Optical path length fluctuations in the atmosphere

The effect of atmospheric fluctuations on measurements of distance has become increasingly important as laser interferometers become more widely used. The present study evaluates the precision with which dimensions can be monitored by interferometry involving optical path lengths in the open air under good atmospheric conditions. The size and time scale of optical path length fluctuations over distances of one meter, and correlations between fluctuations in nearby optical paths, are measured and analyzed.     

Calling behavior of almond moth (Ephestia cautella) females kept in glass cages and airborne pheromone deposited on glass surfaces by airstream

The airborne pheromone emitted by calling almond moth (Ephestia cautella) females kept in individual glass cages was mainly adsorbed on the cage surface (60–65%), but sufficient pheromone was transferred by the airflow to the extended capillaries to be measured. Four calling positions of almond moth females in the glass cages were defined. The position in which the female faced the upwind flow and the gland was free to release the pheromone was the more commonly adopted position (39% of calling females). No significant difference was found in the blend proportion between capillary and cage washings in each calling position or between calling positions. The pheromone blend and amount emitted from each of five individual females was measured on three consecutive nights and both fluctuated during the 11 hr of collection, starting 3 hr before the onset of scotophase and continuing for 8 hr into it.     

Effect of particulates on performance of optical communication in space and an adaptive method to minimize such effects

Decreased signal-to-noise ratio and maximum bit rate as well as increased in error probability in optical digital communication are caused by particulate light scatter in the atmosphere and in space. Two effects on propagation of laser pulses are described: spatial widening of the transmitted beam and attenuation of pulse radiant power. Based on these results a model for reliability of digital optical communication in a particulate-scattering environment is presented. Examples for practical communication systems are given. An adaptive method to improve and in some cases to make possible communication is suggested. Comparison and analysis of two models of communication systems for the particulate-scattering channel are presented: a transmitter with a high bit rate and a receiver with an avalanche photodiode and a transmitter with a variable bit rate and a new model for an adaptive circuit in the receiver. An improvement of more than 7 orders of magnitude in error probability under certain conditions is possible with the new adaptive system model.     

SP1 as a novel scaffold building block for self-assembly nanofabrication of submicron enzymatic structures

In this study, SP1, a ring-shaped highly stable homododecamer protein complex was utilized for the self-assembly of multiple domains in a predefined manner. Glucose oxidase (GOx) was fused in-frame to SP1 and expressed in Escherichia coli. Complexes where GOx encircled SP1 dodecamer were observed, and moreover, the enzymatic monomers self-assembled into active multienzyme nanotube particles containing hundreds of GOx molecules per tube. This work demonstrates the value of SP1 as a self-assembly scaffold.     

Time-domain near-field analysis of short-pulse antennas .II.Reactive energy and the antenna Q

For pt. I see ibid., vol.47, no.2, p.271-79 (1999). The time-domain (TD) multipole expansion, developed in the first part of this two-part sequence, is extended here to analyze the power-flow and energy balance in the vicinity of a pulsed antenna. Using the spherical transmission line formulation, we derive expressions for the pulsed power-flow and energy and identify the radiative and the reactive constituents. For time-harmonic fields, the reactive concepts are well understood in terms of the stored energy, but this interpretation is not applicable for short-pulse fields where there is no stored energy. By considering the TD energy balance, we clarify the transition of the near-zone pulsed reactive energy to the radiation power and show that the pulsed reactive energy discharges back to the source once the pulse has been radiated. We thus introduce a TD Q factor that quantifies the radiation efficiency. In particular, we show that super resolution using short-pulse fields involves large TD reactive energies and Q and is, therefore, not feasible. The general TD concepts discussed are demonstrated through a numerical example of radiation from a circular disk carrying a pulsed current distribution     

Modification of a Single Atom Affects the Physical Properties of Double Fluorinated Fmoc-Phe Derivatives

Supramolecular hydrogels formed by the self-assembly of amino-acid based gelators are receiving increasing attention from the fields of biomedicine and material science. Self-assembled systems exhibit well-ordered functional architectures and unique physicochemical properties. However, the control over the kinetics and mechanical properties of the end-products remains puzzling. A minimal alteration of the chemical environment could cause a significant impact. In this context, we report the effects of modifying the position of a single atom on the properties and kinetics of the self-assembly process. A combination of experimental and computational methods, used to investigate double-fluorinated Fmoc-Phe derivatives, Fmoc-3,4F-Phe and Fmoc-3,5F-Phe, reveals the unique effects of modifying the position of a single fluorine on the self-assembly process, and the physical properties of the product. The presence of significant physical and morphological differences between the two derivatives was verified by molecular-dynamics simulations. Analysis of the spontaneous phase-transition of both building blocks, as well as crystal X-ray diffraction to determine the molecular structure of Fmoc-3,4F-Phe, are in good agreement with known changes in the Phe fluorination pattern and highlight the effect of a single atom position on the self-assembly process. These findings prove that fluorination is an effective strategy to influence supramolecular organization on the nanoscale. Moreover, we believe that a deep understanding of the self-assembly process may provide fundamental insights that will facilitate the development of optimal amino-acid-based low-molecular-weight hydrogelators for a wide range of applications.     

Couples' shared participation in novel and arousing activities and experienced relationship quality.

Using a newspaper questionnaire, a door-to-door survey, and 3 laboratory experiments, the authors examined a proposed effect of shared participation in novel and arousing activities on experienced relationship quality. The questionnaire and survey studies found predicted correlations of reported shared "exciting" activities and relationship satisfaction plus their predicted mediation by relationship boredom. In all 3 experiments, the authors found predicted greater increases in experienced relationship quality from before to after participating together in a 7-min novel and arousing (vs. a more mundane) task. Comparison with a no-activity control showed the effect was due to the novel-arousing task. The same effect was found on ratings of videotaped discussions before and after the experimental task. Finally, all results remained after controlling for relationship social desirability. Results bear on general issues of boredom and excitement in relationships and the role of such processes in understanding the typical early decline of relationship quality after the honeymoon period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for volatile chemical attractants in the beetleMaladera matrida argaman (Coleoptera: Scarabaeidae)

TheMaladera matrida beetle (Coleoptera, Scarabaeidae, Melolonthinae), a relatively new species to science, was first identified in Israel in 1983. In the course of field observations it was found that adultM. matrida beetles emerged from the soil at sunset to feed and mate. During the first 20 min of flight, most of the beetles were males. The females emerged shortly afterwards, and aggregations numbering 20–30 individuals with equal proportions of males and females were eventually formed on peanut plants. Laboratory olfactometer bioassays showed that peanut leaves (food) attracted both males and females. Field-trapping experiments and olfactometer studies showed thatM. matrida beetles were highly attracted by live virgin females in the presence of food (cut-up peanut leaves). Another set of field trapping experiments indicated that airborne volatiles produced by live virgin females plus food had the same attracting ability as live virgin females plus food. The attraction exerted by the combination of live virgin females and peanut leave volatiles suggests a synergism effect. Accordingly, we propose a two-stage mechanism of chemical communication in theM. matrida beetles: first, the males cause mechanical damage to the host plant to attract both sexes; later, the females emit attractants (sex pheromone) while eating or shortly thereafter.     

Functionalization at the double-bond region of jojoba oil. 9. solid-state nuclear magnetic resonance characterization of substituted jojoba wax chemically bonded to a polystyrene matrix

Solid extractants for metal ions have been prepared by chemical bonding of jojoba wax to a polystyrene backbone, followed by phosphonation or sulfur-chlorination of the jojoba moiety. In this study, the intermediates and final solid products of the reactions were characterized by solid-state ¹³C and ³¹P nuclear magnetic resonance spectroscopy. The spectra showed the expected chemical shifts of the atoms involved in the chemical reactions, as well as other parts of the reacting molecules. Thus, the carbonyl carbon of the jojoba chain appears at 175 ppm, the methyl carbons at 15 ppm, the polystyrene backbone at 40–42 ppm (aliphatic carbons) and 128, 137, 143–147 (aromatic carbons). Carbons adjacent to N, S, and P appear at 45–55, 60, and 48 ppm, respectively.