Perception of motion salience shapes the emergence of collective motions.

Despite the profound implications of self-organization in animal groups for collective behaviors, understanding the fundamental principles and applying them to swarm robotics remains incomplete. Here we propose a heuristic measure of perception of motion salience (MS) to quantify relative motion changes of neighbors from first-person view. Leveraging three large bird-flocking datasets, we explore how this perception of MS relates to the structure of leader-follower (LF) relations, and further perform an individual-level correlation analysis between past perception of MS and future change rate of velocity consensus. We observe prevalence of the positive correlations in real flocks, which demonstrates that individuals will accelerate the convergence of velocity with neighbors who have higher MS. This empirical finding motivates us to introduce the concept of adaptive MS-based (AMS) interaction in swarm model. Finally, we implement AMS in a swarm of ~102 miniature robots. Swarm experiments show the significant advantage of AMS in enhancing self-organization of the swarm for smooth evacuations from confined environments.

Emergent Chirality and Hyperuniformity in an Active Mixture with Nonreciprocal Interactions.

We investigate collective dynamics in a binary mixture of programmable robots in experiments and simulations. While robots of the same species align their motion direction, interaction between species is distinctly nonreciprocal: species A aligns with B and species B antialigns with A. This nonreciprocal interaction gives rise to the emergence of collective chiral motion that can be stabilized by limiting the robot angular speed to be below a threshold. Within the chiral phase, increasing the robot density or extending the range of local repulsive interactions can drive the system through an absorbing-active transition. At the transition point, the robots exhibit a remarkable capacity for self-organization, forming disordered hyperuniform states.

Characterizing Pairwise U-Turn Behavior in Fish: A Data-Driven Analysis.

We applied the time-series clustering method to analyze the trajectory data of rummy-nose tetra (Hemigrammus rhodostomus), with a particular focus on their spontaneous paired turning behavior. Firstly, an automated U-turn maneuver identification method was proposed to extract turning behaviors from the open trajectory data of two fish swimming in an annular tank. We revealed two distinct ways of pairwise U-turn swimming, named dominated turn and non-dominated turn. Upon comparison, the dominated turn is smoother and more efficient, with a fixed leader-follower relationship, i.e., the leader dominates the turning process. Because these two distinct ways corresponded to different patterns of turning feature parameters over time, we incorporated the Toeplitz inverse covariance-based clustering (TICC) method to gain deeper insights into this process. Pairwise turning behavior was decomposed into some elemental state compositions. Specifically, we found that the main influencing factor for a spontaneous U-turn is collision avoidance with the wall. In dominated turn, when inter-individual distances were appropriate, fish adjusted their positions and movement directions to achieve turning. Conversely, in closely spaced non-dominated turn, various factors such as changes in distance, velocity, and movement direction resulted in more complex behaviors. The purpose of our study is to integrate common location-based analysis methods with time-series clustering methods to analyze biological behavioral data. The study provides valuable insights into the U-turn behavior, motion characteristics, and decision factors of rummy-nose tetra during pairwise swimming. Additionally, the study extends the analysis of fish interaction features through the application of time-series clustering methods, offering a fresh perspective for the analysis of biological collective data.

A Minimalist Self-Localization Approach for Swarm Robots Based on Active Beacon in Indoor Environments.

When performing indoor tasks, miniature swarm robots are suffered from their small size, poor on-board computing power, and electromagnetic shielding of buildings, which means that some traditional localization methods, such as global positioning system (GPS), simultaneous localization and mapping (SLAM), and ultra-wideband (UWB), cannot be employed. In this paper, a minimalist indoor self-localization approach for swarm robots is proposed based on active optical beacons. A robotic navigator is introduced into a swarm of robots to provide locally localization services by actively projecting a customized optical beacon on the indoor ceiling, which contains the origin and the reference direction of localization coordinates. The swarm robots observe the optical beacon on the ceiling via a bottom-up-view monocular camera, and extract the beacon information on-board to localize their positions and headings. The uniqueness of this strategy is that it uses the flat, smooth, and well-reflective ceiling in the indoor environment as a ubiquitous plane for displaying the optical beacon; meanwhile, the bottom-up view of swarm robots is not easily blocked. Real robotic experiments are conducted to validate and analyze the localization performance of the proposed minimalist self-localization approach. The results show that our approach is feasible and effective, and can meet the needs of swarm robots to coordinate their motion. Specifically, for the stationary robots, the average position error and heading error are 2.41 cm and 1.44°; when the robots are moving, the average position error and heading error are less than 2.40 cm and 2.66°.

Exploring the criticality hypothesis using programmable swarm robots with Vicsek-like interactions.

A widely mentioned but not experimentally confirmed view (known as the 'criticality hypothesis') argues that biological swarm systems gain optimal responsiveness to perturbations and information processing capabilities by operating near the critical state where an ordered-to-disordered state transition occurs. However, various factors can induce the ordered-disordered transition, and the explicit relationship between these factors and the criticality is still unclear. Here, we present an experimental validation for the criticality hypothesis by employing real programmable swarm-robotic systems (up to 50 robots) governed by Vicsek-like interactions, subject to time-varying stimulus-response and hazard avoidance. We find that (i) not all ordered-disordered motion transitions correspond to the functional advantages for groups; (ii) collective response of groups is maximized near the critical state induced by alignment weight or scale rather than noise and other non-alignment factors; and (iii) those non-alignment factors act to highlight the functional advantages of alignment-induced criticality. These results suggest that the adjustability of velocity or directional coupling between individuals plays an essential role in the acquisition of maximizing collective response by criticality. Our results contribute to understanding the adjustment strategies of animal interactions from a perspective of criticality and provide insights into the design and control of swarm robotics.

Efficacy and safety of preoperative immunotherapy alone followed by surgery in the treatment of advanced gastric cancer with MSI-H/dMMR or EBV-positive.

BACKGROUND: At present, there is no consensus on whether preoperative immunotherapy (PIT) without chemotherapy followed by surgery could benefit patients with advanced gastric cancer (AGC). Here, we report a six-case series study to describe the safety and efficacy of PIT plus gastrectomy in patients with AGC. METHODS: This study involved six patients with AGC who received PIT and surgery at our center between January 2019 and July 2021. Demographic characteristics, preoperative gastroscope biopsy pathology, surgical tissue pathology, radicalness of tumor resection, surgical safety, and recovery parameters were reported. RESULTS: Six patients, including four patients with Epstein-Barr virus (EBV)-positive gastric cancer (GC) and two patients with microsatellite instability-high (MSI-H)/expression deficiency of mismatch repair (dMMR) protein GC, were enrolled in this study. Four patients experienced immunotherapy-related adverse events (irAEs), without severe adverse events (SAEs). Five patients underwent R0 resection, and one patient underwent palliative gastrectomy due to liver and hilar lymph node metastasis. Pathologic responses from the surgical tissue were observed in all patients, including two pathological complete response (pCR). No operative complications or postoperative deaths occurred. Three patients (50%) experienced mild or moderate postoperative complications without severe postoperative complications. All six patients eventually recovered and were discharged. CONCLUSION: This study indicated that PIT was effective and tolerant in some patients with MSI-H/dMMR and/or EBV-positive AGC. PIT followed by gastrectomy might be an alternative treatment option for these selected patients.

Safety and short-term outcomes of gastrectomy after preoperative chemotherapy plus immunotherapy versus preoperative chemotherapy: a retrospective cohort study.

BACKGROUND: The safety and short-term outcomes of gastrectomy after preoperative chemotherapy plus immunotherapy (PCIT) versus preoperative chemotherapy (PCT) in patients with advanced gastric cancer (AGC) remain unclear. This study was conducted to compare the safety and short-term efficacy of PCIT with those of PCT in patients with AGC. METHODS: We retrospectively reviewed the data of patients with AGC who received PCIT or PCT at Peking University Cancer Hospital and Institute Gastrointestinal Cancer Center I between January 2019 and June 2021. The clinical characteristics were recorded, and short-term oncological outcomes were compared. Independent t tests, Mann‒Whitney U tests, chi-square tests, and Fisher's exact tests were used to calculate differences. The correlation analyses were performed using Pearson correlation. All p values were two-sided, and a p value < 0.05 was considered statistically significant. All the above statistical analyses were conducted by the SPSS version 24.0 software package (IBM Corp., Armonk, NY, USA). RESULTS: A total of 162 AGC patients were included in this study, including 25 patients who received PCIT and 137 patients who received PCT. There were no significant differences in preoperative treatment-related adverse events (TRAEs) between the PCIT group and the PCT group (p = 0.088). Compared with the PCT group, the PCIT group had comparable postoperative functional recovery, with no significant differences in terms of time to first aerofluxus (p = 0.349), time to first defecation (p = 0.800), time to liquid diet (p = 0.233), or length of stay (p = 0.278). No significant differences were observed in terms of postoperative complications (p = 0.952), postoperative pain intensity at 24, 48, or 72 h (p = 0.375, p = 0.601, and p = 0.821, respectively), or postoperative supplementary analgesic use between the two groups (p = 0.881). In addition, the postoperative complication rate was 33.3% following laparoscopic approaches and 31.2% following open approaches in the PCIT group, with no significant difference (p = 1.000). CONCLUSION: In patients with AGC, gastrectomy with D2 or D2 + lymphadenectomy after PCIT had comparable short-term oncological outcomes to PCT.

Short-and long-term outcomes of laparoscopic versus open gastrectomy in patients with gastric cancer: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Laparoscopic gastrectomy (LG) for gastric cancer has rapidly developed and become more popular in recent decades. Additional high-quality randomized controlled trial (RCT) studies comparing LG versus open gastrectomy (OG) for gastric cancer (GC) have been published in recent years. An updated systematic review is warranted. The aim of our meta-analysis was to comprehensively evaluate the short- and long-term outcomes of LG versus OG for GC. MATERIALS AND METHODS: The PubMed, Embase, Web of Science, and Cochrane Center Register of Controlled Trials databases were comprehensively searched to identify RCTs comparing LG versus OG for GC published between January 1994 and December 7, 2021. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane Collaboration and the Quality of Reporting of Meta-analyses (QUORUM) guidelines. All RCTs comparing the short- and long-term outcomes of LG with those of OG were included. A random effects model was adopted with significant heterogeneity (I2 > 50%), while a fixed effects model was employed in all other cases (I2 ≤ 50%). RESULTS: A total of 26 RCTs with 8301 patients were included in this meta-analysis. The results indicated that the intraoperative complication rate was comparable between the LG group and the OG group (OR=1.14, 95% CI [0.76, 1.70], I2=0%, p=0.53). The LG group had fewer postoperative complications than the OG group (OR=0.65, 95% CI [0.57, 0.74], I2=26%, p<0.00001). However, the severe postoperative complication rate and perioperative mortality were comparable between the two groups (OR=0.83, 95% CI [0.67, 1.04], I2=10%, p=0.10; OR=1.11, 95% CI [0.59, 2.09], I2=0%, p=0.74, respectively). The number of lymph nodes retrieved by the LG group was less than that of the OG group (MD=-1.51, 95% CI [-2.29, -0.74], I2=0%, p<0.0001). The proximal resection margin distance in the LG group was shorter than that in the OG group (MD=-0.34, 95% CI [-0.57, -0.12], I2=23%, p=0.003), but the distal resection margin distance in the two groups was comparable (MD=-0.21, 95% CI [-0.47, 0.04], I2=0%, p=0.10). The time to first ambulation was shorter in the LG group than in the OG group (MD=-0.14, 95% CI [-.26, -0.01], I2=40%, p=0.03). The time to first flatus was also shorter in the LG group than in the OG group (MD=-0.15, 95% CI [-0.23, -0.07], I2=4%, p=0.0001). However, the first time on a liquid diet was comparable between the two groups (MD=-0.30, 95% CI [-0.64, 0.04], I2=88%, p=0.09). Furthermore, the postoperative length of stay was shorter in the LG group than in the OG group (MD=-1.26, 95% CI [-1.99, -0.53], I2=90%, p=0.0007). The 5-year overall survival (OS) was comparable between the two groups (HR=0.97, 95% CI [0.80, 1.17], I2=0%, p=0.73), and the 5-year disease-free survival (DFS) was also similar between the LG group and OG group (HR=1.08, 95% CI [0.77, 1.52], I2=0%, p=0.64). CONCLUSION: LG is a technically safe and feasible alternative to OG with the advantages of a fewer postoperative complication rate, faster recovery of gastrointestinal function, and greater cosmetic benefit for patients with GC. Meanwhile, LG has comparable long-term outcomes to OG for GC.

Selective interaction and its effect on collective motion.

Plenty of empirical evidence on biological swarms reveal that interaction between individuals is selective. Each individual's neighbor is selected based on one or more featured factors. Based on the self-propelled model, we develop a general probability neighbor selection framework to study the effect of four typical featured factors (i.e., distance, bearing, orientation change and bearing change). In this work, two common cases are involved to comprehensively analyze the impact of the four featured factors on the collective motion. One is the flocking, the other is the responsivity to stimulus. The impact of different selection strengths of the featured factors on both cases are investigated. The effect of noise on flocking and different stimulus intensities on responsivity to stimulus are analyzed. This study allows us to get the insight of selective interaction and suggests the potential solution to overcome the trade-off between flocking and responsivity quality.

Challenges of senior 8-year-program medical students' scientific research in China: A multicenter questionnaire-based study.

ABSTRACT: Among the diverse medical education systems in China, the 8-year program is dedicated to cultivating physician scientists. Although the research ability of senior students in 8-year medical programs is a pivotal quality, it remains unclear. This study aimed to clarify the current status and challenges of students' research experience, abilities, and outputs.A multicenter cross-sectional study was conducted in 5 medical schools in northern China. Electronic questionnaires were sent to 235 randomly chosen fifth-grade or sixth-grade 8-year-program medical students. A total of 211 responses were collected and analyzed using SPSS 22.0.Only 13.3% of participants chose research as their future career goal. Students generally felt that conducting research was stressful and difficult. The greatest obstacle was a lack of time due to heavy workloads. The 2 major motivations for research were graduation and/or future employment (75.8%) and research interest (24.2%). More than half of the students (142, 67.3%) had research experience by the time of the survey, among whom 84 students already had research outputs. A higher proportion of students with outputs was motivated by the requirements for graduation or employment compared to students without outputs (71.4% vs 55.2%, P  =  .046).Senior 8-year-program medical students in China generally had high pressure to conduct research and devoted their efforts to overcome these challenges. More guidance and novel encouragement to enhance students' initiative and interest in research could be provided by medical schools and educators in the future.

Short-term outcomes of laparoscopic versus open total gastrectomy after neoadjuvant chemotherapy: a cohort study using the propensity score matching method.

BACKGROUND: Until now, little is known about the benefit of laparoscopic total gastrectomy (LTG) after neoadjuvant chemotherapy (NACT). This study was designed to compare the safety and efficacy of the LTG versus the open total gastrectomy (OTG) approach after NACT treatment in patients with advanced gastric cancer (AGC). METHODS: This study involved a cohort of 145 patients with AGC who underwent total gastrectomy after NACT at our centre between April 2013 and August 2018 including 24 cases of LTG and 121 OTG. The baseline characteristics were matched based on 1:2 balanced propensity score-matching method. RESULTS: Sixty-nine marched cases were finally analysed (23 LTG vs. 46 OTG). All patients underwent R0 resection. Compared to the OTG group, the LTG group had a longer surgery duration (P<0.001), but a shorter incision length (P<0.001) and less intravenous patient-controlled analgesia (IV-PCA) time after surgery (P=0.027). No statistical differences were observed in terms of blood loss, retrieved lymph nodes (LNs), resection margin, length of stay, postoperative pain intensity, and complications (P>0.05). CONCLUSIONS: LTG had comparable safety and histological findings to OTG after NACT in the perioperative period; however, LTG is less invasive and patients can benefit from less IV-PCA use. Further research is needed to investigate long-term effects. KEYWORDS: Gastric cancer (GC); neoadjuvant chemotherapy (NACT); safety; laparoscopic technique.

Autonomous Searching for a Diffusive Source Based on Minimizing the Combination of Entropy and Potential Energy.

The infotaxis scheme is a search strategy for a diffusive source, where the sensor platform is driven to reduce the uncertainty about the source through climbing the information gradient. The infotaxis scheme has been successfully applied in many source searching tasks and has demonstrated fast and stable searching capabilities. However, the infotaxis scheme focuses on gathering information to reduce the uncertainty down to zero, rather than chasing the most probable estimated source when a reliable estimation is obtained. This leads the sensor to spend more time exploring the space and yields a longer search path. In this paper, from the context of exploration-exploitation balance, a novel search scheme based on minimizing free energy that combines the entropy and the potential energy is proposed. The term entropy is implemented as the exploration to gather more information. The term potential energy, leveraging the distance to the estimated sources, is implemented as the exploitation to reinforce the chasing behavior with the receding of the uncertainty. It results in a faster effective search strategy by which the sensor determines its actions by minimizing the free energy rather than only the entropy in traditional infotaxis. Simulations of the source search task based on the computational plume verify the efficiency of the proposed strategy, achieving a shorter mean search time.

[DREAM: a multifunctional transcriptional regulator].

DREAM (downstream regulatory element antagonist modulator), Calsenilin and KChIP3 (potassium channel interacting protein 3) belong to the neuronal calcium sensor (NCS) superfamily, which transduces the intracellular calcium signaling into a variety of activities. They are encoded by the same gene locus, but have distinct subcellular locations. DREAM was first found to interact with DRE (downstream regulatory element) site in the vicinity of the promoter of prodynorphin gene to suppress gene transcription. Calcium can disassemble this interaction by binding reversibly to DREAM protein on its four EF-hand motifs. Apart from having calcium dependent DRE site binding, DREAM can also interact with other transcription factors, such as cAMP responsive element binding protein (CREB), CREB-binding protein (CBP) and cAMP responsive element modulator (CREM), by this concerted actions, DREAM extends the gene pool under its control. DREAM is predominantly expressed in central nervous system with its highest level in cerebellum, and accumulating evidence demonstrated that DREAM might play important roles in pain sensitivity. Novel findings have shown that DREAM is also involved in learning and memory processes, Alzheimer's disease and stroke. This mini-review provides a brief introduction of its discovery history and protein structure properties, focusing on the mechanism of DREAM nuclear translocation and gene transcription regulation functions.