Calabi-Yau Three-folds: Poincare Polynomials and Fractals

We study the Poincare polynomials of all known Calabi-Yau three-folds as constrained polynomials of Littlewood type, thus generalising the well-known investigation into the distribution of the Euler characteristic and Hodge numbers. We find interesting fractal behaviour in the roots of these polynomials in relation to the existence of isometries, distribution versus typicality, and mirror symmetry.Comment: 14 pages, 6 figures, invited contribution to the Max Kreuzer Memorial Volume, based on MPhys project of the first author under the supervision of the second, at the University of Oxfor

SUMOylation determines the voltage required to activate cardiac IKs channels.

IKs channels open in response to depolarization of the membrane voltage during the cardiac action potential, passing potassium ions outward to repolarize ventricular myocytes and end each beat. Here, we show that the voltage required to activate IKs channels depends on their covalent modification by small ubiquitin-like modifier (SUMO) proteins. IKs channels are comprised of four KCNQ1 pore-forming subunits, two KCNE1 accessory subunits, and up to four SUMOs, one on Lys424 of each KCNQ1 subunit. Each SUMO shifts the half-maximal activation voltage (V1/2) of IKs ∼ +8 mV, producing a maximal +34-mV shift in neonatal mouse cardiac myocytes or Chinese hamster ovary (CHO) cells expressing the mouse or human subunits. Unexpectedly, channels formed without KCNE1 carry at most two SUMOs despite having four available KCNQ1-Lys424 sites. SUMOylation of KCNQ1 is KCNE1 dependent and determines the native attributes of cardiac IKs in vivo

Identifying the Effect of Data Breach Publicity on Information Security Awareness using Hierarchical Regression

© 2021 IEEE. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/The technological evolution has formed new challenges for organizations to safeguard their information as digital assets. Information Security Awareness (ISA) is the cognitive state where individuals comprehend information security, threats, and the capability to develop preventive strategies. Prior studies discovered that human mistakes or misbehavior is the most vulnerable link in information security due to insufficient security awareness. There were massive data breaches reported throughout the years globally. Literature shows that individuals will develop their evaluations of risks and sense of security awareness when receiving security risk information such as data breach incidents. These indications motivated us to examine the effect of an unexplored factor, that is, data breach publicity (DBR) on ISA. The purpose of this research is to discover if DBR significantly improves a model's ability to predict ISA and its magnitude in influencing ISA. A 3-stage hierarchical linear regression approach was used to build up the model with prior known influential factors to predict ISA. To the extent of our knowledge, there is no study reported to date regarding the implication of DBR on ISA. Our main findings reveal that DBR significantly explains 6.7% of ISA and achieves the highest coefficient comparing with prior known factors. Our research contributes to a novel discovery of a new factor that significantly influences ISA and its magnitude in increasing ISA. This discovery implies the need to incorporate the knowledge of data breach incidents into ISA-related educative programs or strategies to increase ISA.Peer reviewe

Optimization of microstructured hollow fiber design for membrane distillation applications using CFD modeling

This study explores the potential of microstructured hollow fiber designs to enhance process performance in a direct contact membrane distillation (DCMD) system. Hollow fibers with 10 different geometries (wavy- and gear-shaped cross sections) were evaluated. A series of three-dimensional computational fluid dynamic (CFD) simulations were carried out to investigate their capability in terms of depolarizing the buildup of liquid boundary layers, thus improving water productivity. Analyses of heat and mass transfer as well as the flow-field distribution in respective MD modules were obtained. It was found that the enhancement of the heat-transfer coefficients, hf, was up to 4.5-fold for a module with a wavy fiber design 07 and an approximate 5.5-fold hp increase for a gear-shaped fiber design. The average temperature polarization coefficient and mass flux Nm of the gear-shaped fiber module showed an improvement of 57% and 66%, respectively, over the original straight fiber design, followed by the wavy designs 07 and 08. The enhanced module performance was attributed to the improved hydrodynamics through the flow channels of various fiber geometries, which was confirmed by the visualization of flow-field and temperature profiles in CFD. Investigations of the fiber-length effect showed that the gear-shaped fiber modules exhibited the highest flux enhancement of 57–65% with the same length, compared to the modules with original straight and wavy fibers. In addition, the gear-shaped fiber module is very sensitive to feed velocity changes. Therefore, employing a smart microstructured design on the membrane surface would bring in a significant improvement under adverse flow conditions. Moreover, the computed water production and hydraulic energy consumption (HEC) among the modules with various fiber geometries were compared. With 1.9-fold surface area increase per unit volume, the gear-shaped fiber configuration had the highest water production but the lowest HEC, followed by wavy designs 07 and 08

Analysis of heat and mass transfer by CFD for performance enhancement in direct contact membrane distillation

A comprehensive analysis on the dominant effects for heat and mass transfer in the direct contact membrane distillation (DCMD) process has been performed with the aid of computational fluid dynamics (CFD) simulations for hollow fiber modules without and with annular baffles attached to the shell wall. Potential enhancement strategies under different circumstances have been investigated. Numerical simulations were carried out to investigate the effect of the MD intrinsic mass-transfer coefficient of the membrane (C) on the performance enhancement for both non-baffled and baffled modules. It was found that the temperature polarization coefficient (TPC) decreases significantly with increasing C value regardless of the existence of baffles, signifying a loss of overall driving force. However, the higher C compensated for this and the mass flux showed an increasing trend. A membrane with a lower C value was found to be less vulnerable to the TP effect. In this case, the introduction of turbulence aids such as baffles did not show substantial effect to improve system performance. In contrast, introducing baffles into the module can greatly enhance the mass flux and the TPC for a membrane with a high C value, where the main heat-transfer resistance is determined by the fluid side boundary layers. The effect of operating temperature on heat and mass transfer in the MD process was also studied with a membrane of a lower C value (2.0 × 10−7 kg m−2 s−1 Pa−1). Although the TPC generally decreased with increasing operating temperatures, the mass flux Nm increased significantly when operating temperature increased. A baffled module showed a more significant improvement than a non-baffle module at a higher temperature. Moreover, it was confirmed that higher operating temperatures are preferable for a substantial improvement in the heat/mass transfer as well as MD thermal efficiency, even with a relatively small transmembrane temperature difference of 10 K.Accepted versio