An Overview of the Upper Carboniferous Fossil Deposit at Linton, Ohio

Author Institution: Department of Paleobiology, National Museum of Natural History, Smithsonian Institution and Museum of Natural History, Princeton UniversityThe cannel coal that underlies the Upper Freeport coal (Westphalian D, Upper Carboniferous) at Linton in Jefferson County, Ohio, has yielded a remarkable fossil assemblage of at least 10 invertebrate taxa and nearly 40 vertebrate taxa. Spirorbid worms, crustaceans (primarily syncarids and conchostracans), and fishes (coelacanths, haplolepid palaeoniscoids, and xenacanth sharks) are the most abundant fossils in the deposit; small aquatic amphibians (including nectridean, temnospondyl, and aistopod species) are also common. Other arthropod and tetrapod taxa are exceedingly rare and possess obvious adaptations for terrestrial existence

High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers

Our research group has been engaged in the past few years in the synthesis of biphenol based partially disulfonated poly(arylene ether sulfone) random copolymers as potential PEMs. This series of polymers are named as BPSH-xx, where BP stands for biphenol, S stands for sulfonated, H stands for acidified and xx represents the degree of disulfonation. All of these sulfonated copolymers phase separate to form nano scale hydrophilic and hydrophobic morphological domains. The hydrophilic phase containing the sulfonic acid moieties causes the copolymer to absorb water. Water confined in hydrophilic pores in concert with the sulfonic acid groups serve the critical function of proton (ion) conduction and water transport in these systems. Both Nafion and BPSH show high proton conductivity at fully hydrated conditions. However proton transport is especially limited at low hydration level for the BPSH random copolymer. It has been observed that the diffusion coefficients of both water and protons change with the water content of the pore. This change in proton and water transport mechanisms with hydration level has been attributed to the solvation of the acid groups and the amount of bound and bulk-like water within a pore. At low hydration levels most of the water is tightly associated with sulfonic groups and has a low diffusion coefficient. This tends to encourage isolated domain morphology. Thus, although there may be significant concentrations of protons, the transport is limited by the discontinuous morphological structure. Hence the challenge lies in how to modify the chemistry of the polymers to obtain significant protonic conductivity at low hydration levels. This may be possible if one can alter the chemical structure to synthesize nanophase separated ion containing block copolymers. Unlike the BPSH copolymers, where the sulfonic acid groups are randomly distributed along the chain, the multiblock copolymers will feature an ordered sequence of hydrophilic and hydrophobic segments. If, like in Nafion, connectivity is established between the hydrophilic domains in these multiblock copolymers, they will not need as much water, and hence will show much better protonic conductivity than the random copolymers (with similar degree of sulfonation, or IEC) at partially hydrated conditions. The goal of this research is to develop a material suitable for use as a polymer electrolyte membrane which by the year 2010 will meet all the performance requirements associated with fuel cell operation at high temperatures and low relative humidity, and will out-perform the present standard Nafion{reg_sign}. In particular, it is our objective to extend our previous research based on the use of thermally, oxidatively, and hydrolytically, ductile, high Tg ion containing polymers based on poly(arylene ethers) to the production of polymer electrolyte membranes which will meet all the performance requirements in addition to having an areal resistance of < 0.05 ohm-cm{sup 2} at a temperature of up to 120 C, relative humidity of 25 to 50%, and up to 2.5 atm total pressure. In many instances, our materials already out performs Nafion{reg_sign}, and it is expected that with some modification by either combining with conductive inorganic fillers and/or synthesizing as a block copolymer it will meet the performance criteria at high temperatures and low relative humidity. A key component in improving the performance of the membranes (and in particular proton conductivity) and meeting the cost requirements of $40/m{sup 2} is our development of a film casting process, which shows promise for generation of void free thin films of uniform thickness with controlled polymer alignment and configuration

Resistance to metal contamination by historically-stressed populations of Ceriodaphnia pulchella: Environmental influence versus genetic determination

Field populations of daphnids historically-stressed by metal contamination may show increased resistance to those contaminants. This study was undertaken aiming to confirm/infirm three main hypotheses: (1) field populations living in historically-impacted environments are more tolerant to metal stress than populations from reference sites; (2) resistance differences are genetically-determined, i.e., differences persist after controlling for environmental and maternal effects, by acclimating cloned lineages to similar conditions; and (3) resistance to stress in field populations living in historically-impacted environments is due to the disappearance of sensitive individuals rather than the appearance of highly resistant ones, i.e., the shift in the central tendency of resistance is linked to a decrease in the range of population resistance and not to an increased upper limit of the population resistance. Three populations of the cladoceran Ceriodaphnia pulchella Sars in Southern Portugal were sampled; one of which has been historically-stressed by acid mine drainage (AMD) from an abandoned cupric-pyrite mine and two from reference sites within the same watershed. To assess if resistance differences were genetically-determined, the three populations were acclimated for at least five generations under the same controlled conditions. Assays with AMD contaminated water samples were performed with both non-acclimated and acclimated individuals from all studied populations. Reproduction results in sub-lethal assays revealed significant differences between the reference and stressed populations. Significant differences in resistance to lethal levels of toxicity were observed for both non-acclimated and acclimated populations, individuals from population I being more resistant than those from reference populations. The existence of genetically-determined sensitivity differences was attested by the presence of significant differences in resistance to lethal levels of toxicity in acclimated individuals from reference and stressed populations. Results from cumulative mortality assays revealed that sensitive individuals were most probably present in the original population, but no conclusion could be draw about the presence of extreme resistant individuals in the historically-stressed population. Finally, it was shown that responses among populations converged from high to low levels of contamination.http://www.sciencedirect.com/science/article/B6V74-4G05M6B-5/1/1296fbdbc8b8e0e8820be6136216200

On the discovery of tetrapod trackways from Permo-Carboniferous redbeds of Prince Edward Island and their biostratigraphic significance

The first fossil tetrapod footprints that were discovered on Prince Edward Island, and which were previously undescribed, are small reptilian trackways assignable to the ichnogenera Notalacerta andGilmoreichnus. Their closest zoological correlatives are small, Permo-Carboniferous "stem-reptiles" of the families Protorothyrididae and Captorhinidae in the suborder Captorhinomorpha, and pelycosauran reptiles, possibly of the Ophiacodontidae. Reptiles of this type are rare to unrepresented in the skeletal fauna of the province. The biochronology of the track-bearing bed, combined with terrestrial vertebrate, palynological and macrofloral records, suggest that the host Pictou Group redbeds on Prince Edward Island young from late Stephanian (Pennsylvanian) at Malpeque Bay to early Permian in the north. The combined discoveries of tetrapod footprints and trackways from these Permo-Carboniferous redbeds suggests that the record is potentially extensive. Now included in this record is the youngest known occurrence of the ichno-genus Notalacerta. RÉSUMÉ Les premières empreintes de fossiles de tétrapodes découvertes sur l'Île-du-Prince-Édouard, et précédemment non décrites, sont des traces d'un petit reptile qu'on peut rattacher aux ichnogenres Notalacerta et Gilmoreichnus. Leurs parents géologiques les plus proches sont les petits " reptiles-tiges » permocarbonifères des familles des protorothyridides et des captorhinides du sous-ordre des captorhinomorphes, ainsi que les reptiles pélicosauriens, possiblement les ophiacodontides. Les reptiles de ce type sont rares sinon absents au sein de la faune squelettique de la province. La biochronologie des strates renfermant des traces conjuguée aux relevés de vertébrés terrestres et aux relevés palynologiques et macrofloraux laisse supposer que les couches rouges hôtes du groupe de Pictou, sur l'Île-du-Prince-Édouard, remontent à la période du Stéphanien tardif (Pennsylvanien), dans la baie Malpeque, au Permien précoce, dans le nord. Les découvertes combinées d'empreintes et de traces de tétrapodes des couches rouges permocarbonifères semblent indiquer que la quantité d'enregistrements pourrait être vaste. Ces enregistrements comprennent désormais la manifestation la plus récente connue de l'ichnogenre Notalacerta [Traduit par la rédaction.

The population biology of Crenobia alpina (Dana)

An investigation was carried out into the relationship between environment and reproduction in the freshwater triclad species. By studying two populations occupying adjacent habitats, under varying conditions of temperature, flow rate and resource availability, the effects of habitat variability on the di~ribution~ density, size structure and the levels of se>:ual and ase>:ual reproduction within each population were assessed. The population occupying a habitat which was characterised by its eurythermic temperature regime, high flow rates and complex macroinvertebrate community, occurred at low densities. Within this population, individuals were larger, on average, than in the adjacent population, and se>:ual reproduction occurred at high levels throughout the year, with asexual reproduction (by binary and multiple fission> also occurring throughout the yea~, but at lower levels. The seasonal nature of this habitat was reflected within the popUlation of , which exhibited spring peaks in density, followed by summer peaks in the level of sexual reproduction. In contrast, the adjacent population occupied a habitat which was characterised by its stenothermic temperature regime, low flow rates and a less comple> macroinvertebrate community, and occurred at much higher densities. Within this population, individuals were smaller, on average, than in the adjacent population, and sexual reproduction was virtually absent, wi th asexual reproduction (by binary. and multiple fission) occurring throughout the year at appreciable levels. The lack of seasonality within this habitat was similarly reflected in the lack of any seasonal fluctuations in density, or level of (in this case ase>:ual) reproduction within the population. The level of food availability varied seasonally in both habitats, however, and was generally similar, in terms of biomass, in bath areas. A hypothesis was presented which of triclads within each habitat related the density to the total food availability, measured as stream drift. It was suggested that at low population densities, the relatively higher levels of net resource availability per i ndi vi dual favoured the occurrence of sexual reproduction, in contrast with situations of high population density, where the relatively lower levels of net resource availability per individual inhibited the occurrence of sexual reproduction, thus favouring asexual reproduction. This hypothesis was supported by the results of laboratory investigations in other studies, together with the evidence gained from field observations from this study, particularly the observation that in the low dem::.i ty population, seasonal cycles in the level of sexual reproduction were out of phase with seasonal cycles of a similar nature in the level of popUlation denSity. Further evidence, from the results of .a field manipulation experiment, was presented which supported the hypothesis. In an area of high popUlation denSity, density was reduced artificially, resulting in a significant increase in the level of sexual reproduction within the population. population, It was concluded that in the high density intense intraspecific competition for food resulted in a low net level of food availability per individual, which in turn inhibited the process of sexualisation in triclads from that area. The results from these two populations of ~~~!e~~~, indicating that net food availability controls the occurrence of sexual reproduction in this species, are in marked contrast to the findings of previous studies, in which habitat temperature is implicated as the dominant environmental influence on this process

Inhibition of RNA polymerase II transcription in human cells by synthetic DNA-binding ligands

Sequence-specific DNA-binding small molecules that can permeate human cells potentially could regulate transcription of specific genes. Multiple cellular DNA-binding transcription factors are required by HIV type 1 for RNA synthesis. Two pyrrole-imidazole polyamides were designed to bind DNA sequences immediately adjacent to binding sites for the transcription factors Ets-l, lymphoid-enhancer binding factor 1, and TATA-box binding protein. These synthetic ligands specifically inhibit DNA-binding of each transcription factor and HIV type 1 transcription in cell-free assays. When used in combination, the polyamides inhibit virus replication by >99% in isolated human peripheral blood lymphocytes, with no detectable cell toxicity, The ability of small molecules to target predetermined DNA sequences located within RNA polymerase II promoters suggests a general approach for regulation of gene expression, as well as a mechanism for the inhibition of viral replication

Diaphus taaningi Norman, the principal component of a shallow sound-scattering layer in the Cariaco Trench, Venezuela

A myctophid fish, Diaphus taaningi Norman, is the principal component of a distinct daytime sound-scattering layer lying near 250 m, well above the anoxic, hydrogen-sulfide zone of the Cariaco Trench. The scattering layer produced strong sonar echoes at 12, 25, and 50 kHz; mean sound-scattering strength at layer depth at 25 kHz was approximately --73 dB and at 50 kHz was approximately --67 dB...

Environmental Barcoding: A Next-Generation Sequencing Approach for Biomonitoring Applications Using River Benthos

Timely and accurate biodiversity analysis poses an ongoing challenge for the success of biomonitoring programs. Morphology-based identification of bioindicator taxa is time consuming, and rarely supports species-level resolution especially for immature life stages. Much work has been done in the past decade to develop alternative approaches for biodiversity analysis using DNA sequence-based approaches such as molecular phylogenetics and DNA barcoding. On-going assembly of DNA barcode reference libraries will provide the basis for a DNA-based identification system. The use of recently introduced next-generation sequencing (NGS) approaches in biodiversity science has the potential to further extend the application of DNA information for routine biomonitoring applications to an unprecedented scale. Here we demonstrate the feasibility of using 454 massively parallel pyrosequencing for species-level analysis of freshwater benthic macroinvertebrate taxa commonly used for biomonitoring. We designed our experiments in order to directly compare morphology-based, Sanger sequencing DNA barcoding, and next-generation environmental barcoding approaches. Our results show the ability of 454 pyrosequencing of mini-barcodes to accurately identify all species with more than 1% abundance in the pooled mixture. Although the approach failed to identify 6 rare species in the mixture, the presence of sequences from 9 species that were not represented by individuals in the mixture provides evidence that DNA based analysis may yet provide a valuable approach in finding rare species in bulk environmental samples. We further demonstrate the application of the environmental barcoding approach by comparing benthic macroinvertebrates from an urban region to those obtained from a conservation area. Although considerable effort will be required to robustly optimize NGS tools to identify species from bulk environmental samples, our results indicate the potential of an environmental barcoding approach for biomonitoring programs

Evaluating Rigid and Semiflexible Fiber Orientation Evolution Models in Simple Flows

As American vehicle fuel efficiency requirements have become more stringent due to the CAFE standards, the auto industry has turned to fiber reinforced polymer composites as replacements for metal parts to reduce weight while simultaneously maintaining established safety standards. Furthermore, these composites may be easily processed using established techniques such as injection molding and compression molding. The mechanical properties of these composites are dependent on, among other variables, the orientation of the fibers within the part. Several models have been proposed to correlate fiber orientation with the kinematics of the polymer matrix during processing, each using various strategies to account for fiber interactions and fiber flexing. However, these all require the use of empirical fitting parameters. Previous work has obtained these parameters by fitting to orientation data at a specific location in an injection-molded part. This ties the parameters to the specific mold design used. Obtaining empirical parameters is not a trivial undertaking and adds significant time to the entire mold design process. Considering that new parameters must be obtained any time some aspect of the part or mold is changed, an alternative technique that obtains model parameters independent of the mold design could be advantageous. This paper continues work looking to obtain empirical parameters from rheological tests. During processing, the fiber-polymer suspension is subjected to a complex flow with both shear and extensional behavior. Rather than use a complex flow, this study seeks to isolate and compare the effects of shear and extension on two orientation models. To this end, simple shear and planar extension are employed, and the evolution of orientation from a planar random initial condition is tracked as a function of strain. Simple shear was imparted using a sliding plate rheometer designed and fabricated in-house. A novel rheometer tool was developed and fabricated in-house to impart planar extension using a lubricated squeeze flow technique, where a lowviscosity Newtonian lubricant is applied to the solid boundaries to minimize the effect of shearing due to the no-slip boundary condition. The Folgar-Tucker model with a strain reduction factor is used as a rigid fiber model and compared against a bead-rod model (a semiflexible model) proposed by Ortman. Both models are capable of predicting the data, with the bead-rod model performing slightly better. Orientation occurs at a much faster rate under startup of planar extension and also attains a much higher degree of flow alignment when compared with startup of steady shear