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The municipal wellfield in Collierville, Tennessee, is contaminated with trichloroethylene (TCE) and hexavalent chromium (Cr (VI)) due to industrial operations dating back to the 1970s and 1980s. This study aims to elucidate the aquifer's contaminant transport mechanisms by determining longitudinal and transverse dispersivities through inverse modeling. Utilizing MT3DMS for contaminant transport simulation, based on a well-calibrated groundwater flow model, and leveraging Python's multiprocessing library for efficiency, the study employs a trial-and-error methodology. Key findings reveal that longitudinal dispersivity values range from 5.5 m near the source to 20.5 m further away, with horizontal and vertical transverse dispersivities between 0.28 m and 3.88 m and between 0.03 m and 0.08 m, respectively. These insights into the aquifer's dispersivity coefficients, which reflect the scale-dependent nature of longitudinal dispersivity, are crucial for optimizing remediation strategies and achieving cleanup goals. This study underscores the importance of accurate parameter estimation in contaminant transport modeling and contributes to a better understanding of contaminant dynamics in the Collierville wellfield. [ABSTRACT FROM AUTHOR]

The Cumberland Plateau Salamander, Plethodon kentucki, is a cryptic species with respect to the sympatric Northern Slimy Salamander, Plethodon glutinosus. It was first described by Highton and MacGregor (1983) by using allozyme data. In that description, the authors reported extreme levels of genetic differentiation for a single species with a narrow distribution; however, follow-up studies found patterns of genetic variation that were discordant with the allozyme data. In this paper, we describe patterns of genetic variation within P. kentucki by using an anchored hybrid enrichment dataset of 21 individuals sampled from across its known range. We identified four genetic groups with extensive admixture and isolation by distance. We constructed a population tree by using TreeMix and inferred gene flow between two of the four genetic groups. Finally, we used Bayesian phylogenetics and phylogeography (BPP) in conjunction with the genealogical divergence index (gdi) to test species boundaries within P. kentucki. Although BPP suggested that P. kentucki could be four species, gdi indicated that none of the groups were sufficiently independent to constitute separate species. We conclude that P. kentucki is best recognized as a single species with substantial genetic structure within its limited distribution. [ABSTRACT FROM AUTHOR]

Species are the fundamental unit of biodiversity studies. However, many species complexes are difficult to delimit, especially those characterized by complicated patterns of population structure. Salamanders in the family Plethodontidae often form species by slowly fragmenting across a landscape over space and time. They thus provide many examples of species complexes in which gradual Darwinian evolution has resulted in multiple units of varying degrees of differentiation, including incompletely separated lineages. Herein, we report on a molecular systematic investigation of woodland salamanders in the Plethodon wehrlei group, a group that has recently been split from two species into five species. To quantify patterns of genetic variation, we collected genetic samples from 24 individuals from 20 populations, including all species and representing a carefully selected subset of previous work. From these samples, we obtained genomic data by using anchored hybrid enrichment, resulting in 319 loci averaging 1300 bp in length. Biallelic single-nucleotide polymorphisms were randomly selected from 316 of these loci for some analyses. We examined patterns of genetic structure by using a combination of multivariate statistics and methods based on evolutionary models (such as the Bayesian program STRUCTURE) and found that all of the recognized species formed genetic clusters; however, P. wehrlei and P. punctatus were relatively weakly differentiated and STRUCTURE identified three separate clusters within P. jacksoni. Species trees inferred using the weighted accurate species tree algorithm (wASTRAL), Bayesian phylogenetics and phylogeography (BPP), and TreeMix all recovered the same topology, with P. dixi sister to the other taxa, which included a northern clade (P. wehrlei, P. punctatus, P. pauleyi) and a southern clade (P. jacksoni, with three separate groups). TreeMix only inferred one gene flow event. We evaluated the candidate species by using BPP and the genealogical divergence index (gdi). Although BPP delimited all candidate species with strong support (all posterior probabilities = 1.0), the gdi only strongly supported P. dixi and P. pauleyi, both of which have only been recently described. We discuss the difficult problem of species delimitation in groups that form species via range fragmentation. We also provide a vision for future research, with the aim of better testing and diagnosing the species diversity within the P. wehrlei group. [ABSTRACT FROM AUTHOR]

Aims Location Taxon Methods Results Main Conclusions Glacial retreat at the end of the Pleistocene epoch opened vast expanses of emergent habitat in the northern hemisphere that were colonized by opportunistic taxa. However, species that undergo post‐glacial expansion may have originated from one or several glacial refugia. We inferred the post‐glacial expansion history of the Eastern Red‐backed Salamander (Plethodon cinereus), a fully terrestrial species with a vast distribution despite severe dispersal limitations. Previous studies indicated populations south of the glacial boundary at the eastern and western limits of the distribution were closely related, suggesting either multiple refugia or an extraordinary post‐glacial expansion event.Eastern North America.Plethodon cinereus (Green, 1818), Caudata: Plethodontidae.We collected ddRAD‐seq data from 106 individuals throughout the distribution of P. cinereus. We estimated phylogeographic structure, including finer‐scale structure among the post‐glacial populations. To test the origins and routes of colonization, we used ecological niche modelling, population trees and analyses of directional range expansion.Analyses supported our hypothesis of a southeastern glacial refugium, with northward expansion along the Eastern Seaboard prior to westward invasion into the Great Lakes region, including southwestern expansion into unglaciated areas at the western end of the distribution. However, a distinct subgroup in the northwestern portion of the range raises the possibility of a second refugium near the ice‐free Driftless Area.Based on our results, we hypothesize a southeastern refugium from which most of today's northern populations undertook extensive post‐glacial colonization. Our results indicate a geographically non‐linear colonization history for P. cinereus. [ABSTRACT FROM AUTHOR]

The shallow, Memphis, and Fort Pillow aquifers are the three major water‐bearing strata beneath Memphis, Tennessee, where the Memphis aquifer serves as the primary groundwater source. The upper Claiborne confining unit (UCCU) separates shallow and Memphis aquifers across the majority of Shelby County, acting as an upper protective layer for the Memphis aquifer. However, hydrogeologic breaches within the UCCU create a hydraulic connection and provide an avenue for potential contaminant migration from the shallow to the Memphis aquifer. This research aims to minimize contaminant migration, mitigate risks, extend existing wells' life that may face water contamination, and find suitable locations for future well construction. Several strategies are developed addressing well depth, seasonal well operation, and mapping no‐drilling or red zones to provide practical solutions. A numerical groundwater modeling technique is developed for each strategy that includes stochastic simulation–optimization and customized simulation models depending on the strategy. The models result in thousands of numerical simulations for each scenario to identify recurring patterns of contaminant movement to and through the Memphis aquifer. The results indicate that optimum well positions (spatially and vertically) and modification to pumping can increase the life expectancy of wellfields, offer sustainable management of the Memphis aquifer, and reduce contaminant migration through 2050. [ABSTRACT FROM AUTHOR]

Behavioral repeatability greatly affects the capacity of an individual to respond to varying environments. When multiple behaviors within individuals are repeatable and correlated across time or across contexts, it is termed a behavioral syndrome. However, not all behaviors exhibit the same level of repeatability, and relatively few studies have examined repeatability in amphibians. We examined the repeatability of foraging behavior in the Eastern Red-backed salamander (Plethodon cinereus), a color-polymorphic terrestrial salamander, following a simulated predation attempt. We tested several hypotheses: (1) Simulated predation would negatively affect foraging, increasing latency to feed and decreasing the number of prey items eaten in a fixed time period compared to a control group; (2) Because striped color morphs of P. cinereus are more aggressive, striped individuals would exhibit "bold" behavior by resuming foraging sooner and consuming more prey; and (3) Foraging behavior would be more repeatable for males. We found that the predation treatment inhibited foraging behavior, although neither morphs nor sexes differed in either forging metric. The number of prey eaten was repeatable for all groups of salamanders. Latency to feed, however, was not repeatable for control salamanders. Simulated predation induced repeatable latencies, but when morphs and sexes were analyzed separately, only unstriped and male salamanders were repeatable, suggesting characteristics of these groups related to behavioral syndromes drive this response. We speculate that the greater repeatability of the unstriped morph's latency to feed may result from more frequent encounters with predators in the leaf litter matrix while foraging. Striped salamanders from the source population, in turn, exhibit greater territorial success, and thus may experience more variation in encounters with predators and conspecifics over the course of their lifespans. Our results illustrate the need to carefully define the behavior and subset of the population to be tested when studying behavioral repeatability or behavioral syndromes. [ABSTRACT FROM AUTHOR]

Primary objective: This paper reports on the personal experiences of loneliness for individuals living with brain injury. Research design: This is a qualitative research design, employing semi‐structured interviews and subsequent contextualist thematic analysis. Methods and procedures: Eleven clients (two female and nine male, aged between 27 and 63 years) with brain injury participated in semi‐structured interviews. Thematic analysis was employed in the interpretation of the data. Main outcomes and results: The interview data and subsequent analysis depicted three overarching themes in a healing process – 'Internal Loneliness', 'Healing the Cracks', and 'Visible with Cracks'. Participants described five factors which contribute to their feeling of loneliness: trauma, social isolation, concealment, rejection of part of self, and invisibility of their disability. The participants' accounts also detailed the necessity of a therapeutic intervention and relationship to deal with and address some of these issues. Conclusions: This study highlights that processing the trauma, developing dialectical thinking, self‐compassion, and a degree of self‐acceptance assist in the movement of participants towards allowing themselves to be 'Visible with Cracks'. This allowance of self to be fully seen appears to serve an important function for reconnection with self and others. These results may help to inform brain injury rehabilitative care, through developing their understanding of the internal loneliness factors that may be influencing an individual's social isolation or social withdrawal. [ABSTRACT FROM AUTHOR]

Objective: Conduct a scoping review of literature surrounding acquired brain injury (ABI) sustained secondary to a suicide attempt to establish the current body of research on injury outcomes and rehabilitative needs for this population. Methods: A systematic search of the literature was conducted. Searches were conducted using terms relating to this injury etiology and search results with original or secondary data on individuals with an ABI were included for review. Results: Thirty-two articles were reviewed. Limited data characterizing this population exists in the literature. Findings indicate that this population have generally poorer injury outcomes compared with ABI sustained through other means. Rehabilitative needs are rarely addressed, but limited commentary suggests that extensive pre-morbid conditions, severity of injuries and psychosocial support needs of this population present implications for rehabilitative supports. Conclusion: There is a relative dearth of research examining ABI sustained secondary to a suicide attempt. Collated findings suggest these individuals are rarely recognized in the literature as a distinct ABI population with rehabilitative needs specific to this etiology. Future research should aim to address the gaps identified in the literature, including characterizing the population, establishing pre-morbid conditions and developing tailored rehabilitative support to address complex needs. [ABSTRACT FROM AUTHOR]