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Introduction: Elevated N‐terminal pro B‐type natriuretic peptide (NT‐proBNP) is a potent predictor of adverse outcomes in hemodialysis initiation. These patients often experience intradialytic hypotension, which may partially reflect cardiac dysfunction, but the association of NT‐proBNP with intradialytic hypotension is not clear. Methods: We performed a post hoc analysis of a randomized trial that tested mannitol versus placebo in 52 patients initiating hemodialysis (NCT01520207). NT‐proBNP was measured prior to the first and third sessions (n = 87). Mixed‐effects models (adjusting for randomized treatment, sex, race, age, diabetes, heart failure, catheter use, pre‐dialysis systolic blood pressure, pre‐dialysis weight, ultrafiltration volume, serum sodium, bicarbonate, urea nitrogen, phosphate, albumin, hemoglobin, and session length) were fit to examine the association of NT‐proBNP with systolic blood pressure decline (pre‐dialysis minus nadir systolic blood pressure). Additionally, mixed‐effects Poisson models were fit to examine the association with intradialytic hypotension (≥20 mmHg decline in systolic blood pressure). Findings: Mean age was 55 ± 16 years; 33% had baseline heart failure. The median NT‐proBNP was 5498 [25th‐75th percentile 2011, 14,790] pg/mL; 26 sessions (30%) were complicated by intradialytic hypotension. In adjusted models, each unit higher log‐NT‐proBNP was associated with 6.0 mmHg less decline in systolic blood pressure (95%CI −9.2 to −2.8). Higher pre‐dialysis NT‐proBNP, per log‐unit, was associated with a 52% lower risk of intradialytic hypotension (IRR 0.48, 95%CI 0.23–0.97), without evidence for effect modification by randomized treatment (P‐interaction = 0.17). Discussion: In patients initiating hemodialysis, higher NT‐proBNP is associated with less decline in intradialytic systolic blood pressure and lower risk of intradialytic hypotension. Future studies should investigate if higher pre‐dialysis NT‐proBNP levels may identify patients who might tolerate more aggressive ultrafiltration. [ABSTRACT FROM AUTHOR]

Fish movement in freshwater streams is often tied to patterns of flow, especially when the stream is intermittent, flashy, or some combination thereof. Relationships between flow and fish movement are exacerbated in small urban streams in impervious surface‐dominated watersheds that lead to extreme flow conditions. Here we examined the response of Creek Chub (Semotilus atromaculatus), a common pioneer fish species in eastern North America, to flow events of various sizes in a small intermittent urban headwater stream. Our primary goals were to determine (1) the level of Creek Chub movement occurring in an intermittent headwater stream, (2) the influence of flow on movement direction and magnitude, (3) the degree of variation in individual movement behaviour, and (4) mortality rates in the system. The study used PIT tagging and telemetry surveys to monitor Creek Chub movement over a six‐month period. We found that individual Creek Chub in our study system were generally mobile (71%), but usually moved short distances only; however, a few individuals moved much farther, with a maximum single movement of 521 m. Moderate or major flow events increased the probability and magnitude of Creek Chub movement, but there was no detectable asymmetry towards upstream or downstream directionality. Movement was variable among individual fish and fish were able to respond to large and small flow events to move among habitats. Finally, we observed relatively high, but episodic, mortality in our study site, potentially related to pollution events. Evidence of elevated mortality points to the potential importance of movement in highly disturbed streams, as it may enable recolonization after local extirpation. [ABSTRACT FROM AUTHOR]

Areal data have been used to good effect in a wide range of sociological research. One of the most persistent problems associated with this type of data, however, is the need to combine data sets with incongruous boundaries. To help address this problem, we introduce a new method for identifying common geographies. We show that identifying common geographies is equivalent to identifying components within a "k"-uniform "k"-partite hypergraph. This approach can be easily implemented using a geographic information system in conjunction with a simple search algorithm.

An environmental event that damages housing and the built environment may result in either a short‐ or long‐term out‐migration response, depending on residents' recovery decisions and hazard tolerance. If residents move only in the immediate disaster aftermath, then out‐migration will be elevated only in the short‐term. However, if disasters increase residents' concerns about future risk, heighten vulnerability, or harm the local economy, then out‐migration may be elevated for years after an event. The substantive aim of this research brief is to evaluate hypotheses about short‐ and long‐term out‐migration responses to the highly destructive 2005 hurricane season in the Gulf of Mexico. The methodological aim is to demonstrate a difference‐in‐differences (DID) approach analysing time series data from Gulf Coast counties to compare short‐ and long‐differences in out‐migration probabilities in the treatment and control counties. We find a large short‐term out‐migration response and a smaller sustained increase for the disaster‐affected coastal counties. [ABSTRACT FROM AUTHOR]

This dissertation examines spawning behavior and habitat in Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) in the Southern California Bight (SCB). The fine-scale horizontal and vertical distributions of anchovy and sardine eggs are characterized and their potentials for interaction with the predator Euphausia pacifica are assessed under varying environmental conditions.In Chapter 2, fine-scale horizontal pattern of sardine and anchovy eggs is characterized. Variograms for anchovy eggs have a higher nugget effect than those for sardine eggs, indicating that spatial structure of the distribution of sardine eggs is better resolved at the scales sampled. In light of other spatial studies of eggs of Sardinops sagax and Engraulis spp., I propose that the pattern is a function of species­ specific life history, population size and age structure, spawning intensity, and physical scales of the spawning habitat.Chapter 3 presents a model for vertical distribution of anchovy and sardine eggs, based on vertical mixing and ascent velocities of the eggs. The vertical mixing model that best predicts observed vertical distributions of anchovy eggs is different than that for sardine, and addition of a random error term to the terminal ascent velocity affects predictions of anchovy eggs, but not sardine eggs. Observed vertical distributions of sardine eggs are highly variable, perhaps due to horizontal patchiness or true vertical variability. The model does not improve prediction of integrated abundances from samples at 3-m depth over a simple regression of 3-m on integrated abundances.In Chapter 4, distributions of sardine and anchovy eggs and adult and juvenile Euphausia pacifica, an abundant euphausiid predator on ichthyoplankton, are examined in geographic and T-S space in the SCB for 1953-1959 and 1995-2002. Variability in the relative distributions of the three species shows concordance with environmental change. Occurrence of significantly complementary distributions of anchovy eggs and E. pacifica provides supporting evidence for interaction between anchovy and euphausiids.Spatial pattern in sardine and anchovy eggs is shown to be relevant to relationships between spawning behavior, spawning habitat, and population size. The potential importance of the dominant euphausiid species in influencing recruitment and spawning habitat selection is also supported.