The influence of larval density, food availability and habitat longevity on the life history and population growth rate of the midge Chironomus riparius

Despite long-standing interest in the forms and mechanisms of density dependence, these are still imperfectly understood. However, in a constant environment an increase in density must reduce per capita resource availability, which in turn leads to reduced survival, fecundity and somatic growth rate. Here we report two population experiments examining the density dependent responses under controlled conditions of an important indicator species, Chironomus riparius. The first experiment was run for 35 weeks and was started at low density with replicate populations being fed three different rations. Increased ration reduced generation time and increased population growth rate (pgr) but had no effect on survival, fecundity and female body weight in the first generation. In the second generation there was a six-fold increase in generation time, presumably due to the greatly reduced per capita resource availability as the estimated initial densities of the second generation were 300 times greater than the first. Juvenile survival to emergence, fecundity, adult body weight and pgr declined by 90%, 75%, 35% and 99%, respectively. These large between-generation effects may have obscured the effects of the threefold variation in ration, as only survival to emergence significantly increased with ration in the second generation. These results suggest that some chironomid larvae survive a reduction in resource availability by growing more slowly. In the ephemeral habitats sometimes occupied by C. riparius, the effects of population density may depend crucially on the longevity of the environment. A second experiment was therefore performed to measure pgr from six different starting densities over an eight-week period. The relationship between pgr and density was concave, viewed from above. At densities above 16 larvae per cm(2), less than 1% of the population emerged and no offspring were produced. Under the conditions of experiment 2 - an 8-week habitat lifespan carrying capacity was estimated as 8 larvae per cm(2).

Genomic evidence for the Pleistocene and recent population history of Native Americans

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative “Paleoamerican” relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.

Brief history of the IDRC-CELADE relationship in the development of the Latin American Population Documentation System (DOCPAL)

El documento contiene una breve resena sobre las relaciones entre el IDRC y CELADE con miras al desarrollo del sistema latinoamericano de documentacion en poblacion (DOCPAL)

The Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic attack (PERFORM) study: baseline characteristics of the population

BACKGROUND: The Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic attack (PERFORM) study is an international double-blind, randomized controlled trial designed to investigate the superiority of the specific TP receptor antagonist terutroban (30 mg/day) over aspirin (100 mg/day), in reducing cerebrovascular and cardiovascular events in patients with a recent history of ischemic stroke or transient ischemic attack. Here we describe the baseline characteristics of the population. METHODS AND RESULTS: Parameters recorded at baseline included vital signs, risk factors, medical history, and concomitant treatments, as well as stroke subtype, stroke-associated disability on the modified Rankin scale, and scores on scales for cognitive function and dependency. Eight hundred and two centers in 46 countries recruited a total of 19,119 patients between February 2006 and April 2008. The population is evenly distributed and is not dominated by any one country or region. The mean +/- SD age was 67.2 +/- 7.9 years, 63% were male, and 83% Caucasian; 83% had hypertension, and about half the population smoked or had quit smoking. Ninety percent of the qualifying events were ischemic stroke, 67% of which were classified as atherothrombotic or likely atherothrombotic (pure or coexisting with another cause). Modified Rankin scale scores showed slight or no disability in 83% of the population, while the scores on the Mini-Mental State Examination, Isaacs' Set Test, Zazzo's Cancellation Test, and the instrumental activities of daily living scale showed a good level of cognitive function and autonomy. CONCLUSIONS: The PERFORM study population is homogeneous in terms of demographic and disease characteristics. With 19,119 patients, the PERFORM study is powered to test the superiority of terutroban over aspirin in the secondary prevention of cerebrovascular and cardiovascular events in patients with a recent history of ischemic stroke or transient ischemic attack.

Heart rate is a prognostic risk factor for myocardial infarction: a post hoc analysis in the PERFORM (Prevention of cerebrovascular and cardiovascular Events of ischemic origin with teRutroban in patients with a history oF ischemic strOke or tRansient ischeMic attack) study population

BACKGROUND Elevated resting heart rate is known to be detrimental to morbidity and mortality in cardiovascular disease, though its effect in patients with ischemic stroke is unclear. We analyzed the effect of baseline resting heart rate on myocardial infarction (MI) in patients with a recent noncardioembolic cerebral ischemic event participating in PERFORM. METHODS We compared fatal or nonfatal MI using adjusted Cox proportional hazards models for PERFORM patients with baseline heart rate <70 bpm (n=8178) or ≥70 bpm (n=10,802). In addition, heart rate was analyzed as a continuous variable. Other cerebrovascular and cardiovascular outcomes were also explored. RESULTS Heart rate ≥70 bpm was associated with increased relative risk for fatal or nonfatal MI (HR 1.32, 95% CI 1.03-1.69, P=0.029). For every 5-bpm increase in heart rate, there was an increase in relative risk for fatal and nonfatal MI (11.3%, P=0.0002). Heart rate ≥70 bpm was also associated with increased relative risk for a composite of fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (excluding hemorrhagic death) (P<0001); vascular death (P<0001); all-cause mortality (P<0001); and fatal or nonfatal stroke (P=0.04). For every 5-bpm increase in heart rate, there were increases in relative risk for fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (4.7%, P<0.0001), vascular death (11.0%, P<0.0001), all-cause mortality (8.0%, P<0.0001), and fatal and nonfatal stroke (2.4%, P=0.057). CONCLUSION Elevated heart rate ≥70 bpm places patients with a noncardioembolic cerebral ischemic event at increased risk for MI.

Genetics and the population history of Europe

Analysis of genetic variation among modern individuals is providing insight into prehistoric events. Comparisons of levels and patterns of genetic diversity with the predictions of models based on archeological evidence suggest that the spread of early farmers from the Levant was probably the main episode in the European population history, but that both older and more recent processes have left recognizable traces in the current gene pool.

Sketches of Algiers, political, historical, and civil : containing an account of the geography, population, government, revenues, commerce, agriculture, arts, civil institutions, tribes, manners, languages, and recent political history of that country /

Mode of access: Internet.

Present state of the Spanish colonies : including a particular report of Hispa�nola, or the Spanish part of Santo Domingo; with a general survey of the settlements on the south continent of America, as relates to history, trade, population, customs, manners, &c., with a concise statement of the sentiments of the people on their relative situation to the mother country, &c. /

Printer varies: "H. Bryer, Printer, Bridge-Street, Blackfriars, London."--Vol. I, p. 384; "C. Stower, Printer, Paternoster Row, London."-- Vol. II, p. 356.

Sketches of Algiers, political, historical, and civil; containing an account of the geography, population, government, revenues, commerce, agriculture, arts, civil institutions, tribes, manners, languages, and recent political history of that country /

Xerox reproduction, 1975, 2 pages to a leaf.

An account of travels into the interior of southern Africa, in the years 1797 and 1798 : including cursory observations on the geology and geography of the southern part of that continent ; the natural history of such objects as occurred in the animal, vegetable, and mineral kingdoms ; and sketches of the physical and moral characters of the various tribes of inhabitants surrounding the settlement of the Cape of Good Hope. To which is annexed, a description of the present state, population, and produce of that extensive colony ; with a map constructed entirely from actual observations made in the course of the travels.

Vol. 2 has title: An account of travels into the interior of Southern Africa; in which is considered, the importance of the Cape of Good Hope to the different European powers, as a naval and military station ; as a territorial acquisition and commercial emporium in time of peace : with a statistical sketch of the whole colony ; comp. from authentic documents.

An account of travels into the interior of southern Africa, in the years 1797 and 1798: : including cursory observations on the geology and geography of the southern part of that continent; the natural history of such objects as occurred in the animal, vegetable, and mineral kingdoms; and sketches on the physical and moral characters of the various tribes of inhabitants surrounding the settlement of the Cape of Good Hope. : To which is annexed, a description of the present state, population and produce of that extensive colony; with a map, constructed entirely from actual observations, made in the course of the travels. /

Publisher's advertisement, p. [387].

The Strangers' guide to the islands of Guernsey and Jersey : embracing a brief history of their situation, extent, population, laws, customs, public buildings, amusements, antiquities, climate, and productions, vegetable and mineral : together with a complete commercial directory of both islands : coins, weights, measures, &c. : embellished with maps of both islands.

Goldsmiths'-Kress no. 27880.

A treatise on the records of the creation and on the moral attributes of the creator : with particular reference to the Jewish history, and to the consistency of the principle of population with the wisdom and goodness of the deity /

Mode of access: Internet.