Nodule Initiation Elicited by Noninfective Mutants of \u3cem\u3eRhizobium phaseoli\u3c/em\u3e

Rhizobium phaseoli CE106, CE110, and CE115, originally derived by transposon mutagenesis (Noel et al., J. Bacteriol. 158:149-155, 1984), induced the formation of uninfected root nodule-like swellings on bean (Phaseolus vulgaris). Bacteria densely colonized the root surface, and root hair curling and initiation of root cortical-cell divisions occurred normally in mutant-inoculated seedlings, although no infection threads formed. The nodules were ineffective, lacked leghemoglobin, and were anatomically distinct from normal nodules. Ultrastructural specialization for ureide synthesis, characteristic of legumes that form determinate nodules, was absent. Colony morphology of the mutant strains on agar plates was less mucoid than that of the wild type, and under some cultural conditions, the mutants did not react with Cellufluor, a fluorescent stain for β-linked polysaccharide. These observations suggest that the genetic lesions in these mutants may be related to extracellular polysaccharide synthesis

Microscopic study of 240Pu, mean-field and beyond

The influence of exact angular-momentum projection and configuration mixing on properties of a heavy, well-deformed nucleus is discussed for the example of Pu240. Starting from a self-consistent model using Skyrme interactions, we analyze the resulting modifications of the deformation energy, the fission barrier height, the excitation energy of the superdeformed minimum associated with the fission isomer, the structure of the lowest rotational bands with normal deformation and superdeformation, and the corresponding quadrupole moments and transition moments. We present results obtained with the Skyrme interactions SLy4 and SLy6, which have slightly different surface tensions.Comment: 7 pages REVTEX4, 4 figures. accepted for publication in Phys. Rev.

An Efficient Beam Steerable Antenna Array Concept for Airborne Applications

Deployment of a satellite borne, steerable antenna array with higher directivity and gain in Low Earth Orbit makes sense to reduce ground station complexity and cost, while still maintaining a reasonable link budget. The implementation comprises a digitally beam steerable phased array antenna integrated with a complete system, comprising the antenna, hosting platform, ground station, and aircraft based satellite emulator to facilitate convenient aircraft based testing of the antenna array and ground-space communication link. This paper describes the design, development and initial successful interim testing of the various subsystems. A two element prototype used in this increases the signal-to-noise ratio (SNR) by 3 dB which is corresponding to more than 10 times better bit error rate (BER)

Positive Digital Communication Among Youth: The Development and Validation of the Digital Flourishing Scale for Adolescents

Research has extensively studied the negative effects of digital communication on adolescents’ well-being. However, positive digital experiences and behavior in adolescence are still poorly understood. The recently developed Digital Flourishing Scale addresses this gap and focuses on the positive perceptions of a user’s experiences and behaviors in digital communication among adults. In this paper, we developed an adolescent version of this scale. Study 1 demonstrated the internal consistency of the scale and the same factor structure for adolescence as for adulthood: connectedness, civil participation, positive social comparison, authentic self-presentation, and self-control. Study 2 confirmed the identified factor structure with a second sample of adolescents and established measurement invariance across genders. The construct validity of the scale was confirmed by investigating associations with related constructs, including the basic psychological needs from self-determination theory (competence, autonomy, and relatedness), secure attachment to a close friend, Internet aggression, social media-induced inspiration, authenticity of posted positive content, and social media self-control failure. The results indicated that not all adolescents flourish equally online. Differences occurred depending on the adolescents’ gender and socioeconomic status. The paper concludes that the newly developed scale is a valid and reliable measure for assessing adolescents’ perceptions of digital thriving and digital empowerment

Characterization of a Plain Broadband Textile PIFA

Bandwidth characteristic of a wearable antenna is one of the major factors in determining its usability on the human body. In this work, a planar inverted-F antenna (PIFA) structure is proposed to achieve a large bandwidth to avoid serious antenna reflection coefficient detuning when placed in proximity of the body. The proposed structure is designed based on a simple structure, in order to provide practicality in application and maintain fabrication simplicity. Two different types of conductive textiles, namely Pure Copper Polyester Taffeta Fabric (PCPTF) and ShieldIt, are used in order to proof its concept, in comparison with a metallic antenna made from copper foil. The design is spaced and fabricated using a 6 mm thick fleece fabric. To cater for potential fabrication and material measurement inaccuracies, both antennas' performance are also investigated and analyzed with varying physical and material parameters. From this investigation, it is found that the proposed structure's extended bandwidth enabled the antenna to function with satisfactory on-body reflection coefficients, despite unavoidable gain and efficiency reduction

An evaporation-based model of thermal neutron induced ternary fission of plutonium

Ternary fission probabilities for thermal neutron induced fission of plutonium are analyzed within the framework of an evaporation-based model where the complexity of time-varying potentials, associated with the neck collapse, are included in a simplistic fashion. If the nuclear temperature at scission and the fission-neck-collapse time are assumed to be ~1.2 MeV and ~10^-22 s, respectively, then calculated relative probabilities of ternary-fission light-charged-particle emission follow the trends seen in the experimental data. The ability of this model to reproduce ternary fission probabilities spanning seven orders of magnitude for a wide range of light-particle charges and masses implies that ternary fission is caused by the coupling of an evaporation-like process with the rapid re-arrangement of the nuclear fluid following scission.Comment: 25 pages, 12 figures, accepted for publication in IJMP

Particle transfer and fusion cross-section for Super-heavy nuclei in dinuclear system

Within the dinuclear system (DNS) conception, instead of solving Fokker-Planck Equation (FPE) analytically, the Master equation is solved numerically to calculate the fusion probability of super-heavy nuclei, so that the harmonic oscillator approximation to the potential energy of the DNS is avoided. The relative motion concerning the energy, the angular momentum, and the fragment deformation relaxations is explicitly treated to couple with the diffusion process, so that the nucleon transition probabilities, which are derived microscopically, are time-dependent. Comparing with the analytical solution of FPE, our results preserve more dynamical effects. The calculated evaporation residue cross sections for one-neutron emission channel of Pb-based reactions are basically in agreement with the known experimental data within one order of magnitude.Comment: 19 pages, plus 6 figures, submitted to Phys. Rev.