A grasp-knapsack hybrid for a nurse-scheduling problem

This paper is concerned with the application of a GRASP approach to a nurse-scheduling problem in which the objective is to optimise a set of preferences subject to a set of binding constraints. The balance between feasibility and optimality is a key issue. This is addressed by using a knapsack model to ensure that the solutions produced by the construction heuristic are easy to repair. Several construction heuristics and neighbourhoods are compared empirically. The best combination is further enhanced by a diversification strategy and a dynamic evaluation criterion. Tests show that it outperforms previously published approaches and finds optimal solutions quickly and consistently.     

Bounds for indecomposable torsion-free modules

Let M be a finitely generated torsion-free module over a one-dimensional reduced Noetherian ring R with finitely generated normalization. The rank of M is the tuple of vector-space dimensions of M_P over each field R_P (R localized at P), where P ranges over the minimal prime ideals of R. We assume that there exists a bound N_R on the ranks of all indecomposable finitely generated torsion-free R-modules. For such rings, what bounds and ranks occur? Partial answers to this question have been given by a plethora of authors over the past forty years. In this article we provide a final answer by giving a concise list of the ranks of indecomposable modules for R a local ring with no condition on the characteristic. We conclude that if the rank of an indecomposable module M is (r,r,…,r), then r∈{1,2,3,4,6}, even when R is not local.     

Semiclassical <Emphasis Type="Italic">L</Emphasis><Superscript><Emphasis Type="Italic">p</Emphasis></Superscript> Estimates of Quasimodes on Curved Hypersurfaces

Let M be a compact manifold of dimension n, P=P(h) a semiclassical pseudodifferential operator on M, and u=u(h) an L ² normalized family of functions such that P(h)u(h) is O(h) in L ²(M) as h↓0. Let H⊂M be a compact submanifold of M. In a previous article, the second-named author proved estimates on the L ^p norms, p≥2, of u restricted to H, under the assumption that the u are semiclassically localized and under some natural structural assumptions about the principal symbol of P. These estimates are of the form Ch ^−δ(n,k,p) where k=dim H (except for a logarithmic divergence in the case k=n−2, p=2). When H is a hypersurface, i.e., k=n−1, we have δ(n,n−1, 2)=1/4, which is sharp when M is the round n-sphere and H is an equator.     

A comparative investigation of the presence of psychological conditions in high achieving eighth graders from TIMSS 2007 Mathematics

This study is a second analysis of Trends in International Mathematics and Science Study (TIMSS) 2007 background questionnaires to investigate high achieving eighth-grade students’ possession of three elements of Krutetskii’s (The Psychology of Mathematical Abilities in Schoolchildren, The University of Chicago, 1976) psychological conditions. Analyses were made between high achieving eighth graders and their lower achieving counterparts, and between Korean high achievers and their high achieving peers across ten high performing TIMSS participating countries. After reviewing 44,643 students across selected countries, we conclude that a larger percentage of students with mathematical talent demonstrate positive attitudes toward mathematics, value mathematics, and have self-confidence in their ability to learn mathematics than their peers without high achievement in mathematics. However, a larger portion of high achieving Korean students displayed low self-confidence and valued mathematics less than their peers from other high performing countries. Findings from this study will provide insight into some educational issues in science, technology, engineering and mathematics education.     

An agonistic anti-Tie2 antibody suppresses the normal-to-tumor vascular transition in the glioblastoma invasion zone

Tumor progression is intimately associated with the vasculature, as tumor proliferation induces angiogenesis and tumor cells metastasize to distant organs via blood vessels. However, whether tumor invasion is associated with blood vessels remains unknown. As glioblastoma (GBM) is featured by aggressive invasion and vascular abnormalities, we characterized the onset of vascular remodeling in the diffuse tumor infiltrating zone by establishing new spontaneous GBM models with robust invasion capacity. Normal brain vessels underwent a gradual transition to severely impaired tumor vessels at the GBM periphery over several days. Increasing vasodilation from the tumor periphery to the tumor core was also found in human GBM. The levels of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) showed a spatial correlation with the extent of vascular abnormalities spanning the tumor-invading zone. Blockade of VEGFR2 suppressed vascular remodeling at the tumor periphery, confirming the role of VEGF-VEGFR2 signaling in the invasion-associated vascular transition. As angiopoietin-2 (ANGPT2) was expressed in only a portion of the central tumor vessels, we developed a ligand-independent tunica interna endothelial cell kinase 2 (Tie2)-activating antibody that can result in Tie2 phosphorylation in vivo. This agonistic anti-Tie2 antibody effectively normalized the vasculature in both the tumor periphery and tumor center, similar to the effects of VEGFR2 blockade. Mechanistically, this antibody-based Tie2 activation induced VE-PTP-mediated VEGFR2 dephosphorylation in vivo. Thus, our study reveals that the normal-to-tumor vascular transition is spatiotemporally associated with GBM invasion and may be controlled by Tie2 activation via a novel mechanism of action.Subject terms: Tumour angiogenesis, CNS cancer, Targeted therapies     

Evidence of a Uranium-Paddlewheel Node in a Catecholate-Based Metal–Organic Framework

The interactions between uranium and non-innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium-based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self-assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non-innocent linkers. We report the synthesis of the MOF NU-1700 , assembled from U⁴⁺-paddlewheel nodes and catecholate-based linkers. We propose this highly unusual structure, which contains two U⁴⁺ ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X-ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.     

Toward a Holistic Understanding and Models of Nonphotochemical Quenching Effects on In Vivo Fluorometry of Chlorophyll a in Coastal Waters

Nonphotochemical quenching (NPQ) is known to depress in vivo fluorescence (IVF) of chlorophyll a (Chla) in aquatic environments, which makes it difficult to interpret the hour-to-hour variations in Chla measured by in situ fluorometers. We hypothesized that ratios between quenched and unquenched IVF are a function of both NPQ and photochemical quenching. In this study, two diatom model species Thalassiosira pseudonana (CCMP1335) and Thalassiosira weissflogii (CCMP1047) incubated under a sinusoidal light:dark cycle were studied; IVF was recorded continuously, and Chla and photo-physiological variables were measured seven times a day. The maximal decline in Chla-specific IVF (IVF^B) attributable to quenching was 50% under the experimental settings. An NPQ and photochemical quenching-based modeling equation exhibited a better match to the measured IVF^B than equations representing the sole NPQ effect. Photochemical quenching induced by measuring light beam varied substantially during the day, and the part of the model for this process is excitation intensity-dependent (which is differed between models of in situ fluorometers, implying no straightforward method to correct Chla for all instrument models, instrument-specific parameterization is required). The forms of the IVF^B-light relationship are discussed as well. The findings foster a holistic understanding of NPQ effects on in vivo Chla fluorometry.     

Functionalized latexes as substrates for atom transfer radical polymerization

The application of atom transfer radical polymerization (ATRP) to the homopolymerization of 2‐hydroxyethyl acrylate and 2‐(methacryloyloxy) ethyl trimethylammonium chloride at the surface of a crosslinked polystyrene latex functionalized with alkyl bromide groups is reported. Polymerization was carried out using the surface groups of the dialyzed latex as initiators. The resulting hydrophobic core, hydrophilic shell latexes, were analyzed by FTIR, ¹³C‐NMR spectroscopy, and dynamic light scattering.     

Growth and Characterisation of Silicon Crystallites on Laser Structured Glass

Selective growth of silicon crystallites on glass, seeded from silicon saturated metallic solution droplets is demonstrated. These droplets are deposited in micropore arrays which are generated in the glass substrate by ultrashort laser pulses. In this way, an equidistant distribution of crystallites can be achieved by preferred nucleation in the micropores. Additionally, a crystallite selection occurs corresponding to the tip geometry. The material transport is governed by the vapour-liquid-solid (VLS) mechanism. The morphological characterization of micropores and grown crystallites is performed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Focused Ion Beam (FIB) method.