Disparate Mass Research Articles

General synthetic iterative scheme for rarefied gas mixture flows

The numerical simulation of rarefied gas mixtures with disparate mass and concentration is a huge research challenge. Based on our recent kinetic modeling for monatomic gas mixture flows, this problem is tackled by the general synthetic iterative scheme (GSIS), where the mesoscopic kinetic and macroscopic synthetic equations are alternately solved by the finite-volume discrete velocity method. Three important features of GSIS are highlighted. First, the synthetic equations are precisely derived from the kinetic equation, naturally reducing to the Navier-Stokes equations in the continuum flow regime; in other flow regimes, the kinetic equation provides high-order closure of the constitutive relations to capture the rarefaction effects. Second, these synthetic equations, which can be solved quickly, help to adjust the kinetic system to relax rapidly toward the steady state. Furthermore, in such a two-way coupling, the constraint on the spatial cell size is relieved. Third, the linear Fourier stability analysis demonstrates that the error decay rate in GSIS is smaller than 0.5 for various combinations of mass, concentration and viscosity ratios, such that the error can be reduced by three orders of magnitude after 10 iterations. The efficiency and accuracy of GSIS are demonstrated through several challenging cases covering a wide range of mass ratio, species concentration, and flow speed.

The dynamics of Lato Lato ball collisions

Lato Lato is a toy that consists of two identical solid balls that are secured together with a rope and can be used as a learning tool in physics. In this study, we examined why the Lato Lato toy uses two balls with the same mass rather than balls with different masses. The collision of the two Lato Lato balls can be considered an elastic collision. The two balls move symmetrically at the same velocity and form a semi-circular route with opposing motion directions when we use Lato Lato with the same ball mass ( m2=m1 ). The angular momentum of the two balls is also the same but in opposite directions, so they cancel each other out. Hence, the two balls travel steadily when Lato Lato is performed. This condition leads to a balanced movement of the Lato Lato system and prevents it from collapsing. On the other hand, because of their disparate masses ( {m_1}$?> m2>m1 ), the two balls of Lato Lato move in an imbalanced manner. A lighter ball travels farther because it moves more quickly than a heavier ball. The angular momentum of the two balls is in opposite directions but not of the same magnitude, so they do not cancel each other out. This results in unstable movement of the two balls when Lato Lato is played. Therefore, the two balls no longer collide centrally, like in Lato Lato, with the same mass, but the collision is glancing. Then, the motion of the two balls facilitates collapse easily. This work can enrich students’ understanding of collisions beyond the collisions of two objects commonly discussed in textbooks.

Evidence for Kilometer‐Scale Biophysical Features at the Gulf Stream Front

AbstractUnderstanding the interplay of ocean physics and biology at the submesoscale and below (<30 km) is an ongoing challenge in oceanography. While poorly constrained, these scales may be of critical importance for understanding how changing ocean dynamics will impact marine ecosystems. Fronts in the ocean, regions where two disparate water masses meet and isopycnals become tilted toward vertical, are considered hotspots for biophysical interaction, but there is limited observational evidence at the appropriate scales to assess their importance. Fronts around western boundary currents like the Gulf Stream are of particular interest as these dynamic physical regions are thought to influence both productivity and composition of primary producers; however, how exactly this plays out is not well known. Using satellite data and 2 years of in situ observations across the Gulf Stream front near Cape Hatteras, North Carolina, we investigate how submesoscale frontal dynamics could affect biological communities and generate hotspots of productivity and export. We assess the seasonality and phenology of the region, generalize the kilometer‐scale structure of the front, and analyze 69 transects to assess two physical processes of potential biogeochemical importance: cold shelf filament subduction and high salinity Sargasso Sea obduction. We link these processes observationally to meanders in the Gulf Stream and discuss how cold filament subduction could be exporting carbon and how obduction of high salinity water from depth is connected with high chlorophyll‐a. Finally, we report on phytoplankton community composition in each of these features and integrate these observations into our understanding of frontal submesoscale dynamics.

Investigating the Atmospheric Mass Loss of the Kepler-105 Planets Straddling the Radius Gap

An intriguing pattern among exoplanets is the lack of detected planets between approximately 1.5 R ⊕ and 2.0 R ⊕. One proposed explanation for this “radius gap” is the photoevaporation of planetary atmospheres, a theory that can be tested by studying individual planetary systems. Kepler-105 is an ideal system for such testing due to the ordering and sizes of its planets. Kepler-105 is a Sun-like star that hosts two planets straddling the radius gap in a rare architecture with the larger planet closer to the host star (R b = 2.53 ± 0.07 R ⊕, P b = 5.41 days, R c = 1.44 ± 0.04 R ⊕, P c = 7.13 days). If photoevaporation sculpted the atmospheres of these planets, then Kepler-105b would need to be much more massive than Kepler-105c to retain its atmosphere, given its closer proximity to the host star. To test this hypothesis, we simultaneously analyzed radial velocities and transit-timing variations of the Kepler-105 system, measuring disparate masses of M b = 10.8 ± 2.3 M ⊕ (ρ b = 3.68 ± 0.84 g cm−3) and M c = 5.6 ± 1.2 M ⊕ (ρ c = 10.4 ± 2.39 g cm−3). Based on these masses, the difference in gas envelope content of the Kepler-105 planets could be entirely due to photoevaporation (in 76% of scenarios), although other mechanisms like core-powered mass loss could have played a role for some planet albedos.

The Cauchy Problem for Boltzmann Bi-linear Systems: The Mixing of Monatomic and Polyatomic Gases

From a unified vision of vector valued solutions in weighted Banach spaces, this paper establishes the existence and uniqueness for space homogeneous Boltzmann bi-linear systems with conservative collisional forms arising in complex gas dynamical structures. This broader vision is directly applied to dilute multi-component gas mixtures composed of both monatomic and polyatomic gases. Such models can be viewed as extensions of scalar Boltzmann binary elastic flows, as much as monatomic gas mixtures with disparate masses and single polyatomic gases, providing a unified approach for vector valued solutions in weighted Banach spaces. Novel aspects of this work include developing the extension of a general ODE theory in vector valued weighted Banach spaces, precise lower bounds for the collision frequency in terms of the weighted Banach norm, energy identities, angular or compact manifold averaging lemmas which provide coerciveness resulting into global in time stability, a new combinatorics estimate for p-binomial forms producing sharper estimates for the k-moments of bi-linear collisional forms. These techniques enable the Cauchy problem improvement that resolves the model with initial data corresponding to strictly positive and bounded initial vector valued mass and total energy, in addition to only a 2+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$2^+$$\\end{document} moment determined by the hard potential rates discrepancy, a result comparable in generality to the classical Cauchy theory of the scalar homogeneous Boltzmann equation.

Disparate Muscle Mass And Performance 10-day Outcomes Following Distinct Contraction Protocols Despite Comparable Earlier Responses

Disparate Muscle Mass And Performance 10-day Outcomes Following Distinct Contraction Protocols Despite Comparable Earlier Responses

Primordial black holes ensued from exponential potential and coupling parameter in nonminimal derivative inflation model

Here, Primordial Black Holes (PBHs) creation from exponential potential has been inquired, through gravitationally raised friction emanated from the nonminimal coupling between gravity and field derivative setup. Setting a two-parted exponential function of inflaton field as coupling parameter, and fine-tuning of four parameter Cases of our model, we could sufficiently slow down the inflaton owing to high friction during an ultra slow-roll phase. This empowers us to achieve enough enhancement in the amplitude of curvature perturbations power spectra, via numerical solving of Mukhanov-Sasaki equation. Thereafter, we illustrate the generation of four PBHs with disparate masses in RD era, corresponding to our four parameter Cases. Two specimens of these PBHs with stellar \U0001d4aa(10)M ⊙ and earth \U0001d4aa(10-6)M ⊙ masses can be appropriate to explicate the LIGO-VIRGO events, and the ultrashort-timescale microlensing events in OGLE data, respectively. Another two Cases of PBHs have asteroid masses around \U0001d4aa(10-13)M ⊙ and \U0001d4aa(10-15)M ⊙ with abundance of 96% and 95% of the Dark Matter (DM) content of the universe. Furthermore, we scrutinize the induced Gravitational Waves (GWs) ensued from PBHs production in our model. Subsequently, we elucidate that their contemporary density parameter spectra (ΩGW0 ) for all predicted Cases have acmes which lie in the sensitivity scopes of the GWs detectors, thereupon the verity of our conclusions can be verified in view of deduced data from these detectors. At length, our numerical outcomes exhibit a power-law behavior for the spectra of ΩGW0 with respect to frequency as ΩGW0 (f) ∼ (f/fc ) n in the proximity of acmes position. As well, in the infrared regime f ≪ fc , the log-reliant form of power index as n = 3 - 2/ln(fc /f) is attained.

Manipulating phonons of a trapped-ion system using optical tweezers

We propose an experimental architecture where an array of optical tweezers affords site-dependent control over the confining potential of a conventional radio-frequency ion trap. The site-dependent control enables programmable manipulation of phonon modes of ions, with many potential applications in quantum information processing (QIP) and thermodynamics. We describe protocols for programming the array of optical tweezers to attain a set of target phonon modes with high accuracy. We propose applications of such controls in simulating quantum thermodynamics of a particle of programmable effective mass via Jarzynski's equality and improving the efficiency of sympathetic cooling and quantum logic gates in a multispecies ion system of disparate masses. We discuss the required optical parameters in a realistic ion trap system and potential adverse effects of optical tweezers in QIP. Our scheme extends the utility of trapped ions as a platform for quantum computation and simulation.

Electrical transport properties of liquid Pb-Li alloys

It is generally observed that electrical transport properties of simple liquid metal based alloys can be explained well in terms of Faber-Ziman theory, 2kF scattering model and finite mean free path approach. However, these approaches give poor description for materials, which show departure from nearly free electron (NFE) model. Taking Pb-Li as a test case of a system showing departure from NFE (which also exhibit compound formation tendency and disparate mass system), a new technique is proposed to compute electrical transport properties using model potential formalism coupled with t-matrix formulation. We have treated valence number of Pb & Li as a parameter in determining phase shifts. Further, rather than calculating phase shift in terms of Muffin-Tin potential, we have used model potential formalism. Present results suggest that compared to other three theoretical approaches mentioned above, present coupling scheme reproduce qualitative features of electrical transport properties of liquid Pb-Li alloys, which can be used further to study electrical transport properties of similar systems.

Exploring the Potential of Electrospray-Orbitrap for Stable Isotope Analysis Using Nitrate as a Model.

Widely used isotope ratio mass spectrometers have limited capabilities to measure metabolites, drugs, or small polyatomic ions without the loss of structural isotopic information. A new approach has recently been introduced that uses electrospray ionization Orbitrap to measure multidimensional isotope signatures of intact polar compounds. Using nitrate as a model compound, this study aims to establish performance metrics for comparisons with conventional IRMS at the natural abundance level. We present a framework on how to convert isotopolog intensities to δ values that are commonly used in the isotope geochemistry community. The quantification of seven nitrate isotopologs provides multiple pathways for obtaining the primary N and O δ values including non-mass-dependent O isotope variations, as well as opportunities to explore nonrandom isotopic distributions (i.e., clumping effects) within molecular nitrate. Using automation and the adaptation of measurement principles that are specific to isotope ratio analysis, nitrate δ15NAIR, δ18OVSMOW, and δ17OVSMOW were measured with a long-term precision of 0.4‰ or better for isotopic reference materials and purified nitrate from environmental samples. In addition, we demonstrate promising results for unpurified environmental samples in liquid form. With these new developments, this study connects the two largely disparate mass spectrometry fields of bioanalytical MS and isotope ratio MS, thus providing a route to measure new isotopic signatures in diverse organic and inorganic solutes.

Extreme growth plasticity in the early branching sauropodomorph Massospondylus carinatus.

There is growing evidence of developmental plasticity in early branching dinosaurs and their outgroups. This is reflected in disparate patterns of morphological and histological change during ontogeny. In fossils, only the osteohistological assessment of annual lines of arrested growth (LAGs) can reveal the pace of skeletal growth. Some later branching non-bird dinosaur species appear to have followed an asymptotic growth pattern, with declining growth rates at increasing ontogenetic ages. By contrast, the early branching sauropodomorph Plateosaurus trossingensis appears to have had plastic growth, suggesting that this was the plesiomorphic condition for dinosaurs. The South African sauropodomorph Massospondylus carinatus is an ideal taxon in which to test this because it is known from a comprehensive ontogenetic series, it has recently been stratigraphically and taxonomically revised, and it lived at a time of ecosystem upheaval following the end-Triassic extinction. Here, we report on the results of a femoral osteohistological study of M. carinatus comprising 20 individuals ranging from embryo to skeletally mature. We find major variability in the spacing of the LAGs and infer disparate body masses for M. carinatus individuals at given ontogenetic ages, contradicting previous studies. These findings are consistent with a high degree of growth plasticity in M. carinatus.

Generalized impurity pinch in partially magnetized multi-ion plasma

In a two-ion-species plasma with disparate ion masses, heavy ions tend to concentrate in the low-temperature region of collisionally magnetized plasma and in the high-temperature region of collisionally unmagnetized plasma, respectively. Moreover, collisional magnetization can be determined as the ratio of the light ion gyrofrequency to the collision frequency of light and heavy ion species, and the behavior of this effect in the intermediate regime of partially magnetized plasma is predominantly dependent on this Hall parameter. Multi-ion cross-field transport has been described before in the collisionally magnetized plasma regime, and generalized pinch relations, which describe densities of ion species in equilibrium in that plasma, are found in the literature. In this paper, the role of collisional magnetization and Larmor magnetization in multi-ion collisional transport is clarified, and generalized pinch relations are extended to the partially magnetized regime in which the ion Hall parameter may be small, as long as electrons remain collisionally magnetized. Equilibrium ion density profiles have the same dependence on external forces and on each other regardless of collisional magnetization of ions. The expansion of the range of validity of multi-ion collisional transport models makes them applicable to a wider range of laboratory plasma conditions. In particular, ion density profiles evolve sufficiently fast for radial impurity transport to be observable around stagnation on MagLIF, leading to expulsion of heavy ion impurities from the hotspot as long as plasma becomes sufficiently collisionally magnetized during the implosion.

The MHD Plasma Flow Near the Heliopause Stagnation Region with A View On Kinetic Consistency

Most of the representative space plasma systems in our cosmic environment, - outside of stellar interiors, - like heliospheric, interstellar, or intergalactic plasmas etc., are collision-free or, at least, only weakly collision-determined systems. Nevertheless, these plasmas consist of at least two very different particle species, namely ions and electrons, i.e. particles with very disparate masses and opposite electric charges. If in these systems concerted fluid motions are arranged by electro-magnetic or gravitational forces or by inner forces like pressure gradients, then it must be asked how this combined electron-ion system finds its common internal dynamics. In most text book literature this problem is treated by considering the plasma as a mono-fluid system in which the massive protons and the nearly massless electrons are electrically closely bound together and move as an electrically neutral couple with an identical bulk velocity. Under these conditions the well-known Bernoulli law is derived for the standard MHD. If the electron pressure, however, does compete with the energy density of the ion bulk motion, then a two-fluid situation occurs, and the resulting bulk motion of the charge-neutral plasma needs to be determined on the basis of the kinetic conditions of the two different plasma fluids. In the following we shall exactly study this specific situation.

Rayleigh-Brillouin scattering in binary mixtures of disparate-mass constituents: SF_{6}-He,SF_{6}-D_{2}, and SF_{6}-H_{2}.

The spectral distribution of light scattered by microscopic thermal fluctuations in binary mixture gases was investigated experimentally and theoretically. Measurements of Rayleigh-Brillouin spectral profiles were performed at a wavelength of 532nm and at room temperature, for mixtures of SF_{6}-He,SF_{6}-D_{2}, and SF_{6}-H_{2}. In these measurements, the pressure of the gases with heavy molecular mass (SF_{6}) is set at 1bar, while the pressure of the lighter collision partner was varied. In view of the large polarizability of SF_{6} and the very small polarizabilities of He, H_{2}, and D_{2}, under the chosen pressure conditions these low mass species act as spectators and do not contribute to the light scattering spectrum, while they influence the motion and relaxation of the heavy SF_{6} molecules. A generalized hydrodynamic model was developed that should be applicable for the particular case of molecules with heavy and light disparate masses, as is the case for the heavy SF_{6} molecule, and the lighter collision partners. Based on the kinetic theory of gases, our model replaces the classical Navier-Stokes-Fourier relations with constitutive equations having an exponential memory kernel. The energy exchange between translational and internal modes of motion is included and quantified with a single parameter z that characterizes the ratio between the mean elastic and inelastic molecular collision frequencies. The model is compared with the experimental Rayleigh-Brillouin scattering data, where the value of the parameter z is determined in a least-squares procedure. Where very good agreement is found between experiment and the generalized hydrodynamic model, the computations in the framework of classical hydrodynamics strongly deviate. Only in the hydrodynamic regime both models are shown to converge.

Designing sub-10-nm Metal-Oxide-Semiconductor Field-Effect Transistors via Ballistic Transport and Disparate Effective Mass: The Case of Two-Dimensional BiN

In the post-Moore era, improving energy efficiency is an urgent requirement for microelectronics moving towards the Internet of Things, artificial intelligence, and 5G. In particular, two-dimensional (2D) materials with natural passivation, gate electrostatics, and high mobility have attracted significant attention for integrated circuits in the race towards next-generation field-effect transistors (FETs). Here, by coupling first-principles and nonequilibrium-Green's-function approaches, we obtain a physical understanding of the ballistic transport properties of a V-V binary bismuth nitride ($\mathrm{Bi}\mathrm{N}$) material. Promisingly, monolayer $\mathrm{Bi}\mathrm{N}$ has sharp conduction-band and flat valence-band edges, which exhibit disparate effective masses. Simulated sub-10-nm monolayer $\mathrm{Bi}\mathrm{N}$ transistors show potential device performance and fulfill the high-performance and low-power requirements of the goals of the International Technology Roadmap for Semiconductors 2028 with their optimal parameters. Furthermore, by comprehensively analyzing the effective mass, density of states, on-state current, subthreshold swing, etc., we show that materials whose band dispersions have an extreme character have advantages for transistors. Also, benchmarking of the energy-delay product confirms that $\mathrm{Bi}\mathrm{N}$ FETs possess sufficient competitiveness against other 2D FETs. We believe that this could be a guide for designing potential channel materials for next-generation FETs.

On the optimization of dissipative chain events

A chain event consists of a succession of similar events leading to a cumulative and, at times, dramatic and unexpected effect. In the present work, we consider two examples from undergraduate physics. The first is from mechanics, and it concerns one-dimensional collisions leading to efficient energy transfer between disparate masses. The second from optics deals with the rotation of the plane of polarization of light by a succession of suitably rotated polarizers. In each example, we examine the role of dissipation and arrive at an optimized arrangement for maximum energy/intensity transmission. Our selection of examples is deliberate, and it is to suggest that we may seek out many examples from undergraduate physics. This topic, namely, the cumulative (and at times dramatic) effect of a sequence of near similar events, is often not discussed in textbooks. Its consideration may make the subject matter livelier as well as educate students about the role of optimization at an early stage in their careers.

Influence of the first-order contributions to the partial temperatures on transport properties in polydisperse dense granular mixtures.

The Chapman-Enskog solution to the Enskog kinetic equation of polydisperse granular mixtures is revisited to determine the first-order contributions ϖ_{i} to the partial temperatures. As expected, these quantities (which were neglected in previous attempts) are given in terms of the solution to a set of coupled integrodifferential equations analogous to those for elastic collisions. The solubility condition for this set of equations is confirmed and the coefficients ϖ_{i} are calculated by using the leading terms in a Sonine polynomial expansion. These coefficients are given as explicit functions of the sizes, masses, composition, density, and coefficients of restitution of the mixture. Within the context of small gradients, the results apply for arbitrary degrees of inelasticity and are not restricted to specific values of the parameters of the mixture. In the case of elastic collisions, previous expressions of ϖ_{i} for ordinary binary mixtures are recovered. Finally, the impact of the first-order coefficients ϖ_{i} on the bulk viscosity η_{b} and on the first-order contribution ζ^{(1)} to the cooling rate is assessed. It is shown that the effect of ϖ_{i} on η_{b} and ζ^{(1)} is not negligible, specially for disparate mass ratios and strong inelasticity.

Acoustic trapping of sperm cells from mock sexual assault samples

We report the successful separation of sperm cells from a relevant composition of mock sexual assault samples using a novel acoustic differential extraction (ADE) technology. A multi-layer microfluidic device fabricated in a non-photolithographic process from glass and polydimethylsiloxane (PDMS) was capable of interfacing with custom-built instrumentation to exploit a standing acoustic wave for the trapping of individual sperm cells in a sample containing an abundance of epithelial cells. Samples were generated from buccal and vaginal swabs to mimic post-coital vaginal swabs, and processed through the ADE system followed by DNA extraction of the captured cells with amplification of DNA using a custom short tandem repeat (STR) chemistry. The prototype acoustic trapping technology was fully capable of isolating intact sperm cells from mock samples with disparate masses of male and female DNA. Other biological components were evaluated for adverse effects on sperm cell trapping, including blood, yeast, and bacteria (E. coli), and these had negligible effects on observed sperm cell trapping. Finally, we demonstrate the successful capture of sperm cells from mock samples containing a 40-fold excess in female epithelial cells over sperm cells. The effectiveness of sperm cell purification was ascertained with polymerase chain reaction (PCR) amplification of STR loci from the male fraction post separation with an 18-plex amplification kit, which resulted in male-only profiles.

Frontogenesis and the Creation of Fine‐Scale Vertical Phytoplankton Structure

AbstractFine‐scale spatial structuring of phytoplankton patches has significant consequences for the marine food web, from altering phytoplankton exposure to surface light and limiting nutrients, to influencing the foraging of zooplankton, modifying carbon export, and impacting patterns of diversity. Hence, it is important to identify these fine‐scale features and determine what generates their variability. Here we present evidence of fine‐scale, tilted, interleaved layers in salinity and chlorophyll‐a fluorescence observed in free‐fall Moving Vessel Profiler surveys across a frontal system west of Point Conception, California. The observed covariability of hydrographic and biological properties allows for decomposition of the features into different water histories. Our analyses suggest that recently upwelled coastal water subsequently advected and intermingled with surrounding water masses from farther offshore. Orientations of the fine layers found in the filament are consistent with restratification and downwelling due to an ageostrophic secondary circulation brought on by frontogenesis. Finite size Lyapunov exponents, a Lagrangian diagnostic calculated from remote sensing data, provide positive evidence for frontogenetic convergence occurring upstream of the feature and allow for direct comparisons with in situ data to gauge their general utility in defining dynamical boundaries. These results highlight how frontal systems not only horizontally compress the biological niches represented by formerly disparate water masses but also create vertical structure and patchiness that can rapidly change over submesoscales.

Slow thermal equilibration in methylammonium lead iodide revealed by transient mid-infrared spectroscopy

Hybrid organic–inorganic perovskites are emerging semiconductors for cheap and efficient photovoltaics and light-emitting devices. Different from conventional inorganic semiconductors, hybrid perovskites consist of coexisting organic and inorganic sub-lattices, which present disparate atomic masses and bond strengths. The nanoscopic interpenetration of these disparate components, which lack strong electronic and vibrational coupling, presents fundamental challenges to the understanding of charge and heat dissipation. Here we study phonon population and equilibration processes in methylammonium lead iodide (MAPbI3) by transiently probing the vibrational modes of the organic sub-lattice following above-bandgap optical excitation. We observe inter-sub-lattice thermal equilibration on timescales ranging from hundreds of picoseconds to a couple of nanoseconds. As supported by a two-temperature model based on first-principles calculations, the slow thermal equilibration is attributable to the sequential phonon populations of the inorganic and organic sub-lattices, respectively. The observed long-lasting thermal non-equilibrium offers insights into thermal transport and heat management of the emergent hybrid material class.