FRACAS: A Computerized Aid for Reasoning in Tax

Problem solving in the tax domain requires two kinds of knowledge: of the law itself and of how the law has been applied in the past. The need for the second factor arises as a result of the ambiguity of natural language. The problem solver requires information on how the courts have adjudicated specific cases in the past. This information would then provide the basis for reasoning about the current case. In this paper we address the issue of developing a system which will retrieve relevant historical cases. The cases are stored using a frame representation scheme and the users can retrieve cases by specifying either attributes alone or attributes and values associated with them. Currently the system has been implemented in Pascal on a Cray. The case base contains 250 cases relating to Section 183 of the tax code.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106676/1/isaf00012.pd

Something Old, Something New, Something Borrowed; How the Thermoacidophilic Archaeon Sulfolobus solfataricus Responds to Oxidative Stress

To avoid molecular damage of biomolecules due to oxidation, all cells have evolved constitutive and responsive systems to mitigate and repair chemical modifications. Archaea have adapted to some of the most extreme environments known to support life, including highly oxidizing conditions. However, in comparison to bacteria and eukaryotes, relatively little is known about the biology and biochemistry of archaea in response to changing conditions and repair of oxidative damage. In this study transcriptome, proteome, and chemical reactivity analyses of hydrogen peroxide (H2O2) induced oxidative stress in Sulfolobus solfataricus (P2) were conducted. Microarray analysis of mRNA expression showed that 102 transcripts were regulated by at least 1.5 fold, 30 minutes after exposure to 30 µM H2O2. Parallel proteomic analyses using two-dimensional differential gel electrophoresis (2D-DIGE), monitored more than 800 proteins 30 and 105 minutes after exposure and found that 18 had significant changes in abundance. A recently characterized ferritin-like antioxidant protein, DPSL, was the most highly regulated species of mRNA and protein, in addition to being post-translationally modified. As expected, a number of antioxidant related mRNAs and proteins were differentially regulated. Three of these, DPSL, superoxide dismutase, and peroxiredoxin were shown to interact and likely form a novel supramolecular complex for mitigating oxidative damage. A scheme for the ability of this complex to perform multi-step reactions is presented. Despite the central role played by DPSL, cells maintained a lower level of protection after disruption of the dpsl gene, indicating a level of redundancy in the oxidative stress pathways of S. solfataricus. This work provides the first “omics” scale assessment of the oxidative stress response for an archeal organism and together with a network analysis using data from previous studies on bacteria and eukaryotes reveals evolutionarily conserved pathways where complex and overlapping defense mechanisms protect against oxygen toxicity

Thyroid cancer following childhood low dose radiation exposure::a pooled analysis of nine cohorts

Context: The increased use of diagnostic and therapeutic procedures that involve radiation raises concerns about radiation effects, particularly in children and the radiosensitive thyroid gland.Objectives: Evaluation of relative risk (RR) trends for thyroid radiation doses &lt;0.2 gray (Gy); evidence of a threshold dose; and possible modifiers of the dose-response, e.g., sex, age at exposure, time since exposure.Design and Setting: Pooled data from nine cohort studies of childhood external radiation exposure and thyroid cancer with individualized dose estimates, ≥1000 irradiated subjects or ≥10 thyroid cancer cases, with data limited to individuals receiving doses &lt;0.2 Gy.Participants: Cohorts included the following: childhood cancer survivors (n = 2); children treated for benign diseases (n = 6); and children who survived the atomic bombings in Japan (n = 1). There were 252 cases and 2,588,559 person-years in irradiated individuals and 142 cases and 1,865,957 person-years in nonirradiated individuals.Intervention: There were no interventions.Main Outcome Measure: Incident thyroid cancers.Results: For both &lt;0.2 and &lt;0.1 Gy, RRs increased with thyroid dose (P &lt; 0.01), without significant departure from linearity (P = 0.77 and P = 0.66, respectively). Estimates of threshold dose ranged from 0.0 to 0.03 Gy, with an upper 95% confidence bound of 0.04 Gy. The increasing dose–response trend persisted &gt;45 years after exposure, was greater at younger age at exposure and younger attained age, and was similar by sex and number of treatments.Conclusions: Our analyses reaffirmed linearity of the dose response as the most plausible relationship for “as low as reasonably achievable” assessments for pediatric low-dose radiation-associated thyroid cancer risk.</p

Unprecedented high-resolution view of bacterial operon architecture revealed by RNA sequencing

We analyzed the transcriptome of Escherichia coli K-12 by strand-specific RNA sequencing at single-nucleotide resolution during steady-state (logarithmic-phase) growth and upon entry into stationary phase in glucose minimal medium. To generate high-resolution transcriptome maps, we developed an organizational schema which showed that in practice only three features are required to define operon architecture: the promoter, terminator, and deep RNA sequence read coverage. We precisely annotated 2,122 promoters and 1,774 terminators, defining 1,510 operons with an average of 1.98 genes per operon. Our analyses revealed an unprecedented view of E. coli operon architecture. A large proportion (36%) of operons are complex with internal promoters or terminators that generate multiple transcription units. For 43% of operons, we observed differential expression of polycistronic genes, despite being in the same operons, indicating that E. coli operon architecture allows fine-tuning of gene expression. We found that 276 of 370 convergent operons terminate inefficiently, generating complementary 3′ transcript ends which overlap on average by 286 nucleotides, and 136 of 388 divergent operons have promoters arranged such that their 5′ ends overlap on average by 168 nucleotides. We found 89 antisense transcripts of 397-nucleotide average length, 7 unannotated transcripts within intergenic regions, and 18 sense transcripts that completely overlap operons on the opposite strand. Of 519 overlapping transcripts, 75% correspond to sequences that are highly conserved in E. coli (>50 genomes). Our data extend recent studies showing unexpected transcriptome complexity in several bacteria and suggest that antisense RNA regulation is widespread.Ye

The Synthesis and Characterization of Pegylated Dendrimers

In this work a mPEG(5000) block poly(ether sulfide) dendrimer was functionalized with glutathione, cysteamine, methyl 3-mercaptopropionate, ethylene diamine, 5-hydroxy-2-phenyl-[1,3]-dioxane, and 5-methyl-2-(2,4,6-trimethoxyphenyl)-[1,3]-5-dioxanylmethanol. The derivatives were characterized using NMR and the critical micelle concentration of several derivatives was measured using fluorescence spectroscopy using pyrene. The degradation of 5-hydroxy-2-phenyl-[1,3]-dioxane, and 5-methyl-2-(2,4,6-trimethoxyphenyl)-[1,3]-5-dioxanylmethanol was monitored by measuring the release of encapsulated Nile red dye using fluorescence spectroscopy at pH 5.0 and 7.4. An mPEG (5000) block poly(amino sulfide) dendrimer was synthesized using thiol-ene and epoxy-amine click chemistry and characterized using NMR. The starting materials used were cysteamine hydrochloride, allyl glycidyl ether and mPEG-NH2