Symmetry breaking from confined water wave fields propels an oscillating robot

We discover a new phenomenon in which a symmetrically oscillating, free-floating robot can be attracted to or repelled from a horizontal boundary. The device generates radially expanding gravity-capillary (GC) waves at the fluid surface. Visualization of the wave field dynamics reveals that when near a boundary, the complex interference of generated and reflected waves induces a wave amplitude asymmetry that generates a net radiation force that drives robot motion. Direct force measurements reveal that attraction increases as wave frequency increases or robot-boundary separation decreases. Theory on confined GC wave radiation dynamics developed by Hocking in the 1980s captures the observed parameter dependence due to these ``Hocking fields".Comment: 11 pages, 5 figures, 8 supplementary figure

Toward an integrative understanding of social behavior: new models and new opportunities.

Social interactions among conspecifics are a fundamental and adaptively significant component of the biology of numerous species. Such interactions give rise to group living as well as many of the complex forms of cooperation and conflict that occur within animal groups. Although previous conceptual models have focused on the ecological causes and fitness consequences of variation in social interactions, recent developments in endocrinology, neuroscience, and molecular genetics offer exciting opportunities to develop more integrated research programs that will facilitate new insights into the physiological causes and consequences of social variation. Here, we propose an integrative framework of social behavior that emphasizes relationships between ultimate-level function and proximate-level mechanism, thereby providing a foundation for exploring the full diversity of factors that underlie variation in social interactions, and ultimately sociality. In addition to identifying new model systems for the study of human psychopathologies, this framework provides a mechanistic basis for predicting how social behavior will change in response to environmental variation. We argue that the study of non-model organisms is essential for implementing this integrative model of social behavior because such species can be studied simultaneously in the lab and field, thereby allowing integration of rigorously controlled experimental manipulations with detailed observations of the ecological contexts in which interactions among conspecifics occur

Preparation, imaging, and quantification of bacterial surface motility assays.

Publication fees for this article were partially sponsored by Bruker Corporation.International audienceBacterial surface motility, such as swarming, is commonly examined in the laboratory using plate assays that necessitate specific concentrations of agar and sometimes inclusion of specific nutrients in the growth medium. The preparation of such explicit media and surface growth conditions serves to provide the favorable conditions that allow not just bacterial growth but coordinated motility of bacteria over these surfaces within thin liquid films. Reproducibility of swarm plate and other surface motility plate assays can be a major challenge. Especially for more "temperate swarmers" that exhibit motility only within agar ranges of 0.4%-0.8% (wt/vol), minor changes in protocol or laboratory environment can greatly influence swarm assay results. "Wettability", or water content at the liquid-solid-air interface of these plate assays, is often a key variable to be controlled. An additional challenge in assessing swarming is how to quantify observed differences between any two (or more) experiments. Here we detail a versatile two-phase protocol to prepare and image swarm assays. We include guidelines to circumvent the challenges commonly associated with swarm assay media preparation and quantification of data from these assays. We specifically demonstrate our method using bacteria that express fluorescent or bioluminescent genetic reporters like green fluorescent protein (GFP), luciferase (lux operon), or cellular stains to enable time-lapse optical imaging. We further demonstrate the ability of our method to track competing swarming species in the same experiment

UVUDF: Ultraviolet Imaging of the Hubble Ultradeep Field with Wide-field Camera 3

We present an overview of a 90-orbit Hubble Space Telescope treasury program to obtain near ultraviolet imaging of the Hubble Ultra Deep Field using the Wide Field Camera 3 UVIS detector with the F225W, F275W, and F336W filters. This survey is designed to: (i) Investigate the episode of peak star formation activity in galaxies at 1<z<2.5; (ii) Probe the evolution of massive galaxies by resolving sub-galactic units (clumps); (iii) Examine the escape fraction of ionizing radiation from galaxies at z~2-3; (iv) Greatly improve the reliability of photometric redshift estimates; and (v) Measure the star formation rate efficiency of neutral atomic-dominated hydrogen gas at z~1-3. In this overview paper, we describe the survey details and data reduction challenges, including both the necessity of specialized calibrations and the effects of charge transfer inefficiency. We provide a stark demonstration of the effects of charge transfer inefficiency on resultant data products, which when uncorrected, result in uncertain photometry, elongation of morphology in the readout direction, and loss of faint sources far from the readout. We agree with the STScI recommendation that future UVIS observations that require very sensitive measurements use the instrument's capability to add background light through a "post-flash". Preliminary results on number counts of UV-selected galaxies and morphology of galaxies at z~1 are presented. We find that the number density of UV dropouts at redshifts 1.7, 2.1, and 2.7 is largely consistent with the number predicted by published luminosity functions. We also confirm that the image mosaics have sufficient sensitivity and resolution to support the analysis of the evolution of star-forming clumps, reaching 28-29th magnitude depth at 5 sigma in a 0.2 arcsecond radius aperture depending on filter and observing epoch.Comment: Accepted A

Testing the Parentâ Adolescent Acculturation Discrepancy Hypothesis: A Fiveâ Wave Longitudinal Study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134121/1/jora12214.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134121/2/jora12214_am.pd

Longitudinal Trajectories of Family Functioning Among Recent Immigrant Adolescents and Parents: Links With Adolescent and Parent Cultural Stress, Emotional Wellâ Being, and Behavioral Health

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148234/1/cdev12914.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148234/2/cdev12914_am.pd

A bioinventory of select terrestrial insects at Braidwood Dunes and Savanna Nature Preserve (Will County, Illinois)

We conducted an inventory of select terrestrial insect groups at Braidwood Dunes and Savanna Nature Preserve in 2011 and 2012. A total of 823 unique species, representing 19 orders of Hexapods, were recorded using a variety of sampling methods (including: light trapping, pitfall trapping, sweep net, vacuum sample, litter sample, soil core, wine rope, visual transect). Intensive studies focused on springtails (Collembola), grasshoppers, crickets and katydids (Orthoptera), true bugs (Hemiptera: Heteroptera), leafhoppers and kin (Hemiptera: Auchenorrhyncha), ground beetles (Coleoptera: Carabidae) and butterflies and macromoths (Lepidoptera). We estimate that our records comprise around 11% of the total fauna of Hexapoda that occur at this 315--‐acre site. We evaluated sampling completeness for each group and compared, richness, diversity and evenness across habitat types. Special attention was focused on midwestern remnant dependent species, conservative prairie and savanna insects of the Chicago Wilderness region, and species that appear on Illinois' list of species in greatest need of conservation. We provide the Forest Preserve District of Will County with management recommendations relating to the terrestrial for this site, as well as a large collection of images covering many of the species we encountered. Braidwood Dunes and Savanna Nature Preserve contains a variety of rare and understudied species, some of which have only infrequently been encountered. These animals play a Cover photo: Papaipema speciosissima (Noctuidae), the Osmunda Borer Moth 3 wide variety of roles within the ecosystem and various habitats, and warrant special consideration and appreciation not only by land managers but also by the members of the public with an interest in the natural world.unpublishednot peer reviewe

Who Commits to the Rule of Law? Constrained Government and Foreign Direct Investment in Postcommunist States

Research linking credible commitments to the rule of law in terms of property rights and contract enforcement is a hallmark of recent efforts to explain economic growth and development. However, many postcommunist states have had difficulty making such commitments and spurring growth. Many argue political polarization prevents states from reforming laws and protecting property rights in some countries whereas single-party governance renders state promises incredible in others. I analyze pooled cross-sectional time-series data for twenty-four postcommunist countries and provide evidence effective constraints among elected officials act as democratic commitment mechanisms rendering government policies credible