Michael J. Moses

Policy mechanisms for supply chain coordination

The problem is to determine a review period and stocking policy that are mutually beneficial to a producer and a retailer. In our model, the retailer uses a periodic review, base stock policy for ordering the item from the producers Distribution Center (DC). Excess customer demand is assumed to be lost. A make-to-order production system supplies to the DC. We show that given a review period, unless the manufacturer agrees to share the cost of carrying a fraction of the safety stocks at the retailer, the two will not agree upon the level of stocks to be carried in the store. We prove that there is an equilibrium value for this fraction, such that the retailer and the manufacturer are always in agreement with regard to the stocking level. We then show that complete coordination on the stocking level as well as the review period can be achieved solely through carrying out negotiations on credit terms. These theoretical results are used to construct an algorithm for calculating the optimal policy parameters for a supply chain. As part of the analysis we suggest a modification of the base stock policy for the positive lag lost sales case of periodic review inventory models that consistently outperforms the base stock policy in our numerical studies.

Hemodynamic effects of intrathecal fentanyl in nonlaboring term parturients

STUDY OBJECTIVE To determine the effect of intrathecal fentanyl on maternal hemodynamics. DESIGN Prospective. SETTING Labor and delivery suite of a university medical center. PATIENTS 23 ASA status I nonlaboring term parturients presenting for elective cesarean section. INTERVENTIONS Patients were given either 1,200 ml lactated Ringers Solution (Group 1, n = 12) or no intravenous (i.v.) fluid (Group 2, n = 11). A combined spinal-epidural technique was then performed. Fentanyl 25 micrograms was administered intrathecally through a 24-gauge Sprotte or 25-gauge Whitacre spinal needle. After completion of the hemodynamic study, a catheter was threaded into the epidural space for local anesthetic administration. MEASUREMENTS AND MAIN RESULTS Baseline hemodynamic data [systolic (SBP), diastolic, and mean arterial pressure, heart rate, stroke volume, cardiac output, end-diastolic volume, and ejection fraction] were obtained in triplicate using noninvasive blood pressure monitoring and impedance cardiography. After administration of intrathecal fentanyl, hemodynamic measurements were recorded at 3-minute intervals for 30 minutes. These values were compared with baseline for both groups. Ten patients in each group completed the study. Intrathecal fentanyl administration did not result in any maternal hemodynamic changes in Group 1, and a few small statistically significant changes in Group 2. Measured SBP was always greater than 100 mmHg in all patients during the study. CONCLUSION Intrathecal administration of fentanyl 25 micrograms in nonlaboring term parturients does not produce clinically important maternal hemodynamic changes.

Chapter 27 The Computation of Prices Indices

Abstract While there are no significant investment characteristics that inhibit art from being considered as an asset, a major hurdle has long been the lack of a systematic measure of its financial performance. Due to its heterogeneity (each piece is different) and its infrequency of trading (the exact same piece does not come to the market very often), the determination of changes in market value is difficult to ascertain. Two estimation methods are commonly used to construct indices. Repeat-sales regression (RSR) uses prices of individual objects traded at two distinct moments in time. If the characteristics of an object do not change (which is usually so for collectibles), the heterogeneity issue is bypassed. The basic idea of the hedonic regression (HR) method is to regress prices on various attributes of objects (dimensions, artist, subject matter, etc.) and to use the residuals of the regression which can be considered as “characteristic-free prices” to compute the price index. The chapter deals with the basics of hedonic and repeat-sales estimators, and tries to interpret in economic terms what both are trying to achieve. It also goes into some more technical details which may be useful for researchers who want to construct such indices, and gives some guidelines on how to go about collecting data, and the choice between RSR and HR that this induces. Both methods are compared using simulated returns, pointing to which method should be used given the data at hand.

Clinical outcomes following surgically repaired bucket-handle meniscus tears

ABSTRACT Objectives: Meniscus tears are one of the most common knee injuries. Our goal is to investigate the failure rate for surgically repaired bucket-handle meniscus tears and compare clinical outcomes of repairs that failed versus those that did not, at a minimum 2-year follow-up interval. Methods: 51 patients were identified in this retrospective cohort study who experienced bucket-handle meniscus tears that were isolated or with concomitant ACL injury. Inclusion criteria included age range from 13–55 years, confirmed bucket-handle meniscus tear by MRI and intraoperatively, and at least two-years of post-operative follow-up following index repair. Demographic data and outcome surveys were collected at a minimum of two-years follow-up after repair. Results: Of the 51 patients that had a bucket-handle meniscal repair, 12 (23.5%) were defined as failures (return of symptoms alongside re-tear in the same zone of the repaired meniscus within two years of surgery). No demographic variables (age, sex, and BMI smoking status, location of tear, or concomitant ACL tear) significantly correlated with failure. The mean of the Sports and Recreation KOOS was significantly lower between the non-failure (87 ± 14.4) and failure (70 ± 17.2) cohorts (p = 0.0072). The Quality of Life subscale was significantly lower between the non-failure (76 ± 15.8) and failure (57 ± 18.2) groups (p = 0.0058). There was a significant difference in the post-operative Lysholm scores (p = 0.0039) with a mean of 90 ± 9.1 for the entire cohort and means of 92 ± 8.4 and 83 ± 8.6, for non-failure and failure groups, respectively. Conclusions: We found a higher failure rate (23.5%) for bucket-handle meniscus repairs at two-year follow up than has been cited in the literature, which is typically less than 20%, with significantly lower KOOS Quality of Life and Sports and Recreation subscales and Lysholm scores for the failure cohort. This is the first study to report these outcome scores solely for bucket-handle meniscus repairs, shedding light on the post-operative quality of life of patients with repair success or failure.

3D transesophageal echocardiography and radiography of mitral valve prostheses and repairs

This paper provides a comprehensive overview of 3D transesophageal echocardiography still images and movies of mechanical mitral valves, mitral bioprostheses, and mitral valve repairs. Alongside these visual descriptions, the historical overview of surgical and percutaneous mitral valve intervention is described with the special emphasis on the incremental value of 3D transesophageal echocardiography (3DTEE). For each mitral valve intervention, 2D echocardiography, chest x‐ray, and fluoroscopy images corresponding to 3DTEE are given. In addition, key references on echocardiographic imaging of individual valves and procedures are enumerated in accompanying figures and tables.

T1 Slope Minus Cervical Lordosis (TS-CL), the Cervical Answer to PI-LL, Defines Cervical Sagittal Deformity in Patients Undergoing Thoracolumbar Osteotomy

ABSTRACT Background: Cervical kyphosis and C2-C7 plumb line (CPL) are established descriptors of cervical sagittal deformity (CSD). Reciprocal changes in these parameters have been demonstrated in thoracolumbar deformity correction. The purpose of this study was to investigate the development of CSD, using T1 slope minus cervical lordosis (TS-CL) to define CSD and to correlate TS-CL and a novel global sagittal parameter, cervical-thoracic pelvic angle (CTPA), with CPL. Methods: A multicenter, retrospective analysis of patients with thoracolumbar deformity undergoing three-column osteotomy was performed. Preoperative and postoperative cervical parameters were investigated. Linear regression for postoperative values resulted in a CPL of 4 cm corresponding to a TS-CL threshold of 17°. Patients were classified based on postoperative TS-CL into uncompensated (TS-CL > 17°) or compensated cohorts (TS-CL < 17°); the two were compared using an unpaired t test. Logistic regression modeling was used to determine predictors of postoperative CSD. Results: A total of 223 patients with thoracolumbar deformity (mean age, 57.56 years) were identified. CTPA correlated with CPL (preoperative r = .85, postoperative r = .69). TS-CL correlated with CTPA (preoperative r = .52, postoperative r = .37) and CPL (preoperative r = .52; postoperative r = .37). CSD had greater preoperative CPL (P < .001) and CTPA (P < .001). The compensated cohort had a decrease in TS-CL (from 10.2 to 8.0) with sagittal vertical axis (SVA) correction, whereas the uncompensated had an increase in TS-CL (from 22.3 to 26.8) with all P < .001. Reciprocal change was demonstrated in the compensated group given that CL decreased with SVA correction (r = .39), but there was no such correlation in the uncompensated. Positive predictors of postoperative CSD included baseline TS-CL > 17° (P = .007), longer fusion (P = .033), and baseline CTPA (P = .029). Conclusions: TS-CL and CTPA correlated significantly with established sagittal balance measures. Whereas reciprocal change in cervical and thoracolumbar alignment was demonstrated in the compensated cohort, the uncompensated population had progression of their cervical deformities after three-column osteotomy. Clinical Relevance: The balance between TS-CL mirrors the relationship between pelvic incidence minus lumbar lordosis in defining deformities of their respective spinal regions.

Case Report: Double Oberlin Nerve Transfer to Restore Elbow Flexion Following C5-C6 Avulsion Injury

BACKGROUND AND IMPORTANCE The use of nerve transfers to restore nerve function following traumatic avulsion injuries has been described, though there is still a paucity in the literature documenting technique and long-term outcomes for these procedures. The double Oberlin nerve transfer involves transferring fascicles from the median and ulnar nerves to the musculocutaneous nerve to restore elbow flexion in patients with a C5-C6 avulsion injury. The purpose of this case report is to present our indications and technique for a double Oberlin transfer in addition to exhibiting video footage at follow-up time points documenting the incremental improvement in elbow flexion following the injury. CLINICAL PRESENTATION The patient is a 25-yr old, left-hand dominant male who presented 5 mo following a motor vehicle accident. He had 0/5 biceps muscle strength on the left with a computed tomography myelogram that demonstrated pseudomeningoceles from C2-C3 to C7-T1 with root avulsions of C5 and C6. He was subsequently indicated for a double Oberlin nerve transfer to restore elbow flexion. CONCLUSION In this case report, we present our technique and outcomes for a double Oberlin transfer with restoration of elbow flexion at 1-yr follow-up for a patient with traumatic brachial plexus injury. We believe that the double Oberlin transfer serves as a safe and effective method to restore elbow flexion in this patient population.