Evolution and complexity: the double-edged sword

We attempt to provide a comprehensive answer to the question of whether, and when, an arrow of complexity emerges in Darwinian evolution. We note that this expression can be interpreted in different ways, including a passive, incidental growth, or a pervasive bias towards complexification. We argue at length that an arrow of complexity does indeed occur in evolution, which can be most reasonably interpreted as the result of a passive trend rather than a driven one. What, then, is the role of evolution in the creation of this trend, and under which conditions will it emerge? In the later sections of this article we point out that when certain proper conditions (which we attempt to formulate in a concise form) are met, Darwinian evolution predictably creates a sustained trend of increase in maximum complexity (that is, an arrow of complexity) that would not be possible without it; but if they are not, evolution will not only fail to produce an arrow of complexity, but may actually prevent any increase in complexity altogether. We conclude that, with regard to the growth of complexity, evolution is very much a double-edged sword

Variability in the extreme helium star LSS 5121

We report a photometric and spectroscopic study of the hot extreme helium star LSS 5121. We found photometric variability, but no period was evident in its periodogram. This is consistent with the previous proposal, based on spectral line variations, that LSS 5121 is a non-radial pulsator similar to other hot extreme helium stars.Comment: 5 pages, 6 figure

Tunable Integrated-Optics Nanoscaled Devices Based on Magnetic Photonic Crystals

Magnetooptical properties of magnetic photonic crystals have been investigated in the view of their possible applications for the modern integrated-optics devices. A "transfer matrices" formalism was expanded for the case of oblique light incidence on the periodic nanoscaled magnetic multilayered systems. Several new effects such as the Faraday effect dependence on the incidence angle and the tunability of the bandgap defect modes spectral location by external magnetic fields were found. Several possibilities of one-dimensional magnetic photonic crystals applications for the optical devices are discussed. Initial steps towards the practical implementation of the proposed devices are reported.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Temperature and gravity of the pulsating extreme helium star LSS 3184 (BX Cir) through its pulsation cycle

We report the analysis of optical spectra of the extreme helium star LSS 3184 (BX Cir) to determine its effective temperature and gravity throughout its pulsation cycle. The spectra were also used to measure its chemical abundances. We report rest gravity, log g = 3.38 +/- 0.02, and a chemical abundance mixture consistent with those reported earlier in a study using an optical spectrum with lower spectral resolution and a lower signal to noise ratio. Our analysis decreases the upper limit for the H abundance to H < 6.0 (mass fraction < 7.1 x 10^-7). Our gravity corresponds to stellar mass M = 0.47 +/- 0.03 M_sun. We find that the effective log g varies through the pulsation cycle with an amplitude of 0.28 dex. The effective gravity is smaller than the rest gravity except when the star is very near its minimum radius. The change in effective gravity is primarily caused by acceleration of the stellar surface. Based on the optical spectra, we find the temperature varies with an amplitude of 3450 K. We find a time averaged mean temperature, 23390 +/- 90 K, consistent with that found in the earlier optical spectrum study. The mean temperature is 1750 K hotter than that found using combined ultraviolet spectra and V and R photometry and the variation amplitude is larger. This discrepancy is similar to that found for the extreme helium star V652 Her.Comment: 7 pages, 6 figures, LaTeX, to be published in A&

Subaru and Swift observations of V652 Herculis: resolving the photospheric pulsation

High-resolution spectroscopy with the Subaru High Dispersion Spectrograph, and Swift ultraviolet photometry are presented for the pulsating extreme helium star V652 Her. Swift provides the best relative ultraviolet photometry obtained to date, but shows no direct evidence for a shock at ultraviolet or X-ray wavelengths. Subaru has provided high spectral and high temporal resolution spectroscopy over six pulsation cycles (and eight radius minima). These data have enabled a line-by-line analysis of the entire pulsation cycle and provided a description of the pulsating photosphere as a function of optical depth. They show that the photosphere is compressed radially by a factor of at least 2 at minimum radius, that the phase of radius minimum is a function of optical depth and the pulse speed through the photosphere is between 141 and 239 km s−1 (depending how measured) and at least 10 times the local sound speed. The strong acceleration at minimum radius is demonstrated in individual line profiles; those formed deepest in the photosphere show a jump discontinuity of over 70 kms−1 on a time-scale of 150 s. The pulse speed and line profile jumps imply a shock is present at minimum radius. These empirical results provide input for hydrodynamical modelling of the pulsation and hydrodynamical plus radiative transfer modelling of the dynamical spectra

Big Money, Nuclear Subsidies, and Systemic Corruption

capital as power corruption differential capitalization nuclear energy subsidies taxOver the past decade, the cost of renewable energy like solar and wind has dropped substantially, while the cost of nuclear energy has risen – yet, in the United States, the large corporate owners of nuclear reactors are subsidized to the teeth. This research examines how their differential capitalized power is nourished and boosted, often through corruption, and how this process undermines consumers and risks the future of humanity

Optimal Population Codes for Space: Grid Cells Outperform Place Cells

Rodents use two distinct neuronal coordinate systems to estimate their position: place fields in the hippocampus and grid fields in the entorhinal cortex. Whereas place cells spike at only one particular spatial location, grid cells fire at multiple sites that correspond to the points of an imaginary hexagonal lattice. We study how to best construct place and grid codes, taking the probabilistic nature of neural spiking into account. Which spatial encoding properties of individual neurons confer the highest resolution when decoding the animal’s position from the neuronal population response? A priori, estimating a spatial position from a grid code could be ambiguous, as regular periodic lattices possess translational symmetry. The solution to this problem requires lattices for grid cells with different spacings; the spatial resolution crucially depends on choosing the right ratios of these spacings across the population. We compute the expected error in estimating the position in both the asymptotic limit, using Fisher information, and for low spike counts, using maximum likelihood estimation. Achieving high spatial resolution and covering a large range of space in a grid code leads to a trade-off: the best grid code for spatial resolution is built of nested modules with different spatial periods, one inside the other, whereas maximizing the spatial range requires distinct spatial periods that are pairwisely incommensurate. Optimizing the spatial resolution predicts two grid cell properties that have been experimentally observed. First, short lattice spacings should outnumber long lattice spacings. Second, the grid code should be self-similar across different lattice spacings, so that the grid field always covers a fixed fraction of the lattice period. If these conditions are satisfied and the spatial “tuning curves” for each neuron span the same range of firing rates, then the resolution of the grid code easily exceeds that of the best possible place code with the same number of neurons

Phenology of Apothecium Production in Populations of Monilinia vaccinii-corymbosi from Early- and Late-Maturing Blueberry Cultivars

Pseudosclerotia were evaluated for differences in timing of apothecium development in four controlled experiments conducted over a 2-year period. In a separate experiment, conidia from 10 randomly selected isolates from both of the fungal populations were used to inoculate open flowers. Germination of pseudosclerotia produced from these artificial inoculations also was evaluated. The timing and rate of shoot elongation for cvs. Weymouth and Jersey were assessed in one greenhouse and two field experiments. Average development times for the fungal population from cv. Weymouth were 8 to 15 days earlier or 33 to 42% less than those for the population from cv. Jersey. The fungal population from Weymouth also exhibited less variation in development times for each developmental stage measured. Similarly, germination of pseudosclerotia produced in artificial inoculations differed between populations. On average, pseudosclerotia derived from the Weymouth population produced apothecia 16 days earlier. During spring 1995 and 1996, vegetative and truss buds on cv. Weymouth developed 4 to 16 days earlier than those on cv. Jersey. These results demonstrate that M. vaccinii-corymbosi exhibits variation in timing of pseudosclerotia germination and apothecium development within and between populations. We hypothesize that differences observed in the timing of apothecium development are related to the fitness of the populations on their original host cultivars and were selected by host phenolog

Adolescents’ Writing in the Content Areas: National Study Results

While many adolescents in US school settings do not achieve basic levels of writing proficiency, new standards and assessments hold all students, regardless of academic performance history and language background, to higher standards for disciplinary writing. In response to calls for research that can characterize a range of adolescents’ writing experiences, this study investigated the amount and kinds of writing adolescents with different academic performance histories and language backgrounds produced in math, science, social studies, and English language arts classes in schools with local reputations of excellence. By applying categories of type and length, we analyzed the writing of 66 students from California, Kentucky, New York, and Texas: 26 English learners (L2) and 40 native English speakers (L1), of whom 19 were identified by school norms as lower performing and 21 were identified as higher performing. We found the majority of writing tasks adolescents completed did not require composing more than a paragraph. Exceptions were essays in English language arts and persuasive essays and reports in social studies—almost half of which were source-based tasks. In addition, considerable differences were noted in the range of genres and amount of extended writing produced among L1 writers with histories of higher performance in contrast with L1 writers with histories of lower performance and L2 writers. These findings are discussed in light of Common Core State Standards shifts and the implications they hold for content area teachers who teach adolescents with different achievement histories and language backgrounds