SETI science working group report

This report covers the initial activities and deliberations of a continuing working group asked to assist the SETI Program Office at NASA. Seven chapters present the group's consensus on objectives, strategies, and plans for instrumental R&D and for a microwave search for extraterrestrial in intelligence (SETI) projected for the end of this decade. Thirteen appendixes reflect the views of their individual authors. Included are discussions of the 8-million-channel spectrum analyzer architecture and the proof-of-concept device under development; signal detection, recognition, and identification on-line in the presence of noise and radio interference; the 1-10 GHz sky survey and the 1-3 GHz targeted search envisaged; and the mutual interests of SETI and radio astronomy. The report ends with a selective, annotated SETI reading list of pro and contra SETI publications

The Path Integral for 1+1-dimensional QCD

We derive a path integral expression for the transition amplitude in 1+1-dimensional QCD starting from canonically quantized QCD. Gauge fixing after quantization leads to a formulation in terms of gauge invariant but curvilinear variables. Remainders of the curved space are Jacobians, an effective potential, and sign factors just as for the problem of a particle in a box. Based on this result we derive a Faddeev-Popov like expression for the transition amplitude avoiding standard infinities that are caused by integrations over gauge equivalent configurations.Comment: 16 pages, LaTeX, 3 PostScript figures, uses epsf.st

Marginality of bulk-edge correspondence for single-valley Hamiltonians

We study the correspondence between the non-trivial topological properties associated with the individual valleys of gapped bilayer graphene (BLG), as a prototypical multi-valley system, and the gapless modes at its edges and other interfaces. We find that the exact connection between the valley-specific Hall conductivity and the number of gapless edge modes does not hold in general, but is dependent on the boundary conditions, even in the absence of intervalley coupling. This non-universality is attributed to the absence of a well-defined topological invariant within a given valley of BLG; yet, a more general topological invariant may be defined in certain cases, which explains the distinction between the BLG-vacuum and BLG-BLG interfaces.Comment: 7 pages, 4 figure

Local Buckling of Composite Laminated Cylindrical Shells with Oblique Edges under External Pressure: Asymptotic and Finite Element Simulations

The problem of local buckling ofa thin composite laminated cylindrical shell under external pressure is studied. Each layer of the shell is assumed to be isotropic. The special case of the shell being non-circular and/or having no plane edges is considered here. Presupposing that buckling takes place in the neighborhood of some so-called “weakest” generator, the asymptotic Tovstik’s method is appliedfinding the critical pressure and the elgenmodes. As an example, buckling of a three-layered circular thin cylinder with a sloped edge is investigated. Besides the asymptotic approach the finite element simulation is applied to facilitate the estimation of the range to which the results obtained can be applied

Foreword

The aim of this study is to explore the relationship between gender, discourse and technology, and the resulting construction of bodily norms, in a contemporary environment dominated by info- and bio-technologies. The premise from which this study starts is that the ‘intra-action’ between gender, discourse and technology plays a central role in shaping contemporary identities. The study is based on close readings of material from three case studies: cyberpunk fiction, (in)fertility weblogs and the World Health Organisation guidelines on naming of biotechnologies. The distinctive combination of the three case studies provides a unique perspective on the relationship between gender, discourse and technology, showing how it shifts across different contexts, and demonstrating the socio-historical contingency of the bodily norms produced therein. This study is comprised of three empirical texts, one theoretical text and a kappa. The analysis shows how innovative cyberpunk narratives challenge not only human/non-human boundaries, but also genre and gender conventions. The specific format of the blog allows women’s experiences of infertility to be heard and produces hybrid discourses which challenge contemporary authoritative discourses about femininity. The third case study explores the assignment of International Nonproprietary Names to new biotechnologies, and the implications of this on the construction of patients’ bodies. Finally, the theoretical text contributes to existing feminist analyses of technoscience by proposing a new tool called abject/noise for examining disruptions to discursive and bodily coherence. This tool is then tested on a series of documents about the assignment of International Nonproprietary Names to new biotechnologies. Throughout, the importance of ‘situated knowledges’ is emphasised, both in how gender, discourse and technology are understood, but also in the norms produced and the position of the researcher.Syftet med denna studie är att undersöka relationen mellan genus, diskurs och teknik och hur denna relation bidrar till att konstruera vissa typer av kroppsnormer, speciellt som vår samtid infärgas av informationsteknik och bioteknik. Utgångspunkten för denna studie är att ’intra-action’ mellan genus, diskurs och teknik spelar en central roll i utformningen av samtida identiteter. Studien bygger på närläsningar av material från tre fallstudier: cyberpunk-litteratur, in/fertilitetets-bloggar och Världs-hälsoorganisationens riktlinjer för namngivning av bioteknik. Kombinationen av de tre fallstudierna ger ett unikt perspektiv på relationen mellan genus, diskurs och teknik. Den visar hur relationen skiftar mellan olika sammanhang, och hur denna är kulturellt villkorad och därmed tillåter vissa kroppsliga normer att upstå och cirkulera. Denna undersökning består av tre empiriskt grundade texter, en mer teoretisk text och en kappa. Den försten analysen visar hur innovativa cyberpunk berättelser inte bara utmanar föreställningar kring det mänsklig / icke-mänskliga gränser, utan också själva genren i sig och dess kulturella konventionerna kring genus. Det specifika format webbloggen (eller blogg) i den andra fallstudien tillåter kvinnors upplevelser av infertilitet att höras och producerar genreöverlappningar och igen-kännanden som utmanar samtida normativ diskurser om reproduktiv kvinnlighet. Den tredje fallstudien undersöker tilldelningen av ett så kallat Internationellt generiskt namn till nya biotekniska produkter, och konsekvenserna detta får för konstruktionen av patienternas genusifierade kroppar. Slutligen bidrar den teoretiska texten till befintliga feministiska analyser av ’teknovetenskap’ genom att föreslå ett nytt verktyg som kallas ’abject/noise’ för att undersöka störningar i diskursiva och kroppsliga sammanhang. Detta verktyg testats sedan också analytiskt på dokumentar som rör tilldelningen av Internationellt generiskt namn till ny bioteknik. Genom hela avhandlingen läggs tonvikten på ’situerad kunskap’, både gäller hur genus, diskurs och teknik förstås kontextuellt, hur normer blir till och hur forskaren positionerar sig

Shear Modulus of an Elastic Solid under External Pressure as a function of Temperature: The case of Helium

The energy of a dislocation loop in a continuum elastic solid under pressure is considered within the framework of classical mechanics. For a circular loop, this is a function with a maximum at pressures that are well within reach of experimental conditions for solid helium suggesting, in this case, that dislocation loops can be generated by a pressure-assisted thermally activated process. It is also pointed out that pinned dislocations segments can alter the shear response of solid helium, by an amount consistent with current measurements, without any unpinning.Comment: 5 pages, 3 figure

Query processing of spatial objects: Complexity versus Redundancy

The management of complex spatial objects in applications, such as geography and cartography, imposes stringent new requirements on spatial database systems, in particular on efficient query processing. As shown before, the performance of spatial query processing can be improved by decomposing complex spatial objects into simple components. Up to now, only decomposition techniques generating a linear number of very simple components, e.g. triangles or trapezoids, have been considered. In this paper, we will investigate the natural trade-off between the complexity of the components and the redundancy, i.e. the number of components, with respect to its effect on efficient query processing. In particular, we present two new decomposition methods generating a better balance between the complexity and the number of components than previously known techniques. We compare these new decomposition methods to the traditional undecomposed representation as well as to the well-known decomposition into convex polygons with respect to their performance in spatial query processing. This comparison points out that for a wide range of query selectivity the new decomposition techniques clearly outperform both the undecomposed representation and the convex decomposition method. More important than the absolute gain in performance by a factor of up to an order of magnitude is the robust performance of our new decomposition techniques over the whole range of query selectivity