bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines
Authors: Wentrup Curt
Published: August 2013

Chemical activation (the formation of ‘hot’ molecules due to chemical reactions) is ubiquitous in flash vacuum thermolysis (FVT) reactions, and awareness of this phenomenon is indispensable when designing synthetically useful gas-phase reactions. Chemical activation is particularly prevalent in azide chemistry because the interesting singlet nitrenes are high-energy intermediates, and their reactions are highly exothermic. Consequently, chemical activation is observed in the isomerization of methylnitrene CH3N to methylenimine (methanimine) CH2=NH, facilitating the elimination of hydrogen to form HCN or HNC. Rearrangements of phenylnitrene, 1- and 2-naphthylnitrenes, and 2-, 3- and 4-pyridylnitrenes afford cyanocyclopentadiene, 3- and 2-cyanoindenes, and 2- and 3-cyanopyrroles, all showing the effects of chemical activation by undergoing facile interconversion of isomers. Chemical activation can often be reduced or removed entirely by increasing the pressure, thereby promoting collisional deactivation. Larger molecules having more degrees of freedom are better able to dissipate excess energy; therefore the effects of chemical activation are less pronounced or completely absent in the formation of 3-cyanoindole and 1-cyanobenzimidazoles from 3- and 4-quinolylnitrenes and 4-quinazolinylnitrenes, respectively. In compounds possessing nitro groups, chemical activation can cause the loss of the nitro group at nominal temperatures far below those normally needed to cleave the C-NO2 bond.
Identification of trophic niches of subterranean diving beetles in a calcrete aquifer by DNA and stable isotope analyses
Authors: Bradford Tessa M. , Humphreys William F. , Austin Andrew D. , Cooper Steven J. B.
Published: August 2013

The Yilgarn calcrete aquifers in Western Australia are an interesting system for investigating the process of speciation within subterranean habitats, because of the limited opportunities for dispersal between isolated calcretes. The presence of different-sized diving beetles (Dytiscidae) in separate calcretes, including sympatric sister-species pairs, suggests that species may have evolved within calcretes by an adaptive shift as a result of ecological-niche differentiation. We have studied the potential for trophic niche partitioning in a sister triplet of diving beetles, of distinctly different sizes, from a single aquifer. Fragments of the mitochondrial COI gene, specific to known species of amphipods and copepods, were polymerase chain reaction-amplified from each of the three beetle species, indicating that there is an overlap in their prey items. Significant differences were found in the detected diets of the three species, and results showed a propensity for prey preferences of amphipods by the large beetles and one species of copepod for the small beetles. A terrestrial source of carbon to the calcrete was suggested by stable isotope analyses. The combined approach of molecular, stable isotope and behavioural studies have provided insight into the trophic ecology of this difficult-to-access environment, providing a framework for more fine-scale analyses of the diet of different-sized species to examine speciation underground.
Ecological effects of trawling fisheries on the eastern Australian continental shelf: a modelling study
Authors: Savina Marie , Forrest Robyn E , Fulton Elizabeth A , Condie Scott A
Published: August 2013

The New South Wales Offshore Trawl Fishery began to expand in 1976, following a large exploratory trawl survey carried out on the fishing grounds of the upper continental slope. This survey was repeated 20 years later with the same vessel and using similar protocols. Comparison of the survey results suggested that the overall fish biomass in the survey area had substantially decreased after 20 years. We have implemented an ecosystem model using the Atlantis framework to (1) emulate the evolution of the shelf ecosystems from 1976 to 1996 and (2) explore the effects of alternative fishing pressures on those ecosystems. We have been able to emulate the observed decline of most of the commercial groups of fish species in the Offshore Trawl Fishery, including sharks, and our results confirmed that fishing pressure was the most important cause of these observed changes. Fourteen fishing scenarios highlight the competing nature of some of the ecosystem-based sustainable fishing objectives.
A combination of directing groups and chiral anion phase-transfer catalysis for enantioselective fluorination of alkenes
Authors: Wu Jeffrey , Wang Yi-Ming , Drljevic Amela , Rauniyar Vivek , Phipps Robert J. , Toste F. Dean
Published: August 2013

We report a catalytic enantioselective electrophilic fluorination of alkenes to form tertiary and quaternary C(sp3)-F bonds and generate β-amino- and β-aryl-allylic fluorides. The reaction takes advantage of the ability of chiral phosphate anions to serve as solid–liquid phase transfer catalysts and hydrogen bond with directing groups on the substrate. A variety of heterocyclic, carbocyclic, and acyclic alkenes react with good to excellent yields and high enantioselectivities. Further, we demonstrate a one-pot, tandem dihalogenation–cyclization reaction, using the same catalytic system twice in series, with an analogous electrophilic brominating reagent in the second step.
Conformational states and recognition of amyloidogenic peptides of human insulin-degrading enzyme
Authors: McCord Lauren A. , Liang Wenguang G. , Dowdell Evan , Kalas Vasilios , Hoey Robert J. , Koide Akiko , Koide Shohei , Tang Wei-Jen
Published: August 2013

Insulin-degrading enzyme (IDE) selectively degrades the monomer of amyloidogenic peptides and contributes to clearance of amyloid β (Aβ). Thus, IDE retards the progression of Alzheimer’s disease. IDE possesses an enclosed catalytic chamber that engulfs and degrades its peptide substrates; however, the molecular mechanism of IDE function, including substrate access to the chamber and recognition, remains elusive. Here, we captured a unique IDE conformation by using a synthetic antibody fragment as a crystallization chaperone. An unexpected displacement of a door subdomain creates an ∼18-Å opening to the chamber. This swinging-door mechanism permits the entry of short peptides into the catalytic chamber and disrupts the catalytic site within IDE door subdomain. Given the propensity of amyloidogenic peptides to convert into β-strands for their polymerization into amyloid fibrils, they also use such β-strands to stabilize the disrupted catalytic site resided at IDE door subdomain for their degradation by IDE. Thus, action of the swinging door allows IDE to recognize amyloidogenicity by substrate-induced stabilization of the IDE catalytic cleft. Small angle X-ray scattering (SAXS) analysis revealed that IDE exists as a mixture of closed and open states. These open states, which are distinct from the swinging door state, permit entry of larger substrates (e.g., Aβ, insulin) to the chamber and are preferred in solution. Mutational studies confirmed the critical roles of the door subdomain and hinge loop joining the N- and C-terminal halves of IDE for catalysis. Together, our data provide insights into the conformational changes of IDE that govern the selective destruction of amyloidogenic peptides.
Structure of the processive rubber oxygenase RoxA from
Xanthomonas
sp
Authors: Seidel Julian , Schmitt Georg , Hoffmann Maren , Jendrossek Dieter , Einsle Oliver
Published: August 2013

Rubber oxygenase A (RoxA) is one of only two known enzymes able to catalyze the oxidative cleavage of latex for biodegradation. RoxA acts as a processive dioxygenase to yield the predominant product 12-oxo-4,8-dimethyl-trideca-4,8-diene-1-al (ODTD), a tri-isoprene unit. Here we present a structural analysis of RoxA from
Xanthomonas
sp. strain 35Y at a resolution of 1.8 Å. The enzyme is a 75-kDa diheme
c
-type cytochrome with an unusually low degree of secondary structure. Analysis of the heme group arrangement and peptide chain topology of RoxA confirmed a distant kinship with diheme peroxidases of the CcpA family, but the proteins are functionally distinct, and the extracellular RoxA has evolved to have twice the molecular mass by successively accumulating extensions of peripheral loops. RoxA incorporates both oxygen atoms of its cosubstrate dioxygen into the rubber cleavage product ODTD, and we show that RoxA is isolated with O
2
stably bound to the active site heme iron. Activation and cleavage of O
2
require binding of polyisoprene, and thus the substrate needs to use hydrophobic access channels to reach the deeply buried active site of RoxA. The location and nature of these channels support a processive mechanism of latex cleavage.
Sea surface height evidence for long-term warming effects of tropical cyclones on the ocean
Authors: Mei Wei , Primeau François , McWilliams James C. , Pasquero Claudia
Published: August 2013

Tropical cyclones have been hypothesized to influence climate by pumping heat into the ocean, but a direct measure of this warming effect is still lacking. We quantified cyclone-induced ocean warming by directly monitoring the thermal expansion of water in the wake of cyclones, using satellite-based sea surface height data that provide a unique way of tracking the changes in ocean heat content on seasonal and longer timescales. We find that the long-term effect of cyclones is to warm the ocean at a rate of 0.32 ± 0.15 PW between 1993 and 2009, i.e., ∼23 times more efficiently per unit area than the background equatorial warming, making cyclones potentially important modulators of the climate by affecting heat transport in the ocean–atmosphere system. Furthermore, our analysis reveals that the rate of warming increases with cyclone intensity. This, together with a predicted shift in the distribution of cyclones toward higher intensities as climate warms, suggests the ocean will get even warmer, possibly leading to a positive feedback.
Elucidation of the anaerobic pathway for the corrin component of cobalamin (vitamin B
12
)
Authors: Moore Simon J. , Lawrence Andrew D. , Biedendieck Rebekka , Deery Evelyne , Frank Stefanie , Howard Mark J. , Rigby Stephen E. J. , Warren Martin J.
Published: August 2013

It has been known for the past 20 years that two pathways exist in nature for the de novo biosynthesis of the coenzyme form of vitamin B
12
, adenosylcobalamin, representing aerobic and anaerobic routes. In contrast to the aerobic pathway, the anaerobic route has remained enigmatic because many of its intermediates have proven technically challenging to isolate, because of their inherent instability. However, by studying the anaerobic cobalamin biosynthetic pathway in
Bacillus megaterium
and using homologously overproduced enzymes, it has been possible to isolate all of the intermediates between uroporphyrinogen III and cobyrinic acid. Consequently, it has been possible to detail the activities of purified cobinamide biosynthesis (Cbi) proteins CbiF, CbiG, CbiD, CbiJ, CbiET, and CbiC, as well as show the direct in vitro conversion of 5-aminolevulinic acid into cobyrinic acid using a mixture of 14 purified enzymes. This approach has resulted in the isolation of the long sought intermediates, cobalt-precorrin-6A and -6B and cobalt-precorrin-8. EPR, in particular, has proven an effective technique in following these transformations with the cobalt(II) paramagnetic electron in the d
yz
orbital, rather than the typical d
z
2. This result has allowed us to speculate that the metal ion plays an unexpected role in assisting the interconversion of pathway intermediates. By determining a function for all of the pathway enzymes, we complete the tool set for cobalamin biosynthesis and pave the way for not only enhancing cobalamin production, but also design of cobalamin derivatives through their combinatorial use and modification.
Structural basis of the C1q/C1s interaction and its central role in assembly of the C1 complex of complement activation
Authors: Venkatraman Girija Umakhanth , Gingras Alexandre R. , Marshall Jamie E. , Panchal Roshni , Sheikh Md. Arif , Harper James A. J. , Gál Péter , Schwaeble Wilhelm J. , Mitchell Daniel A. , Moody Peter C. E. , Wallis Russell
Published: August 2013

Complement component C1, the complex that initiates the classical pathway of complement activation, is a 790-kDa assembly formed from the target-recognition subcomponent C1q and the modular proteases C1r and C1s. The proteases are elongated tetramers that become more compact when they bind to the collagen-like domains of C1q. Here, we describe a series of structures that reveal how the subcomponents associate to form C1. A complex between C1s and a collagen-like peptide containing the C1r/C1s-binding motif of C1q shows that the collagen binds to a shallow groove via a critical lysine side chain that contacts Ca2+-coordinating residues. The data explain the Ca2+-dependent binding mechanism, which is conserved in C1r and also in mannan-binding lectin-associated serine proteases, the serine proteases of the lectin pathway activation complexes. In an accompanying structure, C1s forms a compact ring-shaped tetramer featuring a unique head-to-tail interaction at its center that replicates the likely arrangement of C1r/C1s polypeptides in the C1 complex. Additional structures reveal how C1s polypeptides are positioned to enable activation by C1r and interaction with the substrate C4 inside the cage-like assembly formed by the collagenous stems of C1q. Together with previously determined structures of C1r fragments, the results reported here provide a structural basis for understanding the early steps of complement activation via the classical pathway.
Algebraic theory of curvettes and dicriticals
Authors: Abhyankar Shreeram , Bartolo Enrique
Published: August 2013

We relate curvettes with dicriticals.
Origins of bone repair in the armour of fossil fish: response to a deep wound by cells depositing dentine instead of dermal bone
Authors: Johanson Zerina , Smith Moya , Kearsley Anton , Pilecki Peter , Mark-Kurik Elga , Howard Charles
Published: August 2013

The outer armour of fossil jawless fishes (Heterostraci) is, predominantly, a bone with a superficial ornament of dentine tubercles surrounded by pores leading to flask-shaped crypts (ampullae). However, despite the extensive bone present in these early dermal skeletons, damage was repaired almost exclusively with dentine. Consolidation of bone, by dentine invading and filling the vascular spaces, was previously recognized in
Psammolepis
and other heterostracans but was associated with ageing and dermal shield wear (reparative). Here, we describe wound repair by deposition of dentine directly onto a bony scaffold of fragmented bone. An extensive wound response occurred from massive deposition of dentine (reactionary), traced from tubercle pulp cavities and surrounding ampullae. These structures may provide the cells to make reparative and reactionary dentine, as in mammalian teeth today in response to stimuli (functional wear or damage). We suggest in
Psammolepis
, repair involved mobilization of these cells in response to a local stimulatory mechanism, for example, predator damage. By comparison, almost no new bone is detected in repair of the
Psammolepis
shield. Dentine infilling bone vascular tissue spaces of both abraded dentine and wounded bone suggests that recruitment of this process has been evolutionarily conserved over 380 Myr and precedes osteogenic skeletal repair.
Evidence of a component Allee effect driven by predispersal seed predation in a plant (
Pedicularis rex
, Orobanchaceae)
Authors: Xia Jing , Sun ShiGuo , Liu GuiHua
Published: August 2013

A small or sparse population may suffer a reduction in fitness owing to Allee effects. Here, we explored effects of plant density on pollination, reproduction and predation in the alpine herb
Pedicularis rex
over two years. We did not detect a significant difference in the pollination rate or fecundity (fruit set and the initial seed set) before predation between sparse and dense patches in either year, indicating no pollination-driven Allee effect. However, dense patches experienced significantly fewer attacks by predispersal seed predators in both years, resulting in a significantly decreased realized fecundity (final seed set), suggesting a component Allee effect driven by predispersal seed predation. Predation-driven Allee effects have been predicted by many models and demonstrated for a range of animals, but there is scant evidence for such effects in plants. Our study provides strong evidence of a component Allee effect driven by predation in a plant species.
Shallow gene pools in the high intertidal: extreme loss of genetic diversity in viviparous sea stars (
Parvulastra
)
Authors: Keever Carson C. , Puritz Jonathan B. , Addison Jason A. , Byrne Maria , Grosberg Richard K. , Toonen Robert J. , Hart Michael W.
Published: August 2013

We document an extreme example of reproductive trait evolution that affects population genetic structure in sister species of
Parvulastra
cushion stars from Australia. Self-fertilization by hermaphroditic adults and brood protection of benthic larvae causes strong inbreeding and range-wide genetic poverty. Most samples were fixed for a single allele at nearly all nuclear loci; heterozygotes were extremely rare (0.18%); mitochondrial DNA sequences were more variable, but few populations shared haplotypes in common. Isolation-with-migration models suggest that these patterns are caused by population bottlenecks (relative to ancestral population size) and low gene flow. Loss of genetic diversity and low potential for dispersal between high-intertidal habitats may have dire consequences for extinction risk and potential for future adaptive evolution in response to climate and other selective agents.
Density-mediated carry-over effects explain variation in breeding output across time in a seasonal population
Authors: Betini Gustavo S. , Griswold Cortland K. , Norris D. Ryan
Published: August 2013

In seasonal environments, where density dependence can operate throughout the annual cycle, vital rates are typically considered to be a function of the number of individuals at the beginning of each season. However, variation in density in the previous season could also cause surviving individuals to be in poor physiological condition, which could carry over to influence individual success in the following season.We examine this hypothesis using replicated populations ofDrosophila melanogaster, the common fruitfly, over 23 non-overlapping generations with distinct breeding and non-breeding seasons. We found that the density at the beginning of the non-breeding season negatively affected the fresh weight of individuals that survived the non-breeding season and resulted in a 25% decrease inper capitabreeding output among those that survived to the next season to breed. At the population level,per capitabreeding output was best explained by a model that incorporated density at the beginning of the previous non-breeding season (carry-over effect, COE) and density at the beginning of the breeding season. Our results support the idea that density-mediated COEs are critical for understanding population dynamics in seasonal environments.
More than a safety line: jump-stabilizing silk of salticids
Authors: Chen Yung-Kang , Liao Chen-Pan , Tsai Feng-Yueh , Chi Kai-Jung
Published: August 2013

Salticids are diurnal hunters known for acute vision, remarkable predatory strategies and jumping ability. Like other jumpers, they strive for stability and smooth landings. Instead of using inertia from swinging appendages or aerodynamic forces by flapping wings as in other organisms, we show that salticids use a different mechanism for in-air stability by using dragline silk, which was previously believed to function solely as a safety line. Analyses from high-speed images of jumps by the salticidHasarius adansonidemonstrate that despite being subject to rearward pitch at take-off, spiders with dragline silk can change body orientation in the air. Instantaneous drag and silk forces calculated from kinematic data further suggest a comparable contribution to deceleration and energy dissipation, and reveal that adjustments by the spider to the silk force can reverse its body pitch for a predictable and optimal landing. Without silk, upright-landing spiders would slip or even tumble, deferring completion of landing. Thus, for salticids, dragline silk is critical for dynamic stability and prey-capture efficiency. The dynamic functioning of dragline silk revealed in this study can advance the understanding of silk's physiological control over material properties and its significance to spider ecology and evolution, and also provide inspiration for future manoeuvrable robot designs.
Effect of counterface roughness on adhesion of mushroom-shaped microstructure
Authors: Kasem Haytam , Varenberg Michael
Published: August 2013

In this study, the effect of the substrate roughness on adhesion of mushroom-shaped microstructure was experimentally investigated. To do so, 12 substrates having different isotropic roughness were prepared from the same material by replicating topography of different surfaces. The pull-off forces generated by mushroom-shaped microstructure in contact with the tested substrates were measured and compared with the pull-off forces generated by a smooth reference. It was found that classical roughness parameters, such as average roughness (
R
a
) and others, cannot be used to explain topography-related variation in pull-off force. This has led us to the development of an integrated roughness parameter capable of explaining results of pull-off measurements. Using this parameter, we have also found that there is a critical roughness, above which neither smooth nor microstructured surface could generate any attachment force, which may have important implications on design of both adhesive and anti-adhesive surfaces.
Theoretical enhancement of the Gaussian filtering of engineering surfaces
Authors: Whitehouse David J.
Published: August 2013

This study is an extension of the current use of Gaussian filters to smooth surface texture waveforms. It suggests an extension using Hermite polynomials to improve the definition of boundary lines and edges in the geometry of structured surfaces, and to enhance scratch and flaw detection. In addition, a new filtering concept is introduced to enhance the detection of boundary lines and edges and to improve the understanding of their local geometry, thereby minimizing the uncertainties in structured surface filtering and characterization. How this approach can incorporate the measurement of free-form surfaces as well as help improve the fidelity in scratch and crack detection, positioning and characterization is also discussed.
Unpredicted impacts of insect endosymbionts on interactions between soil organisms, plants and aphids
Authors: Hackett Sean C. , Karley Alison J. , Bennett Alison E.
Published: August 2013

Ecologically significant symbiotic associations are frequently studied in isolation, but such studies of two-way interactions cannot always predict the responses of organisms in a community setting. To explore this issue, we adopt a community approach to examine the role of plant–microbial and insect–microbial symbioses in modulating a plant–herbivore interaction. Potato plants were grown under glass in controlled conditions and subjected to feeding from the potato aphid
Macrosiphum euphorbiae
. By comparing plant growth in sterile, uncultivated and cultivated soils and the performance of
M. euphorbiae
clones with and without the facultative endosymbiont
Hamiltonella defensa
, we provide evidence for complex indirect interactions between insect– and plant–microbial systems. Plant biomass responded positively to the live soil treatments, on average increasing by 15% relative to sterile soil, while aphid feeding produced shifts (increases in stem biomass and reductions in stolon biomass) in plant resource allocation irrespective of soil treatment. Aphid fecundity also responded to soil treatment with aphids on sterile soil exhibiting higher fecundities than those in the uncultivated treatment. The relative allocation of biomass to roots was reduced in the presence of aphids harbouring
H. defensa
compared with plants inoculated with
H. defensa
-free aphids and aphid-free control plants. This study provides evidence for the potential of plant and insect symbionts to shift the dynamics of plant–herbivore interactions.
The evolutionary ecology of early weaning in Kilimanjaro, Tanzania
Authors: Wander Katherine , Mattison Siobhán M.
Published: August 2013

Public health recommendations promote prolonged breastfeeding of all children; however, parental investment (PI) theory predicts that breastfeeding will be allocated among a mothers' offspring to maximize her reproductive success. We evaluated PI in terms of risk for weaning before age two among 283 children in Kilimanjaro, Tanzania. Results demonstrate: (i) a Trivers–Willard effect—high socioeconomic status (SES) females and low SES males were more likely to be weaned early; (ii) later-born children were less likely to be weaned early; (iii) higher birthweight children were less likely to be weaned early, and (iv) no effect of cattle (a source of supplementary milk) ownership. These associations were largely independent and remained significant in models controlling for potential confounders; however, the inverse association between early weaning and birth order lost significance in the model containing birthweight. These patterns were observed despite public health recommendations encouraging breastfeeding for at least two years.
Reconsidering the importance of the past in predator–prey models: both numerical and functional responses depend on delayed prey densities
Authors: Li Jiqiu , Fenton Andy , Kettley Lee , Roberts Phillip , Montagnes David J. S.
Published: August 2013

We propose that delayed predator–prey models may provide superficially acceptable predictions for spurious reasons. Through experimentation and modelling, we offer a new approach: using a model experimental predator–prey system (the ciliates
Didinium
and
Paramecium
), we determine the influence of past-prey abundance at a fixed delay (approx. one generation) on both functional and numerical responses (i.e. the influence of present : past-prey abundance on ingestion and growth, respectively). We reveal a nonlinear influence of past-prey abundance on both responses, with the two responding differently. Including these responses in a model indicated that delay in the numerical response drives population oscillations, supporting the accepted (but untested) notion that reproduction, not feeding, is highly dependent on the past. We next indicate how delays impact short- and long-term population dynamics. Critically, we show that although superficially the standard (parsimonious) approach to modelling can reasonably fit independently obtained time-series data, it does so by relying on biologically unrealistic parameter values. By contrast, including our fully parametrized delayed density dependence provides a better fit, offering insights into underlying mechanisms. We therefore present a new approach to explore time-series data and a revised framework for further theoretical studies.
Lower hypoxia thresholds of cuttlefish early life stages living in a warm acidified ocean
Authors: Rosa Rui , Trübenbach Katja , Repolho Tiago , Pimentel Marta , Faleiro Filipa , Boavida-Portugal Joana , Baptista Miguel , Lopes Vanessa M. , Dionísio Gisela , Leal Miguel Costa , Calado Ricardo , Pörtner Hans O.
Published: August 2013

The combined effects of future ocean acidification and global warming on the hypoxia thresholds of marine biota are, to date, poorly known. Here, we show that the future warming and acidification scenario led to shorter embryonic periods, lower survival rates and the enhancement of premature hatching in the cuttlefishSepia officinalis. Routine metabolic rates increased during the embryonic period, but environmental hypercapnia significantly depressed pre-hatchling's energy expenditures rates (independently of temperature). During embryogenesis, there was also a significant rise in the carbon dioxide partial pressure in the perivitelline fluid (PVF), bicarbonate levels, as well as a drop in pH and oxygen partial pressure (pO2). The critical partial pressure (i.e. hypoxic threshold) of the pre-hatchlings was significantly higher than the PVF oxygen partial pressure at the warmer and hypercapnic condition. Thus, the record of oxygen tensions below criticalpO2in such climate scenario indicates that the already harsh conditions inside the egg capsules are expected to be magnified in the years to come, especially in populations at the border of their thermal envelope. Such a scenario promotes untimely hatching and smaller post-hatching body sizes, thus challenging the survival and fitness of early life stages.
Aberrant
Classopollis
pollen reveals evidence for unreduced (2
n
) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition
Authors: Kürschner Wolfram M. , Batenburg Sietske J. , Mander Luke
Published: August 2013

Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type
Classopollis
extracted from sediments of the Triassic–Jurassic transition, 200 Ma.
Classopollis
producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen
Classopollis
tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2
n
) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis.
Numbers count: caste‐specific component Allee effects and their interactions
Authors: Hughes William
Published: August 2013

A queen and worker of the Argentine ant Linepithema humile. The numbers of queens and of workers in a colony each have positive relationships with components of fitness. Photo and copyright: Alexander Wild.

image

A queen and worker of the Argentine ant Linepithema humile. The numbers of queens and of workers in a colony each have positive relationships with components of fitness. Photo and copyright: Alexander Wild.

In Focus: Luque, G., Giraud, T. & Courchamp, F. (2013) . Journal of Animal Ecology,. 82, 956–965.

Allee effects, positive relationships between fitness and the number or density of conspecifics, are surprisingly widespread and are of profound importance for understanding ecological dynamics. Lucque et al. (2013) provide the first explicit demonstration of Allee effects in a social insect. Using laboratory colonies of the Argentine ant, they show that there are component Allee effects of both workers and queens which interact with negative frequency‐dependent effects. Such Allee effects are central to the ecology and evolution of social insects, the societies of which provide a rich, experimentally tractable resource for understanding the mechanisms and impact of Allee effects.
Nonword repetition and phoneme elision skills in school‐age children who do and do not stutter
Authors: Sasisekaran Jayanthi , Byrd Courtney
Published: August 2013

Nonword repetition and phoneme elision represent the combined influence of several speech and language processes. In the present study we investigated nonword repetition and phoneme elision performance in school‐age children who stutter (CWS) and children who do not stutter (CNS). Participants were 14 CWS (mean = 11.7 years, SD = 2.1 years) and age‐ and sex‐matched CNS (mean = 11.8 years, SD = 2.0 years). Each talker group was further subdivided into two age groups: younger (N = 7; 8–11.5 years) and older (N = 7; 11.6–15 years). Repeated‐measures analyses were conducted on the accuracy and response time (in seconds) data. In nonword repetition, the CWS showed a trend for lower per cent of correct phonemes at the two‐syllable level compared with the CNS. In phoneme elision, the younger CWS showed a significantly lower accuracy rate than the older CWS at the two‐ and three‐syllable nonword lengths, while similar differences were not evident between the younger versus older CNS at any of the nonword lengths. No accuracy difference in phoneme elision was noted between the two talker groups. Group differences in speech initiation times were also not evident in either of the tasks. Findings from nonword repetition offer tentative support for difficulties experienced by school‐age CWS in phonemic encoding/working memory abilities. Findings from the phoneme elision task suggest a complex pattern of age‐dependent performance by the CWS. Comparison of response accuracy and speech initiation times in both the tasks failed to show speed–accuracy trade‐off strategies in either of the groups.
It takes Two to Tango? Understanding the Co‐production of Public Services by Integrating the Services Management and Public Administration Perspectives
Authors: Osborne Stephen P. , Strokosch Kirsty
Published: August 2013

We propose an important theoretical development for our understanding of the co‐production of public services. It combines the insights from both public administration and services management theory to produce a novel typology of co‐production. This clarifies its role at the operational and strategic levels, as well as its potential for transformational change in public services. Understanding co‐production in this way provides a basis through which to explore a whole range of dimensions of co‐production that were previously undifferentiated.
Beyond Acceptance and Resistance: Entrepreneurial Change Agency Responses in Policy Implementation
Authors: McDermott Aoife M. , Fitzgerald Louise , Buchanan David A.
Published: August 2013

In this paper we explore how the implementation of public policy can differ from that mandated, and we argue that such departures are not necessarily a problem. Organizational change faces theoretical tension between considering non‐acceptance behaviours as ‘resistance’ and requiring change recipients to tailor and adapt change agendas to fit local contexts. This tension is particularly salient in the public sector, due to the mandated nature of much public reform. We compare the implementation of policy change in four hospital case studies in two countries (Ireland and the UK). Based on interviews with 68 staff across the four cases, we identify how change recipients can react to, translate and contribute to policy change initiatives. Our findings challenge a straightforward distinction between change agents and change recipients, showing how ‘first‐order’ recipients can act as ‘second‐order’ change agents. Entrepreneurial second‐order change agents use locally contextualized change agency to tailor and embellish policy mandates. We distinguish between ‘adaptors’, who make appropriate local adjustments, and ‘extrapreneurs’ who add extra dimensions to mandated change. This evidence suggests replacing the traditional ‘acceptance–resistance’ dichotomy with a continuum of responses to mandated policy, identifying how public sector actors can variously avoid, abstain, adopt, adapt or add to change agendas.
Politics of the Corporation
Authors: Veldman Jeroen
Published: August 2013

The corporate form and its capacity for agency is recognized in political theory, but not adequately understood. As a result, important shifts in the relative position of the state and the corporate form are not addressed. Starting with a historical exploration of the theory of the corporation, I show that the corporate form relies on multiple theoretical backgrounds, which makes it inconsistent. An important part of this inconsistency is the dominance of a post‐1970s theory of the corporate form, which formed the background for New Public Management. This theory supported a reduced status of the state and its regulatory powers and an increase of the relative power of the corporate form. I evaluate some consequences of this inconsistent theory for the contemporary debate with regard to the ‘demise of the state’.
Similarity or Difference? The Relation between Structure and Strategy Isomorphism in Public Organizations
Authors: Villadsen Anders R.
Published: August 2013

While the organizational structures and strategies of public organizations have attracted substantial research attention among public management scholars, little research has explored how these organizational core dimensions are interconnected and influenced by pressures for similarity. In this paperIaddress this topic by exploring the relation between expenditure strategy isomorphism and structure isomorphism inDanish municipalities. Different literatures suggest that organizations exist in concurrent pressures for being similar to and different from other organizations in their field of action. It is theorized that to meet this challenge organizations may substitute increased similarity on one core dimension for increased idiosyncrasy on another, but only after a certain level of isomorphism is reached. Results of quantitative analyses support this theory and show that an inverseU‐shaped relation exists between expenditure strategy isomorphism and structure isomorphism in a longitudinal quantitative study ofDanish municipalities.
Theorizing Contemporary Public Management: International and Comparative Perspectives
Authors: Ashworth Rachel , Ferlie Ewan , Hammerschmid Gerhard , Moon M. Jae , Reay Trish
Published: August 2013

Ten years ago, the British Journal of Management devoted a special issue to public sector management. The issue identified a series of characteristics associated with public management research, most notably a strong organizational behaviour orientation, a qualitative bent and a predominant healthcare and UK focus. That special issue voiced a ‘call to arms’ for public management researchers to speak more directly to management research, elucidate a more nuanced account of public management reform, adopt a more explicit theoretical basis and become more internationally comparative. This paper provides a comment on progress against these objectives. We find that public management research has become more diverse, often characterized by an international focus and a wide range of methodological approaches. The paper echoes concerns regarding an increasingly one‐way relationship with general management studies but highlights a more reciprocal connection with organization studies. In doing so, we emphasize three sections of organization scholarship in particular − sociological institutionalism, Foucauldianism and theories of identity. We demonstrate that engagement with these perspectives has improved our understanding of public service reforms and provided opportunities for theoretical contributions beyond the field of public management. The paper concludes with reflections on future public management research.
European Retail Food Price Inflation
Authors: Lloyd Tim , McCorriston Steve , Morgan Wyn , Zgovu Evious
Published: August 2013

European Retail Food Price Inflation

Retail food price inflation has risen markedly across the EU in recent years but with substantial variation across EU Member States. Indeed, retail food inflation has varied more between Member States than between the EU‐25 and other developed countries. To some extent, this is all the more surprising given the ‘single market’ which characterises the EU but is likely to reflect the considerable differences in food chain structures and levels of economic development that exist within the EU. This article sets out the research issues associated with the experience of retail food inflation across the EU which are currently being addressed in a recently funded EU project on the ‘Transparency of Food Prices’ (TRANSFOP). Attention focuses on food chain structures, market concentration and the mis‐use of unequal bargaining power, and their implications for price transmission. As background, we outline the retail food price inflation experience over the last 20 years or so and suggest that what is key for policymakers is the role retail food price inflation plays in overall inflation. In contrast to the past, the current relatively high and persistent rates of food price inflation are likely to change the relationship between food and non‐food inflation, requiring a reassessment of policy toward food prices.
Driving Lessons: In Celebration of Public Goods
Authors: Ayer Harry
Published: August 2013

Driving Lessons: In Celebration of Public Goods

In this article I briefly describe – celebrate! – some of the wonderful public goods – tree tunnels and landscapes and architectural features encountered on driving tours, handsome historical buildings, pristine glories of mountain scenery, the wonders of English footpaths, lovely sights from a day on the Thames, and more – that my wife and I experienced on a journey through parts of Europe. For economists, public goods are characterised by the great difficulty of excluding the non‐payer and their ready availability to all once provided to anyone – national defense or a hike on a path through a pristine mountain meadow, for example. Because of these characteristics, the market system often falls short of providing what society would want, and government entities of various kinds and not‐for‐profit organisations often step in to better meet society's public goods needs. Yet, we often fail to recognise the value of even the public goods we most enjoy, perhaps in part because they come with no or only trivial out‐of‐pocket costs. Observations about the wondrous public goods we enjoyed on our European journey may help draw attention to similar benefits available to all, and heighten awareness of the role of government and not‐for‐profit institutions in making public goods available and how we might assist.
Antioxidant, Antibrowning, and Cytoprotective Activities of Ligustrum robustum (Rxob.) Blume Extract
Authors: Yu Zhi‐Long , Zeng Wei‐Cai
Published: August 2013

The antioxidant, antibrowning, and cytoprotective activities of Ligustrum robustum (Rxob.) Blume extract (LRE) were investigated and the main antioxidant component was isolated and identified. With its high content of phenols and flavonoids, the LRE showed remarkable antioxidant capacity to scavenge free radicals in vitro and to inhibit oil oxidation in a peanut oil system. Moreover, LRE was observed to inhibit tyrosinase action and browning of fresh‐cut apple slices effectively. Furthermore, the cytoprotective activity of LRE was evaluated in a human intestine model using Caco‐2 cell lines. According to the activity‐guided isolation and identification, by using column chromatography, high‐performance liquid chromatography, time‐of‐flight mass spectrometry, and nuclear magnetic resonance analyses, ursolic acid was characterized as the main antioxidant component of LRE; it showed the strongest free radical‐scavenging activity. The results suggested that L. robustum (Rxob.) Blume could be a new resource for preparing functional food and nutraceutical products for use in food and pharmacology industries.
Determination of Iriflophenone 3‐C‐β‐d‐Glucoside From Aquilaria spp. by an Indirect Competitive Enzyme‐linked Immunosorbent Assay Using a Specific Polyclonal Antibody
Authors: Putalun Waraporn , Yusakul Gorawit , Saensom Paritad , Sritularak Boonchoo , Tanaka Hiroyuki
Published: August 2013

Polyclonal antibody against iriflophenone 3‐C‐β‐d‐glucoside (IP3G), a major compound from the leaves of Aquilaria spp., was produced for the development of an enzyme‐linked immunosorbent assay (ELISA). The results showed that the antibodies were specific for IP3G. The produced antibody has low cross reactivity with iriflophenone 3,5‐C‐β‐d‐diglucopyranoside (13%), genkwanin 5‐O‐β‐primeveroside (3.55%) and no cross reactivity found in other compounds. The range of ELISA assay extends from 100 to 1560 ng/mL with coefficient of variation (CV) 1.19% to 2.07% for intra‐assay and 3.76% to 7.15% for inter‐assay precision levels. The recovery rates of IP3G in the leaves of Aquilaria spp. were in the range of 96.0% to 99.0% with CV 4.50% to 5.32%. A correlation between ELISA and high‐performance liquid chromatography methods was obtained when analysis of IP3G in the plant samples (R2 = 0.9321). These results suggest that the developed ELISA method can be applied to determine IP3G content with high specificity, rapidity, and simplicity. The developed immunosorbent assay in this study provides a useful tool for the analysis of IP3G in plant samples and products.
Mitigation of antagonistic effects on plant growth due to root co‐colonization by dark septate endophytes and ectomycorrhiza
Authors: Reininger Vanessa , Sieber Thomas N.
Published: August 2013

Dark septate endophytes (DSE) are very common root colonizers of woody plant species. Ascomycetes of the Phialocephala fortinii s.l.–Acephala applanata species complex (PAC) are the main representatives of DSE fungi in forest ecosystems. PAC and mycorrhizal fungi share the same habitat, but interactions among PAC, mycorrhizal fungi and plants are poorly understood. We compared the effects of single and dual inoculation of Norway spruce seedlings with PAC and the ectomycorrhizal (ECM) fungus Hebeloma crustuliniforme on host growth, degree of mycorrhization and density of endophytic PAC biomass. Single colonization by H. crustuliniforme or PAC significantly reduced plant biomass. Dual colonization reduced or neutralized plant growth depression caused by single fungal colonization. The degree of mycorrhization was independent on PAC colonization, and mycorrhization significantly reduced endophytic PAC biomass. Plant biomass of dually colonized plants positively correlated with PAC biomass. These results demonstrate the ability of dual inoculation of PAC and H. crustuliniforme to neutralize plant growth depression caused by single fungal inoculation. Our explanations of enhanced plant growth in dually inoculated plants are the inhibition of PAC during root colonization by the ECM mantle and ECM‐mediated access to plant growth‐promoting nutrients resulting from the mineralization of the potting medium by PAC.
How Do Auditors Address Control Deficiencies that Bias Accounting Estimates?
Authors: Mauldin Elaine G. , Wolfe Christopher J.
Published: August 2013

Auditors commonly rely on reviewing management's estimation process to audit accounting estimates. When control deficiencies bias the estimation process by creating omissions of critical inputs, standards require that auditors replace or supplement review of management's estimation process with tests that can identify the omissions. Importantly, overreliance on reviewing management's estimation process when it has been biased by a control deficiency can result in auditor acceptance of an inappropriate accounting estimate. We use an experiment to examine whether auditors recognize the insufficiency of increased sampling of a biased estimation process and their selection of alternative tests to replace or supplement review of the biased estimation process. We find that a significant minority (33 percent) of Big 4 senior auditors erroneously increase tests of management's biased estimation process. We also find that auditors have difficulty selecting alternative tests to replace or supplement review of management's biased estimation process, frequently choosing tests that are either ineffective or inefficient. Our findings suggest that auditors often reach inappropriate judgments about the capability of audit evidence to address control deficiencies and that nonsampling risk (judgment risk) may be a larger risk than auditors realize.