A Seasoned Instructors New Look At Fixed-Income Securities: An Exercise Using Discounted Bonds

Having returned to teaching the basics of pricing fixed-income securities after several years, the author recalls the difficulty students have in understanding the total return provided by fixed-income securities that are purchased at either a discount or premium from face value.This teaching note attempts to clarify the concept by suggesting that separation of the return provided by coupon payments from the return provided by periodic changes in the fair market value may aid in student understanding.The integration of financial calculators in the classroom improves and simplifies this process for seasoned instructors

Buried Black Hole Growth in IR-selected Mergers: New Results from Chandra

Observations and theoretical simulations suggest that a significant fraction of merger-triggered accretion onto supermassive black holes is highly obscured, particularly in late-stage galaxy mergers, when the black hole is expected to grow most rapidly. Starting with the Wide-Field Infrared Survey Explorer all-sky survey, we identified a population of galaxies whose morphologies suggest ongoing interaction and which exhibit red mid-infrared colors often associated with powerful active galactic nuclei (AGNs). In a follow-up to our pilot study, we now present Chandra/ACIS and XMM-Newton X-ray observations for the full sample of the brightest 15 IR-preselected mergers. All mergers reveal at least one nuclear X-ray source, with 8 out of 15 systems exhibiting dual nuclear X-ray sources, highly suggestive of single and dual AGNs. Combining these X-ray results with optical line ratios and with near-IR coronal emission line diagnostics, obtained with the near-IR spectrographs on the Large Binocular Telescope, we confirm that 13 out of the 15 mergers host AGNs, two of which host dual AGNs. Several of these AGNs are not detected in the optical. All X-ray sources appear X-ray weak relative to their mid-infrared continuum, and of the nine X-ray sources with sufficient counts for spectral analysis, eight reveal strong evidence of high absorption with column densities of $N_\mathrm{H} \gtrsim 10^{23}$~cm$^{-2}$. These observations demonstrate that a significant population of single and dual AGNs are missed by optical studies, due to high absorption, adding to the growing body of evidence that the epoch of peak black hole growth in mergers occurs in a highly obscured phase.Comment: 29 pages, 22 figures; (Main text: 17 pages, 4 figures

Collisional Semiclassical Aproximations in Phase-Space Representation

The Gaussian Wave-Packet phase-space representation is used to show that the expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in the zeroth order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that propagating the Wigner distribution along the classical trajectories the amount of error is less than that coming from propagating the Gaussian distribution along classical trajectories.Comment: 20 pages, REVTEX, no figures, 3 tables include

A water-vapor electrolysis cell with phosphoric acid electrolyte

Feasibility of phosphoric acid water vapor electrolysis cell for spacecraft cabin air conditioning syste

Positional Differences in Running Distance and Speed Among Collegiate Rugby 7s Players

Rugby sevens (7s) is an anaerobic contact sport consisting of seven players per team, with two 7-minute halves per match played in tournament style with several matches over up to a three-day event. However, due to the nature of the collegiate game, less funding, and their academic schedule, the tournaments are commonly consolidated into one day (minimum 3, as many as 6 matches). While there are six positions in 7s, this study divided them into three groups: Forwards (FW), Backs (BK), and Scrum halves (SH). Purpose: The purpose of this investigation was to identify the physiological and physical demands between positions of Indiana University 7s club players. Methods: Data was retrospectively analyzed from male (n = 15) collegiate rugby 7s players. Data was collected at Indiana University using GameTraka (Sports Performance Tracking, Victoria, Australia) and data represented here are from one tournament consisting of 5 matches on the same day. Participants wore Global Positioning System (GPS) units from which information on distances run per minute by each position group (FW, BK, and SH) was measured within six different speed zones. A one-way ANOVA was used to determine between group differences by each half of play with Tukey post-hoc analyses to reveal differences between positions. A two-way repeated measures ANOVA was used to determine if differences existed across matches by player position. A p-value of \u3c0.05 was set to determine the level of statistical significance. Results: During the first half no significant differences were seen. In the second half of match #1, significant differences were found in Zone 1 running (p = 0.004) indicating that BK ran more than both FW (p = 0.003) and SH (p = 0.05). No significant differences were found in the second half of matches 2-4. Match #5 second half results indicated significant difference in distance per minute (p = 0.022) with both FW (p = 0.036) and SH (p = 0.041) covering more distance than BK. A main effect for zone 1 (p = 0.015) and zone 4 (p = 0.003) were observed with both FW (p = 0.029) and SH (p = 0.003) higher than BK. No significant differences were found across the five matches between position groups. GPS data indicate that the primary differences between position groups are observed in the second halves of rugby 7s matches. Data suggests that FW and SH have a higher distance covered per minute and spend more time in the different running zones as the number of matches increases. This could be a byproduct of a change in the quality of play as peripheral fatigue sets in as the match progresses. Conclusion: Data presented here can affect the training approaches for the various position groups as the data suggests a greater amount of physiological exertion is present in the later matches of tournament play. Data also may be useful to coaches in the strategic utilization of substituting players as substitutions per match are capped in rugby 7s

Differences in Impact and Load During Collegiate Rugby 7s

Rugby 7s is a sport played with seven players, and two, 7-minute halves, played on a standard rugby field of 100 meters long by 70 meters wide. Impacts with forces greater than 10.0 Gs are an often occurrence in rugby 7s, and the occurrence can be quite frequent in such a short period of time (14 minutes of match play). Multiple matches are played in a day or throughout a weekend in tournament format thus adding to the load on players and current research on the amount of impact and load players experience is lacking in a U.S. collegiate population. Purpose: The purpose of this investigation was to assess differences in impact and load during collegiate rugby 7s matches. Methods: Data was collected at Indiana University from male collegiate rugby 7s players (n = 15) by their head coach using GameTraka (Sports Performance Tracking, Victoria, Australia) during their 2019 season. Participants wore GPS units that collected data on impact and load by position groups forwards (FW), backs (BK), and scrum halves (SH). A one-way ANOVA was used to determine between group differences by each half of play with Tukey post-hoc analyses to reveal differences between positions. A two-way repeated measures ANOVA was used to determine if differences existed across matches by player position. A p-value of \u3c0.05 was set to determine the level of statistical significance. Results: Data analyses revealed a significant difference in number of impacts during the first half of match 1 (p = 0.014). Post-hoc analyses indicated FW incurred a significantly higher number of impacts than BK (p = 0.046), as well as more impacts than SH (p = 0.012). During the second half of play, the only match with a significant difference was match 5. Both summation of horizontal forces (loading 2D) as well as summation of horizontal and vertical forces (loading 3D) to the athlete revealed significant main effects. For the loading 2D and loading 3D during match 5, post-hoc analyses revealed significant differences between BK and SH at p = 0.048 and p = 0.045, respectively. In comparison of position across matches, no significant differences were found for impacts, 2D, or 3D loading. No significant differences were found across the five matches. Conclusion: This data suggests that the number of impacts is higher in the first half, with FW having significantly more impacts when compared to BK and SH. This is likely explained by task differences between FW, BK, and SH as FW are required to compete in scrums and more rucks than either BK or SH and tend to encounter contact more frequently. Differences in the second half occurred only in match 5 with SH being subjected to more forces than BK. This effect is likely a result of the positional differences as SH follow the course of play much more so than BK. This data supports that FW incur the greatest amount of collisions in rugby 7s compared to other positions also being a byproduct of the role that FW play in rugby 7s. There was no significant difference in loading and impact across matches

NuSTAR Observations of Four Mid-IR Selected Dual AGN Candidates in Galaxy Mergers

Mergers of galaxies are a ubiquitous phenomenon in the Universe and represent a natural consequence of the ``bottom-up'' mass accumulation and galaxy evolution cosmological paradigm. It is generally accepted that the peak of AGN accretion activity occurs at nuclear separations of $\lesssim10$ kpc for major mergers. Here we present new NuSTAR and XMM-Newton observations for a subsample of mid-IR preselected dual AGN candidates in an effort to better constrain the column densities along the line-of-sight for each system. Only one dual AGN candidate, J0841+0101, is detected as a single, unresolved source in the XMM-Newton and NuSTAR imaging, while the remaining three dual AGN candidates, J0122+0100, J1221+1137, and J1306+0735, are not detected with NuSTAR; if these non-detections are due to obscuration alone, these systems are consistent with being absorbed by column densities of log($N_{\rm{H}}/\rm{cm}^{-2}$) $\geq$ 24.9, 24.8, and 24.6, which are roughly consistent with previously inferred column densities in these merging systems. In the case of J0841+0101, the analysis of the 0.3-30 keV spectra reveal a line-of-sight column density of $N_{\rm{H}}\gtrsim10^{24}$ cm$^{-2}$, significantly larger than the column densities previously reported for this system and demonstrating the importance of the higher signal-to-noise XMM-Newton spectra and access to the $>10$ keV energies via NuSTAR. Though it is unclear if J0841+0101 truly hosts a dual AGN, these results are in agreement with the high obscuring columns expected in AGNs in late-stage mergers.Comment: 21 pages, 9 tables, 4 figures. Accepted for publication in Ap

Canine intrahepatic portosystemic shunt insertion into the systemic circulation is commonly through primary hepatic veins as assessed with CT angiography

Congenital intrahepatic portosystemic shunts (IHPSS) in dogs are traditionally classified as right, left, or central divisional. There are few descriptive studies regarding the variation of IHPSS within these categories. This multicenter, analytical, cross‐sectional study aimed to describe a large series of dogs with CT angiography (CTA) of IHPSS, hypothesizing that there would be variation to the existing classification. Ninety CTA studies were assessed for IHPSS type, insertion, and the relationship of the insertion to the primary hepatic veins. Ninety‐two percent of IHPSS inserted into a primary hepatic vein (HV) or phrenic vein, 8% inserted directly into the ventral aspect of the intrahepatic caudal vena cava. The most common IHPSS type was a single right divisional (44%), including those inserting via the right lateral HV or the caudate HV. Left divisional IHPSS (33%) inserted into the left HV or left phrenic vein. Central divisional IHPSS (13%) inserted into the quadrate HV, central HV, dorsal right medial HV, or directly into the ventral aspect of the intrahepatic caudal vena cava. Multiple sites of insertion were seen in 9% of dogs. Within left, central, and right divisional types, further subclassifications can therefore commonly be defined based on the hepatic veins with which the shunting vessel communicates. Relating IHPSS morphology to the receiving primary HV could make IHPSS categorization more consistent and may influence the type and method of IHPSS attenuation recommended