Active antennas

All pump intensity dependences measured at fixed times are of the form A = aP - b(1 - exp - P/p ) where a and b are constants (depending on wavelength, tiM and redox), P is the pump intensity imJ/cmr) and P = 0.5 mJ cm , for samples with 50% transmission at the pump wavelength. The equivalent saturation parameter p for a thin sample is estimated at. 35 mJ cm , i.e. 1 x 10 photons/cm which corresponds to the value to be expected for an absorber with seme twenty active antennae chloropiiyll molecules. We have therefore identified all transients exhibiting strong saturation (b a) as due to effects in the reaction centre and the linear cemponents (a b) as due to the antennae. 

For wearable systems, including textile antennas, power efficiency represents a crucial matter, especially for the so-called autonomous systems, where the necessary power for the system operation is ideally obtained entirely by means of energy harvesting [16] from the surrounding environment, and no additional power supply is needed. Even in the case of wearable systems equipped with wearable battery units, it is very important to keep power consumption as low as possible. To this aim, several techniques were recently envisaged, by means of innovative textile antennas, such as active antennas as well as the use of multiantenna-processing techniques, such as diversity with multiple wearable antennas. 

A. Dierck, H. Rogier, F. Declercq, A wearable active antenna for global positioning system and satellite phone, IEEE Trans. Antenn. Propag. 61 (2) (February 2013) 532—538. 

In photosynthetic bacteria, (i.e., Chlorobiaceae) the bacteriochlorophyUs support photosynthesis at low light intensities, and they accomplish this activity by using a unique antenna complex known as a chlorosome in which the pigments are located. Since these bacteria are strict anaerobes, photosynthesis is nonoxygenic. ... 

Figure 12.1. Schematic diagram of a photosynthesis reaction center. Light is absorbed by pigments in the light-gathering antenna and absorbed energy is transferred to a photochemically active site P, where it is utilized to initiate photosynthetic reactions.

Identification of Activated Zeaxanthin in the Photoprotective State of Antenna.130... 

IDENTIFICATION OF ACTIVATED ZEAXANTHIN IN THE PHOTOPROTECTIVE STATE OF ANTENNA... 

Volatiles and cuticular extracts from both sexes of the currant stem girdler, Janus integer, were analyzed by GC-EAD using antenna ofboth sexes. A female specific compound, (9Z)-octadec-9-en-4-olide 7, was identified as active only on male antennas [33]. Separation by chiral GC has shown that only one enantiomer is produced in females. The synthesis ofboth enantiomers has recently been described [34] and the field testing results are forthcoming. 

Indication of a sex attractant has also been obtained for the noctuid pupal parasitoid Diapetimorpha introita (Ichneumonidae). Antennae from D. introita males gave EAG responses to diethyl ether extracts of female head, thorax or abdomen. Antennae from females did not respond to this chemical signal and male extracts elicited no activity. This suggested the presence of an extractable female-produced pheromone, to which the males respond. While live females were able to attract males, extracts were not active. This may be due to very low levels of biologically active material in the extracts [57]. 

Our neurophysiological studies have focused on three important properties of the sex-pheromonal signal its quality (chemical composition of the blend), quantity (concentrations of components), and intermit-tency [owing to the fact that the pheromone in the plume downwind from the source exists in filaments and blobs of odor-bearing air interspersed with clean air (47, 48)]. Each of these properties of the pheromonal message is important, as the male moth gives his characteristic behavioral responses only when the necessary and sufficient pheromone components A and B are present in the blend (44), when the concentrations and blend proportions of the components fall within acceptable ranges (49), and when the pheromone blend stimulates his antennae intermittently (39, 50). In our studies, we examine how each of these important aspects of the odor stimulus affects the activity of neurons at various levels in the olfactory pathway. 

An important subset of pheromone-specialist PNs in male M. sexta receives input from both component A and component B input channels, described above, but the physiological effects of the two inputs are opposite (72). That is, if antennal stimulation with component A leads to excitation, then stimulation with component B inhibits the intemeuron, and vice versa. Simultaneous stimulation of the antenna with both components A and B elicits a mixed inhibitory and excitatory response in these special PNs. Thus these neurons can discriminate between the two inputs based upon how each affects the spiking activity of the cell. These PNs also respond uniquely to the natural pheromone blend released by the female these pheromone specialist neurons have enhanced ability to follow intermittent pheromonal stimuli occurring at natural frequencies of 10 stimuli per sec (77). 

His research interests deal with the chemistry of cyclopropane derivatives, 1,3-dipolar cycloadditions, synthesis of natural compounds and biologically active analogues. Recently, the research activity is also dedicated to synthetic studies for the production of new materials light-harvesting antenna systems and functionalized organogelators. 

Fig-1 Schematic view of the overall olfactory processing in insects. Pheromones and other semiochemicals are detected by specialized sensilla on the antennae, where the chemical signal is transduced into nervous activity. The olfactory receptor neurons in the semiochemi-cal-detecting sensilla are connected directly to the antennal lobe. Here the semiochemical-derived electrical signals are processed and sent out (through projection neurons) to the protocerebrum. Olfactory information is then integrated with other stimulus modalities, a decision is made, and the motor system is told what to do... 

Fig. 4 Gas chromatographic traces of extracts from females of the pale brown chafer Phyl-lopertha diversa monitored by a conventional detector, flame-ionization detector (FID), and a biosensor, electroantennographic detector (EAD), using a male antenna as the sensing element. Although the peak of the sex pheromone (arrow) is hardly seen in the FID trace, its pheromonal activity was initially indicated by the strong EAD peak. Structural elucidation, followed by synthesis and behavioral studies lead to the identification of an unusual sex pheromone, l,3-dimethyl-2,4-(lff,3ff)-quinazolinedione [124]. It is unlikely that this minor compound would be fished out by a bioassay-oriented isolation procedure...

Earlier experiments based on EAG and SSR highlighted the inordinate specificity and sensitivity of the insect olfactory system. While minimal structural modifications to pheromone molecules render them inactive [12], a single molecule of the native ligand is estimated to be sufficient to activate an olfactory neuron in male antennae [14]. The large number of detectors certainly contributes to the sensitivity of the olfactory system, but selectivity is a matter of... 

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