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.

Acala (Gossypium hirsutum L.) and Pima (G. barbadense L.) cotton growth, lint yield, and fiber quality responses to N in the San Joaquin Valley, CA were evaluated. Numerous reasons, including adaptation of N fertilization guidelines to modern production practices, recent increases in energy costs, and growing concerns about NO−3 contamination of ground water, led to the initiation of this study. Acala was grown for 3 yr on a Panoche clay loam [fine‐loamy, mixed (calcareous), thermic Typic Torriorthents] and a Wasco sandy loam (coarse‐loamy, mixed, nonacid, thermic Typic Torriorthents). Pima was grown for 2 yr on the Panoche clay loam. Four N treatments were established in a randomized complete block design: 56, 112, 168, and 224 kg N ha−1. Three‐year average aboveground dry matter production of Acala was 7800 and 12 600 kg ha−1 on the Panoche clay loam and 8500 and 11 900 kg ha−1 on the Wasco sandy loam for the 56 and 168 kg N ha−1 treatments, respectively. The equivalent 2‐yr averages for Pima were 7600 (56 kg N ha−1) and 10 800 kg ha−1 (168 kg N ha−1). Linear increases in lint yield with increased N fertility level occurred for Acala on Panoche clay loam in every year. Maximum lint yield averaged over 3 yr was 1842 kg ha−1 in the 224 kg N ha−1 treatment. The response of Acala lint yield to N management on the Wasco sandy loam was smaller than on Panoche clay loam, with a maximum lint yield of 1666 kg ha−1 (224 kg N ha−1, 3‐yr average). Pima lint yield responded to N management in a quadratic fashion with maximum yields in the 168 kg N ha−1 treatment in both years (1638 kg ha−1, 2‐yr average). Acala gin turnouts were greater at the Panoche than at the Wasco site. Decreases in gin turnout with increasing N were significant on the Panoche clay loam (Acala and Pima) but not on the Wasco sandy loam (Acala). There was a generally positive relationship between increasing N fertilization and yield; however, efficient N management should include an assessment of available soil residual N, soil type, and yearly climatic conditions.

Cumulative effects of annual K additions on cotton (Gossypium hirsutum L.) growth and soil K balance were examined in a field study on an irrigated, vermiculitic soil. In each of 3 consecutive yr, cotton ‘Acala SJ2’ was grown with 0, 120, 240, or 480 kg K ha−1 applied to the same treatment plots in a randomized complete block design with 10 replications. The relationship between seed cotton yield and petiole K concentration was similar across years (r2 = 0.61, P < 0.001), but slopes of the yield response to applied K increased each year; 2.6‐fold more seed cotton was obtained per unit K input in 1987 than in 1985. This cumulative response reflected a yield decline without K addition and increasingly higher yield with each additional input of 480 kg K ha−1. Two processes appeared to control this response. First, without K input, NH4‐extractable K+ in surface soil decreased 20% from August 1985 to August 1987. This decrease greatly exceeded the K removal by cotton, and we surmise that an 11% decrease in soil organic C content contributed to this phenomenon. Loss of cation exchange capacity associated with the loss of soil humus may shift K equilibria towards fixation at interlayer sites in vermiculite at the expense of external K pools extracted by NH+4. Second, with high levels of K input, apparent K uptake efficiency from applied K was 50% greater in 1987 than in 1985. Increased efficiency was attributed to the partial saturation of K fixation sites from previous K additions and thus a larger proportion of newly added K remained in plant‐available K pools. At the highest K addition level, 86% of the 1440 kg K ha−1 applied in the 3‐yr period was fixed beyond extraction by NH+4, and plants remained marginally K deficient. The existence of a cumulative response to applied K on vermiculitic soils would have a marked impact on the economics of K fertilization on cotton.

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1970s to about 200 kg ha Ϫ1 by the mid 1990s (Fritschi et al., 2003). Current management strategies for SJV Nitrogen fertilizer is routinely applied to crops grown in rotation cotton production call for N applications ranging from with upland cotton (Gossypium hirsutum L.) in the San Joaquin 171 to 228 kg ha Ϫ1 (Weir et al., 1996); however, actual Valley (SJV) of California. However, increasing N fertilizer costs, the rates will depend upon soil type and previous cropping potential overuse of N resulting in excessive vegetative growth and harvest delays, increasing pest pressure, and concern for nitrate con-history. In some cases, annual N application for cotton tamination of groundwater support a reassessment of current N fertilmay exceed 228 kg ha Ϫ1 (Weir et al., 1996). Assuming ization practices. The primary goal of this research was to provide annual California cotton production has averaged information that would assist SJV cotton growers in updating and 400 000 ha over the past decade, cotton would account improving N management practices. Plot site selection included two for nearly 18% of all agricultural N used in California university field stations and six on-farm locations representing all SJV during that time. Increases in applied N in the SJV cotton-producing counties. Nitrogen treatments of 56 to 224 kg N above levels prevailing 20 to 30 yr ago are a result of ha Ϫ1 were over a 5-yr period. Cotton lint yield responded positively a combination of factors. For one, the higher yields to increasing N applications in only 41% (16 out of 39) of the test associated with the newer varieties suggest greater need sites. Yield response to fertilizer N was related to residual soil N in for N, yet there is little evidence to support this conthe upper 0.6 m of soil as follows: below 70 kg ha Ϫ1 residual NO 3 -N, 9 of 17 sites responded positively to increasing applied N; at 70 totention. In addition, use of the growth regulator mepi-125 kg ha Ϫ1 , 5 of 11 sites responded; and at greater than 125 kg ha Ϫ1 , quat chloride has altered irrigation and N fertilizer manonly 2 of 11 sites responded. Changes in soil NO 3 -N levels from agement practices in many cotton production areas of postplanting to postharvest were generally larger within the upper the state. Since mepiquat chloride can be used to control 1.2 m of soil than at lower depths. However, net increases in soil excessive growth (Kerby et al., 1996), there is less need NO 3 -N also occurred in the 1.2-to 2.4-m range at sites prone to for restricted water and N applications. leaching.Most of the newer Acala varieties are more determinate in growth habit than the older varieties. Plant populations typically used are higher, and length of the grow-