In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two Centaur objects: 2014 YY49 on 2019 January 28 and 2013 NL24 on ...2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius km and a geometric albedo for 2014 YY49 and a radius km and a geometric albedo for 2013 NL24. To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two Centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two Centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects' colors and light curve amplitudes and on follow-on occultation efforts informed by this astrometry.
Abstract
In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two Centaur objects: 2014 YY
49
on 2019 January 28 and 2013 ...NL
24
on 2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius
km and a geometric albedo
for 2014 YY
49
and a radius
km and a geometric albedo
for 2013 NL
24
. To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two Centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two Centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects’ colors and light curve amplitudes and on follow-on occultation efforts informed by this astrometry.
In 2019, the Research and Education Collaborative Occultation Network (RECON) obtained multiple-chord occultation measurements of two centaur objects: 2014 YY\(_{49}\) on 2019 January 28 and 2013 ...NL\(_{24}\) on 2019 September 4. RECON is a citizen-science telescope network designed to observe high-uncertainty occultations by outer solar system objects. Adopting circular models for the object profiles, we derive a radius \(r=16^{+2}_{-1}\)km and a geometric albedo \(p_V=0.13^{+0.015}_{-0.024}\) for 2014 YY\(_{49}\), and a radius \(r=66 ^{+5}_{-5}\)km and geometric albedo \(p_V = 0.045^{+0.006}_{-0.008}\) for 2013 NL\(_{24}\). To the precision of these measurements, no atmosphere or rings are detected for either object. The two objects measured here are among the smallest distant objects measured with the stellar occultation technique. In addition to these geometric constraints, the occultation measurements provide astrometric constraints for these two centaurs at a higher precision than has been feasible by direct imaging. To supplement the occultation results, we also present an analysis of color photometry from the Pan-STARRS surveys to constrain the rotational light curve amplitudes and spectral colors of these two centaurs. We recommend that future work focus on photometry to more deliberately constrain the objects' colors and light curve amplitudes, and on follow-on occultation efforts informed by this astrometry.
Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ...ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current era of rapid climate change. Models that identify suitable linkages between core areas have been used to prioritize potentially important corridors for maintaining functional connectivity. Here, we identify the most "natural" (i.e., least human-modified) corridors between large protected areas in the contiguous Unites States. We aggregated results from multiple connectivity models to develop a composite map of corridors reflecting agreement of models run under different assumptions about how human modification of land may influence connectivity. To identify which land units are most important for sustaining structural connectivity, we used the composite map of corridors to evaluate connectivity priorities in two ways: (1) among land units outside of our pool of large core protected areas and (2) among units administratively protected as Inventoried Roadless (IRAs) or Wilderness Study Areas (WSAs). Corridor values varied substantially among classes of "unprotected" non-core land units, and land units of high connectivity value and priority represent diverse ownerships and existing levels of protections. We provide a ranking of IRAs and WSAs that should be prioritized for additional protection to maintain minimal human modification. Our results provide a coarse-scale assessment of connectivity priorities for maintaining a connected network of protected areas.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
The National Cardiogenic Shock Initiative is a single‐arm, prospective, multicenter study to assess outcomes associated with early mechanical circulatory support (MCS) in patients ...presenting with acute myocardial infarction and cardiogenic shock (AMICS) treated with percutaneous coronary intervention (PCI).
Methods
Between July 2016 and February 2019, 35 sites participated and enrolled into the study. All centers agreed to treat patients with AMICS using a standard protocol emphasizing invasive hemodynamic monitoring and rapid initiation of MCS. Inclusion and exclusion criteria mimicked those of the “SHOCK” trial with an additional exclusion criteria of intra‐aortic balloon pump counter‐pulsation prior to MCS.
Results
A total of 171 consecutive patients were enrolled. Patients had an average age of 63 years, 77% were male, and 68% were admitted with AMICS. About 83% of patients were on vasopressors or inotropes, 20% had a witnessed out of hospital cardiac arrest, 29% had in‐hospital cardiac arrest, and 10% were under active cardiopulmonary resuscitation during MCS implantation. In accordance with the protocol, 74% of patients had MCS implanted prior to PCI. Right heart catheterization was performed in 92%. About 78% of patients presented with ST‐elevation myocardial infarction with average door to support times of 85 ± 63 min and door to balloon times of 87 ± 58 min.
Survival to discharge was 72%. Creatinine ≥2, lactate >4, cardiac power output (CPO) <0.6 W, and age ≥ 70 years were predictors of mortality. Lactate and CPO measurements at 12–24 hr reliably predicted overall mortality postindex procedure.
Conclusion
In contemporary practice, use of a shock protocol emphasizing best practices is associated with improved outcomes.
Multi-objective optimization of power converters is a time-consuming task, especially when multiple operating points and multiple converter topologies must be considered. As a result, various steps ...are often taken to simplify the design problem and restrict the size of the design space prior to going through an optimization procedure. While this saves time, it produces potentially sub-optimal designs, and existing approaches must tradeoff between running time and design optimality. This paper presents an optimization-oriented method for modeling power converters and their components as posynomial functions, allowing multi-objective optimization of converters to be formulated as a geometric program, a type of convex optimization problem. This allows the use of fast, powerful solvers that guarantee global optimality of solutions. The method is demonstrated using the example of low-power multi-level flying capacitor step-down converters. Results show that, using geometric programming, sets of globally Pareto-optimal designs of two-, three-, and four-level converters with respect to efficiency and power density, for one design space and one operating point, can be generated in as little as 25 s, on a mid- to upper range laptop computer. Thus, optimal designs for three different converter topologies for hundreds of different operating points and/or design spaces can be generated in several hours-less than the time required to globally optimize one converter topology at one operating point for one design space using currently prevalent methods. This paper also demonstrates how geometric programming can be used to quickly perform sensitivity and tradeoff analysis of optimal converter designs.
Background While controversy remains as to the relative benefit of operative (OM) versus non-operative management (NOM) of Achilles tendon (AT) ruptures (ATR), few studies have examined the effect on ...high impact maneuvers such as jumping and hopping. Hypothesis/Purpose The purpose of this study was to determine if functional performance including strength, jumping, and hopping outcomes differed between OM and NOM of acute ATR. The secondary objective was to assess the degree of association between AT morphology and performance outcomes. Study Design Retrospective cohort with a single prospective evaluation. Methods All patients were treated at an institutional secondary care center. Eligible participants (n=12 OM; 12 NOM) who were treated with OM or NOM of ATR within three weeks of injury were evaluated a minimum 20 months following ATR. AT length, thickness and gastrocnemius muscle thickness were assessed with B-mode ultrasound. Isokinetic plantar flexor strength, hop tests and countermovement and drop jumps were completed. Two-way ANOVAS were completed on all tests with unilateral values, independent t-tests were used for bilateral outcomes, and linear regressions were completed to assess the relationship between normalized AT length and performance. Results Affected limb AT was elongated and thickened (p<0.01), gastrocnemius was atrophied (p< 0.01) and angle-specific plantar flexor torque was reduced at 120°/s when measured at 20° plantar flexion (p = 0.028). Single leg drop vertical jump was higher in OM (p = 0.015) with no difference for hop and jump tests. AT length was related to plantar flexor torque but had no relationship with hopping performance. Conclusions Hop test performance was maintained despite plantarflexion weakness, gastrocnemius atrophy, and AT elongation. This may be the result of compensatory movement patterns. AT length holds limited explanatory power in plantar flexor strength, although this relationship should be evaluated further. Level of Evidence Level III
The gut-brain axis, which is mediated via enteric and central neurohormonal signaling, is known to regulate a broad set of physiological functions from feeding to emotional behavior. Various ...pharmaceuticals and surgical interventions, such as motility agents and bariatric surgery, are used to modulate this axis. Such approaches, however, are associated with off-target effects or post-procedure recovery time and expose patients to substantial risks. Electrical stimulation has also been used to attempt to modulate the gut-brain axis with greater spatial and temporal resolution. Electrical stimulation of the gastrointestinal (GI) tract, however, has generally required invasive intervention for electrode placement on serosal tissue. Stimulating mucosal tissue remains challenging because of the presence of gastric and intestinal fluid, which can influence the effectiveness of local luminal stimulation. Here, we report the development of a bioinspired ingestible fluid-wicking capsule for active stimulation and hormone modulation (FLASH) capable of rapidly wicking fluid and locally stimulating mucosal tissue, resulting in systemic modulation of an orexigenic GI hormone. Drawing inspiration from
the "thorny devil" lizard with water-wicking skin, we developed a capsule surface capable of displacing fluid. We characterized the stimulation parameters for modulation of various GI hormones in a porcine model and applied these parameters to an ingestible capsule system. FLASH can be orally administered to modulate GI hormones and is safely excreted with no adverse effects in porcine models. We anticipate that this device could be used to treat metabolic, GI, and neuropsychiatric disorders noninvasively with minimal off-target effects.
This study sought to compare outcomes of patients enrolled in the NCSI (National Cardiogenic Shock Initiative) trial who were treated using a revascularization strategy of percutaneous coronary ...intervention (PCI) of multivessel PCI (MV-PCI) versus culprit-vessel PCI (CV-PCI).
In patients with multivessel disease who present with acute myocardial infarction and cardiogenic shock (AMICS), intervening on the nonculprit vessel is controversial. There are conflicting published reports and lack of evidence, particularly in patients treated with early mechanical circulatory support (MCS).
From July 2016 to December 2019, patients who presented with AMICS to 57 participating hospitals were included in this analysis. All patients were treated using a standard shock protocol emphasizing early MCS, revascularization, and invasive hemodynamic monitoring. Patients with multivessel coronary artery disease (MVCAD) were analyzed according to whether CV-PCI or MV-PCI was undertaken during the index procedure.
Of 198 patients with MVCAD, 126 underwent MV-PCI (64%) and 72 underwent CV-PCI (36%). Demographics between the cohorts were similar with respect to age, sex, history of diabetes, prior PCI or coronary artery bypass grafting, and prior history of myocardial infarction. Patients who underwent MV-PCI had a trend toward more severe impairment of cardiac output and worse lactate clearance on presentation, and cardiac performance was significantly worse at 12 h. However, 24 h from PCI, the hemometabolic derangements were similar. Survival and rates of acute kidney injury were not significantly different between groups (69.8% MV-PCI vs. 65.3% CV-PCI; p = 0.51; and 29.9% vs. 34.2%; p = 0.64, respectively).
In patients with MVCAD presenting with AMICS treated with early MCS, revascularization of nonculprit lesions was associated with similar hospital survival and acute kidney injury when compared with culprit-only PCI. Selective nonculprit PCI can be safety performed in AMICS in patients supported with mechanical circulatory support.
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