A centerline symmetry and double-line transformation based algorithm for large-scale multi-objective optimization

The search space of large-scale multi-objective optimization problems (LSMOPs) is huge because of the hundreds or even thousands of decision variables involved. It is very challenging to design efficient algorithms for LSMOPs to search the whole space effectively and balance the convergence and diversity at the same time. In this paper, to tackle this challenge, we develop a new algorithm based on a weighted optimization framework with two effective strategies. The weighted optimization framework transforms an LSMOP into multiple small-scale multi-objective optimization problems based on a problem transformation mechanism to reduce the dimensionality of the search space effectively. To further improve its effectiveness, we firstly propose a centerline symmetry strategy to select reference solutions to transform the LSMOPs. It takes not only some non-dominated solutions but also their centerline symmetric points as the reference solutions, which can enhance the population diversity to avoid the algorithm falling into local minima. Then, a new double-line transformation function is designed to expand the search range of the transformed problem to further improve the convergence and diversity. With the two strategies, more widely distributed potential search areas are provided and the optimal solutions can be found easier. To demonstrate the effectiveness of our proposed algorithm, numerical experiments on widely used benchmarks are executed and the statistical results show that our proposed algorithm is more competitive and performs better than the other state-of-the-art algorithms for solving LSMOPs

Description of larva of Euphaea superba Kimmins, 1936 (Odonata: Zygoptera: Euphaeidae) from China

Wu, Xiangjuan, Liu, Zhen, Chen, Yu, Wang, Beixin (2019): Description of larva of Euphaea superba Kimmins, 1936 (Odonata: Zygoptera: Euphaeidae) from China. Zootaxa 4545 (4): 585-592, DOI: https://doi.org/10.11646/zootaxa.4545.4.

Euphaea superba Kimmins 1936

Larvae of Euphaea superba Specimens examined. 2 larvae: 1♂, 13.V.2016, Xiaxuezhaicun (29 ° 31’58’’N, 119 ° 52’1’’E), Jinhua City, Zhejiang Province, China, Lei Zhang leg; 1♀, 26.V.2017, Shuijinkeng (29 ° 15’47’’N, 120 ° 58’23’’E), Taizhou City, Zhejiang Province, China, Lei Zhang leg. All specimens are deposited in the Insect Collection, Nanjing Agricultural University. Description (Figs. 2–25). Male. Body medium-sized and flat; in dorsal view black covered (in alcohol) with dense black setae (Fig. 2), in ventral view light brown mottled with yellow spots (Fig. 3). Head: Roughly pentagonal (Fig. 2), greyish brown mottled with yellow stripes, densely covered with short rod-like setae intermingled with small simple setae dorsally. Compound eyes black, somewhat round. Ocelli white and elliptic. Mid-portion of antefrons with inverted T-shaped stripe. Antenna 7-segmented (Fig. 4), filiform; 1 st segment short and thick, black; 2 nd segment slender, about two times as long as 1 st one, black except yellow apex; 3 rd –6 th segments each with base and apex yellow and other portion black; 7 th segment, light brown, thin with apex acute. Clypeus yellowish brown, stripe-like, glabrous. Genae large (Fig. 5), somewhat bottle-shaped, anterior 1/3 much narrower than posterior 2/3; of seven sharp spines on anterolateral margin of both genae, forth to sixth spines larger than other ones in left gena (Fig. 6), and fifth to seventh spines larger than other ones in right gena (Fig. 7); each gena has rows of short setae along lateral margin contiguous with compound eye extending to posterolateral area of rod-like setae. Labrum (Fig. 10) wider than long, with anterior margin concave, dorsal surface densely covered with short rod-like setae intermingled with simple setae laterally, except glabrous triangular area at middle. Mandibles unsymmetrical, somewhat conical, with following formula: L 1’+1234 0 a(m 1,2,3,4)b / R 1’+1234 y aa’. Left mandible with five incisiors and two molars (Fig. 11, 12); incisiors sharp, incisior 1’ small and blunt, close to incisior 1, 4>3>2>1>1’; molar a and b sharp, a > b; four denticles between molar a and b sharp. Right mandible with five incisiors and two molars (Fig. 13, 14); incisiors sharp, incisior 1’ small and blunt, close to incisior 1, 4>3>1>2>1’; molar a and a’ sharp, a > a’; additional tooth y with sharp apex. Basolateral spines of each mandible progressively larger. Maxillae (Fig. 16, 17) long, each with galeolacinea (Fig. 15) having four strong uncinate teeth, and basal half of apical tooth with three blade-like teeth, inner margins of galeolacinea setose; maxillary palpi digitate, slightly curved inwards, distal half setose. Labium flattened. Prementum (Fig. 18) longer than wide, median lobe semicircular, median cleft shallow, lateral margins each with row of compactly arranged uncinate spines. Lateral lobe black, each cylindrical, apex with one inner truncate tooth and two outer uncinate teeth (Fig. 19), with median uncinate tooth largest and incisive; movable hook strong, about twice length of abovementioned largest tooth, with apex sharp. Thorax: Prothorax narrower than head (Fig. 2), wider than long. Pronotum roughly saddle-shaped, dark brown to black, covered with rod-shaped setae intermingled with small simple hairs, except white diamond-shaped depression at middle, and brown cambered glabrous stripe issued from anterolateral angle and extended to diamond-shaped depression, then backward to posterolateral angle on each side. Synthorax as wide as head, setose as pronotum except anteromesal triangular area and adjacent two oblique stripes. Mesonotum rectangular. Metanotum triangular. Prosternum with pale distinct spot mesally. Prosternum, meso- and meta-sternum depressed in the middle (Fig. 3), each with paired depressions laterally. Wing sheaths divergent, dark brown, with sparse short rod-like setae, hind wing sheaths each reaching posterior margin of 7 th abdominal segment. Of three paired legs, forelegs shortest and hind legs longest. Legs overall brown, with tarsi and claws yellowish brown; femora broad, robust, covered with dense setae intermingled with short rod-like setae, posterior margin with sparse long rod-like setae interspersed long bristle-like setae in dorsal view; tibiae slender, setose, interminglesd with sparse long rodlike setae and long bristle-like setae on each outer margin; tarsi with bristle-like setae on dorsal surfaces and dense spines on ventral surface, tarsal formula 3-3-3; claws glabrous. Abdomen: Abdominal segments dark brown, each with posterior margin light brown; S3–S8 each with a pair of crescent yellow spots dorsally (Fig. 2); sterna of S2–S7 each with yellow longitudinal line and pair of roughly round yellow spots (Fig. 3); seven pairs of lateral gills (Fig. 20) from S2–S8, each gill progressively slenderer from base to end, with dense tiny curving setae on ventral margin. Vestigial male primary genitalia (Fig. 21) inconspicuous, present on S9, paired, stripe-shaped, with simple setae on ventral margin. Caudal gills saccular, dark brown, distal portion with a short pale tail, median gill (Fig. 24–25) with dense simple setae, near tail with sparse rod-like setae, distal half with dense long bristle-like setae on ventral margin at middle; lateral gills resemble median gill but smaller. Measurements (mm). Body length (including caudal gills) 23.5; head width 4.8; antenna length 2.7; labrum width 1.3; left mandible length 1.6, right mandible length 1.6; prementum length 4.2, prementum width 3.2; hindwing sheath length 6.7; median gill 6.7. Female. Female larva resembles male larva, except larger body size, 4 th –7 th spines larger than other ones in left gena (Fig. 8), and 5 th –6 th spines larger than other ones in right gena (Fig. 9). Moreover, female primary genitalia (Fig. 22–23) extend to posterior margin of S10. Primary lateral valvulae in ventral view narrow at base, slightly broadened laterad to basal 1/3, then narrowed progressively to apex, setose on inner margins, apex rounded ventrally; in lateral view, upper margin somewhat sinuate, lower margin arch-shaped, apex nipple-shaped. Primary ventral valvulae slender in ventral view, tapering from base to apex, in lateral view slightly curved upwards. Primary inner valvulae similar to primary ventral valvulae both in ventral and lateral views, but slenderer. Measurements (mm). Body length (including caudal gills) 24.1; head width 5.0; antenna length 2.9; labrum width 1.4; left mandible length 1.7, right mandible length 1.7; prementum length 4.3, prementum width 3.3; hindwing sheath length 6.9; median gill 6.9. Female primary genitalia length 1.3. Habitat. Larvae were collected from the underside of raised rocks in a hill stream with rapid flow. The stream is about six metres wide and with about 60% canopy of riparian vegetation. Diagnosis. The larva of E. superba could be diagnosed from E. decorata, E. formosa, E. ochracea and E. yayeyamana by the combination of following characters (according to the descriptions and illustrations of various authors): (1) movable hook about 1.6 times as long as median cleft of labium (7.5 times in E. decorata, 3 times in both E. formosa and E. ochracea, and 2.6 times in E. yayeyamana); (2) the median caudal gill with the base about 10 times as long as its tail (2.5 times in E. decorata, 5 times in E. ochracea, and 3 times in E. yayeyamana, unknown in E. formosa); (3) 2–4 large and sharp spines on outer side of gena (2–3 in E. decorata, 3–5 in E. formosa and E. ochracea, and 3 in E. yayeyamana); (4) female with primary genitalia extend to posterior margin of S10 (extend beyond distal margin of S 10 in E. decorata, E. formosa, E. ochracea and E. yayeyamana).Published as part of Wu, Xiangjuan, Liu, Zhen, Chen, Yu & Wang, Beixin, 2019, Description of larva of Euphaea superba Kimmins, 1936 (Odonata: Zygoptera: Euphaeidae) from China, pp. 585-592 in Zootaxa 4545 (4) on pages 587-590, DOI: 10.11646/zootaxa.4545.4.9, http://zenodo.org/record/261836

Longitudinal trajectories of depressive symptoms: the role of multimorbidity, mobility and subjective memory

Abstract Background The high prevalence of depression among older people in China places a heavy burden on the health system. Multimorbidity, mobility limitation and subjective memory impairment are found to be risk indicators for depression. However, most studies on this topic focused on depression at a single point in time, ignoring the dynamic changes in depressive symptoms and the relationship between the trajectories and these three conditions. Therefore, we aimed to identify distinct trajectories of depressive symptoms in older people and investigate their associations with multimorbidity, mobility limitation and subjective memory impairment. Methods Data was drawn from China Health and Retirement Longitudinal Study conducted during 2011–2018. A total of 5196 participants who completed 4 visits, conducted every 2–3 years were included in this study. Group-based trajectory modeling was conducted to identify distinct trajectories of depressive symptoms z-scores. Multinomial logistic regression was used to investigate the relationships. Results Four distinct trajectories of depressive symptoms z-scores were identified, labeled as persistently low symptoms (68.69%, n = 3569), increasing symptoms (12.14%, n = 631), decreasing symptoms (14.05%, n = 730) and persistently high symptoms (5.12%, n = 266). Participants with multimorbidity had unfavorable trajectories of depressive symptoms compared with those without multimorbidity, with adjusted odds ratios (95% CIs) of 1.40 (1.15, 1.70), 1.59 (1.33, 1.90) and 2.19 (1.65, 2.90) for the increasing symptoms, decreasing symptoms and persistently high symptoms, respectively. We also observed a similar trend among participants with mobility limitations. Compared with participants who had poor subjective memory, participants with excellent/very good/good subjective memory had a lower risk of developing unfavorable trajectories of depressive symptoms. The adjusted odds ratios (95% CIs) of the increasing symptoms, decreasing symptoms and persistently high symptoms were 0.54 (0.40, 0.72), 0.50 (0.38, 0.65) and 0.48 (0.31, 0.73), respectively. Conclusions Multimorbidity, mobility limitation and subjective memory impairment were found to be potential risk factors for unfavorable depression trajectories

Carbon Dioxide Oil Repulsion in the Sandstone Reservoirs of Lunnan Oilfield, Tarim Basin

The Lunnan oilfield, nestled within the Tarim Basin, represents a prototypical extra-low-permeability sandstone reservoir, distinguished by high-quality crude oil characterised by a low viscosity, density, and gel content. The effective exploitation of such reservoirs hinges on the implementation of carbon dioxide (CO2) flooding techniques. This study, focusing on the sandstone reservoirs of Lunnan, delves into the mechanisms of CO2-assisted oil displacement under diverse operational parameters: injection pressures, CO2 concentration levels, and variations in crude oil properties. It integrates analyses on the high-pressure, high-temperature behaviour of CO2, the dynamics of CO2 injection and expansion, prolonged core flood characteristics, and the governing principles of minimum miscible pressure transitions. The findings reveal a nuanced interplay between variables: CO2’s density and viscosity initially surge with escalating injection pressures before stabilising, whereas they experience a gradual decline with increasing temperature. Enhanced CO2 injection correlates with a heightened expansion coefficient, yet the density increment of degassed crude oil remains marginal. Notably, CO2 viscosity undergoes a substantial reduction under stratigraphic pressures. The sequential application of water alternating gas (WAG) followed by continuous CO2 flooding attains oil recovery efficiency surpassing 90%, emphasising the superiority of uninterrupted CO2 injection over processes lacking profiling. The presence of non-miscible hydrocarbon gases in segmented plug drives impedes the oil displacement efficiency, underscoring the importance of CO2 purity in the displacement medium. Furthermore, a marked trend emerges in crude oil recovery rates as the replacement pressure escalates, exhibiting an initial rapid enhancement succeeded by a gradual rise. Collectively, these insights offer a robust theoretical foundation endorsing the deployment of CO2 flooding strategies for enhancing oil recovery from sandstone reservoirs, thereby contributing valuable data to the advancement of enhanced oil recovery (EOR) technologies in challenging, low-permeability environments

Detoxification mechanisms of electroactive microorganisms under toxicity stress : a review

Remediation of environmental toxic pollutants has attracted extensive attention in recent years. Microbial bioremediation has been an important technology for removing toxic pollutants. However, microbial activity is also susceptible to toxicity stress in the process of intracellular detoxification, which significantly reduces microbial activity. Electroactive microorganisms (EAMs) can detoxify toxic pollutants extracellularly to a certain extent, which is related to their unique extracellular electron transfer (EET) function. In this review, the extracellular and intracellular aspects of the EAMs' detoxification mechanisms are explored separately. Additionally, various strategies for enhancing the effect of extracellular detoxification are discussed. Finally, future research directions are proposed based on the bottlenecks encountered in the current studies. This review can contribute to the development of toxic pollutants remediation technologies based on EAMs, and provide theoretical and technical support for future practical engineering applications