Geometric phases for corotating elliptical vortex patches

We describe a geometric phase that arises when two elliptical vortex patches corotate. Using the Hamiltonian moment model of Melander, Zabusky, and Styczek [J. Fluid Mech. 167, 95–115 (1986)] we consider two corotating uniform elliptical patches evolving according to the second order truncated equations of the model. The phase is computed in the adiabatic setting of a slowly varying Hamiltonian as in the work of Hannay [J. Phys. A 18, 221–230 (1985)] and Berry [Proc. R. Soc. London, Ser. A 392, 45–57 (1984)]. We also discuss the geometry of the symplectic phase space of the model in the context of nonadiabatic phases. The adiabatic phase appears in the orientation angle of each patch—it is similiar in form and is calculated using a multiscale perturbation procedure as in the point vortex configuration of Newton [Physica D 79, 416–423 (1994)] and Shashikanth and Newton [J. Nonlinear Sci. 8, 183–214 (1998)], however, an extra factor due to the internal stucture of the patch is present. The final result depends on the initial orientation of the patches unlike the phases in the works of Hannay and Berry [J. Phys. A 18, 221–230 (1985)]; [Proc. R. Soc. London, Ser. A 392, 45–57 (1984)]. We then show that the adiabatic phase can be interpreted as the holonomy of a connection on the trivial principal fiber bundle pi:T2×S1-->S1, where T2 is identified with the product of the momentum level sets of two Kirchhoff vortex patches and S1 is diffeomorphic to the momentum level set of two point vortex motion. This two point vortex motion is the motion that the patch centroids approach in the adiabatic limit

Building Tremor Journal: Examining the Costs of Open Access Publishing

The Center for Digital Research and Scholarship (CDRS) was established in 2007 by the Columbia University Libraries/ Information Services (CUL/IS) to explore and provision new research support services for the university in all areas of scholarly communication, including online scholarly publishing. (Renfro and Neal, 2012) As the landscape for library publishing has continued to grow, CDRS has found an increasing level of demand for library-based support of publishing initiatives from within the University and beyond. Because of CDRS’ unique position as an organization housed within the existing CUL/IS infrastructure, the Center has access to a great deal of resources and support systems that have enabled it to provide a full suite of services in support of library-based publishing, including the publication of Tremor and Other Hyperkinetic Movements (TOHM) journal (http://www.tremorjournal.org/), a fully open access scientific journal based on the Open Journal Systems (OJS) software. Using CDRS' publication and support of TOHM as a case study, this presentation will examine the costs involved in publishing an open access journal, moving beyond the basic setup and execution of a journal website capable of incorporating a peer-review workflow to look in detail at the specific essential services CDRS provides, including: Software development, hosting, and maintenance: The Center continually works to develop on top of the OJS software to customize the web site to allow for full journal publication workflow, including the build of a plugin to work with third-party vendors. Indexing support: In an effort to uphold the journal’s contribution to the scientific community, CDRS has successfully undertaken application for indexing in PubMed Central (http://www.ncbi.nlm.nih.gov/pmc/), and continues to maintain this relationship. Finance management: Through the Center’s relationship with the library finance office, CDRS manages the journal’s finances, including author fees, waivers, and the incorporation of third-party funding and grants to the journal. Research and Development: A constant aspect of CDRS’ support for open-access publication through TOHM is the task of keeping abreast of new opportunities for enhancing the scholarly content through new software tools and platforms; metadata optimization and SEO tools; and methods for integration with the broader scientific research community. The support of TOHM speaks to the Center’s strategy for securing paths for the open access to scholarly research. Additionally, as exemplified by the Library Publishing Coalition’s (LPC) goal to “refine justification and positioning for library-based publishing activities,” (“LPC Project Deliverables”) it provides a useful mechanism for analysis of the opportunities the greater research library community has in the support of scholarly research publication

Heat capacity uncovers physics of a frustrated spin tube

We report on refined experimental results concerning the low-temperature specific heat of the frustrated spin tube material [(CuCl2tachH)3Cl]Cl2. This substance turns out to be an unusually perfect spin tube system which allows to study the physics of quasi-one dimensional antiferromagnetic structures in rather general terms. An analysis of the specific heat data demonstrates that at low enough temperatures the system exhibits a Tomonaga-Luttinger liquid behavior corresponding to an effective spin-3/2 antiferromagnetic Heisenberg chain with short-range exchange interactions. On the other hand, at somewhat elevated temperatures the composite spin structure of the chain is revealed through a Schottky-type peak in the specific heat located around 2 K. We argue that the dominating contribution to the peak originates from gapped magnon-type excitations related to the internal degrees of freedom of the rung spins.Comment: 4+ pages, 6 figure

Small bowel malignant melanoma presenting as a perforated jejunal diverticulum: a case report and literature review.

Although usually harmless and asymptomatic, jejuno-ileal diverticulae are associated with various non-specific gastrointestinal symptoms, and rarely cause surgical emergencies. This case report describes the presentation and management of a patient with an acute abdomen, whose jejunal diverticulum was perforated. Unexpectedly, histopathological assessment demonstrated malignant melanoma lining the diverticulum. Whether this was primary or metastatic is discussed, together with a synopsis of the literature on small bowel diverticulae

The gravitational S-matrix

We investigate the hypothesized existence of an S-matrix for gravity, and some of its expected general properties. We first discuss basic questions regarding existence of such a matrix, including those of infrared divergences and description of asymptotic states. Distinct scattering behavior occurs in the Born, eikonal, and strong gravity regimes, and we describe aspects of both the partial wave and momentum space amplitudes, and their analytic properties, from these regimes. Classically the strong gravity region would be dominated by formation of black holes, and we assume its unitary quantum dynamics is described by corresponding resonances. Masslessness limits some powerful methods and results that apply to massive theories, though a continuation path implying crossing symmetry plausibly still exists. Physical properties of gravity suggest nonpolynomial amplitudes, although crossing and causality constrain (with modest assumptions) this nonpolynomial behavior, particularly requiring a polynomial bound in complex s at fixed physical momentum transfer. We explore the hypothesis that such behavior corresponds to a nonlocality intrinsic to gravity, but consistent with unitarity, analyticity, crossing, and causality.Comment: 46 pages, 10 figure

Levinson's Theorem for Non-local Interactions in Two Dimensions

In the light of the Sturm-Liouville theorem, the Levinson theorem for the Schr\"{o}dinger equation with both local and non-local cylindrically symmetric potentials is studied. It is proved that the two-dimensional Levinson theorem holds for the case with both local and non-local cylindrically symmetric cutoff potentials, which is not necessarily separable. In addition, the problems related to the positive-energy bound states and the physically redundant state are also discussed in this paper.Comment: Latex 11 pages, no figure, submitted to J. Phys. A Email: [email protected], [email protected]

Emerging Opportunities in Library Services: Planning for the Future of Scholarly Publishing

In 2007, the Columbia University Libraries/Information Services (CUL/IS) established the Center for Digital Research and Scholarship (CDRS) to explore and provision new research support services for the university in all areas of scholarly communication, including online scholarly publishing. One of six organizations comprising the Digital Programs and Technology Services group within CUL/IS, CDRS assists faculty, students, staff, and university affiliates with their scholarly communication and digital research needs through a suite of services: publishing support, digital research repository, conference websites and video recording, research data management, and more. Nine of its 17 full-time employees belong to a production team comprising developers, designers, and project managers from diverse academic and professional backgrounds, only one of whom holds a master’s degree in library science. CDRS seeks publishing partnerships with a variety of on-campus groups and individuals and embraces partnerships with allied organizations such as scholarly presses and societies as well. A proponent of eliminating barriers to the progress of research, CDRS advocates for open access (OA) publishing models. This is exemplified by Tremor and Other Hyperkinetic Movements, the peer-reviewed, faculty-run OA journal now indexed in PubMed, which CDRS publishes. To help offset the OA journal publication costs, Tremor authors pay an article processing fee, although waivers and alternative methods of funding are available. In practice, CDRS’ approach to publishing support is business model–neutral, however,and OA is not a requirement for partnership. The journals program at CDRS has been successful, providing publishing support to 16 journals using the Open Journal Systems or WordPress platforms and interactive tools such as blogs and wikis in subject areas ranging from sciences to the humanities. A strategy for keeping this service sustainable and scalable has been the adoption of a tiered structure based on design and customization needs to control flow. Projects can take anywhere from one week for a barebones installation to over 17 weeks for the Premier service

Collective Excitations of Strongly Interacting Fermi Gases of Atoms in a Harmonic Trap

The zero-temperature properties of a dilute two-component Fermi gas in the BCS-BEC crossover are investigated. On the basis of a generalization of the Hylleraas-Undheim method, we construct rigorous upper bounds to the collective frequencies for the radial and the axial breathing mode of the Fermi gas under harmonic confinement in the framework of the hydrodynamic theory. The bounds are compared to experimental data for trapped vapors of Li6 atoms.Comment: 11 pages, 2 figure

Relativistic Operator Description of Photon Polarization

We present an operator approach to the description of photon polarization, based on Wigner's concept of elementary relativistic systems. The theory of unitary representations of the Poincare group, and of parity, are exploited to construct spinlike operators acting on the polarization states of a photon at each fixed energy momentum. The nontrivial topological features of these representations relevant for massless particles, and the departures from the treatment of massive finite spin representations, are highlighted and addressed.Comment: Revtex 9 page

Geographical distribution of selected and putatively neutral SNPs in Southeast Asian malaria parasites.

Loci targeted by directional selection are expected to show elevated geographical population structure relative to neutral loci, and a flurry of recent papers have used this rationale to search for genome regions involved in adaptation. Studies of functional mutations that are known to be under selection are particularly useful for assessing the utility of this approach. Antimalarial drug treatment regimes vary considerably between countries in Southeast Asia selecting for local adaptation at parasite loci underlying resistance. We compared the population structure revealed by 10 nonsynonymous mutations (nonsynonymous single-nucleotide polymorphisms [nsSNPs]) in four loci that are known to be involved in antimalarial drug resistance, with patterns revealed by 10 synonymous mutations (synonymous single-nucleotide polymorphisms [sSNPs]) in housekeeping genes or genes of unknown function in 755 Plasmodium falciparum infections collected from 13 populations in six Southeast Asian countries. Allele frequencies at known nsSNPs underlying resistance varied markedly between locations (F(ST) = 0.18-0.66), with the highest frequencies on the Thailand-Burma border and the lowest frequencies in neighboring Lao PDR. In contrast, we found weak but significant geographic structure (F(ST) = 0-0.14) for 8 of 10 sSNPs. Importantly, all 10 nsSNPs showed significantly higher F(ST) (P < 8 x 10(-5)) than simulated neutral expectations based on observed F(ST) values in the putatively neutral sSNPs. This result was unaffected by the methods used to estimate allele frequencies or the number of populations used in the simulations. Given that dense single-nucleotide polymorphism (SNP) maps and rapid SNP assay methods are now available for P. falciparum, comparing genetic differentiation across the genome may provide a valuable aid to identifying parasite loci underlying local adaptation to drug treatment regimes or other selective forces. However, the high proportion of polymorphic sites that appear to be under balancing selection (or linked to selected sites) in the P. falciparum genome violates the central assumption that selected sites are rare, which complicates identification of outlier loci, and suggests that caution is needed when using this approach