Urban Land Supply, Urban Growth, and Housing Prices in China

Ph.DDOCTOR OF PHILOSOPH

Dynamical Friction and Black Holes in Ultralight Dark Matter Solitons

We numerically simulate the motion of a black hole as it plunges radially through an ultralight dark matter soliton. We investigate the timescale in which dynamical friction reduces the kinetic energy of the black hole to a minimum, and consider the sensitivity of this timescale to changes in the ULDM particle mass, the total soliton mass, and the mass of the black hole. We contrast our numerical results with a semi-analytic treatment of dynamical friction, and find that the latter is poorly suited to this scenario. In particular, we find that the back-reaction of the soliton to the presence of the black hole is significant, resulting in oscillations in the coefficient of dynamical friction which cannot be described in the simple semi-analytical framework. Furthermore, we observe a late-time reheating effect, in which a significant amount of kinetic energy is transferred back to the black hole after an initial damping phase. This complicates the discussion of ULDM dynamical friction on the scales relevant to the final parsec problem.Comment: 15 page

Multifield Ultralight Dark Matter

Ultralight dark matter (ULDM) is usually taken to be a single scalar field. Here we explore the possibility that ULDM consists of $N$ light scalar fields with only gravitational interactions. This configuration is more consistent with the underlying particle physics motivations for these scenarios than a single ultralight field. ULDM halos have a characteristic granular structure that increases stellar velocity dispersion and can be used as observational constraints on ULDM models. In multifield simulations, we find that inside a halo the amplitude of the total density fluctuations decreases as $1/\sqrt{N}$ and that the fields do not become significantly correlated over cosmological timescales. Smoother halos heat stellar orbits less efficiently, reducing the velocity dispersion relative to the single field case and thus weakening the observational constraints on the field mass. Analytically, we show that for $N$ equal-mass fields with mass $m$ the ULDM contribution to the stellar velocity dispersion scales as $1/(N m^3)$. Lighter fields heat the most efficiently and if the smallest mass $m_L$ is significantly below the other field masses the dispersion scales as $1/(N^2 m_L^3)$.Comment: 11 pages, 7 figures, to be submitted to PR

Immunogenicity and therapeutic effects of a Mycobacterium tuberculosis rv2190c DNA vaccine in mice

The Excel data file [FOLT] Figshare, [DOI: 10.6084/m9.figshare.4668148 and https://figshare.com/s/bd46c22986c673579bb6 ] includes all datasets supporting the conclusions of this article: IFN-Îł in spleen lymphocyte culture supernatants, IL-4 in spleen lymphocyte culture supernatants, CD4+ T cell subsets expressing intracellular IFN-Îł or IL-4, CFU in the lungs and spleens.. (XLS 143 kb

Downregulation of Brassica napus MYB69 (BnMYB69) increases biomass growth and disease susceptibility via remodeling phytohormone, chlorophyll, shikimate and lignin levels

MYB transcription factors are major actors regulating plant development and adaptability. Brassica napus is a staple oil crop and is hampered by lodging and diseases. Here, four B. napus MYB69 (BnMYB69s) genes were cloned and functionally characterized. They were dominantly expressed in stems during lignification. BnMYB69 RNA interference (BnMYB69i) plants showed considerable changes in morphology, anatomy, metabolism and gene expression. Stem diameter, leaves, roots and total biomass were distinctly larger, but plant height was significantly reduced. Contents of lignin, cellulose and protopectin in stems were significantly reduced, accompanied with decrease in bending resistance and Sclerotinia sclerotiorum resistance. Anatomical detection observed perturbation in vascular and fiber differentiation in stems, but promotion in parenchyma growth, accompanied with changes in cell size and cell number. In shoots, contents of IAA, shikimates and proanthocyanidin were reduced, while contents of ABA, BL and leaf chlorophyll were increased. qRT-PCR revealed changes in multiple pathways of primary and secondary metabolisms. IAA treatment could recover many phenotypes and metabolisms of BnMYB69i plants. However, roots showed trends opposite to shoots in most cases, and BnMYB69i phenotypes were light-sensitive. Conclusively, BnMYB69s might be light-regulated positive regulators of shikimates-related metabolisms, and exert profound influences on various internal and external plant traits

Exploring the role of the CapG gene in hypoxia adaptation in Tibetan pigs

Introduction: The CapG gene, which is an actin-binding protein, is prevalent in eukaryotic cells and is abundantly present in various pathways associated with plateau hypoxia adaptation. Tibetan pigs, which have inhabited high altitudes for extended periods, provide an excellent research population for investigating plateau hypoxia adaptation.Results: This study focused on Tibetan pigs and Yorkshire pigs residing in Nyingchi, Tibet. The blood physiological data of Tibetan pigs were found to be significantly higher than those of Yorkshire pigs, including RBC, HGB, HCT, MCH, and MCHC. The SNP analysis of the CapG gene identified six sites with mutations only present in Tibetan pigs. Notably, the transcription factors at sites C-489T, C-274T, and A-212G were found to be altered, and these sites are known to be associated with hypoxia adaptation and blood oxygen transportation. The mRNA expression of the CapG gene exhibited highly significant differences in several tissues, with the target proteins predominantly higher in the Yorkshire pig compared to the Tibetan pig. Specifically, a notable difference was observed in the lung tissues. Immunohistochemistry analysis revealed high expression levels of CapG proteins in the lung tissues of both Tibetan and Yorkshire pigs, primarily localized in the cytoplasm and cell membrane.Conclusion: The CapG gene plays a significant role in regulating hypoxia adaptation in Tibetan pigs. This study provides a theoretical basis for the conservation and utilization of Tibetan pig resources, the breeding of highland breeds, epidemic prevention and control, and holds great importance for the development of the highland livestock economy

Nonlinear modeling and transition corridor calculation of a tiltrotor without cyclic pitch

In order to solve the problem of rotor airflow interference to the wing of tiltrotor UAV, the lift and drag in the slipstream area and the free flow area were calculated respectively according to the hydrodynamics theory and CFD simulation. The longitudinal nonlinear dynamics model of tiltrotor UAV is established by Newton-Euler method. In order to solve the problem that the lift and thrust are difficult to balance the body gravity in the transition flight mode, a method for calculating the transition corridor of a tiltrotor UAV without cyclic pitch is proposed. The boundary of the transition corridor is restricted by the Angle of attack of the wing and the thrust of the rotor. Considering the requirements of UAV cruise speed, flight safety and minimum energy consumption, the optimal transition curve is selected. The result show that the designed transition curve can ensure that the lift and the rotor thrust can balance the gravity completely and the Angle of attack is in a reasonable range, and the rotor force has enough margin of safety