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Cyanobacteria are photoautotrophic organisms which occur in aquatic and terrestrial environments. They have the potential to produce toxins which pose a threat to human and animal health. This review covers the global distribution of the common cyanotoxins and related poisoning cases. A total of 468 selected articles on toxic cyanobacteria, dating from the earliest records until 2018, were reviewed. Most of the articles were published after 2000 (72%; 337 out of 468), which is consistent with the recent growth in interest in the analysis, toxinology and ecotoxicology of cyanotoxins. Animal and/or human poisoning cases were described in more than a third of the overall publications (38%; 177 out of 468). The reviewed publications showed that there were 1118 recorded identifications of major cyanotoxins in 869 freshwater ecosystems from 66 countries throughout the world. Microcystins were the most often recorded cyanotoxins worldwide (63%; 699 out of 1118), followed by cylindrospermopsin (10%; 107 out of 1118), anatoxins (9%; 100 out of 1118), and saxitoxins (8%; 93 out of 1118). Nodularins were the most rarely recorded cyanotoxins (2%; 19 out of 1118); however, there were also reports where cyanotoxins were not analysed or specified (9%; 100 out of 1118). The most commonly found toxic cyanobacterial genera were Microcystis spp. (669 reports), Anabaena spp. (397 reports), Aphanizomenon spp. (100 reports), Planktothrix spp. (98 reports), and Oscillatoria spp. (75 reports). Furthermore, there were 183 recorded cyanotoxin poisonings of humans and/or animals. Out of all toxic cyanobacterial blooms reviewed in this paper, the highest percentage of associated poisonings was found in North and Central America (39%; 69 cases out of 179), then Europe (20%; 35 out of 179), Australia including New Zealand (15%; 27 out of 179), and Africa (11%; 20 out of 179), while the lowest percentage was related to Asia (8%; 14 cases out of 179) and South America (8%; 14 cases out of 179). Events where only animals were known to have been affected were 63% (114 out of 182), whereas 32% (58 out of 182) of the investigated events involved only humans. A historical overview of human and animal poisoning episodes associated with cyanobacterial blooms is presented. Further, geographical data on the occurrence of cyanotoxins and related poisonings based on the available literature are shown. Some countries (mainly European) have done very intensive research on the occurrence of toxic cyanobacteria and cyanotoxins, and reported related ecotoxicological observations, while in some countries the lack of data is apparent. The true global extent of cyanotoxins and associated poisonings is likely to be greater than found in the available literature, and it can be assumed that ecotoxicological and hygienic problems caused by toxic cyanobacteria may occur in more environments.

"This paper takes several surveys of the literature concerning migration research as its starting point and directs the reader toward a number of potentially fruitful lines for future research. Major sections include one on modeling migrant choice in which the pros and cons of using gross versus net migration measures are discussed. A second introduces and discusses the concept of a 'spatial' choice set, which has the potential to be implemented with laboratory experimental techniques. The third involves a wide-ranging discussion of new directions in modeling the interrelationships between employment and migration." The primary geographical focus is on the United States., (excerpt)

"In determining metropolitan population size and changes therein, urban theorists traditionally have focused on the number of occupied dwelling units or households and have assumed that these households are equal in size. This paper argues that average household size is an indicator of how intensively the housing stock is utilized and that there is substantial variation in household size across SMSAs in the U.S. The experience of 150 SMSAs is examined for the time period 1960 to 1970. The study model attributes varying household size to differentials in birth and divorce rates, racial composition and age of housing. Ramifications of recent household size declines involve the internal spatial organization of metropolitan areas and the Census controversy with cities over alleged undercounts of urban populations.", (excerpt)

"This paper is a comparison of two contrasting methods for projecting population at the regional and state levels. A projection of the U.S. Bureau of the Census employs standard demographic methods, while the population projection by Data Resources, Inc., is based on economic opportunity. The methodological differences between these two projections are discussed, and the projections for the year 2000 are compared....The U.S. Bureau of the Census projects population decline in the Northeast and rapid growth in the West while Data Resources, Inc., projects some population growth in the Northeast and less rapid growth in the West.", (excerpt)

"This paper has examined the impact of climate on migration. It has compared the results that are obtained when various indicators of climatic conditions, both those which have been used in the literature and those which have not, are included in a regression used to explain migration behavior. The results suggest that individuals do indeed consider climatic conditions in different areas when deciding where to live; people generally prefer areas which have moderate climates to areas which have either extremely hot or extremely cold climates. The results also indicate that the climate variables which yield the best results are generally those which have not been used in the literature." The study is based on U.S. data concerning in-migration to 36 SMSAs between 1960 and 1970., (excerpt)

"This paper presents and tests a regression-based model of black interstate migration. Explanatory variables include characteristics of origins and destinations, distance, and two migrant stock measures. The model is tested using black interstate migration flows published by the U.S. Bureau of the Census for 1965-70 and 1975-80." The emphasis is on the determinants of black migration, particularly for the period 1975-1980., (excerpt)

"This paper examines the impact of age on migration by providing estimates of identically specified migration equations for each of six age groups. Hypothesized effects of age on the relative importance of various explanatory variables are developed from a model viewing migration as an investment decision." This model is then tested empirically using U.S. data on inter-regional migration between 1965 and 1970. "The effects of economic opportunity differentials on migration are found to decline sharply with age. Lagged migration, the 'friends and relatives effect,' is found to be the most significant explanatory variable in all age group equations. Past migration is the only variable found to significantly influence the migration of persons over 65.", (excerpt)