A second look at the colors of the dinosaurs

In earlier work, I predicted that we would probably not be able to determine the colors of the dinosaurs. I lost this epistemic bet against science in dramatic fashion when scientists discovered that it is possible to draw inferences about dinosaur coloration based on the microstructure of fossil feathers (Vinther et al., 2008). This paper is an exercise in philosophical error analysis. I examine this episode with two questions in mind. First, does this case lend any support to epistemic optimism about historical science? Second, under what conditions is it rational to make predictions about what questions scientists will or will not be able answer? In reply to the first question, I argue that the recent work on the colors of the dinosaurs matters less to the debate about the epistemology of historical science than it might seem. In reply to the second question, I argue that it is difficult to specify a policy that would rule out the failed bet without also being too conservative.     

Paradigmatic Road Blocks in Elementary School Science “Reform”: Reconsidering Nature-of-Science Teaching Within a Rational-Realist Milieu

Although governments espouse development in students of comprehensive science literacy, excessive teaching of achievements of science tends to compromise students' development of realistic conceptions about science and expertise for doing science. For most students, school science is like being chained inside Plato's cave, only able to experience and interpret the world of science from flickering, shadowy images. This can be particularly problematic for students in elementary schools, who may not be developmentally ready for abstract topics inherent to nature of science discussions and whose teachers tend to have low science self-efficacy beliefs. In the mainly qualitative ethnographic study of a 3-year, large-scale collaborative action research project reported here, a significant additional factor limiting students' access to more contemporary views about and realistic experiences with science, however, was government curriculum policy—which promotes highly idealized portrayals of and regulated experiences with science. Data and arguments for these claims are provided.     

The use of electro-deoxidation in molten salts to reduce the energy consumption of solar grade silicon and increase the output of PV solar cells

Solar photovoltaics, based upon silicon, are the most popular form of solar cell with efficiencies around 20%. These efficiencies can be further increased by employing light trapping schemes to minimise optical losses through scattering and reflection which enhances the amount of light absorbed and number of photo-carriers generated. Typical approaches employ antireflection coatings (ARCs) or texturise the surface of the silicon disks, so that the structure consists of an array of needles which can absorb most of the light. Usually, these structures are created by leaching the silicon with hydrofluoric-based acids or by reactive ion etching (RIE) methods. This paper reviews some of the methods for improving the energy efficiency of silicon production, and describes the use of electro-deoxidation of SiO2 layers, on silicon, in molten calcium chloride to form nano-porous black silicon (b-Si) structures. By coating b-Si surface with TiO2, a common ARC, extremely black surfaces with negligible reflectance of about 0.1%, are produced, which can have applications for low-cost high efficiency solar cells.     

Burrow occupancy patterns of the Western Burrowing Owl in southern Nevada

Understanding long-term patterns of burrow occupancy for the Western Burrowing Owl ( Athene cunicularia hypugaea ) is necessary for the conservation of this species, especially in arid, desert ecosystems where burrow occupancy data are lacking. Monthly burrow monitoring was conducted over a 4-year period (1997–2001) in southern Nevada to determine burrow occupancy patterns of Burrowing Owls and to evaluate the effects of burrow type and desert region on burrow occupancy. Burrow occupancy occurred year-round and was most consistent in the Transition region and tended to be lowest in the Mojave Desert region. Peak burrow occupancy occurred during March through May, followed by a gradual decline in occupancy through the summer and fall until January and February, when occupancy was lowest. Occupancy was significantly higher at sites with both culvert and pipe burrows than at sites with earthen burrows in disturbed habitat or earthen burrows in natural habitat. Breeding-season occupancy was not significantly higher in wetter, cooler portions (e.g., Great Basin desert region) of the study area. Results suggest that occupancy is influenced by habitat features—such as suitable burrows in open areas with low vegetation—and climatic regime.     

Silurian brachiopods with soft-tissue preservation

'Articulated' rhynchonelliformean brachiopods are abundant shelly fossils, but the direct fossil record of their soft parts was hitherto confined to a single pyritized trace possibly representing a lophophore. Anatomical knowledge of extinct rhynchonelliformeans relies heavily on analogies to extant species; these analogies are untested for stem-group clades. The Silurian Herefordshire (UK) Konservat-Lagerst?tte (about 425 Myr bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a stem-group rhynchonelliformean specimen from this deposit; it most probably belongs in the order Orthida. A robust ridged pedicle with distal rootlets is preserved, together with a lophophore and other soft-tissue structures. The pedicle morphology is novel, urging caution in inferring stem-group rhynchonelliformean anatomy from that of crown-group species. Smaller brachiopods are attached to the specimen; these include a probable atrypide, with pedicle and marginal setae preserved.     

A physical map of the chicken genome

Strategies for assembling large, complex genomes have evolved to include a combination of whole-genome shotgun sequencing and hierarchal map-assisted sequencing. Whole-genome maps of all types can aid genome assemblies, generally starting with low-resolution cytogenetic maps and ending with the highest resolution of sequence. Fingerprint clone maps are based upon complete restriction enzyme digests of clones representative of the target genome, and ultimately comprise a near-contiguous path of clones across the genome. Such clone-based maps are used to validate sequence assembly order, supply long-range linking information for assembled sequences, anchor sequences to the genetic map and provide templates for closing gaps. Fingerprint maps are also a critical resource for subsequent functional genomic studies, because they provide a redundant and ordered sampling of the genome with clones. In an accompanying paper we describe the draft genome sequence of the chicken, Gallus gallus, the first species sequenced that is both a model organism and a global food source. Here we present a clone-based physical map of the chicken genome at 20-fold coverage, containing 260 contigs of overlapping clones. This map represents approximately 91% of the chicken genome and enables identification of chicken clones aligned to positions in other sequenced genomes.     

下水道中高盐度生活污水的微生物反应研究与水质转化数学模拟

通过72 h的连续批量实验,分析高盐度生活污水在下水道环境中的主要微生物反应以及这些微生物反应对水质的影响。实验共进行两组,每组均在3种不同条件的反应器中进行,各反应器中均进行连续72h小时的取样和监测,确定摄氧率(OUR)、硝态氮(NOX)、氨氮(NH3)和溶解态有机碳(DOC)随时间的浓度变化。通过对实验数据的分析,结果表明高、低盐度生活污水在下水道环境中的影响污染物降解的主要微生物反应都是异养微生物的好氧增殖以及有机颗粒物的水解。但与低盐度污水不同的是,高盐度污水中的①硝化反应作用较为明显;②反硝化速率较快,而且由于硝化作用明显,可提供足够的硝氮,因此反硝化反应也不可忽略。根据此分析结果,以活性污泥3号模型(ASM3)为基础,综合考虑复氧、水力和环境温度影响,建立了下水道污水水质模型。经验证,模型可较好地模拟溶解氧、溶解性有机碳、氨氮和硝氮等物质的下水道中的浓度变化。