Timeliness, Trade and Agglomeration

An important element of the cost of distance is time taken in delivering final and intermediategoods. We argue that time costs are qualitatively different from direct monetary costs such asfreight charges. The difference arises because of uncertainty. Unsynchronised deliveries candisrupt production, and delivery time can force producers to order components beforedemand and cost uncertainties are resolved. Using several related models we show that thiscan cause clustering of component production. If final assembly takes place in two locationsand component production has increasing returns to scale, then component production willtend to cluster around just one of the assembly plants.Just- in-time, clustering, location, trade.

Timeliness, Trade and Agglomeration

An important element of the cost of distance is time taken in delivering final and intermediate goods. We argue that time costs are qualitatively different from direct monetary costs such as freight charges. The difference arises because of uncertainty. Unsynchronised deliveries can disrupt production, and delivery time can force producers to order components before demand and cost uncertainties are resolved. Using several related models we show that this generates hitherto unexplored incentives for clustering. If final assembly takes place in two locations and component production has increasing returns to scale, then component production will tend to cluster around just one of the assembly plants.

Harrigan to Doug Donahue, 30 September 1962

Harrigan asks the publication to call and mentions Paul Guihard\u27s death.https://egrove.olemiss.edu/west_union_med/1108/thumbnail.jp

The South Is Different

https://egrove.olemiss.edu/citizens_clip/1113/thumbnail.jp

Papillary muscle traction in mitral valve prolapse: Quantitation by two-dimensional echocardiography

Previous angiographic observations in patients with mitral valve prolapse have suggested that superior leaflet displacement results in abnormal superior tension on the papillary muscle tips that causes their superior traction or displacement. It has further been postulated that such tension can potentially affect the mechanical and electrophysiologic function of the left ventricle. The purpose of this study was to confirm and quantitate this phenomenon noninvasively by using two-dimensional echocardiography to determine whether superior displacement of the papillary muscle tips occurs and its relation to the degree of mitral leaflet displacement.Directed echocardiographic examination of the papillary muscles and mitral anulus was carried out in a series of patients with classic mitral valve prolapse and results were compared with those in a group of normal control subjects. Distance from the anulus to the papillary muscle tip was measured both in early and at peak ventricular systole. In normal subjects, this distance did not change significantly through systole, whereas in the patient group it decreased, corresponding to a superior displacement of the papillary muscle tips toward the anulus in systole (8.5 ± 2.6 vs. 0.8 ± 0.7 mm; p < 0.0001). This superior papillary muscle motion paralleled the superior displacement of the leaflets in individual patients (y = l.0x + 0.8; r = 0.93) and followed a similar time course. The systolic motion of the mitral anulus toward the apex, assessed with respect to a fixed external reference, was not significantly different in the patients and control groups (14.3 ± 4 vs. 15.5 ± 4.4 mm; p = 0.4) and therefore could not explain the superior papillary muscle tip motion relative to the anulus in the patients with mitral valve prolapse.These results demonstrate that normal mechanisms maintain a relatively constant distance between the papillary muscle tips and the mitral anulus during systole. In classic mitral valve prolapse, superior leaflet displacement is paralleled by superior displacement of the papillary muscles that is consistent with superiorly directed forces causing their traction. Two-dimensional echocardiography can therefore be used to measure these relations and test hypotheses as to their clinical correlates in patients with mitral valve prolapse

Use of the Spine AdVerse Events Severity (SAVES) System to Categorize and Report Adverse Events in Spine Surgery.

Introduction: Analysis of adverse events (AEs) in spine surgery has historically been retrospective, utilizing hospital administrative data. Our objective was to determine the incidence, severity and effect on hospital length of stay (LOS) for AEs in spine surgery using the Spine AdVerse Events Severity (SAVES V2) system. Methods: AEs for all surgical spine patients at our institution were prospectively collected for 18 months and correlated with retrospective data from operative reports and H&Ps. Statistical analyses compared patient demographics, diagnoses, and surgical characteristics to hospital length of stay and likelihood of adverse events. Results: This system captured 75% (765/977) of surgical cases for all indications over the study period. 73% (541/743) of patients experienced at least one AE, with an average of 1.2 AEs per patient (range 0-5). The most common AEs were pain control (31%), urinary retention (9.7%), wound infection (6.3%), and incidental durotomy (5.8%). For patients experiencing at least one AE, 30% had no effect on LOS, 48% increased LOS by 1-2 days, 15% increased LOS by 3-7 days, and 7% had prolonged LOS greater than 8 days. Our system captured 25.4% more adverse events (60.0% vs. 34.6%) than hospital administrative data. Univariate analysis revealed patient age, emergent surgery, diagnostic and surgical categories, and spine region to be predictors of both AEs and LOS. Instrumentation was predictive of increased LOS but not AEs. The type of AE was strongly associated with LOS. Multivariable analysis of AE likelihood demonstrated emergent surgery to be the strongest independent predictor with an adjusted odds ratio of 8.5 versus elective surgery. Discussion: Spine surgery is associated with a high incidence of adverse events, which often prolong hospital length of stay. Better characterization of adverse events and their predictors could lead to improved management strategies that reduce patient morbidity and mortality

Global Adoption of Genetically Modified (GM) Crops: Challenges for the Public Sector

Advances in biotechnology continue to drive the development of a wide range of insect-protected, herbicide-tolerant, stress-tolerant, and nutritionally enhanced genetically modified (GM) crops, yet societal and public policy considerations may slow their commercialization. Such restrictions may disproportionately affect developing countries, as well as smaller entrepreneurial and public sector initiatives. The 2014 IUPAC International Congress of Pesticide Chemistry (San Francisco, CA, USA; August 2014) included a symposium on “Challenges Associated with Global Adoption of Agricultural Biotechnology” to review current obstacles in promoting GM crops. Challenges identified by symposium presenters included (i) poor public understanding of GM technology and the need for enhanced communication strategies, (ii) nonharmonized and prescriptive regulatory requirements, and (iii) limited experience with regulations and product development within some public sector programs. The need for holistic resistance management programs to enable the most effective use of insect-protected crops was also a point of emphasis. This paper provides details on the symposium discussion and provides background information that can be used in support of further adoption of beneficial GM crops. Overall, it emphasizes that global adoption of modern agricultural biotechnology has not only provided benefits to growers and consumers but has great potential to provide solutions to an increasing global population and diminishing agricultural land. This potential will be realized by continued scientific innovation, harmonized regulatory systems, and broader communication of the benefits of the high-yielding, disease-resistant, and nutritionally enhanced crops attainable through modern biotechnology

Results of external quality assessment for proviral DNA testing of HIV tropism in the Maraviroc switch collaborative study

The Maraviroc Switch collaborative study (MARCH) is a study in aviremic patients on stable antiretroviral therapy and utilizes population-based sequencing of proviral DNA to determine HIV tropism and susceptibility to maraviroc. An external quality assessment (EQA) program was implemented to ensure competency in assessing the tropism of clinical samples conducted by MARCH laboratories (n = 14). The MARCH EQA has three prestudy phases assessing V3 loop sequencing and tropism determination using the bioinformatic algorithm geno2pheno, which generates a false-positive rate (FPR). DNA sequences with low FPRs are more likely to be from CXCR4-using (X4) viruses. Phase 1 of the EQA involved chromatogram interpretation. Phases 2, 2/3, and 3 involved patient and clonal samples. Clinical samples used in these phases were from treatment-experienced HIVinfected volunteers; 18/20 had viral loads o