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Tournament selection is a widely used method for parent selection in multi- and many-objective evolutionary algorithms (MOEAs). The tournament size determines the strength of selection pressure based on each algorithm’s internal criterion; larger sizes increase the likelihood of selecting highly ranked solutions, while smaller sizes promote diversity in parent selection. Despite its importance, many MOEAs adopt a fixed tournament size of two without justification, potentially limiting performance across different phases of the search. This study investigates the effects of both static and dynamic tournament sizing strategies on optimization behavior. In the static setting, several fixed values are tested; in the dynamic setting, two scheduling strategies are employed: one that gradually increases the tournament size (ITS) and one that decreases it (DTS) as the search progresses. Experimental results on DTLZ and WFG benchmark problems with three, five, and nine objectives reveal that static tournament sizes of more than two tend to show higher optimization performance than the typical size of two, although the effect varies by base algorithm. ITS generally outperforms static sizing, especially for AGE-MOEA and AGE-MOEA-II, where its benefits become more pronounced as the number of objectives increases. These findings highlight the importance of tournament sizing as a key design factor in enhancing the performance of MOEAs.

In the real world, multiobjective optimization problems require the efficient acquisition of diverse solutions. Various multiobjective evolutionary algorithms (MOEAs) have been developed to address these problems. Typically, MOEAs use the same scoring criteria for both survival and mating selection, despite their different roles. Survival selection should ensure convergence and diversity, whereas mating selection should focus on selecting individuals with higher convergence for crossover. In this article, an efficient selection algorithm is proposed that integrates data envelopment analysis (DEA), Pareto front modeling, and a reference crossover mechanism. In survival selection, algorithms are used to ensure high convergence and diversity. In a previous study, DEA was employed to select individuals with higher convergence in mating selection. This approach balances convergence and diversity. In addition, Pareto front modeling addresses the convexity assumption issue in DEA. In this study, by selecting constraint solutions obtained through DEA as crossover targets, the algorithm makes crossover with superior solutions possible, enhancing optimization speed and diversity. The algorithm is particularly effective for benchmark functions that benefit from neighborhood crossover. In comparisons using the hypervolume metric on the WFG and DTLZ benchmark functions, the proposed algorithm outperformed NSGA-II, NSGA-III, AGE-MOEA-II, DEA-GA, MOEA/D, and other previous algorithms. The results of a Wilcoxon rank-sum test also showed that the proposed algorithm is statistically superior.

The detection and simulation of a type Ia supernova with an early, red flash suggests that it formed through detonation of the helium shell of a white dwarf, rather than by collision of the ejecta with a companion star or by merging with another white dwarf. A different kind of supernova Type Ia supernovae have rather uniform and normalizable light curves, making them suitable for cosmology, yet there remains uncertainty over what paths lead to the explosion. Several years ago a claim was made that a flash seen soon after the explosion was evidence of the shock wave hitting a normal companion star, although most other evidence so far suggests that the explosions arise from the merger of two white dwarfs. Ji-an Jiang and collaborators report observations of a red flash half a day after a type Ia explosion. Their observations lead them to the conclusion that the flash came from the detonation of a thin helium shell surrounding the exploding star. The authors conclude that their finding supports the existence of the previously proposed helium-ignition pathway. Type Ia supernovae arise from the thermonuclear explosion of white-dwarf stars that have cores of carbon and oxygen 1 , 2 . The uniformity of their light curves makes these supernovae powerful cosmological distance indicators 3 , 4 , but there have long been debates about exactly how their explosion is triggered and what kind of companion stars are involved 2 , 5 , 6 . For example, the recent detection of the early ultraviolet pulse of a peculiar, subluminous type Ia supernova has been claimed as evidence for an interaction between a red-giant or a main-sequence companion and ejecta from a white-dwarf explosion 7 , 8 . Here we report observations of a prominent but red optical flash that appears about half a day after the explosion of a type Ia supernova. This supernova shows hybrid features of different supernova subclasses, namely a light curve that is typical of normal-brightness supernovae, but with strong titanium absorption, which is commonly seen in the spectra of subluminous ones. We argue that this early flash does not occur through previously suggested mechanisms such as the companion–ejecta interaction 8 , 9 , 10 . Instead, our simulations show that it could occur through detonation of a thin helium shell either on a near-Chandrasekhar-mass white dwarf, or on a sub-Chandrasekhar-mass white dwarf merging with a less-massive white dwarf. Our finding provides evidence that one branch of previously proposed explosion models—the helium-ignition branch—does exist in nature, and that such a model may account for the explosions of white dwarfs in a mass range wider than previously supposed 11 , 12 , 13 , 14 .

This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine M = 0.315 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 .

We have obtained optical integral field spectroscopy of the explosion sites of more than 25 nearby type-IIP/IIL/Ib/Ic supernovae using UH88/SNIFS, and additionally Gemini/GMOS IFU. This technique enables us to obtain both spatial and spectral information of the immediate environment of the supernovae. Using strong line method we measured the metallicity of the star cluster present at the explosion site, presumably the coeval parent stellar population of the supernova progenitor, and comparison with simple stellar population models gives age estimate of the cluster. With this method we were able to put constraints on the metallicity and age of the progenitor star. The age, i.e. lifetime, of the progenitor corresponds to the initial mass of the star. By far this is the most direct measurement of supernova progenitor metallicity and, if the cluster-progenitor association is confirmed, provides reliable determination of the initial mass of supernova progenitor stars.

This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg² area along the celestial equator. This data release is comprised of all transient sources brighter than r ≃ 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine ΩM  = 0.315 ± 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7σ.

In a series of our three previous papers, we presented several constructions of positive and negative 3D gadgets in origami extrusions which create with two simple outgoing pleats a top face parallel to the ambient paper and two side faces sharing a ridge, where a 3D gadget is said to be positive (resp. negative) if the top face of the resulting gadget seen from the front side lies above (resp. below) the ambient paper. For any possible set of angle parameters, we obtained an infinite number of positive 3D gadgets in our second paper, while we obtained a unique negative 3D gadget by our third construction in our third paper. In this paper we present a geometric (ruler and compass) construction of our third negative 3D gadgets, while the construction presented in our third paper was a numerical one using a rather complicated formula. Also, we prove that there exists a unique positive 3D gadget corresponding to each of our third negative ones. Thus we obtain a canonical pair of a positive and a negative 3D gadget. The proof is based on a geometric redefinition of the critical angles which we introduced in constructing our positive 3D gadgets. This redefinition also enables us to give a simplified proof of the existence theorem of our positive 3D gadgets in our second paper. As an application, we can construct a positive and a negative extrusion from a common crease pattern by using the canonical counterparts, as long as there arise no interferences.

In our previous two papers, we studied (positive) 3D gadgets in origami extrusions which create a top face parallel to the ambient paper and two side faces sharing a ridge with two simple outgoing pleats. Then a natural problem comes up whether it is possible to construct a `negative' 3D gadget from any positive one having the same net without changing the outgoing pleats, that is, to sink the top and two side faces of any positive 3D gadget to the reverse side without changing the outgoing pleats. Of course, simply sinking the faces causes a tear of the paper, and thus we have to modify the crease pattern. There are two known constructions of negative 3D gadgets before ours, but they do not solve this problem because their outgoing pleats are different from positive ones. In the present paper we give an affirmative solution to the above problem. For this purpose, we present three constructions of negative 3D gadgets with a supporting triangle on the back side, which are based on our previous ones of positive 3D gadgets. The first two are an extension of those presented in our previous paper, and the third is new. We prove that our first and third constructions solve the problem. Our solutions enable us to deal with positive and negative 3D gadgets on the same basis, so that we can construct from an origami extrusion constructed with 3D gadgets its negative using the same pleats if there are no interferences among the 3D gadgets. We also treat repetition/division of negative 3D gadgets under certain conditions, which reduces their interferences with others.

The aim of this study was to investigate the efficacy of pre-and posttreatment 99mTc-ethyl cysteinate dimer (99mTc-ECD) single photon emission computed tomography (SPECT) for predicting the ischemic outcome of embolic middle cerebral artery occlusion after treatment with local intraarterial thrombolysis. The authors examined 28 patients with a moderately ischemic area (ratio of affected regional activity to cerebellar activity (A/C ratio) of 0.4 to 0.7) determined using pretreatment SPECT, and with complete recanalization within 6 hours. Posttreatment dynamic and static SPECT studies were performed immediately after thrombolysis. The extent of the affected area outlined on pretreatment SPECT was used for the posttreatment SPECT images, and A/C ratios were calculated. The relative retention ratio of 99mTc-ECD in the affected area was also analyzed using posttreatment dynamic SPECT. Fourteen patients either without infarction or with small subcortical and basal ganglial infarction, 11 patients with medium or large cortical infarction, and 3 patients with hemorrhage were identified by follow-up computed tomography. Ischemic outcome correlated with the relative retention ratio of 99mTc-ECD more closely than either the pre-or posttreatment A/C ratios. In particular, a threshold value for the development of hemorrhage was distinct only in the relative retention ratio of 99mTc-ECD. Pretreatment 99mTc-ECD SPECT did not always predict the occurrence of hemorrhagic transformation, whereas dynamic 99mTc-ECD SPECT performed immediately after thrombolysis allowed clear identification of patients at risk for hemorrhagic transformation.

The aim of this study was to investigate the prognostic utility of post-treatment technetium-99m ethyl cysteinate dimer (99mTc-ECD) single-photon emission tomography (SPET) for predicting ischemic tissue outcome in cases involving embolic middle cerebral artery occlusion treated with local intra-arterial thrombolysis. We examined twenty-five patients with a moderately ischemic area determined using pretreatment technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) SPET, and with complete recanalization within 6 h. Post-treatment 99mTc-ECD SPET studies, consisting of scanning for 0.5-6.5 min (early scan) and 15-21 min (delayed scan) after tracer injection, were performed immediately after thrombolysis. The extent of the affected area outlined on pretreatment 99mTc-HMPAO SPET was used for the post-treatment early and delayed 99mTc-ECD SPET images, and the AR/CE ratio (ratio of affected regional activity to cerebellar activity) was calculated. The washout index of 99mTc-ECD in the affected area was also calculated by dividing the difference between the AR/CE ratio in the early and delayed images by the AR/CE ratio in the early image. Twelve patients without infarction or with small subcortical/basal ganglial infarction, ten with medium or large cortical infarction, and three with hemorrhage were identified by follow-up computed tomography. Although the AR/CE ratio in post-treatment early 99mTc-ECD SPET images was significantly higher in the hemorrhagic group than in the cortical infarction group, this value did not differentiate the reversible ischemia group from either the cortical infarction or the hemorrhagic group. The AR/CE ratio in post-treatment delayed 99mTc-ECD SPET images statistically differentiated the reversible ischemia group from both the cortical infarction and the hemorrhagic group. However, the difference between the cortical infarction and hemorrhagic groups was not statistically significant. The washout index of 99mTc-ECD statistically differentiated all three groups. This study demonstrated that a combination of early and delayed 99mTc-ECD SPET imaging performed immediately after thrombolysis predicts ischemic tissue outcome.