bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards a ligand targeted enzyme prodrug therapy: Single round panning of a β‐lactamase scaffold library on human cancer cells
Authors: Shukla Girja S. , Murray Christopher J. , Estabrook Melodie , Shen Guang‐Ping , Schellenberger Volker , Krag David N.
Published: February 2007

A novel β‐lactamase scaffold library in which the target‐binding moiety is built into the enzyme was generated using phage display technology. The binding element is composed of a fully randomized 8 amino acid loop inserted at position between Y34 and K37 on the outer surface of Enterobacter cloacae P99 cephalosporinase (β‐lactamase, E.C. 3.5.2.6) with all library members retaining catalytic activity. The frequency and diversity of amino acids distributions in peptide inserts from library clones were analyzed. The complexity of the randomized loop appears consistent with standards of other types of phage display library systems. The library was panned against SKBR3 human breast cancer cells in 1 round using rolling circle amplification of phage DNA to recover bound phage. Individual β‐lactamase clones, independent of phage, were rapidly assessed for their binding to SKBR3 cells using a simple high throughput screen based on cell‐bound β‐lactamase activity. SKBR3 cell‐binding β‐lactamase enzymes were also shown to bind specifically using an immunochemical method. Selected β‐lactamase clones were further studied for their protein expression, enzyme activity and binding to nontumor cell‐lines. Overall, the approach outlined here offers the opportunity of rapidly selecting targeted β‐lactamase ligands that may have a potential for their use in enzyme prodrug therapy with cephalosporin‐based prodrugs. It is expected that a similar approach will be useful in developing tumor‐targeting molecules of several other enzyme candidates of cancer prodrug therapy. © 2007 Wiley‐Liss, Inc.
Serum levels of C‐peptide, IGFBP‐1 and IGFBP‐2 and endometrial cancer risk; Results from the European prospective investigation into cancer and nutrition
Authors: Cust Anne E. , Allen Naomi E. , Rinaldi Sabina , Dossus Laure , Friedenreich Christine , Olsen Anja , Tjønneland Anne , Overvad Kim , Clavel‐Chapelon Françoise , Boutron‐Ruault Marie‐Christine , Linseisen Jakob , Chang‐Claude Jenny , Boeing Heiner , Schulz Mandy , Benetou Vassiliki , Trichopoulou Antonia , Trichopoulos Dimitrios , Palli Domenico , Berrino Franco , Tumino Rosario , Mattiello Amalia , Vineis Paolo , Quirós J. Ramón , Agudo Antonio , Sánchez Maria‐Jose , Larrañaga Nerea , Navarro Carmen , Ardanaz Eva , Bueno‐de‐Mesquita H. Bas , Peeters Petra H.M. , van Gils Carla H. , Bingham Sheila , Khaw Kay‐Tee , Key Tim , Slimani Nadia , Riboli Elio , Kaaks Rudolf
Published: February 2007

We conducted a case‐control study nested within the European Prospective Investigation into Cancer and Nutrition, to examine the associations between prediagnostic serum concentrations of C‐peptide, insulin‐like growth factor binding protein (IGFBP)‐1 and IGFBP‐2, and endometrial cancer risk. Among pre‐ and post‐menopausal women, who were not currently using exogenous hormones, 286 women developed incident endometrial cancer during an average 5.1 years follow‐up. Using risk set sampling, 555 matched control subjects were selected. In conditional logistic regression models adjusted for matching factors only, endometrial cancer risk increased with increasing serum levels of C‐peptide (relative risks (RR) for the top vs. bottom quartile = 2.13 [95% confidence interval (CI) 1.33–3.41], ptrend = 0.001, and decreasing serum levels of IGFBP‐2 (RR for the top vs. bottom quartile = 0.56 [95% CI 0.35–0.90], ptrend = 0.03, but was not significantly associated with IGFBP‐1 levels (RR for the top vs. bottom quartile = 0.76 [95% CI 0.47–1.21], ptrend = 0.25). In BMI‐adjusted models, only the C‐peptide association remained marginally statistically significant (RR for the top vs. bottom quartile = 1.56 [95% CI 0.94–2.57], ptrend = 0.05 for C‐peptide; 0.84 [95% CI 0.50–1.40], ptrend = 0.74 for IGFBP‐2; and 1.08 [95% CI 0.65–1.78], ptrend = 0.86 for IGFBP‐1 levels). These associations were stronger among nonfasting women (≤≤6 hr since last meal; 63% of subjects) but were not evident among fasting women, although the interactions were not statistically significant. The C‐peptide‐risk association was substantially attenuated after adjustment for free estradiol in postmenopausal women (RR for the top vs. bottom quartile = 1.28 [95% CI 0.67–2.45], ptrend = 0.42. Our results provide modest support to the hypothesis that hyperinsulinaemia is a risk factor for endometrial cancer. © 2007 Wiley‐Liss, Inc.
Water sorption and solubility of contemporary resin‐based filling materials
Authors: Janda Ralf , Roulet Jean‐François , Latta Mark , Rüttermann Stefan
Published: February 2007

Purpose: Evaluation of water sorption and solubility of contemporary resin‐based filling materials. Methods: Specimens of Herculite (HE), Point 4 (P4), TetricCeram (TC), Miris (MI), TetricCeram HB (HB), Solitaire 2 (SO), SureFil (SU), Definite (DE), Admira (AD), Dyract AP (DY), Compoglass F (CO), and TetricFlow (TF) were prepared according to ISO 4049. Water sorption and solubility were measured after water storage at 37°C for 7 days. Results: Water sorption was HE 14 μg mm−3, P4 17 μg mm−3, TC 12 μg mm−3, MI 13 μg mm−3, HB 9 μg mm−3, SO 18 μg mm−3, SU 9 μg mm−3, DE 14 μg mm−3, AD 27 μg mm−3, DY 19 μg mm−3, CO 23 μg mm−3, and TF 19 μg mm−3. Solubility was HE 3 μg mm−3, P4 3 μg mm−3, TC 1 μg mm−3, MI 0 μg mm−3, HB 0 μg mm−3, SO 3 μg mm−3, SU 0 μg mm−3, DE 1 μg mm−3, AD 2 μg mm−3, DY 4 μg mm−3, CO −2 μg mm−3, and TF 1 μg mm−3. Conclusion: All materials met the corresponding requirement in ISO 4049. Filler load negatively correlated with water sorption but not with solubility. There was an influence of the resin matrix, too. No significant differences were found between composites, ormocers, and compomers. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Materials characterization of explanted polypropylene hernia meshes
Authors: Costello C. R. , Bachman S. L. , Ramshaw B. J. , Grant S. A.
Published: February 2007

Hernia repair with prosthetic mesh significantly decreases the rate of recurrence compared with traditional, primary suture repair by reducing the tension on the edges of the wound. However, there are several complications associated with the use of mesh that may be due to the chronic inflammatory reaction to the mesh or a loss of compliance after degradation of the material. Mesh contraction and migration can also occur, sometimes resulting in a recurrent hernia. Based on the chemical structure of the polypropylene mesh material and the physiological conditions to which it is subjected, it is possible that oxidation is responsible for these changes in material properties. Oxidation would result in surface cracking, decreased melting temperature, loss of mass, and reduced compliance of the material. The objective of this study was to identify physiochemical changes in the surface and bulk properties of explanted polypropylene hernia meshes compared to pristine polypropylene mesh materials. Several characterization techniques were utilized, including scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and compliance testing. Overall, the results supported our hypothesis that oxidation is involved with the degradation of polypropylene hernia mesh materials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Antibacterial activity of silver‐doped silica glass microspheres prepared by a sol‐gel method
Authors: Masuda Noriaki , Kawashita Masakazu , Kokubo Tadashi
Published: February 2007

Various kinds of inorganic substances doped with silver ions have been developed as antibacterial materials, and some have already been commercialized. Previously, we successfully prepared colorless silica glass microspheres doped with silver ions in combination with aluminum ions by a sol‐gel method. However, the antibacterial activity of the microspheres was not maintained for long periods in an aqueous environment, since the silver ions were located only in a thin layer near the surface of the microspheres. In this study, silica glass microspheres in which silver ions are uniformly distributed were attempted to be prepared. A tetraethoxysilane ethanol solution was mixed with aqueous silver nitrate and aluminum nitrate solutions to be subjected to almost simultaneous hydrolysis and polycondensation. An ammonia solution was then added, to form microspheres. Monodispersed microspheres about 0.1 μm in diameter were obtained, which did not show coloring even after heat treatment at 600–1000°C, indicating that the silver in the microspheres took the form of Ag+ ions and not colloid, even after the heat treatments. Microspheres heat‐treated at temperatures ranging from 700 to 800°C showed much higher antibacterial activity than commercial antibacterial zeolites and maintained their high antibacterial activities for long periods in an aqueous environment. Polypropylene plates and films mixed with the microspheres heat‐treated at 800°C showed excellent antibacterial properties. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Do infections provoke exacerbations and relapses of thrombotic thrombocytopenic purpura?
Authors: Cserti Christine M. , Landaw Stephen , Uhl Lynne
Published: February 2007

Several case reports have suggested an association between infections and thrombotic thrombocytopenic purpura (TTP). In Case 1, a 37‐year‐old female presented with TTP 6 times over 7 years, requiring 242 therapeutic plasma exchanges (TPE), for a per‐course range of 4–57 TPE (median 48), and treatment durations of 4–241 days (median 71 days), largely on account of multiple exacerbations (range 0–3, median 3). Twelve of 17 (71%) of her presentations or exacerbations were associated with suspected infections, with confirmation in 9 episodes. These included pulmonary TB, CMV pneumonitis, mucocutaneous HSV, ventilator‐associated or urinary tract‐associated gram‐negative sepsis, central line‐associated staphylococcal bacteremia, and cellulitis. Except for TB, all infections occurred after splenectomy, which had been performed on day 33 of presentation 1. In Case 2, a 24‐year‐old female presented with TTP 3 times over 15 months. Her courses were managed with brief courses of TPE (5–11 treatments per course, median 5). Suppressed ADAMTS13 levels due to inhibitors were confirmed twice. Presentation 1 was antedated by atypical community acquired pneumonia. Presentation 3 (and possibly 2) followed prolonged, progressive, antibiotic‐refractory periodontal infections ultimately requiring exodontic surgery. Our cases add to a literature that suggests that infection may be associated with exacerbations or relapses of TTP in some patients. Our patients demonstrated repeated TTP exacerbations in association with different infectious agents. A better understanding of the possible relationship between infection and clinical expression of TTP might lead to improved treatment decisions for patients with this complex illness. J. Clin. Apheresis. 22:, 2007 © 2007 Wiley‐Liss, Inc.
Maintaining solvent accessible surface area under rotamer substitution for protein design
Authors: Leaver‐Fay Andrew , Butterfoss Glenn L. , Snoeyink Jack , Kuhlman Brian
Published: February 2007

Although quantities derived from solvent accessible surface areas (SASA) are useful in many applications in protein design and structural biology, the computational cost of accurate SASA calculation makes SASA‐based scores difficult to integrate into commonly used protein design methodologies. We demonstrate a method for maintaining accurate SASA during a Monte Carlo search of sequence and rotamer space for a fixed protein backbone. We extend the fast Le Grand and Merz algorithm (Le Grand and Merz, J Comput Chem, 14, 349), which discretizes the solvent accessible surface for each atom by placing dots on a sphere and combines Boolean masks to determine which dots are exposed. By replacing semigroup operations with group operations (from Boolean logic to counting dot coverage) we support SASA updates. Our algorithm takes time proportional to the number of atoms affected by rotamer substitution, rather than the number of atoms in the protein. For design simulations with a one hundred residue protein our approach is ∼145 times faster than performing a Le Grand and Merz SASA calculation from scratch following each rotamer substitution. To demonstrate practical effectiveness, we optimize a SASA‐based measure of protein packing in the complete redesign of a large set of proteins and protein–protein interfaces. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Calcium‐sensing receptor stimulates secretion of an interferon‐γ‐induced monokine (CXCL10) and monocyte chemoattractant protein‐3 in immortalized GnRH neurons
Authors: Bandyopadhyay Sanghamitra , Jeong Kyeong‐Hoon , Hansen Jacob Tfelt , Vassilev Peter M. , Brown Edward M. , Chattopadhyay Naibedya
Published: February 2007

Biology of GnRH neurons is critically dependent on extracellular Ca2+ (Ca2+o). We evaluated differences in gene expression patterns with low and high Ca2+o in an immortalized GnRH neuron line, GT1‐7 cells. Mouse global oligonucleotide microarray was used to evaluate transcriptional differences among the genes regulated by elevated Ca2+o. Our result identified two interferon‐γ (IFNγ)‐inducible chemokines, CXCL9 and CXCL10, and a beta chemokine, monocyte chemoattractant protein‐3 (MCP‐3/CCL7), being up‐regulated in GT1‐7 cells treated with high Ca2+o (3.0 mM) compared with low Ca2+o (0.5 mM). Up‐regulation of these mRNAs by elevated Ca2+o was confirmed by quantitative PCR. Elevated Ca2+o stimulated secretion of CXCL10 and MCP‐3 but not CXCL9 in GT1‐7 cells, and this effect was mediated by an extracellular calcium‐sensing receptor (CaR) as the dominant negative CaR attenuated secretion of CXCL10 and MCP‐3. CXCL10 and MCP‐3 were localized in mouse GnRH neurons in the preoptic hypothalamus. Suppression of K+ channels (BK channels) with 25 nM charybdotoxin inhibited high‐Ca2+o‐stimulated CXCL10 release. Accordingly, CaR activation by a specific CaR agonist, NPS‐467, resulted in the activation of a Ca2+‐activated K+ channel in these cells. CaR‐mediated MCP‐3 secretion involves the PI3 kinase pathway in GT1‐7 cells. MCP‐3 stimulated chemotaxis of astrocytes treated with transforming growth factor‐β (TGFβ). With TGFβ‐treated astrocytes, we next observed that conditioned medium from GT1‐7 cells treated with high Ca2+ promoted chemotaxis of astrocytes, and this effect was attenuated by a neutralizing antibody to MCP‐3. These results implicate CaR as an important regulator of GnRH neuron function in vivo by stimulating secretion of heretofore unsuspected cytokines, i.e., CXCL10 and MCP‐3. © 2007 Wiley‐Liss, Inc.
Xylanase production by Aspergillus versicolor
Authors: Carmona Eleonora Cano , Pizzirani‐Kleiner Aline A. , Monteiro Regina T. Rosim , Jorge João Atilio
Published: February 2007

The xylanolytic system of Aspergillus versicolor is controlled by induction and carbon catabolite repression. Carboxymethylcellulose and wheat bran were the best inducers of xylanolytic activity. When the fungus was grown for 5 days on VOGEL's liquid medium with wheat bran, the optimal pH and temperature for xylanase production were 6.5 and 30 °C, respectively. Optimal conditions for the xylanolytic activity assay were at pH 6.0 and 55 °C. The half‐life at 60 °C of the crude enzyme was 6.5 and 21 minutes, in the absence or presence of substrate, respectively.
Mycoflora of seeds and feeds from the Spanish market
Authors: Cantalejo M. J. , Carrasco J. M. , Hernández E.
Published: February 2007

Survey of infected seeds and feeds for species of Penicillium, Aspergillus, Fusarium, Rhizopus, Alternaria, Acremonium and yeasts were carried out on samples collected in 1991/92 and 1992/93 from two regions of Spain, one in northern Spain where the annual rainfall is over 900 mm and the other one in southeastern Spain where the annual rainfall is less than about 400 mm. The isolation frequency and genus of fungal contamination were determined in the 657 samples anayzed, and results were analyzed statistically to assess the effects of substrate and meteorological conditions on fungal proliferation.

Significant differences were found among the different fungi that contaminated the samples. Penicillium was the most frequently isolated genus in the analyzed samples (62.8% in total), and the predominant species were P. chrysogenum and P. viridicatum. Aspergillus, Fusarium, Rhizopus and yeasts contaminated the samples at an intermediate level (between 21% and 53% of the samples). There was only a statistically significant correlation between the climatic conditions and the fungal contamination caused by yeasts in the samples.
Effect of amino acids on the production and activities of cephalosporin C acylase and penicillin V acylase from Aeromonas species ACY 95
Authors: Dehpande Bhagwant S. , Ambedkar Sudha S. , Shewale Jaiprakash G.
Published: February 2007

Amino acids altered the production and activities of cephalosporin C acylase and penicillin V acylase from Aeromonas species ACY 95 to a varying degree. DL‐Tryptophan enhanced the cephalosporin C acylase formation by 222% while suppressed the penicillin V acylase formation by 68%.
Evaluation of the flocculent strain Zymomonas mobilis Z1‐81 for the production of sorbitol and gluconic acid
Authors: Wisbeck Elisabeth , Ninow Jorge , Jonas Rainer , Silveira Mauricio M.
Published: February 2007

The biological production of sorbitol and gluconic acid from glucose and fructose is normally performed with previously grown and concentrated Zymomonas mobilis suspensions, in reactions catalyzed by the enzymes glucose‐fructose oxidoreductase (GFOR) and glucono‐δ‐lactonase (GL). By using the flocculent strain Z. mobilis Z1‐81, mechanical methods for cell concentration are unnecessary. Flocculation of Z. mobilis Z1‐81 is seriously affected by both stirring and initial glucose concentration (S0). Under mild agitation conditions, with S0 = 100 g · 1−1, up to 76% of the final biomass was recovered by settling. At any impeller speed tested, similar specific GFOR/GL activities (8.4 to 9.5 U · g−1 cell) were measured. When S0 was increased to 144 and 210 g · 1−1, however, enzyme activities above 14 U · g−1 were found. Ideal pH and temperature values for GFOR/GL, in whole Z. mobilis Z1‐81 cells, are 6.4 and 39 °C, respectively. The Km and the theoretical Vmax are 250 g glucose · 1−1 and 26.6 g gluconic acid · g−1 cell · h−1. With the settled biomass, bioconversion of 300 g · 1−1 each of glucose and fructose led to gluconic acid and sorbitol yields between 91 and 92% of the theoretical maximum, with specific productivities of 1.09 and 1.00 g product · g−1 cell · h−1.
Replication of plasmids derived from P1, F, R1, R6K and RK2 replicons in amino acid‐starved Escherichia coli stringent and relaxed strains
Authors: Wróbel Borys , Węgrzyn Grzegorz
Published: February 2007

Replication of mini‐plasmids derived from bacteriophage P1 and naturally existing plasmids F, R1, R6K and RK2 in otherwise isogenic relA+ and relA− Escherichia coli strains during amino acid starvation and limitation was investigated. Since it was previously demonstrated that inhibition of DNA synthesis or amplification of plasmid DNA may depend on the nature of deprived amino acid, we starved bacteria for five different amino acids. We found differential replication of all these plasmids but RK2 (which did not replicate at all in amino acid‐starved bacteria) during the stringent and relaxed response. While in almost all cases plasmid DNA replication was inhibited during the stringent response irrespective of the nature of deprived amino acid, wild‐type or copy‐up mini‐P1, mini‐F and mini‐R1 plasmids replicated in relA− bacteria depending on the kind of starvation. R6K‐derived plasmids harbouring ori β and γ (but not those containing ori α, β and γ or only ori γ) were able to replicate in relA− bacteria starved for all tested amino acids. Possible explanations for the mechanisms of regulation of replication of plasmids derived from P1, F, R1, R6K and RK2 during amino acid starvation are discussed. Our results also indicate that, like in the case of some other replicons, appropriate amino acid starvation or limitation may be used as a method for efficient amplification of plasmids derived from P1, F, R1 and R6K.
Southern hemisphere cyclones and anticyclones: recent trends and links with decadal variability in the Pacific Ocean
Authors: Pezza Alexandre Bernardes , Simmonds Ian , Renwick James A.
Published: February 2007

The aim of this paper is to study the association between the extratropical Southern Hemisphere and the decadal variability in the Pacific Ocean (PO). We discuss a pattern of coherent large‐scale anomalies and trends in cyclone and anticyclone behaviour in light of the climate variability in the PO over the ERA40 reanalysis period (1957–2002). The two representative PO indices are the Pacific Decadal and Interdecadal Oscillations (PDO and IPO), and here the PDO is chosen owing to it being less associated with the southern oscillation index (SOI).

Composites of the indicators of the density and intensity of cyclones/anticyclones given by an automatic tracking scheme were calculated for the years when the PDOI was more than one standard deviation above or below its mean. Although the ERA40 is not free from noise and assimilation changes, the results show a large‐scale feature, which seems to be robust and agrees with earlier studies using different data sets.

The sea‐level pressure shows a strong annular structure related to the PDO, which is not seen for the SOI, with lower pressure around Antarctica during the positive phase and vice versa. More intense (and fewer) cyclones and anticyclones were observed during the positive PDO. This is less consistent for the SOI, particularly during the summer when a different PDO/SOI pattern arises at high latitudes. The trends project a pattern coincident with the positive PDO phase and seem to be linked with the main climate shift in the late seventies. Trends observed over the Tasman Sea are consistent with declining winter rainfall over southeastern Australia.

Most patterns are statistically significant and seem robust, but random changes in ENSO may play a part, to a certain degree, in modulating the results, and a physical mechanism of causality has not been demonstrated. Although global warming and related changes in the Southern Annular Mode (SAM) may also help explain the observed behaviour, the large‐scale response presented here provides a new insight and would be of considerable interest for further modelling studies. Copyright © 2007 Royal Meteorological Society
Age and origin of clayey silt ‚brickearth’︁ in west London, England
Authors: Gibbard Philip L. , Wintle Ann G. , Catt John A.
Published: February 2007

The loamy ‚brickearth’︁ deposits overlying coarse cold climate Kempton Park, Lynch Hill and Taplow Gravels of the R. Thames in west London are dated by thermoluminescence and mineralogical comparisons with loesses of three known ages. Although much of the ‚brickearth’︁ resembles loess, it often contains more sand or clay than typical loess, and the mineralogical studies suggest that even the coarse silt (16–63 μm) fraction is rarely similar in composition to any known English loess. The thermoluminescence measurements suggest that most of the ‚brickearth’︁ on the Taplow and Lynch Hill Gravels was deposited in the late Devensian, whereas that on the Park Gravel is mainly Flandrian. It is suggested that the latter is mainly floodloam, whereas the earlier ‚brickearth’︁ is a mixed aeolian sediment derived from various local sources in and close to the Thames Valley.
An ash fall within the Loch Lomond stadial
Authors: Long David , Morton Andrew C.
Published: February 2007

Cores recovered from the Witch Ground Basin (central North Sea) and the northern Rockall Trough, near the Wyville‐Thomson Ridge have been found to contain volcanic glass shards. These have been correlated with the Vedde Ash Bed of western Norway, which has an age of 10600± 60yr BP, and with North Atlantic ash zone 1. This is the first time that this important chronostratigraphic marker has been identified on the UK continental shelf and it is suggested that it might also be present in northern Scotland. If so, it would be a useful tool in the correlation of terrestrial, lacustrine and marine sequences of the Loch Lomond Stadial.
A magnetostratigraphic comparison between 14C years and varve years during the Late Weichselian, indicating significant differences between the time‐scales
Authors: Björck Svante , Sandgren Per , Holmquist Björn
Published: February 2007

A 14C‐dated magnetostratigraphy of absolute declination and inclination between 12500 and 10000 14C yr BP was recently developed for southern Sweden. Recently also the Swedish geochronological time‐scale, based on c. 11 500 annually deposited clay‐varves, was connected with the present. It should therefore be possible to compare the two chronologies with a reliable magnetostratigraphic record in an appropriate clay‐varve section. We have found such a site within the Middle Swedish end‐moraine zone. Statistical correlations between the two independently dated time‐scales suggest that at 10500–10200 14Cy r BP the varve chronology exceeds the 14C chronology by the order of 500‐600 varve yr. Other correlations indicate that the difference between the two chronologies was less at 11000 14C yr BP, and further correlations between the time‐scales at 12000 14C yr BP suggest that the difference between the chronologies increased steadily from 12000 to 10000 14C yr BP. If these correlations are correct they imply that the 14C production rate increased steadily during the Late Weichselian.
Ice wedges: Growth, thaw transformation, and palaeoenvironmental significance
Authors: Harry D. G. , Gozdzik J. S.
Published: February 2007

Frost‐cracking and ice‐wedge growth are fundamental processes within the permafrost environment. Extensive areas of contemporary permafrost terrain are characterised by frost‐fissure polygons, formed by repeated thermal contraction‐cracking of the ground. The incremental growth of ice veins and wedges along the axes of contraction‐cracks contributes significantly to the volume of ground ice in near‐surface permafrost. In areas beyond the present limit of permafrost, the recognition of ice‐wedge pseudomorphs provides one of the few unambiguous indications of the former existence of permafrost conditions. An understanding of the processes of ice‐wedge growth and thaw transformation is essential if contemporary ice wedges are to be used as analogues for Pleistocene frost‐fissure structures, in palaeoenvironmental reconstructions.
The significance of rock glaciers in the glacial‐periglacial landscape continuum
Authors: Giardino John R. , Vitek John D.
Published: February 2007

Rock glaciers are distinct landforms whose wide distribution, occurrence, and significance often go unrecognised. They are deposits of poorly sorted, angular, blocky to tabular debris which are held together by an ice core or a matrix of ice‐cemented fine clastics. Rock glaciers have formed in glaciated and non‐glaciated areas. Many researchers have suggested that the absence of an ice core or the lack of movement indicates relict or fossil status. Active and inactive states can be viewed as the end members of a movement continuum. Movement rates, derived from world‐wide locations as reported in the literature, range from less than 1 cmyr−1to greater than 130cmyr−1. Unfortunately, lack of observed movement has been equated incorrectly with an inactive status.

Rock glacier movement must be considered from a rheological point of view. Movement is controlled by the transformation of potential energy to kinetic energy as the system attempts to reach thermal equilibrium or stability. Whereas a glacier can completely disappear or redevelop, reactivation of a rock glacier requires only the re‐establishment of the conditions responsible for development and maintenance of interstitial ice. Although it might not be possible to re‐establish an ice core, interstitial areas can definitely be recharged with ice and thus facilitate movement. The concept of active versus inactive should be abandoned in favor of the view that a spatial and temporal continuum of form and movement exists.
The occurrence of Greigite in sediments from Loch Lomond
Authors: Snowball Ian , Thompson Roy
Published: February 2007

Greigite has been identified in the sediments of Loch Lomond using X‐ray diffraction. Greigite is the dominant magnetic mineral in the oldest sediments recovered, while magnetite predominates in the younger sediments which had previously been used for palaeomagnetic secular variation studies. A layer of sediment in between these two magnetic mineral regimes has very low magnetic concentrations, probably as a consequence of magnetite dissolution associated with sulphide rich pore‐waters produced at the time of a marine incursion.

The greigite largely oxidises once the sediment is exposed to air, but if freeze dried the greigite becomes surprisingly stable. Following freeze drying the greigite can be heated to 280°C in air before it alters and loses its strong ferrimagnetic properties.
Loess and palaeoenvironment: Some results of a European joint programme of research
Authors: Derbyshire Edward , Billard Armelle , Van Vliet‐Lanoë Brigitte , Lautridou Jean‐Pierre , Cnr Mauro Cremaschi
Published: February 2007

In 1985, a programme of research on the sedimentology and diagenesis of the loess and loessic silts of western Europe was initiated jointly by laboratories in Leicester, Meudon, Caen, Milan, Cardiff and Southampton, involving a limited amount of comparative work on the loess from types sites in the Loess Plateau of central China. Preliminary results include the following: (1) Experimental procedures in particle size analysis, clay sample preparation and microscopy have been standardised in all cooperating groups; distinctive fabrics indicative of depositional mechanisms have been recognised. (2) Comparison of aeolian, colluvial and alluvial silt by laser‐scanning and bulk magnetic susceptibility anisotropy methods appears to differentiate aeolian silt from loessic silts re‐deposited by slope processes and flowing water. (3) The variability in the anisotropy of the limon à doublet facies has been assessed by image analysis of scanning electron microscopy (SEM) and optical microscopy. Strong anisotropy has also been measured in thin section imagery of loess from Normandy and Poland as the product of freezing and thawing. This is confirmed by scanning electron microscopy and by experimental freezing of some silts. (4) The clay fabric and mineralogy in western European loess differ from those in Chinese loess, especially in the case of semi‐arid deposits. (5) Distribution of CaCO3, using thin sections and SEM analysis, has been determined for loess from Normandy and the Rhǒne valley in France and for some Chinese loess, At Saint Vallier, zones of CaCO3 concentration occur masking much of the original (loess) sedimentary skeleton which is a locally reworked loessic silt with some laminations. Despite considerable scatter, the palaeomagnetic results indicate a reversed polarity throughout, placing the whole Saint Vallier sequence in the Matuyama chron.

These preliminary results suggest the existence of two different palaeoenvironments: one typified by central China, with arid glacials and humid interglacials; and the other represented by western Europe, with generally high humidities. There was stronger weathering and soil development and fewer freezing effects on the lossic succession in northern Italy than in western littoral Europe.
The recognition of glacial retreat from palynological data: A review of recent work in the British Isles
Authors: Tipping Richard M.
Published: February 2007

Recent publications have presented palynological data from the early postglacial period in the British Isles, which have been interpreted as reflecting sequential glacial retreat following the Loch Lomond Stadial, The methodologies and results of these studies were examined and were concluded to be insufficient to demonstrate glacial retreat. A more cautious methodology was adopted and tested at several pollen sites in the Awe valley, Scotland. The results differed from previous studies in not demonstrating the sequence of palynological changes predicted from the hypothesis. These results need to be replicated at other localities, however, before the deglacial chronology hypothesis can be dismissed. Proposals to test the hypothesis further are suggested.
A Holocene tsunami deposit in eastern Scotland
Authors: Long David , Smith David E. , Dawson Alastair G.
Published: February 2007

A thin, regionally extensive, laterally persistent sand layer identified within the Holocene coastal sequences of eastern Scotland, dated to 7000 years BP, is suggested to be a tsunami deposit. The likely source of the tsunami wave is the earthquake induced second Storegga Slide on the Norwegian continental slope at least 750 km northeast of the deposit.
Quaternary tephrachronology on the Iceland Plateau, north of Iceland
Authors: Sejrup H. P. , Sjøholm J. , Furnes H. , Beyer I. , Eide L. , Jansen E. , Mangerud J.
Published: February 2007

Four major ash zones recorded in piston cores raised from the Iceland Plateau north of Iceland are shown to be coincident with the last four interglacial isotopic stages. Their geochemical composition links the ashes to volcanic events on Iceland. The occurrence of these ash layers, which record events orders of magnitude larger than the ‘normal’ Holocene volcanic eruptions, can not be explained by changes in sea ice cover and atmospheric circulation alone. It is suggested that these events are related to pressure releases in the magma chambers resulting from major deglaciations of the Icelandic Ice Cap.
Sediment source variations and lead‐210 inventories in recent Potomac Estuary sediment cores
Authors: Oldfield Frank , Maher Barbara A. , Appleby Peter G.
Published: February 2007

We present the results of magnetic measurements (low field susceptibility, anhysteretic and isothermal remanences) on samples of sediment from 11 cores from the Potomac River between Washington DC and its mouth. The magnetic properties indicate that at sites in the upstream reaches especially, there has been a shift to surface‐soil‐derived sediments in recent times. No such shift is indicated at the mouth of the Estuary. Comparison with pollen, 210Pb and trace metal analyses, where available, suggests that the shift to soil‐derived material dates from the early to mid‐19th century and coincides with a major land use change previously documented by Brush et al. (1982). Inventories of unsupported (excess) 210Pb activity in the cores increase upstream, are positively correlated with total sedimentation rates, and, in the upper reaches where the magnetic properties indicate soil inwash, greatly exceed values expected from direct atmospheric deposition alone. We infer that in these cores, most of the unsupported 210Pb is deposited from the surfaces of the catchment as a result of soil erosion.
Late Quaternary stratigraphy of the northern Rockall trough and Faeroe‐Shetland channel, northeast Atlantic Ocean
Authors: Stoker Martyn S. , Harland Rex , Morton Andrew C. , Graham Douglas K.
Published: February 2007

A late Quaternary deep‐water stratigraphic framework has been established for the deep‐water areas (>450m) of the northern Rockall Trough and Faeroe‐Shetland Channel. Four stratigraphic units (1–4) are identified; these are primarily biostratigraphic units based on dinoflagellate cyst evidence. Unit 1 represents the late Weichselian glacial (pre‐13 000 yr BP); unit 2 the Late Glacial Interstadial (11 000‐13 000 yr BP); unit 3 is of Younger Dryas age (10 000‐11 000 yr BP); and unit 4 represents the Holocene interglacial (post‐10 000 yr BP). This stratigraphy is supported by the discovery of the mixed Vedde Ash (10 600 yr BP) and North Atlantic Ash zone 1, and the Saksunarvatn Ash (9000–9100 yr BP), concentrated in units 3 and 4 respectively. The sedimentology indicates that the oceanographic regime underwent a major change between the glacial and interglacial stages. This is marked by the onset of strong bottom current activity, allied to the restoration of overflow of the Norwegian Sea Deep Water into the North Atlantic, towards the end of the Younger Dryas Stadial. Despite intense bioturbation and bottom‐current reworking the basic stratigraphic framework is maintained. Recognition of two volcanic ash markers enables correlation with established onshore and offshore sequences of marine and non‐marine environments.
Stress indicators adjacent to buried channels of Elsterian age in North Germany
Authors: Bruns Johannes
Published: February 2007

Tectonic and soil mechanics investigations of a strongly plastic clay (Miocene ‘Mica Clay’) led to the detection of strain phenomena induced in connection with the formation of Elsterian buried channels. A microjoint system with randomly distributed fissures is thought to result from early Elsterian dessiccation and frost crack formation. It occurs frequently in the upper part of the clay horizon. A younger joint system, which is encountered throughout the entire clay body, comprises macrojoints arranged in three joint sets. The evidence strongly suggests that they were formed by gravitational and kinematic loading of the clay body by overriding ice. The macrojoints display various secondary alterations such as slickensides, escarpments, shear zones, erosive and pressure zones, the formation of which is seen in context with the channel incision. Investigations into the genesis of these alterations indicate a strong horizontally‐orientated stress induction lateral to the channels, which resulted in stiffness modulus anisotropy. It has also caused a horizontal compression of the clay body, which at that time was already consolidated through ice overburdening. Horizontal compression of the clay led to evorsion of pore water eroding clay particles from the joint walls. Lower water content of the clay, in combination with increased dry unit weights, are found adjacent to the channels today.
Pleistocene climatic change in Southern Australia and its effect on speleothem deposition in some Nullarbor caves
Authors: Coede Albert , Harmon Russell S. , Atkinson Tim C. , Rowe Peter J.
Published: February 2007

Activity ratios of 234U/238U, 230Th/234U, and 230Th/232Th have been determined for calcite, gypsum and halite speleothems from caves of the Nullarbor Plain, mostly in the area N and NW of Mundrabilla Station, for the purpose of U‐series dating. All calcite speleothems contain adequate amounts of uranium for dating, but some show an excess of 230Th. Stratigraphic relationships indicate that there were at least three phases of calcium carbonate deposition in the Nullarbor caves. The calcite samples, with one possible exception, have ages in excess of ca. 400000 yrs BP. This suggests that no significant amounts of calcium carbonate deposition have taken place during the last 400ka.

At present, active deposition of speleothems is restricted almost entirely to gypsum and halite. The only gypsum speleothem dated was found to have a finite age of ca. 185 ka. Six dates on a small halite speleothem containing insect and arachnid remains indicate that it formed rapidly during Holocene time.
The last glaciation and relative sea level history of Northwest Ellesmere Island, Canadian high arctic
Authors: Evans David J. A.
Published: February 2007

Philips Inlet and Wootton Peninsula are located at 82°N and 85°W on the northwest coast of Ellesmere Island and are composed of three bedrock controlled zones: (1) 900 m undulating plateau dissected by fiords; (2) a deeply fretted cirque terrain >1200m; (3) a 300m plateau bounded by coastal cliffs. Each zone contains different glacier morphologies and these control glacigenic sediment and landform assemblages. The extent of the last glaciation is mapped using the distribution of moraines, kames, meltwater channels and glacimarine sediments. Glaciers advanced on average <10 km from their present margins and many piedmont lobes coalesced and floated in the sea. Morainal banks were deposited at the grounding lines of floating glaciers, and where debris‐charged basal ice occurred, subaqueous fans were deposited upon deglaciation. Marine shells dating 20.2 ka BP (<2km from present ice margin) and 14.9ka BP (from a morainal bank) document full glacial marine fauna. Thirty‐three radiocarbon dates document glacier retreat patterns and are used to reconstruct the postglacial sea level history (glacioisostatic rebound pattern). An equidistant shoreline diagram is constructed using the 8.5ka BP shoreline as a guide. Tilts from 0.73‐0.85m/km are calculated for this shoreline. Using two firm control points and tilts from elsewhere on northern Ellesmere Island, the 10.1 ka BP (full glacial) marine limit descends from 117m as at the fiord heads to 63 m asl at the north coast. Deglaciation started with a pronounced calving phase throughout the field area between 10.1 and 7.8ka BP. This chronology is similar to that from northeast Ellesmere Island and attests to an early Holocene warming trend recorded in high arctic ice cores. A maximum lag of 2.1 ka exists between the field area and locations to the south of the Grant Land Mountains suggesting differences in glacioclimatic regimes on either side of the mountain range. Persistent reconstructions of all‐pervasive ice sheets for the last glaciation of the area are obsolete and should be abandoned.
The Seal Edge Coombes, North Derbyshire — a study of their erosional and depositional history
Authors: Johnson Richard H. , Tallis John H. , Wilson Peter
Published: February 2007

Periglacial landforms and deposits of Devensian age are commonly observed on the higher hill slopes of North Derbyshire but to date very few glacial features or sediments have been recognised. At Seal Edge, the escarpment slope has been sculptured by both frost and nivational processes but at Middle Seal Clough there are lobate ridges located beyond the talus foot that are probably moraines, formed during the Dimlington Stadial of the Late Devensian, by a small corrie glacier. The history of the ‘coombe’ has been interpreted from a study of both the inorganic and organic sediments and although the results are not conclusive, they indicate that ice and snow were important in the development of the coombe and that the peat formations in the basin also provide the earliest record to date for events in the vegetation history of the southern Pennine moorlands.
Micromorphology of some North Sea till samples, a pilot study
Authors: Van Meer Jaap J. M. Der , Laban Cees
Published: February 2007

In a pilot study three samples of diamictons from boreholes in the Dutch sector of the North Sea have been thin sectioned. In the thin sections the granulometry, structure and plasmic fabric of the diamictons have been studied. On the basis of this study two of the samples have been interpreted as flow tills, while one sample has been interpreted as a basal (lodgement) till.
Pleistocene sediments, soils and landscape evolution at Stebbing, Essex
Authors: Whiteman Colin A. , Kemp Rob A.
Published: February 2007

Pleistocene sediments and soils exposed at Stebbing in central Essex, England are described, analysed and interpreted. The sand and gravel units above Eocene London Clay and Upper Pliocene Red Crag are shown to be a high level member of the Kesgrave Formation, with a surface immediately beneath that of the Westland Green Gravels, which are tentatively assigned to the Pre‐Pastonian ‘a’ Stage of the British Quaternary succession. The rubified, argillic soil developed in the surface of these fluvial deposits is a composite of the Valley Farm and Barham Soils and displays micromorphological evidence of several phases of clay illuviation, gleying and clay coating disruption. Originally truncated and buried beneath Anglian gelifluction deposits, cover sand and till, the soil has been exhumed in most places by subsequent erosion. The full succession, however, is preserved within large gulls that formed by periglacial cambering prior to this erosion. More recent loess incorporation and pedogenesis have modified the exhumed soil and the materials within the gulls.
Sand intraclasts within a diamicton mélange, southern Niagara Peninsula, Ontario, Canada
Authors: Menzies John
Published: February 2007

Sand intraclasts found within diamicton units along the north shore of Lake Erie in the Mohawk Bay area of the Niagara Peninsula would appear to be part of a ‘block‐in‐matrix’ mélange. The intraclasts are undeformed and many exhibit primary bedding structures. Numerous intraclasts have been rotated and/or tilted and are, in general, subrounded in outline. Examination of the surrounding diamicton reveals that the diamicton clast fabrics exhibit a wide scatter and are not characteristic of any known till clast fabric. Around each intraclast exists an aureole of brecciated diamicton. Other evidence in the form of macro‐ and microshear structures, and banding within the diamicton indicate that the diamicton has been subject to high strain.

Interpretation of the sand intraclasts seems to be intrinsically linked to the origin of the diamicton and together linked to the origin of the mélange. Various hypotheses are suggested separately for the sand intraclasts, diamicton and mélange. A subglacial deformable bed hypothesis is advanced as the most acceptable explanation for the complete sediment sequence in which diamicton and frozen sand intraclasts, the latter mobilised from the substrate, are moved as a mélange below an active fast‐moving ice mass.

Several implications from this study emerge with regard to glacial sedimentology and stratigraphic interpretations.
Lateglacial and Early Flandrian Coleoptera from La Taphanel, Massif Central, France: Climatic and Ecological Implications
Authors: Ponel Philippe , Russell Coope G.
Published: February 2007

A Lateglacial and early Holocene sequence of coleopteran assemblages is described from La Taphanel in the Massif Central, France. The site is a sediment‐filled small lake at an altitude of almost 1000 m. The insect fauna provides evidence for a detailed palaeoecological reconstruction, and in particular enables a reconstruction of climatic changes at the close of the last glaciation. A sudden climatic warming occurs at about 13000 yr BP followed by a temperate episode equivalent in time to the Bølling period. There is clear evidence of a short cold period between the Bølling and Allerød that is approximately equivalent to the Older Dryas period. The Allerød phase is decidedly cooler than the Bølling, as is shown by the Coleoptera from several sites in northwest Europe. A clear Younger Dryas signal is provided by the Coleoptera, with climates similar in severity to those of the glacial period. The climatic improvement at the start of the Holocene is also sudden, so that by Preboreal times temperatures were equivalent to those of the present day.