bluuebunny/crossref_metadata_2025 huggingface dataset:
Tributary valley impoundment by trunk river floodplain development: a case study from the KwaZulu‐Natal Drakensberg foothills, eastern South Africa
Authors: Grenfell Michael Cyril , Ellery William , Grenfell Suzanne Elaine
Published: March 2008

This paper investigates the origin and geomorphic evolution of Stillerust Vlei, a 189 ha wetland located approximately 150 km northwest of Durban in the temperate submontane foothills of the KwaZulu‐Natal Drakensberg Mountains. The investigation confirms the findings of previous research on the arid to semi‐arid South African interior, which established that many floodplain wetlands in eastern South Africa are located upstream of resistant rock barriers (dolerite intrusions) that cross river courses and form stable local base levels. Upstream of these barriers, rivers laterally plane less resistant Karoo sedimentary rocks (sandstones, mudstones), creating broad, low gradient valleys conducive to the formation of floodplain wetlands. In addition, the study examines how local levee and alluvial ridge accretion on the floodplain of Stillerust Vlei has impounded a small tributary valley, and drawing on observations of similar wetlands in the region, the paper explains the origin and geomorphic evolution of wetlands in floodplain‐abutting valleys, and associated streams that commonly become discontinuous toward their confluence with the trunk (floodplain) river. Controls on the origin and geomorphic evolution of Stillerust Vlei are placed within the context of slope‐channel decoupling and (dis)connectivity in sediment delivery, illustrating that wetlands are environments of deposition. As a result of dynamic trunk‐tributary relations, Stillerust Vlei holds a diversity of geomorphic features, and thus provides potential habitat for a diversity of biota. Copyright © 2008 John Wiley & Sons, Ltd.
Infant crying and maternal holding in the first 2 months of age: an Italian diary study
Authors: Bonichini Sabrina , Axia Giovanna , St. James‐Roberts Ian , DeCian Samantha
Published: March 2008

This study aims to confirm previous North American and North European findings about the normal developmental pattern of infant crying by studying the crying of Italian babies. A cohort of 70 healthy, full‐term Italian infants was assessed longitudinally at 2, 5 and 8 weeks of age. Mothers were asked to fill in 24‐h behaviour diaries for 3 consecutive days at each age. Results show significant differences in the amount of daily crying between 2 and 8 weeks and between 5 and 8 weeks. Different from other similar studies, no significant cry peak at 5 weeks was found in the Italian babies, but the amount of time Italian mothers spent holding their babies showed a peak at 5 weeks. Infants cried more during the evenings and mothers carried them most during this part of the day. Significant correlations between maternal holding and infant crying were found both concurrently and predictively. The amount of infant crying at 2 weeks predicted the amount of holding at 5 weeks. Results confirmed previous findings about the individual stability of daily crying in the first 8 weeks of age, but future research should take account of cultural variations in maternal holding in studying infant crying in different societies. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of surface acid groups associated with amorphous and structured carbon on the catalytic hydrodechlorination of chlorobenzenes
Authors: Amorim Claudia , Keane Mark A
Published: March 2008

BACKGROUND: Catalytic hydrodechlorination (HDC) is a progressive approach to treating chlorinated waste streams. While carbon is widely used as a catalyst support, the influence of carbon surface functionality on HDC performance has not been established. This work sets out to assess the impact of surface acid groups associated with activated carbon (AC), graphite and graphitic nanofibers (GNF) on Pd promoted gas phase HDC of chlorobenzene (CB) and 1,3‐dichlorobenzene (DCB).

RESULTS: The acid groups were introduced by HNO3 washing and the HDC reaction performed over bulk Pd and Pd physically mixed with each carbon. The carbon was subjected to a thermal treatment to remove the surface acidity. Characterization was by temperature programmed decomposition (TPD), temperature programmed hydrogen treatment (TPH), BET area, acid‐base titration, scanning and transmission electron microscopy. TPD, TPH and titration analyses served to establish the presence of surface oxygen groups after acid washing and facilitated an evaluation of the effectiveness of the thermal treatment to remove these groups.

CONCLUSIONS: The surface acid groups inhibited HDC activity, a response most pronounced for Pd + AC, less so for Pd + graphite, while the effect was slight for Pd + GNF. HDC inhibition is attributed to chloroarene interaction with the surface functional (notably carboxylic) groups that impedes HDC. Fractional dechlorination of DCB was equivalent to or lower than CB HDC; there is some evidence of DCB interactions with heat treated graphite and GNF that served to raise HDC activity. Effective HDC over carbon based catalysts requires removal of surface acid groups. Copyright © 2008 Society of Chemical Industry
Influence of pH and ionic strength on Cu(II) biosorption by aerobic granular sludge and biosorption mechanism
Authors: Gai Li‐Hong , Wang Shu‐Guang , Gong Wen‐Xin , Liu Xian‐Wei , Gao Bao‐Yu , Zhang Hua‐Yong
Published: March 2008

BACKGROUND: To elucidate the process and mechanism of Cu(II) biosorption onto aerobic granules, the influence of pH and ionic strength (IS) on the Cu(II) biosorption capacity and biosorption mechanism was studied.

RESULTS: The biosorption of Cu(II) onto aerobic granules under different conditions of pH (3, 4 and 5), IS (0, 0.1 and 0.5 mol L−1) and Cu(II) concentration (25–250 mg L−1) was investigated. The correlation coefficients of the pseudo‐second‐order kinetic model were $R_{2}^{2} > 0.99$, while those of the Langmuir and Freundlich models were $R_{1}^{2} > 0.975$ and $R_{2}^{2} > 0.955$ respectively. The biosorption of Cu(II) increased with increasing pH, while the effect of IS on the biosorption was complicated, which could be explained by the competition among different metallic ions, colloidal chemistry theory or Derjaguin, Landau, verwey and Overbeek (DLVO) theory. About 70% of the solid phase Cu(II) was exchanged by Na(I), Ca(II) and Mg(II) released from the aerobic granules at pH 4 and 5. The results revealed that ion exchange is the most important biosorption mechanism but that other mechanisms also play a part.

CONCLUSION: The sorption performance can be optimised by adjusting the pH and IS. Aerobic granules can be used as an alternative effective, economical and practical biosorbent for heavy metal removal. Copyright © 2008 Society of Chemical Industry
Selective enrichment of trace copper(II) from biological and natural water samples by SPE using ion‐imprinted polymer
Authors: Zhai Yunhui , Yang Dong , Chang Xijun , Liu Yongwen , He Qun
Published: March 2008

A novel Cu(II)‐imprinted polymer sorbent was prepared by an ion‐imprinted polymer (IIP) technique using (2Z)‐N,N′‐bis(2‐aminoethylic)but‐2‐enediamide as the functional monomer and pentaerythritol triacylate as a crosslinker. IR, XPS, and elemental analysis techniques were used to confirm the obtained product. Subsequently, when this polymer was used as sorbent in SPE, it exhibited excellent selectivity for template ion from an aqueous solution. Quantitative extraction of Cu(II) was achieved in the pH range of 4–7. The time needed to extract each sample was less than 30 min by the batch method. The distribution ratio (D) values of IIP for Cu(II) were greatly larger than that for other ions. At optimal pH value, the maximum extraction capacity of IIP and nonimprinted polymer (NIP) was found to be 29.8 and 7.0 mg/g, respectively. The adsorption behavior of Cu(II) on the sorbents could be described by Langmuir adsorption isotherm equation. The feasible flow rate of Cu(II)‐containing solution for quantitative extraction onto the column packed with IIP was 1–4 mL/min, whereas for elution it was less than 1 mL/min. The developed method was successfully applied to the separation and enrichment of trace Cu(II) in biological and natural water samples with satisfactory results.
Double‐wall nanotube as vibrational system: Mathematical approach
Authors: Shubov Marianna A. , Rojas‐Arenaza Miriam
Published: March 2008

In this paper, we present a recently developed mathematical model for short double‐wall carbon nanotubes. The model is governed by a system of four hyperbolic equations representing the two Timoshenko beams coupled through the Van der Waals forces. The system is equipped with a four‐parameter family of the boundary conditions and can be reduced to an evolution equation. This equation defines a strongly continuous semi‐group. Spectral properties of the semi‐group generator are presented in the paper. We show that it is an unbounded non‐selfadjoint operator with compact resolvent. Moreover, this operator is a relatively compact perturbation of a certain selfadjoint operator. Copyright © 2008 John Wiley & Sons, Ltd.
Treatment of juvenile xanthogranuloma
Authors: Stover Daniel G. , Alapati Srilatha , Regueira Osvaldo , Turner Curtis , Whitlock James A.
Published: March 2008

Juvenile xanthogranuloma (JXG) is generally a benign, self‐limited histiocytic disorder of the skin. We report two cases of multisystem JXG presenting with clinical features more commonly seen in Langerhans cell histiocytosis (LCH), including diabetes insipidus and lytic bony lesions. Histologically, the skin lesions demonstrated a histiocytic dermal infiltrate that stained for CD‐68, but S‐100 and CD1a stains were negative. Treatment according to LCH‐based chemotherapy regimens resulted in prompt resolution of symptoms. A literature review of multisystem JXG cases treated with chemotherapy suggests that symptomatic patients can successfully be treated with LCH‐based regimens that include both corticosteroids and vinca alkaloids. Pediatr Blood Cancer 2008;51:130–133. © 2008 Wiley‐Liss, Inc.
Management of women with psychosis during pregnancy
Authors: Howard Louise , Seneviratne Trudi
Published: March 2008

In the first of a series of reviews focusing on the management of women with psychiatric and neurological conditions during pregnancy, Dr Howard and Dr Seneviratne discuss the many issues surrounding the care of women with psychotic disorders during pregnancy and postpartum, including risks to the mother and fetus, use of antipsychotic medication and child protection issues. Copyright © 2008 Wiley Interface Ltd
Computational studies on the solvolysis of the chemical warfare agent VX
Authors: Daniel Kelly A. , Kopff Laura A. , Patterson Eric V.
Published: March 2008

The reaction of the chemical warfare agent VX with hydroxide and hydroperoxide has been studied using a combination of correlated molecular orbital and density functional theory. It is found that the alkaline hydrolysis leads to a mixture of neurotoxic and non‐toxic products while hydroperoxidolysis leads to exclusive formation of non‐toxic products. Natural bond orbital (NBO) analysis is used to rationalize the observation that hydroxide will attack opposite the alkoxide ligand, while hydroperoxide will attack opposite the thiolate. The current results are in good agreement with previous experimental and computational work and serve to clarify the mechanism for destruction of this highly potent nerve agent. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of a herbal gel containing carvacrol and chalcones on alveolar bone resorption in rats on experimental periodontitis
Authors: Botelho Marco Antonio , Rao Vietla Satyanarayana , Montenegro Danusa , Bandeira Mary Anne Menezes , Fonseca Said Gonçalves Cruz , Nogueira Nadia Accioly Pinto , Ribeiro Ronaldo Albuquerque , Brito Gerly Anne Castro
Published: March 2008

Carvacrol and dimeric chalcones are the respective bioactive components of Lippia sidoides and Myracrodruon urundeuva, popular medicinal plants of Northeastern Brazil with proven antimicrobial and antiinflammatory properties. Periodontal disease is associated with inflammation and microbiological proliferation, thus the study aimed to investigate the effect of a topical gel based on carvacrol and chalcones in the experimental periodontal disease (EPD) in rats. Animals were treated with carvacrol and/or chalcones gel, immediately after EPD induction, three times a day for 11 days. Appropriate controls were included in the study. Animals were weighed daily. They were killed on day 11, the mandibles dissected and alveolar bone loss was measured. The periodontium were examined at histopathology and the neutrophil influx into the gingiva was assayed using myeloperoxidase activity. The bacterial flora were assessed through culture of the gingival tissue. Alveolar bone loss was significantly (p < 0.05) inhibited by combined carvacrol and chalcones gel, compared with the vehicle and non‐treated groups. The treatment with the combined gel reduced tissue lesion at histopathology, decreased myeloperoxidase activity in gingival tissue and inhibited the growth of oral microorganisms as well as the weight loss. Carvacrol and chalcones combination gel has a beneficial effect upon EPD in this model. Copyright © 2008 John Wiley & Sons, Ltd.
Xα‐DVM investigation of double water molecule interactions with active sites of α‐ and β‐subunits of hemoglobin
Authors: Yuryeva Elmira I.
Published: March 2008

In this work, the results of Xα‐discrete variation method calculations of the electronic structure and interatomic parameters of chemical bonding between iron (II) and oxygen molecule with and without extra electrons and protons in active site (AS) of α‐ and β‐subunits of oxyhemoglobin are presented. The Skulachev model Skulachev, Sorosovskii obrazovatel'nyi zhurnal, 1998, 8, 2 of O2 molecule existing in respiration medium in the 2H2O form was used. The introduction of extra electrons does not change considerably the interaction of the iron atom with the O2 oxygen molecule, but strengthens the repulsion in the FeN bonds. In this case, the estimated effective charge of the iron atom is +1.8/1.5e for AS of α‐/β‐subunits of oxyhemoglobin, and the magnetic moment of iron atoms becomes zero. The deoxygenation effect of the AS of the α‐ and β‐subunits of oxyhemoglobin is due to the ability of extra protons to break down covalent attraction between the iron atom and the nearest oxygen atom and also to weakening of the repulsive component of the covalent FeN interactions. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Entanglement of angular momenta of atoms and molecules
Authors: Mishima K. , Yamashita K.
Published: March 2008

In this article, we investigate the entanglement degrees of angular momenta of atoms and molecules. We demonstrate theoretically and numerically the guidelines, how to prepare maximally entangled states and how the entanglement of the angular momenta changes by changing the quantum numbers of atoms and molecules. We show that the entanglement degree reduces to the Clebsch–Gordan coefficients frequently encountered in angular momentum theory. The maximally entangled states found in this manner are useful for quantum computers and quantum information science. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Structure‐hepatoprotective activity relationship study of sesquiterpene lactones: A QSAR analysis
Authors: Paukku Yuliya , Rasulev Bakhtiyor , Syrov Vladimir , Khushbaktova Zainab , Leszczynski Jerzy
Published: March 2008

This study has been carried out using quantitative structure‐activity relationship analysis (QSAR) for 22 sesquiterpene lactones to correlate and predict their hepatoprotective activity. Sesquiterpenoids, the largest class of terpenoids, are a widespread group of substances occurring in various plant organisms. QSAR analysis was carried out using methods such as genetic algorithm for variables selection among generated and calculated descriptors and multiple linear regression analysis. Quantum‐chemical calculations have been performed by density functional theory at B3LYP/6‐311G(d, p) level for evaluation of electronic properties using reference geometries optimized by semi‐empirical AM1 approach. Three models describing hepatoprotective activity values for series of sesquiterpene lactones are proposed. The obtained models are useful for description of sesquiterpene lactones hepatoprotective activity and can be used to estimate the hepatoprotective activity of new substituted sesquiterpene lactones. The models obtained in our study show not only statistical significance, but also good predictive ability. The estimated predictive ability (r) of these models lies within 0.942–0.969. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Coherent x‐ray diffraction measurements of Cu thin lines
Authors: Takahashi Yukio , Furukawa Hayato , Kubo Hideto , Yamauchi Kazuto , Nishino Yoshinori , Ishikawa Tetsuya , Matsubara Eiichiro
Published: March 2008

1‐µm‐thick Cu thin lines with adjacent connections, which simulate via structures in large‐scale integration circuits, were fabricated on Si3N4 membranes by both electron‐beam evaporation and a focused ion beam for coherent x‐ray diffraction measurements. A direct current was applied to a Cu thin line to prepare an electromigration sample. In the scanning electron microscope image of the electromigration sample, a roughness of a few hundred nanometers was observed on the surface around the via structures. Coherent x‐ray diffraction patterns of both the thin line and electromigration samples were measured using synchrotron x‐rays at SPring‐8. Characteristic diffraction patterns resulting from both the shape of the Cu thin lines and the defects around the via structures formed by the application of the current were observed. Copyright © 2008 John Wiley & Sons, Ltd.
Practical guidelines for assessing power and false discovery rate for a fixed sample size in microarray experiments
Authors: Tong Tiejun , Zhao Hongyu
Published: March 2008

One major goal in microarray studies is to identify genes having different expression levels across different classes/conditions. In order to achieve this goal, a study needs to have an adequate sample size to ensure the desired power. Owing to the importance of this topic, a number of approaches to sample size calculation have been developed. However, due to the cost and/or experimental difficulties in obtaining sufficient biological materials, it might be difficult to attain the required sample size. In this article, we address more practical questions for assessing power and false discovery rate (FDR) for a fixed sample size. The relationships between power, sample size and FDR are explored. We also conduct simulations and a real data study to evaluate the proposed findings. Copyright © 2008 John Wiley & Sons, Ltd.
An imputation strategy for incomplete longitudinal ordinal data
Authors: Demirtas Hakan , Hedeker Donald
Published: March 2008

A new quasi‐imputation strategy for correlated ordinal responses is proposed by borrowing ideas from random number generation. The essential idea is collapsing ordinal levels to binary ones and converting correlated binary outcomes to multivariate normal outcomes in a sensible way so that re‐conversion to the binary and then ordinal scale, after conducting multiple imputation, yields the original marginal distributions and correlations. This conversion process ensures that the correlations are transformed reasonably, which in turn allows us to take advantage of well‐developed imputation techniques for Gaussian outcomes. We use the phrase ‘quasi’ because the original observations are not guaranteed to be preserved. We present an application using a data set from psychiatric research. We conclude that the proposed method may be a promising tool for handling incomplete longitudinal or clustered ordinal outcomes. Copyright © 2008 John Wiley & Sons, Ltd.
Calibrating standards using chemical reagents for glass bead x‐ray fluorescence analyses of geochemical samples
Authors: Nakayama Kenichi , Nakamura Toshihiro
Published: March 2008

Calibration standards for glass bead x‐ray fluorescence (XRF) analysis of geochemical samples are discussed in this article. Although rock references issued by geological organizations have often been applied to glass bead XRF, several problems remain: limited varieties and numbers, and uncertainty related to uncertified (recommended or preferred) values. Various geological references (e.g. rocks, sediments, and materials) having extensive elemental composition have often been applied for calibration. The XRF intensities must be corrected using an appropriate matrix‐correction method because the matrix effect resulting from the application of various references was not negligible. Attempts have been made to extend the calibration range by geological reference with such approaches as blending some references and adding chemical reagents to references. However, geological references for the calibrating standards should be used intact because the reliability of the certified values of references is lost. Synthesized calibrating standards with chemical reagents have constitutive properties which are superior to those of the rock references. Synthesized standards can ensure the traceability of the analytical procedure and the resultant accuracy and propriety of calibration curves. Reliable calibration curves are obtainable by designing such parameters as the number of plots, plotting arrangements, and calibrating ranges. Synthesized standards must be prepared by fitting the elemental composition to each geological sample. This discussion reviews calibration standards applying rock references or chemical reagents related to glass bead XRF. Copyright © 2008 John Wiley & Sons, Ltd.
Lifetime‐broadening‐suppressed XANES spectra of copper complexes
Authors: Hayashi Hisashi , Matsuo Shuji , Kurisaki Tsutomu , Kawamura Naomi
Published: March 2008

Lifetime‐broadening‐suppressed (LBS) Cu K‐XANES spectra of several Cu (II) complexes have been measured by partially fluorescent yield technique. The obtained spectra were compared with oscillator strength distributions calculated by discrete variational Xα method. It was demonstrated that LBS‐XANES spectra are sensitive to ligands, and hence are applicable as a helpful probe in coordination chemistry. Copyright © 2008 John Wiley & Sons, Ltd.
Powder briquette/x‐ray fluorescence analysis of major and minor elements in alkali‐washed fly ash of municipal solid waste
Authors: Ohbuchi Atsushi , Kitano Masaru , Nakamura Toshihiro
Published: March 2008

X‐ray fluorescence (XRF) analyses of 13 major and 5 minor components in alkali‐washed fly ash of municipal solid waste were developed using powder briquette method. Fly ash samples were ground for 80 min using a ball mill to prepare reproducible powder briquette. The resultant particles had 12‐µm modal diameter and gave good reproducibility (3.2%). Calibration curves for analyses of 13 major and 5 minor elements required 16 reagents containing 18 analytes. They were ground for 20 min by ball milling after 80‐min mixing with a V‐type mixing machine or 2‐h manual mixing using an alumina mortar. Lower limits of detection corresponding to 3 times the standard deviation (n = 6) for blank measurements were: Na2O, 23 ppm; MgO, 22 ppm; Al2O3, 24 ppm; SiO2, 21 ppm; P2O5, 3.0 ppm; SO4, 3.1 ppm; Cl, 232 ppm; K2O, 51 ppm; CaO, 26 ppm; TiO2, 32 ppm; Cr, 6.3 ppm; MnO, 7.2 ppm; Fe2O3, 18 ppm; Ni, 5.3 ppm; Cu, 4.7 ppm; Zn, 5.4 ppm; Br, 4.7 ppm; and Pb, 4.6 ppm. This method was applied to analyses of 13 major and 5 minor elements in fly ash samples, which mainly consisted of Al2O3, SiO2, Cl, and CaO. Several thousand parts per million of Zn and Pb were included in most fly ash samples; Cl and Br were analyzed though their volatile characteristics. Copyright © 2008 John Wiley & Sons, Ltd.
Exposure age chronology of the last glaciation in the eastern Pyrenees
Authors: Delmas Magali , Gunnell Yanni , Braucher Régis , Calvet Marc , Bourlès Didier
Published: March 2008

We present a chronology of ice recession in the eastern Pyrenees based onin situ-produced10Be data obtained from the Têt paleoglacier complex. The sampling strategy is based on the relative chronology provided by a detailed geomorphological map of glacial landforms. Results indicate that the last maximum ice advance occurred late (i.e., during Marine Isotope Stage 2) compared to the chronology currently established for the rest of the Pyrenees. Despite debatable evidence for a glacial readvance during the Oldest Dryas stade, ice-cap melt-out was rapid, residual cirque glaciers having disappeared by the Allerød interstade. This is consistent both with North Atlantic excursions established by the Greenland ice cores and paleoenvironmental data for the region. The rapid response of the east-Pyrenean ice cap to temperature variations is primarily linked to its small size compared to larger Pyrenean ice fields, to the dry Mediterranean climate, and to topography-related nonlinearities in which a small vertical rise in equilibrium line altitude generates a large change in ice mass. Possible sources of age uncertainty are discussed in the context of sampling design for single-nuclide (10Be) dating of landform sequences in formerly glaciated landscapes.
Contribution of gut microbial lysine to liver and milk amino acids in lactating does
Authors: Abecia Leticia , Balcells Joaquím , Fondevila Manuel , Belenguer Alvaro , Holtrop Grietje , Lobley Gerald E.
Published: March 2008

The contribution of microbial amino acids through caecotrophy to tissue protein metabolism was investigated in lactating does. Attempts were made to vary microbial supply through a dietary antibiotic, Zn bacitracin, and to vary tissue demand through manipulation of litter size. Three groups of eight New Zealand does were fed different experimental diets from day 28 of pregnancy to day 26 of lactation. The control group received the basal diet formulated to meet requirements with grass hay, wheat, soyabean meal and barley grain. The second (no antibiotic) group and the third (bacitracin; BAC) group ingested the basal diet supplemented with ammonium sulfate (5 g/kg), initially unlabelled (day 1 to day 8) then labelled with15N (day 9 to day 30), while the BAC diet was also supplemented throughout with antibiotic (Zn bacitracin; 100 mg/kg). From just after birth each group of does was subdivided into two groups, each of four females, with the litter size either five (LS5) or nine (LS9) pups. The15N enrichment in liver, milk and caecal bacteria amino acids was determined by GC-combustion-isotope ratio MS. All amino acids in bacterial protein were enriched with the (15NH4)2SO4treatment, with lysine15N enrichment significantly greater in caecal bacteria (0·23 (se0·0063) atom % excess (ape)) than in liver (0·04 (se0·0004) ape) or milk protein (0·05 (se0·0018) ape), confirming the double origin (bacterial and dietary) of tissue lysine. The contribution of microbes to tissue lysine was 0·23 (se0·006) when milk protein was used as reference.
Extreme values for Benedicks–Carleson quadratic maps
Authors: MOREIRA FREITAS ANA CRISTINA , FREITAS JORGE MILHAZES
Published: March 2008

We consider the quadratic family of maps given by fa(x)=1−ax2 with x∈[−1,1], where a is a Benedicks–Carleson parameter. For each of these chaotic dynamical systems we study the extreme value distribution of the stationary stochastic processes X0,X1,… , given by Xn=fan, for every integer n≥0, where each random variable Xn is distributed according to the unique absolutely continuous, invariant probability of fa. Using techniques developed by Benedicks and Carleson, we show that the limiting distribution of Mn=max {X0,…,Xn−1} is the same as that which would apply if the sequence X0,X1,… was independent and identically distributed. This result allows us to conclude that the asymptotic distribution of Mn is of type III (Weibull).
Preparation, Characterization and Refolding in Vitro of a Recombinant Human Cyclophilin A Mutant: Effect of a Single Pro/Ser Substitution on Cyclophilin A Structure and Properties
Authors: Xu Li‐Ren , Yan Xiao , Luo Man , Guan Yi‐Xin , Yao Shan‐Jing
Published: March 2008

A recombinant cyclophilin A (CypA) mutant, which carries a serine instead of proline at sequence 16, was prepared for structural and functional assessment for human CypA. Soluble expression of the recombinant CypA mutant in E. coli was obtained under 30 °C, 180 rpm culture condition after being induced by IPTG. Ion exchange chromatography was used to purify the CypA mutant in a single step, and a high activity recovery of target protein with a high purity was achieved. Peptide fragments produced by trypsin proteolysis were applied to MALDI‐TOF‐MS, and searching results from the NCBI protein databank confirmed the protein attribution as well as the mutation sequence. Peptidyl‐prolyl cis‐ trans isomerase activity was assayed for the CypA mutant using tetrapeptide substrate Suc‐Ala‐Ala‐Pro‐Phe‐ p‐nitroanilide, and the calculated kcat/ Km value was 1.5 × 106 M−1 s−1 at 10 °C, which was 10‐fold lower than the previously reported constant for wild‐type CypA. An Eyring plot was also carried out. Inhibition by cyclosporine A demonstrated that the IC50 value was 26.5 nM. Meanwhile the expected enhancement of intrinsic tryptophan fluorescence was quenched by the mutation. The effect of CypA mutant on accelerating protein refolding in vitro was investigated in ribonuclease A refolding process, and it was found that 10% slow phase could be catalyzed by CypA. The protein was subject to urea and GdmCl denaturation, where both activity and fluorescence served as structural probes. Activity recovery indicated this CypA mutant was extremely sensitive to GdmCl and the susceptibility to urea was increased. Low pH could also destabilize CypA. Furthermore the refolding of this CypA mutant itself was studied. Although the activity yield was nearly unchanged, the former proposed folding/assembly pathway might be altered. Fluorescence chart also demonstrated that the folding time was extended, and fast‐folding and slow‐folding analysis indicated the slow‐folding rate constant presented a concentration dependence property denoting the autocatalysis of the foldase.
Scale‐Up of Agrobacterium‐Mediated Transient Protein Expression in Bioreactor‐Grown Nicotiana glutinosa Plant Cell Suspension Culture
Authors: M. O'Neill Kristin , Larsen Jeffrey S. , Curtis Wayne R.
Published: March 2008

The reporter gene β‐glucuronidase was transiently expressed in a 51‐L bioreactor‐grown plant cell suspension culture of Nicotiana glutinosa at a yield of approximately 1.1 mg through co‐culture with an auxotrophic strain of Agrobacterium tumefaciens. The three order of magnitude scale‐up involved the investigation of factors contributing to transient expression including the timing of Agrobacterium inoculation relative to the plant cell growth phase, plant tissue culture hormonal triggers and plant cell cycle synchronization. The co‐culture process was simplified to facilitate implementation in a pilot‐scale bioreactor. At the shake flask scale it was determined that elevated concentrations of oxygen in the headspace were detrimental to transient expression levels and the addition of acetosyringone to the co‐culture had a negligible effect. The bacterial preparation process was also streamlined, permitting the direct transfer of the Agrobacterium culture from a bench‐scale fermentor to the pilot‐scale plant cell culture bioreactor. Increasing expression levels and overcoming batch‐to‐batch variability despite extensive procedure systemization remain the major technical hurdles.
Physical modeling of the influence of bedrock topography and ablation on ice flow and meteorite concentration in Antarctica
Authors: Corti Giacomo , Zeoli Antonio , Belmaggio Pietro , Folco Luigi
Published: March 2008

Three‐dimensional laboratory physical experiments have been used to investigate the influence of bedrock topography and ablation on ice flow. Different models were tested in a Plexiglas box, where a transparent silicone simulating ice in nature was allowed to flow. Experimental results show how the flow field (in terms of both flow lines and velocity) and variations in the topography of the free surface and internal layers of the ice are strongly influenced by the presence and height of bedrock obstacles. In particular, the buttressing effect forces the ice to slow down, rise up, and avoid the obstacle; the higher the bedrock barrier, the more pronounced the process. Only limited uplift of internal layers is observed in these experiments. In order to exhume deep material embedded in the ice, ablation (simulated by physically removing portions of silicone from the model surface to maintain a constant topographic depression) must be included in the physical models. In this case, the analogue ice replenishes the area of material removal, thereby allowing deep layers to move vertically to the surface and severely altering the local ice flow pattern. This process is analogous to the ice flow model proposed in the literature for the origin of meteorite concentrations in blue ice areas of the Antarctic plateau.
Biogenic silica concentration as a high‐resolution, quantitative temperature proxy at Hallet Lake, south‐central Alaska
Authors: McKay Nicholas P. , Kaufman Darrell S. , Michelutti Neal
Published: March 2008

High‐resolution, quantitative temperature records are valuable for placing recent warming in the context of long‐term, natural climate variability. Here we use biogenic silica (BSi) concentrations preserved in lacustrine sediment from an oligotrophic lake to quantitatively reconstruct air temperature at Hallet Lake in south‐central Alaska. Mean June through August temperature measured over the past 80 yr at Valdez (Alaska) correlate with BSi from Hallet Lake (r = 0.87, p = 0.01). We chose a nested function to model the non‐linear relation between summer temperature and BSi in the calibration data set, and to reconstruct temperature for the past 2 ka. Our BSi‐inferred temperature reconstruction shows synchronous changes with independent paleoclimatic proxies for southern Alaska, and provides evidence for a greater rate and magnitude of 20th century temperature warming at Hallet Lake than recorded by other quantitative temperature proxies in the region.
Modeling the relationship between E × B vertical drift and the time rate of change of hmF2 (ΔhmF2/Δt) over the magnetic equator
Authors: Yue Xinan , Wan Weixing , Lei Jiuhou , Liu Libo
Published: March 2008

A middle and low latitude ionospheric model is used to model the relationship between E × B vertical drift velocity and time rate of change of hmF2 (ΔhmF2/Δt) over the magnetic equator. F107 (10.7 cm solar radiation flux) is chosen to be equal to 100, 150, and 200 to represent low, middle, and high solar activities, respectively, and Ap is equal to 1 to represent quiet geomagnetic activity. Our simulations show that hmF2 derived vertical drifts over the magnetic equator are in good agreement with the E × B vertical drift imposed in the model during 0600–0730 and 1700–2100 LT. This is consistent with previous comparisons between vertical drift velocities derived from ionosonde, Jicamarca incoherent scatter radar, and AE‐E observations well. However, the amplitudes of hmF2 derived drift are smaller than the given drift velocities during other local times. During disturbed conditions, the variations of hmF2 can be used to determine the occurrence of intense electric field disturbance.
Decadal‐scale periodicities in the stratosphere associated with the solar cycle and the QBO
Authors: Smith Anne K. , Matthes Katja
Published: March 2008

An interactive two‐dimensional model is used to analyze the response of the stratosphere to the 11‐year solar cycle in the presence of a quasi‐biennial oscillation (QBO). The purpose of the paper is to demonstrate how the solar cycle response of stratospheric ozone and temperature diagnosed from model simulations depends on the QBO. The analyses show that (1) the simulated response to the solar flux when no QBO is imposed is very similar in different periods, despite differences in the magnitude and variability of the solar forcing; (2) the apparent solar response of temperature and ozone is modified by the presence of an imposed QBO; and (3) the impact of the QBO on the derived solar response is greatly reduced when the observed QBO forcing is replaced by an idealized sinusoidal forcing. The impact of the QBO on the solar cycle analysis is larger when only two solar cycles are analyzed but is not negligible even for analysis of four solar cycles. Differences in the QBO contribution account for most of the differences in analyses of separate 22‐year periods. The statistical significance is not always a reliable indicator that the QBO effect has been separated.
U.S. National Science Foundation Budget Proposal Focuses on Basic Research
Authors: Kumar Mohi
Published: March 2008

The budget request of the U.S. National Science Foundation (NSF) for fiscal year (FY) 2009 focuses attention on basic research, establishes and supports several cross‐foundation investment projects designed to have a transformative impact across science and engineering, and puts foundation activities back on track to double their research budgets by the next decade.

The foundation's total proposed budget is US$6.85 billion, an increase of 13% over that enacted for FY 2008. Most of this funding increase goes to NSF's Research and Related Activities (R&RA) account, which, at $5.59 billion, is $772.5 million above the FY 2008 enacted amount.
Developing Strategies for Future Climate Change Science: Future Climate Change Research and Observations: GCOS, WCRP and IGBP Learning From the IPCC Fourth Assessment Report; Sydney, Australia, 4–6 October 2007
Authors: Bojinski Stephan , Doherty Sarah
Published: March 2008

Learning from the findings of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report to design future strategies for climate change research and observations was the key objective of a workshop organized jointly by the Global Climate Observing System (GCOS), the World Climate Research Program (WCRP), and the International Geosphere‐ Biosphere Programme (IGBP) in Sydney, Australia.

Some 66 key IPCC authors and other experts associated with the three international programs discussed ways to sustain and develop future observing systems and to define climate change research challenges, based on gaps and uncertainties identified by IPCC Working Group I (The Physical Science Basis) and Working Group II (Impacts, Adaptation, and Vulnerability) in their latest assessments.
Foufoula‐Geogiou Receives 2007 Hydrologic Sciences Award
Authors: Hornberger George M. , Foufoula‐Georgiou Efi
Published: March 2008

It is my great pleasure today to introduce the recipient of the 2007 AGU Hydrologic Sciences Award, Efi Foufoula‐Georgiou.

Efi took her Ph.D. at the University of Florida (environmental engineering), and she has been at the University of Minnesota for a number of years where she is the McKnight Distinguished Professor in the Department of Civil Engineering. Efi is codirector of NCED, the National Science Foundation Science and Technology Center dealing with Earth‐surface dynamics.
Mantle Plumes: A Multidisciplinary Approach
Authors: Condie Kent C.
Published: March 2008

Mantle plumes are blobs of relatively hot, low‐density mantle that because of their buoyancy, rise through the surrounding mantle. The existence of mantle plumes in the Earth was first suggested in 1963 by J. Tuzo Wilson at the University of Toronto as an explanation of oceanic island chains, such as the Hawaiian and Emperor volcanic chains, which change progressively in age along the chain. Wilson proposed that as lithospheric plates move over fixed hot spots (the mantle plumes), volcanism is recorded as a linear array of volcanic seamounts and islands parallel to the direction the plate is moving.

In 1971, W. Jason Morgan at Princeton University suggested that flood basalts were formed by the melting of plume heads, whereas hot spot volcanic chains were derived from partial melting of plume tails. He also showed that closely spaced hot spots on the same plate had not moved significantly relative to each other, and he suggested this was evidence that the plumes had come from the core‐mantle boundary.
Understanding the social context of the Schelling segregation model
Authors: Clark William A. V. , Fossett Mark
Published: March 2008

A recent article [Vinkovic D, Kirman A (2006)
Proc Natl Acad Sci USA
103:19261–19265] showing that the Schelling model has a physical analogue extends our understanding of the model. However, prior research has already outlined a mathematical basis for the Schelling model and simulations based on it have already enhanced our understanding of the social dynamics that underlie the model, something that the physical analogue does not address. Research in social science has provided a formal basis for the segregative outcomes resulting from the residential selection process and simulations have replicated relevant spatial outcomes under different specifications of the residential dynamics. New and increasingly detailed survey data on preferences demonstrates the embeddedness of the Schelling selection process in the social behaviors of choosing alternative residential compositions. It also demonstrates that, in the multicultural context, seemingly mild preferences for living with similar neighbors carry the potential to be strong determinants for own race selectivity and residential segregation.
Hierarchical modelling of attachment and detachment mechanisms of gecko toe adhesion
Authors: Chen B , Wu P.D , Gao H
Published: March 2008

The mechanics of reversible adhesion of the gecko is investigated in terms of the attachment and detachment mechanisms of the hierarchical microstructures on its toe. At the bottom of the hierarchy, we show that a spatula pad of tiny thickness can be well absorbed onto a substrate with a large surface area and a highly constrained decohesion process zone, both of which are beneficial for robust attachment. With different peeling angles, the peeling strength of a spatula pad for attachment can be 10 times larger than that for detachment. At the intermediate level of hierarchy, we show that a seta can achieve a stress level similar to that in the spatula pad by uniformly distributing adhesion forces; as a consequence, the 10 times difference in the peel-off force of a single spatula pad for attachment and detachment is magnified up to a 100 times difference in adhesion energy at the level of seta. At the top of the hierarchy, the attachment process of a gecko toe is modelled as a pad under displacement-controlled pulling, leading to an adhesive force much larger than the gecko's body weight, while the associated detachment process is modelled as a pad under peeling, resulting in a negligible peel-off force. The present work reveals, in a more systematic way than previous studies in the literature, that the hierarchical microstructures on the gecko's toe can indeed provide the gecko with robust adhesion for attachment and reversible adhesion for easy detachment at the same time.
Tel2 mediates activation and localization of ATM/Tel1 kinase to a double-strand break
Authors: Anderson Carol M. , Korkin Dmitry , Smith Dana L. , Makovets Svetlana , Seidel Jeffrey J. , Sali Andrej , Blackburn Elizabeth H.
Published: March 2008

The kinases ATM and ATR (Tel1 and Mec1 in the yeast Saccharomyces cerevisiae) control the response to DNA damage. We report that S. cerevisiae Tel2 acts at an early step of the TEL1/ATM pathway of DNA damage signaling. We show that Tel1 and Tel2 interact, and that even when Tel1 protein levels are high, this interaction is specifically required for Tel1 localization to a DNA break and its activation of downstream targets. Computational analysis revealed structural homology between Tel2 and Ddc2 (ATRIP in vertebrates), a partner of Mec1, suggesting a common structural principle used by partners of phoshoinositide 3-kinase-like kinases.
General Detoxification and Stress Responses Are Mediated by Oxidized Lipids through TGA Transcription Factors inArabidopsis
Authors: Mueller Stefan , Hilbert Beate , Dueckershoff Katharina , Roitsch Thomas , Krischke Markus , Mueller Martin J. , Berger Susanne
Published: March 2008

12-oxo-phytodienoic acid and several phytoprostanes are cyclopentenone oxylipins that are formed via the enzymatic jasmonate pathway and a nonenzymatic, free radical–catalyzed pathway, respectively. Both types of cyclopentenone oxylipins induce the expression of genes related to detoxification, stress responses, and secondary metabolism, a profile clearly distinct from that of the cyclopentanone jasmonic acid. Microarray analyses revealed that 60% of the induction by phytoprostanes and 30% of the induction by 12-oxo-phytodienoic acid was dependent on the TGA transcription factors TGA2, TGA5, and TGA6. Moreover, treatment with phytoprostanes and 12-oxo-phytodienoic acid inhibited cell division and root growth, a property also shared by jasmonic acid. Besides being potent signals, cyclopentenones and other lipid peroxidation products are reactive electrophiles that can covalently bind to and damage proteins. To this end, we show that at least two of the induced detoxification enzymes efficiently metabolize cyclopentenones in vitro. Accumulation of two of these metabolites was detectable during Pseudomonas infection. The cyclopentenone oxylipin gene induction profile resembles the defense response induced by a variety of lipophilic xenobiotics. Hence, oxidized lipids may activate chemosensory mechanisms of a general broad-spectrum detoxification network involving TGA transcription factors.
Changes in the Marrow Reserve of Eosinophils Following Re‐exposure to Foreign Protein
Authors: Hudson G.
Published: March 2008

In an earlier investigation (Hudson, 1960), the quantitative methods developed in this laboratory (Yoffey, 1960) were used to demonstrate the magnitude of the ‘reserve’of mature and nearly mature eosinophils in normal bone marrow. The question arose as to the circumstances under which this reserve might be drawn upon. Numerous investigations have shown that eosinophil granulocytes have an important role in the response to foreign protein and that increased numbers are found in blood and bone marrow following repeated exposure to the same antigen (e.g. Schlecht, 1910; Speirs, 1960; Litt, 1960; Winqvist, 1960). It has also been noted by several investigators (Hajós, 1928; Biggart, 1932; Samter, 1949) that at a definite interval after re‐exposing a sensitized animal to a foreign protein, there is a very striking circulatory eosinophilia which, the observations of Homma (1921) suggest, may be accompanied by a temporary decrease in the percentage of eosinophils in the bone marrow. However, the possibility that there may be a depletion of the marrow reserve of eosinophils in these circumstances has not hitherto been investigated by quantitative methods. It seemed important, therefore, to study these methods to study the blood and bone‐marrow eosinophils of the guinea‐pig during the phase of marked circulatory eosinophilia which follows the reinjection of foreign protein.
The Utilization of Tritium‐Labelled Folic Acid in Megaloblastic Anaemia
Authors: Chanarin I. , Belcher E. H. , Berry V.
Published: March 2008

The retention of small doses of parenteral folic acid in man provides good evidence of the state of the folic‐acid stores. Not only is a greater amount retained in patients with haematological evidence of folic‐acid deficiency but these doses, when given intravenously, are cleared from the plasma to the tissues more rapidly than in control subjects (Chanarin, Mollin and Anderson, 1958; Chanarin and Bennett, 1962a). The amount of folic acid retained is assessed by subtracting the urinary loss measured by microbiological assay from the dose administered. However, after small doses of folic acid the urine may contain not only folic acid itself but also breakdown products and analogues which may be unavailable to microbiological assay organisms (Johns, Sperti and Burgen, 1961). This problem can be overcome by using isotopically labelled folic acid and measuring both the radioactivity and microbiological activity of urine samples following standard doses of folic acid. This paper reports the results of such an investigation.