bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of MPA amide for the assignment of absolute configuration of a sterically hindered cyclic secondary amine by ‘mix and shake’ NMR method
Authors: Gao Jinhai , Haas Hansjoerg , Wang Kate Yaping , Chen Zhuoliang , Breitenstein Werner , Rajan Srinivasan
Published: December 2007

We present here a new method using methoxyphenylacetic acid (MPA) as the chiral derivatizing agent (CDA) for the assignment of absolute configuration of cyclic secondary amines. The MPA amides were prepared using the purification‐free ‘mix and shake’ method. A detailed conformational analysis for the two diastereomeric amides was conducted by 2D NMR experiments and molecular mechanics calculations. We have established that, in the most stable conformation of each syn rotamer of MPA amides, the H‐α in the MPA moiety is oriented toward the bulky substituent group at the asymmetric carbon in the chiral amine, presumably to avoid steric and/or electrostatic interactions. The observed NMR data were correlated with the conformational model to allow unambiguous assignment of absolute configuration of secondary amines. The results demonstrate that the MPA can be used as a useful CDA in the case of sterically crowded cyclic secondary amines from which the MTPA amides are usually difficult to make. Copyright © 2008 John Wiley & Sons, Ltd.
A multinuclear solid‐state magnetic resonance study of the interactions between the inorganic and organic coatings of BaSO4 submicronic particles
Authors: Borsacchi S. , Geppi M. , Veracini C. A. , Lazzeri A. , Di Cuia F. , Geloni C.
Published: December 2007

Silica‐coated BaSO4submicronic particles, modified on the surface by treatment with stearic acid, have been characterized by means of 29Si, 13C, and 1H magic‐angle‐spinning (MAS) high‐resolution techniques, and low‐resolution 1H‐FID analysis. Two types of adsorbed water were identified; adsorbed either inside or on the surface of BaSO4, most of the latter being removed by the silica coating. Evidences of silica–stearic acid interactions were found involving either carboxylic acid or carboxylate functional groups, and occurring by means of hydrogen and/or covalent bonds. Stearic acid was present as monolayer only, its chain being mostly rigid, even though a small fraction was subjected to fast inter‐conformational motions. Copyright © 2008 John Wiley & Sons, Ltd.
Dielectric permittivity and temperature effects on spin–spin couplings studied on acetonitrile
Authors: Sahakyan Aleksandr B. , Shahkhatuni Astghik A. , Shahkhatuni Aleksan G. , Panosyan Henry A.
Published: December 2007

Dielectric permittivity (ε) and temperature effects on indirect spin–spin coupling constants were studied using acetonitrile as a probe molecule. Experiments were accompanied by hybrid DFT (density functional theory) studies, where the solvent was modeled using the polarization continuum model. Owing to its numerous types of J‐couplings, acetonitrile is a very convenient molecule against which various basis sets can be tested or the best basis set can be selected for a given study. The results show reasonable agreement between calculated and experimental values. According to our data, scalar spin–spin coupling constants undergo substantial shifts at lower values of the dielectric constant. Thus J‐coupling values are not transferable between measurements made at differing ε–conditions, and the assumption of the ε‐independence of the J‐coupling can lead to crucial mistakes in experiments using low‐ε media. Dielectric permittivity also causes small geometric fluctuations within the molecule, which themselves can affect J‐coupling values. Examinations of the results computed with frozen and relaxed geometries show that geometry mediation mostly affects the spin‐dipole term of the J‐coupling; hence, for accurate evaluation of the latter, frozen geometries are not acceptable. Another interesting fact revealed is the connection between the solvent dielectric properties and the temperature‐dependence slopes of J‐couplings in corresponding media. Copyright © 2008 John Wiley & Sons, Ltd.
Spectral analysis of 1H coupled 13C spectra of the amino acids: adaptive spectral library of amino acid 13C isotopomers and positional fractional 13C enrichments
Authors: Tiainen Mika , Maaheimo Hannu , Niemitz Matthias , Soininen Pasi , Laatikainen Reino
Published: December 2007

The natural abundance 1H‐coupled 13C NMR spectra of all proteogenic amino acids were measured in D2O at pH* 1. The accurate 1H,13C spin‐spin coupling constants were analyzed using total‐line‐shape fitting. The obtained spectral parameters can be used to establish a spectral library of amino acid 13C isotopomers. The adaptive spectral library principle is introduced and discussed in this article. The simulated spectra can be applied to quantification of 13C isotopomer mixtures of amino acids and, thus, for exploring metabolic pathways. Also a protocol for amino acid 13C isotopomer metabolomic profiling in 13C labeled glucose feeding experiments is outlined. The approach is suggested to give invaluable information about positional fractional 13C enrichments, which are not easily available by any other method. Copyright © 2007 John Wiley & Sons, Ltd.
Two new phenylbutanoids from inner bark of Betula pendula
Authors: Liimatainen Jaana , Sinkkonen Jari , Karonen Maarit , Pihlaja Kalevi
Published: December 2007

Two phenylbutanoids, 7‐{3R‐[(4‐hydroxyphenyl)butyl] β‐glucopyranosid‐O‐6‐yl} 4‐O‐β‐glucopyranosylvanillin and 3‐β‐glucopyranosyloxy‐1‐(4‐hydroxyphenyl)‐butanone were isolated from an aqueous methanol extract of the inner bark of Betula pendula. Their structures were determined by NMR spectroscopy and mass spectrometry. The complete assignment of proton and carbon signals was achieved by 1D and 2D NMR experiments: selective 1D TOCSY, HSQC, HMBC and DQF‐COSY. Copyright © 2007 John Wiley & Sons, Ltd.
Continuous Atom Transfer Radical Polymerization in a Tubular Reactor
Authors: Müller Matthias , Cunningham Michael F. , Hutchinson Robin A.
Published: December 2007

The use of a tubular reactor for conducting living radical polymerizations by atom transfer radical polymerization (ATRP) was investigated. Solution polymerization experiments were performed with styrene and butyl acrylate to elucidate the influence of a continuous reaction process on conversion, molecular weight, and polydispersity compared to batch polymerization experiments. The continuous polymerizations were well controlled. Initial conversion was found to be slightly higher in the tubular reactor than in a batch polymerization run at similar conditions, while number average molecular weight and polydispersity are comparable between the continuous and batch processes. Residence time distribution studies showed the reactor exhibits nearly plug flow behavior.

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Transcriptome and proteome profiling of colon mucosa from quercetin fed F344 rats point to tumor preventive mechanisms, increased mitochondrial fatty acid degradation and decreased glycolysis
Authors: Dihal Ashwin A. , van der Woude Hester , Hendriksen Peter J. M. , Charif Halima , Dekker Lennard J. , IJsselstijn Linda , de Boer Vincent C. J. , Alink Gerrit M. , Burgers Peter C. , Rietjens Ivonne M. C. M. , Woutersen Ruud A. , Stierum Rob H.
Published: December 2007

Quercetin has been shown to act as an anticarcinogen in experimental colorectal cancer (CRC). The aim of the present study was to characterize transcriptome and proteome changes occurring in the distal colon mucosa of rats supplemented with 10 g quercetin/kg diet for 11 wk. Transcriptome data analyzed with Gene Set Enrichment Analysis showed that quercetin significantly downregulated the potentially oncogenic mitogen‐activated protein kinase (Mapk) pathway. In addition, quercetin enhanced expression of tumor suppressor genes, including Pten, Tp53, and Msh2, and of cell cycle inhibitors, including Mutyh. Furthermore, dietary quercetin enhanced genes involved in phase I and II metabolism, including Fmo5, Ephx1, Ephx2, and Gpx2. Quercetin increased PPARα target genes, and concomitantly enhanced expression of genes involved in mitochondrial fatty acid (FA) degradation. Proteomics performed in the same samples revealed 33 affected proteins, of which four glycolysis enzymes and three heat shock proteins were decreased. A proteome‐transcriptome comparison showed a low correlation, but both pointed out toward altered energy metabolism. In conclusion, transcriptomics combined with proteomics showed that dietary quercetin evoked changes contrary to those found in colorectal carcinogenesis. These tumor‐protective mechanisms were associated with a shift in energy production pathways, pointing at decreased cytoplasmic glycolysis and toward increased mitochondrial FA degradation.
Multidimensional chromatography: Validation and efficient fishing for biomarkers and fractions containing them using the VisualCockpit software package
Authors: Cumme Gerhard A. , Kreusch Stefan , Nagel Matthias , Rhode Heidrun
Published: December 2007

2‐D native LC yields thousands of fractions especially when applied to sera of different origin. Checking reproducibility of repeated separation of the same serum or searching for biomarker candidates and fractions containing them requires finding, selection, and comparison of interesting data subsets out of huge data volumes. An innovative software package is applied that markedly enhances simplicity, velocity, and reliability of (i) check of reproducibility of the separation method and (ii) analysis of proteomes pertaining to different disease states.
Characterisation of the plasma membrane subproteome of bloodstream form Trypanosoma brucei
Authors: Bridges Daniel J. , Pitt Andrew R. , Hanrahan Orla , Brennan Kiva , Voorheis H. Paul , Herzyk Pawel , de Koning Harry P. , Burchmore Richard J. S.
Published: December 2007

Proteome analysis by conventional approaches is biased against hydrophobic membrane proteins, many of which are also of low abundance. We have isolated plasma membrane sheets from bloodstream forms of Trypanosoma brucei by subcellular fractionation, and then applied a battery of complementary protein separation and identification techniques to identify a large number of proteins in this fraction. The results of these analyses have been combined to generate a subproteome for the pellicular plasma membrane of bloodstream forms of T. brucei as well as a separate subproteome for the pellicular cytoskeleton. In parallel, we have used in silico approaches to predict the relative abundance of proteins potentially expressed by bloodstream form trypanosomes, and to identify likely polytopic membrane proteins, providing quality control for the experimentally defined plasma membrane subproteome. We show that the application of multiple high‐resolution proteomic techniques to an enriched organelle fraction is a valuable approach for the characterisation of relatively intractable membrane proteomes. We present here the most complete analysis of a protozoan plasma membrane proteome to date and show the presence of a large number of integral membrane proteins, including 11 nucleoside/nucleobase transporters, 15 ion pumps and channels and a large number of adenylate cyclases hitherto listed as putative proteins.
Synthesis of polyisobutylene with arylamino terminal group by combination of cationic polymerization with alkylation
Authors: Zhang Cheng‐Long , Wu Yi‐Xian , Xu Xu , Li Yan , Feng Li , Wu Guan‐Ying
Published: December 2007

The controlled cationic polymerization of isobutylene (IB) initiated by H2O as initiator and TiCl4 as coinitiator was carried out in n‐Hexane/CH2Cl2 (60/40, v/v) mixture at −40 °C in the presence of N,N‐dimethylacetamide (DMA). Polyisobutylene (PIB) with nearly theoretical molecular weight (Mn = 1.0 × 104 g/mol), polydispersity (Mw/Mn) of 1.5 and high content (87.3%) of reactive end groups (tert‐Chlorine and α‐double bond) was obtained. The Friedel‐Crafts alkylation of triphenylamine (TPA) with the above reactive PIB was further conducted at different reactions, such as [TPA]/[PIB], solvent polarity, alkylation temperature, and time. The resultant PIBs with arylamino terminal group were characterized by 1H NMR, UV, and GPC with RI/UV dual detectors. The experimental results indicate that alkylation efficiency (Aeff) increased with increases in [TPA]/[PIB], reaction temperature, and reaction time and with a decrease in solvent polarity. The alkylation efficiency could reach 81.0% at 60/40(v/v) mixture of n‐Hex/CH2Cl2 with [TPA]/[PIB] of 4.49 at 50 °C for 54 h. Interestingly, the synthesis of PIB with arylamino terminal group could also be achieved in one pot by combination of the cationic polymerization of IB initiated by H2O/TiCl4/DMA system with the successive alkylation by further introduction of TPA. Mono‐, di‐ or tri‐alkylation occurred experimentally with different molar ratio of [TPA]/[PIB]. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 936–946, 2008
Polystyrene/Fe3O4 composite latex via miniemulsion polymerization‐nucleation mechanism and morphology
Authors: Luo Ying‐Da , Dai Chi‐An , Chiu Wen‐Yen
Published: December 2007

In this research, oil‐based Fe3O4 nanoparticles were prepared by means of coprecipitation method followed by a surface modification using lauric acid. Oil‐based Fe3O4 could disperse in styrene, and polystyrene/Fe3O4 (PS/Fe3O4) composite particles were prepared via miniemulsion polymerization in the presence of potassium peroxide (KPS) as an initiator, sodium dodecyl sulphate as a surfactant, hexadecane or sorbitan monolaurate(Span 20) as a costabilizer. The effects of Fe3O4 content, homogenization energy, amount of initiator, amount of surfactant and costabilizer on the conversion, size distributions of droplets and latex particles, nucleation mechanism and morphology of composite latex particles were investigated. The results showed that different nucleation mechanisms dominated during the course of reaction when polymerization conditions changed. The most important two key factors to influence the nucleation mechanism were homogenization energy and initiator. High homogenization energy provided critically stabilized size of droplets. Otherwise, secondary nucleation, including micellar and/or homogeneous nucleation, would take place rather than droplet nucleation when a water‐soluble initiator, KPS, was used. It resulted in two populations of latex particles, pure PS particles in smaller size and PS/Fe3O4 composite particles in larger size. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1014–1024, 2008
Long‐term X‐ray stimulated crystallization of poly(N‐methyldodecano‐12‐lactam) in blend with poly(styrene‐stat‐acrylic acid)
Authors: Kratochvíl Jaroslav , Baldrian Josef , Brus Jiří , Sikora Antonín
Published: December 2007

The effect of X‐ray irradiation on crystallization of the blend of poly(N‐methyldodecano‐12‐lactam) (PMDL) with 29.5% of statistical copolymer poly(styrene‐stat‐acrylic acid) (PSAA) was studied using DSC, WAXD, and solid‐state 13C NMR methods. Significant acceleration of crystallization was found in the as‐prepared X‐ray irradiated (XI), that is, WAXD‐measured, samples compared with the nonirradiated (NI) ones. In the XI blend, the incubation period was shortened and crystallization proceeded at significantly higher rate. In the asymptote, after 100–120 days, both NI and XI samples reached the same final crystallinity of about 18%. The second DSC runs indicated that the stimulating effect of X‐ray irradiation was eliminated by heating the sample during the first run. The 13C NMR studies have shown that PMDL chains crystallize exclusively in cis conformation on the CN bond. Both in neat PMDL and in the blend with PSAA, the XI samples contained a significantly higher proportion of cis conformers in amorphous phase than the NI samples. It is suggested that energy absorbed by the sample during the standard WAXD measurement helps overcome the barrier of the trans/cis transition in the PMDL molecules. This opens the way to the formation of a higher number of critical equilibrium nuclei and, finally, results in accelerated crystallization of the XI samples. No irreversible changes were found in the XI samples. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 311–321, 2008
Managing bioremediation of a creosote‐contaminated superfund site by optimizing moisture and temperature in a biopile
Authors: Portier Ralph J. , Iqbal Javed , Metosh‐Dickey Caroline A. , Davis T. M.
Published: December 2007

Soil moisture content and temperature in a contaminated soil biopile equipped with immobilized microbe bioreactors (IMBRs) were optimized during ex situ bioremediation at a creosote‐contaminated Superfund site. Efficiency of remediation during warm summer months without soil‐temperature and moisture optimization was compared with that of cold winter months when corrective measures were applied. Significant reduction (35 percent) in total polycyclic aromatic hydrocarbons (PAHs) was observed, compared to 3.97 percent without corrective measures (p < 0.05). Kinetic rates (KRs) for total PAH removal were significantly enhanced from 3.93 to 50.95 mg/kg/day. KRs for removal of high molecular mass four‐to‐six‐ring PAHs were also significantly enhanced from 70.29 mg/kg/day to 97.45 mg/kg/day ( p < 0.05). Bioremediation of two‐ and three‐ring PAHs increased significantly from 15 percent to 40 percent. Benzo[a]pyrene toxicity equivalent mass (BaPequiv) was significantly reduced by 48 percent with KR of 0.47 mg/kg/day as compared to 22 percent with KR of 0.14 mg/kg/day (p < 0.05). Soil moisture content was enhanced from 15.7 percent to 41.4 percent. © 2007 Wiley Periodicals, Inc.
A “convective” flow biofilter for the biofiltration of contaminants at sub‐low concentrations
Authors: Fang Yuanxiang , Govind Rakesh
Published: December 2007

Biofiltration of contaminants at concentrations below a certain level (sub‐low concentrations) is not as effective as at higher concentrations, which leads to incomplete removal of the contaminants, because of diffusive mass transfer of the contaminants inside the biofilm and insufficient carbon and energy sources to sustain biomass growth and maintenance. To overcome the limitation of diffusion, this article proposes the concept of convective flow biofilm in which contaminated air flows through the porous biofilm and thus carries the carbon and energy sources to the biomass. The innovative concept of convective flow biofilm was implemented in a convective flow biofilter (CFB), which was built from activated carbon‐coated ceramic monoliths by selectively blocking the channel openings. The CFB was tested for 11 weeks for the biofiltration of toluene at inlet concentrations below 100 ppmv. The CFB performed consistently better than the conventional diffusive flow biofilter (DFB), as indicated by the higher removal efficiencies and the higher CO2 productions. The CFB demonstrated up to 30 percent higher removal efficiency and an up to 100 percent higher elimination capacity than the DFB. © 2007 Wiley Periodicals, Inc.
Optical Investigation of Quantum Confinement in PbSe Nanocrystals at Different Points in the Brillouin Zone
Authors: Koole Rolf , Allan Guy , Delerue Christophe , Meijerink Andries , Vanmaekelbergh Daniël , Houtepen Arjan J.
Published: December 2007

We present detailed investigations on the optical properties of PbSe nanocrystals. The absorption spectra of monodisperse, quasispherical nanocrystals exhibit sharp features as a result of distinct optical transitions. To study the size dependence, absorption spectra of nanocrystals ranging from 3.4 to 10.9 nm in diameter are analysed and a total of 11 distinct optical transitions are identified. The assignment of the various optical transitions is discussed and compared to theoretically calculated transition energies. By plotting all transitions as a function of nanocrystal size (D) we find that the energy (E) changes with the following relationship E∝︁D−1.5 for the lowest energy transitions. The transition energy extrapolates to approximately 0.3 eV for infinite crystal size, in agreement with the bandgap of bulk PbSe at the L‐point in the Brillouin zone. In addition, high‐energy transitions are observed, which extrapolate to 1.6 eV for infinite crystal size, which is in good agreement with the bulk bandgap of PbSe at the Σ‐point in the Brillouin zone. Tight‐binding calculations confirm that the high‐energy transitions originate from the Σ‐point in the Brillouin zone. The Σ‐character of the high‐energy transitions may be of importance to explain the mechanism behind multiple exciton generation in PbSe nanocrystals.
Designing a new program in family relations and applied nutrition
Authors: Devine Sharon Mayne , Daly Kerry , Lero Donna , MacMartin Clare
Published: December 2007

This chapter describes the development of a new major in Adult Development, Families, and Well‐Being in the Department of Family Relations and Applied Nutrition.
Integrating knowledge, skills, and values into the curriculum development process at the University of Guelph‐Humber
Authors: Evers Frederick , Wolstenholme Janet
Published: December 2007

This chapter describes and critiques the curriculum development process for the original six programs at the University of Guelph‐Humber, a new institution developed by the University of Guelph and the Humber Institute of Technology and Advanced Learning.
Theory of Raman Scattering by Phonons in Germanium Nanostructures
Authors: Alfaro-Calderón Pedro , Cruz-Irisson Miguel , Wang-Chen Chumin
Published: December 2007

Within the linear response theory, a local bond-polarization model based on the displacement–displacement Green’s function and the Born potential including central and non-central interatomic forces is used to investigate the Raman response and the phonon band structure of Ge nanostructures. In particular, a supercell model is employed, in which along the [001] direction empty-column pores and nanowires are constructed preserving the crystalline Ge atomic structure. An advantage of this model is the interconnection between Ge nanocrystals in porous Ge and then, all the phonon states are delocalized. The results of both porous Ge and nanowires show a shift of the highest-energy Raman peak toward lower frequencies with respect to the Raman response of bulk crystalline Ge. This fact could be related to the confinement of phonons and is in good agreement with the experimental data. Finally, a detailed discussion of the dynamical matrix is given in the appendix section.
Integrated stratigraphy and palaeoecology of the Lower and Middle Miocene of the Porcupine Basin
Authors: LOUWYE STEPHEN , FOUBERT ANNELEEN , MERTENS KENNETH , VAN ROOIJ DAVID ,   THE IODP EXPEDITION 307 SCIENTIFIC PARTY
Published: December 2007

A high-resolution palynological analysis and a detailed palaeomagnetic study of a marine sequence recovered during IODP Expedition Leg 307 in the Porcupine Basin southwest of Ireland provide new insights into the regional depositional history and palaeoenvironmental evolution during Early Neogene times. The Hole 1318B studied was drilled on the upper slope of the continental margin in a water depth of 409 m, upslope from a province of carbonate mounds (the Belgica mound province). The diverse and well-preserved dinoflagellate cyst associations consist typically of deep neritic and oceanic species, mixed with a neritic component transported from the shelf, reflecting the deep depositional setting at the continental margin. The palaeomagnetic record together with the ranges of key dinoflagellate cyst species constrain the age of the studied sequence between 16.7 Ma and 12.01 Ma, that is, between the late Burdigalian and late Serravallian. The distinct unconformity terminating the Miocene sequence correlates to the global sequence boundary Ser4/Tor1 dated at 10.5 Ma, and represents, according to previous extensive seismic studies, a basin-wide erosional event. The overlying sediments are of Middle Pleistocene or younger age. Downslope from IODP Site 1318, carbonate mounds root on the erosional surface. The dinoflagellate cyst associations from the Porcupine Basin distinctly mirror the global cooling phase following the Middle Miocene Climatic Optimum. Cooling phase Mi3, a short-lived glaciation, is particularly well expressed and here dated at 13.6 Ma. The palynomorph record furthermore indicates a reduction of the productivity and an increase of oceanic oligotrophic species after 14 Ma, suggesting a reduction or perhaps even a shutdown of the upwelling.
SUBSTANTIVE MORAL THEORY
Authors: Pettit Philip
Published: December 2007

Philosophy can serve two roles in relation to moral thinking: first, to provide a meta-ethical commentary on the nature of moral thought, as the methodology or the philosophy of science provides a commentary on the nature of scientific thought; and second, to build on the common presumptions deployed in people's moral thinking about moral issues, looking for a substantive moral theory that they might support. The present essay addresses the nature of this second role; illustrates it with substantive theories that equate moral obligations respectively with requirements of nature, self-interest, benevolence, reason and justifiability; and outlines a novel competitor in which the focus is shifted to requirements of co-reasoning and respect.
FOUNDATIONS IN AQUINAS'S ETHICS
Authors: MacDonald Scott
Published: December 2007

Aquinas argues that practical reasoning requires foundations: first practical principles (ultimate ends) grasped by usper sefrom which deliberation proceeds. Contrary to the thesis of an important paper of Terence Irwin's, I deny that Aquinas advances two inconsistent conceptions of the scope of deliberation and, correspondingly, two inconsistent accounts of the content of the first practical principles presupposed by deliberation. On my account, Aquinas consistently takes first practical principles to be highly abstract, general, or formal ends, ends subject to specification and determination by a process of reasoning. Aquinas therefore gives deliberation wide scope, allowing (indeed, requiring) it not only to settle for us the things that are for the sake of our ends but also to engage in determining in important respects what our ends are. Accordingly, I conclude that Aquinas's foundations in ethics are “thin.” Our natural grasp of first practical principles gives us very little in the way substantive ethical principles.
Retinal bipolar cells: Temporal filtering of signals from cone photoreceptors
Authors: BURKHARDT DWIGHT A. , FAHEY PATRICK K. , SIKORA MICHAEL A.
Published: December 2007

The temporal dynamics of the response of neurons in the outer retina were investigated by intracellular recording from cones, bipolar, and horizontal cells in the intact, light-adapted retina of the tiger salamander (Ambystoma tigrinum), with special emphasis on comparing the two major classes of bipolars cells, the ON depolarizing bipolars (Bd) and the OFF hyperpolarizing bipolars (Bh). Transfer functions were computed from impulse responses evoked by a brief light flash on a steady background of 20 cd/m2. Phase delays ranged from about 89 ms for cones to 170 ms for Bd cells, yielding delays relative to that of cones of about 49 ms for Bh cells and 81 ms for Bd cells. The difference between Bd and Bh cells, which may be due to a delay introduced by the second messenger G-protein pathway unique to Bd cells, was further quantified by latency measurements and responses to white noise. The amplitude transfer functions of the outer retinal neurons varied with light adaptation in qualitative agreement with results for other vertebrates and human vision. The transfer functions at 20 cd/m2 were predominantly low pass with 10-fold attenuation at about 13, 14, 9.1, and 7.7 Hz for cones, horizontal, Bh, and Bd cells, respectively. The transfer function from the cone voltage to the bipolar voltage response, as computed from the above measurements, was low pass and approximated by a cascade of three low pass RC filters (“leaky integrators”). These results for cone→bipolar transmission are surprisingly similar to recent results for rod→bipolar transmission in salamander slice preparations. These and other findings suggest that the rate of vesicle replenishment rather than the rate of release may be a common factor shaping synaptic signal transmission from rods and cones to bipolar cells.
No age-related cell loss in three retinal nuclear layers of the Long-Evans rat
Authors: FENG LIXIA , SUN ZHAOXIA , HAN HUI , ZHOU YIFENG , ZHANG MING
Published: December 2007

The retina mainly contains ganglion, bipolar and photoreceptor cells which are distributed in the ganglion cell layer (GCL), inner nuclear layer (INL) and outer nuclear layer (ONL), respectively. Whether there is an age-related loss of these retinal cells remains not well understood. Cell density and the total number of cells were two commonly used measures to evaluate such age-related changes in most previous studies and provided controversial conclusions. The use of density measures as decisive data is problematic because the total area of the retina was expanded in aging, whereas the application of the total number of cells was limited for assessing ganglion cells. In this study, thus, we wanted to test whether there is an age-related cell loss in the GCL, INL and ONL and if so, whether such a loss is correlated to the convergence ratio of these cells. We used stereological procedures to quantify the total number of cells in the three retinal nuclear layers in six young and six aged Long-Evans rats. We found that during aging, the total volume of the retina remained unchanged, but the retina became thinner. There was no cell loss in each individual nuclear layer, and the ratio of the ONL to INL to GCL was preserved.
The multifocal pattern electroretinogram (mfPERG) and cone-isolating stimuli
Authors: LANGROVÁ HANA , JÄGLE HERBERT , ZRENNER EBERHART , KURTENBACH ANNE
Published: December 2007

The number of L cones in the retina normally exceeds that of the M cones. Because normal color vision does not depend on the ratio of L- and M-photoreceptors, their signals must undergo an alteration in gain before being analyzed in the cortex. Previous studies have shown that this gain must take place before the cortex, but after the bipolar/amacrine cell layer of the retina. The aim of this study was to obtain topographical information about L- and M-cone activity at the ganglion cell layer using multifocal pattern electroretinography (mfPERG). A standard (black and white) stimulus was used, as well as stimuli modulating only the long wavelength-sensitive (L) or only the middle wavelength-sensitive (M) cones. The L:M ratio was calculated from the amplitude of the L-cone isolating mfPERG to that of the M-cone isolating mfPERG of 10 trichromats. Both the positive and negative components of the waveform were analyzed. Additional recordings of single cone modulated mfERGs were obtained from nine of the 10 subjects. We also recorded from one protanope and one deuteranope. The L:M cone amplitude ratios for both deflections of the mfPERG in the trichromats were around unity (medians 1.18 and 1.16, respectively) for the central 8° of retina. In the peripheral retina between 12.8° and 26°, this ratio increased to 1.42 for the positive component, and 1.37 for the negative component. The median L:M cone amplitude ratios for the mfPERG were higher and ranged between 1.00–2.78 in the central 8° and 1.29–2.78 in the periphery. The results indicate that a major gain adjustment of the retinal signals takes place at the ganglion cell level, and that the ratio is higher at eccentric locations than in the central retinal area.
Properties of stimulus-dependent synchrony in retinal ganglion cells
Authors: CHATTERJEE SUSMITA , MERWINE DAVID K. , AMTHOR FRANKLIN R. , GRZYWACZ NORBERTO M.
Published: December 2007

Neighboring retinal ganglion cells often spike synchronously, but the possible function and mechanism of this synchrony is unclear. Recently, the strength of the fast correlation between ON-OFF directionally selective cells of the rabbit retina was shown to be stimulus dependent. Here, we extend that study, investigating stimulus-dependent correlation among multiple ganglion-cell classes, using multi-electrode recordings. Our results generalized those for directionally selective cells. All cell pairs exhibiting significant spike synchrony did it for an extended edge but rarely for full-field stimuli. The strength of this synchrony did not depend on the amplitude of the response and correlations could be present even when the cells' receptive fields did not overlap. In addition, correlations tended to be orientation selective in a manner predictable by the relative positions of the receptive fields. Finally, extended edges and full-field stimuli produced significantly greater and smaller correlations than predicted by chance respectively. We propose an amacrine-network model for the enhancement and depression of correlation. Such an apparently purposeful control of correlation adds evidence for retinal synchrony playing a functional role in vision.
The association between consumption of breakfast cereals and BMI in schoolchildren aged 12–17 years: The VYRONAS study
Authors: Kosti Rena I , Panagiotakos Demosthenes B , Zampelas Antonis , Mihas Costas , Alevizos Alevizos , Leonard Clare , Tountas Yannis , Mariolis Anargiros
Published: December 2007

Objective

To evaluate whether consumption of breakfast cereals is associated with BMI in a sample of Greek adolescents.

Design

A cross-sectional health and nutrition survey.

Setting and subjects

During 2004–5, 2008 schoolchildren aged 12–17 years were selected from twelve schools located in Vyronas region (Athens metropolitan area). Height and weight were measured and BMI was calculated. A semi-quantitative FFQ was applied and multiple logistic regression analysis was used.

Results

Overall, 4·7 % of boys and 1·7 % of girls were obese, whereas 19·4 % of boys and 13·2 % of girls were overweight. Only 20·7 % of boys and 15·5 % of girls reported that they consume cereals as a first choice for breakfast. Consumption of breakfast cereals was associated with lower BMI in boys (P= 0·08) and girls (P= 0·019), irrespective of age and physical activity status. More prominent results were observed for daily cereal consumption or for more than two daily servings of cereals consumed for breakfast. Consumption of pre-sweetened breakfast cereals was associated with lower BMI compared with non-pre-sweetened or no intake of cereals, in both genders (P< 0·001). Consumption of breakfast cereals was associated with 33 % (95 % CI 14 %, 48 %) lower likelihood of overweight/obesity, irrespective of age, sex and physical activity status.

Conclusions

Consumption of breakfast cereals was associated with lower BMI levels and a lower likelihood of overweight/obesity in both genders; thus a solid basis for public health professionals could be built when issuing advice on weight management.
Update Tuberkulose-Diagnostik: Interferon-gamma-Bluttests
Authors: Zimmerli  , Nüesch  , Elzi
Published: December 2007

Bislang war der Tuberkulinhauttest (THT) der einzige verfügbare Test zur Erkennung einer latenten tuberkulösen Infektion (LTBI). Der THT weist jedoch verschiedene Limitationen auf: er ist eine Mischung aus über 200 verschiedenen Antigenen, die nicht nur in M. tuberculosis (M.tbc.), sondern auch in M. bovis BCG und verschiedenen Umweltmykobakterien enthalten sind, weshalb es zu falsch-positiven Reaktionen kommen kann.Neuere immunologische Testverfahren machen sich die Interferon-γ (IFN-γ)-Produktion durch Lymphozyten, welche auf M.tbc.-spezifische Peptide sensibilisiert sind, nach in vitro-Stimulation mit spezifischen Antigenen zunutze. Diese IFN-γ-Tests zeigen ein günstiges Sensitivitäts-/Spezifitätsverhältnis. Auch hinsichtlich der Korrelation mit dem Ausmass der Exposition scheinen die IFN-γ-Tests dem THT überlegen zu sein. Dabei ist die Anwendung insbesondere bei BCG-geimpften Personen vorteilhaft, da hier im Vergleich zu allen anderen Testmethoden die Spezifität besonders hoch ist. Ein weiterer Vorteil ist, dass die IFN-γ-Tests reproduzierbar sind, ohne dass ein Boostereffekt auftritt und ihre Interpretation Untersucher-unabhängig ist. Ein kompletter Ersatz des THT durch die IFN-γ-Tests ist aufgrund der aktuellen Datenlage allerdings noch nicht gerechtfertigt: es fehlen insbesondere noch Daten zur Verwendung der Tests bei immunsupprimierten Personen. Für diese wäre eine zuverlässige Alternative zum THT dringend notwendig.
Evaluation of heterogeneous processes in the polar lower stratosphere in the Whole Atmosphere Community Climate Model
Authors: Tilmes Simone , Kinnison Douglas E. , Garcia Rolando R. , Müller Rolf , Sassi Fabrizio , Marsh Daniel R. , Boville Byron A.
Published: December 2007

Chemical ozone loss in the polar lower stratosphere is derived from an ensemble of three simulations from the Whole Atmosphere Community Climate Model (WACCM3) for the period 1960–2003, using the tracer‐tracer correlation technique. We describe a detailed model evaluation of the polar region by applying diagnostics such as vortex temperature, sharpness of the vortex edge, and the potential of activated chlorine (PACl). Meteorological and chemical information about the polar vortex, temperature, vortex size, and activation time, and level of equivalent effective stratospheric chlorine, are included in PACl. Discrepancies of the relationship between chemical ozone loss and PACl between model and observations are discussed. Simulated PACl for Antarctica is in good agreement with observations, owing to slightly lower simulated temperatures and a larger vortex volume than observed. Observed chemical ozone loss of 140 ± 30 DU in the Antarctic vortex core are reproduced by the WACCM3 simulations. However, WACCM3 with the horizontal resolution used here (4 × 5) is not able to simulate the observed sharp transport barrier at the polar vortex edge. Therefore the model does not produce an homogeneous cold polar vortex. Warmer temperatures in the outer region of the vortex result in less chemical ozone loss over the entire polar vortex than observed. For the Arctic, WACCM3 temperatures are biased high (by 2–3 degrees in the annual average) and the vortex volume and chlorine activation period is significantly smaller than observed. WACCM3 Arctic chemical ozone loss only reaches 20 DU for cold winters, where observations suggest ≈80–120 DU.
Interactions between earthquakes and volcano activity
Authors: Lemarchand Nicolas , Grasso Jean‐Robert
Published: December 2007

Using the 1973–2005 worldwide catalogues for M ≥ 4.8 seismicity and VEI ≥ 0 volcano eruptions, we find a significant, when tested against catalogue randomizations, increase of eruption onsets on the earthquake day. This result emerges from stacking time series of daily eruption rates relatively to earthquake time,t0, over the whole seismicity catalogue. It is stronger for earthquake‐volcano pairs for which the volcano is within ten rupture size from the epicenter. These results show that M ≥ 4.8 − VEI ≥ 0 earthquake‐volcano pairs are as important for interaction processes as the M ≥ 7 and VEI ≥ 2–5 pairs previously reported to interact. The clustering in time for earthquake‐eruption pairs is not bounded tot0. It remains above the background noise 6–10 days before and aftert0, and follows a power law distribution. These patterns, which are similar to the direct and inverse Omori's laws observed for tectonic earthquakes, are the first evidence for the volcano eruptions to be contemporary of a stochastic brittle damage in the earth crust. The clustering we observe in time and space (i) rejects the earthquake triggering as the single process that drive earthquake‐volcano interactions; (ii) supports a regional tectonic coupling in the earth crust damage.
Validation of daily erythemal doses from Ozone Monitoring Instrument with ground‐based UV measurement data
Authors: Tanskanen Aapo , Lindfors Anders , Määttä Anu , Krotkov Nickolay , Herman Jay , Kaurola Jussi , Koskela Tapani , Lakkala Kaisa , Fioletov Vitali , Bernhard Germar , McKenzie Richard , Kondo Yutaka , O'Neill Michael , Slaper Harry , den Outer Peter , Bais Alkiviadis F. , Tamminen Johanna
Published: December 2007

The Dutch‐Finnish Ozone Monitoring Instrument (OMI) on board the NASA EOS Aura spacecraft is a nadir viewing spectrometer that measures solar reflected and backscattered light in a selected range of the ultraviolet and visible spectrum. The instrument has a 2600 km wide viewing swath and it is capable of daily, global contiguous mapping. The Finnish Meteorological Institute and NASA Goddard Space Flight Center have developed a surface ultraviolet irradiance algorithm for OMI that produces noontime surface spectral UV irradiance estimates at four wavelengths, noontime erythemal dose rate (UV index), and the erythemal daily dose. The overpass erythemal daily doses derived from OMI data were compared with the daily doses calculated from the ground‐based spectral UV measurements from 18 reference instruments. Two alternative methods for the OMI UV algorithm cloud correction were compared: the plane‐parallel cloud model method and the method based on Lambertian equivalent reflectivity. The validation results for the two methods showed some differences, but the results do not imply that one method is categorically superior to the other. For flat, snow‐free regions with modest loadings of absorbing aerosols or trace gases, the OMI‐derived daily erythemal doses have a median overestimation of 0–10%, and some 60 to 80% of the doses are within ±20% from the ground reference. For sites significantly affected by absorbing aerosols or trace gases one expects, and observes, bigger positive bias up to 50%. For high‐latitude sites the satellite‐derived doses are occasionally up to 50% too small because of unrealistically small climatological surface albedo.
Ecological feedbacks following deforestation create the potential for a catastrophic ecosystem shift in tropical dry forest
Authors: Lawrence Deborah , D'Odorico Paolo , Diekmann Lucy , DeLonge Marcia , Das Rishiraj , Eaton James
Published: December 2007

The long-term ecological response to recurrent deforestation associated with shifting cultivation remains poorly investigated, especially in the dry tropics. We present a study of phosphorus (P) dynamics in the southern Yucatán, highlighting the possibility of abrupt shifts in biogeochemical cycling resulting from positive feedbacks between vegetation and its limiting resources. After three cultivation–fallow cycles, available soil P declines by 44%, and one-time P inputs from biomass burning decline by 76% from mature forest levels. Interception of dust-borne P (“canopy trapping”) declines with lower plant biomass and leaf area, limiting deposition in secondary forest. Potential leaching losses are greater in secondary than in mature forest, but the difference is very small compared with the difference in P inputs. The decline in new P from atmospheric deposition creates a long-term negative ecosystem balance for phosphorus. The reduction in soil P availability will feed back to further limit biomass recovery and may induce a shift to sparser vegetation. Degradation induced by hydrological and biogeochemical feedbacks on P cycling under shifting cultivation will affect farmers in the near future. Without financial support to encourage the use of fertilizer, farmers could increase the fallow period, clear new land, or abandon agriculture for off-farm employment. Their response will determine the regional balance between forest loss and forest regrowth, as well as the frequency of use and rate of recovery at a local scale, further feeding back on ecological processes at multiple scales.
A synthetic host-guest system achieves avidin-biotin affinity by overcoming enthalpy–entropy compensation
Authors: Rekharsky Mikhail V. , Mori Tadashi , Yang Cheng , Ko Young Ho , Selvapalam N. , Kim Hyunuk , Sobransingh David , Kaifer Angel E. , Liu Simin , Isaacs Lyle , Chen Wei , Moghaddam Sarvin , Gilson Michael K. , Kim Kimoon , Inoue Yoshihisa
Published: December 2007

The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 × 10
15
M
−1
(
K
d
= 3 × 10
−16
M), equivalent to that exhibited by the avidin–biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy–entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.
A synthetic precedent for the [Fe
IV
2
(μ-O)
2
] diamond core proposed for methane monooxygenase intermediate Q
Authors: Xue Genqiang , Wang Dong , De Hont Raymond , Fiedler Adam T. , Shan Xiaopeng , Münck Eckard , Que Lawrence
Published: December 2007

Intermediate Q, the methane-oxidizing species of soluble methane monooxygenase, is proposed to have an [Fe
IV
2
(μ-O)
2
] diamond core. In an effort to obtain a synthetic precedent for such a core, bulk electrolysis at 900 mV (versus Fc
+/0
) has been performed in MeCN at −40°C on a valence-delocalized [Fe
III
Fe
IV
(μ-O)
2
(L
b
)
2
]
3+
complex (1b) (
E
1/2
= 760 mV versus Fc
+/0
). Oxidation of 1b results in the near-quantitative formation of a deep red complex, designated 2b, that exhibits a visible spectrum with λ
max
at 485 nm (9,800 M
−1
·cm
−1
) and 875 nm (2,200 M
−1
·cm
−1
). The 4.2 K Mössbauer spectrum of 2b exhibits a quadrupole doublet with δ = −0.04(1) mm·s
−1
and Δ
E
Q
= 2.09(2) mm·s
−1
, parameters typical of an iron(IV) center. The Mössbauer patterns observed in strong applied fields show that 2b is an antiferromagnetically coupled diiron(IV) center. Resonance Raman studies reveal the diagnostic vibration mode of the [Fe
2
(μ-O)
2
] core at 674 cm
−1
, downshifting 30 cm
−1
upon
18
O labeling. Extended x-ray absorption fine structure (EXAFS) analysis shows two O/N scatterers at 1.78 Å and an Fe scatterer at 2.73 Å. Based on the accumulated spectroscopic evidence, 2b thus can be formulated as [Fe
IV
2
(μ-O)
2
(L
b
)
2
]
4+
, the first synthetic complex with an [Fe
IV
2
(μ-O)
2
] core. A comparison of 2b and its mononuclear analog [Fe
IV
(O)(L
b
)(NCMe)]
2+
(4b) reveals that 4b is 100-fold more reactive than 2b in oxidizing weak C

H bonds. This surprising observation may shed further light on how intermediate Q carries out the hydroxylation of methane.
An intragenic MEF2-dependent enhancer directs muscle-specific expression of microRNAs 1 and 133
Authors: Liu Ning , Williams Andrew H. , Kim Yuri , McAnally John , Bezprozvannaya Svetlana , Sutherland Lillian B. , Richardson James A. , Bassel-Duby Rhonda , Olson Eric N.
Published: December 2007

The muscle-specific microRNAs, miR-1 and miR-133, play important roles in muscle growth and differentiation. Here, we show that the MEF2 transcription factor, an essential regulator of muscle development, directly activates transcription of a bicistronic primary transcript encoding miR-1-2 and 133a-1 via an intragenic muscle-specific enhancer located between the miR-1-2 and 133a-1 coding regions. This MEF2-dependent enhancer is activated in the linear heart tube during mouse embryogenesis and thereafter controls transcription throughout the atrial and ventricular chambers of the heart. MEF2 together with MyoD also regulates the miR-1-2/-133a-1 intragenic enhancer in the somite myotomes and in all skeletal muscle fibers during embryogenesis and adulthood. A similar muscle-specific intragenic enhancer controls transcription of the miR-1-1/-133a-2 locus. These findings reveal a common architecture of regulatory elements associated with the miR-1/-133 genes and underscore the central role of MEF2 as a regulator of the transcriptional and posttranscriptional pathways that control cardiac and skeletal muscle development.