Symmetry-surfing the moduli space of Kummer K3s.

A maximal subgroup of the Mathieu group M24 arises as the combined holomorphic symplectic automorphism group of all Kummer surfaces whose Kaehler class is induced from the underlying complex torus. As a subgroup of M24, this group is the stabilizer group of an octad in the Golay code. To meaningfully combine the symmetry groups of distinct Kummer surfaces, we introduce the concepts of Niemeier markings and overarching maps between pairs of Kummer surfaces. The latter induce a prescription for symmetry-surfing the moduli space, while the former can be seen as a first step towards constructing a vertex algebra that governs the elliptic genus of K3 in an M24-compatible fashion. We thus argue that a geometric approach from K3 to Mathieu Moonshine may bear fruit.Comment: 20 pages; minor changes; accepted for publication in the Proceedings Volume of String-Math 201

DNA duplex cage structures with icosahedral symmetry

A construction method for duplex cage structures with icosahedral symmetry made out of single-stranded DNA molecules is presented and applied to an icosidodecahedral cage. It is shown via a mixture of analytic and computer techniques that there exist realisations of this graph in terms of two circular DNA molecules. These blueprints for the organisation of a cage structure with a noncrystallographic symmetry may assist in the design of containers made from DNA for applications in nanotechnology

Dynamical implications of Viral Tiling Theory

The Caspar–Klug classification of viruses whose protein shell, called viral capsid, exhibits icosahedral symmetry, has recently been extended to incorporate viruses whose capsid proteins are exclusively organised in pentamers. The approach, named ‘Viral Tiling Theory’, is inspired by the theory of quasicrystals, where aperiodic Penrose tilings enjoy 5-fold and 10-fold local symmetries. This paper analyses the extent to which this classification approach informs dynamical properties of the viral capsids, in particular the pattern of Raman active modes of vibrations, which can be observed experimentally

Infections associated with eating seed sprouts: an international concern.

Recent outbreaks of Salmonella and Escherichia coli O157:H7 infections associated with raw seed sprouts have occurred in several countries. Subjective evaluations indicate that pathogens can exceed 107 per gram of sprouts produced from inoculated seeds during sprout production without adversely affecting appearance. Treating seeds and sprouts with chlorinated water or other disinfectants fails to eliminate the pathogens. A comprehensive approach based on good manufacturing practices and principles of hazard analysis and critical control points can reduce the risk of sprout-associated disease. Until effective measures to prevent sprout-associated illness are identified, persons who wish to reduce their risk of foodborne illness from raw sprouts are advised not to eat them; in particular, persons at high risk for severe complications of infections with Salmonella or E. coli O157:H7, such as the elderly, children, and those with compromised immune systems, should not eat raw sprouts

A Quadrupole/Time-of-Flight Mass Spectrometry Study of Trp-Cage’s Conformation

Trp-cage is a synthetic 20-residue miniprotein that uses tertiary contacts to stabilize its native conformation. NMR, circular dichroism (CD), and UV-resonance Raman spectroscopy were used to probe its energy landscape. In this quadrupole/time-of-flight study, electrospray ionization charge state distribution (CSD) and solution-phase H/D exchange are used to probe Trp-cage’s tertiary structure. The CSDs of Trp-cage and its mutant provide spectra showing a pH-dependent conformation change. Solution-phase H/D exchange in 30% deuterated trifluoroethanol solution of the wild type shows increased protection of one labile hydrogen in the native state. Together, CSDs and solution-phase H/D exchange are demonstrated to constitute a simple but effective means to follow conformation changes in a small tertiary protein

Cascading Failures in Interconnected Power-to-Water Networks

The manageability and resilience of critical infrastructures, such as power and water networks, is challenged by their increasing interdependence and interconnectivity. Power networks often experience cascading failures, i.e. blackouts, that have unprecedented economic and social impact. Al- though knowledge exists about how to control such complex non-linear phenomena within a single power network, little is known about how such failures can spread and coevolve in the water network when failing power components energize the water distribution infrastructure, i.e. pumps and valves. This paper studies such a scenario and specifically the impact of power cascading failures on shortages of water supply. A realistic exemplary of an interconnected power-to-water network is experimentally evaluated using a modular simulation approach. Power and waterflow dynamics are simulated separately by taking into account different maximum powerlines capacities and water demand requirements. Results showcase the strong dependency of urban water sup- ply systems on the reliability of power networks, with severe shortages of water supply being caused by failures originating indistant power lines, especially for heavily loaded power networks

Imidazolium bromide substituted magnesium phthalocyanine polymers: New promising materials for CO2 conversion

The conversion of CO2 with epoxides into the corresponding cyclic carbonates represents a green approach to transform a waste into value-added products. To promote this conversion, a catalyst in needed. This study presents the synthesis of two cross-linked materials composed of magnesium phthalocyanine and imidazolium bromide moieties: MgPc-BIBI-Br and MgPc-SIBI-Br. Magnesium phthalocyanines are cost-effective and versatile catalysts, synthesized in high yield from low-cost precursors and can be easily modified for specific needs. Imidazolium bromide groups play a crucial role as well, acting as a nucleophile source essential to promote the ring-opening process of the epoxide. The materials have been extensively characterized through analytical and spectroscopic techniques and tested as catalysts in the conversion of epichlorohydrin into 4-chloromethyl-1,3-dioxalan-2-one. They both achieved excellent catalytic performance (maximal TON values of 3070 for MgPc-SIBI-Br and 1903 for MgPc-BIBI-Br) and recyclability (both recyclable at least for 4 cycles). The reported results represent an improvement if compared to similar materials already reported in the literature in which the addition of external nucleophilic species (e.g. TBAB, BMIM-Br, etc.) is needed. To the best of our knowledge, this work is the first example in which imidazolium bromide and magnesium phthalocyanine moieties are combined in bifunctional polymeric materials that convert CO2 into cyclic carbonates via heterogeneous catalysis

Free field representations for the affine superalgebra sl(2|1)

Free field representations of the affine superalgebra $A(1,0)^{(1)}$ at level $k$ are needed in the description of the noncritical $N=2$ string. The superalgebra admits two inequivalent choices of simple roots. We give the Wakimoto representations corresponding to each of these and derive the relation between the two at the quantum level.Comment: Latex file, 12 page