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A system manager makes dynamic pricing and dispatch control decisions in a queueing network model motivated by ride hailing applications. A novel feature of the model is that it incorporates travel times. Unfortunately, this renders the exact analysis of the problem intractable. Therefore, we study this problem in the heavy traffic regime. Under the assumptions of complete resource pooling and common travel time and routing distributions, we solve the problem in closed form by analyzing the corresponding Bellman equation. Using this solution, we propose a policy for the queueing system and illustrate its effectiveness in a simulation study. [ABSTRACT FROM AUTHOR]

This paper studies a diffusion control problem motivated by challenges faced by public health agencies who run clinics to serve the public. A key challenge for these agencies is to motivate individuals to participate in the services provided. They must manage the flow of (voluntary) participants so that the clinic capacity is highly utilized, but not overwhelmed. The organization can deploy costly promotion activities to increase the inflow of participants. Ideally, the system manager would like to have enough participants waiting in a queue to serve as many individuals as possible and efficiently use clinic capacity. However, if too many participants sign up, resulting in a long wait, participants may become irritated and hesitate to participate again in future. We develop a diffusion model of managing participant inflow mechanisms. Each mechanism corresponds to choosing a particular drift rate parameter for the diffusion model. The system manager seeks to balance three different costs optimally: (i) a linear holding cost that captures the congestion concerns, (ii) an idleness penalty corresponding to wasted clinic capacity and negative impact on public health, and (iii) costs of promotion activities. We show that a nested-threshold policy for deployment of participant inflow mechanisms is optimal under the long-run average cost criterion. In this policy, the system manager progressively deploys mechanisms in increasing order of cost, as the number of participants in the queue decreases. We derive explicit formulas for the queue length thresholds that trigger each promotion activity, providing the system manager with guidance on when to use each mechanism. [ABSTRACT FROM AUTHOR]

Motivated by applications in queueing theory, we consider a class of singular stochastic control problems whose state space is the d-dimensional positive orthant. The original problem is approximated by a drift control problem, to which we apply a recently developed computational method that is feasible for dimensions up to d=30\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$d=30$$\end{document} or more. To show that nearly optimal solutions are obtainable using this method, we present computational results for a variety of examples, including queueing network examples that have appeared previously in the literature. [ABSTRACT FROM AUTHOR]

In this paper, a decoupled backstepping sliding mode control method is proposed to control underactuated systems under uncertainties and disturbances. The sliding mode control technique and the backstepping control technique are combined owing to their merits. Since the design methodology is based on the Lyapunov theorem, the stability of the system is guaranteed. The effectiveness of the proposed method is verified by the experimental results of the controller which is applied to a nonlinear, underactuated inverted pendulum system. The experimental results show that the decoupled backstepping sliding mode control achieves a satisfactory control performance rather than the decoupled sliding mode controller and the proposed method provides a robust performance to overcome parametric uncertainties where the decoupled sliding mode control fails. [ABSTRACT FROM AUTHOR]

This paper studies a Geo/Geo/1 $$+GI$$ queue in which the abandonments are endogenous. One crucial feature of this model is that the abandonment behavior is affected by the system performance and vice versa. Our model captures this interaction by developing two closely related models: an abandonment model and a queueing model. In the abandonment model, customers take the virtual waiting time distribution as given. They receive a reward r from service and incur a cost c per period of waiting. Customers are forward-looking and maximize their expected discounted utilities by making wait or abandon decisions dynamically as they wait in the queue. The queueing model takes the customers' abandonment time distribution as an input and studies the resulting virtual waiting time distribution. In equilibrium, the customers' abandonment behavior and the system performance must be consistent across the two models. Therefore, combining the two models and imposing this consistency requirement, we show that there exists a unique equilibrium. Lastly, we provide a computational scheme to calculate the equilibrium numerically. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to provide an overview of the studies investigating a possible association between thrombophilia and assisted reproductive technology (ART) outcome. Methods: This is a literature review. Results: Congenital thrombophilias (CoT) are reported to be associated with pregnancy loss. However, the association between CoT and early pregnancy loss is weak and does not necessarily support causation. CoT are more likely to be associated with late fetal loss. Even though data pooled from case-control and cohort studies suggest an increased risk of ART failure in women with CoTs, there seems no association when the analysis is confined to better quality cohort studies. The evidence supporting anticoagulation to improve ART outcome in CoT carriers is weak. Likewise, studies on antiphospholipid antibodies (APAs) and ART outcome suffer from multiple methodological limitations and a detrimental impact of APA positivity is controversial. Empirical administration of heparin or low molecular weight heparin to women with recurrent ART failures is supported by weak evidence. Importantly, thrombophilias are likely to increase thrombotic complications after ovarian stimulation for ART. Conclusions: Current evidence does not support routinely testing for or treatment of thrombophilia in the setting of ART nor in couples with implantation failure. A careful personal and family history should be obtained and a risk assessment for thrombotic complications should be made in every woman undergoing ovarian stimulation. If positive, testing for thrombophilia is warranted. [ABSTRACT FROM AUTHOR]

Dysbiosis in the genital tract or gut microbiome can be associated with endometriosis. We sampled vaginal, cervical and gut microbiota from 14 women with histology proven stage 3/4 endometriosis and 14 healthy controls. The V3 and V4 regions of the 16S rRNA gene were amplified following the 16S Metagenomic Sequencing Library Preparation. Despite overall similar vaginal, cervical and intestinal microbiota composition between stage 3/4 endometriosis group and controls, we observed differences at genus level. The complete absence of Atopobium in the vaginal and cervical microbiota of the stage 3/4 endometriosis group was noteworthy. In the cervical microbiota, Gardnerella, Streptococcus, Escherichia, Shigella, and Ureoplasma, all of which contain potentially pathogenic species, were increased in stage 3/4 endometriosis. More women in the stage 3/4 endometriosis group had Shigella/Escherichia dominant stool microbiome. Further studies can clarify whether the association is causal, and whether dysbiosis leads to endometriosis or endometriosis leads to dysbiosis. [ABSTRACT FROM AUTHOR]

To evaluate the expectations, experiences, and fertility awareness status of women who underwent social oocyte cryopreservation. Cohort survey study was conducted at an academic medical center. All women who underwent social oocyte cryopreservation between January 2015 and June 2016 were recruited. One hundred thirty-three women were contacted by phone to participate in a survey. The questionnaire investigated the initial motivation towards freezing, intentions to use cryopreserved oocytes, treatment experience, awareness of fertility and knowledge about chances of having a live birth with their frozen oocytes. The mean age at the time of oocyte freezing was 38.5 ± 2.68 years. The average number of mature oocytes cryopreserved was 5.48 ± 6.6 (1–16). Two major motivations were absence of a male partner (40%) and an anticipated age-related fertility decline (42%). Almost 60% overestimated the chances of natural conception, as well as the success of IVF at the age of 40 years. Half of the oocyte bankers reported that fertility declined between ages 35 and 39, but only 28% of patients estimated the live birth rate per cryopreserved oocyte correctly. Overall 98.8% stated that they would recommend oocyte cryopresevation to a friend, and 72% felt more secure in terms of reproductive potential. Despite comprehensive personalized counseling prior to the start of ovarian stimulation, many women do not seem to have a realistic understanding of reproductive aging. Even though gamete cryopreservation provides some insurance, overestimating the effectiveness of oocyte cryopreservation can also lead to a false sense of security. Clinical Trial Registration: 2016.086.IRB1.006 [ABSTRACT FROM AUTHOR]

We aimed to answer one key question, that was not previously addressed as to whether serum progesterone (P4-hCG day) and its co-variates (estradiol (E2-hCG day) and the number of retrieved oocytes) of a given cycle can be predictive of the subsequent cycle when both cycles are consecutive and comparable for the stimulation protocol, gonadotropin dose and duration of stimulation. We analyzed such 244 consecutive (< 6 months) IVF cycles in 122 patients with GnRH agonist long protocol and found that P4, E2 and the number of retrieved oocytes significantly vary between the two cycles. Although P4 increased (ranging from 4.7 to 266.7%) in the 2nd cycle in 61 patients, E2 and the number of retrieved oocytes, which are normally positively correlated with P4 paradoxically decreased in the 41% and 37.7% respectively, of these same 61 patients. When a similar analysis was done in the 54 out of 122 patients (44.3%) in whom serum P4 was decreased in the 2nd cycle, the mean decrease in P4 was − 34.1 ± 23.3% ranging from − 5.26 to − 90.1%. E2 and the number of retrieved oocytes paradoxically increased in the 42.3% and 40.7% of these 54 patients respectively. P4 remained the same only in the 7 (5.7%) of these 122 patients. These findings indicate that late follicular phase serum P4 may change unpredictably in the subsequent IVF cycle. The changes are not always necessarily proportional with ovarian response of previous cycle suggesting that growth characteristics and steroidogenic activities of antral cohorts may exhibit considerable cycle to cycle variations. [ABSTRACT FROM AUTHOR]

Introduction and hypothesis: Mesh-related problems are significant complications of laparoscopic sacral colpopexy. The conventional technique precludes performing laparoscopic sacral colpopexy without using a mesh. We describe the Ozerkan modification for laparoscopic sacral colpopexy using a polyester fiber suture instead of a standard mesh and report 1-year objective and subjective outcomes. Methods: Women diagnosed with stage ≥ 2 vaginal vault prolapse were prospectively recruited for the Ozerkan modification between 2015 and 2017. The primary outcome was the anatomic success of the repair, defined by objective parameters using the pelvic organ prolapse quantification system (stage 0 or 1). Secondary outcomes were subjective outcomes assessed with the quality of life scores. Results: Twenty-two women underwent the Ozerkan modified laparoscopic sacrocolpopexy. Mean operation time was 85.6 min. Mean estimated blood loss was 71 ml. One patient was lost during the clinical follow-up in the outpatient clinic up to 1 year. Nineteen of 21 patients had stage 0 or 1 prolapse at the end of 1 year. Two patients were not satisfied with their pelvic floor after 1 year. Both the objective and subjective cure rates were 90.4%. There were no bladder or bowel complications during the peri- or postoperative period. Conclusions: The new modification of laparoscopic sacral colpopexy seems a feasible and safe option to avoid mesh complications in the treatment of vaginal vault prolapse. [ABSTRACT FROM AUTHOR]

Objective: A systematic review and meta-analysis was conducted to investigate whether gonadotropin-releasing hormone analogs (GnRHa) have a protective role in women treated with alkylating agents. Data Sources: Major databases (PubMED, EMBASE, Cochrane Central Register of Controlled Trials), systematic snowballing, and trial registries were screened from the inception dates until September 2017. Methods and Study Selection: Comparative studies involving reproductive-aged women undergoing chemotherapy with or without coadministration of GnRHa were included. Spontaneous menstrual resumption was assessed as a main outcome. Statistical analyses were performed with STATA 14.2 statistical software. Effect estimates were presented as risk ratios (RR) with 95% confidence intervals (CIs). Results: The literature search yielded 25 436 citations and 84 papers were assessed in full text. Eighteen studies (11 randomized controlled trials [RCTs] and 7 cohort studies) published between 1987 and 2015 were included in the analysis, revealing a significant protective effect of GnRHa (n = 1043; RR:1.38; 95% CI: 1.18-1.63) although with high heterogeneity (I2 = 83.3%). Subgroup analyses revealed a significant benefit of GnRHa cotreatment both in RCTs and in cohort studies. Statistical significance was found in all subgroups by the underlying disease, that is, hematological malignancies, autoimmune diseases, and breast cancer. Sensitivity analyses in GnRH agonist-treated patients, in patients younger than 40 years old, and in patients without supradiaphragmatic radiotherapy also revealed a significant benefit of GnRHa cotreatment. Conclusion: Our results indicate that concurrent GnRHa administration is an effective method to decrease gonadotoxicity of alkylating agents. The presence of low-quality evidence favoring gonadoprotective effect requires a strong recommendation for offering GnRHa coadministration to young women who are to undergo gonadotoxic chemotherapy. Capsule: The present systematic review and meta-analysis shows a significant gonadoprotective effect of gonadotropin-releasing hormone analogs in women treated with alkylating agents. [ABSTRACT FROM AUTHOR]

Objective: In vitro maturation (IVM) of human oocytes can be an alternative treatment option to conventional in vitro fertilization. Women with polycystic ovary syndrome (PCOS) are considered the classical candidates for IVM because of the associated ovarian morphology and because IVM diminishes the risk of developing ovarian hyperstimulation syndrome. The objective of this study was to identify predictive factors for live birth in a cohort of women with PCOS who underwent IVM.Methods: This retrospective study included 159 patients with PCOS who had IVM cycles in which single or double embryo transfer was performed. The IVM protocol included three days of gonadotropin ovarian stimulation and hCG priming when the leading follicle size was 10-12 mm. Collected cumulus-oocyte complexes were cultured for 24 h for maturation. Intracytoplasmic sperm injection (ICSI) was used for fertilization. Embryo transfer was performed two days after fertilization. Demographic and clinical parameters were analyzed with logistic regression to identify predictors for live birth.Results: The women's mean age was 27.4 years, the mean number of retrieved oocytes was 14, and the live birth rate was 34.6%. The logistic regression revealed the following significant factors for live birth: infertility duration (OR 0.9; 95% CI, 0.82-0.98), number of collected oocytes (OR 1.56; 95% CI, 1.01-3.2), embryo cell number (OR 2.1; 95% CI, 1.4-3.5), and embryo grade (OR 1.84; 95% CI, 1.13-4.2).Conclusion: Infertility duration, oocyte number, embryo cell number, and embryo grade were the most significant predictors for live birth after IVM in PCOS patients. These prognostic factors can be used when planning treatment or counselling patients. [ABSTRACT FROM AUTHOR]