Multi-objective genetic algorithms for scheduling of radiotherapy treatments for categorised cancer patients

Abstract. This paper presents a multi-objective optimisation model and algorithms for scheduling of radiotherapy treatments for categorised cancer patients. The model is developed considering real life radiotherapy treatment processes at Arden Cancer Centre, in the UK. The scheduling model considers various real life constraints, such as doctors ’ rota, machine availability, patient’s category, waiting time targets, (i.e., the time when a patient should receive the first treatment fraction), and so on. Two objectives are defined: minimisation of the Average patient’s waiting time and minimisation of Average length of breaches of waiting time targets. Three Genetic Algorithms (GAs) are developed and implemented which treat radiotherapy patient categories, namely emergency, palliative and radical patients in different ways: (1) Standard-GA, which considers all patient categories equally, (2) KB-GA, which has an embedded knowledge on the scheduling of emergency patient category and (3) Weighted-GA, which operates with different weights given to the patient categories. The performance of schedules generated by using the three GAs is compared using the statistical analyses. The results show that KB-GA generated the schedules with best performance considering emergency patients and slightly outperforms the other two GAs when all patient categories are considered simultaneously. KB-GA and Standard-GA generated better performance schedules for emergency and palliative patient

121,123Sb NQR as a microscopic probe in Te doped correlated semimetal FeSb2 : emergence of electronic Griffith phase, magnetism and metallic behavior %

$^{121,123}Sb$ nuclear quadrupole resonance (NQR) was applied to $Fe(Sb_{1-x}Te_x)_2$ in the low doping regime (\emph{x = 0, 0.01} and \emph{0.05}) as a microscopic zero field probe to study the evolution of \emph{3d} magnetism and the emergence of metallic behavior. Whereas the NQR spectra itself reflects the degree of local disorder via the width of the individual NQR lines, the spin lattice relaxation rate (SLRR) $1/T_1(T)$ probes the fluctuations at the $Sb$ - site. The fluctuations originate either from conduction electrons or from magnetic moments. In contrast to the semi metal $FeSb_2$ with a clear signature of the charge and spin gap formation in $1/T_1(T)T ( \sim exp/ (\Delta k_BT) )$, the 1\% $Te$ doped system exhibits almost metallic conductivity and a almost filled gap. A weak divergence of the SLRR coefficient $1/T_1(T)T \sim T^{-n} \sim T^{-0.2}$ points towards the presence of electronic correlations towards low temperatures wheras the \textit{5\%} $Te$ doped sample exhibits a much larger divergence in the SLRR coefficient showing $1/T_1(T)T \sim T^{-0.72}$. According to the specific heat divergence a power law with $n\ =\ 2\ m\ =\ 0.56$ is expected for the SLRR. Furthermore $Te$-doped $FeSb_2$ as a disordered paramagnetic metal might be a platform for the electronic Griffith phase scenario. NQR evidences a substantial asymmetric broadening of the $^{121,123}Sb$ NQR spectrum for the \emph{5\%} sample. This has purely electronic origin in agreement with the electronic Griffith phase and stems probably from an enhanced $Sb$-$Te$ bond polarization and electronic density shift towards the $Te$ atom inside $Sb$-$Te$ dumbbell

Enhanced Magnetization from Proton Irradiated Bulk van der Waals Magnet CrSiTe3

Van der Waals (vdWs) crystals have attracted a great deal of scientific attention due to their interesting physical properties and widespread practical applications. Among all, CrSiTe3 (CST) is a ferromagnetic semiconductor with the Curie temperature (TC) of ~32 K. In this letter, we study the magnetic properties of bulk CST single-crystal upon proton irradiation with the fluence of 1x1018 protons/cm2. Most significantly, we observed an enhancement (23%) in the saturation magnetization from 3.9 {\mu}B to 4.8 {\mu}B and is accompanied by an increase in the coercive field (465-542 Oe) upon proton irradiation. Temperature-dependent X-band electron paramagnetic resonance measurements show no additional magnetically active defects/vacancies that are generated upon proton irradiation. The findings from X-ray photoelectron spectroscopy and Raman measurements lead us to believe that modification in the spin-lattice coupling and introduction of disorder could cause enhancement in saturation magnetization. This work demonstrates that proton irradiation is a feasible method in modifying the magnetic properties of vdWs crystals, which represents a significant step forward in designing future spintronic and magneto-electronic applications

Exploring the fragile antiferromagnetic superconducting phase in CeCoIn5

CeCoIn5 is a heavy fermion Type-II superconductor which exhibits clear indications of Pauli-limited superconductivity. A variety of measurements give evidence for a transition at high magnetic fields inside the superconducting state, when the field is applied either parallel to or perpendicular to the c axis. When the field is perpendicular to the c axis, antiferromagnetic order is observed on the high-field side of the transition, with a magnetic wavevector of (q q 0.5), where q = 0.44 reciprocal lattice units. We show that this order remains as the magnetic field is rotated out of the basal plane, but the associated moment eventually disappears above 17 degrees, indicating that the anomalies seen with the field parallel to the c axis are not related to this magnetic order. We discuss the implications of this finding.Comment: Accepted Physical Review Letters, September 2010. 4 pages, 4 figure

Light elements in massive single and binary stars

We highlight the role of the light elements (Li, Be, B) in the evolution of massive single and binary stars, which is largely restricted to a diagnostic value, and foremost so for the element boron. However, we show that the boron surface abundance in massive early type stars contains key information about their foregoing evolution which is not obtainable otherwise. In particular, it allows to constrain internal mixing processes and potential previous mass transfer event for binary stars (even if the companion has disappeared). It may also help solving the mystery of the slowly rotating nitrogen-rich massive main sequence stars.Comment: 10 pages, 8 figures, to appear in proc. IAU-Symp. 268. C. Charbonnel et al., eds

Magnetic excitations in the spinel compound Lix_x[Mn1.96_{1.96}Li0.04_{0.04}]O4_4 (x= 0.2, 0.6, 0.8, 1.0): how a classical system can mimic quantum critical scaling

We present neutron scattering results on the magnetic excitations in the spinel compounds Li$_x$[Mn$_{1.96}$Li$_{0.04}$]O$_4$ (x= 0.2, 0.6, 0.8, 1.0). We show that the dominant excitations below T ~ 70 K are determined by clusters of Mn^4+ ions, and that these excitations mimic the E/T-scaling found in quantum critical systems that also harbor magnetic clusters, such as CeRu$_{0.5}$Fe$_{1.5}$Ge$_2$. We argue that our results for this classical spinel compound show that the unusual response at low temperatures as observed in quantum critical systems is (at least) partially the result of the fragmentation of the magnetic lattice into smaller units. This fragmentation in quantum critical systems is the direct and unavoidable result of intrinsic disorder.Comment: 8 pages, 8 figures; to be submitted to PR

Genetic and phenotypic variability of yield components in wheat (Triticum aestivum L.)

Variability, heritability and components of variance for number of grains per spike and grain weight per spike have been studied in 10 winter wheat varieties from different selection centers (Arsenal, KG-56, Gruza, Mironovskaya 808, Norin 10, Rana Niska, Spartanka, Sterna, Osjecanka, and Szegedi 765). The experiment was performed in randomized block design in three replications on the experimental field of Small Grains Research Centre, Kragujevac in three years. Average estimated values for number of grains per spike and grain weight per spike differed significantly among years and among varieties. The highest average value for number of grains per spike had Szegedi 765 variety ( x = 75.1) and the lowest value was found in Spartanka ( x = 56.0). During investigated period the highest average value for grain weight per spike was determined in Gruza ( Norin 10 ( x = 2.9 g), and the lowest value in x = 2.0 g). The average variation coefficient for number of grains per spike was 17.4%, and for grain weight per spike was 21.4%. The lowest variability for number of grains per spike and grain weight per spike was established in Sterna variety (V = 13.0%; 16.2%, respectively) and the highest in Norin 10 variety (V = 21.6%; 25.1%, respectively). Obtained heritability value in broad sense for number of grains per spike was about 60%, and for grain weight per spike about 40%. Statistical analysis of variance established highly significant differences in mean values for number of grains per spike and grain weight per spike. Phenotypic analysis of variance indicated that ecological factors had higher impact on the expression of number of grains per spike and grain weight per spike than genetic factors