A follow-up study of 100 reading disability cases, now adults, who were associated with the Boston University Education Clinic between 1936-1948

Thesis (Ed.M.)--Boston Universit

Transducers Applied to Measurements of Velocity Dispersion of Acoustic Surface Waves

This talk concerns two new acoustic surface wave (SAW) transducer units developed and applied to the field of nondestructive testing. We confine ourselves here to tone burst transduction of Rayleigh waves (at MHz frequencies), although CW operation and (for example) Lamb and bulk waves are also possible

Structural basis of mitochondrial receptor binding and constriction by DRP1.

Mitochondrial inheritance, genome maintenance and metabolic adaptation depend on organelle fission by dynamin-related protein 1 (DRP1) and its mitochondrial receptors. DRP1 receptors include the paralogues mitochondrial dynamics proteins of 49 and 51 kDa (MID49 and MID51) and mitochondrial fission factor (MFF); however, the mechanisms by which these proteins recruit and regulate DRP1 are unknown. Here we present a cryo-electron microscopy structure of full-length human DRP1 co-assembled with MID49 and an analysis of structure- and disease-based mutations. We report that GTP induces a marked elongation and rotation of the GTPase domain, bundle-signalling element and connecting hinge loops of DRP1. In this conformation, a network of multivalent interactions promotes the polymerization of a linear DRP1 filament with MID49 or MID51. After co-assembly, GTP hydrolysis and exchange lead to MID receptor dissociation, filament shortening and curling of DRP1 oligomers into constricted and closed rings. Together, these views of full-length, receptor- and nucleotide-bound conformations reveal how DRP1 performs mechanical work through nucleotide-driven allostery

Ecological history affects zooplankton community responses to acidification

The effects of ecological history are frequently ignored in attempts to predict community responses to environmental change. In this study, we explored the possibility that ecological history can cause differences in community responses to perturbation using parallel acidification experiments in three sites with different pH histories in the Northern Highland Lake District of Wisconsin, USA. In Trout Lake, high acid neutralizing capacity had historically buffered changes in pH. In contrast, the two basins of Little Rock Lake (Little Rock-Reference and Little Rock-Treatment) had experienced seasonal fluctuations in pH. Furthermore, the two lake basins were separated with a curtain and Little Rock-Treatment was experimentally acidified in the late 1980s. In each site, we conducted mesocosm experiments to compare zooplankton community dynamics in control (ambient pH) and acidified (pH 4.7) treatments. Zooplankton community responses were strongest in Trout Lake and weakest in Little Rock-Treatment suggesting that ecological history affected responses to acidification. In part, variation in community sensitivity to acidification was driven by differences in species composition. However, the results of a reciprocal transplant experiment indicated that changes in the acid tolerance of populations during past acidification events may make zooplankton communities less sensitive to subsequent pH stress. Our study highlights the role that ecological history may play in community-level responses to environmental change

Trajectories Of Zooplankton Recovery In The Little Rock Lake Whole‐Lake Acidification Experiment

Understanding the factors that affect biological recovery from environmental stressors such as acidification is an important challenge in ecology. Here we report on zooplankton community recovery following the experimental acidification of Little Rock Lake, Wisconsin, USA. One decade following cessation of acid additions to the northern basin of Little Rock Lake (LRL), recovery of the zooplankton community was complete. Approximately 40% of zooplankton species in the lake exhibited a recovery lag in which biological recovery to reference basin levels was delayed by 1–6 yr after pH recovered to the level at which the species originally responded. Delays in recovery such as those we observed in LRL may be attributable to “biological resistance” wherein establishment of viable populations of key acid-sensitive species following water quality improvements is prevented by other components of the community that thrived during acidification. Indeed, we observed that the recovery of species that thrived during acidification tended to precede recovery of species that declined during acidification. In addition, correspondence analysis indicated that the zooplankton community followed different pathways during acidification and recovery, suggesting that there is substantial hysteresis in zooplankton recovery from acidification. By providing an example of a relatively rapid recovery from short-term acidification, zooplankton community recovery from experimental acidification in LRL generally reinforces the positive outlook for recovery reported for other acidified lakes

Cationic lipid-based nanoparticles mediate functional delivery of acetate to tumor cells in vivo leading to significant anticancer effects

Metabolic reengineering using nanoparticle delivery represents an innovative therapeutic approach to normalizing the deregulation of cellular metabolism underlying many diseases, including cancer. Here, we demonstrated a unique and novel application to the treatment of malignancy using a short-chain fatty acid (SCFA)-encapsulated lipid-based delivery system – liposome-encapsulated acetate nanoparticles for cancer applications (LITA-CAN). We assessed chronic in vivo administration of our nanoparticle in three separate murine models of colorectal cancer. We demonstrated a substantial reduction in tumor growth in the xenograft model of colorectal cancer cell lines HT-29, HCT-116 p53+/+ and HCT-116 p53-/-. Nanoparticle-induced reductions in histone deacetylase gene expression indicated a potential mechanism for these anti-proliferative effects. Together, these results indicated that LITA-CAN could be used as an effective direct or adjunct therapy to treat malignant transformation in vivo

Multi-Pulse Terahertz Spectroscopy Unveils Hot Polaron Photoconductivity Dynamics in Metal-Halide Perovskites

The behavior of hot carriers in metal-halide perovskites (MHPs) present a valuable foundation for understanding the details of carrier-phonon coupling in the materials as well as the prospective development of highly efficient hot carrier and carrier multiplication solar cells. Whilst the carrier population dynamics during cooling have been intensely studied, the evolution of the hot carrier properties, namely the hot carrier mobility, remain largely unexplored. To address this, we introduce a novel ultrafast visible pump - infrared push - terahertz probe spectroscopy (PPP-THz) to monitor the real-time conductivity dynamics of cooling carriers in methylammonium lead iodide. We find a decrease in mobility upon optically depositing energy into the carriers, which is typical of band-transport. Surprisingly, the conductivity recovery dynamics are incommensurate with the intraband relaxation measured by an analogous experiment with an infrared probe (PPP- IR), and exhibit a negligible dependence on the density of hot carriers. These results and the kinetic modelling reveal the importance of highly-localized lattice heating on the mobility of the hot electronic states. This collective polaron-lattice phenomenon may contribute to the unusual photophysics observed in MHPs and should be accounted for in devices that utilize hot carriers.Comment: 28 pages, 4 figures, 77 reference