CONCAP 4: A Complex Autonomous Payload (CAP) for growing organic thin films in microgravity

A GAS facility has been developed for carrying out low temperature experiments. The arrangement being used on CONCAP IV-01 is designed for thin film growth in microgravity and can process up to twelve samples per mission. The nonlinear optical oven hardware can also be made suitable for other low temperature applications, such as gradient freeze and solution growth of crystals

The effect of infant feeding on childhood body composition

Childhood overweight and obesity has been increasing in the United States. According to the 2009-2010 National Health and Nutrition Examination Survey (NHANES), almost one third of children and adolescents in America are either overweight or obese. Overweight is defined as at or above the 85th percentile and less than the 95th percentile on the Center for Disease Control and prevention (CDC) BMI-for-age growth charts. Obesity is defined as at or above the 95th percentile on the CDC BMI-for-age growth charts. With increasing childhood weight there is an increased risk in health related issues. The use of infant formula has been thought to increase the risk of childhood obesity, but research is inconclusive to whether infant feeding practices are related to childhood body composition. Studies have found that breast feeding may have protective effect again childhood overweight and underweight, but there are other factors such as maternal weight status, ethnicity, and lifestyle habits that may confound these results. Other studies have shown differences in infant weight status for those who are fed formula versus breast milk, but these differences are not seen after one year of age. The purpose of this study is to determine if there is a relationship between infant feeding practices and childhood body composition and anthropometrics. Infant feeding practices for this study includes a) exclusively breast fed, b) bottle fed with expressed breast milk, c) exclusively formula fed and d) mixed feeding with formula and human milk. Most research does not include human milk fed by bottle or take into account mixed feeding practices. Some of the published reports use childhood anthropometrics as a surrogate marker of adiposity instead of measuring actual fat mass and fat free mass. This study includes childhood anthropometrics (BMI-for-age percentiles) and body composition (fat mass, fat free mass and percent body fat). We used multiple linear regression data analysis to assess the relationship between infant feeding practices and each of the body composition and anthropometric measurements (fat mass, fat free mass, percent body fat, and BMI-for-age percentile at three, four and five years old). We used a stepwise process to remove maternal confounding variables (maternal PPVT, race, smoking status, long chain polyunsaturated fatty acid supplementation during pregnancy and pre-pregnancy BMI) that had a change in significance of greater than 0.1 on the variability of the childhood body composition and anthropometric measurement. In the final model, we found no significant relationships between infant feeding practices at four months old and childhood body composition at five years of age and anthropometrics at three, four and five years old. This study has similarities with the recent research showing no difference between infant feeding practices on childhood body composition and anthropometrics. Although, there have been a few studies showing positive relationships between infant feeding practices and childhood weight status. These studies also determined that maternal characteristics confound or influence these findings, indicating there are other factors involved with childhood overweight and obesity. Childhood overweight and obesity may be influenced more by parental genetic factors or by childhood activity and dietary habits than infant feeding practices

Heavy Pentaquarks in the Diquark Model and the Large N_c Expansion

Recent experimental evidence for the Theta^+(1540) has given rise to much theoretical interest in exotic baryons. The Theta^+ is a baryon that has strangeness S=+1, meaning that it contains an anti-strange quark. Thus it cannot be constructed from three quarks, unlike all other known baryons; it needs at least an extra quark-antiquark pair. It is usually modeled as a pentaquark state in the 10 bar representation of flavor SU(3), with flavor content \bar{s}uudd. This thesis considers possible heavy pentaquarks, in which the antiquark is charmed or bottom rather than strange. In the context of the diquark model of Jaffe and Wilczek, it is argued that negative-parity pentaquarks of this type may be lighter than their positive-parity counterparts, and hence are likely to be stable against strong decay. Estimates are made for their masses, and their weak decays are discussed. Isospin relations are found between the decay rates for different possible decay channels. Negative-parity heavy pentaquarks are also considered in a less model-dependent way, in the context of a 1/N_c expansion, where N_c is the number of colors. Heavy quark effective theory is also employed. Mass relations are found between the mass splittings of heavy pentaquarks and those of nonexotic baryons, and SU(3)-breaking corrections to these relations are computed. The results could be helpful in interpreting experimental data if heavy pentaquarks are observed.Comment: PhD thesis; 84 pages, 22 figure

Failure to account for behavioral variability significantly compromises accuracy in indirect population monitoring (advance online)

Abstract Indirect wildlife population surveying largely depends upon counts of artifacts of behavior (e.g., nests or dung). Likelihood to encounter these artifacts is derived from both artifact production and decay, and variability in production behavior is considered to contribute minimally to inaccuracy in wildlife estimation. Here, we demonstrate how ignoring behavioral variability leads to significant population misestimation, using an example of an endangered ape, the bonobo (Pan paniscus). Until now, a single estimate of nest construction rate has been used to extrapolate bonobo densities, assumed to be broadly representative of bonobo sign production behavior. We estimated nest construction rates across seasons and social groups at the Kokolopori Bonobo Reserve, Democratic Republic of the Congo, and find nest construction rates in bonobos to be highly variable across populations as well as seasonal within populations. Failure to account for this variability led to degradation in the accuracy of bonobo population density estimates, accounting for a likely overestimation of bonobo numbers by 34%, and at worst as high as 80%. With this example, we demonstrate that failure to account for inter- and intrapopulation behavioral variation compromises the ability to estimate both relative and absolute wildlife abundances. We argue that variation in sign production is but one of the several potential ways that behavioral variability can affect conservation monitoring, should be measured across contexts whenever possible, and must be considered in population estimation confidence intervals. With increasing attention to behavioral variability as a potential tool for conservation, conservationists must also account for the impact that behavioral variability can have upon wildlife population estimation. Our results underline the importance of observational research to wildlife monitoring schemes as a critical component of conservation management. We discuss the avenues through which behavioral variability is likely to impact wildlife monitoring accuracy and precision and propose potential approaches for accounting for behavioral variability in wildlife monitoring

Quantifying effective slip length over micropatterned hydrophobic surfaces

We employ micro-particle image velocimetry ($\mu$-PIV) to investigate laminar micro-flows in hydrophobic microstructured channels, in particular the slip length. These microchannels consist of longitudinal micro-grooves, which can trap air and prompt a shear-free boundary condition and thus slippage enhancement. Our measurements reveal an increase of the slip length when the width of the micro-grooves is enlarged. The result of the slip length is smaller than the analytical prediction by Philip et al. [1] for an infinitely large and textured channel comprised of alternating shear-free and no-slip boundary conditions. The smaller slip length (as compared to the prediction) can be attributed to the confinement of the microchannel and the bending of the meniscus (liquid-gas interface). Our experimental studies suggest that the curvature of the meniscus plays an important role in microflows over hydrophobic micro-ridges.Comment: 8 page

The Long Range Gravitational Potential Energy Between Strings

We calculate the gravitational potential energy between infinitely long parallel strings with tensions \tau_1 and \tau_2. Classically, it vanishes, but at one loop, we find that the long range gravitational potential energy per unit length is U/L = 24G_N^2\tau_1\tau_2/(5 \pi a^2) + ..., where a is the separation between the strings, G_N is Newton's constant, and we set \hbar = c =1. The ellipses represent terms suppressed by more powers of G_N \tau_i. Typically, massless bulk fields give rise at one loop to a long range potential between p-branes in space-times of dimension p+2+1. The contribution to this potential from bulk scalars is computed for arbitrary p (strings correspond to p=1) and in the case of three-branes its possible relevance for cosmological quintessence is commented on.Comment: 10 pages, 6 figure

Spontaneous Breakdown of Superhydrophobicity

In some cases water droplets can completely wet micro-structured superhydrophobic surfaces. The {\it dynamics} of this rapid process is analyzed by ultra-high-speed imaging. Depending on the scales of the micro-structure, the wetting fronts propagate smoothly and circularly or -- more interestingly -- in a {\it stepwise} manner, leading to a growing {\it square-shaped} wetted area: entering a new row perpendicular to the direction of front propagation takes milliseconds, whereas once this has happened, the row itself fills in microseconds ({\it ``zipping''})Comment: Accepted for publication in Physical Review Letter

Dynamics of the spontaneous breakdown of superhydrophobicity

Drops deposited on rough and hydrophobic surfaces can stay suspended with gas pockets underneath the liquid, then showing very low hydrodynamic resistance. When this superhydrophobic state breaks down, the subsequent wetting process can show different dynamical properties. A suitable choice of the geometry can make the wetting front propagate in a stepwise manner leading to {\it square-shaped} wetted area: the front propagation is slow and the patterned surface fills by rows through a {\it zipping} mechanism. The multiple time scale scenario of this wetting process is experimentally characterized and compared to numerical simulations.Comment: 7 pages, 5 figure