Date: 2017-01-01

Creator: T.S. Magney, B.A. Logan, J.S. Reblin, N.T. Boelman, J.U.H., Eitel, H.E. Greaves, K.L. Griffin, C.M. Prager, L.A. Vierling

Access: Open access

Date: 2013-04-13

Creator: George Ritzer

Access: Open access

Many of “cyber-utopians” have lauded the Internet, especially social networking sites, for a variety of reasons, including making possible a dramatic and revolutionary increase in social collaboration (Benkler, 2007; Tapscott and Williams, 2006). The goal of this essay is to examine- and, at least in part, debunk- this claim from a new and unique sociological perspective- the relationship between collaboration and the “new means of prosumption”. Such an examination is suggested by the fact that collaboration is, by definition, a form of prosumption. That is, it involves one or more parties “producing” and other(s) “consuming” something of mutual interest and importance. However, the collaborative process, like prosumption more generally, is not as separable as all that. In fact, collaboration is a dialectical process in which those involved are continually changing their positions on the prosumption continuum (see below), sometimes they are more

Date: 2022-11-15

Creator: Elizabeth R. Chrastil, Caroline Rice, Mathias Goncalves, Kylie N. Moore, Syanah C. Wynn, Chantal E. Stern, Erika Nyhus

Access: Open access

Active navigation seems to yield better spatial knowledge than passive navigation, but it is unclear how active decision-making influences learning and memory. Here, we examined the contributions of theta oscillations to memory-related exploration while testing theories about how they contribute to active learning. Using electroencephalography (EEG), we tested individuals on a maze-learning task in which they made discrete decisions about where to explore at each choice point in the maze. Half the participants were free to make active decisions at each choice point, and the other half passively explored by selecting a marked choice (matched to active exploration) at each intersection. Critically, all decisions were made when stationary, decoupling the active decision-making process from movement and speed factors, which is another prominent potential role for theta oscillations. Participants were then tested on their knowledge of the maze by traveling from object A to object B within the maze. Results show an advantage for active decision-making during learning and indicate that the active group had greater theta power during choice points in exploration, particularly in midfrontal channels. These findings demonstrate that active exploration is associated with theta oscillations during human spatial navigation, and that these oscillations are not exclusively related to movement or speed. Results demonstrating increased theta oscillations in prefrontal regions suggest communication with the hippocampus and integration of new information into memory. We also found evidence for alpha oscillations during active navigation, suggesting a role for attention as well. This study finds support for a general mnemonic role for theta oscillations during navigational learning. © 2022

Date: 2015-09-01

Creator: Tess Chakkalakal

Access: Open access

Date: 2021-06-01

Creator: Myron Child, Jack R. Bateman, Amir Jahangiri, Armando Reimer, Nicholas C., Lammers, Nica Sabouni, Diego Villamarin, Grace C. McKenzie-Smith, Justine E. Johnson, Daniel Jost, Hernan G. Garcia

Access: Open access

3D eukaryotic genome organization provides the structural basis for gene regulation. In Drosophila melanogaster, genome folding is characterized by somatic homolog pairing, where homologous chromosomes are intimately paired from end to end; however, how homologs identify one another and pair has remained mysterious. Recently, this process has been proposed to be driven by specifically interacting “buttons” encoded along chromosomes. Here, we turned this hypothesis into a quantitative biophysical model to demonstrate that a button-based mechanism can lead to chromosome-wide pairing. We tested our model using live-imaging measurements of chromosomal loci tagged with the MS2 and PP7 nascent RNA labeling systems. We show solid agreement between model predictions and experiments in the pairing dynamics of individual homologous loci. Our results strongly support a button-based mechanism of somatic homolog pairing in Drosophila and provide a theoretical framework for revealing the molecular identity and regulation of buttons.

Date: 2012-08-30

Creator: Mary Rogalski

Access: Open access

Date: 2000-04-01

Creator: William R. Jackman, James A. Langeland, Charles B. Kimmel

Access: Open access

The vertebrate embryonic hindbrain is segmented into rhombomeres. Gene expression studies suggest that amphioxus, the closest invertebrate relative of vertebrates, has a hindbrain homolog. However, this region is not overtly segmented in amphioxus, raising the question of how hindbrain segmentation arose in chordate evolution. Vertebrate hindbrain segmentation includes the patterning of cranial motor neurons, which can be identified by their expression of the LIM-homeodomain transcription factor islet1. To learn if the amphioxus hindbrain homolog is cryptically segmented, we cloned an amphioxus gene closely related to islet1, which we named simply islet. We report that amphioxus islet expression includes a domain of segmentally arranged cells in the ventral hindbrain homolog. We hypothesize that these cells are developing motor neurons and reveal a form of hindbrain segmentation in amphioxus. Hence, vertebrate rhombomeres may derive from a cryptically segmented brain present in the amphioxus/vertebrate ancestor. Other islet expression domains provide evidence for amphioxus homologs of the pineal gland, adenohypophysis, and endocrine pancreas. Surprisingly, homologs of vertebrate islet1-expressing spinal motor neurons and Rohon-Beard sensory neurons appear to be absent. (C) 2000 Academic Press.

Date: 2016-02-25

Creator: B. Zorina Khan

Access: Open access

The French economy has been criticized for a lack of integration of women in business and for the prevalence of inefficient family firms. A sample drawn from patent and exhibition records is used to examine the role of women in enterprise and invention in France. Middle-class women were extensively engaged in entrepreneurship and innovation, and the empirical analysis indicates that their commercial efforts were significantly enhanced by association with family firms. Such formerly invisible achievements suggest a more productive role for family-based enterprises, as a means of incorporating relatively disadvantaged groups into the market economy as managers and entrepreneurs. This business model .... melds entrepreneurial passion with a long family tradition. - Wendel Company (1704-2014) 1

Date: 2013-10-28

Creator: Yao Tang, Yoshinori Kurokawa, Jiaren Pang

Access: Open access

We construct a dynamic Ricardian model of trade with money and nominal exchange rate. The model implies that the nominal wages of the trading countries are more likely to exhibit stronger positive comovements when the countries fix their bilateral exchange rates. Panel regression results based on data from OECD countries from 1973 to 2012 suggest that countries in the European Monetary Union (EMU) experienced stronger positive wage comovements with their main trade partners. When we restrict the regression to the subsample of the EMU countries, we find a significant increase in wage comovements after these countries joined the EMU in 1999 compared to the pre-euro era. In comparison, when the sample is restricted to the non-EMU countries, we find no evidence that non-currency union pegs affected the wage comovements.

Date: 2014-01-01

Creator: Anja Forche

Access: Open access

Pathogenic fungi encounter many different host environments to which they must adapt rapidly to ensure growth and survival. They also must be able to cope with alterations in established niches during long-term persistence in the host. Many eukaryotic pathogens have evolved a highly plastic genome, and large-scale chromosomal changes including aneuploidy, and loss of heterozygosity (LOH) can arise under various in vitro and in vivo stresses. Both aneuploidy and LOH can arise quickly during a single cell cycle, and it is hypothesized that they provide a rapid, albeit imprecise, solution to adaptation to stress until better and more refined solutions can be acquired by the organism. While LOH, with the extreme case of haploidization in Candida albicans, can purge the genome from recessive lethal alleles and/or generate recombinant progeny with increased fitness, aneuploidy, in the absence or rarity of meiosis, can serve as a non-Mendelian mechanism for generating genomic variation. © Springer Science+Business Media 2014.

Date: 2017-01-01

Creator: Emilie Dassié, Kristine Delong, Hali Kilbourne, Branwen Williams, Nerilie, Abram, Logan Brenner, Chloé Brahmi, Kim M. Cobb, Thierry Corrège, Delphine Dissard, Julien Emile-Geay, Heitor Evangelista, Michael N. Evans, Jesse Farmer, Thomas Felis, Michael Gagan, David P. Gillikin, Nathalie Goodkin, Myriam Khodri, Ana Carolina Lavagnino, Michèle Lavigne, Claire Lazareth, Braddock Linsley, Janice Lough, Helen McGregor, Intan S. Nurhati, Gilman Ouellette, Laura Perrin, Maureen Raymo, Brad Rosenheim, Michael Sandstrom, Bernd R. Schöne

Access: Open access

Date: 2014-01-01

Creator: Allen Wells, Natalia Sanz González, (translator)

Access: Open access

Setecientos cincuenta refugiados judíos dejaron la Alemania nazi y fundaron la colonia agrícola de Sosúa en la República Dominicana, que en ese momento estaba bajo el régimen de uno de los dictadores más represivos de Latinoamérica, el general Rafael Trujillo. En este libro, Allen Wells, hijo de uno de los colonos de Sosúa, cuenta la historia del general Trujillo, Franklin Delano Roosevelt y los afortunados pioneros que fundaron, en la costa norte de la isla, una exitosa cooperativa de productos lácteos de propiedad de los mismos empleados. ¿Por qué el dictador admitió a esos desesperados refugiados cuando muy pocas naciones aceptaron a los que escapaban del nazismo? Ansioso de mitigar las críticas internacionales después de que su Ejército masacrara varios miles de haitianos desarmados, Trujillo mandó a sus representantes a una conferencia sobre los refugiados del nazismo realizada en Évian, Francia, en 1938. Propuesta por Roosevelt para desviar las críticas a las políticas restrictivas de inmigración de su Gobierno, la Conferencia de Évian resultó un completo fracaso. La República Dominicana fue la única nación que aceptó abrir sus puertas; el oportunista Trujillo buscaba “blanquear” la población dominicana, recibiendo refugiados judíos, quienes en Europa eran ellos mismos sujeto de desprecio racista. Debido a que los Estados Unidos no admitieron números significativos de refugiados judíos, alentaron a Latinoamérica a aceptarlos. Esta propuesta, sumada a la preocupación mayor de Roosevelt de luchar contra el nazismo, fortaleció las relaciones estadounidenses con las dictaduras latinoamericanas en las décadas que vendrían.

Date: 1991-01-01

Creator: M. Alfaro, M. Conger, K. Hodges, A. Levy, R., Kochar, L. Kuklinski

Access: Open access

Date: 2021-01-01

Creator: José Edwards, Stephen Meardon

Access: Open access

In 2018, Clarivate Analytics, publisher of the Web of Science Journal Citation Reports (JCR), suppressed publication of the 2017 Journal Impact Factor (JIF) for three of the four journals that it then indexed in the academic field of history of economics. Clarivate judged one of the journals, History of Economic Ideas (HEI), to be the “donor” of citations that distorted the impact factors of the European Journal of the History of Economic Thought (EJHET) and the Journal of the History of Economic Thought (JHET). The other journal, History of Political Economy (HOPE), was not included in that judgment. Our purpose is to define the JIF, summarize the controversy that gave rise to this symposium, and discuss methodologically and historically some of the problems with the use of citation indexes in general and the JIF in particular. We show how these problems pertain differently to the scholarly field of the history of economics than to economics in general. In so doing we also introduce the following five articles of this symposium.

Date: 2020-05-01

Creator: Erika Nyhus, William A. Engel, Tomas Donatelli Pitfield, Isabella M.W. Vakkur

Access: Open access

Although there has been recent interest in how mindfulness meditation can affect episodic memory as well as brain structure and function, no study has examined the behavioral and neural effects of mindfulness meditation on episodic memory. Here we present a protocol that combines mindfulness meditation training, an episodic memory task, and EEG to examine how mindfulness meditation changes behavioral performance and the neural correlates of episodic memory. Subjects in a mindfulness meditation experimental group were compared to a waitlist control group. Subjects in the mindfulness meditation experimental group spent four weeks training and practicing mindfulness meditation. Mindfulness was measured before and after training using the Five Facet Mindfulness Questionnaire (FFMQ). Episodic memory was measured before and after training using a source recognition task. During the retrieval phase of the source recognition task, EEG was recorded. The results showed that mindfulness, source recognition behavioral performance, and EEG theta power in right frontal and left parietal channels increased following mindfulness meditation training. In addition, increases in mindfulness correlated with increases in theta power in right frontal channels. Therefore, results obtained from combining mindfulness meditation training, an episodic memory task, and EEG reveal the behavioral and neural effects of mindfulness meditation on episodic memory.

Date: 2016-04-01

Creator: Bruce D. Kohorn, Divya Hoon, Benjamin B. Minkoff, Michael R. Sussman, Susan L., Kohorn

Access: Open access

The wall-associated kinases (WAKs)1 are receptor protein kinases that bind to long polymers of cross-linked pectin in the cell wall. These plasma-membrane-associated protein kinases also bind soluble pectin fragments called oligo-galacturonides (OGs) released from the wall after pathogen attack and damage. WAKs are required for cell expansion during development but bind water soluble OGs generated from walls with a higher affinity than the wall-associated polysaccharides. OGs activate a WAKdependent, distinct stress-like response pathway to help plants resist pathogen attack. In this report, a quantitative mass-spectrometric-based phosphoproteomic analysis was used to identify Arabidopsis cellular events rapidly induced by OGs in planta. Using N14/ N15 isotopic in vivo metabolic labeling, we screened 1,000 phosphoproteins for rapid OG-induced changes and found 50 proteins with increased phosphorylation, while there were none that decreased significantly. Seven of the phosphosites within these proteins overlap with those altered by another signaling molecule plants use to indicate the presence of pathogens (the bacterial "elicitor" peptide Flg22), indicating distinct but overlapping pathways activated by these two types of chemicals. Genetic analysis of genes encoding 10 OG-specific and two Flg22/OG-induced phosphoproteins reveals that null mutations in eight proteins compromise the OG response. These phosphorylated proteins with genetic evidence supporting their role in the OG response include two cytoplasmic kinases, two membrane-associated scaffold proteins, a phospholipase C, a CDPK, an unknown cadmium response protein, and a motor protein. Null mutants in two proteins, the putative scaffold protein REM1.3, and a cytoplasmic receptor like kinase ROG2, enhance and suppress, respectively, a dominant WAK allele. Altogether, the results of these chemical and genetic experiments reveal the identity of several phosphorylated proteins involved in the kinase/ phosphatase-mediated signaling pathway initiated by cell wall changes.

Date: 2016-01-01

Creator: Bruce D. Kohorn

Access: Open access

The pectin matrix of the angiosperm cell wall is regulated in both synthesis and modification and greatly influences the direction and extent of cell growth. Pathogens, herbivory and mechanical stresses all influence this pectin matrix and consequently plant form and function. The cell wall-associated kinases (WAKs) bind to pectin and regulate cell expansion or stress responses depending upon the state of the pectin. This review explores the WAKs in the context of cell wall biology and signal transduction pathways.

Date: 2019-09-04

Creator: Erika Nyhus, William Andrew Engel, Tomas Donatelli Pitfield, Isabella Marie Wang Vakkur

Access: Open access

Mindfulness meditation has been shown to improve episodic memory and increase theta oscillations which are known to play a role in episodic memory retrieval. The present study examined the effect of mindfulness meditation on episodic memory retrieval and theta oscillations. Using a longitudinal design, subjects in the mindfulness meditation experimental group who underwent 4 weeks of mindfulness meditation training and practice were compared to a waitlist control group. During the pre-training and post-training experimental sessions, subjects completed the Five Facet Mindfulness Questionnaire (FFMQ) and studied adjectives and either imagined a scene (Place Task) or judged its pleasantness (Pleasant Task). During the recognition test, subjects decided which task was performed with each word (“Old Place Task” or “Old Pleasant Task”) or “New.” FFMQ scores and source discrimination were greater post-training than pre-training in the mindfulness meditation experimental group. Electroencephalography (EEG) results revealed that for the mindfulness meditation experimental group theta power was greater post-training than pre-training in right frontal and left parietal channels and changes in FFMQ scores correlated with changes in theta oscillations in right frontal channels (n = 20). The present results suggest that mindfulness meditation increases source memory retrieval and theta oscillations in a fronto-parietal network.

Date: 2021-06-15

Creator: Rachel J. Beane, Eric M.D. Baer, Rowan Lockwood, R. Heather Macdonald, John, R., McDaris, Vernon R. Morris, I. Joshua Villalobos, Lisa D. White

Access: Open access

Date: 2019-08-01

Creator: Lea Takács, Filip Smolík, Samuel Putnam

Access: Open access

Background Previous studies of relations between parenting self-concepts, parental adjustment and child temperament have been ambiguous regarding the direction of influence; and have rarely followed families from pregnancy through the first year of life. The current study examines change and stability in maternal depressive symptoms, parenting competences and child temperament through the perinatal period until nine months postpartum. Methods Czech mothers (N = 282) participated at three time points: the third trimester of pregnancy (Time 1), six weeks (Time 2) and nine months postpartum (Time 3). Questionnaire data concerned depressive symptoms (T1, T2, T3), maternal parenting self-esteem (T1, T2) and sense of competence (T3), and child temperament (T2, T3). A path model was used to examine concurrent and longitudinal relations between these variables. Results The analyses indicated longitudinal stability of all constructs, as well as concurrent relations between them. Longitudinal relations supported child-to-parent, rather than parent-to-child, effects: child difficult temperament predicted decreases in perceived maternal parenting competences, but maternal variables did not predict change in infant temperament. In addition, we observed weak mutual relations between maternal depression levels and parenting competences, such that maternal depression diminished perceived parenting competences that in turn contributed to higher levels of depression. Conclusion Mothers’ confidence in their ability to parent is influenced by their experience with a difficult infant and by their depressive symptoms during the child’s first year of life. Depressive symptoms are, in turn, aggravated by mothers’ low perceived competences in the parenting role.

Date: 2014-01-01

Creator: Xinyang Bing, Teresa Z. Rzezniczak, Jack R. Bateman, Thomas J.S. Merritt

Access: Open access

Transvection, a chromosome pairing-dependent form of trans-based gene regulation, is potentially widespread in the Drosophila melanogaster genome and varies across cell types and within tissues in D. melanogaster, characteristics of a complex trait. Here, we demonstrate that the trans-interactions at the Malic enzyme (Men) locus are, in fact, transvection as classically defined and are plastic with respect to both genetic background and environment. Using chromosomal inversions, we show that trans-interactions at the Men locus are eliminated by changes in chromosomal architecture that presumably disrupt somatic pairing. We further show that the magnitude of transvection at the Men locus is modified by both genetic background and environment (temperature), demonstrating that transvection is a plastic phenotype. Our results suggest that transvection effects in D. melanogaster are shaped by a dynamic interplay between environment and genetic background. Interestingly, we find that cis-based regulation of the Men gene is more robust to genetic background and environment than trans-based. Finally, we begin to uncover the nonlocal factors that may contribute to variation in transvection overall, implicating Abd-B in the regulation of Men in cis and in trans in an allele-specific and tissue-specific manner, driven by differences in expression of the two genes across genetic backgrounds and environmental conditions.

Date: 2018-05-04

Creator: Maria Tysiachniouk, Laura A. Henry, Machiel Lamers, Jan P.M. van Tatenhove

Access: Open access

How can indigenous communities in illiberal regimes benefit from oil production? This paper compares the experience of two indigenous peoples in the Russian Arctic, the Nenets and the Komi-Izhemtsi, in their quest for environmental protection and the development of benefit-sharing arrangements with Lukoil, a Russian oil company. The Nenets people, recognized by the Russian state as indigenous, are marginalized political actors who identified a route to receiving compensation for loss of land and damage to the environment as well as economic benefits under the auspices of Russian law and Lukoil’s corporate policies. In contrast, the Komi-Izhemtsi, despite indigenous status in global institutions including the United Nations and the Arctic Council, are unrecognized as indigenous domestically and initially received no compensation. Their path to benefit sharing was more challenging as they partnered with local nongovernmental organizations and global environmentalists to pressure Lukoil to sign a benefit-sharing agreement. Ultimately, the comparison illustrates how transnational partnerships can empower indigenous people to gain benefits from natural resource exploitation even in illiberal political systems.

Date: 2018-03-01

Creator: Maria Tysiachniouk, Laura A. Henry, Machiel Lamers, Jan P.M. van Tatenhove

Access: Open access

How can the interests of extractive industries and indigenous communities in the Arctic be balanced through benefit sharing policies? This paper analyses how the international oil consortia of Sakhalin Energy and Exxon Neftegaz Limited (ENL) on Sakhalin Island in Russia have introduced benefit sharing through tripartite partnerships. We demonstrate that the procedural and distributional equity of benefit sharing depend on corporate policies, global standards, pressure from international financial institutions, and local social movements connected in a governance generating network. Sakhalin Energy was profoundly influenced by international financial institutions’ global rules related to environmental and indigenous people's interests. The benefit sharing arrangement that evolved under these influences resulted in enhanced procedural equity for indigenous people, but has not prevented conflict with and within communities. In contrast, ENL was not significantly influenced by international financial institutions. Its more flexible and limited benefit sharing arrangement was shaped predominantly by global corporate policies, pressure from the regional government and the influence of Sakhalin Energy's model. The paper closes with policy recommendations on benefit sharing arrangements between extractive industries and indigenous communities across Arctic states that could be further developed by the Arctic Council Sustainable Development Working Group.

Date: 2021-12-01

Creator: Laura Howells, Laura A. Henry

Access: Open access

Digital authoritarianism threatens the privacy and rights of Internet users worldwide, yet scholarship on this topic remains limited in analytical power and case selection. In this article, we introduce a comprehensive analytical framework to the field of Internet governance and apply it first, briefly, to the well-known case of China and then, in more depth, to the still-understudied Russian case. We identify the extent and relative centralization of Internet governance as well as proactive versus reactive approaches to governance as notable differences between the cases, highlighting variation among digital authoritarians’ governance strategies. We conclude that Russia’s Internet governance model is less comprehensive and consistent than China’s, but its components may be more easily exported to other political systems. We then consider whether recent changes to Russia’s Internet governance suggest that it could converge with the Chinese model over time.

Date: 2014-04-08

Creator: Van N. Tra, Danielle H. Dube

Access: Open access

A substantial obstacle to the existing treatment of bacterial diseases is the lack of specific probes that can be used to diagnose and treat pathogenic bacteria in a selective manner while leaving the microbiome largely intact. To tackle this problem, there is an urgent need to develop pathogen-specific therapeutics and diagnostics. Here, we describe recent evidence that indicates distinctive glycans found exclusively on pathogenic bacteria could form the basis of targeted therapeutic and diagnostic strategies. In particular, we highlight the use of metabolic oligosaccharide engineering to covalently deliver therapeutics and imaging agents to bacterial glycans. © 2014 The Partner Organisations.

Date: 2017-09-01

Creator: G. Serrato Marks, M. LaVigne, T. M. Hill, W. Sauthoff, T. P., Guilderson, E. B. Roark, R. B. Dunbar, T. J. Horner

Access: Open access

Trace elemental ratios preserved in the calcitic skeleton of bamboo corals have been shown to serve as archives of past ocean conditions. The concentration of dissolved barium (Ba ), a bioactive nutrientlike element, is linked to biogeochemical processes such as the cycling and export of nutrients. Recent work has calibrated bamboo coral Ba/Ca, a new Ba proxy, using corals spanning the oxygen minimum zone beneath the California Current System. However, it was previously unclear whether Ba/Ca records were internally reproducible. Here we investigate the accuracy of using laser ablation inductively coupled plasma mass spectrometry for Ba/Ca analyses and test the internal reproducibility of Ba/Ca among replicate radial transects in the calcite of nine bamboo corals collected from the Gulf of Alaska (643–720 m) and the California margin (870–2054 m). Data from replicate Ba/Ca transects were aligned using visible growth bands to account for nonconcentric growth; smoothed data were reproducible within ~4% for eight corals (n = 3 radii/coral). This intracoral reproducibility further validates using bamboo coral Ba/Ca for Ba reconstructions. Sections of the Ba/Ca records that were potentially influenced by noncarbonate bound Ba phases occurred in regions where elevated Mg/Ca or Pb/Ca and coincided with anomalous regions on photomicrographs. After removing these regions of the records, increased Ba/Ca variability was evident in corals between ~800 and 1500 m. These findings support additional proxy validation to understand Ba variability on interannual timescales, which could lead to new insights into deep sea biogeochemistry over the past several centuries. SW SW coral coral SW coral SW

Date: 2006-07-25

Creator: Jason Hill, Erik Nelson, David Tilman, Stephen Polasky, Douglas, Tiffany

Access: Open access

Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels. © 2006 by The National Academy of Sciences of the USA.

Date: 2008-07-01

Creator: Samuel P. Putnam, Cynthia A. Stifter

Access: Open access

Through her theoretical and empirical work, Mary Rothbart has had a profound impact on the scientific understanding of infant and child temperament. This special issue honors her contributions through the presentations of original, contemporary studies relevant to three primary themes in Rothbart's conceptual approach: the expansive scope and empirically-derived structure of temperament, the importance of considering developmental change, and the interplay of reactive and regulatory processes. In addition to summarizing these themes, this introductory article acknowledges the ways Mary has spurred progress in the field through methodological advances, institutional service, and pedagogy. Copyright © 2008 John Wiley & Sons, Ltd.

Date: 2017-06-08

Creator: Henriette Elvang, Callum R.T. Jones, Stephen G. Naculich

Access: Open access

Extensions of the photon and graviton soft theorems are derived in 4D local effective field theories with massless particles of arbitrary spin. We prove that effective operators can result in new terms in the soft theorems at subleading order for photons and subsubleading order for gravitons. The new soft terms are unique, and we provide a complete classification of all local operators responsible for such modifications. We show that no local operators can modify the subleading soft graviton theorem. The soft limits are taken in a manifestly on-locus manner using a complex double deformation of the external momenta. In addition to the new soft theorems, the resulting master formula yields consistency conditions, such as the conservation of electric charge, the Einstein equivalence principle, supergravity Ward identities, and that particles with spin greater than two cannot couple to those with spin less than or equal to two.

Date: 2004-06-01

Creator: Anja Forche, P. T. Magee, B. B. Magee, Georgiana May

Access: Open access

Single-nucleotide polymorphisms (SNPs) are essential tools for studying a variety of organismal properties and processes, such as recombination, chromosomal dynamics, and genome rearrangement. This paper describes the development of a genome-wide SNP map for Candida albicans to study mitotic recombination and chromosome loss. C. albicans is a diploid yeast which propagates primarily by clonal mitotic division. It is the leading fungal pathogen that causes infections in humans, ranging from mild superficial lesions in healthy individuals to severe, life-threatening diseases in patients with suppressed immune systems. The SNP map contains 150 marker sequences comprising 561 SNPs and 9 insertions-deletions. Of the 561 SNPs, 437 were transition events while 126 were transversion events, yielding a transition-to-transversion ratio of 3:1, as expected for a neutral accumulation of mutations. The average SNP frequency for our data set was 1 SNP per 83 bp. The map has one marker placed every 111 kb, on average, across the 16-Mb genome. For marker sequences located partially or completely within coding regions, most contained one or more nonsynonymous substitutions. Using the SNP markers, we identified a loss of heterozygosity over large chromosomal fragments in strains of C. albicans that are frequently used for gene manipulation experiments. The SNP map will be useful for understanding the role of heterozygosity and genome rearrangement in the response of C. albicans to host environments.

Date: 1999-01-01

Creator: Eric Chown

Access: Open access

This article examines the relationship between environmental and cognitive structure. One of the key tasks for any agent interacting in the real world is the management of uncertainty; because of this the cognitive structures which interact with real environments, such as would be used in navigation, must effectively cope with the uncertainty inherent in a constantly changing world. Despite this uncertainty, however, real environments usually afford structure that can be effectively exploited by organisms. The article examines environmental characteristics and structures that enable humans to survive and thrive in a wide range of real environments. The relationship between these characteristics and structures, uncertainty, and cognitive structure is explored in the context of PLAN, a proposed model of human cognitive mapping, and R-PLAN, a version of PLAN that has been instantiated on an actual mobile robot. An examination of these models helps to provide insight into environmental characteristics which impact human performance on tasks which require interaction with the world. Copyright 1999 International Society for Adaptive Behavior.

Date: 2019-10-02

Creator: R. Heather Macdonald, Rachel J. Beane, Eric M.D. Baer, Pamela L. Eddy, Norlene R., Emerson, Jan Hodder, Ellen R. Iverson, John R. McDaris, Kristin O’Connell, Carol J. Ormand

Access: Open access

Faculty play an important role in attracting students to the geosciences, helping them to thrive in geoscience programs, and preparing them for careers. Thus, faculty have the responsibility to work toward broadening participation in the geosciences by implementing equitable and inclusive practices in their teaching and their programs. Faculty professional development that promotes diversity and inclusion is one way to move evidence-based practices into wider use. The adoption of these practices may be accelerated through a professional development diffusion model that amplifies the impacts through the work of faculty change agents. An example of this approach is the SAGE 2YC professional development program, in which faculty change agents learn and practice strategies during workshop sessions, implement changes in their own teaching, and then work in teams to lead workshops in their region under the auspices of the national program. Although this example focuses on two-year colleges, the model is applicable to faculty professional development more broadly. The success of the model is due in large part to a suite of leader-developed workshop sessions and curated resources that change agent teams may select and adapt for the regional workshops they lead. Furthermore, change agents are trusted colleagues, which makes adoption of the evidence-based practices by regional workshop participants more likely. Increased adoption of a change agent approach to faculty development will support the creation and sharing of additional resources, leading to wider diffusion and implementation of inclusive teaching practices.

Date: 2019-02-01

Creator: Stephen G. Warren, Collin S. Roesler, Richard E. Brandt, Mark Curran

Access: Open access

Ice crystals form in supercooled seawater beneath several Antarctic ice shelves; as they rise to the ice-shelf base they scavenge particles from the water and incorporate them into the growing basal ice. The resulting marine ice can be ~100 m thick; it differs from sea ice in that it is clear, desalinated, and bubble-free. Icebergs of marine ice vary in color from blue to green, depending on the nature and abundance of foreign constituents in the seawater that became trapped in the ice as it grew. A red or yellow material (i.e., one that absorbs blue light), in combination with the blue of ice, can shift the wavelength of minimum absorption to green. Previously, dissolved organic carbon (DOC) had been proposed to be responsible for the green color. Subsequent measurements of low DOC values in green icebergs, together with the recent finding of large concentrations of iron in marine ice from the Amery Ice Shelf, suggest that the color of green icebergs is caused more by iron-oxide minerals than by DOC. These icebergs travel great distances from their origin; when they melt they can deliver iron as a nutrient to the Southern Ocean.

Date: 2010-12-01

Creator: Erik Nelson, Heather Sander, Peter Hawthorne, Marc Conte, Driss, Ennaanay, Stacie Wolny, Steven Manson, Stephen Polasky

Access: Open access

Background: As the global human population grows and its consumption patterns change, additional land will be needed for living space and agricultural production. A critical question facing global society is how to meet growing human demands for living space, food, fuel, and other materials while sustaining ecosystem services and biodiversity [1]. Methodology/Principal Findings: We spatially allocate two scenarios of 2000 to 2015 global areal change in urban land and cropland at the grid cell-level and measure the impact of this change on the provision of ecosystem services and biodiversity. The models and techniques used to spatially allocate land-use/land-cover (LULC) change and evaluate its impact on ecosystems are relatively simple and transparent [2]. The difference in the magnitude and pattern of cropland expansion across the two scenarios engenders different tradeoffs among crop production, provision of species habitat, and other important ecosystem services such as biomass carbon storage. For example, in one scenario, 5.2 grams of carbon stored in biomass is released for every additional calorie of crop produced across the globe; under the other scenario this tradeoff rate is 13.7. By comparing scenarios and their impacts we can begin to identify the global pattern of cropland and irrigation development that is significant enough to meet future food needs but has less of an impact on ecosystem service and habitat provision. Conclusions/Significance: Urban area and croplands will expand in the future to meet human needs for living space, livelihoods, and food. In order to jointly provide desired levels of urban land, food production, and ecosystem service and species habitat provision the global society will have to become much more strategic in its allocation of intensively managed land uses. Here we illustrate a method for quickly and transparently evaluating the performance of potential global futures.

Date: 2008-05-01

Creator: Anja Forche, Kevin Alby, Dana Schaefer, Alexander D. Johnson, Judith, Berman, Richard J. Bennett

Access: Open access

Candida albicans has an elaborate, yet efficient, mating system that promotes conjugation between diploid a and α strains. The product of mating is a tetraploid a/α cell that must undergo a reductional division to return to the diploid state. Despite the presence of several "meiosis-specific" genes in the C. albicans genome, a meiotic program has not been observed. Instead, tetraploid products of mating can be induced to undergo efficient, random chromosome loss, often producing strains that are diploid, or close to diploid, in ploidy. Using SNP and comparative genome hybridization arrays we have now analyzed the genotypes of products from the C. albicans parasexual cycle. We show that the parasexual cycle generates progeny strains with shuffled combinations of the eight C. albicans chromosomes. In addition, several isolates had undergone extensive genetic recombination between homologous chromosomes, including multiple gene conversion events. Progeny strains exhibited altered colony morphologies on laboratory media, demonstrating that the parasexual cycle generates phenotypic variants of C. albicans. In several fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, the conserved Spo11 protein is integral to meiotic recombination, where it is required for the formation of DNA double-strand breaks. We show that deletion of SPO11 prevented genetic recombination between homologous chromosomes during the C. albicans parasexual cycle. These findings suggest that at least one meiosis-specific gene has been re-programmed to mediate genetic recombination during the alternative parasexual life cycle of C. albicans. We discuss, in light of the long association of C. albicans with warm-blooded animals, the potential advantages of a parasexual cycle over a conventional sexual cycle. © 2008 Forche et al.

Date: 2019-01-01

Creator: Jack R. Bateman, David J. Anderson

Access: Open access

Date: 2014-01-01

Creator: Jarrod Olson, Daniel F. Stone

Access: Open access

U.S. college football’s traditional bowl system, and lack of a postseason play-off tournament, has been controversial for years. The conventional wisdom is that a play-off would be a more fair way to determine the national champion, and more fun for fans to watch. The colleges finally agreed to begin a play-off in the 2014-2015 season, but with just four teams, and speculation continues that more teams will be added soon. A subtle downside to adding play-off teams is that it reduces the significance of regular season games.We use the framework of Ely, Frankel, and Kamenica (in press) to directly estimate the utility fans would get from this significance, that is, utility from suspense, under a range of play-off scenarios. Our results consistently indicate that play-off expansion causes a loss in regular season suspense utility greater than the gain in the postseason, implying the traditional bowl system (two team play-off) is suspense-optimal. We analyze and discuss implications for TV viewership and other contexts.

Date: 2002-12-22

Creator: Amy S. Johnson, Olaf Ellers, Jim Lemire, Melissa Minor, Holly A., Leddy

Access: Open access

Date: 2007-01-01

Creator: Michael W. Otto, Teresa M. Leyro, Kelly Christian, Christen M. Deveney, Hannah, Reese, Mark H. Pollack, Scott P. Orr

Access: Open access

Studies using fear-conditioning paradigms have found that anxiety patients are more conditionable than individuals without these disorders, but these effects have been demonstrated inconsistently. It is unclear whether these findings have etiological significance or whether enhanced conditionability is linked only to certain anxiety characteristics. To further examine these issues, the authors assessed the predictive significance of relevant subsyndromal characteristics in 72 healthy adults, including measures of worry, avoidance, anxious mood, depressed mood, and fears of anxiety symptoms (anxiety sensitivity), as well as the dimensions of Neuroticism and Extraversion. Of these variables, the authors found that the combination of higher levels of subsyndromal worry and lower levels of behavioral avoidance predicted heightened conditionability, raising questions about the etiological significance of these variables in the acquisition or maintenance of anxiety disorders. In contrast, the authors found that anxiety sensitivity was more linked to individual differences in orienting response than differences in conditioning per se. © 2007 Sage Publications.

Date: 2008-10-13

Creator: Thomas Pietraho

Access: Open access

We examine the partition of a finite Coxeter group of type B into cells determined by a weight function L. The main objective of these notes is to reconcile Lusztig's description of constructible representations in this setting with conjectured combinatorial descriptions of cells.

Date: 2008-03-28

Creator: Francisco Barceló, José A. Periáñez, Erika Nyhus

Access: Open access

This study aimed to clarify the neural substrates of behavioral switch and restart costs in intermittently instructed task-switching paradigms. Event-related potentials (ERPs) were recorded while participants were intermittently cued to switch or repeat their categorization rule (Switch task), or else they performed two perceptually identical control conditions (NoGo and Oddball). The three tasks involved different task-sets with distinct stimulus-response associations in each, but identical visual stimulation, consisting of frequent colored shapes (p = 0.9) and randomly interspersed infrequent black shapes (p = 0.1; '+' and 'x' symbols). Behavioral restart costs were observed in the first target responses following all black shapes in the Switch and NoGo tasks - but not in the Oddball task - and corresponded with enhanced fronto-centrally distributed early cue-locked P3 activity (peak latency 325-375 ms post-cue onset at the vertex). In turn, behavioral switch costs were associated with larger late cue-locked P3 amplitudes in the Switch task only (peak latency 400-450 ms post-cue onset at mid-parietal sites). Together with our information theoretical estimations, ERP results suggested that restart and switch costs indexed two neural mechanisms related to the preparatory resolution of uncertainty: (1) the intermittent re-activation of task-set information, and (2) the updating of stimulus-response mappings within an active task set, as indexed by early and late cue-locked P3 activations, respectively. In contrast, target-locked P3 activations reflected a functionally distinct mechanism related to the implementation of task-set information. We conclude that task-switching costs consist of both switch-specific and switch-unspecific processes during the preparation and execution stages of task performance. © 2008 Barceló, Periáñez and Nyhus.

Date: 2012-05-08

Creator: Bruce D. Kohorn, Susan L. Kohorn

Access: Open access

The wall-associated kinases, WAKs, are encoded by five highly similar genes clustered in a 30-kb locus in Arabidopsis. These receptor-like proteins contain a cytoplasmic serine threonine kinase, a transmembrane domain, and a less conserved region that is bound to the cell wall and contains a series of epidermal growth factor repeats. Evidence is emerging that WAKs serve as pectin receptors, for both short oligogalacturonic acid fragments generated during pathogen exposure or wounding, and for longer pectins resident in native cell walls. This ability to bind and respond to several types of pectins correlates with a demonstrated role for WAKs in both the pathogen response and cell expansion during plant development. © 2012 Kohorn and Kohorn.

Date: 2003-01-01

Creator: Jennifer Taback, Kevin Whyte

Access: Open access

Date: 2011-12-01

Creator: Sean Cleary, Susan Hermiller, Melanie Stein, Jennifer Taback

Access: Open access

We give the first examples of groups which admit a tame combing with linear radial tameness function with respect to any choice of finite presentation, but which are not minimally almost convex on a standard generating set. Namely, we explicitly construct such combings for Thompson's group F and the Baumslag-Solitar groups BS(1, p) with p ≥ 3. In order to make this construction for Thompson's group F, we significantly expand the understanding of the Cayley complex of this group with respect to the standard finite presentation. In particular we describe a quasigeodesic set of normal forms and combinatorially classify the arrangements of 2-cells adjacent to edges that do not lie on normal form paths. © 2010 Springer-Verlag.

Date: 1994-07-01

Creator: Tracy A. Smith, Bruce D. Kohorn

Access: Open access

The apparatus that permits protein translocation across the internal thylakoid membranes of chloroplasts is completely unknown, even though these membranes have been the subject of extensive biochemical analysis. We have used a genetic approach to characterize the translocation of Chlamydomonas cytochrome f, a chloroplast-encoded protein that spans the thylakoid once. Mutations in the hydrophobic core of the cytochrome f signal sequence inhibit the accumulation of cytochrome f, lead to an accumulation of precursor, and impair the ability of Chlamydomonas cells to grow photosynthetically. One hydrophobic core mutant also reduces the accumulation of other thylakoid membrane proteins, but not those that translocate completely across the membrane. These results suggest that the signal sequence of cytochrome f is required and is involved in one of multiple insertion pathways. Suppressors of two signal peptide mutations describe at least two nuclear genes whose products likely describe the translocation apparatus, and selected second- site chloroplast suppressors further define regions of the cytochrome f signal peptide.

Date: 1991-06-15

Creator: Tracy A. Smith, Bruce D. Kohorn

Access: Open access

We have developed a simple genetic selection that could be used to isolate eukaryotic cDNAs encoding proteases that cleave within a defined amino acid sequence. The selection was developed by using the transcription factor GAL4 from Saccharomyces cerevisiae as a selectable marker, a cloned protease from tobacco etch virus (TEV), and an 18-amino acid TEV protease target sequence. In yeast, TEV protease cleaves its target even when the target is fused to internal regions of the GAL4 protein. This cleavage separates the DNA binding domain from the transcription activation domain of GAL4, rendering it transcriptionally inactive. The proteolytic cleavage can be detected phenotypically by the inability of cells to metabolize galactose. Cells expressing the TEV protease can also be selected on the suicide substrate 2-deoxygalactose. DNA binding studies show that the TEV protease decreases the activity of the GAL4/target fusion protein. Because another protease target sequence of 55 amino acids can be inserted into GAL4 without any loss of transcriptional activity, this assay offers the opportunity to use high-efficiency cDNA cloning and expression vectors to select coding sequences of other proteases from various species. The assay could also be used to help define both target specificities and functional domains of proteases.

Date: 2012-08-01

Creator: Jack R. Bateman, Justine E. Johnson, Melissa N. Locke

Access: Open access

Studies from diverse systems have shown that distinct interchromosomal interactions are a central component of nuclear organization. In some cases, these interactions allow an enhancer to act in trans, modulating the expression of a gene encoded on a separate chromosome held in close proximity. Despite recent advances in uncovering such phenomena, our understanding of how a regulatory element acts on another chromosome remains incomplete. Here, we describe a transgenic approach to better understand enhancer action in trans in Drosophila melanogaster. Using phiC31-based recombinase-mediated cassette exchange (RMCE), we placed transgenes carrying combinations of the simple enhancer GMR, a minimal promoter, and different fluorescent reporters at equivalent positions on homologous chromosomes so that they would pair via the endogenous somatic pairing machinery of Drosophila. Our data demonstrate that the enhancer GMR is capable of activating a promoter in trans and does so in a variegated pattern, suggesting stochastic interactions between the enhancer and the promoter when they are carried on separate chromosomes. Furthermore, we quantitatively assessed the impact of two concurrent promoter targets in cis and in trans to GMR, demonstrating that each promoter is capable of competing for the enhancer's activity, with the presence of one negatively affecting expression from the other. Finally, the single-cell resolution afforded by our approach allowed us to show that promoters in cis and in trans to GMR can both be activated in the same nucleus, implying that a single enhancer can share its activity between multiple promoter targets carried on separate chromosomes. © 2012 by the Genetics Society of America.

Date: 2006-06-01

Creator: Bruce D. Kohorn, Masaru Kobayashi, Sue Johansen, Henry Perry Friedman, Andy, Fischer, Nicole Byers

Access: Open access

The Arabidopsis thaliana wall-associated kinases (WAKs) bind to pectin with an extracellular domain and also contain a cytoplasmic protein kinase domain. WAKs are required for cell elongation and modulate sugar metabolism. This work shows that in leaf protoplasts a WAK1-GFP fusion protein accumulates in a cytoplasmic compartment that contains pectin. The WAK compartment contains markers for the Golgi, the site of pectin synthesis. The migration of WAK1-GFP to the cell surface is far slower than that of a cell surface receptor not associated with the cell wall, is influenced by the presence of fucose side chains on one or more unidentified molecules that might include pectin, and is dependent upon cellulose synthesis on the plasma membrane. WAK is crosslinked into a detergent-insoluble complex within the cytoplasmic compartment before it appears on the cell surface, and this is independent of fucose modification or cellulose synthesis. Thus, the assembly and crosslinking of WAKs may begin at an early stage within a cytoplasmic compartment rather than in the cell wall itself, and is coordinated with synthesis of surface cellulose.

Date: 2021-07-01

Creator: Alan Hastings, Karen C. Abbott, Kim Cuddington, Tessa B. Francis, Ying Cheng, Lai, Andrew Morozov

Access: Open access

There is a growing recognition that ecological systems can spend extended periods of time far away from an asymptotic state, and that ecological understanding will therefore require a deeper appreciation for how long ecological transients arise. Recent work has defined classes of deterministic mechanisms that can lead to long transients. Given the ubiquity of stochasticity in ecological systems, a similar systematic treatment of transients that includes the influence of stochasticity is important. Stochasticity can of course promote the appearance of transient dynamics by preventing systems from settling permanently near their asymptotic state, but stochasticity also interacts with deterministic features to create qualitatively new dynamics. As such, stochasticity may shorten, extend or fundamentally change a system's transient dynamics. Here, we describe a general framework that is developing for understanding the range of possible outcomes when random processes impact the dynamics of ecological systems over realistic time scales. We emphasize that we can understand the ways in which stochasticity can either extend or reduce the lifetime of transients by studying the interactions between the stochastic and deterministic processes present, and we summarize both the current state of knowledge and avenues for future advances.

Date: 2021-07-01

Creator: Vadim Khaitov, Julia Marchenko, Marina Katolikova, Risto Väinölä, Sarah E., Kingston, David B. Carlon, Michael Gantsevich, Petr Strelkov

Access: Open access

Cryptic and hybridizing species may lack diagnostic taxonomic characters leaving researchers with semi-diagnostic ones. Identification based on such characters is probabilistic, the probability of correct identification depending on the species composition in a mixed population. Here we test the possibilities of applying a semi-diagnostic conchological character for distinguishing two cryptic species of blue mussels, Mytilus edulis and M. trossulus. These ecologically, stratigraphically and economically important molluscs co-occur and hybridize in many areas of the North Atlantic and the neighboring Arctic. Any cues for distinguishing them in sympatry without genotyping would save much research effort. Recently these species have been shown to statistically differ in the White Sea, where a simple character of the shell was used to distinguish two mussel morphotypes. In this paper, we analyzed the associations between morphotypes and species-specific genotypes based on an abundant material from the waters of the Kola Peninsula (White Sea, Barents Sea) and a more limited material from Norway, the Baltic Sea, Scotland and the Gulf of Maine. The performance of the “morphotype test” for species identification was formally evaluated using approaches from evidence-based medicine. Interspecific differences in the morphotype frequencies were ubiquitous and unidirectional, but their scale varied geographically (from 75% in the White Sea to 15% in the Baltic Sea). In addition, salinity-related variation of this character within M. edulis was revealed in the Arctic Barents Sea. For every studied region, we established relationships between the proportions of the morphotypes in the populations as well as between the proportions of the morphotypes in samples and the probabilities of mussels of different morphotypes being M. trossulus and M. edulis. We provide recommendations for the application of the morphotype test to mussels from unstudied contact zones and note that they may apply equally well to other taxa identified by semi-diagnostic traits.