Mechanism of the Enzymic Reduction of N_2: The Binding of Adenosine 5'-Triphosphate and Cyanide to the N_2-reducing System

The in vitro reduction of N_2 is a complex process involving at least six different reactants: two proteins [1,2] for which the names azoferredoxin (AzoFd) and molybdoferredoxin (MoFd) have been proposed[3], an electron source, the electron acceptor, ATP[4], and Mg2+[5-7]. One of the goals of research in this area is to define the orderly and quantitative participation of these reactants leading to the reduction of the electron acceptor with concomitant breakdown of ATP to ADP and inorganic phosphate[7]. The work described in this paper shows that (1) AzoFd reversibly binds both ATP, a reactant in N2 reduction, and ADP, a specific inhibitor of N2 reduction, and (2) MoFd reversibly binds cyanide, which is also reduced by the N_2-reducing system. It is suggested that the binding of ATP and of cyanide are partial reactions of the N_2-reducing system

The Battle Of Peach Tree Creek: Hood\u27s First Effort To Save Atlanta

Foreshadowing the Fall: A Prelude On July 20, 1864, Union and Confederate forces clashed on the northern outskirts of Atlanta in the first of several major battles for the city. At Peach Tree Creek General John Bell Hood, the newly appointed as Commander of the Confederate Army of Tennessee, launch...

Visual to Sound: Generating Natural Sound for Videos in the Wild

As two of the five traditional human senses (sight, hearing, taste, smell, and touch), vision and sound are basic sources through which humans understand the world. Often correlated during natural events, these two modalities combine to jointly affect human perception. In this paper, we pose the task of generating sound given visual input. Such capabilities could help enable applications in virtual reality (generating sound for virtual scenes automatically) or provide additional accessibility to images or videos for people with visual impairments. As a first step in this direction, we apply learning-based methods to generate raw waveform samples given input video frames. We evaluate our models on a dataset of videos containing a variety of sounds (such as ambient sounds and sounds from people/animals). Our experiments show that the generated sounds are fairly realistic and have good temporal synchronization with the visual inputs.Comment: Project page: http://bvision11.cs.unc.edu/bigpen/yipin/visual2sound_webpage/visual2sound.htm

Hood’s Texas Brigade: The Soldiers and Families of the Confederacy’s Most Celebrated Unit

General John Bell Hood was not the first commander of the Texas Brigade, but he was at the helm when the unit won lasting fame during the battles of 1862 in the Eastern Theatre. Indeed, the Brigade compiled a distinguished record of service: Seven Days, Second Manassas, Antietam, Gettysburg, Chickamauga, the Overland Campaign, and fittingly, Appomattox. The Texans paid dearly for their glory. At Antietam in 1862 the Brigade suffered a 64% casualty rate; the 1st Texas Infantry alone lost 86% its members (128). Some 1,300 went to Georgia in 1864 for the late summer campaign; 570 because casualties (192). At war’s end, only 617 men of the Brigade remained to surrender at Appomattox (250)

Predicting species' tolerance to salinity and alkalinity using distribution data and geochemical modelling: a case study using Australian grasses

BACKGROUND AND AIMS: Salt tolerance has evolved many times independently in different plant groups. One possible explanation for this pattern is that it builds upon a general suite of stress-tolerance traits. If this is the case, then we might expect a correlation between salt tolerance and other tolerances to different environmental stresses. This association has been hypothesized for salt and alkalinity tolerance. However, a major limitation in investigating large-scale patterns of these tolerances is that lists of known tolerant species are incomplete. This study explores whether species' salt and alkalinity tolerance can be predicted using geochemical modelling for Australian grasses. The correlation between taxa found in conditions of high predicted salinity and alkalinity is then assessed. METHODS: Extensive occurrence data for Australian grasses is used together with geochemical modelling to predict values of pH and electrical conductivity to which species are exposed in their natural distributions. Using parametric and phylogeny-corrected tests, the geochemical predictions are evaluated using a list of known halophytes as a control, and it is determined whether taxa that occur in conditions of high predicted salinity are also found in conditions of high predicted alkalinity. KEY RESULTS: It is shown that genera containing known halophytes have higher predicted salinity conditions than those not containing known halophytes. Additionally, taxa occurring in high predicted salinity tend to also occur in high predicted alkalinity. CONCLUSIONS: Geochemical modelling using species' occurrence data is a potentially useful approach to predict species' relative natural tolerance to challenging environmental conditions. The findings also demonstrate a correlation between salinity tolerance and alkalinity tolerance. Further investigations can consider the phylogenetic distribution of specific traits involved in these ecophysiological strategies, ideally by incorporating more complete, finer-scale geochemical information, as well as laboratory experiments.This work was supported by the Australian Research Council

Numerical studies of the Lagrangian approach for reconstruction of the conductivity in a waveguide

We consider an inverse problem of reconstructing the conductivity function in a hyperbolic equation using single space-time domain noisy observations of the solution on the backscattering boundary of the computational domain. We formulate our inverse problem as an optimization problem and use Lagrangian approach to minimize the corresponding Tikhonov functional. We present a theorem of a local strong convexity of our functional and derive error estimates between computed and regularized as well as exact solutions of this functional, correspondingly. In numerical simulations we apply domain decomposition finite element-finite difference method for minimization of the Lagrangian. Our computational study shows efficiency of the proposed method in the reconstruction of the conductivity function in three dimensions

Zero Entropy Interval Maps And MMLS-MMA Property

We prove that the flow generated by any interval map with zero topological entropy is minimally mean-attractable (MMA) and minimally mean-L-stable (MMLS). One of the consequences is that any oscillating sequence is linearly disjoint with all flows generated by interval maps with zero topological entropy. In particular, the M\"obius function is orthogonal to all flows generated by interval maps with zero topological entropy (Sarnak's conjecture for interval maps). Another consequence is a non-trivial example of a flow having the discrete spectrum.Comment: 12 page

Demonstration of wide band RF photonic transversal phase-shifter

A transversal phase-shifter using multiple MZMs is demonstrated. The device exhibits continuously variable phase-shift exceeding 360° at 2 GHz and amplitude uniformity within 3 dB over 0.2-2 GHz. The device stability and practicality are discussed

Multi-channel vector sum phase shifter

A novel multichannel vector sum phase shifter that is suitable for phased array antenna applications is demonstrated. Each channel is implemented using a distinct optical wavelength. Selective control of each channel is performed using an acousto-optic polarization coupler. The concept is successfully demonstrated for two individually controlled channels. For each channel, a continuously variable frequency linear phase shift is demonstrated between DC and 7 GHz, with the phasing range exceeding 100 degrees