Submodular memetic approximation for multiobjective parallel test paper generation

Parallel test paper generation is a biobjective distributed resource optimization problem, which aims to generate multiple similarly optimal test papers automatically according to multiple user-specified assessment criteria. Generating high-quality parallel test papers is challenging due to its NP-hardness in both of the collective objective functions. In this paper, we propose a submodular memetic approximation algorithm for solving this problem. The proposed algorithm is an adaptive memetic algorithm (MA), which exploits the submodular property of the collective objective functions to design greedy-based approximation algorithms for enhancing steps of the multiobjective MA. Synergizing the intensification of submodular local search mechanism with the diversification of the population-based submodular crossover operator, our algorithm can jointly optimize the total quality maximization objective and the fairness quality maximization objective. Our MA can achieve provable near-optimal solutions in a huge search space of large datasets in efficient polynomial runtime. Performance results on various datasets have shown that our algorithm has drastically outperformed the current techniques in terms of paper quality and runtime efficiency

Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films

Spin reorientation has been observed in CoFe2O4 thin single crystalline films epitaxially grown on (100) MgO substrate upon varying the film thickness. The critical thickness for such a spin-reorientation transition was estimated to be 300 nm. The reorientation is driven by a structural transition in the film from a tetragonal to cubic symmetry. At low thickness, the in-plane tensile stress induces a tetragonal distortion of the lattice that generates a perpendicular anisotropy, large enough to overcome the shape anisotropy and to stabilize the magnetization easy axis out of plane. However, in thicker films, the lattice relaxation toward the cubic structure of the bulk allows the shape anisotropy to force the magnetization to be in plane aligned

Hepatic Steatosis After Neoadjuvant Chemotherapy for Pancreatic Cancer: Incidence and Implications for Outcomes After Pancreatoduodenectomy

This article is made available for unrestricted research re-use and secondary analysis in any form or be any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemicBackground This study aimed to determine the incidence of new onset hepatic steatosis after neoadjuvant chemotherapy for pancreatic cancer and its impact on outcomes after pancreatoduodenectomy. Methods Retrospective review identified patients who received neoadjuvant chemotherapy for pancreatic adenocarcinoma and underwent pancreatoduodenectomy from 2013 to 2018. Preoperative computed tomography scans were evaluated for the development of hepatic steatosis after neoadjuvant chemotherapy. Hypoattenuation included liver attenuation greater than or equal to 10 Hounsfield units less than tissue density of spleen on noncontrast computed tomography and greater than or equal to 20 Hounsfield units less on contrast-enhanced computed tomography. Results One hundred forty-nine patients received neoadjuvant chemotherapy for a median of 5 cycles (interquartile range (IQR), 4–6). FOLFIRINOX was the regimen in 78% of patients. Hepatic steatosis developed in 36 (24%) patients. The median time from neoadjuvant chemotherapy completion to pancreatoduodenectomy was 40 days (IQR, 29–51). Preoperative biliary stenting was performed in 126 (86%) patients. Neoadjuvant radiotherapy was delivered to 23 (15%) patients. Female gender, obesity, and prolonged exposure to chemotherapy were identified as risk factors for chemotherapy-associated hepatic steatosis. Compared with control patients without neoadjuvant chemotherapy-associated hepatic steatosis, patients developing steatosis had similar rates of postoperative pancreatic fistula (8% (control) vs. 4%, p = 0.3), delayed gastric emptying (8% vs. 14%, p = 0.4), and major morbidity (11% vs. 15%, p = 0.6). Ninety-day mortality was similar between groups (8% vs. 2%, p = 0.08). Conclusion Hepatic steatosis developed in 24% of patients who received neoadjuvant chemotherapy but was not associated with increased morbidity or mortality after pancreatoduodenectomy

Analysis and contribution of stress anisotropy in epitaxial hard ferrite thin films

The stress anisotropy in epitaxial hard ferrites thin films (BaFe12O19, CoFe2O4) has been investigated using two methods. (a) The thickness dependence of torque curves and magnetic hysteresis loops. (b) The comparison between magnetic and magneto-optic Kerr hysteresis loops. Both analyses confirm the domination of stress in CoFe2O4 whereas in BaFe12O19 films the stress is too weak to compete with magnetocrystalline anisotropy

Vortex structure in d-density wave scenario of pseudogap

We investigate the vortex structure assuming the d-density wave scenario of the pseudogap. We discuss the profiles of the order parameters in the vicinity of the vortex, effective vortex charge and the local density of states. We find a pronounced modification of these quantities when compared to a purely superconducting case. Results have been obtained for a clean system as well as in the presence of a nonmagnetic impurity. We show that the competition between superconductivity and the density wave may explain some experimental data recently obtained for high-temperature superconductors. In particular, we show that the d-density wave scenario explains the asymmetry of the gap observed in the vicinity of the vortex core.Comment: 8 pages, 10 figure

Low-Cost, Accessible Fabrication Methods for Microfluidics Research in Low-Resource Settings

Microfluidics are expected to revolutionize the healthcare industry especially in developing countries since it would bring portable, easy-to-use, self-contained diagnostic devices to places with limited access to healthcare. To date, however, microfluidics has not yet been able to live up to these expectations. One non-negligible factor can be attributed to inaccessible prototyping methods for researchers in low-resource settings who are unable to afford expensive equipment and/or obtain critical reagents and, therefore, unable to engage and contribute to microfluidics research. In this paper, we present methods to create microfluidic devices that reduce initial costs from hundreds of thousands of dollars to about $6000 by using readily accessible consumables and inexpensive equipment. By including the scientific community most embedded and aware of the requirements of healthcare in developing countries, microfluidics will be able to increase its reach in the research community and be better informed to provide relevant solutions to global healthcare challenges

Morphology of the archaellar motor and associated cytoplasmic cone in Thermococcus kodakaraensis

Archaeal swimming motility is driven by archaella: rotary motors attached to long extracellular filaments. The structure of these motors, and particularly how they are anchored in the absence of a peptidoglycan cell wall, is unknown. Here, we use electron cryotomography to visualize the archaellar basal body in vivo in Thermococcus kodakaraensis KOD1. Compared to the homologous bacterial type IV pilus (T4P), we observe structural similarities as well as several unique features. While the position of the cytoplasmic ATPase appears conserved, it is not braced by linkages that extend upward through the cell envelope as in the T4P, but rather by cytoplasmic components that attach it to a large conical frustum up to 500 nm in diameter at its base. In addition to anchoring the lophotrichous bundle of archaella, the conical frustum associates with chemosensory arrays and ribosome‐excluding material and may function as a polar organizing center for the coccoid cells

On the dispersion of solid particles in a liquid agitated by a bubble swarm

This article deals with the dispersion of solid particles in a liquid agitated by a homogeneous swarm of bubbles. The scale of interest lies between the plant scale (of the order of the tank) and the microscale (less than the bubble diameter). The strategy consists in simulating both the twophase flow of deforming bubbles and the motion of solid particles. The evolution of the spatial distribution of particles together with the encounter and entrainment phenomena is studied as a function of the void fraction and the relative size and mass of particles. The influence of the shape of the bubble and of the model of forces that govern the motion of particles is also considered

Magnetic Order in YBa2_2Cu3_3O6+x_{6+x} Superconductors

Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa$_2$Cu$_3$O$_{6+x}$ superconductors. Most of the measurements were made on a high quality crystal of YBa$_2$Cu$_3$O$_{6.6}$. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudogap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at high temperatures that seems to stem from an impurity with a moment that is in the $a$-$b$ plane, but disordered on the crystal lattice. A second ordering occurs near the pseudogap temperature that has a shorter correlation length than the high temperature phase and a moment direction that is at least partly along the c-axis of the crystal. Its moment direction, temperature dependence, and Bragg intensities suggest that it may stem from orbital ordering of the $d$-density wave (DDW) type. An additional intensity increase occurs below the superconducting transition. The magnetic intensity in these phases does not change noticeably in a 7 Tesla magnetic field aligned approximately along the c-axis. Searches for magnetic order in YBa$_2$Cu$_3$O$_{7}$ show no signal while a small magnetic intensity is found in YBa$_2$Cu$_3$O$_{6.45}$ that is consistent with c-axis directed magnetic order. The results are contrasted with other recent neutron measurements.Comment: 11 pages with 10 figure