Effects of Eutrophication and Runoff on Arsenic Cycling in an Urban Lake

Urban lakes are important recreational and natural resources that add to the quality of life for city residents. Unfortunately, urban watersheds often contribute contaminants to these lakes, including organic chemicals, metals, nutrients, and pathogens. Nitrogen and phosphorus are very high in urban and suburban runoff, mostly as a result of animal waste and fertilizers, although leaky sewage systems may also contribute. These nutrients promote plant and algal growth in urban lakes, ultimately resulting in hyper-eutrophic conditions. Eutrophication, in turn, may affect the cycling and mobility of contaminants, such as arsenic and other toxic metals. Spy Pond, located in Arlington, Massachusetts, was recently discovered to be heavily contaminated with arsenic of unknown origin. Surface sediment concentrations above 2,500 ppm have been measured. Subsequent investigations have also revealed that total arsenic levels in the overlying hypolimnetic waters reach over 150 ppb. However, the two interconnected basins that constitute Spy Pond have been found to differ by an order of magnitude in the concentrations of arsenic found in hypolimnetic waters. The goal of this study is to determine the mechanisms responsible for the differences in arsenic mobility in the two basins of Spy Pond, and how this may impact the potential for minimizing human and ecological arsenic exposure. Based on differences in the concentrations of chemical constituents (e.g. iron, sulfur, conductivity, etc.) measured in each basin, we hypothesize that the greater arsenic concentrations found in the bottom waters of the South Basin of Spy Pond are caused by the combined effects of eutrophication, differences in the Fe/S ratio of the two basins, and the physical and chemical impacts of salts in highway runoff

Varied effects of algal symbionts on transcription factor NF-κB in a sea anemone and a coral: possible roles in symbiosis and thermotolerance

Many cnidarians, including the reef-building corals, undergo symbiotic mutualisms with photosynthetic dinoflagellate algae of the family Symbiodiniaceae. These partnerships are sensitive to temperature extremes, which cause symbiont loss and increased coral mortality. Previous studies have implicated host immunity and specifically immunity transcription factor NF-κB as having a role in the maintenance of the cnidarian-algal symbiosis. Here we have further investigated a possible role for NF-κB in establishment and loss of symbiosis in various strains of the anemone Exaiptasia (Aiptasia) and in the coral Pocillopora damicornis. Our results show that NF-κB expression is reduced in Aiptasia larvae and adults that host certain algae strains. Treatment of Aiptasia larvae with a known symbiosis-promoting cytokine, transforming growth factor β, also led to decreased NF-κB expression. We also show that aposymbiotic Aiptasia (with high NF-κB expression) have increased survival following infection with the pathogenic bacterium Serratia marcescens as compared to symbiotic Aiptasia (low NF-κB expression). Furthermore, a P. damicornis coral colony hosting Durusdinium spp. (formerly clade D) symbionts had higher basal NF-κB expression and decreased heat-induced bleaching as compared to two individuals hosting Cladocopium spp. (formerly clade C) symbionts. Lastly, genome-wide gene expression profiling and genomic promoter analysis identified putative NF-κB target genes that may be involved in thermal bleaching, symbiont maintenance, and/or immune protection in P. damicornis. Our results provide further support for the hypothesis that modulation of NF-κB and immunity plays a role in some, but perhaps not all, cnidarian-Symbiodiniaceae partnerships as well as in resistance to pathogens and bleaching.Accepted manuscrip

A differential pressure instrument with wireless telemetry for in-situ measurement of fluid flow across sediment-water boundaries

© 2009 The Authors. This article is distributed under the terms of the Creative Commons Attribution (3.0) License. The definitive version was published in Sensors 9 (2009): 404-429, doi:10.3390/s90100404.An instrument has been built to carry out continuous in-situ measurement of small differences in water pressure, conductivity and temperature, in natural surface water and groundwater systems. A low-cost data telemetry system provides data on shore in real time if desired. The immediate purpose of measurements by this device is to continuously infer fluxes of water across the sediment-water interface in a complex estuarine system; however, direct application to assessment of sediment-water fluxes in rivers, lakes, and other systems is also possible. Key objectives of the design include both low cost, and accuracy of the order of ±0.5 mm H2O in measured head difference between the instrument’s two pressure ports. These objectives have been met, although a revision to the design of one component was found to be necessary. Deployments of up to nine months, and wireless range in excess of 300 m have been demonstrated

A Preference for Contralateral Stimuli in Human Object- and Face-Selective Cortex

Visual input from the left and right visual fields is processed predominantly in the contralateral hemisphere. Here we investigated whether this preference for contralateral over ipsilateral stimuli is also found in high-level visual areas that are important for the recognition of objects and faces. Human subjects were scanned with functional magnetic resonance imaging (fMRI) while they viewed and attended faces, objects, scenes, and scrambled images in the left or right visual field. With our stimulation protocol, primary visual cortex responded only to contralateral stimuli. The contralateral preference was smaller in object- and face-selective regions, and it was smallest in the fusiform gyrus. Nevertheless, each region showed a significant preference for contralateral stimuli. These results indicate that sensitivity to stimulus position is present even in high-level ventral visual cortex

Longitudinal Assessment of Resident Performance Using Entrustable Professional Activities

IMPORTANCE Entrustable professional activities (EPAs) are an emerging workplace-based, patient-oriented assessment approach with limited empirical evidence. OBJECTIVE To measure the development of pediatric trainees’ clinical skills over time using EPA-based assessment data. DESIGN, SETTING, AND PARTICIPANTS Prospective cohort study of categorical pediatric residents over 3 academic years (2015-2016, 2016-2017, and 2017-2018) assessed on 17 American Board of Pediatrics EPAs. Residents in training at 23 pediatric residency programs in the Association of Pediatric Program Directors Longitudinal Educational Assessment Research Network were included. Assessment was conducted by clinical competency committee members, who made summative assessment decisions regarding levels of supervision required for each resident and each EPA. Data were collected from May 2016 to November 2018 and analyzed from November to December 2018. INTERVENTIONS Longitudinal, prospective assessment using EPAs. MAIN OUTCOMES AND MEASURES Trajectories of supervision levels by EPA during residency training and how often graduating residents were deemed ready for unsupervised practice in each EPA. RESULTS Across the 5 data collection cycles, 1987 residents from all 3 postgraduate years in 23 residency programs were assigned 25 503 supervision level reports for the 17 general pediatrics EPAs. The 4 EPAs that required the most supervision across training were EPA 14 (quality improvement) on the 5-level scale (estimated mean level at graduation, 3.7; 95% CI, 3.6-3.7) and EPAs 8 (transition to adult care; mean, 7.0; 95% CI, 7.0-7.1), 9 (behavioral and mental health; mean, 6.6; 95% CI, 6.5-6.6), and 10 (resuscitate and stabilize; mean, 6.9; 95% CI, 6.8-7.0) on the expanded 5-level scale. At the time of graduation (36 months), the percentage of trainees who were rated at a supervision level corresponding to “unsupervised practice” varied by EPA from 53% to 98%. If performance standards were set to align with 90% of trainees achieving the level of unsupervised practice, this standard would be met for only 8 of the 17 EPAs (although 89% met this standard for EPA 17, performing the common procedures of the general pediatrician). CONCLUSIONS AND RELEVANCE This study presents initial evidence for empirically derived practice readiness and sets the stage for identifying curricular gaps that contribute to discrepancy between observed practice readiness and standards needed to produce physicians able to meet the health needs of the patient populations they serve. Future work should compare these findings with post-graduation outcomes data as a means of seeking validity evidence

Dynamic Spatial Coding within the Dorsal Frontoparietal Network during a Visual Search Task

To what extent are the left and right visual hemifields spatially coded in the dorsal frontoparietal attention network? In many experiments with neglect patients, the left hemisphere shows a contralateral hemifield preference, whereas the right hemisphere represents both hemifields. This pattern of spatial coding is often used to explain the right-hemispheric dominance of lesions causing hemispatial neglect. However, pathophysiological mechanisms of hemispatial neglect are controversial because recent experiments on healthy subjects produced conflicting results regarding the spatial coding of visual hemifields. We used an fMRI paradigm that allowed us to distinguish two attentional subprocesses during a visual search task. Either within the left or right hemifield subjects first attended to stationary locations (spatial orienting) and then shifted their attentional focus to search for a target line. Dynamic changes in spatial coding of the left and right hemifields were observed within subregions of the dorsal front-parietal network: During stationary spatial orienting, we found the well-known spatial pattern described above, with a bilateral hemifield representation in the right hemisphere and a contralateral preference in the left hemisphere. However, during search, the right hemisphere had a contralateral preference and the left hemisphere equally represented both hemifields. This finding leads to novel perspectives regarding models of visuospatial attention and hemispatial neglect

AKT Signaling Mediates IGF-I Survival Actions on Otic Neural Progenitors

Background: Otic neurons and sensory cells derive from common progenitors whose transition into mature cells requires the coordination of cell survival, proliferation and differentiation programmes. Neurotrophic support and survival of post-mitotic otic neurons have been intensively studied, but the bases underlying the regulation of programmed cell death in immature proliferative otic neuroblasts remains poorly understood. The protein kinase AKT acts as a node, playing a critical role in controlling cell survival and cell cycle progression. AKT is activated by trophic factors, including insulin-like growth factor I (IGF-I), through the generation of the lipidic second messenger phosphatidylinositol 3-phosphate by phosphatidylinositol 3-kinase (PI3K). Here we have investigated the role of IGF-dependent activation of the PI3K-AKT pathway in maintenance of otic neuroblasts. Methodology/Principal Findings: By using a combination of organotypic cultures of chicken (Gallus gallus) otic vesicles and acoustic-vestibular ganglia, Western blotting, immunohistochemistry and in situ hybridization, we show that IGF-I-activation of AKT protects neural progenitors from programmed cell death. IGF-I maintains otic neuroblasts in an undifferentiated and proliferative state, which is characterised by the upregulation of the forkhead box M1 (FoxM1) transcription factor. By contrast, our results indicate that post-mitotic p27Kip-positive neurons become IGF-I independent as they extend their neuronal processes. Neurons gradually reduce their expression of the Igf1r, while they increase that of the neurotrophin receptor, TrkC. Conclusions/Significance: Proliferative otic neuroblasts are dependent on the activation of the PI3K-AKT pathway by IGF-I for survival during the otic neuronal progenitor phase of early inner ear development

A review of the distribution of particulate trace elements in urban terrestrial environments and its application to considerations of risk

We review the evolution, state of the art and future lines of research on the sources, transport pathways, and sinks of particulate trace elements in urban terrestrial environments to include the atmosphere, soils, and street and indoor dusts. Such studies reveal reductions in the emissions of some elements of historical concern such as Pb, with interest consequently focusing on other toxic trace elements such as As, Cd, Hg, Zn, and Cu. While establishment of levels of these elements is important in assessing the potential impacts of human society on the urban environment, it is also necessary to apply this knowledge in conjunction with information on the toxicity of those trace elements and the degree of exposure of human receptors to an assessment of whether such contamination represents a real risk to the city’s inhabitants and therefore how this risk can be addressed

Population diversity and function of hyperpolarization-activated current in olfactory bulb mitral cells

Although neurons are known to exhibit a broad array of intrinsic properties that impact critically on the computations they perform, very few studies have quantified such biophysical diversity and its functional consequences. Using in vivo and in vitro whole-cell recordings here we show that mitral cells are extremely heterogeneous in their expression of a rebound depolarization (sag) at hyperpolarized potentials that is mediated by a ZD7288-sensitive current with properties typical of hyperpolarization-activated cyclic nucleotide gated (HCN) channels. The variability in sag expression reflects a functionally diverse population of mitral cells. For example, those cells with large amplitude sag exhibit more membrane noise, a lower rheobase and fire action potentials more regularly than cells where sag is absent. Thus, cell-to-cell variability in sag potential amplitude reflects diversity in the integrative properties of mitral cells that ensures a broad dynamic range for odor representation across these principal neurons