Mark R. Welford

Validation of Inverse Seasonal Peak Mortality in Medieval Plagues, Including the Black Death, in Comparison to Modern Yersinia pestis-Variant Diseases

Background Recent studies have noted myriad qualitative and quantitative inconsistencies between the medieval Black Death (and subsequent “plagues”) and modern empirical Y. pestis plague data, most of which is derived from the Indian and Chinese plague outbreaks of A.D. 1900±15 years. Previous works have noted apparent differences in seasonal mortality peaks during Black Death outbreaks versus peaks of bubonic and pneumonic plagues attributed to Y. pestis infection, but have not provided spatiotemporal statistical support. Our objective here was to validate individual observations of this seasonal discrepancy in peak mortality between historical epidemics and modern empirical data. Methodology/Principal Findings We compiled and aggregated multiple daily, weekly and monthly datasets of both Y. pestis plague epidemics and suspected Black Death epidemics to compare seasonal differences in mortality peaks at a monthly resolution. Statistical and time series analyses of the epidemic data indicate that a seasonal inversion in peak mortality does exist between known Y. pestis plague and suspected Black Death epidemics. We provide possible explanations for this seasonal inversion. Conclusions/Significance These results add further evidence of inconsistency between historical plagues, including the Black Death, and our current understanding of Y. pestis-variant disease. We expect that the line of inquiry into the disputed cause of the greatest recorded epidemic will continue to intensify. Given the rapid pace of environmental change in the modern world, it is crucial that we understand past lethal outbreaks as fully as possible in order to prepare for future deadly pandemics.

Did medieval trade activity and a viral etiology control the spatial extent and seasonal distribution of Black Death mortality

Recent research into the worlds greatest recorded epidemic, the Medieval Black Death (MBD), has cast doubt on Bubonic Plague as the etiologic agent. Prior research has recently culminated in outstanding advances in our understanding of the spatio-temporal pattern of MBD mortality, and a characterization of the incubation, latent, infectious, and symptomatic periods of the MBD. However, until now, several mysteries remained unexplained, including perhaps the biggest quandary of all: why did the MBD exhibit inverse seasonal peaks in mortality from diseases recorded in modern times, such as seasonal Influenza or the Indian Plague Epidemics of the early 1900 s? Although some have argued that climate changes likely explain the observed differences between modern clinical Bubonic Plague seasonality and MBD mortality accounts, we believe that another factor explains these dissimilarities. Here, we provide a synthetic hypothesis which builds upon previous theories developed in the last ten years or so. Our all-encompassing theory explains the causation, dissemination, and lethality of the MBD. We theorize that the MBD was a human-to-human transmitted virus, originating in East-Central Asia and not Africa (as some recent work has proposed), and that its areal extent during the first great epidemic wave of 1347-1350 was controlled hierarchically by proximity to trade routes. We also propose that the seasonality of medieval trade controlled the warm-weather mortality peaks witnessed during 1347-1350; during the time of greatest market activity, traders, fairgoers, and religious pilgrims served as unintentional vectors of a lethal virus with an incubation period of approximately 32 days, including a largely asymptomatic yet infectious period of roughly three weeks. We include a description of the rigorous research agenda that we have proposed in order to subject our theory to scientific scrutiny and a description of our plans to generate the first publicly available georeferenced GIS dataset pertaining to MBD mortality, as far as we are aware. This proposed theory, if supported by our aggressive and statistically robust proposed research activities, finally contains all of the elements necessary to convincingly reanalyze both the greatest historical epidemic of the last millennium, and the risk to modern populations in light of such findings.

Coastal Georgia Is Not Immune: Hurricane History, 1851–2012

we utilize HURDAT2 data. Prior research has utilized historical records to regionally examine hurricane landfalls along the U.S. coast. For example, Mock has conducted studies for South Carolina (2004) and Louisiana (2008). Fraser (2006) has noted historic Georgia hurricanes as described in newspapers and other written documentation, but a focus on coastal Georgia’s HURDAT2 data is novel. We analyze the frequency trends, intensity over time, seasonality, zone of formation, time from formation to landfall, and spatial distribution for Georgia’s fourteen recorded hurricane landfalls in HURDAT2.

Body Lice,Yersinia pestisOrientalis, and Black Death

To the Editor: A scientifi c debate with public health implications wages: What caused the medieval European plague epidemics known as Black Death? Recent articles note inconsistencies between a rat fl ea– borne pandemic of Yersinia pestis (the bacterium that causes bubonic plague) and the documented characteristics of Black Death (1, among others). Ayyadurai et al. (2) acknowledge that a rat fl ea–only hypothesis does not fi t Black Death observations, but they resolve theoretical transmission inconsistencies through a louse-borne hypothesis. Ayyadurai et al. base their surety of fact—that medieval “plagues” were caused by Y. pestis infection—on a 2007 study (3) in which 5 of 36 teeth of “plague” victims, none of which were dated to the Black Death era (1347–1351), contained biological evidence of Y. pestis. The 3 locations in that study were all port cities: 2 on the Mediterranean Sea and 1 on the Rhone River. As Duncan and Scott (4) note, bubonic plague most likely existed endemically near ship-borne trade, unlike the fast-moving epidemic fronts exhibited by medieval “plagues.” Moreover, Gilbert et al. (5) found no Y. pestis DNA in 61 skeletons from primarily nonport locations in England, France, and Denmark. We do not dispute the authors’ claim that Y. pestis might have been present in some skeletons from port cities in France, or that body lice might, under certain circumstances, transmit the Orientalis biotype of Y. pestis; their work appears careful and considered. However, given the differences mentioned above and improved knowledge on the rapidity of virus mutation and worldwide transmission potential, we merely argue that the simplest explanation for medieval plagues has yet to be ruled out: that they may have resulted from a human-to-human transmitted virus. Adding complexity to an already complicated etiologic theory, and stating such as historical fact based on limited geography and sample size, does not seem congruent with Occam’s razor.

A SIMPLE SOIL MOISTURE INDEX TO FORECAST CROP YIELDS

Neutron probe soil moisture measurements obtained biweekly during the growing season between 1982 and 1991 from multiple depths under grass-covered plots at 17 Illinois Climate Network sites are used to forecast crop yields. A Soil Moisture Index (SMIX) that combines the effect of intensity, duration, and timing of drought or excessively wet conditions was computed by integrating the quantity of available soil moisture throughout the rooting zone over the growing season. Relationships between the SMIX values and crop yields are evaluated at county, regional, and statewide scales. Coefficients of determination (r 2) for relationships between the SMIX values and maize, soybeans, and hay yields at the statewide level are 0.88, 0.74, and 0.81, respectively, when the period of integration is terminated at the end of the growing season. This new soil index can be employed to forecast yields as early as 12 weeks before harvest for the state of Illinois. However, predictions with RMSE ≤ 10% of the mean yield can ...

Field Evaluation of Empirical Equations in Straight Alluvial Channels

Six experimentally derived formulae that predict the conditions for alternate bar formation and equilibrium bar dimensions are assessed using field data. The study site is an artificially straightened section of the Embarras River located approximately 16 km south of Champaign, Illinois. Data were collected on channel form, gradient, alternate bar dimensions, bar sediment size, and flow conditions over a two-year study period. Experimental flume studies suggest that alternate bars form in wide, straight, shallow streams, have wavelengths between 4 and 15 channel widths, and have heights that are roughly equal to the average depth of flow. Bar formation under unsteady flow conditions can be predicted accurately by the experimentally derived steady-flow formulae, but these formulae fail to predict bar dimensions sucessfully. These results suggest that the process of bar formation in artificially straightened, sand-bedded natural streams may occur outside the range of flow conditions predicted by existing em...

Archival Evidence of Secular Changes in Georgia Hurricanes: 1750–2012

North Atlantic hurricanes present the greatest recurring meteorological hazard along the southern and eastern shores of the USA. Since the late 1800s, in contrast to much of the Southeastern USA, the Georgia coast has experienced infrequent hurricane landfalls, particularly in recent decades. As a result, coastal storm preparedness complacency appears to be rampant along the Georgia coastline. Both local and state governments were unprepared for shadow evacuation during Hurricane Floyd in 1999. The study described here includes an examination of temporal and spatial trends in hurricane landfall along the Georgia coast from 1750 to 2012. Since 1750, 18 of the 24 recorded hurricanes that made landfall along the Georgia coast occurred between 1801 and 1900, yet the hurricane intensities have declined since 1851. Most critically our data establishes that the mean location of landfall along the Georgia coast has shifted 60 km north and hence closer to Savannah. Future efforts to re-characterize hurricane surge zones and improve evacuation infrastructure along the Georgia coast must reevaluate this threat.

Arena symposium: teaching assistants

Abstract The Teaching Assistant (TA) system operating in the United States has both advantages and disadvantages to graduate students employed as TAs and undergraduates taught by these TAs. The system develops teaching and communication skills and broadens TA capability, understanding and marketability. Discussion and lab sections taught by TAs provide an arena where undergraduates are exposed to everything from simple ideas to difficult ideas that need hands‐on help. However, few quality control procedures are employed to determine prospective TAs. Moreover, TA training is of limited extent and use. TAs either sink or swim; none the less the vast majority do survive and do an excellent job. A number of measures that any university, college or department might employ if they intend to begin employing TAs are recommended: all TAs should attend TA orientation sessions that discuss university‐wide TA issues; departments should also create sessions that specially train TAs in how to teach their respective cou...

Arena symposium: teaching assistants: Experiences, reflections and recommendations of a teaching assistant in the USA

Abstract The Teaching Assistant (TA) system operating in the United States has both advantages and disadvantages to graduate students employed as TAs and undergraduates taught by these TAs. The system develops teaching and communication skills and broadens TA capability, understanding and marketability. Discussion and lab sections taught by TAs provide an arena where undergraduates are exposed to everything from simple ideas to difficult ideas that need hands‐on help. However, few quality control procedures are employed to determine prospective TAs. Moreover, TA training is of limited extent and use. TAs either sink or swim; none the less the vast majority do survive and do an excellent job. A number of measures that any university, college or department might employ if they intend to begin employing TAs are recommended: all TAs should attend TA orientation sessions that discuss university‐wide TA issues; departments should also create sessions that specially train TAs in how to teach their respective cou...