Abstract Mass and energy exchanges with the atmosphere were compared in two soybean ( Glycine max L. Merr. cv. Harosoy) isolines differing in pubescence density. The study was conducted in a field with a Sharpsburg silty clay loam soil (fine, montmorillonitic, mesic Typic Argiudoll) during the summer of 1980 at Mead, Nehr. Mass and energy exchanges were determined by means of micrometeorological techniques. Evapotranspiration (reported in terms of latent heat flux) was reduced in the densely pubescent isoline. Canopy CO 2 exchange was unchanged on a per unit land area basis. Water use efficiency (reported in terms of the CO 2 ‐water flux ratio) was, accordingly, greater in the densely pubescent isoline. The increase in pubescence did not significantly alter the net radiation balance, turbulent mixing, canopy CO 2 exchange, or plant water status. Observed differences in the partitioning of net radiation into latent and sensible heat can be explained by greater penetration of solar radiation into the densely pubescent canopy. Leaf pubescence appears to alter the spectral characteristics of the leaf and, thus, to facilitate the penetration of solar radiation into the canopy.
Mechanical fractionation and aqueous or aqueous/organic two-phase partition approaches were applied for extraction and separation of extracellular terpenoid hydrocarbons from Botryococcus braunii var. Showa. A direct spectrophotometric method was devised for the quantitation of botryococcene and associated carotenoid hydrocarbons extracted by this method. Separation of extracellular botryococcene hydrocarbons from the Botryococcus was achieved upon vortexing of the micro-colonies with glass beads, either in water followed by buoyant density equilibrium to separate hydrocarbons from biomass, or in the presence of heptane as a solvent, followed by aqueous/organic two-phase separation of the heptane-solubilized hydrocarbons (upper phase) from the biomass (lower aqueous phase). Spectral analysis of the upper heptane phase revealed the presence of two distinct compounds, one absorbing in the UV-C, attributed to botryococcene(s), the other in the blue region of the spectrum, attributed to a carotenoid. Specific extinction coefficients were developed for the absorbance of triterpenes at 190nm (epsilon = 90 +/- 5 mM(-1) cm(-1)) and carotenoids at 450 nm (epsilon=165+/-5mM(-1) cm(-1)) in heptane. This enabled application of a direct spectrophotometric method for the quantitation of water- or heptane-extractable botryococcenes and carotenoids. B. braunii var. Showa constitutively accumulates approximately 30% of the dry biomass as extractable (extracellular) botryococcenes, and approximately 0.2% of the dry biomass in the form of a carotenoid. It was further demonstrated that heat-treatment of the Botryococcus biomass substantially accelerates the rate and yield of the extraction process. Advances in this work serve as foundation for a cyclic Botryococcus growth, non-toxic extraction of extracellular hydrocarbons, and return of the hydrocarbon-depleted biomass to growth conditions for further product generation.
Majorana fermions in a superconductor hybrid system are charge neutral\nzero-energy states. For the detection of this unique feature, we propose an\ninterferometry of a chiral Majorana edge channel, formed along the interface\nbetween a superconductor and a topological insulator under an external magnetic\nfield. The superconductor is of a ring shape and has a Josephson junction that\nallows the Majorana state to enclose continuously tunable magnetic flux.\nZero-bias differential electron conductance between the Majorana state and a\nnormal lead is found to be independent of the flux at zero temperature,\nmanifesting the Majorana feature of a charge neutral zero-energy state. In\ncontrast, the same setup on graphene has no Majorana state and shows\nAharonov-Bohm effects.\n
Nonuniform transmission line models have been developed to provide an accurate account of the impedance characteristics of sintered porous nickel electrodes when charging and discharging under stress and low earth orbit cycling regimes (described in Part I which is the preceding article). This model represents a single pore in a porous electrode by a nonuniform transmission line involving both the charged and discharged phases. The most accurate description of the impedance characteristics was obtained by assuming a conical geometry and a χ2 distribution for the penetration depth of down the pore on discharge. The modeling results indicate that charging and discharging a sintered electrode over 596 cycles increases both the number of active pores and the fraction of pores that are more deeply reduced. These two trends account for the observed increase in capacity of the electrode with cycle number.
Understanding terrestrial carbon metabolism is critical because terrestrial ecosystems play a major role in the global carbon cycle. Furthermore, humans have severely disrupted the carbon cycle in ways that will alter the climate system and directly affect terrestrial metabolism. Changes in terrestrial metabolism may well be as important an indicator of global change as the changing temperature signal. Improving our understanding of the carbon cycle at various spatial and temporal scales will require the integration of multiple, complementary and independent methods that are used by different research communities. Tools such as air sampling networks, inverse numerical methods, and satellite data (top-down approaches) allow us to study the strength and location of the global- and continental-scale carbon sources and sinks. Bottom-up studies provide estimates of carbon fluxes at finer spatial scales and examine the mechanisms that control fluxes at the ecosystem, landscape, and regional scales. Bottom-up approaches include comparative and process studies (for example, ecosystem manipulative experiments) that provide the necessary mechanistic information to develop and validate terrestrial biospheric models. An iteration and reiteration of top-down and bottom-up approaches will be necessary to help constrain measurements at various scales. We propose a major international effort to coordinate and lead research programs of global scope of the carbon cycle.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Chaotic digital code-division multiple access ((CD) 2 MA) systems are new types of communication systems using chaotic carriers. (CD) 2 MA had found applications in both wireless and other communication systems. In this paper we study the error performance of chaotic digical code-division multiple access ((CD) 2 MA) systems used in both wireless environment and cable networks. We present first the details of the interleave mode of the (CD) 2 MA. When a (CD) 2 MA system works in the interleave mode, each of its transmitters only transmits signals during a portion of the bit duration of the message signal. The total interference level is thus reduced which in turn increases the channel capacity. The relationship between the bit error rate (BER) and the interleave rate is studied in both the synchronous (CD) 2 MA system used in cable systems, and the asynchronous (CD) 2 MA system used in wireless environments. Our simulation results show that in a cable system the synchronous (CD) 2 MA system can support 1.5 times more channel capacity than synchronous CDMA systems, and double the channel capacity of CDMA systems in wireless environments.
