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Regionally scaled assessments of hydrologic alteration for small streams and its effects on freshwater taxa are often inhibited by a low number of stream gages. To overcome this limitation, we paired modeled estimates of hydrologic alteration to a benthic macroinvertebrate index of biotic integrity data for 4522 stream reaches across the Chesapeake Bay watershed. Using separate random-forest models, we predicted flow status (inflated, diminished, or indeterminant) for 12 published hydrologic metrics (HMs) that characterize the main components of flow regimes. We used these models to predict each HM status for each stream reach in the watershed, and linked predictions to macroinvertebrate condition samples collected from streams with drainage areas less than 200 km2. Flow alteration was calculated as the number of HMs with inflated or diminished status and ranged from 0 (no HM inflated or diminished) to 12 (all 12 HMs inflated or diminished). When focused solely on the stream condition and flow-alteration relationship, degraded macroinvertebrate condition was, depending on the number of HMs used, 3.8–4.7 times more likely in a flow-altered site; this likelihood was over twofold higher in the urban-focused dataset (8.7–10.8), and was never significant in the agriculture-focused dataset. Logistic regression analysis using the entire dataset showed for every unit increase in flow-alteration intensity, the odds of a degraded condition increased 3.7%. Our results provide an indication of whether altered streamflow is a possible driver of degraded biological conditions, information that could help managers prioritize management actions and lead to more effective restoration efforts.

Anthropogenic alterations have resulted in widespread degradation of stream conditions. To aid in stream restoration and management, baseline estimates of conditions and improved explanation of factors driving their degradation are needed. We used random forests to model biological conditions using a benthic macroinvertebrate index of biotic integrity for small, non-tidal streams (upstream area ≤200 km

N acylated substituted beta 3 oligoamides are known to form unique supramolecular nanorods based on a 3 point hydrogen bond self assembly motif. This motif is an intermolecular extension of the hydrogen bonding network that stabilizes the 14 helix secondary structure unique to beta 3 oligoamides. Acetylation of the N terminus of the molecule provides the necessary third hydrogen bond pair of the motif. Here, the possibility of introducing the third hydrogen bond pair via amidation of the C terminus is investigated. While similar in purpose, this modification introduces a chemically distinct new self assembly motif, also removing the bulky carboxyl group that does not fold into the 14 helix positioning instead as a side chain. Three substituted beta 3 oligoamide variants with the base sequence LIA where the letters denote beta 3 residues with side chains analogous to alpha amino acids were compared N acylated Ac beta 3 [LIA] as a reference, C amidated beta 3 [LIA] CONH2, and beta 3 [LIA] with free unmodified N and C termini as a negative control. The three variants were dissolved in water to promote self assembly. The self assembly was characterised using mid and far infrared spectroscopy, small angle x ray scattering SAXS and atomic force microscopy AFM . IR measurements confirmed that all three samples were in a similar conformation, consistent with pseudo 14 helical secondary structures. Far infrared spectroscopy measurements of beta 3 [LIA] CONH2 showed distinct peaks consistent with highly organised skeletal modes, i.e. regular supramolecular assembly, that was largely absent from the other two oligoamides. Modelling of SAXS data is consistent with elliptical cylinder structures resulting from nanorod bundling for both beta 3 [LIA] CONH2 and Ac beta 3 [LIA], but not in the unmodified sample. Consistently, AFM imaging showed large nanorod bundling structures in beta 3 [LIA] CONH2, varied bundling structures in Ac beta 3 [LIA], and only aggregation in beta 3 [LIA]. Amidation showed much more organised and robust assembly compared to acetylation, providing a new, easy to synthesize self assembly motif for helical nanorod assembly that is similar but distinct to N acylation

Land‐use and climate change are significantly affecting stream ecosystems, yet understanding of their long‐term impacts is hindered by the few studies that have simultaneously investigated their interaction and high variability among future projections. We modeled possible effects of a suite of 2030, 2060, and 2090 land‐use and climate scenarios on the condition of 70,772 small streams in the Chesapeake Bay watershed, United States. The Chesapeake Basin‐wide Index of Biotic Integrity, a benthic macroinvertebrate multimetric index, was used to represent stream condition. Land‐use scenarios included four Special Report on Emissions Scenarios (A1B, A2, B1, and B2) representing a range of potential landscape futures. Future climate scenarios included quartiles of future climate changes from downscaled Coupled Model Intercomparison Project ‐ Phase 5 (CMIP5) and a watershed‐wide uniform scenario (Lynch2016). We employed random forests analysis to model individual and combined effects of land‐use and climate change on stream conditions. Individual scenarios suggest that by 2090, watershed‐wide conditions may exhibit anywhere from large degradations (e.g., scenarios A1B, A2, and the CMIP5 25th percentile) to small degradations (e.g., scenarios B1, B2, and Lynch2016). Combined land‐use and climate change scenarios highlighted their interaction and predicted, by 2090, watershed‐wide degradation in 16.2% (A2 CMIP5 25th percentile) to 1.0% (B2 Lynch2016) of stream kilometers. A goal for the Chesapeake Bay watershed is to restore 10% of stream kilometers over a 2008 baseline; our results suggest meeting and sustaining this goal until 2090 may require improvement in 11.0%–26.2% of stream kilometers, dependent on land‐use and climate scenario. These results highlight inherent variability among scenarios and the resultant uncertainty of predicted conditions, which reinforces the need to incorporate multiple scenarios of both land‐use (e.g., development, agriculture, etc.) and climate change in future studies to encapsulate the range of potential future conditions., Maps showing small NHDplusV2 catchments (

Substituted β3 oligoamides form a unique self-assembling system where each monomer folds into a helix containing approximately three β3 amino acids per turn, yielding a geometrically well-defined cylindrical building block that, when N-acylated, is able to self-assemble head-to-tail into nanorods that can reach several 100 μm length. It was shown in previous works that self-assembly can be achieved with a three residue long oligoamide as well that lacks any intramolecular H-bonds, yet it crystallizes in a helix-like conformation. The self-assembly properties of these small oligoamides are however elusive, suggesting a more complex system than the self-assembly of the H-bond stabilized helical monomers. Here we focus on the self-assembly behaviour of a three residue oligoamide, Ac-β3[LIA] where the letters denote the side chain of the analogous α amino acid. Ac-β3[LIA] can yield highly inhomogeneous suspensions in water with a broad range of large fibrous structures that seem to be very stable, yet occasionally fibre growth is only observed upon heating. The small size of the monomer suggests a highly dynamic equilibrium yet all previous attempts failed to clearly identify low molecular weight species. Therefore a special methodology was employed in this study to characterize the suspensions at different size ranges: SANS that is optimal to measure the small oligomers and cross sectional diameter of the assemblies, DLS that is sensitive to the large populations and therefore the length of the superstructures, and NMR that is sensitive to monomeric and small oligomeric form, in conjunction with IR spectroscopy to probe the folding and AFM to image the morphology of the assemblies. Temperature ramping was used to perturb the system to probe the dynamicity of the self-assembly. It was found that the anomalous self-assembly behaviour of Ac-β3[LIA] is caused by its two stable conformations, a helix-building “horseshoe” fold and a linear conformer. The latter is exclusively found in monomeric form in solution whereas the horseshoe fold is stable in solid phase and in fibrous assemblies. Small oligomers were absent. Thus the self-assembly of Ac-β3[LIA] is arrested by the activation energy need of the conformation change; fibre growth might be triggered by conditions that allow increased conformational freedom of the monomers. This observation may be used to develop strategies for controlled switchable self-assembly.

Understanding the temporal and spatial roles of nutrient limitation on phytoplankton growth is necessary for developing successful management strategies. Chesapeake Bay has well-documented seasonal and spatial variations in nutrient limitation, but it remains unknown whether these patterns of nutrient limitation have changed in response to nutrient management efforts. We analyzed historical data from nutrient bioassay experiments (1992–2002) and data from long-term, fixed-site water-quality monitoring program (1990–2017) to develop empirical approaches for predicting nutrient limitation in the surface waters of the mainstem Bay. Results from classification and regression trees (CART) matched the seasonal and spatial patterns of bioassay-based nutrient limitation in the 1992–2002 period much better than two simpler, non-statistical approaches. An ensemble approach of three selected CART models satisfactorily reproduced the bioassay-based results (classification rate = 99%). This empirical approach can be used to characterize nutrient limitation from long-term water-quality monitoring data on much broader geographic and temporal scales than would be feasible using bioassays, providing a new tool for informing water-quality management. Results from our application of the approach to 21 tidal monitoring stations for the period of 2007–2017 showed modest changes in nutrient limitation patterns, with expanded areas of nitrogen-limitation and contracted areas of nutrient saturation (i.e., not limited by nitrogen or phosphorus). These changes imply that long-term reductions in nitrogen load have led to expanded areas with nutrient-limited phytoplankton growth in the Bay, reflecting long-term water-quality improvements in the context of nutrient enrichment. However, nutrient limitation patterns remain unchanged in the majority of the mainstem, suggesting that nutrient loads should be further reduced to achieve a less nutrient-saturated ecosystem.

A primary goal for Chesapeake Bay watershed restoration is to improve stream health and function in 10% of stream miles by 2025. Predictive spatial modeling of stream conditions, when accur...

Substituted oligoamides are short sequences of unnatural amino acids. Oligoamides made entirely of amp; 946;3 amino acids yield helical monomers that, if N acylated, assemble into nanorod structures via a supramolecular assembly motif. In this work, coordination crosslinking was used to create complex nanomaterials fromoligoamides WKLWEL KE and WELWEL EE the letters denote the analogous amp; 945; amino acids . Upon Cu II addition, atomic force microscopy and small angle neutron scattering revealedmorphologic changes specific to KE but absent in EE. Vibration spectroscopymeasurements revealed that Cu II can coordinate to the amine moieties of the side chains, without direct effect on the backboneamides. While coordination in excess solvent lead to regular nanostructures, fast drying of the sample yielded oligoamide templated crystallization of CuCl2. The metal coordination crosslinking of supramolecular assemblies as reported here is the first realization of a metallosupramolecular framework structure

A Phytoplankton Index of Biotic Integrity (P-IBI) was developed from data collected during 18 yr 91985–2002) of the Chesapeake Bay Water Quality Monitoring Program. Dissolved inorganic nitrogen (DIN), orthophosphate (PO4), and Secchi depth were used to characterize phytoplankton habitat conditions. Low DIN and PO4 concentrations and high Secchi depths characterized least-impaire conditions. Thirty-eight phytoplankton metrics were tested for their ability to discriminate between impaired and least-impaired habitat conditions. Twelve discriminatory metrics were chosen, and different combinations of these twelve metrics were scored and used to create phytoplankton community indexes for spring and summer in the four salinity regimes in Chesapeake Bay. The scoring criteria for each metric were based on the distribution of the metric’s values in least-impaired conditions relative to the distribution in impaired conditions. An independent data set and jackknife validation procedure were used to examine P-IBI performance. The P-IBI correctly classified 70.0–84.4% of the impaired and least-impaired samples, grouped by season and salinity, in the calibration data set. The P-IBI is a management tool to assess phytoplankton community status relative to estuarine nutrient and light conditions.

Phytoplankton reference communities for Chesapeake Bay were quantified from least-impaired water quality conditions using commonly measured parameters and indicators derived from measured parameters. A binning approach was developed to classify water quality. Least-impaired conditions had relatively high water column transparency and low concentrations of dissolved inorganic nitrogen and orthophosphate. Reference communities in all seasons and salinity zones are characterized by consistently low values of chlorophylla and pheophytin coupled with relative stable proportions of the phytoplankton taxonomic groups and low biomasses of key bloom-forming species. Chlorophyll cell content was lower and less variable and average cell size and seasonal picophytoplankton biomass tended to be greater in the mesohaline and polyhaline reference communities as compared to the impaired communities. Biomass concentrations of the nano-micro phytoplankton size fractions (2–200 μm) in 12 of the 16 season-specific and salinity-specific reference communities were the same or higher than those in impaired habitat conditions, suggesting that nutrient reductions will not decrease the quantity of edible phytoplankton food available to large consumers. High (bloom) and low (bust) biomass events within the impaired phytoplankton communities showed strikingly different chlorophyll cell content and turnover rates. Freshwater flow had little effect on phytoplankton responses to water quality condition in most of the estuary. Improved water column transparency, or clarity, through the reduction of suspended sediments will be particularly important in attaining the reference communities. Significant nitrogen load reductions are also required.

In 2006, a phytoplankton index of biotic integrity (PIBI) was published for Chesapeake Bay Lacouture et al. (Estuaries 29(4):598–616, 2006). The PIBI was developed from data collected during the first 18 years (1985–2002) of the Chesapeake Bay Program long-term phytoplankton and water quality monitoring programs. Combinations of up to nine phytoplankton metrics were selected to characterize bay habitat health according to plankton community condition in spring and summer seasons across four salinity zones. The independent data available at the time for index validation was not sufficient to test the PIBI because they lacked critical index parameters (pheophytin and dissolved organic carbon) and reference samples for some seasons and salinity zones. An additional 8 years of monitoring data (2003–2010) are now available to validate the original index, reassess index performance and re-examine long-term trends in PIBI conditions in the Bay. The PIBI remains sensitive to changes in nutrient and light conditions. Evaluation of the PIBI results over the entire 1985–2010 time period shows no discernible trends in the overall health of Bay habitat based on phytoplankton community conditions. This lack of overall PIBI trend appears to be a combined response to declines in water clarity and improvements in dissolved inorganic nitrogen and dissolved phosphorus conditions in the bay.

A current-carrying resonant nanoscale device, simulated by non-adiabatic molecular dynamics, exhibits sharp activation of non-conservative current-induced forces with bias. The result, above the critical bias, is generalized rotational atomic motion with a large gain in kinetic energy. The activation exploits sharp features in the electronic structure, and constitutes, in effect, an ignition key for atomic-scale motors. A controlling factor for the effect is the non-equilibrium dynamical response matrix for small-amplitude atomic motion under current. This matrix can be found from the steady-state electronic structure by a simpler static calculation, providing a way to detect the likely appearance, or otherwise, of non-conservative dynamics, in advance of real-time modelling.

We evaluate the CyberKnife (Accuray Incorporated, Sunnyvale, CA, USA) for non-invasive delivery of accelerated partial breast irradiation (APBI) in early breast cancer patients. Between 6/2009 and 5/2011, nine patients were treated with CyberKnife APBI. Normal tissue constraints were imposed as outlined in the National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Therapy Oncology Group 0413 (NSABP/RTOG) Protocol (Vicini and White, 2007). Patients received a total dose of 30 Gy in five fractions (group 1, n = 2) or 34 Gy in 10 fractions (group 2, n = 7) delivered to the planning treatment volume (PTV) defined as the clinical target volume (CTV) +2 mm. The CTV was defined as either the lumpectomy cavity plus 10 mm (n = 2) or 15 mm (n = 7). The cavity was defined by a T2-weighted non-contrast breast MRI fused to a planning non-contrast thoracic CT. The CyberKnife Synchrony system tracked gold fiducials sutured into the cavity wall during lumpectomy. Treatments started 4-5 weeks after lumpectomy. The mean PTV was 100 cm(3) (range, 92-108 cm(3)) and 105 cm(3) (range, 49-241 cm(3)) and the mean PTV isodose prescription line was 70% for groups 1 and 2, respectively. The mean percent of whole breast reference volume receiving 100 and 50% of the dose (V(100) and V(50)) for group 1 was 11% (range, 8-13%) and 23% (range, 16-30%) and for group 2 was 11% (range, 7-14%) and 26% (range, 21-35.0%), respectively. At a median 7 months follow-up (range, 4-26 months), no acute toxicities were seen. Acute cosmetic outcomes were excellent or good in all patients; for those patients with more than 12 months follow-up the late cosmesis outcomes were excellent or good. In conclusion, the lack of observable acute side effects and current excellent/good cosmetic outcomes is promising. We believe this suggests the CyberKnife is a suitable non-invasive radiation platform for delivering APBI with achievable normal tissue constraints.

Zooplankton in the tidal, freshwater Potomac River were usually unstratified in the water column. Vertical mixing caused primarily by tides apparently prevented stratification, hence the classic pattern of diel vertical migration was not found. Larger grazers could occasionally concentrate in deeper waters during daylight hours, so the mean distributions of zooplankton grazing pressure was slightly skewed towards the bottom. Zooplankton tended to exhibit patchy horizontal distributions, and densities along river transects could vary by an order of magnitude. Populations of zooplankton grazers during the 1981 summer could hypothetically remove an average of of 1.1% to 3.7% of the water column's phytoplankton each day. Estimated values ranged as high as 9.7% day-1.