bluuebunny/crossref_metadata_2025 huggingface dataset:
Immobilisation of biomolecules for biosensors
Authors: Barlen Benjamin , Mazumdar Saikat Datta , Keusgen Michael
Published: January 2009

Immobilisation of proteins, mainly enzymes and antibodies, is one of the most crucial steps in the development of biosensors. Unspecific methods as well as site‐directed strategies have been developed in order to obtain highest functionality and stability. Different methods for immobilisation of antibodies were tested to develop a surface plasmon resonance (SPR) biosensor for the detection of Salmonella. It turned out, that best results in terms of capturing and detection of Salmonella were achieved by immobilisation via hydrophobic interaction, using a sensor surface coated with C18‐alkyl chains allowing integration of hydrophobic parts of the antibody. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon nanotubes in nanostructured films: Potential application as amperometric and potentiometric field‐effect (bio‐)chemical sensors
Authors: Siqueira José R. , Abouzar Maryam H. , Bäcker Matthias , Zucolotto Valtencir , Poghossian Arshak , Oliveira Osvaldo N. , Schöning Michael J.
Published: January 2009

The assembly of carbon nanotubes (CNTs) into nanostructured films is attractive for producing functionalized hybrid materials and (bio‐)chemical sensors, but this requires experimental methods that allow for control of molecular architectures. In this study, we exploit the layer‐by‐layer (LbL) technique to obtain two types of sensors incorporating CNTs. In the first, LbL films of alternating layers of multi‐walled carbon nanotubes (MWNTs) dispersed in polyaminoamide (PAMAM) dendrimers and nickel phthalocyanine (NiTsPc) were used in amperometric detection of the neurotransmitter dopamine (DA). The electrochemical properties evaluated with cyclic voltammetry indicated that the incorporation of MWNTs in the PAMAM‐NT/NiTsPc LbL films led to a 3‐fold increase in the peak current, in addition to a decrease of 50 mV in the oxidation potential of DA. The latter allowed detection of DA even in the presence of ascorbic acid (AA), a typical interferent for DA. Another LbL film was obtained with layers of PAMAM and single‐walled carbon nanotubes (SWNTs) employed in field‐effect‐devices using a capacitive electrolyte–insulator–semiconductor structure (EIS). The adsorption of the film components was monitored by measuring the flat‐band voltage shift in capacitance–voltage (C –V) curves, caused by the charges from the components. Constant‐capacitance (ConCap) measurements showed that the EIS‐PAMAM/SWNT film displayed a high pH sensitivity (ca. 54.5 mV/pH), being capable of detecting penicillin G between 10–4 mol L–1 and 10–2 mol L–1, when a layer of penicillinase was adsorbed atop the PAMAM/SWNT film. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synoptic scale wave breaking and its potential to drive NAO‐like circulation dipoles: A simplified GCM approach
Authors: Kunz Torben , Fraedrich Klaus , Lunkeit Frank
Published: January 2009

Recent studies suggest a synoptic view of the North Atlantic oscillation (NAO) with its positive (negative) phase being the remnant of anticyclonic (cyclonic) synoptic scale wave breaking. This study examines the potential of anticyclonic (AB) and cyclonic wave breaking (CB) to drive NAO‐like meridional circulation dipoles by investigating the synoptic evolution of AB and CB events in a mid‐latitude eddy‐driven jet in a simplified GCM with zonally uniform basic state. First, a method for the detection of such events from daily isentropic maps of potential vorticity and horizontal deformation is constructed. Then, from the obtained sample of events AB‐ and CB‐composites of the upper and lower tropospheric flow are computed, and a distinct spatial and temporal asymmetry in the response to AB and CB events is found. While from the interaction of two AB events (with a mean lifetime of 2.6 days) a strong and short‐lived positive phase NAO‐like dipole is produced at the surface but not at upper levels, single CB events (4.3 days) are found to drive a strong and more persistent negative phase NAO‐like dipole at upper levels but not at the surface. It is concluded that AB (CB) is not capable of driving a positive (negative) phase NAO‐like dipole individually. However, the results suggest that equivalent barotropic NAO‐like variability may arise from the successive occurrence of AB and CB events. Further, a sensitivity to the strength of the stratospheric polar vortex is found with more (less) frequent AB (CB) events under strong vortex conditions. Copyright © 2009 Royal Meteorological Society
International standards for palm oil
Authors: Cornelius J. A.
Published: January 2009

Abstract and Summary

Crude oil for edible purposes has in the past mainly been sold on the basis of moisture, dirt, and free fatty acid (FFA) content. Within an increasingly competitive market, user requirements with regard to quality characteristics are becoming more closely defined so that the producer can market an oil which can be refined to particular standards of color, taste, consistency, and shelflife at minimum cost to the refiner. Other tests for plam oil quality which have been developed for use over the lqast 20 years include the assessment of bleachability, oxidation level, and oxidative stability. With the prospect of oils with a higher unsaturated acid content from African‐American hybrid palms being produced commercially and the present interest in fractionation, fatty acid composition is likely to become more important quality factor. Progress to date on standard procedures fort the assessment of crudepalm oil quality is reviewed and possible standards for refined, bleached, deodorized, and factionated palm oils are discussed. In this survey of progress to date towards international standards for palm oil, the author has endeavored to provide an overall picture of what has led to the present situation as well as to indicate aims for the future. Much has still to be done in the proper formulation of tests which are acceptable to user and producer, to buyer and seller, and also in the evolution of recognized grades of both crude oils and oils with predictable refining properties giving refined oils of acceptable quality and shelf life when incorporated in the final food products.
Surfactants for producing low interfacial tensions I: Linear alkyl benzene sulfonates
Authors: Doe Peter H. , El‐Emary Mahmoud , Wade William H. , schechter Robert S.
Published: January 2009

Abstract and Summary

The synthesis of a variety of linear alkylbenzene‐sulfonates is described. These materials have been examined for their ability to promote every low interfacial tensions between alkanes, alkylbenzenes, or alkylcyclohexanes and water. Each surfactant gives its lowest tension against a particular member of each of these homologous series. For these surfactant struc‐tures, the magnitude of its minimum tension is determined by the oil phase equivalent alkane carbon number (EACN) and structure and is largely independent of the particular surfactant used. The position of the minimum tension within the alkane series varies in a systematic and predictable manner. The significance of these results for tertiary oil recovery by surfactant flooding is discussed.
Manufacture of palm kernel oil using the traditional coconut oil processing system
Authors: Banigo E. O. I. , Ogunlesi A. , Ofi O.
Published: January 2009

Abstract and Summary

The traditional processing system of coconut oil, comprising grating of coconut meats, extraction with boiling water, cooling, followed by skimming off the cream, and heating it to dryness to give coconut oil, has been adapted for the manufacture of palm kernel oil. Palm kernels were crushed in a laboratory hammer mill, extracted with several lots of boiling water, cooled, the resulting cream skimmed off, and heated to dryness to yield palm kernel oil. A comparison of existing traditional and new adapted processing systems showed that the yield palm kernel oil obtained in both cases was about the same. Furthermore, the specific gravity, melting point, refractive index, and saponification number were similar, but the moisture content, acid value, color, and odor were dissimilar.
Evaluation of Trauma Care Resources in Health Centers and Referral Hospitals in Cambodia
Authors: Nakahara Shinji , Saint Saly , Sann Sary , Phy Radian , Ichikawa Masao , Kimura Akio , Eng Lycheng , Yoshida Katsumi
Published: January 2009

Background

The aim of this study was to evaluate the available resources for trauma care at health centers (HCs) and referral hospitals (RHs) in rural Cambodia and to examine whether the resources at HCs are allocated on the basis of actual need based on the referral distance and number of severely injured patients referred to RHs.

Methods

We conducted a cross‐sectional facility survey by phone interview or mail using structured questionnaires at nationally representative samples of 85 HCs and 17 RHs from December 2006 to April 2007. The questionnaire included a modified checklist of the guidelines for essential trauma care as well as questions on distance for referral and the number of injured patients received and referred during the last 3 months. We analyzed the association between resource availability at HCs and their need using multivariate linear regression.

Results

Median (interquartile range) numbers of available resources at HCs and RHs were 25.5 (22.0–27.5) and 35 (28–41) among 37 and 62 essential items, respectively. Basic equipment, including both consumable supplies and durable devices and life‐saving knowledge/skills, were not satisfactory at either HCs or RHs. A longer distance to the RH was associated with more knowledge/skills but not with equipment supplies; the number of referred patients was not associated with equipment or knowledge/skills.

Conclusions

Staff training emphasizing life‐saving knowledge/skills and better organization and planning to supply physical resources are needed. There is a gap between resource allocation and need, which should be addressed through clear policies to prioritize remote areas and to allocate resources based on reliable injury data.
A defense of universalism: With a critique of particularism in Chinese culture
Authors: Dunhua ZHAO
Published: January 2009

Universalism can be defined as the belief in the universal application of certain knowledge, world-views and value-views. Universalism has often been confused with Occident-centrism, due to the fact that the latter was used to justify the former, which confused the content of a thought with the social condition that gave rise to the thought. For many years, clarifications of this confusion have been made in sociology of knowledge, relativism and skepticism. Yet, the particularistic conclusion thus reached has led to more confusion, namely, that between the intrinsic criterion for truth and the practical application of thought. China, with its long tradition of Sino-centrism, has recently shown a movement towards particularism, characterized by a search for national and cultural superiority by “returning to the source”. In today’s academic circles, some particularist themes are taken for granted, and believed to be true, but cannot be proved with rational examination. The particularistic claims to the “self grounded”, “self-featured” and “self-located” tradition of Chinese culture jointed with the post-modernism, neo-leftist movement of anti-globalization in the West, are not only harmful in practice, but also impotent in theory. The propaganda against the hegemony of Western discourse should be analyzed with questioning which hegemony and whose discourse.
The double meanings of “essence”: The natural and humane sciences — A tentative linkage of Hegel, Dilthey, and Husserl
Authors: Shiying ZHANG
Published: January 2009

Early in Aristotle’s terminology, and ever since, “essence” has been conceived as having two meanings, namely “universality” and “individuality”. According to the tradition of thought that has dominated throughout the history of Western philosophy, “essence” unequivocally refers to “universality”. As a matter of fact, however, “universality” cannot cover Aristotle’s definition and formulation of “essence”: Essence is what makes a thing “happen to be this thing.” “Individuality” should be the deep meaning of “essence”. By means of an analysis of some relevant Western thoughts and a review of cultural realities, it can be concluded that the difference between the attitudes toward things of the natural sciences and the humane sciences mainly lies in the fact that the former focus on the pursuit of universal regularity, whereas the latter go after the value and significance of human life. The movement from natural things to cultural things is a process in which essence shifts from universality to individuality. It is the author’s contention that what should be stressed in the fields of human culture and society is the construction of an ideal society that is “harmonious yet not identical”, on the basis of respecting and developing individual peculiarity and otherness.
Synthesis of Monodisperse Nanocrystals via Microreaction: Open-to-Air Synthesis with Oleylamine as a Coligand
Authors: Yang Hongwei , Fan Ningning , Luan Weiling , Tu Shan-tung
Published: January 2009

Microreaction provides a controllable tool to synthesize CdSe nanocrystals (NCs) in an accelerated fashion. However, the surface traps created during the fast growth usually result in low photoluminescence (PL) efficiency for the formed products. Herein, the reproducible synthesis of highly luminescent CdSe NCs directly in open air was reported, with a microreactor as the controllable reaction tool. Spectra investigation elucidated that applying OLA both in Se and Cd stock solutions could advantageously promote the diffusion between the two precursors, resulting in narrow full-width-at-half maximum (FWHM) of PL (26 nm). Meanwhile, the addition of OLA in the source solution was demonstrated helpful to improve the reactivity of Cd monomer. In this case, the focus of size distribution was accomplished during the early reaction stage. Furthermore, if the volume percentage (vol.%) of OLA in the precursors exceeded a threshold of 37.5%, the resulted CdSe NCs demonstrated long-term fixing of size distribution up to 300 s. The observed phenomena facilitated the preparation of a size series of monodisperse CdSe NCs merely by the variation of residence time. With the volume percentage of OLA as 37.5% in the source solution, a 78 nm tuning of PL spectra (from 507 to 585) was obtained through the variation of residence time from 2 s to 160 s, while maintaining narrow FMWH of PL (26–31 nm) and high QY of PL (35–55%).
Comparative study of DNA damage and repair in head and neck cancer after radiation treatment
Authors: Rusin Pawel , Olszewski Jurek , Morawiec‐Bajda Alina , Przybylowska Karolina , Kaczmarczyk Dariusz , Golinska Aleksandra , Majsterek Ireneusz
Published: January 2009

We compared DNA damage and the efficacy of its repair after genotoxic treatment with γ‐radiation of lymphocytes and tissue cells isolated from patients with squamous cell carcinoma of head and neck (HNSCC) and healthy donors. Thirty‐seven subjects with HNSCC and 35 healthy donors were enrolled in the study. The extent of DNA damage including oxidative lesions and efficiency of the repair were examined by alkaline comet assay. HNSCC cancer cells were more sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by γ‐radiation were repaired less effectively in metastasis of HNSCC than in healthy controls. The differences in radiation sensitivity of cancer and control cells suggested that DNA repair might be critical for HNSCC treatment. We conclude that γ‐radiation might be considered as an effective therapeutic strategy for head and neck cancers, including patients in advanced stage of the disease with clear evidence of metastasis.
Suppression of the ecdysteroid‐triggered growth arrest by a novel Drosophila membrane steroid binding protein
Authors: Fujii-Taira Ikuko , Yamaguchi Shinji , Iijima Ryoko , Natori Shunji , Homma Koichi J.
Published: January 2009

Ecdysteroid is a crucial steroid hormone in insects, especially during metamorphosis. Here, we show that the Drosophila membrane steroid binding protein (Dm_MSBP) is a novel structural homolog of the vertebrate membrane‐bound receptor component for progesterone. Dm_MSBP exhibited binding affinity to ecdysone when expressed on the cell surface of Drosophila S2 cells. In S2 cells, the stable overexpression of Dm_MSBP suppressed the growth arrest triggered by 20‐hydroxyecdysone and prevented the temporal activation of extracellular signal‐regulated kinase proteins. These results suggest that Dm_MSBP is a membranous suppressor to ecdysteroid and blocks the signaling by binding it in extracellular fluid.
Vitronectin promotes oligodendrocyte differentiation during neurogenesis of human embryonic stem cells
Authors: Gil Jung-Eun , Woo Dong-Hun , Shim Joong-Hyun , Kim Sung-Eun , You Hyun-Ju , Park Sung-Hye , Paek Sun Ha , Kim Suel-Kee , Kim Jong-Hoon
Published: January 2009

We demonstrate enhanced differentiation of oligodendrocytes during neurogenesis of human embryonic stem cells (hESCs) using an extracellular matrix protein, vitronectin (VN). We show that VN is expressed in the ventral part of the developing human spinal cord. Combined treatment of retinoic acid, sonic hedgehog, and noggin in the presence of VN allows hESCs to differentiate into O4‐positive oligodendrocytes. Particularly, VN profoundly promotes the derivation of oligodendrocyte progenitors that proliferate and differentiate into oligodendrocytes in response to mitogenic and survival factors. These results support the beneficial effect of VN on oligodendrocytic differentiation of hESCs.
The crystal structure of C176A mutated [Fe]‐hydrogenase suggests an acyl‐iron ligation in the active site iron complex
Authors: Hiromoto Takeshi , Ataka Kenichi , Pilak Oliver , Vogt Sonja , Stagni Marco Salomone , Meyer-Klaucke Wolfram , Warkentin Eberhard , Thauer Rudolf K. , Shima Seigo , Ermler Ulrich
Published: January 2009

[Fe]‐hydrogenase is one of three types of enzymes known to activate H2. Crystal structure analysis recently revealed that its active site iron is ligated square‐pyramidally by Cys176‐sulfur, two CO, an “unknown” ligand and the sp2‐hybridized nitrogen of a unique iron–guanylylpyridinol‐cofactor. We report here on the structure of the C176A mutated enzyme crystallized in the presence of dithiothreitol (DTT). It suggests an iron center octahedrally coordinated by one DTT‐sulfur and one DTT‐oxygen, two CO, the 2‐pyridinol's nitrogen and the 2‐pyridinol's 6‐formylmethyl group in an acyl‐iron ligation. This result led to a re‐interpretation of the iron ligation in the wild‐type.
Spatiotemporal within-plant distribution of the spider miteTetranychus urticaeand associated specialist and generalist predators
Authors: Walzer A. , Moder K. , Schausberger P.
Published: January 2009

Predators are important determinants of the spatiotemporal distribution of prey within a given habitat. The predator effects may vary with diet specialisation, the associated risk posed to prey and, if multiple predators are present, the predator-predator interactions. We examined the spatiotemporal distribution of the herbivorous spider miteTetranychus urticaeand the associated specialist and generalist predatorsPhytoseiulus persimilisandNeoseiulus californicuson bean plants.Tetranychus urticaeis a key pest on numerous agricultural crops. Both predators are used singly and in combination for biological control of spider mites. Population development and within-plant distribution of the spider mites and the predators were compared among five treatments:T. urticaewithout predators, with either predator alone and with both predators in combination at full and half densities. The spider mites were suppressed to zero density in both predator combination treatments but not in the single predator treatments. The predators determined the spatiotemporal distribution of the spider mites through density- and behaviour-mediated effects, and these effects were linked to diet specialisation. The specialistP. persimilisexerted stronger density-mediated effects on the spider mite distribution than did the generalistN. californicus. Either predator induced in the spider mites early upward migration on plants. The predators also affected each other's distribution. The aggregation level ofN. californicuswas lowered byP. persimilisbut notvice versa. In combination, the predators were more dispersed than when alone, reducing the predator-free space and leading to the local extinction ofT. urticae.
Molecular detection of benzimidazole resistance in Haemonchus contortus using real-time PCR and pyrosequencing
Authors: von SAMSON-HIMMELSTJERNA G. , WALSH T. K. , DONNAN A. A. , CARRIÈRE S. , JACKSON F. , SKUCE P. J. , ROHN K. , WOLSTENHOLME A. J.
Published: January 2009

Benzimidazoles (BZ) are widely used to treat parasitic nematode infections of humans and animals, but resistance is widespread in veterinary parasites. Several polymorphisms in β-tubulin genes have been associated with BZ-resistance. In the present study, we investigated β-tubulin isotype 1 sequences of 18 Haemonchus contortus isolates with varying levels of resistance to thiabendazole. The only polymorphism whose frequency was significantly increased in the resistant isolates was TTC to TAC at codon 200. Real-time PCR (using DNA from 100 third-stage larvae, L3s) and pyrosequencing (from DNA from 1000–10 000 L3s) were used to measure allele frequencies at codon 200 of these isolates, producing similar results; drug sensitivity decreased with increasing TAC frequency. Pyrosequencing was also used to measure allele frequencies at positions 167 and 198. We showed that such measurements are sufficient to assess the BZ-resistance status of most H. contortus isolates. The concordance between real-time PCR and pyrosequencing results carried out in different laboratories indicated that these tools are suitable for the routine diagnosis of BZ-resistance in H. contortus. The molecular methods were more sensitive than the ‘egg hatch test’, and less time-consuming than current in vivo- or in vitro-anthelmintic resistance detection methods. Thus, they provide a realistic option for routine molecular resistance testing on farms.
Population dynamics ofAntarctophthirus microchir(Anoplura: Echinophthiriidae) in pups from South American sea lion,Otaria flavescens, in Northern Patagonia
Authors: AZNAR F. J. , LEONARDI M. S. , BERÓN VERA B. , VALES D. G. , AMEGHINO S. , RAGA J. A. , CRESPO E. A.
Published: January 2009

We analysed population dynamics of the louseAntarctophthirus microchirin pups of the South American sea lion,Otaria flavescens, at the Punta León rookery (Argentina) over a period of 2 years. A total of 136 pups were aged and marked at the beginning of the lactation period ashore, then sampled for lice at different times within 30 days. Sampling was restricted to the chest and belly, two sites where lice were especially abundant. This concentration on ventral areas might protect lice from thermal stress in the austral summer. Infestation patterns in pups ⩽3 days old suggested that the potential for transmission increased from first nymphs to adults. Population trends of each instar with pup age, based on standardised values of abundance, were conserved between years, reflecting the basic dynamics of recruitment and reproduction. However, trends based on log-transformed abundances varied significantly between years; apparently, environmental conditions affected growth of lice populations differently each year. Stage-based deterministic models for population growth ofA. microchirsuggested generation times from 18 to 23 days. Accordingly, only 2 lice generations might be produced before pups start going to the sea. Shortening the cycle to accommodate a third generation might be risky, whereas a 2-generation cycle might at least result in larger females producing higher numbers of viable offspring.
Identification and molecular characterization of numerous Histomonas meleagridis proteins using a cDNA library
Authors: BILIC I. , LEBERL M. , HESS M.
Published: January 2009

Histomonas meleagridis is a protozoan parasite of various galliform birds causing a type of enterohepatitis termed histomonosis or ‘blackhead disease’. Due to the ban of chemotherapeutic substances and an increase in free-range poultry production, histomonosis is currently a re-emerging disease. So far limited molecular knowledge is available. In the present work, mRNAs coding for antigenic proteins of H. meleagridis were identified. For this purpose, a cDNA expression library was constructed from a mono-eukaryotic culture of H. meleagridis. The library was screened with polyclonal rabbit serum raised against purified H. meleagridis trophozoites. Polyclonal rabbit serum specifically recognized the same major H. meleagridis antigens as chicken and turkey sera originating from animal trials, but displayed a significantly lower bacteria-dependent background signal. After 2 rounds of screening, a total of 95 positive clones were sequenced. Bioinformatics analyses were performed on nucleotide and deduced amino acid sequences, identifying 37 unique clones. Based on the homology to other protozoan parasites, mostly Trichomonas vaginalis, the clones were grouped according to functional aspects: structural proteins, possible surface proteins, oxygen reducing proteins, ribosomal proteins, protein kinases and various other intracellular proteins.
Sensitivity of pooled serum testing for screening antibody of schistosomiasis japonica by IHA in a mountainous area of Yunnan, China
Authors: JIA X. M. , SRIPLUNG H. , CHONGSUVIVATWONG V. , GEATER A.
Published: January 2009

Pooled sample testing (PST) as a strategy for avoiding testing the majority of individual negative samples has been proposed for screening of diseases in low prevalence areas. There has been no standard guideline for PST in screening ofSchistosoma japonicuminfection of Yunnan, China. To document the optimum pool size with acceptable sensitivity of PST for screening ofSchistosoma japonicuminfection in this setting, an experimental pooling of each of 31 positive sera by IHA with various numbers of 24 negative sera was done. The results were used to create a statistical model which was subsequently used for simulation to predict sensitivity of the pooled serum tests in the population with varying prevalence and pool size. We found that to keep the sensitivity of PST above 90%, 1:05 should be the maximum dilution, that is, the optimum pool size should not be greater than 6. Antigen will have rather little interference if the prevalence of infection is low e.g. 1% or the antigen:antibody ratio is 1:100 or below. Pooled serum testing by IHA is an acceptable sensitive method for detecting antibody forSchistosoma japonicuminfection in this area.
Impaired inhibitory control is associated with higher-order repetitive behaviors in autism spectrum disorders
Authors: Mosconi M. W. , Kay M. , D'Cruz A.-M. , Seidenfeld A. , Guter S. , Stanford L. D. , Sweeney J. A.
Published: January 2009

Background

Impairments in executive cognitive control, including a reduced ability to inhibit prepotent responses, have been reported in autism spectrum disorders (ASD). These deficits may underlie patterns of repetitive behaviors associated with the disorder.

Method

Eighteen individuals with ASD and 15 age- and IQ-matched healthy individuals performed an antisaccade task and a visually guided saccade control task, each with gap and overlap conditions. Measures of repetitive behaviors were obtained using the Autism Diagnostic Inventory – Revised (ADI-R) and examined in relation to neurocognitive task performance.

Results

Individuals with an ASD showed increased rates of prosaccade errors (failures to inhibit prepotent responses) on the antisaccade task regardless of task condition (gap/overlap). Prosaccade error rates were associated with the level of higher-order (e.g. compulsions, preoccupations) but not sensorimotor repetitive behaviors in ASD.

Conclusions

Neurocognitive disturbances in voluntary behavioral control suggest that alterations in frontostriatal systems contribute to higher-order repetitive behaviors in ASD.
The Electrostatic Energy of a Two-Dimensional System
Authors: Chambers LL. G.
Published: January 2009

The use of the complex variable z( = x + iy) and the complex potential W(= U + iV) for two-dimensional electrostatic systems is well known and the actual system in the (x, y) plane has an image system in the (U, V) plane. It does not seem to have been noticed previously that the electrostatic energy per unit length of the actual system is simply related to the area of the image domain in the (U, V) plane.
Linear Partial Differential Equations with Constant Coefficients: an Elementary Proof of an Existence Theorem
Authors: Parsons D. H.
Published: January 2009

We consider a linear partial differential equation with constant coefficients in one dependent and m independent variables, the right-hand side being zero,

P being a symbolic polynomial in D1, …, Dm. If P can be decomposed into two factors, so that the equation can be written

it is evident that the sum of any solution of

and any solution of

is also a solution of (1).
A Note on Gamma Functions
Authors: Watson G. N.
Published: January 2009

Various improvements in the formula

which was discovered by Wallis in 1669, were studied by D. K. Kazarinoff in No. 40 of these Notes (December 1956).
Linkages for the Trisection of an Angle and Duplication of the Cube
Authors: Stokes G. D. C.
Published: January 2009

In this note some linkage systems for trisecting an angle and for finding the cube root of a number are described. The models are easily made and are of considerable pedagogic value
Some Properties of the Zeros of Bessel Functions
Authors: Chambers Ll. G.
Published: January 2009

Let jnm be the mth positive zero of Jn(x) (n not necessarily integral). Then Relton (1), p. 59, has conjectured from numerical considerations that
Morphodynamic regime of gravel bed, single‐thread meandering rivers
Authors: Zolezzi G. , Luchi R. , Tubino M.
Published: January 2009

This work attempts to link theoretical and experimental findings on the issue of two‐dimensional morphodynamic influence with field data from natural single‐thread rivers. Theoretical and experimental work has shown that two‐dimensional planform and bed deformation waves can propagate both upstream and downstream within single‐thread meandering rivers. The existence of upstream influence is controlled by the value of channel aspect ratio with respect to a threshold that is determined by reach‐averaged characteristics and by the evolutionary state of a given river section. We explore the predictions of a mechanistic meander simulation model based on the input of field data referring to more than 100 gravel bed rivers in order to quantify the regime of morphodynamic influence that can be expected in these streams. The analysis points out how the predicted morphodynamic regime of a given reach can be controlled by the bankfull aspect ratio and the Shields stress. Differences within the data set suggest an autogenic tendency of gravel bed rivers to behave superresonantly, while environmental factors like denser vegetation and reduced gravel supply tend to promote the subresonant regime. Moreover, the autogenic tendency of developing meanders to continuously modify their sinuosity and to consequently reduce the down‐channel slope almost invariably promotes transition from the superresonant to the subresonant regime.
Altitude of Saturn's aurora and its implications for the characteristic energy of precipitated electrons
Authors: Gérard J.‐C. , Bonfond B. , Gustin J. , Grodent D. , Clarke J. T. , Bisikalo D. , Shematovich V.
Published: January 2009

Images of Saturn's aurora at the limb have been collected with the Advanced Camera for Surveys on board the Hubble Space Telescope. They show that the peak of Saturn's nightside emission is generally located 900–1300 km above the 1‐bar level. On the other hand, methane and H2 columns overlying the aurora have been determined from the analysis of FUV and EUV spectra, respectively. Using a low‐latitude model, these columns place the emission layer at or above 610 km. One possibility to solve this apparent discrepancy between imaging and spectral observations is to assume that the thermospheric temperature in the auroral region sharply increases at a higher pressure level than in the low‐latitude regions. Using an electron transport code, we estimate the characteristic energy of the precipitated electrons derived from these observations to be in the range 1–5 keV using a low latitude model and 5–30 keV in case of the modified model.
Timing and localization of ionospheric signatures associated with substorm expansion phase onset
Authors: Rae I. Jonathan , Mann Ian R. , Murphy Kyle R. , Milling David K. , Parent Adrienne , Angelopoulos Vassilis , Frey Harald U. , Kale Andy , Watt Clare E. J. , Mende Stephen B. , Russell Christopher T.
Published: January 2009

In this paper, we present case studies of the optical and magnetic signatures of the characteristics of the first minute of substorm expansion phase onset observed in the ionosphere. We find that for two isolated substorms, the onset of magnetic pulsations in the 24–96 s period wavelet band are colocated in time and space with the formation and development of small‐scale optical undulations along the most equatorward preexisting auroral arc prior to auroral breakup. These undulations undergo an inverse spatial cascade into vortices prior to the release of the westward traveling surge. We also present a case study of a multiple activation substorm, whereby discrete onsets of ULF wave power above a predetermined quiet time threshold are shown to be associated with specific optical intensifications and brightenings. Moreover, in the multiple activation substorm event, we show that neither the formation of the small‐scale undulations nor the formation of similar structures along a north–south aligned arc is sufficient to produce auroral breakup associated with expansion phase onset. It is only ∼10 min after these two disparate activation regions initiate that auroral breakup and the subsequent formation of a westward traveling surge occur. We discuss the implications of these results in terms of the triggering mechanisms likely to be occurring during these specific events.
Comparison of airborne in situ measurements and Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals of cirrus cloud optical and microphysical properties during the Midlatitude Cirrus Experiment (MidCiX)
Authors: Davis Sean M. , Avallone Linnea M. , Kahn Brian H. , Meyer Kerry G. , Baumgardner Darrel
Published: January 2009

During the Midlatitude Cirrus Experiment (MidCiX), in situ measurements of cirrus cloud microphysical properties were made from aboard the NASA WB‐57F aircraft in conjunction with Terra and Aqua satellite overpasses. These in situ data are directly compared to retrievals of cirrus visible optical thickness (τ), effective size (De), and ice water path (IWP) from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard Terra and Aqua. The MODIS data considered here include both the operational retrieval (MOD06) and visible optical thickness retrieved from the 1.38‐μm channel. Instruments aboard the WB‐57F included three bulk probes for measuring ice water content (IWC), a cloud integrating nephelometer for measuring the visible extinction coefficient (β), and four optical particle probe instruments from which β and De are inferred. In situ β (IWC) data taken during vertical spiral profiles through cirrus are integrated to get τ (IWP) for comparison with MODIS values, and a methodology for comparing satellite and aircraft data is developed and illustrated using several case studies from MidCiX. It is found that the presence of cirrus overlapping low cloud layers significantly biases the MODIS operational τ to high values. For single‐layer cirrus cases, the in situ IWP agree with MODIS values to within 20%, on average. The in situ τ/De differ from MODIS values in a manner that is roughly consistent with previous claims of particle shattering on aircraft inlets, although the magnitude of the differences is less than expected, and biases in the MODIS retrievals cannot be ruled out.
Evidence for northward expansion of Antarctic Bottom Water mass in the Southern Ocean during the last glacial inception
Authors: Govin Aline , Michel Elisabeth , Labeyrie Laurent , Waelbroeck Claire , Dewilde Fabien , Jansen Eystein
Published: January 2009

We investigated deep water changes in the Southern Ocean during the last glacial inception, in relationship to surface hydrology and global climatology, to better understand the mechanisms of the establishment of a glacial ocean circulation. Changes in benthic foraminiferal δ13C from three high‐resolution cores are compared and indicate decoupled intermediate and deep water changes in the Southern Ocean. From the comparison with records from the North Atlantic, South Atlantic, and the Southern Ocean, we show that the early southern deep water δ13C drop observed at the MIS 5.5–5.4 transition occurred before any significant reduction of North Atlantic Deep Water ventilation. We propose that this drop is linked to the northward expansion of poorly ventilated Antarctic Bottom Water (AABW) mass in the Southern Ocean. Associated with an early cooling in the high southern latitudes, the westerly winds and surface oceanic fronts would migrate equatorward, thus weakening the upwelling of Circumpolar Deep Waters. Reduced heat brought to Antarctic surface waters would enhance sea ice formation during winters and the deep convection of cold and poorly ventilated AABW.
Time-Course of Cerebral Perfusion and Tissue Oxygenation in the First 6 h after Experimental Subarachnoid Hemorrhage in Rats
Authors: Westermaier Thomas , Jauss Alina , Eriskat Jörg , Kunze Ekkehard , Roosen Klaus
Published: January 2009

Present knowledge about hemodynamic and metabolic changes after subarachnoid hemorrhage (SAH) originates from neuromonitoring usually starting with aneurysm surgery and animal studies that have been focusing on the first 1 to 3 h after SAH. Most patients, however, are referred to treatment several hours after the insult. We examined the course of hemodynamic parameters, cerebral blood flow, and tissue oxygenation (ptiO2) in the first 6 h after experimental SAH. Sixteen Sprague–Dawley rats were subjected to SAH using the endovascular filament model or served as controls ( n = 8). Bilateral local cortical blood flow, intracranial pressure, cerebral perfusion pressure, and ptiO2 were followed for 6 h after SAH. After induction of SAH, local cortical blood flow rapidly declined to 22% of baseline and returned to 80% after 6 h. The decline of local cortical blood flow markedly exceeded the decline of cerebral perfusion pressure. ptiO2 declined to 57%, recovered after 2 h, and reached ≥140% of baseline after 6 h. Acute vasoconstriction after SAH is indicated by the marked discrepancy of cerebral perfusion pressure and local cortical blood flow. The excess tissue oxygenation several hours after SAH suggests disturbed oxygen utilization and cerebral metabolic depression. Aside from the sudden increase of intracranial pressure at the time of hemorrhage and delayed cerebral vasospasm, the occurrence of acute vasoconstriction and disturbed oxygen utilization may be additional factors contributing to secondary brain damage after SAH.
Reputation, authority and incentives. Or: How to get rid of the Impact Factor
Authors: Brembs Björn , Binfield Peter
Published: January 2009

A short intro into the impact factor and its limitations and potential successors.
Structural analysis of outer membrane beta-stranded porins using B-factor
Authors: Kumar Abhishek , Krishnaswamy S
Published: January 2009

Computational and statistical analysis has formed a large component of the biophysical efforts put forth to understand protein structure and function, due to the diversity and complexity of their structure. Outer membrane proteins form a diverse and complex set of proteins. Of these, porins that allow passage of molecules across the membrane interface have been analyzed here from a biophysical and structural perspective. The objective of this study is to analyze the structural organization of porins using atomic temperature factor as a parameter. Generally atomic temperature factors of molecules from crystal structures indicate the degree of mobility or disorder seen in the crystal structure. As good crystal structures have lesser possibilities of errors so there is lesser chance that errors are playing roles in temperature factors. Structures of six porins (four 16-stranded beta barrel porins and two 8-stranded beta barrel porins) were taken from the PDB for the analysis based on resolution and R-factor. Programs and scripts were written for extracting the temperature factors for the beta strands, loops and turns so that the analysis could be done for different atom-types and residue-types. The residue distribution and mobility distribution was found to be characteristic of each of the porins. The mobility and residue distribution amongst the secondary structural elements were found to follow the level of homology at the sequence and structural level. The loops that had defined functional roles in structural terms were found to have lower temperature factors than the other loops. The turn regions that are thought to face the periplasmic region in the cell, showed higher temperature factors. For both the 16 stranded and the 8-stranded barrels it was found one part of the barrel (the lower wall or 'inner' wall comprising the trimer interface in the case of the 16-stranded barrels) was more rigid and the other half of the barrel (the higher or 'outer' wall) showed more mobility as seen from the temperature factors. This seems to be an intrinsic structural component of the beta barrels.
Adiabatic and nonadiabatic dissociation of ethyl radical
Authors: Hostettler Jonas M. , Bach Andreas , Chen Peter
Published: January 2009

Direct ab initio molecular dynamics using the trajectory surface hopping method with Tully’s fewest switches simulates the photodissociation dynamics of ethyl radical, C2H5, following electronic excitation to the Ã-state. Nonadiabatic dissociation dominates and produces ground state ethylene and fast hydrogen atoms with an anisotropic angular distribution. Surface hopping also generates hot ground state ethyl radicals followed ultimately by unimolecular dissociation to C2H4+H. The calculated excited state lifetime and the product recoil energy distribution obtained from an ensemble of trajectories are consistent with previous experiments and suggest that a strictly nonadiabatic mechanism can account for nonradiative decay. This process is in competition with adiabatic dissociation producing electronically excited state ethylene and H, a dissociation channel that has not yet been experimentally observed. The branching ratio between adiabatic and nonadiabatic dissociation pathways depends sensitively on the quality of the potential energy surfaces. At the multireference configuration interaction with singles and doubles level of theory, 15% of all trajectories dissociate adiabatically.
Calorimetric and dielectric study of organic ferroelectrics, phenazine-chloranilic acid, and its bromo analog
Authors: Amano Masakazu , Yamamura Yasuhisa , Sumita Masato , Yasuzuka Syuma , Kawaji Hitoshi , Atake Tooru , Saito Kazuya
Published: January 2009

The heat capacities of single crystals of organic ferroelectric complexes phenazine-chloranilic acid (Phz-H2ca) and phenazine-bromanilic acid (Phz-H2ba) were measured. At temperatures below those of the reported ferroelectric phase transitions, heat capacity anomalies due to successive phase transitions were found in both complexes. Excess entropies involved in the low-temperature successive phase transitions are much larger than those due to the ferroelectric phase transitions. The temperature dependence of the complex dielectric constants showed the existence of multiple dielectric relaxation modes in both complexes and their deuterated analogs (Phz-D2ca and Phz-D2ba). We discuss the possibility of concerted hopping of neighboring protons within a hydrogen-bonded chain while taking into account the one-dimensional nature of the chain.
Direct observation of time-dependent photoluminescence spectral shift in CdS nanoparticles synthesized in polymer solutions
Authors: Mandal Debabrata , Hosoi Haruko , Chatterjee Uma , Tahara Tahei
Published: January 2009

Direct observation of time-resolved emission spectra (TRESs) of cadmium sulfide nanoparticles in polymer solutions was carried out with picosecond resolution using a streak camera. The TRESs were found to undergo a pronounced time-dependent Stokes shift, eventually coinciding with the steady-state photoluminescence spectra within an ∼40 ns delay time. Moreover, ∼90% of the shift was complete within the first 1 ns after excitation, in contrast to the fact that overall photoluminescence involves very long time constants of 10–100 ns. The observed Stokes shift dynamics was very similar in CdS nanoparticles stabilized in two very different types of polymer solutions. Thus the solvent and/or polymeric stabilizer appeared to have a minimal effect on the shift. We propose that the relaxation proceeds through an internal mechanism involving the fast decay of high-energy traps into relatively slow-decaying low-energy traps. Time-dependent photoluminescence anisotropy experiments also revealed an ∼1 ns decay component appearing only in the higher-energy end of the photoluminescence spectrum. Because this time constant is too short to represent rotational diffusion of the nanometer-sized particles, it was associated with the rapid relaxation of the high-energy trap states.
A finite-difference implementation of the Caldeira–Leggett master equation
Authors: Grossmann Frank , Koch Werner
Published: January 2009

The Caldeira–Leggett master equation for dissipative quantum dynamics has predominantly been implemented in phase space, where it plays the role of a quantum Fokker–Planck equation. Here we demonstrate the feasibility of a pure coordinate space implementation in the case of intermediate damping strength and temperature, for times long enough to observe thermal equilibration. After a thorough numerical investigation of the analytically solvable harmonic oscillator case, a Morse oscillator model is studied. This is a case in which a quantal phase space approach would be difficult to implement and we show how analytical results for thermal averages are reproduced to a surprisingly high degree.
Additive and nonadditive models of vapor-liquid equilibrium in CO2 from first principles
Authors: Oakley Mark T. , Wheatley Richard J.
Published: January 2009

We describe quantum-chemical calculations on dimers of CO2 and use the results to develop first-principles models for Gibbs ensemble Monte Carlo simulations of the phase coexistence curve. Isotropic pairwise potentials are insufficient to model the phase behavior and overestimate the binding in liquid CO2 by 4 kJ mol−1. An anisotropic treatment of the atoms in the pairwise potential reduces the strength of the binding by ∼0.5 kJ mol−1. We use ab initio calculations on trimers of CO2 to assess the strength of nonadditive interactions. Including nonadditive dispersion in Gibbs ensemble simulations gives an enthalpy of vaporization within 1.5 kJ mol−1 of the experimental value over a wide range of temperatures.