bluuebunny/crossref_metadata_2025 huggingface dataset:
Broadband directive sources for acoustic discrete-time simulations
Authors: Escolano José , López José J. , Pueo Basilio
Published: December 2009

This work investigates a generalized implementation of directive sources on discrete-time methods. Results based on previous work for sinusoidal sources have been extended to accomplish real life source requirements, which have a frequency-dependent pattern and show gradual transitions between the different directivities at successive frequencies. One of the main advantages of this method lies in its capacity to be applied to any discrete-time method, since it is based on a proper combination of impulse responses radiated from discrete positions, which, in turn, will produce a particular pressure distribution at far-field. Furthermore, some considerations about mesh-dispersion effects on source modeling are addressed using some examples.
Estimation of vehicle speed using wayside sound pressure onset rate
Authors: Zapfe Jeffrey A. , Wood Eric W. , Newmark Marc S.
Published: December 2009

Transportation-related environmental noise studies, particularly those associated with rail traffic, often require long term measurements near existing rights of way. In addition to the sound produced by passing vehicles, it is also useful to know their speed. Previously, speed measurements have generally required an additional piece of instrumentation, such as a second microphone, video camera, or a radar gun—resulting in added measurement cost and complexity. The present study shows how estimations of vehicle speed can be obtained using a single wayside microphone. The method is based on the rate of pressure rise as the vehicle approaches, specifically the maximum onset rate. This paper shows how the maximum onset rate depends only on the vehicle speed, the microphone distance, and the speed of sound. In order to demonstrate the feasibility of the approach field test data are presented for train passages ranging in speed from 33.5to55.6m∕s, as measured by a microphone located 28.65m from the tracks. Speed estimates derived from the onset rate were generally accurate to within 8% of the independently measured speed of the train.
The intelligibility of pointillistic speech
Authors: Kidd Gerald , Streeter Timothy M. , Ihlefeld Antje , Maddox Ross K. , Mason Christine R.
Published: December 2009

A form of processed speech is described that is highly discriminable in a closed-set identification format. The processing renders speech into a set of sinusoidal pulses played synchronously across frequency. The processing and results from several experiments are described. The number and width of frequency analysis channels and tone-pulse duration were variables. In one condition, various proportions of the tones were randomly removed. The processed speech was remarkably resilient to these manipulations. This type of speech may be useful for examining multitalker listening situations in which a high degree of stimulus control is required.
Modelling the human cochlea
Authors: Mayon Ku Emery
Published: December 2009

One of the salient features of the human cochlea is the incredible dynamic range it possesses—the loudest bearable sound is 10,000,000 times greater than the softest detectable sound; this is in part due to an active process. More than twelve thousand hairlike cells known as outer hair cells are believed to expand and contract in time to amplify cochlear motions. However, the cochlea's response is more than just the sum of its parts: the local properties of outer hair cells can have unexpected consequences for the global behavior of the system. One such consequence is the existence of otoacoustic emissions (OAEs), sounds that (sometimes spontaneously!) propagate out of the cochlea to be detected in the ear canal. In this doctoral thesis, a classical, lumped-element model is used to study the cochlea and to simulate click-evoked and spontaneous OAEs. The original parameter values describing the microscopic structures of the cochlea are re-tuned to match several key features of the cochlear response in humans. The frequency domain model is also recast in a formulation known as state space; this permits the calculation of linear instabilities given random perturbations in the cochlea which are predicted to produce spontaneous OAEs.Full text available at http://eprints.soton.ac.uk/64535/
A methodology for developing high damping materials with application to noise reduction of railway track
Authors: Ahmad Nazirah
Published: December 2009

A methodology is developed that allows a material to be formulated for a particular damping application where temperature-dependence has to be taken into account. This is applied to a tuned absorber system used for damping the vibration of a railway track. This is required to be effective over a temperature range -20 to 40 deg C. The time-temperature superposition principle is used to convert frequency-dependence to temperature-dependence for a notional material with constant loss factor. This is used in the prediction of decay rates and thereby noise reduction. In addition, a weighted noise reduction is studied by using measured rail temperature distributions. Two types of viscoelastic material, butyl and EPDM rubbers with various amount of fillers and plasticisers, are investigated. The properties of both rubbers have been measured over the range of temperatures for frequencies 300-3000 Hz. For butyl, the best combination of filler and plasticiser gives temperature weighted noise reductions up to 5.9 dB(A). The best EPDM compound gives a temperature-weighted noise reduction up to 6.2 dB(A). Comparing these two rubbers, EPDM is more suitable for low temperatures below 10 deg and butyl is more suitable for higher temperatures above 10 deg.
Selection of Mutations To Detect Multidrug-Resistant
Mycobacterium tuberculosis
Strains in Shanghai, China
Authors: Luo Tao , Zhao Ming , Li Xia , Xu Peng , Gui Xiaohong , Pickerill Sam , DeRiemer Kathryn , Mei Jian , Gao Qian
Published: December 2009

Novel tools are urgently needed for the rapid, reliable detection of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of
Mycobacterium tuberculosis
. To develop such tools, we need information about the frequency and distribution of the mycobacterial mutations and genotypes that are associated with phenotypic drug resistance. In a population-based study, we sequenced specific genes of
M. tuberculosis
that were associated with resistance to rifampin and isoniazid in 242 phenotypically MDR isolates and 50 phenotypically pan-susceptible isolates from tuberculosis (TB) cases in Shanghai, China. We estimated the sensitivity and specificity of the mutations, using the results of conventional, culture-based phenotypic drug susceptibility testing as the standard. We detected mutations within the 81-bp core region of
rpoB
in 96.3% of phenotypically MDR isolates. Mutations in two structural genes (
katG
and
inhA
) and two regulatory regions (the promoter of
mabA
-
inhA
and the intergenic region of
oxyR
-
ahpC
) were found in 89.3% of the MDR isolates. In total, 88.0% (213/242 strains) of the phenotypic MDR strains were confirmed by mutations in the sequenced regions. Mutations in
embB306
were also considered a marker for MDR and significantly increased the sensitivity of the approach. Based on our findings, an approach that prospectively screens for mutations in 11 sites of the
M. tuberculosis
genome (
rpoB531
,
rpoB526
,
rpoB516
,
rpoB533
, and
rpoB513
,
katG315
,
inhA
-
15
,
ahpC
-
10
,
ahpC-6
, and
ahpC-12
, and
embB306
) could detect 86.8% of MDR strains in Shanghai. This study lays the foundation for the development of a rapid, reliable molecular genetic test to detect MDR strains of
M. tuberculosis
in China.
Identification of a Plasmid-Borne Resistance Gene Cluster Comprising the Resistance Genes
erm
(T),
dfrK
, and
tet
(L) in a Porcine Methicillin-Resistant
Staphylococcus aureus
ST398 Strain
Authors: Kadlec Kristina , Schwarz Stefan
Published: December 2009

A novel plasmid-borne resistance gene cluster comprising the genes
erm
(T) for macrolide-lincosamide-streptogramin B resistance,
dfrK
for trimethoprim resistance, and
tet
(L) for tetracycline resistance was identified in a porcine methicillin-resistant
Staphylococcus aureus
sequence type 398 (ST398) strain. This
erm
(T)-
dfrK
-
tet
(L) region was flanked by copies of the novel IS element IS
Sau10
. The
erm
(T) region resembled that of
Streptococcus pyogenes
plasmid pRW35. The
erm
(T) gene of pKKS25 was expressed constitutively due to a 57-bp deletion in the
erm
(T) translational attenuator.
Salicylic Acid DiminishesStaphylococcus aureusCapsular Polysaccharide Type 5 Expression
Authors: Alvarez Lucía P. , Barbagelata María S. , Gordiola Mariana , Cheung Ambrose L. , Sordelli Daniel O. , Buzzola Fernanda R.
Published: December 2009

Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are majorStaphylococcus aureusvirulence factors. Previous studies have shown that salicylic acid (SAL), the main aspirin metabolite, affects the expression of certain bacterial virulence factors. In the present study, we found thatS. aureusstrain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells in larger numbers than strain Reynolds organisms not exposed to SAL. Furthermore, the internalization of the isogenic nonencapsulated Reynolds strain into MAC-T cells was not significantly affected by preexposure to SAL. Pretreatment ofS. aureusstrain Newman with SAL also enhanced internalization into MAC-T cells compared with that of untreated control strains. Using strain Newman organisms, we evaluated the activity of the majorcap5promoter, which was significantly decreased upon preexposure to SAL. Diminished transcription ofmgrAand upregulation of thesaeRStranscript, both global regulators of CP expression, were found inS. aureuscultured in the presence of SAL, as ascertained by real-time PCR analysis. In addition, CP5 production byS. aureusNewman was also decreased by treatment with SAL. Collectively, our data demonstrate that exposure of encapsulatedS. aureusstrains to low concentrations of SAL reduced CP production, thus unmasking surface adhesins and leading to an increased capacity of staphylococci to invade epithelial cells. The high capacity of internalization of the encapsulatedS. aureusstrains induced by SAL pretreatment may contribute to the persistence of bacteria in certain hosts.
Expression of BfrH, a Putative Siderophore Receptor of
Bordetella bronchiseptica
, Is Regulated by Iron, Fur1, and the Extracellular Function Sigma Factor EcfI
Authors: Burgos Jonathan M. , King-Lyons Natalie D. , Connell Terry D.
Published: December 2009

Iron (Fe) in soluble elemental form is found in the tissues and fluids of animals at concentrations insufficient for sustaining growth of bacteria. Consequently, to promote colonization and persistence, pathogenic bacteria evolved a myriad of scavenging mechanisms to acquire Fe from the host.
Bordetella bronchiseptica
, the etiologic agent of upper respiratory infections in a wide range of mammalian hosts, expresses a number of proteins for acquisition of Fe. Using proteomic and genomic approaches, three Fe-regulated genes were identified in the bordetellae:
bfrH
, a gene encoding a putative siderophore receptor;
ecfI
, a gene encoding a putative extracellular function (ECF) sigma factor; and
ecfR
, a gene encoding a putative EcfI modulator. All three genes are highly conserved in
B. pertussis
,
B. parapertussis
, and
B. avium
. Genetic analysis revealed that transcription of
bfrH
was coregulated by
ecfI
,
ecfR
, and
fur1
, one of two
fur
homologues carried by
B. bronchiseptica
. Overexpression of
ecfI
decoupled
bfrH
from Fe-dependent regulation. In contrast, expression of
bfrH
was significantly reduced in an
ecfI
deletion mutant. Deletion of
ecfR
, however, was correlated with a significant increase in expression of
bfrH
, due in part to a
cis
-acting nucleotide sequence within
ecfR
which likely reduces the frequency of readthrough transcription of
bfrH
from the Fe-dependent
ecfIR
promoter. Using a murine competition infection model,
bfrH
was shown to be required for optimal virulence of
B. bronchiseptica
. These experiments revealed
ecfIR
-
bfrH
as a locus encoding a new member of the growing family of Fe and ECF sigma factor-modulated regulons in the bordetellae.
Kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions assessed by voltammetry
Authors: Cuculić Vlado , Pižeta Ivanka
Published: December 2009

The kinetics of iron(III) hydrolysis and precipitation in aqueous glycine solutions were studied by cathodic voltammetry with a mercury drop electrode. The kinetics was controlled by changing ionic strength (I), pH and glycine concentration. Voltammetric measurements clearly showed formation and dissociation of a soluble Fe(III)–glycine complex, formation of iron(III) hydroxide and its precipitation. The rate constants of iron(III) hydroxide precipitation were assessed. The precipitation is first-order with respect to dissolved inorganic iron(III). The calculated rate constants of iron(III) precipitation varied from 0.18 × 10–5 s–1 (at 0.2 M total glycine, pH 7.30, I = 0.6 mol dm–3) to 2.22 × 10–3 s–1 (at 0.1 M total glycine, pH 7.30, I = 0.2 mol dm–3). At 0.5 M total glycine and I = 0.6 mol dm–3, the iron(III) precipitation was not observed.
Paleomagnetic and geochemical evidence for a pre-Triassic age for the Lower Amaranth Member of the Williston Basin of Manitoba (Canada)
Authors: Szabó Erika , Cioppa Maria T. , Al-Aasm Ihsan S.
Published: December 2009

Paleomagnetic and geochemical data obtained from six wells in southwestern Manitoba indicate that the Lower Amaranth redbeds were deposited earlier than Jurassic or Triassic, the most commonly cited depositional ages for this formation in the Williston Basin. The magnetization is carried primarily by detrital specular and pigmentary hematite and occasionally magnetite. Inclination-only analysis of paleomagnetic data (83 specimens from 60 plugs) indicates two possible depositional magnetization ages: Devonian–Pennsylvanian (D, found in very few samples) or Carboniferous to Permian, as suggested by the inclination and the polarity of the most predominant magnetization (B). An isolated magnetization (C) could be a mid-Jurassic to Neogene localized fluid flow remagnetization event. The oxygen and carbon isotope values of dolomite (–6.45‰ to 0.30‰ Vienna PeeDee Belemnite (VPDB) δ18O, –1.57‰ to 5.44‰ VPDB δ13C; n = 18) indicate that dolomitization could have occurred anytime between Carboniferous and Jurassic. However, the distribution of these values is a function of the three types of dolomite present in the Lower Amaranth strata: detrital, cement, and matrix replacive and reflects both the primary values and diagenetic overprints. Detrital and cement dolomite show depleted values in both oxygen and carbon isotopes, most likely inherited from the original values of the detrital dolomite, with superimposed effects of recrystallization. The matrix replacive dolomite has no detrital content, and its oxygen isotope values are similar to the expected values for primary or early diagenetic dolomite from Carboniferous to Jurassic times. Mixtures of detrital and replacive matrix dolomite give intermediate oxygen and carbon isotope values.
Factors affecting the growth and condition of lake whitefish (Coregonus clupeaformis)
Authors: Rennie Michael D. , Sprules W. Gary , Johnson Timothy B.
Published: December 2009

Though declines in the growth and condition of Great Lakes lake whitefish ( Coregonus clupeaformis ) have been largely attributed to food web disruptions caused by invasive dreissenid mussels, a comprehensive evaluation of alternative hypotheses is currently lacking. Using various statistical approaches, we evaluated 69 years of data from the inner basin of South Bay, Lake Huron, considering the role of biological variables (food availability as Diporeia abundance and lake whitefish relative abundance as catch per unit effort, CPUE) versus environmental variables (climate change as growing degree days >5 °C and productive habitat capacity as percent epilimnetic volume, EV) on the condition and early growth rates of resident lake whitefish. Consistently, biological variables (Diporeia abundance, CPUE) best explained changes in lake whitefish growth and condition, respectively, in years when Diporeia data were available. In their absence, environmental variables (EV) best explained early growth rates of lake whitefish, whereas CPUE again best explained lake whitefish condition. Our analysis revealed that environmental change contributed significantly but alone was not sufficient to explain declines in lake whitefish growth after dreissenid establishment, whereas biological variables considered here could account for the majority of growth and condition changes observed in this population.
Pelagic fish outburst or suprabenthic habitat occupation: legacy of the Atlantic cod (Gadus morhua) collapse in eastern Canada
Authors: McQuinn Ian H.
Published: December 2009

The use of bottom-trawl research survey data to estimate population trends for small pelagic fishes, despite the extremely low selectivity of this gear for these species, has created the impression of a pelagic fish outburst along eastern Canada in the 1990s as a top-down response resulting from the demise of the Atlantic cod ( Gadus morhua ) and other groundfish. Using Atlantic herring ( Clupea harengus ) population assessments, fisheries statistics, and an acoustic database, as well as grey seal (Halichoerus grypus) diet studies, I demonstrate that contrary to a pelagic outburst, pelagic catches in research bottom trawls increased in several eastern Canadian ecosystems as these species increasingly occupied the suprabenthic habitat vacated by their diminishing groundfish predators. Although several herring populations were actually decreasing in abundance, bottom-trawl indices (BTIs) were dramatically increasing as their availability to research bottom-trawl surveys increased. Studies using BTIs have systematically underestimated pelagic fish abundances before the cod decline and therefore have dramatically overestimated their importance since, seriously biasing our view of the past and present state of many Canadian east coast ecosystems.
Evaluation of performance of alternative management models of Pacific salmon (Oncorhynchus spp.) in the presence of climatic change and outcome uncertainty using Monte Carlo simulations
Authors: Dorner Brigitte , Peterman Randall M. , Su Zhenming
Published: December 2009

An important management challenge is to maintain productive populations of Pacific salmon ( Oncorhynchus spp.), despite highly variable environments and our weak understanding of future climatic conditions and mechanisms that link them to salmon. This understanding could be improved by including environmental covariates in salmon population models and applying advanced “meta-analyses” to large data sets to better estimate underlying functional relationships. However, the performance of such models needs to be determined in the context of an overall system. We therefore simulated a 15-population salmon fishery system and compared the performance (in terms of catch and an index of conservation concern) of 10 forecasting and stock assessment models, ranging from simple to complex, by stochastically simulating components of a salmon fishery using a “closed-loop simulation” (or “management strategy evaluation”) under a variety of plausible future climatic scenarios. We found that complex models perform better in some situations. However, their incremental benefits are small and are swamped by the large variability in outcomes of management actions caused by “outcome uncertainty”, which reflects noncompliance of fishing vessels with regulations as well as variation in catchability. Reduction of this outcome uncertainty should therefore be a top priority, as should evaluations of more complex stock assessment models before adopting them.
Long-term food web change in Lake Superior
Authors: Schmidt Stephanie N. , Vander Zanden M. Jake , Kitchell James F.
Published: December 2009

Restoration and rehabilitation of native species in the Laurentian Great Lakes is a priority for fisheries management agencies. Restoration efforts are increasingly incorporating a perspective that considers species within a broader food web context. We used stable isotope analysis and museum-preserved specimens to describe and quantify 100 years of food web changes in the Lake Superior fish community. We validated stable isotope analysis of museum specimens by showing a positive correlation between isotope- and diet-based estimates of trophic position. While introductions have created a more trophically diverse food web than historically found in Lake Superior, two separate metrics revealed little community-wide change in the food web. Our species-specific analysis revealed trophic niche differences between shortjaw ( Coregonus zenithicus ) and shortnose ( Coregonus reighardi ) ciscoes, two species previously argued to be indistinguishable based on morphological characteristics. By providing a historical context, our findings show the ability of the Lake Superior food web to accommodate non-native species introductions over the last century while still supporting native species populations. This long-term information about food web structure can help guide management and restoration goals in Lake Superior. Furthermore, Lake Superior can serve as a basis for comparing food web changes in other, more highly altered Great Lakes.
Coastal largemouth bass (Micropterus salmoides) movement in response to changing salinity
Authors: Lowe Michael R. , DeVries Dennis R. , Wright Russell A. , Ludsin Stuart A. , Fryer Brian J.
Published: December 2009

Estuaries are productive, heterogeneous, and dynamic systems that support a diverse array of fishes. However, our understanding of how presumably stenohaline fishes persist in such transitional systems is limited, particularly for most fishes in tidal freshwater areas. We conducted a laboratory experiment and field investigation along an upstream–downstream salinity gradient in the Mobile–Tensaw River Delta, Alabama, USA, to test the hypothesis that age-0 largemouth bass ( Micropterus salmoides ), an economically and ecologically important freshwater species that uses low-salinity habitats in many North American estuaries, move to avoid seasonal salinity increases. To do so, we quantified changes in otolith microchemistry (e.g., Sr to Ca ratios) along the major growth axis of otoliths in both field-collected and laboratory-reared individuals. Our experiment revealed a 21-day lag time between initial salinity changes and Sr:Caotolith saturation but that Sr:Caotolith in field-collected fish reflect changes in ambient salinity. Further, contrary to our expectation, otolith microchemical analyses from spring- and fall-collected age-0 largemouth bass indicate no avoidance of increased salinity, which has potential implications for their growth and recruitment in these systems.
Phylogeography and postglacial dispersal of smallmouth bass (Micropterus dolomieu) into the Great Lakes
Authors: Borden W. Calvin , Krebs Robert A.
Published: December 2009

Refugia and dispersal routes of smallmouth bass ( Micropterus dolomieu ) into the Great Lakes were identified using 427 mitochondrial sequences from across their native range. Overall, smallmouth bass accessed the Great Lakes via long-distance dispersal from multiple refugia, and the distribution of genetic variation reflected the consequences of vicariant, dispersal, and paleogeological events. Proximity of lakes to glacial outlets had a greater predictive power on the resulting distribution of mitochondrial diversity relative to interbasin migration. Populations in the Eastern and Interior Highlands contained the most divergent and oldest haplotypes, reflecting their role as glacial refugia and subsequent high incidence of endemicity. Lake Superior, Lake Michigan, and northern Lake Huron were colonized by bass of a single mitochondrial clade that accessed the Brule–Portage (Mississippi and St. Croix rivers) and Chicago (Illinois and Fox rivers) outlets. Lakes Huron and Erie contained admixed mitochondrial lineages in part due to numerous access points, including the Fort Wayne (Wabash and Maumee rivers), Lower Peninsula of Michigan (Grand River valley), and Kirkfield (Kawartha Lakes) outlets. In contrast, populations in Lake Ontario, Georgian Bay of Lake Huron, and the St. Lawrence River were monomorphic, indicating a single but unidentified source. These patterns were consistent with many examples from the North American freshwater ichthyofauna.
Scattering of a Klein–Gordon particle by a Hulthén potential
Authors: Guo Jian-You , Fang Xiang-Zheng
Published: December 2009

The Klein–Gordon equation in the presence of a spatially one-dimensional Hulthén potential is solved exactly and the scattering solutions are obtained in terms of hypergeometric functions. The transmission coefficient is derived by the matching conditions on the wave functions and the conditions for the existence of transmission resonances are investigated. It is shown how the zero-reflection condition depends on the shape of the potential.
On the uniqueness of unitary representations of the non-commutative Heisenberg–Weyl algebra
Authors: Gouba L. , Scholtz F. G.
Published: December 2009

In this paper, we discuss the uniqueness of the unitary representations of the noncommutative Heisenberg–Weyl algebra. We show that, apart from a critical line for the noncommutative position and momentum parameters, the Stone–von Neumann theorem still holds, which implies uniqueness of the unitary representation of the Heisenberg–Weyl algebra.
Mach–Zehnder fiber interferometer test of the anisotropy of the speed of light
Authors: de Haan Victor
Published: December 2009

Two optical fiber Mach–Zehnder interferometers were constructed in an environment with a temperature stabilization of better than 1 mK per day. One interferometer consisted of a length of 12 m optical fiber in each arm, with the main direction of the arms perpendicular to each other while the other consisted of a length of 2 m optical fiber in each arm, where the main direction of the arms are parallel, and served as a control. In each arm, 1 m of fiber was wound around a ring made of piezo material, enabling the control of the length of the arms by means of an applied voltage. The influence of the temperature on the optical phase difference between the interferometer arms was measured. The temperature change induced a variation of the interaction region of the optical fiber couplers. Further, the influence of rotation of the interferometers at the Earth surface on the observed phase differences was determined. For one interferometer (with the long and perpendicular arms), it was found that the phase difference depends on the azimuth of the interferometer. For the other one (with the short and parallel arms), no relevant dependence on the azimuth has been measured.
Numerical solution of peristaltic transport of an Oldroyd 8-constant fluid in a circular cylindrical tube
Authors: Ali N. , Wang Y. , Hayat T. , Oberlack M.
Published: December 2009

The present paper is concerned with the peristaltic flow of a non-Newtonian fluid in circular cylindrical tube. Long wavelength and low Reynolds number approximations are adopted in the problem definition. The non-Newtonian behaviour of the fluid is characterized by the constitutive equation of an Oldroyd 8-constant fluid. The governing nonlinear equation and boundary conditions are solved numerically by a suitable finite-difference method with an iterative scheme. It is seen that shear-thinning and shear-thickening phenomena can be explained through the chosen fluid model. The interaction of shear-thinning and shear-thickening effects with peristaltic motion is studied in detail with particular focus on the basic features of peristalsis such as flow characteristics, pumping characteristics, and trapping. It is found that pressure rise per wavelength against which peristalsis has to work as a positive displacement pump decreases in going from shear-thickening to shear-thinning fluids. Moreover, for strong shear-thinning fluids trapping does not appear. However, a trapped bolus occurs for a weak shear-thinning fluid and its size increases as the fluid is changing from shear thinning towards weak shear thickening. For strong shear-thickening fluids such increase in the size and circulation of bolus stops.
Physical and hydraulic characterization of fractured, hydrophobic sulphur within above-ground sulphur blocks
Authors: Bonstrom Kristie , Barbour S. Lee , Hendry M. Jim
Published: December 2009

Volatility in the price of sulphur has resulted in the temporary storage of sulphur in large, surface blocks at oil sands properties in northern Alberta, Canada, that are subject to oxidation which produces acidic effluent. Characterization of water storage and migration within these blocks is required to assess potential environmental impacts. Investigation of the elemental sulphur (S0) blocks at Syncrude’s Mildred Lake site included fracture mapping and laboratory testing of core samples for density and permeability to air and water. Internal porosity was mapped with X-ray tomography, and water-intrusion porosimetry was used to define saturation–pressure relationships. The blocks have regular polygonal fractures with a porosity of approximately 1.4%. The mean total and water-available porosity of core samples was 9% and 6%, respectively. The water-entry pressure head was 1–2 m for matrix pores, but only 1–2 mm for fractures. Estimated functional relationships for volumetric water content versus water pressure of the fracture and matrix system are used to illustrate how infiltration is likely to occur rapidly along fracture pathways but with insufficient pressure to allow water to penetrate the matrix, suggesting that acid production occurs by flushing of the fracture surface with little influence from the matrix.
The stock recovery rate in a Central African rain forest: an index of sustainability based on projection matrix models
Authors: Picard Nicolas , Banak Ludovic Ngok , Namkosserena Salomon , Yalibanda Yves
Published: December 2009

The stock recovery rate is used in most natural forests of the Congo Basin to assess logging sustainability. This rate is computed using the so-called Dimako formula. Although this formula has been used for many years now in management plans, its mathematical properties have not been closely reviewed. We show that the Dimako formula corresponds to a Leslie matrix model, and then we propose an extension of it as a Usher matrix model. The stock recovery rate at the end of the first felling cycle for six commercial species in the Central African Republic varied between 21.7% and 99.9%. As felling cycles follow each other, the stock recovery rate converged towards a limit that is the asymptotic stock recovery rate. This limit varies between 27.2% and 158.4% for the same six species. Comparing felling scenarios reveals that increasing the minimum harvest diameter was as efficient at increasing the stock recovery rate at the end of the first felling cycle as decreasing the logging intensity. The results for the other parameters of the felling scenarios varied among species, with changes in the stock recovery rate ranging from 0% to 180% at the end of the first felling cycle, and changes in the asymptotic rate ranging from 0% to 685%.
Ecology and management of the lobster mushroom in an eastern Canadian jack pine stand
Authors: Rochon Caroline , Paré David , Khasa Damase P. , Fortin J. André
Published: December 2009

The lobster mushroom, an organism resulting from the infection of Russula spp. by Hypomyces lactifluorum (Schwein.) Tul. & C. Tul., is common to Canadian boreal forests and has good commercial potential. Within a Pinus banksiana Lamb. stand managed for mushroom production, this study aimed to (1) document carpophore productivity (density, biomass per area) during three seasons, (2) compare productivity among three forest conditions (trails, forest strips between trails, and unmanaged forest), (3) establish ecological parameters related to productivity, and (4) define microhabitats where carpophores are present by using soil and vegetation descriptors. Mushroom density tended to be higher on the trails than under the canopy, but fresh biomass was higher in forest strips except in 2006 when midsummer precipitation was low. Trail management did not increase mushroom production but maintained it during periods of reduced precipitation. Productivity was positively related to the abundance of shade-intolerant plant species and to extractable ammonium, and negatively related to soil pH. Within the present study conditions, microhabitats suitable for the presence of carpophores had low pH, high available phosphorus, low Kalmia angustifolia L. cover, and small canopy gaps with shade-intolerant species. This study was the first step toward understanding the ecology and impacts of forest practices on the lobster mushroom.
A multilevel individual tree basal area increment model for aspen in boreal mixedwood stands
Authors: Yang Yuqing , Huang Shongming , Meng Shawn X. , Trincado Guillermo , VanderSchaaf Curtis L.
Published: December 2009

Based on a multilevel nonlinear mixed model approach, a basal area increment model was developed for individual aspen ( Populus tremuloides Michx.) trees growing in boreal mixedwood stands in Alberta. Various stand and tree characteristics were evaluated for their contributions to model improvement. Total stand basal area, basal area of larger trees, and the ratio of target tree height to maximum stand height were found to be significant predictors. When random effects were modeled at the plot level alone, correlations among normalized residuals remained significant. These correlations were successfully removed when random effects were modeled at both plot and tree levels. The predictive abilities of two alternative models were evaluated at the population, plot, and tree levels. At the tree level, a tree measured at the first growth period was used for estimating random parameters, and basal area increments of that tree in future growth periods were subsequently predicted. At the plot level, one to five trees in each plot at each growth period were used to estimate random parameters. Basal area increments of the remaining trees in the same plot at the same growth period were subsequently predicted. The final model provided accurate predictions at all three levels.
Air pollution, climate, soil acidity, and indicators of forest health in Ontario’s sugar maple forests
Authors: Miller Diane E. , Watmough Shaun A.
Published: December 2009

Ontario’s hardwood forests are currently subjected to high levels of air pollution, but critical levels at which point adverse effects may occur are poorly known. In this study, we sampled 35 hardwood plots dominated by sugar maple ( Acer saccharum Marsh.) located along a contrasting climate, soil acidity, and air pollution gradient in southern Ontario to explore relationships between these potential ecosystem stressors and ecosystem responses. Foliar sulfur (S) and nitrogen (N) contents were positively correlated with modeled deposition, and foliose lichen species richness was negatively correlated with modeled air pollution levels (S deposition, N deposition, and atmospheric ozone AOT40), whereas foliar calcium, magnesium, and manganese contents were correlated with A-horizon soil acidity. Forest floor S and N contents and C/N ratios were related to soil pH, with high S and N contents and low C/N ratios occurring on the more acidic soil in the northern part of the region, which receives the lowest modeled loadings of S and N deposition and experience colder and wetter climate. Forest health as determined by canopy condition was not related to indices of air pollution, climate, or soil acidity, and no relationship was found among air pollution, soil acidity, and ground vegetation species richness or diversity.
Soil processes and microbial community structures in 45- and 135-year-old lodgepole pine stands
Authors: Chatterjee A. , Ingram L.J. , Vance G.F. , Stahl P.D.
Published: December 2009

As forests develop, changes in soil organic matter quantity and quality affect both nutrient dynamics and microbial community structure. Litter decomposition and nitrogen mineralization in association with soil microbial communities were compared between 45- and 135-year-old lodgepole pine ( Pinus contorta var. latifolia (Englem.)) stands in southeastern Wyoming, USA. Compared with the 45-year-old stand, the 135-year-old stand was found to have greater live-tree biomass, litter decomposition rates (264 versus 135 mg·(g litter)–1·year–1), soil nitrification rates (0.38 versus 0.19 µg NO3–·(g soil)–1 after 265 days of field incubation), and total phospholipid fatty acid (PLFA) concentrations (25 versus 9.2 nmol·(g soil)–1 at 0–5 cm depth). Canonical correspondence analysis indicated that variation of PLFA profiles within the 45-year-old stand was explained by soil pH and bulk density, whereas soil process rates explained the distributions of PLFA profiles within the 135-year-old stand. The results of these studies indicate that stand age influences live-tree biomass and soil properties that can lead to changes in litter decomposition rates and soil microbial communities in lodgepole pine forests.
Decomposition of Nothofagus wood in vitro and nutrient mobilization by fungi
Authors: Clinton Peter W. , Buchanan P. K. , Wilkie J. P. , Smaill S. J. , Kimberley M. O.
Published: December 2009

The role of fungi in determining rates of wood decomposition and nutrient release in forest ecosystems is poorly understood. The decomposition of wood from three species of Nothofagus by 12 species of widely occurring New Zealand wood-decay fungi was investigated in vitro under standardized conditions. Wood mass loss varied strongly among fungal species and to a lesser extent with the species of wood. The species of fungi in this study were divided into three groups based on the extent of mass loss after 15 weeks: (1) rapid (>65% reduction in mass, Fomes hemitephrus , Pleurotus purpureoolivaceus , Trametes versicolor , and Ganoderma cf. applanatum), (2) intermediate (15%–30%, Phellinus sp., Schizopora radula , Phellinus nothofagi , and Skeletocutis stramenticus ), and (3) slow (<10%, Armillaria novaezelandiae , Postia pelliculosa , Australoporus tasmanicus , and Laetiporus portentosus ). For several fungal species, the final contents of nitrogen, phosphorus, and calcium in the remaining wood exceeded the initial nutrient contents in the wood, indicating that nutrient sequestration from the supporting soil matrix occurred during decomposition. Nutrient dynamics during decomposition varied with wood species, but the variation among different fungal species was much greater, indicating that fungal diversity is an important factor in determining nutrient flux in decaying wood.
A meta-regression analysis of forest carbon offset costs
Authors: van Kooten G. Cornelis , Laaksonen-Craig Susanna , Wang Yichuan
Published: December 2009

The main focus of efforts to mitigate climate change is on the avoidance of fossil fuel emissions. However, the Kyoto Protocol rules permit the use of forestry activities that create carbon offset credits. These could obviate the need for lifestyle-changing reductions in fossil fuel use. Therefore, it is necessary for policy purpose to determine the cost effectiveness of creating forest sink carbon credits. In this study, meta-regression analyses with 1047 observations from 68 studies are used to determine factors that affect carbon sequestration costs. Results indicate that forest plantations and use of harvested biomass for energy make forestry activities more attractive. It also turns out that forestry activities are competitive with emissions reduction in tropical regions and, perhaps, boreal regions but certainly not in Europe. Finally, the regression estimates are used to project the potential costs of carbon uptake for various forest management scenarios — costs range from 0 to over 200 US$/t CO2.
AN MPI PERFORMANCE MONITORING INTERFACE FOR CELL BASED COMPUTE NODES
Authors: DURSUN HIKMET , BARKER KEVIN J. , KERBYSON DARREN J. , PAKIN SCOTT , SEYMOUR RICHARD , KALIA RAJIV K. , NAKANO AIICHIRO , VASHISHTA PRIYA
Published: December 2009

In this paper, we present a methodology for profiling parallel applications executing on the family of architectures commonly referred as the "Cell" processor. Specifically, we examine Cell-centric MPI programs on hybrid clusters containing multiple Opteron and IBM PowerXCell 8i processors per node such as those used in the petascale Roadrunner system. We analyze the performance of our approach on a PlayStation3 console based on Cell Broadband Engine—the CBE—as well as an IBM BladeCenter QS22 based on PowerXCell 8i. Our implementation incurs less than 0.5% overhead and 0.3 µs per profiler call for a typical molecular dynamics code on the Cell BE while efficiently utilizing the limited local store of the Cell's SPE cores. Our worst-case overhead analysis on the PowerXCell 8i costs 3.2 µs per profiler call while using only two 5 KiB buffers. We demonstrate the use of our profiler on a cluster of hybrid nodes running a suite of scientific applications. Our analyses of inter-SPE communication (across the entire cluster) and function call patterns provide valuable information that can be used to optimize application performance.
ANATOLY VASILIEVICH EFREMOV – KNOWN AND UNKNOWN
Authors: SHIRKOV DMITRY V.
Published: December 2009

Short illustrated description of the Professor A.V. Efremov story in life and science on the occasion of his 75th birthday.
ON PERTURBATIVE QCD OF HARD AND SOFT PROCESSES
Authors: EFREMOV A. V. , RADYUSHKIN A. V.
Published: December 2009

We discuss some problems concerning the application of perturbative QCD to high energy processes. In particular for hard processes, we analyze higher order and higher twist corrections. It is argued that these effects are of great importance for understanding the behaviour of pion electromagnetic form factor at moderately large momentum transfers. For soft processes, we show that summing the contributions of the lowest twist operators leads to a Regge-like amplitude.
LESSONS FROM ALL LOGS SUMMATION IN YUKAWA THEORIES
Authors: GINZBURG I. F.
Published: December 2009

Some features of old results in the total summation of all logarithmic contributions of all diagrams in Yukawa theory are presented. We discuss some lessons from this picture for the description of Pomeron, odderon, etc. in QCD.
NUCLEON SPIN AND ORBITAL STRUCTURE: 20 YEARS LATER
Authors: TERYAEV O. V.
Published: December 2009

The personal view on some recent aspects of average spin and orbital momenta of partons in nucleon is discussed and compared with the previous understanding. The special attention is payed to the strangeness polarization mediated by gluon anomaly and treatment of the strange quarks in a heavy ones in a multiscale nucleon. The crucial role in the orbital structure of nucleon is played by relocalization (Belinfante) invariance and Equivalence Principle (EP). The new manifestation of EP for spin 1 particles is suggested and discussed.
SURPRISING SYMMETRY OF SCATTERING AMPLITUDES IN GAUGE THEORIES
Authors: KORCHEMSKY G. P.
Published: December 2009

I will review a recent progress in computing scattering amplitudes in strongly coupled gauge theories — a fascinating subject which has been recently boosted by the formulation of the gauge/string duality in maximally supersymmetric Yang–Mills theory. In addition to the conventional symmetry of the underlying Lagrangian, the scattering amplitudes in this theory exhibit a new, dual superconformal symmetry. This symmetry is powerful enough to completely determine the scattering amplitudes for arbitrary coupling in a suitably defined limit.
PROBING THE PARTON CONTENT OF THE NUCLEON
Authors: BOFFI SIGFRIDO , PASQUINI BARBARA
Published: December 2009

The parton content of the nucleon is explored within a meson-cloud model developed to derive light-cone wave functions for the physical nucleon. The model is here applied to study electromagnetic form factors, distribution amplitudes and nucleon-to-meson transition distribution amplitudes.
SPIN EFFECTS IN HARD EXCLUSIVE ELECTROPRODUCTION OF MESONS
Authors: KROLL P.
Published: December 2009

In this talk various spin effects in hard exclusive electroproduction of mesons are briefly reviewed. The data are discussed in the light of recent theoretical calculations within the frame work of the handbag approach. This talk has been presented at the Conference in Honor of Prof. Anatoly Efremov's 75th Birthday held at Trento, July, 2009.
EVOLUTION OF UNDERSTANDING POLARIZED DIS: FROM LARGE TO SMALL x
Authors: ERMOLAEV B. I. , GRECO M. , TROYAN S. I.
Published: December 2009

The standard theoretical description of Polarized DIS is based on the use of the DGLAP evolution equations. This approach controls the Q2 -evolution of the DIS structure functions but cannot describe the x -evolution and therefore should not be used at small x. We complement this approach, accounting for the x-evolution of the spin structure function g1 in the leading logarithmic approximation.
INSIGHTS ON NON-PERTURBATIVE ASPECTS OF TMDs FROM MODELS
Authors: AVAKIAN H. , EFREMOV A. V. , SCHWEITZER P. , TERYAEV O. V. , YUAN F. , ZAVADA P.
Published: December 2009

Transverse momentum dependent parton distribution functions are a key ingredient in the description of spin and azimuthal asymmetries in deep-inelastic scattering processes. Recent results from non-perturbative calculations in effective approaches are reviewed, with focus on relations among different parton distribution functions in QCD and models.
SCALE EVOLUTION OF UNINTEGRATED DISTRIBUTIONS AND THE Pt-SPECTRUM OF GAUGE BOSONS
Authors: CECCOPIERI FEDERICO ALBERTO
Published: December 2009

We present predictions for the Z-boson pt-spectrum at Tevatron within the framework of unintegrated distributions evolved according to evolution equations recently proposed by us. We discuss the dependence of the results on the choice of non-perturbative parameters, the coupling constant and the impact of soft gluon resummation.
HADRON STRUCTURE STUDY IN FORTHCOMING DRELL–YAN EXPERIMENTS: COMPASS PROJECT AT CERN
Authors:   on behalf of COMPASS Collaboration, DENISOV OLEG
Published: December 2009

The study of Drell–Yan (DY) processes involving the collision of an (un)polarised hadron beam on an (un)polarised proton target can result in a fundamental improvement of our knowledge on the transverse momentum dependent (TMDs) parton distribution functions (PDFs) of hadrons. The production mechanism of J/ψ and J/ψ - DY duality can also be addressed. One of the forthcoming polarised DY experiments (COMPASS (SPS, CERN)) is discussed in this context. The most important features of this project are briefly reviewed, as well as its sensitivity to the various transverse momentum dependent spin asymmetries.
RESTRICTED CLASS OF COLLIDING EINSTEIN–YANG–MILLS PLANE WAVES
Authors: GURTUG OZAY , HALILSOY MUSTAFA
Published: December 2009

By gauging an Abelian electromagnetic solution through a non-Abelian transformation and in accordance with a theorem proved long time ago, we construct a simple class of colliding Einstein–Yang–Mills plane waves. The solution is isometric to the Wu–Yang charged Kerr–Newman black hole and shares much of the properties satisfied by colliding Einstein–Maxwell plane waves. In the linear polarization limit with unit degenerate charge it reduces to the Bell–Szekeres solution for colliding em shock waves.
WAKIMOTO REALIZATION OF THE ELLIPTIC QUANTUM GROUP $U_{q,p}(\widehat{{\rm sl}_N})$
Authors: KOJIMA TAKEO
Published: December 2009

We construct a free field realization of the elliptic quantum algebra [Formula: see text] for arbitrary level k ≠ 0, -N. We study Drinfeld current and the screening current associated with [Formula: see text] for arbitrary level k. In the limit p → 0 this realization becomes q-Wakimoto realization for [Formula: see text].