Lessons Learned from Personal Experience in Adaptive Reuse

This presentation details themes, regarding sustainability, from three adaptive reuse projects of Brutalist and post-war Modernist structures, accentuating overlaps with sustainability, embodied carbon, preservation, densification, and urbanization – all hallmarks regarding the adaptive reuse of these buildings. The first project illustrates opportunities created by up-branding a 1970’s era Sheraton into a “new” W Hotel (Midtown, Atlanta), whereby the preservation of the concrete playfully juxtaposed new interior/exterior design elements. The second project looks at the transformation of a purpose-built newspaper headquarters into a “new” LEED/Fitwel certified commercial facility, which reknit previously separated neighborhoods into a pedestrian/transit-oriented destination, serving as a catalyst for future growth/density within a previously auto-centric community (Dorchester, MA). The third example explores the drafting of a Request for Proposals (RFP), which the City of Boston utilized to solicit bids to reimagine the Paul Rudolf designed Erich Lindemann Mental Health Center site, encouraging the adaption/preservation of the existing building as part of a larger complex and realization of the original vision for the site by the architect. In conclusion, the presentation addresses challenges and opportunities with adaptive reuse of buildings of this vintage, including thermal bridging, municipal decarbonization efforts, and efforts by professional organizations to curb embodied carbon

Self-assembled ErAs islands in GaAs for optical-heterodyne THz generation

We report photomixer devices fabricated on a material consisting of self-assembled ErAs islands in GaAs, which is grown by molecular beam epitaxy. The devices perform comparably and provide an alternative to those made from low-temperature-grown GaAs. The photomixer's frequency response demonstrates that the material is a photoconductor with subpicosecond response time, in agreement with time-resolved differential reflectance measurements. The material also provides the other needed properties such as high photocarrier mobility and high breakdown field, which exceeds 2×10^5 V/cm. The maximum output power before device failure at frequencies of 1 THz was of order 0.1 µW. This material has the potential to allow engineering of key photomixer properties such as the response time and dark resistance

Answering Two OPAC Problems Involving Banff Quivers

In a post on the Open Problems in Algebraic Combinatorics (OPAC) blog, E. Bucher and J. Machacek posed three open problems: OPAC-033, OPAC-034, and OPAC-035. These three problems deal with the relationships between three infinite classes of quivers: the Banff, Louise, and $\mathcal{P}$ quivers. OPAC-034 asks whether or not every Banff quiver can be verified to be Banff by only considering sources and sinks, and OPAC-035 asks whether or not every Banff quiver is contained in the class $\mathcal{P}$. We give an answer to both questions, showing that every Banff quiver can be verified to be Banff by using sources and sinks, and therefore that every Banff quiver lives in the class $\mathcal{P}$. We also make some progress on OPAC-033, showing a result similar to our result OPAC-034 for Louise quivers.Comment: 10 pages, 1 figur

Traveling-Wave Photomixers Based On Noncollinear Optical/Terahertz Phase-Matching

Traveling-wave THz photomixers based on angle-tuned optical/THz phase-matching are experimentally demonstrated. A dc-biased coplanar stripline terminated by a planar antenna is fabricated on low-temperature-grown GaAs. A distributed area between the striplines is illuminated by two noncollinear laser beams which generate interference fringes accompanied by THz waves. The velocity of the optical fringe is matched to the THz-wave velocity in the stripline by tuning the incident angle of the laser beams. The device can handle the laser power over 300 mW and provides the THz output of ~0.1 µW with the 3-dB bandwidth of 2 THz. The experimental results show that traveling-wave photomixers have the potential to surpass conventional small area designs

Design and characterization of optical-THz phase-matched traveling-wave photomixers

Design and characterization of optical-THz phase-matched traveling-wave photomixers for difference-frequency generation of THz waves are presented. A de-biased coplanar stripline fabricated on low-temperature-grown GaAs is illuminated by two non-collinear laser beams which generate moving interference fringes that are accompanied by THz waves. By tuning the offset angle between the two laser beams, the velocity of the interference fringe can be matched to the phase velocity of the THz wave in the coplanar stripline. The generated THz waves are radiated into free space by the antenna at the termination of the stripline. Enhancement of the output power was clearly observed when the phase-matching condition was satisfied. The output power spectrum has a 3-dB bandwidth of 2 THz and rolls off as ~9 dB/Oct which is determined by the frequency dependent attenuation in the stripline, while the bandwidth of conventional photomixer design has the limitation by the RC time constant due to the electrode capacitance. The device can handle the laser power of over 380 mW, which is 5 times higher than the maximum power handring capability of conventional small area devices. The results show that the traveling-wave photomixers have the potential to surpass small area designs, especially at higher frequencies over I THz, owing to their great thermal dissipation capability and capacitance-free wide bandwidth

A traveling-wave THz photomixer based on angle-tuned phase matching

A traveling-wave THz photomixer based on a free-space optical-THz phase-matching scheme is proposed. A dc-biased coplanar strip line fabricated on low-temperature-grown GaAs serves as the active area of the device, and is illuminated by two noncollinear laser beams which generate interference fringes that are accompanied by THz waves. The device with the laser-power-handling capability over 300 mW and a 3-dB bandwidth of 1.8 THz was experimentally demonstrated. The results show that traveling-wave photomixers have the potential to surpass small-area designs

X-ray structure determination using low-resolution electron microscopy maps for molecular replacement

Structures of multisubunit macromolecular machines are primarily determined either by electron microscopy (EM) or by X-ray crystallography. In many cases, a structure for a complex can be obtained at low resolution (at a coarse level of detail) with EM and at a higher resolution (with finer detail) by X-ray crystallography. The integration of these two structural techniques is becoming increasingly important for the generation of atomic models of macromolecular complexes. A low-resolution EM image can be a powerful tool for obtaining the 'phase' information that is missing from an X-ray crystallography experiment; however, integration of EM and X-ray diffraction data has been technically challenging. Here we present a step-by-step protocol that explains how low-resolution EM maps can be placed in the crystallographic unit cell by molecular replacement, and how initial phases computed from the placed EM density are extended to high resolution by averaging maps over noncrystallographic symmetry. As the resolution gap between EM and X-ray crystallography continues to narrow, the use of EM maps to help with X-ray crystal structure determination, as described in this protocol, will become increasingly effective.R.N.J. is supported by the National Research Service Award postdoctoral fellowship (F32 GM108436) from the US National Institutes of Health (NIH). R.J.R. and T.C.T. are supported by a grant (GM063210) from the NIH. R.J.R. is supported by a Principal Research Fellowship from the Wellcome Trust (grant no. 082961/Z/07/Z). Research in the Wiedenheft lab is supported by the NIH IDeA Program COBRE (GM110732), an R01 to B.W. (GM108888), the National Science Foundation EPSCoR (EPS-110134), the M.J. Murdock Charitable Trust and the Montana State University Agricultural Experimental Station.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/nprot.2015.06

Doing memory work with older men: the practicalities, the process, the potential

This article describes the process of setting up and participating in a collective memory work group of older men, with a focus on the making and unmaking of older men and masculinities through age, ageing, gender, gendering, and other intersections. Memory work is located in relation to related but different forms of writing and group work, emphasizing how in this method everyone becomes a writer, an author, a listener, a reader, a discussant, and a commentator. The potential of memory work, both for working with older men, and more generally is outlined. Key issues are: genuine and collective commitment to substantive change, not just at a personal level, but also at wider social/political/cultural levels; willingness to trust in the other members of the group, an issue that may be difficult for some men; and commitment for caring for one another especially in their moments of greatest vulnerability