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Effective, long-range, and self-propelled water elevation and transport are important in industrial, medical, and agricultural applications. Although research has grown rapidly, existing methods for water film elevation are still limited. Scaling up for practical applications in an energy-efficient way remains a challenge. Inspired by the continuous water cross-boundary transport on the peristome surface of Nepenthes alata, here we demonstrate the use of peristome-mimetic structures for controlled water elevation by bending biomimetic plates into tubes. The fabricated structures have unique advantages beyond those of natural pitcher plants: bulk water diode transport behavior is achieved with a high-speed passing state (several centimeters per second on a milliliter scale) and a gating state as a result of the synergistic effect between peristome-mimetic structures and tube curvature without external energy input. Significantly, on further bending the peristome-mimetic tube into a “candy cane”-shaped pipe, a self-siphon with liquid diode behavior is achieved. Such a transport mechanism should inspire the design of next generation water transport devices.

Based on a balanced panel dataset of 272 prefecture-level cities from 2000 to 2022, this paper systematically investigates the impact of the carbon emissions trading system on green total factor productivity and its underlying mechanisms from an integrated perspective of overall, dynamic, and spatial dimensions. The findings reveal that (1) the carbon emissions trading system significantly enhances regional total factor productivity, primarily by optimizing resource allocation efficiency and strengthening regional competitiveness. (2) From a dynamic perspective, the policy effect exhibited a U-shaped relationship: from 2013 to 2018, green total factor productivity was suppressed due to underdeveloped market mechanisms and the policy environment; after 2018, with market maturation and policy stabilization, the policy effects improved significantly. (3) Spatial effect analysis indicates that the emissions trading system positively influences pilot regions but generates a siphon effect on nonpilot regions, leading to regional performance divergence, although the overall impact remains positive. (4) Heterogeneity analysis reveals that the policy has more pronounced effects in regions with higher carbon intensity, stricter environmental regulations, better infrastructure, and richer resource endowments, reflecting significant regional disparities in policy effectiveness. This study provides empirical evidence and theoretical insights to optimize carbon trading policies and achieve regional green development.

Motivation: We aim to study the boundary stability and persistence of positive odes in mathematical epidemiology models by importing structural tools from chemical reaction networks. This is largely a review work, which attempts to congregate the fields of mathematical epidemiology (ME), and chemical reaction networks (CRNs), based on several observations. We started by observing that epidemiologic strains, defined as disjoint blocks in either the Jacobian on the infected variables, or as blocks in the next generating matrix (NGM), coincide in most of the examples we studied, with either the set of critical minimal siphons or with the set of minimal autocatalytic sets (cores) in an underlying CRN. We leveraged this to provide a definition of the disease-free equilibrium (DFE) face/infected set as the union of either all minimal siphons, or of all cores (they always coincide in our examples). Next, we provide a proposed definition of ME models, as models which have a unique boundary fixed point on the DFE face, and for which the Jacobian of the infected subnetwork admits a regular splitting, which allows defining the famous next generating matrix. We then define the interaction graph on minimal siphons (IGMS), whose vertices are minimal siphons, and whose edges indicate the existence of reactions producing species in one siphon from species in another. When this graph is acyclic, we say the model exhibits an Acyclic Minimal Siphon Decomposition (AMSD). For AMSD models whose minimal siphons partition the infection species, we show that the NGM is block triangular after permutation, which implies the classical max structure of the reproduction number R0 for multi-strain models. In conclusion, using irreversible reaction networks, minimal siphons and acyclic siphon decompositions, we provide a natural bridge from CRN to ME. We implement algorithms to compute IGMS and detect AMSD in our Epid-CRN Mathematica package (which already contain modules to identify minimal siphons, criticality, drainability, self-replicability, etc.). Finally, we illustrate on several multi-strain ME examples how the block structure induced by AMSD, and the ME reproduction functions, allow expressing boundary stability and persistence conditions by comparing growth numbers to 1, as customary in ME. Note that while not addressing the general Persistence Conjecture mentioned in the title, our work provides a systematic method for deriving boundary instability conditions for a significant class of structured models.

Deadlocks should be eliminated in highly automated manufacturing systems since their occurrence implies the stoppage of the whole or partial system operation. Over the past decades, Petri nets are increasingly becoming one of the most popular and full-fledged mathematical tools to deal with deadlock problems due to their inherent characteristics. In a Petri net formalism, liveness is an important property of system safeness, which implies the absence of global and local deadlock situations in an automated manufacturing system. The liveness assessment can be performed by verifying the satisfiability of certain predicates on siphons, a well-known structural object in Petri nets. Therefore, siphons have received much attention to analyze and control systems modeled with Petri nets. Particularly, elementary siphon theory plays a key role in the development of structurally simple liveness-enforcing Petri net supervisors, leading to a variety of deadlock control approaches. This survey studies on the state-of-the-art elementary siphon theory of Petri nets including refined concepts of elementary siphons and their extended version, computation methods of siphons and elementary ones, controllability conditions, and their application to deadlock control. As a reference, this work attempts to provide a comprehensive and updated research survey on siphons, elementary siphons, and their applications to the deadlock resolution in Petri nets.

Siphons are devices that transport liquids uphill between two containers. It has been proposed that a siphon principle operates in closed circulatory systems, as best exemplified by the circulation of blood in mammals. This principle is supposed to ensure that no additional work is necessary to pump blood above the level of the heart, and that there is no gravitational static pressure gradient in the column of blood. The first statement is correct, while we demonstrate that, ignoring hydraulic resistance to blood flow, the static pressure gradient is equal to the hydrostatic gradient in a siphon model of blood circulation, although the details of the proof do not depend on the geometry of the circulatory system and the proof can be trivially extended to other models such as a vascular waterfall. This implies that the controversy over the siphon principle has no implications for the description of blood circulation, and that mechanisms such as the “baffle,” which some authors have appealed to in order to obtain the expected gradient, are not necessary. In our discussion, we also discuss empirical data that appear to provide additional verification of our results, as well as several everyday occurrences that provide additional support.

Deadlock control approaches based on Petri nets are usually implemented by adding control places and related arcs to the Petri net model of a system. The main disadvantage of the existing policies is that many control places and associated arcs are added to the initially constructed Petri net model, which significantly increases the complexity of the supervisor of the Petri net model. The objective of this study is to develop a two-step robust deadlock control approach. In the first step, we use a method of deadlock prevention based on strict minimal siphons (SMSs) to create a controlled Petri net model. In the second step, all control places obtained in the first step are merged into a single control place based on the colored Petri net to mark all SMSs. Finally, we compare the proposed method with the existing methods from the literature.

Shunt over-drainage in patients harboring a ventriculoperitoneal shunt constitutes one of the most devastating, and difficult to manage, side effects associated with this operation. Siphoning is one of the most important contributing factors that predispose to this complication. Based on the fact that the predisposing pathophysiologic mechanism is considerably multiplicated, amelioration of that adverse condition is considerably difficult to achieve. A lot of evidence suggests that the widespread utilization of gravitational valves or antisiphon devices is of utmost importance, in order to minimize or even avoid the occurrence of such complications. The recent literature data highlight that gravity-related, long-lasting shunt over-drainage consists of a momentous factor that could be considered one of the main culprits of central shunt failure. A lot of efforts have been performed, in order to design effective means that are aimed at annihilating siphoning. Our tenet was the investigation of the usefulness of the incorporation of an extra apparatus in the shunt system, capable of eliminating the impact of the siphoning effect, based on the experience that was gained by their long-term use in our institution. A retrospective analysis was performed, based on the data that were derived from our institution’s database, centered on patients to which an ASD was incorporated into their initial shunt device between 2006 and 2021. A combination of clinical, surgical, radiological findings, along with the relevant demographic characteristics of the patients were collected and analyzed. We attempted to compare the rates of shunt dysfunction, attributed to occlusion of the ventricular catheter, in a group of patients, before and after the incorporation of an anti-siphon device to all of them. A total number of 120 patients who have already been shunted due to hydrocephalus of different etiologies, were managed with the insertion of an ASD. These devices were inserted at different anatomical locations, which were located peripherally to the initially inserted valvular mechanism. The data that were collected from a subpopulation of 17 of these patients were subjected to a separate statistical analysis because they underwent a disproportionately large number of operations (i.e., >10-lifetime shunt revisions). These patients were studied separately as their medical records were complicated. The analysis of our records revealed that the secondary implementation of an ASD resulted in a decrease of the 1-year and 5-year central catheter dysfunction rates in all of our patients when compared with the relevant obstruction rates at the same time points prior to ASD insertion. According to our data, and in concordance with a lot of current literature reports, an ASD may offer a significant reduction in the obstruction rates that is related to the ventricular catheter of the shunt. These data could only be considered preliminary and need to be confirmed with prospective studies. Nevertheless, this study could be considered capable of providing supportive evidence that chronic shunt over-drainage is a crucial factor in the pathophysiology of shunt malfunction. Apart from that, it could provide pilot data that could be reviewed in order to organize further clinical and laboratory studies, aiming toward the assessment of optimal shunt valve systems that, along with ASD, resist siphoning.

A novel siphon-based divide-and-conquer (SbDaC) policy is presented in this paper for the synthesis of Petri net (PN) based liveness-enforcing supervisors (LES) for flexible manufacturing systems (FMS) prone to deadlocks or livelocks. The proposed method takes an uncontrolled and bounded PN model (UPNM) of the FMS. Firstly, the reduced PNM (RPNM) is obtained from the UPNM by using PN reduction rules to reduce the computation burden. Then, the set of strict minimal siphons (SMSs) of the RPNM is computed. Next, the complementary set of SMSs is computed from the set of SMSs. By the union of these two sets, the superset of SMSs is computed. Finally, the set of subnets of the RPNM is obtained by applying the PN reduction rules to the superset of SMSs. All these subnets suffer from deadlocks. These subnets are then ordered from the smallest one to the largest one based on a criterion. To enforce liveness on these subnets, a set of control places (CPs) is computed starting from the smallest subnet to the largest one. Once all subnets are live, this process provides the LES, consisting of a set of CPs to be used for the UPNM. The live controlled PN model (CPNM) is constructed by merging the LES with the UPNM. The SbDaC policy is applicable to all classes of PNs related to FMS prone to deadlocks or livelocks. Several FMS examples are considered from the literature to highlight the applicability of the SbDaC policy. In particular, three examples are utilized to emphasize the importance, applicability and effectiveness of the SbDaC policy to realistic FMS with very large state spaces.

Amino acids play essential roles in various biological processes. In humans, most amino acids are present in the l -form; however, small amounts of d -amino acids also exist and have significant physiological roles, highlighting the importance of dietary intake from foods or drinks. In this study, we investigated the amino acid composition of the geoduck clam Panopea japonica , emphasizing its remarkably high d -alanine ( d -Ala) content in the siphon tissue. The d -Ala content (6.99–14.2 mmol/100 g-wet) amounted to 91–94% of the total Ala, far exceeding that of other bivalves such as Tresus keenae (74%). Enzyme assays revealed alanine racemase and d -amino acid oxidase activities, suggesting active d -Ala biosynthesis and metabolism. The high concentrations of d -Ala enhance its value as a delicacy owing to its unique sweetness. This study provides new insights into the biosynthesis and metabolic characteristics of d -Ala in bivalves, highlighting its physiological and food ingredient significance.

Both deadlocks and livelocks can result in the serious problems in running process of a flexible manufacturing system (FMS). This study proposes an iterative control policy for an FMS modelled with Petri nets on the basis of a combination of revised mixed integer programming and the concept of max′-controlled siphon, which can not only solve the smart siphons associated with deadlocks and livelocks in Petri nets directly, but also make them max′-controlled. Accordingly, an original Petri net system with deadlocks and livelocks can be turned into the live controlled one with a simple structure, and meanwhile no smart siphons can be found in it. It lays foundations for further analysis and control on deadlocks and livelocks. Compared with the existing methods in the literature, the proposed one is more general and effective. A theoretical analysis and several examples are given to demonstrate its efficiency and practical potentials.