bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of residual carbon impurities and gallium vacancies on trapping effects in AlGaN/GaN metal insulator semiconductor high electron mobility transistors
Authors: Huber Martin , Silvestri Marco , Knuuttila Lauri , Pozzovivo Gianmauro , Andreev Andrei , Kadashchuk Andrey , Bonanni Alberta , Lundskog Anders
Published: July 2015

Effects of residual C impurities and Ga vacancies on the dynamic instabilities of AlN/AlGaN/GaN metal insulator semiconductor high electron mobility transistors are investigated. Secondary ion mass spectroscopy, positron annihilation spectroscopy, and steady state and time-resolved photoluminescence (PL) measurements have been performed in conjunction with electrical characterization and current transient analyses. The correlation between yellow luminescence (YL), C- and Ga vacancy concentrations is investigated. Time-resolved PL indicating the CN ON complex as the main source of the YL, while Ga vacancies or related complexes with C seem not to play a major role. The device dynamic performance is found to be significantly dependent on the C concentration close to the channel of the transistor. Additionally, the magnitude of the YL is found to be in agreement with the threshold voltage shift and with the on-resistance degradation. Trap analysis of the GaN buffer shows an apparent activation energy of ∼0.8 eV for all samples, pointing to a common dominating trapping process and that the growth parameters affect solely the density of trap centres. It is inferred that the trapping process is likely to be directly related to C based defects.
Actively controlled plasmonic Bragg reflector based on a graphene parallel-plate waveguide
Authors: Wang Yueke , Chen Quansheng , Shen Xinru
Published: July 2015

We investigate theoretically and numerically a graphene parallel-plate waveguide structure with two alternate chemical potentials (which can be realized by alternately applying two biased voltages to graphene). A plasmonic Bragg reflector can be formed in infrared range because of the alternate effective refractive indexes of SPPs propagating along graphene sheets. By introducing a defect into the Bragg reflector, and then the defect resonance mode can be formed. Thanks to the tunable permittivity of graphene by bias voltages, the central wavelength and bandwidth of SPPs stop band, and the wavelength of the defect mode can be tuned.
Ab initio design of CsSn(XxY 1−x)3 (X and Y = Cl, Br, and I) perovskites for photovoltaics
Authors: Deb Arpan Krishna , Kumar Vijay
Published: July 2015

Ab initio calculations on CsSnX3 perovskites and mixed halides CsSn(XxY 1−x)3, X and Y = I, Cl, and Br, show that all of them have a direct band gap of ∼1 eV which can be tuned by varying the compositions of X and Y. The optimized supercells are tetragonal, orthorhombic or monoclinic. The top of the valence band arises from hybridization of Sn 4s and halogen p valence orbitals while the bottom of the conduction band has predominantly Sn p character. Similar to organo-metallic lead halides this is expected to facilitate p-p optical transitions that are highly favourable for photoabsorption. Our results suggest that these inorganic perovskites have the desired features to achieve high efficiency of photo-response with appropriate combination of halogens.
Inhibition of the ultrasonic microjet-pits on the carbon steel in the particles-water mixtures
Authors: Yan Dayun , Wang Jiadao , Liu Fengbin
Published: July 2015

In the incubation period of ultrasonic cavitation, due to the impact of microjets on the material surface, the needle-like microjet-pits are formed. Because the formation of microjet-pits relates with the evolution of cavitation erosion on engineering materials, corresponding study will promote the understanding on the mechanism of cavitation erosion. However, little study on the microjet-pits has been carried out, especially in the particles-water mixture. In this study, we firstly demonstrated the microjet-pits on the carbon steel would be significantly inhibited by Al particles in water. Such inhibition effect indicated that particular particles might not only provide growth sites for cavitation bubbles but also affect the collapse of cavitation bubbles near a solid surface. Our study deepened the understanding on the ultrasonic cavitation erosion in the particles-water mixture.
Size-dependent deformation mechanisms in hollow silicon nanoparticles
Authors: Yang L. , Bian J. J. , Zhang H. , Niu X. R. , Wang G. F.
Published: July 2015

Even inherently brittle hollow silicon nanoparticles (NPs) can withstand larger strain to failure than solid NPs. However, the influence of wall thickness on the mechanical behavior of hollow Si NPs is not fully understood. Using molecular dynamics simulations, we investigate the compressive behavior of hollow Si NPs. Three distinct failure mechanisms of hollow NPs are uncovered, and their strength and deformability are analyzed quantitatively. For extra-thick-walled NPs, dislocations will nucleate below the contact area and cut through the particles till failure. For mid-thick-walled NPs, however, dislocations will emit from the inner surface and slip towards the outer surface. For thin-walled NPs, elastic buckling is the cause of failure. Compared to solid NPs, hollow NPs with wall thickness being around half of its outer radius can achieve significant improvement in both strength and deformability.
Piezoelectric and opto-electrical properties of silver-doped ZnO nanorods synthesized by low temperature aqueous chemical method
Authors: Nour E. S. , Echresh A. , Liu Xianjie , Broitman E. , Willander M. , Nur O.
Published: July 2015

In this paper, we have synthesized Zn1−xAgxO (x = 0, 0.03, 0.06, and 0.09) nanorods (NRs) via the hydrothermal method at low temperature on silicon substrate. The characterization and comparison between the different Zn1−xAgxO samples, indicated that an increasing Ag concentration from x = 0 to a maximum of x = 0.09; All samples show a preferred orientation of (002) direction with no observable change of morphology. As the quantity of the Ag dopant was changed, the transmittances, as well as the optical band gap were decreased. X-ray photoelectron spectroscopy data clearly indicate the presence of Ag in ZnO crystal lattice. A nanoindentation-based technique was used to measure the effective piezo-response of different concentrations of Ag for both direct and converse effects. The value of the piezoelectric coefficient (d33) as well as the piezo potential generated from the ZnO NRs and Zn1−xAgxO NRs was found to decrease with the increase of Ag fraction. The finding in this investigation reveals that Ag doped ZnO is not suitable for piezoelectric energy harvesting devices.
Successful reintroduction of red-tailed phascogale to Wadderin Sanctuary in the eastern wheatbelt of Western Australia
Authors: Short Jeff , Hide Andrew
Published: July 2015

Red-tailed phascogales (Phascogale calura) were reintroduced to Wadderin Sanctuary in the eastern wheatbelt of Western Australia in April 2009 with individuals sourced from remnant native vegetation on farmland some 180 km to the west. Their establishment was monitored initially by radio-telemetry and trapping, and subsequently by the checking of nest boxes both within and outside the sanctuary. Translocated phascogales established well and bred successfully in their first season. Phascogales remain extant at Wadderin more than five years after release and appear to be abundant and to occupy all available habitat. They have spread beyond the fenced sanctuary to adjoining woodland and to shrubland and woodland habitat in a remnant 1.4 km away. Comparison with two other reintroductions of this species (one apparently successful, one not) suggests management and habitat factors that may have contributed to the outcomes.
Distributions of neonicotinoid insecticides in the Commonwealth of Massachusetts: a temporal and spatial variation analysis for pollen and honey samples
Authors: Lu Chensheng (Alex) , Chang Chi-Hsuan , Tao Lin , Chen Mei
Published: July 2015

Environmental context Neonicotinoids are a group of widely used insecticides that have been implicated in the deterioration of honeybee health and the declining number of honeybee colonies worldwide. We wanted to find out whether neonicotinoids are commonly present in pollen and honey, which are the main food sources for bees. The results show that neonicotinoids are ubiquitous in the environment where bees foraged, and therefore could pose risks to honeybee health. Abstract It is known that honeybees are exposed to a wide variety of pesticides, including systemic neonicotinoids, through different media. Pollen might be a better matrix for assessing exposure to neonicotinoid not only because it is the protein source for bees, but also because pollen collected from foraging bees could help to establish the field-realistic levels of neonicotinoids. In this study, we aimed to assess temporal and spatial variations of neonicotinoids in pollen collected across the Commonwealth of Massachusetts. Monthly pollen samples and a honey sample were collected between April and August 2013 from 62 volunteered hives and analysed for eight neonicotinoids. We utilised the relative potency factor (RPF) method to integrate individual neonicotinoids into a single measurement of imidaclopridRPF. We then analysed the spatial and temporal variations of imidaclopridRPF in pollen using the response profile analysis. Overall, 73% of pollen and 72% of honey samples contained at least one detectable neonicotinoid. We found that 49, 20 and 4% of pollen samples contained one, two and three neonicotinoids respectively. In honey, we detected that 57 and 15% of samples contained one and two neonicotinoids respectively. Neonicotinoids as a group, or imidacloprid, in pollen exhibited no significant temporal or spatial variation, however, we found statistically significant spatial–temporal interaction differences of imidaclopridRPF concentrations. Considering the ubiquitous of neonicotinoids in the environment and their effects on bees at the sub-lethal levels, it is prudent to identify ways to minimise the uses of neonicotinoids in order to reduce the risk of neonicotinoid exposure to honeybees.
Fauna-rescue programs can successfully relocate vertebrate fauna prior to and during vegetation-clearing programs
Authors: Thompson Scott A. , Thompson Graham G.
Published: July 2015

Vegetation clearing is often a precursor to urban, industrial and mining developments. Vertebrate fauna are often lost and injured during this process; however, these impacts are often mitigated by implementing a fauna rescue program. Here we report on the success of a trapping and relocation program and the use of fauna rescue personnel to remove vertebrate fauna from two vegetation-clearing programs. We provide comment on the impact of various machines that are used in the clearing process and which taxa have the higher survival rates, and conclude with some management recommendations that will provide better outcomes for vertebrate fauna during vegetation-clearing programs.
Comparison of animal biodiversity in three livestock systems of open environments of the semi-arid Chaco of Argentina
Authors: Marinaro Sofia , Grau Ricardo H.
Published: July 2015

Increasing global food demand requires the exploration of agricultural production systems that minimise the conflict between food production and biodiversity conservation. Cattle ranching is a main land-use in tropical and sub-tropical South American semi-arid ecosystems, such as the Chaco eco-region of sub-tropical Argentina, one of the most active frontiers of land-use change. Despite open habits being a key component of the Chaco landscape, conservation studies and policies have focussed on forests. In this study, bird and mammal communities of three different open-canopy livestock-producing systems in the semi-arid Argentinian Chaco: natural grasslands, sown non-native pastures and silvopastoral systems are discussed. Diversity (Inverse Simpson index) and species composition (multivariate ordinations) were measured and species identified that characterise each system (indicator species). The three livestock systems did not significantly differ in terms of diversity but showed differences in the composition of bird communities. Natural grasslands had the highest number of bird and mammal indicator species (including Myrmecophaga tridactyla, a high conservation-value species). These results highlight natural grasslands as a landscape unit with a high conservation value and indicate that they should be explicitly targeted by conservation and land-use policies, particularly because they represent a small and rapidly decreasing proportion of the semi-arid Argentinian Chaco.
TPC2 mediates new mechanisms of platelet dense granule membrane dynamics through regulation of Ca2+release
Authors: Ambrosio Andrea L. , Boyle Judith A. , Di Pietro Santiago M.
Published: July 2015

Platelet dense granules (PDGs) are acidic calcium stores essential for normal hemostasis. They develop from late endosomal compartments upon receiving PDG-specific proteins through vesicular trafficking, but their maturation process is not well understood. Here we show that two-pore channel 2 (TPC2) is a component of the PDG membrane that regulates PDG luminal pH and the pool of releasable Ca2+. Using a genetically encoded Ca2+biosensor and a pore mutant TPC2, we establish the function of TPC2 in Ca2+release from PDGs and the formation of perigranular Ca2+nanodomains. For the first time, Ca2+spikes around PDGs—or any organelle of the endolysosome family—are visualized in real time and revealed to precisely mark organelle “kiss-and-run” events. Further, the presence of membranous tubules transiently connecting PDGs is revealed and shown to be dramatically enhanced by TPC2 in a mechanism that requires ion flux through TPC2. “Kiss-and-run” events and tubule connections mediate transfer of membrane proteins and luminal content between PDGs. The results show that PDGs use previously unknown mechanisms of membrane dynamics and content exchange that are regulated by TPC2.
GeneCOST: a novel scoring-based prioritization framework for identifying disease causing genes
Authors: Ozer Bugra , Sağıroğlu Mahmut , Demirci Hüseyin
Published: July 2015

Summary: Due to the big data produced by next-generation sequencing studies, there is an evident need for methods to extract the valuable information gathered from these experiments. In this work, we propose GeneCOST, a novel scoring-based method to evaluate every gene for their disease association. Without any prior filtering and any prior knowledge, we assign a disease likelihood score to each gene in correspondence with their variations. Then, we rank all genes based on frequency, conservation, pedigree and detailed variation information to find out the causative reason of the disease state. We demonstrate the usage of GeneCOST with public and real life Mendelian disease cases including recessive, dominant, compound heterozygous and sporadic models. As a result, we were able to identify causative reason behind the disease state in top rankings of our list, proving that this novel prioritization framework provides a powerful environment for the analysis in genetic disease studies alternative to filtering-based approaches.

Availability and implementation: GeneCOST software is freely available at www.igbam.bilgem.tubitak.gov.tr/en/softwares/genecost-en/index.html.

Contact:  buozer@gmail.com

Supplementary information:  Supplementary data are available at Bioinformatics online.
Quantifying AGN-driven metal-enhanced outflows in chemodynamical simulations
Authors: Taylor Philip , Kobayashi Chiaki
Published: July 2015

We show the effects of AGN-driven outflows on the ejection of heavy elements using our cosmological simulations, where supermassive black holes originate from the first stars. In the most massive galaxy, we have identified two strong outflows unambiguously driven by active galactic nucleus (AGN) feedback. These outflows have a speed greater than ∼8000 km s−1 near the AGN, and travel out to a half Mpc with ∼3000 km s−1. These outflows remove the remaining gas (∼3 per cent of baryons) and significant amounts of metals (∼2 per cent of total produced metals) from the host galaxy, chemically enriching the circumgalactic medium (CGM) and the intergalactic medium (IGM). 17.6 per cent of metals from this galaxy, and 18.4 per cent of total produced metals in the simulation, end up in the CGM and IGM, respectively. The metallicities of the CGM and IGM are higher with AGN feedback, while the mass–metallicity relation of galaxies is not affected very much. We also find ‘selective’ mass-loss where iron is more effectively ejected than oxygen because of the time delay of Type Ia supernovae. AGN-driven outflows play an essential role not only in quenching of star formation in massive galaxies to match with observed downsizing phenomena, but also in a large-scale chemical enrichment in the Universe. Observational constraints of metallicities and elemental abundance ratios in outflows are important to test the modelling of AGN feedback in galaxy formation.
Focus Issue Articles on Emerging and Re-Emerging Plant Diseases
Authors: Subbarao Krishna V. , Sundin George W. , Klosterman Steven J.
Published: July 2015

The history of plant pathology is closely tied to plant diseases that have changed the course of human history. The Irish potato famine, caused by late blight of potato, resulted in the starvation and death of millions of people and one of the most influential human migrations in history. Other plant diseases have impacted quality of life in myriad ways. The advent of fungicides, clean seeds, host resistance, and the development of a plethora of other techniques, has diminished the impact of plant diseases. However, impressive advances in modes of rapid transport have not only increased global trade and human migration, but also augmented the risk for anthropogenic invasions of plant pathogens. As a consequence, and possibly aggravated by climate change, many historical and contemporary diseases are emerging as threats to modern agriculture and food security. These emerging diseases are not only important in global crop production, but also pose severe risks on a local level, especially on small farms in developing countries. This Focus Issue of Phytopathology contains a collection of peer-reviewed research articles, invited reviews and perspective articles on an assortment of emerging and re-emerging diseases caused by bacterial (3 papers), fungal (6 papers), oomycete (5 papers), and viral plant pathogens (3 papers). These diseases cover a range of crops including annual field crops and perennial tree crops, and vegetables, across five continents.
Explaining large-scale patterns of vertebrate diversity
Authors: Wiens John J.
Published: July 2015

The major clades of vertebrates differ dramatically in their current species richness, from 2 to more than 32 000 species each, but the causes of this variation remain poorly understood. For example, a previous study noted that vertebrate clades differ in their diversification rates, but did not explain why they differ. Using a time-calibrated phylogeny and phylogenetic comparative methods, I show that most variation in diversification rates among 12 major vertebrate clades has a simple ecological explanation: predominantly terrestrial clades (i.e. birds, mammals, and lizards and snakes) have higher net diversification rates than predominantly aquatic clades (i.e. amphibians, crocodilians, turtles and all fish clades). These differences in diversification rates are then strongly related to patterns of species richness. Habitat may be more important than other potential explanations for richness patterns in vertebrates (such as climate and metabolic rates) and may also help explain patterns of species richness in many other groups of organisms.
The life story of hydrogen peroxide II: a periodic pH and thermochemical drive for the RNA world
Authors: Ball Rowena , Brindley John
Published: July 2015

It is now accepted that primordial non-cellular RNA communities must have been subject to a periodic drive in order to replicate and prosper. We have proposed the oxidation of thiosulfate by hydrogen peroxide as this drive. This reaction system behaves as (i) a thermochemicaland(ii) a pH oscillator, and in this work, we unify (i) and (ii) for the first time. We report thermally self-consistent, dynamical simulations in which the system transitions smoothly from nearly isothermal pH to fully developed thermo-pH oscillatory regimes. We use this oscillator to drive simulated replication of a 39-bp RNA species. Production of replicated duplex under thermo-pH drive was significantly enhanced compared with that under purely thermochemical drive, effectively allowing longer strands to replicate. Longer strands are fitter, with more potential to evolve enzyme activity and resist degradation. We affirm that concern over the alleged toxicity of hydrogen peroxide to life is largely misplaced in the current context, we survey its occurrence in the solar system to motivate its inclusion as a biosignature in the search for life on other worlds and highlight that pH oscillations in a spatially extended, bounded system manifest as the fundamental driving force of life: a proton gradient.
An artificial elementary eye with optic flow detection and compositional properties
Authors: Pericet-Camara Ramon , Dobrzynski Michal K. , Juston Raphaël , Viollet Stéphane , Leitel Robert , Mallot Hanspeter A. , Floreano Dario
Published: July 2015

We describe a 2 mg artificial elementary eye whose structure and functionality is inspired by compound eye ommatidia. Its optical sensitivity and electronic architecture are sufficient to generate the required signals for the measurement of local optic flow vectors in multiple directions. Multiple elementary eyes can be assembled to create a compound vision system of desired shape and curvature spanning large fields of view. The system configurability is validated with the fabrication of a flexible linear array of artificial elementary eyes capable of extracting optic flow over multiple visual directions.
Directional, passive liquid transport: the Texas horned lizard as a model for a biomimetic ‘liquid diode’
Authors: Comanns Philipp , Buchberger Gerda , Buchsbaum Andreas , Baumgartner Richard , Kogler Alexander , Bauer Siegfried , Baumgartner Werner
Published: July 2015

Moisture-harvesting lizards such as the Texas horned lizard (Iguanidae:
Phrynosoma cornutum
) live in arid regions. Special skin adaptations enable them to access water sources such as moist sand and dew: their skin is capable of collecting and transporting water directionally by means of a capillary system between the scales. This fluid transport is passive, i.e. requires no external energy, and directs water preferentially towards the lizard's snout. We show that this phenomenon is based on geometric principles, namely on a periodic pattern of interconnected half-open capillary channels that narrow and widen. Following a biomimetic approach, we used these principles to develop a technical prototype design. Building upon the Young–Laplace equation, we derived a theoretical model for the local behaviour of the liquid in such capillaries. We present a global model for the penetration velocity validated by experimental data. Artificial surfaces designed in accordance with this model prevent liquid flow in one direction while sustaining it in the other. Such passive directional liquid transport could lead to process improvements and reduction of resources in many technical applications.
An empirical investigation into the role of subjective prior probability in searching for potentially missing items
Authors: Fanshawe T. R.
Published: July 2015

There are many examples from the scientific literature of visual search tasks in which the length, scope and success rate of the search have been shown to vary according to the searcher's expectations of whether the search target is likely to be present. This phenomenon has major practical implications, for instance in cancer screening, when the prevalence of the condition is low and the consequences of a missed disease diagnosis are severe. We consider this problem from an empirical Bayesian perspective to explain how the effect of a low prior probability, subjectively assessed by the searcher, might impact on the extent of the search. We show how the searcher's posterior probability that the target is present depends on the prior probability and the proportion of possible target locations already searched, and also consider the implications of imperfect search, when the probability of false-positive and false-negative decisions is non-zero. The theoretical results are applied to two studies of radiologists' visual assessment of pulmonary lesions on chest radiographs. Further application areas in diagnostic medicine and airport security are also discussed.
Functional morphology and efficiency of the antenna cleaner in
Camponotus rufifemur
ants
Authors: Hackmann Alexander , Delacave Henry , Robinson Adam , Labonte David , Federle Walter
Published: July 2015

Contamination of body surfaces can negatively affect many physiological functions. Insects have evolved different adaptations for removing contamination, including surfaces that allow passive self-cleaning and structures for active cleaning. Here, we study the function of the antenna cleaner in
Camponotus rufifemur
ants, a clamp-like structure consisting of a notch on the basitarsus facing a spur on the tibia, both bearing cuticular ‘combs’ and ‘brushes’. The ants clamp one antenna tightly between notch and spur, pull it through, and subsequently clean the antenna cleaner itself with the mouthparts. We simulated cleaning strokes by moving notch or spur over antennae contaminated with fluorescent particles. The notch removed particles more efficiently than the spur, but both components eliminated more than 60% of the particles with the first stroke. Ablation of bristles, brush and comb strongly reduced the efficiency, indicating that they are essential for cleaning. To study how comb and brush remove particles of different sizes, we contaminated antennae of living ants, and anaesthetized them immediately after they had performed the first cleaning stroke. Different-sized beads were trapped in distinct zones of the notch, consistent with the gap widths between cuticular outgrowths. This suggests that the antenna cleaner operates like a series of sieves that remove the largest objects first, followed by smaller ones, down to the smallest particles that get caught by adhesion.
Keep up or drown: adjustment of western Pacific coral reefs to sea-level rise in the 21st century
Authors: van Woesik R. , Golbuu Y. , Roff G.
Published: July 2015

Since the Mid-Holocene, some 5000 years ago, coral reefs in the Pacific Ocean have been vertically constrained by sea level. Contemporary sea-level rise is releasing these constraints, providing accommodation space for vertical reef expansion. Here, we show thatPoritesmicroatolls, from reef-flat environments in Palau (western Pacific Ocean), are ‘keeping up’ with contemporary sea-level rise. Measurements of 570 reef-flatPoritesmicroatolls at 10 locations around Palau revealed recent vertical skeletal extension (78±13 mm) over the last 6–8 years, which is consistent with the timing of the recent increase in sea level. We modelled whether microatoll growth rates will potentially ‘keep up’ with predicted sea-level rise in the near future, based upon average growth, and assuming a decline in growth for every 1°C increase in temperature. We then compared these estimated extension rates with rates of sea-level rise under four Representative Concentration Pathways (RCPs). Our model suggests that under low–mid RCP scenarios, reef-coral growth will keep up with sea-level rise, but if greenhouse gas concentrations exceed 670 ppm atmospheric CO2levels and with +2.2°C sea-surface temperature by 2100 (RCP 6.0 W m−2), our predictions indicate thatPoritesmicroatolls will be unable to keep up with projected rates of sea-level rise in the twenty-first century.
Principles for the determination of the surface potential of charged particles in mixed electrolyte solutions
Authors: Liu Xinmin , Tian Rui , Li Rui , Ding Wuquan , Li Hang , Yuan Ruo
Published: July 2015

The Gouy–Chapman surface potential is a key parameter for many interfacial phenomena in physical, chemical and biological systems. Existing theoretical approaches allow the determination of the surface potential at a solid–liquid interface only in single electrolyte solutions; however, mixed electrolytes are often encountered in practical applications. The development of a theoretical approach for the determination of the surface potential in mixed electrolyte solutions is therefore a desirable goal. In this study, this important issue was resolved for the first time. Based on the analytical solutions of the nonlinear Poisson–Boltzmann equation in different mixed electrolyte solutions, corresponding mathematical relationships were developed between the surface potential and the mean ionic concentration in the diffuse layer. As the mean ionic concentration in the diffuse layer can be easily determined, the surface potential could be calculated using the newly derived equations. The effects of electrolyte composition on the surface potential were theoretically quantified in the new equations, while only counterionic type was taken into account for mixed electrolyte solutions in the current studies.
On the ecogeomorphological feedbacks that control tidal channel network evolution in a sandy mangrove setting
Authors: van Maanen B. , Coco G. , Bryan K. R.
Published: July 2015

An ecomorphodynamic model was developed to study how
Avicennia marina
mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution.
Causality and passivity in elastodynamics
Authors: Srivastava Ankit
Published: July 2015

What are the constraints placed on the constitutive tensors of elastodynamics by the requirements that the linear elastodynamic system under consideration be both causal (effects succeed causes) and passive (system does not produce energy)? The analogous question has been tackled in other areas but in the case of elastodynamics its treatment is complicated by the higher order tensorial nature of its constitutive relations. In this paper, we clarify the effect of these constraints on highly general forms of the elastodynamic constitutive relations. We show that the satisfaction of passivity (and causality) directly requires that the hermitian parts of the transforms (Fourier and Laplace) of the time derivatives of the constitutive tensors be positive semi-definite. Additionally, the conditions require that the non-hermitian parts of the Fourier transforms of the constitutive tensors be positive semi-definite for positive values of frequency. When major symmetries are assumed these definiteness relations apply simply to the real and imaginary parts of the relevant tensors. For diagonal and one-dimensional problems, these positive semi-definiteness relationships reduce to simple inequality relations over the real and imaginary parts, as they should. Finally, we extend the results to highly general constitutive relations which include the Willis inhomogeneous relations as a special case.
The domestication of Amazonia before European conquest
Authors: Clement Charles R. , Denevan William M. , Heckenberger Michael J. , Junqueira André Braga , Neves Eduardo G. , Teixeira Wenceslau G. , Woods William I.
Published: July 2015

During the twentieth century, Amazonia was widely regarded as relatively pristine nature, little impacted by human history. This view remains popular despite mounting evidence of substantial human influence over millennial scales across the region. Here, we review the evidence of an anthropogenic Amazonia in response to claims of sparse populations across broad portions of the region. Amazonia was a major centre of crop domestication, with at least 83 native species containing populations domesticated to some degree. Plant domestication occurs in domesticated landscapes, including highly modified Amazonian dark earths (ADEs) associated with large settled populations and that may cover greater than 0.1% of the region. Populations and food production expanded rapidly within land management systems in the mid-Holocene, and complex societies expanded in resource-rich areas creating domesticated landscapes with profound impacts on local and regional ecology. ADE food production projections support estimates of at least eight million people in 1492. By this time, highly diverse regional systems had developed across Amazonia where subsistence resources were created with plant and landscape domestication, including earthworks. This review argues that the Amazonian anthrome was no less socio-culturally diverse or populous than other tropical forested areas of the world prior to European conquest.
Structural mouthpart interaction evolved already in the earliest lineages of insects
Authors: Blanke Alexander , Rühr Peter T. , Mokso Rajmund , Villanueva Pablo , Wilde Fabian , Stampanoni Marco , Uesugi Kentaro , Machida Ryuichiro , Misof Bernhard
Published: July 2015

In butterflies, bees, flies and true bugs specific mouthparts are in close contact or even fused to enable piercing, sucking or sponging of particular food sources. The common phenomenon behind these mouthpart types is a complex composed of several consecutive mouthparts whichstructurallyinteract during food uptake. The single mouthparts are thus only functional in conjunction with other adjacent mouthparts, which is fundamentally different to biting–chewing. It is, however, unclear when structural mouthpart interaction (SMI) evolved since this principle obviously occurred multiple times independently in several extant and extinct winged insect groups. Here, we report a new type of SMI in two of the earliest wingless hexapod lineages—Diplura and Collembola. We found that the mandible and maxilla interact with each other via an articulatory stud at the dorsal side of the maxillary stipes, and they are furthermore supported by structures of the hypopharynx and head capsule. These interactions are crucial stabilizing elements during food uptake. The presence of SMI in these ancestrally wingless insects, and its absence in those crustacean groups probably ancestral to insects, indicates that SMI is a groundplan apomorphy of insects. Our results thus contradict the currently established view of insect mouthpart evolution that biting–chewing mouthparts without any form of SMI are the ancestral configuration. Furthermore, SMIs occur in the earliest insects in a high anatomical variety. SMIs in stemgroup representatives of insects may have triggered efficient exploitation and fast adaptation to new terrestrial food sources much earlier than previously supposed.
Adaptive genetic variation mediates bottom-up and top-down control in an aquatic ecosystem
Authors: Rudman Seth M. , Rodriguez-Cabal Mariano A. , Stier Adrian , Sato Takuya , Heavyside Julian , El-Sabaawi Rana W. , Crutsinger Gregory M.
Published: July 2015

Research in eco-evolutionary dynamics and community genetics has demonstrated that variation within a species can have strong impacts on associated communities and ecosystem processes. Yet, these studies have centred around individual focal species and at single trophic levels, ignoring the role of phenotypic variation in multiple taxa within an ecosystem. Given the ubiquitous nature of local adaptation, and thus intraspecific variation, we sought to understand how combinations of intraspecific variation in multiple species within an ecosystem impacts its ecology. Using two species that co-occur and demonstrate adaptation to their natal environments, black cottonwood (Populus trichocarpa) and three-spined stickleback (Gasterosteus aculeatus), we investigated the effects of intraspecific phenotypic variation on both top-down and bottom-up forces using a large-scale aquatic mesocosm experiment. Black cottonwood genotypes exhibit genetic variation in their productivity and consequently their leaf litter subsidies to the aquatic system, which mediates the strength of top-down effects from stickleback on prey abundances. Abundances of four common invertebrate prey species and available phosphorous, the most critically limiting nutrient in freshwater systems, are dictated by the interaction between genetic variation in cottonwood productivity and stickleback morphology. These interactive effects fit with ecological theory on the relationship between productivity and top-down control and are comparable in strength to the effects of predator addition. Our results illustrate that intraspecific variation, which can evolve rapidly, is an under-appreciated driver of community structure and ecosystem function, demonstrating that a multi-trophic perspective is essential to understanding the role of evolution in structuring ecological patterns.
A novel characterization of organic molecular crystal structures for the purpose of crystal engineering
Authors: Thomas Noel W.
Published: July 2015

A novel analytical approach is proposed for the characterization of organic molecular crystal structures where close packing is an important factor. It requires the identification of a unique reference axis within the crystal, along which three-dimensional space is divided into close-packed blocks (CPB) and junction zones (JZ). The degree of close packing along the reference axis is quantified by a two-dimensional packing function, φ2D, of symmetry determined by the space group. Values of φ2Dreflect the degree of area-filling in planes perpendicular to this axis. The requirement of close packing within CPB allows the planar structures perpendicular to the reference axis to be analysed as tessellations of area-filling molecular-based cells (MBC), which are generally hexagonal. The form of these cells reflects the molecular shape in the cross-section, since their vertices are given by the centres of the voids between molecules. There are two basic types of MBC, Type 1, of glide or pseudo-glide symmetry, and Type 2, which is formed by lattice translations alone and generally requires a short unit-cell axis. MBC at layers of special symmetry are used to characterize the structures in terms of equivalent ellipses with parametersaell,belland χell. The ratioaell/bellallows the established α, β, γ classification to be integrated into the current framework. The values of parametersaellandbellarising from all the structures considered, polynuclear aromatic hydrocarbons (PAH), substituted anthracenes and anthraquinones (SAA) and 2-benzyl-5-benzylidene (BBCP) are mapped onto a universal curve. The division of three-dimensional space into CPB and JZ is fundamentally useful for crystal engineering, since the structural perturbations brought about by substitution at hydrogen positions located within JZ are minimal. A contribution is also made to ongoing debate concerning the adoption of polar space groups, isomorphism and polymorphism.
Crystal structures of (2E)-1-(3-bromothiophen-2-yl)-3-(2-methoxyphenyl)prop-2-en-1-one and (2E)-1-(3-bromothiophen-2-yl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one
Authors: Naik Vasant S. , Shettigar Venkataraya , Berglin Tyler S. , Coburn Jillian S. , Jasinski Jerry P. , Yathirajan Hemmige S.
Published: July 2015

In the molecules of the title compounds, (2E)-1-(3-bromo-thiophen-2-yl)-3-(2-methoxyphenyl)prop-2-en-1-one, C14H11BrO2S, (I), which crystallizes in the space groupP-1 with four independent molecules in the asymmetric unit (Z′ = 8), and (2E)-1-(3-bromothiophen-2-yl)-3-(3,4-dimethoxyphenyl)prop-2-en-1-one, C15H13BrO3S, (II), which crystallizes withZ′ = 8 in the space groupI2/a, the non-H atoms are nearly coplanar. The molecules of (I) pack with inversion symmetry stacked diagonally along thea-axis direction. Weak C—H...Br intramolecular interactions in each of the four molecules in the asymmetric unit are observed. In (II), weak C—H...O, bifurcated three-center intermolecular interactions forming dimers along with weak C—H...π and π–π stacking interactions are observed, linking the molecules into sheets along [001]. A weak C—H...Br intramolecular interaction is also present. There are no classical hydrogen bonds present in either structure.
Crystal structure of methyl 3-(3-fluorophenyl)-1-methyl-1,3a,4,9b-tetrahydro-3H-thiochromeno[4,3-c]isoxazole-3a-carboxylate
Authors: Savithri M. P. , Suresh M. , Raghunathan R. , Vimala G. , SubbiahPandi A.
Published: July 2015

In the title compound, C19H18FNO3S, the five-membered oxazolidine ring adopts an envelope conformation with the methine C atom of the fused bond as the flap. Its mean plane is oriented at a dihedral angle of 50.38 (1)° with respect to the fluorophenyl ring. The six-membered thiopyran ring has a half-chair conformation and its mean plane is almost coplanar with the fused benzene ring, making a dihedral angle of 4.94 (10)°. The two aromatic rings are inclined to one another by 85.96 (11)°, and the mean planes of the oxazolidine and thiopyran rings are inclined to one another by 57.64 (12)°. In the crystal, molecules are linked by C—H...π interactions, forming a three-dimensional structure.
Crystal structure ofcatena-poly[hemi[1,3-bis(2,6-diisopropylphenyl)imidazolium] [[μ3-acetato-κ3O:O:O′-tri-μ2-acetato-κ6O:O′-dicopper(II)(Cu—Cu)]-μ-chlorido] dichloromethane sesquisolvate]
Authors: Iqbal Mohammad , Raftery James , Quayle Peter
Published: July 2015

The title copper(II) complex, {(C27H37N2)[Cu4(CH3COO)8Cl]·3CH2Cl2}n, is a one-dimensional coordination polymer. The asymmetric unit is composed of a copper(II) tetraacetate paddle-wheel complex, a Cl−anion situated on a twofold rotation axis, half a 1,3-bis(2,6-diisopropylphenyl)imidazolium cation (the whole molecule being generated by twofold rotation symmetry) and one and a half of a dichloromethane solvent molecule (one being located about a twofold rotation axis). The central metal-organic framework comprises of a tetranuclear copper(II) acetate `paddle-wheel' complex which arises from the dimerization of the copper(II) tetraacetate core comprising of three μ2-bidentate acetate and one μ3-tridentate acetate ligands per binuclear paddle-wheel complex. Both CuIIatoms of the binuclear component adopt a distorted square-pyramidal coordination geometry (τ = 0.04), with a Cu...Cu separation of 2.6016 (2) Å. The apical coordination site of one CuIIatom is occupied by an O atom of a neighbouring acetate bridge [Cu—O = 2.200 (2) Å], while that of the second CuIIatom is occupied by a bridging chloride ligand [Cu...Cl = 2.4364 (4) Å]. The chloride bridge is slightly bent with respect to the Cu...Cu internuclear axis [Cu—Cl—Cu = 167.06 (6)°] and the tetranuclear units are located about a twofold rotation axis, forming the one-dimensional polymer that propagates along [101]. Charge neutrality is maintained by the inclusion of the 1,3-bis(2,6-diisopropylphenyl)imidazolium cation within the crystal lattice. In the crystal, the cation and dichloromethane solvent molecules are linked to the coordination polymer by various C—H...O and C—H...Cl hydrogen bonds. There are no other significant intermolecular interactions present.
Crystal structure of 13-(2-methoxyphenyl)-3,4-dihydro-2H-indazolo[1,2-b]phthalazine-1,6,11(13H)-trione
Authors: Bouraiou Abdelmalek , Bouacida Sofiane , Merazig Hocine , Chibani Aissa , Bouaziz Zouhair
Published: July 2015

In the title compound, C22H18N2O4, the three fused rings of the pyrazolophthalazine moiety are coplanar (r.m.s. deviation = 0.027 Å). The cyclohexene ring fused to the pyrazolidine ring, so forming the indazolophthalazine unit, has a half-chair conformation. The benzene ring is almost normal to the mean plane of the pyrazolophthalazine moiety, with a dihedral angle of 87.21 (6)° between their planes. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds forming inversion dimers. The dimers are linkedviaC—H...π interactions, forming slabs parallel to (100). Between the slabs there are weak π–π interactions [shortest inter-centroid distance = 3.6664 (9) Å], leading to the formation of a three-dimensional structure.
Screening tools for autism spectrum disorders
Authors: Sappok Tanja , Heinrich Manuel , Underwood Lisa
Published: July 2015

Purpose

– Diagnosing autism spectrum disorder (ASD) is important over the whole life span. Standardized instruments may support the assessment process. The purpose of this paper is to describe English- and German-screening tools for ASD.

Design/methodology/approach

– PubMed was used to search for published tools and evidence on their diagnostic validity.

Findings

– Searches identified 46 screening tools for ASD. Most are designed for children, while only few measures are available for adults, especially those with additional intellectual disabilities. Many instruments are under-researched, although a small number such as the Modified Checklist for Autism in Toddlers and the SCQ have been widely examined in a variety of populations.

Originality/value

– The study identified and described a number of ASD screeners that can support clinicians or researchers when deciding whether to carry out a more comprehensive ASD assessment.
A preliminary study of autism and cybercrime in the context of international law enforcement
Authors: Ledingham Rebecca , Mills Richard
Published: July 2015

Purpose

– The purpose of this paper is to explore the association of cybercrime, autistic spectrum conditions and international law enforcement, the past decade having seen a significant growth in reported cybercrimes involving autistic individuals.

Design/methodology/approach

– Interest in the profile of autism and cybercrime and the pathways whereby such offences are committed is shared by key law-enforcement agencies worldwide. This was explored by literature review and survey.

Findings

– The authors identified a presence of persons with Autism Spectrum Disorders but no empirical evidence to suggest a prevalence or an over representation of autistic individuals committing cybercrime offences. At present profiling, pathways, and recording is under developed.

Research limitations/implications

– Paucity of literature on cybercrime and autism. Awareness of autism within law-enforcement agencies and the absence of key diagnostic and other data from the cross-section of agencies surveyed.

Practical implications

– Improve detection, diversion, profiling, risk and pathways into cybercrime.

Social implications

– Better prediction of risk of cybercrime and improved responses.

Originality/value

– Original paper believed to be the first to look at cybercrime and ASD in the context of international law enforcement.