bluuebunny/crossref_metadata_2025 huggingface dataset:
Tribes Hill–Rochdale formations in east Laurentia: proxies for Early Ordovician (Tremadocian) eustasy on a tropical passive margin (New York and west Vermont)
Authors: LANDING ED , ADRAIN JONATHAN M. , WESTROP STEPHEN R. , KRÖGER BJÖRN
Published: August 2011

Slow subsidence and tectonic quiescence along the New York Promontory margin of Laurentia mean that the carbonate-dominated Tribes Hill and overlying Rochdale formations serve as proxies for the magnitude and timing of Tremadocian eustatic changes. Both formations are unconformity-bound, deepening–shoaling, depositional sequences that double in thickness from the craton into the parautochthonous, western Appalachian Mountains. A consistent, ‘layer cake’ succession of member-level units of the formations persists through this region. The Tribes Hill Formation (late early Tremadocian, late Skullrockian, late Fauna B–Rossodus manitouensisChron) unconformably overlies the terminal Cambrian Little Falls Formation as the lowest Ordovician unit on the New York Promontory. It was deposited during the strong early Tremadocian, or Stonehenge, transgression that inundated Laurentia, brought dysoxic/anoxic (d/a) slope water onto the shelf and led to deposition of the Schaghticoke d/a interval (black mudstone and ‘ribbon limestone’) on the Laurentian continental slope. The uniform lithofacies succession of the Tribes Hill includes a lower sand-rich member; a middle, dark grey to black mudstone that records d/a in eastern exposures; and an upper, shoaling-up carbonate highstand facies. A widespread (12000+ km2) thrombolitic interval in the highstand carbonate suggests the New York Promontory was rimmed by thrombolites during deposition of the Tribes Hill. Offlap and erosion of the Tribes Hill was followed by the relatively feeble sea-level rise of the Rochdale transgression (new) in Laurentia, and deposition of the Rochdale Formation. The Rochdale transgression, correlated with theKierograptusDrowning Interval in Baltica, marks a eustatic rise. The Rochdale Formation represents a short Early Ordovician interval (early late Tremadocian, middle–late Stairsian,Macerodus dianaeChron). It correlates with a depositional sequence that forms the middle Boat Harbour Formation in west Newfoundland and with the Rte 299 d/a interval on the east Laurentian slope. The Rochdale has a lower carbonate with abundant quartz silt (Comstock Member, new) and an upper, thrombolitic (Hawk Member, new) high-stand facies. Tribes Hill and Rochdale faunas are mollusc-rich, generally trilobite-poor, and have low diversity, Laurentian faunal province conodonts.Ulrichodina rutnikaLanding n. sp. is rare in Rochdale conodont assemblages. Trilobites are also low in diversity, but locally form coquinas in the middle Tribes Hill. The poorly preserved Rochdale trilobites include the bathyuridRandaynia, at least two hystricurid species andLeiostegium.
Description and ecology of a new Middle Ordovician (Llanvirn) odontopleurid trilobite from the Builth Inlier of Mid-Wales, with a review of the genusMeadowtownella
Authors: CONWAY TIM M. , BOTTING JOSEPH P.
Published: August 2011

A new odontopleurid trilobite,Meadowtownella serrata, is described from a new Llanvirnian (Darriwilian;Didymograptus murchisoniBiozone) locality in the Builth Inlier, Mid-Wales. This unusually spinose species displays a remarkable array of pygidial spines and extends the stratigraphic range of the genus back into the Abereiddian. Benthic faunas are rare in the predominantly ‘anoxic’D. murchisoniBiozone of the Welsh Basin, and these beds are an unusual habitat for odontopleurids. Environmental analyses (framboidal pyrite and associated total organic carbon) in this study, together with the distribution of benthic faunas (described and figured) in the section, indicate a likely oxic water column and episodically oxic bottom waters. A new diagnosis forMeadowtownellais presented with a review of the genus, as a clarification of previous work. The greater spinosity of earlier members of the lineage may reflect either changing environmental preferences, or the derivation ofMeadowtownellafrom an original more spinose lineage.
Representing Queerness: Clifton Webb on the American Stage
Authors: LEFF LEONARD J.
Published: August 2011

In the American theater of the 1930s and 1940s, the designation “queer star” was an oxymoron – except when applied to Clifton Webb. The Indiana-born singer and dancer was (according to colleagues) homosexual and (according to critics and audiences) queer. He was also, after 1932, a star on Broadway and the road as well as a reliably queer presence in the gossip columns and arts pages of the daily paper. Unlike any other show business personality of his rank, he used his star text to raise the visibility of queerness in early twentieth-century entertainment culture.
Seroprevalence ofToxoplasma gondiiandNeospora caninumin slaughtered pigs in the Czech Republic
Authors: BÁRTOVÁ E. , SEDLÁK K.
Published: August 2011

In the Czech Republic, sera from 551 clinically healthy adult slaughtered pigs (females, 6–8 months old) were collected during the first half of June in 2010. Sera were tested forToxoplasma gondii-specific IgG antibodies by an enzyme-linked immunosorbent assay; samples with more than 50% S/P were considered as positive. The same samples were also analysed forNeospora caninumantibodies using a commercial competitive-inhibition enzyme-linked immunosorbent assay; samples with more than 30% inhibition were considered as positive. Antibodies againstT. gondiiwere found in 198 pigs (36%) in all districts with prevalences ranging from 18% to 75%. Antibodies againstN. caninumwere found in 16 pigs (3%); positive animals were found in 4 districts with prevalences ranging from 1% to 20%. Indication of mixed infections (concurrent presence of bothN. caninumandT. gondiiantibodies) was found in 8 (1·5%) pigs. The results of our study indicate that pigs in the Czech Republic have a relatively high seroprevalence forT. gondii, while they have only a low seroprevalence forN. caninum. Therefore, natural infection withT. gondiiseems to be very common in Czech pigs. It is the first evidence ofN. caninumantibodies in pigs in the Czech Republic. These results complete data aboutN. caninuminfection in pigs in Europe.
The loading of labelled antibody-engineered nanoparticles with Indinavir increases itsin vitroefficacy againstCryptosporidium parvum
Authors: BONDIOLI L. , LUDOVISI A. , TOSI G. , RUOZI B. , FORNI F. , POZIO E. , VANDELLI M. A. , GÓMEZ-MORALES M. A.
Published: August 2011

There is much evidence to indicate the ability of Indinavir (IND) to reduceCryptosporidium parvuminfection in bothin vitroandin vivomodels. However, there are limitations to the administration of IND as such, due to its renal toxicity and the high rate of metabolism and degradation. We aimed to encapsulate IND in biodegradable poly (D,L-lactide-co-glycolide) nanoparticles (Np) and to engineer their surface by conjugation with an anti-CryptosporidiumIgG polyclonal antibody (Ab). Tetramethylrhodamine-labelled Np were loaded with IND and modified by conjugation with an Ab. The IND-loaded modified Np (Ab-TMR-IND-Np) did not show any change, as demonstrated by chemical analysis studies. Simultaneous addition of 50μM Ab-TMR-IND-Np and excysted oocysts to the cell culture resulted in complete inhibition of the infection. InC. parvum-infected cells, the extent to which the infection decreased depended on the duration of treatment with the Ab-TMR-IND-Np. The antibody-engineered Np loaded with IND were able to targetC. parvumin infected cells and therefore might represent a novel therapeutic strategy againstCryptosporidiumsp. infection. Moreover, the use of Np as an IND delivery device, allows the development of a more appropriate dose formulation thereby reducing the IND side effects.
Variation in growth and drug susceptibility amongGiardia duodenalisassemblages A, B and E in axenicin vitroculture and in the gerbil model
Authors: BÉNÉRÉ E. , VAN ASSCHE T. , COS P. , MAES L.
Published: August 2011

This study investigated the molecular and biological variation among differentGiardia duodenalisassemblages.In vitrogrowth and susceptibility to albendazole, fenbendazole, flubendazole, metronidazole, tinidazole and furazolidone was studied for laboratory (AI: WB, AII: G1 and B: GS/M-83-H7) and 6 field isolates of assemblage subtype AI, AII, B and EIII. Additionally, isolates of the 3 assemblages were evaluated in the gerbil upon 3-day oral treatment with albendazole (6 mg/kg), flubendazole (5 mg/kg) and metronidazole (20 mg/kg). Assemblage AIgrew significantly faster than all other assemblage subtypes, which showed comparable generation times. The assemblage A laboratory strains displayed alteredin vitrodrug susceptibilities compared to their matching AIor AIIfield isolate. No variation in drug susceptibility was observed between field isolates of assemblages A and E. However, assemblage A laboratory strains were more susceptible to the benzimidazoles and less susceptible to the nitro-imidazoles and furazolidone than the assemblage B laboratory strain. In the gerbil, no markedly different drug susceptibilities were observed. In conclusion, theGiardiaassemblage subtype can be associated with differences in growth characteristics rather than in drug susceptibility.
Optimal mapping of joint faults into healthy joint velocity space for fault-tolerant redundant manipulators
Authors: Abdi Hamid , Nahavandi Saeid , Frayman Yakov , Maciejewski Anthony A.
Published: August 2011

Self-reconfiguration of robotic manipulators under joint failure can be achieved via fault-tolerance strategies. Fault-tolerant manipulators are required to continue their end-effector motion with a minimum velocity jump, when failures occur to their joints. Optimal fault tolerance of the manipulators requires a framework that can map the velocity jump of the end-effector to the compensating joint velocity commands. The main objective of the present paper is to propose a general framework for the fault tolerance of the manipulators, which can minimize the end-effector velocity jump. In the present paper, locked joint failures of the manipulators are modeled using matrix perturbation methodology. Then, the optimal mapping for the faults with a minimum end-effector velocity jump is presented. On the basis of this mapping, the minimum end-effector velocity jump is calculated. A generalized framework is derived from the extension of optimal mapping toward multiple locked joint failures. Two novel expressions are derived representing the generalized optimal mapping framework and the generalized minimum velocity jump. These expressions are suitable for the optimal fault tolerance of the serial link redundant manipulators. The required conditions for a zero end-effector velocity jump of the manipulators are analyzed. The generalized framework in this paper is then evaluated for different failure scenarios for a 5-DOF planar manipulator and a 5-DOF spatial manipulator. The validation includes three case studies. While the first two are instantaneous studies, the third one is for the whole trajectory of the manipulators. From the results of these case studies, it is shown that, when locked joint faults occur, the faulty manipulator is able to optimally maintain its velocity with a zero end-effector velocity jump if the conditions of a zero velocity jump are hold.
Joint stiffness identification of industrial serial robots
Authors: Dumas Claire , Caro Stéphane , Cherif Mehdi , Garnier Sébastien , Furet Benoît
Published: August 2011

This paper presents a new methodology for the joint stiffness identification of industrial serial robots and as consequence for the evaluation of both translational and rotational displacements of the robot's end-effector subject to an external wrench (force and torque). In this paper, the robot's links are supposed to be quite stiffer than the actuated joints as it is usually the case with industrial serial robots. The robustness of the identification method and the sensitivity of the results to measurement errors, and the number of experimental tests are also analyzed. The Kuka KR240-2 robot is used as an illustrative example throughout the paper.
Robust design of multiscale programs to reduce deforestation
Authors: CATTANEO ANDREA
Published: August 2011

A framework is provided for structuring programs aimed at reducing emissions from deforestation and forest degradation (REDD). Crediting reference levels and the coordination among different implementing entities at multiple geographic scales are discussed. A crediting reference level has an error component if it differs from the business-as-usual (BAU) without REDD. Both the BAU emissions and the impact of REDD actions are uncertain, implying that participating in REDD entails stakeholder risk, the distribution of which depends on REDD program design. To categorize REDD architectures we definescale-neutralitywhereby, for a given REDD design, crediting relative to the reference level at a given scale is not affected by errors in reference levels at scales below it. Sufficient conditions are derived for scale-neutrality to hold. A Brazilian Amazon example is provided, comparing potential REDD architectures, and highlighting how a cap-and-trade approach may match the environmental outcome obtainable with perfect foresight of the BAU emissions.
What is ‘minimal’ anyway? John Pawson: Plain Space at the Design Museum and About a Minute at the Gopher Hole
Authors: Reynolds Jessica
Published: August 2011

Architecture shows and biennales have proliferated in the last decade, accompanied by new courses and publications on architectural curation. The curation of an exhibition can be as complex and political as the realisation of a work of architecture. It can be presented as an effective vehicle for critical discourse, challenging the traditional definition of architectural practice as the design, procurement and construction of a building. In response, existing architecture exhibition spaces are adapting and new galleries are opening, reconceptualising modes of display. This review considers two contrasting architecture exhibitions on show in London at the turn of 2011, each with different agendas, ambitions and audiences.
Porticoes and churches: episodes in thematic decorum
Authors: Hill Michael , Kohane Peter
Published: August 2011

A classical church portico – say, St Paul's in London – implies a rite of passage and mediation between the city and the interior rituals of the institution; it beckons the street, while offering shelter to those who want to observe the crowd. In contrast, the spectacular interiors of Modernist churches are often entered without theatre – the plain outer door [1], for example, of Jørn Utzon's Bagsværd Church (Copenhagen, 1973), provides little hint of the magical cloud-like movement of vaulted space within. This is not simply a matter of the changing formal language of architecture (namely, interior space taking priority over exterior shell), but also how the church might be defined in wider civic and historical contexts. Here the Classical theory of decorum remains helpful, for Vitruvius proposed that identifying a building's theme (statione) – that is, the social and institutional destination of the building – was the first step in determining appropriate form, the prerequisite one before considering the related determinates of decor, namely stylistic coherence (consuetudine) and site (natura). The issue of thematic appropriateness is above all important for the front, which announces the building like a frontispiece does a text. Yet as the church portico demonstrates, a thematic motif was rarely the straightforward application of a code, for in the period when architectural decorum prevailed – loosely speaking the fifteenth to nineteenth century in Italy, France and England among other places – how a genre was defined and what constituted the repertoire of appropriate form were contested.
Political or dental power in private and public service provision: a study of municipal expenditures for child dental care
Authors: Andersen Lotte Bøgh , Bech Mickael , Lauridsen Jørgen
Published: August 2011

Both professionals and politicians may affect expenditures for highly professional services provided in the public and private sector. We investigated Danish publicly financed child dental care with a special focus on the influence of politicians and dentists on the expenditure level. By studying spatial patterns in expenditure levels across municipalities, we are able to test the influences of these two main actors and the networks through which learning is achieved. Four hypotheses on the existence of different spatial spillover effects are tested. The empirical analysis is based on annual data from 1996 to 2001 for 226 Danish municipalities, thus allowing for the control for heterogeneity between municipalities and for intra-municipal correlations across time. The results point to differences in expenditures between municipalities with privately and publicly produced dental care. Furthermore, dentists appear to be the most important actors for the spatial spillover effects, and these effects are especially strong for municipalities situated in the same county that use private dental clinics. There is no evidence of political spatial spillover effects between municipalities.
NOAA draft scientific integrity policy: Comment period open through 20 August
Authors: Showstack Randy
Published: August 2011

The National Oceanic and Atmospheric Administration (NOAA) is aiming to finalize its draft scientific integrity policy possibly by the end of the year, Larry Robinson, NOAA assistant secretary for conservation and management, indicated during a 28 July teleconference. The policy “is key to fostering an environment where science is encouraged, nurtured, respected, rewarded, and protected,” Robinson said, adding that the agency's comment period for the draft policy, which was released on 16 June, ends on 20 August. “Science underpins all that NOAA does. This policy is one piece of a broader effort to strengthen NOAA science,” Robinson said, noting that the draft “represents the first ever scientific integrity policy for NOAA. Previously, our policy only addressed research misconduct and focused on external grants. What's new about this policy is that it establishes NOAA's principles for scientific integrity, a scientific code of conduct, and a code of ethics for science supervision and management.”
Constraining the trigger for an ancient warming episode
Authors: Schultz Colin
Published: August 2011

The Paleocene epoch (∼66–56 million years ago) was sandwiched between sudden climate shifts and mass extinctions. The boundary between the end of the Paleocene and the beginning of the Eocene (the P‐E boundary) saw the global average temperature soar by 5°C over a few thousand years, leading to a pronounced reorganization of both terrestrial and oceanic plant and animal communities. The P‐E boundary warming was triggered by an influx of atmospheric carbon dioxide, but the influx's ultimate trigger is still being debated. Other prominent warming events within the Paleogene (∼66–23 million years ago), the broad time span that encompasses the Paleocene and Eocene, have been linked to regularly recurring changes in the eccentricity of the Earth's orbit that take place on 100,000‐ and 405,000‐year cycles. Proponents of this view suggest that an alignment of the two cycles could lead to the warming of deep ocean waters, melting frozen methane and triggering an increase in atmospheric carbon dioxide. However, some studies have suggested that the P‐E boundary warming was instead the product of geological processes, where carbon‐rich rocks were baked by injected magma, which eventually liberated the carbon to the atmosphere. Deciding between proposed explanations for the cause of the P‐E warming, whether they are astronomical or geological, depends on accurately pinning the event in time. (Geochemistry, Geophysics, Geosystems, doi:10.1029/2010GC003426, 2011)
Are the world's oceans optically different?
Authors: Szeto M. , Werdell P. J. , Moore T. S. , Campbell J. W.
Published: August 2011

Regional differences in the Sea‐viewing Wide Field‐of‐view Sensor chlorophyll algorithm uncertainty were observed in a large global data set containing coincident in situ measurements of chlorophyll a concentration (Chla) and spectral radiometry. The uncertainty was found to be systematic when the data were sorted by ocean: Atlantic, Pacific, Southern, and Indian Oceans. Artifacts associated with different instrumentation and analytical methods had been previously ruled out. Given these oceanic biases in the chlorophyll algorithm, we hypothesized that the oceans may be optically different, and their optical differences may be intrinsically related to regional differences in phytoplankton community structure or biogeochemical processes. The oceanic biases, originally observed using radiometric measurements, were independently verified using total absorption measurements in a subset of the data. Moreover, they were explained through oceanic differences in the absorption of colored detrital matter (CDM) and phytoplankton. Both effects were considered together in explaining the ocean biases through a stepwise linear regression analysis. Significant oceanic differences in the amount of CDM and in phytoplankton cell sizes and pigmentation would give rise to optical differences, but we raise a concern for the spatial coverage of the data. We do not suggest the application of ocean‐based algorithms but rather emphasize the importance of consolidating regional data sets before reaching this conclusion.
An MPI/GPU parallelization of an interior penalty discontinuous Galerkin time domain method for Maxwell's equations
Authors: Dosopoulos Stylianos , Gardiner Judith D. , Lee Jin‐Fa
Published: August 2011

In this paper we discuss our approach to the MPI/GPU implementation of an Interior Penalty Discontinuous Galerkin Time domain (IPDGTD) method to solve the time dependent Maxwell's equations. In our approach, we exploit the inherent DGTD parallelism and describe a combined MPI/GPU and local time stepping implementation. This combination is aimed at increasing efficiency and reducing computational time, especially for multiscale applications. The CUDA programming model was used, together with non‐blocking MPI calls to overlap communications across the network. A 10× speedup compared to CPU clusters is observed for double precision arithmetic. Finally, for p = 1 basis functions, a good scalability with parallelization efficiency of 85% for up to 40 GPUs and 80% for up to 160 CPU cores was achieved on the Ohio Supercomputer Center's Glenn cluster.
Profound change of the near‐Earth radiation environment caused by solar superstorms
Authors: Shprits Yuri , Subbotin Dmitriy , Ni Binbin , Horne Richard , Baker Daniel , Cruce Patrick
Published: August 2011

The outer radiation belt is often enhanced during storms while the inner belt is usually considered to be unaffected by geomagnetic activity. During the most recent Halloween superstorms, the extreme erosion of the plasmasphere allowed particles to be transported closer to the Earth where they were locally accelerated. Modeling, which now includes transport with resonant acceleration and loss processes and mixed diffusion, shows a rather good correspondence with observations. In this study, we use the same version of the VERB code to model a storm stronger than the Halloween storms, which most likely occurred in the past and may occur in the future. Our simulations indicate that during such a strong event, electrons will be transported into the heart of the inner zone, where they will be accelerated by chorus waves. When the plasmapause extends to larger distances, electrons accelerated by resonant wave‐particle interactions in the inner radiation belt will find themselves in a very different plasma environment and strong fluxes may persist for several years after such a storm. Such intensification of the near‐Earth plasma environment would substantially decrease satellite lifetimes at LEO. The radiation mitigation strategy for satellites operating in the inner belt should include a consideration of the potential for a dramatic increase in the near‐Earth radiation. Such intensification of the near‐Earth radiation environment may be truly devastating and would substantially decrease the lifetimes of meteorological, communication, and military satellites.
A combined NLP‐differential evolution algorithm approach for the optimization of looped water distribution systems
Authors: Zheng Feifei , Simpson Angus R. , Zecchin Aaron C.
Published: August 2011

This paper proposes a novel optimization approach for the least cost design of looped water distribution systems (WDSs). Three distinct steps are involved in the proposed optimization approach. In the first step, the shortest‐distance tree within the looped network is identified using the Dijkstra graph theory algorithm, for which an extension is proposed to find the shortest‐distance tree for multisource WDSs. In the second step, a nonlinear programming (NLP) solver is employed to optimize the pipe diameters for the shortest‐distance tree (chords of the shortest‐distance tree are allocated the minimum allowable pipe sizes). Finally, in the third step, the original looped water network is optimized using a differential evolution (DE) algorithm seeded with diameters in the proximity of the continuous pipe sizes obtained in step two. As such, the proposed optimization approach combines the traditional deterministic optimization technique of NLP with the emerging evolutionary algorithm DE via the proposed network decomposition. The proposed methodology has been tested on four looped WDSs with the number of decision variables ranging from 21 to 454. Results obtained show the proposed approach is able to find optimal solutions with significantly less computational effort than other optimization techniques.
Environmental Pursuits In Nanomaterial Systems Science With Indian Exemplars
Authors: Sen Ranen , Seth Dipankar , Roy Indrani , Dasgupta Debmalya , Goswami Arunava
Published: August 2011

The behavior and pattern of NPs of minerals in the evolutionary history of the earth vis – a –vis the environmental context are inquired into, with a riverine system as a model. The study of fractal dimensions of NPs of interest serves as an aid to obtain a comprehensive view of natural NPs in the model system. The present study combines inputs from work done on nanoparticles, derived from the Subanarekha River System and products of base metal mine effluents that are rich in NPs of minerals. The authors believe this study would help to establish certain universalities about NPs and provide an updated framework for understanding the current state of nanomineral science.
Soil Disturbance Increases Soil Microbial Enzymatic Activity in Arid Ecoregions
Authors: Schwab-Uchanski Lori Kae , Unc Adrian , Lucero Mary
Published: August 2011

Functional diversity of the soil microbial community is commonly used in the assessment of soil health as it relates to the activity of soil microflora involved in carbon cycling. Soil microbes in different microenvironments will have varying responses to different substrates, thus catabolic fingerprint information of each location-specific community can be obtained. The purpose of this study was to evaluate total-soil enzymatic activity profiles across three disturbance regimes in an arid desert grassland in the Southwestern United States. Microbial enzymatic activity was measured using the MicroResp™ system, which measures respiration of microbes within whole soil samples supplemented with various carbon sources (simple and polymeric sugars, amino acids, carboxylic acids, and fatty acids - tests run in the absence of light). Total bacterial diversity was assessed by 16s DNA pyrosequencing. Microbial activity was greatest and most variable in sites exposed to disturbance (grazing, natural gas extraction). Decoupling the C cycle from the C-fixing cyanobacteria may induce more diverse C uptake pathways associated with a more diverse microbial population. Similarities in taxonomic diversity and C substrate utilization patterns show that, for arid lands, any degradation-enhanced heterogeneity in soil’s biotic and abiotic parameters may drive changes in soils towards higher functional diversity to adapt to the disturbance.
Rapid bioassay for evaluating enzyme production in fungal isolates from environmental sources
Authors: Bordo Eleonora , Luziatellie Francesca , Crognale Silvia , Marinari Sara , Grego Stefano , Ruzzi Maurizio
Published: August 2011

Fungal hydrolytic enzymes have a great potential due to the rapid development of enzyme technology and their industrial applications. A fluorimetric microplate assay has been developed for measuring activity of β-D-exoglucanase, β-D-glucosidase, α-D-glucosidase, β-N-acetyl-hexosaminidase, β-D-xylosidase in diluted culture broth samples. The substrates used are conjugates of the highly fluorescent compounds 4-methylumbelliferone (MUB) and thus product formation can be measured directly in the microplate without previous extraction and purification of the product. The developed system was evaluated on eight fungal strains isolated from shrub species (Tamarix) that can be used in phytoremediation. Depending upon the enzyme, each species exhibited different levels of enzymatic activities as well as different production profiles. The fluorimetric method could constitute an effective alternative to the pectrophotometric method to screen hydrolase-producing microbial strains.
Peripheral insertion modulates the editing activity of the isolated CP1 domain of leucyl-tRNA synthetase
Authors: Liu Ru-Juan , Tan Min , Du Dao-Hai , Xu Bei-Si , Eriani Gilbert , Wang En-Duo
Published: August 2011

A large insertion domain called CP1 (connective peptide 1) present in class Ia aminoacyl-tRNA synthetases is responsible for post-transfer editing. LeuRS (leucyl-tRNA synthetase) from Aquifex aeolicus and Giardia lamblia possess unique 20 and 59 amino acid insertions respectively within the CP1 that are crucial for editing activity. Crystal structures of AaLeuRS-CP1 [2.4 Å (1 Å=0.1 nm)], GlLeuRS-CP1 (2.6 Å) and the insertion deletion mutant AaLeuRS-CP1Δ20 (2.5 Å) were solved to understand the role of these insertions in editing. Both insertions are folded as peripheral motifs located on the opposite side of the proteins from the active-site entrance in the CP1 domain. Docking modelling and site-directed mutagenesis showed that the insertions do not interact with the substrates. Results of molecular dynamics simulations show that the intact CP1 is more dynamic than its mutant devoid of the insertion motif. Taken together, the data show that a peripheral insertion without a substrate-binding site or major structural role in the active site may modulate catalytic function of a protein, probably from protein dynamics regulation in two respective LeuRS CP1s. Further results from proline and glycine mutational analyses intended to reduce or increase protein flexibility are consistent with this hypothesis.
Relativistically strong Langmuir turbulence in the kinetic regime
Authors: Liu X. L. , Li X. Q. , Liu S. Q.
Published: August 2011

Using a kinetic description, the relativistically strong Langmuir turbulence is investigated, which has considered the nonlinear wave–wave, wave–particle interactions and the relativistic effects of electrons. The relativistic Zakharov equations have been obtained. On the basis of these equations, dynamics of collapse has been studied. It is shown that the field strength of relativistic Langmuir plasmons will increase and the ponderomotive expulsion of particles gives rise to the formation of density caviton during the collapsing, which is useful for understanding the natural structural element of relativistically strong Langmuir turbulence
Tuning electronic transport of ZnO micro/nanowires by a transverse electric field
Authors: Zhang Qi , Qi Junjie , Huang Yunhua , Li Xin , Zhang Yue
Published: August 2011

Electronic transport of individual ZnO micro/nanowires was tuned by applying a transverse electric field, and the diameter effect on carrier mobility in that process was measured. Surface charges induced by the external field modulate longitudinal electronic transport in wires and a minimum conductivity was obtained in the negative electric field. Electron mobility deduced from conductivity versus surface-charge was in agreement with the value obtained from the current-voltage characteristics. Moreover, electron mobility of the wire decreases as its diameter increases in a constant transverse electric field, which was not observed without the transverse electric field. We also discuss the possible mechanisms.
Laboratory test reactor for the investigation of liquid reducing agents in the selective catalytic reduction of NOx
Authors: Peitz D. , Bernhard A. , Elsener M. , Kröcher O.
Published: August 2011

A test reactor was designed and built for investigating liquid reducing agents in the selective catalytic reduction (SCR) process in the laboratory. The design of the experimental setup is described in detail and its performance was evaluated. Using a glass nebulizer, liquid reducing agents were sprayed directly onto a catalyst positioned in a heated glass reactor with a length of 250 mm and an internal diameter of 20.4 mm or 40 mm. Model exhaust gases were mixed from individual gas components and were heated up to 450 °C in a heat exchanger before entering the reactor. The off-gas was analyzed using two complimentary techniques, a multi-component online FTIR gas analysis and a liquid quench gas absorption setup, to detect higher molecular compounds and aerosols. Due to the versatility of construction, processes not related to SCR, but involving three-phase reactions with gases, liquids and a catalyst, can also be investigated.
The relationship between double excitation amplitudes and Z vector components in some post-Hartree-Fock correlation methods
Authors: Kollmar Christian , Neese Frank
Published: August 2011

The relationship between Z vector components and excitation amplitudes is analyzed for several post-Hartree-Fock correlation methods limited to double excitation amplitudes. An analytical formula approximating the Z vector for the coupled cluster doubles method is presented and shown to be quite accurate. This approximation is also used to determine the prefactor of the norm of doubly excited states in averaged coupled pair functional-type energy functionals self-consistently leading to better agreement with coupled cluster results.
Impact of a few dopant positions controlled by deterministic single-ion doping on the transconductance of field-effect transistors
Authors: Hori Masahiro , Shinada Takahiro , Ono Yukinori , Komatsubara Akira , Kumagai Kuninori , Tanii Takashi , Endoh Tetsuo , Ohdomari Iwao
Published: August 2011

As semiconductor device dimensions decrease, the individual impurity atom position becomes a critical factor in determining device performance. We fabricated transistors with ordered and random dopant distributions on one side of the channel and evaluated the transconductance to investigate the impact of discrete dopant positions on the electron transport properties. The largest transconductance was observed when dopants were placed on the drain side in an ordered distribution; this was attributed to the suppression of injection velocity degradation on the source side and the uniformity of the electrostatic potential. Thus, the control of discrete dopant positions could enhance the device performance.
Shape dependence of slip length on patterned hydrophobic surfaces
Authors: Gu Xiaokun , Chen Min
Published: August 2011

The effects of solid-liquid interfacial shape on the boundary velocity slip of patterned hydrophobic surfaces are investigated. The scaling law in literature is extended to demonstrate the role of such shape, indicating a decrease of the effective slip length with increasing interfacial roughness. A patterned surface with horizontally aligned carbon nanotube arrays reaches an effective slip length of 83 nm, by utilizing large intrinsic slippage of carbon nanotube while keeping away from the negative effects of interfacial curvature through the flow direction. The results emphasize the importance of avoiding the solid-liquid interfacial roughness in low-friction patterned surface design and manufacture.
Communication: Where does the first water molecule go in imidazole?
Authors: Zischang Julia , Lee Juhyon J. , Suhm Martin A.
Published: August 2011

Supersonic jet FTIR spectroscopy supplemented by 18O substitution shows unambiguously that water prefers to act as an O−H⋅⋅⋅N hydrogen bond donor towards imidazole, instead of acting as a N−H⋅⋅⋅O acceptor. Previous matrix isolation, helium droplet, and aromatic substitution experiments had remained ambiguous, as are standard quantum chemical calculations. The finding is supported by a study of the analogous methanol complexes and by higher level quantum chemical calculations.
Phonon deformation potentials of hexagonal GaN studied by biaxial stress modulation
Authors: Lu Jun-Yong , Deng Dong-Mei , Wang Yong , Chen Kevin Jing , Lau Kei-May , Zhang Tong-Yi
Published: August 2011

In this work, a biaxial stress modulation method, combining the microfabrication technique, finite element analysis and a weighted averaging process, was developed to study piezospectroscopic behavior of hexagonal GaN films, epitaxially grown by metalorganic chemical vapor deposition on c-sapphire and Si (111) substrates. Adjusting the size of patterned islands, various biaxial stress states could be obtained at the island centers, leading to abundant stress-Raman shift data. With the proposed stress modulation method, the Raman biaxial stress coefficients of $E_2^H$E2H and A1 (LO) phonons of GaN were determined to be 3.43 cm-1/GPa and 2.34 cm-1/GPa, respectively.
Rhus glabra response to season and intensity of fire in tallgrass prairie
Authors: Hajny Kristy M. , Hartnett David C. , Wilson Gail W. T.
Published: August 2011

Altered fire regimes play a key role in shrub expansion in grasslands worldwide. We assessed how season and type or intensity of fire affected the growth and demography of Rhus glabra, a common woody invader in North American mesic grasslands. Fire during any season killed 99% of ramets but stimulated new ramet recruitment from belowground buds, resulting in a near-complete turnover of ramet populations. During the first 2 years following fire, populations on spring-burned sites had the greatest post-fire ramet densities and population growth rates, and winter- and spring-burned populations showed the highest resprouting rates. However, after 10 years, R. glabra cover on summer-burned sites was 3.5 times greater than on autumn- or winter-burned treatments. Thus, short-term post-fire responses may not be good predictors of long-term changes in abundance. Low-intensity spring backfires resulted in the highest ramet population growth rates, whereas high-intensity headfires in any season resulted in slower growth, and populations burned with low-intensity winter fires declined. In addition, season of fire influenced browsing pressure, suggesting that plant responses may be partially a result of indirect effects of fire on rates of herbivory. Overall, our results demonstrate that the application of frequent autumn or winter backfires is an effective management tool for limiting R. glabra expansion in grasslands, and that long-term data are critical for management decision-making, particularly in systems characterised by high interannual climate variability.
Assessing the susceptibility of semiarid rangelands to wildfires using Terra MODIS and Landsat Thematic Mapper data
Authors: Chen Fang , Weber Keith T. , Anderson Jamey , Gokhal Bhushan
Published: August 2011

In order to monitor wildfires at broad spatial scales and with frequent periodicity, satellite remote sensing techniques have been used in many studies. Rangeland susceptibility to wildfires closely relates to accumulated fuel load. The normalised difference vegetation index (NDVI) and fraction of photosynthetically active radiation (fPAR) are key variables used by many ecological models to estimate biomass and vegetation productivity. Subsequently, both NDVI and fPAR data have become an indirect means of deriving fuel load information. For these reasons, NDVI and fPAR, derived from the Moderate Resolution Imaging Spectroradiometer on-board Terra and Landsat Thematic Mapper imagery, were used to represent prefire vegetation changes in fuel load preceding the Millennial and Crystal Fires of 2000 and 2006 in the rangelands of south-east Idaho respectively. NDVI and fPAR change maps were calculated between active growth and late-summer senescence periods and compared with precipitation, temperature, forage biomass and percentage ground cover data. The results indicate that NDVI and fPAR value changes 2 years before the fire were greater than those 1 year before fire as an abundance of grasses existed 2 years before each wildfire based on field forage biomass sampling. NDVI and fPAR have direct implication for the assessment of prefire vegetation change. Therefore, rangeland susceptibility to wildfire may be estimated using NDVI and fPAR change analysis. Furthermore, fPAR change data may be included as an input source for early fire warning models, and may increase the accuracy and efficiency of fire and fuel load management in semiarid rangelands.
Recent trends in post-wildfire seeding in western US forests: costs and seed mixes
Authors: Peppin Donna L. , Fulé Peter Z. , Sieg Carolyn Hull , Beyers Jan L. , Hunter Molly E. , Robichaud Peter R.
Published: August 2011

Broadcast seeding is one of the most commonly used post-fire rehabilitation treatments to establish ground cover for erosion control and mitigation of non-native plant species invasions. Little quantitative information is available on overall trends of post-fire seeding expenditures and seed mixes used over time in forested ecosystems in the western USA. We reviewed scientific articles, government publications and unpublished documents as well as USDA Forest Service Burned Area Reports to determine trends in post-fire seeding in forested ecosystems over time. Of 1164 USDA Forest Service Burned Area Reports, 380 contained information on seeding treatments conducted in forested ecosystems. A review of 40 papers and 67 Burned Area Reports reporting species seeded between 1970 and 2007 revealed a trend of increasing use of native species, annual cereal grains and sterile-grass hybrids, with natives dominating seed mixes. According to 380 Burned Area Reports with data on costs and area seeded, total post-fire seeding expenditures have increased substantially, averaging US$3.3 million per year spent on post-fire emergency seeding treatments in forested ecosystems that involved the Forest Service during the period 2000 to 2007 – an increase of 192% compared with the average spent during the previous 30 years. The percentage of the total burned area seeded averaged 21% in the 1970s, compared with only 4% between 2000 and 2007.
Biologically induced initiation of Neoproterozoic snowball-Earth events
Authors: Tziperman Eli , Halevy Itay , Johnston David T. , Knoll Andrew H. , Schrag Daniel P.
Published: August 2011

The glaciations of the Neoproterozoic Era (1,000 to 542 MyBP) were preceded by dramatically light C isotopic excursions preserved in preglacial deposits. Standard explanations of these excursions involve remineralization of isotopically light organic matter and imply strong enhancement of atmospheric CO
2
greenhouse gas concentration, apparently inconsistent with the glaciations that followed. We examine a scenario in which the isotopic signal, as well as the global glaciation, result from enhanced export of organic matter from the upper ocean into anoxic subsurface waters and sediments. The organic matter undergoes anoxic remineralization at depth via either sulfate- or iron-reducing bacteria. In both cases, this can lead to changes in carbonate alkalinity and dissolved inorganic pool that efficiently lower the atmospheric CO
2
concentration, possibly plunging Earth into an ice age. This scenario predicts enhanced deposition of calcium carbonate, the formation of siderite, and an increase in ocean pH, all of which are consistent with recent observations. Late Neoproterozoic diversification of marine eukaryotes may have facilitated the episodic enhancement of export of organic matter from the upper ocean, by causing a greater proportion of organic matter to be partitioned as particulate aggregates that can sink more efficiently, via increased cell size, biomineralization or increased C∶N of eukaryotic phytoplankton. The scenario explains isotopic excursions that are correlated or uncorrelated with snowball initiation, and suggests that increasing atmospheric oxygen concentrations and a progressive oxygenation of the subsurface ocean helped to prevent snowball glaciation on the Phanerozoic Earth.
ADP ribosylation factor 6 (ARF6) controls amyloid precursor protein (APP) processing by mediating the endosomal sorting of BACE1
Authors: Sannerud Ragna , Declerck Ilse , Peric Aleksandar , Raemaekers Tim , Menendez Guillermo , Zhou Lujia , Veerle Baert , Coen Katrijn , Munck Sebastian , De Strooper Bart , Schiavo Giampietro , Annaert Wim
Published: August 2011

Amyloid β (Aβ) peptides, the primary constituents of senile plaques and a hallmark in Alzheimer's disease pathology, are generated through the sequential cleavage of amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. The early endosome is thought to represent a major compartment for APP processing; however, the mechanisms of how BACE1 encounters APP are largely unknown. In contrast to APP internalization, which is clathrin-dependent, we demonstrate that BACE1 is sorted to early endosomes via a route controlled by the small GTPase ADP ribosylation factor 6 (ARF6). Altering ARF6 levels or its activity affects endosomal sorting of BACE1, and consequently results in altered APP processing and Aβ production. Furthermore, sorting of newly internalized BACE1 from ARF6-positive towards RAB GTPase 5 (RAB5)-positive early endosomes depends on its carboxyterminal short acidic cluster-dileucine motif. This ARF6-mediated sorting of BACE1 is confined to the somatodendritic compartment of polarized neurons in agreement with Aβ peptides being primarily secreted from here. These results demonstrate a spatial separation between APP and BACE1 during surface-to-endosome transport, suggesting subcellular trafficking as a regulatory mechanism for this proteolytic processing step. It thereby provides a novel avenue to interfere with Aβ production through a selective modulation of the distinct endosomal transport routes used by BACE1 or APP.
Common-path interference and oscillatory Zener tunneling in bilayer graphene p-n junctions
Authors: Nandkishore Rahul , Levitov Leonid
Published: August 2011

Interference and tunneling are two signature quantum effects that are often perceived as the yin and yang of quantum mechanics: a particle simultaneously propagating along several distinct classical paths versus a particle penetrating through a classically inaccessible region via a single least-action path. Here we demonstrate that the Dirac quasiparticles in graphene provide a dramatic departure from this paradigm. We show that Zener tunneling in gapped bilayer graphene, which governs transport through p-n heterojunctions, exhibits common-path interference that takes place under the tunnel barrier. Due to a symmetry peculiar to the gapped bilayer graphene bandstructure, interfering tunneling paths form conjugate pairs, giving rise to high-contrast oscillations in transmission as a function of the gate-tunable bandgap and other control parameters of the junction. The common-path interference is solely due to forward-propagating waves; in contrast to Fabry–Pérot-type interference in resonant-tunneling structures, it does not rely on multiple backscattering. The oscillations manifest themselves in the junction I–V characteristic as N-shaped branches with negative differential conductivity. The negative
dI
/
dV
, which arises solely due to under-barrier interference, can enable new high-speed active-circuit devices with architectures that are not available in electronic semiconductor devices.