ABSTRACT
Over the past decades, rest-frame ultraviolet (UV) observations have provided large samples of UV luminous galaxies at redshift (z) greater than 6 (refs. 1-3), during the so-called epoch of reionization. While a few of these UV-identified galaxies revealed substantial dust reservoirs4-7, very heavily dust-obscured sources at these early times have remained elusive. They are limited to a rare population of extreme starburst galaxies8-12 and companions of rare quasars13,14. These studies conclude that the contribution of dust-obscured galaxies to the cosmic star formation rate density at z > 6 is sub-dominant. Recent ALMA and Spitzer observations have identified a more abundant, less extreme population of obscured galaxies at z = 3-6 (refs. 15,16). However, this population has not been confirmed in the reionization epoch so far. Here, we report the discovery of two dust-obscured star-forming galaxies at z = 6.6813 ± 0.0005 and z = 7.3521 ± 0.0005. These objects are not detected in existing rest-frame UV data and were discovered only through their far-infrared [C II] lines and dust continuum emission as companions to typical UV-luminous galaxies at the same redshift. The two galaxies exhibit lower infrared luminosities and star-formation rates than extreme starbursts, in line with typical star-forming galaxies at z ≈ 7. This population of heavily dust-obscured galaxies appears to contribute 10-25% to the z > 6 cosmic star formation rate density.
ABSTRACT
The purpose of the study was to investigate the effects of maternal presence or absence and childrearing practices on young children's response to an injection. One hundred thirty-eight mothers and their children, who were attending health screening clinic, were assigned to one of four groups in which mothers were either present or absent during an interview and an immunization. Mothers were asked to fill out a questionnaire about their childrearing practices. Child behavior was observed during both the interview and the immunization. Results indicated that while maternal presence was associated with the children behaving more distressed during the interview, maternal presence had no effect on child behavior during the immunization. Children whose mothers reported high levels of both control and warmth in their relationship (authoritative parents) were found to be significantly less distressed during the immunization than children of either the low-control, high-warmth (permissive), high-control, low-warmth (authoritarian) or low-control, low-warmth (nonresponsive) parent groups.
Subject(s)
Child Behavior , Child Rearing , Mother-Child Relations , Authoritarianism , Child , Child, Preschool , Female , Humans , Injections/psychology , Male , Pain/psychology , Stress, Psychological/etiologySubject(s)
Child Behavior , Pain/psychology , Psychology, Child , Child, Preschool , Female , Group Processes , Humans , MaleABSTRACT
Thirty-six preschool children were invited to look at a set of stimulus materials. One-third of the children were presented with three-dimensional materials that they were free to touch, one third with three-dimensional materials that they could not touch, and one-third with life-size photographs of the objects. Results revealed that the children in each group asked a similar number of questions to identify the names of the objects. However, children who could touch the objects asked the most "transformational" questions (e.g., questions involving broader speculations about the object's origin, function, and relation to other objects in the environment), while those who could not touch the objects asked the next most and those shown photos of the objects asked the least.
