Characteristics of Symmetric Surface Plasmon Polariton Mode in Glass–Metal–Glass Waveguide

The propagation characteristics of symmetric surface plasmon polariton mode in a glass–metal–glass waveguide are presented. Gallium lanthanum sulfide has been taken as the glass and silver (Ag) has been used as the metal. The analysis has been done both numerically and analytically. A two-dimensional finite-difference time-domain-based simulation model has been developed in order to analyze the propagation characteristics numerically. The obtained results using numerical and analytical methods have been compared and a very good agreement has been found.     

Does Glass Size and Shape Influence Judgements of the Volume of Wine?

Background

Judgements of volume may influence the rate of consumption of alcohol and, in turn, the amount consumed. The aim of the current study was to examine the impact of the size and shape of wine glasses on perceptions of wine volume.

Methods

Online experiment: Participants (n = 360; recruited via Mechanical Turk) were asked to match the volume of wine in two wine glasses, specifically: 1. the Reference glass holding a fixed reference volume, and 2. the Comparison glass, for which the volume could be altered until participants perceived it matched the reference volume. One of three comparison glasses was shown in each trial: ‘wider’ (20% wider but same capacity); ‘larger’ (same width but 25% greater capacity); or ‘wider-and-larger’ (20% wider and 25% greater capacity). Reference volumes were 125ml, 175ml and 250ml, in a fully factorial within-subjects design: 3 (comparison glass) x 3 (reference volume). Non-zero differences between the volumes with which participants filled comparison glasses and the corresponding reference volumes were identified using sign-rank tests.

Results

Participants under-filled the wider glass relative to the reference glass for larger reference volumes, and over-filled the larger glass relative to the reference glass for all reference volumes. Results for the wider-and-larger glass showed a mixed pattern across reference volume. For all comparison glasses, in trials with larger reference volumes participants tended to fill the comparison glass less, relative to trials with smaller reference volumes for the same comparison glass.

Conclusions

These results are broadly consistent with people using the relative fullness of glasses to judge volume, and suggest both the shape and capacity of wine glasses may influence perceived volume. Perceptions that smaller glasses contain more than larger ones (despite containing the same volume), could slow drinking speed and overall consumption by serving standard portions in smaller glasses. This hypothesis awaits testing.     

Saturated C21–C33Hydrocarbons Are Involved in the Self-Regulation of Pseudomonas fluorescensAdhesion to a Glass Surface

One of the two putative groups of antiadhesins was identified in Pseudomonas fluorescensby the method of gas chromatography–mass spectrometry. A mixture of high-molecular unbranched hydrocarbons (HC) with a chain length from 21 to 33 carbon atoms reduced cell adhesion to a glass surface. These HC accumulated in the culture liquid to a total concentration of 10–15 g/l; the concentrations of individual HC ranged from 0.1 to 3.0 g/l. After the addition of individual HC to the bacterial culture, the number of cells attached to the glass surface decreased. This decrease in cell adhesion was due to the enhanced aggregation of the bacterial cells, which promoted mechanical (hydrodynamic) cell detachment from the surface.     

Temporal relationships of a pulse of prolactin (PRL) to a pulse of a metabolite of PGF2α in mares

Hourly blood samples were collected from 10 mares during 24 h of each of the preluteolytic, luteolytic, and postluteolytic periods. The autocorrelation function of the R program was used to detect pulse rhythmicity, and the intra-assay CV was used to locate and characterize pulses of prolactin (PRL) and a metabolite of prostaglandin F2α (PGFM). Rhythmicity of PRL and PGFM concentrations was detected in 67% and 89% of mares, respectively. Combined for the three periods (no difference among periods), the PRL pulses were 5.2 ± 0.4 h (mean ± SEM) at the base, 7.5 ± 1.5 h between nadirs of adjacent pulses, and 12.3 ± 1.5 h from peak to peak. The peaks of PRL pulses were greater (P < 0.05) during the luteolytic period (46 ± 14 ng/mL) and postluteolytic period (52 ± 15 ng/mL) than during the preluteolytic period (17 ± 3 ng/mL). Concentrations of PRL during hours of a PGFM pulse were different (P < 0.003) within the luteolytic period and postluteolytic period and were greatest at the PGFM peak; PRL concentrations during a PGFM pulse were not different during the preluteolytic period. The frequency of the peak of PRL and PGFM pulses occurring at the same hour (synchrony) was greater for the luteolytic period (65%, P < 0.01) and postluteolytic period (50%, P < 0.001) than for the preluteolytic period (17%). This is the first report in mares on characterization and rhythmicity of PRL pulses, synchrony between PRL and PGFM pulses, and greater PRL activity during the luteolytic and postluteolytic periods than during the preluteolytic period.     

Glass Transition and Dynamics in Lysozyme�CWater Mixtures Over Wide Ranges of Composition

Differential scanning calorimetry (DSC) and two dielectric techniques, broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents (TSDC), were employed to study glass transition and water and protein dynamics in mixtures of water and a globular protein, lysozyme, in wide ranges of water content, both solutions, and hydrated solid samples. In addition, water equilibrium sorption isotherms (ESI) measurements were performed at room temperature. The main objective was to correlate results by different techniques to each other and to determine critical water contents for various processes. From ESI measurements the content of water directly bound to primary hydration sites was determined to 0.088 (grams of water per grams of dry protein), corresponding to 71 water molecules per protein molecule, and that where clustering becomes significant to about 0.25. Crystallization and melting events of water were first observed at water contents 0.270 and 0.218, respectively, and the amount of uncrystallized water was found to increase with increasing water content. Two populations of ice crystals were observed by DSC, primary and bulk ice crystals, which give rise to two separate relaxations in dielectric measurements. In addition, the relaxation of uncrystallized water was observed, superimposed on a local relaxation of polar groups on the protein surface. The glass transition temperature, determined by DSC and TSDC in rather good agreement to each other, was found to decrease significantly with increasing water content and to stabilize at about −90 °C for water contents higher than about 0.25. This is a novel result of this study with potential impact on cryoprotection and pharmaceutics.     

Range-body mass interactions of a northern ungulate – a test of hypothesis

Summer diet, summer temperature, length of the growth season and animal density appeared to best explain annual and regional differences in calf and yearling body mass in moose from southeastern Norway. In general animals inhabiting steep, alpine landscapes had less body mass than animals using flat, low-altitude habitats. Autumn body mass of calves and yearlings decreased with increasing snow depth during the preceding winter and spring. However, calf body mass was more influenced by the summer range and less by the winter range than was body mass of yearlings. There was no indication that the effect of snow depth on autumn body mass was greater in moose living on poor than on good summer ranges. Body mass decreased with increasing competition for summer forage, while the winter range mainly had an density-independent effect. Habitat quality, expressed as regression lines between calf and yearling body mass and animal density (hunting yield), differed between regions. On ranges of medium and high altitude where birch (Betula spp.) rowan (Sorbus aucuparia) and bilberry (Vaccinium myrtillus) dominated moose summer diet, body mass decreased at a rapid rate with increasing animal density. Body mass decreased at a slower rate at low-altitude ranges and at high-altitude ranges where willow (Salix spp.) and forbs dominated the diet. Body mass of lactating cows decreased with increasing animal density, but animal density did not affect body mass of non-lactating cows. There was no indication that the decrease in autumn body mass with increasing moose density over the last 25 years has caused a decrease in animal condition (ability to survive the winter). The results are discussed in relation to the effect of summer and winter range on population regulation in moose. It is concluded that a density-dependent effect is apparent on the summer range even at low and intermediate population densities. On the winter range, on the other hand, density-dependence is likely to occur only at high levels of population density. Received: 4 February 1997 / Accepted: 1 February 1999     

Synthesis of a cyclic isostere of α-methyl homoserine by a stereoselective acylation–alkylation sequence of a chiral γ-lactam

Starting from a chiral 4-hydroxymethyl pyrrolidin-2-one, an isostere of α-methyl homoserine tethered on a γ-lactam ring was prepared exploiting a stereoselective acylation–methylation sequence, followed by Curtius rearrangement, and structural assignment was confirmed by n.O.e. experiments. By reverting the sequence, the 3-carboxy-3-methyl derivative having the opposite configuration at C-3 was obtained with total stereoselection, but Curtius rearrangement invariably afforded only inseparable mixtures of decomposition products.     

Is aggregation of beta-amyloid peptides a mis-functioning of a current interaction process?

In a previous study, Hughes et al. [Proc. Natl. Acad. Sci. USA 93 (1996) 2065-2070] demonstrated that the amyloid peptide is able to interact with itself in a two-hybrid system and that interaction is specific. They further supported that the method could be used to define the sequences that might be important in nucleation-dependent aggregation. The sequence of the amyloid peptide can be split into four clusters, two hydrophilic (1-16 and 22-28) and two hydrophobic (17-21 and 29-42). We designed by molecular modeling and tested by the two-hybrid approach, series of mutations spread all over the sequence and changing the distribution of hydrophobicity and/or the spatial hindrance. In the two-hybrid assay, interaction of native Abeta is reproduced. Screening of mutations demonstrates that the C-domain (residues 29-40 (42)), the median domain (residues 17-22) and the N-domain (1-16) are all crucial for interaction. This demonstrates that almost all fragments of the amyloid peptide but a loop (residues 23-28) and the C-term amino acid are important for the native interaction. We support that the folded three-dimensional (3D) structure is the Abeta-Abeta interacting species, that the whole sequence is involved in that 3D fold which has a low secondary structure propensity and a high susceptibility to mutations and thus should have a low stability. The native fold of Abeta could be stabilized in Abeta-Abeta complexes which could in other circumstances facilitate the nucleation event of aggregation that leads to the formation of stable senile plaques.     

Structural characterization of a carbon monoxide adduct of a heme–DNA complex

Abstract  

The structure of a carbon monoxide (CO) adduct of a complex between heme and a parallel G-quadruplex DNA formed from a single repeat sequence of the human telomere, d(TTAGGG), has been characterized using ¹H and ¹³C NMR spectroscopy and density function theory calculations. The study revealed that the heme binds to the 3′-terminal G-quartet of the DNA though a π–π stacking interaction between the porphyrin moiety of the heme and the G-quartet. The π–π stacking interaction between the pseudo-C ₂-symmetric heme and the C ₄-symmetric G-quartet in the complex resulted in the formation of two isomers possessing heme orientations differing by 180° rotation about the pseudo-C ₂ axis with respect to the DNA. These two slowly interconverting heme orientational isomers were formed in a ratio of approximately 1:1, reflecting that their thermodynamic stabilities are identical. Exogenous CO is coordinated to heme Fe on the side of the heme opposite the G-quartet in the complex, and the nature of the Fe–CO bond in the complex is similar to that of the Fe–CO bonds in hemoproteins. These findings provide novel insights for the design of novel DNA enzymes possessing metalloporphyrins as prosthetic groups.     

Characterization of a transient unfolding intermediate in a core mutant of γS-crystallin

In many age-related and neurological diseases, formerly native proteins aggregate via formation of a partially unfolded intermediate. γS-Crystallin is a highly stable structural protein of the eye lens. In the mouse Opj cataract, a non-conservative F9S mutation in the N-terminal domain core of γS allows the adoption of a native fold but renders the protein susceptible to temperature- and concentration-dependent aggregation, including fibril formation. Hydrogen/deuterium exchange and denaturant unfolding studies of this mutant protein (Opj) have suggested the existence of a partially unfolded intermediate in its aggregation pathway. Here, we used NMR and fluorescence spectroscopy to obtain evidence for this intermediate. In 3.5 M urea, Opj forms a stable and partially unfolded entity that is characterized by an unstructured N-terminal domain and a largely intact C-terminal domain. Under physiologically relevant conditions, Carr-Purcell-Meiboom-Gill T₂-relaxation dispersion experiments showed that the N-terminal domain residues were in conformational exchange with a loosely structured intermediate with a population of 1-2%, which increased with temperature. This provides direct evidence for a model in which proteins of native fold can explore an intermediate state with an increased propensity for formation of aggregates, such as fibrils. For the crystallins, this shows how inherited sequence variants or environmentally induced modifications can destabilize a well-folded protein, allowing the formation of intermediates able to act as nucleation sites for aggregation and the accumulation of light-scattering centers in the cataractous lens.     

Stereoselective formation of a 2′(3′)-aminoacyl ester of a nucleotide

Summary Reaction ofDl-serine and adenosine-5-phosphorimidazolide in the presence of adenosine-5-(O-methylphosphate) and imidazole resulted in the stereoselective synthesis of the aminoacyl nucleotide ester 2(3)-O-seryl-adenosine-5-(O-methylphosphate). The enantiomeric excess ofd-serine incorporated into 2(3)-O-seryl-adenosine-5-(O-methylphosphate) was about 9%. Adenylyl-(5N)-serine and an unknown product also incorporated an excess ofd-serine; however, serylserine showed an excess ofl-serine. The relationship of these results to the origin of the biological pairing ofl-amino acids and nucleotides containingd-ribose is discussed.     

Glass transition behavior of octyl β-D-glucoside and octyl β-D-thioglucoside/water binary mixtures

The lyotropic behavior and glass-forming properties of octyl β-d-glucoside (C8Glu) and octyl β-d-thioglucoside (C8SGlu)/water binary mixtures were evaluated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The results clearly indicate that the mixture forms a glass in the supercooling state of liquid crystalline phases such as cubic, lamellar, and smectic. The glass transition temperature (T_g) of the mixture was strongly dependent on solute concentration, with a higher concentration correlating with a higher T_g. The experimental T_g was consistent with the predicted value calculated using the Couchman-Karasz equation in both the C8Glu and C8SGlu/water mixtures. The change of heat capacity at T_g showed the two bending points under variation of concentrations. And the highest temperature of phase transition from lamellar to isotropic solution was observed at around 50% molar concentration. It was expected that non-percolated state of water existed in extremely higher concentration ranges.     

“Pollination” of a fungus by a fly

Summary The mechanism resulting in fertilization of Epichloë typhina, a heterothallic ascomycete that is an endophytic pathogen of grasses, has now been discovered. Conidia of one mating type are produced in stromata and are then transferred by insects to individuals of the opposite mating type. One insect, Phorbia phrenione, is a particularly important vector of conidia. Once conidia of the opposite mating type have been transferred to a stroma, the life cycle continues with the formation of perithecia.     

‘Through a Glass Darkly’: The Rockefeller Foundation's International Health Board and Soviet Public Health

In the early 1920s, the Rockefeller Foundation's International Health Board was presenting itself as the watchtower of public health for the world at large. Yet Soviet Russia was never included in any of the International Health Board's programs, despite the efforts of the Russians to reach out to the Board. This paper examines the exclusion of Russia as a function of the conceptual and structural lenses through which the International Health Board ‘saw’ post-revolutionary Soviet public health. It also speculates about the ways in which those who spoke on behalf of Soviet public health contributed to the perceptions of the Board.     

Effects of a half a millennium winter on a deep lake – a shape of things to come?

Analyses of the effects of extreme climate periods have been used as a tool to predict ecosystem functioning and processes in a warmer world. The winter half‐year 2006/2007 (w06/07) has been extremely warm and was estimated to be a half‐a‐millennium event in central Europe. Here we analyse the consequences of w06/07 for the temperatures, mixing dynamics, phenologies and population developments of algae and daphnids (thereafter w06/07 limnology) in a deep central European lake and investigate to what extent analysis of w06/07 limnology can really be used as a predictive tool regarding future warming. Different approaches were used to put the observations during w06/07 into context: (1) a comparison of w06/07 limnology with long‐term data, (2) a comparison of w06/07 limnology with that of the preceding year, and (3) modelling of temperature and mixing dynamics using numerical experiments. These analyses revealed that w06/07 limnology in Lake Constance was indeed very special as the lake did not mix below 60 m depth throughout winter. Because of this, anomalies of variables associated strongly with mixing behaviour, e.g., Schmidt stability and a measure for phosphorus upward mixing during winter exceeded several standard deviations the long‐term mean of these variables. However, our modelling results suggest that this extreme hydrodynamical behaviour was only partially due to w06/07 meteorology per se, but depended also strongly on the large difference in air temperature to the previous cold winter which resulted in complete mixing and considerable cooling of the water column. Furthermore, modelling results demonstrated that with respect to absolute water temperatures, the model ‘w06/07’ most likely underestimates the increase in water temperature in a warmer world as one warm winter is not sufficient to rise water temperatures in a deep lake up to those expected under a future climate.     

Characterization of a predominantly pistil-expressed gene encoding a γ-thionin-like protein of Petunia inflata

We isolated a cDNA clone from a pistil cDNA library of Petunia inflata which encodes a protein, PPT, with sequence similarity to -thionins. Characterization of a genomic clone containing a PPT gene revealed the presence of a single intron. Northern analysis revealed that the PPT gene was predominantly expressed in the pistil during all stages of flower development. Since thionins have been implicated in plant defense against pathogens, PPT may play a role similar to that of other defense-related proteins found in the pistil, defending the pistil against pathogen infection.     

Growth of a Capsid Mutant of Bacteriophage φX174 in a Temperature-Sensitive Strain of Escherichia coli

A capsid mutant of X174 is capable of forming replicative form and synthesizing single strands at the restrictive temperature in a dnaB mutant of Escherichia coli. Under similar conditions, the wild-type bacteriophage is incapable of either step in viral synthesis.