bluuebunny/crossref_metadata_2025 huggingface dataset:
Bilateral adrenal hemorrhage associated with heparin induced thrombocytopenia
Authors: Kurtz Leon E. , Yang Sarah
Published: February 2007

Heparin induced thrombocytopenia (HIT) is associated with serious and sometimes devastating thrombotic events. We report a case of bilateral adrenal hemorrhage (BAH) associated with HIT after prophylactic use of low molecular weight heparin. The vague presenting symptoms of acute adrenal insufficiency offers a diagnostic challenge, which if delayed may be life threatening. A high index of suspicion for adrenal hemorrhage is required in patients receiving any form of heparin therapy presenting with new onset thrombocytopenia, abdominal pain, and fevers. Am. J. Hematol., 2007. © 2007 Wiley‐Liss, Inc.
Crunoecia irrorata (Curtis) (Trichoptera: Lepidostomatidae) and conservation of boreal springs: indications of clustering of red‐listed species
Authors: Ilmonen Jari
Published: January 2007

Crunoecia irrorata is widely dispersed across Europe, but rare and red‐listed in Finland. Its geographical range comprises most of the southern boreal zone in Fennoscandia. The species is confined to springs in the north, but occurs also in lower reaches of headwater streams in central and western Europe. It becomes more rare and less abundant towards the limits of its range across Europe, showing diffusive rarity. Glacial history and climate limit the distribution of the species in the north.

The most important habitat characteristic for C. irrorata in Finland was the total area of helocrene habitats. Its occurrence was positively related to taxon richness of benthic macroinvertebrates, but not bryophytes. Co‐occurrence of C. irrorata with other red‐listed spring‐dependent taxa was observed, indicating high conservation value of the springs occupied.

Crunoecia irrorata occurred frequently in moderately disturbed springs, indicating tolerance to human disturbance around springs. However, the effect of the disturbance on population size is not known. Forestry and water and gravel extraction are potential threats to C. irrorata, and only a few of its populations are strictly protected. Therefore, populations of C. irrorata in the boreal zone should be conserved and monitored to ensure the species' survival at the northern limits of its range.

Copyright © 2007 John Wiley & Sons, Ltd.
Early morphogenesis of the sinuatrial region of the chick heart: A contribution to the understanding of the pathogenesis of direct pulmonary venous connections to the right atrium and atrial septal defects in hearts with right isomerism of the atrial appendages
Authors: Männer Jörg , Merkel Nico
Published: February 2007

The morphogenesis of the sinuatrial region of embryonic hearts is still not well understood. Current matters of dispute are the topogenesis of the future pulmonary vein orifice and the topogenesis of the primary atrial septum. We analyzed the development of the sinuatrial region in chick embryos ranging from Hamburger and Hamilton (HH) stage 14 to 25. Our study disclosed three features of sinuatrial development. First, the primitive atrium of the HH stage 16 chick embryo heart has a separate inflow component. This inflow component takes up the mouth of the confluence of the systemic veins (sinus venosus) as well as the future mouth of the common pulmonary vein (pulmonary pit). The left portion of the atrial inflow component becomes incorporated into the left atrium and its right portion becomes incorporated into the right atrium. Rightward growth of the sinuatrial fold separates the sinus venosus from the left atrium. Second, the pulmonary pit originally forms as a bilaterally paired structure. Its left and right portions are connected to the left and right portions of the atrial inflow component, respectively. Normally, only the left portion of the pulmonary pit deepens to form the common pulmonary vein orifice, whereas the right portion disappears. Third, the primary atrial septum of the chick heart is not formed at the original midline of the embryonic heart, but is formed to the left of the original midline. This finding is in accord with molecular data suggesting that the primary atrial septum derives from the left heart‐forming field. Our findings shed new light on the pathogenesis of direct pulmonary venous connections to the right atrium and atrial septal defects in hearts with right isomerism of the atrial appendages. Anat Rec 290:168–180, 2007. © 2007 Wiley‐Liss, Inc.
Striated muscle and nerve fascicle distribution in the female raturethral sphincter
Authors: Kim Ronald J. , Kerns James M. , Liu Shirley , Nagel Ted , Zaszczurynski Paul , Lin Dan Li , Damaser Margot S.
Published: February 2007

The anatomical basis for urinary continence depends on a thorough understanding of the tissues in the urethra. The objective of this study was to evaluate the morphology and neuroanatomy of urethral striated muscle, called the rhabdosphincter or external urethral sphincter, in normal female rats. Urethras from 12 female rats were dissected from the bladder, fixed, embedded in paraffin or epon, and sectioned every 1 mm. Striated muscle content was taken as the ratio of the striated muscle area to net urethral area. Nerve fascicles containing myelinated axons near the rhabdosphincter were counted and mapped. Both striated muscle content and number of nerve fascicles peak in the proximal third of the urethra, with a secondary peak at the distal end of the urethra. This secondary peak may correspond to an analog of the combined compressor urethrae/urethrovaginal sphincter located in the distal urethra in human. The rhabdosphincter has a variable distribution along the length of the urethra. In the middle and distal thirds of the urethra, the dorsal striated muscle fibers between the urethra and vagina become more sparse. The majority of nerve fascicles are contained in the lateral quadrants of the urethra, similar to the lateral distribution of somatic nerves in humans. In conclusion, this study demonstrates the normal distribution of the striated musculature and neuroanatomy in the urethra, with similarities to the human. It thus supports and extends the usefulness of the rat as an experimental model for studying urinary incontinence. Anat Rec 290:145–154, 2007. © 2007 Wiley‐Liss, Inc.
An Adaptive Single‐step FDR Procedure with Applications to DNA Microarray Analysis
Authors: Iyer Vishwanath , Sarkar Sanat
Published: February 2007

The use of multiple hypothesis testing procedures has been receiving a lot of attention recently by statisticians in DNA microarray analysis. The traditional FWER controlling procedures are not very useful in this situation since the experiments are exploratory by nature and researchers are more interested in controlling the rate of false positives rather than controlling the probability of making a single erroneous decision. This has led to increased use of FDR (False Discovery Rate) controlling procedures. Genovese and Wasserman proposed a single‐step FDR procedure that is an asymptotic approximation to the original Benjamini and Hochberg stepwise procedure. In this paper, we modify the Genovese‐Wasserman procedure to force the FDR control closer to the level alpha in the independence setting. Assuming that the data comes from a mixture of two normals, we also propose to make this procedure adaptive by first estimating the parameters using the EM algorithm and then using these estimated parameters into the above modification of the Genovese‐Wasserman procedure. We compare this procedure with the original Benjamini‐Hochberg and the SAM thresholding procedures. The FDR control and other properties of this adaptive procedure are verified numerically. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An efficient domain‐decomposition pseudo‐spectral method for solving elliptic differential equations
Authors: Mai‐Duy N. , Tran‐Cong T.
Published: February 2007

In this paper, a new numerical scheme based on non‐overlapping domain decompositions and integrated Chebyshev approximations for solving elliptic differential equations (DEs) is presented. The distinguishing feature of the present scheme is that it achieves a Cp continuous solution across the interfaces (p is the order of the DE). Several test problems are employed to verify the method. The obtained results indicate that the achievement of higher‐order smoothness leads to a significant improvement in accuracy. Copyright © 2007 John Wiley & Sons, Ltd.
Alternating Spin Chains: Controlled Assembly from Bimetallic Building Blocks and QMC Simulation of Spin Correlation
Authors: Demeshko Serhiy , Leibeling Guido , Dechert Sebastian , Fuchs Sebastian , Pruschke Thomas , Meyer Franc
Published: February 2007

By using the compartmental dinucleating pyrazolate ligand HL, dinickel(II) complexes [LNi2(μ‐N3)(acetone)2]X2 (1: X=ClO4; 2: X=BPh4) and tetranickel(II) complex [{LNi2(μ‐N3)(MeOH)}2](ClO4)4 (3) have been prepared and structurally characterized. Complexes 1 and 2 differ in the torsion along the bridging μ‐1,3‐azide moiety, while the azido ligands in 3 adopt an unusual μ‐1,1,3 bridging mode to connect the two subunits. All three complexes show overall antiferromagnetic coupling and an S=0 ground state, but the torsion along the azide moiety is a determining factor for the coupling strength. Compounds 1 and 2 serve as preorganized building blocks for the controlled synthesis of alternating 1D polymeric structures 4–6 by replacement of their labile acetone ligands by additional azido ligands. Due to the modular synthetic approach, 4–6 can be described as Heisenberg antiferromagnetic systems with inherent bond alternation (HABA), whereby the organic ligand framework ensures that the individual nickel/azido chains are well isolated in the crystal lattice. Like their precursors, 4–6 are mainly distinguished by torsion along the μ‐1,3‐azido bridges, both within and between the bimetallic constituents. Magnetic measurements confirm an overall S=0 ground state for 4–6, and coupling parameters have been deduced from quantum Monte Carlo simulations. The two J values for the alternating 1D chains can be clearly assigned on the basis of the magnetostructural correlations established for the bimetallic building blocks. The alternation ratio γ=J2J${{{- 1\hfill \atop 1\hfill}}}$ places the three new systems in the HABA regime for a singlet‐dimer ground state.
Properties of AgGa1‐xInxSe2 single crystals grown by Bridgman method
Authors: Huang Y. , Zhao B. J. , Zhu S. F. , Zhu W. L. , Xu C. F. , Wan S. Q. , He Z. Y.
Published: February 2007

High‐pure and single‐phase AgGa1‐xInxSe2 (x=0.2) polycrystalline was synthesized by the mechanical and temperature oscillation method. Adopting the modified Bridgman method an integral AgGa1‐xInxSe2 single crystal with diameter of 14 mm and length of 35 mm has been obtained at the rate of 6 mm/day. It was found that there is a new cleavage face which was (101), and observed the four order X‐ray spectrum of the {101} faces. By the method of DSC analysis the melting and freezing points of the AgGa1‐xInxSe2 (x=0.2) single crystal were about 828°C and 790°C. The transmission spectra of the AgGa1‐xInxSe2 (x=0.2) sample of 5×6×2 mm3 were obtained by means of UV and IR spectrophotometer. The limiting frequency was 774.316nm and the band gap was 1.6eV. It can be found in the infrared spectrum that the infrared transmission was above 60% from 4000cm‐1 to 600cm‐1. The value of α in 5.3µm and 10.6µm were 0.022cm‐1 and 0.1cm‐1 respectively. All results showed that the crystal was of good quality. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heat treatment induced structural and optical properties of rf magnetron sputtered tantalum oxide films
Authors: Jagadeesh Chandra S. V. , Mohan Rao G. , Uthanna S.
Published: February 2007

Rf magnetron sputtering technique was employed for preparation of tantalum oxide films on quartz and crystalline silicon (111) substrates held at room temperature by sputtering of tantalum in an oxygen partial pressure of 1x10‐4 mbar. The films were annealed in air for an hour in the temperature range 573 – 993 K. The effect of annealing on the chemical binding configuration, structure and optical absorption of tantalum oxide films was systematically studied. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reliability of confocal microscopy spectral imaging systems: Use of multispectral beads
Authors: Zucker Robert M. , Rigby Paul , Clements Ian , Salmon Wendy , Chua Michael
Published: February 2007

Background:

There is a need for a standardized, impartial calibration, and validation protocol on confocal spectral imaging (CSI) microscope systems. To achieve this goal, it is necessary to have testing tools to provide a reproducible way to evaluate instrument performance.

Methods:

We evaluated fluorescent spectral beads (FocalCheck™) from Molecular Probes/Invitrogen that consist of four pairs with emissions between 500 and 725 nm and a europium macrocycle quantum dye bead. These bead tools compliment our previously published protocol for testing spectral imaging systems that used an inexpensive multi‐ion discharge lamp (MIDL) that contains Hg+, Ar+, and inorganic fluorophores that emits distinct, stable spectral features.

Results:

We acquired the spectra of the FocalCheck™ beads on a Zeiss 510 Meta, a Leica TCS‐SP1, a Leica SP2 AOBS, an Olympus FV 1000, and a Nikon C1Si confocal systems and a PARISS microscopic spectral system and of the europium beads on the Leica TCS‐SP1 and PARISS spectral imaging systems. A lack of performance with some equipment between 650 and 750 nm was identified using the far red pair of the FocalCheck™ beads. The position of the slider in front of PMT 2 that reflects light into PMT 1 and PMT 3 affected the measurement of all bead intensities. Unmixing algorithms were used to separate beads with different fluorochromes and separate two fluorochromes on the same bead.

Conclusions:

The FocalCheck™ multi‐spectral beads yielded similar profiles on four CSI systems and a PARISS spectral system. The utilization of the spectral FocalCheck™ beads is helpful to evaluate proper spectral performance, especially in the far red region. Europium beads provide a very narrow spectrum that can help to identify machines that have spectral problems. The dyes located on individual beads or mixed together in ring‐core configuration can be used as test particles to demonstrate spectral unmixing with various algorithms. Published 2007 Wiley‐Liss, Inc.
The vitamin D receptor gene FokI polymorphism: Functional impact on the immune system
Authors: van Etten Evelyne , Verlinden Lieve , Giulietti Annapaula , Ramos‐Lopez Elizabeth , Branisteanu Dumitru D. , Ferreira Gabriela B. , Overbergh Lut , Verstuyf Annemieke , Bouillon Roger , Roep Bart O. , Badenhoop Klaus , Mathieu Chantal
Published: February 2007

1α,25‐Dihydroxyvitamin D3 (1,25(OH)2D3) has important effects on the growth and function of multiple cell types. These pleiotropic effects of 1,25(OH)2D3 are mediated through binding to the vitamin D receptor (VDR). Several polymorphisms of the human VDR gene have been identified, with the FokI polymorphism resulting in VDR proteins with different structures, a long f‐VDR or a shorter F‐VDR. The aim of this study was to investigate the functional consequences of the FokI polymorphism in immune cells. In transfection experiments, the presence of the shorter F‐VDR resulted in higher NF‐κB‐ and NFAT‐driven transcription as well as higher IL‐12p40 promoter‐driven transcription. Marginal differences were observed for AP‐1‐driven transcription, and no differential effects were observed for transactivation of a classical vitamin D‐responsive element. Concordantly, in human monocytes and dendritic cells with a homozygous short FF VDR genotype, expression of IL‐12 (mRNA and protein) was higher than in cells with a long ff VDR genotype. Additionally, lymphocytes with a short FF VDR genotype proliferated more strongly in response to phytohemagglutinin. Together, these data provide the first evidence that the VDR FokI polymorphism affects immune cell behavior, with a more active immune system for the short F‐VDR, thus possibly playing a role in immune‐mediated diseases.
β‐Selection: Abundance of TCRβ–/γδ– CD44–CD25– (DN4) cells in the foetal thymus
Authors: Hager‐Theodorides Ariadne L. , Rowbotham Nicola J. , Outram Susan V. , Dessens Johannes T. , Crompton Tessa
Published: February 2007

Expression of TCRβ and pre‐TCR signalling are essential for differentiation of CD4–CD8– double negative (DN) thymocytes to the CD4+CD8+ double‐positive (DP) stage. Thymocyte development in adult Rag1, Rag2 or TCRβδ‐deficient mice is arrested at the DN3 stage leading to the assumption that pre‐TCR signalling and β‐selection occur at, and are obligatory for, the transition from DN3 to DN4. We show that the majority of DN3 and DN4 cells that differentiate during early embryogenesis in wild‐type mice do not express intracellular (ic) TCRβ/γδ. These foetal icTCRβ−/γδ− DN4 cells were T lineage as determined by expression of Thy1 and icCD3 and TCRβ DJ rearrangement. In addition, in the foetal Rag1–/– thymus, a normal percentage of DN4 cells were present. In wild‐type mice after hydrocortisone‐induced synchronisation of differentiation, the majority of DN4 cells that first emerged did not express icTCRβ/γδ, showing that adult thymocytes can also differentiate to the DN4 stage independently of pre‐TCR signalling. Pre‐TCR signalling induced expansion in the DN4 population, but lack of TCRβ/γδ expression did not immediately induce apoptosis. Our data demonstrate in vivo differentiation from DN3 to DN4 cell in the absence of TCRβ/γδ expression in the foetal thymus, and after hydrocortisone treatment of adult mice.
Detection of bis(sulfosuccinimidyl) suberate binding in electrophoresis: Determination of membrane sidedness of proteins
Authors: Till Olaf , Schmidt Martin , Linss Werner , Baumann Eckehard
Published: February 2007

The applicability of the membrane‐impermeant protein cross‐linker bis(sulfosuccinimidyl) suberate (BS3) to the determination of membrane sidedness of proteins was tested in 3T3‐L1 cells and in erythrocytes. Binding of BS3 to proteins was apparent in electrophoresis. In three proteins of 3T3‐L1 cells, protein kinase‐Cϵ, protein kinase‐Cζ, and glyceraldehyde‐3‐phosphate dehydrogenase, BS3 action was detectable in SDS‐PAGE with immunoblotting. This enabled confirmation of the well‐known intracellular localization of these proteins. In cathepsin E of erythrocytes, a mobility increase in nondenaturing PAGE was the most prominent effect of BS3 treatment. A mechanism for the increase in mobility due to BS3 binding is suggested. Cathepsin E was found to be located at the intracellular side of the membrane, in accordance with existing evidence.
Dynamic coating using methylcellulose and polysorbate 20 for nondenaturing electrophoresis of proteins on plastic microchips
Authors: Mohamadi Mohamad Reza , Mahmoudian Laili , Kaji Noritada , Tokeshi Manabu , Baba Yoshinobu
Published: February 2007

A dynamic coating using methylcellulose (MC) and a nonionic detergent (polysorbate 20) was developed, which controlled protein adsorption onto the surface of microchannels on a microchip made of poly(methyl methacrylate) (PMMA). Optimum concentration of polysorbate 20 in combination with the range of MC concentrations controlled the protein adsorption onto the microchannel surface, and increased the solubility of the protein samples while facilitating the injection of high concentrations of MC solutions into the microchannels. Higher concentrations of nonionic detergent increased the EOF mobility as opposed to the electrophoretic mobility and caused the electrophoresis to fail. Nondenaturing microchip electrophoresis of protein samples with molecular masses ranging from 20 to 100 kDa were completed in 100 s. Also, successful separation of a BSA sample and its complex with anti‐BSA mAb (˜220 kDa) was achieved on a PMMA microchip. The separation exhibited high reproducibility in both migration time (RSD = 1%) and peak area (RSD = 10–15%).
The Role of Particulate Organic Matter and Acetic Acid in the Removal of Phosphate in Anaerobic/Aerobic Activated Sludge Processes
Authors: Ubukata Y.
Published: February 2007

Acetic acid is thought to be an important substrate for the removal of phosphate in anaerobic/aerobic activated sludge (AS) processes. However, the acetic acid content in municipal sewage is low, and the main organic compounds in such sewage are particulate organic matters (POM) that are converted to endogenous substrates (E(ntrapped) POM, i.e., EPOM) in AS processes. Thus, the question arises whether it is really acetate or POM, which is important for the removal of phosphate in full‐scale AS plants. AS was harvested from a full‐scale anaerobic/aerobic AS plant. The amount of phosphate released after the addition of acetic acid depends on the AS conditions, particularly the influent sewage quality. However, the amount of phosphate released by EPOM was not affected by the AS conditions, and the amount of phosphate released per AS concentration and per unit of time was calculated to be about 0.86 mg PO4‐P/g MLSS/hour. When the AS concentration is 2.5 g/L and the mixed‐liquor retention time is 2 hours in the anaerobic zone, about 4 mg/L PO4‐P is released from EPOM. Under these conditions, phosphate in such sewage is removed by full‐scale AS plants without using acetic acid. In the case of carbon deficiency, the introduction of primary sludge to the anaerobic zone promoted the release of phosphate.
Environmental mesothelioma incidence, time since exposure to asbestos and level of exposure
Authors: Berry G.
Published: February 2007

In occupational follow‐up studies it has generally been found that the mesothelioma rate increases according to time since first exposure raised to a power of between 3 and 4. An alternative form includes a lag period, which is subtracted from time before raising to a power. In most studies only a small minority of the follow‐up has exceeded 40 years, and when the above relationships are extrapolated the incidence rate increases by a factor of up to 4 from 40 to 60 years. A modified model has been developed in which increase in mesothelioma rate with time since exposure is attenuated by a factor representing a decline in risk corresponding to elimination of asbestos from the lungs. The three models have been fitted to mesothelioma incidence observed in the group of former workers exposed to crocidolite asbestos in the Wittenoom mine and mill in Western Australia. The three models fitted the data equally well but diverged markedly when extrapolated to longer periods of follow‐up. With elimination of asbestos the incidence rate was relatively constant from 40 to 60 years, in contrast to the increasing rate without elimination. Estimates of the number of mesotheliomas associated with exposure to asbestos amongst residents and tourists to the town of Wittenoom have been made by extrapolating from the very high occupational exposures during 1943 to 1966 to the current low environmental exposures. For residents the estimated lifetime mesothelioma rate is at least three orders of magnitude less than that of the former workers, and for tourists the risk is another two or three orders of magnitude lower. The uncertainties in extrapolating in time beyond the current length of follow‐up and from high to low exposures means that estimates of lifetime mesotheliomas can only be given with a range of not less than 10‐fold.
Field evaluation of some sand transport models
Authors: Berg Neil H.
Published: February 2007

Fluorescent tracer procedures, originally developed for research on fluvial sediment movement, were used to monitor the movement of three commercially purchased sands in a natural dune environment. Results were compared with estimates of transport rates from three theoretical models. Estimates from models by Bagnold (1941) and Hsu (1971) were larger by as much as one order of magnitude than the rates observed in the tracer study. The model of A. A. Kadib (1965) provided closer correspondence to observed transport rates for medium sand (mean diam. 0.653 mm) but underestimated rates for coarse sand (mean diam. 0.992 mm).
Sorted stripes on sub‐Antarctic Kerguelen Island
Authors: Hall Kevin
Published: February 2007

Observations of sorted stripes at nine different localities on sub‐Antarctic Kerguelen Island are presented. The study sites range from 25‐600 m above sea level and are of varying aspect. It is found that there is a strong relationship between stripe orientation and the wind direction, to the extent that at one locality stripes were orientated across a slope. Stripe width was seen to increase with altitude and, in addition, the coarse stripe was dominant at lower elevations and the fine stripe at higher elevations. At one site a secondary set of stripes was observed to occur within the fine stripe of a primary larger set. On a trachyte plug there was evidence of lateral squeezing in the formation of the stripes. A number of minor observations pertaining to the possible mechanism of stripe formation are given.
A new technique for determining the surface level of salt marshes and other uncompacted sedimentary environments
Authors: Carr Alan P.
Published: February 2007

The method described involves the use of an electro‐optical distance measurer mounted on a theodolite. Observations are taken onto a series of acrylic reflectors, aligned at right angles to the line of sight, and slope distances and vertical and horizontal angles are recorded. From these data it is possible to obtain surface heights to an accuracy of ±0·5 cm at 200 m and to avoid any direct disturbance of the site under investigation.
The non‐independence of rainfall erosivity and soil erodibility
Authors: Morgan Christopher
Published: February 2007

Three high erosivity conditions (50 mm hr−1, 100 mm hr−1, and 200 mm hr−1) were generated in a laboratory using a rainfall simulator and coherent soil block samples from fourteen different soil erodibility conditions. The data acquired supports the theoretical contention that soil loss should not increase as a simple linear function of storm intensity. Rather, a variable relationship is caused by the rupturing of surface seals and the changing relative significance of splash, wash and rainwash processes. Slope angle appears to influence soil loss at the higher erosivity conditions of 100 mm hr−1 and 200 mm hr−1 on slopes that were either very steep (> 20°) or very shallow (< 3°), but on moderate slopes the relationship is unclear. Examination of the variation of soil loss with erosivity when soil loss for a specific high erosivity condition is known revealed that conversion and power factors are of doubtful value and little generality. A satisfactory predictive equation, a power curve, is seen to be of value only when comparing rainwash soil loss between the higher erosivity conditions. The relationship is most safely considered as soil and site specific. Where the influence of slope and soil erodibility are disregarded, a strong association between soil loss and rainfall intensity is found. That soil loss, and hence, soil erodibility varies non‐uniformly with erosivity is clear. The findings indicate caution is required when comparing conclusions drawn from studies based upon different erosivity conditions.
Wind ripples in an active drift sand area in the Netherlands: A preliminary report
Authors: Brugmans Freddy
Published: February 2007

Two types of wind ripples are distinguished in an active drift sand area near Hulshorst in The Veluwe (Central Netherlands). The common type has amplitudes of about 0·5 cm and wavelengths of some 11 cm, the atypical ripple has amplitudes of about 1 cm and wavelengths of some 16 cm. In both cases, the sand grains in the crests are coarser than those in the troughs. However, the coarseness of the grains in the crests of the higher ripples is much more pronounced than that of the lower. It is tentatively suggested that wind ripples are initiated by a regular downwind alternation in the impact energy of the descending grains in saltation, possibly due to fixed gravity waves in the sheared flows of air with grains which have strong density gradients with height.
(Re) deposition of loess in southern Limbourg, the Netherlands 3. Field evidence for conditions of deposition of the middle and upper silt loam complexes, and landscape evolution at Nagelbeek
Authors: Vreeken W. J.
Published: February 2007

This paper is about conditions and processes during the accumulation of the Upper Pleniglacial Middle and Upper Silt Loam complexes at Nagelbeek, Limbourg, a Weichselian stratigraphical type locality. The complexes correlate with Hesbayan and Brabantian loesses in Belgium, formed between 28,000 and 12,400 yrs BP. They are characterized by sediment features (cracks, mass deformations, and cut‐and‐fill features) that are ascribed to a cryogenic regimen. The main Middle Silt Loam subunit contains contraction cracks deformed and further modified by masswasting. Intra‐Upper‐Pleniglacial pedogenic intervals are inferred from three greyish bands, from a truncated weathered zone surmounting the Middle Silt Loam, and from an aeolian‐cumulic palaeosol at the base of the Upper Silt Loam. Latter two zones and an intervening erosional unconformity were cryogenically reworked, less than 22,000 yrs BP, to form a complex stratigraphical marker‐zone: the ‘Horizon à Langues de Nagelbeek’. Morphological variants of the marker‐zone are described. The geomorphic evolution of the Nagelbeek upland, from Saalian to Holocene times, is summarized in unconformity maps and a time diagram.
Typology of segregated (armoured/paved) surfaces: Some comments
Authors: Gomez Basil
Published: February 2007

A review of the characteristics of segregated surfaces and consideration of the origins of the terms armoured and paved suggests that the two terms are interchangeable, and that neither term is specifically associated with a particular segregation process. The dichotomy between segregated surfaces which are formed in channels in which the entire range of bed material is mobile under the prevailing hydrologic regime, and segregated surfaces which are intrinsically stable, forms the basis of an elementary distinction between different types of segregated surface. It is suggested that the term stable armour or stable pavement be applied to those cases where the segregated surface is considered to be inactive under the prevailing hydrologic regime, and that the term unstable armour or unstable pavement be applied to cases where the segregated surface experiences periodic mobilization.
Threshold response of small streams to surface coal mining, bituminous coal fields, central Pennsylvania
Authors: Touysinhthiphonexay Kimball C. N. , Gardner Thomas W.
Published: February 2007

Stream response to surface coal mining and reclamation was studied in 29 small (0·13 to 5·72 km2) watersheds located in the bituminous coal fields of Central Pennsylvania. These basins, up to 82 per cent mined, were selected from 176 first‐order tributaries of Beech Creek with similar vegetation, soil, lithology, and basin characteristics. Measurements were made at 262 cross‐sections (an average of nine cross‐sections per stream) of channel cross‐section area, bankfull width, mean bankfull depth, dimensions of the largest moving blocks, stream slope, valley‐side slope, basin area, and mined area. Observed differences in channel morphology were related to differences in extent of mining by means of scatter plots, correlation, cluster analysis, and bivariate regression.

Stream response to increased peak discharge and channel shear stress produced by increased surface runoff from regraded mine spoil takes the form of enlarged channels and increases in the size of moving blocks. Large basin areas appear to dampen the effect of mining, resulting in limited channel enlargement with greater extent of mining. In contrast, where peak discharges and associated shear stresses exceed the combined erosional resistance of floodplain vegetation, colluvial blocks, and channel banks, streams adjust extensively to higher levels of mining, causing an abrupt increase in the size of transported blocks and eroded channels. In the first‐order basins studied, this stepped response occurs at approximately 0·45 km2 mined area and 50 per cent of the total basin area mined.

For streams that have exceeded both threshold levels, disequilibrium is demonstrated by a strong, positive correlation between local stream slope and basin area. Where both threshold levels of mining are exceeded, steep channel slopes reinforce the tendency of stream cross‐sections to increase with greater disturbance by mining, necessitating that these streams rapidly adjust their morphology in order to attain a new equilibrium which is compatible with the conditions imposed by mining and reclamation.
Twenty‐one years of German geomorphology
Authors: Bremer Hanna
Published: February 2007

In recent decades, German geomorphology has been mainly concerned with climatic and climato‐genetic geomorphology. The first is the study of processes, especially of process combinations in different climato‐morphological zones. The second is concerned with the way exogenic forces control the evolution of relief in a certain region. This study of relief generations differs fundamentally from denudation chronology. Certain principles developed as knowledge of these fields has grown, such as the variability of rock resistance with climate and discontinuity of processes in both space and time, are considered. In recent years new trends, based mainly on climatic geomorphology, have been towards greater specialization in fields such as quantitative geomorphology, geomorphological mapping, and laboratory analysis of regolith and soil samples.
The micromorphology of quaternary river terrace deposits in the Kennet Valley, Berkshire, England
Authors: Chartres C. J.
Published: February 2007

Three groups of micromorphological features are recognized in the river terrace deposits of the Kennet Valley. These are orthic pedological features, orthic pedological features disrupted by cryoturbation, and transport‐inherited features. Fluvial and solifluction processes account for the presence of the transport‐inherited features. Used in conjunction with sedimentological and geomorphological investigations the distribution, composition, size, shape, and relative proportions of micromorphological features are helpful in separating pedogenically‐altered materials from undisturbed sediments, and in recognizing the occurrence of more than one phase of soil development.
Environmental reconstructions of a late devensian terrace sequence. Some preliminary findings
Authors: Dawson Martin
Published: February 2007

Facies analysis of Severn Main terrace sediments at Eardington, Shropshire is instructive in determining aspects of the sedimentary environment at a ‘proximal’ location in the terrace. Evaluation of the structural and directional properties of the gravels indicates that the terrace is a composite feature comprising two units. The lower unit is notable for the widespread occurrence of large sandy facies, a near absence of massive gravel facies, and the presence of large, locally derived, lithoclasts in excess of 1 m in diameter. Facies associations observed indicate the existence of in‐channel bars and large channels with bedforms at the dune‐plane bed transition. The directional properties of the unit indicate flows parallel to the main valley axis and although the unit is unlike previously reported examples it is interpreted as being the product of a proximal low sinuosity environment. The upper unit is composed mainly of multistorey, coarse, massive gravel units with limited interbedded sand facies. Fabric analysis indicates progradation of the unit from the west. The facies sequence is similar to those encompassed by facies models proposed for proximal alluvial fan deposits and therefore, on structural and directional grounds, the upper unit is interpreted as an alluvial fan deposit which prograded into the main Severn valley from the adjacent Mor Brook tributary. The implications of the composite nature of the terrace at this point are considered both in terms of terrace correlation and palaeohyrological estimation.
Comparison of taxon calibrations, modern analogue techniques, and forest‐stand simulation models for the quantitative reconstruction of past vegetation
Authors: Delcourt Hazel R. , Delcourt Paul A.
Published: February 2007

We compared results of three quantitative methods for reconstructing past vegetation, including (1) calibrations of per cent dominance vs. per cent pollen for individual tree taxa; (2) coefficients of dissimilarity between fossil and modern pollen assemblages; and (3) simulation modelling of long‐term forest succession. For calibration, we used 1684 modern pollen samples and 1742 forest‐inventory summaries from eastern North America. We applied the calibrations at 1 000‐year intervals to the 19000‐year pollen record from Anderson Pond, Tennessee. Dominance values reconstructed using taxon calibrations typically paralleled the changes in percentages of arboreal pollen. Dissimilarity values between fossil and modern pollen assemblages were lowest from 19 000 yr BP to 15 000 yr BP and from 9 000 yr BP to the present, indicating good modern analogues for both full‐glacial and Holocene time periods. During times of good analogue, forest composition estimated from forest inventories at the locations of best pollen analogues was similar to that reconstructed using taxon calibrations. Relatively poor modern analogues exist for late glacial and early Holocene pollen spectra from Anderson Pond. During times of poor analogues, forest composition reconstructed from taxon calibrations differed from that derived from analogue methods. FORET‐model simulations of forest‐stand biomass differed markedly from palaeovegetation estimates made from the other two methods. This is primarily because the FORET model is scaled to forest succession on 1/12‐ha forest plots rather than forest dynamics integrated over a broad landscape mosaic. Because they are based upon fundamental relationships of pollen production and dispersal, taxon calibrations provide the best available means for reconstructing forest history both during times of good and of poor analogues.
Deformation of laminated silt loam due to repeated freezing and thawing cycles
Authors: Coutard J. P. , Mücher H. J.
Published: February 2007

The effect of repeated freezing and thawing cycles on an experimentally‐produced laminated silt loam was studied with the purpose of obtaining more insight into the genesis of macro‐ and microstructures observed in the loessic formations of Northwestern Europe.

The laminated silt loam was subsequently subjected to 18 cycles of alternate freezing and thawing. The minimum temperature recorded after 11 days of frost was − 7°C at a depth of 5 cm and − 4°C at 29 cm. The underlying sediments, compact loam (except its upper part) and sand, always remained unfrozen. The experiment reproduced a seasonal superficially frozen ground.

New structures and microfabrics in the form of vesicles, platy structures, shear planes, and micro‐undulations were created by ice segregation and thawing, mechanical stress and subsequent frost‐creep. The impact of the freezing and thawing cycles is very strong, all the laminae being deformed or broken. Judging by the abundance and the diversity of the structures created, freezing is a more important process than simple drying without frost.

As is evidenced by the range in temperature chosen for the experiment and the low number of cycles, these structures do not necessarily require severe climatic conditions to develop, unlike frost cracks or ice wedge casts. They could develop in winter conditions similar to those present today in the French Southern Alps.
Estimating limiting age for pleistocene erosional surfaces in central Montana by uranium‐series dating of associated travertines
Authors: Szabo Barney J. , Lindsey David A.
Published: February 2007

Travertine deposits overlie the highest Number 2 surfaces in central Montana and clasts of travertine occur in gravels on lower Number 2 surfaces. Dating these travertine deposits may provide limits on the ages of surfaces that record intervals of extensive erosion during Pleistocene time. Analysis of three travertine samples from the southeast side of The Park yield an average uranium‐thorium age of 73 000 ±+M 7 000 years. Another sample from the west side of The Park is 320 000 (+ 160 000, − 70 000) years old. These results indicate that travertine deposits may have formed at several intervals. The surface beneath The Park travertine is older than about 320 000 years. Number 2 pediment gravels that contain travertine downslope from the oldest dated sample may be younger than about 320 000 years.
Seasonal changes in surface level of a salt marsh creek
Authors: Carr Alan P. , Blackley Michael W. L.
Published: February 2007

Nineteen surveys were carried out over a two‐year period to determine the surface height of a salt marsh creek located on the north side of the River Esk, Cumbria, England. An AGA 112 electromagnetic distance measurer mounted on a Wild TI theodolite was used in conjunction with acrylic reflectors to follow the form of the ground. The results showed that there were no significant net trends in surface level, although seasonal variations of the order of 2 cm occurred. Vegetated areas responded in similar fashion to bare surfaces. It is thought that the elevational changes were attributable to the swelling of clay particles during the winter months rather than the effects of erosion and accretion.
Downslope movement of in situ clasts on forested hillslopes, Virginia
Authors: Mills Hugh H
Published: February 2007

Downslope movements of 109 clasts ranging in intermediate diameter from 30 to 870 mm were monitored over a five‐year period on hillslopes in the Valley and Ridge province of southwest Virginia. Gradients ranged from 8° to 42°. Regression on slope tangent, depth of clast base below ground surface, clast size, and clast shape explained 70 per cent of clastmovement variance. A substantial part of the unexplained variance appears due to variation in substrate and slope aspect. Additional measurements made on two steep boulder streams showed extremely low rates.
Slope properties, slope processes and soil erosion risk in the tropical rain forest of Kalimantan Timur (Indonesian Borneo)
Authors: Besler Helga
Published: February 2007

The landforms of the study area at the margin of the Central Kalimantan Mountains are relatively young and covered by undisturbed primary rain forest receiving an annual rainfall of 4147 mm. The most important variables for slope processes and their interrelations were studied by simple means along slope profiles on a representative hill. Weathering and erosion appear to be in a dynamic equilibrium leading to parallel slope retreat. Measurable denudation occurred within a fortnight with rates of 10 to 22 mm, varying with litter cover and slope exposition. As the forest is planned for ‘limited production’, the soil‐erosion risk for changing conditions was estimated using the model by Morgan et al. (1982). Results from field work and from calculations alike show the enormous importance of a protective ground cover.
Dunes of the Gran Desierto Sand‐Sea, Sonora, Mexico
Authors: Lancaster N. , Greeley R. , Christensen P. R.
Published: February 2007

The Gran Desierto Sand‐Sea contains dunes of crescentic and star form in simple, compound, and complex varieties. The dunes have developed in bimodal to complex wind regimes of intermediate energy. Transitions from simple through compound to complex crescentic dunes are associated with regional changes in wind regimes. Growth of large star dunes takes place by merging of smaller crescentic and reversing dunes from southerly directions and reworking of sand by northerly and westerly winds. Although wind regimes appear to be the major control of dune morphology in this sand‐sea, there is a close correlation between the spacing of simple crescentic dunes and the grain size of the coarse 20th percentile.
Plate tectonics, palaeoenvironments and limestone geomorphology in West‐Central Britain
Authors: Douglas Ian
Published: February 2007

The variety of active, exhumed, and buried limestone landforms of northern England, North Wales, and the Isle of Man arises in part from the way in which Dinantian (Lower Carboniferous) sedimentation was affected by a tilt‐block basement structure evolved during the closure of the Iapetus Ocean suture to the north, and partly to subsequent plate tectonic movements associated with the closure of the proto‐Tethys ocean, the opening of the Atlantic Ocean and the Alpine orogeny. Landforms created during the Dinantian now form important exhumed and buried landscape features. The Permian half‐graben structures of the eastern Irish Sea‐Cheshire‐Worcester Basins account for many of the contrasts between the upland karsts of the Pennines and the lowland karsts of coastal areas.
Changing drainage patterns in a semi‐arid area and their effects on groundwater resources
Authors: Sutton Sally E.
Published: February 2007

The magnitude of groundwater resources is poorly correlated with surface catchment area in a group of wadi bottom alluvial aquifers in Northern Oman. It is suggested that this is due to progressive water gap captures across a limestone ridge.
Quantum theory and geography
Authors: Biggs Robin A.
Published: February 2007

The application of Newtonian physics to complex fluvial and atmospheric processes is suggested to be inadequate. In the 1970s a number of exciting cosmological theories were developed which formed the basis for models of the early expansion of the Universe. Since these models derive from Einstein's ten gravitational field equations (rather than Newton's single equation) they possess a deep subtlety and may well be of interest to geographers in the explanation of fundamental patterns.
Medium‐term effects of afforestation on sediment dynamics in a water supply catchment: A mineral magnetic interpretation of reservoir deposits in the macclesfield forest, N.W. England
Authors: Stott A. P.
Published: February 2007

Short term increases in stream sediment loads during pre‐afforestation ground preparation have often been followed by a return to low sediment loads. However, in the Macclesfield Forest in the southern Pennines, comparison of the magnetic characteristics of soils and downstream reservoir deposits suggest that significant changes in the processes of soil erosion occur later in the cycle of forest management at the time of canopy closure. A preliminary magnetic mixing model indicates that the proportion of reservoir sediments derived from the subsoil (below 0·3 m depth) has increased from 30 to 70 per cent between 1929 and 1981. Changes in hydraulic stresses subsequent to road construction and forest development, in association with unstable Pleistocene deposits, may provide an explanation for these events.
On the use of resistance envelopes to identify the controls on slope stability in the tropics
Authors: Anderson M. G. , Kemp M. J. , Shen J. M.
Published: February 2007

In tropical and sub‐tropical slopes, soil suction may in certain circumstances play a role in maintaining slope stability. Resistance envelope methods are outlined that provide a means of assessing the threshold soil water conditions for stability. In addition, this technique enables the likely failure depth to be identified. Application to slopes in St. Lucia, West Indies, show the accordance of resistance envelope predictions with stability analysis results. A methodology for the geomorphological investigation of stability processes in tropical slopes is proposed.
Suction‐controlled triaxial testing: Laboratory procedures in relation to resistance envelope methods
Authors: Anderson M. G. , Kemp M. J.
Published: February 2007

In certain tropical slopes it appears possible that soil suction may play a significant role in maintaining stability. This communication outlines a laboratory suction‐controlled triaxial test that can be undertaken to validate the threshold suction predicted by resistance envelope methods. It is shown that for two sites examined in St. Lucia, West Indies, the results from such a test confirm results obtained by use of resistance envelopes.