A novel approach to correcting TeT_e-based mass-metallicity relations

Deriving oxygen abundances from the electron temperature (hereafter the $T_e$-method) is the gold-standard for extragalactic metallicity studies. However, unresolved temperature fluctuations within individual HII regions and across different HII regions throughout a galaxy can bias metallicity estimates low, with a magnitude that depends on the underlying and typically unknown temperature distribution. Using a toy model, we confirm that computing $T_e$-based metallicities using the temperature derived from the [O III] $\lambda$4363/$\lambda$5007 or [O II] $\lambda\lambda$7320,7330 / [O II] $\lambda\lambda$3727 ratio ('ratio temperature'; $T_{\rm ratio}$) results in an underprediction of metallicity when temperature fluctuations are present. In contrast, using the unobservable 'line temperatures' ($T_{\rm line}$) that provide the mean electron and ion density-weighted emissivity yield an accurate metallicity estimate. To correct this bias in low-mass galaxies, we demonstrate an example calibration of a relation between T_ratio and T_line based on a high-resolution (4.5 pc) RAMSES-RTZ simulation of a dwarf galaxy that self-consistently models the formation of multiple HII regions and ion temperature distribution in a galactic context. Applying this correction to the low-mass end of the mass-metallicity relation shifts its normalization up by 0.18 dex on average and flattens its slope from 0.87 to 0.58, highlighting the need for future studies to account for, and correct, this bias.Comment: 6 pages, 6 figures, accepted for publication in MNRA

CLAIMING MARKET PLACE

CLAIMING MARKET PLACE UMass Amherst Design Center in Springfield Department of Landscape Architecture & Regional Planning The Senior Urban Design Studio developed a tangible vision for the revitalization of downtown Springfield through creating ideas for the underutilized Market Place block and reconnect it to the urban fabric. We carried out small-scale, temporary urban design installations as wayfinding interventions in the spirit of “tactical urbanism”. These interventions had a real target: the students’ work supported the opening of the Holiday Market in the Market Street block from Thanksgiving to Christmas. The interventions were taken one step further with the development of phased design drawings. The designs support safer walking and bicycling, possibilities to sit and relax, and art-inspired media such as artificial light and color. Market Place has a prominent location within Downtown Springfield. The site is placed around several hot-spots including the Mass Mutual Center, Symphony Hall, Tower Square, and of course Main Street. These main attractions in the core of Downtown Springfield foster great opportunities for pedestrian interaction with Market Place. Project Goals: Claiming Market Place as a destination for residents, employees, and visitors through creation of an active and diverse space that contributes to the positive future of the City of Springfield. Providing elegant and pleasant walking connections to Main Street and downtown assets while creating attractive and legible entrances to Market Street. Creating short-term interventions to raise publicity for Market Place. Creating long-term design and programmatic solutions that respect place and people while creating new and meaningful layers through landscape media. The work explores a community service learning strategy within the framework of an urban design studio with the goal of revitalizing the city of Springfield, Massachusetts, through sustainable design, planning, and engagement with the community

A Mobile Concrete Laboratory to Support Quality Concrete, Technology Transfer, and Training

This report is a summary of work performed by the Mobile Infrastructure Materials Testing Laboratory (MIMTL) as a part of the Joint Transportation Research Program (JTRP) through SPR-3858. The development of the MIMTL began in February of 2014 and became fully operational by June of 2014. The MIMTL was deployed in the field for a total of 46 days. This report describes the activities of the MIMTL as of December 2015. The MIMTL was involved in the field testing of concrete bridges, concrete pavements, and asphalt pavements. This report describes the development of the mobile testing laboratory and provides some examples of how the MIMTL was used. The main highlights of the MIMTL’s implementation are as follows: The MIMTL’s high mobility and extensive inventory of research equipment allowed graduate students and researchers to conduct field studies on a wide range of infrastructure materials to accomplish the research objectives of their specific projects. More extensive details of the background, objectives, methods, findings, results and implementation from those projects can be found in the respective reports for those projects; The MIMTL supported a culture of safety that allowed students to work safely on jobsites in the State of Indiana ranging from roadside interstates, rural country roads, to ready-mix batching plants, often around heavy equipment, traffic, and in close quarters. During the operation of the MTIML described in this report, there were zero workplace accidents, and zero near misses reported; The MIMTL assisted in technology transfer between the infrastructure materials experts at Purdue University and contractors and suppliers in the State of Indiana. A wide range of new technologies evaluating infrastructure materials were utilized on a variety of projects. On each of these projects, MIMTL researchers educated industry personnel (contractors and suppliers), agency personnel (INDOT and local agencies), and consultants within the state. The MIMTL attended demonstrations with INDOT district and central office personnel to further highlight capabilities as well as the emerging technologies; The MIMTL was established a joint investment with partners in industry, local agencies, and INDOT. Operated by the Joint Transportation Research Program and the Local Technical Assistance Program as pay-per-use model, means this sustainable venture will offer services to researchers, industry, or agency entities that can cover the pay-per-use costs

The Physics of Indirect Estimators of Lyman Continuum Escape and their Application to High-Redshift JWST Galaxies

Reliable indirect diagnostics of LyC photon escape from galaxies are required to understand which sources were the dominant contributors to reionization. While multiple escape fraction ($f_{\rm esc}$) indicators have been proposed to trace favourable conditions for LyC leakage from the interstellar medium of low-redshift ``analog'' galaxies, it remains unclear whether these are applicable at high redshifts where LyC emission cannot be directly observed. Using a library of 14,120 mock spectra of star-forming galaxies with redshifts $4.64 \leq z \leq 10$ from the SPHINX$^{20}$ cosmological radiation hydrodynamics simulation, we develop a framework for the physics that leads to high $f_{\rm esc}$. We investigate LyC leakage from our galaxies based on the criteria that successful LyC escape diagnostics must \textit{i)} track a high specific star formation rate, \textit{ii)} be sensitive to stellar population age in the range $3.5-10$~Myr representing the times when supernova first explode to when LyC production significantly drops, and \textit{iii)} include a proxy for neutral gas content and gas density in the interstellar medium. ${\rm O}_{32}$, $\Sigma_{\rm SFR}$, M$_{\rm UV}$, and H$\beta$ equivalent width select for one or fewer of our criteria, rendering them either necessary but insufficient or generally poor diagnostics. In contrast, UV slope ($\beta$), and ${\rm E(B-V)}$ match two or more of our criteria, rendering them good $f_{\rm esc}$ diagnostics (albeit with significant scatter). Using our library, we build a quantitative model for predicting $f_{\rm esc}$ based on $\beta$, ${\rm E(B-V)}$, H$\beta$, M$_{\rm UV}$, ${\rm R_{23}}$, and ${\rm O_{32}}$. When applied to bright $z > 6$ Ly$\alpha$ emitters observed with JWST, we find that the majority of them have $f_{\rm esc} \lesssim 10\%$.Comment: 16 pages, 15 figures, 1 table, submitted to MNRA

Data Collection at Fifteen Selected Creeks in Support of Shallow Water Dredging on Virginia’s Middle Peninsula - Methods & Data Report

Federal funding has been historically available for the Army Corps of Engineers for shallow draft navigation projects. However, past and recent subsidies have not provided ample funding at levels to sustain maintenance dredging for the 17 federal navigation channels on the Middle Peninsula. Further, funding for maintenance of non-federal channels has been historically neglected by the Commonwealth of Virginia until the Virginia General Assembly established the Virginia Waterway Maintenance Fund in 2018. For the past decade the Middle Peninsula Chesapeake Bay Public Access Authority, the Middle Peninsula Planning District Commission and its member jurisdictions, and the Virginia Institute of Marine Science Shoreline Studies Program have worked to advance local solutions and alternatives to address dredging needs in the Commonwealth

Simple photocleavable indoline-based materials for surface wettability patterning

There is a continued interest for smart surfaces that can transition between being hydrophobic or hydrophilic on-demand. Surfaces that can be switched with light are highly attractive, where the wettability properties of the surface or photopatterned water channels can be remotely controlled. However, many existing systems are complex, rely on synthetically challenging materials, lack reproducibility, or involve costly and intricate fabrication methods. Here, we introduce a straightforward approach using indoline-based, small molecules for the simple and precise control of a surface’s wettability, using UV light as the external trigger. The wettability transition is accomplished through the photocleavage of the o-nitroanilide moieties, resulting in substantial water contact angle changes of up to 61°. Simplicity is achieved through solution-based spin-coating for material deposition, while each of the photoproducts were investigated using UV−vis and NMR studies, concluding that photocleave was fast and efficient (both in solution and the solid-state). Each material showed complete thermal stability within their operational range, while the best performing materials, 7-OH and 9-OH, produced smooth, high-quality coatings (RMS 0.24 and 0.50 nm, respectively). Furthermore, we demonstrated their use for wettability patterning and water channel creation, highlighting the materials suitability for integration in smart surfaces. This work offers an extremely accessible pathway to develop light-activated responsive surfaces