bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal, synoptic, and diurnal‐scale variability of biogeochemical trace gases and O2 from a 300‐m tall tower in central Siberia
Authors: Kozlova Elena A. , Manning Andrew C. , Kisilyakhov Yegor , Seifert Thomas , Heimann Martin
Published: December 2008

We present first results from 19 months of semicontinuous concentration measurements of biogeochemical trace gases (CO2, CO, and CH4) and O2, measured at the Zotino Tall Tower Observatory (ZOTTO) in the boreal forest of central Siberia. We estimated CO2 and O2 seasonal cycle amplitudes of 26.6 ppm and 134 per meg, respectively. An observed west‐east gradient of about −7 ppm (in July 2006) between Shetland Islands, Scotland, and ZOTTO reflects summertime continental uptake of CO2 and is consistent with regional modeling studies. We found the oceanic component of the O2 seasonal amplitude (Atmospheric Potential Oxygen, or APO) to be 51 per meg, significantly smaller than the 95 per meg observed at Shetlands, illustrating a strong attenuation of the oceanic O2 signal in the continental interior. Comparison with the Tracer Model 3 (TM3) atmospheric transport model showed good agreement with the observed phasing and seasonal amplitude in CO2; however, the model exhibited greater O2 (43 per meg, 32%) and smaller APO (9 per meg, 18%) amplitudes. This seeming inconsistency in model comparisons between O2 and APO appears to be the result of phasing differences in land and ocean signals observed at ZOTTO, where ocean signals have a significant lag. In the first 2 months of measurements on the fully constructed tower (November and December 2006), we observed several events with clear vertical concentration gradients in all measured species except CO. During “cold events” (below −30°C) in November 2006, we observed large vertical gradients in CO2 (up to 22 ppm), suggesting a strong local source. The same pattern was observed in CH4 concentrations for the same events. Diurnal vertical CO2 gradients in April to May 2007 gave estimates for average nighttime respiration fluxes of 0.04 ± 0.02 mol C m−2 d−1, consistent with earlier eddy covariance measurements in 1999–2000 in the vicinity of the tower.
Temperature sensitivity of N2O emissions from fertilized agricultural soils: Mathematical modeling in ecosys
Authors: Grant R. F. , Pattey E.
Published: December 2008

N2O emissions have been found to be highly sensitive to soil temperature (Ts) which may cause substantial rises in emissions with rises in Ts expected in most climate change scenarios. Mathematical models used to project changes in emissions during climate change should be able to simulate the physical and biological processes by which this sensitivity is determined. We show that the large rises in N2O emissions with short‐term rises in Ts (Q10 > 5) found in controlled temperature studies can be modeled from established Arrhenius functions for rates of microbial C and N oxidation (Q10 ∼ 2) when combined with Ts effects on gaseous solubilities and diffusivities and with water effects on gaseous diffusivities, interphase gas transfer coefficients, and diffusion path lengths. Rises in N2O emissions modeled with a long‐term rise in Ts during a climate warming scenario were smaller than expected from short‐term rises in Ts. Nonetheless, annual N2O emissions rose by ∼30% during three growing seasons in a cool humid maize‐soybean rotation under a climate change scenario in which atmospheric CO2 concentration Ca was raised by 50%, air temperature Ta by 3°C, and precipitation events by 5%. These model results indicate that climate warming may cause substantial rises in N2O emissions from fertilized agricultural fields in cool, humid climates.
Correlation between the magnetic susceptibility record of the Chinese aeolian sequences and the marine benthic oxygen isotope record
Authors: Nie Junsheng , King John W. , Fang Xiaomin
Published: December 2008

It has been long known that the magnetic susceptibility record of the Chinese loess correlates well with the marine benthic oxygen isotope record at the orbital bands during the last ∼0.8 Ma, suggesting that at the orbital scale, the phasing and periodicity of the East Asian Summer Monsoon (EASM) are controlled by northern ice volume but not by northern summer insolation. However, during the interval ∼2.8–0.8 Ma, there is poor correlation between the EASM record obtained from loess magnetic susceptibility and the global ice volume record obtained from marine benthic oxygen isotopes, arguing against control of the phasing and periodicity of the EASM by global ice volume. Here we show that during the interval ∼2.8–0.8 Ma the magnetic susceptibility record of the Chinese loess correlates well with the clipped and smoothed marine benthic oxygen isotope record from the Eastern Equatorial Pacific Ocean. The data thus suggest that the orbital‐scale periodicity and phasing of the EASM are controlled by northern ice sheets during the entire ∼2.8 Ma, not just the last ∼0.8 Ma. We have shown that tectonic events during the Pliocene are the most plausible causes for the lack of correlation between the Chinese red clay magnetic susceptibility record and the marine benthic oxygen isotope record during the interval ∼4.5–2.7 Ma. We have also shown that the correlation between Chinese red clay magnetic susceptibility record and benthic oxygen isotope record between ∼6 and ∼4.5 Ma is remarkable. The work reported here is complementary to our previous work and indicate that the magnetic susceptibility record of the entire aeolian sequence on the Chinese loess plateau can be correlated with the marine benthic oxygen isotope record.
Coseismic strengthening of the shallow portion of the subduction fault and its effects on wedge taper
Authors: Hu Yan , Wang Kelin
Published: December 2008

According to the dynamic Coulomb wedge model, coseismic strengthening of the shallowest part of the subduction interface can cause permanent deformation of the overlying outer wedge, so that the cumulative effects of great interplate earthquakes control the geometry of the wedge. In this work, we use a numerical model, which is a hybrid of the frictional contact model and the classical crack model, to study how stress is coseismically transferred from the seismogenic zone to the strengthening updip zone to cause wedge deformation. In this static model, the “critical strengthening” required to prevent the rupture from breaking the trench depends on the force drop of the seismogenic zone, defined as the product of the average shear stress drop and the area of the seismogenic zone. In a simple model of uniform material properties with a few megapascals average stress drop over a seismogenic zone of 120 km downdip width, the critical strengthening for a 30 km wide updip zone is an increase in the effective friction coefficient by about 0.05. Using the Coulomb wedge theory, we demonstrate that this level of strengthening can readily push the overlying wedge into a critical state of failure. With much greater strengthening, the rupture is able to extend into the updip zone only slightly, causing localized wedge compression in the area of slip termination. We examined wedge geometry of 22 subduction zones in the light of the model results. We found that the surface slope of these wedges is generally too high to be explained using the classical wedge theory but can be explained using the dynamic Coulomb wedge model including coseismic strengthening of the shallow portion of the megathrust.
Representing cloud overlap with an effective decorrelation length: An assessment using CloudSat and CALIPSO data
Authors: Barker Howard W.
Published: December 2008

This study commenced testing the hypothesis that a vertically constant, effective, decorrelation length *cf can be used to represent overlap of cloud for the purpose of performing radiative transfer calculations in global climate models. It was assumed that total cloud fraction resulting from multiple layers of overlapping fractional cloud can be described as a linear combination of maximum and random overlap, with the weight defined by exp(−Δz/*cf) where Δz is distance between layers. Cloud masks and water contents (CWC) obtained from CloudSat and CALIPSO satellite data, for January 2007, were used to solve for *cf. Benchmark shortwave (SW) and longwave (LW) broadband flux profiles were computed for 500‐km‐long retrieved cross‐sections via the independent column approximation (ICA). Then *cf was found and used, along with corresponding profiles of cloud fraction and CWCs, in a stochastic cloud generator suitable for use in global climate models (GCMs), and ICA fluxes computed for the generated fields. When clouds were homogenized horizontally, zonal mean bias errors for SW cloud radiative effect (CRE) at the top of atmosphere (TOA) were generally <±3 W m−2, with LW counterparts <2 W m−2, similar to changing cloud particle size by ∼15%. For inhomogeneous clouds, SW CRE biases jumped to typically −5 W m−2 partly because of limitations with the generator. When *cf = 2 km (near global median) was used ubiquitously in the generator, was overestimated slightly, mostly by clouds above ∼10 km, and CRE errors grew by just ∼10% to 20%. Exposing too much high cloud to space produced local SW heating rate biases of ∼15%. While optimal effective decorrelation lengths differ for SW and LW radiation, which in turn generally differ from *cf, it appears that use of *cf will suffice for both bands. The impact of using *cf in GCMs remains to be seen.
Spatiotemporal drivers of dissolved organic matter in high alpine lakes: Role of Saharan dust inputs and bacterial activity
Authors: Mladenov Natalie , Pulido‐Villena Elvira , Morales‐Baquero Rafael , Ortega‐Retuerta Eva , Sommaruga Ruben , Reche Isabel
Published: December 2008

The effects of many environmental stressors such as UV radiation are mediated by dissolved organic matter (DOM) properties. Therefore, determining the factors shaping spatial and temporal patterns is particularly essential in the most susceptible, low dissolved organic carbon (DOC) lakes. We analyzed spatiotemporal variations in dissolved organic carbon concentration and dissolved organic matter optical properties (absorption and fluorescence) in 11 transparent lakes located above tree line in the Sierra Nevada Mountains (Spain), and we assessed potential external (evaporation and atmospheric deposition) and internal (bacterial abundance, bacterial production, chlorophyll a, and catchment vegetation) drivers of DOM patterns. At spatial and temporal scales, bacteria were related to chromophoric DOM (CDOM). At the temporal scale, water soluble organic carbon (WSOC) in dust deposition and evaporation were found to have a significant influence on DOC and CDOM in two Sierra Nevada lakes studied during the ice‐free periods of 2000–2002. DOC concentrations and absorption coefficients at 320 nm were strongly correlated over the spatial scale (n = 11, R2 = 0.86; p < 0.01), but inconsistently correlated over time, indicating seasonal and interannual variability in external factors and a differential response of DOC concentration and CDOM to these factors. At the continental scale, higher mean DOC concentrations and more CDOM in lakes of the Sierra Nevada than in lakes of the Pyrenees and Alps may be due to a combination of more extreme evaporation, and greater atmospheric dust deposition.
Supporting the Transition of Elementary School Students Who Use AAC as They Are Promoted From One Grade to the Next
Authors: Blackstien-Adler Susie
Published: December 2008

One of the challenges in supporting students who use AAC and who have complex learning needs is the transition from one school year to the next. These students are typically supported by large teams, many of whom change from one year to the next. Effective, efficient transfer of knowledge and skill from one team to the next does not always occur, compromising the continuity of programming. This article will outline a 3-year project (spanning two transition periods) that aimed to improve on the transition practices within a school board in Ontario Canada. Data collection focused on beliefs and knowledge about transition, transfer of important strategies and tools, and the actual process undertaken by each school. Following analysis of data collected in five schools during the first transition period, the schools developed and piloted a transition checklist, designed to improve on practice. The transition checklist, which resulted in significant change in practice in all five schools, will be described and is offered by the author upon request.
A Service Learning Project in AAC
Authors: Scherz Julie
Published: December 2008

This article presents a service learning project designed for students in the mandatory graduate level Augmentative and Alternative Communication (AAC) class at Wichita State University. The project was developed to allow students a hands-on experience with clients who use AAC.
Case Studies of Intermediate Steps/Between AAC Evaluations and Implementation
Authors: Stuart Sheela , Ritthaler Christopher
Published: December 2008

This article presents two case studies of children with complex communication needs, including a diagnosis of autism. Although different in age and overall diagnoses, both children primarily used behaviors, gestures, and limited overall vocalizations for communication. In each case, some pictures and signing had been intermittently incorporated into their school programs with very little success. The school-based augmentative and alternative communication (AAC) teams had used the candidacy model and decided that, until the children made gains in cognition and behavior, they could not use any type of speech generating device. In each instance, the child's parent disagreed and requested a second AAC evaluation. The second opinion evaluating center incorporated Language Acquisition Though Motor Planning (LAMP) to utilize a speech generating device for participation in some motivating activities. Results were sufficiently positive to support trial use of this approach and private outpatient sessions were provided. The article includes a brief overview of the resulting journey: the give-and-take process between second opinion center, parents, and school to arrive at a form of successful communication for each child.
Words We Would Want: Comparison of Three Pre-programmed Vocabulary Sets With Frequently Used Words in English
Authors: Helmbold Bruce
Published: December 2008

In this descriptive study, three pre-programmed vocabulary sets—Picture WordPower 45 location (Inman Innovations), Unity 45 Full vs. 4.06 (Prentke-Romich Company), and Gateway 60 vs. 1.06.18 (Dynavox Technologies)—were examined for word-based vocabulary content and keystrokes per word. The vocabulary contents of the each set were then compared to the thousand most common words as identified by two different listings apiece, that published in Word Frequencies in Written and Spoken English based on the British National Corpus (BNC), and Wiktionary TV/Movie Frequency Lists (2006). The pre-programmed vocabulary set best representing these frequency lists was Unity 45 Full, followed by Gateway 60 and Picture WordPower. The vocabulary sets using the fewest average keystrokes per word, based on frequency lists, were Picture WordPower and Gateway 60 followed by Unity 45 Full. Results provide an aid for evaluating the comparative merits of pre-programmed vocabulary sets, such as inclusion of frequently used English words and relative keystroke savings.
The role of oxygen in secondary electron contrast in doped semiconductors using low voltage scanning electron microscopy
Authors: Walker C. G. H. , Zaggout F. , El-Gomati M. M.
Published: December 2008

It has been known for many years that p-doped and n-doped regions in semiconductors reveal different contrasts (p-doped normally brighter than n-doped) when imaged in a scanning electron microscope (SEM). This effect could be very useful to the semiconductor industry to determine dopant concentrations at nanoscale dimensions if it could be understood and made quantifiable. Highly doped n+ and p+ samples were studied in a SEM with two different oxide thicknesses. The samples were initially studied without applying any initial treatment and then the oxide was removed by dipping in diluted HF. The samples were studied as a function of primary electron beam energy. It was found that at low primary beam energy (1–2 keV), the p-type material was brighter than the n-type for both oxide thicknesses. However, at higher primary beam energy, the contrast reversed for the sample with the thicker oxide above a primary beam energy of 2 keV. The role of the oxide in these contrast variations is explored and the consequences for the various theories are examined. A comparison is made between the results found here and published results from other techniques which also involve the emission of electrons from surfaces such as photoemission and field emission. It is concluded that oxygen plays a significant role in the dopant contrast (DC) mechanism and that the results are inconsistent with all current DC theories.
Microstructure and origin of dislocation etch pits in GaN epilayers grown by metal organic chemical vapor deposition
Authors: Lu L. , Gao Z. Y. , Shen B. , Xu F. J. , Huang S. , Miao Z. L. , Hao Y. , Yang Z. J. , Zhang G. Y. , Zhang X. P. , Xu J. , Yu D. P.
Published: December 2008

Morphology and microstructure of dislocation etch pits in GaN epilayers etched by molten KOH have been investigated by atomic force microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). Three types of etch pits (α, β, and γ) are observed. The α type etch pit shows an inversed trapezoidal shape, the β one has a triangular shape, and the γ type one has a combination of triangular and trapezoidal shapes. TEM observation shows that α, β, and γ types etch pits originate from screw, edge, and mixed-type threading dislocations (TDs), respectively. For the screw-type TD, it is easily etched along the steps that the dislocation terminates, and consequently, a small Ga-polar plane is formed to prevent further vertical etching. For the edge-type TD, it is easily etched along the dislocation line. Since the mixed-type TDs have both screw and edge components, the γ type etch pit has a combination of α and β type shapes. It is also found that the chemical stabilization of Ga-polar surface plays an important role in the formation of various types of dislocation etch pits.
Etching-dependent reproducible memory switching in vertical SiO2 structures
Authors: Yao Jun , Zhong Lin , Natelson Douglas , Tour James M.
Published: December 2008

Vertical structures of SiO2 sandwiched between a top tungsten electrode and conducting nonmetallic substrate were fabricated by dry and wet etching methods. Both structures exhibit similar voltage-controlled memory behaviors, in which short voltage pulses (1 μs) can switch the devices between high- and low-impedance states. Through the comparison of current-voltage characteristics in structures made by different methods, filamentary conduction at the etched oxide edges is most consistent with the results, providing insights into similar behaviors in metal/SiO/metal systems. High ON/OFF ratios of over 104 were demonstrated.
Two-dimensional expansion of finite-size barium photoplasma in an electrostatic field
Authors: Majumder A. , Jana B. , Kathar P. T. , Das A. K. , Mago V. K.
Published: December 2008

Two-dimensional evolution of finite-size barium photoplasma, produced using multistep-resonant ionization is experimentally investigated in an externally applied electrostatic field. Several processes like bulk motion, ambipolar diffusion, Coulomb repulsion, Child–Langmuir flux, bounded diffusion, etc. that contribute to its expansion, have been identified. They are quantified with the help of signals recorded by Faraday cups, electrodes and plates and by two-dimensional particle-in-cell simulation. These processes are superimposed and their relative magnitudes decide the evolution of the photoions. When external field is dominant, a significant fraction of ions reach the cathode with negligible vertical spread and the plasma motion can be considered as one-dimensional. However, when plasma collective effects are dominant, then the different mechanisms become comparable and the photoplasma expands in two dimensions. The spread of photoions at different locations in parallel plate geometry is determined as a function of plasma density and compared with simulation.
Observation of electric field-assisted phase transition in thin film vanadium oxide in a metal-oxide-semiconductor device geometry
Authors: Ko Changhyun , Ramanathan Shriram
Published: December 2008

We report the observation of electric field-assisted phase transition across a vanadium oxide thin film. The threshold field for initiation of transition was ∼107 V/m at room temperature and decreased with increasing temperature with activation energy of ∼0.2 eV. Electron transport mechanisms were investigated using both current-in-plane and out-of-plane devices and the results correlated very well. In the insulator phase, Poole–Frenkel emission was determined to be a dominant mechanism at high fields, while in the low field regime, Ohmic behavior with activation energy of ∼0.24 eV was observed. In the metallic state, activation energy for Ohmic conduction was ∼0.08 eV.
Study on characteristics of thermally stable HfLaON gate dielectric with TaN metal gate
Authors: Xu Qiuxia , Xu Gaobo , Wang Wenwu , Chen Dapeng , Shi Shali , Han Zhengsheng , Ye Tianchun
Published: December 2008

We have fabricated the thinnest equivalent oxide thickness of 0.62 nm HfLaON gate dielectric for TaN/HfLaON/SiOx gate stack with improved thermal stability and electrical characteristics. The HfLaON film was deposited using reactive sputtering of Hf–La and Hf targets by alternate means in N2/Ar ambience. The effects of different postdeposition annealing conditions and various La contents on the properties of HfLaON film and its interface have been investigated; the corresponding mechanisms are discussed. The gate tunneling leakage is five orders of magnitude lower than the normal polycrystalline silicon/SiO2 structure. The effective work function with TaN metal gate is 4.06 eV.
A slip model for rarefied gas flows at arbitrary Knudsen number
Authors: Wu Lin
Published: December 2008

A slip model for wall bounded rarefied gas flows is derived from kinetic theory. A corresponding modified Reynolds lubrication equation is obtained from the slip velocity boundary conditions at walls for high Knudsen number gas flows. The slip model in a simplest form has predictions very close to the numerical solutions of linearized Boltzmann equation in the whole Knudsen number range, and is preferable to the widely applied 1st order (Maxwell slip model), 2nd order, and 1.5 order slip models.
Method to analyze programmable deformation of dielectric elastomer layers
Authors: Zhao Xuanhe , Suo Zhigang
Published: December 2008

A layer of a dielectric elastomer expands its area when a voltage is applied across its thickness. The layer can be programed to deform in three dimensions by using patterned prestretches, electrodes, and stiffeners. To aid the design of such programmable deformation, this paper describes a computational method, exploiting the fact that the prescribed voltage sets the nominal electric field. The method is demonstrated with examples including formation of wrinkles, movements of a handlike actuator, and nonlinear oscillation of a balloon.
On enhancing classification performance by exploiting multiple scattering
Authors: Carin Lawrence , Guo Bin , Liu Dehong
Published: December 2008

Using concepts developed in the fields of compressive sensing and random-projection-based embeddings, we consider classification of an object situated within a complex propagation environment. We demonstrate that propagation through such an environment may be exploited to enhance classification performance, analogous to the enhanced resolution in time-reversal techniques. The theory is demonstrated using rf measurements.
Epitaxial growth and Ohmic contacts in MgxZn1−xO∕TiN∕Si(111) heterostructures
Authors: Jin Chunming , Wei Wei , Zhou Honghui , Yang Tsung-Han , Narayan Roger J.
Published: December 2008

In this work, the electronic properties of Mg0.1Zn0.9O∕TiN∕Si(111) heterostructures processed using pulsed laser deposition were examined. X-ray diffraction and transmission electron microscopy studies demonstrated epitaxial growth of the titanium nitride buffer layer and the Mg0.1Zn0.9O thin film. Transmission electron microscopy demonstrated a thin (∼5nm) spinel layer along the magnesium zinc oxide/titanium nitride interface. Current-voltage measurements revealed Ohmic contact behavior through the magnesium zinc oxide/titanium nitride interface. These results suggest that the titanium nitride buffer layer in the MgxZn1−xO∕TiN∕Si(111) heterostructure provides a buffer layer for integrating magnesium zinc oxide thin films with silicon substrates, which both enable epitaxial growth and serve as an Ohmic electrode for the magnesium zinc oxide thin film.
Half-cycle atomic layer deposition reaction studies of Al2O3 on (NH4)2S passivated GaAs(100) surfaces
Authors: Milojevic M. , Hinkle C. L. , Aguirre-Tostado F. S. , Kim H. C. , Vogel E. M. , Kim J. , Wallace R. M.
Published: December 2008

“Half-cycle” atomic layer deposition reactions of trimethyl aluminum (TMA) and water on GaAs exposed to wet chemical sulfur treatments are studied for the formation of Al2O3. Trivalent oxides of gallium and arsenic are completely reduced following the first TMA pulse. The same processing step also removes As–S bonding below the level of detection, while the relative concentration of gallium suboxides as well as Ga–S bonds is not affected. A concomitant decrease in the S 2p peak intensity is observed, indicating that sulfur is lost through a volatile reaction product. Further precursor exposures do not measurably affect substrate surface chemistry.
Diffusion of water submonolayers on hydrophilic surfaces
Authors: Park Jae Hyun , Aluru N. R.
Published: December 2008

In this letter, we investigate using molecular dynamics simulations the diffusion of water submonolayers on hydrophilic surfaces. In contrast to a strong hydrophilic Ag surface, on a weak hydrophilic Pb surface, the diffusion coefficient is remarkably enhanced at a critical surface coverage and a Λ-shape anomaly with surface coverage is observed, i.e., the diffusion coefficient increases with the increase in surface coverage until a critical surface coverage, beyond which the diffusion coefficient decreases. We explain the anomalous diffusion of water on hydrophilic surfaces by a detailed understanding of molecular cavities and monolayer tail contributing to three-dimensional hydrogen bonding.
“I Don't Know Why They Call it the Lake District They Might as Well Call it the Rock District!” The Workings of Humour and Laughter in Research with Members of Visually Impaired Walking Groups
Authors: Macpherson Hannah
Published: December 2008

Humour and laughter are socioembodied phenomena which may be evident in interview, ethnographic, or other social research settings. In this paper I argue that we should engage with humour and laughter in our research accounts, rather than simply relegate these themes to the brackets in our transcripts. Drawing upon doctoral research carried out with members of specialist visually impaired walking groups, I show how laughter and humour form a temporary sonic element to the landscapes they pass through and how laughter and humour are used to negotiate the relations between sighted guide and walker, relieve nervousness, and subvert stereotypes. I argue that recognition should be given to laughter and humour as both a conscious reflective strategy and a ‘nonrepresentational’ embodied and contagious phenomenon, for laughter and humour are intimately connected both to the subject positions of walkers with visual impairments and to the embodied, muscular practice of walking itself. I note that, while humour is a useful individual coping strategy that gives people with blindness a sense of liberation from a notion of ‘the blind’ as subjects of pity, laughter and humour can also betray a certain pessimism—sometimes used as a way of coping with, rather than actually challenging, some of the subtle prejudices that they face as users of rural space.
Being Fieldworthy: Environmental Knowledge Practices and the Space of the Field in Forest Certification
Authors: Eden Sally
Published: December 2008

This paper considers how environmental knowledge practices and learning are coproduced through heterogeneous assemblages of inscriptions, devices, skills, ecologies, and people in the field. Drawing on concepts from science and technology studies, I use the certification processes of the Forest Stewardship Council as an example, because its processes of verification through embodied and emplaced fieldwork explicitly seek to make abstract standards of environmental management ‘fieldworthy’ in different places and thus enable their implementation on the ground through specific environmental knowledge practices. Hence, it is only through the field as a shared space that certification processes can work (and travel) in the interests of better environmental management. The space of fieldwork thus enables knowledge workers to exploit the uncertainty, heterogeneity, and discretion in environmental science and management more readily than do other spaces, rendering these qualities more beneficial than problematic.
Phylogeny of the Limnophilinae (Limoniidae) and early evolution of the Tipulomorpha (Diptera)
Authors: Ribeiro Guilherme Cunha
Published: December 2008

Tipulomorpha (crane flies) comprise one of the largest subgroups of Diptera, but its phylogeny at different levels has been poorly explored. This study presents the most comprehensive cladistic analysis of the group ever made, with emphasis on the genera and subgenera of the subfamily Limnophilinae (Limoniidae), assumed to include some of the earliest lineages of Tipulomorpha sensu stricto and therefore important for the understanding of the early patterns in the evolution of the crane flies. Eighty-eight characters of the male imago were scored for 104 exemplar species. The most parsimonious trees were searched using implied weighting, in the framework of a sensitivity analysis with different values of k (2 to 6). The dataset based on the characters of adult male morphology showed high levels of homoplasy and yielded very incongruent and unstable phylogenetic results, which are very sensitive to changes in analytical parameters. In the preferred and most parsimonious phylogenetic hypothesis, the Pediciidae is the sister-group of all other Tipulomorpha sensu stricto. The results indicate the paraphyly of the Limoniidae with respect to the Cylindrotomidae and Tipulidae, which are considered sister-groups. The Limoniidae subfamilies Limnophilinae, Limoniinae and Chioneinae are considered non-monophyletic. The study allowed a reconstruction of the possible ground plan condition of selected features of the adult male morphology of crane flies. The genera/subgenera Epiphragma (Epiphragma), Acantholimnophila, Shannonomyia, Limnophila (Arctolimnophila), Eloeophila, Conosia, Polymera, Polymera (Polymerodes), Prionolabis, Eutonia, Phylidorea (Phylidorea), Metalimnophila, Gynoplistia (Cerozodia), Gynoplistia (Dirhipis), Nothophila, Pseudolimnophila (Pseudolimnophila), Pilaria and Ulomorpha are considered monophyletic, but in general are defined by combinations of very homoplastic character states. Two Temperate Gondwanan clades, (Tonnoirella + (Edwardsomyia + (Tinemyia + (Rhamphophila + (Nothophila))))) and ((Notholimnophila + Bergrothomyia) + (Mesolimnophila + (Chilelimnophila + Ctenolimnophila))) are recovered. The genera Limnophila, Neolimnomyia, Gynoplistia (sensu lato) and Hexatoma (sensu lato) are considered non-monophyletic. The systematic position and some morphological characters of ‘problematic’ taxa, such as Dactylolabis, Elephantomyia, Helius and Atarba are discussed on the light of the proposed phylogeny and the analysis of the characters. Character states are richly illustrated. A detailed study of the morphology of the male genitalia is made, and several genera and species have the morphology of the male genitalia illustrated for the first time.
Species status and conservation issues of New Zealand's endemic Latrodectus spider species (Araneae : Theridiidae)
Authors: Vink Cor J. , Sirvid Phil J. , Malumbres-Olarte Jagoba , Griffiths James W. , Paquin Pierre , Paterson Adrian M.
Published: December 2008

New Zealand has two endemic widow spiders, Latrodectus katipo Powell, 1871 and L. atritus Urquhart, 1890. Both species face many conservation threats and are actively managed. The species status of the Latrodectus spiders of New Zealand was assessed using molecular (COI, ITS1, ITS2) and morphological methods and with cross-breeding experiments. Latrodectus katipo and L. atritus were not found to be reciprocally monophyletic for any of the gene regions or morphological traits. Other than colour, which is variable, there were no morphological characters that separated the two species, which cross-bred in the laboratory and produced fertile eggsacs. Colour variation is clinal over latitude and correlates significantly with mean annual temperature. We conclude that L. atritus is a junior synonym of L. katipo. An example of introgression from the Australian species L. hasseltii Thorell, 1870 was also detected and its conservation implications are discussed.
Fruit anatomy of the genus Anabasis (Salsoloideae, Chenopodiaceae)
Authors: Sukhorukov Alexander P.
Published: December 2008

The fruit anatomy and morphology of 22 representatives of the genus Anabasis L. were studied, with the aim of clarifying the taxomomic importance of carpological characters in the genus. As shown in cross-sections, the pericarp of Anabasis is differentiated into the following four zones: (i) outer epidermis, (ii) subepidermal hydrated parenchyma, (iii) crystalliferous layer with lignified U-shaped cell walls and (iv) inner epidermis. Anatomical differences mainly relate to the outer epidermal structure. Fruit anatomy does not confirm the separation of the genera Brachylepis and Esfandiaria. A combination of carpological characteristics separates A. annua and A. setifera from the other species studied. Also, characters of reproductive organs in representatives of Anabasis are shown. When vegetative and reproductive features are considered, the genus Fredolia appears rather distant from Anabasis s.l. The pericarp histology of almost all the Salsoloideae (incl. Anabasis) is fully presented in the upper third of the fruit. In the lower parts of the fruit, some histological layers are either reduced or absent altogether. On the basis of the anatomical structures in the upper third of the fruit, the common carpological features of the Salsoloideae can be defined. These include a pericarp consisting of several, usually well-differentiated layers and the presence of crystalliferous cells with U-shaped walls. The two- to four-cell layered outer epidermis of three Anabasis representatives (A. eriopoda, A. jaxartica, A. turkestanica) seems to be an apomorphic feature in the Salsoloideae. The seed coat is thin (two cell layers thick) and non-differentiated. Owing to the pericarp and seedcoat structure, the fruit and seed covers have low resistance to environmental degradation processes and, therefore, are unlikely to be found among fossil remnants.
The group ring of ℚ/ℤ and an application of a divisor problem
Authors: Haynes Alan , Homma Kosuke
Published: December 2008

First we prove some elementary but useful identities in the group ring ofQ/Z\mathbb {Q}/\mathbb {Z}. Our identities have potential applications to several unsolved problems which involve sums of Farey fractions. In this paper we use these identities, together with some analytic number theory and results about divisors in short intervals, to estimate the cardinality of a class of sets of fundamental interest.
Powers of Coxeter elements in infinite groups are reduced
Authors: Speyer David
Published: December 2008

Let

W
W

be an infinite irreducible Coxeter group with

(

s
1

,
…
,

s
n

)

(s_1, \ldots , s_n)

the simple generators. We give a short proof that the word

s
1

s
2

⋯

s
n

s
1

s
2

⋯

s_1 s_2 \cdots s_n s_1 s_2 \cdots

s
n

⋯

s
1

s
2

⋯

s
n

s_n \cdots s_1 s_2 \cdots s_n

is reduced for any number of repetitions of

s
1

s
2

⋯

s
n

s_1 s_2 \cdots s_n

. This result was proved for simply laced, crystallographic groups by Kleiner and Pelley using methods from the theory of quiver representations. Our proof uses only basic facts about Coxeter groups and the geometry of root systems. We also prove that, in finite Coxeter groups, there is a reduced word for

w
0

w_0

which is obtained from the semi-infinite word

s
1

s
2

⋯

s
n

s
1

s
2

⋯

s
n

⋯

s_1 s_2 \cdots s_n s_1 s_2 \cdots s_n \cdots

by interchanging commuting elements and taking a prefix.
Bounded harmonic 1-forms on complete manifolds
Authors: Cocos M.
Published: December 2008

In this paper we present some results concerning bounded harmonic

1
1

-forms on manifolds of compact type. As a corollary we obtain a rigidity result for the first cohomology group of locally isometric Riemannian manifolds.
Orbit-counting for nilpotent group shifts
Authors: Miles Richard , Ward Thomas
Published: December 2008

We study the asymptotic behaviour of the orbit-counting function and a dynamical Mertens’ theorem for the full 

G
G

-shift for a finitely-generated torsion-free nilpotent group 

G
G

. Using bounds for the Möbius function on the lattice of subgroups of finite index and known subgroup growth estimates, we find a single asymptotic of the shape
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="sigma-summation Underscript StartAbsoluteValue tau EndAbsoluteValue less-than-or-equal-to upper N Endscripts StartFraction 1 Over e Superscript h StartAbsoluteValue tau EndAbsoluteValue Baseline EndFraction tilde upper C upper N Superscript alpha Baseline left-parenthesis log upper N right-parenthesis Superscript beta">

∑

|
τ
|
≤
N

1

e

h
|
τ
|

∼
C

N

α

(
log
⁡
N

)

β

\sum _{\vert \tau \vert \le N}\frac {1}{e^{h\vert \tau \vert }}\sim CN^{\alpha }(\log N)^{\beta }

\]
where 

|
τ
|

\vert \tau \vert

is the cardinality of the finite orbit 

τ
\tau

and 

h
h

denotes the topological entropy. For the usual orbit-counting function we find upper and lower bounds, together with numerical evidence to suggest that for actions of non-cyclic groups there is no single asymptotic in terms of elementary functions.
Invariant subspaces of super left-commutants
Authors: Gessesse Hailegebriel
Published: December 2008

For a positive operator

Q
Q

on a Banach lattice, one defines

⟨
Q
]
=
{
T
≥
0

:

 
T
Q
≤
Q
T
}

\langle Q]=\{T\geq 0\,:\,~TQ\leq QT\}

and

[
Q
⟩
=
{
T
≥
0

:

T
Q
≥
Q
T
}

[Q\rangle =\{T\geq 0\,:\, TQ\geq QT\}

. There have been several recent results asserting that, under certain assumptions on

Q
Q

,

[
Q
⟩

[Q\rangle

has a common invariant subspace. In this paper, we use the technique of minimal vectors to establish similar results for

⟨
Q
]

\langle Q]

.
Galois scaffolding in one-dimensional elementary abelian extensions
Authors: Elder G.
Published: December 2008

A Galois scaffold is defined to be a variant of a normal basis that allows for an easy determination of valuation and thus has implications for the questions of the Galois module structure. We introduce a class of elementary abelian

p
p

-extensions of local function fields of characteristic

p
p

, which we call one-dimensional and which should be considered no more complicated than cyclic degree

p
p

extensions, and show that they, just as cyclic degree

p
p

extensions, possess a Galois scaffold.
Linear isometries between spaces of vector-valued Lipschitz functions
Authors: Jiménez-Vargas A. , Villegas-Vallecillos Moisés
Published: December 2008

In this paper we state a Lipschitz version of a theorem due to Cambern concerning into linear isometries between spaces of vector-valued continuous functions and deduce a Lipschitz version of a celebrated theorem due to Jerison concerning onto linear isometries between such spaces.
Mechanism of inhibition of tumor angiogenesis by β‐hydroxyisovalerylshikonin
Authors: Komi Yusuke , Suzuki Yasuhiro , Shimamura Mariko , Kajimoto Sachiko , Nakajo Shigeo , Masuda Michitaka , Shibuya Masabumi , Itabe Hiroyuki , Shimokado Kentaro , Oettgen Peter , Nakaya Kazuyasu , Kojima Soichi
Published: December 2008

Shikonin and β‐hydroxyisovalerylshikonin (β‐HIVS) from Lithospermum erythrorhizon inhibit angiogenesis via inhibition of vascular endothelial growth factor receptors (VEGFR) in an adenosine triphosphate‐non‐competitive manner, although the underlying molecular mechanism has not been fully understood. In the present study, we found that β‐HIVS inhibited angiogenesis within chicken chorioallantoic membrane approximately threefold more efficiently than shikonin. β‐HIVS also significantly inhibited angiogenesis in two other assays, induced either by Lewis lung carcinoma cells implanted in mouse dorsal skin or by VEGF in s.c. implanted Matrigel plugs and metastasis of Lewis lung carcinoma cells to lung. Therefore, using β‐HIVS as a bioprobe, we investigated the molecular mechanism of shikonin's anti‐angiogenic actions. β‐HIVS inhibited the phosphorylation and expression of VEGFR2 and Tie2 without affecting VEGFR1 and fibroblast growth factor receptor 1 levels. β‐HIVS suppressed the phosphorylation but not the expression of extracellular signal‐regulated kinase, and an Sp1‐dependent transactivation of the VEGFR2 and Tie2 promoters, thereby suppressing the proliferation of vascular endothelial and progenitor cells. This was mimicked by an Sp1 inhibitor mithramycin A and partially rescued by Sp1 overexpression. These results implicate potential use of shikonin and β‐HIVS as leading compounds for clinical application in the future by virtue of their unique properties including: (i) inhibition of VEGFR2 and Tie2 phosphorylation in an adenosine triphosphate‐non‐competitive manner; (ii) simultaneous inhibition of the phosphorylation and expression of VEGFR2 and Tie2; and (iii) bifunctional inhibition of the growth in endothelial cells and vascular remodeling. (Cancer Sci 2009; 100: 269–277)
Early clinical experience with adalimumab in treatment of inflammatory bowel disease with infliximab‐treated and naïve patients
Authors: SWAMINATH A. , ULLMAN T. , ROSEN M. , MAYER L. , LICHTIGER S. , ABREU M. T.
Published: December 2008

Background  Adalimumab, at an induction dose of 160/80 mg followed by 40 mg every other week is approved for treatment of refractory Crohn's disease (CD) and for patients with loss of response to infliximab.

Aim  To evaluate the indications for adalimumab, the proportion of inflammatory bowel disease patients who require dose escalation and to identify whether this strategy is effective in inducing or maintaining remission.

Methods  Patients prescribed adalimumab for CD were identified and included for analysis, if they had follow‐up of at least 6 weeks. Adalimumab dose was escalated if patients had return of symptoms prior to next dose. Clinical judgment was used to determine severity of disease. A second GI physician confirmed disease severity as determined by the first physician.

Results  A total of 48 out of 60 patients met inclusion criteria. Adalimumab was used to treat CD in 47/48 (98%) and ulcerative colitis in one (2%). Most patients had moderate 30/48 (63%) or severe 17/48 (35%) disease. Prior infliximab exposure was present in 42/48 (88%). Adalimumab dose escalation occurred in 14/48 (29%) within an average time of 2.2 months (s.d. 1.5 months). A majority of patients who required dose escalation, nine of 14 (64%) did not improve clinically. Steroids could be discontinued in three of 16 (18.8%). Clinical improvement was noted in 21/48 (43.8%) and one of 48 (2%) patients achieved clinical remission. Adverse drug reactions necessitated drug discontinuation in four of 48 (8%) of patients.

Conclusions  This retrospective review from a single academic medical centre suggests that a minority of patients, who cannot be maintained on 40 mg every other week, of adalimumab benefit from an increased dose. This suggests the need for a treatment with an alternative mode of action in anti‐TNF failures.
Prevalence and clinical correlates of JAK2 mutations in Down syndrome acute lymphoblastic leukaemia
Authors: Gaikwad Amos , Rye Cassia L. , Devidas Meenakshi , Heerema Nyla A. , Carroll Andrew J. , Izraeli Shai , Plon Sharon E. , Basso Giuseppe , Pession Andrea , Rabin Karen R.
Published: December 2008

Recurrent, prognostically significant chromosomal abnormalities occur in approximately 75% of paediatric acute lymphoblastic leukaemia (ALL), but only infrequently in children with Down syndrome (DS) and ALL. Recently, novel somatic activating mutations in the gene Janus kinase 2 (JAK2) were reported in 18% of DS ALL. Here we report identification and clinical correlates of JAK2 mutations in an independent cohort. JAK2 activating mutations occurred in 10/53 DS ALL cases (18·9%). Mutations were overrepresented in males (P < 0·03), occurred once in association with high hyperdiploidy and were not significantly correlated with age, initial white blood count, or event‐free survival. Our results confirm the significance of JAK–STAT pathway activation in DS ALL.
Barriers for dental treatment of primary teeth in East and West Germany
Authors: SPLIETH CHRISTIAN H. , BÜNGER BIANKA , PINE CYNTHIA
Published: December 2008

Background.  In many countries, restorative treatment in primary teeth is suboptimal.

Aim.  Thus, this study tried to detect barriers for dentists to restore primary teeth in kindergarten children (3–6 years).

Design.  For a representative survey, 320 dentists (184 West, 136 East Germany) were randomly selected from the dental associations’ registers and asked to answer a questionnaire on their profile, their view of the National Health System, and possible barriers for restoring primary teeth.

Results.  The analysis (response rate 57.7%) showed that the parents were no barrier and the dentists felt the need of restoring primary teeth. In addition to the children's anxiety, the inadequate reimbursement for fillings were perceived as clear barrier. The comparison of West and East German dentists detected statistically significantly higher barriers in West Germany, where – in contrast to the German Democratic Republic – no structured training in paediatric dentistry was compulsory before unification. Only 35% of the East German dentists rated restorative treatment in 3‐ to 6‐year‐olds as stressful in contrast to 65% in West Germany, where especially male dentists found no time to treat children.

Conclusion.  This study reveals that dentists can also be a considerable barrier to restorative treatment in small children, especially without adequate training in dental schools.