Quantifying the Bull's Eye Effect

We have used N-body simulations to develop two independent methods to quantify redshift distortions known as the Bull's Eye effect (large scale infall plus small scale virial motion). This effect depends upon the mass density, $\Omega_0$, so measuring it can in principle give an estimate of this important cosmological parameter. We are able to measure the effect and distinguish between its strength for high and low values of $\Omega_0$. Unlike other techniques which utilize redshift distortions, one of our methods is relatively insensitive to bias. In one approach, we use path lengths between contour crossings of the density field. The other is based upon percolation. We have found both methods to be successful in quantifying the effect and distinguishing between values of $\Omega_0$. However, only the path lengths method exhibits low sensitivity to bias.Comment: 21 pages, 5 figures, 3 tables; Replaced version - minor corrections, replaced figure 2; To appear in ApJ, Jan. 20, 200

Ras-mediated phosphorylation of a conserved threonine residue enhances the transactivation activities of c-Ets1 and c-Ets2

The Ras oncogene products regulate the expression of genes in transformed cells, and members of the Ets family of transcription factors have been implicated in this process. To determine which Ets factors are the targets of Ras signaling pathways, the abilities of several Ets factors to activate Ras-responsive enhancer (RRE) reporters in the presence of oncogenic Ras were examined. In transient transfection assay, reporters containing RREs composed of Ets-AP-1 binding sites could be activated 30-fold in NIH 3T3 fibroblasts and 80-fold in the macrophage-like line RAW264 by the combination of Ets1 or Ets2 and Ras but not by several other Ets factors that were tested in the assay. Ets2 and Ras also superactivated an RRE composed of Ets-Ets binding sites, but the Ets-responsive promoter of the c-fms gene was not superactivated. Mutation of a threonine residue to alanine in the conserved amino-terminal regions of Ets1 and Ets2 (threonine 38 and threonine 72, respectively) abrogated the ability of each of these proteins to superactivate reporter gene expression. Phosphoamino acid analysis of radiolabeled Ets2 revealed that Ras induced normally absent threonine-specific phosphorylation of the protein. The Ras-dependent increase in threonine phosphorylation was not observed in Ets2 proteins that had the conserved threonine 72 residue mutated to alanine or serine. These data indicate that Ets1 and Ets2 are specific nuclear targets of Ras signaling events and that phosphorylation of a conserved threonine residue is a necessary molecular component of Ras-mediated activation of these transcription factors

Preparation of Dicke States in an Ion Chain

We have investigated theoretically and experimentally a method for preparing Dicke states in trapped atomic ions. We consider a linear chain of $N$ ion qubits that is prepared in a particular Fock state of motion, $|m>$. The $m$ phonons are removed by applying a laser pulse globally to the $N$ qubits, and converting the motional excitation to $m$ flipped spins. The global nature of this pulse ensures that the $m$ flipped spins are shared by all the target ions in a state that is a close approximation to the Dicke state \D{N}{m}. We calculate numerically the fidelity limits of the protocol and find small deviations from the ideal state for $m = 1$ and $m = 2$. We have demonstrated the basic features of this protocol by preparing the state \D{2}{1} in two $^{25}$Mg$^+$ target ions trapped simultaneously with an $^{27}$Al$^+$ ancillary ion.Comment: 5 pages, 2 figure

Active transport, independent mobility and territorial range among children residing in disadvantaged areas

Available online 14 March 2014Regular physical activity during childhood and adolescence promotes physical and mental health across the lifespan. Walking and cycling for transport may be important, inexpensive and accessible sources of physical activity among socioeconomically disadvantaged youth. This study aimed to examine active transport and independent mobility (i.e. walking/cycling without adult accompaniment) on journeys to school and other local destinations, and their associations with children's physical activity in disadvantaged urban and rural areas of Victoria, Australia. In addition, associations were examined between children's perceived accessibility of local destinations by walking/cycling and their territorial range (i.e. how far they were allowed to roam without adult accompaniment).Survey-reported active transport, independent mobility, territorial range, and objectively-measured physical activity were analysed for 271 children (mean age 12.1 (SD 2.2) years). Habitual travel modes (on 3 or more days/week) were examined. Car travel was most prevalent to (43%) and from (33%) school, while 25% walked to school, 31% walked home, and few cycled (6%). Most walking/cycling trips were made independently. Total weekly duration rather than frequency of active transport to school was positively associated with physical activity. No associations were found between independent mobility and physical activity. Territorial range was restricted - only a third of children were allowed to roam more than 15. min from home alone, while approximately half were allowed to do so with friends. The number of accessible destination types in the neighbourhood was positively associated with territorial range. This research provides evidence of how active transport contributes to children's physical activity and a preliminary understanding of children's independent mobility on journeys to school and local destinations. Further research is required to explore influences on these behaviours.Alison Carver, Jenny Veitch, Shannon Sahlqvist, David Crawford, Clare Hum

From Non-human to Human: Adult's and Children's Perceptions of Agents Varying in Humanness

While most interface agents have been designed from an adult perspective, the present paper compares adults’ and children’s views of agents that vary in their degree of humanness. Four synthetic characters ranging in appearance from non-human to very human (blob, cat, cartoon, human) were presented to adult and children perceivers and were evaluated with respect to their cognitive and emotional abilities. The visual appearance significantly influenced participants’ ratings in both age groups. However, the pattern of results was more differentiated for adult perceivers as a function of the human-likeness of the character. The findings suggest that children may rely less on human-like features in inferring agents’ capabilities which are judged along simpler cognitive and social dimensions. Implications for the design of artificial agents are discussed