ABSTRACT
In our previous study of Neptune’s 4:7 mean-motion resonance (MMR), we discovered that its resonant angle can only librate within a specific eccentricity (e) versus inclination (i) region, ...determined by a theoretical limiting curve. This ‘permissible region’ is independent of time and encompasses the entire possible stable region. We now generalize this theory to investigate all high-order MMRs embedded in the main classical Kuiper belt (MCKB). We first consider the second-order 3:5 MMR in the framework of planet migration and resonance capture, and have further validated our limiting curve theory for both captured and observed 3:5 resonators. It suggests that only the (e, i) pairs inside the individual permissible regions should be chosen as initial conditions for studying the in situ evolution of high-order resonators. With such a new setting, we proceed to explore the long-term stability (for 4 Gyr) of different resonant populations, and our simulations predict that (1) the 3:5 and 4:7 resonators are comparable in number, and they could have inclinations up to 40°, (2) the populations of objects in the higher order 5:9, 6:11, 7:12, and 7:13 resonances are about 1/10 of the 3:5 (or 4:7) resonator population, and nearly all of them are found on the less inclined orbits with i < 10°, and (3) for these high-order resonances, almost all resonators reside in their individual permissible regions. In summary, our results make predictions for the number and orbital distributions of potential resonant objects that will be discovered in the future throughout the MCKB.
The scattering trans-Neptunian Objects (TNOs) can be measured to smaller sizes than any other distant small-body population. We use the largest sample yet obtained, 68 discoveries, primarily by the ...Outer Solar System Origins Survey (OSSOS), to constrain the slope of its luminosity distribution, with sensitivity to much fainter absolute H-magnitudes than previous work. Using the analysis technique in Shankman et al., we confirm that a single slope for the H-distribution is not an accurate representation of the scattering TNOs and Centaurs, and that a break in the distribution is required, in support of previous conclusions. A bright-end slope of b = 0.9 transitioning to a faint-end slope f of 0.4-0.5 with a differential number contrast c from 1 (a knee) to 10 (a divot) provides an acceptable match to our data. We find that break magnitudes Hb of 7.7 and 8.3, values both previously suggested for dynamically hot Kuiper Belt populations, are equally non-rejectable for a range of f and c in our statistical analysis. Our preferred divot H-distribution transitions to f = 0.5 with a divot of contrast c = 3 at Hb = 8.3, while our preferred knee H-distribution transitions to f = 0.4 at Hb = 7.7. The intrinsic population of scattering TNOs required to match the OSSOS detections is 3 × 106 for Hr < 12, and 9 × 104 for Hr < 8.66 (D 100 km), with Centaurs having an intrinsic population two orders of magnitude smaller.
We analyze a detailed Nice model simulation of Kuiper Belt emplacement from Brasser & Morbidelli, where Neptune undergoes a high-eccentricity phase and migrates outward. In this work, which follows ...from Pike et al., we specifically focus on the details of structures within Neptune's mean-motion resonances and in the high-pericenter population of simulated trans-Neptunian objects (TNOs). We find several characteristics of these populations that should be observable in the distant solar system in future large-scale TNO surveys as a diagnostic of whether or not this mode of Neptune migration occurred in the early solar system. We find that the leading asymmetric libration islands of the n:1 resonances are generally much more populated than the trailing islands. We also find the nonresonant high-q population of TNOs should have higher inclinations than the low-q population due to the importance of Kozai cycling during their emplacement histories. Finally, high-q TNOs should be present in roughly equal numbers on either side of distant mean-motion resonances. These predictions contrast with predictions from other Kuiper Belt emplacement simulations and will be testable by upcoming surveys.
We explore the distant giant planet hypothesis by integrating the large-semimajor-axis, large-pericenter trans-Neptunian objects (TNOs) in the presence of the giant planets and an external perturber ...whose orbit is consistent with the proposed distant, eccentric, and inclined giant planet, so-called planet 9. We find that TNOs with semimajor axes greater than 250 au experience some longitude of perihelion shepherding, but that a generic outcome of such evolutions is that the TNOs evolve to larger pericenter orbits and commonly get raised to retrograde inclinations. This pericenter and inclination evolution requires a massive disk of TNOs (tens of ) in order to explain the detection of the known sample today. Some of the highly inclined orbits produced by the examined perturbers will be inside of the orbital parameter space probed by prior surveys, implying a missing signature of the ninth-planet scenario. The distant giant planet scenarios explored in this work do not reproduce the observed signal of simultaneous clustering in argument of pericenter, longitude of the ascending node, and longitude of perihelion in the region of the known TNOs.
The migration of Neptune's resonances through the proto-Kuiper Belt has been imprinted in the distribution of small bodies in the outer solar system. Here we analyze five published Neptune migration ...models in detail, focusing on the high pericenter distance (high-q) trans-Neptunian objects (TNOs) near Neptune's 5:2 and 3:1 mean-motion resonances because they have large resonant populations, are outside the main classical belt, and are relatively isolated from other strong resonances. We compare the observationally biased output from these dynamical models with the detected TNOs from the Outer Solar System Origins Survey (OSSOS) via its Survey Simulator. All four of the new OSSOS detections of high-q nonresonant TNOs are on the sunward side of the 5:2 and 3:1 resonances. We show that even after accounting for observation biases, this asymmetric distribution cannot be drawn from a uniform distribution of TNOs at 2 confidence. As shown by previous work, our analysis here tentatively confirms that the dynamical model that uses grainy slow Neptune migration provides the best match to the real high-q TNO orbital data. However, due to extreme observational biases, we have very few high-q TNO discoveries with which to statistically constrain the models. Thus, this analysis provides a framework for future comparison between the output from detailed, dynamically classified Neptune migration simulations and the TNO discoveries from future well-characterized surveys. We show that a deeper survey (to a limiting r-magnitude of 26.0) with a similar survey area to OSSOS could statistically distinguish between these five Neptune migration models.
This paper presents a new zero-voltage-switching (ZVS) bidirectional dc-dc converter. Compared to the traditional full and half bridge bidirectional dc-dc converters for the similar applications, the ...new topology has the advantages of simple circuit topology with no total device rating (TDR) penalty, soft-switching implementation without additional devices, high efficiency and simple control. These advantages make the new converter promising for medium and high power applications especially for auxiliary power supply in fuel cell vehicles and power generation where the high power density, low cost, lightweight and high reliability power converters are required. The operating principle, theoretical analysis, and design guidelines are provided in this paper. The simulation and the experimental verifications are also presented.
ABSTRACT
The high-inclination population in the 4:7 mean-motion resonance (MMR) with Neptune has also substantial eccentricities (e ≳ 0.1), with more inclined objects tending to occupy more eccentric ...orbits. For this high-order resonance, there are two different resonant modes. The principal one is the eccentricity-type mode, and we find that libration is permissible for orbits with $e\ge e_\mathrm{ c}^0$, where the critical eccentricity $e_\mathrm{ c}^0$ increases as a function of increasing inclination i. Correspondingly, we introduce a limiting curve $e_\mathrm{ c}^0(i)$, which puts constraints on the (e, i) distribution of possible 4:7 resonators. We then perform numerical simulations on the sweep-up capture and long-term stability of the 4:7 MMR, and the results show that the simulated resonators are well constrained by this theoretical limiting curve. The other 4:7 resonant mode is the mixed-(e, i)-type, and we show that stable resonators should exist at i ≳ 20○. We predict that the intrinsic number of these mixed-(e, i)-type resonators may provide a new clue into the Solar system’s evolution, but, so far, only one real object has been observed resonating in this mode.
Snus is an oral tobacco product that originated in Sweden. Snus products are available as fine-cut loose tobacco or in pre-portioned porous "pouches." Some snus products undergo tobacco ...pasteurization during manufacturing, a process that removes or reduces nitrite-forming microbes, resulting in less tobacco-specific nitrosamine content in the product. Some tobacco companies and researchers have suggested that snus is potentially less harmful than traditional tobacco and thus a potential smoking cessation aid or an alternative to continued cigarette consumption. Although snus is available in various countries, limited information exists on snus variants from different manufacturers.
Moisture, pH, nicotine, and tobacco-specific N'-nitrosamines (TSNAs) were quantified in 64 snus products made by 10 manufacturers in the United States and Northern Europe (NE). Reported means, standard errors, and differences are least-square (LS) estimates from bootstrapped mixed effects models, which accounted for correlation among repeated measurements. Minor alkaloids and select flavors were also measured.
Among all product types, moisture (27.4%-59.5%), pH (pH 5.87-9.10), total nicotine (6.81-20.6 mg/g, wet), unprotonated nicotine (0.083-15.7 mg/g), and total TSNAs (390-4,910 ng/g) varied widely. The LS-mean unprotonated nicotine concentration of NE portion (7.72 mg/g, SE = 0.963) and NE loose (5.06 mg/g, SE = 1.26) snus were each significantly higher than US portion snus (1.00 mg/g, SE = 1.56). Concentrations of minor alkaloids varied most among products with the highest total nicotine levels. The LS-mean NNN+NNK were higher in snus sold in the US (1360 ng/g, SE = 207) than in NE (836 ng/g, SE = 132) countries. The most abundant flavor compounds detected were pulegone, eucalyptol, and menthol.
Physical and chemical characteristics of US and NE products labeled as snus can vary considerably and should not be considered "equivalent". Our findings could inform public health and policy decisions pertaining to snus exposure and potential adverse health effects associated with snus.
Insufficient stress response and elevated oxidative stress can contribute to skeletal muscle atrophy during mechanical unloading (e.g., spaceflight and bedrest). Perturbations in heat shock proteins ...(e.g., HSP70), antioxidant enzymes, and sarcolemmal neuronal nitric oxidase synthase (nNOS) have been linked to unloading-induced atrophy. We recently discovered that the sarcolemmal NADPH oxidase-2 complex (Nox2) is elevated during unloading, downstream of angiotensin II receptor 1, and concomitant with atrophy. Here, we hypothesized that peptidyl inhibition of Nox2 would attenuate disruption of HSP70, MnSOD, and sarcolemmal nNOS during unloading, and thus muscle fiber atrophy. F344 rats were divided into control (CON), hindlimb unloaded (HU), and hindlimb unloaded +7.5 mg/kg/day gp91ds-tat (HUG) groups. Unloading-induced elevation of the Nox2 subunit p67phox-positive staining was mitigated by gp91ds-tat. HSP70 protein abundance was significantly lower in HU muscles, but not HUG. MnSOD decreased with unloading; however, MnSOD was not rescued by gp91ds-tat. In contrast, Nox2 inhibition protected against unloading suppression of the antioxidant transcription factor Nrf2. nNOS bioactivity was reduced by HU, an effect abrogated by Nox2 inhibition. Unloading-induced soleus fiber atrophy was significantly attenuated by gp91ds-tat. These data establish a causal role for Nox2 in unloading-induced muscle atrophy, linked to preservation of HSP70, Nrf2, and sarcolemmal nNOS.
ABSTRACT The orbital element distribution of trans-Neptunian objects (TNOs) with large pericenters has been suggested to be influenced by the presence of an undetected, large planet at >200 au from ...the Sun. To find additional observables caused by this scenario, we present here the first detailed emplacement simulation in the presence of a massive ninth planet on the distant Kuiper Belt. We perform 4 Gyr N-body simulations with the currently known solar system planetary architecture, plus a 10 M⊕ planet with similar orbital parameters to those suggested by Trujillo & Sheppard or Batygin & Brown, and 105 test particles in an initial planetesimal disk. We find that including a distant super-Earth-mass planet produces a substantially different orbital distribution for the scattering and detached TNOs, raising the pericenters and inclinations of moderate semimajor axis (50 < a < 500 au) objects. We test whether this signature is detectable via a simulator with the observational characteristics of four precisely characterized TNO surveys. We find that the qualitatively very distinct solar system models that include a ninth planet are essentially observationally indistinguishable from an outer solar system produced solely by the four giant planets. We also find that the mass of the Kuiper Belt's current scattering and detached populations is required to be 3-10 times larger in the presence of an additional planet. We do not find any evidence for clustering of orbital angles in our simulated TNO population. Wide-field, deep surveys targeting inclined high-pericenter objects will be required to distinguish between these different scenarios.
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