The modular organization of the brain network can vary in two fundamental ways. The amount of interversus intra-modular connections between network nodes can be altered, or the community structure itself can be perturbed, in terms of which nodes belong to which modules (or communities). Alterations have previously been reported in modularity, which is a function of the proportion of intra-modular edges over all modules in the network. For example, we have reported that modularity is decreased in functional brain networks in schizophrenia: There are proportionally more inter-modular edges and fewer intra-modular edges. However, despite numerous and increasing studies of brain modular organization, it is not known how to test for differences in the community structure, i.e., the assignment of regional nodes to specific modules. Here, we introduce a method based on the normalized mutual information between pairs of modular networks to show that the community structure of the brain network is significantly altered in schizophrenia, using resting-state fMRI in 19 participants with childhood-onset schizophrenia and 20 healthy participants. We also develop tools to show which specific nodes (or brain regions) have significantly different modular communities between groups, a subset that includes right insular and perisylvian cortical regions. The methods that we propose are broadly applicable to other experimental contexts, both in neuroimaging and other areas of network science.

Although results from in vitro ovule culture studies have demonstrated a specific K requirement for fiber growth, a direct association between the K status of the cotton (Gossypium hirsutum L.) plant and fiber quality has not been established under field conditions. To evaluate this relationship, a single cultivar (1985) and two cultivars (1986 and 1987) were grown with 0, 120, 240, or 480 kg K ha‐1 in 10 blocked replicates of each K level on an irrigated, vermiculitic soil. There was a significant seed‐cotton yield response to applied K in each year. Lint yield, however, increased relatively more than seed yield, resulting in a greater lint percentage as plant K supply increased. The greater lint percentage reflected increased fiber length and secondary wall thickness (measured as a micronaire index) obtained from plants that received fertilizer K. For both cultivars, the fiber length, micronaire index, fiber strength and percent elongation, and fiber length uniformity ratio (dependent variables) were each positively related to (i) fiber K concentration at maturity, (ii) leaf K concentration at early bloom, and (iii) an index of soil K availability as independent variables in regression analyses. Comparison of cultivar regressions, however, indicated that fiber quality of ‘Acala GC510’ was higher than that of ‘Acala SJ2’ at low fiber, leaf, or soil K levels. We conclude that K supply to cotton fruit is an important determinant of fiber quality under field conditions, and that the K requirement for producing high lint yield with acceptable quality may differ among genotypes.

Cotton (Gossypium hirsutum L.) cultivars have considerable yield differences on vermiculitic soils where late‐season K deficiency occurs in California. A 2‐yr field study was conducted to evaluate cultivar differences in K use efficiency (defined as higher yield with a limited K supply) in relation to K uptake, K partitioning, and critical internal and external K requirements. The experiment had a split plot design with fertilizer‐K addition levels as mainplots, two cultivar subplots, and 10 blocked replications. Without K addition, yield was 29% (1986) and 35% (1987) greater in the K‐use‐efficient cultivar. Cultivar yield differences reflected greater boll retention at later fruiting positions, but was not related to differences in partitioning of K between vegetative and fruiting structures. When K supply was not limited, cultivar yields were similar. Yield of both cultivars was closely associated with leaf K concentration and soil K availability, but response curves indicated a lower leaf and soil K requirement for the K‐use‐efficient cultivar. The K‐use‐efficient cultivar had a higher K uptake rate during fruit development and greater total K accumulation, particularly at low soil K levels. Defining the physiological bases for such large genetic variation in K use efficiency will help to identify why the cotton plant is more sensitive to K limitation than other crops and will aid breeding efforts to develop germplasm more tolerant of a limited soil K supply.

Labrador, Canada is the last relatively undeveloped landmass of Boreal and subarctic Canada. Its land area is over 288,000 km 2 , with less than 1% developed, and a human population of below 30,000. Labrador is greater than 60% forest-and woodlandcovered and over 30% tundra, soil and rock barrens. We review the ecology and distribution of forests, woodlands, and related vegetation of Labrador within the context of climate, forest site index, landform, soils, and disturbance. Recent ecosystem management through a public planning process with emphasis on past and future comanagement and development with traditional and western scientific principles is currently underway. Plant-animal interactions, traditional uses by aboriginal groups, and early history are also reviewed.