cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Heterojunction Hybrid Devices from Vapor Phase Grown MoS$_{2}$
Creators: name: Yim, Chanyoung
name: O`Brien, Maria
name: McEvoy, Niall
name: Riazimehr, Sarah
name: Schäfer-Eberwein, Heiko
name: Bablich, Andreas
name: Pawar, Ravinder
name: Iannaccone, Giuseppe
name: Downing, Clive
name: Fiori, Gianluca
name: Lemme, Max C.
name: Duesberg, Georg S.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigate a vertically-stacked hybrid photodiode consisting of a thin n-type molybdenum disulfide (MoS$_{2}$) layer transferred onto p-type silicon. The fabrication is scalable as the MoS$_{2}$ is grown by a controlled and tunable vapor phase sulfurization process. The obtained large-scale p-n heterojunction diodes exhibit notable photoconductivity which can be tuned by modifying the thickness of the MoS$_{2}$ layer. The diodes have a broad spectral response due to direct and indirect band transitions of the nanoscale MoS$_{2}$. Further, we observe a blue-shift of the spectral response into the visible range. The results are a significant step towards scalable fabrication of vertical devices from two-dimensional materials and constitute a new paradigm for materials engineering.
description: 23 pages with 4 figures. This article has been published in Scientific Reports. (26 June 2014, doi:10.1038/srep05458)
Genetic and physical organization of the cloned gyrA and gyrB genes of Bacillus subtilis.
Creators: name: The University of North Carolina at Chapel Hill University Libraries
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1985

description: An 8-kilobase fragment already known to contain the gyrA gene of Bacillus subtilis was shown to encode the gyrB gene as well. Plasmids containing this fragment can rescue both B. subtilis gyrA and gyrB mutants and complement Escherichia coli gyrA mutants. Deletion analysis has indicated the gene locations on the cloned fragment. Under low-stringency conditions the cloned E. coli gyrA and gyrB genes each hybridized to the appropriate subfragments, confirming the assignment of the gene locations on the cloned DNA. In E. coli maxicells, proteins of 67,000 (gyrA) and 77,000 (gyrB) Mr were synthesized. Analysis of proteins encoded by various subfragments indicated the direction of transcription. Although the gyrA and gyrB genes are located adjacent to each other on the chromosome, they may be transcribed independently since expression of gyrA protein is not dependent upon the gyrB gene in maxicells.
CDRNet: Accurate Cup-to-Disc Ratio Measurement with Tight Bounding Box Supervision in Fundus Photography Using Deep Learning
Creators: name: Wang, Juan
name: Xia, Bin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: The cup-to-disc ratio (CDR) is one of the most significant indicator for glaucoma diagnosis. Different from the use of costly fully supervised learning formulation with pixel-wise annotations in the literature, this study investigates the feasibility of accurate CDR measurement in fundus images using only tight bounding box supervision. For this purpose, we develop a two-task network named as CDRNet for accurate CDR measurement, one for weakly supervised image segmentation, and the other for bounding-box regression. The weakly supervised image segmentation task is implemented based on generalized multiple instance learning formulation and smooth maximum approximation, and the bounding-box regression task outputs class-specific bounding box prediction in a single scale at the original image resolution. To get accurate bounding box prediction, a class-specific bounding-box normalizer and an expected intersection-over-union are proposed. In the experiments, the proposed approach was evaluated by a testing set with 1200 images using CDR error and $F_1$ score for CDR measurement and dice coefficient for image segmentation. A grader study was conducted to compare the performance of the proposed approach with those of individual graders. The experimental results indicate that the proposed approach outperforms the state-of-the-art performance obtained from the fully supervised image segmentation (FSIS) approach using pixel-wise annotation for CDR measurement. Its performance is also better than those of individual graders. In addition, the proposed approach gets performance close to the state-of-the-art obtained from FSIS and the performance of individual graders for optic cup and disc segmentation. The codes are available at \url{https://github.com/wangjuan313/CDRNet}.
description: 18 pages, 7 figures, 8 tables, Multimedia Tools and Applications
INVESTIGATING OF THE MIXED MODE CRACK PROBLEMS IN NONHOMOGENOUS MATERIALS UNDER UNIFORM HEAT FLOW
Creators: Fengnan, Guo
Yanyan, Zhang
Licheng, Guo
Hongjun, Yu
Publisher: name: University of Alberta Library
Year: 2022

Conference abstract. Part of the Proceedings of the Canadian Society for Mechanical Engineering International Congress 2022.
Molecular cloning of nif DNA from Azotobacter vinelandii.
Creators: name: The University of North Carolina at Chapel Hill University Libraries
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1985

description: Two clones which contained nif DNA were isolated from a clone bank of total EcoRI-digested Azotobacter vinelandii DNA. The clones carrying the recombinant plasmids were identified by use of the 32P-labeled 6.2-kilobase (kb) nif insert from pSA30 (which contains the Klebsiella pneumoniae nifK, nifD, and nifH genes) as a hybridization probe. Hybridization analysis with fragments derived from the nif insert of pSA30 showed that the 2.6-kb insert from one of the plasmids (pLB1) contains nifK whereas the 1.4-kb insert from the other plasmid (pLB3) contains nifD. Marker rescue tests using genetic transformation indicated that the 2.6-kb A. vinelandii nif fragment contains the wild-type alleles for the nif-6 and nif-38 mutations carried by Nif- strains UW6 and UW38. The 1.4-kb insert contains the wild-type allele for the nif-10 mutation carried by Nif- strain UW10.
Graphene, a material for high temperature devices; intrinsic carrier density, carrier drift velocity, and lattice energy
Creators: name: Yin, Yan
name: Cheng, Zengguang
name: Wang, Li
name: Jin, Kuijuan
name: Wang, Wenzhong
Publisher: name: arXiv
Year: 2014
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of the intrinsic G mode phonon energy. Above knowledge is vital in understanding the physical phenomena of graphene under high power or high temperature.
Proper interaction between at least two components is required for efficient export of proteins to the Escherichia coli cell envelope.
Creators: name: The University of North Carolina at Chapel Hill University Libraries
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1985

description: An Escherichia coli mutant carrying delta malE12-18, a 21-base pair deletion confined to the coding DNA of the maltose-binding protein signal peptide, is unable to export maltose-binding protein to the periplasm efficiently. Consequently, such a strain is defective for the utilization of maltose as a sole carbon source. We obtained 16 mutants harboring extragenic delta malE12-18 suppressor mutations that exhibit partial restoration of export to the mutant maltose-binding protein. A genetic analysis of these extragenic suppressor mutations demonstrated that 15 map at prlA, at 72 min on the standard E. coli linkage map, and that 1 maps at a new locus, prlD, at 2.5 min on the linkage map. Our evidence indicates that the prlA and prlD gene products play an important role in the normal pathway for export of proteins to the cell envelope. Efficient execution of the secretory process requires that these prl gene products interact properly with each other so that a productive interaction of these gene products with the signal peptide also can occur. Our data suggest that proper assembly of a complex is required for efficient export of E. coli envelope proteins to their various extracytoplasmic compartments.
To theory of asymptotically stable accelerating Universe in Riemann-Cartan spacetime
Creators: name: Garkun, A. S.
name: Kudin, V. I.
name: Minkevich, A. V.
Publisher: name: arXiv
Year: 2014
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Homogeneous isotropic cosmological models built in the framework of the Poincaré gauge theory of gravity based on general expression of gravitational Lagrangian with indefinite parameters are analyzed. Special points of cosmological solutions for flat cosmological models at asymptotics and conditions of their stability in dependence of indefinite parameters are found. Procedure of numerical integration of the system of gravitational equations at asymptotics is considered. Numerical solution for accelerating Universe without dark energy is obtained.
description: 13 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:1107.1566
Repair of cis-platinum-DNA adducts by ABC excinuclease in vivo and in vitro.
Creators: name: The University of North Carolina at Chapel Hill University Libraries
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1985

description: cis-Platinum compounds, which are used in cancer chemotherapy, are thought to exert their effect by damaging DNA. It is known that this damage is partially repaired in Escherichia coli. Using cis-Pt-treated pBR322 DNA as a probe, we investigated the role of nucleotide excision repair in the removal of Pt-DNA adducts. We found that the nucleotide excision pathway was the major mechanism for repairing Pt adducts in transforming plasmid DNA but that a recA-dependent pathway also contributed to plasmid survival. When cis-Pt-damaged pBR322 was treated with the purified nucleotide excision enzyme ABC excinuclease in vitro, a fraction of the adducts was removed by the enzyme; this removal resulted in a corresponding increase in transformation efficiency.
Effects of strong magnetic fields on the population of hyperon stars
Creators: name: Gomes, R. O.
name: Dexheimer, V.
name: Vasconcellos, C. A. Z.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In this contribution we study the effects of strong magnetic fields on the particle population of neutron stars with hyperon degrees of freedom in their composition. The star matter is described by a multi-component model with parameterized baryon-meson interaction couplings. We study the magnetic effects on the equation of state (EoS) due to the Landau quantization, assuming a density dependent static magnetic field that reaches about $10^{19}\,G$ in the center of the star. The Tolman-Oppenheimer-Volkoff equations are solved in order to understand the dependence of the mass-radius relation and hyperon population on the magnetic field intensity assuming different interaction coupling schemes.
description: Prepared for conference STARS2013 - 2nd Caibbean Symposium on Cosmology, Gravitaion, Nuclear and Astroparticle Physics / SMFNS2013 - 3rd International Symposium on Strong Electromagnetic Fields and Neutron Stars
On the energy landscape of symmetric quantum signal processing
Creators: name: Wang, Jiasu
name: Dong, Yulong
name: Lin, Lin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Symmetric quantum signal processing provides a parameterized representation of a real polynomial, which can be translated into an efficient quantum circuit for performing a wide range of computational tasks on quantum computers. For a given polynomial $f$, the parameters (called phase factors) can be obtained by solving an optimization problem. However, the cost function is non-convex, and has a very complex energy landscape with numerous global and local minima. It is therefore surprising that the solution can be robustly obtained in practice, starting from a fixed initial guess $Φ^0$ that contains no information of the input polynomial. To investigate this phenomenon, we first explicitly characterize all the global minima of the cost function. We then prove that one particular global minimum (called the maximal solution) belongs to a neighborhood of $Φ^0$, on which the cost function is strongly convex under the condition ${\left\lVert f\right\rVert}_{\infty}=\mathcal{O}(d^{-1})$ with $d=\mathrm{deg}(f)$. Our result provides a partial explanation of the aforementioned success of optimization algorithms.
description: 48 pages, 6 figures
Spontaneous jamming and unjamming in a hopper with multiple exit orifices
Creators: name: Kunte, Amit
name: Doshi, Pankaj
name: Orpe, Ashish V.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We show that the flow of granular material inside a 2-dimensional flat bottomed hopper is altered significantly by having more than one exit orifice. For the hoppers with small orifice widths, inter-mittent flow through one orifice enables the resumption of flow through the adjacent jammed orifice, thus displaying a sequence of jamming and unjamming events. Using discrete element simulations, we show that the total amount of granular material (i.e. avalanche size) emanating from all the orifices combined can be enhanced by about an order of magnitude difference by simply adjusting the inter-orifice distance. The unjamming is driven primarily by fluctuations alone when the inter-orifice distance is large, but when the orifices are brought close enough, the fluctuations along with the mean flow cause the flow unjamming.
description: 5 pages, 4 figures
Winding vacuum energies in a deformed O(4) sigma model
Creators: name: Bazhanov, Vladimir V.
name: Kotousov, Gleb A.
name: Lukyanov, Sergei L.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider the problem of calculating the Casimir energies in the winding sectors of Fateev's SS-model, which is an integrable two-parameter deformation of the O(4) non-linear sigma model in two dimensions. This problem lies beyond the scope of all traditional methods of integrable quantum field theory including the thermodynamic Bethe ansatz and non-linear integral equations. Here we propose a solution based on a remarkable correspondence between classical and quantum integrable systems and express the winding energies in terms of certain solutions of the classical sinh-Gordon equation.
description: 10 pages, 4 figures
Construction of isogenic gonococcal strains varying in the presence of a 4.2-kilobase cryptic plasmid.
Creators: name: Graves, J
name: Sparling, P F
name: Schwalbe, R
name: Biswas, G D
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1986

description: A 4.2-kilobase (kb) cryptic plasmid is present in 96% of isolates of Neisseria gonorrhoeae. An inability to construct isogenic derivatives which vary in the presence of the 4.2-kb plasmid has prevented the study of its function. We report a method to deliver an intact 4.2-kb plasmid into plasmidless gonococcal strains. The method involved transformation with novel 15.7-kb hybrid penicillinase-producing (Pcr) plasmids, which were cointegrates containing two copies of the 4.2-kb plasmid arranged in tandem direct repeat plus one copy of the 7.2-kb Pcr plasmid pFA3. When the 15.7-kb hybrid Pcr plasmids were introduced into a gonococcal recipient lacking evident plasmids, they dissociated at a relatively high frequency into plasmids identical to their parents: the 4.2-kb cryptic plasmid and pFA10 (a stable 11.5-kb plasmid containing one copy of each of the 7.2-kb Pcr plasmid pFA3 and the 4.2-kb cryptic plasmid pFA1). Curing strains of their Pcr plasmids resulted in isogenic strains which varied only in the presence of the 4.2-kb plasmid. The presence of the autonomously replicating 4.2-kb plasmid did not affect a number of tested phenotypes, including auxotype, antibiotic sensitivity, and frequencies of variation of outer membrane protein II. The interpretation of the functional significance of the 4.2-kb plasmid was complicated, however, by the additional finding that each of three tested plasmid-free strains contained a chromosomal fragment of about 1.6 kb that hybridized under moderate stringency with a 1.65-kb HinfI fragment of the 4.2-kb plasmid.
Mutually unbiased frames
Creators: name: Perez, F. Caro
name: Avella, V. Gonzalez
name: Goyeneche, D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In this work, the concept of mutually unbiased frames is introduced as the most general notion of unbiasedness for sets composed by linearly independent and normalized vectors. It encompasses the already existing notions of unbiasedness for orthonormal bases, regular simplices, equiangular tight frames, positive operator valued measure, and also includes symmetric informationally complete quantum measurements. After introducing the tool, its power is shown by finding the following results about the last mentioned class of constellations: (i) real fiducial states do not exist in any even dimension, and (ii) unknown $d$-dimensional fiducial states are parameterized, a priori, with roughly $3d/2$ real variables only, without loss of generality. Furthermore, multi-parametric families of pure quantum states having minimum uncertainty with regard to several choices of $d+1$ orthonormal bases are shown, in every dimension $d$. These last families contain all existing fiducial states in every finite dimension, and the bases include maximal sets of $d+1$ mutually unbiased bases, when $d$ is a prime number.
description: 17 pages, 2 figures
Genetic transformation of genes for protein II in Neisseria gonorrhoeae.
Creators: name: Schwalbe, R S
name: Cannon, J G
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1986

description: The protein II (PII) outer membrane proteins of Neisseria gonorrhoeae are a family of heat-modifiable proteins that are subject to phase variation, in which the synthesis of different PII species is turned on and off at a high frequency. Transformation of PII genes from a donor gonococcal strain into a recipient strain was detected with monoclonal antibodies specific for the PII proteins of the donor. Individual PII protein-expressing transformants generally bound only one donor-specific PII monoclonal antibody. Recovery of transformants expressing a donor-specific PII protein depended on the PII protein expression state of the donor: the transformed population bound only monoclonal antibodies specific for PII proteins that were expressed in the donor. Colony variants with an altered frequency of switching of PII protein expression were isolated, but the altered switch phenotype did not cotransform with the PII structural gene. These results provide genetic evidence that PII proteins are the products of different genes and that expressed and unexpressed forms of the PII gene are different from each other.
Higher order Lagrange-Poincaré and Hamilton-Poincaré reductions
Creators: name: Gay-Balmaz, François
name: Holm, Darryl D.
name: Ratiu, Tudor S.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 70H50, 37J15, 70H25, 70H30

description: Motivated by the problem of longitudinal data assimilation, e.g., in the registration of a sequence of images, we develop the higher-order framework for Lagrangian and Hamiltonian reduction by symmetry in geometric mechanics. In particular, we obtain the reduced variational principles and the associated Poisson brackets. The special case of higher order Euler-Poincaré and Lie-Poisson reduction is also studied in detail.
description: This paper has appeared in 2011 in the Journal of the Brazilian Mathematical Society 42(4), 579--606
High-spin torus isomers and their precession motions
Creators: name: Ichikawa, T.
name: Matsuyanagi, K.
name: Maruhn, J. A.
name: Itagaki, N.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We systematically investigate the existence of exotic torus isomers and their precession motions for a series of $N=Z$ even-even nuclei from $^{28}$Si to $^{56}$Ni. We analyze the microscopic shell structure of the torus isomer and discuss why the torus shape is generated beyond the limit of large oblate deformation. We use the cranked three-dimensional Hartree-Fock (HF) method with various Skyrme interactions in a systematic search for high-spin torus isomers. We use the three-dimensional time-dependent Hartree-Fock (TDHF) method for describing the precession motion of the torus isomer. We obtain high-spin torus isomers in $^{36}$Ar, $^{40}$Ca, $^{44}$Ti, $^{48}$Cr, and $^{52}$Fe. The emergence of the torus isomers is associated with the alignments of single-particle angular momenta, which is the same mechanism as found in $^{40}$Ca. It is found that all the obtained torus isomers execute the precession motion at least two rotational periods. The moment of inertia about a perpendicular axis, which characterizes the precession motion, is found to be close to the classical rigid-body value. The high-spin torus isomer of $^{40}$Ca is not an exceptional case. Similar torus isomers exist widely in nuclei from $^{36}$Ar to $^{52}$Fe and they execute the precession motion. The torus shape is generated beyond the limit of large oblate deformation by eliminating the $0s$ components from all the deformed single-particle wave functions to maximize their mutual overlaps.
Resolving puzzles of the phase-transformation-based mechanism of the deep-focus earthquake
Creators: name: Levitas, Valery I.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: Deep-focus earthquakes that occur at 350-660 km, where pressures 12-23 GPa and temperature 1800-2000 K, are generally assumed to be caused by olivine-spinel phase transformation (PT). However, there are many existing puzzles: (a) What are the mechanisms for jump from geological 10^-17-10^-15 1/s to seismic 10-10^3 1/s strain rates? Is it possible without PT? (b) How does metastable olivine, which does not completely transform to spinel at high temperature and deeply in the region of stability of spinel for over the million years, suddenly transforms during seconds and generates seismic strain rates 10-10^3 1/s? (c) How to connect deviatorically dominated seismic signals with volume-change dominated PT strain during PT? Here we introduce a combination of several novel concepts that allow us to resolve the above puzzles quantitatively. We treat the PT in olivine like plastic strain-induced (instead of pressure/stress-induced) and find an analytical 3D solution for coupled deformation-PT-heating processes in a shear band. This solution predicts conditions for severe (singular) transformation-induced plasticity (TRIP) and self-blown-up TRIP-PT-heating process due to positive thermomechanochemical feedback between TRIP and strain-induced PT. In nature, this process leads to temperature in a band exceeding the unstable stationary temperature, above which the self-blown-up shear-heating process in the shear band occurs after finishing the PT. Without PT and TRIP, significant temperature and strain rate increase is impossible. Due to the much smaller band thickness in the laboratory, heating within the band does not occur, and plastic flow after the PT is very limited. Our findings change the main concepts in studying the initiation of the deep-focus earthquakes and PTs during plastic flow in geophysics in general.
description: 23 pages, 11 figures
On Cooperative Multiple Access Channels with Delayed CSI at Transmitters
Creators: name: Zaidi, Abdellatif
name: Shamai, Shlomo
Publisher: name: arXiv
Year: 2014
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: We consider a cooperative two-user multiaccess channel in which the transmission is controlled by a random state. Both encoders transmit a common message and, one of the encoders also transmits an individual message. We study the capacity region of this communication model for different degrees of availability of the states at the encoders, causally or strictly causally. In the case in which the states are revealed causally to both encoders but not to the decoder we find an explicit characterization of the capacity region in the discrete memoryless case. In the case in which the states are revealed only strictly causally to both encoders, we establish inner and outer bounds on the capacity region. The outer bound is non-trivial, and has a relatively simple form. It has the advantage of incorporating only one auxiliary random variable. We then introduce a class of cooperative multiaccess channels with states known strictly causally at both encoders for which the inner and outer bounds agree; and so we characterize the capacity region for this class. In this class of channels, the state can be obtained as a deterministic function of the channel inputs and output. We also study the model in which the states are revealed, strictly causally, in an asymmetric manner, to only one encoder. Throughout the paper, we discuss a number of examples; and compute the capacity region of some of these examples. The results shed more light on the utility of delayed channel state information for increasing the capacity region of state-dependent cooperative multiaccess channels; and tie with recent progress in this framework.
description: 54 pages. To appear in IEEE Transactions on Information Theory. arXiv admin note: substantial text overlap with arXiv:1201.3278
Explaining Mercury's Density through Magnetic Erosion
Creators: name: Hubbard, Alexander
Publisher: name: arXiv
Year: 2014
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: In protoplanetary disks, dust grains rich in metallic iron can attract each other magnetically. If they are magnetized to values near saturation, the magnetically induced collision speeds are high enough to knock off the non-magnetized, loosely bound silicates. This process enriches the surviving portions of the dust grains in metallic iron, which further enhances the magnetically mediated collisions. The magnetic enhancement to the collisional cross-section between the iron rich dust results in rapid grain growth leading to planetesimal formation. While this process of knocking off silicates, which we term "magnetic erosion", occurs only in a very limited portion of a protoplanetary disk, it is a possible explanation for Mercury's disproportionately large iron core.
description: 8 pages, 2 figures, accepted, Icarus
Linearization of donor DNA during plasmid transformation in Neisseria gonorrhoeae.
Creators: name: Sparling, P F
name: Burnstein, K L
name: Biswas, G D
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1986

description: We examined the fate of plasmid DNA after uptake during transformation in Neisseria gonorrhoeae. An 11.5-kilobase plasmid, pFA10, was processed to linear double-stranded DNA during uptake by competent cells, but cleavage of pFA10 was not site specific. A minority of pFA10 entered as open circles. A 42-kilobase plasmid, pFA14, was degraded into small fragments during uptake; no intracellular circular forms of pFA14 were evident. Since pFA10 DNA linearized by a restriction enzyme was not further cut during uptake, the endonucleolytic activity associated with entry of plasmid DNA appeared to act preferentially on circular DNA. Although linear plasmid DNA was taken up into a DNase-resistant state as efficiently as circular DNA, linear plasmid DNA transformed much less efficiently than circular plasmid DNA. These data suggest that during entry transforming plasmid DNA often is processed to double-stranded linear molecules; transformants may arise when some molecules are repaired to form circles. Occasional molecules which enter as intact circles may also lead to transformants.
Organization of the genes for protein synthesis elongation factors Tu and G in the cyanobacterium Anacystis nidulans.
Creators: name: Mickel, F S
name: Spremulli, L L
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1986

description: The genes for protein synthesis elongation factors Tu and G were cloned from the cyanobacterium Anacystis nidulans. The locations of these genes were mapped within the cloned DNA fragment by hybridization with Escherichia coli probes. The organization of the cloned fragment and the DNA flanking it in the A. nidulans chromosome was also determined. The elongation factor Tu and G genes are adjacent to one another and in the same 5'-to-3' orientation. In contrast to other gram-negative bacteria, A. nidulans contains only one gene for elongation factor Tu.
Gravitational leptogenesis in teleparallel and symmetric teleparallel gravities
Creators: name: Li, Mingzhe
name: Mou, Yicen
name: Rao, Haomin
name: Zhao, Dehao
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this paper, we consider the possibilities of generating baryon number asymmetry in thermal equilibrium within the frameworks of teleparallel and symmetric teleparallel gravities. Through the derivative couplings of the torsion scalar or the non-metricity scalar to baryons, the baryon number asymmetry is indeed produced in the radiation dominated epoch. For gravitational baryogenesis mechanisms in these two frameworks, the produced baryon-to-entropy ratio is too small to be consistent with observations. But the gravitational leptogenesis models within both frameworks have the possibilities to interpret the observed baryon-antibaryon asymmetry.
description: 7 pages, to be published in Chinese Physics C
Aerobactin utilization by Neisseria gonorrhoeae and cloning of a genomic DNA fragment that complements Escherichia coli fhuB mutations.
Creators: name: Sparling, P F
name: West, S E
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1987

description: Aerobactin, a dihydroxamate siderophore produced by many strains of enteric bacteria, stimulated the growth of Neisseria gonorrhoeae FA19 and F62 in iron-limiting medium. However, gonococci did not produce detectable amounts of aerobactin in the Escherichia coli LG1522 aerobactin bioassay. We probed gonococcal genomic DNA with the cloned E. coli aerobactin biosynthesis (iucABCD), aerobactin receptor (iutA), and hydroxamate utilization (fhuCDB) genes. Hybridization was detected with fhuB sequences but not with the other genes under conditions which will detect 70% or greater homology. Similar results were obtained with 21 additional strains of gonococci by colony filter hybridization. A library of DNA from N. gonorrhoeae FA19 was constructed in the phasmid vector lambda SE4, and a clone was isolated that complemented the fhuB mutation in derivatives of E. coli BU736 and BN3307. These results suggest that fhuB is a conserved gene and may play a fundamental role in iron acquisition by N. gonorrhoeae.
Radiation friction vs ponderomotive effect
Creators: name: Fedotov, A. M.
name: Elkina, N. V.
name: Gelfer, E. G.
name: Narozhny, N. B.
name: Ruhl, H.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Computational Physics (physics.comp-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The concept of ponderomotive potential is upgraded to a regime in which radiation friction becomes dominant. The radiation friction manifests itself in novel features of long-term capturing of the particles released at the focus and impenetrability of the focus from the exterior. We apply time scales separation to the Landau-Lifshitz equation splitting the particle motion into quivering and slow drift of a guiding center. The drift equation is deduced by averaging over fast motion.
description: 4 pages, 3 figures
Characterization of nonattaching mutants of Agrobacterium tumefaciens.
Creators: name: Matthysse, A G
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1987

description: The first step in tumor formation by Agrobacterium tumefaciens is the site-specific binding of the bacteria to plant host cells. Transposon mutants of the bacteria which fail to attach to carrot suspension culture cells were isolated. These mutants showed no significant attachment to carrot cells with either microscopic or viable cell count assays of bacterial binding. The nonattaching mutants were all avirulent. When revertants of the mutants were obtained by enriching for bacteria which do bind to carrot cells, the bacteria were found to have regained the ability to bind to carrot cells and virulence simultaneously. These results suggest that the ability of the bacteria to bind to plant cells is required for virulence. Like the parent strain, all of the nonattaching mutants synthesized cellulose, but unlike the parent strain, they failed to aggregate carrot suspension culture cells. The transposon Tn5, which was used to obtain the mutants, was located on a 12-kilobase EcoRI fragment of the bacterial chromosomal DNA in all of the nonattaching mutants from strain C58. That the mutant phenotype was due to the Tn5 insertion was shown by cloning the Tn5-containing DNA fragment from the mutant bacteria and using it to replace the wild-type fragment in the parent strain by marker exchange. The resulting bacteria had the same mutant phenotype as the original Tn5 mutants; they did not attach to carrot cells, they did not cause the aggregation of carrot cells, and they were avirulent. No difference was seen between the parent strain and the nonattaching mutants in hydrophobicity, motility, flagella, fimbriae, beta-2-glucan content, size of lipopolysaccharide, or ability of the lipopolysaccharide to inhibit bacterial attachment to tissue culture cells. Differences were seen between the parent strain and the nonattaching mutants in the polypeptides removed from the bacteria during the preparation of spheroplasts. Three of the mutants were lacking a polypeptide of about 34 kilodaltons (kDa). One mutant was lacking the 34-kDa polypeptide and another polypeptide of about 38 kDa. The fifth mutant was lacking a polypeptide slightly smaller than the 34-kDa polypeptide missing in the other four mutants. These missing polypeptides all reappeared in the revertants of the mutants. Thus, bacterial binding to plant cells appears to require the presence of these polypeptides.
Export of unprocessed precursor maltose-binding protein to the periplasm of Escherichia coli cells.
Creators: name: Fikes, J D
name: Bassford, P J
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1987

description: The Escherichia coli maltose-binding protein (MBP) R2 signal peptide is a truncated version of the wild-type structure that still facilitates very efficient export of MBP to the periplasm. Among single amino acid substitutions in the R2 signal peptide resulting in an export-defective precursor MBP (pMBP) were two that replaced residues in the consensus Ala-X-Ala sequence (residues -3 to -1) that immediately precedes the cleavage site. It was suggested that the functional hydrophobic core and signal peptidase recognition sequence of this signal peptide substantially overlap and that these two alterations affect both pMBP translocation and processing. In this study, the export of pMBP by the mutants, designated CC15 and CC17, with these two alterations was investigated further. The pMBP of mutant CC17 has an Arg substituted for Leu at the -2 position. It was found that CC17 cells exported only a very small amount of MBP, but that which was exported appeared to be correctly processed. This result was consistent with other studies that have concluded that virtually any amino acid can occupy the -2 position. For mutant CC15, which exhibits a fully Mal+ phenotype, an Asp is substituted for the Ala at the -3 position. CC15 cells were found to export large quantities of unprocessed, soluble pMBP to the periplasm, although such export was achieved in a relatively slow, posttranslational manner. This result was also consistent with other studies that suggested that charged residues are normally excluded from the -3 position of the cleavage site. Using in vitro oligonucleotide-directed mutagenesis, we constructed a new signal sequence mutant in which Asp was substituted for Arg at the -3 position of an otherwise wild-type MBP signal peptide. This alteration had no apparent effect on pMBP translocation across the cytoplasmic membrane, but processing by signal peptidase was inhibited. This pMBP species with its full-length hydrophobic core remained anchored to the membrane, where it could still participate in maltose uptake. The implications of these results for models of protein export are discussed.
Mutational alterations affecting the export competence of a truncated but fully functional maltose-binding protein signal peptide.
Creators: name: Bankaitis, V A
name: Bassford, P J
name: Fikes, J D
name: Ryan, J P
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1987

description: The wild-type maltose-binding protein (MBP) signal peptide is 26 amino acids in length. A mutationally altered MBP signal peptide has been previously described that is missing one of the basic residues from the hydrophilic segment and seven residues from the hydrophobic core; however, it still facilitates MBP secretion to the periplasm at a rate and efficiency comparable to those of the wild-type structure. Thus, this truncated signal peptide (designated the R2 signal peptide) must retain all of the essential features required for proper export function. In this study, alterations were obtained in the R2 signal peptide that resulted in an export-defective MBP. For the first time, signal sequence mutations were obtained that resulted in the synthesis of a totally export-defective MBP. As was previously the case for the wild-type signal peptide, the introduction of either charged residues or helix-breaking proline residues adversely affected export function. Despite these similarities, the position of these alterations within the R2 signal peptide, their relative effects on MBP secretion and processing, and an analysis of the ability of various extragenic prl mutations to suppress the secretion defects provide additional insight into the minimal requirements for a functional MBP signal peptide.
Detecting the ultra low dimensionality of real networks
Creators: name: Almagro, Pedro
name: Boguna, Marian
name: Serrano, M. Angeles
Publisher: name: arXiv
Year: 2021
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Social and Information Networks (cs.SI)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Reducing dimension redundancy to find simplifying patterns in high-dimensional datasets and complex networks has become a major endeavor in many scientific fields. However, detecting the dimensionality of their latent space is challenging but necessary to generate efficient embeddings to be used in a multitude of downstream tasks. Here, we propose a method to infer the dimensionality of networks without the need for any a priori spatial embedding. Due to the ability of hyperbolic geometry to capture the complex connectivity of real networks, we detect ultra low dimensionality far below values reported using other approaches. We applied our method to real networks from different domains and found unexpected regularities, including: tissue-specific biomolecular networks being extremely low dimensional; brain connectomes being close to the three dimensions of their anatomical embedding; and social networks and the Internet requiring slightly higher dimensionality. Beyond paving the way towards an ultra efficient dimensional reduction, our findings help address fundamental issues that hinge on dimensionality, such as universality in critical behavior.
Instrumental Variables Before and LATEr
Creators: name: Kitagawa, Toru
Publisher: name: arXiv
Year: 2014
Subjects: subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences

description: The modern formulation of the instrumental variable methods initiated the valuable interactions between economics and statistics literatures of causal inference and fueled new innovations of the idea. It helped resolving the long-standing confusion that the statisticians used to have on the method, and encouraged the economists to rethink how to make use of instrumental variables in policy analysis. [arXiv:1410.0163]
description: Published in at http://dx.doi.org/10.1214/14-STS494 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Two-component millicharged dark matter and the EDGES 21cm signal
Creators: name: Li, Qiaodan
name: Liu, Zuowei
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal. The heavier dark matter component is long-lived whose decay is primarily responsible for the relic abundance of the lighter dark matter which is millicharged. To evade the constraints from CMB, underground dark matter direct detection, and XQC experiments, the lifetime of the heavier dark matter has to be larger than $0.1\, τ_U$, where $τ_U$ is the age of the universe. Our model provides a viable realization of the millicharged dark matter model to explain the EDGES 21 cm, since the minimal model in which the relic density is generated via thermal freeze-out is ruled out by various constraints.
description: 13 pages, 2 figures
Equivalence and superposition of real and imaginary quasiperiodicities
Creators: name: Cai, Xiaoming
name: Jiang, Shaojian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We take non-Hermitian Aubry-André-Harper models and quasiperiodic Kitaev chains as examples to demonstrate the equivalence and superposition of real and imaginary quasiperiodic potentials (QPs) on inducing localization of single-particle states. We prove this equivalence by analytically computing Lyapunov exponents (or inverse of localization lengths) for systems with purely real and purely imaginary QPs. Moreover, when superposed and with the same frequency, real and imaginary QPs are coherent on inducing the localization, under a way which is determined by the relative phase between them. The localization induced by a coherent superposition can be simulated by the Hermitian model with an effective strength of QP, implying that models are in the same universality class. When their frequencies are different and relatively incommensurate, they are incoherent and their superposition leads to less correlation effects. Numerical results show that the localization happens earlier and there is an intermediate mixed phase lacking of mobility edge.
description: 6 pages, 4 figures
Repair of N-methyl-N'-nitro-N-nitrosoguanidine-induced DNA damage by ABC excinuclease.
Creators: name: Sancar, A
name: Van Houten, B
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 1987

description: Escherichia coli has several overlapping DNA repair pathways which act in concert to eliminate the DNA damage caused by a diverse array of physical and chemical agents. The ABC excinuclease which is encoded by the uvrA, uvrB, and uvrC genes mediates both the incision and excision steps of nucleotide excision repair. Traditionally, this repair pathway has been assumed to be active against DNA adducts that cause major helical distortions. To determine the level of helical deformity required for recognition and repair by ABC excinuclease, we have evaluated the substrate specificity of this enzyme by using DNA damaged by N-methyl-N'-nitro-N-nitrosoguanidine. ABC excinuclease incised methylated DNA in vitro in a dose-dependent manner in a reaction that was ATP dependent and specific for the fully reconstituted enzyme. In vivo studies with various alkylation repair-deficient mutants indicated that the excinuclease participated in the repair of DNA damage induced by N-methyl-N'-nitro-N-nitrosoguanidine.
Low momentum propagators at two loops in gluon mass model
Creators: name: Gracey, J. A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We compute the two loop corrections to the gluon propagator for low momentum in a gluon mass model. This model has recently been proposed as an alternative to the Gribov construction in the way it handles Gribov copies in the gauge fixing. The corrections provide improvements for estimating the point where the gluon propagator freezes in relation to lattice data.
description: 16 latex pages, 1 figure
M5-branes Probing Flux Backgrounds
Creators: name: Bah, Ibrahima
name: Bonetti, Federico
name: Leung, Enoch
name: Weck, Peter
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We analyze the global symmetries and anomalies of 4d $\mathcal{N} = 1$ field theories that arise from a stack of $N$ M5-branes probing a class of flux backgrounds. These backgrounds consist of a resolved $\mathbb{C}^2 / \mathbb{Z}_k$ singularity fibered over a smooth Riemann surface of genus $g \geq 2$, supported by a non-trivial $G_4$-flux configuration labeled by a collection of $2(k-1)$ flux quanta, $\{N_i\}$. For $k=2$, this setup defines a non-trivial superconformal field theory (SCFT) in the IR, which is holographically dual to an explicit $AdS_5$ solution first described by Gauntlett, Martelli, Sparks, and Waldram. The generalization to $k \geq 3$ is hard to tackle directly within holography. Instead, in this paper we lay the groundwork for a systematic analysis of such a generalization by adopting anomaly inflow methods to identify continuous and discrete global symmetries of the 4d field theories. We also compute the 't Hooft anomalies for continuous symmetries at leading order in the limit of large $N$, $N_i$.