Periods of Double EPW-sextics

We study the indeterminacy locus of the period map for double EPW-sextics. We recall that double EPW-sextics are parametrized by lagrangian subspaces of the third wedge-product of a 6-dimensional complex vector-space. The indeterminacy locus is contained in the set of lagrangians containing a decomposable vector. The projectivization of the 3-dimensional support of such a decomposable vector contains a degeneracy subscheme which is either all of the plane or a sextic curve. We show that the period map is regular on any lagrangian A such that for all decomposables in A the corresponding degeneracy subscheme is a GIT-semistable sextic curve whose closure (in the semistable locus) does not contain a triple conic.Comment: We added a proof that the the period map of double EPW-sextics with isolated singularities is an open embedding into the complement of four explicit arithmetic divisors in the period space. Gave precise references to results of "Moduli of double EPW-sextics" (latest arXiv version) which will appear in Memoirs of the AM

Moduli of sheaves and the Chow group of K3 surfaces

Let X be a projective complex K3 surface. Beauville and Voisin singled out a 0-cycle c_X on X of degree 1: it is represented by any point lying on a rational curve in X. Huybrechts proved that the second Chern class of a rigid simple vector-bundle on X is a multiple of the Beauville-Voisin class c_X if certain hypotheses hold and he conjectured that the additional hypotheses are unnecessary. We believe that the following generalization of Huybrechts' conjecture holds. Let M and N be moduli spaces of stable pure sheaves on X (with fixed cohomological Chern characters) and suppose that they have the same dimension: then the set whose elements are second Chern classes of sheaves parametrized by the closure of M (in the corresponding moduli spaces of semistable sheaves) is equal to the set whose elements are second Chern classes of sheaves parametrized by the closure of N after a translation by a suitable multiple of c_X (so that degrees match). We will prove that the above statement holds under some additional assumptions.Comment: Deleted a footnote and replaced it by a sentence in the main body of the pape

Scaling Analysis and Application: Phase Diagram of Magnetic Nanorings and Elliptical Nanoparticles

The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with an assumption of {\em incomplete} self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane and out-of-plane ferromagnetism and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Three-dimensional phase diagrams are obtained for cylindrical nanorings, depending on their height, outer and inner radius. The triple points in these phase diagrams are shown to be in linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram are identified where the double vortex is a stable ground state.Comment: 9 pages, 7 figures; added references, and discussion, as suggested by referee

Supersymmetric Yang-Mills Theory On A Four-Manifold

By exploiting standard facts about $N=1$ and $N=2$ supersymmetric Yang-Mills theory, the Donaldson invariants of four-manifolds that admit a Kahler metric can be computed. The results are in agreement with available mathematical computations, and provide a powerful check on the standard claims about supersymmetric Yang-Mills theory.Comment: 55 page

Modelling and analyzing adaptive self-assembling strategies with Maude

Building adaptive systems with predictable emergent behavior is a challenging task and it is becoming a critical need. The research community has accepted the challenge by introducing approaches of various nature: from software architectures, to programming paradigms, to analysis techniques. We recently proposed a conceptual framework for adaptation centered around the role of control data. In this paper we show that it can be naturally realized in a reflective logical language like Maude by using the Reflective Russian Dolls model. Moreover, we exploit this model to specify and analyse a prominent example of adaptive system: robot swarms equipped with obstacle-avoidance self-assembly strategies. The analysis exploits the statistical model checker PVesta

Measurement of the total cross section for e^+e^-→hadrons at √s=10.52 GeV

Using the CLEO detector at the Cornell Electron Storage Ring, we have made a measurement of R≡σ(e^+e^-→hadrons)/σ(e^+e^-→μ^+μ^-)=3.56±0.01±0.07 at √s=10.52 GeV. This implies a value for the strong coupling constant of α_s(10.52 GeV)=0.20±0.01±0.06, or α_s(MZ)=0.13±0.005±0.03

Curve classes on irreducible holomorphic symplectic varieties

We prove that the integral Hodge conjecture holds for 1-cycles on irreducible holomorphic symplectic varieties of K3 type and of Generalized Kummer type. As an application, we give a new proof of the integral Hodge conjecture for cubic fourfolds.Comment: 15 page

Employers’ Perceptions of Information Technology Competency Requirements for Management Accounting Graduates

Management accountants work in a computerized workplace with information technology (IT) for producing financial ledgers and for reporting. Thus, the role of the management accountant has shifted from capturing and recording transactions to analyzing business issues. The research question is: what IT knowledge and skills do employers require of management accounting graduates? An exploratory field research approach was used; chief financial officers and their subordinates at some of New Zealand's largest firms were consulted. These respondents were consistent in their requirements. They emphasized intermediate proficiency with some Microsoft tools (Excel, Word, PowerPoint, and Outlook) and sufficient familiarity with the structure and navigation of an enterprise resource planning system to process transactions such as accounts receivable. Of those requirements, Excel for analysis was the most important. Our contributions update and augment the literature by clarifying the perceptions of employers regarding the IT competencies required of management accounting graduates

ERP systems and management accounting: New understandings through “nudging” in qualitative research

Purpose: This paper aims to show how our understanding of the effects of enterprise resource planning (ERP) systems on management accounting are influenced through “nudging” by researchers in their preamble before interviews begin. Design/methodology/approach: There were two groups of comparable respondents. Each group received a different preamble to the same questions. The differences in group responses were analyzed. Findings: When the impact of ERP implementation on the physical, transactional and information flows within the firm were nudged, the responses focused on how the chart of accounts had to be expanded to account for the additional data introduced by transaction processing. When the IT and ERP system knowledge and skills were nudged, the responses tended to emphasize analyses or the use of new information through the use of drill down functionality. This research provides new insights and contributions to understanding how nudging affects or directs respondent assessments of the impact of ERP systems on management accounting. Research limitations/implications: The research is limited by the relatively small samples and by the fact that these were different research projects. Practical implications: Nudging has an obvious impact on research that should not be ignored. Social implications: Unintentional nudging should be considered with all research projects. Originality/value: This paper makes explicit that nudging occurs in research whether intentional or unintentional

The Unyvero P55 ‘sample-in, answer-out’ pneumonia assay: A performance evaluation

Background: O’Neill’s recent Review on Antimicrobial Resistance expressed the view that by 2020 high-income countries should make it mandatory to support antimicrobial prescribing with rapid diagnostic evidence whenever possible. Methods: Routine microbiology diagnosis of 95 respiratory specimens from patients with severe infection were compared with those generated by the Unyvero P55 test, which detects 20 pathogens and 19 antimicrobial resistance markers. Supplementary molecular testing for antimicrobial resistance genes, comprehensive culture methodology and 16S rRNA sequencing were performed. Results: Unyvero P55 produced 85 valid results, 67% of which were concordant with those from the routine laboratory. Unyvero P55 identified more potential pathogens per specimen than routine culture (1.34 vs. 0.47 per specimen). Independent verification using 16S rRNA sequencing and culture (n = 10) corroborated 58% of additional detections compared to routine microbiology. Overall the average sensitivity for organism detection by Unyvero P55 was 88.8% and specificity was 94.9%. While Unyvero P55 detected more antimicrobial resistance markers than routine culture, some instances of phenotypic resistance were missed. Conclusions: The Unyvero P55 is a rapid pathogen detection test for lower respiratory specimens, which identifies a larger number of pathogens than routine microbiology. The clinical significance of these additional organisms is yet to be determined. Further studies are required to determine the effect of the test in practise on antimicrobial prescribing and patient outcomes