Exploring the relationship between a fluid container\u27s geometry and when it will balance on edge

At some point while consuming a beverage, many people will idly try to balance its container on edge. The act itself is physically straightforward, merely involving the system\u27s center of mass and achieving a static equilibrium between the opposing torques caused by gravity and the normal force between the container and the surface on which it balances. Further analysis of the act, however, illuminates the richness of the exercise. These nuances are apparent even in simplified two-dimensional models because of the depth of the relationship between a container\u27s geometry and achieving balance. The purpose of such analysis is threefold: first, when considering a rectangular container, to determine the relationship between the angle at which it balances and the amount of fluid in the container; second, to consider a massless analogue to a standard twelve-ounce aluminum can which balances at a fixed angle and observe the interplay between the various parameters of that container\u27s geometry and balance; and finally, to revisit the aluminum can model, this time considering its mass relative to the fluid\u27s, and recover the familiar behavior observed when balancing real-world beverages in aluminum cans

Prolonged length of stay in illeal conduit compared to neobladder diversion in radical cystectomy patients for bladder cancer

Background: Radical cystectomy and urinary diversion has become the standard treatment for invasive and complicated malignancies of the bladder, urethra, and ureters. [1] Robotic-assisted radical cystectomy (RARC), introduced in the last decade, has been associated with favorable perioperative outcomes when compared to open radical cystectomy. Yet little is known about how different urinary diversion types compare in regards to length of hospital stay, readmission rates, and perioperative course. This data analysis seeks to identify the statistically significant differences in postoperative course of ileal conduit versus neobladder among patients with staged bladder cancer. Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) is a health insurance portability and accountability act (HIPAA) compliant data file containing cases from 706 participating hospitals. The data includes 275 HIPAA compliant variables on 902,968 cases in 2020 and 273 variables on 1,076,441 cases in 2019. ACS NSQIP includes all major cases as determined by Current Procedural Terminology (CPT) code. The goal of the program is to determine the quality of care after surgical procedures. The ACS NSQIP is deidentified and the study was exempted from the requirement for institutional review board approval. The primary outcomes were length of stay and readmission after radical cystectomy with either ileal conduit or neobladder. Wilcoxon signed-rank test was utilized for continuous variables as the data was not normally distributed. For categorical variables, Fisher’s exact test was performed and Chi-squared analysis where more than two categories were evaluated. Statistical significance was set at P-value \u3c 0.05. Results: Data from a total of 6,103 patients in the NSQIP database were screened and 1,478 analyzed for all outcomes measures. There was no statistical significance in terms of mean length of stay between the ileal conduit and neobladder groups (7.85 vs. 7.44 days, p = 0.185) (Table 1). Additionally, there was not a statistically significant difference in mean days to discharge. Secondary endpoints that resulted in statistically significant differences include rates of readmission (21.5% vs 30%, p \u3c 0.05), colonic anastomotic leak (6.3% vs 1.8%, p \u3c 0.05), urinary anastomotic leak (3.1% vs 6.7%, p \u3c 0.05) , and lymphocele/lymphatic leak (3.8% vs 8.5%, p \u3c 0.05)( Table 1.) Multivariable analysis revealed additional differences between these groups. Prior pelvic radiotherapy ( p = 0.003) and a characterized bleeding disorder (p = 0.001) were associated with length of stay in the ileal conduit group (Table 2). Chemotherapy within 90 days (p = 0.004) and diabetes mellitus (p = 0.029) were predictors of length of stay in the neobladder group (Table 2). Conclusion: The conduit diversion cohort did not show a difference in length of stay compared to the neobladder cohort. However, secondary endpoints including rates of readmission, colonic anastomotic leak, urinary anastomotic leak, and lymphocele/lymphatic leak showed significant differences. Risk factors that influenced length of stay were prior pelvic radiation, a characterized bleeding disorder, chemotherapy within 90 days, and diabetes mellitus

Making sense of cancer news coverage trends: a comparison of three comprehensive content analyses

Cancer stories (N = 5,327) in the top 50 U.S. newspapers were analyzed by a team of four coders and the results were compared with the earliest analyses of this type (from 1977 and 1980). Using cancer incidence rates as a comparison, three cancers were found to be consistently underreported (male Hodgkin’s, and thyroid) and four cancers were found to be consistently overreported (breast, blood/Leukemia, pancreatic, and bone/muscle). In addition, cancer news coverage consistently has focused on treatment rather than on other aspects of the cancer continuum (e.g., prevention), portrayed lifestyle choices (e.g., diet, smoking) as the most common cancer risk factor, and rarely reported incidence or mortality data. Finally, the data were compatible with the idea that personalization bias (e.g., celebrity profiles, event coverage) may explain some news coverage distortions

Initial results from a field campaign of wake steering applied at a commercial wind farm – Part 1

Wake steering is a form of wind farm control in which turbines use yaw offsets to affect wakes in order to yield an increase in total energy production. In this first phase of a study of wake steering at a commercial wind farm, two turbines implement a schedule of offsets. Results exploring the observed performance of wake steering are presented and some first lessons learned. For two closely spaced turbines, an approximate 14&thinsp;% increase in energy was measured on the downstream turbine over a 10∘ sector, with a 4&thinsp;% increase in energy production of the combined upstream–downstream turbine pair. Finally, the influence of atmospheric stability over the results is explored.</p

Search for Ultraheavy Dark Matter from Observations of Dwarf Spheroidal Galaxies with VERITAS

Dark matter is a key piece of the current cosmological scenario, with weakly interacting massive particles (WIMPs) a leading dark matter candidate. WIMPs have not been detected in their conventional parameter space (100 GeV $\lesssim M_{\chi} \lesssim$ 100 TeV), a mass range accessible with current Imaging Atmospheric Cherenkov Telescopes. As ultraheavy dark matter (UHDM; $M_{\chi} \gtrsim$ 100 TeV) has been suggested as an under-explored alternative to the WIMP paradigm, we search for an indirect dark matter annihilation signal in a higher mass range (up to 30 PeV) with the VERITAS gamma-ray observatory. With 216 hours of observations of four dwarf spheroidal galaxies, we perform an unbinned likelihood analysis. We find no evidence of a $\gamma$-ray signal from UHDM annihilation above the background fluctuation for any individual dwarf galaxy nor for a joint-fit analysis, and consequently constrain the velocity-weighted annihilation cross section of UHDM for dark matter particle masses between 1 TeV and 30 PeV. We additionally set constraints on the allowed radius of a composite UHDM particle.Comment: 10 pages, 7 figure

Demonstration of stellar intensity interferometry with the four VERITAS telescopes

High angular resolution observations at optical wavelengths provide valuable insights in stellar astrophysics, directly measuring fundamental stellar parameters, and probing stellar atmospheres, circumstellar disks, elongation of rapidly rotating stars, and pulsations of Cepheid variable stars. The angular size of most stars are of order one milli-arcsecond or less, and to spatially resolve stellar disks and features at this scale requires an optical interferometer using an array of telescopes with baselines on the order of hundreds of meters. We report on the successful implementation of a stellar intensity interferometry system developed for the four VERITAS imaging atmospheric-Cherenkov telescopes. The system was used to measure the angular diameter of the two sub-mas stars $\beta$ Canis Majoris and $\epsilon$ Orionis with a precision better than 5%. The system utilizes an off-line approach where starlight intensity fluctuations recorded at each telescope are correlated post-observation. The technique can be readily scaled onto tens to hundreds of telescopes, providing a capability that has proven technically challenging to current generation optical amplitude interferometry observatories. This work demonstrates the feasibility of performing astrophysical measurements with imaging atmospheric-Cherenkov telescope arrays as intensity interferometers and the promise for integrating an intensity interferometry system within future observatories such as the Cherenkov Telescope Array.Comment: Accepted for publication in Nature Astronomy (2020

VERITAS and Fermi-LAT constraints on the Gamma-ray Emission from Superluminous Supernovae SN2015bn and SN2017egm

Superluminous supernovae (SLSNe) are a rare class of stellar explosions with luminosities ~10-100 times greater than ordinary core-collapse supernovae. One popular model to explain the enhanced optical output of hydrogen-poor (Type I) SLSNe invokes energy injection from a rapidly spinning magnetar. A prediction in this case is that high-energy gamma rays, generated in the wind nebula of the magnetar, could escape through the expanding supernova ejecta at late times (months or more after optical peak). This paper presents a search for gamma-ray emission in the broad energy band from 100 MeV to 30 TeV from two Type I SLSNe, SN2015bn, and SN2017egm, using observations from Fermi-LAT and VERITAS. Although no gamma-ray emission was detected from either source, the derived upper limits approach the putative magnetar's spin-down luminosity. Prospects are explored for detecting very-high-energy (VHE; 100 GeV - 100 TeV) emission from SLSNe-I with existing and planned facilities such as VERITAS and CTA.Comment: 20 pages, 7 figures, 2 table

An Archival Search for Neutron-Star Mergers in Gravitational Waves and Very-High-Energy Gamma Rays

The recent discovery of electromagnetic signals in coincidence with neutron-star mergers has solidified the importance of multimessenger campaigns in studying the most energetic astrophysical events. Pioneering multimessenger observatories, such as LIGO/Virgo and IceCube, record many candidate signals below the detection significance threshold. These sub-threshold event candidates are promising targets for multimessenger studies, as the information provided by them may, when combined with contemporaneous gamma-ray observations, lead to significant detections. Here we describe a new method that uses such candidates to search for transient events using archival very-high-energy gamma-ray data from imaging atmospheric Cherenkov telescopes (IACTs). We demonstrate the application of this method to sub-threshold binary neutron star (BNS) merger candidates identified in Advanced LIGO's first observing run. We identify eight hours of archival VERITAS observations coincident with seven BNS merger candidates and search them for TeV emission. No gamma-ray emission is detected; we calculate upper limits on the integral flux and compare them to a short gamma-ray burst model. We anticipate this search method to serve as a starting point for IACT searches with future LIGO/Virgo data releases as well as in other sub-threshold studies for multimessenger transients, such as IceCube neutrinos. Furthermore, it can be deployed immediately with other current-generation IACTs, and has the potential for real-time use that places minimal burden on experimental operations. Lastly, this method may serve as a pilot for studies with the Cherenkov Telescope Array, which has the potential to observe even larger fields of view in its divergent pointing mode

VERITAS Observations of the Galactic Center Region at Multi-TeV Gamma-Ray Energies

The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit a large flux of non-thermal radiation. The inner 375 pc x 600 pc region, called the Central Molecular Zone, is home to the supermassive black hole Sagittarius A*, massive cloud complexes, and particle accelerators such as supernova remnants. We present the results of our improved analysis of the very-high-energy (VHE) gamma-ray emission above 2 TeV from the GC using 125 hours of data taken with the VERITAS imaging-atmospheric Cherenkov telescope between 2010 and 2018. The central source VER J1745-290, consistent with the position of Sagittarius A*, is detected at a significance of 38 standard deviations above the background level $(38\sigma)$, and we report its spectrum and light curve. Its differential spectrum is consistent with a power law with exponential cutoff, with a spectral index of $2.12^{+0.22}_{-0.17}$, a flux normalization at 5.3 TeV of $1.27^{+0.22}_{-0.23}\times 10^{-13}$ TeV-1 cm-2 s-1, and cutoff energy of $10.0^{+4.0}_{-2.0}$ TeV. We also present results on the diffuse emission near the GC, obtained by combining data from multiple regions along the GC ridge which yield a cumulative significance of $9.5\sigma$. The diffuse GC ridge spectrum is best fit by a power law with a hard index of 2.19 $\pm$ 0.20, showing no evidence of a cutoff up to 40 TeV. This strengthens the evidence for a potential accelerator of PeV cosmic rays being present in the GC. We also provide spectra of the other sources in our field of view with significant detections, composite supernova remnant G0.9+0.1 and HESS J1746-285.Comment: 19 pages, 8 figures, Accepted for publication in Astrophysical Journa

VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study

The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E $>100$ GeV) $\gamma$-ray emission from this active galaxy. An analysis of $\sim$57 hours of quality-selected live time yields a detection at the position of the source, corresponding to a statistical significance of 7.8 standard deviations above background. The observed VHE flux is variable on monthly time scales, with an elevated flux seen in 2018 observations. The VHE emission during this elevated state is well-characterized by a power-law spectrum with a photon index $\Gamma = 2.20 \pm 0.27$ and flux F($>315$ GeV) = ($7.6\pm 1.2_{\mathrm stat} \pm 2.3_{\mathrm syst})\times 10^{-13}$ cm$^{-2}$ s$^{-1}$, or approximately 0.7% of the Crab Nebula flux above the same threshold. 3C 264 ($z = 0.0217$) is the most distant radio galaxy detected at VHE, and the elevated state is thought to be similar to that of the famously outbursting jet in M 87. Consequently, extensive contemporaneous multi-wavelength data were acquired in 2018 at the time of the VHE high state. An analysis of these data, including VLBA, VLA, HST, Chandra and Swift observations in addition to the VERITAS data, is presented, along with a discussion of the resulting spectral energy distribution.Comment: 19 pages, 11 figures, Accepted for publication in Astrophysical Journa