Fluid net models: from behavioral properties to structural objects

Increasing the production in manufacturing systems is one of the main demands in modern systems. The naive approach that this goal can be achieved when more or faster resources are used is not always valid. In fact, the complex interactions among system’s elements may lead to paradoxical behaviors; for example, using faster machines could reduce the equilibrium throughput (number of part fabricated per unit time in steady state) of the system, or even worse, block all system activities, reducing it to zero. This work leverages the concepts about fluidization and analysis techniques used in Timed Continuous Petri nets (TCPN) presented in earlier works to study the behavior of the equilibrium throughput when more/faster machines are used. Herein, we illustrate how discontinuities induced bifurcations of the equilibrium throughput are due to the existence of paths that can increase/decrease the marking of certain subnets. In particular, if paths gaining/losing tokens are fired without a particular balance, then the equilibrium throughput exhibits discontinuities since the equilibrium marking loses hyperbolicity. Moreover, these discontinuities imply other undesired throughput behaviors; for example, the existence of non-monotonicities of the equilibrium throughput (when more/faster resources are used in the system, its equilibrium throughput is reduced). The discontinuities together with a homothecy property are used to explain non-monotonicities in the equilibrium throughput. A relevant aspect is that these undesired system behaviors appear when the net has structural objects named problematic configurations that are associated with certain subnets in which there are no P-semiflows. Although the number of these configurations increase exponentially in the size of the net, some reduction rules are introduced to remove configurations, while the problematic ones are kept (or can be recovered) in the reduced net. This saves computation time in the analysis and, more importantly, provides useful insights about the root of undesired behaviors. This work focus on systems that can be modeled with fluid (or continuous) mono T-semiflow Timed Continuous Petri nets. Even if under certain constraints, they are capable of capturing many characteristics of modern systems, such as interleaving of cooperation and competition

Structural Sequence Detectability in Free Choice Interpreted Petri Nets

This paper is concerned with the structural sequence detectability problem in Free Choice Interpreted Petri nets, i.e. with the possibility of recovering the firing transition sequence in Free Choice Interpreted Petri nets using the output information when the initial marking is unknown. Based on the Free Choice Interpreted Petri net structure, three relationships are proposed which are devoted to capture the confusion over the transitions. These relationships depend on interpreted Petri nets structures such as T-invariants, P-Invariants, attribution and distribution places. Thus, the approach herein presented exploits the interpreted Petri nets structural information in order to determine the structural sequence detectability of an interpreted Petri net.Consejo Nacional de Ciencia y Tecnologí

Energy-Efficient Thermal-Aware Scheduling for RT Tasks Using TCPN

This work leverages TCPNs to design an energy-efficient, thermal-aware real-time scheduler for a multiprocessor system that normally runs in a low state energy at maximum system utilization but its capable of increasing the clock frequency to serve aperiodic tasks, optimizing energy, and honoring temporal and thermal constraints. An off-line stage computes the minimum frequency required to run the periodic tasks at maximum CPU utilization, the proportion of each task''s job to be run on each CPU, the maximum clock frequency that keeps temperature under a limit, and the available cycles (slack) with respect to the system with minimum frequency. Then, a Zero-Laxity online scheduler dispatches the periodic tasks according to the offline calculation. Upon the arrival of aperiodic tasks, it increases clock frequency in such a way that all periodic and aperiodic tasks are properly executed. Thermal and temporal requirements are always guaranteed, and energy consumption is minimized

A flexible framework for real-time thermal-aware schedulers using timed continuous petri nets

This work presents TCPN-ThermalSim, a software tool for testing Real-Time Thermal-Aware Schedulers1. This framework consists of four main modules. The first one helps the user to define the problem: Task set with periods, deadlines and worst case execution times in CPU cycles, along with the CPU characteristics, temperature and energy consumption. The second module is the Kernel simulation, which builds up a global simulation model according to the configuration module. In the third module, the user selects the scheduler algorithm. Finally the last module allows the execution of the simulation and present the results. The framework encompasses two modes: Manual and automatic. In manual mode the simulator uses the task set data provided in the first section. In automatic mode the task set is generated by parameterizing the integrated UUniFast algorithm

Thermal-aware real-time scheduling using timed continuous Petri Nets

We present a thermal-aware, hard real-time (HRT) global scheduler for a multiprocessor system designed upon three novel techinques. First, we present a modeling methodology based on Timed Continuous Petri nets (TCPN) that yields a complete state variable model, including job arrivals, CPU usage, power, and thermal behavior. The model is accurate and avoids the calibration stage of RC thermal models. Second, based on this model, a linear programming problem (LPP) determines the existence of a feasible HRT thermal-aware schedule. Last, a sliding-mode controller and an online discretization algorithm implement the global HRT scheduler, which is capable of managing thermal constraints, context switching, migrations, and disturbances

Identification of a Novel Pathogenic Rearrangement Variant of the APC Gene Associated with a Variable Spectrum of Familial Cancer

Familial adenomatous polyposis (FAP) is an autosomal-dominant condition characterized by the presence of multiple colorectal adenomas, caused by germline variants in the adenomatous polyposis coli (APC) gene. More than 300 germline variants have been characterized. The detection of novel variants is important to understand the mechanisms of pathophysiology. We identified a novel pathogenic germline variant using next-generation sequencing (NGS) in a proband patient. The variant is a complex rearrangement (c.422+1123_532-577 del ins 423-1933_423-1687 inv) that generates a complete deletion of exon 5 of the APC gene. To study the variant in other family members, we designed an endpoint PCR method followed by Sanger sequencing. The variant was identified in the proband patient’s mother, one daughter, her brother, two cousins, a niece, and a second nephew. In patients where the variant was identified, we found atypical clinical symptoms, including mandibular, ovarian, breast, pancreatic, and gastric cancer. Genetic counseling and cancer prevention strategies were provided for the family. According to the American College of Medical Genetics (ACMG) guidelines, this novel variant is considered a PVS1 variant (very strong evidence of pathogenicity), and it can be useful in association with clinical data for early surveillance and suitable treatment. View Full-Tex

Breast reconstruction: a review

Surgeons in the late 19th - 20th century performed radical mastectomies as the only possible treatment for breast cancers. Since then, the medical-surgical/scientific community has been constantly encouraged to develop and study different less invasive alternatives in breast reconstruction. Over time, locoregional perforator flap options have served as practical alternatives to implant-based reconstruction and abdominal flaps, especially in the setting of patients who have received radiation therapy or have a history of failed reconstruction, as they effectively fill the missing volume and respect the musculature of the donor site. Breast reconstruction using strategies with one of the different locoregional flaps can preserve the musculature and innervation of the post-mastectomy site, which manages to reduce possible adverse events. In addition to evaluating the anatomical characteristics of the defect and affected quadrant, it is essential to assess the patient's body constitution and the skills of the surgical team as well as microsurgery training when designing a reconstructive plan. Different research protocols should be developed in the study and development of new medical-surgical therapeutic alternatives; we suggest joint development with tissue engineering

Intentional replantation: case report

Intentional reimplantation is a procedure in which an intentional tooth extraction is performed followed by reinsertion of the extracted tooth. We present the case of a 50-year-old male patient who came to the consultation due to incrustation detachment in tooth #37, when performing the radiographic study an extensive apical lesion was observed in tooth #36 with a sinuous path and the presence of purulent exudate. The tooth #36 was extracted, apicoectomy, retro preparation and retrograde filling were carried out for later reimplantation, showing bone regeneration after one year of evolution

Endodontic regenerative treatment for internal radicular resorption using bio-ceramic material, case report

The internal resorption of the internal radicular conduct is a process than can be both physiological or pathological, being the osteoclasts, odontoclasts and dentinoclast responsible for said process. 49-year-old female patient, refers orthodontic treatment at age 20, attends a dental check-up due to pain when chewing. Dental organ (DO) #11 was diagnosed with internal root resorption and symptomatic, suppurative apical periodontitis. Treatment started performing an endodontic access and taking a conductometry reading with an apical foramen locator, using a precision hybrid instrumentation technique and applying hypochlorite irrigation, the intra-canal was medicated with chemically pure calcium hydroxide for 7 days. The canal obturation was repaired infiltrating a bio-ceramic material (BIO-C Sealer) followed by the placement of the single cone using a vertical condensation technique

Management of a ruptured epidural catheter, an anesthesiologist's dilemma: a case report

Epidural anesthesia is a widely used anesthetic technique in lower extremity surgeries although it is a relatively safe procedure, it can have complications, such as rupture of the epidural catheter. This is a 69-year-old male patient with a diagnosis of Wagner IV diabetic foot is presented, which was scheduled for left supracondylar amputation in which after epidural block, retention of the catheter tip in the epidural space at level L2-L3 was seen, so hemi laminectomy was performed in a second surgical stage in L2 and removal of the epidural catheter. Ideally a broken needle should be removed as soon as possible