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Background Interference competition among sympatric carnivores can potentially influence species viability through population reduction or extinction, and has important implications for the structure and function of large carnivore communities. Carnivores may mitigate the risk of competition through fine-scaled spatial or temporal separation that subsequently affects predator interactions and community dynamics. Simultaneous telemetry records of sympatric carnivores allows for an in-depth analysis of individual space-use patterns and association metrics. Together with the application of a novel method for analyzing fine-scaled movement interactions, quantifying spatiotemporal separation between predator species provides insight into understanding the dynamic interactions among co-existing carnivores. Methods We analyzed GPS satellite relocation data from 17 lions (Panthera leo) and 14 spotted hyenas (Crocuta crocuta) over four-years, across two distinct ecosystems. Data were used to investigate lion and hyena space-use patterns and fine-scale movement of intra- and interspecific dyads. We assessed home range overlap among lion and spotted hyena, and applied a novel T-LoCoH (Time-Local Convex Hull) method to study species range overlaps from an interaction perspective. We also present the first application of our dyadic movement methodology to characterize the relative movement of lion and spotted hyena dyads. Results Heterospecific home-range overlap between lion prides and hyena clans was considerably greater than conspecific pride-pride and clan-clan overlap. Spatial overlaps among heterospecific competitors occurred mainly at the edge of home ranges, and were indicative of joint, contemporaneous space-use. Close encounters between individual lion and hyena provided opportunities to assess and compare interactions within home ranges and, even, core areas across seasons and ecosystems. At distances

The objective of our study was identification and molecular characterization of piroplasms and rickettsias occurring in brown (Parahyaena brunnea) and spotted hyaenas (Crocuta crocuta) from various localities in Namibia and South Africa. Whole blood (n = 59) and skin (n = 3) specimens from brown (n = 15) and spotted hyaenas (n = 47) were screened for the presence of Babesia, Theileria, Ehrlichia and Anaplasma species using the reverse line blot (RLB) hybridization technique. PCR products of 52/62 (83.9%) of the specimens hybridized only with the Theileria/Babesia genus-specific probes and not with any of the species-specific probes, suggesting the presence of a novel species or variant of a species. No Ehrlichia and/or Anaplasma species DNA could be detected. A parasite 18S ribosomal RNA gene of brown (n = 3) and spotted hyaena (n = 6) specimens was subsequently amplified and cloned, and the recombinants were sequenced. Homologous sequence searches of databases indicated that the obtained sequences were most closely related to Babesia lengau, originally described from cheetahs (Acinonyx jubatus). Observed sequence similarities were subsequently confirmed by phylogenetic analyses which showed that the obtained hyaena sequences formed a monophyletic group with B. lengau, B abesia conradae and sequences previously isolated from humans and wildlife in the western USA. Within the B. lengau clade, the obtained sequences and the published B. lengau sequences were grouped into six distinct groups, of which groups I to V represented novel B. lengau genotypes and/or gene variants. We suggest that these genotypes cannot be classified as new Babesia species, but rather as variants of B. lengau. This is the first report of occurrence of piroplasms in brown hyaenas.

The authors conducted a survival analysis to determine the effect of poverty on mortality in a national sample of blacks and whites, 25 to 74 years of age (the first National Health and Nutrition Examination Survey (NHANES-1) and NHANES-I Epidemiologic Follow-up Study). They estimated the proportion of mortality associated with poverty during 1971–1984 and in 1991 by calculating population attributable risk and assessed confounding by major known risk factors (e.g., smoking, cholesterol levels, and physical inactivity). In 1973, 6.0 percent of U.S. mortality among black and white persons 25 to 74 years of age was attributable to poverty; in 1991, the proportion was 5.9 percent. In 1991, rates of mortality attributable to poverty were lowest for white women, 2.2 times as high for white men, 8.6 times as high for black men, and 3.6 times as high for black women. Adjustment for all these potential confounders combined had little effect on the hazard ratio among men, but reduced the effect of poverty on mortality among women by 42 percent. The proportion of mortality attributable to poverty among U.S. black and white adults has changed only minimally in recent decades. The effect of poverty on mortality must be largely explained by conditions other than commonly recognized risk factors.

We conducted a survival analysis to determine the effect of poverty on mortality in a national sample of blacks and whites 25-74 years of age (in the First National Health and Nutrition Examination Survey and National Health Examination Follow-up Survey). We estimated the proportion of mortality associated with poverty from 1973 through 1984 and in 1991 by calculating the population attributable risk. We assessed confounding by major known risk factors, such as smoking, serum total cholesterol, and inactivity. In 1973, 16.1% of U.S. mortality among black and white persons 25-74 years of age was attributable to poverty; in 1991, the proportion increased to 17.7%. In 1991, the population attributable risk of poverty on mortality was lowest for white women, 1.7 times higher for white men, 2.6 times higher for black women, and 3.6 times higher for black men. Potential confounders explained 40% of the effect of poverty on mortality among women. The proportion of mortality attributable to poverty among U.S. black and white adults has increased in recent decades and is comparable to that attributable to cigarette smoking. The effect of poverty on mortality must be explained by conditions other than commonly recognized risk factors.

In the previous lesson on Measures of Effect, we focused exclusively on ratio measures of effect. In this lesson, we consider difference measures of effect and other related measures that allow the investigator to consider the potential public health impact of the results obtained from an epidemiologic study.

In epidemiologic studies, we compare disease frequencies of two or more groups using a measure of effect. We will describe several types of measures of effect in this chapter. The choice of measure typically depends on the study design being used.

This lesson considers how the assessment of confounding gets somewhat more complicated when controlling for more than one risk factor. In particular, when several risk factors are being controlled, we may find that considering all risk factors simultaneously may not lead to the same conclusion as when considering risk factors separately. We have previously (Lesson 10) argued that the assessment of confounding is not appropriate for variables that are effect modifiers of the exposure-disease relationship under study. Consequently, throughout this lesson, our discussion of confounding will assume that none of the variables being considered for control are effect modifiers (i.e., there is no interaction between exposure and any variable being controlled).

The field of epidemiology was initially concerned with providing a methodological basis for the study and control of population epidemics. Now, however, epidemiology has a much broader scope, including the study of both acute and chronic diseases, the quality of health care, and mental health problems. As the focus of epidemiologic inquiry has broadened, so has the methodology. In this overview lesson, we describe examples of epidemiologic research and introduce several important methodologic issues typically considered in such research.

A key stage of epidemiologic research is the study design. This is defined to be the process of planning an empirical investigation to assess a conceptual hypothesis about the relationship between one or more exposures and a health outcome. The purpose of the study design is to transform the conceptual hypothesis into an operational hypothesis that can be empirically tested. Since all study designs are potentially flawed, it is therefore important to understand the specific strengths and limitations of each design. Most serious problems or mistakes at this stage cannot be rectified in subsequent stages of the study.

Suppose we are studying whether there is a link between exposure to a toxic chemical and the development of lung cancer in a chemical industry. To answer this question properly, we would want to isolate the effect of the chemical from the possible influence of other variables, particularly age and smoking status, two known risk factors for lung cancer. That is, our goal is to determine whether or not exposure to the chemical contributes anything over and above the effects of age and smoking to the development of lung cancer.

(1993). “Let Them Eat Cake”: The Mythical Marie Antoinette and the French Revolution. The Historian: Vol. 55, No. 4, pp. 709-724.

This study examined the dominant factors that predict the utilization of services by 129 identified elder abuse victims who reside in the community. Utilizing the Andersen Model, services accepted or rejected were analyzed from individual, family and environmental perspectives. Results indicated that service utilization is related to three "need" factors: (1) Victim has cognitive and ADL impairments, (2) Victim has poor health status (self rated), and (3) The abuser is financially dependent on the victim and is also the primary caregiver of the victim. "Enabling" factor (1) Victim lives alone. "Predisposing" factors (1) Abuser is substance abuser and (2) Abuser is female. A great proportion of the elder abuse victims in this study accepted services from an agency that provided a single entry point into the service system and had highly trained personnel utilizing a case management approach.

We examined consistency in the classification of ancestry by self, proxy, interviewer, and funeral director (on a death certificate) in a sample of the U.S. population--the First National Health and Nutrition Examination Survey and Epidemiologic Follow-up. Among study subjects for whom comparable ethnic identity options were available at both interviews, 58% of subjects specified the same identity at two times. Persons who specified four different ethnic backgrounds were 3.4 times as likely to change their identity over time as persons specifying only one background. Self-classification of ancestry at initial interview was consistent with proxy reports at follow-up for 55% of subjects for whom proxy information was available. Comparison of the self-classification of ancestry with the classification of race by interviewers and by funeral directors indicates high consistency for Whites and Blacks and low consistency for American Indians. The "measurement" of ancestry (that is, race or ethnicity) is critical to the understanding and elimination of differences in health status among racial/ethnic populations, but the low reliability of these measures over time and across observers complicates the analysis and interpretation of health statistics by ancestry, particularly for populations other than White or Black.

From January to April, 1990, 695 measles cases were reported to the Puerto Rico Health Department; there were 12 measles-associated deaths (case fatality ratio, 17/1000), more than in any year since 1967. We conducted a case-control study of risk factors for severe measles. We identified 16 children (ages 5 to 34 months) with severe measles and selected children with nonsevere measles as controls (39 hospitalized and 38 nonhospitalized). Controls were frequency matched to severe measles cases by region of residence. One case and two controls had been vaccinated. An underlying illness was present in 50% of cases and 16% of nonhospitalized controls (Mantel-Haenszel weighted odds ratio 5.3; 95% confidence interval 1.4, 20.2). In a multivariate analysis cases were significantly more likely than hospitalized controls to be from families with an annual income of$5000 (odds ratio (OR), 26.9), to have a mother without a high school degree (OR 11.1), to be anemic (hemoglobin10 g/dl) (OR 15.9) and have an underlying illness (OR 18.3). During measles outbreaks preventing severe illness requires aggressive control measures and strategies to increase vaccine coverage of children with underlying illnesses and of low socioeconomic status.

The effects of a prescribed winter bum on two species of pitcher plant, Sarracenia alata and S. psittacina, were investigated by comparing changes in variables measured before and after the fire in randomly selected plots in a Louisiana savanna. Burned plots showed an increase in foliage and unburned plots showed a decrease in foliage, as measured in total number of leaves (>25 cm) for S. alata and in total cover for S. psittacina. For S. alata, the gain in foliage in the burned plots was less than the loss in foliage in the unburned plots, but for S. psittacina the gain in burned plots was greater than the loss in unburned plots. Seedling recruitment of S. alata after the fire was exponentially related to the number of floral scapes produced in the year before the fire and was greater in burned plots than in unburned plots. Number of floral scapes of both pitcher plant species decreased in the year after the fire, but the decrease occurred equally in burned and unburned plots. THROUGHOUT the Gulf Coastal Plain of the southeastern United States are numerous discontinuous bogs, savannas, and shrub bogs (pocosins) which support carnivorous plants.

Ever since the egregious and tragic failure of Napoleon III's attempt to place the Archduke Ferdinand Maximilian on a throne in Mexico, virtually all but the participants have tended to view his enterprise as a species of folly. Whether they believe his motives to have been quixotic or meanly avaricious, historians generally agree in blaming ignorance as the basic cause of the fiasco. Instead of informing himself accurately on the true conditions in Mexico, the argument runs, the emperor allowed himself to be hoodwinked by a handful of self-serving emigres and deluded by the clerical enthusiasms of the Empress Eugenie. "Without a shred of evidence," wrote a prominent British historian of the Second Empire,' he persuaded himself of the existence of a strong monarchist movement that would welcome a prince as a liberator. "He was badly informed because he did nothing to inform himself well," concludes the foremost French authority on the Mexican expedition.2 Hence he failed to recognize

“Listen to what I say, sir. We made one mistake, and one only: we ought not to have hoisted the flag of the principle of nationality. It was that, and that alone, which was our undoing. The whole disaster sprang from that!”1

The “Count de Saligny,” as he was usually known to his contemporaries and as he has gone down in history, has long been a vexatious but enigmatic figure. Wherever he went there was trouble, sometimes even tragedy; yet whence he came, why he acted as he did, and where and how he ended his days could not be fathomed. His career has been known only in isolated and ragged fragments. To American historians of the western frontier he appears from the blue as the unpopular and unsuccessful charge d’affaires to the Republic of Texas. Having acquired notoriety in Texas and disapprobation in the French Foreign Ministry for his role in an undignified episode known as the “Pig War,” he disappeared from sight when Texas became part of the United States in 1846. Specialists in the Second Empire of France or of Latin American history encounter him some fifteen years later in his career when, unaccountably, he was designated minister to Mexico. For a few years they have ample evidence to trace his malignant work in urging French intervention and to describe the incorrigible behavior that led to his recall and disgrace in 1863. They have puzzled in vain over the reasons for this aberrant and destructive mission. Yet long before the French expedition to Mexico and the attempt to establish a monarchy in Mexico had born their tragic fruits the “Count de Saligny” had returned to France to vanish once more without trace.