The Influence of the Size of Retinal Image and of Perspective upon the Visual Perception of Distance: A Comparative Study

Upon the assumption that visual perceptions are integrated in character and that some kind of an empirical basis is presupposed in their formation, we have attempted to segregate, for experimental purposes, two of the more commonly acknowledged factors in the estimation of relative distances. Both of these factors may be said to be functions of the stimulus, rather than of the response. A comparison of their relative influence in the distance perceptions of young children and adults, as well as a study of acuity in these perceptions, is the object of this investigation

A Preliminary Study of the Nature of Finality in Melody

According to a recognized definition, a melody is a succession of musical sounds which is felt to constitute a unity. The stipulation, sometimes made, that this unity must be aesthetic, is felt to be not only ambiguous, the aesthetic depending to some degree on individual taste, but restricting, in the sense that melodies termed aesthetic by common consent would be few in number. Unity implies, first, an interrelationship, and secondly, coherence and completeness as a whole; that is, relationship and finality. The melody problem is that of discovering how a series of tonal stimuli can excite a feeling of unity

Jorge Eliecer Gaitan and his term as mayor of Bogota, Colombia, June 1936 to February 1937

One of the most controversial figures in Colombian history is that of Jorge Eliecer Gaitan, whose assassination of April 9, 1948, ended a twenty-year career in national politics.1 The Colombian writer-diplomat, Juan Lozano Y Lozano, has distinguished Gaitan as the man most responsible for creating a new mood: in twentieth century Colombian politics.2 Essentially, this new mood is that of increased interest in national social problems which, during the lifetime of Gaitan, was accompanied by an increasing demand on the part of the masses for significant participation in the political processes of the nation. The paper is divided into three chapters. The first describes the setting for the initial political activity of Gaitan: the Colombian capital, Bogota. The second is a biographical study of Gaitan. The third examines the impact of Gaitan on Bogata during his term as mayor. An epilogue briefly discusses Gaitan after his mayoralty

Seasonal patterns and controls on net ecosystem CO2 exchange in a boreal peatland complex

We measured seasonal patterns of net ecosystem exchange (NEE) of CO2 in a diverse peatland complex underlain by discontinuous permafrost in northern Manitoba, Canada, as part of the Boreal Ecosystems Atmosphere Study (BOREAS). Study sites spanned the full range of peatland trophic and moisture gradients found in boreal environments from bog (pH 3.9) to rich fen (pH 7.2). During midseason (July‐August, 1996), highest rates of NEE and respiration followed the trophic sequence of bog (5.4 to −3.9 μmol CO2 m−2 s−1) \u3c poor fen (6.3 to −6.5 μmol CO2 m−2 s−1) \u3c intermediate fen (10.5 to −7.8 μmol CO2 m−2 s−1) \u3c rich fen (14.9 to −8.7 μmol CO2m−2 s−1). The sequence changed during spring (May‐June) and fall (September‐October) when ericaceous shrub (e.g., Chamaedaphne calyculata) bogs and sedge (Carex spp.) communities in poor to intermediate fens had higher maximum CO2 fixation rates than deciduous shrub‐dominated (Salix spp. and Betula spp.) rich fens. Timing of snowmelt and differential rates of peat surface thaw in microtopographic hummocks and hollows controlled the onset of carbon uptake in spring. Maximum photosynthesis and respiration were closely correlated throughout the growing season with a ratio of approximately 1/3 ecosystem respiration to maximum carbon uptake at all sites across the trophic gradient. Soil temperatures above the water table and timing of surface thaw and freeze‐up in the spring and fall were more important to net CO2 exchange than deep soil warming. This close coupling of maximum CO2 uptake and respiration to easily measurable variables, such as trophic status, peat temperature, and water table, will improve models of wetland carbon exchange. Although trophic status, aboveground net primary productivity, and surface temperatures were more important than water level in predicting respiration on a daily basis, the mean position of the water table was a good predictor (r2 = 0.63) of mean respiration rates across the range of plant community and moisture gradients. Q10 values ranged from 3.0 to 4.1 from bog to rich fen, but when normalized by above ground vascular plant biomass, the Q10 for all sites was 3.3

Jorge Eliecer Gaitan and his term as mayor of Bogota, Colombia, June 1936 to February 1937

One of the most controversial figures in Colombian history is that of Jorge Eliecer Gaitan, whose assassination of April 9, 1948, ended a twenty-year career in national politics.1 The Colombian writer-diplomat, Juan Lozano Y Lozano, has distinguished Gaitan as the man most responsible for creating a new mood: in twentieth century Colombian politics.2 Essentially, this new mood is that of increased interest in national social problems which, during the lifetime of Gaitan, was accompanied by an increasing demand on the part of the masses for significant participation in the political processes of the nation. The paper is divided into three chapters. The first describes the setting for the initial political activity of Gaitan: the Colombian capital, Bogota. The second is a biographical study of Gaitan. The third examines the impact of Gaitan on Bogata during his term as mayor. An epilogue briefly discusses Gaitan after his mayoralty