bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion rotating motion in a gas‐filled radio‐frequency quadrupole ion guide as a new technique for structural and kinetic investigations of ions
Authors: Raznikov Valeri V. , Soulimenkov Ilia V. , Kozlovski Viatcheslav I. , Pikhtelev Alexander R. , Raznikova Marina O. , Horwath Thomas , Kholomeev Alexander A. , Zhou Zhen , Wollnik Herman , Dodonov Alexander F.
Published: January 2005

An ion rotating excitation mode of operation of a segmented gas‐filled radio‐frequency quadrupole (RFQ) ion guide for a high‐resolution orthogonal time‐of‐flight (TOF) mass spectrometer is described. It is shown theoretically, by computer simulation and experimentally, that ion rotating excitation in a gas‐filled RFQ has several advantages over other types of ion oscillation excitation. The main advantages are an approximately twofold increase in average ion kinetic energy for the same maximal deviation from the RFQ axis and therefore an increase of about this factor of average internal excitation energy of ions, and the extended mass range of fragment ions that can be observed. The new method of ion decomposition by ion rotation around the axis of an RFQ ion guide was experimentally implemented and tested using a home‐built ‘SIN‐COS’ generator to supply the excitation voltage. This generator enables control of phase shift and amplitude of excitation voltages applied to quadrupole rods smoothly from the data acquisition program running on a PC. Copyright © 2001 John Wiley & Sons, Ltd.
Studies of the ortho effect in fragmentations of acetyl ion adducts of disubstituted benzenes
Authors: Li Zhili , Song Fengrui , Liu Shuying
Published: January 2005

The ion‐molecule reactions of disubstituted benzenes under chemical ionization conditions with acetyl chloride as reagent gas were examined, and the fragmentation reactions of the adduct ions (mostly proton and acetyl ion adducts) were studied by collision‐induced dissociation. Electron‐releasing substituents favored the adduct reactions, and electron‐withdrawing groups did not. The position and properties of substituting groups had an effect on the relative abundances of the adduct ions. Several examples of the ortho effect were observed. The fragmentation reaction of the adduct ions formed by ortho‐benzenediamine with the acetyl ion was similar to the reductive alkylation reaction of amines in the condensed phase. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of small organics on planar silica surfaces using surface‐assisted laser desorption/ionization mass spectrometry
Authors: Chen Yu‐Chie , Wu Jia‐Yi
Published: January 2005

This study demonstrates the feasibility of directly obtaining analyte signals from a planar silica gel surface by using laser desorption mass spectrometry (LDMS). The surface of the planar silica gel was pretreated using a line drawn by a soft carbon pencil, and 0.3 µL of a liquid matrix (15% sucrose/glycerol‐methanol 1:1, v/v) was applied to it (width ∼1mm) before sample deposition. The laser was then used to directly irradiate the sample spot on the pencil line (∼2 mm). Carbon powder ablated from the pencil residue is used to couple the laser UV energy into a liquid solution in LDMS. This sample preparation method is related to surface‐assisted laser desorption/ionization (SALDI) mass spectrometry, which uses a suspension of µm‐sized carbon powder (SALDI solid) mixed with a viscous liquid (SALDI matrix) as the matrix. In the present approach, the ablated carbon powder from the pencil drawing on a planar silica gel surface was used as an alternative to the SALDI solid. The liquid matrix was that used in conventional SALDI matrix systems, and the sample preparation applied herein is simpler than conventional SALDI. The matrix background remains quite low in this approach, which significantly assists the analysis of small organics such as methylephedrine and cytosine. PEG (polyethylene glycol) 400 and PEG 2000 were also used for demonstration purposes. Copyright © 2001 John Wiley & Sons, Ltd.
Ion chemistry of chloroethanes in air at atmospheric pressure
Authors: Nicoletti Anna , Paradisi Cristina , Scorrano Gianfranco
Published: January 2005

Ion chemistry at atmospheric pressure is of major relevance to novel methods for the abatement of volatile organic compounds (VOCs) that employ non‐thermal plasmas. For this reason, positive and negative APCI (atmospheric pressure chemical ionization) mass spectra of all six di‐, tri‐ and tetrachloroethanes diluted in air (500–1500 ppm) at atmospheric pressure were investigated at 30 °C and at 300 °C. Spectral changes due to collisional activation of the ions achieved by increasing ΔV, the potential difference between sampling and skimmer cones, are informative of structures and ion‐molecule reactions. Positive ion chemistry of the chloroethanes (M) can, in general, be ascribed to C‐C and C‐Cl cleavages of the molecular ion, M+·, never detected but likely formed via exothermic charge exchange from primary ions of the APCI plasma. Exceptions to this characteristic pattern were observed for 1,1‐dichloroethane and 1,1,2,2‐tetrachloroethane, which give [M − H]+ and [M − HCl]+· species, respectively. It is suggested that both such species are due to ionization via hydride transfer. Upon increasing ΔV, the [M − HCl]+· ion formed from 1,1,2,2‐tetrachloroethane undergoes the same fragmentation and ion‐molecule reactions previously reported for trichloroethene. A nucleophilic reaction of water within the [C2H4Cl+](H2O)n ionic complexes to displace HCl is postulated to account for the [C2H5O+](H2O)m species observed in the positive APCI spectra of the dichloroethanes. Negative ion spectra are, for all investigated chloroethanes, dominated by Cl− and its ion‐neutral complexes with one, two and, in some cases, three molecules of the neutral precursor and/or water. Another common feature is the formation of species (X−)(M)n where X− is a background ion of the APCI plasma, namely O2−,O3− and, in some cases, (NO)2−. Peculiar to 1,1,1‐trichloroethane are species attributed to Cl− complexes with phosgene, (Cl−)(Cl2C=O)n(n = 1,2). Such complexes, which were not observed for either the isomeric 1,1,2‐trichloroethane or for the tetrachloroethanes, are of interest as oxidation intermediates in the corona‐induced decomposition process. No conclusions can be drawn in the case of the dichloroethanes, since, for these compounds, the ions (Cl−)(Cl2C=O)n and (Cl−)(M)n happen to be isobaric. Copyright © 2001 John Wiley & Sons, Ltd.
Negative ion fragmentations of deprotonated peptides: backbone cleavages directed through both Asp and Glu
Authors: Brinkworth Craig S. , Dua Suresh , McAnoy Andrew M. , Bowie John H.
Published: January 2005

The collision‐induced spectra of [M − H]− ions of a variety of natural and synthetic amphibian peptides containing Asp and/or Glu exhibit characteristic γ backbone cleavage ions that identify the positions of these residues in the peptide. A theoretical study suggests that the Glu cleavage involves an SNi reaction of the carboxylate anion from the Glu α side chain to form a deprotonated cyclic lactone. The presence of either Asp or Glu or other residues that effect pronounced side‐chain cleavages (e.g. Ser or Thr) results in the normal α and β backbone cleavages being reduced in comparison to those cleavages which originate from side chains. Copyright © 2001 John Wiley & Sons, Ltd.
Optimal pressure conditions for unbiased external ion accumulation in a two‐dimensional radio‐frequency quadrupole for Fourier transform ion cyclotron resonance mass spectrometry
Authors: Belov Mikhail E. , Gorshkov Michael V. , Alving Kim , Smith Richard D.
Published: January 2005

When combined with on‐line separations (e.g., capillary liquid chromatography (LC)), Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS) provides a powerful tool for biological applications, and particularly proteomic studies. The sensitivity, dynamic range, and duty cycle provided by FTICR‐MS have been shown to be increased by ion trapping and accumulation in a two‐dimensional (2D) radio‐frequency (rf)‐only multipole positioned externally to an FTICR cell. However, it is important that ions be detected across the desired m/z range without a significant bias. In this work we found that pressure inside the accumulation rf‐quadrupole plays an important role in obtaining ‘unbiased’ ion accumulation. Pressure optimization was performed in both pulsed and continuous modes. It was found that unbiased accumulation in a 2D rf‐only quadrupole could be achieved in the pressure range of 5 × 10−4 to 5 × 10−3 Torr. External ion accumulation performed at the optimal pressure resulted in an increase in both the spectrum acquisition rates and dynamic range. Copyright © 2001 John Wiley & Sons, Ltd.
Comparative quantitative fatty acid analysis of triacylglycerols using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry and gas chromatography
Authors: Hlongwane C. , Delves I. G. , Wan L. W. , Ayorinde F. O.
Published: January 2005

Quantitative analyses of fatty acids from five triacylglycerol products, coconut oil, palm kernel oil, palm oil, lard and cocoa butter, were carried out using two analytical methods: matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) and gas chromatography (GC), in an effort to validate the application of MALDI‐TOFMS in quantitative fatty acid analysis. For the GC analysis, transmethylated products were used, whereas, for the MALDI‐TOF analysis, saponified products were used. Under MALDI‐TOF conditions, the acids were detected as sodiated sodium carboxylates [RCOONa + Na]+ consistent with the mode of ionization that was previously reported.

Thus, the MALDI‐TOF mass spectrum of saponified coconut oil showed the presence of sodiated sodium salts of caprylic acid (7.5 ± 0.67, m/z 189), capric acid (6.9 ± 0.83, m/z 217), lauric acid (47.8 ± 0.67, m/z 245), myristic acid (20.4 ± 0.51, m/z 273), palmitic acid (9.8 ± 0.47, m/z 301), linoleic acid (0.9 ± 0.07, m/z 325), oleic acid (4.8 ± 0.42, m/z 327) and stearic acid (2.0 ± 0.13, m/z 329). Saponified palm kernel oil had a fatty acid profile that included caprylic acid (3.5 ± 0.59), capric acid (4.7 ± 0.82), lauric acid (58.6 ± 2.3), myristic acid (20.9 ± 1.5), palmitic acid (7.2 ± 1.1), oleic acid (3.8 ± 0.62) and stearic acid (1.2 ± 0.15). Saponified palm oil gave myristic acid (0.83 ± 0.18), palmitic acid (55.8 ± 1.7), linoleic acid (4.2 ± 0.51), oleic acid (34.5 ± 1.5), stearic acid (3.8 ± 0.26) and arachidic acid (0.80 ± 0.22). Saponified lard showed the presence of myristic acid (1.5 ± 0.24), palmitic acid (28.9 ± 1.3), linoleic acid (13.7 ± 0.67), oleic acid (38.7 ± 1.4), stearic acid (12.8 ± 0.64) and arachidic acid (2.4 ± 0.35). Finally, for saponified cocoa butter, the fatty acid distribution was: palmitic acid (32.3 ± 1.0), linoleic acid (2.6 ± 0.35), oleic acid (34.9 ± 1.7) and stearic acid (30.3 ± 1.6).

Quantitative gas chromatographic analysis of the corresponding methyl esters from these triacylglycerol products yielded data that were mostly in agreement with the MALDI‐TOFMS data. The MALDI‐TOF experiment, however, proved to be superior to the GC experiment, particularly with regard to baseline resolution of unsaturated acids. Furthermore, the ability of MALDI‐TOFMS to detect low concentrations of fatty acids rendered it more sensitive than the GC methodology. Copyright © 2001 John Wiley & Sons, Ltd.
A simple and robust conductive graphite coating for sheathless electrospray emitters used in capillary electrophoresis/mass spectrometry
Authors: Nilsson Stefan , Wetterhall Magnus , Bergquist Jonas , Nyholm Leif , Markides Karin E.
Published: January 2005

A graphite‐polyimide mixture was used as a conductive coating for sheathless electrospray emitters. The coating procedure described is simple and inexpensive compared to previously described methods. An investigation of the stability of the conductive coating carried out by electrochemical methods revealed good performances during oxidative stress. In addition, no decrease in emitter performance was seen during continuous electrospray in the positive electrospray mode for two weeks. Fast capillary electrophoresis with attomole sensitivity demonstrated the excellent performance of the described sheathless interface when used in conjunction with an orthogonal time‐of‐flight mass spectrometer. The overall simplicity, stability and low cost of this type of sheathless emitter make the described approach highly suitable for any on‐column coupling of low flow rate separation techniques to a mass spectrometer. Copyright © 2001 John Wiley & Sons, Ltd.
Study of mass spectrometric fragmentations of tributyl phosphate via collision‐induced dissociation
Authors: Lesage Denis , Virelizier Henri , Tabet Jean Claude , Jankowski Christopher K.
Published: January 2005

Tributyl phosphate (TBP) fragmentation mechanisms were studied by mass spectrometry (MS) and tandem mass spectrometry (MS/MS), using electron impact (EI) or chemical (CI) ionisation of the parent compound and its deuterated analogues. The study of this simple compound is essential for the analysis of complex post‐radiolysis mixtures and the identification of particular effects arising from the radiolysis or acid hydrolysis of TBP during nuclear fuel reprocessing. Energy‐resolved mass spectrometry (ERMS) and isotopic labelling helped to establish the fragment ion connectivities by distinct identification of the competitive and consecutive mechanisms. An ion‐dipole intermediate hypothesis, proposed previously in the case of alkyl phosphates and phosphonates in order to explain the mobility of hydrogen atoms from the alkyl chains, is rejected on the basis of the identification of competitive mechanisms in the TBP fragmentation pathways. Copyright © 2001 John Wiley & Sons, Ltd.
Numerical investigation of the effect of electrode size on the behaviour of quadrupole mass filters
Authors: Gibson John Raymond , Taylor Stephen
Published: January 2005

The behaviour of a quadrupole mass spectrometer (QMS) for variation in rod size has been investigated using a numerical approach reported previously. Behaviour is found to vary significantly with the change in rod size and the optimum rod size suggested is closer to that used in some commercial QMS instruments than to the value from analytical approaches. The results allow an upper limit to manufacturing tolerances to be inferred. The present work also confirms that the size of the QMS housing has only a very small effect on QMS behaviour. Copyright © 2001 John Wiley & Sons, Ltd.
A solid phase extraction method for the screening and determination of pyrethroid metabolites and organochlorine pesticides in human urine
Authors: Columé A. , Cárdenas S. , Gallego M. , Valcárcel M.
Published: January 2005

A screening method has been developed for the determination of 23 organochlorine pesticides (OCPs) and 3‐pyrethroid metabolities [cis‐ and trans‐3‐(2,2‐dichlorovinyl)‐2,2‐dimethyl‐(1‐cyclopropane) carboxylic acid, cis‐3‐(2,2‐dibromovinyl)‐2,2‐dimethyl‐(1‐cyclopropane) carboxylic acid and 3‐phenoxybenzoic acid] from human urine. OCPs were directly detected in urine samples while pyrethroid metabolites required acid‐induced hydrolysis to convert their conjugates into free acids; all compounds were then cleaned‐up/preconcentrated using solid phase extraction. Determination and quantitation was achieved by gas chromatography with a mass spectrometer detector operating in selected ion monitoring mode. Limits of detection varied between 0.1 and 0.3 ng/mL with linear ranges from 0.3 to 700 ng/mL; the precision of the method was high (4.3–7.2%). Recoveries of all analytes from urine samples fortified at levels of 30 ng/mL for each OCP and 15 ng/mL for each pyrethroid metabolite ranged from 88 to 101% (captan gave the lowest recovery). The results obtained from the analysis of real urine samples show the suitability of the proposed method for monitoring people exposed to organochlorine and pyrethroid pesticides. Copyright © 2001 John Wiley & Sons, Ltd.
High‐sensitivity negative‐ion laser spray for liquid chromatography/mass spectrometry
Authors: Hiraoka Kenzo , Asakawa Yoshiki , Yamamoto Yasuteru , Nakamura Masana , Ueda Kazuhiro
Published: January 2005

A negative‐ion mode laser spray interface for use in liquid chromatography/mass spectrometry (LC/MS) has been developed and investigated. The laser spray gave sensitivities that were orders of magnitude better than the negative‐ion electrospray for all samples investigated with the exception of sugars. Fragment ions, HSO4− and SO3−, were formed from the laser‐sprayed aqueous solution of cholesterol 3‐sulfate sodium salt. This suggests that structural information may be obtained directly from the laser‐spray mass spectra for thermally labile compounds. Copyright © 2001 John Wiley & Sons, Ltd.
A novel multifunctional labeling reagent for enhanced protein characterization with mass spectrometry
Authors: Peters Eric C. , Horn David M. , Tully David C. , Brock Ansgar
Published: January 2005

Individual peptides with lysine at the C‐terminus as well as protein tryptic digests were reacted with 2‐methoxy‐4,5‐dihydro‐1H‐imidazole, converting lysine residues to their 4,5‐dihydro‐1H‐imidazol‐2‐yl derivatives. The mass spectra of derivatized digests exhibit a greater number of more intense features than their underivatized counterparts, thus increasing the information obtained in peptide mapping experiments. Additionally, MS/MS spectra of the derivatized peptides are greatly simplified in comparison to their native species, yielding primarily an easily interpretable series of y‐ions. Finally, this novel label also enables differential quantitation studies, as a stable isotopic form containing four deuterium atoms can readily be produced. Copyright © 2001 John Wiley & Sons, Ltd.
Stabilization of invariant sets for nonlinear systems with applications to control of oscillations
Authors: Shiriaev Anton S. , Fradkov Alexander L.
Published: January 2005

The existing results on stabilization of invariant sets for nonlinear systems based on speed–gradient method and the notion ofV‐detectability are overviewed and extended. Applications to control of oscillations in pendulum, cart–pendulum and spherical pendulum systems are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Robust stability and structured uncertainty bounded by the Euclidean norm
Authors: Álamo Teodoro , Dormido Sebastian
Published: January 2005

In the context of robust stability, theμ‐problem is generalized for uncertainty bounded by means of the Euclidean norm. In some cases, a weighted Euclidean norm may be preferable to the infinite norm, for example, when the deviation from the nominal parameters exhibits a Gaussian distribution, also in the case that the parameters of the system are estimated by the ellipsoid algorithm. Several polynomial‐time upper bounds for the newμ‐problem are proposed. Copyright © 2001 John Wiley & Sons, Ltd.
A comparison of small gain versus Lyapunov type robust stability bounds
Authors: Chen Jie , Ren Zhang
Published: January 2005

We address stability issues pertaining to perturbed linear time‐invariant systems described by state space models. We show that for a class of highly structured uncertainties in the system matrix, a robust stability bound given by the complex structured singular value is less conservative than that obtained via Lyapunov approach. This result thus provides a counterpart to an earlier one pertaining to unstructured uncertainties, and serves to extend and support the statement that frequency domain small gain conditions may often be less conservative than those time domain criteria obtained using Lyapunov approach. Copyright © 2001 John Wiley & Sons, Ltd.
Exotic and native vegetation establishment following channelization of a western Iberian river
Authors: Aguiar F.C. , Ferreira M.T. , Moreira I.
Published: January 2005

Channelization is often a major cause of human impacts on river systems. It affects both hydrogeomorphic features and habitat characteristics and potentially impacts riverine flora and fauna. Human‐disturbed fluvial ecosystems also appear to be particularly vulnerable to exotic plant establishment. Following a 12‐year recovery period, the distribution, composition and cover of both exotic and native plant species were studied along a Portuguese lowland river segment, which had been subjected to resectioning, straightening and two‐stage bank reinforcement, and were compared with those of a nearby, less impacted segment. The species distribution was also related to environmental data. Species richness and floristic composition in the channelized river segment were found to be similar to those at the more ‘natural’ river sites. Floral differences were primarily consistent with the dominance of cover by certain species. However, there were significant differences in exotic and native species richness and cover between the ‘natural’ corridor and the channelized segment, which was more susceptible to invasion by exotic perennialtaxa, such asEryngium pandanifolium,Paspalum paspalodes,Tradescantia fluminensisandAcacia dealbata. Factorial and canonical correspondence analyses revealed considerable patchiness in the distribution of species assemblages. The latter were associated with small differences in substrate composition and their own relative position across the banks and along the river segments in question. Data was also subjected to an unweighted pair‐group arithmetic average clustering, and the Indicator Value methodology was applied to selected cluster noda in order to obtain significant indicator species. Copyright © 2001 John Wiley & Sons, Ltd.
Sediment deposition along the channel margins of a reach of the middle River Severn, UK
Authors: Steiger J. , Gurnell A.M. , Petts G.E.
Published: January 2005

This paper investigates vegetational, hydrological and geomorphological influences on sedimentation within the river margin of a 1.7 km, sinuous reach of the River Severn, UK. The empirical study was designed to investigate the impact of the following factors on riparian zone sediment deposition: (i) land use, (ii) channel planform location, (iii) the flood stage at which inundation occurs, (iv) submersion time, (v) flood event timing and ordering. Sedimentation was observed using sediment traps located on 48 sample plots within four sites (one on pasture, one within a poplar plantation and two within mixed riparian woodland) during four flood events. A total of 177 observations of sediment deposition were analysed for total dry weight of sediment, particle size and organic content. All sample plots were located within a 30 m wide ribbon of the riparian zone, immediately above the limit of perennial vegetation (i.e. the edge of the low flow channel). Patterns and rates of sedimentation differed between flood events. Whilst significant differences were found in sedimentation between the four sample sites, these were interpreted to be more a function of planform location than land use. The most marked variations were found in the quantity, particle size and organic content of deposited sediment according to riparian zone cross‐sectional morphology and elevation. Highest sedimentation occurred within a 1 m elevation band that correlated with the channel‐ward face of a morphological bench. Percentage sand content of deposited sediment exhibited a change from approximately 35% in a band extending from the low flow channel to a 1 m elevation above the morphological bench edge to approximately 10% above this level. Organic matter content was low (less than 5%) in sediment deposited up to a 1 m elevation above the edge of the morphological bench. Above this level, there was a gradual increase in organic matter content. These observations suggest a link between the form of the riparian zone and the sedimentation process. The relative influence of vegetational, hydrological and geomorphological influences on sedimentation characteristics are also discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Understanding natural patterns and processes in river corridors as the basis for effective river restoration
Authors: Ward J.V. , Tockner K. , Uehlinger U. , Malard F.
Published: January 2005

An Erratum has been published for this article in Regulated Rivers: Research and Management 17 (6) 2001, 311–323.

Running water ecology is a young science, the conceptual foundations of which were derived largely from research conducted in Europe and North America. However, virtually all European river corridors were substantially regulated well before the science of river ecology developed. While regulation of North American river systems occurred later than in European systems, river ecology also developed later. Therefore, there is a general impression of rivers as being much less heterogeneous and much more stable than they actually are in the natural state. The thesis of this paper is that established research and management concepts may fail to fully recognize the crucial roles of habitat heterogeneity and fluvial dynamics owing to a lack of fundamental knowledge of the structural and functional features of morphologically intact river corridors. Until quite recently, most concepts in river ecology were based on the implicit assumption that rivers are stable, single‐thread channels isolated from adjacent floodplains. Unfortunately, many rivers are in just such a state, but it should be recognized that this is not the natural condition. This incomplete understanding constrains scientific advances in river ecology and renders management and restoration initiatives less effective. Examples are given of the high level of spatio‐temporal heterogeneity that may be attained in rivers where natural processes still operate on a large scale. The objective of this paper is to promulgate a broader and more integrative understanding of natural processes in river corridors as a necessary prelude to effective river conservation and management. Copyright © 2001 John Wiley & Sons, Ltd.
Cannibalism governing mortality of juvenile brown trout,Salmo trutta, in a regulated stream
Authors: Vik Jon Olav , Borgstrøm Reidar , Skaala Øystein
Published: January 2005

Although lake‐dwelling trout frequently eat smaller conspecifics in the absence of other fish prey, there are fewer reports of cannibalism in stream populations. However, a coarse riverbed structure and low discharge may facilitate cannibalism by providing pools for large fish whilst limiting refuges for small ones.

We estimated the autumn size structure and density of the seatrout population in a regulated stream in western Norway over a period of 12 years. Bioenergetics models were used to relate energy intake in large trout (≥17 cm) to the biomass of small fish present.

The number of 0+ trout in autumn decreased with increasing abundance of large trout (log‐log regression, nonlinearR2=0.80,n=10,p=0.0005). The size distribution of 0+ trout in autumn had a lower mean, but more positive skewness, when many small fish were present. Twenty percent of the large trout sampled had parr of trout or salmonSalmo salarin their stomach. The total food consumption estimated for large trout exceeded the total energy content of small fish in years with few small per large trout.

We conclude that cannibalism appears to be an important cause of small‐fish mortality in this stream, regulating the abundance and size distribution of small trout. In streams with low discharge, weir building can improve conditions for large trout, presumably reducing the density of small fish. However, it is difficult to predict the net effect on smolt production of improved growth but increased mortality. Copyright © 2001 John Wiley & Sons, Ltd.
Macroinvertebrate instream flow studies after 20 years: a role in stream management and restoration
Authors: Gore James A. , Layzer James B. , Mead Jim
Published: January 2005

Over the past two decades of refinement and application of instream flow evaluations, we have examined the hydraulic habitat of aquatic macroinvertebrates in a variety of conditions, along with the role of these macroinvertebrates in sustaining ecosystem integrity. Instream flow analyses assume that predictable changes in channel flow characteristics can, in turn, be used to predict the change in the density or distribution of lotic species or, more appropriately, the availability of useable habitat for those species. Five major hydraulic conditions most affect the distribution and ecological success of lotic biota: suspended load, bedload movement, and water column effects, such as turbulence, velocity profile, and substratum interactions (near‐bed hydraulics). The interactions of these hydraulic conditions upon the morphology and behavior of the individual organisms govern the distribution of aquatic biota. Historically, management decisions employing the Physical Habitat Simulation (PHABSIM) have focused upon prediction of available habitat for life stages of target fish species. Regulatory agencies have rarely included evaluation of benthos for flow reservations. Although ‘taxonomic discomfort’ may be cited for the reluctant use or creation of benthic criteria, we suggest that a basic misunderstanding of the links between benthic macroinvertebrate and the fish communities is still a problem. This is derived from the lack of a perceived ‘value’ that can be assigned to macroinvertebrate species. With the exception of endangered mussel species (for which PHABSIM analysis is probably inappropriate), this is understandable. However, it appears that there is a greater ability to predict macroinvertebrate distribution (that is, a response to the change in habitat quality or location) and diversity without complex population models. Also, habitat suitability criteria for water quality indicator taxa (Ephemeroptera, Plecoptera, and Trichoptera; the so‐called ‘EPTs’) may also provide additional management options to stream regulators. The greatest application for macroinvertebrate criteria will be in low‐order streams where a more immediate link to fish communities can be established. We present an example from Queens Creek, in North Carolina, USA, in which monthly allocations required to preserve the integrity of the benthic macroinvertebrate community were significantly higher than for the target benthic fish species, Cottus bairdi. In the months when both Cottus and community diversity of macroinvertebrates were the ‘bottleneck’ life stages, preservation of only fish species could result in an additional 5–25% loss in macroinvertebrate habitat. We suggest that, as there becomes an increased emphasis on maintaining macroinvertebrates as monitors of stream health, there will be a concurrent emphasis on incorporating hydraulic habitat conditions as a part of bioassessment. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of hydrological regime on the drift algae in a regulated Mediterranean river (River Verdon, southeastern France)
Authors: Bertrand Céline , Siauve Véronique , Fayolle Stéphanie , Cazaubon Arlette
Published: January 2005

The lower part of the River Verdon is profusely regulated by hydroelectric impoundments and the exploitation of canals by the water supply company. This study is an attempt at determining the effects of mean daily flow on the suspended algae in this river. The sampling sectors were localized downstream to the last hydroelectric dam. Two patterns of hydrological regime were analyzed in this hydrosystem: the river manifests a stable and low residual flow and the canal is characterized by a stronger and annually variable flow.

In the canal, the algal community has a lower species richness, cell density and diversity than in the river. The abundance of drift algae decreases significantly with the flow. The composition of the algal community also varies in accordance with the flow. The response of drift algae to hydrological regime shows strong seasonal variations; the hydrological disturbance was heavily linked to the freshwater needs. Copyright © 2001 John Wiley & Sons, Ltd.
Factors regulating brown trout populations in two French rivers: application of a dynamic population model
Authors: Gouraud V. , Baglinière J.L. , Baran P. , Sabaton C. , Lim P. , Ombredane D.
Published: January 2005

A dynamic population model was developed to study the impact of biotic and abiotic environmental factors on changes in trout populations. The model is based on the Leslie Matrix and simulates population change by age class in terms of biological parameters (i.e. fish survival, fertility, growth rates), which are dependent on environmental conditions. Changes in physical habitat, expressed as Weighted Usable Area, cause displacement of fish and increased mortality. Calculations were made at 1‐month intervals to account for the effect of climatic variations on the population.

The model was used to analyze the dynamics of two trout populations, quite different in terms of their biological characteristics: one in Lower Normandy in the Oir watershed and the other in the Pyrenees Mountains in the Neste d'Oueil watershed. Application of the model to those populations revealed two types of stabilizing mechanisms. The first was a capacity for population restoration, which is well‐represented by the model through the phenomenon of density‐dependent mortality in the first months of life. The second was adjustment of the adult population to the carrying capacity of the environment.

The two applications demonstrate the utility of this type of model for understanding and simulating the dynamics of different cohorts of a population. Coupling habitat models and dynamic population models facilitates the identification of key periods during which carrying capacity—related to the hydrology—becomes a limiting factor for fish. This brings new perspectives to water management and may facilitate analysis of instream flow requirements related to water development projects, such as hydropower plants. Copyright © 2001 John Wiley & Sons, Ltd.
The importance of different scale processes for the restoration of floodplain woodlands
Authors: Hughes F.M.R. , Adams W.M. , Muller E. , Nilsson C. , Richards K.S. , Barsoum N. , Decamps H. , Foussadier R. , Girel J. , Guilloy H. , Hayes A. , Johansson M. , Lambs L. , Pautou G. , Peiry J.‐L. , Perrow M. , Vautier F. , Winfield M.
Published: January 2005

The restoration of floodplain woodlands demands an understanding of the linkages between process, form and past management history at both a local and catchment scale. Site and reach scale processes that influence the species composition of floodplain woodland species are described with a particular focus on the relationships between hydrological and sediment inputs to floodplains and the regeneration response by tree species. The importance of integrating natural science knowledge gained at the site reach scale with decisions taken at the catchment scale on water allocation priorities is then discussed.

Research was carried out on the River Öre in Sweden, The River Ouse in the United Kingdom and the River Isère and River Garonne in France. Research results at the site and reach scale allow broad definition of ideal conditions for the regeneration and growth of floodplain tree species and the flows that provide them: (1) channel movement has to occur for the creation of sedimentation sites required for the regeneration of early successional species and the flows that provide them; (2) flooding events should occur periodically to cause both channel movement and recharge floodplain water tables; (3) water table decline rates following a flood event must be slow enough that seedling roots can maintain contact with the retreating water front; (4) unseasonal flood events can cause high mortality of seedlings and prevent successful regeneration in any season. Some of the requirements for the restoration of floodplain woodlands can be delivered through site and reach scale restoration projects with reasonably predictable ecological outcomes. A more holistic approach to the provision of regeneration sites for floodplain woodlands would also include water allocation decisions targeted at providing flow conditions which could restore geomorphological processes. However, it is difficult to predict ecosystem responses to catchment scale flow allocation measures and, therefore, in the intensively managed river corridors of Western Europe, river restoration initiatives tend to be restricted to the site and reach scale. Copyright © 2001 John Wiley & Sons, Ltd.
Scales of hydroecological variability within a groundwater‐dominated stream
Authors: Wood P.J. , Hannah D.M. , Agnew M.D. , Petts G.E.
Published: January 2005

This paper aims to show how hydrological, ecological and climatological data may be analysed to assess the temporal and spatial scales at which hydroclimatological variables influence instream ecology. A groundwater‐dominated chalk stream (Little Stour River, Kent, UK), for which ecological data are available over 6 years (1992–1997), provides the focus for the testing and application of these techniques. Correlation and regression analyses are undertaken to highlight the dominant hydroclimatological factors influencing community abundance at a range of spatial scales encompassing: the entire river, upstream and downstream sectors, habitat type (riffle) and individual riffle sites. To set these results in a longer‐term context, temporal sequencing of annual air temperature and discharge regimes is undertaken (based upon 30 years of data, 1969–1999). A classification of annual discharge hydrograph ‘shape’ and ‘magnitude’ identifies years with early, intermediate or late peaks, which may be assigned into three magnitude groups. Four annual air temperature ‘magnitude’ classes are apparent. The regime analysis clearly reveals inter‐annual variability in both these key physical habitat parameters. Analysis of variance indicates a significant difference in macroinvertebrate community abundance for the hydrograph ‘shape’, ‘magnitude’ and combined classes identified at all scales of analysis, although the influence of air temperature only varied significantly between riffle sites. The techniques used may be easily adapted to water resource management. Copyright © 2001 John Wiley & Sons, Ltd.
Revisiting the serial discontinuity concept
Authors: Stanford Jack A. , Ward J.V.
Published: January 2005

We revisit the serial discontinuity concept (SDC), which predicts river ecosystem responses to stream regulation in the context of recovery with distance downstream from the dam (discontinuity distance). Many studies have described pervasive interruptions of natural biophysical gradients of dams by comparing conditions in tailwaters to reference or pre‐impoundment conditions. But only a few studies provide data or interpretations that explicitly test the SDC within entire stream corridors or along specifically defined reaches where recovery was expected in view of the predictions of the SDC. We present discontinuity distance measures for nine rivers around the world where the predictions of the SDC were substantiated. In two cases, recovery trajectories were overwhelmed by other human sources of disturbance. In one case, the SDC did not hold up, but only biotic measures were made. We conclude that, in general, the SDC is a sound construct that in most cases can be used to predict, or at least clearly articulate, the consequences of new regulation. The next step is to develop better empirical models of the SDC and to validate them experimentally through re‐regulation of entire river corridors. Copyright © 2001 John Wiley & Sons, Ltd.
Annual dynamics of the fish stock in a backwater of the River Dyje
Authors: Lusk Stanislav , Halačka Karel , Lusková Vĕra , Horák Václav
Published: January 2005

Canalization of the lower reaches of the River Dyje included the isolation of its meanders. One of these meander lakes remained connected at its downstream end with the River Dyje at river kilometre (r. km) 4.44. The meander lake was 500 m long, with a width varying from 30 to 50 m, and a surface area of 1.2–2.0 ha depending on the water level in the river. In 1997–1999 we studied the temporal changes in the species composition of the fish stock, using gill nets and electrofishing. We found 38 fish species in the backwater under study. Cyprinid fishes were most common, especially Rutilus rutilus, Alburnus alburnus, Abramis brama, A. ballerus, Blicca bjoerkna, Carassius auratus. We also caught rare species such as Abramis sapa, Pelecus cultratus and Gymnocephalus schraetser, or species new to the Czech Republic, Sander volgense, Gymnocephalus baloni and Proterorhinus marmoratus. In addition to the cyprinid species mentioned above, we also found Esox lucius, Sander lucioperca, Perca fluviatilis and Gymnocephalus cernuus spawning in the backwater. There was also a permanent population of Cobitis elongatoides. The fish stock in the backwater was highly variable. Species diversity, size structure and abundance varied over the course of the year. It was markedly affected by the water discharge in the River Dyje. The results obtained document the importance of river backwaters for the fish communities inhabiting the river channel. Copyright © 2001 John Wiley & Sons, Ltd.
Man‐made secondary channels along the River Rhine (The Netherlands); results of post‐project monitoring
Authors: Simons Jennie H.E.J. , Bakker Corian , Schropp Max H.I. , Jans Luc H. , Kok Frank R. , Grift Rob E.
Published: January 2005

Owing to river regulations in the past and intensive farming, the ecological value of the floodplains of the River Rhine in The Netherlands has decreased dramatically. One way to restore riverine biotopes is to create permanently flowing channels in the floodplain. Along the River Waal, the main branch of the Lower River Rhine, two such secondary channels have been created since 1994. A post‐project monitoring programme of 5 years was set up, which included hydrological, morphological and ecological parameters. This article focuses on the monitoring of aquatic macrophytes, aquatic macroinvertebrates, fish and wading‐birds.

The results show that man‐made, excavated secondary channels function as a biotope for riverine species including the more demanding rheophilic species. The demands for shipping and protection against flooding on the River Waal cause constraints on secondary channels. Despite these constraints there is still enough space for hydromorphological processes to create new habitats in secondary channel 1, near Opijnen. The space for hydromorphological processes is less in secondary channel 2, near Beneden‐Leeuwen. The density and the number of (rheophilic) species are for a large part influenced by the water level and frequent inundation caused by the high hydrological connectivity. Man‐made secondary channels seem to provide suitable habitat that is currently lacking for a broad range of rheophilic macroinvertebrate and fish species in the Lower River Rhine in The Netherlands. Owing to the lack of suitable habitats for rheophilic macroinvertebrate and fish species before the creation of the secondary channels, the importance of longitudinal and transversal migration could be illustrated by the drift of macroinvertebrates during floods and the seasonal migration of Age‐0 and Age‐1+ fish species. Copyright © 2001 John Wiley & Sons, Ltd.
Concentration of vertex degrees in a scale‐free random graph process
Authors: Szymański Jerzy
Published: January 2005

The web may be viewed as a directed graph each of whose vertices is a static HTML Web page, and each of whose edges corresponds to a hyperlink from one Web page to another. In this paper we study the model of random graph (i.e., scale‐free random graph process) introduced by Barabási and Albert and formalized by Bollobás, Riordan, Spencer, and Tusnády, which obey two properties known as power laws for vertex degrees and “small‐world phenomenon.” In the paper we give some exact formulas and fair estimations for expectations of the number of vertices of given degree and the degree of given vertex. Moreover, based on Hájek‐Rényi inequality we give the rate of concentration of the number of vertices of given degree. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2005
Municipalities and industrial ecology: reconsidering municipal environmental management
Authors: Burström Fredrik , Korhonen Jouni
Published: January 2005

In order for society to secure a healthy environment and reach sustainability, there is a need for reconsideration of municipal environmental management (MEM). Among other things, the potential roles of a municipality in regionally oriented environmental management and development planning have to be further analysed. In this paper, MEM is confronted with the concept of industrial ecology (IE). In particular, the role of a municipality in developing regional industrial ecology, and, vice versa, the role of regional industrial ecology in developing MEM, will be reflected upon. It is argued that a municipality, serving as aninstitutional anchor tenant, may provide the regional IE effort with the needed institutional support. In return, regional IE seems to have the potential to provide a basis for increased co‐operation between public and private actors of a region as well as integration of regional environmental and development issues. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment.
Phenytoin differentially modulates the affinity of agonist and antagonist ligands for σ1 receptors of guinea pig brain
Authors: Cobos Enrique J. , Baeyens José M. , Del Pozo Esperanza
Published: January 2005

We evaluated the effects of phenytoin (DPH) on the affinity for sigma‐1 (σ1) receptors of agonist or antagonist σ1 ligands in guinea pig brain. Heterologous competition experiments showed that DPH (250 μM and 1 mM) concentration‐dependently increased the affinity of the σ1 agonists dextromethorphan, (+)‐SKF‐10,047, (+)‐3‐PPP, and PRE‐084. However, neither DPH 250 μM nor 1 mM increased (in fact, they slightly decreased) the affinity of the σ1 receptor antagonists haloperidol, BD 1063, NE‐100, progesterone, and BD 1047. These findings suggest that allosteric modulation by DPH of the affinity of σ1 receptor ligands depends on the agonist or antagonist characteristics of the ligand. Therefore, determining in vitro the differential modulation by DPH of σ1 ligand affinity appears to constitute a procedure that can predict the pharmacological profile of different σ1 ligands. Synapse 55:192–195, 2005. © 2005 Wiley‐Liss, Inc.
Nicotine stimulates dendritic arborization in motor cortex and improves concurrent motor skill but impairs subsequent motor learning
Authors: Gonzalez Claudia L.R. , Gharbawie Omar A. , Whishaw Ian Q. , Kolb Bryan
Published: January 2005

The effect of the premature commitment of neurons to exuberant growth by nicotine on concurrent and subsequent learning is unknown and was the focus of the present study. Animals were trained on a tray reaching for food task (where lots of pieces of chicken feed were available) for 3 weeks before they received two daily injections of nicotine (0.3 mg/kg) or 0.9% saline for 12 days. Measures of tray‐reaching performance were obtained before the administration of nicotine and every other week for a total of 7 weeks. Starting on week 8, animals were given a novel motor skill problem that required them to learn to use a forepaw to reach through a slot in a cage for single food pellets located on an external shelf. Pyramidal cells in the forelimb area of both hemispheres were then examined for dendritic length and branching using a Golgi‐Cox procedure. Animals treated with saline displayed excellent performance in both reaching tasks and an increase in neuronal branching in Layer V pyramidal cells in the motor cortex contralateral to the reaching paw. In contrast, animals treated with nicotine showed bilateral increases in neuronal branching. Behavioral results showed that nicotine improved forelimb use in the concurrently administered tray‐reaching task, but severely degraded quantitative and qualitative scores of skilled forelimb use in the subsequently administered single‐pellet reaching task. The results suggest that plasticity coincidence with skilled training is essential to skilled motor learning, but this expenditure can impair subsequent learning. Synapse 55:183–191, 2005. © 2005 Wiley‐Liss, Inc.