Mark Welford | Georgia Southern University (original) (raw)

Papers by Mark Welford

Research paper thumbnail of Revisiting the Medieval Black Death of 1347–1351: Spatiotemporal Dynamics Suggestive of an Alternate Causation

Geography Compass, Jan 1, 2010

Recent research points to multiple inconsistencies regarding modern Yersinia pestis (in Bubonic, ... more Recent research points to multiple inconsistencies regarding modern Yersinia pestis (in Bubonic, Pneumonic, or Septicemic Plague variants) as a causative agent for the Medieval Black Death (MBD). Published arguments at odds with a Y. pestis-caused epidemic include differences in recorded periodicity, seasonal mortality peaks, relevant biogeographical details, genetic findings, and spatiotemporal dynamics, among other inconsistencies. Here, we describe and expand on some of the recent literature noting these items. In addition, we discuss preliminary research related to our recently published theory, in which we agree with research suggesting that the MBD was caused by a virus, not a bacterium, and elucidate our contention that seasonal changes and medieval human trade patterns controlled the timing of peak mortality during the MBD and subsequent 'plagues'. Epidemic evidence from the first epidemic wave and later outbreaks is presented in support of our hypothesis.

Research paper thumbnail of Spatio‐Temporal Attributes of Pandemic and Epidemic Diseases

Geography Compass, Jan 1, 2010

Human-to-human transmissible pandemics, most notably the Medieval Black Death and Spanish

Research paper thumbnail of Rock Glacier Distribution: The Results of Either Topoclimatic Or Geologic Factors

Research paper thumbnail of Evidence for Giant Cowbird Molothrus oryzivorus brood parasitism of Turquoise Jays Cyanolyca turcosa in north-west Ecuador, and how this alters our  …

Research paper thumbnail of An Assessment of Combined Academic Geology and Geography Departments Based on a Survey of Department Chairs.

Journal of Geoscience Education, Jan 1, 2000

Research paper thumbnail of Quaternary terrace formation in the Little Salmon River Basin

Research paper thumbnail of Habitat preference and population density among wintering Hermit Thrushes in SE Georgia

… from the Annual Meeting of the …, Jan 1, 2009

Research paper thumbnail of THE CURSE OF THE LABRADOR DUCK: My Obsessive Quest to the Edge of Extinction. By Glen Chilton.

Geographical Review, Jan 1, 2010

Research paper thumbnail of Theory and research in geography education

Journal of Geography, Jan 1, 2000

Research paper thumbnail of New record of Swallow-tailed Nightjar Uropsalis segmentata for Pichincha province and the west slope of the Andes in Ecuador

Research paper thumbnail of Field evaluation of empirical equations in straight alluvial channels

Physical Geography, Jan 1, 1993

Research paper thumbnail of A simple soil moisture index to forecast crop yields

Research paper thumbnail of A field evaluation of the formative conditions, wavelengths and heights of alternate bars in alluvial channels

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

Medical hypotheses, Jan 1, 2009

Available online xxxx s u m m a r y Recent research into the world's greatest recorded epidemic, ... more Available online xxxx s u m m a r y Recent research into the world's 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 1900s? 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 allencompassing 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 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.

Research paper thumbnail of Experiences, reflections and recommendations of a teaching assistant in the USA

Journal of Geography in Higher Education, Jan 1, 1986

(1986) Welford. Journal of Geography in Higher Education. Read by researchers in: 100% Education.... more (1986) Welford. Journal of Geography in Higher Education. Read by researchers in: 100% Education. The Teaching Assistant (TA) system operating in the United States has both advantages and disadvantages to graduate students employed as TAs and undergraduates taught ...

Research paper thumbnail of Validation of inverse seasonal peak mortality in medieval plagues, including the Black Death, in comparison to modern Yersinia pestis-variant diseases

PLoS One, Jan 1, 2009

Background: Recent studies have noted myriad qualitative and quantitative inconsistencies between... more 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. 1900615 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.

Research paper thumbnail of The importance of early successional habitats to rare, restricted-range, and endangered birds in the Ecuadorian Andes

Bird Conservation International, Jan 1, 2000

Since the mid-1980s, exhausted pastures in Ecuador have been increasingly abandoned, allowing for... more Since the mid-1980s, exhausted pastures in Ecuador have been increasingly abandoned, allowing forest regeneration. At approximately 2,200 m in the Tandayapa valley I surveyed four abandoned pastures to evaluate their use by birds. Each former pasture represented a different age of vegetation maturity. The number of bird species recorded in each successively older abandoned pasture increased but only half the number of species recorded in the undisturbed forest site was recorded in the most mature pasture. However, at least four restricted-range bird species were recorded in a single pasture. As pastures rapidly convert to secondary forest, more bird species and rarer bird species use them, even in highly disturbed areas where surrounding pristine forest constitutes less than 10% of local forest cover. Conservation efforts should then be directed toward them.

Research paper thumbnail of A field test of tubino's (1991) model of alternate bar formation

Earth Surface Processes and Landforms, Jan 1, 1994

This study investigates the fluvial dynamics of straight natural stream channels. In particular, ... more This study investigates the fluvial dynamics of straight natural stream channels. In particular, this experimental field study quantitatively assesses a physically based non-linear mathematical theory of alternate bar formation under unsteady natural flow conditions within a straight alluvial stream. 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, bed sediment size and flow stage over a 2 year study period.

Research paper thumbnail of Initiation of river meandering

Progress in Physical Geography, Jan 1, 1991

Meanders, or frequent sinuous reversals of channel curvature, are a fundamental characteristic of... more Meanders, or frequent sinuous reversals of channel curvature, are a fundamental characteristic of river planform. Although the cause of meandering has attracted attention since the beginning of civilization, as yet there is no completely satisfactory explanation of this phenomenon. The self-similarity of meander geometry over a wide range of scales and environmental conditions suggests that meandering reflects the influence of some general control (Davy and . Various arguments have been advanced to explain why rivers meander, including dissipation of excess energy , minimization of energy expenditure , and minimization of the variance in bed shear stress and boundary friction (Langbein and . These theories provide predictions that conform well with observed forms, but they are primarily teleological in nature and thus difficult to evaluate scientifically; minimization of energy or shear stress could just as easily be the result of meandering as it could the cause (Richards, 1982: 28). More important, these arguments do not describe how meanders develop.

Research paper thumbnail of The equilibrium concept in geomorphology

Annals of the Association of American …, Jan 1, 1994

Research paper thumbnail of Revisiting the Medieval Black Death of 1347–1351: Spatiotemporal Dynamics Suggestive of an Alternate Causation

Geography Compass, Jan 1, 2010

Recent research points to multiple inconsistencies regarding modern Yersinia pestis (in Bubonic, ... more Recent research points to multiple inconsistencies regarding modern Yersinia pestis (in Bubonic, Pneumonic, or Septicemic Plague variants) as a causative agent for the Medieval Black Death (MBD). Published arguments at odds with a Y. pestis-caused epidemic include differences in recorded periodicity, seasonal mortality peaks, relevant biogeographical details, genetic findings, and spatiotemporal dynamics, among other inconsistencies. Here, we describe and expand on some of the recent literature noting these items. In addition, we discuss preliminary research related to our recently published theory, in which we agree with research suggesting that the MBD was caused by a virus, not a bacterium, and elucidate our contention that seasonal changes and medieval human trade patterns controlled the timing of peak mortality during the MBD and subsequent 'plagues'. Epidemic evidence from the first epidemic wave and later outbreaks is presented in support of our hypothesis.

Research paper thumbnail of Spatio‐Temporal Attributes of Pandemic and Epidemic Diseases

Geography Compass, Jan 1, 2010

Human-to-human transmissible pandemics, most notably the Medieval Black Death and Spanish

Research paper thumbnail of Rock Glacier Distribution: The Results of Either Topoclimatic Or Geologic Factors

Research paper thumbnail of Evidence for Giant Cowbird Molothrus oryzivorus brood parasitism of Turquoise Jays Cyanolyca turcosa in north-west Ecuador, and how this alters our  …

Research paper thumbnail of An Assessment of Combined Academic Geology and Geography Departments Based on a Survey of Department Chairs.

Journal of Geoscience Education, Jan 1, 2000

Research paper thumbnail of Quaternary terrace formation in the Little Salmon River Basin

Research paper thumbnail of Habitat preference and population density among wintering Hermit Thrushes in SE Georgia

… from the Annual Meeting of the …, Jan 1, 2009

Research paper thumbnail of THE CURSE OF THE LABRADOR DUCK: My Obsessive Quest to the Edge of Extinction. By Glen Chilton.

Geographical Review, Jan 1, 2010

Research paper thumbnail of Theory and research in geography education

Journal of Geography, Jan 1, 2000

Research paper thumbnail of New record of Swallow-tailed Nightjar Uropsalis segmentata for Pichincha province and the west slope of the Andes in Ecuador

Research paper thumbnail of Field evaluation of empirical equations in straight alluvial channels

Physical Geography, Jan 1, 1993

Research paper thumbnail of A simple soil moisture index to forecast crop yields

Research paper thumbnail of A field evaluation of the formative conditions, wavelengths and heights of alternate bars in alluvial channels

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

Medical hypotheses, Jan 1, 2009

Available online xxxx s u m m a r y Recent research into the world's greatest recorded epidemic, ... more Available online xxxx s u m m a r y Recent research into the world's 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 1900s? 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 allencompassing 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 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.

Research paper thumbnail of Experiences, reflections and recommendations of a teaching assistant in the USA

Journal of Geography in Higher Education, Jan 1, 1986

(1986) Welford. Journal of Geography in Higher Education. Read by researchers in: 100% Education.... more (1986) Welford. Journal of Geography in Higher Education. Read by researchers in: 100% Education. The Teaching Assistant (TA) system operating in the United States has both advantages and disadvantages to graduate students employed as TAs and undergraduates taught ...

Research paper thumbnail of Validation of inverse seasonal peak mortality in medieval plagues, including the Black Death, in comparison to modern Yersinia pestis-variant diseases

PLoS One, Jan 1, 2009

Background: Recent studies have noted myriad qualitative and quantitative inconsistencies between... more 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. 1900615 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.

Research paper thumbnail of The importance of early successional habitats to rare, restricted-range, and endangered birds in the Ecuadorian Andes

Bird Conservation International, Jan 1, 2000

Since the mid-1980s, exhausted pastures in Ecuador have been increasingly abandoned, allowing for... more Since the mid-1980s, exhausted pastures in Ecuador have been increasingly abandoned, allowing forest regeneration. At approximately 2,200 m in the Tandayapa valley I surveyed four abandoned pastures to evaluate their use by birds. Each former pasture represented a different age of vegetation maturity. The number of bird species recorded in each successively older abandoned pasture increased but only half the number of species recorded in the undisturbed forest site was recorded in the most mature pasture. However, at least four restricted-range bird species were recorded in a single pasture. As pastures rapidly convert to secondary forest, more bird species and rarer bird species use them, even in highly disturbed areas where surrounding pristine forest constitutes less than 10% of local forest cover. Conservation efforts should then be directed toward them.

Research paper thumbnail of A field test of tubino's (1991) model of alternate bar formation

Earth Surface Processes and Landforms, Jan 1, 1994

This study investigates the fluvial dynamics of straight natural stream channels. In particular, ... more This study investigates the fluvial dynamics of straight natural stream channels. In particular, this experimental field study quantitatively assesses a physically based non-linear mathematical theory of alternate bar formation under unsteady natural flow conditions within a straight alluvial stream. 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, bed sediment size and flow stage over a 2 year study period.

Research paper thumbnail of Initiation of river meandering

Progress in Physical Geography, Jan 1, 1991

Meanders, or frequent sinuous reversals of channel curvature, are a fundamental characteristic of... more Meanders, or frequent sinuous reversals of channel curvature, are a fundamental characteristic of river planform. Although the cause of meandering has attracted attention since the beginning of civilization, as yet there is no completely satisfactory explanation of this phenomenon. The self-similarity of meander geometry over a wide range of scales and environmental conditions suggests that meandering reflects the influence of some general control (Davy and . Various arguments have been advanced to explain why rivers meander, including dissipation of excess energy , minimization of energy expenditure , and minimization of the variance in bed shear stress and boundary friction (Langbein and . These theories provide predictions that conform well with observed forms, but they are primarily teleological in nature and thus difficult to evaluate scientifically; minimization of energy or shear stress could just as easily be the result of meandering as it could the cause (Richards, 1982: 28). More important, these arguments do not describe how meanders develop.

Research paper thumbnail of The equilibrium concept in geomorphology

Annals of the Association of American …, Jan 1, 1994