Orientation cues for high-flying nocturnal insect migrants: do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?

Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction

Development of a Slab-based Monte Carlo Proton Dose Algorithm with a Robust Material-dependent Nuclear Halo Model

Pencil beam algorithms (PBAs) are often utilized for dose calculation in proton therapy treatment planning because they are fast and accurate under most conditions. However, as discussed in Chapman et al (2017), the accuracy of a PBA can be limited under certain conditions because of two major assumptions: (1) the central-axis semi-infinite slab approximation; and, (2) the lack of material dependence in the nuclear halo model. To address these limitations, we transported individual protons using a class II condensed history Monte Carlo and added a novel energy loss method that scaled the nuclear halo equation in water to arbitrary geometry. Our results indicated significant reductions in primary dose difference distal to laterally finite slab heterogeneities (~15%) compared to our previous model. Furthermore, our improved nuclear halo model decreased the distance-to-agreement (DTA) of the 1% isodose lines near heterogeneities by ~2-7 mm, and resulted in significant in-field improvement for deep air slabs (~2% improvement in total dose at the peak). Evaluation of both of these improvements in more clinically relevant geometries revealed an improved DTA of the 1% isodose line (~0.3-3 mm) and a reduction of maximum dose near the peak (18-27% reduced to 6-15%). Overall, the two modeling improvements made in this work have resulted in a dose model with significantly higher dose calculation accuracy across a wide range of particularly challenging geometries

Proton dose calculations in homogeneous media

In this study, a proton pencil beam dose calculation algorithm was developed for a parallel, monoenergetic beam incident on a homogeneous water phantom. Fermi-Eyges theory (Eyges 1948) was used to transport pencil beams, and the characteristic width of elastic scatter events was modeled using the differential Moliere scattering power (Gottschalk 2010). The incorporation of this scattering power formalism allowed our model to account for multiple Coulomb scattering, single scattering, plural scattering, and rigorously accounted for material effects on scatter. Nonelastic nuclear interactions were incorporated into an additional pencil beam model. The attenuation of primary fluence due to nuclear events was accounted for using a weighted sum of primary and nuclear pencil beam components (Pedroni et al. 2005, Soukup et al. 2005). Free parameters of the nuclear pencil beam model were determined by a non-linear least squares fit to narrow field Monte Carlo data. Our dose calculation model was commissioned using central-axis depth dose data extracted from Monte Carlo simulations. Analytical corrections were incorporated to ensure that all input central-axis data satisfied side scatter equilibrium. The dose calculation model was evaluated against Monte Carlo simulations of dose in a simplified beamline. Proton beam energies of 50, 100, 150, 200, and 250 MeV and field sizes of 4x4 cm2 and 10x10 cm2 were evaluated in three geometries: (1) flat phantom; (2) step phantoms (step heights of 1 and 4 cm); and (3) oblique phantom (rotation angle of 45°). All geometries evaluated with Monte Carlo dose calculations yielded 100% of points passing distance-to-agreement (DTA) ≤ 1 mm or Percent Dose Difference ≤ 3%. At least 99% of points passed with a DTA ≤ 1 mm or Percent Dose Difference ≤ 2%. The pencil beam dose calculation model provided excellent results when compared with Monte Carlo data

The hermeneutics of Hermann Diem: a renewed conversation between existentialist exegesis and dogmatic theology

Thesis (Ph.D.)--Boston UniversityThe problems of contemporary biblical interpretation are largely rooted in the instability caused by an inadequate response by the Church to the challenge realised by historical criticism, and this uncertainty has now been compounded by the embittered divisions between two contemporary responses to the hermeneutical impasse, namely existentialist exegesis and dogmatic theology. This dissertation undertakes to examine the hermeneutic's reaction to this situation by an outstanding continental theologian, Hermann Diem. The scope of this dissertation is limited to the realm of German speaking Protestantism, and further to the debate aroused by the alternatives currently presented by Rudolf Bultmann and Karl Barth in hermeneutics, and to Diem's response to these alternatives. The method used is descriptive and comparative in nature. [TRUNCATED

Using Proxies for the Short Rate: When are Three Months Like an Instant?

The dynamics of the unobservable "short" or "instantaneous" rate of interest are frequently estimated using a proxy variable. We show the biases resulting from this practice (the "proxy" problem) are related to the derivatives of the proxy with respect to the short rate and the (inverse) function from the proxy to the short rate. Analytic results show that the proxy problem is not economically significant for single- factor affine models, for parameter values consistent with US data. In addition, for the two-factor affine model of Longstaff and Schwartz (1992), the proxy problem is only economically significant for pricing discount bonds with maturities of more than 5 years. We also describe two different procedures which can be used to assess the magnitude of the proxy problem in more general interest rate models. Numerical evaluation of a nonlinear single-factor model suggests that the proxy problem can significantly affect both estimates of the diffusion function and discount bond prices.interest rates, proxies, term structure

Searching for the truth

Thesis for graduate student Sherroy N. Chapman Jr. Includes titular essay and six scripts: Big Brother, Central High, Let Go, Superstore, Nerd Love, and MasterChef: Prison Edition

A Look at Illegal Immigration: Causes and Impact on the United States

This brief Article discusses illegal immigration into the United States and its effects on the country. The Author argues that the problem of illegal immigration has grown to the point where it is out of control, and our nation faces the dim prospect of even greater numbers of aliens pouring into the country unless steps are taken soon to halt the movement

Administrative Perspectives on Technology Integration: the Globaloria: MyGLife Program in West Virginia

The reputed benefits of using technology in schools have been the topic of many research studies. When the World Wide Workshop Foundation implemented their Globaloria program into a group of pilot public secondary schools in West Virginia in the fall of 2008, another opportunity for study was created. The perceptions of principals relating to: 1) the effect(s) of the Globaloria program on students‘ academic outcomes; 2) the purpose(s) of the program; 3) the principal‘s role in the program 4) the benefits; and/or 5) the liabilities of having the program in their schools were examined in this mixed-method study. Analysis of student data indicated that there was no statistically significant change in students‘ academic outcomes following the program‘s implementation, although data were available for only the year immediately prior to and the year immediately after their enrollment in Globaloria . Principals indicated that they believed the program had an overall positive effect upon students‘ academic outcomes, behavior and attendance. A majority of the participating principals also reported that they would like to continue the program in their schools. These findings were viewed through Lev Vygotsky‘s (1978) cultural-historical activity theory in order to generate conclusions and recommendations for further study