The detonation of a 10 Kiloton Improvised Nuclear Device (IND) is a serious scenario that the United States must be prepared to address. The likelihood of a single nuclear bomb exploding in a single city is greater today than at the height of the Cold War. Layered defenses against domestic nuclear terrorism indicate that our government continues to view the threat as credible. The risk of such an event is further evidenced by terrorists desire to acquire nuclear weapons. The act of nuclear terrorism, particularly an act directed against a large population center in the United States, will overwhelm the capabilities of many local and state governments to respond, and will seriously challenge existing federal response capabilities. A 10 Kiloton IND detonation would cause total infrastructure damage in a 3-mile radius and levels of radiation spanning out 3,000 square miles. In a densely populated urban area, the anticipated casualties would be in excess of several hundred thousand. Although there would be enormous loss of life, housing and infrastructure, an IND detonation is a recoverable event. We can reduce the risk of these high-consequence, nontraditional threats by enhancing our nuclear detection architecture and establishing well planned and rehearsed plans for coordinated …

Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin-protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase …

We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10 cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of {approx}80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10 cGy, some with suggestive evidence that transcription was modulated at doses below 1 cGy. MYC, FOS and TP53 were the major network nodes of the low-dose response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types …

Article discussing the synergy between qualitative theory, quantitative calculations, and direct experiments in understanding, calculating, and measuring the energy differences between the lowest singlet and triplet states of organic diradicals.