abnormal cerebral ultrasound, early breast milk provision), and developmental factors at 30 months (head circumference, cognitive development), were independent predictors of educational outcomes at 11 years. Neonatal complications combined with assessments of early cognitive function provide moderate prediction for educational outcomes in children born extremely preterm

Emotional engagements predict and enhance social cognition in young chimpanzees

Social cognition in infancy is evident in coordinated triadic engagements, that is, infants attending jointly with social partners and objects. Current evolutionary theories of primate social cognition tend to highlight species differences in cognition based on human-unique cooperative motives. We consider a developmental model in which engagement experiences produce differential outcomes. We conducted a 10-year-long study in which two groups of laboratory-raised chimpanzee infants were given quantifiably different engagement experiences. Joint attention, cooperativeness, affect, and different levels of cognition were measured in 5- to 12-month-old chimpanzees, and compared to outcomes derived from a normative human database. We found that joint attention skills significantly improved across development for all infants, but by 12 months, the humans significantly surpassed the chimpanzees. We found that cooperativeness was stable in the humans, but by 12 months, the chimpanzee group given enriched engagement experiences significantly surpassed the humans. Past engagement experiences and concurrent affect were significant unique predictors of both joint attention and cooperativeness in 5- to 12-month-old chimpanzees. When engagement experiences and concurrent affect were statistically controlled, joint attention and cooperation were not associated. We explain differential social cognition outcomes in terms of the significant influences of previous engagement experiences and affect, in addition to cognition. Our study highlights developmental processes that underpin the emergence of social cognition in support of evolutionary continuity

Stability of the Autism Diagnostic Interview—Revised from Pre-School to Elementary School Age in Children with Autism Spectrum Disorders

This study examined the stability of scores on the ADI-R from pre-school to elementary school age in children with autism spectrum disorders (ASD). Participants were 35 children who, at T1, all had a clinical diagnosis of ASD. On initial assessment (mean age 3.5 years; SD 0.6), all met ADI-R algorithm criteria for autism. ADI-R assessments were repeated at follow up (FU; mean age 10.5 years; SD 0.8). Changes in ADI-R total, domain and ADI-R algorithm item scores were assessed. Twentyeight children continued to score above the ADI-R cut-off for autism at FU, although significant decreases in ADI-R domain and item scores were also found. In conclusion, while classification of children according to ADI-R criteria, generally remained stable between pre-school and elementary school age, many children demonstrated significant improvements in symptom severity

Extending the concept of research impact literacy: levels of literacy, institutional role and ethical considerations

Building on the concept of ‘impact literacy’ established in a previous paper from Bayley and Phipps, here we extend the principles of impact literacy in light of further insights into sector practice. More specifically, we focus on three additions needed in response to the sector-wide growth of impact: (1) differential levels of impact literacy; (2) institutional impact literacy and environment for impact; and (3) issues of ethics and values in research impact. This paper invites the sector to consider the relevance of all dimensions in establishing, maintaining and strengthening impact within the research landscape. We explore implications for individual professional development, institutional capacity building and ethical collaboration to maximise societal benefit

A monodisperse transmembrane α-helical peptide barrel

The fabrication of monodisperse transmembrane barrels formed from short synthetic peptides has not been demonstrated previously. This is in part because of the complexity of the interactions between peptides and lipids within the hydrophobic environment of a membrane. Here we report the formation of a transmembrane pore through the self-assembly of 35 amino acid α-helical peptides. The design of the peptides is based on the C-terminal D4 domain of the Escherichia coli polysaccharide transporter Wza. By using single-channel current recording, we define discrete assembly intermediates and show that the pore is most probably a helix barrel that contains eight D4 peptides arranged in parallel. We also show that the peptide pore is functional and capable of conducting ions and binding blockers. Such α-helix barrels engineered from peptides could find applications in nanopore technologies such as single-molecule sensing and nucleic-acid sequencing