Signed permutohedra, delta-matroids, and beyond

We establish a connection between the algebraic geometry of the type B permutohedral toric variety and the combinatorics of delta-matroids. Using this connection, we compute the volume and lattice point counts of type B generalized permutohedra. Applying tropical Hodge theory to a new framework of "tautological classes of delta-matroids," modeled after certain vector bundles associated to realizable delta-matroids, we establish the log-concavity of a Tutte-like invariant for a broad family of delta-matroids that includes all realizable delta-matroids. Our results include new log-concavity statements for all (ordinary) matroids as special cases

Dynamic Performance of Cantilevered Sign Trusses for Fatigue

Cantilevered overhead sign structures (COSS) experience cyclic loading due to stochastic loads such as natural wind gusts (NWG). Wind loading can produce large deflections in the cantilever and large-magnitude stresses can develop at the box-type connection between the cantilevered arm and mast where fatigue performance is a concern. Modifications to the sign structures pose further concerns as changes to the aerodynamic properties could have unintended consequences. A design consideration of COSS is serviceability of the sign through use of a steel grate walkway that workers can use for maintenance on the sign. The steel grate walkways on COSS are rarely used for maintenance anymore, hence are being removed by multiple state DOTs to prevent vandalism. However, the impact on COSS with the removal of the walkways is unknown. This report describes an investigation in which the dynamic and aerodynamic properties of COSS was studied, and the effect of the walkway presence on structural response was explored. Computer simulations of 32 different COSS configurations were carried out to see the effect of the grate removal on the natural frequency and the mass of the overall structural system. Aerodynamic performance was considered through the use of computational fluid dynamics (CFD) and experimental testing, where wind pressure on the sign in both axial directions and effects of vortex shedding were examined. Findings include: 1) the walkway had a minimal effect on the system’s mass and natural frequencies, 2) the walkway had a minimal influence on the wind-induced force on the sign, 3) vortex shedding was not exacerbated with removal of a walkway attachment, and 4) walkway removal did not significantly change stress magnitudes at the connection between the cantilever and mast. Based on these findings, the removal of walkways from KDOT’s COSS was not found to problematic.The Kansas Department of Transportatio

Astaxanthin Reduces Heart Rate and Carbohydrate Oxidation Rates During Exercise in Overweight Individuals

International Journal of Exercise Science 16(2): 252-266, 2023. Astaxanthin (AX) is an antioxidant which may spare endogenous carbohydrates and improve fat oxidation rates, thus improving metabolic flexibility. To date, no studies have attempted to examine the impact of AX in an overweight cohort, whom often suffer from metabolic inflexibility. Nineteen subjects (mean ± SD: age: 27.5 ± 6.3 years; height: 169.7 ± 9.0 cm; body mass: 96.4 ± 17.9 kg; BF%: 37.9 ± 7.0%; BMI: 33.4 ± 5.6 kg/m2; VO2peak: 25.9 ± 6.7 ml·kg−1·min−1) were recruited and supplemented with either 12 mg of AX or placebo (PLA) for 4 weeks. Subjects completed a graded exercise test on a cycling ergometer to examine changes in substrate oxidation rates. A total of 5 stages, each lasting 5 min and resistance increased 15 W each stage, were completed to examine changes in levels of glucose and lactate, fat and carbohydrate (CHO) oxidation rates, heart rate, and rating of perceived exertion (RPE). Although there were no changes found in rates of fat oxidation, blood lactate or glucose, or RPE (all p \u3e 0.05), a significant decrease was observed in CHO oxidation from pre to post supplementation in the AX group only. Further, the AX group demonstrated a 7% decrease in heart rate across the graded exercise test. These findings suggest that 4 weeks of AX supplementation may offer some cardiometabolic benefits to overweight individuals, and be a favorable supplement for these individuals beginning an exercise program

Effect of feeding system on enteric methane emissions from individual dairy cows on commercial farms

This study investigated the effects of feeding system on diurnal enteric methane (CH4) emissions from individual cows on commercial farms. Data were obtained from 830 cows across 12 farms, and data collated included production records, CH4 measurements (in the breath of cows using CH4 analysers at robotic milking stations for at least seven days) and diet composition. Cows received either a partial mixed ration (PMR) or a PMR with grazing. A linear mixed model was used to describe variation in CH4 emissions per individual cow and assess the effect of feeding system. Methane emissions followed a consistent diurnal pattern across both feeding systems, with emissions lowest between 05:00 and 08:59, and with a peak concentration between 17:00 and 20:59. No overall difference in emissions was found between feeding systems studied; however, differences were found in the diurnal pattern of CH4 emissions between feeding systems. The response in emissions to increasing dry matter intake was higher for cows fed PMR with grazing. This study showed that repeated spot measurements of CH4 emissions whilst cows are milked can be used to assess the effects of feeding system and potentially benchmark farms on level of emissions

Early adoption in an agile online teaching environment: an intrapreneurial perspective

The Covid-19 pandemic has blown through the Higher Education sector like a Schumpterian ‘gale of creative destruction’ (Schumpeter, 1934), accelerating the pace of change, disrupting entrenched pedagogical approaches, and revealing glimpses of the future of teaching. This study identifies how university-based early adopters responded to this ‘gale,’ successfully implementing the rapid change required to pivot to online teaching while addressing institutional requests to support the reluctant majority. Adopting an innovative interdisciplinary framework, this study advances understanding about the criticality of early-adopter behaviour in implementing change. The triggers, dynamics and impact of early-adopter behaviours are identified, as are the resultant implications for institutions for resourcing, recognising, and rewarding early adopters. The research design is underpinned by polyphony (Belova, 2010). Theoretical aspects from entrepreneurship (Stevenson, Roberts & Grousebeck, 1989) and networked learning (Dohn, Cranmer, Sime, De Laat & Ryberg, 2018) are also incorporated, relating early adopter behaviour to the entrepreneurial process in the context of virtual learning communities. This study uses vignettes from early adopters who have pivoted to online teaching in a university, identifying their experiences of instigating and supporting change. The findings highlight the facilitators of, and constraints on, early adopter behaviour, identifying the contextual characteristics necessary to challenge preconceived institutional notions and develop intrapreneurial mindsets that more readily support and implement early-adopter behaviours

International Examination and Synthesis of the Primary and Secondary Surveys in Paramedicine

BackgroundTo guide their care paramedics routinely rely upon two assessment and treatment algorithms, known as the primary survey and the secondary survey.  No clear consensus of the concepts (assessments and interventions) that are, or should be, included in these algorithms exist internationally. Methods This paper evaluated Australasian paramedic clinical practice guidelines (CPGs), as well as six other international paramedic CPGs (USA, Ireland, UK, South Africa, Qatar, and the United Arab Emirates) in order to identify which concepts are currently described in best-practice recommendations for paramedics.  The authors also contributed concepts that they felt were important additions based on their experience as veteran paramedics and paramedic educators.Results The resulting amalgamation of concepts identified in each term was then formed into two mnemonics which, together sequentially list approximately 100 specific clinical concepts that paramedics routinely consider in their care of patients. We describe these as the “International Paramedic Primary and Secondary Surveys”.Conclusion The primary and secondary surveys presented in this paper represent an evidence-based guide to the best practice in conducting a primary and secondary survey in the paramedic context.  Findings will be of use to paramedics, paramedic students, and other clinicians working in remote or isolated practices

The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC1365

We present a multiwavelength analysis of the prominent active galaxy NGC1365, in particular looking at the radio and X-ray properties of the central regions of the galaxy. We analyse ROSAT observations of NGC1365, and discuss recent ASCA results. In addition to a number of point sources in the vicinity of NGC1365, we find a region of X-ray emission extending along the central bar of the galaxy, combined with an emission peak near the centre of the galaxy. This X-ray emission is centred on the optical/radio nucleus, but is spatially extended. The X-ray spectrum can be well fitted by a thermal plasma model, with kT=0.6-0.8keV and a low local absorbing column. The thermal spectrum is suggestive of starburst emission rather than emission from a central black-hole. The ATCA radio observations show a number of hotspots, located in a ring around a weak radio nucleus. Synchrotron emission from electrons accelerated by supernovae and supernova remnants (SNRs) is the likely origin of these hotspots. The radio nucleus has a steep spectrum, indicative perhaps of an AGN or SNRs. The evidence for a jet emanating from the nucleus is at best marginal. The extent of the radio ring is comparable to the extended central X-ray source.Comment: 13 pages, 5 figures, to be published in MNRA

Design of a Green Monopropellant Propulsion System for the Lunar Flashlight CubeSat Mission

Lunar Flashlight is a 6U CubeSat mission from NASA\u27s Jet Propulsion Laboratory that will search for water-ice deposits near the lunar south pole. Lunar Flashlight aims to add to the flight experience of deep-space CubeSats by demonstrating an orbit insertion using a green monopropellant propulsion system designed uniquely for this mission. Developed by NASA Marshall Spaceflight Center (MSFC) and Georgia Tech\u27s Space Systems Design Laboratory (SSDL), the Lunar Flashlight Propulsion System (LFPS) delivers over 2500N-s of total impulse for the orbit insertion and necessary attitude maneuvers. The custom propulsion system fits within a 2.5U volume and has a total wet mass of less than six kilograms. It will be fueled byAF-M315E, which is a green monopropellant developed by the Air Force Research Laboratory (AFRL) as a safer alternative to hydrazine. Additive manufacturing is utilized to fabricate several components of its primary structure. Upon completion, Lunar Flashlight may become the first CubeSat to achieve orbit around a celestial body besides Earth. The LFPS aims to be a pathfinder device for CubeSat missions by demonstrating how monopropellant systems, green monopropellant fuel, and additive manufacturing can be utilized to expand the reach of small satellite space exploration