A Pedagogical Exercise in Concept Integration: Or Relaxing Assumptions and Moving Toward the Real World

This article suggests to the educator an example of combining conceptual notions that should be familiar to students of business. In addition the example, which combines the notions of economic lot size and the learning curve, serves as a means for dealing with those critical of the many assumptions that often precede model building. This exercise or ones similar to it should give critics and/or students some appreciation of the complexities which are unveiled as we attempt to model closer to real-world applications

Combining the Learning Curve Concept with Economic Lot Sizing

Simple concepts familiar to most operations management students are frequently not integrated as a result of the complexity generated by their combination. This expository note demonstrates a method for combining the economic lot size concept with the learning curve and using a simple computer algorithm for solution purposes. It avoids the traditional trade-off of reality and accuracy for expediency

Kinematic Masses of Super Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy

Using high-resolution (R~22,000) near-infrared (1.51 -- 1.75 microns) spectra from Keck Observatory, we measure the kinematic masses of two super star clusters in M82. Cross-correlation of the spectra with template spectra of cool evolved stars gives stellar velocity dispersions of sigma_r=15.9 +/- 0.8 km/s for MGG-9 and sigma_r=11.4 +/- 0.8 km/s for MGG-11. The cluster spectra are dominated by the light of red supergiants, and correlate most closely with template supergiants of spectral types M0 and M4.5. We fit King models to the observed profiles of the clusters in archival HST/NICMOS images to measure the half-light radii. Applying the virial theorem, we determine masses of 1.5 +/- 0.3 x 10^6 M_sun for MGG-9 and 3.5 +/- 0.7 x 10^5 M_sun for MGG-11. Population synthesis modelling suggests that MGG-9 is consistent with a standard initial mass function, whereas MGG-11 appears to be deficient in low-mass stars relative to a standard IMF. There is, however, evidence of mass segregation in the clusters, in which case the virial mass estimates would represent lower limits.Comment: 16 pages, 8 figures; ApJ, in pres

Gonadotropin-releasing hormone agonist use in men without a cancer registry diagnosis of prostate cancer

<p>Abstract</p> <p>Background</p> <p>Use of gonadotropin-releasing hormone (GnRH) agonists has become popular for virtually all stages of prostate cancer. We hypothesized that some men receive these agents after only a limited work-up for their cancer. Such cases may be missed by tumor registries, leading to underestimates of the total extent of GnRH agonist use.</p> <p>Methods</p> <p>We used linked Surveillance, Epidemiology and End-Results (SEER)-Medicare data from 1993 through 2001 to identify GnRH agonist use in men with either a diagnosis of prostate cancer registered in SEER, or with a diagnosis of prostate cancer based only on Medicare claims (from the 5% control sample of Medicare beneficiaries residing in SEER areas without a registered diagnosis of cancer). The proportion of incident GnRH agonist users without a registry diagnosis of prostate cancer was calculated. Factors associated with lack of a registry diagnosis were examined in multivariable analyses.</p> <p>Results</p> <p>Of incident GnRH agonist users, 8.9% had no diagnosis of prostate cancer registered in SEER. In a multivariable logistic regression model, lack of a registry diagnosis of prostate cancer in GnRH agonist users was significantly more likely with increasing comorbidity, whereas it was less likely in men who had undergone either inpatient admission or procedures such as radical prostatectomy, prostate biopsy, or transurethral resection of the prostate.</p> <p>Conclusion</p> <p>Reliance solely on tumor registry data may underestimate the rate of GnRH agonist use in men with prostate cancer.</p

Enset‐based agricultural systems in Ethiopia: A systematic review of production trends, agronomy, processing and the wider food security applications of a neglected banana relative

Enset (Ensete ventricosum (Welw.) Cheesman) is the major starch staple of the Ethiopian Highlands, where its unique attributes enhance the food security of approximately 20 million people and have earned it the title “The Tree Against Hunger”. Yet enset‐based agriculture is virtually unknown outside of its narrow zone of cultivation, despite growing wild across much of East and Southern Africa. Here, we review historical production data to show that the area of land under enset production in Ethiopia has reportedly increased 46% in two decades, whilst yield increased 12‐fold over the same period, making enset the second most produced crop species in Ethiopia—though we critically evaluate potential issues with these data. Furthermore, we address a major challenge in the development and wider cultivation of enset, by reviewing and synthesizing the complex and fragmented agronomic and ethnobotanic knowledge associated with this species; including farming systems, processing methods, products, medicinal uses and cultural importance. Finally, we provide a framework to improve the quality, consistency and comparability of data collected across culturally diverse enset‐based agricultural systems to enhanced sustainable use of this neglected starch staple. In conclusion, we discuss the challenges and opportunities for enset cultivation beyond its restricted distribution, and the regional food security potential it could afford smallholders elsewhere in Southern and East Africa

Cause of Death in Older Men After the Diagnosis of Prostate Cancer

To compare survival and cause of death in men aged 65 and older diagnosed with prostate cancer and with survival and cause of death in a noncancer control population. DESIGN : Retrospective cohort from a population-based tumor registry linked to Medicare claims data. SETTING : Eleven regions of the Surveillance, Epidemiology and End Results (SEER) Tumor Registry. PARTICIPANTS : Men aged 65 to 84 (N=208,601) diagnosed with prostate cancer from 1988 through 2002 formed the basis for different analytical cohorts. MEASUREMENTS : Survival as a function of stage and tumor grade (low, Gleason grade<7; moderate, grade=7; and high, grade=8–10) was compared with survival in men without any cancer using Cox proportional hazards regression. Cause of death according to stage and tumor grade were compared using chi-square statistics. RESULTS : Men with early-stage prostate cancer and with low- to moderate-grade tumors (59.1% of the entire sample) experienced a survival not substantially worse than men without prostate cancer. In those men, cardiovascular disease and other cancers were the leading causes of death. CONCLUSION : The excellent survival of older men with early-stage, low- to moderate-grade prostate cancer, along with the patterns of causes of death, implies that this population would be well served by an ongoing focus on screening and prevention of cardiovascular disease and other cancers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66098/1/j.1532-5415.2008.02091.x.pd

Informing the design of a randomised controlled trial of an exercise-based programme for long term stroke survivors: lessons from a before-and-after case series study

Background: To inform the design of a randomised controlled trial (RCT) of an exercise-based programme for long term stroke survivors, we conducted a mixed methods before-and-after case series with assessment at three time points. We evaluated Action for Rehabilitation from Neurological Injury (ARNI), a personalised, functionally-focussed programme. It was delivered through 24 hours of one-to-one training by an Exercise Professional (EP), plus at least 2 hours weekly unsupervised exercise, over 12- 14 weeks. Assessment was by patient-rated questionnaires addressing function, physical activity, confidence, fatigue and health-related quality of life; objective assessment of gait quality and speed; qualitative individual interviews conducted with participants. Data were collected at baseline, 3 months and 6 months. Fidelity and acceptability was assessed by participant interviews, audit of participant and EP records, and observation of training. Findings: Four of six enrolled participants completed the exercise programme. Quantitative data demonstrated little change across the sample, but marked changes on some measures for some individuals. Qualitative interviews suggested that small benefits in physical outcomes could be of great psychological significance to participants. Participant-reported fatigue levels commonly increased, and non-completers said they found the programme too demanding. Most key components of the intervention were delivered, but there were several potentially important departures from intervention fidelity. Discussion: The study provided data and experience that are helping to inform the design of an RCT of this intervention. It suggested the need for a broader recruitment strategy; indicated areas that could be explored in more depth in the qualitative component of the trial; and highlighted issues that should be addressed to enhance and evaluate fidelity, particularly in the preparation and monitoring of intervention providers. The experience illustrates the value of even small sample before-and-after studies in the development of trials of complex interventions.PenCLAHRC; NIH

Hubble Space Telescope Observations of the Oldest Star Clusters in the LMC

We present V, V-I color-magnitude diagrams (CMDs) for three old star clusters in the Large Magellanic Cloud (LMC): NGC 1466, NGC 2257 and Hodge 11. Our data extend about 3 magnitudes below the main-sequence turnoff, allowing us to determine accurate relative ages and the blue straggler frequencies. Based on a differential comparison of the CMDs, any age difference between the three LMC clusters is less than 1.5 Gyr. Comparing their CMDs to those of M 92 and M 3, the LMC clusters, unless their published metallicities are significantly in error, are the same age as the old Galactic globulars. The similar ages to Galactic globulars are shown to be consistent with hierarchial clustering models of galaxy formation. The blue straggler frequencies are also similar to those of Galactic globular clusters. We derive a true distance modulus to the LMC of (m-M)=18.46 +/- 0.09 (assuming (m-M)=14.61 for M 92) using these three LMC clusters.Comment: 22 pages; to be published in Ap

Aggregation of Normative Microsupply Relationships for Dryland Crop Farms in the Rolling Plains of Oklahoma and Texas

The Oklahoma Agricultural Experiment Station periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311