Showing 71 - 80 of 733 Items
To what extent may peptide receptor gene diversity/complement contribute to functional flexibility in a simple pattern-generating neural network?
Date: 2019-06-01
Creator: Patsy S. Dickinson, J. Joe Hull, Alexandra Miller, Emily R. Oleisky, Andrew E., Christie
Access: Open access
- Peptides are known to contribute to central pattern generator (CPG) flexibility throughout the animal kingdom. However, the role played by receptor diversity/complement in determining this functional flexibility is not clear. The stomatogastric ganglion (STG) of the crab, Cancer borealis, contains CPGs that are models for investigating peptidergic control of rhythmic behavior. Although many Cancer peptides have been identified, their peptide receptors are largely unknown. Thus, the extent to which receptor diversity/complement contributes to modulatory flexibility in this system remains unresolved. Here, a Cancer mixed nervous system transcriptome was used to determine the peptide receptor complement for the crab nervous system as a whole. Receptors for 27 peptide families, including multiple receptors for some groups, were identified. To increase confidence in the predicted sequences, receptors for allatostatin-A, allatostatin-B, and allatostatin-C were cloned, sequenced, and expressed in an insect cell line; as expected, all three receptors trafficked to the cell membrane. RT-PCR was used to determine whether each receptor was expressed in the Cancer STG. Transcripts for 36 of the 46 identified receptors were amplified; these included at least one for each peptide family except RYamide. Finally, two peptides untested on the crab STG were assessed for their influence on its motor outputs. Myosuppressin, for which STG receptors were identified, exhibited clear modulatory effects on the motor patterns of the ganglion, while a native RYamide, for which no STG receptors were found, elicited no consistent modulatory effects. These data support receptor diversity/complement as a major contributor to the functional flexibility of CPGs.
Measurement of the τ-lepton mass
Date: 1993-01-01
Creator: R. Balest, M. Daoudi, W. T. Ford, D. R. Johnson, K., Lingel, M. Lohner, P. Rankin, J. G. Smith, J. P. Alexander, C. Bebek, K. Berkelman, D. Besson, T. E. Browder, D. G. Cassel, H. A. Cho, D. M. Coffman, P. S. Drell, R. Ehrlich, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, K. Honscheid, C. D. Jones, J. Kandaswamy, N. Katayama, P. C. Kim, D. L. Kreinick
Access: Open access
- Using data from the CLEO II detector at CESR, we measure the τ-lepton mass by exploiting the unique kinematics of events in which both τ's decay hadronically. The result is mτ=1777.8±0.7±1.7 MeV/c2. By comparing our result with other measurements near τ-pair threshold, we extract an upper limit on the τ-neutrino mass of 75 MeV/c2 at 95% confidence level. © 1993 The American Physical Society.
The Future of Social Movement Organizations: The Waning Dominance of SMOs Online
Date: 2013-04-12
Creator: Jennifer Earl
Access: Open access
- For scholars interested in the role of information communication technologies (ICTs) in protest and social movements, the importance of organizations doesn’t appear to be as axiomatic. Work over the past decade researching “Internet activism” has raised fundamental questions about SMOs and their continuing importance to protest: Do organizations play the same role in online protest as they have played in offline protest? Are SMOs as necessary for online movements and protest organizing? What role or functions do SMOs play in online protest? In this article, I address these questions by first surveying social movement research on pre-Internet protest to establish how traditional social movement scholarship understands the role and impact of SMOs. I then compare these expectations to existing work on online protest. In the end, I argue that there are a variety of factors that contribute to the declining necessity of SMOs. Nonetheless, I point to some advantages that SMOs still seem to offer over other forms of organizing. Finally, I discuss the differences between a movement ecology devoid of SMOs versus one that has some level of SMO presence as well as reasons why SMOs might persist, separate and apart from the advantages the organizational form imparts.
Under the hood of satellite empirical chlorophyll a algorithms: Revealing the dependencies of maximum band ratio algorithms on inherent optical properties
Date: 2012-09-10
Creator: Michael J. Sauer, C. S. Roesler, P. J. Werdell, A. Barnard
Access: Open access
- Empirically-based satellite estimates of chlorophyll a [Chl] (e.g. OC3) are an important indicator of phytoplankton biomass. To correctly interpret [Chl] variability, estimates must be accurate and sources of algorithm errors known. While the underlying assumptions of band ratio algorithms such as OC3 have been tacitly hypothesized (i.e. CDOM and phytoplankton absorption covary), the influence of component absorption and scattering on the shape of the algorithm and estimated [Chl] error has yet to be explicitly revealed. We utilized the NOMAD bio-optical data set to examine variations between satellite estimated [Chl] and in situ values. We partitioned the variability into (a) signal contamination and (b) natural phytoplankton variability (variability in chlorophyll-specific phytoplankton absorption). Not surprisingly, the OC3 best-fit curve resulted from a balance between these two different sources of variation confirming the bias by detrital absorption on global scale. Unlike previous descriptions of empirical [Chl] algorithms, our study (a) quantified the mean detrital:phytoplankton absorption as ~1:1in the global NOMAD data set, and (b) removed detrital (CDOM + non-algal particle) absorption in radiative transfer models directly showing that the scale of the remaining variability in the band ratio algorithm was dominated by phytoplankton absorption cross section. © 2012 Optical Society of America.
Waterfowl habitat change over five decades in a freshwater tidal ecosystem in mid-coast maine
Date: 2011-01-01
Creator: J. Lichter, M.E.H. Burton, S.L. Close, J.M. Grinvalsky, J., Reblin
Access: Open access
Climate change's impact on key ecosystem services and the human well-being they support in the US
Date: 2013-11-01
Creator: Erik J. Nelson, Peter Kareiva, Mary Ruckelshaus, Katie Arkema, Gary, Geller, Evan Girvetz, Dave Goodrich, Virginia Matzek, Malin Pinsky
Access: Open access
- Climate change alters the functions of ecological systems. As a result, the provision of ecosystem services and the well-being of people that rely on these services are being modified. Climate models portend continued warming and more frequent extreme weather events across the US. Such weather-related disturbances will place a premium on the ecosystem services that people rely on. We discuss some of the observed and anticipated impacts of climate change on ecosystem service provision and livelihoods in the US. We also highlight promising adaptive measures. The challenge will be choosing which adaptive strategies to implement, given limited resources and time. We suggest using dynamic balance sheets or accounts of natural capital and natural assets to prioritize and evaluate national and regional adaptation strategies that involve ecosystem services. © The Ecological Society of America.
Understanding the effect of political advertising on voter turnout: A response to Krasno and Green
Date: 2008-01-01
Creator: Michael M. Franz, Paul Freedman, Ken Goldstein, Travis N. Ridout
Access: Open access
- Krasno and Green have argued that political advertising has no impact on voter turnout. We remain unconvinced by their evidence, given concerns about how they measure the advertising environment, how they measure advertising tone, their choice of modeling techniques and the generalizability of their findings. These differences aside, we strongly agree that political advertising does little to undermine voter participation. © 2008 Southern Political Science Association.
Tempered, invariant, positive-definite distributions on SU(1, 1)/{± 1}
Date: 1984-01-01
Creator: William H. Barker
Access: Open access
The 'obligate diploid' Candida albicans forms mating-competent haploids
Date: 2013-02-07
Creator: Meleah A. Hickman, Guisheng Zeng, Anja Forche, Matthew P. Hirakawa, Darren, Abbey, Benjamin D. Harrison, Yan Ming Wang, Ching Hua Su, Richard J. Bennett, Yue Wang, Judith Berman
Access: Open access
- Candida albicans, the most prevalent human fungal pathogen, is considered to be an obligate diploid that carries recessive lethal mutations throughout the genome. Here we demonstrate that C. albicans has a viable haploid state that can be derived from diploid cells under in vitro and in vivo conditions, and that seems to arise through a concerted chromosome loss mechanism. Haploids undergo morphogenetic changes like those of diploids, including the yeast-hyphal transition, chlamydospore formation and a white-opaque switch that facilitates mating. Haploid opaque cells of opposite mating type mate efficiently to regenerate the diploid form, restoring heterozygosity and fitness. Homozygous diploids arise spontaneously by auto-diploidization, and both haploids and auto-diploids show a similar reduction in fitness, in vitro and in vivo, relative to heterozygous diploids, indicating that homozygous cell types are transient in mixed populations. Finally, we constructed stable haploid strains with multiple auxotrophies that will facilitate molecular and genetic analyses of this important pathogen. © 2013 Macmillan Publishers Limited. All rights reserved.
More pendants for Polya: Two loops in the SU(2) sector
Date: 2005-07-01
Creator: Marta Gómez-Reino, Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- We extend the methods of Spradlin and Volovich to compute the partition function for a conformally-invariant gauge theory on ℝ × S 3 in which the dilatation operator is represented by a spin-chain hamiltonian acting on pairs of states, not necessarily nearest neighbors. A specific application of this is the two-loop dilatation operator of the planar SU(2) subsector of the N ≤ 4 SU(N) super Yang-Mills theory in the large-N limit. We compute the partition function and Hagedorn temperature for this sector to second order in the gauge coupling. The Hagedorn temperature is to be interpreted as giving the exponentially-rising portion of the density of states of the SU(2) sector, which may be a signal of stringy behavior in the dual theory. © SISSA 2005.