Hypotheses Of Causation Research Articles

Pathology-Based Animal Cancer Registry of Abruzzo and Molise Regions (Central Italy): A Ten-Year Retrospective Study (2014–2023)

Pets have a crucial role in cancer research. Specifically, dogs and cats share the same environment as their owners and thus may serve as sentinels of naturally occurring tumors that are linked to the exposure to environmental hazards. Quantitative comparison of tumor types may reveal unusual cancer frequencies, providing directions for research and generation of hypotheses of cancer causation in a specific area and identification of risk factors. The aim of this study was to describe the data collected by the pathology-based animal cancer registry, managed by Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise (IZSAM), during 10 years of activity (2014–2023) and to assess its potential epidemiological relevance. Frequencies of tumor topography and morphology in dogs and cats were described, analyzed and compared. Proportional morbidity ratios (PMRs) were calculated, taking into consideration some potential risk factors such as species, breed, sex, diet and living environment. The database comprises 5311 tumors (n = 4719 in dogs and n = 592 in cats), with a higher prevalence in females (67.3% in dogs and 61.2% in cats). The mean age at the first diagnosis of tumors was similar between sexes and slightly lower in dogs compared to cats. PMRs highlighted certain risk and “protective” factors for the development of tumors in specific topography. The risk of developing tumors of the blood and hematopoietic system (PMR = 0.44; 95% CI: 0.21–0.94), skin and subcutaneous tissues (PMR = 0.70; 95% CI: 0.61–0.80), oral cavity and pharynx (PMR = 0.60; 95% CI: 0.24–0.89), urinary organs (PMR = 0.33; 95% CI: 0.11–0.99) and bones, joints and cartilage (PMR = 0.72; 95% CI: 0.22–0.98) was lower in non-neutered male dogs than in neutered male dogs. Non-spayed female dogs had a greater risk of developing tumors of the mammary gland (PMR = 1.75; 95% CI: 1.57–1.96), female sexual organs (PMR = 2.12; 95% CI: 1.01–4.36) and respiratory system (PMR = 2.25; 95% CI: 1.55–6.74) but less risk for cutaneous and subcutaneous tissue tumors (PMR = 0.44; 95% CI: 0.38–0.51) and blood/hematopoietic system tumors (PMR = 0.47; 95% CI: 0.26–0.85) compared to spayed female dogs. Compared with mixed breed, purebred dogs had a significantly greater risk of developing mammary gland tumors (PMR = 1.36; 95% CI: 1.20–1.54) and lower risk for respiratory (PMR = 0.15; 95% CI: 0.07–0.32), gastrointestinal (PMR = 0.63; 95% CI: 0.34–0.94) and oral (PMR = 0.59; 95% CI: 0.36–0.96) neoplasia. Non-neutered male cats had a lower risk of developing skin and subcutaneous tumors (PMR = 0.68; 95% CI: 0.50–0.92) compared with neutered cats. The risk of developing skin and subcutaneous tissues tumors was higher for dogs and cats that lived mostly outdoor (PMR dogs = 1.21; 95% CI: 1.10–1.33; PMR cats = 1.18; 95% CI: 1.08–1.47), while dogs that live mainly indoor had a greater risk to develop mammary gland tumors (PMR = 0.78; 95% CI: 0.68–0.89). Results described herein highlight the fundamental role of animal cancer registration initiatives. These efforts would contribute to the possibility of conducting multicentric collaborative studies to deepen the knowledge of the epidemiology of tumors in dogs and cats from a comparative perspective, thus fulfilling the One Health approach.

Abstract 5754: Spatial clustering of sex ratio variations of cancer incidence: A modified Moran's index approach

Abstract Background: Moran's index (I) is one of the most common correlation measurements to investigate spatial process of geographical evolution of disease development and progression. Geospatial variations of sex ratios (male-to-female age-standardized incidence rates) of cancers can be used to postulate on genetic and environmental underpinnings of cancer etiology. The study explored through improved version of Moran's I whether geographic contiguous regions tend to have similar sex-ratios or not, and how SRs of different types of cancers are geographically clustered. Methods: A simplified approach of computing spatial autocorrelation through Moran's Index (I) was applied to global cancer incidence data. Detailed data on 28 cancer subtypes were retrieved from the tenth volume (2003-07) of the International Agency for Research on Cancer's ‘Cancer Incidence in Five Continents'. Using a publicly available world geolocation database, we geocoded 102 and 52 cancer registry-based regions in Europe and Asia, and linked these to cancer incidence data. For each type of cancer, the spatial clustering of SR in geographically contiguous areas were ranked according to the degree of clustering based on values of Moran's I (dispersed [-1] to highly clustered [+1]). Results: In Europe, Moran's I values for SRs of cancer incidence ranged from dispersed patterns such as -0.09 for melanoma, to moderate clustering for esophageal (0.115), liver (0.115), and kidney (0.114) cancers. In contrast in Asia, the SRs for esophageal cancer showed a high degree of spatial clustering (0.597). However, despite these spatial patterns being different in Europe and Asia, the degree of clustering for many of the 28 cancers analyzed were comparable. Among top 10 high incident cancers in Europe and Asia (>5 cases per 100,000), those that have relatively similar clustering include cancers of the esophagus, thyroid, pancreas, rectum and anus, stomach, and kidney. For lung, colon, non-Hodgkin's lymphoma, leukemia, skin melanoma, and brain cancers, we observed different spatial patterns across the two continents. Among the low incident cancers (<2 cases per 100,000) such as nose and sinus, pharynx and gallbladder, there were substantial differences in the degree of geospatial clustering between Europe and Asia, whereas rankings were closer in larynx, eye, multiple myeloma, Hodgkin's lymphoma, and small-intestinal cancers. Conclusions: The findings may help to generate etiological hypotheses of cancer causation. A spatially clustered pattern of cancer suggests exogenous or avoidable causes of cancers, whereas dispersed patterns suggest endogenous causes. Cancers of the esophagus, liver and stomach showed clustered SR patterns in both Europe and Asia. For cancers in which endogenous causes may be reasonably hypothesized, more of high dispersed patterns of SR are observed in Europe (e.g., cancer of the eye). Secondarily, our findings can also be used to identify spatial anomalies that may be reflective of quality concerns for cancer registries. Citation Format: Syed-Ahsan Raza. Spatial clustering of sex ratio variations of cancer incidence: A modified Moran's index approach [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5754.

Incidence pattern and spatial analysis of breast cancer in Iranian women: Geographical Information System applications.

Breast cancer is the leading cancer in Iranian women, but no studies have yet been conducted on the distribution and pattern of its incidence. To perform a spatial analysis and determine the incidence pattern of breast cancer in the Islamic Republic of Iran. This was a cross-sectional, pathology-based study of all new female patients with breast cancer registered in the Islamic Republic of Iran in 2011 (n=10 233). Initially, crude incidence rates were calculated for each province and the whole country per 100 000 person-years. Then, a direct standardization method and World Health Organization standard population were used to adjust for age effects on a geographical scale. Stata and Arc GIS software were used to calculate incidence rates and conduct spatial analysis. The mean (standard deviation) age of the patients was 50.9 (12.6) years. The national age-standardized incidence rate for breast cancer in women was 29.88 per 100 000 person-years, with a range of 5-72 in different provinces. The clustering incidence pattern was observed in Mazandaran, Tehran, Alborz, Isfahan and Markazi Provinces (P < 0.01). There was a significant cluster of high incidence of breast cancer in Iranian women. These findings may help to establish etiological hypotheses of cancer causation and identify spatial anomalies in cancer incidence or registration in the Islamic Republic of Iran. Our findings may also aid further research on the possible explanations for these clusters and associations.

Estimating canine cancer incidence: findings from a population-based tumour registry in northwestern Italy

BackgroundCanine cancer registry data can be put to good use in epidemiological studies. Quantitative comparison of tumour types may reveal unusual cancer frequencies, providing directions for research and generation of hypotheses of cancer causation in a specific area, and suggest leads for identifying risk factors. Here we report canine cancer incidence rates calculated from a population-based registry in an area without any known specific environmental hazard.ResultsIn its 90 months of operation from 2001 to 2008 (the observation period in this study), the population-based Piedmont Canine Cancer Registry collected data on 1175 tumours confirmed by histopathological diagnosis. The incidence rate was 804 per 100,000 dog-years for malignant tumours and 897 per 100,000 dog-years for benign tumours. Higher rates for all cancers were observed in purebred dogs, particularly in Yorkshire terrier and Boxer. The most prevalent malignant neoplasms were cutaneous mastocytoma and hemangiopericytoma, and mammary gland complex carcinoma and simplex carcinoma.ConclusionsThe Piedmont canine cancer registry is one of few of its kind whose operations have been consistently supported by long-term public funding. The registry-based cancer incidence rates were estimated with particular attention to the validity of data collection, thus minimizing the potential for bias. The findings on cancer incidence rates may provide a reliable reference for comparison studies. Researches conducted on dogs, used as sentinels for community exposure to environmental carcinogens, can be useful to detect excess risks in the incidence of malignant tumours in the human population.

Medical, ethical and personal dimensions of parent-offspring conflicts

Medical, ethical and personal dimensions of parent-offspring conflicts

Spatial Autocorrelation of Cancer Incidence in Saudi Arabia

Little is known about the geographic distribution of common cancers in Saudi Arabia. We explored the spatial incidence patterns of common cancers in Saudi Arabia using spatial autocorrelation analyses, employing the global Moran’s I and Anselin’s local Moran’s I statistics to detect nonrandom incidence patterns. Global ordinary least squares (OLS) regression and local geographically-weighted regression (GWR) were applied to examine the spatial correlation of cancer incidences at the city level. Population-based records of cancers diagnosed between 1998 and 2004 were used. Male lung cancer and female breast cancer exhibited positive statistically significant global Moran’s I index values, indicating a tendency toward clustering. The Anselin’s local Moran’s I analyses revealed small significant clusters of lung cancer, prostate cancer and Hodgkin’s disease among males in the Eastern region and significant clusters of thyroid cancers in females in the Eastern and Riyadh regions. Additionally, both regression methods found significant associations among various cancers. For example, OLS and GWR revealed significant spatial associations among NHL, leukemia and Hodgkin’s disease (r² = 0.49–0.67 using OLS and r² = 0.52–0.68 using GWR) and between breast and prostate cancer (r² = 0.53 OLS and 0.57 GWR) in Saudi Arabian cities. These findings may help to generate etiologic hypotheses of cancer causation and identify spatial anomalies in cancer incidence in Saudi Arabia. Our findings should stimulate further research on the possible causes underlying these clusters and associations.

Granger Causality—Statistical Analysis Under a Configural Perspective

The concept of Granger causality can be used to examine putative causal relations between two series of scores. Based on regression models, it is asked whether one series can be considered the cause for the second series. In this article, we propose extending the pool of methods available for testing hypotheses that are compatible with Granger causation by adopting a configural perspective. This perspective allows researchers to assume that effects exist for specific categories only or for specific sectors of the data space, but not for other categories or sectors. Configural Frequency Analysis (CFA) is proposed as the method of analysis from a configural perspective. CFA base models are derived for the exploratory analysis of Granger causation. These models are specified so that they parallel the regression models used for variable-oriented analysis of hypotheses of Granger causation. An example from the development of aggression in adolescence is used. The example shows that only one pattern of change in aggressive impulses over time Granger-causes change in physical aggression against peers.

Sternocleidomastoid pseudotumor and congenital muscular torticollis

Various hypotheses of causation of SCM pseudotumor and CMT include malposition of the fetus in utero, birth trauma, infection, and vascular injury. More recently, Davids et al have postulated it as sequelae of an intra-uterine or perinatal compartment syndrome.9 They found that MRI of infants with CMT showed signals in the SCM muscle similar to signals observed in the forearm and leg after compartment syndrome.9 Sternocleidomastoid pseudotumor and congenital muscular torticollis

Adaptive management for a turbulent future

The challenges that face humanity today differ from the past because as the scale of human influence has increased, our biggest challenges have become global in nature, and formerly local problems that could be addressed by shifting populations or switching resources, now aggregate (i.e., “scale up”) limiting potential management options. Adaptive management is an approach to natural resource management that emphasizes learning through management based on the philosophy that knowledge is incomplete and much of what we think we know is actually wrong. Adaptive management has explicit structure, including careful elucidation of goals, identification of alternative management objectives and hypotheses of causation, and procedures for the collection of data followed by evaluation and reiteration. It is evident that adaptive management has matured, but it has also reached a crossroads. Practitioners and scientists have developed adaptive management and structured decision making techniques, and mathematicians have developed methods to reduce the uncertainties encountered in resource management, yet there continues to be misapplication of the method and misunderstanding of its purpose. Ironically, the confusion over the term “adaptive management” may stem from the flexibility inherent in the approach, which has resulted in multiple interpretations of “adaptive management” that fall along a continuum of complexity and a priori design. Adaptive management is not a panacea for the navigation of ‘wicked problems’ as it does not produce easy answers, and is only appropriate in a subset of natural resource management problems where both uncertainty and controllability are high. Nonetheless, the conceptual underpinnings of adaptive management are simple; there will always be inherent uncertainty and unpredictability in the dynamics and behavior of complex social-ecological systems, but management decisions must still be made, and whenever possible, we should incorporate learning into management.

Shell Shock and Mild Traumatic Brain Injury: A Historical Review

Mild traumatic brain injury is now claimed to be the signature injury of the Iraq and Afghanistan conflicts. During World War I, shell shock came to occupy a similar position of prominence, and postconcussional syndrome assumed some importance in World War II. In this article, the nature of shell shock, its clinical presentation, the military context, hypotheses of causation, and issues of management are explored to discover whether there are contemporary relevancies to the current issue of mild traumatic brain injury. When shell shock was first postulated, it was assumed to be the product of a head injury or toxic exposure. However, subsequent clinical studies suggested that this view was too simplistic, and explanations soon oscillated between the strictly organic and the psychological as well as the behavioral. Despite a vigorous debate, physicians failed to identify or confirm characteristic distinctions. The experiences of the armed forces of both the United States and the United Kingdom during World Wars I and II led to two conclusions: that there were dangers in labeling anything as a unique "signature" injury and that disorders that cross any divide between physical and psychological require a nuanced view of their interpretation and treatment. These findings suggest that the hard-won lessons of shell shock continue to have relevance today.

Predictors of Introduction Success in the South Florida Avifauna

Biological invasions are an increasing global challenge, for which single-species studies and analyses focused on testing single hypotheses of causation in isolation are unlikely to provide much additional insight. Species interact with other species to create communities, which derive from species interactions and from the interactions of species with the scale specific elements of the landscape that provide suitable habitat and exploitable resources. I used logistic regression analysis to sort among potential intrinsic, community and landscape variables that theoretically influence introduction success. I utilized the avian fauna of the Everglades of South Florida, and the variables body mass, distance to nearest neighbor (in terms of body mass), year of introduction, presence of congeners, guild membership, continent of origin, distribution in a body mass aggregation or gap, and distance to body-mass aggregation edge (in terms of body mass). Two variables were significant predictors of introduction success. Introduced avian species whose body mass placed them nearer to a body-mass aggregation edge and further from their neighbor were more likely to become successfully established. This suggests that community interactions, and community level phenomena, may be better understood by explicitly incorporating scale.

Kinetics of cancer: a method to test hypotheses of genetic causation

BackgroundMouse studies have recently compared the age-onset patterns of cancer between different genotypes. Genes associated with earlier onset are tentatively assigned a causal role in carcinogenesis. These standard analyses ignore the great amount of information about kinetics contained in age-onset curves. We present a method for analyzing kinetics that measures quantitatively the causal role of candidate genes in cancer progression. We use our method to demonstrate a clear association between somatic mutation rates of different DNA mismatch repair (MMR) genotypes and the kinetics of cancer progression.MethodsMost experimental studies report age-onset curves as the fraction diagnosed with tumors at each age for each group. We use such data to estimate smoothed survival curves, then measure incidence rates at each age by the slope of the fitted curve divided by the fraction of mice that remain undiagnosed for tumors at that age. With the estimated incidence curves, we compare between different genotypes the median age of cancer onset and the acceleration of cancer, which is the rate of increase in incidence with age.ResultsThe direction of change in somatic mutation rate between MMR genotypes predicts the direction of change in the acceleration of cancer onset in all 7 cases (p ˜ 0.008), with the same result for the association between mutation rate and the median age of onset.ConclusionMany animal experiments compare qualitatively the onset curves for different genotypes. If such experiments were designed to analyze kinetics, the research could move to the next stage in which the mechanistic consequences of particular genetic pathways are related to the dynamics of carcinogenesis. The data we analyzed here were not collected to test mechanistic and quantitative hypotheses about kinetics. Even so, a simple reanalysis revealed significant insights about how DNA repair genotypes affect separately the age of onset and the acceleration of cancer. Our method of comparing genotypes provides good statistical tests even with small samples for each genotype.

Is it Really Worse to Have Public Health Insurance Than to Have No Insurance at All? Health Insurance and Adult Health in the United States

Using prospective cohort data from the 1979 National Longitudinal Survey of Youth, this study examines the extent to which health insurance coverage and the source of that coverage affect adult health. While previous research has shown that privately insured nonelderly individuals enjoy better health outcomes than their uninsured counterparts, the same relationship does not hold for those publicly insured through programs such as Medicaid. Because it is unclear whether this finding reflects a true causal relationship or is in fact due to selection bias on socioeconomic status and health, previous estimates of the contribution of health insurance to inequities in health may have been biased. This study attempts to disentangle these competing hypotheses of causation or selection bias by using fixed effects models with sibling clusters to corroborate--or contradict--the results of a conventional OLS regression. By controlling for unobserved factors shared by siblings, such as parental genetic influences, sibling models estimate health insurance effects that are less affected by selection bias. Findings suggest that, among the US. birth cohorts of 1957 to 1961, the negative relationship between public health insurance and health is not causal, but rather due to prior health and socioeconomic status. Conversely, the lack of health insurance coverage has a strong cumulative negative impact on adult health.

Another perspective on altitudinal limits of alpine timberlines.

Recent hypotheses of timberline causation include the possibility that limitations to growth processes may be more limiting than restrictions on photosynthetic carbon gain, and that cold soil is a primary limiting factor at high altitude. However, almost all of the supporting data for timberline causation have come from studies on older trees, with little focus on the mechanisms of seedling establishment and the growth of saplings away from the forest edge into the treeline ecotone. We describe a conceptual model of timberline migration that invokes a strong dependence on ecological facilitation, beginning with seed germination and continuing through seedling establishment and sapling growth to the stage where trees with forest-like stature form new subalpine forest at a higher altitude. In addition to protection from severe mechanical damage, facilitation of photosynthetic carbon gain and carbon processing is enhanced by plasticity in plant form and microsite preference, enabling seedling survival and sapling growth inside and through the often severe boundary layer just above the ground cover. Several forms of facilitation (inanimate, interspecific, intraspecific and structural) result in substantial increases in photosynthetic carbon gain throughout the summer growth period, leading to enhanced root growth, subsequent amelioration of drought stress, and increased seedling survival. Avoidance of low temperatures and low-temperature photoinhibition of photosynthesis may be major benefits of the facilitation, enhancing photosynthetic carbon gain and respiratory-driven growth processes. We propose that the growth of vertical stems (flagged tree forms) from krummholz mats is analogous functionally to the facilitated growth of a seedling/sapling in and away from ground cover. Increasing abundance and growth of newly established trees in the treeline ecotone generates a structural and microsite facilitation characteristic of the subalpine forest below. This is followed by the formation of new subalpine forest with forest-like trees, and a new timberline at higher altitude.

Genes, germs, and schizophrenia: an evolutionary perspective.

Literature on schizophrenia and other mental illnesses has emphasized the compatibility of evidence with genetic causation without adequately considering alternative hypotheses of disease causation. Although some studies from the mid-20th century reported associations between certain pathogens and schizophrenia, only recently has the possibility of infectious causation of schizophrenia again become an active focus of research. Infectious causation of schizophrenia is still, however, generally regarded as less well demonstrated than genetic causation. This article evaluates the evidence that has been used to support genetic and infectious causation. Our consideration of infectious causation focuses on the protozoan Toxoplasma gondii but also assesses other pathogens that may contribute to the development of some of the illnesses currently categorized as schizophrenia. Although evidence generally accepted as demonstrating genetic causation can be readily explained by hypotheses of infectious causation, some of the evidence implicating infectious causation cannot be similarly explained by genetic causation. This asymmetry indicates that a scientific approach to the causation of schizophrenia needs to put a greater emphasis on tests that distinguish hypotheses of genetic causation from those of infectious causation.

Children with specific language impairment. Laurence B. Leonard. Cambridge, MA: MIT Press, 1998. Pp. 339.

Laurence Leonard is one of the most prolific and well-respected researchers in the area of specific language impairment (SLI) in children, and he is well qualified to write a book surveying the topic. SLI is a disorder of unknown origin, which appears to have a genetic component, causing delays and disorders of language development in children of normal nonverbal intelligence with no significant medical, emotional, or sensory deficits. The primary purpose of this book is to provide a comprehensive review of research in the field of SLI, and Leonard has the minute knowledge necessary to succeed at the task. The coverage in the book reaches back to the earliest nineteenth-century descriptions of children who fit the profile and then moves forward quickly to the massive literature that has accumulated on the topic in the last 20 years. Following the introductory historical and definitional section, Leonard goes on to describe the nature of the linguistic impairment in SLI, including important cross-linguistic accounts and nonlinguistic cognitive issues. The book also covers hypotheses of causation, in a “nature versus nurture” section, and clinical issues of assessment and intervention. Part V, on theory, may be of most interest to psycholinguists who are not language disorders specialists. Overall, there is no doubt that this book is both an excellent introduction for those unfamiliar with SLI and a welcome overview and resource for experts. Leonard's knowledge is encyclopedic, his presentation erudite, and his grasp of detail unfailingly impressive.

Explaining the latitudinal gradient anomaly in ichneumonid species richness: evidence from butterflies

1. Despite the profusion of Lepidoptera and other potential hosts in the tropics, the Ichneumonidae are not more species‐rich in the lowland tropics than in temperate communities. Alternate but partially complementary hypotheses emphasizing resource fragmentation, predation, or chemical defence have been proposed to explain this paradox. 2. Because different diversity gradients occur in the various subgroups of the Ichneumonidae, as well as among their hosts, general explanations are unlikely to account for this ‘anomalous diversity.’ Hypotheses of ecological causation are best tested at the taxonomic level where the pattern of interest applies. 3. Phylogenetic trends in the distribution, abundance, and palatability of butterflies (Papilionoidea), a group that increases dramatically in species richness towards the tropics, are presented as a case study for evaluating hypotheses of parasitoid species richness. Evidence is presented that supports the ‘nasty host hypothesis’ as an explanation for the lack of diversity of associated parasitoids. 4. An examination of hypotheses and the approaches used to test them suggests that the nasty‐host hypothesis is best supported by the limited evidence available, while evidence in favour of other hypotheses is either lacking or ambiguous. In particular, use of the koinobiont/idiobiont dichotomy and parasitoid assemblage‐size comparisons may result in contradictory conclusions.

Incidence of post-asphyxial encephalopathy (PAE) in term neonates: a hypothesis of “precocious postmaturity” as a risk factor. 959

Background: The spectrum of recognized causes of PAE varies from pre-eclampsia to shoulder dystocia, but the incidence of these clear causes of PAE is not known. Objectives: (1)To determine the proportion of a cohort of term newborns with PAE in which a cause or risk factor can be clearly identified and (2) to generate hypotheses of causation in those with no recognizable causation or factors. Study design: A cohort of all term infants with PAE (ACOG) admitted to a regional level-III NICU for outborn infants, from 1990 to 1993 was retrospectively studied. Recognized causes and risk factors for asphyxia were identified. Causes were divided into three groups(1)Clear causes (eg. abruptio placentae);(2)Risk factors present (eg. oligohydramnios, cigarette smoking); (3) No causes or risk factors. Exclusion criteria: Haemorrhagic shock, septic shock & head trauma.

Epidemiology of biliary atresia: a population-based study.

Biliary atresia is the leading cause of extrahepatic obstructive jaundice in the newborn and is the single most frequent indication for liver transplantation in children. The cause of biliary atresia is unknown, although several mechanisms have been postulated to explain the inflammatory process that obliterates the bile ducts. Most interest has been directed toward viral infections. Information about the epidemiologic characteristics of biliary atresia in well-defined populations is lacking but is essential for developing and addressing hypotheses of causation for the disease. Infants with biliary atresia were identified in metropolitan Atlanta from 1968 through 1993 by a population-based birth defects surveillance system that ascertains infants with serious birth defects in the first year of life using active case ascertainment. Birth prevalence rates were analyzed for spatial and temporal clustering and effects attributable to county of residence, sex, race, maternal age, parity, and birth weight. Logistic regression was used to study the independent effects of the risk factors and to look for interactions. Fifty-seven infants with biliary atresia were identified, for a rate of 0.73 per 10,000 live births. There was significant seasonal clustering of the disease, with rates three times higher from December through March compared with rates from April through July. Rates were significantly higher among nonwhite infants compared with white infants (0.96 vs 0.44 per 10,000 live births) and infants born at term with low birth weights (<2500 g) compared with infants born at term with normal birth weights (> or = 2500 g) (2.62 vs 0.75 per 10,000 live births). Our study is the first in the United States to describe the epidemiologic characteristics of biliary atresia using a population-based approach. The demonstration of significant seasonal clustering provides support for theories that biliary atresia may be caused by environmental exposure (consistent with a viral cause) during the perinatal period.

The reenchantment of geomorphology

Much of modern Geomorphology lacks the enchantment that the science possessed a century ago. Practical and philosophical impediments are thwarting modern attempts to achieve a satisfying understanding of landforms and their genesis. In recent years, even the security of geomorphologists' academic bases has been threatened within the cognate disciplines of Geography and Geology. During the 1960s these fields experienced so-called “scientific revolutions,” which many geomorphologists either uncritically embraced or assumed to be irrelevant. While commendable in spirit, progressive initiatives to establish research traditions in landscape evolution, climatic geomorphology, and process studies all encountered fundamental limitations as unifying themes. More disturbing are ideological impositions that advocate geomorphological concentration on timeless, theoretical, or utilitarian problems. While facilitating precision of explanation and prediction, various geoideological bandwagons may stifle creativity, insight, and intellectual satisfaction. Most insidious is the substitution of elegantly structured methodology and theory for spontaneity, serendipity, and common sense. Hope for the reenchantment of Geomorphology lies in a new connectedness to nature that will facilitate the identification of anomalies and the formulation of outrageous hypotheses of causation. In the words of William Morris Davis, “…violence must be done to many of our accepted principles.” Examples of such ideas may be found in fringe areas of the discipline, including planetary geomorphology, tectonic geomorphology, and denudation chronology with emphasis on ancient paleosurfaces. Geomorphologists should consider inverting their belief that they are achieving progressive (timebound) understanding of invariant (timeless) laws in nature. Rather, they may choose a geophysiological view in which the richness of natural history is revealed in a timeless conversation with the Earth.