Discrete Steps Research Articles

Finite-Time Stability for Caputo Nabla Fractional-Order Switched Linear Systems

In this paper, we address the finite-time stability problem of Caputo nabla fractional-order switched linear systems with α∈(0,1). Firstly, the monotonicity of the discrete Mittag-Leffler function is proposed. Secondly, under the per-designed switching rules, the form of the solution for Caputo nabla fractional-order switched linear systems is obtained by using the discrete unit step function. On the above basis, some sufficient conditions of finite-time stability for Caputo nabla fractional-order switched linear systems are proposed, according to the discrete Grönwall inequality and the monotonicity of the discrete Mittag-Leffler function. Finally, simulation verification is carried out via three numerical examples.

One-pot synthesis of bimetallic Ni/Ag nanosphere inside colloidal silica cavities for in situ SERS monitoring of the elementary steps of chemoselective nitroarene reduction evidenced by DFTB calculation

Spherically shaped bimetallic Ni/Ag nanocomposite is synthesized in one-pot within colloidal silica cavities in aqueous media in an efficient way and is characterized using UV-Vis, IR, EPR, Raman, powder XRD, SEM, TEM, and SERS. This could trigger the chemoselective NaBH4 reduction of nitoarenes under solvent free conditions at ambient temperature in excellent yields. The process could be scaled up to multi-gram scale without any need for temperature control and organic extractor. This spherical nanocomposite showed good operational stability, robustness and recyclability as is evidenced by a model reaction of 2-nitophenol (2-NP) to 2-aminophenol (2-AP). Reduction of nitroarenes is widely used for the studies of catalytic efficacy of nanoparticles as its mechanism is still unproven in heterogenous condition. Although complicated, a real time monitoring of surface-enhanced Raman scattering (SERS) with discrete steps, by placing the surface-immobilized reactant molecules at the well-defined spherical nanocomposite, we identified dihydroxyazobenzene (DHAB) as the intermediate. The catalysing process was further studied computationally using DFTB level of theory through Nudged elastic band (NEB) method to locate the involved transition states and intermediates. Overall, the results demonstrate that spherical Ni/Ag@silica bimetallic nanocomposite could catalyse the selective activation of NaBH4 reduction of nitoarenes in a fast, clean process and SERS as a powerful tool for studying heterogeneous catalysis and hence, the present catalyst system constitutes one straightforward and environmentally safe approach to a class of much sought organic transformation.

Interference-free walks in time: temporally disjoint paths

We investigate the computational complexity of finding temporally disjoint paths and walks in temporal graphs. There, the edge set changes over discrete time steps. Temporal paths and walks use edges that appear at monotonically increasing time steps. Two paths (or walks) are temporally disjoint if they never visit the same vertex at the same time; otherwise, they interfere. This reflects applications in robotics, traffic routing, or finding safe pathways in dynamically changing networks. At one extreme, we show that on general graphs the problem is computationally hard. The path version is NP-hard even if we want to find only two temporally disjoint paths. The walk version is W-hard (Klobas in IJCAI 4090–4096, 2021) when parameterized by the number of walks. However, it is polynomial-time solvable for any constant number of walks. At the other extreme, restricting the input temporal graph to have a path as underlying graph, quite counter-intuitively, we find NP-hardness in general but also identify natural tractable cases.

Specific steps in the operation determine resident speed: Experience with a live tissue simulation model of laparoscopic nephrectomy.

It is increasingly important to identify and eliminate inefficiencies in resident education. We hypothesize that slower performance of specific operative steps in laparoscopic nephrectomy accounts for much of the slower operative speed observed in junior residents vs. their senior colleagues. Therefore, we sought to evaluate the by-step time-differential between experienced senior residents and their junior colleagues in a live-tissue simulation. Residents participated in our swine model surgical simulation of laparoscopic radical and partial nephrectomy (LRNx and LPNx). PGY5 and 6 residents were considered senior; junior residents were PGY3 and 4. We defined discrete surgical steps. Residents' post-graduate training levels were tracked and time-to-completion of each operative step was recorded. Seven live-tissue simulations sessions took place, with 12 residents conducting 22 operations (12 LRNx, 10 LPNx). On average, each resident operated in 2 simulation sessions (range 1-4). The average time required by senior residents for LPNx was 152 min; junior residents required 173 min (p = 0.35). When considering the operative steps, juniors required nearly twice as much time to achieve hilar control (42 min vs. 23 min, p = 0.03). Significant differences in performance time were not seen in the other steps. The performance differential between senior and junior residents conducting nephrectomies was most evident during hilar dissection. Our study suggests that specific efforts should be focused on teaching junior residents the skills required for this step early in their training.

Numerical Prediction of Long-Term Droplet Erosion and Washing Efficiency of Axial Compressors Through the Use of a Discrete Mesh Morphing Approach

Abstract Online water washing represents an operation strategy commonly used to reduce compressor performance deterioration due to blade fouling. Since this kind of washing is applied when the machine operates close to full load conditions, injected droplets are strongly accelerated and consequently impact the rotor blades at high velocity, thus inducing undesirable phenomena like erosion. Here, we present a novel technique to study long-term water droplets erosion by also considering the geometry modification caused by droplets impacts. Two-phase unsteady numerical simulations were carried out, considering the injection of water droplets and their transport across the fluid flow in the first part of a real compressor, which is modeled in the region extending from the inlet to the rotor blades of the first stage. Simulations are performed on the whole machine to account for the asymmetric distribution of the spray injectors, the machine struts, inlet guide vanes (IGVs), and rotor blades. The k−ɛ realizable turbulence model with standard wall functions was coupled with the discrete phase model to track injected droplets motion. Droplets-wall interaction is modeled following the Stanton–Rutland approach aiming at detecting the effect of droplet impact (deposit, rebound, and splashing) depending on the impact conditions. Moreover, a semi-empirical erosion model developed by the authors was used to evaluate the erosion induced by the droplets injection. Material removal due to erosion is converted into nodal mesh displacement that is used by a secondary routine to implement the mesh morphing scheme. The mesh modification is applied at discrete steps to reduce the computational load. This technique is adopted to account for the blades geometry modification due to water droplet erosion leading to performance losses. Moreover, an estimation of the compressor operating life before maintenance operations is given and the water washing efficiency during the whole life of the machine is evaluated by means of proper indices. At the end of the simulation workflow, erosion phenomena are observed in all the compressor regions, especially in the rotor where erosion peaks are reached at the hub of the blades leading edge. The rotor blades wet surface was found to remain almost constant at around 50% during compressor water washing. Erosive phenomena were proved to evolve nonlinearly with time indicating the need to account for the geometry modification for obtaining an accurate prediction of the long-time process.

Numerical evaluation of ODE solutions by Monte Carlo enumeration of Butcher series

We present an algorithm for the numerical solution of ordinary differential equations by random enumeration of the Butcher trees used in the implementation of the Runge–Kutta method. Our Monte Carlo scheme allows for the direct numerical evaluation of an ODE solution at any given time within a certain interval, without iteration through multiple time steps. In particular, this approach does not involve a discretization step size, and it does not require the truncation of Taylor series.

Microwave photonics scanning channelizer with digital image-reject mixing and linearization

Microwave photonics scanning channelizer with digital image-reject mixing and linearization is investigated by employing a cascaded distributed feedback semiconductor laser (DFB) operating at stable locking dynamics when subjected to flat optical frequency comb (OFC) injection. The OFC injection locking (OIL) provides a high-quality coherent optical local oscillator with ultra-broadband tuning capability by demultiplexing and amplifying individual comb from densely spaced OFC. The channelizer receiver scans the whole frequency range at discrete steps through a single tunable heterodyne receiver and a single ADC, thus reducing the SWaP and increasing agility. By introducing the digital Hartley structure image-reject mixing (IRM), the amplitude and phase imbalance of the IQ channel are easily compensated, resulting in a high image rejection ratio (IRR) up to around ∼50 dB for all channels. Furthermore, a novel digital linearization technique is employed to suppress third-order intermodulation components by more than 19.43 dB while improving the spurious free dynamic range (SFDR) by 16.1 dB The analysis confirms the scheme’s capability for detecting signals from 1.5 GHz to 43.5 GHz and beyond with excellent performance. The proposed channelizer can find applications in future wideband RF systems, including 5G and beyond wireless communications, electronic warfare, and radars.

Gap junctions mediate discrete regulatory steps during fly spermatogenesis.

Gametogenesis requires coordinated signaling between germ cells and somatic cells. We previously showed that Gap junction (GJ)-mediated soma-germline communication is essential for fly spermatogenesis. Specifically, the GJ protein Innexin4/Zero population growth (Zpg) is necessary for somatic and germline stem cell maintenance and differentiation. It remains unknown how GJ-mediated signals regulate spermatogenesis or whether the function of these signals is restricted to the earliest stages of spermatogenesis. Here we carried out comprehensive structure/function analysis of Zpg using insights obtained from the protein structure of innexins to design mutations aimed at selectively perturbing different regulatory regions as well as the channel pore of Zpg. We identify the roles of various regulatory sites in Zpg in the assembly and maintenance of GJs at the plasma membrane. Moreover, mutations designed to selectively disrupt, based on size and charge, the passage of cargos through the Zpg channel pore, blocked different stages of spermatogenesis. Mutations were identified that progressed through early germline and soma development, but exhibited defects in entry to meiosis or sperm individualisation, resulting in reduced fertility or sterility. Our work shows that specific signals that pass through GJs regulate the transition between different stages of gametogenesis.

Early embryonic development of Johnston’s organ in the antenna of the desert locust Schistocerca gregaria

Johnston’s organ has been shown to act as an antennal auditory organ across a spectrum of insect species. In the hemimetabolous desert locust Schistocerca gregaria, Johnston’s organ must be functional on hatching and so develops in the pedicellar segment of the antenna during embryogenesis. Here, we employ the epithelial cell marker Lachesin to identify the pedicellar domain of the early embryonic antenna and then triple-label against Lachesin, the mitosis marker phosphohistone-3, and neuron-specific horseradish peroxidase to reveal the sense-organ precursors for Johnston’s organ and their lineages. Beginning with a single progenitor at approximately a third of embryogenesis, additional precursors subsequently appear in both the ventral and dorsal pedicellar domains, each generating a lineage or clone. Lineage locations are remarkably conserved across preparations and ages, consistent with the epithelium possessing an underlying topographic coordinate system that determines the cellular organization of Johnston’s organ. By mid-embryogenesis, twelve lineages are arranged circumferentially in the pedicel as in the adult structure. Each sense-organ precursor is associated with a smaller mitotically active cell from which the neuronal complement of each clone may derive. Neuron numbers within a clone increase in discrete steps with age and are invariant between clones and across preparations of a given age. At mid-embryogenesis, each clone comprises five cells consolidated into a tightly bound cartridge. A long scolopale extends apically from each cartridge to an insertion point in the epithelium, and bundled axons project basally toward the brain. Comparative data suggest mechanisms that might also regulate the developmental program of Johnston’s organ in the locust.

Power consumption analysis of an optical modulator based on different amounts of graphene

Energy-efficient devices will play a key role in the continued performance scaling of next-generation information and communications technology systems. Graphene has emerged as a key optoelectronic material with unique energy-like properties. But to the best of our knowledge, these advantages have not yet been fully exploited in optical modulators design. In this work, we design and analyze an optical modulator which is composed of two graphene layers and a ring resonator made with different amount of graphene. For performance analysis, the ring resonator’s amount of graphene is varied from 25 to 100% with four discrete steps. The critical coupling condition representing the OFF-state, and the 3-dB transmission level representing the ON-state of the device are obtained. Numerical results show this new optical modulator consumes as little energy as 4.6 fJ/bit whilst achieving a high-speed operation with a bandwidth up to 42.6 GHz when employing surprisingly only 25% of graphene. The 42.6 GHz modulator has a footprint as small as 22.1 µm2 with an active area of 1.68 µm2 only, the smallest active area to date. Alternatively, the optical modulator achieves up to ∼88.5 GHz at the expense of consuming 17.5 fJ/bit when using 100% of graphene. The proposed graphene-based modulator proved to be a compact, energy-efficient, high-speed device, useful for a myriad of applications including mobile fronthaul, telecom, and datacom.

Practical Steps to Writing a Scientific Manuscript.

Writing a scientific manuscript can be a very intimidating process for new writers. However, writing a scientific research article can be broken down into discrete steps to make the process more digestible. Radiology manuscripts have common conventions that differ from research in technical and other medical fields. The practical steps summarized within describe what to do before you start writing, successful writing strategies, and common writing styles. Templates for producing an abstract, introduction, methods, results, and discussion are outlined, along with tips to collect references and produce high quality figures. All writers can benefit from an outside writing perspective, and the practical steps described should ease the transition from a blank page to a finished manuscript.

On the Design and Implementation of a Blockchain-Based Data Management System for ETO Manufacturing

Engineer-to-order (ETO) is a currently popular production model that can meet customers’ individual needs, for which the orders are primarily non-standard parts or small batches. This production model has caused many management challenges, including the difficulty of tracing the production process data of products and the inability to monitor order status in real-time. In this paper, by analyzing the steps of ETO manufacturing and the business process between departments in the manufacturing industry, a blockchain-based process data management system (BPDMS) is proposed. The immutable nature of the blockchain data ensures the data’s validity and consistency in each production step. Furthermore, by embedding the sequential aggregate signature in the system, the sequence verification of discrete process steps can be completed in time. Finally, an electrical equipment assembly production platform is used to discuss the specific implementation on top of the Hyperledger Fabric, a permissioned blockchain. The experiment results show that the proposed system effectively manages the process data of ETO-type production, and the real-time querying of the production status of the orders.

Target Set Selection Parameterized by Vertex Cover and More

Diffusion is a natural phenomenon in many real-world networks. Spreading of ideas, rumors in an online social network; propagation of virus, malware in a computer network; spreading of diseases in a human contact network, etc. are some real-world examples of this. Diffusion often starts from a set of initial nodes known as seed nodes. A node can be in any one of the following two states: influenced (active) or not influenced (inactive). We assume that a node can change its state from inactive to active, however, not vice versa. Only the seed nodes are active initially and the information is dissipated from these seed nodes in discrete time steps. Each node v is associated with a threshold value τ(v) which is a positive integer. A node v will be influenced at time step \(t^{\prime }\), if there are at least τ(v) number of nodes in its neighborhood which have been activated on or before time step \(t^{\prime }-1\). The diffusion stops when no more node-activation is possible. Given a simple, undirected graph G with a threshold function \(\tau :V(G) \rightarrow \mathbb {N}\), the Target Set Selection (TSS) problem is about choosing a minimum cardinality set, say \(S \subseteq V(G)\), such that starting a diffusion process with S as its seed set will eventually result in activating all the nodes in G. For any non-negative integer i, we say a set \(T\subseteq V(G)\) is a degree-i modulator of G if the degree of any vertex in the graph G − T is at most i. Degree-0 modulators of a graph are precisely its vertex covers. Consider a graph G on n vertices and m edges. We have the following results on the TSS problem: It was shown by Nichterlein et al. (Soc. Netw. Anal. Min. 3(2), 233–256 10) that it is possible to compute an optimal-sized target set in \(\boldsymbol {O}(\boldsymbol {2}^{(\boldsymbol {2}^{t}+\boldsymbol {1})\boldsymbol {t}}\boldsymbol {\cdot m})\) time, where t denotes the cardinality of a minimum degree-0 modulator of G. We improve this result by designing an algorithm running in time \(\boldsymbol {2}^{\boldsymbol {O}(\boldsymbol {t}\log \boldsymbol {t})}\boldsymbol {n}\). We design a \(\boldsymbol {2}^{\boldsymbol {2}^{\boldsymbol {O}(\boldsymbol {t})}}\boldsymbol {n}^{\boldsymbol {O}(\boldsymbol {1})}\) time algorithm to compute an optimal target set for G, where t is the size of a minimum degree-1 modulator of G. We show that for a graph on n vertices of treewidth s, the TSS problem cannot be solved in \(\boldsymbol {f}(\boldsymbol {s})\boldsymbol {n}^{\boldsymbol {o}(\boldsymbol {\frac {s}{\log s}})}\) time unless the Exponential Time Hypothesis fails. This is an improvement over the previously known lower bound of \(\boldsymbol {f}(\boldsymbol {s})\boldsymbol {n}^{\boldsymbol {o}(\sqrt {\boldsymbol {s}})}\) due to Ben-Zwi et al. (Discret. Optim. 8(1), 87–96 16). In fact, we prove that same lower bound holds when parameterized by tree-depth or star-deletion number.

Multistage online maxmin allocation of indivisible entities

We consider an online allocation problem that involves a set P of n players and a set E of m indivisible entities over discrete time steps 1,2,…,τ. At each time step t∈[1,τ], for every entity e∈E, there is a restriction list Lt(e) that prescribes the subset of players to whom e can be assigned and a non-negative value vt(e,p) of e to every player p∈P. The sets P and E are fixed beforehand. The sets Lt(⋅) and values vt(⋅,⋅) are given in an online fashion. An allocation is a distribution of E among P, and we are interested in the minimum total value of the entities received by a player according to the allocation. In the static case, it is NP-hard to find an optimal allocation the maximizes this minimum value. On the other hand, ρ-approximation algorithms have been developed for certain values of ρ∈(0,1]. We propose a w-lookahead algorithm for the multistage online maxmin allocation problem for any fixed w⩾1 in which the restriction lists and values of entities may change between time steps, and there is a fixed stability reward for an entity to be assigned to the same player from one time step to the next. The objective is to maximize the sum of the minimum values and stability rewards over the time steps 1,2,…,τ. Our algorithm achieves a competitive ratio of (1−c)ρ, where c is the positive root of the equation wc2=ρ(w+1)(1−c). When w=1, it is greater than ρ4ρ+2+ρ10, which improves upon the previous ratio of ρ4ρ+2−21−τ(2ρ+1) obtained for the case of 1-lookahead.

Brain-inspired sensorimotor echolocation system for confident landmark recognition.

A landmark is a familiar target in terms of the echoes that it can produce and is important for echolocation-based navigation by bats, robots, and blind humans. A brain-inspired system (BIS) achieves confident recognition, defined as classification to an arbitrarily small error probability (PE), by employing a voting process with an echo sequence. The BIS contains sensory neurons implemented with binary single-layer perceptrons trained to classify echo spectrograms with PE and generate excitatory and inhibitory votes in face neurons until a landmark-specific face neuron achieves recognition by reaching a confidence vote level (CVL). A discrete random step process models the vote count to show the recognition probability can achieve any desired accuracy by decreasing PE or increasing CVL. A hierarchical approach first classifies surface reflector and volume scatterer target categories and then uses that result to classify two subcategories that form four landmarks. The BIS models blind human echolocation to recognize four human-made and foliage landmarks by acquiring suitably sized and dense audible echo sequences. The sensorimotor BIS employs landmark-specific CVL values and a 2.7° view increment to acquire echo sequences that achieve zero-error recognition of each landmark independent of the initial view.

Route Planning and Tracking Control of an Intelligent Automatic Unmanned Transportation System Based on Dynamic Nonlinear Model Predictive Control

Tracking control is one of the important working conditions of unmanned driving and can help vehicles keep distances and run in an orderly manner to improve traffic utilization, ensure clear roads and avoid rear-end collisions. This paper constructs the motion trend of obstacles within the predictive step length of model predictive control (MPC), designs the danger level indicator between vehicles and obstacles, and formulates dynamic planning for the original reference path based on MPC. This paper proposes an integrated collision avoidance control strategy based on dynamic nonlinear MPC (DNMPC), and predicts the locations of moving obstacles within the predictive step length of DNMPC. The proposed method can perform initial planning for the collision-avoidance path according to the road environment information and based on the activation function. It builds the function for the tendency of obstacles within the predictive step length of MPC, introduces it into the objective function for optimization, designs dynamic path planning control based on the theories of MPC, and performs local optimization to the initial reference path under the obstacles in motion with a mass model. In addition, it defines varying discrete step lengths within the predictive step length and achieves the long-distance prediction and high-precision control of collision avoidance controllers. The experimental results show that the dynamic, nonlinear, and integrated collision avoidance control proposed in this paper can ensure excellent collision avoidance and steady vehicle driving and has very good practical value.

Multiagent Reinforcement Learning-Based Adaptive Sampling for Conformational Dynamics of Proteins.

Machine learning is increasingly applied to improve the efficiency and accuracy of molecular dynamics (MD) simulations. Although the growth of distributed computer clusters has allowed researchers to obtain higher amounts of data, unbiased MD simulations have difficulty sampling rare states, even under massively parallel adaptive sampling schemes. To address this issue, several algorithms inspired by reinforcement learning (RL) have arisen to promote exploration of the slow collective variables (CVs) of complex systems. Nonetheless, most of these algorithms are not well-suited to leverage the information gained by simultaneously sampling a system from different initial states (e.g., a protein in different conformations associated with distinct functional states). To fill this gap, we propose two algorithms inspired by multiagent RL that extend the functionality of closely related techniques (REAP and TSLC) to situations where the sampling can be accelerated by learning from different regions of the energy landscape through coordinated agents. Essentially, the algorithms work by remembering which agent discovered each conformation and sharing this information with others at the action-space discretization step. A stakes function is introduced to modulate how different agents sense rewards from discovered states of the system. The consequences are three-fold: (i) agents learn to prioritize CVs using only relevant data, (ii) redundant exploration is reduced, and (iii) agents that obtain higher stakes are assigned more actions. We compare our algorithm with other adaptive sampling techniques (least counts, REAP, TSLC, and AdaptiveBandit) to show and rationalize the gain in performance.

Middle Miocene faulting and basin evolution during central Basin and Range extension: A detailed record from the upper Horse Spring Formation and red sandstone unit, Lake Mead region, Nevada, USA

AbstractMiocene basins of the Lake Mead region (southwestern United States) contain a well-exposed record of rifting and the evolving paleogeography of the eastern central Basin and Range. The middle Miocene Horse Spring Formation and red sandstone unit allow for detailed stratigraphic, chronostratigraphic, and structural analysis for better understanding the geologic history of extension in this region. We present new data from the White Basin and Lovell Wash areas (Nevada) to interpret the evolution of faulting, basin fill, and paleogeography. We conclude that tectonics strongly influenced sedimentation and hypothesize that climate may have played a secondary but important role in creating stratigraphic variations. Deposited from 14.5 to 13.86 Ma, the microbialitic Bitter Ridge Limestone Member of the Horse Spring Formation, the stratigraphically lowest unit in this study, records a widespread shallow and uniform lake which had moderate and steady sedimentation rates, both of which were controlled by a few faults. The persistent lake was broken up by fault reorganization followed by deposition of the highly variable fluvial-lacustrine facies of the Lovell Wash Member from 13.86 to 12.7 Ma. During this time, faulting shifted from the northeast-trending, oblique normal left-lateral White Basin fault to the northwest-trending, normal Muddy Peak fault and other smaller northwest-trending faults. The lower and middle portions of the red sandstone unit, 12.7–11.4 Ma, record an increase in the sedimentation rate of basin fill near the Muddy Peak fault as well as the return to widespread lacustrine conditions. Sedimentation and faulting slowed during deposition of the uppermost red sandstone unit, but some deformation occurred post–11.4 Ma. This study records basin-fill evolution including variations in depositional environments laterally and vertically, documents changes in the location and magnitude of faulting, supports earlier work that hypothesized faulting proceeded in discrete westward steps across the Lake Mead area, and helps constrain the paleogeographic and tectonic evolution of the region.

Fertility-sparing surgery for diffuse adenomyosis: a narrated, stepwise approach to the Osada procedure

To equip reproductive surgeons with an approach to the Osada procedure and critical prophylactic hemostatic measures that optimize perioperative outcomes. Stepwise demonstration of the Osada procedure with narrated video footage. Definitive management of symptomatic adenomyosis requires hysterectomy. However, adenomyomectomy can improve symptoms and restore anatomy while maintaining fertility potential. Limited but comparable perioperative outcomes exist for minimally invasive methods of adenomyomectomy, and most involve resection of focal, not diffuse, adenomyosis. Among the literature involving resection of diffuse adenomyosis using minimally invasive methods, relatively small volumes of resected tissue are reported and none include obstetric outcomes. Most published reports for excision of diffuse adenomyosis involve laparotomic resection, likely because of specific intraoperative challenges curtailed by this approach. In response, a laparoscopic-assisted laparotomic approach was developed in 2011 by Dr. Hisao Osada, a reproductive surgeon in Japan. This procedure involves aggressive excision of adenomyotic tissue with prophylactic hemostatic techniques and subsequent uterine wall reconstruction using a triple-flap method. Compared with other excisional methods for diffuse adenomyomectomy, the Osada procedure has the best reported obstetric outcomes. A 37-year-old nulliparous female presented with pelvic pain, bulk symptoms, abnormal uterine bleeding, and infertility. Physical examination demonstrated a 20-week, bulky uterus with limited bimanual mobility. Her endometrial cavity was inaccessible because of marked anatomic distortion. Magnetic resonance imaging revealed marked abnormality of her endometrial contour because of a 15 cm adenomyoma with diffuse adenomyomatous tissue in the posterior uterine compartment. Prior interventions included a trial of combined hormonal contraceptive, leuprolide acetate, and tranexamic acid. She was interested in fertility-sparing adenomyomectomy to address symptoms and fertility potential and chose to proceed with the Osada procedure. She was optimized medically with oral and parenteral iron therapy to bring her hemoglobin from 55-111 g/L preoperatively. Institutional review board approval and informed consent from the patient were obtained. The Osada procedure was performed using the following 8 surgical steps: Systemic administration of tranexamic acid was also administered intraoperatively. Perioperative blood loss, anatomic normalization, symptom remediation, and maintenance of fertility potential. Perioperative blood loss was minimal, 469 g of adenomyotic tissue was extracted, and discharge was on postoperative day 2 without any complications. Three months later, cyclic pain and bleeding had improved markedly, ultrasound confirmed Doppler flow throughout the uterus, hysterosalpingogram demonstrated a nonobliterated endometrial cavity and tubal patency, and magnetic resonance imaging confirmed normalized uterine dimensions measuring 11 × 7 cm from 19 × 10 cm. Most literature supports waiting at least 6-12 months and until demonstration of normalized uterine blood flow in the operated area before attempting conception. Fertility-sparing excision of diffuse adenomyosis can be achieved safely using the Osada procedure, following the 8 discrete steps demonstrated in this video. Reproductive surgeons can reference this video to teach and maintain this important procedure.

Reconstitution of the S. aureus agr quorum sensing pathway reveals a direct role for the integral membrane protease MroQ in pheromone biosynthesis

In Staphylococcus aureus, virulence is under the control of a quorum sensing (QS) circuit encoded in the accessory gene regulator (agr) genomic locus. Key to this pathogenic behavior is the production and signaling activity of a secreted pheromone, the autoinducing peptide (AIP), generated following the ribosomal synthesis and posttranslational modification of a precursor polypeptide, AgrD, through two discrete cleavage steps. The integral membrane protease AgrB is known to catalyze the first processing event, generating the AIP biosynthetic intermediate, AgrD (1-32) thiolactone. However, the identity of the second protease in this biosynthetic pathway, which removes an N-terminal leader sequence, has remained ambiguous. Here, we show that membrane protease regulator of agr QS (MroQ), an integral membrane protease recently implicated in the agr response, is directly involved in AIP production. Genetic complementation and biochemical experiments reveal that MroQ proteolytic activity is required for AIP biosynthesis in agr specificity group I and group II, but not group III. Notably, as part of this effort, the biosynthesis and AIP-sensing arms of the QS circuit were reconstituted together invitro. Our experiments also reveal the molecular features guiding MroQ cleavage activity, a critical factor in defining agr specificity group identity. Collectively, our study adds to the molecular understanding of the agr response and Staphylococcus aureus virulence.