Estimates and estimate-based inferences in young children

The ability of children to perform in estimation-based inference tasks was studied in two experiments. In the first study, children in the CA range 5-7 years were tested for their ability to make increasingly accurate estimates of proportions as a function of CA. A simple visual judgment task which did not involve either verbal stimuli or responses was judgment task was found that there was above-chance level performance at all CA levels and that performance improved as a function of CA. In the second study, measures of the ability to make quantitative inferences were also studied in children in the CA range 6-8 years. It was hypothesized that: (1) performance would be above-chance level at all ages; (2) inferential performance would improve with increasing CA; (3) conservatism, defined here as the constriction of responses to the middle of the response scale, would vary inversely with performance level; and (4) attention strategies would be a significant determiner of performance. All of the hypotheses except (2) were supported. The results were discussed in terms of cognitive models which consider inference strategies and the role of language in the development of these strategies. The studies provide evidence that accurate but nonlogical modes of inference operate in the performance of children within the CA range tested.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33710/1/0000222.pd

Memory strategies in children with learning disabilities

Memory strategies were examined among children, 7-13 years old, with diagnosed learning disabilities, in order to investigate whether they perform in appropriately active and efficient ways. The children were grouped at two age levels and administered tasks of serial recall and free recall. A strategy-training session was conducted on the second task. On the serial recall, neither age group showed evidence of rehearsal, in contrast to previous studies. On the free recall task, the younger children's performance was consistent with the mediation deficiency hypothesis, while the older children improved in sorting, clustering, and recall following training; i.e., they showed a typical production deficiency. There was support for considering this sample of learning disabled children as inactive learners, with potential developmental change. Serial recall improved with age, and the older children's production deficiences in free recall appeared to be ameliorated with training in organizational strategies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24548/1/0000828.pd

Verbal labeling, rehearsal, and short-term memory

The effects of verbal labeling in a serial position short-term memory (STM) task were investigated in two studies. In the first, 32 children at each of the grades 4, 6, and 8 were tested. In the second, 40 college students were tested. The stimuli consisted of eight cards with a central and an incidental picture on each. Half of the subjects overtly labeled the central pictures as they were presented; half did not. In Study I there were eight trials; in Study II there were additional trials in which stimuli contained only the central pictures. In Study I labeling did not affect overall performance; in Study II labeling was found to decrease performance significantly. For both studies labeling had differential effects at the primacy and recency portions of the serial-position data. There was no effect of one versus two stimuli per card in Study II. The findings were discussed in terms of issues concerning verbal mediation and rehearsal strategies. A developmental model for the processes involved in serial-position STM was presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32831/1/0000206.pd

Labeling, rehearsal, and short-term memory in retarded children

A short-term memory task was used to explore the effects of verbal labeling and rehearsal on serial-position recall in mildly retarded 9- to 11-year-old children. A stimulus array consisting of seven cards depicting familiar animals was presented for seven trials. In Expt I, recall when subjects labeled the pictures as they were shown was compared to recall when no labeling occurred. Total recall was not affected, but for the older CA group primacy recall was hindered and recency recall was facilitated by labeling. In Expt II, three variations of rehearsal of the names to be recalled were compared. When prompting accompanied rehearsal, recall improved at both recency and primacy positions. When prompting occurred for the primacy positions only, recall was higher for these positions but not for other positions. These results support the view that verbal skills affect recall in mildly retarded children similarly to normal children.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22264/1/0000701.pd

Month-Timescale Optical Variability in the M87 Jet

A previously inconspicuous knot in the M87 jet has undergone a dramatic outburst and now exceeds the nucleus in optical and X-ray luminosity. Monitoring of M87 with the Hubble Space Telescope and Chandra X-ray Observatory during 2002-2003, has found month-timescale optical variability in both the nucleus and HST-1, a knot in the jet 0.82'' from the nucleus. We discuss the behavior of the variability timescales as well as spectral energy distribution of both components. In the nucleus, we see nearly energy-independent variability behavior. Knot HST-1, however, displays weak energy dependence in both X-ray and optical bands, but with nearly comparable rise/decay timescales at 220 nm and 0.5 keV. The flaring region of HST-1 appears stationary over eight months of monitoring. We consider various emission models to explain the variability of both components. The flares we see are similar to those seen in blazars, albeit on longer timescales, and so could, if viewed at smaller angles, explain the extreme variability properties of those objects.Comment: 4 pages, 3 figures, ApJ Lett., in pres

Measurement of the Condensation Coefficient of Water in the UMR Simulation Chamber

The UMR Cloud Simulation Facility is described. The facility is designed to provide a controlled environment simulating the conditions of natural atmospheric processes. It consists of two cooled-wall expansion cloud chambers and peripheral instrumentation for generation and characterization of aerosols used for cloud formation studies. Results of initial studies of the growth of warm cloud droplets and inferred measurements of the condensation coefficient are described

Towards Space-like Photometric Precision from the Ground with Beam-Shaping Diffusers

We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating $62^{+26}_{-16}$ppm precision in 30 minute bins on a nearby bright star 16-Cygni A (V=5.95) using the ARC 3.5m telescope---within a factor of $\sim$2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V=11.2) and TRES-3b (V=12.4), where the residuals bin down to $180^{+66}_{-41}$ppm in 30 minute bins for WASP-85-Ab---a factor of $\sim$4 of the precision achieved by the K2 mission on this target---and to 101ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests have demonstrated $137^{+64}_{-36}$ppm precision for a $K_S =10.8$ star on the 200" Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets.Comment: Accepted for publication in ApJ. 30 pages, 20 figure

Effects of habitat composition and landscape structure on worker foraging distances of five bumblebee species

Bumblebees (Bombus spp.) are important pollinators of both crops and wild flowers. Their contribution to this essential ecosystem service has been threatened over recent decades by changes in land use, which have led to declines in their populations. In order to design effective conservation measures it is important to understand the effects of variation in landscape composition and structure on the foraging activities of worker bumblebees. This is because the viability of individual colonies is likely to be affected by the trade-off between the energetic costs of foraging over greater distances and the potential gains from access to additional resources. We used field surveys, molecular genetics and fine resolution remote sensing to estimate the locations of wild bumblebee nests and to infer foraging distances across a 20 km2 agricultural landscape in southern England. We investigated five species, including the rare B. ruderatus and ecologically similar but widespread B. hortorum. We compared worker foraging distances between species and examined how variation in landscape composition and structure affected foraging distances at the colony level. Mean worker foraging distances differed significantly between species. Bombus terrestris, B. lapidarius and B. ruderatus exhibited significantly greater mean foraging distances (551 m, 536 m, 501 m, respectively) than B. hortorum and B. pascuorum (336 m, 272 m, respectively). There was wide variation in worker foraging distances between colonies of the same species, which was in turn strongly influenced by the amount and spatial configuration of available foraging habitats. Shorter foraging distances were found for colonies where the local landscape had high coverage and low fragmentation of semi-natural vegetation, including managed agri-environmental field margins. The strength of relationships between different landscape variables and foraging distance varied between species, for example the strongest relationship for B. ruderatus being with floral cover of preferred forage plants. Our findings suggest that favourable landscape composition and configuration has the potential to minimise foraging distances across a range of bumblebee species. There is thus potential for improvements in the design and implementation of landscape management options, such as agri-environment schemes, aimed at providing foraging habitat for bumblebees and enhancing crop pollination services

Microbiota-directed fibre activates both targeted and secondary metabolic shifts in the distal gut

Beneficial modulation of the gut microbiome has high-impact implications not only in humans, but also in livestock that sustain our current societal needs. In this context, we have tailored an acetylated galactoglucomannan (AcGGM) fibre to match unique enzymatic capabilities of Roseburia and Faecalibacterium species, both renowned butyrate-producing gut commensals. Here, we test the accuracy of AcGGM within the complex endogenous gut microbiome of pigs, wherein we resolve 355 metagenome-assembled genomes together with quantitative metaproteomes. In AcGGM-fed pigs, both target populations differentially express AcGGM-specific polysaccharide utilization loci, including novel, mannan-specific esterases that are critical to its deconstruction. However, AcGGM-inclusion also manifests a “butterfly effect”, whereby numerous metabolic changes and interdependent cross-feeding pathways occur in neighboring non-mannanolytic populations that produce short-chain fatty acids. Our findings show how intricate structural features and acetylation patterns of dietary fibre can be customized to specific bacterial populations, with potential to create greater modulatory effects at large