bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental geochemistry of recent volcanic ashes from the Southern Andes
Authors: Ruggieri Flavia , Fernández-Turiel Jose-Luis , Saavedra Julio , Gimeno Domingo , Polanco Edmundo , Naranjo José Antonio
Published: June 2011

Environmental contextExplosive volcanic eruptions may have significant environmental repercussions for many Earth system cycles, particularly the water cycle. We investigate the potential contribution to local geochemical fluxes through water of five historical eruptions that occurred over a 20-year period in the Southern Andes. In all five cases, the major potentially toxic trace elements were arsenic, copper, fluoride, molybdenum, nickel, lead and zinc.
AbstractThe potential contribution to the local geochemical balance of five historical eruptions that occurred during the 20th Century has been investigated in the Southern Volcanic Zone (SVZ) of the Andean volcanic arc of South America (Lonquimay 1988, Hudson 1991, Copahue 2000, Llaima 2008, Chaitén 2008). These ashes were characterised by SEMEDX and XRD, and their potential released geochemical fluxes were examined using water and nitric acid batch leaching tests. Leachates were analysed by ICP-OES, ICP-MS and ISE. The major contents removed correspond to SO42– and Cl–. The potential toxic trace element (PTTE) content was highly variable among the ash samples following this order: Chaitén > Copahue > Hudson > Llaima > Lonquimay. The trace elements with significant load in water batch leaching tests include Fe > F > B > P > Zn > As > Mn > Sr > Ba > Ti > Cu > Ni > Li > Rb > Co > Cr > Cd > Sb. Some of these elements (As, Cu, F, Mo, Ni, Pb and Zn) are included in the drinking water guidelines due to their potential toxicity and must be especially monitored in the environmental assessment of these ashfall deposits.
Trace metals in the open oceans: speciation modelling based on humic-type ligands
Authors: Stockdale Anthony , Tipping Edward , Hamilton-Taylor John , Lofts Stephen
Published: June 2011

Environmental contextSpeciation of trace metals in the oceans is typically explained by invoking the concept of metal binding to specific organic ligands. Here, using a speciation model widely used for freshwaters, we assess the extent to which non-specific humic-type ligands found in the ocean may explain chemical speciation of cationic metals. We found that the model can give good fits in some cases, and that experimental results do not give consistent variation from the model. This has implications for the way that the availability of trace elements is considered in ocean environments. AbstractThe speciation of trace metals in the oceans is typically explained by invoking the concept of metal binding to specific organic ligands, but a lack of detailed knowledge about the ligands has impeded the formulation of comprehensive models to predict speciation chemistry. The aim of our study was to shed further light on the possible role of humic-type ligands in trace metal complexation in the oceans by comparing published seawater (open ocean) speciation measurements with predictions obtained using a speciation model typically used for freshwater and soil systems (Windermere Humic Aqueous Model; WHAM). We show that in some cases, speciation of trace metals in seawater environments may be reasonably predicted using this model with its default parameter set, without any model fitting. The results support the idea that humic-type ligands may account for much of the observed organic binding at least in the cases of Fe, Cu and Pb. Although the model does not consistently provide agreement with the measured values, it provides a useful benchmark to compare different datasets and to examine variation in speciation as a result of varying levels of competing metal ion concentration and fulvic acid activity.
Humic Ion-Binding Model VII: a revised parameterisation of cation-binding by humic substances
Authors: Tipping E. , Lofts S. , Sonke J. E.
Published: June 2011

Environmental contextNatural organic matter exerts a powerful control on chemical conditions in waters and soils, affecting pH and influencing the biological availability, transport and retention of metals. To quantify the reactions, we collated a wealth of laboratory data covering 40 metals and acid–base reactions, and used them to parameterise the latest in a series of Humic Ion-Binding Models. Model VII is now available to interpret field data, and contribute to the prediction of environmental chemistry.
AbstractHumic Ion-Binding Model VII aims to predict the competitive reactions of protons and metals with natural organic matter in soils and waters, based on laboratory results with isolated humic and fulvic acids (HA and FA). Model VII is simpler in its postulated multidentate metal binding sites than the previous Model VI. Three model parameters were eliminated by using a formal relationship between monodentate binding to strong- and weak-acid oxygen-containing ligands, and removing factors that provide ranges of ligand binding strengths. Thus Model VII uses a single adjustable parameter, the equilibrium constant for monodentate binding to strong-acid (carboxylate) groups (KMA), for each metallic cation. Proton-binding parameters, and mean values of log KMA were derived by fitting 248 published datasets (28 for protons, 220 for cationic metals). Default values of log KMA for FA were obtained by combining the fitted values for FA, results for HA, and the relationship for different metals between log KMA and equilibrium constants for simple oxygen-containing ligands. The equivalent approach was used for HA. The parameterised model improves on Model VI by incorporating more metals (40), providing better descriptions of metal binding at higher pH, and through more internally consistent parameter values.
Capillary electrophoresis study of iron(II) and iron(III) polyaminocarboxylate complex speciation
Authors: Wilson Jessica M. , Carbonaro Richard F.
Published: June 2011

Environmental contextMethods for determining iron species are integral to investigations of iron cycling processes in the environment. Capillary electrophoresis is an effective tool for determining the concentrations of various iron species in solution, but the separations are highly dependent on the electrolyte composition. This study reports the use of capillary electrophoresis to separate and quantify distinct FeII and FeIII complexes with polyaminocarboxylates. AbstractThe purpose of this study was to use capillary electrophoresis to (i) separate and quantify distinct FeII and FeIII complexes with polyaminocarboxylates and (ii) develop new methods for distinguishing between FeII and FeIII in aqueous media. A 25 mM phosphate and a 50 mM 3-(N-morpholino)propanesulfonic acid (MOPS) background electrolyte (BGE), both buffered at pH 7.1, were each tested with 6 polyaminocarboxylate complexes with FeII and FeIII. Adequate separation of all FeIII-chelating agent complexes was observed with the MOPS BGE. With the phosphate BGE, sharp peaks were obtained for FeIII complexes with EDTA, HEDTA, DTPA and CDTA, however FeIII–EGTA showed excessive peak broadening, and FeIII–TMDTA showed no discernable peak. Mobilities of FeIII–EGTA, FeIII–EDTA and FeIII–HEDTA were much larger when the phosphate BGE was employed, providing evidence for ternary complex formation with phosphate during electromigration. For FeII, complexes with TMDTA and EGTA were adequately separated with either BGE, but separations of the other chelating agents resulted in their corresponding FeIII complexes due to rapid oxidation by molecular oxygen. These chelating agents may be used as preservatives and derivatising agents for the analysis of ferrous and ferric iron in environmental samples.
The patterns of grazed pasture associated with scattered trees across an Australian temperate landscape: an investigation of pasture quantity and quality
Authors: Barnes Phoebe , Wilson Brian R. , Trotter Mark G. , Lamb David W. , Reid Nick , Koen Terry , Bayerlein Leopold
Published: June 2011

Scattered paddock trees occur across agricultural landscapes in Australia. However, in the temperate regions of Australia their numbers are rapidly declining and they may be lost across much of the landscape in 200 years. Here we examined the spatial distribution of green (GDB), senescent (SDB) and total (TDB) dry pasture biomass, and nutrient status of the GDB fraction around scattered Eucalyptus trees on three parent materials (basalt, granite and meta-sediment) in native and sown pastures across a range of grazed temperate landscapes in northern New South Wales. We used a combination of destructive harvests and a handheld active optical canopy reflectance sensor (AOS) with an integrated GPS to examine pasture biomass around scattered trees. The harvested pasture biomass data indicated that under grazed conditions the presence of scattered trees did not introduce significant radial trends in TDB or GDB out to a distance of 3.5 canopy radii regardless of tree species or parent material. The red and near-infrared reflectance-based Normalised Difference Vegetation Index (NDVI), as measured by the AOS, did indicate a consistent azimuthal trend with larger GDB on the southern side of the tree and lower GDB on the northern side in the native pasture. However, this observation must be qualified as the regression coefficient for the relationship between NDVI and GDB was significant but weak (best r2 = 0.42), and SDB reduced its predictive capacity. We also found a higher percentage of GDB under the canopy than in the open paddock. We suggest that the combination of these results may indicate higher grazing pressure under trees than in the open paddock. Pasture nutrient concentration (P, K and S) was higher in both native and sown pastures beneath the tree canopy compared with the open paddock. This study indicates that, in this temperate environment, scattered trees do not adversely affect pasture production, and that they can improve some pasture nutrients.
Primary prevention lessons learned from those with HIV in Chennai, India
Authors: Hendriksen Ellen Setsuko , Krishnan A. K. Sri , Vallabhaneni Snigda , Johnson Sethu , Raminani Sudha , Kumarasamy N. , Solomon Suniti , Mayer Kenneth K. H. , Safren Steven S.
Published: June 2011

Background As each HIV-infected individual represents a breakdown of HIV primary prevention measures, formative data from representative individuals living with HIV can help shape future primary prevention interventions. Little is known about sexual behaviours and other transmission risk factors of high-risk group members who are already HIV-infected in Chennai, India. Methods: Semi-structured qualitative interviews were conducted with 27 HIV-infected individuals representing each high-risk group in Chennai (five men who have sex with men (MSM), five female commercial sex workers (CSW), four truckers and other men who travel for business, four injecting drug users (IDU), five married male clients of CSW, and four wives of CSW clients, MSM, truckers, and IDU). Results: Themes relevant to HIV primary prevention included: (1) HIV diagnosis as the entry into HIV education and risk reduction, (2) reluctance to undergo voluntary counselling and testing, (3) gender and sexual roles as determinants of condom use, (4) misconceptions about HIV transmission, and (5) framing and accessibility of HIV education messages. Conclusions: These qualitative data can be used to develop hypotheses about sexual risk taking in HIV-infected individuals in South India, inform primary prevention intervention programs, and improve primary prevention efforts overall.
Anal intercourse among female sex workers in East Africa is associated with other high-risk behaviours for HIV
Authors: Veldhuijzen Nienke J. , Ingabire Chantal , Luchters Stanley , Bosire Wilkister , Braunstein Sarah , Chersich Matthew , van de Wijgert Janneke
Published: June 2011

Introduction
Epidemiological and HIV prevention studies in sub-Saharan Africa have almost exclusively focussed on vaginal transmission of HIV, the primary mode of transmission in the region. Little is known about the prevalence of heterosexual anal intercourse (AI), its correlates and its role in the spread of HIV. Prevention messaging seldom, if ever, includes AI. Methods: Sexual and other risk behaviours (including frequency of AI) were assessed in two cross-sectional surveys of female sex workers (FSW) in Kigali, Rwanda (n = 800) and Mombasa, Kenya (n = 820). In addition, a subset of FSW surveyed in Kigali attended seven focus group discussions and four in-depth interviews. Results: AI was reported by 5.5% and 4.3% of FSW in the cross-sectional surveys, in Kigali and Mombasa, respectively. FSW practising AI reported multiple risk factors for HIV transmission: inconsistent condom use (odds ratio (OR) Kigali 5.9 (95% CI 1.4–24.7); OR Mombasa 2.1 (1.1–4.2)); more than five sexual partners in the past week (OR Kigali 4.3 (1.5–12.4); OR Mombasa 2.2 (1.1–4.3)); alcohol use before sex (OR Kigali 2.8 (1.4–5.8)); more than 5 years of female sex work (OR Mombasa 2.4 (1.2–4.9)); and history of genital symptoms in the past year (OR Mombasa 3.6 (1.7–7.9)). AI was, however, not associated with HIV prevalence (OR Kigali 0.9 (0.5–1.9); OR Mombasa 0.5 (0.2–1.2)). Negative connotations and stigma associated with AI were expressed during qualitative interviews. Conclusions: AI was associated with several indicators of sexual risk behaviour. Prevalence of AI was probably underreported due to social desirability bias. Stigma associated with AI poses methodological challenges in obtaining valid data.
A review of the epidemiology, diagnosis and evidence-based management of Mycoplasma genitalium
Authors: Weinstein Scott A. , Stiles Bradley G.
Published: June 2011

Mycoplasma genitalium is attracting increasing recognition as an important sexually transmitted pathogen. Presented is a review of the epidemiology, detection, presentation and management of M. genitalium infection. Accumulating evidence suggests that M. genitalium is an important cause of non-gonococcal, non-chlamydial urethritis and cervicitis, and is linked with pelvic inflammatory disease and, possibly, obstetric complications. Although there is no standard detection assay, several nucleic acid amplification tests have >95% sensitivity and specificity for M. genitalium. To date, there is a general lack of established protocols for screening in public health clinics. Patients with urethritis or cervicitis should be screened for M. genitalium and some asymptomatic sub-groups should be screened depending on individual factors and local prevalence. Investigations estimating M. genitalium geographic prevalence document generally low incidence, but some communities exhibit infection frequencies comparable to that of Chlamydia trachomatis. Accumulating evidence supports an extended regimen of azithromycin for treatment of M. genitalium infection, as data suggest that stat 1 g azithromycin may be less effective. Although data are limited, azithromycin-resistant cases documented to date respond to an appropriate fluoroquinolone (e.g. moxifloxacin). Inconsistent clinical recognition of M. genitalium may result in treatment failure and subsequent persistence due to ineffective antibiotics. The contrasting nature of existing literature regarding risks of M. genitalium infection emphasises the need for further carefully controlled studies of this emerging pathogen.
Hepatitis B virus and hepatitis C virus infections among female sex workers and men who have sex with men in Lebanon: prevalence, risk behaviour and immune status
Authors: Kassak Kassem , Mahfoud Ziyad , Kreidieh Khalil , Shamra Sarah , Afifi Rima , Ramia Sami
Published: June 2011

Background The aim of our study was to study the prevalence of and the risk behaviours associated with the hepatitis B virus (HBV) and hepatitis C virus (HCV) infections among two high-risk groups: female sex workers (FSW) and men who have sex with men (MSM). Furthermore, since vaccination is a key component of HBV prevention programs, the immune status of HBV infection in these two high-risk groups was evaluated. Methods: Participants included in this study were part of a bio-behavioural surveillance study done to assess HIV prevalence among four vulnerable groups in Lebanon. Participants were recruited using a respondent-driven sampling method. The total number of eligible participants were 101 MSM and 103 FSW. Blood samples were collected as dried blood spots and then eluted to be tested for HCV, HBV and HIV by enzyme-linked immunosorbent assay. Results: None of the 204 individuals tested has been exposed to HCV. In the 101 MSM, only one (0.99%) was an HBsAg carrier and one (0.99%) was confirmed as anti-HIV-positive. Among FSW, 30% showed they were immune to HBV compared with only ~10% among MSM. The distribution of socio-demographic characteristics and potential risk factors in both groups were shown. Conclusion: Our results highlight the urgent need to raise awareness among FSW and MSM and their health care providers of the availability and benefits of HBV vaccination in Lebanon. In addition, and due to the absence of vaccines against HCV and HIV, education programs aiming at behavioural changes should be intensified.
HIV results: practice at public sexual health clinics in New South Wales
Authors: Healey Loretta M. , Templeton David J.
Published: June 2011

New South Wales (NSW) Health guidelines recommend all HIV results be given in person, however this practice fails to achieve high levels of result collection. Fourteen of all 38 NSW public sexual health clinics (37%) surveyed offer HIV results by telephone to low-risk patients, although all positive results are given in person. Efficiency of result-giving, accessibility to results, patient acceptability and awareness of more flexible national guidelines were cited as reasons for varying practice from state guidelines. NSW guidelines require revision to allow clinicians to determine the most effective and efficient mode of HIV result delivery to their patients.
Drama and Healing in Ancient Greece: Demeter and Asklepios
Authors: Pitruzzella Salvo
Published: June 2011

This article focuses on two important rituals of Ancient Greece, which are of some interest for dramatherapists, as dramatic performances had a key role in them. We will examine them from a historical point of view, then explore their mythic contents and how they were expressed in drama, trying to suggest cues that relate them to present day dramatherapy theory and practice.
Meeting with the Metaphor: The Impact of the Dramatic Metaphor on the Therapeutic Relationship
Authors: Swanepoel Marlize
Published: June 2011

This investigation focuses on the impact of the dramatic metaphor on the therapeutic relationship. It follows the hypothesis that the dramatic metaphor is unique in the sense that it can be made physical in the therapeutic space by offering clients an embodied experience of their own symbols and metaphors. It explores what this may implicate in the therapeutic process. Furthermore, it hopes to demonstrate how the dramatic metaphor facilitates a meaningful relationship between client and therapist. It is also being suggested that the dramatic metaphor can serve the therapeutic process as a channel for transference and countertransference. The investigation adopts a hermeneutic approach that attempts to synthesize selected literature on the subject and relate it to a piece of clinical work. The case vignettes highlight work with two clients that took place over a period of six months in an adult mental health community centre.
Land grabbing in Southern Africa: the many faces of the investor rush
Authors: Hall Ruth
Published: June 2011

The popular term ‘land grabbing’, while effective as activist terminology, obscures vast differences in the legality, structure and outcomes of commercial land deals and deflects attention from the roles of domestic elites and governments as partners, intermediaries and beneficiaries. This paper summarises initial evidence of the characteristics of recent acquisitions of public lands and land held under customary tenure in Southern Africa, and their distribution across the region. It draws attention to their diverse manifestations – to questions of size, duration and source of the investments; the commodities and business models through which they are implemented; the tenure arrangements and resources accessed; the terms of leases and compensation; the degree of displacement; labour regimes and employment creation; and changes in settlement and infrastructure. The article proposes a schematic analytical framework for distinguishing between different types of land deals and considers the implications for unfolding and future trajectories of agrarian change.
Strategic privatisation: rehabilitating the Mozambican sugar industry
Authors: Buur Lars , Mondlane Carlota , Baloi Obede
Published: June 2011

This article argues that the rehabilitation of the sugar industry in Mozambique cannot be understood without including the active role played by the state and government. It focuses on key aspects of why and how the Mozambican sugar industry was rehabilitated after 1996 with and through foreign direct investments. It challenges the externalist literature on Mozambique that has commonly argued that all policy decisions are enforced by the pressure of well-meaning donors and/or ignorant international financial institutions preparing the ground for large international corporations through neoliberal policies, privatisation and structural adjustment programmes. There can be no doubt that donors in general, international financial institutions, and international capital have had and continue to have considerable influence over economic and industrial policy in Mozambique, but externalist accounts of various persuasions have limitations and tend to present accounts of the Mozambican state and government solely as victims instead of active players.
English in the National Curriculum: a simple redraft or a major rewrite?
Authors: Marshall Bethan
Published: June 2011

The national curriculum for English is about to be rewritten again, having only been looked at four years ago. According to the chair of the expert group on the new national curriculum this is because the curricula of the past had become too baggy. Although he was not specifically looking at the English curriculum this too is being examined. This article considers the main areas that they will be attending to in the revisions – phonics, the canon and Standard English. It argues that these are the areas that the Tory governments looked at before when they first tried to rewrite the national curriculum and that the reasons are ideological rather than pragmatic. It compares the writing of this curriculum with other countries and looks at how they have framed the debates about what should be in their curricula.
Disciplinary knowledge for all, the secondary history curriculum and history teachers' achievement
Authors: Counsell Christine
Published: June 2011

The history education community%s efforts to help pupils distinguish between the discipline of history and rawer forms of collective memory have been beset with problems from inside and outside the education community. From without, teachers face criticism for their supposed failure to foster narrowly celebratory versions of Britain%s past; from within, pressure to reduce history to generic ‘skills’ of the ‘new cross‐curricularity’, apparently in the interests of relevance, utility or engagement. This article will argue that such genericism is, first, redundant, in that it adds nothing to strong disciplinary practice in fostering thinking, reflection, criticality and motivation; and, second, inadequate: disciplinary knowledge and concepts are necessary in order to reach or challenge claims about the past. The argument is built from history teachers' discourse about their own efforts to find out how to make disciplinary history work at the pedagogic site. The article examines history teacher efforts to address complex problems of uniting content and concept and of motivating lower‐attaining or marginalised students whom others (variously) claim can be helped only by narrow narratives or by giving up on disciplinary rigour altogether. The story of history teacher efforts contains valuable lessons for curriculum reviewers about the potential of strong classificatory framing for emancipatory and engaging learning. The article argues that any improvement of the existing Key Stage 3 curriculum is pointless, however, unless wider cultural and structural problems impeding lower‐attaining students' entitlement to the subject are resolved.
EDUCATIONAL ATTAINMENT, OCCUPATIONAL ACHIEVEMENTS, CAREER PEAKS
Authors: Wolbers Maarten H.J. , Luijkx Ruud , Ultee Wout
Published: June 2011

This paper answers questions on the educational attainment and occupational career of men in The Netherlands whose working life began in the 1950s, 1960s, and 1970s, in so far as their job history is available until at least the age of 45 years. The analysis draws on five Dutch retrospective life-history surveys conducted between 1992 and 2003. The results show that a man's education depends upon his father's job, and that this effect has not changed for labour market entry cohorts. When explaining a man's first job, his father's job is influential once more, independent of a man's education. A man's education has a direct positive effect on his first job, his job after 10 and 20 years, and his peak job, but again the differences in status attainment between labour market entry cohorts are limited. Findings also reveal that advantages accumulate during a person's working life. Apart from a higher level of education, a higher first job has an independent positive effect on a man's job after 10 and 20 years, as well as on his peak status.
Directed Forgetting of Faces: The Role of Response Criterion
Authors: Goernert Phillip N. , Corenblum Barry , Otani Hajime
Published: June 2011

In two experiments, we examined recognition for faces following item method directed forgetting. During testing, participants reported whether the face was a new face or, if they thought it was a studied face, they identified the instruction paired with the face during study. In both experiments, the proportion of new faces falsely recognized and classified as forget faces exceeded those falsely recognized and classified as remember faces. Despite the use of different response criteria during testing, participants showed greater discrimination accuracy when identifying remember faces than when identifying forget faces. Taken together, these data patterns indicate that participants employed a strength-based criterion when responding. Specifically, participants responding to new faces were more likely to classify those faces as forget faces from study rather than as remember faces from study.
π-extended conjugated semiconducting molecules based on triphenylene
Authors: Ha Hoang Mai , Nghia Nguyen Duc , Hoon Choi Dong
Published: June 2011

The authors report on the design and synthesis of new semiconducting materials, based on a triphenylene core. In comparison with all previous reported triphenylene derivatives, these molecules have lower bandgap energies. 2,3,6,7,10,11-Hexakis(4-((E)-2-(5′-hexyl-2,2′-bithiophen-5-yl)vinyl)phenyl) triphenylene and 2,3,6,7,10,11-Hexakis(4-((E)-2-(5′-dodecyl-2,2′-bithiophen-5-yl)vinyl)phenyl)triphenylene have good solubility and are applicable to soluble processing for organic field effect transistor (OFET) and organic solar cell (OSC) fabrications. As far as we know, there are few reports on the application of π-extended triphenylene systems to OFET. The other molecule, 2,3,6,7,10,11-Hexakis((4-(5-dodecylthiophen-2-yl)phenyl)ethynyl)triphenylene, is a new discotic liquid crystalline (LC) semiconducting material. This molecule is readily soluble in common organic solvents to exhibit self-organizing long fiber structures with supramolecularly ordered columnar stacks that lie parallel to the substrate. The semiconducting properties of these molecules were quite promising for further designs of π-extended triphenylene derivatives.
Global sections of structure sheaves of Keigher rings
Authors: Trushin Dmitry
Published: June 2011

Answering a question of J. Kovacic, we show that for any Keigher ring, its differential spectrum coincides with the differential spectrum of the ring of global sections of the structure sheaf. In particular, we obtain the answer for Ritt algebras, that is, differential rings containing the rational numbers.
Multi-variate models are essential for understanding vertebrate diversification in deep time
Authors: Benson Roger B. J. , Mannion Philip D.
Published: June 2011

Statistical models are helping palaeontologists to elucidate the history of biodiversity. Sampling standardization has been extensively applied to remedy the effects of uneven sampling in large datasets of fossil invertebrates. However, many vertebrate datasets are smaller, and the issue of uneven sampling has commonly been ignored, or approached using pairwise comparisons with a numerical proxy for sampling effort. Although most authors find a strong correlation between palaeodiversity and sampling proxies, weak correlation is recorded in some datasets. This has led several authors to conclude that uneven sampling does not influence our view of vertebrate macroevolution. We demonstrate that multi-variate regression models incorporating a model of underlying biological diversification, as well as a sampling proxy, fit observed sauropodomorph dinosaur palaeodiversity best. This bivariate model is a better fit than separate univariate models, and illustrates that observed palaeodiversity is a composite pattern, representing a biological signal overprinted by variation in sampling effort. Multi-variate models and other approaches that consider sampling as an essential component of palaeodiversity are central to gaining a more complete understanding of deep time vertebrate diversification.
Sibling bullying during infancy does not make wimpy adults
Authors: Sánchez-Macouzet Oscar , Drummond Hugh
Published: June 2011

Despite frequent suggestions that dominance–subordination relationships in infancy can affect subsequent agonistic potential during adult life, to our knowledge no explicit test has been made. Experiments have shown that adverse conditions during early development can have long-term effects on a variety of traits ranging from growth to competitive behaviour. In many vertebrate species, the main social setting in which the infant develops is a sibling group where competition is often mediated by a dominance hierarchy. Here, we show in a long-lived marine bird that subordination to an aggressive sibling throughout infancy does not compromise aggressiveness years later during adult life. Former junior and senior chicks of the blue-footed booby, whose typical brood of two chicks exhibits a consistent dominance–subordination relationship with strong ‘trained winner’ and ‘trained loser’ conditioning effects, did not differ in their aggressiveness while defending their nest against a conspecific intruder stimulus. Our results suggest that aggressive subordination and associated food deprivation, poor growth and elevated stress hormone during infancy do not prejudice aggressiveness of adult boobies during at least the first 13 years of life. Development of important traits such as aggressive tendencies may be buffered against the normal and predictable challenges of infancy.
Modelling human balance using switched systems with linear feedback control
Authors: Kowalczyk Piotr , Glendinning Paul , Brown Martin , Medrano-Cerda Gustavo , Dallali Houman , Shapiro Jonathan
Published: June 2011

We are interested in understanding the mechanisms behind and the character of the sway motion of healthy human subjects during quiet standing. We assume that a human body can be modelled as a single-link inverted pendulum, and the balance is achieved using linear feedback control. Using these assumptions, we derive a switched model which we then investigate. Stable periodic motions (limit cycles) about an upright position are found. The existence of these limit cycles is studied as a function of system parameters. The exploration of the parameter space leads to the detection of multi-stability and homoclinic bifurcations.
On valuing patches: estimating contributions to metapopulation growth with reverse-time capture–recapture modelling
Authors: Sanderlin Jamie S. , Waser Peter M. , Hines James E. , Nichols James D.
Published: June 2011

Metapopulation ecology has historically been rich in theory, yet analytical approaches for inferring demographic relationships among local populations have been few. We show how reverse-time multi-state capture–recapture models can be used to estimate the importance of local recruitment and interpopulation dispersal to metapopulation growth. We use ‘contribution metrics’ to infer demographic connectedness among eight local populations of banner-tailed kangaroo rats, to assess their demographic closure, and to investigate sources of variation in these contributions. Using a 7 year dataset, we show that: (i) local populations are relatively independent demographically, and contributions to local population growth via dispersal within the system decline with distance; (ii) growth contributions via local survival and recruitment are greater for adults than juveniles, while contributions involving dispersal are greater for juveniles; (iii) central populations rely more on local recruitment and survival than peripheral populations; (iv) contributions involving dispersal are not clearly related to overall metapopulation density; and (v) estimated contributions from outside the system are unexpectedly large. Our analytical framework can classify metapopulations on a continuum between demographic independence and panmixia, detect hidden population growth contributions, and make inference about other population linkage forms, including rescue effects and source–sink structures. Finally, we discuss differences between demographic and genetic population linkage patterns for our system.
Selective inactivation of adenosine A2A receptors in striatal neurons enhances working memory and reversal learning
Authors: Wei Catherine J. , Singer Philipp , Coelho Joana , Boison Detlev , Feldon Joram , Yee Benjamin K. , Chen Jiang-Fan
Published: June 2011

The adenosine A2A receptor (A2AR) is highly enriched in the striatum where it is uniquely positioned to integrate dopaminergic, glutamatergic, and other signals to modulate cognition. Although previous studies support the hypothesis that A2AR inactivation can be pro-cognitive, analyses of A2AR's effects on cognitive functions have been restricted to a small subset of cognitive domains. Furthermore, the relative contribution of A2ARs in distinct brain regions remains largely unknown. Here, we studied the regulation of multiple memory processes by brain region-specific populations of A2ARs. Specifically, we evaluated the cognitive impacts of conditional A2AR deletion restricted to either the entire forebrain (i.e., cerebral cortex, hippocampus, and striatum, fb-A2AR KO) or to striatum alone (st-A2AR KO) in recognition memory, working memory, reference memory, and reversal learning. This comprehensive, comparative analysis showed for the first time that depletion of A2AR-dependent signaling in either the entire forebrain or striatum alone is associated with two specific phenotypes indicative of cognitive flexibility—enhanced working memory and enhanced reversal learning. These selective pro-cognitive phenotypes seemed largely attributed to inactivation of striatal A2ARs as they were captured by A2AR deletion restricted to striatal neurons. Neither spatial reference memory acquisition nor spatial recognition memory were grossly affected, and no evidence for compensatory changes in striatal or cortical D1, D2, or A1 receptor expression was found. This study provides the first direct demonstration that targeting striatal A2ARs may be an effective, novel strategy to facilitate cognitive flexibility under normal and pathologic conditions.
Nicotine trained as a negative feature passes the retardation-of-acquisition and summation tests of a conditioned inhibitor
Authors: Murray Jennifer E. , Walker Andrew W. , Li Chia , Wells Nicole R. , Penrod Rachel D. , Bevins Rick A.
Published: June 2011

Nicotine functions as a negative feature in a Pavlovian discriminated goal-tracking task. Whether withholding of responding to the conditional stimulus (CS) reflects nicotine functioning as a conditioned inhibitor is unknown. Accordingly, the present research sought to determine whether nicotine trained as a negative feature passed the retardation-of-acquisition and summation tests, thus characterizing it as a pharmacological (interoceptive) conditioned inhibitor. In the retardation test, rats received either nicotine (0.4 mg/kg) or chlordiazepoxide (5 mg/kg) negative feature training in which the drug state signaled when a 15-sec light CS would not be paired with sucrose; light was paired with sucrose on intermixed saline sessions. Following acquisition of the discrimination, both groups received nicotine CS training in which sucrose was intermittently available on nicotine but not intermixed saline sessions. Acquisition of conditioned responding to the nicotine CS was slower in the nicotine negative feature group than in the chlordiazepoxide negative feature group. In the summation test, rats were assigned to either the nicotine negative feature group or a pseudoconditioning control. In this control, the light CS was paired with sucrose on half the nicotine and half the saline sessions. Both groups also received excitatory training in which a white noise CS was paired with sucrose. The summation test consisted of presenting the white noise in conjunction with nicotine. Conditioned responding evoked by the white noise was decreased in the negative feature but not the pseudoconditioning group. Combined, the results provide the first evidence that an interoceptive stimulus (nicotine) can become a conditioned inhibitor.
Differing time dependencies of object recognition memory impairments produced by nicotinic and muscarinic cholinergic antagonism in perirhinal cortex
Authors: Tinsley Chris J. , Fontaine-Palmer Nadine S. , Vincent Maria , Endean Emma P.E. , Aggleton John P. , Brown Malcolm W. , Warburton E. Clea
Published: June 2011

The roles of muscarinic and nicotinic cholinergic receptors in perirhinal cortex in object recognition memory were compared. Rats' discrimination of a novel object preference test (NOP) test was measured after either systemic or local infusion into the perirhinal cortex of the nicotinic receptor antagonist methyllycaconitine (MLA), which targets alpha-7 (α7) amongst other nicotinic receptors or the muscarinic receptor antagonists scopolamine, AFDX-384, and pirenzepine. Methyllycaconitine administered systemically or intraperirhinally before acquisition impaired recognition memory tested after a 24-h, but not a 20-min delay. In contrast, all three muscarinic antagonists produced a similar, unusual pattern of impairment with amnesia after a 20-min delay, but remembrance after a 24-h delay. Thus, the amnesic effects of nicotinic and muscarinic antagonism were doubly dissociated across the 20-min and 24-h delays. The same pattern of shorter-term but not longer-term memory impairment was found for scopolamine whether the object preference test was carried out in a square arena or a Y-maze and whether rats of the Dark Agouti or Lister-hooded strains were used. Coinfusion of MLA and either scopolamine or AFDX-384 produced an impairment profile matching that for MLA. Hence, the antagonists did not act additively when coadministered. These findings establish an important role in recognition memory for both nicotinic and muscarinic cholinergic receptors in perirhinal cortex, and provide a challenge to simple ideas about the role of cholinergic processes in recognition memory: The effects of muscarinic and nicotinic antagonism are neither independent nor additive.
Model-Based Analysis of Arabidopsis Leaf Epidermal Cells Reveals Distinct Division and Expansion Patterns for Pavement and Guard Cells
Authors: Kheibarshekan Asl Leila , Dhondt Stijn , Boudolf Véronique , Beemster Gerrit T.S. , Beeckman Tom , Inzé Dirk , Govaerts Willy , De Veylder Lieven
Published: June 2011

To efficiently capture sunlight for photosynthesis, leaves typically develop into a flat and thin structure. This development is driven by cell division and expansion, but the individual contribution of these processes is currently unknown, mainly because of the experimental difficulties to disentangle them in a developing organ, due to their tight interconnection. To circumvent this problem, we built a mathematic model that describes the possible division patterns and expansion rates for individual epidermal cells. This model was used to fit experimental data on cell numbers and sizes obtained over time intervals of 1 d throughout the development of the first leaf pair of Arabidopsis (Arabidopsis thaliana). The parameters were obtained by a derivative-free optimization method that minimizes the differences between the predicted and experimentally observed cell size distributions. The model allowed us to calculate probabilities for a cell to divide into guard or pavement cells, the maximum size at which it can divide, and its average cell division and expansion rates at each point during the leaf developmental process. Surprisingly, average cell cycle duration remained constant throughout leaf development, whereas no evidence for a maximum cell size threshold for cell division of pavement cells was found. Furthermore, the model predicted that neighboring cells of different sizes within the epidermis expand at distinctly different relative rates, which could be verified by direct observations. We conclude that cell division seems to occur independently from the status of cell expansion, whereas the cell cycle might act as a timer rather than as a size-regulated machinery.
The Arabidopsis Leucine-Rich Repeat Receptor–Like Kinases BAK1/SERK3 and BKK1/SERK4 Are Required for Innate Immunity to Hemibiotrophic and Biotrophic Pathogens
Authors: Roux Milena , Schwessinger Benjamin , Albrecht Catherine , Chinchilla Delphine , Jones Alexandra , Holton Nick , Malinovsky Frederikke Gro , Tör Mahmut , de Vries Sacco , Zipfel Cyril
Published: June 2011

Recognition of pathogen-associated molecular patterns (PAMPs) by surface-localized pattern recognition receptors (PRRs) constitutes an important layer of innate immunity in plants. The leucine-rich repeat (LRR) receptor kinases EF-TU RECEPTOR (EFR) and FLAGELLIN SENSING2 (FLS2) are the PRRs for the peptide PAMPs elf18 and flg22, which are derived from bacterial EF-Tu and flagellin, respectively. Using coimmunoprecipitation and mass spectrometry analyses, we demonstrated that EFR and FLS2 undergo ligand-induced heteromerization in planta with several LRR receptor-like kinases that belong to the SOMATIC-EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) family, including BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1/SERK3 (BAK1/SERK3) and BAK1-LIKE1/SERK4 (BKK1/SERK4). Using a novel bak1 allele that does not exhibit pleiotropic defects in brassinosteroid and cell death responses, we determined that BAK1 and BKK1 cooperate genetically to achieve full signaling capability in response to elf18 and flg22 and to the damage-associated molecular pattern AtPep1. Furthermore, we demonstrated that BAK1 and BKK1 contribute to disease resistance against the hemibiotrophic bacterium Pseudomonas syringae and the obligate biotrophic oomycete Hyaloperonospora arabidopsidis. Our work reveals that the establishment of PAMP-triggered immunity (PTI) relies on the rapid ligand-induced recruitment of multiple SERKs within PRR complexes and provides insight into the early PTI signaling events underlying this important layer of plant innate immunity.
Live Cell Imaging Reveals Structural Associations between the Actin and Microtubule Cytoskeleton in Arabidopsis
Authors: Sampathkumar Arun , Lindeboom Jelmer J. , Debolt Seth , Gutierrez Ryan , Ehrhardt David W. , Ketelaar Tijs , Persson Staffan
Published: June 2011

In eukaryotic cells, the actin and microtubule (MT) cytoskeletal networks are dynamic structures that organize intracellular processes and facilitate their rapid reorganization. In plant cells, actin filaments (AFs) and MTs are essential for cell growth and morphogenesis. However, dynamic interactions between these two essential components in live cells have not been explored. Here, we use spinning-disc confocal microscopy to dissect interaction and cooperation between cortical AFs and MTs in Arabidopsis thaliana, utilizing fluorescent reporter constructs for both components. Quantitative analyses revealed altered AF dynamics associated with the positions and orientations of cortical MTs. Reorganization and reassembly of the AF array was dependent on the MTs following drug-induced depolymerization, whereby short AFs initially appeared colocalized with MTs, and displayed motility along MTs. We also observed that light-induced reorganization of MTs occurred in concert with changes in AF behavior. Our results indicate dynamic interaction between the cortical actin and MT cytoskeletons in interphase plant cells.
Aroma impact compounds in Liuyang douchi, a Chinese traditional fermented soya bean product
Authors: Chen Qing‐Chan , Xu Yong‐Xia , Wu Peng , Xu Xiao‐Yun , Pan Si‐Yi
Published: June 2011

Two procedures for the isolation of volatiles from Liuyang douchi, the typical representative of Aspergillus‐type douchi, were compared: solid‐phase microextraction (SPME) and simultaneous steam distillation extraction (SDE). Compared with SDE, the SPME extract was judged to be more similar to the aroma of the starting materials. The aroma impact compounds of the SPME extract were then determined using GC–MS and gas chromatography–olfactometry (GC–O). From the detection frequencies and the intensities of the peaks, twenty‐eight volatile compounds were detected in the sniffing port of GC–O. Identification of twenty‐two aroma impact compounds was based on the combination of sensory descriptors, linear retention index values, GC–MS data and co‐injection of authentic standards. Compounds with the greatest aroma intensities include 2‐methyl‐butanal, ethyl 2‐methylbutyrate, isoamyl acetate, 2,6‐dimethylpyrazine, 1‐octen‐3‐ol, 2‐pentyl furan, benzeneacetaldehyde, phenylethyl alcohol, phenethyl acetate and phenethyl butyrate. These compounds might have an impact on the overall aroma of Liuyang douchi.
Response surface optimisation of spray dryer operational parameters for low‐phenylalanine skim milk powder
Authors: Amiri‐Rigi Atefeh , Mohammadifar Mohammad A. , Emam‐Djomeh Zahra , Mohammadi Mehrdad
Published: June 2011

The aim of this study was to optimise the spray‐drying process for low‐phenylalanine (low‐Phe) milk. Influence of inlet air temperature (100, 150 and 200 °C), feed flow rate (5, 10 and 15 mL min−1) and air flow rate (400, 600 and 800 L h−1) on the solubility, yield, water activity and moisture content (MC) of the milk powder were assessed using response surface methodology. The following optimum process parameters were determined: inlet air temperature of 160 °C, feed flow rate of 8 mL min−1 and air flow rate of 400 L h−1. The predicted values for the solubility, yield, water activity and MC were 98.77%, 88.08%, 0.263% and 5.48%, respectively. With the optimum parameters, the experimental values for the solubility, yield, water activity and MC were 97.56 ± 0.03%, 87.00 ± 0.10%, 0.26 ± 0.01% and 5.53 ± 0.08%, respectively. The similarity of the experimental results to the predicted values verified the models.