Free Space Optical Link Utilizing a Modulated Retro-Reflector Intended for Planetary Duplex Communication Links Between an Orbiter and Surface Unit

Presented are simulation and experimental results that provide duplex optical-free space communication links with minimal power and pointing requirements by using a modulated retro-reflector (MRR) for planetary communications. The design is the MRR resides on the surface of a planet or moon, where energy is scarce, while the source of the communication laser resides on an orbiter to achieve satellite-to-ground communications. Also, a simulated scenario using the Mars Reconnaissance Orbiter (MRO) is provided for real world potential results. The information sent through this communication path can range from raw scientific data to multimedia files such as videos and pictures. Bidirectional communications is established with the MRR by using a nested pulse position modulation (PPM) structure. This modulation scheme is then evaluated for its validity in a proof-of-concept experiment. Initial results indicate a promising return-link performance of at least 300 kbps in the nested arrangement

Exponential asymptotics using numerical rational approximation in linear differential equations

Singularly perturbed ordinary differential equations often exhibit Stokes’ phenomenon, which describes the appearance and disappearance of oscillating exponentially small terms across curves in the complex plane known as Stokes lines. These curves originate at singular points in the leading-order solution to the differential equation. In many important problems, it is impossible to obtain a closed-form expression for these leading-order solutions, and it is therefore challenging to locate these singular points. We present evidence that the analytic leading-order solution of a linear differential equation can be replaced with a numerical rational approximation using the adaptive Antoulas–Anderson (AAA) method. Despite such an approximation having completely different singularity types and locations, we show that the subsequent exponential asymptotic analysis accurately predicts the exponentially small behaviour present in the solution. For sufficiently small values of the asymptotic parameter, this approach breaks down; however, the range of validity may be extended by increasing the number of poles in the rational approximation. We present a related nonlinear problem and discuss the challenges that arise due to nonlinear effects. Overall, our approach allows for the study of exponentially small asymptotic effects without requiring an exact analytic form for the leading-order solution; this permits exponential asymptotic methods to be used in a much wider range of applications

Increasing Accessibility to Birth Control: Over the Counter Oral Birth Control

The increasing barriers to the accessibility of birth control have prompted a need for a solution. One long standing solution suggested to diminish the barriers is by removing the prescription requirement of oral contraceptives. Removing the prescription requirement not only breaks down barriers for women without healthcare access but also allows women an opportunity to control their reproduction with more accessibility. Although this solution appears to be concise, the reality is there are many different views regarding offering birth control over the counter, including some healthcare professionals who believe the health risks outweigh the access benefit. On the contrary, those in support of removing the prescription barrier for oral contraceptives, including the American Medical Association, argue that the risks women undergo through pregnancy outweigh the risks of consuming oral contraceptives. Throughout this review article, research investigating both the advantages and disadvantages of the suggested solution is discussed assessing the potential outcomes of having oral contraceptives offered over the counter

Cardiovascular Effects of Long Term Androgenic Anabolic Steroid Use

Background: Anabolic steroids have been a consistent area of debate when it comes to athletes. Anabolic steroids are very common in certain sports like powerlifting and bodybuilding. Negative health effects have been found to be associated with the long term use of anabolic steroids. The objective of this review is to determine if there are negative cardiovascular effects associated with chronic androgenic anabolic steroid use when compared to non-steroid users. Methods: A literature review of past research articles was performed. Pertinent information was obtained from the sources and compiled as evidence for the topic of this paper. Results: Using primarily bodybuilder populations, the findings obtained from the articles supported decreased left ventricular function, increase in blood pressure, atherosclerosis of blood vessels, and an increase in LDL with a decrease in HDL. Conclusion: Anabolic steroids can be contributed to decreased left ventricular function, increased blood pressure, atherosclerosis, and increase LDL and decrease HDL leading to an overall decrease in cardiovascular function. Improving education on the cardiovascular impact anabolic steroids can have can ultimately decrease the risk of individuals abusing these drugs and having a decrease in overall health

Precision Pointing of IBEX-Lo Observations

Post-launch boresight of the IBEX-Lo instrument onboard the Interstellar Boundary Explorer (IBEX) is determined based on IBEX-Lo Star Sensor observations. Accurate information on the boresight of the neutral gas camera is essential for precise determination of interstellar gas flow parameters. Utilizing spin-phase information from the spacecraft attitude control system (ACS), positions of stars observed by the Star Sensor during two years of IBEX measurements were analyzed and compared with positions obtained from a star catalog. No statistically significant differences were observed beyond those expected from the pre-launch uncertainty in the Star Sensor mounting. Based on the star observations and their positions in the spacecraft reference system, pointing of the IBEX satellite spin axis was determined and compared with the pointing obtained from the ACS. Again, no statistically significant deviations were observed. We conclude that no systematic correction for boresight geometry is needed in the analysis of IBEX-Lo observations to determine neutral interstellar gas flow properties. A stack-up of uncertainties in attitude knowledge shows that the instantaneous IBEX-Lo pointing is determined to within \sim 0.1\degr in both spin angle and elevation using either the Star Sensor or the ACS. Further, the Star Sensor can be used to independently determine the spacecraft spin axis. Thus, Star Sensor data can be used reliably to correct the spin phase when the Star Tracker (used by the ACS) is disabled by bright objects in its field-of-view. The Star Sensor can also determine the spin axis during most orbits and thus provides redundancy for the Star Tracker.Comment: 22 pages, 18 figure

Διερεύνηση Πλημυρικής Κατάκλυσης σε συνθήκες μη μόνιμης ροής με τη χρήση Λογισμικών Υδραυλικής Προσομοίωση. Εφαρμογή στον Πηνειό Θεσσαλίας.

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Επιστήμη και Τεχνολογία Υδατικών Πόρων

Factorisation of 3d N = 4 twisted indices and the geometry of vortex moduli space

We study the twisted indices of $\mathcal{N}=4$ supersymmetric gauge theories in three dimensions on spatial $S^{2}$ with an angular momentum refinement. We demonstrate factorisation of the index into holomorphic blocks for the $T[SU(N)]$ theory in the presence of generic fluxes and fugacities. We also investigate the relation between the twisted index, Hilbert series and the moduli space of vortices. In particular, we show that each holomorphic block coincides with a generating function for the $\chi_{t}$ genera of the moduli spaces of "local" vortices. The twisted index itself coincides with a corresponding generating function for the $\chi_{t}$ genera of moduli spaces of "global" vortices in agreement with a proposal of Bullimore et. al. We generalise this geometric interpretation of the twisted index to include fluxes and Chern-Simons levels. For the $T[SU(N)]$ theory, the relevant moduli spaces are the local and global versions of Laumon space respectively and we demonstrate the proposed agreements explicitly using results from the mathematical literature. Finally, we exhibit a precise relation between the Coulomb branch Hilbert series and the Poincar\'e polynomials of the corresponding vortex moduli spaces

Blocks and vortices in the 3d ADHM quiver gauge theory

We study the hemisphere partition function of a three-dimensional $\mathcal{N}=4$ supersymmetric $U(N)$ gauge theory with one adjoint and one fundamental hypermultiplet -- the ADHM quiver theory. In particular, we propose a distinguished set of UV boundary conditions which yield Verma modules of the quantised chiral rings of the Higgs and Coulomb branches. In line with a recent proposal by two of the authors in collaboration with M. Bullimore, we show explicitly that the hemisphere partition functions recover the characters of these modules in two limits, and realise blocks gluing exactly to the partition functions of the theory on closed three-manifolds. We study the geometry of the vortex moduli space and investigate the interpretation of the vortex partition functions as equivariant indices of quasimaps to the Hilbert scheme of points in $\mathbb{C}^2$. We also investigate half indices of the ADHM quiver gauge theory in the presence of a line operator and discuss their geometric interpretation. Along the way we find interesting relations between our hemisphere blocks and related quantities in topological string theory and equivariant quantum K-theory

Detection of two poleroviruses infecting garlic (Allium sativum) in Australia

Two near complete polerovirus genomes were assembled using high throughput sequencing (HTS) data from two separate samples of garlic cultivar ‘Glenlarge’ grown in Gatton, Queensland, Australia. Whole genome sequence comparisons showed that one contig shared 96.7% nucleotide identity with phasey bean mild yellows virus (MT966032.1) and the other, 99.8% nucleotide identity with turnip yellows virus (MT586581.1). Phylogenetic analyses further revealed that the isolates fell within the PBMYV group 2 and TuYV group 2 clades, respectively. This is the first report of these poleroviruses infecting garlic