The arithmetic of genus two curves with (4,4)-split Jacobians

In this paper we study genus 2 curves whose Jacobians admit a polarized (4,4)-isogeny to a product of elliptic curves. We consider base fields of characteristic different from 2 and 3, which we do not assume to be algebraically closed. We obtain a full classification of all principally polarized abelian surfaces that can arise from gluing two elliptic curves along their 4-torsion and we derive the relation their absolute invariants satisfy. As an intermediate step, we give a general description of Richelot isogenies between Jacobians of genus 2 curves, where previously only Richelot isogenies with kernels that are pointwise defined over the base field were considered. Our main tool is a Galois theoretic characterization of genus 2 curves admitting multiple Richelot isogenies.Comment: 30 page

Involving users in OPAC interface design: Perspective from a UK study

This is the post-print versoin of the Article. The official published version can be accessed from the link below - Copyright @ 2007 SpringerThe purpose of this study was to determine user suggestions for a typical OPAC (Online Public Library Catalogue) application’s functionality and features. An experiment was undertaken to find out the type of interactions features that users prefer to have in an OPAC. The study revealed that regardless of users’ Information Technology (IT) backgrounds, their functionality expectations of OPACs are the same. However, based on users’ previous experiences with OPACs, their requirements with respect to specific features may change. Users should be involved early in the OPAC development cycle process in order to ensure usable and functional interface

Transfusion audit of blood products using the World Health Organization Basic Information Sheet in Qazvin, Islamic Republic of Iran

We assessed the practicality of using the transfusion Basic Information Sheet (BIS) for data collection, to determine the overall adequacy of physician documentation of blood product transfusion, and to make an audit of the appropriateness of blood product transfusion. The transfusion process and clinical indications for transfusions administered to adult hospitalized patients in 3 tertiary care teaching hospitals in Qazvin were prospectively reviewed. Adequate documentation was achieved in 62.6 of all transfusion episodes, range 41?73, depending on the medical specialty; 15.7 of red blood cells and whole blood requests, 40.8 of platelet requests and 34.1 of fresh frozen plasma requests were inappropriate. BIS-based information along with data collection can be used to provide feedback regarding the effectiveness of and compliance with local and national transfusion guidelines

A fluidic relaxation oscillator for reprogrammable sequential actuation in soft robots

Despite exciting developments in soft robotics, fully autonomous systems remain elusive. Fluidic circuits could enable fully embedded control of soft robots without using electronics. In this work, we introduce a simple and compact soft valve with intentional hysteresis, analogous to an electronic relaxation oscillator. By integrating the valve with a soft actuator, we transform a continuous inflow to cyclic activation. Importantly, we show that our circuits can activate up to five actuators in various sequences and that we can physically reprogram the activation order by varying the (initial) conditions in the fluidic circuit. Moreover, we show the feasibility of our approach under more realistic conditions by building a four-legged robot. Our work paves the way toward fully autonomous soft robots that can interact with their environment to reprogram their behavior, e.g., to trigger targeted drug release inside our body or to change gait to move past obstacles

Central Charge Reduction and Spacetime Statistics in the Fractional Superstring

Fractional superstrings in the tensor-product formulation experience ``internal projections'' which reduce their effective central charges. Simple expressions for the characters of the resulting effective worldsheet theory are found. All states in the effective theory can be consistently assigned definite spacetime statistics. The projection to the effective theory is shown to be described by the action of a dimension-three current in the original tensor-product theory.Comment: 11 pages (LaTeX), CLNS 92/1168, McGill/92-41 (minor typos corrected

The shock compression of microorganism-loaded broths and emulsions: Experiments and simulations

By carefully selecting flyer plate thickness and the geometry of a target capsule for bacterial broths and emulsions, we have successfully subjected the contents of the capsule to simultaneous shock and dynamic compression when subjected to a flyer-plate impact experiment. The capsules were designed to be recovered intact so that post experimental analysis could be done on the contents. ANSYS® AUTODYN hydrocode simulations were carried out to interrogate the deformation of the cover plate and the wave propagation in the fluid. Accordingly, we have shown that microorganisms such as Escherichia coli, Enterococcus faecalis and Zygosaccharomyces bailii are not affected by this type of loading regime. However, by introducing a cavity behind the broth we were able to observe limited kill in the yeast sample. Further, on using this latter technique with emulsions it was shown that greater emulsification of an oil-based emulsion occurred due to the cavitation that was introduced

Analytic curves in algebraic varieties over number fields

We establish algebraicity criteria for formal germs of curves in algebraic varieties over number fields and apply them to derive a rationality criterion for formal germs of functions, which extends the classical rationality theorems of Borel-Dwork and P\'olya-Bertrandias valid over the projective line to arbitrary algebraic curves over a number field. The formulation and the proof of these criteria involve some basic notions in Arakelov geometry, combined with complex and rigid analytic geometry (notably, potential theory over complex and $p$-adic curves). We also discuss geometric analogues, pertaining to the algebraic geometry of projective surfaces, of these arithmetic criteria.Comment: 55 pages. To appear in "Algebra, Arithmetic, and Geometry: In Honor of Y.i. Manin", Y. Tschinkel & Yu. Manin editors, Birkh\"auser, 200

Equation formulation considerations for efficient numerical modeling of semiconductor phenomena

This paper highlights the importance of equation formulation and associated programming efficiency with respect to modeling of semiconductor phenomena via numerical methods.Two numerical modeling efforts are developed in this paper for one-space dimension device modeling. It is shown on a per iteration basis that the ratio of the computational effort between the two methods is a factor of sixteen. The reduction in the computational effort between the two methods was realized by reformulating the mathematical equations and by reconsidering the effect of programming efficiency. A by-product of the reformulation was a factor of two to three improvement in the convergence rate of the nonlinear iteration. With all considerations, the overall improvement in the solution times for one-space dimension device numerical modeling was determined to be a factor of 30-50.When considering equation formulation alone, the per iteration improvement is a factor of 1[middle dot]43. Coupled with the two to three convergence rate improvement the overall improvement due to equation formulation was approximately 3[middle dot]67.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22001/1/0000414.pd