Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.Comment: version in press, Physical Review Letters; 17 pages, 5 figures (includes supplementary material

Baseball Stadium in Baltimore, Maryland

Baseball Stadium in Baltimore, Maryland. Britton award winner, thesis board

Thesis Board by Jon Eric Moss

Thesis Board, Britton Award Winner. Photographs of Site Model and Model

The Indigent as King

On New York\u27s Lower East Side in the midst of burned out tenements and drugged out neighbors, Adam Purple, notorious Manhattan eccentric, willed his cosmological vision into existence

Stage-Specific Timing of the microRNA Regulation of \u3cem\u3elin-28\u3c/em\u3e by the Heterochronic Gene \u3cem\u3elin-14\u3c/em\u3e in \u3cem\u3eCaenorhabditis elegans\u3c/em\u3e

In normal development, the order and synchrony of diverse developmental events must be explicitly controlled. In the nematode Caenorhabditis elegans, the timing of larval events is regulated by hierarchy of proteins and microRNAs (miRNAs) known as the heterochronic pathway. These regulators are organized in feedforward and feedback interactions to form a robust mechanism for specifying the timing and execution of cell fates at successive stages. One member of this pathway is the RNA binding protein LIN-28, which promotes pluripotency and cell fate decisions in successive stages. Two genetic circuits control LIN-28 abundance: it is negatively regulated by the miRNA lin-4, and positively regulated by the transcription factor LIN-14 through a mechanism that was previously unknown. In this report, we used animals that lack lin-4 to elucidate LIN-14’s activity in this circuit. We demonstrate that three let-7 family miRNAs—miR-48, miR-84, and miR-241—inhibit lin-28 expression. Furthermore, we show genetically that these miRNAs act between lin-14 and lin-28, and that they comprise the pathway by which lin-14 positively regulates lin-28. We also show that the lin-4 family member mir-237, also regulates early cell fates. Finally, we show that the expression of these miRNAs is directly inhibited by lin-14 activity, making them the first known targets of lin-14 that act in the heterochronic pathway

Evolutionary Conservation of the Heterochronic Pathway in C. elegans and C. briggsae

Heterochronic genes control the sequence and timing of developmental events during four larval stages of Caenorhabitis nematodes. Mutations in these genes may cause skipping or reiteration of developmental events. C. briggsae is a close relative of C. elegans. These species have similar morphology and share the same ecological niche. C. briggsae undergoes the same developmental pathway consisting of four larval stages before reaching adulthood. It also has the same set of heterochronic genes. Lin-28 is one of the heterochronic genes that also exists in other animals from flies to humans. It conservatively blocks the maturation of let-7 miRNA, the process is generally associated with the stem cell state. lin-28 is silenced as cells differentiate. C. elegans mutants of lin-28 have a reduced number of seam cells and precocious alae. Despite the highly conserved protein sequence, C. briggsae develop a distinct phenotype when its lin 28 is disrupted. Worms did not have a characteristic vulval development defect, they also became lethargic and had a reduced fertility. This observation led to a question of how conserved the heterochronic pathway is in close species

Conservation and Divergence in the Heterochronic Pathway of C. elegans and C. briggsae

The heterochronic pathway of Caenorhabditis elegans is exemplary as a mechanism of developmental timing: mutations in genes of this pathway alter the relative timing of diverse developmental events independent of spatial or cell type specific regulation. It is the most thoroughly characterized developmental timing pathway known. Most of the heterochronic genes are conserved across great evolutionary time, and a few homologs seem to have developmental timing roles in certain contexts. The degree to which other organisms have explicit developmental timing mechanisms, and what factors comprise those mechanisms, isn’t generally known. Developmental pathways evolve even if the resulting morphology remains the same, a phenomenon called Developmental Systems Drift. Components of developmental pathways and their roles may stay the same over time, their relationships to each other may change, or new factors can join or leave a pathway as it evolves, while still producing the same developmental result. It is known, for example, that the components and relationships of certain spatial patterning pathways are largely conserved widely. But in sex determination, for example, the pathways evolve rapidly and those of even closely related organisms can differ dramatically. We set out to explore the evolution of this well-characterized developmental timing pathway by characterizing the phenotypes of the heterochronic gene orthologs in a closely related nematode C. briggsae. These species share the same ecological niche and are nearly identical in development and morphology. Both worms develop after hatching through four larval stages (L1-L4) before reaching adulthood. Both develop the egg laying system, including the vulva, during the L3 and L4. Lateral hypodermal cells divide and add nuclei to a syncytium at each larval stage and diffentiate at adulthood producing a cuticle structure called alae, a feature we use to characterize heterochronic mutants

Urban Stadium

Certain major urban elements have been pished into suburban environments to the detriment of cities. The thesis proposed that through investigating the implications of reinserting such a building into the urban condition, it can be demonstrated that both the city and the facility will benefit. The vehicle is the design of a public building which must mediate between its needs and its urban conditions. The project therefore should have a program which has specific requirements and the site should have a strong urban dynamic

Definition of the sea surface infrared sun glitter corridor

Measurements of sea surface radiance were made in the 2-5.6 and 8-14 um wavebands near the azimuth of the sun at low solar observation angles. From these measurement, an analysis of the statistical and physical nature of a sun glitter channel as presented to a low altitude observer (i.e. shipboard) was conducted. findings showed strong correlations between wind speed and corridor width, and between wind speed and strength of source radiance, dominated primarily by the direct solar reflected contribution to sea radiance. 8-14 um radiances showed far less susceptibility to the detrimental effects of sun glitter on IE sensing systems. All patterns were Gaussian in shape across the azimuthal extent of each glitter corridor. The magnitude of glinting radiances decreased with increasing depression angles, presenting an approximate half Gaussian radiance distribution in elevation. A method to convert apparent radiant (as received at the sensor) to equivalent zero-range blackbody source radiance was formulated but showed weaknesses in computing the path radiance of the atmosphere intervening between the sea and the AGA 780 sensor, and in accounting for the emissivity of the sea surface as it affected the self-emitted component of sea surface source radiance.http://archive.org/details/definitionofseas00mossLieutenant, United States NavyApproved for public release; distribution is unlimited