Multi-wavelength visibility measurements of the red giant R Doradus

We present visibility measurements of the nearby Mira-like star R Doradus taken over a wide range of wavelengths (650--990 nm). The observations were made using MAPPIT (Masked APerture-Plane Interference Telescope), an interferometer operating at the 3.9-m Anglo-Australian Telescope. We used a slit to mask the telescope aperture and prism to disperse the interference pattern in wavelength. We observed in R Dor strong decreases in visibility within the TiO absorption bands. The results are in general agreement with theory but differ in detail, suggesting that further work is needed to refine the theoretical models.Comment: 8 pages; SPIE Conf. 4006 "Interferometry in Optical Astronomy

Diet Composition: A Proximate Mechanism Explaining Stream Salamander Declines in Surface Waters with Elevated Specific Conductivity

Changes in land use, such as mountaintop removal mining with valley fills (MTR-VF), often results in headwater streams with elevated specific conductivity (SC). Stream salamanders appear to be particularly sensitive to elevated SC, as previous studies have shown occupancy and abundance decline consistently among all species and life stages as SC increases. Yet, the proximate mechanism responsible for the population declines in streams with elevated SC have eluded researchers. We sampled salamander assemblages across a continuous SC gradient (30–1966 μS/cm) in southeastern Kentucky and examined the diet of larval and adult salamanders to determine if the ratio of aquatic to terrestrial prey (autochthony), total prey volume, aquatic prey importance (Ix), and body condition are influenced by SC. Further, we asked if threshold points for each diet component were present along a gradient of SC. Larval salamanders experienced a 12–fold decline in autochthony at 153 μS/cm, a 4.2–fold decline in total prey volume at 100 μS/cm, a 2.2-fold decline in aquatic Ix at 135 μS/cm, and a rapid decline in body condition as SC increased. Adult salamanders experienced a 3–fold decline in autochthony at 382 μS/cm, no change in prey volumes, a 2-fold decline in aquatic Ix at 163 μS/cm, and a decline in body condition as SC increased. Our results indicate that SC indirectly affects stream salamander populations by changing the composition of diet, which suggests that food availability is a proximate mechanism that leads to reduced population occupancy, abundance, and persistence in streams with elevated SC

A Low-Cost Microprocessor-Controlled Stance-Control Knee Orthosis for Pediatric Mobility Impairments

Knee-ankle-foot orthoses (KAFOs) are commonly prescribed for individuals with knee instability or quadriceps weakness resulting from a variety of conditions such as spinal cord injury, stroke, spina bifida, and cerebral palsy. A locking KAFO fixes the leg fully straight and is the most prescribed orthotic intervention for these conditions. However, the functional benefits of lower extremity orthoses are maximally realized in stance-controlled knee-ankle-foot orthoses (SC-KAFOs) which allow free knee motion during swing but lock during stance. Existing SC-KAFO options are generally unreliable or expensive, and thus an unmet need exists for a reliable, versatile orthosis which can be manufactured at relatively low cost. The SC-KO team is working to meet this need by developing an intelligent stance-controlled knee orthotic with an any-angle locking mechanism controlled by a microprocessor based on information received from onboard inertial gait-phase sensing. The resulting device will allow for reliable knee locking for support during the stance phase, easy unlocking even under load for the free swing phase, and predictable, safe behavior on stairs and uneven terrain. The system is being developed as a knee-only orthosis but can be adapted for a full knee-ankle-foot orthosis, with ankle support being prescribed as needed. The first system developed will be configured for pediatric use to address mobility impairments arising from cerebral palsy and spina bifida with CURE Ethiopia serving as the clinical partner for the development and testing. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1017/thumbnail.jp

Occupancy and Abundance of Stream Salamanders along a Specific Conductance Gradient

In the Central Appalachians (USA), mountaintop-removal mining accompanied by valley fills often leads to streams with elevated specific conductivity (SC). Thus, the ionic composition of freshwaters in this region is hypothesized to be a driver of the distribution and abundance of freshwater taxa, including stream salamanders. We examined the association between SC and stream salamander populations by conducting salamander counts in 30 southeastern Kentucky streams across a continuous gradient of SC that ranged from 30 to 1966 μS/cm. We counted 2319 salamanders across 5 species and, using a hierarchical Bayesian version of the N-mixture model, found a negative association between SC and salamander occupancy rates. This finding was consistent across adults and larvae of the 5 species we examined. Furthermore, we found that most salamander species and life stages showed reduced abundances given occupancy at greater SC levels. For example, estimated mean abundance given occupancy of larval Southern Two-lined Salamanders (Eurycea cirrigera) was 67.69 (95% credible interval 48.31–98.25) ind/10 m at 250 μS/cm and 2.30 (95% credible interval 1.46–3.93) ind/10 m at 2000 μS/cm. The consistent negative association across all species and life stages supports the hypothesis that salamander distributions and abundances are negatively associated with elevated SC of streams in southeastern Kentucky, even though physical and chemical environmental attributes, such as forest cover within stream catchments, were correlated with SC. Restoration of streams affected by mountaintop-removal mining should focus on restoring the ionic compositions that naturally occur in this region

A Low-Cost Egg Incubator to Provide Zambian Churches with Income and Food Security

Partnering with Brethren in Christ (BIC) Church in Zambia, the Egg Incubator Team is seeking to help provide a source of income for the growing churches in Choma, Zambia. They will accomplish this by designing and building a high-quality, low-cost egg incubator fabricated from local parts and cheap internationally available parts for The Nahumba Mission, in Choma, Zambia. The team’s design will provide the means for the Mission to hatch and sell chickens to provide both food security and a sustainable supplemental income. With the specifications to maintain temperature, humidity and constant ventilation, the team selected heating and humidity concepts for their incubator series. The team completed both mechanical and electrical designs for the setter and hatcher. In preparation for testing the incubator design with fertilized eggs, the team has also produced an incubation and hatching plan and achieved IACUC approval. Currently, the team is in the prototyping phase, while simultaneously monitoring the temperature and humidity in an existing incubator setter design. Once the team finishes their hatcher prototype and verifies that the temperature and humidity specifications are met, they will be ready to test designs using fertilized chicken eggs.https://mosaic.messiah.edu/engr2021/1020/thumbnail.jp

Early stages of ramified growth in quasi-two-dimensional electrochemical deposition

I have measured the early stages of the growth of branched metal aggregates formed by electrochemical deposition in very thin layers. The growth rate of spatial Fourier modes is described qualitatively by the results of a linear stability analysis [D.P. Barkey, R.H. Muller, and C.W. Tobias, J. Electrochem. Soc. {\bf 136}, 2207 (1989)]. The maximum growth rate is proportional to $(I/c)^\delta$ where $I$ is the current through the electrochemical cell, $c$ the electrolyte concentration, and $\delta = 1.37 \pm 0.08$. Differences between my results and the theoretical predictions suggest that electroconvection in the electrolyte has a large influence on the instability leading to ramified growth.Comment: REVTeX, four ps figure

An Investigation of the Ionic Conductivity and Species Crossover of Lithiated Nafion 117 in Nonaqueous Electrolytes

Nonaqueous redox flow batteries are a fast-growing area of research and development motivated by the need to develop low-cost energy storage systems. The identification of a highly conductive, yet selective membrane, is of paramount importance to enabling such a technology. Herein, we report the swelling behavior, ionic conductivity, and species crossover of lithiated Nafion 117 membranes immersed in three nonaqueous electrolytes (PC, PC : EC, and DMSO). Our results show that solvent volume fraction within the membrane has the greatest effect on both conductivity and crossover. An approximate linear relationship between diffusive crossover of neutral redox species (ferrocene) and the ionic conductivity of membrane was observed. As a secondary effect, the charge on redox species modifies crossover rates in accordance with Donnan exclusion. The selectivity of membrane is derived mathematically and compared to experimental results reported here. The relatively low selectivity for lithiated Nafion 117 in nonaqueous conditions suggests that new membranes are required for competitive nonaqueous redox flow batteries to be realized. Potential design rules are suggested for the future membrane engineering work.United States. Dept. of Energy. Office of Basic Energy Sciences. Joint Center for Energy Storage Researc

High-Energy gamma-ray Astronomy and String Theory

There have been observations, first from the MAGIC Telescope (July 2005) and quite recently (September 2008) from the FERMI Satellite Telescope, on non-simultaneous arrival of high-energy photons from distant celestial sources. In each case, the highest energy photons were delayed, as compared to their lower-energy counterparts. Although the astrophysics at the source of these energetic photons is still not understood, and such non simultaneous arrival might be due to non simultaneous emission as a result of conventional physics effects, nevertheless, rather surprisingly, the observed time delays can also fit excellently some scenarios in quantum gravity, predicting Lorentz violating space-time "foam" backgrounds with a non-trivial subluminal vacuum refractive index suppressed linearly by a quantum gravity scale of the order of the reduced Planck mass. In this pedagogical talk, I discuss the MAGIC and FERMI findings in this context and I argue on a theoretical model of space-time foam in string/brane theory that can accommodate the findings of those experiments in agreement with all other stringent tests of Lorentz invariance. However, I stress the current ambiguities/uncertainties on the source mechanisms, which need to be resolved first before definite conclusions are reached regarding quantum gravity foam scenarios.Comment: 34 pages latex, 12 eps figures incorporated, uses special macros. Based on invited plenary talk at DICE 2008 Conference (Castiglioncello, Italy), September 22-26 200