Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane

Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned

Impact of tumor-specific targeting on the biodistribution and efficacy of siRNA nanoparticles measured by multimodality in vivo imaging

Targeted delivery represents a promising approach for the development of safer and more effective therapeutics for oncology applications. Although macromolecules accumulate nonspecifically in tumors through the enhanced permeability and retention (EPR) effect, previous studies using nanoparticles to deliver chemotherapeutics or siRNA demonstrated that attachment of cell-specific targeting ligands to the surface of nanoparticles leads to enhanced potency relative to nontargeted formulations. Here, we use positron emission tomography (PET) and bioluminescent imaging to quantify the in vivo biodistribution and function of nanoparticles formed with cyclodextrin-containing polycations and siRNA. Conjugation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid to the 5' end of the siRNA molecules allows labeling with 64Cu for PET imaging. Bioluminescent imaging of mice bearing luciferase-expressing Neuro2A s.c. tumors before and after PET imaging enables correlation of functional efficacy with biodistribution data. Although both nontargeted and transferrin-targeted siRNA nanoparticles exhibit similar biodistribution and tumor localization by PET, transferrin-targeted siRNA nanoparticles reduce tumor luciferase activity by {approx}50% relative to nontargeted siRNA nanoparticles 1 d after injection. Compartmental modeling is used to show that the primary advantage of targeted nanoparticles is associated with processes involved in cellular uptake in tumor cells rather than overall tumor localization. Optimization of internalization may therefore be key for the development of effective nanoparticle-based targeted therapeutics

Propagation of optical excitations by dipolar interactions in metal nanoparticle chains

Dispersion relations for dipolar modes propagating along a chain of metal nanoparticles are calculated by solving the full Maxwell equations, including radiation damping. The nanoparticles are treated as point dipoles, which means the results are valid only for a/d <= 1/3, where a is the particle radius and d the spacing. The discrete modes for a finite chain are first calculated, then these are mapped onto the dispersion relations appropriate for the infinite chain. Computed results are given for a chain of 50-nm diameter Ag spheres spaced by 75 nm. We find large deviations from previous quasistatic results: Transverse modes interact strongly with the light line. Longitudinal modes develop a bandwidth more than twice as large, resulting in a group velocity that is more than doubled. All modes for which k_mode <= w/c show strongly enhanced decay due to radiation damping.Comment: 26 pages, 7 figures, 2 tables. to appear in Phys. Rev.

Experimental Evidence for Quantum Interference and Vibrationally Induced Decoherence in Single-Molecule Junctions

We analyze quantum interference and decoherence effects in single-molecule junctions both experimentally and theoretically by means of the mechanically controlled break junction technique and density-functional theory. We consider the case where interference is provided by overlapping quasi-degenerate states. Decoherence mechanisms arising from the electronic-vibrational coupling strongly affect the electrical current flowing through a single-molecule contact and can be controlled by temperature variation. Our findings underline the all-important relevance of vibrations for understanding charge transport through molecular junctions.Comment: 5 pages, 4 figure

Growth and Performance of Nursery Pigs Fed Crude Glycerol

The growth and performance of 96 nursery pigs fed crude glycerol was evaluated in a 33 d trial. Pigs were weaned at 21 d of age and had an average start weight of 7.9±1.2 kg (17.4±2.6 lb). Pigs were provided ad libitum access to corn soybean diets containing three levels of crude glycerol, 0, 5, or 10%. Diets were formulated to be ioscaloric and isolysinic. There was no difference in pig performance based on dietary treatment. Crude glycerol can be fed to young pigs as an energy source without growth or performance effects

Challenges in Estimating the Causal Effect of an Intervention with Pre-Post Data (Part 1): Definition & Identification of the Causal Parameter

There is mixed evidence of the effectiveness of interventions operating on a large scale. Although the lack of consistent results is generally attributed to problems of implementation or governance of the program, the failure to find a statistically significant effect (or the success of finding one) may be due to choices made in the evaluation. To demonstrate the potential limitations and pitfalls of the usual analytic methods used for estimating causal effects, we apply the first half of a roadmap for causal inference to a pre-post evaluation of a community-level, national nutrition program. Selection into the program was non-random and strongly associated with the pre-treatment (lagged) outcome. Using structural causal models (SCM), directed acyclic graphs (DAGs) and simulated data, we demonstrate that a post treatment estimand controls for confounding by the lagged outcome but not from possible unmeasured confounders. Two separate difference-in-differences estimands have the potential to adjust for a certain type of unmeasured confounding, but introduce bias if the additional assumptions they require are not met. Our results reveal an important issue of identifiability when estimating the causal effect of a program with pre-post observational data. A careful appraisal of the assumptions underlying the causal model is imperative before committing to a statistical model and progressing to estimation

Growth Performance of Growing Pigs Fed Crude Glycerol-Supplemented Diets

Growth performance of growing pigs fed crude glycerol was determined in a 138-d feeding trial. Crude glycerol utilized in the trial contained 84.51% glycerol, 11.95% water, 2.91% sodium chloride, and 0.32% methanol. Eight days post-weaning, 96 pigs (48 barrows, 48 gilts) with an average BW of 7.9 ± 0.4 kg were allotted to 24 pens (4 pigs/pen), with gender and pen weight balanced at the start of the experiment. Dietary regimes were randomly assigned to each pen. Dietary treatments were 0, 5, and 10% crude glycerol inclusion in corn-soybean meal based diets. Diets were offered ad libitum in meal form and formulated to be equal in metabolizable energy (ME), sodium, chloride, and Lys, with other amino acids (AA) balanced on an ideal AA basis. Every two weeks, pigs and feeders were weighed and G:F calculated. Pig growth, feed intake, and G:F were not affected by dietary treatment. Crude glycerol is a viable source of dietary energy that is well utilized by pigs. Inclusion of crude glycerol in pig diets may be determined by relative availability and price of other dietary energy sources