Explorer 31 ion mass spectrometer experiment

Ion mass spectrometer experimental design on Explorer 31 satellite and data processing techniques for ionospheric compositio

Crassulacean acid metabolism in the Gesneriaceae

The occurrence of the Crassulacean acid metabolism (CAM) was studied in four epiphytic species of the Gesneriaceae: two neotropical species, Codonanthe crassifolia and Columnea linearis, and two paleotropical species, Aoschynanthus pulcher and Saintpaulia ionantha. Gas exchange parameters, enzymology, and leaf anatomy, including mesophyll succulence and rel­ ative percent of the mesophyll volume occupied by airspace, were studied for each species. Codonanthe crassifolia was the only species to show nocturnal CO2 uptake and a diurnal organic acid fluctuation. According to these results, Codonanthe crassifolia shows CAM-cycling under well-watered conditions and when subjected to drought, it switches to CAM-idling. Other characteristics, such as leaf anatomy, mesophyll succulence, and PEP carboxylase and NADP malic enzyme activity, indicate attributes of the CAM pathway. All other species tested showed C3 photosynthesis. The most C3-like species is Columnea linearis, according to the criteria tested in this investigation. The other two species show mesophyll succulence and relative percent of the leaf volume occupied by airspace within the CAM range, but no other characters of the CAM pathway. The leaf structure of certain genera of the Gesneriaceae and of the genus Peperomia in the Piperaceae are similar, both having an upper succulent, multiple epidermis, a medium palisade of one or a few cell layers, and a lower, succulent spongy parenchyma not too unlike CAM photosynthetic tissue. We report ecophysiological similarities between these two distantly related families. Thus, the occurrence of CAM-cycling may be more common among epiphytic species than is currently known

Annual Report Readership: A Study of an Agricultural Supply Cooperative

Recent corporate collapses have focussed attention on the (un)reliability of financial information. However, although the agricultural sector, which is significant globally, is run primarily using the cooperative form, there is scant research on these users' perception of financial information. Therefore this paper examines members' readership and understanding of the annual reports of a large, fertiliser cooperative. The findings show that there is a lack of readership of the annual report, due to a lack of understanding and a lack of time. A minority of non-readers trust directors to "do a good job". Preparers of information should focus on making reports more user-friendly and evidence suggests that financial information could be released more strategically using other sources of communication, namely other print media and the internet.cooperatives, annual reports, readership, understanding, Agribusiness,

The Role of Subsurface Flows in Solar Surface Convection: Modeling the Spectrum of Supergranular and Larger Scale Flows

We model the solar horizontal velocity power spectrum at scales larger than granulation using a two-component approximation to the mass continuity equation. The model takes four times the density scale height as the integral (driving) scale of the vertical motions at each depth. Scales larger than this decay with height from the deeper layers. Those smaller are assumed to follow a Kolomogorov turbulent cascade, with the total power in the vertical convective motions matching that required to transport the solar luminosity in a mixing length formulation. These model components are validated using large scale radiative hydrodynamic simulations. We reach two primary conclusions: 1. The model predicts significantly more power at low wavenumbers than is observed in the solar photospheric horizontal velocity spectrum. 2. Ionization plays a minor role in shaping the observed solar velocity spectrum by reducing convective amplitudes in the regions of partial helium ionization. The excess low wavenumber power is also seen in the fully nonlinear three-dimensional radiative hydrodynamic simulations employing a realistic equation of state. This adds to other recent evidence suggesting that the amplitudes of large scale convective motions in the Sun are significantly lower than expected. Employing the same feature tracking algorithm used with observational data on the simulation output, we show that the observed low wavenumber power can be reproduced in hydrodynamic models if the amplitudes of large scale modes in the deep layers are artificially reduced. Since the large scale modes have reduced amplitudes, modes on the scale of supergranulation and smaller remain important to convective heat flux even in the deep layers, suggesting that small scale convective correlations are maintained through the bulk of the solar convection zone.Comment: 36 pages, 6 figure

Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein Condensates

We study the Kelvin mode excitations on a vortex line in a three-dimensional trapped Bose-Einstein condensate at finite temperature. Our stochastic Gross-Pitaevskii simulations show that the activation of these modes can be suppressed by tightening the confinement along the direction of the vortex line, leading to a strong suppression in the vortex decay rate as the system enters a regime of two-dimensional vortex dynamics. As the system approaches the condensation transition temperature we find that the vortex decay rate is strongly sensitive to dimensionality and temperature, observing a large enhancement for quasi-two-dimensional traps. Three-dimensional simulations of the recent vortex dipole decay experiment of Neely et al. [Phys. Rev. Lett. 104, 160401 (2010)] confirm two-dimensional vortex dynamics, and predict a dipole lifetime consistent with experimental observations and suppression of Kelvon-induced vortex decay in highly oblate condensates.Comment: 8 pages, 8 figure

Valuing flexibility in the migration to flexible-grid networks

Increasing network demand is expected to put pressure on the available capacity in core networks. Flexible optical networking can now be installed to increase network capacity in light of future traffic demands. However, this technology is still in its infancy and might lack the full functionality that may appear within a few years. When replacing core network equipment, it is therefore important to make the right investment decision between upgrading toward flexible-grid or fixed-grid equipment. This paper researches various installation options using a techno-economic analysis, extended with real option insights, showing the impact of uncertainty and flexibility on the investment decision. By valuing the different options, a correct investment decision can be made

Principal component analysis of atrial fibrillation: Inclusion of posterior ECG leads does not improve correlation with left atrial activity

Background Lead V? is routinely analysed due to its large amplitude AF waveform. V? correlates strongly with right atrial activity but only moderately with left atrial activity. Posterior lead V? correlates strongest with left atrial activity. Aims (1) To establish whether surface dominant AF frequency (DAF) calculated using principal component analysis (PCA) of a modified 12-lead ECG (including posterior leads) has a stronger correlation with left atrial activity compared to the standard ECG. (2) To assess the contribution of individual ECG leads to the AF principal component in both ECG configurations. Methods Patients were assigned to modified or standard ECG groups. In the modified ECG, posterior leads V? and V? replaced V? and V?. AF waveform was extracted from one-minute surface ECG recordings using PCA. Surface DAF was correlated with intracardiac DAF from the high right atrium (HRA), coronary sinus (CS) and pulmonary veins (PVs). Results 96 patients were studied. Surface DAF from the modified ECG did not have a stronger correlation with left atrial activity compared to the standard ECG. Both ECG configurations correlated strongly with HRA, CS and right PVs but only moderately with left PVs. V? contributed most to the AF principal component in both ECG configurations

From cellular properties to population asymptotics in the Population Balance Equation

Proliferating cell populations at steady state growth often exhibit broad protein distributions with exponential tails. The sources of this variation and its universality are of much theoretical interest. Here we address the problem by asymptotic analysis of the Population Balance Equation. We show that the steady state distribution tail is determined by a combination of protein production and cell division and is insensitive to other model details. Under general conditions this tail is exponential with a dependence on parameters consistent with experiment. We discuss the conditions for this effect to be dominant over other sources of variation and the relation to experiments.Comment: Exact solution of Eq. 9 is adde

Excitation of the molecular gas in the nuclear region of M82

We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M 82. Six ^(12)CO lines, 2 ^(13)CO lines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 10^(3.5) cm^(-3)) clouds, with column densities of N_H = 10^(21.5) cm^(-2) and a relatively low UV radiation field (G_0 = 10^2). The remaining gas is predominantly found in clouds with higher densities (n = 10^5 cm^(-3)) and radiation fields (G_0 = 10^(2.75)), but somewhat lower column densities (N_H = 10^(21.2) cm^(-2)). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 10^6 cm^(-3)) and UV field (G_0 = 10^(3.25)). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies