The effects of random and seasonal environmental fluctuations on optimal harvesting and stocking.

We analyze the harvesting and stocking of a population that is affected by random and seasonal environmental fluctuations. The main novelty comes from having three layers of environmental fluctuations. The first layer is due to the environment switching at random times between different environmental states. This is similar to having sudden environmental changes or catastrophes. The second layer is due to seasonal variation, where there is a significant change in the dynamics between seasons. Finally, the third layer is due to the constant presence of environmental stochasticity-between the seasonal or random regime switches, the species is affected by fluctuations which can be modelled by white noise. This framework is more realistic because it can capture both significant random and deterministic environmental shifts as well as small and frequent fluctuations in abiotic factors. Our framework also allows for the price or cost of harvesting to change deterministically and stochastically, something that is more realistic from an economic point of view. The combined effects of seasonal and random fluctuations make it impossible to find the optimal harvesting-stocking strategy analytically. We get around this roadblock by developing rigorous numerical approximations and proving that they converge to the optimal harvesting-stocking strategy. We apply our methods to multiple population models and explore how prices, or costs, and environmental fluctuations influence the optimal harvesting-stocking strategy. We show that in many situations the optimal way of harvesting and stocking is not of threshold type.

Twenty Years of Antireflux Surgery. Retrospective of a Laparoscopic Surgery Center.

Introduction: Non-oncological pathology of the esogastric junction (EGJ) is an area of interdisciplinary interest for many practitioners (endoscopist, gastroenterologist, surgeon, radiologist). This is due to the increased incidence of esogastric junction benign pathology, especially gastroesophageal reflux disease (GERD), currently considered the disease of the 21st century. The overall incidence of GERD is increasing annually. Meta-analyses show the prevalence of this pathology in Western countries of about 10-20%, compared to Asian countries where it is below 10%, in North America of 27.8%, and 25.9% in Europe (1,2,3). Material and Methods: The experience of our department in antireflux surgery represents 20 years (2002-2021) of activity, during this time 768 antireflux interventions were performed for GERD and hiatal hernias (HH). Patients selected for antireflux surgery initially underwent conservative treatment in accordance with applicable international protocols. Approximately 40% of all patients were unwilling to undergo conservative antireflux treatment, and these data are in line with the world literature statistic (4). Moreover, the symptoms of gastroesophageal reflux disease in 24.2% of cases appeared one month after the end of conservative treatment, and in 35.8% after 6 months. Results: The type of antireflux surgery in this period of activity was different and depended on the situation: the individual characteristics of the patient, different approaches to surgical techniques over different periods of time. Laparoscopic antireflux operations predominate in the majority of patients (96.6%) in the last 10 years, compared to previous years, where the rate of traditional interventions was 15-20. The complete fundoplication Nissen-Rossetti, due to the good control of GERD, has become an intervention of choice mainly for patients with GERD. Conclusions: 1. Early diagnosis of refractory forms to medical treatment requires referral of patients to laparoscopic antireflux surgery to avoid severe complications of GERD. 2. The minimally invasive approach to antireflux surgery today is a golden standard, and the use of a complete fundoplication ensures the high effectiveness of these interventions.

Asymptotic harvesting of populations in random environments.

We consider the harvesting of a population in a stochastic environment whose dynamics in the absence of harvesting is described by a one dimensional diffusion. Using ergodic optimal control, we find the optimal harvesting strategy which maximizes the asymptotic yield of harvested individuals. To our knowledge, ergodic optimal control has not been used before to study harvesting strategies. However, it is a natural framework because the optimal harvesting strategy will never be such that the population is harvested to extinction-instead the harvested population converges to a unique invariant probability measure. When the yield function is the identity, we show that the optimal strategy has a bang-bang property: there exists a threshold [Formula: see text] such that whenever the population is under the threshold the harvesting rate must be zero, whereas when the population is above the threshold the harvesting rate must be at the upper limit. We provide upper and lower bounds on the maximal asymptotic yield, and explore via numerical simulations how the harvesting threshold and the maximal asymptotic yield change with the growth rate, maximal harvesting rate, or the competition rate. We also show that, if the yield function is [Formula: see text] and strictly concave, then the optimal harvesting strategy is continuous, whereas when the yield function is convex the optimal strategy is of bang-bang type. This shows that one cannot always expect bang-bang type optimal controls.

Electrical Stimulation as an Alternative Treatment in Gastroesophageal Reflux Disease - Clinical Study.

Background: Recently, there was described the possibility to increase the lower esophageal sphincter (LES) tone by means of implantable electrical stimulator. Although, this method has already been used in clinical practice, however, the optimal parameters of LES electrical stimulation are still unknown. Aims: The goals of this study were to get clinical data regarding the effects of different types of electrical stimulation on LES and to elaborate and test the prototype on laboratory animals. Material and Methods: In the Department of Surgery no 4, during 4 years (2015-2018), there has been achieved one clinical-experimental study of LES electrical stimulation. During the first stage, the electrical stimulation of the LES, using an external pulse generator, was assessed in 15 patients. These patients underwent an antireflux intervention, with an additional insertion of 2 temporary electrodes on the LES. During the second stage, there was created an experimental device which consisted of a re-insertable microstimulator using wireless energy transfer. During the third stage, it was tested in the experimental surgery center "Pius Branzeu", Timisoara, on laboratory animals (pigs). Results: Values of the LES resting pressure and integrated relaxation pressure (IRP) were significantly different during the prestimulation and poststimulation periods. Conclusions: There was successfully demonstrated the possibility to increase the LES tone. Modifications in the LES functionality and tone, during the electrical stimulation and in the period immediately after the stimulation, depend upon the pulse frequency and length. Also, the additional change of the Bluetooth transmitter antenna is necessary to offset the screening effect of the biological tissues.

MEN 2A syndrome - Multiple endocrine neoplasia with autosomal dominant transmission.

INTRODUCTION: Multiple endocrine neoplasias (MEN) are rare inherited syndromes. MEN type 2 syndromes occur in 1:30000 individuals, and are reported in approximately 500-1000 families worldwide, the most frequent being MEN 2A (80%), followed by familial medullary thyroid carcinoma (15%) and MEN 2B (5%) (Marx and Wells, 2011; Dumitrache, 2012). CASE: The patient, a 20-years old with MEN 2A syndrome, which has been manifested by bilateral pheochromocytoma and medullary thyroid carcinoma. It was a familial form, having first degree relatives (mother) with pheochromocytoma. The patient underwent laparoscopic adrenalectomy on her left in 2015, laparoscopic adrenalectomy on the right in 2019 and total thyroidectomy in 2020 year. The postoperative evolution of this patient is favorable. She is satisfied with the received treatment and is being supervised by an endocrinologist, undergoing hormone replacement therapy. CONCLUSIONS: The case demonstrates the importance of the radical approach to MEN 2A syndrome from both a therapeutic and surgical point of view. If a pheochromocytoma is detected, adrenalectomy should be performed before thyroidectomy or other surgery to avoid intraoperative catecholamine release. Laparoscopy is the choice of approach in surgical treatment. Limitations only arise because of technical difficulties or tumor size.

HPV pathway profiling: HPV related cervical dysplasia and carcinoma studies.

Cervical cancer is the second most common malignancy among women worldwide. While more than 90% of cervical cancers carry one or more high risk HPV types, the exact relationship between HPV oncoproteins and signaling pathways alterations in cervical cancer remains to be clarified. Vaccines and targeted therapies are today considered of great potential for the improvement of patients' outcome. This review will focus on the interaction of HPV with cervical cancer pathway activations. Next generation high throughput screening technologies for molecular and protein profiling as well as innovative logistics, necessary for the implementation of the personalized care of cervical cancer patients will be discussed.

Comparison of 400 mcg buccal and 400 mcg sublingual misoprostol after mifepristone medical abortion through 63 days' LMP: a randomized controlled trial.

BACKGROUND: Buccal misoprostol 800 mcg and sublingual misoprostol 400 mcg demonstrate high efficacy and few adverse effects when used with 200 mg mifepristone for medical abortion through 63 days since the last menstrual period (LMP). Little is known about a 400-mcg buccal dose. This study compares two in-the-mouth routes of misoprostol using the same dose. STUDY DESIGN: Eligible and consenting women (n=550) were randomized to 400 mcg of misoprostol buccally or sublingually 24 h after ingestion of 200 mg of mifepristone. Abortion status was assessed 2 weeks later. RESULTS: Complete abortion occurred in 97.1% of the buccal group and 97.4% of the sublingual group (p=.97, RR: 1.00, 95% CI=0.97-1.03). Adverse effects were similar in both groups. Over 90% of women in both arms expressed high satisfaction with the method. CONCLUSIONS: Both 400 mcg buccal misoprostol and 400 mcg sublingual misoprostol after mifepristone appear to be good options for medical abortion through 63 days' LMP.

Two-pill regimens of misoprostol after mifepristone medical abortion through 63 days' gestational age: a randomized controlled trial of sublingual and oral misoprostol.

BACKGROUND: A 400 mcg dose of sublingual misoprostol has high efficacy and few side effects when used with 200 mg mifepristone for medical abortion through 63 days' gestation. STUDY DESIGN: Eligible and consenting women (n=480) were randomized to 400 mcg of misoprostol sublingually or orally, 24 h after 200 mg of mifepristone. Abortion status was assessed two weeks later. RESULTS: Complete abortion occurred in 98.7% of the sublingual group and 94.0% of the oral group (p value=.006, RR: 1.05, 95% CI=1.01--1.09). Over 90% of women in both arms expressed high satisfaction with the method. Side effects were similar in both groups, with only fever or chills reported by significantly more women in the sublingual arm. CONCLUSIONS: The sublingual route appears superior to the regimen of 400 mcg misoprostol used orally and may be a good option for mifepristone medical abortion.