Distribution of spectral widths and preponderance of spin-0 ground states in nuclei

We use a single j-shell model with random two-body interactions to derive closed expressions for the distribution of and the correlations between spectral widths of different spins. This task is facilitated by introducing two-body operators whose squared spectral widths sum up to the squared spectral width of the random Hamiltonian. The spin-0 width is characterized by a relatively large average value and small fluctuations while the width of maximum spin has the largest average and the largest fluctuations. The approximate proportionality between widths and spectral radii explains the preponderance of spin-0 ground states.Comment: 4 pages, 4 eps figure

Instrument for measuring thin-film belt lengths

Instrument consists of base, vernier height gauge, sliding block, and balance-beam assembly with tension weight. Pulley bracket is provided with three pulley mounting holes, 4 inches apart, to accommodate widely different belt lengths. Instrument is accurate to within 0.001 inch and is suitable for commercial production

Inference of the ring current ion composition by means of charge exchange decay

The analysis of the measured ion fluxes during the several day storm recovery period and the assumption that beside hydrogen other ions were present and that the decays were exponential in nature, it was possible to establish three separate lifetimes for the ions. These fitted decay lifetimes are in excellent agreement with the expected charge exchange decay lifetimes for H(+), O(+), and He(+) in the energy and L-value range of the data. This inference technique, thus, establishes the presence of measurable and appreciable quantities of oxygen and helium ions as well as protons in the storm-time ring current. Indications that He(+) may also be present under these same conditions were found

Motions of charged particles in the Magnetosphere under the influence of a time-varying large scale convection electric field

The motions of charged particles under the influence of the geomagnetic and electric fields were quite complex in the region of the inner magnetosphere. The Volland-Stern type large scale convection electric field was used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 measurements. A time dependence in this electric field was introduced based on the variation in Kp for actual magnetic storm conditions. The particle trajectories were computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments were allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format

Learning the Roots of Visual Domain Shift

In this paper we focus on the spatial nature of visual domain shift, attempting to learn where domain adaptation originates in each given image of the source and target set. We borrow concepts and techniques from the CNN visualization literature, and learn domainnes maps able to localize the degree of domain specificity in images. We derive from these maps features related to different domainnes levels, and we show that by considering them as a preprocessing step for a domain adaptation algorithm, the final classification performance is strongly improved. Combined with the whole image representation, these features provide state of the art results on the Office dataset.Comment: Extended Abstrac

On the Complexity of Local Search for Weighted Standard Set Problems

In this paper, we study the complexity of computing locally optimal solutions for weighted versions of standard set problems such as SetCover, SetPacking, and many more. For our investigation, we use the framework of PLS, as defined in Johnson et al., [JPY88]. We show that for most of these problems, computing a locally optimal solution is already PLS-complete for a simple neighborhood of size one. For the local search versions of weighted SetPacking and SetCover, we derive tight bounds for a simple neighborhood of size two. To the best of our knowledge, these are one of the very few PLS results about local search for weighted standard set problems

Nucleosynthesis in Outflows from the Inner Regions of Collapsars

We consider nucleosynthesis in outflows originating from the inner regions of viscous accretion disks formed after the collapse of a rotating massive star. We show that wind-like outflows driven by viscous and neutrino heating can efficiently synthesize Fe-group elements moving at near-relativistic velocities. The mass of 56Ni synthesized and the asymptotic velocities attained in our calculations are in accord with those inferred from observations of SN1998bw and SN2003dh. These steady wind-like outflows are generally proton rich, characterized by only modest entropies, and consequently synthesize essentially nothing heavier than the Fe-group elements. We also discuss bubble-like outflows resulting from rapid energy deposition in localized regions near or in the accretion disk. These intermittent ejecta emerge with low electron fraction and are a promising site for the synthesis of the A=130 r-process peak elements.Comment: 35 pages, 6 figures, added discussion of the influence of nuclear recombination on wind dynamics, to appear in Ap

Precise Mapping of the Replication and Transcription Promoters of Human Parainfluenza Virus Type 3

AbstractThe terminal RNA regions of the genomic and antigenomic RNAs of the paramyxoviruses and rhabdoviruses are known to contain sequences essential for directing RNA replication and transcription. The 3′ terminus (leader region) of the negative-sense, genomic RNA of the rhabdoviruses and paramyxoviruses is known as the leader (Le) promoter and directs synthesis of positive-sense replication and transcription products. The 3′ terminus of the antigenome is termed the trailer complementary (TrC) promoter and directs the synthesis of genomic RNA. By creating mutations in the corresponding regions of an HPIV3 minireplicon in which the viral protein coding sequences were replaced by the luciferase gene, we were able to precisely define the elements of the leader promoter involved in directing positive-strand replication of HPIV3. Nucleotides 1 through 12 (from the terminus) formed a domain critical for replication. The region from nucleotides 13 through 55 was important but not crucial for replication, while G residues at positions 79, 85, and 91 comprised another domain critical for replication. It was also shown that the TrC promoter is similar, though not identical, to the Le promoter. Nucleotides 1 through 12 of the TrC promoter were critical for synthesis of genomic RNA, though specific positions behaved differently from the corresponding positions of the Le promoter. While many of these mutations could not be analyzed for transcription because they completely abrogated genomic RNA synthesis (the template for transcription), we were surprised to find that no mutations in the leader promoter which decreased replication had any significant effect on transcription. However, mutations in the intergenic sequence and gene start signal following the leader and preceding the luciferase message severely decreased transcription, but not replication

Wikitruth Through Wikiorder

How does large-scale social production coordinate individual behavior to produce public goods? Hardin (1968) denied that the creation of public goods absent markets or the State is possible. Benkler (2006), Shirky (2008), Zittrain (2008), and Lessig (2008) recently countered that the needed coordination might emerge though social norms. However, the means to this coordination is under-theorized. Focusing on Wikipedia, we argue that the site’s dispute resolution process is an important force in promoting the public good it produces, i.e., a large number of relatively accurate public encyclopedia articles. We describe the development and shape of Wikipedia’s existing dispute resolution system. Further, we present a statistical analysis based on coding of over 250 arbitration opinions from Wikipedia’s arbitration system. The data show that Wiki-dispute resolution ignores the content of user disputes, instead focusing on user conduct. Based on fairly formalized arbitration findings, we find a high correlation between the conduct found and the remedies ordered. In effect, the system functions not so much to resolve disputes and make peace between conflicting users, but to weed out problematic users while weeding potentially productive users back in to participate. Game theorists have modeled large scale social production as a solution to the herder problem/multi-player prisoner’s dilemma. But we demonstrate that the “weeding in” function reflects dynamics more accurately captured in coordination games instead. In this way, dispute resolution can provide a constitutive function for the community