L’environnement tardiglaciaire du Yukon septentrional, Canada

Le site des grottes du Poisson-Bleu, localisé sur une assise à calcaires dévoniens au sein de la forêt boréale du Yukon septentrional, a fourni, en plus d'un abondant matériel paléontologique et de quelques données archéologiques, des sédiments pollinifères. Le diagramme pollinique d'un dépôt consistant en un loess tardiglaciaire recouvert d'un humus à cailloutis d'âge holocène présente un assemblage inférieur dominé par des herbes de toundra et un assemblage supérieur dominé par l'épinette et l'aulne. Grâce à ces données ainsi qu'à celles tirées de sites avoisinants, il est possible d'en arriver à une reconstitution de la végétation dont les phases importantes sont les suivantes: une période tardiglaciaire, de 16 000 à 12 000 BP, caractérisée par une toundra herbacée, éparse sur les hauts plateaux et par des marécages à laiches et à graminées dans les basses terres; ultérieurement, au cours de l'Holocène, le phénomène d'entourbement du sol et le développement de bruyères et de pessières, conséquences d'un climat plus chaud.The Bluefish Caves site, located on a scarp of Devonian limestone in the northern boreal forest of the Yukon, has yielded pollen-bearing sediments in addition to abundant paleontological and some archaeological data. A pollen diagram based on samples of late-glacial lcess overlain by Holocene humus shows two main pollen assemblages, the lower dominated by herbs and dwarf shrubs and the upper by spruce and alder. Based on these results, but also drawing on recent findings from other sites in N. Yukon, we offer the following reconstruction of the vegetation history of the region. The vegetation of the late-glacial period, from 16 000 to 12 000 BP, was a sparse herb tundra on upland surfaces and a complex of sedge-grass marshes with willow on lowlands. There was a notable change in cover at the beginning of the Holocene when spruce forest spread to all upland surfaces except the highest ridges, and palu-dification in the lowlands resulted in the spread of bog and mire communities

Sexual risk behavior and pregnancy in detained adolescent females: a study in Dutch detention centers

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to investigate the lifetime prevalence of teenage pregnancy in the histories of detained adolescent females and to examine the relationship between teenage pregnancy on the one hand and mental health and sexuality related characteristics on the other.</p> <p>Methods</p> <p>Of 256 admitted detained adolescent females aged 12–18 years, a representative sample (N = 212, 83%) was examined in the first month of detention. Instruments included a semi-structured interview, standardized questionnaires and file information on pregnancy, sexuality related characteristics (sexual risk behavior, multiple sex partners, sexual trauma, lack of assertiveness in sexual issues and early maturity) and mental health characteristics (conduct disorder, alcohol and drug use disorder and suicidality).</p> <p>Results</p> <p>Approximately 20% of the participants reported having been pregnant (before detention), although none had actually given birth. Sexuality related characteristics were more prevalent in the pregnancy group, while this was not so for the mental health characteristics. Age at assessment, early maturity, sexual risk behavior, and suicidality turned out to be the best predictors for pregnancy.</p> <p>Conclusion</p> <p>The lifetime prevalence of pregnancy in detained adolescent females is high and is associated with both sexuality related risk factors and mental health related risk factors. Therefore, prevention and intervention programs targeting sexual risk behavior and mental health are warranted during detention.</p

Characteristics of Sexual Abuse in Childhood and Adolescence Influence Sexual Risk Behavior in Adulthood

Childhood and adolescent sexual abuse has been associated with subsequent (adult) sexual risk behavior, but the effects of force and type of sexual abuse on sexual behavior outcomes have been less well-studied. The present study investigated the associations between sexual abuse characteristics and later sexual risk behavior, and explored whether gender of the child/adolescent moderated these relations. Patients attending an STD clinic completed a computerized survey that assessed history of sexual abuse as well as lifetime and current sexual behavior. Participants were considered sexually abused if they reported a sexual experience (1) before age 13 with someone 5 or more years older, (2) between the ages of 13 and 16 with someone 10 or more years older, or (3) before the age of 17 involving force or coercion. Participants who were sexually abused were further categorized based on two abuse characteristics, namely, use of penetration and force. Analyses included 1177 participants (n=534 women; n=643 men). Those who reported sexual abuse involving penetration and/or force reported more adult sexual risk behavior, including the number of lifetime partners and number of previous STD diagnoses, than those who were not sexually abused and those who were abused without force or penetration. There were no significant differences in sexual risk behavior between nonabused participants and those who reported sexual abuse without force and without penetration. Gender of the child/adolescent moderated the association between sexual abuse characteristics and adult sexual risk behavior; for men, sexual abuse with force and penetration was associated with the greatest number of episodes of sex trading, whereas for women, those who were abused with penetration, regardless of whether the abuse involved force, reported the most episodes of sex trading. These findings indicate that more severe sexual abuse is associated with riskier adult sexual behavior

Cheek Tooth Morphology and Ancient Mitochondrial DNA of Late Pleistocene Horses from the Western Interior of North America: Implications for the Taxonomy of North American Late Pleistocene Equus

Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study