Dreams, Twilight Dreams

https://digitalcommons.library.umaine.edu/mmb-vp/2863/thumbnail.jp

If the Rose of my Dream, was You

https://digitalcommons.library.umaine.edu/mmb-vp/1819/thumbnail.jp

Tracking system study

A digital computer program was generated which mathematically describes an optimal estimator-controller technique as applied to the control of antenna tracking systems used by NASA. Simulation studies utilizing this program were conducted using the IBM 360/91 computer. The basic ideas of applying optimal estimator-controller techniques to antenna tracking systems are discussed. A survey of existing tracking methods is given along with shortcomings and inherent errors. It is explained how these errors can be considerably reduced if optimal estimation and control are used. The modified programs generated in this project are described and the simulation results are summarized. The new algorithms for direct synthesis and stabilization of the systems including nonlinearities, are presented

Total Value of Phosphorus Recovery

Phosphorus (P) is a critical, geographically concentrated, nonrenewable resource necessary to support global food production. In excess (e.g., due to runoff or wastewater discharges), P is also a primary cause of eutrophication. To reconcile the simultaneous shortage and overabundance of P, lost P flows must be recovered and reused, alongside improvements in P-use efficiency. While this motivation is increasingly being recognized, little P recovery is practiced today, as recovered P generally cannot compete with the relatively low cost of mined P. Therefore, P is often captured to prevent its release into the environment without beneficial recovery and reuse. However, additional incentives for P recovery emerge when accounting for the total value of P recovery. This article provides a comprehensive overview of the range of benefits of recovering P from waste streams, i.e., the total value of recovering P. This approach accounts for P products, as well as other assets that are associated with P and can be recovered in parallel, such as energy, nitrogen, metals and minerals, and water. Additionally, P recovery provides valuable services to society and the environment by protecting and improving environmental quality, enhancing efficiency of waste treatment facilities, and improving food security and social equity. The needs to make P recovery a reality are also discussed, including business models, bottlenecks, and policy and education strategies

Opposing effects of final population density and stress on Escherichia coli mutation rate

Evolution depends on mutations. For an individual genotype, the rate at which mutations arise is known to increase with various stressors (stress-induced mutagenesis-SIM) and decrease at high final population density (density-associated mutation-rate plasticity-DAMP). We hypothesised that these two forms of mutation-rate plasticity would have opposing effects across a nutrient gradient. Here we test this hypothesis, culturing Escherichia coli in increasingly rich media. We distinguish an increase in mutation rate with added nutrients through SIM (dependent on error-prone polymerases Pol IV and Pol V) and an opposing effect of DAMP (dependent on MutT, which removes oxidised G nucleotides). The combination of DAMP and SIM results in a mutation rate minimum at intermediate nutrient levels (which can support 7 × 10  cells ml ). These findings demonstrate a strikingly close and nuanced relationship of ecological factors-stress and population density-with mutation, the fuel of all evolution

Modeling the Distance-Dependent Blurring in Transmission Imaging in the Ordered-Subset Transmission (OSTR) Algorithm by Using an Unmatched Projector/Backprojector Pair

In SPECT, accurate emission reconstruction requires attenuation compensation with high-quality attenuation maps. Resolution loss in transmission maps could cause blurring and artifacts in emission reconstruction. For a transmission system employing parallel-hole collimators and a sheet source, distance-dependent blurring is caused by the non-ideal source and camera collimations, and the finite intrinsic resolution of the detector. These can be approximately modeled by an incremental-blurring model. To compensate for this blurring in iterative transmission reconstruction, we incorporated the incremental blurring model in the forward projector of the OSTR algorithm but did not include the blur in the backprojector. To evaluate our approach, we simulated transmission projections of the MCAT phantom using a ray-tracing projector, in which the rays coming out from a source point form a narrow cone. The geometric blurring due to the non-ideal source and camera collimations was simulated by multiplying the counts along each cone-beam ray with a weight calculated from the overall geometric response function (assumed a two-dimensional Gaussian function), and then summing the weighted counts into projections. The resulting projections were convolved with the intrinsic response (another two-dimensional Gaussian) to simulate the total system blurring of transmission imaging. Poisson noise was then added to the projection data. We also acquired two sets of transmission measurements of an air-filled Data Spectrum Deluxe SPECT phantom on a Prism 2000 scanning-line-source transmission system. We reconstructed the simulations using the OSTR algorithm, with and without modeling of the incremental blur in the projector. The scaling parameter of the penalty prior was optimized in each case by minimizing the root-mean-square error (RMSE). Reconstructions showed that modeling the incremental blur improved the resolution of the attenuation map and quantitative accuracy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85829/1/Fessler211.pd

Spontaneous mutation rate is a plastic trait associated with population density across domains of life

Rates of random, spontaneous mutation can vary plastically, dependent upon the environment. Such plasticity affects evolutionary trajectories and may be adaptive. We recently identified an inverse plastic association between mutation rate and population density at 1 locus in 1 species of bacterium. It is unknown how widespread this association is, whether it varies among organisms, and what molecular mechanisms of mutagenesis or repair are required for this mutation-rate plasticity. Here, we address all 3 questions. We identify a strong negative association between mutation rate and population density across 70 years of published literature, comprising hundreds of mutation rates estimated using phenotypic markers of mutation (fluctuation tests) from all domains of life and viruses. We test this relationship experimentally, determining that there is indeed density-associated mutation-rate plasticity (DAMP) at multiple loci in both eukaryotes and bacteria, with up to 23-fold lower mutation rates at higher population densities. We find that the degree of plasticity varies, even among closely related organisms. Nonetheless, in each domain tested, DAMP requires proteins scavenging the mutagenic oxidised nucleotide 8-oxo-dGTP. This implies that phenotypic markers give a more precise view of mutation rate than previously believed: having accounted for other known factors affecting mutation rate, controlling for population density can reduce variation in mutation-rate estimates by 93%. Widespread DAMP, which we manipulate genetically in disparate organisms, also provides a novel trait to use in the fight against the evolution of antimicrobial resistance. Such a prevalent environmental association and conserved mechanism suggest that mutation has varied plastically with population density since the early origins of life

Long-term safety of glycopyrrolate: A randomized study in patients with moderate-to-severe COPD (GEM3)

AbstractBackgroundChronic obstructive pulmonary disease (COPD) is one of the leading causes of death in the United States. Long-acting muscarinic antagonists (LAMAs) are a class of medications used as maintenance therapy for COPD. The GEM3 (Glycopyrrolate Effect on syMptoms and lung function) study assessed the long-term safety and efficacy of a LAMA, glycopyrrolate (GLY) 15.6 μg twice daily (b.i.d.), compared with an approved long-acting β2-agonist (LABA), indacaterol (IND) 75 μg once daily (q.d.) in patients with stable, symptomatic COPD with moderate-to-severe airflow limitation.MethodsThis 52-week, multicenter, double-blind, parallel-group study randomized patients (1:1) of the United States to receive GLY 15.6 μg b.i.d. or IND 75 μg q.d. both delivered via the Neohaler® device. The primary objective was to assess the safety and tolerability in terms of adverse event (AE) reporting rates over 52 weeks. Safety was also determined by evaluating multiple secondary endpoints, including vital signs, electrocardiograms (ECGs), and time to first moderate or severe exacerbation. Efficacy-related secondary endpoints included pre-dose forced expiratory volume in one second (FEV1) and forced vital capacity (FVC).ResultsOf the 511 randomized patients (GLY, n = 254; IND, n = 257), 81.6% completed the study. The overall incidences of AEs (GLY, 77.3%; IND, 77.0%) and serious AEs (GLY, 13.1%; IND, 13.3%) were comparable between the groups. The incidence of major adverse cardiovascular events was low and comparable between the groups. No clinically relevant differences for vital signs or ECG parameters were observed between the treatment groups. The three sudden deaths reported within 30 days of the treatment (GLY, n = 2; IND, n = 1) were adjudicated as unrelated to the study medication. In terms of efficacy, GLY 15.6 μg b.i.d. showed improvements in pre-dose FEV1 and FVC from baseline, which was comparable to those with IND 75 μg q.d., with no statistically significant differences. No significant differences were observed between the treatment groups in the time to first moderate or severe COPD exacerbation.ConclusionGLY 15.6 μg b.i.d. showed a long-term safety profile comparable to that of IND 75 μg q.d. and provided rapid and sustained bronchodilation over 52 weeks in patients with COPD with moderate-to-severe airflow limitation.Clinical trial registration numberNCT01697696

Serum Iron Level is Associated with Time to Antibiotics in Cystic Fibrosis

Background: Serum levels of hepcidin‐25, a peptide hormone that reduces blood iron content, are elevated when patients with cystic fibrosis (CF) develop pulmonary exacerbation (PEx). Because hepcidin‐25 is unavailable as a clinical laboratory test, we questioned whether a one‐time serum iron level was associated with the subsequent number of days until PEx, as defined by the need to receive systemic antibiotics (ABX) for health deterioration. Methods: Clinical, biochemical, and microbiological parameters were simultaneously checked in 54 adults with CF. Charts were reviewed to determine when they first experienced a PEx after these parameters were assessed. Time to ABX was compared in subgroups with and without specific attributes. Multivariate linear regression was used to identify parameters that significantly explained variation in time to ABX. Results: In univariate analyses, time to ABX was significantly shorter in subjects with Aspergillus‐positive sputum cultures and CF‐related diabetes. Multivariate linear regression models demonstrated that shorter time to ABX was associated with younger age, lower serum iron level, and Aspergillus sputum culture positivity. Conclusions: Serum iron, age, and Aspergillus sputum culture positivity are factors associated with shorter time to subsequent PEx in CF adults