Silk from Crickets: A New Twist on Spinning

Raspy crickets (Orthoptera: Gryllacrididae) are unique among the orthopterans in producing silk, which is used to build shelters. This work studied the material composition and the fabrication of cricket silk for the first time. We examined silk-webs produced in captivity, which comprised cylindrical fibers and flat films. Spectra obtained from micro-Raman experiments indicated that the silk is composed of protein, primarily in a beta-sheet conformation, and that fibers and films are almost identical in terms of amino acid composition and secondary structure. The primary sequences of four silk proteins were identified through a mass spectrometry/cDNA library approach. The most abundant silk protein was large in size (300 and 220 kDa variants), rich in alanine, glycine and serine, and contained repetitive sequence motifs; these are features which are shared with several known beta-sheet forming silk proteins. Convergent evolution at the molecular level contrasts with development by crickets of a novel mechanism for silk fabrication. After secretion of cricket silk proteins by the labial glands they are fabricated into mature silk by the labium-hypopharynx, which is modified to allow the controlled formation of either fibers or films. Protein folding into beta-sheet structure during silk fabrication is not driven by shear forces, as is reported for other silks

Positions and sizes of X-ray solar flare sources

<p><b>Aims:</b> The positions and source sizes of X-ray sources taking into account Compton backscattering (albedo) are investigated.</p> <p><b>Methods:</b> Using a Monte Carlo simulation of X-ray photon transport including photo-electric absorption and Compton scattering, we calculate the apparent source sizes and positions of X-ray sources at the solar disk for various source sizes, spectral indices and directivities of the primary source.</p> <p><b>Results:</b> We show that the albedo effect can alter the true source positions and substantially increase the measured source sizes. The source positions are shifted by up to ~0.5” radially towards the disk centre and 5 arcsec source sizes can be two times larger even for an isotropic source (minimum albedo effect) at 1 Mm above the photosphere. The X-ray sources therefore should have minimum observed sizes, and thus their FWHM source size (2.35 times second-moment) will be as large as ~7” in the 20-50 keV range for a disk-centered point source at a height of 1 Mm (~1.4”) above the photosphere. The source size and position change is greater for flatter primary X-ray spectra, a stronger downward anisotropy, for sources closer to the solar disk centre, and between the energies of 30 and 50 keV.</p> <p><b>Conclusions:</b> Albedo should be taken into account when X-ray footpoint positions, footpoint motions or source sizes from e.g. RHESSI or Yohkoh data are interpreted, and we suggest that footpoint sources should be larger in X-rays than in either optical or EUV ranges.</p&gt

Technology developments for a large-format heterodyne MMIC array at W-band

We report on the development of W-band (75–110 GHz) heterodyne receiver technology for large-format astronomical arrays. The receiver system is designed to be both mass producible, so that the designs could be scaled to thousands of receiver elements, and modular. Most of the receiver functionality is integrated into compact monolithic microwave integrated circuit (MMIC) amplifier-based multichip modules. The MMIC modules include a chain of InP MMIC low-noise amplifiers, coupled-line bandpass filters, and sub-harmonic Schottky diode mixers. The receiver signals will be routed to and from the MMIC modules on a multilayer high-frequency laminate, which includes splitters, amplifiers, and frequency triplers. A prototype MMIC module has exhibited a band-averaged noise temperature of 41 K from 82 to 100 GHz and a gain of 29 dB at 15 K, which is the state-of-the-art for heterodyne multichip modules

Putting lives in danger? Tinker, tailor, journalist, spy: the use of journalistic cover

The Anglo-American intelligence agencies’ use of journalists as spies or propagandists and the practice of providing intelligence agents in the field with journalistic cover have been a source of controversy for many decades. This paper examines the extent to which these covert practices have taken place and whether they have put journalists’ lives in danger. This paper, drawing on various methodologies, examines a number of cases where the arrest, murder or kidnap of journalists was justified on the grounds that the journalist was a ‘spy’. This has been followed through with research using a range of sources that shows there have been many occasions when the distinction between spies and journalists has been opaque. The paper concludes that widespread use of journalistic cover by spies has put lives in danger but the extent is unquantifiable

Complexities in barrier island response to sea level rise : insights from numerical model experiments, North Carolina Outer Banks

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 115 (2010): F03004, doi:10.1029/2009JF001299.Using a morphological-behavior model to conduct sensitivity experiments, we investigate the sea level rise response of a complex coastal environment to changes in a variety of factors. Experiments reveal that substrate composition, followed in rank order by substrate slope, sea level rise rate, and sediment supply rate, are the most important factors in determining barrier island response to sea level rise. We find that geomorphic threshold crossing, defined as a change in state (e.g., from landward migrating to drowning) that is irreversible over decadal to millennial time scales, is most likely to occur in muddy coastal systems where the combination of substrate composition, depth-dependent limitations on shoreface response rates, and substrate erodibility may prevent sand from being liberated rapidly enough, or in sufficient quantity, to maintain a subaerial barrier. Analyses indicate that factors affecting sediment availability such as low substrate sand proportions and high sediment loss rates cause a barrier to migrate landward along a trajectory having a lower slope than average barrier island slope, thereby defining an “effective” barrier island slope. Other factors being equal, such barriers will tend to be smaller and associated with a more deeply incised shoreface, thereby requiring less migration per sea level rise increment to liberate sufficient sand to maintain subaerial exposure than larger, less incised barriers. As a result, the evolution of larger/less incised barriers is more likely to be limited by shoreface erosion rates or substrate erodibility making them more prone to disintegration related to increasing sea level rise rates than smaller/more incised barriers. Thus, the small/deeply incised North Carolina barriers are likely to persist in the near term (although their long-term fate is less certain because of the low substrate slopes that will soon be encountered). In aggregate, results point to the importance of system history (e.g., previous slopes, sediment budgets, etc.) in determining migration trajectories and therefore how a barrier island will respond to sea level rise. Although simple analytical calculations may predict barrier response in simplified coastal environments (e.g., constant slope, constant sea level rise rate, etc.), our model experiments demonstrate that morphological-behavior modeling is necessary to provide critical insights regarding changes that may occur in environments having complex geometries, especially when multiple parameters change simultaneously.This work was partially supported by the U.S. Geological Survey, Woods Hole Science Center and a sabbatical leave fellowship from Oberlin College to Laura Moore from the Mellon‐8 Consortium

To reverse engineer an entire nervous system

There are many theories of how behavior may be controlled by neurons. Testing and refining these theories would be greatly facilitated if we could correctly simulate an entire nervous system so we could replicate the brain dynamics in response to any stimuli or contexts. Besides, simulating a nervous system is in itself one of the big dreams in systems neuroscience. However, doing so requires us to identify how each neuron's output depends on its inputs, a process we call reverse engineering. Current efforts at this focus on the mammalian nervous system, but these brains are mind-bogglingly complex, allowing only recordings of tiny subsystems. Here we argue that the time is ripe for systems neuroscience to embark on a concerted effort to reverse engineer a smaller system and that Caenorhabditis elegans is the ideal candidate system as the established optophysiology techniques can capture and control each neuron's activity and scale to hundreds of thousands of experiments. Data across populations and behaviors can be combined because across individuals the nervous system is largely conserved in form and function. Modern machine-learning-based modeling should then enable a simulation of C. elegans' impressive breadth of brain states and behaviors. The ability to reverse engineer an entire nervous system will benefit the design of artificial intelligence systems and all of systems neuroscience, enabling fundamental insights as well as new approaches for investigations of progressively larger nervous systems.Comment: 23 pages, 2 figures, opinion pape

Functioning of Coastal River-Dominated Ecosystems and Implications for Oil Spill Response: From Observations to Mechanisms and Models

Coastal river-dominated oceans are physically complex, biologically productive, and intimately connected to human socioeconomic activity. The Deepwater Horizon blowout and subsequent advection of oil into coastal waters of the northern Gulf of Mexico (nGOM) highlighted the complex linkages among oceanographic processes within this river-dominated system and knowledge gaps about it that resulted in imprecise information on both oil transport and ecosystem consequences. The interdisciplinary research program implemented through the CONsortium for oil exposure pathways in COastal River-Dominated Ecosystems (CONCORDE) is designed to identify and quantitatively assess key physical, biological, and geochemical processes acting in the nGOM, in order to provide the foundation for implementation of a synthesis model (coupled circulation and biogeochemistry) of the nGOM shelf system that can ultimately aid in prediction of oil spill transport and impacts. CONCORDE field and modeling efforts in 2015–2016 focused on defining the influence of freshwater input from river plumes in the nGOM. In situ observations, combined with field-deployed and simulated drifters, show considerable variability in the spatial extent of freshwater influence that is related to wind direction and strength. Increased primary production and particle abundance (a proxy for secondary production) was observed during the spring when nGOM shelf waters were becoming stratified. Zooplankton and marine snow displayed intense vertical and horizontal patchiness during all seasons, often aggregating near the halocline. Simulations of a neutrally buoyant tracer released offshore of the Mississippi Bight showed surface advection of low tracer concentrations onto the inner shelf under high river discharge, high stratification, and variable wind conditions compared to almost no advection onto the inner shelf under low discharge, negligible stratification, and generally northeasterly winds. The interconnectedness of environmental variables and biological activity indicate that multiple factors can affect the transport of oil and the resulting ecological impacts. The process-oriented understanding provided by CONCORDE is necessary to predict ecosystem-level impacts of oil spills, and these results are applicable to other river-dominated coastal systems worldwide that often support oil extraction activities

The Prohibition of the Proposed Springer-Prosiebensat.1-Merger: How Much Economics in German Merger Control?

We review the Bundeskartellamt (Federal Cartel Office Germany) decision on the proposed merger between Springer and ProSiebenSat.1 from an economic point of view. In doing so, it is not our goal to analyse whether the controversial decision by the Bundeskar-tellamt has been correct or flawed from a legal point of view. Instead, we analyse whether the economic reasoning in the decision document reflects state-of-the-art economic theory on conglomerate mergers. Regarding such types of mergers, anticompetitive effects either do not occur regularly or are more often than not overcompensated by efficiency gains, so that a standard welfare perspective demands reluctance concerning antitrust interventions. This is particularly true if two-sided markets, like media markets, are involved. However, anticompe-titive conglomerate mergers are not impossible, in particular in neighbouring markets where there is some relationship between the products of the merging companies. In line with the more-economic approach in European merger control, a particular thorough line of argumen-tation, backed with particularly convincing economic evidence, is necessary to justify a pro-hibition of a conglomerate merger from an economic point of view. Against this background, we do not find the reasoning of the Bundeskartellamt entirely convincing and sufficiently strong to justify a prohibition of the proposed combination from an economic perspective. The reasons are that (i) the Bundeskartellamt fails to continuously consider consumer and customer welfare as the relevant standards, (ii) positive efficiency and welfare effects of cross-media strategies are neglected, (iii) in contrast, the competition agency sometimes ap-pears to view profitability of post-merger strategy options to be per se anticompetitive (effi-ciency offence), (iv) the incontestability of the relevant markets is not sufficiently substanti-ated, (v) inconsistencies occur regarding the symmetry of the TV advertising market duopoly versus the unique role of the BILD-Zeitung and (vi) the employment of modern economic instruments appears to be underdeveloped. Thus, we conclude that the Bundeskartellamt has not embraced the European more-economic approach in the analysed decision. However, one can discuss whether economic effects are overcompensated in this case by concerns about a reduction in diversity of opinion and threats to free speech. Similar to the Bundeskartellamt, we do not consider these concerns in our analysis