Mass Interval Research Articles

Prospects for detecting the couplings of axion-like particle with neutrinos at the CEPC

AbstractWe explore the possibility of detecting the couplings of axion-like particle (ALP) with leptons from their loop-level impact on the ALP couplings to electroweak (EW) gauge bosons via the signal process "Equation missing" at the circular electron positron collider (CEPC) and obtain prospective sensitivities to the ALP-lepton couplings. Our numerical results show that the CEPC with the center of mass energy $$\sqrt{s}=240~(91)$$ s = 240 ( 91 ) GeV and the integrated luminosity $$\mathcal {L}=5.6~(16)$$ L = 5.6 ( 16 ) $$\hbox {ab}^{-1}$$ ab - 1 might be sensitive for probing the ALP-lepton couplings in the ALP mass range from 10 GeV to 130 (50) GeV, where the prospective sensitivities to the ALP-neutrino coupling $$Tr(g_{a\nu \nu })/f_a$$ T r ( g a ν ν ) / f a can be as low as 0.016 (0.012) $$\hbox {GeV}^{-1}$$ GeV - 1 and $$0.0031~(2.8 \times 10^{-4})$$ 0.0031 ( 2.8 × 10 - 4 ) $$\hbox {GeV}^{-1}$$ GeV - 1 for $$c_{R}=0$$ c R = 0 and $$c_{R}=c_{L}$$ c R = c L , and to the ALP-charged lepton coupling $$Tr(g_{a\ell \ell })/f_a$$ T r ( g a ℓ ℓ ) / f a can be as low as 0.035 (0.07) $$\hbox {GeV}^{-1}$$ GeV - 1 for $$c_{L}=0$$ c L = 0 . We find that the prospective sensitivities given by the CEPC are not covered by the current and expected exclusion regions in some ALP mass intervals. The CEPC has the potential for exploring the ALP-neutrino couplings via some promising processes induced by the ALP-EW gauge boson couplings in the future.

Search for long-lived particles decaying in the CMS muon detectors in proton-proton collisions at s=13 TeV

A search for long-lived particles (LLPs) decaying in the CMS muon detectors is presented. A data sample of proton-proton collisions at s=13 TeV corresponding to an integrated luminosity of 138 fb−1, recorded at the LHC in 2016–2018, is used. The decays of LLPs are reconstructed as high multiplicity clusters of hits in the muon detectors. In the context of twin Higgs models, the search is sensitive to LLP masses from 0.4 to 55 GeV and a broad range of LLP decay modes, including decays to hadrons, τ leptons, electrons, or photons. No excess of events above the standard model background is observed. The most stringent limits to date from LHC data are set on the branching fraction of the Higgs boson decay to a pair of LLPs with masses below 10 GeV. This search also provides the best limits for various intervals of LLP proper decay length and mass. Finally, this search sets the first limits at the LHC on a dark quantum chromodynamic sector whose particles couple to the Higgs boson through gluon, Higgs boson, photon, vector, and dark-photon portals, and is sensitive to branching fractions of the Higgs boson to dark quarks as low as 2×10−3. © 2024 CERN, for the CMS Collaboration 2024 CERN

A fuzzy rough-interval linear programming model for booster optimization in water distribution systems

In this article, a fuzzy rough-interval linear programming (FRILP) approach is proposed to deal with the uncertainty expressed by the fuzzy rough set in the optimization of booster cost under uncertainty. The FRILP model was applied to two cases to verify its effectiveness in booster optimization under uncertainty. The optimal upper and lower approximation intervals of the injection mass and booster cost in the fuzzy rough set were obtained and the effects of booster number and location were analysed. The results indicated that with an increase in booster number, the injection mass generally decreased, and booster cost decreased or increased. The nodal chlorine concentration also decreased and was distributed uniformly under a scenario with more boosters. Locating the booster far from the source resulted in more uniform chlorine distribution. The results could help managers design booster schemes with consideration of technical and economic factors comprehensively under uncertainty.

No Catch-22 for fuzzy dark matter: testing substructure counts and core sizes via high-resolution cosmological simulations

ABSTRACT Fuzzy dark matter (FDM) has recently emerged as an interesting alternative model to the standard cold dark matter (CDM). In this model, dark matter consists of very light bosonic particles with wave-like behaviour on galactic scales. Using the N-body code ax-gadget, we perform cosmological simulations of FDM that fully model the dynamical effects of the quantum potential throughout cosmic evolution. Through the combined analysis of FDM volume and high-resolution zoom-in simulations of different FDM particle masses ($m_{\chi }$$\sim$$10^{-23}\!-\!10^{-21}$ eV c−2), we study how FDM impacts the abundance of substructure and the inner density profiles of dark matter haloes. For the first time, using our FDM volume simulations, we provide a fitting formula for the FDM-to-CDM subhalo abundance ratio as a function of the FDM mass. More importantly, our simulations clearly demonstrate that there exists an extended FDM particle mass interval able to reproduce the observed substructure counts and, at the same time, create substantial cores ($r_{c} \sim 1$ kpc) in the density profile of dwarf galaxies ($\approx 10^{9}\!-\!10^{10}$ M$_{\odot }$), which stands in stark contrast with CDM predictions even with baryonic effects taken into account. The dark matter distribution in the faintest galaxies offers then a clear way to discriminate between FDM and CDM.

Galaxies’ properties in the Fundamental Plane across time

Context. Using the Illustris-1 and IllustrisTNG-100 simulations, we investigate the properties of the Fundamental Plane (FP), which is the correlation between the effective radius Re, the effective surface intensity Ie, and the central stellar velocity dispersion σ of galaxies, at different cosmic epochs. Aims. Our aim is to study the properties of galaxies in the FP and its projections across time, adopting samples covering different intervals of mass. We would like to demonstrate that the position of a galaxy in the FP space strongly depends on its degree of evolution, which might be represented by the β and $ L^\prime_0 $ parameters entering the L = $ L^\prime_0 $ (t)σβ(t) law. Methods. Starting from the comparison of the basic relations among the structural parameters of artificial and real galaxies at low redshift, we obtain the fit of the FP and its coefficients at different cosmic epochs for samples of different mass limits. Then, we analyze the dependence of the galaxy position in the FP space as a function of the β parameter and the star formation rate (SFR). Results. We find that: (1) the coefficients of the FP change with the mass range of the galaxy sample; (2) the low luminous and less massive galaxies do not share the same FP of the bright massive galaxies; (3) the scatter around the fitted FP is quite small at any epoch and increases when the mass interval increases; (4) the distribution of galaxies in the FP space strongly depends on the β values (i.e., on the degree of virialization and the star formation rate). Conclusions. The FP is a complex surface that is well approximated by a plane only when galaxies share similar masses and condition of virialization.

Influence of loading on the heat transfer rate and specific water consumption of detached loosed fresh palm fruits during vertical mini-batch sterilization

This study presents the effect of loading on the heat transfer rate and specific water consumption of detached loosed fresh palm fruits during sterilization. Sterilization is an integral process of palm oil extraction that consumes a lot of water. However, most industrial research in the past focused on fresh fruit bunch (FFB) sterilization dynamics. At the same time, the medium- and small-scale industries sterilize already detached loosed fresh palm fruits (LFPF) that have been removed from the spikelet as purchased from aggregators. Therefore, the process data generated from the sterilization of FFB might not be optimal for sterilizing LFPF. This study, therefore, investigates the transient response of variation in LFPF loading of the sterilization chamber to steam injection during steam sterilization of LFPF at 3 ± 0.5 bars using a vertical, single-peak LFPF sterilizer that combines the boiler and sterilizer in a single unit. The LFPF were loaded at mass intervals of 0.2 kg ranging from 0.2 kg to 2 kg. The vapour temperature dynamics, heat transfer rate, steam energy utilization efficiency and specific water consumption parameters were studied. The average vapour temperature varied from 100 °C to 130 °C for the LFPF mass range of 0.2 to 2 kg at steam injection temperature of 140 °C and pressure of 3 ± 0.5 bars. This temperature range matched the saturated vapour temperature of pure water at 1.0––2.8 bars absolute pressure but slightly lower than the saturated vapour temperature of 133.54 °C for pure steam at 3 bars. The percentage of steam energy utilization effectiveness is inversely related to the steam mass flow rate. While energy effectiveness increased with loading mass, the steam mass flow rate decreased with increased LFPF mass. The value of the heat transfer rate ranged between 1.7––55.4 W, while the specific heat transfer rate ranged between 8.5–––41.8 W/kg. The average specific water consumption ranged from 0.014 to 0.09 kg-water/kg-LFPF, with an average value of 0.031 kg-water/kg-LFPF. This value is lower than 0.112–––0.5 kg-water/kg-FFB, with an average value of 0.256 kg-water/kg-FFB for conventional FFB steam sterilization. This represents an 87.9 % reduction in water consumption in conventional FFB steam sterilization. An empirical model deduced for specific heat transfer rate and water consumption for steam sterilization of LFPF at 3 ± 0.5 bars and vapour temperature range of 100––130 °C showed a high coefficient of determination above 99 %.

Detecting the coupling of axion-like particles with fermions at the ILC

New pseudoscalars, axion-like particles (ALPs), provide the exciting target for present and future collider-based experiments. Search for ALPs is performed in this paper via the W+W− fusion process e−e+→νeνe‾a→νeνe‾ff‾ at the 1 TeV ILC corresponding to an integrated luminosity of 1 ab−1 and the beam polarization P(e−, e+)=(−80%, +20%). Owing to the good capability of the ILC in performing b-tagging and the sufficiently large branching ratio of the ALP decaying into a pair of b quarks, the decay channel a→bb‾ is mainly concerned. The prospective sensitivities provided by the ILC on the ALP-fermion coupling as low as 1 TeV−1 and 1.75 TeV−1 are derived at 95% confidence level in the ALP mass intervals 37−50 GeV and 52−300 GeV, respectively. Our results will help to probe significant parameter space in an unexplored region beyond the existing constraints.

Measurement of the Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} Differential Branching Fraction.

The branching fraction of the rare decay Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} is measured for the first time, in the squared dimuon mass intervals q^{2}, excluding the J/ψ and ψ(2S) regions. The data sample analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13TeV, corresponding to a total integrated luminosity of 9 fb^{-1}. The result in the highest q^{2} interval, q^{2}>15.0 GeV^{2}/c^{4}, where theoretical predictions have the smallest model dependence, agrees with the predictions.

Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVIII. The Dark Matter Halo Mass of Quasars at z ∼ 6

We present, for the first time, dark matter halo (DMH) mass measurement of quasars at z ∼ 6 based on a clustering analysis of 107 quasars. Spectroscopically identified quasars are homogeneously extracted from the Hyper Suprime-Cam Strategic Survey Program wide layer over 891 deg2. We evaluate the clustering strength by three different autocorrelation functions: projected correlation function, angular correlation function, and redshift–space correlation function. The DMH mass of quasars at z ∼ 6 is evaluated as with the bias parameter b = 20.8 ± 8.7 by the projected correlation function. The other two estimators agree with these values; though, each uncertainty is large. The DMH mass of quasars is found to be nearly constant ∼1012.5 h −1 M ⊙ throughout cosmic time, suggesting that there is a characteristic DMH mass where quasars are always activated. As a result, quasars appear in the most massive halos at z ∼ 6, but in less extreme halos thereafter. The DMH mass does not appear to exceed the upper limit of 1013 h −1 M ⊙, which suggests that most quasars reside in DMHs with across most of the cosmic time. Our results supporting a significant increasing bias with redshift are consistent with the bias evolution model with inefficient active galactic nucleus feedback at z ∼ 6. The duty cycle (f duty) is estimated as 0.019 ± 0.008 by assuming that DMHs in some mass interval can host a quasar. The average stellar mass is evaluated from stellar-to-halo mass ratio as , which is found to be consistent with [C ii] observational results.

Development of a moving vehicle identification framework using structural vibration response and deep learning algorithms

The accurate identification of vehicle position, velocity, and mass on bridges is crucial in the field of structural health monitoring (SHM). Existing methods for moving vehicle identification primarily rely on staged approaches, which may not adequately address multiple vehicle scenarios. This study is the first to propose a framework that simultaneously considers vehicle velocity, mass, and location as supervised learning problems using structural vibration response. The framework comprises three phases: data generation and preparation, network building and training, and prediction. In Phase 1, a labeling strategy is introduced to convert arbitrary moving vehicle scenarios into a unified, trainable format. Phase 2 presents a novel loss function specifically designed to measure the discrepancy between the network output and the label. Lastly, Phase 3 introduces a data post-processing workflow that converts the network output into moving vehicle information. To demonstrate the effectiveness of the proposed method, the identification accuracy is quantified and analyzed using five different indexes under different vehicle numbers, velocity intervals, and mass intervals. Furthermore, the influences of some key variables, the modeling error and model simplification are discussed in detail. The proposed approach surpasses conventional methods by overcoming staged identification limitations and accommodating multiple vehicles, while efficiently identifying their velocity, mass, and moving range on the bridge without requiring initial conditions.

Measurement of the e+e−→ΛΛ¯ cross section from threshold to 3.00 GeV using events with initial-state radiation

Using initial-state radiation events from a total integrated luminosity of 11.957 fb−1 of e+e− collision data collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at BEPCII, the cross section for the process e+e−→ΛΛ¯ is measured in 16 ΛΛ¯ invariant mass intervals from the production threshold up to 3.00 GeV/c2. The results are consistent with previous results from BABAR and BESIII, but with better precision and with narrower ΛΛ¯ invariant mass intervals than BABAR.1 MoreReceived 15 March 2023Accepted 23 March 2023DOI:https://doi.org/10.1103/PhysRevD.107.072005Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasForm factorsParticle interactionsQuantum chromodynamicsPhysical SystemsBaryonsStrange quarkTechniquesLepton collidersMonte Carlo methodsParticle productionParticles & Fields

An Atlas of Color-selected Quiescent Galaxies at z > 3 in Public JWST Fields

We present the results of a systematic search for candidate quiescent galaxies in the distant universe in 11 JWST fields with publicly available observations collected during the first 3 months of operations and covering an effective sky area of ∼145 arcmin2. We homogeneously reduce the new JWST data and combine them with existing observations from the Hubble Space Telescope. We select a robust sample of ∼80 candidate quiescent and quenching galaxies at 3 < z < 5 using two methods: (1) based on their rest-frame UVJ colors, and (2) a novel quantitative approach based on Gaussian mixture modeling of the near-UV − U, U − V, and V − J rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive (M ⋆ ≥ 1010.6 M ⊙) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of 2–3, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at z > 3, as could be expected for highly clustered massive systems. Importantly, JWST enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available.

Abstract P2-14-06: Prospective, multicenter, clinical validation study of the repeatability and accuracy of internal mammary sentinel lymph node biopsy with modified injection technique (CBCSG026/CBCSG027)

Abstract Background: As a first-echelon nodal drainage site of breast cancer, the status of axillary lymph nodes (ALN) and internal mammary lymph nodes (IMLN) is both valuable for regional staging and treatment choice. The internal mammary sentinel lymph node biopsy (IM-SLNB) may provide minimally invasive staging, and guide individual IMLN radiation. Modified technique (periareolar intraparenchymal, high volume and ultrasound guidance) got a high internal mammary sentinel lymph nodes (IM-SLN) visualization rate of 71.1% in single center, and the prospective multicenter study was designed to verify its repeatability (CBCSG026, NCT03541278). High visualization rate and low false negative rate are prerequisites for the widespread of IM-SLNB. The question arises as to whether IM-SLN detected with the modified technique should be considered as “true” IM-SLN. The prospective, multicenter, clinical validation study of IM-SLNB followed by internal mammary lymph node dissection (IM-LND) was designed to verify the accuracy of IM-SLNB in patients with ALN positive breast cancer (CBCSG027, NCT03024463). Methods: While CBCSG026 trial enrolled patients with both axillary negative and positive breast cancer, CBCSG027 trial only enrolled axillary positive patients receiving mastectomy (either biopsy proving cN+ disease or cN0 with positive axillary SLN). The 1st to 3rd intercostal IM-LND was performed immediately after IM-SLNB to verify its accuracy in the CBCSG027 trial. Result: From May 2018 to June 2022, 600 and 264 patients were enrolled in the CBCSG026 and CBCSG027 trial from seven centers in China, respectively. Among the 600 recruited patients in the CBCSG026, the IM-SLN visualization rate was 65.0% (390/600), which was significantly related to patient’s age, body mass index, radiotracer intensity and interval time between injection and IM-SLN identification (all P&amp;lt; 0.05). The IM-SLNB successful rate was 97.4% (380/390), and the complication was 6.9%. The median number of IM-SLN was 1. The overall IM-SLN metastases rate was 18.9% (72/380), with 33.0% (65/195) and 3.8% (7/185) in ALN positive and negative patients, respectively. Multivariate analysis showed that the tumor size (P=0.028), the tumor location (P&amp;lt; 0.001) and the number of positive ALNs (P&amp;lt; 0.001) were independent predictors of IM-SLN metastasis. Those variables were included in a novel nomogram (Table 1), which was significantly better than the probability based on the number of metastatic ALNs alone according to the current guidelines (area under the curve: 0.860 vs. 0.804, P&amp;lt; 0.001). Of the 264 patients enrolled in the CBCSG027 trial, 185 patients (70.1%) had IM-SLN visualization (included 107 with cN+ disease and 78 with positive axillary SLN). The median number of IM-SLN and IM-nSLN was 2 (1~4) and 3 (1~9), respectively. The positive rate of IMLN and IM-SLN was 37.8% (70/185) and 36.8% (68/185), respectively, yielding the false negative rate of IM-SLNB 2.9% (2/70), the accuracy of 98.9% (183/185) and the sensitivity of 97.1% (68/70). The false negative rate of patients with cN+ disease and patients with positive axillary SLN was 4.8% (2/42) and 0, respectively. The positive IM-SLNs were the only positive IMLNs identified in 51.4% (36/70) patients. IM-SLNB can change the pN stages of 37.2% (68/183) patients. IMLN irradiation could be avoided in 72.7% (80/110) patients with axillary pN1 and 46.7% (35/75) with pN2/N3 disease in the study. Conclusions: The modified technique of radiotracer injection (periareolar intraparenchymal, high volume, and ultrasound guidance) can significantly improve the detection rate of IM-SLN with very low false-negative rate with the prospective, multicenter validation results, providing minimally invasive staging and guiding individual IMLN radiation. When there is no IM-SLN visualization, the nomogram can predict the risk of IMLN metastasis and guide IMLN radiation. The nomogram which can predict the risk of IMLN metastasis The nomogram which can predict the risk of IMLN metastasis Citation Format: Yong-Sheng Wang, Qing Lu, Shi-Guang Zhu, Wen-He Zhao, Guang-Lun Yang, Yuan-Xi Huang, Hong Zhong, Xiao Sun, Pengfei Qiu. Prospective, multicenter, clinical validation study of the repeatability and accuracy of internal mammary sentinel lymph node biopsy with modified injection technique (CBCSG026/CBCSG027) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-14-06.

Difference of the association between low muscle mass and physical inactivity by sex resulting from the choice of the diagnostic criterion for low muscle mass in elderly Koreans.

We investigated the difference in the relationship between physical activity and low muscle mass resulting from the choice of diagnostic criterion for low muscle mass. Our study was cross-sectional, using data from the 2008-2011 National Health and Nutrition Examination Survey. Muscle mass was measured by dual-energy X-ray absorptiometry. Low muscle mass was defined as height-adjusted and weight-adjusted low muscle mass. Odds ratios (ORs) and 95% confidence intervals (CIs) of low muscle mass in relation to physical inactivity were analyzed using multivariate logistic regression analysis. Our study included 3977 older people (1698 men and 2279 women). The prevalence of height-adjusted and weight-adjusted low muscle mass was 4.1% and 11.8%, respectively, in the physically inactive group, and 3.9% and 7.9%, respectively, in the physically active group. The prevalence of weight-adjusted low muscle mass increased by 48% in the physically inactive group in the fully adjusted model (OR, 1.48; 95% CI, 1.13-1.95) and increased by 61% in men and 50% in women (men: OR, 1.61; 95% CI, 1.12-2.31 and women: OR, 1.50; 95% CI, 1.20-2.20) compared with the physically active group. The risk of height-adjusted low muscle mass in men tended to be higher in the physically inactive group than in the physically active group. However, this trend was not observed among women. Physical inactivity was associated with an increased prevalence of low muscle mass in weight-adjusted measures among elderly adults in Korea. Height-adjusted low muscle mass in women is less useful as an indicator of the relationship between low muscle mass and physical inactivity. Geriatr Gerontol Int 2023; 23: 71-77.

The Stellar Mass Function in CANDELS and Frontier Fields: The Buildup of Low-mass Passive Galaxies since z ∼ 3

Despite significant efforts in recent years, the physical processes responsible for the formation of passive galaxies through cosmic time remain unclear. The shape and evolution of the stellar mass function (SMF) give an insight into these mechanisms. Taking advantage of the CANDELS and the deep Hubble Frontier Fields (HFF) programs, we estimated the SMF of total, star-forming, and passive galaxies from z = 0.25 to z = 2.75 to unprecedented depth and we focus on the latter population. The density of passive galaxies underwent a significant evolution over the last 11 Gyr. They account for 60% of the total mass in the nearby universe against ∼20% observed at z ∼ 2.5. The inclusion of the HFF program allows us to detect, for the first time at z > 1.5, the characteristic upturn in the SMF of passive galaxies at low masses, usually associated with environmental quenching. We observe two separate populations of passive galaxies evolving on different timescales: roughly half of the high-mass systems were already quenched at high redshift, while low-mass passive galaxies are gradually building up over the redshift range probed. In the framework of environmental quenching at low masses, we interpret this finding as evidence of an increasing role of the environment in the buildup of passive galaxies as a function of time. Finally, we compared our findings with a set of theoretical predictions. Despite good agreement in some redshift and mass intervals, none of the models are able to fully reproduce the observations. This calls for further investigation into the involved physical mechanisms, both theoretically and observationally, especially with the brand-new JWST data.

Dynamic Analysis and Machine Learning Prediction of a Nonuniform Slot Air Bearing System

Abstract Nonuniform slot air bearing (NSAB) systems have two major advantages, the external air supply and slot restrictor design, and their inherent multidirectional supporting forces and stiffness that provide excellent rotational stability. However, NSAB systems are prone to vibration from nonperiodic or chaotic motion caused by nonlinear pressure distribution within the gas film, gas supply imbalance, or simply inappropriate design. It is necessary to determine under which conditions these nonperiodic motions arise, and to design a NSAB system that will resist these vibrations. The dynamic behavior of a rotor supported by an NSAB system was studied using spectral response, bifurcation, Poincaré map, and the maximum Lyapunov exponent. The numerical results showed that chaos in an NSAB system occurred within specific ranges of rotor mass and bearing number. For example, the chaotic regions where the maximum Lyapunov exponents were greater than zero occurred in the intervals of rotor mass 20.84 ≦ mf &amp;lt; 24.1 kg with a bearing number of Λ = 3.45. In addition, the coupling effect of rotor mass and bearing number was also investigated. To predict chaotic behavior, ensemble regression, and the back propagation neural network were used to forecast the occurrence of chaos. It was found that ensemble regression using dataset of 26 × 121 gave the best results and most accurate prediction for this NSAB system. The results may make a valuable contribution to the design of NSAB systems for use in a wide variety of industrial applications.

Nonradial oscillation of strange stars in d dimensions

The influence of the dimensions on the f and p 1 pulsation modes from strange quark stars, in the Cowling approximation, are investigated. For that purpose, the d-dimensional nonradial pulsation equations (d > 4) are numerically integrated considering that the Schwarzschild-Tangherlini line element describes the spacetime outside the object. We found that the fluid pulsation modes could become larger than those obtained in four dimensions. In four dimensions, the f pulsation mode is nearly constant, and for high total masses, it increases monotonically and quickly with the total mass. In this mass interval, the f frequencies grow for the spacetime dimensions between 4 and 6 and decay for d larger than 7. Concerning the p 1 pulsation modes, we found that they increase with the spacetime dimension and decline with the increment of the total mass.

Numerical Calculation Model and Efficiency Analysis of Distributed-Energy-Store Railgun

In order to study the factors affecting the launch efficiency of the distributed-energy-store (DES) railgun, a numerical calculation model of the DES railgun is established in this article. Taking the six-stage equidistant DES railgun with 4-MJ initial energy storage as an example, the simulation results show that the launch efficiency of DES railgun is 21.14%, and the resistance loss and the residual magnetic energy of rail account for a small proportion of 6.47% and 3.77%, respectively. The resistance loss of power supply and other energy losses (the losses caused by the equivalent resistance produced by the armature and its related physical effects) accounted for the highest proportions, respectively, 23.91% and 37.52%. Therefore, these two parts of losses should be reduced to further improve the system launch efficiency. The influence of system parameters on launch efficiency was analyzed, and the parameters include capacitance, charging voltage, inductance, equivalent internal resistance, rail length, interval of current feed point, armature mass, inductance gradient, and rail height. Among them, inductance gradient has the most significant impression on launch efficiency, followed by equivalent internal resistance, rail length, and interval of current feed point. The conclusions can guide the selection of the feeding mode of the electromagnetic launch system and provide reference to the further optimization of the DES railgun launch system.

Aging of galaxies along the morphological sequence, marked by bulge growth and disk quenching

Aims. We revisit the color bimodality of galaxies using the extensive EFIGI morphological classification of nearby galaxies. Methods. The galaxy profiles from the Sloan Digital Sky Survey (SDSS) gri images were decomposed as a bulge and a disk by controlled profile modeling with the Euclid SourceXtractor++ software. The spectral energy distributions from our resulting gri SDSS photometry complemented with Galaxy Evolution Explorer (GALEX) NUV photometry were fitted with the ZPEG software and PEGASE.2 templates in order to estimate the stellar masses and specific star formation rates (sSFR) of whole galaxies as well as their bulge and disk components. Results. The absolute NUV−r color versus stellar mass diagram shows a continuous relationship between the present sSFR of galaxies and their stellar mass, which spans all morphological types of the Hubble sequence monotonously. Irregular galaxies to intermediate-type Sab spirals make up the “Blue Cloud” across 4 orders of magnitude in stellar mass but a narrow range of sSFR. This mass build-up of spiral galaxies requires major mergers, in agreement with their frequently perturbed isophotes. At high mass, the Blue Cloud leads to the “Green Plain”, dominated by S0a and Sa early-type spirals. It was formerly called the “Green Valley”, due to its low density, but we rename it because of its wide stretch and nearly flat density over ∼2 mag in NUV−r color (hence sSFR), despite a limited range of stellar mass (1 order of magnitude). The Green Plain links up the “Red Sequence”, containing all lenticular and elliptical galaxies with a 2 order of magnitude mass interval, and systematically higher masses for the ellipticals. We confirm that the Green Plain cannot be studied using u − r optical colors because it is overlayed by the Red Sequence, hence NUV data are necessary. Galaxies across the Green Plain undergo a marked growth by a factor 2 to 3 in their bulge-to-total mass ratio and a systematic profile change from pseudo to classical bulges, as well as a significant reddening due to star formation fading in their disks. The Green Plain is also characterized by a maximum stellar mass of 1011.7 M⊙ beyond which only elliptical galaxies exist, hence supporting the scenario of ellipticals partly forming by major mergers of massive disk galaxies. Conclusions. The EFIGI attributes indicate that dynamical processes (spiral arms and isophote distortions) contribute to the scatter of the Main Sequence of star-forming galaxies (Blue Cloud), via the enhancement of star formation (flocculence, HII regions). The significant bulge growth across the Green Plain confirms that it is a transition region, and excludes a predominantly quick transit due to rapid quenching. The high frequency of bars for all spirals as well as the stronger spiral arms and flocculence in the knee of the Green Plain suggest that internal dynamics, likely triggered by flybys or (mainly minor) mergers, may be the key to the bulge growth of massive disk galaxies, which is a marker of the aging of galaxies from star forming to quiescence. The Hubble sequence can then be considered as an inverse sequence of galaxy physical evolution.

Chemical Tracing and the Origin of Carbon in the Galactic Disk

A basic problem in studies of the evolution of chemical elements in galaxies is the uncertainties in the yields of elements produced by different types of stars. The possibilities of tracing the sites producing chemical elements and corresponding yields in stellar populations by studying ratios of abundances in stars of different ages and metallicities, with an approach with minimal assumptions concerning the yields, is explored by means of simple models of Galactic chemical evolution. Elemental abundances of carbon and oxygen, obtained by recent observations of samples of solar-type stars with estimated ages in the thin disk of the Galaxy, are analysed. Constraints on the yields from winds of intermediate-mass stars and of hot massive stars, including core-collapse supernovae, are derived. It is found that a dominating contribution of carbon from massive stars is most probable, although stars in the mass interval of two to three solar masses may have provided some amounts of carbon in the Sun. The results are consistent with those obtained by using theoretical yields and more elaborate models of Galactic evolution. The uncertainties as regards the mixing of stellar populations due to migration of stars in the Galactic disk may be important for the conclusions. Variations in the star formation rates, lack of chemical homogeneity in the Galactic gas, the inflow of gas from the intergalactic space and possible variations in the Initial mass function may also limit conclusions about the sites and their yields. Very accurate abundance ratios and the determination of stellar ages provide further important constraints on the yields.