bluuebunny/crossref_metadata_2025 huggingface dataset:
Beyond Traditional Borders: A New Proposal for Federalism
Authors: Frey Bruno S.
Published: December 2005

A federal, i.e. decentralized, state is superior to a centralized one because it fulfills the preferences of the citizens more effectively. However, it is also faced with major problems. Therefore, a new kind of democratic federalism for Europe is proposed which maintains the great advantages of federalism but which overcomes its most important weaknesses. Functional, overlapping, and competing jurisdictions (FOCJ) emerge in response to the 'geography of problems'. This concept suggests that prospective new member countries of the European Union should have the possibility of partially entering the EU with respect to functions where they expect positive net benefits.
When Economists Dream, They Dream of Clear Skies
Authors: Gayer Ted , Horowitz John , List John A.
Published: December 2005

Clear Skies is an economists approach to pollution reduction. We heartily endorse its core approach, while recommending surgery for a few minor blemishes.
Straight Talk on Social Security Reform
Authors: Boskin Michael J
Published: December 2005

The critics of President Bushs Social Security reform proposal claim there will be massive cuts in guaranteed benefits of 40% or more. That is absurd. Nobodys benefits need to be cut and nobodys taxes need to be raised. Current tax rates, given projected economic growth, are sufficient to deal with the demographic deluge. However, the current benefit formula projects real Social Security benefits per recipient will double within a few decades. Further, benefits involve immense economic, demographic and political risk.Four commonsense reforms would make Social Security solvent and modernize it. First, switch from wage to price indexing, except for those with low earnings; 2) slightly increase the retirement age in the distant future, while maintaining a strong early retirement option; 3) the Bureau of Labor Statistics (BLS)  not the Congress -- should soon implement its far more accurate chained-CPI that accounts for consumer substitution in purchases. 4) add a small individual accounts component to Social Security.These reforms will resolve the solvency problem without a tax increase, eradicate poverty among the elderly, and for the first time, enable the bottom half of the wealth distribution to acquire financial assets.Critics claim there is no problem, no rush. The first baby boomers retire in three years. The ratio of beneficiaries to taxpayers will double in a few decades, making reform ever more difficult. Reform is overdue and should be gradual and cumulative, to avoid economic disruption to beneficiaries, taxpayers and the economy. Thus reform really is urgent.
Does College Still Pay?
Authors: Barrow Lisa , Rouse Cecilia Elena
Published: December 2005

Since the mid-1990s college tuition costs have risen quickly while the rate of increase in the value of education has slowed considerably. Cecilia Rouse and Lisa Barrow explore the reasons and ask if college remains a good investment.
Reform U.S. Capital Gains Taxation à la Canada
Authors: Kesselman Jonathan R.
Published: December 2005

Reformed taxation of capital gains could play an important role in a broader policy package to improve the simplicity, equity, and efficiency of the federal tax system. Constructive reforms for the United States would draw on Canadian provisions for taxing capital gains: a) eliminate the distinction between short-term and long-term gains, taxing both equally; b) use an average-cost basis for computing capital gains on all holdings of a security; c) apply a fixed tax inclusion rate for net capital gains; d) eliminate the $3,000 offset of taxable income for net capital losses; and e) adopt deemed realization of capital gains on death to facilitate quick abolition of the estate tax.
The Economics of Rebuilding Cities: Reflections after Katrina
Authors: Hahn Robert W.
Published: December 2005

In the aftermath of Katrina, Robert Hahn asks whether and how New Orleans should be rebuilt.
Divergent Views on the Coming Dollar Crisis
Authors: DeLong J. Bradford
Published: December 2005

Is the U.S. vulnerable to a full-blown dollar crisis? Why are international finance economists scared and jittery, but domestically-oriented macroeconomists much less concerned?
The Tax Reform Proposals: Some Good Ideas, but Show Me the Money
Authors: Burman Leonard E , Gale William G.
Published: December 2005

The President's Advisory Panel on Federal Tax Reform has submitted an important set of proposed structural changes that would generally move the tax system in the right direction. However, at the tax rates the Panel proposes, the plans will not bring in the revenue the U.S. needs.
Reforming Taxes to Promote Economic Growth
Authors: Lazear Edward P. , Poterba James M
Published: December 2005

Edward Lazear and James Poterba, both members of the President's Advisory Panel on Federal Tax Reform, explain the need for tax reform, and how the Panel's proposals are geared to bring about higher growth, simplification that saves filing time, and fairness.
Chemical Marker Profile and Biological Effects of Natural Products Containing Echinacea
Authors: Foster Brian C , Drouin Cathy , Krantis Anthony , Panahi Mitra , Franovic Aleksandra , Burczynski Frank J , Yiang Ping , Arnason John T , Livesey John , Drobitch Robert , Briggs Colin
Published: December 2005

Natural health products containing Echinacea have been used by many patient populations and although there are reports of adverse effects with products containing Echinacea, few clearly characterized the nature of the product with respect to constituent content, the nature of the products and the mechanism underlying the interaction. The objective of this study was to examine blended and single-entity Echinacea products containing ground plant material or extracts in commercial capsules, herbal teas, tablets, tinctures and soft gel liquid-filled capsule formulations in an attempt to correlate biomarker constituent content and effects on cellular and subcellular parameters of interest. HPLC analysis indicated significant variability in the major biomarker constituent content in extracts from these Echinacea products. These extracts were also examined for their potential to affect cytochrome P450 CYP1A1/2, 2C9*1, 2C9*2, 2C19, 2D6, 3A4, 3A5, 3A7, and flavin-containing monooxygenase 3 (FMO3); CYP3A5-mediated metabolism, and expression of CYP3A4 and ABCB1. The extracts of some products were also examined for their effect cellular processes such as cell proliferation, nitric oxide formation as a marker of immunostimulatory capacity, and lactate dehydrogenase release as a marker for cell toxicity. The present study indicated that key Echinacea constituents varied widely within and between the products tested and that these levels did not correlate with the ability of these products to markedly affect the cellular processes studied.
Cover Picture: Self‐Assembly of Single‐Walled Carbon Nanotubes into a Sheet by Drop Drying (Adv. Mater. 1/2006)
Authors: Duggal R. , Hussain F. , Pasquali M.
Published: December 2005

Drops of a suspension of individual single‐walled carbon nanotubes in F68 Pluronic surfactant dry on glass substrates to form a “crust” at the free surface. The crust is extremely thin (∼ 100 nm) and consists of an entangled mesh of nanotubes and Pluronic. Pasquali and co‐workers report on p. 29 that the convective flow associated with the drying preferentially assembles the micelles into a hexagonal arrangement, as revealed by the birefringent pattern shown on the cover. This technique is promising for developing thin, optically transparent, and electrically conductive coatings and films consisting of nanotubes.
Inside Front Cover: Multicolor Photoluminescence from Porous Silicon Using Focused, High‐Energy Helium Ions (Adv. Mater. 1/2006)
Authors: Teo E. J. , Breese M. B. H. , Bettiol A. A. , Mangaiyarkarasi D. , Champeaux F. , Watt F. , Blackwood D. J.
Published: December 2005

Controlled light emission from porous silicon has been obtained by focused helium beam irradiation prior to electrochemical etching in hydrofluoric acid. The photoluminescence wavelength of porous silicon can be continuously red‐shifted with increasing dose to produce different color emission on a single substrate, as shown in work by E. J. Teo and co‐workers on p. 51. The image features an orange dragon produced on a green background, which clearly shows the longer wavelength emission from the irradiated regions as compared to the un‐irradiated background.
Inverse relation between in vivo amyloid imaging load and cerebrospinal fluid Aβ42 in humans
Authors: Fagan Anne M. , Mintun Mark A. , Mach Robert H. , Lee Sang‐Yoon , Dence Carmen S. , Shah Aarti R. , LaRossa Gina N. , Spinner Michael L. , Klunk William E. , Mathis Chester A. , DeKosky Steven T. , Morris John C. , Holtzman David M.
Published: December 2005

Objectives

Amyloid‐β42 (Aβ42) appears central to Alzheimer's disease (AD) pathogenesis and is a major component of amyloid plaques. Mean cerebrospinal fluid (CSF) Aβ42 is decreased in dementia of the Alzheimer's type. This decrease may reflect plaques acting as an Aβ42 “sink,” hindering transport of soluble Aβ42 between brain and CSF. We investigated this hypothesis.

Methods

We compared the in vivo brain amyloid load (via positron emission tomography imaging of the amyloid‐binding agent, Pittsburgh Compound‐B [PIB]) with CSF Aβ42 and other measures (via enzyme‐linked immunosorbent assay) in clinically characterized research subjects.

Results

Subjects fell into two nonoverlapping groups: those with positive PIB binding had the lowest CSF Aβ42 level, and those with negative PIB binding had the highest CSF Aβ42 level. No relation was observed between PIB binding and CSF Aβ40, tau, phospho‐tau181, plasma Aβ40, or plasma Aβ42. Importantly, PIB binding and CSF Aβ42 did not consistently correspond with clinical diagnosis; three cognitively normal subjects were PIB‐positive with low CSF Aβ42, suggesting the presence of amyloid in the absence of cognitive impairment (ie, preclinical AD).

Interpretation

These observations suggest that brain amyloid deposition results in low CSF Aβ42, and that amyloid imaging and CSF Aβ42 may potentially serve as antecedent biomarkers of (preclinical) AD. Ann Neurol 2006
Cover Picture: Applications of Transition‐Metal Catalysts to Textile and Wood‐Pulp Bleaching (Angew. Chem. Int. Ed. 2/2006)
Authors: Hage Ronald , Lienke Achim
Published: December 2005

Bleaching catalysts accelerate the removal of a variety of unwanted chromophores present in stains or wood pulp. The cover picture shows the structures of lignin residues from wood pulp and of lycopene which is found in tomato stains. Peroxo–metal and oxo–metal species are proposed as intermediates in the various catalytic cycles. In their Review on page 206 ff. R. Hage and A. Lienke show that a large variety of transition‐metal complexes enhance the activity of H2O2 or O2 towards stain or wood‐pulp bleaching.
Continuous‐time stochastic modelling of capital adequacy ratios for banks
Authors: Fouche Casper H. , Mukuddem‐Petersen J. , Petersen M. A.
Published: December 2005

Regulation related to capital requirements is an important issue in the banking sector. In this regard, one of the indices used to measure how susceptible a bank is to failure, is the capital adequacy ratio (CAR). We consider two types of such ratios, viz. non‐risk‐based (NRBCARs) and risk‐based (RBCARs) CARs. According to the US Federal Deposit Insurance Corporation (FDIC), we can further categorize NRBCARs into leverage and equity capital ratios and RBCARs into Basel II and Tier 1 ratios. In general, these indices are calculated by dividing a measure of bank capital by an indicator of the level of bank risk. Our primary objective is to construct continuous‐time stochastic models for the dynamics of each of the aforementioned ratios with the main achievement being the modelling of the Basel II capital adequacy ratio (Basel II CAR). This ratio is obtained by dividing the bank's eligible regulatory capital (ERC) by its risk‐weighted assets (RWAs) from credit, market and operational risk. Mainly, our discussions conform to the qualitative and quantitative standards prescribed by the Basel II Capital Accord. Also, we find that our models are consistent with data from FDIC‐insured institutions. Finally, we demonstrate how our main results may be applied in the banking sector. Copyright © 2005 John Wiley & Sons, Ltd.
Silver Complexes of Cyclic Hexachlorotriphosphazene
Authors: Gonsior Marcin , Antonijevic Sasa , Krossing Ingo
Published: December 2005

The first solid‐state structures of complexed P3N3X6 (X=halogen) are reported for X=Cl. The compounds were obtained from P3N3Cl6 and Ag[Al(OR)4] salts in CH2Cl2/CS2 solution. The very weakly coordinating anion with R=C(CF3)3 led to the salt Ag(P3N3Cl6)2+[Al(OR)4]− (1), but the more strongly coordinating anion with R′=C(CH3)(CF3)2 gave the molecular adduct (P3N3Cl6)AgAl(OR′)4 (3). Crystals of [Ag(CH2Cl2)(P3N3Cl6)2]+[Al(OR)4]− (2), in which Ag+ is coordinated by two phosphazene and one CH2Cl2 ligands, were isolated from CH2Cl2 solution. The three compounds were characterized by their X‐ray structures, and 1 and 3 also by NMR and vibrational spectroscopy. Solution and solid‐state 31P NMR investigations in combination with quantum chemically calculated chemical shifts show that the 31P NMR shifts of free and silver‐coordinated P3N3Cl6 differ by less than 3 ppm and indicate a very weakly bound P3N3Cl6 ligand in 1. The experimental silver ion affinity (SIA) of the phosphazene ligand was derived from the solid‐state structure of 3. The SIA shows that (PNCl2)3 is only a slightly stronger Lewis base than P4 and CH2Cl2, while other ligands such as S8, P4S3, toluene, and 1,2‐Cl2C2H4 are far stronger ligands towards the silver cation. The energetics of the complexes were assessed with inclusion of entropic, thermal, and solvation contributions (MP2/TZVPP, COSMO). The formation of the cations in 1, 2, and 3 was calculated to be exergonic by ΔrG°(CH2Cl2)=−97, −107, and −27 kJ mol−1, respectively. All prepared complexes are thermally stable; formation of P3N3Cl5+ and AgCl was not observed, even at 60 °C in an ultrasonic bath. Therefore, the formation of P3N3Cl5+ was investigated by quantum chemical calculations. Other possible reaction pathways that could lead to the successful preparation of P3N3X5+ salts were defined.
Anchoring Dyes into Multidimensional Large‐Pore Zeolites: A Prospective Use as Chromogenic Sensing Materials
Authors: Comes María , Marcos M. Dolores , Martínez‐Máñez Ramón , Millán M. Carmen , Ros‐Lis José Vicente , Sancenón Félix , Soto Juan , Villaescusa Luis A.
Published: December 2005

A versatile procedure for anchoring dyes into the pores of multidimensional zeolites by including organic dye precursors in the synthesis gel has been developed. To prove the concept, an aniline‐functionalised zeolite Beta was obtained by reaction of triethylorthosilicate (TEOS), tetraethylammonium hydroxide, and N‐methyl,N‐(propyl‐3‐trimethoxysilyl)aniline (MPTMSA) in the presence of HF. Further extraction of the structure‐directing agents resulted in a highly crystalline, white, functionalised zeolite Beta containing anchored aniline groups. Similar organic functionalised molecular sieves (OFMS) have been explored as novel catalysts, but, as far as we know, OFMS have never been used as precursors for dye‐immobilisation or to design new solid‐based host systems for selective molecular sensing processes as is reported here. In a second step the solids containing dyes were prepared by reaction of the hybrid material with the appropriate reactives to obtain tricyanovinylbenzene, triphenylpyrylium, azoic, and squaraine derivatives. All these reactions are straightforward and involve electrophilic aromatic substitution or diazotisation reactions at the electron‐rich aniline ring. The final dye‐functionalised solid materials were isolated by simple filtration and washing procedures and have been characterised by a number of techniques. In all cases the Beta structure of the solid remains unaltered. Among the large number of areas where dye‐containing zeolites might be of importance, we were interested in testing their unconventional use as heterosupramolecular hosts in chromogenic protocols. To check their potential use as chemosensors, microporous solids with anchored triphenylpyrilium and squaraine dyes were selected and used as sensors for the chromogenic discrimination of amines. It was found that the response of both solids to amines was basically governed by the three‐dimensional (3D) solid architecture that tuned the intrinsic unselective reactivity of the pyrylium dye. By using new solid‐state supramolecular chemistry protocols we believe that these, and similar future dye–zeolite hosts, might be promising new sensor materials allowing the visible discrimination of selected target guests by size and/or polarity within families or closely related molecules.
Naturally Engineered Glycolipid Biosurfactants Leading to Distinctive Self‐Assembled Structures
Authors: Imura Tomohiro , Ohta Noboru , Inoue Katsuaki , Yagi Naoto , Negishi Hideyuki , Yanagishita Hiroshi , Kitamoto Dai
Published: December 2005

Self‐assembling properties of “natural” glycolipid biosurfactants, mannosyl‐erythritol lipids A and B (MEL‐A, MEL‐B), which are abundantly produced from yeast strains, were investigated by using the fluorescence‐probe method, dynamic light‐scattering (DLS) analysis, freeze‐fracture transmission electron microscopy (FF‐TEM), and synchrotron small/wide‐angle X‐ray scattering (SAXS/WAXS) analysis, among other methods. Both MEL‐A and MEL‐B exhibit excellent self‐assembly properties at extremely low concentrations; they self‐assemble into large unilamellar vesicles (LUV) just above their critical‐aggregation concentration (CAC). The CACI value was found to be 4.0×10−6 M for MEL‐A and 6.0×10−6 M for MEL‐B. Moreover, the self‐assembled structure of MEL‐A above a CACII value of 2.0×10−5 M was found to drastically change into sponge structures (L3) composed of a network of randomly connected bilayers that are usually obtained from a complicated multicomponent “synthetic” surfactant system. Interestingly, the average water‐channel diameter of the sponge structure was 100 nm. This is relatively large compared with those obtained from “synthetic” surfactant systems. In addition, MEL‐B, which has a hydroxyl group at the C‐4′ position on mannose instead of an acetyl group, gives only one CAC; the self‐assembled structure of MEL‐B seems to gradually move from LUV to multilamellar vesicles (MLV) with lattice constants of 4.4 nm, depending on the concentration. Furthermore, the lyotropic‐liquid‐crystal‐phase observation at high concentrations demonstrates the formation of an inverted hexagonal phase (H2) for MEL‐A, together with a lamella phase (Lα) for MEL‐B, indicating a difference between MEL‐A and MEL‐B molecules in the spontaneous curvature of the assemblies. These results clearly show that the difference in spontaneous curvature caused by the single acetyl group on the head group probably decides the direction of self‐assembly of glycolipid biosurfactants. The unique and complex molecular structures with several chiral centers that are molecularly engineered by microorganisms must have led to the sophisticated self‐assembling properties of the glycolipid biosurfactants.
Redox Reactions in Strontium Iron Phosphates: Synthesis, Structures, and Characterization of Sr9Fe(PO4)7 and Sr9FeD(PO4)7.
Authors: Belik Alexei A. , Izumi Fujio , Azuma Masaki , Kamiyama Takashi , Oikawa Kenichi , Pokholok Konstantin V. , Lazoryak Bogdan I. , Takano Mikio
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Organocatalytic Asymmetric α‐Halogenation of 1,3‐Dicarbonyl Compounds.
Authors: Bartoli Giuseppe , Bosco Marcella , Carlone Armando , Locatelli Manuela , Melchiorre Paolo , Sambri Letizia
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Recyclable Polymer‐Supported Pd Catalysts for Aryl Amination Reactions.
Authors: Guino Meritxell , Hii King Kuok
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Solution Phase Parallel Synthesis of 4‐Aminophenyl Ethers Using a Carboxyl‐Functionalized Ionic Liquid as Support.
Authors: Peng Yanqing , Yi Fengping , Song Gonghua , Zhang Ying
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Tin‐Free Radical Carbonylation: Thiol Ester Synthesis Using Alkyl Allyl Sulfone Precursors, Phenyl Benzenethiosulfonate and CO.
Authors: Kim Sangmo , Kim Sunggak , Otsuka Noboru , Ryu Ilhyong
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Substituted Pyrrolo[3,4‐a]carbazoles from Reactions Between 3‐(1‐Methoxyvinyl)indoles and Maleimides.
Authors: Bleile Michaela , Otto Hans‐Hartwig
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Preparation and Alkali Metal Ion Exchange Properties of Protonated Rb8Nb22O59 Compound.
Authors: Yang Xiaojing , Makita Yoji , Hosokawa Junji , Sakane Kohji , Ooi Kenta
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Two‐, Three‐ and Four‐Feldspar Assemblages with Hyalophane and Celsian: Implications for Phase Equilibria in BaAl2Si2O8—CaAl2Si2 O8— NaAlSi3O8—KAlSi3O8
Authors: Essene Eric J. , Claflin Christopher L. , Giorgetti Giovanna , Mata Pilar M. , Peacor Donald R. , Arkai Peter , Rathmell Mark A.
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
The Synthesis of Fluorinated Heteroaromatic Compounds. Part 1. Five‐Membered Rings with More than Two Heteroatoms
Authors: Pace Andrea , Buscemi Silvestre , Vivona Nicolo
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
The π‐Halogen Dimer (PHD) Interaction: A Versatile New Construction Unit for Crystal Engineering
Authors: Bishop Roger , Scudder Marcia L. , Craig Donald C. , Rahman A. Noman M. M. , Alshahateet Solhe F.
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Conjugated Polymers and Aromaticity
Authors: Kertesz Miklos , Choi Cheol Ho , Yang Shujiang
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Interrelation Between H‐Bond and Pi‐Electron Delocalization
Authors: Sobczyk Lucjan , Grabowski Slawomir Janusz , Krygowski Tadeusz Marek
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Quantum Cascade Semiconductor Infrared and Far‐Infrared Lasers: From Trace Gas Sensing to Non‐Linear Optics
Authors: Duxbury Geoffrey , Langford Nigel , McCulloch Michael T. , Wright Stephen
Published: December 2005

For Abstract see ChemInform Abstract in Full Text.
Probing the Dinucleating Behaviour of a Bis‐Bidentate Ligand: Synthesis and Characterisation of Some Di‐ and Mononuclear Cobalt(II), Nickel(II), Copper(II) and Zinc(II) Complexes of 3,5‐Di(2‐pyridyl)‐4‐(1H‐pyrrol‐1‐yl)‐4H‐1,2,4‐triazole
Authors: Klingele Marco H. , Boyd Peter D. W. , Moubaraki Boujemaa , Murray Keith S. , Brooker Sally
Published: December 2005

As a probe of the dinucleating ability of the known but little studied bis‐bidentate ligand 3,5‐di(2‐pyridyl)‐4‐(1H‐pyrrol‐1‐yl)‐4H‐1,2,4‐triazole (pldpt) its reactivity towards MX2·6H2O (M = CoII, NiII and ZnII; X = ClO4– and BF4–) as well as Cu(ClO4)2·6H2O, in a 1:1 metal‐to‐ligand molar ratio in MeCN, has been investigated. In the case of CoII, NiII and ZnII, these reactions gave dinuclear complexes MII2(pldpt)2X4(MeCN)m(H2O)n, whereas for CuII initially the mononuclear complex [CuII(pldpt)2(ClO4)2] was isolated, followed by the dinuclear complex [CuII2(pldpt)2(MeCN)2(H2O)2](ClO4)4. The use of the strongly polar aprotic co‐solvent DMF resulted in the partial breakdown of the initial dinuclear entities in the case of CoII and NiII but not in the case of ZnII. In all five of the structurally characterised dinuclear complexes the (N′,N1,N2,N′′)2 double‐bridging coordination mode is realised with distorted octahedral N4Y2‐coordinated metal centres (Y = DMF, H2O or MeCN). The two mononuclear complexes feature the common trans‐(N′,N1)2 coordination mode with axial DMF or ClO4– co‐ligands. The near‐perpendicular orientation [82.4(3)–88.8(1)°] of the π‐electron‐rich 4‐(1H‐pyrrol‐1‐yl) substituent with respect to the triazole ring of pldpt, observed in all of these structures, means that no π‐interactions are expected between these rings so any electronic interaction is likely to be small. Whether a di‐ or mononuclear complex of pldpt forms is therefore primarily determined by a number of other factors, including the reaction stoichiometry, the nature of the counterions and the solvent, as well as the relative solubility of the various possible products. Clearly the nature of the N4 substituent can have a major impact on the last of these factors. Magnetic studies carried out on the dinuclear complexes revealed that the triazole bridges mediate relatively weak antiferromagnetic coupling between the two metal centres. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Estimating within‐field variation using a nonparametric density algorithm
Authors: Castrignanò A. , Buttafuoco G. , Pisante M. , Lopez N.
Published: December 2005

The application of site‐specific techniques and technologies in precision farming requires subdividing a field into a generally small number of contiguous homogeneous zones. The proposed algorithm of clustering is based on nonparametric density estimate, where a cluster is defined as a region surrounding a local maximum of the probability density function.

Soil samples were collected in a 2‐ha field of the experimental farm of the Agricultural Research Institute, located in Foggia (Southern Italy) and some of the most production‐affecting soil properties were interpolated by using the geostatistical techniques of kriging and cokriging.

The application of the clustering approach to the (co)kriged surface variables produced the subdivision of the field into five distinct classes.

The proposed algorithm proves quite promising in identifying spatially contiguous zones, which are more homogeneous in soil properties than the whole‐field. Its great advantage consists in giving an additional description of the residual variation within the class and such a piece of information is very useful in precision farming as a basis for the variable‐rate application of agronomic inputs. Copyright © 2005 John Wiley & Sons, Ltd.
Variable weathering response in sandstone: factors controlling decay sequences
Authors: Warke P. A. , McKinley J. , Smith B. J.
Published: December 2005

Differences in weathering response characteristics of fine‐ and coarse‐grained Stanton Moor sandstone samples were assessed in a laboratory weathering simulation experiment using a variable combination of salt weathering and freeze/thaw cycles. Preliminary analysis of permeability characteristics identified similar mean values for each type of Stanton sandstone but significant differences in the range of values between the two sample sets, with coarse‐grained samples of Stanton Moor sandstone displaying a restricted range of values in comparison to fine‐grained samples which showed much greater within‐block variation. Data indicated that the greater the range in initial permeability values, the greater the potential for salt and moisture ingress and retention and hence eventual disruption of the fabric of the stone. Experimental data also identified different stages in decay sequences, with significant structural change occurring during the initial preparatory stage before material breakdown and loss became apparent. Evidence suggests that relatively minor structural and mineralogical differences between samples of the same stone type can have a significant influence on weathering behaviour, resulting in distinct rates and patterns of breakdown. Copyright © 2005 John Wiley & Sons, Ltd.
Seasonal changes in runoff characteristics on a permafrost watershed in the southern mountainous region of eastern Siberia
Authors: Yamazaki Yusuke , Kubota Jumpei , Ohata Tetsuo , Vuglinsky Varely , Mizuyama Takahisa
Published: December 2005

We attempted to clarify the runoff characteristics of a permafrost watershed in the southern mountainous region of eastern Siberia using hydrological and meteorological data obtained by the State Hydrological Institute in Russia from 1976 to 1985. We analysed seasonal changes in the direct runoff ratio and recession gradient during the permafrost thawing period. Thawing depth began to increase from the beginning of May and continued to increase until the end of September, exceeding 150 cm. Annual precipitation and discharge were in the range 525–649 mm and 205–391 mm respectively. The sum of the annual evapotranspiration and changes in water storage ranged from 235 to 365 mm. The mean daily evapotranspiration in June, July, August and September was 1·5 mm day−1, 1·7 mm day−1, 1·5 mm day−1, and 0·5 mm day−1 respectively. The direct runoff ratio was highest in June, decreasing from 0·8 in June to 0·2 in September. The recession gradient also decreased from June to September. Since the frozen soil functioned as an impermeable layer, the soil water storage capacity in the thawing part of the soil, the depth of which changed over time, controlled the runoff characteristics. Copyright © 2005 John Wiley & Sons, Ltd.
Matching hydrologic response to measured effective hydraulic conductivity
Authors: Vigiak Olga , van Dijck Simone J. E. , van Loon E. Emiel , Stroosnijder Leo
Published: December 2005

The objective of this study was to test the practicability of defining hydrologic response units as combinations of soil, land use and topography for modelling infiltration at the hillslope and catchment scales. In an experimental catchment in the East African Highlands (Kwalei, Tanzania), three methods of measuring infiltration were compared for their ability to capture the spatial variability of effective hydraulic conductivity: the constant head (CH) method; the tension infiltration (TI) method; and the mini‐rainfall simulation (RS) method. The three methods yielded different probability distributions of effective hydraulic conductivity and suggested different types of hydrologic response units. Independently from these measurements, the occurrence of infiltration‐excess overland flow was monitored over an area of 6 ha by means of overland flow detectors. The observed pattern of overland flow occurrence did not match any of the patterns suggested by the infiltration measurements. Instead, clusters of spots with overland flow were practically independent from field borders. Geostatistical analysis of the overland flow confirmed the absence of spatial correlation for distances over 40 m. The RS method yielded the pattern closest to the observations, probably because the method simulated better the processes that trigger infiltration‐excess overland flow, i.e. soil sealing and infiltration through macroporosity. The RS hydrologic response unit correlated significantly with observed overland flow frequency. However, the location of clusters and ‘hot spots’ of overland flow remained largely unexplained by land use, soil and topographic variables. It is concluded that using such landscape variables to define hydrologic units may create artificial boundaries that do no correspond to physical realities, especially if the stochastic component within hydrologic units is neglected. Copyright © 2005 John Wiley & Sons, Ltd.
Urban fluvial flood modelling using a two‐dimensional diffusion‐wave treatment, part 1: mesh resolution effects
Authors: Yu D. , Lane S. N.
Published: December 2005

High‐resolution data obtained from airborne remote sensing is increasing opportunities for representation of small‐scale structural elements (e.g. walls, buildings) in complex floodplain systems using two‐dimensional (2D) models of flood inundation. At the same time, 2D inundation models have been developed and shown to provide good predictions of flood inundation extent, with respect to both full solution of the depth‐averaged Navier–Stokes equations and simplified diffusion‐wave models. However, these models have yet to be applied extensively to urban areas. This paper applies a 2D raster‐based diffusion‐wave model to determine patterns of fluvial flood inundation in urban areas using high‐resolution topographic data and explores the effects of spatial resolution upon estimated inundation extent and flow routing process. Model response shows that even relatively small changes in model resolution have considerable effects on the predicted inundation extent and the timing of flood inundation. Timing sensitivity would be expected, given the relatively poor representation of inertial processes in a diffusion‐wave model. Sensitivity to inundation extent is more surprising, but is associated with: (1) the smoothing effect of mesh coarsening upon input topographical data; (2) poorer representation of both cell blockage and surface routing processes as the mesh is coarsened, where the flow routing is especially complex; and (3) the effects of (1) and (2) upon water levels and velocities, which in turn determine which parts of the floodplain the flow can actually travel to. It is shown that the combined effects of wetting and roughness parameters can compensate in part for a coarser mesh resolution. However, the coarser the resolution, the poorer the ability to control the inundation process, as these parameters not only affect the speed, but also the direction of wetting. Thus, high‐resolution data will need to be coupled to a more sophisticated representation of the inundation process in order to obtain effective predictions of flood inundation extent. This is explored in a companion paper. Copyright © 2005 John Wiley & Sons, Ltd.
Urban fluvial flood modelling using a two‐dimensional diffusion‐wave treatment, part 2: development of a sub‐grid‐scale treatment
Authors: Yu D. , Lane S. N.
Published: December 2005

This paper develops and tests a sub‐grid‐scale wetting and drying correction for use with two‐dimensional diffusion‐wave models of urban flood inundation. The method recognizes explicitly that representations of sub‐grid‐scale topography using roughness parameters will provide an inadequate representation of the effects of structural elements on the floodplain (e.g. buildings, walls), as such elements not only act as momentum sinks, but also have mass blockage effects. The latter may dominate, especially in structurally complex urban areas. The approach developed uses high‐resolution topographic data to develop explicit parameterization of sub‐grid‐scale topographic variability to represent both the volume of a grid cell that can be occupied by the flow and the effect of that variability upon the timing and direction of the lateral fluxes. This approach is found to give significantly better prediction of fluvial flood inundation in urban areas than traditional calibration of sub‐grid‐scale effects using Manning's n. In particular, it simultaneously reduces the need to use exceptionally high values of n to represent the effects of using a coarser mesh process representation and increases the sensitivity of model predictions to variation in n. Copyright © 2005 John Wiley & Sons, Ltd.
A field‐scale infiltration model accounting for spatial heterogeneity of rainfall and soil saturated hydraulic conductivity
Authors: Morbidelli Renato , Corradini Corrado , Govindaraju Rao S.
Published: December 2005

This study first explores the role of spatial heterogeneity, in both the saturated hydraulic conductivity Ks and rainfall intensity r, on the integrated hydrological response of a natural slope. On this basis, a mathematical model for estimating the expected areal‐average infiltration is then formulated. Both Ks and r are considered as random variables with assessed probability density functions. The model relies upon a semi‐analytical component, which describes the directly infiltrated rainfall, and an empirical component, which accounts further for the infiltration of surface water running downslope into pervious soils (the run‐on effect). Monte Carlo simulations over a clay loam soil and a sandy loam soil were performed for constructing the ensemble averages of field‐scale infiltration used for model validation. The model produced very accurate estimates of the expected field‐scale infiltration rate, as well as of the outflow generated by significant rainfall events. Furthermore, the two model components were found to interact appropriately for different weights of the two infiltration mechanisms involved. Copyright © 2005 John Wiley & Sons, Ltd.
Snow density variations: consequences for ground‐penetrating radar
Authors: Lundberg A. , Richardson‐Näslund C. , Andersson C.
Published: December 2005

Reliable hydrological forecasts of snowmelt runoff are of major importance for many areas. Ground‐penetrating radar (GPR) measurements are used to assess snowpack water equivalent for planning of hydropower production in northern Sweden. The travel time of the radar pulse through the snow cover is recorded and converted to snow water equivalent (SWE) using a constant snowpack mean density from the drainage basin studied. In this paper we improve the method to estimate SWE by introducing a depth‐dependent snowpack density. We used 6 years measurements of peak snow depth and snowpack mean density at 11 locations in the Swedish mountains. The original method systematically overestimates the SWE at shallow depths (+25% for 0·5 m) and underestimates the SWE at large depths (−35% for 2·0 m). A large improvement was obtained by introducing a depth–density relation based on average conditions for several years, whereas refining this by using separate relations for individual years yielded a smaller improvement. The SWE estimates were substantially improved for thick snow covers, reducing the average error from 162 ± 23 mm to 53 ± 10 mm for depth range 1·2–2·0 m. Consequently, the introduction of a depth‐dependent snow density yields substantial improvements of the accuracy in SWE values calculated from GPR data. Copyright © 2005 John Wiley & Sons, Ltd.
On the use of the groundwater replenishment periods approach to determining aquifer parameters
Authors: Lallahem S. , Mania J.
Published: December 2005

Chalk crops out from a wide belt around the Paris basin, France, covering an area of about 70 000 km2. In this region, the chalk presents the most important unconfined aquifer because of its extent and the size of its resources ((11–12) × 109 m3 year−1). The assessment of underground outflow depends on the vertical feeding, the infiltration and the hydrometry. This paper analyses the regional structural map, interprets the groundwater reaction under rainfall, explains the water circulation in such media where the reservoir geometry plays an essential role on aquifer response, and determines different aquifer physical parameters. Attempts are made to identify the rapid transfer of groundwater at the level of faults and their important fissures. Based on a quantitative study of the seasonal and interannual piezometry fluctuations, it is noted that the mode and the piezometric chronology events are controlled by major parameters of geological and hydrogeologic contexts, aquifer hydraulic characteristics, the position of upstream and downstream basin limits, groundwater depth and replenishment time. This paper ends with determination of groundwater physical parameters of the diffusivity (T/S, T and S) values by examination of the groundwater replenishments periods. Copyright © 2005 John Wiley & Sons, Ltd.
Statistical characterization of arsenic contamination in shallow tube wells of western Bangladesh
Authors: Hossain Faisal , Bagtzoglou Amvrossios C. , Nahar Nurun , Delawer Hossain M.
Published: December 2005

A regional assessment of the arsenic (As) contamination scenario in shallow tube wells (depth < 150 m) of western Bangladesh is presented. Comparisons are made in light of bulk geological differences (Pleistocene versus Holocene deposits/northwest versus southwest) and As measurement protocols (field kit (FK) versus atomic absorption spectroscopy (AAS)). Our As database comprised the following: (1) the nationwide As survey completed in 1999 by the British Geological Survey in collaboration with the Department of Public Health Engineering (DPHE); and (2) a regional As survey conducted in southwest Bangladesh by the Japan International Cooperation Agency in collaboration with DPHE in 2002. First, we characterize the error structure of the semi‐quantitative FK As measurements using collocated AAS As measurements as reference from a set of 307 wells located in southwest Bangladesh. The depth distribution of As is identified using a very dense cluster of 2963 wells over a 560 km2 domain. The probability of the FK method for successful detection of a well sample as unsafe (safe) was found to be 96·9% (34·1%) and 95·2% (80·3%) for the World Health Organization (WHO) and Bangladesh safe limits, respectively. Similarly, the probability of false alarms and false hopes for WHO (Bangladesh) safe limits were found to be 3·1% (4·8%) and 87·5% (19·7%), respectively. The depth at which the highest fraction of wells exceeding a given safe limit occurred could still be inferred correctly by FK measurements. A simple bias adjustment procedure on FK As data did not result in a more accurate characterization of depth distribution of As. This indicated that simple error statistics are inadequate for advancing the utility of FKs; rather, an understanding of the complex and multidimensional error structure is required. Regional anisotropy in the spatial dependence of As for the northwest was found to be stronger than the southwest. The correlation length for As concentration in the east–west direction of northwest Bangladesh (i.e. across major river floodplains) was found to be almost twice (158·80 km) that of the north–south direction (along the major axis of Pleistocene deposits) (78·21 km). For the southwest region, the ratio of east–west to north–south correlation lengths ranged from 1·40 to 1·51. For the northwest region, because it is well known to have the lowest concentrations of As countrywide, knowledge of this anisotropy appears to suggest the need for drilling twice as many remediation deep wells in the proximity of an unsafe shallow well in the north–south direction than in the east–west direction. Findings from this study are potentially useful in setting priority areas for emergency testing, distributing remediation resources equitably and formulating a regional water resources strategy for western Bangladesh. Copyright © 2005 John Wiley & Sons, Ltd.
Spatiotemporal dynamics of evapotranspiration at the Glacial Ridge prairie restoration in northwestern Minnesota
Authors: Melesse Assefa M. , Oberg Jason , Nangia Vijay , Beeri Ofer , Baumgartner David
Published: December 2005

Among the various indicators of success in wetland restoration, hydrology is the most important and relatively easy to monitor. Evapotranspiration (ET) was used to assess the ecohydrologic changes at the Glacial Ridge prairie restoration site in northwestern Minnesota. Twelve Landsat images from 2000–03 for the months of June, July and August were used to study the spatial ET changes. Spatial monthly and seasonal ET were estimated using a surface energy budget technique from Landsat images. Five sub‐basins within the study area were delineated to represent the different conditions of the wetlands. Their spatial and temporal ET responses to the restoration activities (native species planting, burning and ditch closures) were studied. Spatial statistics showing mean and standard deviation of monthly ET were computed. Comparisons were made between these watersheds and the preserved sub‐watershed of the study area. The average annual ET increases for the five sub‐basins were in the range of 9% (2002–03) to 25% (2001–02). Over the study period, ET increased by nearly 50%. After considering the effect of variations in precipitation, wind speed and solar radiation on the resulting ET, the results show that ET increased in recent years as result of the restoration activities. Copyright © 2005 John Wiley & Sons, Ltd.
Response of surface water chemistry to reduced levels of acid precipitation: comparison of trends in two regions of New York, USA
Authors: Burns Douglas A. , McHale Michael R. , Driscoll Charles T. , Roy Karen M.
Published: December 2005

In light of recent reductions in sulphur (S) and nitrogen (N) emissions mandated by Title IV of the Clean Air Act Amendments of 1990, temporal trends and trend coherence in precipitation (1984–2001 and 1992–2001) and surface water chemistry (1992–2001) were determined in two of the most acid‐sensitive regions of North America, i.e. the Catskill and Adirondack Mountains of New York. Precipitation chemistry data from six sites located near these regions showed decreasing sulphate (SO42−), nitrate (NO3−), and base cation (CB) concentrations and increasing pH during 1984–2001, but few significant trends during 1992–2001. Data from five Catskill streams and 12 Adirondack lakes showed decreasing trends in SO42− concentrations at all sites, and decreasing trends in NO3−, CB, and H+ concentrations and increasing trends in dissolved organic carbon at most sites. In contrast, acid‐neutralizing capacity (ANC) increased significantly at only about half the Adirondack lakes and in one of the Catskill streams. Flow correction prior to trend analysis did not change any trend directions and had little effect on SO42− trends, but it caused several significant non‐flow‐corrected trends in NO3− and ANC to become non‐significant, suggesting that trend results for flow‐sensitive constituents are affected by flow‐related climate variation. SO42− concentrations showed high temporal coherence in precipitation, surface waters, and in precipitation–surface water comparisons, reflecting a strong link between S emissions, precipitation SO42− concentrations, and the processes that affect S cycling within these regions. NO3− and H+ concentrations and ANC generally showed weak coherence, especially in surface waters and in precipitation–surface water comparisons, indicating that variation in local‐scale processes driven by factors such as climate are affecting trends in acid–base chemistry in these two regions. Copyright © 2005 John Wiley & Sons, Ltd.
Rainfall interception by an isolated evergreen oak tree in a Mediterranean savannah
Authors: David T. S. , Gash J. H. C. , Valente F. , Pereira J. S. , Ferreira M. I. , David J. S.
Published: December 2005

Redistribution of ground‐level rainfall and interception loss by an isolated Quercus ilex tree were measured over 2 years in a Mediterranean oak savannah. Stemflow, meteorological variables and sap flow were also monitored. Rainfall at ground level was measured by a set of rain‐gauges located in a radial layout centred on the tree trunk and extending beyond the crown limits. Interception loss was computed as the difference between the volume of rainwater that would reach the ground in the absence of the tree and the volume of water that actually fell on the ground sampling area (stemflow included). This procedure provided correct interception loss estimates, irrespective of rainfall inclination. Results have shown a clear non‐random spatial distribution of ground‐level rainfall, with rainwater concentrations upwind beneath the crown and rain‐shadows downwind. Interception loss amounted to 22% of gross rainfall, per unit of crown‐projected area. Stand interception loss, per unit of ground area, was only 8% of gross rainfall and 28% of tree evapotranspiration. These values reflect the low crown cover fraction of the stand (0·39) and the specific features of the Mediterranean rainfall regime (predominantly with few large storms). Nevertheless, it still is an important component of the water balance of these Mediterranean ecosystems. Copyright © 2005 John Wiley & Sons, Ltd.