Date: 1983-01-01

Creator: B. D. Kohorn, P. M.M. Rae

Access: Open access

Date: 2003-01-01

Creator: Mary Lou Zeeman, W. Weckesser, D. Gokhman

Access: Open access

In vertebrates, ovulation is triggered by a surge of LH from the pituitary. The precise mechanism by which rising oestradiol concentrations initiate the LH surge in the human menstrual cycle remains a fundamental open question of reproductive biology. It is well known that sampling of serum LH on a time scale of minutes reveals pulsatile release from the pituitary in response to pulses of gonadotrophin releasing hormone from the hypothalamus. The LH pulse frequency and amplitude vary considerably over the cycle, with the highest frequency and amplitude at the midcycle surge. Here a new mathematical model is presented of the pituitary as a damped oscillator (pulse generator) driven by the hypothalamus. The model LH surge is consistent with LH data on the time scales of both minutes and days. The model is used to explain the surprising pulse frequency characteristics required to treat human infertility disorders such as Kallmann's syndrome, and new experimental predictions are made.

Date: 1996-01-01

Creator: Francisco Montes De Oca, Mary Lou Zeeman

Access: Open access

It is well known that for the two species autonomous competitive Lotka-Volterra model with no fixed point in the open positive quadrant, one of the species is driven to extinction, whilst the other population stabilises at its own carrying capacity. In this paper we prove a generalisation of this result to nonautonomous systems of arbitrary finite dimension. That is, for the n species nonautonomous competitive Lotka-Volterra model, we exhibit simple algebraic criteria on the parameters which guarantee that all but one of the species is driven to extinction. The restriction of the system to the remaining axis is a nonautonomous logistic equation, which has a unique solution u(t) that is strictly positive and bounded for all time; see Coleman (Math. Biosci. 45 (1979), 159-173) and Ahmad (Proc. Amer. Math. Soc. 117 (1993), 199-205). We prove in addition that all solutions of the n-dimensional system with strictly positive initial conditions are asymptotic to u(t). © 1996 American Mathematical Society.

Date: 2006-01-24

Creator: Aimee M. Eldridge, Wayne A. Halsey, Deborah S. Wuttke

Access: Open access

The single-strand overhang present at telomeres plays a critical role in mediating both the capping and telomerase regulation functions of telomeres. The telomere end-binding proteins, Cdc13 in Saccharomyces cerevisiae, Pot1 in higher eukaryotes, and TEBP in the ciliated protozoan Oxytricha nova, exhibit sequence-specific binding to their respective single-strand overhangs. S. cerevisiae telomeres are composed of a heterogeneous mixture of GT-rich telomeric sequence, unlike in higher eukaryotes which have a simple repeat that is maintained with high fidelity. In yeast, the telomeric overhang is recognized by the essential protein Cdc13, which coordinates end-capping and telomerase activities at the telomere. The Cdc13 DNA-binding domain (Cdc13-DBD) binds these telomere sequences with high affinity (3 pM) and sequence specificity. To better understand the basis for this remarkable recognition, we have investigated the binding of the Cdc13-DBD to a series of altered DNA substrates. Although an 11-mer of GT-rich sequence is required for full binding affinity, only three of these 11 bases are recognized with high specificity. This specificity differs from that observed in the other known telomere end-binding proteins, but is well suited to the specific role of Cdc13 at yeast telomeres. These studies expand our understanding of telomere recognition by the Cdc13-DBD and of the unique molecular recognition properties of ssDNA binding. © 2006 American Chemical Society.

Date: 2007-09-01

Creator: Benjamin R. Williams, Jack R. Bateman, Natasha D. Novikov, C. Ting Wu

Access: Open access

Homolog pairing refers to the alignment and physical apposition of homologous chromosomal segments. Although commonly observed during meiosis, homolog pairing also occurs in nonmeiotic cells of several organisms, including humans and Drosophila. The mechanism underlying nonmeiotic pairing, however, remains largely unknown. Here, we explore the use of established Drosophila cell lines for the analysis of pairing in somatic cells. Using fluorescent in situ hybridization (FISH), we assayed pairing at nine regions scattered throughout the genome of Kc167 cells, observing high levels of homolog pairing at all six euchromatic regions assayed and variably lower levels in regions in or near centromeric heterochromatin. We have also observed extensive pairing in six additional cell lines representing different tissues of origin, different ploidies, and two different species, demonstrating homolog pairing in cell culture to be impervious to cell type or culture history. Furthermore, by sorting Kc167 cells into G1, S, and G2 subpopulations, we show that even progression through these stages of the cell cycle does not significantly change pairing levels. Finally, our data indicate that disrupting Drosophila topoisomerase II (Top2) gene function with RNAi and chemical inhibitors perturbs homolog pairing, suggesting Top2 to be a gene important for pairing. Copyright © 2007 by the Genetics Society of America.

Date: 2008-01-01

Creator: Melanie Legrand, Anja Forche, Anna Selmecki, Christine Chan, David T., Kirkpatrick, Judith Berman

Access: Open access

Haplotype maps (HapMaps) reveal underlying sequence variation and facilitate the study of recombination and genetic diversity. In general, HapMaps are produced by analysis of Single-Nucleotide Polymorphism (SNP) segregation in large numbers of meiotic progeny. Candida albicans, the most common human fungal pathogen, is an obligate diploid that does not appear to undergo meiosis. Thus, standard methods for haplotype mapping cannot be used. We exploited naturally occurring aneuploid strains to determine the haplotypes of the eight chromosome pairs in the C. albicans laboratory strain SC5314 and in a clinical isolate. Comparison of the maps revealed that the clinical strain had undergone a significant amount of genome rearrangement, consisting primarily of crossover or gene conversion recombination events. SNP map haplotyping revealed that insertion and activation of the UAU1 cassette in essential and non-essential genes can result in whole chromosome aneuploidy. UAU1 is often used to construct homozygous deletions of targeted genes in C. albicans; the exact mechanism (trisomy followed by chromosome loss versus gene conversion) has not been determined. UAU1 insertion into the essential ORC1 gene resulted in a large proportion of trisomic strains, while gene conversion events predominated when UAU1 was inserted into the non-essential LRO1 gene. Therefore, induced aneuploidies can be used to generate HapMaps, which are essential for analyzing genome alterations and mitotic recombination events in this clonal organism. © 2008 Legrand et al.

Date: 2021-03-01

Creator: Travis N. Ridout, Erika Franklin Fowler, Michael M. Franz

Access: Open access

This article is a "first look"at political advertising in 2020. Spending on political advertising in the United States in 2020 obliterated records, and Democrats held huge advantages in the presidential race and in most congressional and senatorial races. In addition, all indicators suggest that spending on digital advertising continued to rise. Political advertising was largely similar in tone to past years and, in the presidential race, was substantially more positive than 2016. In addition, interest groups remained heavily involved in federal races in 2020, airing more ads than ever before, though their spending as a percentage of total ad spending was slightly less than in 2016. Political ad spending in 2020 may have been historically high because of the impact of COVID-19 on how campaigns could reach voters, suggesting that paid advertising may decline in 2022 and 2024, at least as a percentage of total election spending.

Date: 2016-01-01

Creator: Maria A. Gartstein, Samuel P. Putnam, Rachel Kliewer

Access: Open access

Examined relationships between temperament, measured via parent report at 4 months and structured laboratory observations at 12 months of age, and a school readiness battery administered at about 4 years of age (N =31). Scores on the School Readiness Assessment of the Bracken Basic Concept Scale (BBCS) were related to infant Positive Affectivity/Surgency (PAS), with infants described as demonstrating higher levels of PAS at 4 months of age later demonstrating greater school readiness in the domains of color, letter, and number skills. Regulatory Capacity/Orienting (RCO) at 4 months also predicted color skills, with more regulated infants demonstrating superior pre-academic functioning in this area. Analyses involving laboratory observations of temperament provided additional information concerning the importance of infant Positive Affectivity/Surgency, predictive of letter skills and overall school-readiness scores later in childhood. Results are discussed in the context of implications for theory and research, as well as early education settings.

Date: 2008-02-01

Creator: Kenneth A. Norman, Katharine Tepe, Erika Nyhus, Tim Curran

Access: Open access

The question of interference (how new learning affects previously acquired knowledge and vice versa) is a central theoretical issue in episodic memory research, but very few human neuroimaging studies have addressed this question. Here, we used event-related potentials (ERPs) to test the predictions of the complementary learning systems (CLS) model regarding how list strength manipulations (strengthening some, but not all, items on a study list) affect recognition memory. Our analysis focused on the FN400 old-new effect, a hypothesized ERP correlate of familiarity-based recognition, and the parietal old-new effect, a hypothesized ERP correlate of recollection-based recognition. As is predicted by the CLS model, increasing list strength selectively reduced the ERP correlate of recollection-based discrimination, leaving the ERP correlate of familiarity-based discrimination intact. In a second experiment, we obtained converging evidence for the CLS model's predictions, using a remember/know test: Increasing list strength reduced recollection-based discrimination but did not reduce familiarity-based discrimination. Copyright 2008 Psychonomic Society, Inc.

Date: 2004-02-15

Creator: Thomas Pietraho

Access: Open access

Consider a complex classical semisimple Lie group along with the set of its nilpotent coadjoint orbits. When the group is of type A, the set of orbital varieties contained in a given nilpotent orbit is described a set of standard Young tableaux. We parameterize both, the orbital varieties and the irreducible components of unipotent varieties in the other classical groups by sets of standard domino tableaux. The main tools are Spaltenstein's results on signed domino tableaux together with Garfinkle's operations on standard domino tableaux. © 2004 Elsevier Inc. All rights reserved.

Date: 2020-10-01

Creator: Emily R. Oleisky, Meredith E. Stanhope, J. Joe Hull, Andrew E. Christie, Patsy S., Dickinson

Access: Open access

The American lobster, Homarus americanus, cardiac neuromuscular system is controlled by the cardiac ganglion (CG), a central pattern generator consisting of four premotor and five motor neurons. Here, we show that the premotor and motor neurons can establish independent bursting patterns when decoupled by a physical ligature. We also show that mRNA encoding myosuppressin, a cardioactive neuropeptide, is produced within the CG. We thus asked whether myosuppressin modulates the decoupled premotor and motor neurons, and if so, how this modulation might underlie the role(s) that these neurons play in myosuppressin's effects on ganglionic output. Although myosuppressin exerted dose-dependent effects on burst frequency and duration in both premotor and motor neurons in the intact CG, its effects on the ligatured ganglion were more complex, with different effects and thresholds on the two types of neurons. These data suggest that the motor neurons are more important in determining the changes in frequency of the CG elicited by low concentrations of myosuppressin, whereas the premotor neurons have a greater impact on changes elicited in burst duration. A single putative myosuppressin receptor (MSR-I) was previously described from the Homarus nervous system. We identified four additional putative MSRs (MSR-II-V) and investigated their individual distributions in the CG premotor and motor neurons using RT-PCR. Transcripts for only three receptors (MSR-II-IV) were amplified from the CG. Potential differential distributions of the receptors were observed between the premotor and motor neurons; these differences may contribute to the distinct physiological responses of the two neuron types to myosuppressin. NEW & NOTEWORTHY Premotor and motor neurons of the Homarus americanus cardiac ganglion (CG) are normally electrically and chemically coupled, and generate rhythmic bursting that drives cardiac contractions; we show that they can establish independent bursting patterns when physically decoupled by a ligature. The neuropeptide myosuppressin modulates different aspects of the bursting pattern in these neuron types to determine the overall modulation of the intact CG. Differential distribution of myosuppressin receptors may underlie the observed responses to myosuppressin.

Date: 2013-10-22

Creator: Kristin M.K. Halbert, Erica Goetze, David B. Carlon

Access: Open access

Although holoplankton are ocean drifters and exhibit high dispersal potential, a number of studies on single species are finding highly divergent genetic clades. These cryptic species complexes are important to discover and describe, as identification of common marine species is fundamental to understanding ecosystem dynamics. Here we investigate the global diversity within Pleuromamma piseki and P. gracilis, two dominant members of the migratory zooplankton assemblage in subtropical and tropical waters worldwide. Using DNA sequence data from the mitochondrial gene cytochrome c oxidase subunit II (mtCOII) from 522 specimens collected across the Pacific, Atlantic and Indian Oceans, we discover twelve well-resolved genetically distinct clades in this species complex (Bayesian posterior probabilities >0.7; 6.3-17% genetic divergence between clades). The morphologically described species P. piseki and P. gracilis did not form monophyletic groups, rather they were distributed throughout the phylogeny and sometimes co-occurred within well-resolved clades: this result suggests that morphological characters currently used for taxonomic identification of P. gracilis and P. piseki may be inaccurate as indicators of species' boundaries. Cryptic clades within the species complex ranged from being common to rare, and from cosmopolitan to highly restricted in distribution across the global ocean. These novel lineages appear to be ecologically divergent, with distinct biogeographic distributions across varied pelagic habitats. We hypothesize that these mtDNA lineages are distinct species and suggest that resolving their systematic status is important, given the ecological significance of the genus Pleuromamma in subtropical-tropical waters worldwide. © 2013 Halbert et al.

Date: 2009-02-01

Creator: Patsy S. Dickinson, Elizabeth A. Stemmler, Elizabeth E. Barton, Christopher R. Cashman, Noah P., Gardner, Szymon Rus, Henry R. Brennan, Timothy S. McClintock, Andrew E. Christie

Access: Open access

Recently, cDNAs encoding prepro-orcokinins were cloned from the crayfish Procambarus clarkii; these cDNAs encode multiple copies of four orcokinin isoforms as well as several other peptides. Using the translated open reading frames of the P. clarkii transcripts as queries, five ESTs encoding American lobster Homarus americanus orthologs were identified via BLAST analysis. From these clones, three cDNAs, each encoding one of two distinct prepro-hormones, were characterized. Predicted processing of the deduced prepro-hormones would generate 13 peptides, 12 of which are conserved between the 2 precursors: the orcokinins NFDEIDRSGFGFN (3 copies), NFDEIDRSGFGFH (2 copies) and NFDEIDRSGFGFV (2 copies), FDAFTTGFGHN (an orcomyotropin-related peptide), SSEDMDRLGFGFN, GDY(SO3)DVYPE, VYGPRDIANLY and SAE. Additionally, one of two longer peptides (GPIKVRFLSAIFIPIAAPARSSPQQDAAAGYTDGAPV or APARSSPQQDAAAGYTDGAPV) is predicted from each prepro-hormone. MALDI-FTMS analyses confirmed the presence of all predicted orcokinins, the orcomyotropin-related peptide, and three precursor-related peptides, SSEDMDRLGFGFN, GDYDVYPE (unsulfated) and VYGPRDIANLY, in H. americanus neural tissues. SAE and the longer, unshared peptides were not detected. Similar complements of peptides are predicted from P. clarkii transcripts; the majority of these were detected in its neural tissues with mass spectrometry. Truncated orcokinins not predicted from any precursor were also detected in both species. Consistent with previous studies in the crayfish Orconectes limosus, NFDEIDRSGFGFN increased mid-/hindgut motility in P. clarkii. Surprisingly, the same peptide, although native to H. americanus, did not affect gut motility in this species. Together, our results provide the framework for future investigations of the regulation and physiological function of orcokinins/orcokinin precursor-related peptides in astacideans. © 2008 Elsevier Inc. All rights reserved.

Date: 2007-02-01

Creator: Andrew E. Christie, Kimberly K. Kutz-Naber, Elizabeth A. Stemmler, Alexandra Klein, Daniel I., Messinger, Christopher C. Goiney, Anna J. Conterato, Emily A. Bruns, Yun Wei A. Hsu, Lingjun Li, Patsy S. Dickinson

Access: Open access

Over a quarter of a century ago, Mykles described the presence of putative endocrine cells in the midgut epithelium of the crab Cancer magister (Mykles, 1979). In the years that have followed, these cells have been largely ignored and nothing is known about their hormone content or the functions they play in this species. Here, we used a combination of immunohistochemistry and mass spectrometric techniques to investigate these questions. Using immunohistochemistry, we identified both SIFamide-and tachykinin-related peptide (TRP)-like immunopositive cells in the midgut epithelium of C. magister, as well as in that of Cancer borealis and Cancer productus. In each species, the SIFamide-like labeling was restricted to the anterior portion of the midgut, including the paired anterior midgut caeca, whereas the TRP-like immunoreactivity predominated in the posterior midgut and the posterior midgut caecum. Regardless of location, label or species, the morphology of the immunopositive cells matched that of the putative endocrine cells characterized ultrastructurally by Mykles (Mykles, 1979). Matrix-assisted laser desorption/ ionization-Fourier transform mass spectrometry identified the peptides responsible for the immunoreactivities as GYRKPPFNGSIFamide (Gly 1-SIFamide) and APSGFLGMRamide [Cancer boreatis tachykinin-related peptide Ia (CabTRP Ia)], respectively, both of which are known neuropeptides of Cancer species. Although the function of these midgut-derived peptides remains unknown, we found that both Gly1-SIFamide and CabTRP Ia were released when the midgut was exposed to high-potassium saline. In addition, CabTRP Ia was detectable in the hemolymph of crabs that had been held without food for several days, but not in that of fed animals, paralleling results that were attributed to TRP release from midgut endocrine cells in insects. Thus, one function that midgut-derived CabTRP Ia may play in Cancer species is paracrine/hormonal control of feeding-related behavior, as has been postulated for TRPs released from homologous cells in insects.

Date: 1997-01-01

Creator: Patsy S. Dickinson, Wesley P. Fairfield, John R. Hetling, Jane Hauptman

Access: Open access

Two of the peptides found in the stomatogastric nervous system of the spiny lobster. Panulirus interruptus, interacted to modulate the activity of the cardiac sac motor pattern. In the isolated stomatogastric ganglion, red- pigment-concentrating hormone (RPCH), but not proctolin, activated the bursting activity in the inferior ventricular (IV) neurons that drives the cardiac sac pattern. The cardiac sac pattern normally ceased within 15 min after the end of RPCH superfusion. However, when proctolin was applied within a few minutes of that time, it was likewise able to induce cardiac sac activity. Similarly, proctolin applied together with subthreshold RPCH induced cardiac sac bursting. The amplitude of the excitatory postsynaptic potentials from the IV neurons to the cardiac sac dilator neuron CD2 (1 of the 2 major motor neurons in the cardiac sac system) was potentiated in the presence of both proctolin and RPCH. The potentiation in RPCH was much greater than in proctolin alone. However, the potentiation in proctolin after RPCH was equivalent to that recorded in RPCH alone. Although we do not yet understand the mechanisms for these interactions of the two modulators, this study provides an example of one factor that can determine the 'state' of the system that is critical in determining the effect of a modulator that is 'state dependent,' and it provides evidence for yet another level of flexibility in the motor output of this system.

Date: 2014-09-01

Creator: Vladimir Douhovnikoff, Eric L.G. Hazelton

Access: Open access

Premise of the study: The characteristics of clonal growth that are advantageous in invasive plants can also result in native plants’ ability to resist invasion. In Maine, we compared the clonal architecture and diversity of an invasive lineage (introduced Phragmites) and a noninvasive lineage (native Phragmites) present in much of North America. This study is the fi rst on standscale diversity using a sample size and systematic spatial-sampling scheme adequate for characterizing clonal structure in Phragmites. Our questions included: (1) Does the structure and extent of clonal growth suggest that the potential for clonal growth contributes to the invasiveness of the introduced lineage? (2) Is clonal growth common in the native lineage, acting as a possible source of ecological resistance and resilience?

Date: 1994-01-01

Creator: C. L. Borders, John A. Broadwater, Paula A. Bekeny, Johanna E. Salmon, Ann S., Lee, Aimee M. Eldridge, Virginia B. Pett

Access: Open access

We propose that arginine side chains often play a previously unappreciated general structural role in the maintenance of tertiary structure in proteins, wherein the positively charged guanidinium group forms multiple hydrogen bonds to backbone carbonyl oxygens. Using as a criterion for a “structural” arginine one that forms 4 or more hydrogen bonds to 3 or more backbone carbonyl oxygens, we have used molecular graphics to locate arginines of interest in 4 proteins: Arg 180 in Thermus thermophilus manganese superoxide dismutase, Arg 254 in human carbonic anhydrase II, Arg 31 in Streptomyces rubiginosus xylose isomerase, and Arg 313 in Rhodospirillum rubrum ribulose‐1,5‐bisphosphate carboxylase/oxygenase. Arg 180 helps to mold the active site channel of superoxide dismutase, whereas in each of the other enzymes the structural arginine is buried in the “mantle” (i.e., inside, but near the surface) of the protein interior well removed from the active site, where it makes 5 hydrogen bonds to 4 backbone carbonyl oxygens. Using a more relaxed criterion of 3 or more hydrogen bonds to 2 or more backbone carbonyl oxygens, arginines that play a potentially important structural role were found in yeast enolase, Bacillus stearothermophilus glyceraldehyde‐3‐phosphate dehydrogenase, bacteriophage T4 and human lysozymes, Enteromorpha prolifera plastocyanin, HIV‐1 protease, Trypanosoma brucei brucei and yeast triosephosphate isomerases, and Escherichia coli trp aporepressor (but not trp repressor or the trp repressor/operator complex). In addition to helping form the active site funnel in superoxide dismutase, the structural arginines found in this study play such diverse roles as stapling together 3 strands of backbone from different regions of the primary sequence, and tying α‐helix to α‐helix, βturn to β‐turn, and subunit to subunit. Copyright © 1994 The Protein Society

Date: 2010-11-01

Creator: Vladimir Douhovnikoff, Gregory R. Goldsmith, Ken D. Tape, Cherrie Huang, Nadine, Sur, M. Syndonia Bret-Harte

Access: Open access

Rapid climate change in arctic environments is leading to a widespread expansion in woody deciduous shrub populations. However, little is known about the reproductive, dispersal, and establishment mechanisms associated with shrub expansion. It is assumed that harsh environmental conditions impose limitations on plant sexual reproduction in the Arctic, such that population survival and expansion is predominately a function of clonal recruitment. We present contrary evidence from microsatellite genetic data suggesting the prevalence of recruitment by seed. Further, we present a conceptual model describing modes of recruitment in relation to the abiotic environment. Climate change may be alleviating abiotic stress so that resources are available for more frequent recruitment by seed. Such changes have widespread implications for ecosystem structure and functioning, including species composition, wildlife habitat, biogeochemical cycling, and surface energy balance. © 2010 Regents of the University of Colorado.

Date: 2007-01-01

Creator: Nadia V. Celis Salgado, Magali García Ramis

Access: Open access

Date: 2013-09-01

Creator: Kanokwan Champasa, Scott A. Longwell, Aimee M. Eldridge, Elizabeth A. Stemmler, Danielle H., Dube

Access: Open access

Virulence of the gastric pathogen Helicobacter pylori (Hp) is directly linked to the pathogen's ability to glycosylate proteins; for example, Hp flagellin proteins are heavily glycosylated with the unusual nine-carbon sugar pseudaminic acid, and this modification is absolutely essential for Hp to synthesize functional flagella and colonize the host's stomach. Although Hp's glycans are linked to pathogenesis, Hp's glycome remains poorly understood; only the two flagellin glycoproteins have been firmly characterized in Hp. Evidence from our laboratory suggests that Hp synthesizes a large number of as-yet unidentified glycoproteins. Here we set out to discover Hp's glycoproteins by coupling glycan metabolic labeling with mass spectrometry analysis. An assessment of the subcellular distribution of azide-labeled proteins by Western blot analysis indicated that glycoproteins are present throughout Hp and may therefore serve diverse functions. To identify these species, Hp's azide-labeled glycoproteins were tagged via Staudinger ligation, enriched by tandem affinity chromatography, and analyzed by multidimensional protein identification technology. Direct comparison of enriched azide-labeled glycoproteins with a mock-enriched control by both SDS-PAGE and mass spectrometry-based analyses confirmed the selective enrichment of azide-labeled glycoproteins. We identified 125 candidate glycoproteins with diverse biological functions, including those linked with pathogenesis. Mass spectrometry analyses of enriched azide-labeled glycoproteins before and after cleavage of O-linked glycans revealed the presence of Staudinger ligation-glycan adducts in samples only after beta-elimination, confirming the synthesis of O-linked glycoproteins in Hp. Finally, the secreted colonization factors urease alpha and urease beta were biochemically validated as glycosylated proteins via Western blot analysis as well as by mass spectrometry analysis of cleaved glycan products. These data set the stage for the development of glycosylation-based therapeutic strategies, such as new vaccines based on natively glycosylated Hp proteins, to eradicate Hp infection. Broadly, this report validates metabolic labeling as an effective and efficient approach for the identification of bacterial glycoproteins. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.

Date: 2000-01-01

Creator: Nalini M. Nadkarni, Nathaniel T. Wheelwright

Access: Open access

The Monteverde Cloud Forest Reserve has captured the worldwide attention of biologists, conservationists, and ecologists and has been the setting for extensive investigation over the past 40 years. Roughly 40,000 ecotourists visit the Cloud Forest each year, and it is often considered the archetypal high-altitude rain forest. Featuring synthetic chapters and specific accounts written by more than 100 biologists and local residents, the 573-page book documents in a single volume everything known about the biological diversity of Monteverde, Costa Rica, and how to protect it. New short chapters which update and expand the research presented in the 2000 Oxford publication were written in 2014 and are now available.

Date: 2020-01-22

Creator: Madeleine E. Msall, Paulo V. Santos

Access: Open access

Focusing microcavities for surface acoustic waves (SAWs) produce highly localized strain and piezoelectric fields that can dynamically control excitations in nanostructures. Focusing transducers (FIDTs) that generate SAW beams that match nanostructure dimensions require pattern correction due to diffraction and wave-velocity anisotropy. The anisotropy correction is normally implemented by adding a quadratic term to the dependence of the wave velocity on the propagation angle. We show that a SAW focusing to a diffraction-limited size in GaAs requires corrections that more closely follow the group-velocity wave front, which is not a quadratic function. Optical interferometric mapping of the resultant SAW displacement field reveals tightly focused SAW beams on GaAs with a minimal beam waist. An additional set of Gouy-phase-corrected passive fingers creates an acoustic microcavity in the focal region with a small volume and a high quality factor. Our λSAW=5.6μm FIDTs are expected to scale well to the approximately 500-nm wavelength regime needed to study strong coupling between vibrations and electrons in electrostatic GaAs quantum dots.

Date: 2014-06-07

Creator: Kenneth A. Dennison, Thomas W. Baumgarte

Access: Open access

We describe a simple family of analytical coordinate systems for the Schwarzschild spacetime. The coordinates penetrate the horizon smoothly and are spatially isotropic. Spatial slices of constant coordinate time t feature a trumpet geometry with an asymptotically cylindrical end inside the horizon at a prescribed areal radius R0 (with 0 < R0 M) that serves as the free parameter for the family. The slices also have an asymptotically flat end at spatial infinity. In the limit R0 = 0 the spatial slices lose their trumpet geometry and become flat - in this limit, our coordinates reduce to Painlevé- Gullstrand coordinates. © 2014 IOP Publishing Ltd.

Date: 2002-01-01

Creator: M. Saijo, T.W. Baumgarte, S.L. Shapiro, M. Shibata

Access: Open access

Date: 2004-01-01

Creator: I.A. Morrison, T.W. Baumgarte, S.L. Shapiro, V.R. Pandharipande

Access: Open access

Date: 1991-01-01

Creator: R. Morrison, D. Schmidt, M. Procario, D. R. Johnson, K., Lingel, P. Rankin, J. G. Smith, J. Alexander, M. Artuso, C. Bebek, K. Berkelman, D. Besson, T. E. Browder, D. G. Cassel, E. Cheu, 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, J. Kandaswamy, N. Katayama, D. L. Kreinick, J. D. Lewis, G. S. Ludwig

Access: Open access

Using the CsI calorimeter of the CLEO II detector, the spin triplet b(2P) states are observed in (3S) radiative decays with much higher statistics than seen in previous experiments. The observed mass splittings are not described well by theoretical models, while the relative branching ratios agree with predictions that include relativistic corrections to the radiative transition rates. © 1991 The American Physical Society.

Date: 1991-01-01

Creator: Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S., Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson, D. Bortoletto, D. Brown, J. Dominick, R. L. McIlwain, D. H. Miller, M. Modesitt, C. R. Ng, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, M. Battle, H. Kroha, K. Sparks, E. H. Thorndike, C. H. Wang, M. S. Alam

Access: Open access

The spin alignment of D*+ mesons produced in e+e- annihilation at s=10.5 GeV is obtained from a study of the angular distribution of the decay D*+D0+. The alignment is studied as a function of momentum and compared to theoretical predictions. We find an average value of the spin alignment parameter of =0.040.020.01. We obtain a model-dependent measurement of the probability of producing a vector particle PV=0.770.020.01 for D mesons. © 1991 The American Physical Society.

Date: 1991-01-01

Creator: G. Crawford, R. Fulton, K. K. Gan, T. Jensen, D. R., Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson, D. Bortoletto, D. Brown, J. Dominick, R. L. McIlwain, D. H. Miller, M. Modesitt, C. R. Ng, S. F. Schaffner, E. I. Shibata, I. P.J. Shipsey, M. Battle, P. Kim, H. Kroha, K. Sparks, E. H. Thorndike, C. H. Wang, M. S. Alam, I. J. Kim, B. Nemati, V. Romero

Access: Open access

Using the CLEO detector at the Cornell Electron Storage Ring, we have performed a direct measurement of the ratio of D0 semileptonic branching fractions into vector and pseudoscalar final states. We find B(D0K*-e+e)B(D0K-e+e)=0.510.180.06, in agreement with the ratio derived by the E691 experiment which compares D+ and D0 final states. We also set an upper limit on the ratio B(D0*0-e+e)B(D0K*-e+e)<0.64 at 90% confidence level. © 1991 The American Physical Society.

Date: 1991-01-01

Creator: K. Kinoshita, F. M. Pipkin, M. Procario, Richard Wilson, J., Wolinski, D. Xiao, Y. Zhu, R. Ammar, P. Baringer, D. Coppage, R. Davis, P. Haas, M. Kelly, N. Kwak, Ha Lam, S. Ro, Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore, P. Wilson

Access: Open access

We have made measurements of decay modes of neutral D mesons into exclusive final states containing photons using data collected with the CLEO detector at the Cornell Electron Storage Ring. We report observation of D0'K-+-+0 (charge conjugates are implicit), and present new measurements of the branching ratios for D0'K-+0, D0'K0+0-, D0'K00, K*0, and D0'K0. Where possible, results are compared with theoretical predictions for two-body D0 decays. © 1991 The American Physical Society.

Date: 1992-01-01

Creator: S. Henderson, K. Kinoshita, F. Pipkin, M. Procario, M., Saulnier, R. Wilson, J. Wolinski, D. Xiao, R. Ammar, P. Baringer, D. Coppage, R. Davis, P. Haas, M. Kelly, N. Kwak, Ha Lam, S. Ro, Y. Kubota, J. K. Nelson, D. Perticone, R. Poling, S. Schrenk, G. Crawford, R. Fulton, T. Jensen, D. R. Johnson, H. Kagan, R. Kass, R. Malchow, F. Morrow, J. Whitmore

Access: Open access

We report new measurements of semileptonic branching fractions of B mesons produced at the '(4S) resonance determined by fitting the inclusive electron and muon momentum spectra to different theoretical models. Using B(B»'X"-») to denote the average of the semileptonic branching fractions for B decay to electrons and muons, we obtain B(B»'X"-»)= (10.5±0.2±0.4)% using the refined free-quark model of Altarelli et al., and B(B»'X"-»)=(11.2±0.3±0.4)% using a modified version of the form-factor model of Isgur et al., in which the D**"-» contribution is allowed to float in the fit. The average of these two results is B(B»'X"-»)=(10.8±0. 2±0.4±0.4)%, where the errors are statistical, systematic uncertainties in the measurement, and systematic uncertainties associated with the theoretical models, respectively. Semileptonic branching fractions as low as this are difficult to accommodate in theoretical models where hadronic B-meson decays arise only from spectator diagrams. We use dilepton yields to limit the uncertainty in the semileptonic branching fraction due to the possible existence of non-BB» decays of the '(4S). In addition, we tag neutral B mesons using the decays B»0'D*+- and B»0'D*+"-» to obtain the first direct measurement of semileptonic branching fractions for neutral B mesons; the average of the electron and muon results for neutral B mesons is B(B»0'X"-»)=(9.9±3.0±0.9)%. © 1992 The American Physical Society.

Date: 2005-12-01

Creator: Michael L. Bender, David T. Ho, Melissa B. Hendricks, Robert Mika, Mark O., Battle, Pieter P. Tans, Thomas J. Conway, Blake Sturtevant, Nicolas Cassar

Access: Open access

Improvements made to an established mass spectrometric method for measuring changes in atmospheric O2/N2 are described. With the improvements in sample handling and analysis, sample throughput and analytical precision have both increased. Aliquots from duplicate flasks are repeatedly measured over a period of 2 weeks, with an overall standard error in each flask of 3-4 per meg, corresponding to 0.6-0.8 ppm O2 in air. Records of changes in O2/N2 from six global sampling stations (Barrow, American Samoa, Cape Grim, Amsterdam Island, Macquarie Island, and Syowa Station) are presented. Combined with measurements Of CO2 from the same sample flasks, land and ocean carbon uptake were calculated from the three sampling stations with the longest records (Barrow, Samoa, and Cape Grim). From 1994-2002, We find the average CO2 uptake by the ocean and the land biosphere was 1.7 ± 0.5 and 1.0 ± 0.6 GtC yr -1 respectively; these numbers include a correction of 0.3 Gt C yr-l due to secular outgassing of ocean O2. Interannual variability calculated from these data shows a strong land carbon source associated with the 1997-1998 El Niño event, supporting many previous studies indicating that high atmospheric growth rates observed during most El Niño events reflect diminished land uptake. Calculations of interannual variability in land and ocean uptake are probably confounded by non-zero annual air sea fluxes of O2. The origin of these fluxes is not yet understood. Copyright 2005 by the American Geophysical Union.

Date: 2008-06-30

Creator: X. Faïn, C. P. Ferrari, A. Dommergue, M. Albert, M., Battle, L. Arnaud, J. M. Barnola, W. Cairns, C. Barbante, C. Boutron

Access: Open access

Gaseous Elemental Mercury (Hg° or GEM) was investigated at Summit Station, Greenland, in the interstitial air extracted from the perennial snowpack (firn) at depths ranging from the surface to 30 m, during summer 2005 and spring 2006. Photolytic production and destruction of Hg° were observed close to the snow surface during summer 2005 and spring 2006, and we observed dark oxidation of GEM up to 270 cm depth in June 2006. Photochemical transformation of gaseous elemental mercury resulted in diel variations in the concentrations of this gas in the near-surface interstitial air, but destruction of Hg° was predominant in June, and production was the main process in July. This seasonal evolution of the chemical mechanisms involving gaseous elemental mercury produces a signal that propagates downward through the firn air, but is unobservably small below 15 m in depth. As a consequence, multi-annual averaged records of GEM concentration should be well preserved in deep firn air at depths below 15 m, and available for the reconstruction of the past atmospheric history of GEM over the last decades.

Date: 2007-08-01

Creator: J. P. Eisenstein, D. Syphers, L. N. Pfeiffer, K. W. West

Access: Open access

The quantum lifetime of two-dimensional holes in a GaAs/AlGaAs double quantum well is determined via tunneling spectroscopy. At low temperatures the lifetime is limited by impurity scattering but at higher temperatures hole-hole Coulomb scattering dominates. Our results are consistent with the Fermi liquid theory, at least up to rs = 11. At the highest temperatures the measured width of the hole spectral function becomes comparable to the Fermi energy. A new, tunneling-spectroscopic method for determining the in-plane effective mass of the holes is also demonstrated. © 2007 Elsevier Ltd. All rights reserved.

Date: 2009-09-22

Creator: Xavier Faïn, Christophe P. Ferrari, Aurélien Dommergue, Mary R. Albert, Mark, Battle, Jeff Severinghaus, Laurent Arnaud, Jean Marc Barnola, Warren Cairns, Carlo Barbante, Claude Boutron

Access: Open access

Mercury (Hg) is an extremely toxic pollutant, and its biogeochemical cycle has been perturbed by anthropogenic emissions during recent centuries. In the atmosphere, gaseous elemental mercury (GEM; Hg°) is the predominant form of mercury (up to 95%). Here we report the evolution of atmospheric levels of GEM in mid- to high-northern latitudes inferred from the interstitial air of firn (perennial snowpack) at Summit, Greenland. GEM concentrations increased rapidly after World War II from ≈1.5 ng m-3 reaching a maximum of ≈3 ng m-3 around 1970 and decreased until stabilizing at ≈1.7 ng m -3 around 1995. This reconstruction reproduces real-time measurements available from the Arctic since 1995 and exhibits the same general trend observed in Europe since 1990. Anthropogenic emissions caused a two-fold rise in boreal atmospheric GEM concentrations before the 1970s, which likely contributed to higher deposition of mercury in both industrialized and remotes areas. Once deposited, this toxin becomes available for methylation and, subsequently, the contamination of ecosystems. Implementation of air pollution regulations, however, enabled a large-scale decline in atmospheric mercury levels during the 1980s. The results shown here suggest that potential increases in emissions in the coming decades could have a similar large-scale impact on atmospheric Hg levels.

Date: 2000-12-18

Creator: Isabel P. Ennes, Carlos Lozano, Stephen G. Naculich, Howard J. Schnitzer

Access: Open access

We analyze the large N supergravity descriptions of the class of type IIB models T-dual to elliptic type IIA brane configurations containing two orientifold 6-planes and up to two NS 5-branes. The T-dual IIB configurations contain N D3-branes in the background of an orientifold 7-plane and, in some models, a Z2 orbifold and/or D7-branes, which give rise to four-dimensional N=2 (or N=4) gauge theories with at most two factors. We identify the chiral primary states of the supergravity theories, and match them to gauge invariant operators of the corresponding superconformal theories using Maldacena's duality. © 2000 Elsevier Science B.V.

Date: 1999-06-24

Creator: James H. Butler, Mark Battle, Michael L. Bender, Stephen A. Montzka, Andrew D., Clarke, Eric S. Saltzman, Cara M. Sucher, Jeffrey P. Severinghaus, James W. Elkins

Access: Open access

Measurements of trace gases in air trapped in polar firn (unconsolidated snow) demonstrate that natural sources of chlorofluorocarbons, halons, persistent chlorocarbon solvents and sulphur hexafluoride to the atmosphere are minimal or non-existent. Atmospheric concentrations of these gases, reconstructed back to the late nineteenth century, are consistent with atmospheric histories derived from anthropogenic emission rates and known atmospheric lifetimes. The measurements confirm the predominance of human activity in the atmospheric budget of organic chlorine, and allow the estimation of atmospheric histories of halogenated gases of combined anthropogenic and natural origin. The pre-twentieth-century burden of methyl chloride was close to that at present, while the burden of methyl bromide was probably over half of today's value.

Date: 1999-07-01

Creator: R. L. Langenfelds, R. J. Francey, L. P. Steele, M. Battle, R. F., Keeling, W. F. Budd

Access: Open access

O2/N2 is measured in the Cape Grim Air Archive (CGAA), a suite of tanks filled with background air at Cape Grim, Tasmania (40.7°S, 144.8°E) between April 1978 and January 1997. Derived trends are compared with published O2/N2 records and assessed against limits on interannual variability of net terrestrial exchanges imposed by trends of δ13C in CO2. Two old samples from 1978 and 1987 and eight from 1996/97 survive critical selection criteria and give a mean 19-year trend in δ(O2/N2) of -16.7 ± 0.5 per meg yr-1, implying net storage of +2.3 ± 0.7 GtC (1015 g carbon) yr-1 of fossil fuel CO2 in the oceans and +0.2 ± 0.9 GtC yr-1 in the terrestrial biosphere. The uptake terms are consistent for both O2/N2 and δ13C tracers if the mean 13C isotopic disequilibrium flux, combining terrestrial and oceanic contributions, is 93 ± 15 GtC ‰ yr-1. Copyright 1999 by the American Geophysical Union.

Date: 1995-01-01

Creator: R. Balest, K. Cho, T. Ford, D. R. Johnson, K., Lingel, M. Lohner, P. Rankin, J. G. Smith, J. P. Alexander, C. Bebek, K. Berkelman, K. Bloom, T. E. Browder, D. G. Cassel, H. A. Cho, D. M. Coffman, D. S. Crowcroft, P. S. Drell, D. Dumas, R. Ehrlich, P. Gaidarev, R. S. Galik, M. Garcia-Sciveres, B. Geiser, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, S. Henderson, C. D. Jones, S. L. Jones

Access: Open access

We consider the decay of Υ(1S) particles produced at CESR into a photon which is observed by the CLEO detector plus particles which are not seen. These could be real particles which fall outside of our acceptance, or particles which are noninteracting. We report the results of our search fo the process Υ(1S)→γ+''unseen'' for photon energies >1 GeV, obtaining limits for the case where ''unseen'' is either a single particle or a particle-antiparticle pair. Our upper limits represent the highest sensitivity measurements for such decays to date. © 1995 The American Physical Society.

Date: 2014-01-01

Creator: Stephen G. Naculich

Access: Open access

Inspired by recent developments on scattering equations, we present a constructive procedure for computing symmetric, amplitude-encoded, BCJ numerators for n-point gauge-theory amplitudes, thus satisfying the three virtues identified by Broedel and Carrasco. We also develop a constructive procedure for computing symmetric, amplitude-encoded dual-trace functions τ for n-point amplitudes. These can be used to obtain symmetric kinematic numerators that automatically satisfy color-kinematic duality. The S n symmetry of n-point gravity amplitudes formed from these symmetric dual-trace functions is completely manifest. Explicit expressions for four- and five-point amplitudes are presented. © 2014 The Author(s).

Date: 2008-12-11

Creator: Stephen G. Naculich, Horatiu Nastase, Howard J. Schnitzer

Access: Open access

We derive an ABDK-like relation between the one- and two-loop four-graviton amplitudes in N = 8 supergravity. Specifically we show that the infrared-divergent part of the two-loop amplitude is one-half the square of the one-loop amplitude, suggesting an exponential structure for IR divergences. The difference between the two-loop amplitude and one-half the square of the full one-loop amplitude is therefore finite, and expressible in a relatively simple form. We give arguments for generalizations to higher loops and n-point functions, suggesting that the exponential of the full one-loop amplitude may be corrected, to low orders, by only simple finite terms. © 2008 Elsevier B.V. All rights reserved.

Date: 2003-08-01

Creator: Stephen G. Naculich, Howard J. Schnitzer, Niclas Wyllard

Access: Open access

We study the matrix model/gauge theory connection for three different N =1 models: U(N) × U(N) with matter in bifundamental representations, U(N) with matter in the symmetric representation, and U (N) with matter in the antisymmetric representation. Using Ward identities, we explicitly show that the loop equations of the matrix models lead to cubic algebraic curves. We then establish the equivalence of the matrix model and gauge theory descriptions in two ways. First, we derive generalized Konishi anomaly equations in the gauge theories, showing that they are identical to the matrix-model equations. Second, we use a perturbative superspace analysis to establish the relation between the gauge theories and the matrix models. We find that the gauge coupling matrix for U (N) with matter in the symmetric or antisymmetric representations is not given by the second derivative of the matrix-model free energy. However, the matrix-model prescription can be modified to give the gauge coupling matrix. © SISSA/ISAS 2003.

Date: 1993-01-01

Creator: Stephen G. Naculich

Access: Open access

Relations among fermion masses and mixing angles at the scale of grand unification are modified at lower energies by renormalization group running induced by gauge and Yukawa couplings. In super-symmetric theories, the b quark and lepton Yukawa couplings, as well as the t quark coupling, may cause significant running if tan, the ratio of Higgs field expectation values, is large. We present approximate analytic expressions for the scaling factors for fermion masses and CKM matrix elements induced by all three third generation Yukawa couplings. We then determine how running caused by the third generation of fermions affects the predictions arising from three possible forms for the Yukawa coupling matrices at the GUT scale: the Georgi-Jarlskog, Giudice, and Fritzsch textures. © 1993 The American Physical Society.

Date: 1992-01-01

Creator: Stephen G. Naculich

Access: Open access

We examine solitons in theories with heavy fermions. These "quantum" solitons differ dramatically from semiclassical (perturbative) solitons because fermion loop effects are important when the Yukawa coupling is strong. We focus on kinks in a (1 + 1)-dimensional 4 theory coupled to fermions; a large-N expansion is employed to treat the Yukawa coupling g nonperturbatively. A local expression for the fermion vacuum energy is derived using the WKB approximation for the Dirac eigenvalues. We find that fermion loop corrections increase the energy of the kink and (for large g) decrease its size. For large g, the energy of the quantum kink is proportional to g, and its size scales as 1g, unlike the classical kink; we argue that these features are generic to quantum solitons in theories with strong Yukawa couplings. We also discuss the possible instability of fermions to solitons. © 1992 The American Physical Society.

Date: 1994-01-01

Creator: R. Ammar, S. Ball, P. Baringer, A. Bean, D., Besson, D. Coppage, N. Copty, R. Davis, N. Hancock, M. Kelly, N. Kwak, H. Lam, Y. Kubota, M. Lattery, J. K. Nelson, S. Patton, D. Perticone, R. Poling, V. Savinov, S. Schrenk, R. Wang, M. S. Alam, I. J. Kim, B. Nemati, J. J. O'Neill, H. Severini, C. R. Sun, M. M. Zoeller, G. Crawford, C. M. Daubenmier, R. Fulton

Access: Open access

We have searched for B0 decays to two charged leptons and set 90% confidence level upper limits on the branching fractions: B(B0→e+e-)<5. 9×10-6, B(B0→μ+μ-)<5.9×10-6, B(B0→e±μ) <5.9×10-6, B(B0→e±τ)<5.3×10-4, and B(B0→μ±τ)<8.3×10-4. © 1994 The American Physical Society.

Date: 1994-01-01

Creator: M. Artuso, D. He, M. Goldberg, N. Horwitz, R., Kennett, G. C. Moneti, F. Muheim, Y. Mukhin, S. Playfer, Y. Rozen, S. Stone, M. Thulasidas, G. Vasseur, G. Zhu, J. Bartelt, S. E. Csorna, Z. Egyed, V. Jain, P. Sheldon, D. S. Akerib, B. Barish, M. Chadha, S. Chan, D. F. Cowen, G. Eigen, J. S. Miller, C. O'Grady, J. Urheim, A. J. Weinstein, D. Acosta, M. Athanas

Access: Open access

A measurement of the cross section for γγ→pp̄ is performed at two-photon center-of-mass energies between 2.00 and 3.25 GeV. These results are obtained using e+e-→e+e-pp̄ events selected from 1.31 fb-1 of data taken with the CLEO II detector. The measured cross section is in reasonable agreement with previous measurements and is in excellent agreement with recent calculations based on a diquark model. However, leading order QCD calculations performed using the Brodsky-Lepage formalism are well below the measured cross section. © 1994 The American Physical Society.

Date: 1993-01-01

Creator: J. Bartelt, S. E. Csorna, Z. Egyed, V. Jain, D. S., Akerib, B. Barish, M. Chadha, S. Chan, D. F. Cowen, G. Eigen, J. S. Miller, C. O'Grady, J. Urheim, A. J. Weinstein, D. Acosta, M. Athanas, G. Masek, H. Paar, M. Sivertz, A. Bean, J. Gronberg, R. Kutschke, S. Menary, R. J. Morrison, S. Nakanishi, H. N. Nelson, T. K. Nelson, J. D. Richman, A. Ryd, H. Tajima, D. Schmidt

Access: Open access

Using the CLEO II detector and a sample of 955 000 Υ(4S) decays we have confirmed charmless semileptonic decays of B mesons. In the momentum interval 2.3-2.6 GeV/c we observe an excess of 107±15±11 leptons, which we attribute to b→ulν. This result yields a model-dependent range of values for Vub/Vcb that is lower than has been obtained in previous studies. For the inclusive spectator model of Altarelli et al. we find Vub/Vcb=0.076±0.008. Models that describe b→ulν with a limited set of exclusive final states give Vub/Vcb=0.06-0.10. © 1993 The American Physical Society.

Date: 2015-01-12

Creator: Sean Barker, Mohamed Musthag, David Irwin, Prashant Shenoy

Access: Open access

An increasing interest in energy-efficiency combined with the decreasing cost of embedded networked sensors is lowering the cost of outlet-level metering. If these trends continue, new buildings in the near future will be able to install 'smart' outlets, which monitor and transmit an outlets power usage in real time, for nearly the same cost as conventional outlets. One problem with the pervasive deployment of smart outlets is that users must currently identify the specific device plugged into each meter, and then manually update the outlets meta-data in software whenever a new device is plugged into the outlet. Correct meta-data is important in both interpreting historical outlet energy data and using the data for building management. To address this problem, we propose Non-Intrusive Load Identification (NILI), which automatically identifies the device attached to a smart outlet without any human intervention. In particular, in our approach to NILI, we identify an intuitive and simple-to-compute set of features from time-series energy data and then employ well-known classifiers. Our results achieve accuracy of over 90% across 15 device types on outlet-level energy traces collected from multiple real homes.

Date: 2010-07-21

Creator: Pamela V. Chang, Danielle H. Dube, Ellen M. Sletten, Carolyn R. Bertozzi

Access: Open access

Glycans can be imaged by metabolic labeling with azidosugars followed by chemical reaction with imaging probes; however, tissue-specific labeling is difficult to achieve. Here we describe a strategy for the use of a caged metabolic precursor that is activated for cellular metabolism by enzymatic cleavage. An N-azidoacetylmannosamine derivative caged with a peptide substrate for the prostate-specific antigen (PSA) protease was converted to cell-surface azido sialic acids in a PSA-dependent manner. The approach has applications in tissue-selective imaging of glycans for clinical and basic research purposes. © 2010 American Chemical Society.

Date: 2021-10-01

Creator: Abigail Kaminski, Dana Marie Bauer, Kathleen P. Bell, Cynthia S. Loftin, Erik J., Nelson

Access: Open access

Context: Urban-rural gradients are useful tools when examining the influence of human disturbances on ecological, social and coupled systems, yet the most commonly used gradient definitions are based on single broad measures such as housing density or percent forest cover that fail to capture landscape patterns important for conservation. Objectives: We present an approach to defining urban–rural gradients that integrates multiple landscape pattern metrics related to ecosystem processes important for natural resources and wildlife sustainability. Methods: We develop a set of land cover composition and configuration metrics and then use them as inputs to a cluster analysis process that, in addition to grouping towns with similar attributes, identifies exemplar towns for each group. We compare the outcome of the cluster-based urban-rural gradient typology to outcomes for four commonly-used rule-based typologies and discuss implications for resource management and conservation. Results: The resulting cluster-based typology defines five town types (urban, suburban, exurban, rural, and agricultural) and notably identifies a bifurcation along the gradient distinguishing among rural forested and agricultural towns. Landscape patterns (e.g., core and islet forests) influence where individual towns fall along the gradient. Designations of town type differ substantially among the five different typologies, particularly along the middle of the gradient. Conclusions: Understanding where a town occurs along the urban-rural gradient could aid local decision-makers in prioritizing and balancing between development and conservation scenarios. Variations in outcomes among the different urban-rural gradient typologies raise concerns that broad-measure classifications do not adequately account for important landscape patterns. We suggest future urban-rural gradient studies utilize more robust classification approaches.