bluuebunny/crossref_metadata_2025 huggingface dataset:
N‐Acetyl lysyl‐tRNA synthetases evolved by a CcdB‐based selection possess N‐acetyl lysine specificity in vitro and in vivo
Authors: Umehara Takuya , Kim Jihyo , Lee Sangsik , Guo Li-Tao , Söll Dieter , Park Hee-Sung
Published: January 2012

Posttranslational modifications play a crucial role in modulating protein structure and function. Genetic incorporation of unnatural amino acids into a specific site of a protein facilitates the systematic study of protein modifications including acetylation. We here report the directed evolution of pyrrolysyl‐tRNA synthetase (PylRS) from Methanosarcina mazei to create N‐acetyl lysyl‐tRNA synthetases (AcKRSs) using a new selection system based on the killing activity of the toxic ccdB gene product. The amino acid specificity of these and of published [1,2] AckRSs was tested in vitro and in vivo, and the enzyme‐kinetic properties of the AckRSs were evaluated for the first time.
OIT3 deficiency impairs uric acid reabsorption in renal tubule
Authors: Yan Bing , Zhang Zhuang-Zhuang , Huang Li-Yu , Shen Hai-Lian , Han Ze-Guang
Published: January 2012

The oncoprotein induced transcript 3 (OIT3), also named liver‐specific zona pellucida domain‐containing protein (LZP), has been shown to be expressed in kidney, and was confirmed to interact with the Tamm–Horsfall glycoprotein (THP). However, the function of OIT3 in kidney remains unclear. In this study we found that serum uric acid level of Oit3 null mice was significantly lower than that in wild type controls, whereas the excretion of uric acid in urine increased in the mutant mouse. Significantly, the excretion of THP in urine also increased while renal THP decreased in Oit3 null mice. Our data suggest that OIT3 could maintain urate homeostasis by regulating the excretion and reabsorption of uric acid in renal tubule via cooperating with THP.
Smad‐mediated regulation of microRNA biosynthesis
Authors: Blahna Matthew T. , Hata Akiko
Published: January 2012

microRNAs (miRNAs) are small non‐coding RNAs conserved in metazoans. Depletion of miRNAs results in embryonic lethality, suggesting they are essential for embryogenesis. Similarly, pathways induced by growth factors of the transforming growth factor β (TGF‐β) superfamily control cell growth, differentiation, and development. Recently Smad proteins, the signal transducers of the TGF‐β pathway, were found to regulate miRNA expression, which, in turn, affects expression of numerous proteins. Smads modulate miRNA expression through both transcriptional and post‐transcriptional mechanisms illustrating the complexity of gene regulation by TGF‐β. In this chapter we summarize the current knowledge of mechanisms underlying Smad‐mediated regulation of miRNA biogenesis.
A change in the sensitivity of elongation factor G to oxidation protects photosystem II from photoinhibition in Synechocystis sp. PCC 6803
Authors: Ejima Kayoko , Kawaharada Tomoko , Inoue Shuhei , Kojima Kouji , Nishiyama Yoshitaka
Published: January 2012

The repair of photosystem II (PSII) after photodamage is particularly sensitive to oxidative stress and inhibition of such repair is associated with the oxidation of specific cysteine residues in elongation factor G (EF‐G), a key translation factor, in the cyanobacterium Synechocystis sp. PCC 6803. Expression of mutated EF‐G with a target cysteine residue replaced by serine in Synechocystis resulted in the protection of PSII from photoinhibition. This protection was attributable to the enhanced repair of PSII via acceleration of the synthesis of the D1 protein, which might have been due to reduced sensitivity of protein synthesis to oxidative stress.
Use of Kikume green–red fusions to study the influence of pharmacological chaperones on trafficking of G protein‐coupled receptors
Authors: Ridelis Ingrid , Schmidt Antje , Teichmann Anke , Furkert Jens , Wiesner Burkhard , Schülein Ralf
Published: January 2012

In this study we demonstrate that the photoconvertible monomeric Kikume green–red (mKikGR) protein is suitable to study trafficking of G protein‐coupled receptors. Taking mKikGR‐tagged mutants of the vasopressin V2 receptor (V2R) as models, we analyzed whether the V2R‐specific pharmacological chaperone SR121463B influences receptor folding on a co‐ or post‐translational level. Misfolded mKikGR‐tagged V2Rs were completely photoconverted in the early secretory pathway yielding a red receptor population (already synthesized receptors) and an arising green receptor population (newly synthesized receptors). Trafficking of both receptor populations could be rescued by treatment with SR121463B demonstrating that the substance can act co‐ and post‐translationally.
Controls, service type and perceived supplier performance in interfirm service exchanges
Authors: Stouthuysen Kristof , Slabbinck Hendrik , Roodhooft Filip
Published: January 2012

Control offers a critical differentiator between successful and failed interfirm service exchanges. The application of informal control to improve supplier performance has been well established, but the effect of formal control appears profoundly equivocal. This study proposes that the actual effect of formal control depends on its mode (output vs. behavior) and its relationship with the service type (mass vs. professional) and informal control. With survey data from 252 service buying organizations, the results indicate that output control interacts with service type to determine perceived supplier performance (PSP). Buyers’ reliance on high output control has a positive effect on PSP in mass service exchanges; this effect becomes negative in professional service exchanges. The effect of the interaction of behavior control and service type also depends on the presence of informal control. Buyers’ reliance on high behavior control exerts a more positive effect on PSP in professional service exchanges than in mass service exchanges, but only in the presence of informal control. These findings have key implications for both theory and practice.
Primärprävention von sturzbedingten Hüftfrakturen bei Bewohnern von Pflegeheimen in Bayern
Authors: Rapp Kilian , König Hans-Helmut , Becker Clemens
Published: January 2012

Einleitung

Das hier vorgestellte Projekt untersuchte, inwieweit ein landesweit angelegtes Sturzpräventionsprogramms in Pflegeheimen die Inzidenz hüftnaher Frakturen verminderte, welche Kosten damit verbunden waren und welche Beteiligungsraten am Trainingsprogramm vorlagen.
Computational Identification of Sweet Wormwood (Artemisia Annua) microRNA and Their mRNA Targets
Authors: Pani Alok , Mahapatra Rajani Kanta , Behera Niranjan , Naik Pradeep Kumar
Published: January 2012

Despite its efficacy against malaria, the relatively low yield (0.01%-0.8%) of artemisinin in Artemisia annua is a serious limitation to the commercialization of the drug. A better understanding of the biosynthetic pathway of artemisinin and its regulation by both exogenous and endogenous factors is essential to improve artemisinin yield. Increasing evidence has shown that microRNAs (miRNAs) play multiple roles in various biological processes. In this study, we used previously known miRNAs from Arabidopsis and rice against expressed sequence tag (EST) database of A. annua to search for potential miRNAs and their targets in A. annua. A total of six potential miRNAs were predicted, which belong to the miR414 and miR1310 families. Furthermore, eight potential target genes were identified in this species. Among them, seven genes encode proteins that play important roles in artemisinin biosynthesis, including HMG-CoA reductase (HMGR), amorpha-4,11-diene synthase (ADS), farnesyl pyrophosphate synthase (FPS) and cytochrome P450. In addition, a gene coding for putative AINTEGUMENTA, which is involved in signal transduction and development, was also predicted as one of the targets. This is the first in silico study to indicate that miRNAs target genes encoding enzymes involved in artemisinin biosynthesis, which may help to understand the miRNA-mediated regulation of artemisinin biosynthesis in A. annua.
Representability of derived stacks
Authors: Pridham J.P.
Published: January 2012

Lurie's representability theorem gives necessary and sufficient conditions for a functor to be an almost finitely presented derived geometric stack. We establish several variants of Lurie's theorem, making the hypotheses easier to verify for many applications. Provided a derived analogue of Schlessinger's condition holds, the theorem reduces to verifying conditions on the underived part and on cohomology groups. Another simplification is that functors need only be defined on nilpotent extensions of discrete rings. Finally, there is a pre-representability theorem, which can be applied to associate explicit geometric stacks to dg-manifolds and related objects.
Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects
Authors: Theuwissen Elke , Cranenburg Ellen C. , Knapen Marjo H. , Magdeleyns Elke J. , Teunissen Kirsten J. , Schurgers Leon J. , Smit Egbert , Vermeer Cees
Published: January 2012

Vitamin K is required for the carboxylation of Gla-proteins in the liver (coagulation factors) and extra-hepatic tissues, such as bone (osteocalcin, OC), and arterial wall (matrix Gla-protein, MGP). Although the coagulation factors are essentially fully carboxylated under normal conditions, 10–40 % of OC and MGP remains undercarboxylated. We were therefore interested to study the dose–response effects of extra intake of menaquinones on the carboxylation of the extra-hepatic Gla-proteins. A total of forty-two healthy Dutch men and women aged between 18 and 45 years were randomised into seven groups to receive: placebo capsules or menaquinone-7 (MK-7) capsules at a daily dose of 10, 20, 45, 90, 180 or 360 μg. Circulating uncarboxylated OC (ucOC), carboxylated OC (cOC) and desphospho-uncarboxylated MGP were measured by ELISA. The ucOC:cOC ratio was calculated from circulating ucOC and cOC values. Endogenous thrombin potential and peak height were determined by calibrated automated thrombography. To increase the statistical power, we collapsed the treatment groups into three dosage groups: placebo, low-dose supplementation (doses below RDA, Commission Directive 2008/100/EC), and high-dose supplementation (doses around RDA, Commission Directive 2008/100/EC). MK-7 supplementation at doses in the order of the RDA (Commission Directive 2008/100/EC) increased the carboxylation of circulating OC and MGP. No adverse effects on thrombin generation were observed. Extra MK-7 intake at nutritional doses around the RDA (Commission Directive 2008/100/EC) improved the carboxylation of the extra-hepatic vitamin K-dependent proteins. Whether this improvement contributes to public health, i.e. increasing the protection against age-related diseases needs further investigation in specifically designed intervention trials.
Lab support for strong reciprocity is weak: Punishing for reputation rather than cooperation
Authors: Shaw Alex , Santos Laurie
Published: January 2012

Strong reciprocity is not the only account that can explain costly punishment in the lab; it can also be explained by reputation-based accounts. We discuss these two accounts and suggest what kinds of evidence would support the two different alternatives. We conclude that the current evidence favors a reputation-based account of costly punishment.
Parasite stress, ethnocentrism, and life history strategy
Authors: Figueredo Aurelio José , Gladden Paul Robert , Black Candace Jasmine
Published: January 2012

Fincher & Thornhill (F&T) present a compelling argument that parasite stress underlies certain cultural practices promoting assortative sociality. However, we suggest that the theoretical framework proposed is limited in several ways, and that life history theory provides a more explanatory and inclusive framework, making more specific predictions about the trade-offs faced by organisms in the allocation of bioenergetic and material resources.
The evolution and development of human social systems requires more than parasite-stress avoidance explanation
Authors: Grotuss Jason
Published: January 2012

Fincher & Thornhill (F&T) present a model of in-group assortative sociality resulting from differing levels of parasite-stress in differing geographical locations in the United States and the world. Their model, while compelling, overlooks some important issues, such as mutualistic associations with parasites that are beneficial to humans and how some religious practices increase parasite risk.
Coping with germs and people: Investigating the link between pathogen threat and human social cognition
Authors: Navarrete Carlos David
Published: January 2012

Group assortative biases are stronger in regions where pathogen stress has been historically prevalent. Pushing the logic of this approach, extensions should include investigations of how cultural norms related to prosociality and relational striving may also covary with regional pathogen stress. Likewise, the pan-specific observation that diseased animals show decreased motor activity to facilitate recovery suggests that norms relevant to sickness behaviors may also vary as a function of regional parasite stress.
Experiments combining communication with punishment options demonstrate how individuals can overcome social dilemmas
Authors: Ostrom Elinor
Published: January 2012

Guala raises important questions about the misinterpretation of experimental studies that have found that subjects engage in costly punishment. Instead of positing that punishment is the solution for social dilemmas, earlier research posited that when individuals facing a social dilemma agreed on their own rules and used graduated sanctions, they were more likely to have robust solutions over time.
Parasite stress is not so critical to the history of religions or major modern group formations
Authors: Atran Scott
Published: January 2012

Fincher & Thornhill's (F&T's) central hypothesis is that strong in-group norms were formed in part to foster parochial social alliances so as to enable cultural groups to adaptively respond to parasite stress. Applied to ancestral hominid environments, the story fits with evolutionary theory and the fragmentary data available on early hominid social formations and their geographical distributions. Applied to modern social formations, however, the arguments and inferences from data are problematic.
Costs and benefits in hunter-gatherer punishment
Authors: Boehm Christopher
Published: January 2012

Hunter-gatherer punishment involves costs and benefits to individuals and groups, but the costs do not necessarily fit with the assumptions made in models that consider punishment to be altruistic – which brings in the free-rider problem and the problem of second-order free-riders. In this commentary, I present foragers' capital punishment patterns ethnographically, in the interest of establishing whether such punishment is likely to be costly; and I suggest that in many cases abstentions from punishment that might be taken as defections by free-riders are actually caused by social-structural considerations rather than being an effect of free-rider genes. This presentation of data supplements the ethnographic analysis provided by Guala.
Russian Enterprise, Bengali Theatre, and the Machinations of the East India Company
Authors: Senelick Laurence
Published: January 2012

Was the father of Bengali theatre a Russian? Or were the brief adventures in India of Gerasim Stepanovich Lebedev (1749–1817) ‘a mere blip on the screen of Bengali performance history’? Already widely travelled in Europe, Lebedev, influenced by the then current belief that India was the cradle of civilization, arrived in Madras in 1785 during the virtual hegemony of the East India Company in the sub-continent. Inspired by his attempts to master the ancient Sanskrit tongue, he eventually set up a Bengali company in opposition to the New Playhouse in Calcutta, which staged English plays for audiences of colonists. Initial success was tempered when Lebedev's company found itself the target of attack from the Playhouse, and subject to continuous legal harassment. Forced to take flight from his supposed creditors, Lebedev found security only when, under the more tolerant regime which followed the accession of Tsar Alexander I in 1801, he returned to his native land, where he laid the foundations for the scientific study of India in Russia. Laurence Senelick here traces the many ups and downs of Lebedev's career, and argues that ‘his theatrical activities are a cynosure for the controlling urges of his age’.
The Diva and the Demon: Ingmar Bergman Directs The Rose Tattoo
Authors: Gindt Dirk
Published: January 2012

In this article Dirk Gindt discusses Ingmar Bergman's 1951 production of Tennessee Williams's The Rose Tattoo in the small Swedish town of Norrköping, demonstrating how Bergman methodically ignored the tragicomic nature of the play in order to develop and exaggerate its comic and grotesque elements. After extensive cuts and alterations in the script, the character Serafina delle Rose became even more overpowering than in the original text and dominated the action from beginning to end. Karin Kavli, a leading lady in Swedish post-war theatre and a frequent collaborator with Bergman, played the character not as a mourning widow but as a possessed disciple of Dionysus in an unabashedly entertaining and sexualized production which, despite reservations from critics, became a success with audiences. Dirk Gindt now works as a Postdoctoral Research Fellow at Stockholm University. He is co-editor of Fashion: an Interdisciplinary Reflection (Stockholm: Raster, 2009), and has published numerous articles in journals such as Nordic Theatre Studies, The Tennessee Williams Annual Review, Theatre Survey, and Fashion Studies, as well as chapters in edited volumes. He is the editor-in-chief of Lambda Nordica: Journal for GLBT-Studies, for which he has edited a special issue on masculinities (2008) and a double issue on queer fashion (2009).
Remembering Ewan MacColl: the Agency of Writing and the Creation of a Participatory Popular Culture
Authors: Holland Owen
Published: January 2012

In this article Owen Holland examines Ewan MacColl's early work in agit-prop theatre and his later activity as a songwriter, performer, and collector in the second British folk revival. He argues that his experience in the theatre provides a necessary route into understanding the problems of his later work – and what unites the ‘two halves’ is MacColl's consistent sense of the function of art (specifically his preferred media of drama and song) within a wider politico-cultural praxis. There is a contradiction in MacColl's praxis, however, in that while he wanted to create a popular culture of participation, his dogmatic textual strategies and exclusivist tendencies often became coercive enough to undermine his intentions. The discussion of MacColl's writing is situated within a critique of the problems that appear in his wider praxis, and Holland concludes by asserting that MacColl's agency as a writer was achieved through the development of a performance-oriented aesthetic. Owen Holland is a PhD candidate in the English Faculty at the University of Cambridge, affiliated to St Catharine's College. His research focuses on utopian fiction in the late nineteenth century, with a particular interest in William Morris.
Verbs and attention to relational roles in English and Tamil
Authors: SETHURAMAN NITYA , SMITH LINDA B.
Published: January 2012

English-learning children have been shown to reliably use cues from argument structure in learning verbs. However, languages pair overtly expressed arguments with verbs to varying extents, raising the question of whether children learning all languages expect the same, universal mapping between arguments and relational roles. Three experiments examined this question by asking how strongly early-learned verbs by themselves,without their corresponding explicitly expressed arguments, point to ‘conceptual arguments’ – the relational roles in a scene. Children aged two to four years and adult speakers of two languages that differ structurally in terms of whether the arguments of a verb are explicitly expressed more (English) or less (Tamil) frequently were compared in their mapping of verbs, presented without any overtly expressed arguments, to a range of scenes. The results suggest different developmental trajectories for language learners, as well as different patterns of adult interpretation, and offer new ways of thinking about the nature of verbs cross-linguistically.
Mothers' frontal EEG asymmetry in response to infant emotion states and mother–infant emotional availability, emotional experience, and internalizing symptoms
Authors: Killeen Lauren A. , Teti Douglas M.
Published: January 2012

This study examined the links between mothers' frontal EEG asymmetry at rest and during videos of their 5- to 8-month-old infants expressing three emotion states (joy, anger/distress, and neutral interest), mother–infant emotional availability (EA) in the home, mothers' depressive and anxious symptoms, and mothers' emotional experience in response to infant emotion cues. Greater relative right frontal activity at rest was associated with greater maternal anxiety, but was unrelated to EA or mother-reported emotional experience in response to infant emotion cues. A shift toward greater relative right frontal activation in response to infant emotional stimuli was associated with lower maternal anxiety, greater mother–infant EA, and mothers' experience of sadness, concern, irritability, and the absence of joy in response to seeing their own infant in distress. These findings suggest that mothers' in the moment empathetic responding to their infant's emotions, indexed by a shift in frontal EEG asymmetry in response to infant emotional displays, is related to mother–infant EA in the home. Implications for conceptualizing parenting risk are discussed.
Emotional availability, attachment, and intervention in center-based child care for infants and toddlers
Authors: Biringen Zeynep , Altenhofen Shannon , Aberle Jennifer , Baker Megan , Brosal Aubrey , Bennett Sera , Coker Ellen , Lee Carly , Meyer Beatrice , Moorlag Albertha , Swaim Randall
Published: January 2012

According to data from the 1997 NICHD Study of Child Care, center-based child care can have deleterious effects on children's social–emotional development. We hypothesized that training child care professionals to develop positive relationships with children in their care would improve the quality of center-based child care. Thirty-three professional caregiver–child pairs participated in the intervention group and 24 professional caregiver–child pairs were assigned to a care as usual comparison group. The intervention consisted of an informational and a practice component with an emotional availability (EA) coach. The infants and toddlers (ages 11 to 23 months) in the classrooms were enrolled in the project only if they spent at least 20 hr per week in center-based care. The measures included were (a) the EA Scales, (b) the Attachment Q-Sort, and (c) the Classroom Interaction Scale. The intervention group professional caregiver–child relationships showed improvements on the EA Scales, Attachment Q-Sort, and the Classroom Interaction Scale from pre- to posttest, compared to the comparison group, who showed some decrements over a comparable period of time.
Postadoption parenting and socioemotional development in postinstitutionalized children
Authors: Garvin Melissa C. , Tarullo Amanda R. , Van Ryzin Mark , Gunnar Megan R.
Published: January 2012

Children adopted from institutions (e.g., orphanages) overseas are at increased risk of disturbances in social relationships and social understanding. Not all postinstitutionalized children exhibit these problems, although factors like the severity of deprivation and duration of deprivation increase their risk. To date, few studies have examined whether postadoption parenting might moderate the impact of early adverse care. Three groups were studied: postinstitutionalized and foster care children both adopted internationally and nonadopted children reared in their families of origin. The Emotional Availability (EA) Scales were assessed at 18 months in parent–child dyads. Parent emotional availability was found to predict two aspects of social functioning shown in previous studies to be impaired in postinstitutionalized children. Specifically, EA positively correlated with emotion understanding at 36 months; in interaction with initiation of joint attention at 18 months and group, it predicted indiscriminate friendliness as scored from a parent attachment interview at 30 months. Among the postinstitutionalized children but not among the children in other groups, higher EA scores reduced the negative association between initiation of joint attention and indiscriminate friendliness, thus suggesting that parenting quality may moderate the effects of early institutional deprivation.
The integration of emotional availability into a developmental psychopathology framework: Reflections on the Special Section and future directions
Authors: Biringen Zeynep , Easterbrooks M. Ann
Published: January 2012

We appreciate both the opportunity to co-edit this Special Section of Development and Psychopathology and the thoughtful commentaries provided by Marjorie Beeghly, Marc Bornstein, Robert Emde, and David Oppenheim. Their commentaries review historical perspectives, provide new insights, and suggest future horizons for the study of emotional availability (EA) within a developmental psychopathology framework. Along with the collection of empirical studies in this Special Section, they begin to chart a course for further growth and integration of EA into the field of developmental psychopathology. Taking stock of the research on EA, we realize that there is now a sufficient corpus to suggest that research focusing on this construct, as operationalized by the EA Scales (Biringen, Robinson, & Emde, 1998) is entering a more mature phase of inquiry. In the last 14 years, research on EA, including several special journal issues on the topic (see Biringen & Easterbrooks, 2008; Easterbrooks & Biringen, 2000, 2005, 2009), has explored the methodological concerns, reliability, and validity of the EA Scales and application across different samples and ages. This “critical mass” of knowledge (more than 100 peer-reviewed publications) supports the current focus on asking incisive questions for the field of developmental psychopathology (Cicchetti & Toth, 1995, 2009).
Sluggish vagal brake reactivity to physical exercise challenge in children with selective mutism
Authors: Heilman Keri J. , Connolly Sucheta D. , Padilla Wendy O. , Wrzosek Marika I. , Graczyk Patricia A. , Porges Stephen W.
Published: January 2012

Cardiovascular response patterns to laboratory-based social and physical exercise challenges were evaluated in 69 children and adolescents, 20 with selective mutism (SM), to identify possible neurophysiological mechanisms that may mediate the behavioral features of SM. Results suggest that SM is associated with a dampened response of the vagal brake to physical exercise that is manifested as reduced reactivity in heart rate and respiration. Polyvagal theory proposes that the regulation of the vagal brake is a neurophysiological component of an integrated social engagement system that includes the neural regulation of the laryngeal and pharyngeal muscles. Within this theoretical framework, sluggish vagal brake reactivity may parallel an inability to recruit efficiently the structures involved in speech. Thus, the findings suggest that dampened autonomic reactivity during mobilization behaviors may be a biomarker of SM that can be assessed independent of the social stimuli that elicit mutism.
International fuel tax assessment: an application to Chile
Authors: Parry Ian , Strand Jon
Published: January 2012

Gasoline and diesel fuel are heavily taxed in many developed and some emerging and developing countries. Outside the United States and Europe, however, there has been little attempt to quantify the external costs of vehicle use, so policy makers lack guidance on whether prevailing tax rates are economically efficient. This paper develops a general approach for estimating motor vehicle externalities, and hence corrective taxes on gasoline and diesel, based on pooling local data with extrapolations from US evidence. The analysis is illustrated for the case of Chile, although it could be applied to other countries.
A European perspective for developing modern multifunctional agroforestry systems for sustainable intensification
Authors: Smith Jo , Pearce Bruce D. , Wolfe Martin S.
Published: January 2012

One of the key questions of primary importance to global agriculture and food security is how to optimize sustainable intensification to balance competing demands on land for food and energy production, while ensuring the provision of ecosystem services and maintaining or increasing yields. Integrating trees and agriculture through agroforestry has been attracting increasing interest as an agroecological approach to sustainable intensification. Trees have traditionally been important elements of temperate agricultural systems around the world, but there has been increasing separation of agriculture, forestry and nature over the past few decades. This paper discusses what we can learn from traditional agroforestry systems to help develop modern systems that integrate ecological farming and agroecological advances to achieve sustainable intensification. We also discuss the existing barriers to wider adoption of agroforestry, and identify how these barriers can be overcome to promote agroforestry as a mainstream land-use system.
The phenology, yield and tuber composition of ‘early’ crop potatoes: A comparison between organic and conventional cultivation systems
Authors: Lombardo Sara , Lo Monaco Antonino , Pandino Gaetano , Parisi Bruno , Mauromicale Giovanni
Published: January 2012

Potato production in several Mediterranean countries is focused on the ‘early’ crop type, and is generally associated with intensive applications of farming inputs. Here we report, for the first time, a comparison of crop performance between organic and conventional cultivation systems. Three cultivars were tested over two seasons (2007 and 2008) to record their phenology, yield and tuber chemical composition. The organic cultivation system was less productive than the conventional one across both years with respect to total yield, but in the season (2008) when late blight infection was not severe the difference was narrowed from 7% (Ditta) to 20% (MN 2-1577 S1). The Italian breeding clones (MN 1404 O5 and MN 2-1577 S1) deserve specific consideration due to their higher total yield and nutritional value (in terms of total protein and vitamin C content) under organic cultivation system than the cultivar Ditta. In addition, the organic farming produced tubers with a lower nitrate content, an important benefit in the context of human health. In conclusion, our results indicate that organic cultivation of ‘early’ potatoes can deliver acceptable agronomic and qualitative performances. However, the response of the ‘early’ crop potato to organic farming depends upon both seasonal conditions and cultivar choice. In particular, the selection of appropriate cultivars is one of the key aspects to optimize this environmentally friendly production system.
The role of terrestrial vegetation in atmospheric Hg deposition: Pools and fluxes of spike and ambient Hg from the METAALICUS experiment
Authors: Graydon Jennifer A. , St. Louis Vincent L. , Lindberg Steve E. , Sandilands Ken A. , Rudd John W. M. , Kelly Carol A. , Harris Reed , Tate Michael T. , Krabbenhoft Dave P. , Emmerton Craig A. , Asmath Hamish , Richardson Murray
Published: January 2012

As part of the Mercury Experiment to Assess Atmospheric Loading in Canada and the U.S. (METAALICUS), different stable Hg(II) isotope spikes were applied to the upland and wetland areas of a boreal catchment between 2001 and 2006 to examine retention of newly deposited Hg(II). In the present study, a Geographical Information Systems (GIS)‐based approach was used to quantify canopy and ground vegetation pools of experimentally applied upland and wetland spike Hg within the METAALICUS watershed over the terrestrial loading phase of the experiment. A chemical kinetic model was also used to describe the changes in spike Hg concentrations of canopy and ground vegetation over time. An examination of the fate of spike Hg initially present on canopy vegetation using a mass balance approach indicated that the largest percentage flux from the canopy over one year post‐spray was emission to the atmosphere (upland: 45%; wetland: 71%), followed by litterfall (upland: 14%; wetland: 10%) and throughfall fluxes (upland: 12%; wetland: 9%) and longer term retention of spike in the forest canopy (11% for both upland and wetland). Average half‐lives (t1/2) of spike on deciduous (110 ± 30 days) and coniferous (180 ± 40 days) canopy and ground vegetation (890 ± 620 days) indicated that retention of new atmospheric Hg(II) on terrestrial (especially ground) vegetation delays downward transport of new atmospheric Hg(II) into the soil profile and runoff into lakes.
Thermotidal and land‐heating forcing of the diurnal cycle of oceanic surface winds in the eastern tropical Pacific
Authors: Takahashi Ken
Published: January 2012

The diurnal cycle in the oceanic surface winds in the tropical eastern Pacific is shown, through numerical experiments with a regional atmospheric model, to be associated with the migrating diurnal atmospheric thermal tide, forced by absorption of solar near‐IR radiation by tropospheric water vapor, and a topographically‐modified extended sea‐breeze, forced by diurnal land heating. Idealized experiments prove capable of discriminating the effects of both processes, showing that beyond 2000 km from the coast, the thermal tide is dominant, while closer to the coast both processes are of the same order. The shortwave forcing due to water vapor is also found to produce a diurnal cycle in precipitation, but the process appears to be independent from the thermal tide and it is proposed that this effect is mediated by the radiatively‐forced changes in the column stability.
Electron velocity distribution instability in magnetized plasma wakes and artificial electron mass
Authors: Hutchinson I. H.
Published: January 2012

The wake behind a large object (such as the moon) moving rapidly through a plasma (such as the solar wind) contains a region of depleted density, into which the plasma expands along the magnetic field, transverse to the flow. It is shown here that (in addition to any ion instability) a bump‐on‐tail which is unstable appears on the electrons' parallel velocity distribution function because of the convective non‐conservation of parallel energy (drift‐energization). It arises regardless of any non‐thermal features on the external electron velocity distribution. The detailed electron distribution function throughout the wake is calculated by integration along orbits; and the substantial energy level of resulting electron plasma (Langmuir) turbulence is evaluated quasi‐linearly. It peaks near the wake axis. If the mass of the electrons is artificially enhanced, for example in order to make numerical simulation feasible, then much more unstable electron distributions arise; but these are caused by the unphysical mass ratio.
Inference of coseismic slip via joint inversion of GPS and aftershock data: The 2004 Parkfield example
Authors: Ziv A.
Published: January 2012

In many coseismic slip inversions, the number of model parameters is much larger than that of the independent observations, and the problem is extremely underdetermined. It is thus instructive to incorporate additional data sets into the slip inversion. In this study I describe a new approach for coseismic slip inversion, whereby both GPS displacements and first day aftershock rate changes are used jointly to constrain the solution. The joint inversion incorporates the Dieterich's aftershock model, which adopts a constitutive friction that depends logarithmically on the sliding rate. The method is applied to the 2004 Parkfield earthquake. The joint inversion not only provides resolving power of slip at depths inaccessible to GPS‐only inversions, but it also helps to gain insight on the fault mechanical properties. I show that the data are consistent with the adopted aftershock model being the dominant mechanism for aftershock production along the Parkfield segment, and I obtain an upper bound on the friction dependence on the log of rate of fault patches that have experienced aftershock activity. A consequence of the irregular aftershock distribution is that the slip distribution is extremely nonsmooth, with the aftershock zones acting as barriers.
Nucleation of slip‐weakening rupture instability in landslides by localized increase of pore pressure
Authors: Viesca Robert C. , Rice James R.
Published: January 2012

We model landslide initiation as slip surface growth driven by locally elevated pore pressure, with particular reference to submarine slides. Assuming an elastic medium and friction that weakens with slip, solutions exist in which the slip surface may dynamically grow, without further pore pressure increases, at a rate of the order of the sediment shear wave speed, a situation comparable to earthquake nucleation. The size of the rupture at this transition point depends weakly on the imposed pore pressure profile; however, the amount of slip at the transition depends strongly on whether the pore pressure was broadly or sharply elevated. Sharper profiles may result in pore pressures reaching the total slope‐normal stress before dynamic rupture is nucleated. While we do not account for modes of failure other than pure slip on a failure surface, this may be an indication that additional modes involving liquefaction or hydraulic cracking may be factors in the initiation of shallow slope failure. We identify two length scales, one geometrical (h, depth below the free surface) and one material (ℓ, determined by the frictional weakening rate) and a transition in nucleation behavior between effectively “deep” and “shallow” limits dependent on their ratio. Whether dynamic propagation of failure is indefinite or arresting depends largely on whether the background shear stress is closer to nominal peak or residual frictional strength. This is determined in part by background pore pressures, and to consider the submarine case we simplify a common sedimentation/consolidation approach to reflect interest in near‐seafloor conditions.
Effects of stencil width on surface ocean geostrophic velocity and vorticity estimation from gridded satellite altimeter data
Authors: Arbic Brian K. , Scott Robert B. , Chelton Dudley B. , Richman James G. , Shriver Jay F.
Published: January 2012

This paper examines the effect of “stencil width” on surface ocean geostrophic velocity and vorticity estimated from differentiating gridded satellite altimeter sea surface height products. In oceanographic applications, the value of the first derivative at a central grid point is generally obtained by differencing the sea surface heights at adjacent grid points. This is called a “three‐point stencil centered difference”. Here the stencil width is increased from three to five, seven, and nine points, using well‐known formulae from the numerical analysis literature. The discrepancies between velocities computed with successive stencils decreases with increasing stencil width, suggesting that wide stencil results are more reliable. Significant speed‐dependent biases (up to 10–20%) are found between results computed from three‐point stencils versus those computed from wider stencils. The geostrophic velocity, and the variance of geostrophic velocity, are underestimated with thin stencils. Similar results are seen in geostrophic velocities computed from high‐resolution model output. In contrast to the case when three‐point stencils are used, wider stencils yield estimates of the anisotropy of velocity variance that are insensitive to the differences in grid spacing between two widely used altimeter products. Three‐point stencils yield incorrect anisotropies on the 1/4° anisotropic AVISO grid; we recommend the use of 7‐point stencils. Despite the demonstrated inadequacies of the three‐point stencils, the conclusions of earlier studies based on them, that the zonally averaged midlatitude eddy kinetic energy field is nearly isotropic, are found to pertain also with wider stencils. Finally, the paper also examines the strengths and limitations of applying noise‐suppressing differentiators, versus classic centered differences, to altimeter data.
An updated examination of the Luzon Strait transport
Authors: Hsin Yi‐Chia , Wu Chau‐Ron , Chao Shenn‐Yu
Published: January 2012

Despite numerous previous estimates of Luzon Strait transport (LST), we attempt an update using a fine‐resolution model. With these improvements, the circulation in and around Luzon Strait shows up rather realistically. Intrusion of a Kuroshio meander into the South China Sea (SCS) is seasonally varying. The LST, especially in the upper ocean, caused by a small difference between the large meander inflow and outflow, is also seasonally varying and subject to large standard deviation. The annual mean LST is estimated to be westward (−4.0 ± 5.1 Sv) along 120.75°E. We have also conducted process of elimination experiments to assess the relative importance of open ocean inflow/outflow, wind stress, and surface heat flux in regulating LST and its seasonality. The East Asian monsoon winds stand out as the predominant forcing. Without it, the upper ocean LST changes from westward to eastward (ranging up to 4 Sv) and, with misaligned seasonality, triggering an inflow from the Mindoro Strait to the SCS to replenish the water mass loss. Discounting monsoon winds, sea level in the Sulu Sea is generally higher because it receives the Indonesian Throughflow before the SCS, which causes an inflow from the Sulu Sea to the SCS. On the other hand, the annual mean wind from the northeast invites outflow from the SCS to the Sulu Sea (or inflow from the Luzon Strait). Weighing the two competing factors together, we see the cessation of northeast monsoon as a condition favorable for the Luzon Strait outflow or the Mindoro Strait inflow.
Structure, specific surface area and thermal conductivity of the snowpack around Barrow, Alaska
Authors: Domine Florent , Gallet Jean‐Charles , Bock Josué , Morin Samuel
Published: January 2012

The structure of the snowpack near Barrow was studied in March–April 2009. Vertical profiles of density, specific surface area (SSA) and thermal conductivity were measured on tundra, lakes and landfast ice. The average thickness was 41 cm on tundra and 21 cm on fast ice. Layers observed were diamond dust or recent wind drifts on top, overlaying wind slabs, occasional faceted crystals and melt‐freeze crusts, and basal depth hoar layers. The top layer had a SSA between 45 and 224 m2 kg−1. All layers at Barrow had SSAs higher than at many other places because of the geographical and climatic characteristics of Barrow. In particular, a given snow layer was remobilized several times by frequent winds, which resulted in SSA increases each time. The average snow area index (SAI, the dimensionless vertically integrated SSA) on tundra was 3260, higher than in the Canadian High Arctic or in the Alaskan taiga. This high SAI, combined with low snow temperatures, imply that the Barrow snowpack efficiently traps persistent organic pollutants, as illustrated with simple calculations for PCB 28 and PCB 180. The average thermal conductivity was 0.21 Wm−1 K−1, and the average thermal resistance on tundra was 3.25 m2 K W−1. This low value partly explains why the snow‐ground interface was cold, around −19°C. The high SAI and low thermal resistance values illustrate the interplay between climate, snow physical properties, and their potential impact on atmospheric chemistry, and the need to describe these relationships in models of polar climate and atmospheric chemistry, especially in a climate change context.
Chemical composition of the snowpack during the OASIS spring campaign 2009 at Barrow, Alaska
Authors: Jacobi H. W. , Voisin D. , Jaffrezo J. L. , Cozic J. , Douglas T. A.
Published: January 2012

The chemical composition of the seasonal snowpack was determined close to Barrow, an Arctic coastal location in northern Alaska. One hundred and twelve samples of different snow types including fresh snow, surface hoar, diamond dust, blowing snow, rounded snow grains, and depth hoar were collected and analyzed for major sea salt components, bromide, and nitrate. Sodium, chloride, sulfate, and potassium are mainly introduced into the snowpack by the deposition of sea salt, while magnesium and calcium result from a combination of sea salt and dust. Sulfate was strongly depleted in most samples compared to other sea salt components. This is attributed to the precipitation of mirabilite in newly formed sea ice and frost flowers that leads to an efficient fractionation of sulfate. Uptake of volatile but soluble species from the gas phase also contributed to the observed chloride, sulfate, and nitrate in the snow. However, for chloride and sulfate the input from the marine sources was overwhelming and the uptake from the gas phase was only visible in the samples with low concentrations like fresh snow, diamond dust, and surface hoar. Nitrate concentrations in the snowpack were less variable and for aged snow nitrate was related to the specific surface area of the snow indicating the adsorption of nitric acid can be an important nitrate source in the aged snow. Bromide was also introduced into the snowpack from marine sources, but due to its high reactivity it was partly transferred back to the atmosphere in the form of reactive species. The result of these processes was evident in bromide concentrations, which were both enriched and depleted at the snowpack surface while deeper layers were mostly depleted. Blowing snow also exhibited a depleted bromide composition. For all compounds except nitrate, many depth hoar samples exhibited the greatest concentrations, probably as a result of higher input earlier in the season as well as increases due to the sublimation of water during the metamorphism of the snow.
Reproduction of twentieth century intradecadal to multidecadal surface temperature variability in radiatively forced coupled climate models
Authors: Brown Patrick T. , Cordero Eugene C. , Mauget Steven A.
Published: January 2012

Coupled Model Intercomparison Project 3 simulations that included time‐varying radiative forcings were ranked according to their ability to consistently reproduce twentieth century intradecadal to multidecadal (IMD) surface temperature variability at the 5° by 5° spatial scale. IMD variability was identified using the running Mann‐Whitney Z method. Model rankings were given context by comparing the IMD variability in preindustrial control runs to observations and by contrasting the IMD variability among the ensemble members within each model. These experiments confirmed that the inclusion of time‐varying external forcings brought simulations into closer agreement with observations. Additionally, they illustrated that the magnitude of unforced variability differed between models. This led to a supplementary metric that assessed model ability to reproduce observations while accounting for each model's own degree of unforced variability. These two metrics revealed that discernable differences in skill exist between models and that none of the models reproduced observations at their theoretical optimum level. Overall, these results demonstrate a methodology for assessing coupled models relative to each other within a multimodel framework.