Combinatorial Structure of the Deterministic Seriation Method with Multiple Subset Solutions

Seriation methods order a set of descriptions given some criterion (e.g., unimodality or minimum distance between similarity scores). Seriation is thus inherently a problem of finding the optimal solution among a set of permutations of objects. In this short technical note, we review the combinatorial structure of the classical seriation problem, which seeks a single solution out of a set of objects. We then extend those results to the iterative frequency seriation approach introduced by Lipo (1997), which finds optimal subsets of objects which each satisfy the unimodality criterion within each subset. The number of possible solutions across multiple solution subsets is larger than $n!$, which underscores the need to find new algorithms and heuristics to assist in the deterministic frequency seriation problem.Comment: 8 pages, 2 figure

Very Small Strangelets

We study the stability of small strangelets by employing a simple model of strange matter as a gas of non-interacting fermions confined in a bag. We solve the Dirac equation and populate the energy levels of the bag one quark at a time. Our results show that for system parameters such that strange matter is unbound in bulk, there may still exist strangelets with $A<100$ that are stable and/or metastable. The lifetime of these strangelets may be too small to detect in current accelerator experiments, however.Comment: 13 pages, MIT CTP#217

Color-flavor locked strange matter and strangelets at finite temperature

It is possible that a system composed of up, down and strange quarks consists the true ground state of nuclear matter at high densities and low temperatures. This exotic plasma, called strange quark matter (SQM), seems to be even more favorable energetically if quarks are in a superconducting state, the so-called color-flavor locked state. Here are presented calculations made on the basis of the MIT bag model considering the influence of finite temperature on the allowed parameters characterizing the system for stability of bulk SQM (the so-called stability windows) and also for strangelets, small lumps of SQM, both in the color-flavor locking scenario. We compare these results with the unpaired SQM and also briefly discuss some astrophysical implications of them. Also, the issue of strangelet's electric charge is discussed. The effects of dynamical screening, though important for non-paired SQM strangelets, are not relevant when considering pairing among all three flavor and colors of quarks.Comment: 17 pp. 15 figs., to appear in Phys. Rev.

Measuring Cultural Relatedness Using Multiple Seriation Ordering Algorithms

Seriation is a long-standing archaeological method for relative dating that has proven effective in probing regional-scale patterns of inheritance, social networks , and cultural contact in their full spatiotemporal context. The orderings produced by seriation are produced by the continuity of class distributions and uni-modality of class frequencies, properties that are related to social learning and transmission models studied by evolutionary archaeologists. Linking seriation to social learning and transmission enables one to consider ordering principles beyond the classic unimodal curve. Unimodality is a highly visible property that can be used to probe and measure the relationships between assemblages, and it was especially useful when seriation was accomplished with simple algorithms and manual effort. With modern algorithms and computing power, multiple ordering principles can be employed to better understand the spatiotemporal relations between assemblages. Ultimately, the expansion of seriation to additional ordering algorithms allows us an ability to more thoroughly explore underlying models of cultural contact, social networks, and modes of social learning. In this paper, we review our progress to date in extending seriation to multiple ordering algorithms, with examples from Eastern North America and Oceania

Tools for Transparency and Replicability of Simulation in Archaeology

Session: Open methods in archaeology: how to encourage reproducible research as the default practic

Identification of candidate genes affecting chronic subclinical mastitis in Norwegian Red cattle: combining genome‐wide association study, topologically associated domains and pathway enrichment analysis

The aim of this study was to identify genes associated with chronic subclinical mastitis (SCM) in Norwegian Red (NR) cattle. Twelve SCM traits defined based on fixed threshold for test‐day somatic cell count (SCC) were, together with lactation‐average somatic cell score (LSCS) used for association and pathway enrichment analyses. A GWAS was performed on 3795 genotyped NR bulls with 777K SNP data and phenotypic information from 7 300 847 test‐day SCC observations from 3 543 764 cows. At 5% chromosome‐wide significance level 36 unique SNP were detected to be associated with one or more of the traits. These SNPs were analysed for linked genes using genomic positions of topologically associated domains (TAD). For the SCM traits with SCC >50 000 and >100 000 cells/ml on two test‐days in a row and LSCS, the same top significant genes were identified – checkpoint clamp loader component (RAD17) and cyclin B1 (CCNB1). The SCM traits with SCC >250 000, 300 000, 350 000 or 400 000 cells/ml on two test‐days in a row and D400 (number of days before the first case with SCC >400 000 cells/ml) displayed similar top significant genes: acyl‐CoA thioesterase 2 and 4 (ACOT2; ACOT4). For the traits SCM200_3 (SCC >200 000 cells/ml on three test‐days in a row) and SCM150, SCM200 (SCC >150 000; 200 000 cells/ml on two test‐days in a row) a group of chemokine (C–X–C motif) ligand genes and the Fos proto‐oncogene, AP‐1 transcription factor subunit (FOS) gene, were identified. Further functional studies of these identified candidate genes are necessary to clarify their actual role in development of chronic SCM in NR cattle.publishedVersio

Questions of quality: the Danish State Serum Institute, Thorvald Madsen and biological standardisation

The opening of the Danish State Serum Institute (SSI) in Copenhagen on 9 September 1902 was a festive occasion, attended by renowned figures from the wider bacteriological community including the German scientists Paul Ehrlich, Carl Weigert, and Julius Morgenroth, future Nobel prize-winner Svante Arrhenius from Sweden, Ole Malm and Armauer Hansen from Norway, and William Bulloch and German Sims Woodhead from England.1 Established as a national resource for the production of diphtheria antitoxin, the SSI was from its inception concerned to deliver a quality product at a minimum price, and to link pharmaceutical production with research into, and further development of, biological products. In the course of the twentieth century, the institute acquired an international reputation for the quality of its products and its cutting edge research, and, in the 1920s, achieved international authority as the League of Nations Health Commission’s central laboratory for the preservation and distribution of all standard sera and bacterial products.2 The rise of the SSI to international prominence came about through a combination of factors, personal, scientific and political, but above all, perhaps, from its early association with questions of quality in the production of the new generation biological medicines, of which diphtheria antitoxin was the first to emerge

Chemical Evolution of Strongly Magnetized Quark Core in a Newborn Neutron Star

The chemical evolution of nascent quark matter core in a newborn compact neutron star is studied in presence of a strong magnetic field. The effective rate of strange quark production in degenerate quark matter core in presence of strong magnetic fields is obtained. The investigations show that in presence of strong magnetic fields a quark matter core becomes energetically unstable and hence a deconfinement transition to quark matter at the centre of a compact neutron star under such circumstances is not possible. The critical strength of magnetic field at the central core to make the system energetically unstable with respect to dense nuclear matter is found to be $\sim 4.4\times 10^{13}$G. This is the typical strength at which the Landau levels for electrons are populated. The other possible phase transitions at such high density and ultra strong magnetic field environment are discussed.Comment: 18 pages, latex, eight EPS figures not included, available under request, REVTEX forma

Control and femtosecond time-resolved imaging of torsion in a chiral molecule

We study how the combination of long and short laser pulses, can be used to induce torsion in an axially chiral biphenyl derivative (3,5-difluoro-3',5'-dibromo-4'-cyanobiphenyl). A long, with respect to the molecular rotational periods, elliptically polarized laser pulse produces 3D alignment of the molecules, and a linearly polarized short pulse initiates torsion about the stereogenic axis. The torsional motion is monitored in real-time by measuring the dihedral angle using femtosecond time-resolved Coulomb explosion imaging. Within the first 4 picoseconds, torsion occurs with a period of 1.25 picoseconds and an amplitude of 3 degrees in excellent agreement with theoretical calculations. At larger times the quantum states of the molecules describing the torsional motion dephase and an almost isotropic distribution of the dihedral angle is measured. We demonstrate an original application of covariance analysis of two-dimensional ion images to reveal strong correlations between specific ejected ionic fragments from Coulomb explosion. This technique strengthens our interpretation of the experimental data.Comment: 11 pages, 9 figure

Einstein-Weyl structures and Bianchi metrics

We analyse in a systematic way the (non-)compact four dimensional Einstein-Weyl spaces equipped with a Bianchi metric. We show that Einstein-Weyl structures with a Class A Bianchi metric have a conformal scalar curvature of constant sign on the manifold. Moreover, we prove that most of them are conformally Einstein or conformally K\"ahler ; in the non-exact Einstein-Weyl case with a Bianchi metric of the type $VII_0, VIII$ or $IX$, we show that the distance may be taken in a diagonal form and we obtain its explicit 4-parameters expression. This extends our previous analysis, limited to the diagonal, K\"ahler Bianchi $IX$ case.Comment: Latex file, 12 pages, a minor modification, accepted for publication in Class. Quant. Gra