Rapid Design of Gravity Assist Trajectories

Several International Solar Terrestrial Physics (ISTP) missions require the design of complex gravity assisted trajectories in order to investigate the interaction of the solar wind with the Earth's magnetic field. These trajectories present a formidable trajectory design and optimization problem. The philosophy and methodology that enable an analyst to design and analyse such trajectories are discussed. The so called 'floating end point' targeting, which allows the inherently nonlinear multiple body problem to be solved with simple linear techniques, is described. The combination of floating end point targeting with analytic approximations with a Newton method targeter to achieve trajectory design goals quickly, even for the very sensitive double lunar swingby trajectories used by the ISTP missions, is demonstrated. A multiconic orbit integration scheme allows fast and accurate orbit propagation. A prototype software tool, Swingby, built for trajectory design and launch window analysis, is described

Humidification Factors from Laboratory Studies of Fresh Smoke from Biomass Fuels

Measurements of smoke aerosol humidification factors were performed in a laboratory for different biomass fuel types and burn conditions. Two nephelometers simultaneously measured dry and humidified light scattering coefficients (bsp(dry) and bsp(RH), respectively), providing the first observations of the temporal evolution of the humidification factor (f(RH) = bsp(RH)/bsp(dry)) for fresh (minutes-old) smoke. Hygroscopic characteristics of the smoke aerosols varied with fuel type and fire conditions, with the mean f(RH) ranging from 1.01 to 1.95 for fresh minutes-old smoke for the relative humidity (RH) range of 70-94%. These f(RH) values exhibited temporal variability, with some fuels alternating from hygroscopic to nonhygroscopic within minutes. Humidograms were also obtained, demonstrating that smoke from different fuels begins to take up water at different RH values. Humidification factors for hour-old smoke ranged from 1.10 to 1.51 for RH \u3e 90%. Finally, light-absorbing carbon mass measured with a multiwavelength aethalometer demonstrated different spectral responses as a function of fuel type. These laboratory experiments demonstrate the complexity of smoke hygroscopicity from young fires and are essential for understanding the radiative effects of biomass burning in the ambient atmosphere

Parkinson’s Disease Support Groups in Rural America: Barriers, Resources, and Opportunities

People with Parkinson’s disease who live in rural communities may lack information and support regarding their condition, compared to those in urban or suburban areas. For the study described herein, the researchers sought to gain a deeper understanding of support group experiences of rural Parkinson’s disease stakeholders through merging an interpretive phenomenological design with Community-based Participatory Research (CBPR). Using this merged approach, we collected qualitative data from five focus groups to gain a community perspective. The qualitative data was analyzed thematically, first, and then further explored for an overall essence. The theme, Support Group Benefits: Opportunities for Communication expounded upon the importance of support groups to Parkinson’s disease stakeholders. Barriers to Support Group Participation represented how the disease and the rural living conditions inhibited support group participation. Strategies to Improve Support Group Access demonstrated the different ways that the stakeholders had tried to overcome barriers and strengthen support groups. Notably, some participants discussed ways that support groups could increase their accessibility to more individuals with Parkinson’s living rurally so that they endured as a future resource. The themes and accessibility recommendations that emerged led the researchers to interpret the overall essence of this work as, experiencing support group benefits despite barriers, leaving a legacy

Water activity and activation diameters from hygroscopicity data - Part I: Theory and application to inorganic salts

International audienceA method is described that uses particle hygroscopicity measurements, made with a humidified tandem differential mobility analyzer (HTDMA), to determine solution water activity as a function of composition. The use of derived water activity data in computations determining the ability of aerosols to serve as cloud condensation nuclei (CCN) is explored. Results for sodium chloride and ammonium sulfate are shown in Part I. The methodology yields solution water activities and critical dry diameters for ammonium sulfate and sodium chloride in good agreement with previously published data. The approach avoids the assumptions required for application of simplified and modified Köhler equations to predict CCN activity, most importantly, knowledge of the molecular weight and the degree of dissociation of the soluble species. Predictions of the dependence of water activity on the mass fraction of aerosol species are sensitive to the assumed dry density, but predicted critical dry diameters are not

Building Community Capacity for Integrating Engineering in Rural Middle School Science Classrooms

: Broadening participation in engineering is an important national priority and has led to increasing demands for engineering content to be integrated into traditional K-12 curriculum. However, expecting teachers to incorporate engineering into their classrooms without additional training or resources is unreasonable. Partnering teachers with industry partners is one promising way to prioritize integrated science and engineering content while also introducing youth to possible career paths. In this programmatic article, we introduce the Partnering with Educators and Engineers in Rural Schools (PEERS) project that focuses on the collaborative design, implementation, and study of recurrent hands-on engineering activities with middle school youth in three rural communities in or near Appalachia. We discuss the curricular priorities of the program as well as preliminary findings on both student-focused and capacity-building metrics across the partnerships. Key discussion points include (1) a need to distill goals for engineering outreach by wrestling with what success might really look like for middle-school youth engagement with engineering and (2) cultivating community capacity to better support education systems and the simultaneous potential for and challenges of collaborating to build such infrastructure

Water activity and activation diameters from hygroscopicity data - Part II: Application to organic species

International audienceA method has been developed for using particle hygroscopicity measurements made with a humidified tandem differential mobility analyzer (HTDMA) to determine water activity as a function of solute weight percent. In Part I, the method was tested for particles composed of sodium chloride and ammonium sulfate. Here, we report results for several atmospherically-relevant organic species: glutaric acid, malonic acid, oxalic acid and levoglucosan. Predicted water activities for aqueous dicarboxylic acid solutions are quite similar in some cases to published estimates and the simplified predictions of Köhler theory, while in other cases substantial differences are found, which we attribute primarily to the semivolatile nature of these compounds that makes them difficult to study with the HTDMA. In contrast, estimates of water activity for levoglucosan solutions compare very well with recently-reported measurements and with published data for aqueous glucose and fructose solutions. For all studied species, the critical dry diameters active at supersaturations between 0.2 and 1% that are computed with the HTDMA-derived water activities are generally within the experimental error (~20%) estimated in previously-published direct measurements using cloud condensation nuclei counters. For individual compounds, the variations in reported solution water activity lead to uncertainties in critical dry diameters of 5-25%, not significantly larger than the uncertainty in the direct measurements. To explore the impact of these uncertainties on modeled aerosol-cloud interactions, we incorporate the variations in estimates of solution water activities into the description of hygroscopic growth of aerosol particles in an adiabatic parcel model and examine the impact on the predicted drop number concentrations. For the limited set of initial conditions examined here, we find that the uncertainties in critical dry diameters for individual species lead to 0-21% changes in drop number concentration, with the largest effects at high aerosol number concentrations and slow updraft velocities. Ammonium sulfate, malonic acid and glutaric acid have similar activation behavior, while glutaric acid and levoglucosan are somewhat less hygroscopic and lead to lower drop number concentrations; sodium chloride is the most easily activated compound. We explain these behaviors in terms of a parameter that represents compound hygroscopicity, and conclude that this parameter must vary by more than a factor of 2 to induce more than a 15% change in activated drop number concentrations. In agreement with earlier studies, our results suggest that the number concentration of activated drops is more sensitive to changes in the input aerosol size and number concentrations and the applied updraft velocity than to modest changes in the aerosol composition and hygroscopic properties

Measured and modeled humidification factors of fresh smoke particles from biomass burning: role of inorganic constituents

During the 2006 FLAME study (<b>F</b>ire <b>L</b>aboratory <b>a</b>t <b>M</b>issoula <b>E</b>xperiment), laboratory burns of biomass fuels were performed to investigate the physico-chemical, optical, and hygroscopic properties of fresh biomass smoke. As part of the experiment, two nephelometers simultaneously measured dry and humidified light scattering coefficients (<i>b</i><sub>sp(dry) </sub> and <i>b</i><sub>sp(RH)</sub>, respectively) in order to explore the role of relative humidity (RH) on the optical properties of biomass smoke aerosols. Results from burns of several biomass fuels from the west and southeast United States showed large variability in the humidification factor (<i>f</i>(RH)=<i>b</i><sub>sp(RH)</sub>/<i>b</i><sub>sp(dry)</sub>). Values of <i>f</i>(RH) at RH=80–85% ranged from 0.99 to 1.81 depending on fuel type. We incorporated measured chemical composition and size distribution data to model the smoke hygroscopic growth to investigate the role of inorganic compounds on water uptake for these aerosols. By assuming only inorganic constituents were hygroscopic, we were able to model the water uptake within experimental uncertainty, suggesting that inorganic species were responsible for most of the hygroscopic growth. In addition, humidification factors at 80–85% RH increased for smoke with increasing inorganic salt to carbon ratios. Particle morphology as observed from scanning electron microscopy revealed that samples of hygroscopic particles contained soot chains either internally or externally mixed with inorganic potassium salts, while samples of weak to non-hygroscopic particles were dominated by soot and organic constituents. This study provides further understanding of the compounds responsible for water uptake by young biomass smoke, and is important for accurately assessing the role of smoke in climate change studies and visibility regulatory efforts

Lithographic Patterning of Photoreactive Cell-Adhesive Proteins

We describe a novel, simple method for the photolithographic patterning of cell-adhesive proteins. Intrinsically photoreactive proteins are synthesized in Escherichia coli through incorporation of the non-canonical, photosensitive amino acid para-azidophenylalanine. Upon ultraviolet irradiation at 365 nm, proteins form cross-linked films with elastic moduli that can be tuned by varying the concentration of photoreactive amino acid in the expression medium. Films of these proteins can be directly patterned using standard photolithographic techniques. We demonstrate the utility of this method of protein patterning by creating stable arrays of fibroblast cells on an engineered protein “photoresist”

Colorado State University (CSU) accelerator and FEL facility

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band (1.3 GHz) electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test laboratory, and a magnetic test laboratory. The photocathode-driven linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Here, a summary of the systems used at the CSU Accelerator Facility is discussed. The building construction is completed and equipment move-in has begun. The first beam is expected to occur by mid 2015