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Gleaning programs organize volunteer gleaners to harvest a variety of leftover crops that are donated by farmers for the purpose of feeding food-insecure individuals. Thus, the gleaning process simultaneously reduces food waste and food insecurity. However, the operationalization of this process is challenging because gleaning relies on two uncertain sources of input: the food and labor supplies. The purpose of this paper is to help gleaning organizations increase the (value-weighted) volume of fresh food gleaned by better managing the uncertainties in the gleaning operation. We develop a model to capture the uncertainties in food and labor supplies and seek a dynamic volunteer-staffing policy that maximizes the payoff associated with the amount of food gleaned. The exact analysis of the staffing problem seems intractable. Therefore, we resort to an approximation in the heavy traffic regime. In that regime, we characterize the system dynamics of the multicrop gleaning operation and derive the optimal staffing policy in closed form. The optimal policy is a nested threshold policy that specifies the staffing level for each class of donation (i.e., a donation of a particular crop type and donation size). The policy depends on the number of available gleaners and the backlog of gleaning donations. A numerical study using data calibrated from a gleaning organization in the Boston area shows that the dynamic staffing policy we propose can recover approximately 10% of the volume lost when the gleaning organization uses a static policy. To achieve this improvement, no capital or major process changes would be required--only some small changes to the staffing level requests. History: An earlier version of this paper was circulated with the title 'Dynamic Staffing of Volunteer Gleaning Operations' and is available from SSRN: https://ssrn.com/abstract=2873250 or http://dx.doi.org/10.2139/ssrn.2873250. Funding: This work is supported by the Neubauer Family Foundation at the University of Chicago Booth School of Business. Supplemental Material: The online appendices are available at https://doi.org/10.1287/opre.2018.1792. Keywords: gleaning * volunteer * food bank * food waste * food insecurity * dynamic control, 1. Introduction The practice of gleaning combines two societal problems to create an elegant solution for both. Gleaning dates back to ancient times when landowners allowed the poor to gather [...]

This paper studies a multiclass queueing system with endogenous abandonments where congestion affects customers' abandonment behavior, 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. Class k customers receive a reward [r.sub.k] from service and incur a cost [c.sub.k] per period of waiting. Customers are forward looking and make wait or abandon decisions dynamically to maximize their expected discounted utilities. The queueing model takes the customers' abandonment time distribution as an input and studies the resulting virtual waiting time distribution. Because the multiclass queueing system is not amenable to exact analysis, we resort to an approximate analysis in the conventional heavy traffic limit (under the hazard rate scaling). Leveraging the so-called state-space collapse property, we provide a characterization of the system performance. Combining the results for the two models, we show that there exists a unique equilibrium in which the customers' abandonment time and the virtual waiting time for the various classes are consistent in the two models. Finally, we provide a computational scheme to calculate the equilibrium numerically and apply that using data from an Israeli bank call center. Supplemental Material: The online appendix is available at https://doi.org/10.1287/opre.2017.1638. Keywords: queueing systems * endogenous abandonments * heavy traffic, 1. Introduction Queueing models with abandonments have been studied extensively in the operations research literature from both the performance analysis and optimization perspectives; see Ward (2011) for a survey. In [...]

Abstract. We undertake an empirical study of the impact of delay announcements on callers' abandonment behavior and the performance of a call center with two priority classes. A Cox regression [...]

We consider a congestible system serving multiple classes of customers who differ in their delay sensitivity and valuation of service (or product). Customers are endowed with convex-concave delay cost functions. [...]

We consider the problem of designing an efficient system for allocating donated livers to patients waiting for transplantation. The trade-off between medical urgency and efficiency is at the heart of [...]

We consider a make-to-order system where customers are dynamically quoted lead times (and prices). Customers are homogenous but have general (nonlinear) disutility for delay. Because the firm is a monopolist, [...]

Endometriosis usually presents as cyclical pain in the pelvis but may also present as painful cutaneous lesions. Many diseases may mimic hidradenitis suppurativa (HS) since HS, a chronic inflammatory painful skin disease, is a clinical diagnosis. A 32-year-old woman presented with painful lumps on her vulva and groin accompanied with bloody discharge during menstruation. She was followed up with preliminary diagnosis of endometriosis. Previous excision without definitive diagnosis resulted in temporary relief. She was prescribed oral contraceptive pills that alleviated her symptoms but quitted due to headache. Surgical excision was performed for definitive diagnosis and therapeutic relief. Pathology report revealed HS. She was prescribed oral doxycycline. She responded well to the therapy and has symptom-free for the last 2 years. She delivered one healthy girl via cesarian section 2 years after the treatment. Endometriosis and HS should be included in the differential diagnosis when women present with menstrual painful lesions around external genitalia for diagnosis and treatment.

As a model of make-to-order production, we consider an admission control problem for a multiclass, single-server queue. The production system serves multiple demand streams, each having a rigid due-date lead [...]

A controller dynamically chooses a state-dependent transmission rate on a static, point-to-point wireless link by varying transmission power over time. The transmitter is modeled as a finite-buffer Markovian queue with [...]

As a chronic inflammatory disease, endometriosis generates fibrosis and anatomic distortion, which add extra-challenges to assisted reproductive technology cycles and requires a personalized approach. Patients with endometriomas have significantly decreased ovarian reserve and the ultrasound examination tends to be challenging, possibly underestimating follicle counts. It is crucial to assess the feasibility of oocyte retrieval procedure during the initial examination of the patient, as the distortion of the pelvic anatomy, the presence of hydrosalpinges and endometriomas might render the procedure difficult and increase the risk of complications. Possible injury to adjacent organs and risk of infection must be considered. Assisted reproductive technology seems to have limited or no impact on endometriosis recurrence, pain symptom progression or the size of endometrioma.

We performed a literature review of studies comparing the effectiveness of progestins in preventing premature ovulation during ovarian stimulation for assisted reproductive technology (ART). Five randomized trials and cohort studies involving a total of 2404 women, which compared; i) two different progestins or ii) two different doses of the same progestin were included. The primary outcome was live birth rate (LBR) per woman. Secondary outcomes were live birth or ongoing pregnancy (LB/OP) per woman and per embryo transfer (ET), ongoing pregnancy, clinical pregnancy, positive pregnancy test, numbers of oocytes and metaphase-two oocytes, duration of stimulation and gonadotropin consumption. The primary outcome was not reported in most studies however there were no differences between progestins for secondary outcomes. All progestins seem to effectively prevent premature ovulation in ART cycles. Low-quality evidence suggests that progestins can effectively prevent premature ovulation in ART cycles.

The use of power morcellation (PM) in abdominal and pelvic surgery has been discouraged and even banned in some institutions because of the risk of spreading malignant cells, although some authorities maintain that PM can be an appropriate tool for selected patients deemed to be at low risk of malignancy.

Three-dimensional ultrasound (3D USG) is a fast-evolving imaging technique that holds a great potential for use in gynecology. Its sensitivity and specificity is reported to be close to 100 % for diagnosing congenital uterine anomalies, comparable with those of magnetic resonance imaging (MRI) and laparoscopy. With 3D USG, a coronal view of the uterus can be obtained, clearly outlining the external contour of the uterus and providing accurate information about the shape of the cavity. Although 3D USG may not perform well in thin endometria, combining it with saline infusion sonography (SIS) overcomes this problem. Research shows that 3D USG is more sensitive and specific than two-dimensional ultrasound (2D USG) in defining and mapping uterine lesions, such as fibroids, adenomyosis, and intrauterine synechia. In cases of suspected malignancy, 3D USG is mainly used in the initial evaluation of patients. Measuring various indices and mapping vascular architecture with 3D power Doppler have been proposed for evaluating adnexal masses. Although some studies raised hope, no consensus is reached about its use, success, and limitations. In urogynecology, translabial 3D USG is proved to be a valuable tool, as it provides instant access to the axial plane, which clearly depicts the relationship of the vagina, urethra, rectum, and the muscular pelvic floor. Studies report no significant differences between translabial 3D USG and MRI measurements for evaluation of the pelvic floor. In conclusion, adding 3D USG to routine gynecological workup can be beneficial for clinicians, as it provides fast and accurate results in a relatively cost-effective setting.

We have developed a new oocyte collection technique applicable to use in women with “string-of-pearls” polycystic ovaries undergoing in vitro maturation (IVM) of oocytes for in vitro fertilization.

To evaluate the agreement between measurements of uterine septum by 3-D ultrasound (3-D US) and magnetic resonance imaging.

Do live birth rates (LBR), obstetric and perinatal outcomes vary between women who underwent frozen embryo transfer (ET) in the immediately subsequent menstrual cycle, and with those who underwent delayed frozen ET.

Simultaneous transfer of multiple embryos in an assisted reproductive technology (ART) cycle results in a high rate of multiple pregnancy. Besides the medical complications associated with multiple pregnancy, the financial burden of the resultant preterm infants is also substantial. The current review evaluates the costs associated with the care of preterm infants that are born as a result of ART-associated multiple pregnancies.

To give an overview of the economic aspects of assisted reproductive technologies (ART) and assess the implications of economic factors for utilization and practice of ART.

In vitro fertilization and embryo cryopreservation is regarded as the only established method for fertility preservation in female cancer patients. However, a possible delay in treatment of the primary disease due to ovarian stimulation, exposure to supraphysiologic estrogen levels induced by ovarian stimulation, the requirement for a male partner or willingness to use donor sperm for embryo production, legal, ethical, religious issues related to cryopreservation of embryos raise concerns for patients and physicians. Recent improvements achieved with oocyte vitrification have increased the effectiveness of oocyte cryopreservation rendering it a viable option, especially for patients without a male partner. In vitro maturation avoids treatment delay or exposure to increased estradiol levels associated with ovarian stimulation for in vitro fertilization. In vitro maturation combined with embryo or oocyte vitrification provides previously unavailable options for some patients and improves the services provided by a fertility preservation program.

To give an overview of the current status and future directions of blastocyst transfer and outcome with particular focus on markers of blastocyst quality and their relationship with implantation.

Animal models are necessary for research, technical developments, and training purposes in laparoscopic surgery. Although various operations on small animals have been described, there is still a need for a simple and practical laparoscopic small animal model. We acknowledged truncal vagotomy as a simple procedure, and aimed to develop a model of laparoscopic truncal vagotomy (LTV) in the rat, an inexpensive and easily available animal. Fifty Wistar rats were randomized into an LTV group (n= 25) and an open truncal vagotomy (OTV) group (n= 25). LTV was effected with two minitrocars inserted into the left upper and right lower quadrants. Two techniques of vagotomy were developed: first, with the esophagus in its anatomical position, and second, with the distal esophagus retracted anteriorly with a grasper inserted into the retroesophageal space. OTV was performed through a midline incision. Animals were sacrificed 24 h post-operatively, and autopsy was performed. The mean ± SD operating time was 8.3 ± 1.4 min in the LTV group and 5.5 ± 0.2 min in the OTV group (P< 0.05). The laparoscopically magnified view provided a better distinction of vagal fibers compared with open surgery, with the second laparoscopic technique providing the best exposure. Complications developed in three rats (12%) from the LTV group and one (4%) from the OTV group (P> 0.05). Vagotomy was confirmed to be complete at autopsy in all of the animals. This is the first technical description of laparoscopic peptic ulcer surgery in the rat. Although subsequent histopathological and physiological studies may be required, technically, laparoscopic vagotomy in the rat seems to be a simple, inexpensive, and expeditious small-animal model for laparoscopic research.