bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carrier‐density‐dependent increase and suppression of optical gain in T‐shaped quantum‐wire lasers
Authors: Yoshita Masahiro , Okano Makoto , Ihara Toshiyuki , Akiyama Hidefumi , Huai Ping , Ogawa Tetsuo , Pfeiffer Loren N. , West Ken W. 
Published: June 2008

AbstractCarrier‐density dependence of the optical‐gain spectra were studied for an undoped T‐shaped quantum‐wire (T wire) laser by optical pumping at 4 K. The gain appeared at a low excitation power of 3 mW corresponding to the carrier density of about 3 × 105 cm–1 in the T wire. As the carrier density was increased, the peak gain increased, but it reached a maximum value of about 1 × 104 cm–1 at the carrier density of 1 × 106 cm–1 and then decreased hereafter. This peculiar gain evolution dependent on the carrier density was not explained by a simple free‐electron model, which suggests significant contributions of the enhanced Coulomb interactions to the optical gain in the T‐wire laser. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural, optical, and electrical characterizations of epitaxial lifted‐off InGaAs/InAlAs metamorphic heterostructures bonded on AlN ceramic substrates
Authors: Jeong Y. , Shindo M. , Takita H. , Akabori M. , Suzuki T. 
Published: June 2008

AbstractWe investigated epitaxial lift‐off (ELO) of In0.57Ga0.43As/In0.56Al0.44As metamorphic high electron mobility heterostructures and their van der Waals bonding (VWB) on AlN ceramic substrates. Structural, optical, and electrical characterizations were carried out for samples obtained by ELO and VWB, in comparison with on‐wafer counterparts before ELO. We confirmed a strain release after ELO and VWB from xray diffraction, and observed a consequent photoluminescence energy shift. The ELO samples exhibit very high electron mobilities owing to the high indium contents and successful ELO and VWB processes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Attribute control charts using generalized zero‐inflated Poisson distribution
Authors: Chen Nan , Zhou Shiyu , Chang Tzyy‐Shuh , Huang Howard 
Published: June 2008

AbstractThis paper presents a control charting technique to monitor attribute data based on a generalized zero‐inflated Poisson (GZIP) distribution, which is an extension of ZIP distribution. GZIP distribution is very flexible in modeling complicated behaviors of the data. Both the technique of fitting the GZIP model and the technique of designing control charts to monitor the attribute data based on the estimated GZIP model are developed. Simulation studies and real industrial applications illustrate that the proposed GZIP control chart is very flexible and advantageous over many existing attribute control charts. Copyright © 2008 John Wiley & Sons, Ltd.
Gaussian approximation of exponential type orbitals based on B functions
Authors: Pinchon Didier , Hoggan Philip E. 
Published: May 2008

AbstractThis work gives new, highly accurate optimized gaussian series expansions for the B functions used in molecular quantum mechanics. These functions are generally chosen because of their compact Fourier transform, following Shavitt. The inverse Laplace transform in the square root of the variable is used for Gauss quadrature in this work. Two procedures for obtaining accurate gaussian expansions have been compared for the required extended precision arithmetic. The first is based on Gaussian quadratures and the second on direct optimization. Both use the Maple computer algebra system. Numerical results are tabulated and compared with previous work. Special cases are found to agree before pushing the optimization technique further. The optimal gaussian expansions of B functions obtained in this work are available for reference. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Molecular properties calculations using the q‐integral method
Authors: de Oliveira Heibbe C. B. , Esteves Cristiano S. , Gargano Ricardo , Chaer Do Nascimento Marco A. , Malbouisson Luiz A. C. , Mundim Kleber C. 
Published: May 2008

AbstractThe q‐Integral method, based on the q‐Exponential function, has been recently introduced as an alternative approach to calculate the two‐electron integrals which appear in ab initio atomic and molecular quantum mechanical calculations. The advantage of this procedure is that the CPU time for calculating of two‐electron integrals is substantially reduced when compared with the usual one. The objective of this work is to investigate the accuracy of the q‐Integrals as a function of the internuclear distance for molecular systems. To this purpose we employed the q‐Integrals to construct the potential energy surface (PES) for the H2 molecule and used the PES to determine the rovibrational levels and spectroscopic constants of the molecule, which are properties very sensitive to the form of the PES. The results obtained are in good agreement with the ones obtained through the standard procedure of calculating the two‐electron integrals, implying that the q‐Integral method is accurate enough to be used in any molecular quantum mechanical calculation. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Measuring the 13C content of soil‐respired CO2 using a novel open chamber system
Authors: Midwood Andrew J. , Thornton Barry , Millard Pete 
Published: June 2008

AbstractCarbon dioxide respired by soils comes from both autotrophic and heterotrophic respiration. 13C has proved useful in differentiating between these two sources, but requires the collection and analysis of CO2 efflux from the soil. We have developed a novel, open chamber system which allows for the accurate and precise quantification of the δ13C of soil‐respired CO2. The chamber was tested using online analyses, by configuring a GasBench II and continuous flow isotope ratio mass spectrometer, to measure the δ13C of the chamber air every 120 s. CO2 of known δ13C value was passed through a column of sand and, using the chamber, the CO2 concentration stabilized rapidly, but 60 min was required before the δ13C value was stable and identical to the cylinder gas (−33.3‰). Changing the chamber CO2 concentration between 200 and 900 µmol.mol−1 did not affect the measured δ13C of the efflux. Measuring the δ13C of the CO2 efflux from soil cores in the laboratory gave a spread of ±2‰, attributed to heterogeneity in the soil organic matter and roots. Lateral air movement through dry sand led to a change in the δ13C of the surface efflux of up to 8‰. The chamber was used to measure small transient changes (±2‰) in the δ13C of soil‐respired CO2 from a peaty podzol after gradual heating from 12 to 35°C over 12 h. Finally, soil‐respired CO2 was partitioned in a labelling study and the contribution of autotrophic and heterotrophic respiration to the total efflux determined. Potential applications for the chamber in the study of soil respiration are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
The gas‐phase interactions of TEMPO radicals with Fe+ ions
Authors: Kazazić Snježana P. , Klasinc Leo , Rožman Marko , Srzić Dunja 
Published: June 2008

AbstractThe gas‐phase ligation of the 2,2,6,6‐tetramethylpiperidyl‐1‐oxide (TEMPO) radical (1) and its 4‐hydroxy derivative (2) with Fe+ ions in a 3 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer was investigated. Triple ligation may occur: the first ligation produces a transient species prone to either charge exchange or a stable second ligation; the third ligand adds slowly, with fragmentation. 1 and 2 differ in that 1 binds exclusively at the nitroxyl oxygen while 2 also binds at the OH site after the loss of a H‐radical. Calculations combined with steric considerations support such a mechanism for 2. The site and the mechanism of the important side reaction of 1 that involves OH addition from a water impurity to yield an FeR species remain unexplained. Copyright © 2008 John Wiley & Sons, Ltd.
Environmental flow methodologies to protect fisheries resources in human‐modified large lowland rivers
Authors: Huckstorf Volker , Lewin Wolf‐Christian , Wolter Christian 
Published: May 2008

AbstractThe flow regimes of temperate large lowland rivers are manipulated to provide various services for society. Most water policy decisions are based on economic considerations, with little or no consideration toward fish conservation and fisheries. The prerequisite for a stronger implementation of these interests in water policy decisions is the development of appropriate tools for assessing the adequate flow needed to protect fish diversity and fisheries resources.From the 1970s onwards, environmental flow methodologies (EFMs) have been developed primarily to protect endangered fish species and to maintain fisheries resources in human‐modified rivers. Until now, their application had mainly been restricted to small upland rivers and headwater streams. Here, we investigate the applicability of commonly used EFMs for predicting and quantifying the consequences of flow manipulation on fish and fisheries of regulated large lowland rivers.Among the range of environmental flow methods currently available, habitat simulation methods are promising tools to assess adequate flow and to quantify the consequences of flow manipulation on the temporal and spatial availability of littoral habitats important for fish. However, habitat simulation methods may be effective only with those fish species whose recruitment is influenced by the availability of those habitats. To increase prediction accuracy, habitat simulation methods have to be linked to population dynamic models. More research is needed to improve understanding of the mechanisms controlling the dynamics of populations and assemblages in regulated large lowland rivers. Copyright © 2008 John Wiley & Sons, Ltd.
Quantifying channel planform and physical habitat dynamics on a large braided river using satellite data—the Brahmaputra, India
Authors: Boruah Sanchita , Gilvear David , Hunter Peter , Sharma Nayan 
Published: May 2008

AbstractThis paper presents the results of a trialling of the use of Indian Remote Sensing (IRS) satellite imagery for mapping the geomorphology and physical habitat of the Brahmaputra River in Assam, India. The study was undertaken on a 110 km reach as the river emerges out of the Himalayas; a reach with a complex braid pattern and high levels of channel instability. Image analysis on four sets of IRS data encompassing a period of 13 years (1990–2002) was undertaken to detect basic changes in the extent and pattern of low flow channels, vegetated islands, exposed sand bars and floodplain vegetation. Simple unsupervised classification techniques were applied to the images. The water surface of the low flow braided channel network, however was mapped more accurately using the GROW facility within ENVI 4.1; a technique based upon mapping areas within a given number of standard deviations in terms of pixel values within a training area. Subsequent to this unsupervised classification of the water surface area allowed classification of the water in to three water types based on depth and separation of isolated pools and backwaters from the channels conveying flow. Overall classification accuracies of 82.5% were achieved in relation to mapping physical habitat; varying between 86 and 95% for the four different dates. Analysis of the nature of channel planform and habitat change showed that there has been a 3.7% increase in the active channel area consisting of exposed sediment and water within the river corridor. This substantiated a general awareness of an increase in the width and reduction in depth of the Brahmaputra River over the last few decades. The analysis also depicts the occurrence of a major avulsion and the highly dynamic nature of the braided channel network and sand bars.Overall the study demonstrated that simple classification methods when applied to satellite data, capturing imagery in the visible and near infra‐red, can be used to measure important changes in the geomorphology and physical habitats that make up the fluvial system of the Brahmaputra River. The approach may also be more widely applicable to large river systems comprising a mosaic of water, exposed sediment and spectrally different vegetation communities. Copyright © 2008 John Wiley & Sons, Ltd.
The relationships between benthic macroinvertebrates and biotic and abiotic environmental characteristics downstream of the Yahagi Dam, Central Japan, and the State Change Caused by inflow from a Tributary
Authors: Takao Akira , Kawaguchi Yôichi , Minagawa Tomoko , Kayaba Yuichi , Morimoto Yukihiro 
Published: May 2008

AbstractAnthropogenic modifications have disrupted aquatic ecosystems by modification of the flow regime and transport of sediment. The impacts of dams are believed to be very large, but, despite the abundance of dams in monsoonal Asia, great scientific uncertainty still exists about the effect of dams on macroinvertebrates. Therefore, we studied macroinvertebrate assemblages at three reaches (downstream of a dam, downstream of a confluence and on a tributary) of the Yahagi River, central Japan, to confirm the impact of long‐term impoundment on the relationships between macroinvertebrate assemblages and biotic and abiotic environmental factors and also the role of a major tributary in community shift.Four Surber samples and associated physical measurements (depth, velocity and substrate composition) were taken from four study sites (riffles) at each study reach during the period from 10 to 21 February 2004. Drifting materials (zooplankton, POM and bedload sediment) and periphyton were also sampled. Significant differences were found in the macroinvertebrate fauna of these different reaches. Faunal distributions downstream of the dam were severely altered, with high macroinvertebrate abundance and low taxa richness in contrast to those in the tributary. The two‐way indicator species analysis (TWINSPAN) classification clearly distinguished these samples from the others. Based on nonmetric multidimensional scaling (NMS) ordination and correlation analysis (environmental variables vs. NMS axis score), these differences in community structure reflected changes in substrate composition and quantity and quality of suspended and benthic FPOMs. Our observations suggest that while dam‐derived zooplankton and reduced sediment transport had a great impact on the fauna, the tributary inflow, with a catchment size of less than 20% of that above the dam, acted as a major source of sediment input and facilitated macroinvertebrate community recovery. Copyright © 2008 John Wiley & Sons, Ltd.
Trophic gradients in a large‐river Delta: ecological structure determined by connectivity gradients in the Danube Delta (Romania)
Authors: Coops Hugo , Buijse Laura L. , Buijse Anthonie D. (Tom) , Constantinescu Adrian , Covaliov Silviu , Hanganu Jenica , Ibelings Bas W. , Menting Geert , Navodaru Ion , Oosterberg Willem , Staras Mircea , Török Liliana 
Published: May 2008

AbstractThere are over 300 lakes interconnected by riverbranches and man‐made canals in the Danube Delta (Romania). A multidisciplinary survey of these riverine lakes situated in large wetland complexes was made comprising hydrological modelling, remote sensing and monitoring of water quality, plankton, aquatic vegetation and fish communities. Between‐lake differences in water quality and aquatic vegetation cover were inferred from satellite image. Based on channel and lake dimensions, hydrological characteristics of the lakes in the delta were determined: hydrological distance from a riverbranch, residence time and impact of reed water. Water‐quality and biotic parameters (phyto‐ and zooplankton, submerged plants and fish) were sampled in a comparative survey in June 1997–1999 in subsets of the lakes. In a follow‐up study in 2001–2002, seasonality of aquatic vegetation and fish were recorded.A clear distinction was found in three lake types: (1) inflow lakes at short distance to the river, with a high flushing rate, high load of suspended minerals but low chlorophyll concentrations, high cover of floating and submerged vegetation and dominance of eurytopic fish; (2) large, relatively deep lakes with moderately long residence time, high Potamogeton‐cover that collapses during summer, and dominated by eurytopic fish; (3) smaller, isolated lakes at the longest distance from the river, with long residence time, of which the water quality is strongly influenced by water flows through large floating reedbeds (‘blackwater’), with a high vegetation cover of Ceratophyllum demersum and Nitellopsis obtusa throughout the summer and a limnophilic fish community tolerant for low oxygen conditions.Aquatic vegetation showed a clear seasonality related to the interaction between plant development and light conditions. Seasonal changes in fish distribution within the system merely followed the vegetation trends in different lakes and the conditions in the river channels.Past trends in the trophic gradient are discussed in the context of hydromorphological modifications in the Delta. There is a high potential for restoring natural processes owing to the high connectivity and large scale of the system. Copyright © 2008 John Wiley & Sons, Ltd.
Florida river flow patterns and the Atlantic multidecadal oscillation
Authors: Kelly Martin H. , Gore James A. 
Published: May 2008

AbstractA major step in developing legislatively mandated ecological flows for watercourses in Florida, USA is the selection of an appropriate baseline flow period. Recently climatologists have established a link between multidecadal periods of warming and cooling of the Atlantic Ocean (the Atlantic Multidecadal Oscillation (AMO)) and rainfall patterns across much of North America. During an AMO warm period (pre‐1970), much of North America received less than average rainfall, while during a multidecadal cool period (post‐1970), much of North America experienced above normal rainfall. There are exceptions to this general trend with some areas of North America showing an opposite relationship with the AMO. Peninsular Florida is one of these exceptions. While analysing flows on a number of rivers in south–central Florida, we observed a step rather than a monotonic trend in flows consistent with a switch from a warm multidecadal period to a cool multidecadal period. We examined river flows at all gaging sites throughout Florida and the southeast United States that had flow records of 60 years or more. Three river flow patterns were clearly discerned: a Southern River Flow Pattern (SRP) where flows are seasonally greatest during the summer months (June–September); a Northern River Flow Pattern (NRP) where flows are seasonally greatest in the spring and a Bimodal River Flow Pattern (BRP) with distinct peaks in rainfall and flow both in spring and summer. Those rivers with a BRP occur in a band that stretches diagonally from the northeast corner of Florida (St. Marys River) and runs in a southwest direction to the big bend area of the state near the mouth of the Suwannee River. Rivers to the north of this line exhibit the NRP, while rivers to the south of this line exhibit the SRP. Rivers with the SRP exhibited consistently lower flows during the AMO cool period and consistently higher flows during the AMO warm period. Differences in flow volumes between multidecadal periods averaged 30% in SRP rivers. Rivers with a NRP showed an opposite trend. Most convincingly, rivers with the BRP exhibited both trends, the spring mode responded similarly to the northern rivers while the summer mode followed the southern river trend. These results have important implications not only for the establishment of ecological flows, but also for water supply planning and development, flood control and stream ecology in general, since there are considerable differences in the magnitude of flows that should naturally be expected between multidecadal periods. Relatively large decreases and increases in flow are attributable to rainfall differences between multidecadal periods. Copyright © 2008 John Wiley & Sons, Ltd.
Increased growth and distribution of Ephemerella aurivillii (Ephemeroptera) after hydropower regulation of the Aurland catchment in Western Norway
Authors: Raddum Gunnar G. , Fjellheim Arne , Velle Gaute 
Published: May 2008

AbstractThe Aurland watershed has been regulated for hydropower since the establishment of a series of power plants during the period 1970–1983. This resulted in a strong reduction of the flow in the river Vassbygdelvi, the inlet river to lake Vassbygdvatn. In the downstream river Aurland, the flow has varied, but from 2000 the intention has been to simulate pre‐regulation winter flow as far as possible. The temperature in the river Vassbygdelvi has increased from about 1500 degree‐days per year before regulation to above 2000 degree‐days after regulation. In the river Aurland the thermal regime, expressed as degree‐days per year, was more or less unchanged, but a small reduction in the summer temperature and a corresponding increase during other periods was observed. The mayfly Ephemerella aurivillii (Bengtsson) was not recorded in Vassbygdelvi prior to regulation, but became abundant in the river after. Full‐grown larvae were recorded 1–2 months earlier in the river Vassbygdelvi than in the river Aurland after regulation. E. aurivillii has a 1‐year life cycle with imagos present in June–August. Young larvae occurred from June to early September. It is concluded that larvae of E. aurivillii could not complete their life cycle within 1 year before regulation in the river Vassbygdelvi, due to low temperature. The study demonstrates how temperature can regulate the distribution of a species with a strict 1‐year life cycle. Copyright © 2008 John Wiley & Sons, Ltd.
Hydraulic resistance of some selected vegetation in open channel Flows
Authors: Rhee Dong Sop , Woo Hyoseop , Kwon Bo Ae , Ahn Hong Kyu 
Published: May 2008

AbstractVegetation in rivers has important roles in improving and restoring river environment. Other than it adds high aesthetic value to revetments, that it can be used as a levee protection in environmental friendly way. In open channel hydraulics, vegetation often causes changes in the flow resistance, usually resulting in the increase of flood stage. Both experimental and numerical researches have been conducted on flow resistance of vegetation in open channels, however, the researches were based mostly on the vegetation found in the region where the researches were conducted, and this restricts the generality of the results.In this study, three Korean natural vegetations, Zoysia matrella (Korean zoysia), Pennisetum alopecuroides (L.) Spreng. (Korean native vegetation) and Phragmites communis Trin. (Korean reed) were used in flume tests on the effect of vegetation in the channel on flow resistance. ‘n‐VR’ retardance curves were developed for each grass. All the grasses were tested under unmown conditions. Z. matrella was tested under fully submerged condition and other two were tested under both submerged and un‐submerged conditions.Resistance coefficient, expressed as Manning's n, converged to about 0.027 (total roughness) for Z. matrella as VR increased. Resistance coefficients for other plants were found affected by the states of the plants, that is, whether they were ‘green’ or ‘dormant’. Generally, resistance coefficients are higher when plants are ‘green’ than when they are ‘dormant’. This is because the resistance coefficient is influenced by the leaf elements of vegetation on the river flow in addition to the stem of vegetation. The interaction between the bending part of vegetation and the water surface can also increase the resistance coefficient. In terms of water depth, P. communis Trin were found more affected on the resistance coefficients compared to Z. matrella and P. alopecuroides (L.) Spreng. Copyright © 2008 John Wiley & Sons, Ltd.