Rapid Growth of Galactic Supermassive Black Holes through Accreting Giant Molecular Clouds during Major Mergers of their Host Galaxies

Understanding the formation of the supermassive black holes (SMBHs) present in the centers of galaxies is a crucial topic in modern astrophysics. Observations have detected the SMBHs with mass $M$ of $10^{9}\, \rm M_\odot$ in the high-redshift galaxies with $\rm z\sim7$. However, how SMBHs grew to such huge masses within the first billion years after the big bang remains elusive. One possible explanation is that SMBHs grow quickly through the frequent mergers of galaxies, which provides sustainable gas to maintain rapid growth. This study presents the hydrodynamics simulations of the SMBHs' growth with their host galaxies using the GIZMO code. In contrast to previous simulations, we have developed a giant molecular cloud (GMC) model by separating molecular-gas particles from the atomic-gas particles and then evolving them independently. During major mergers, we show that the more massive molecular gas particles cloud bear stronger dynamical friction. Consequently, GMCs are substantially accreted onto the galactic centers that grow SMBHs from $\sim 10^{7}$ $\rm M_\odot$ to $\sim 10^{9}\, \rm M_\odot$ within $300$ Myr, explaining the rapid growth of SMBHs, and this accretion also triggers a violent starburst at the galactic center. Furthermore, we examine the impact of minor mergers on the bulge of a Milky-Way-like galaxy and find that the size and mass of the bulge can increase from $0.92$ kpc to $1.9$ kpc and from $4.7\times 10^{10}\, \rm M_\odot$ to $7\times 10^{10}\, \rm M_\odot$.Comment: 17 pages, 9 figures. Accepted for publication in Ap

Ultrafast Electron Tunneling Devices—from Electric-field driven to Optical-field driven

The search for ever higher frequency information processing has become an area of intense research activity within the micro, nano, and optoelectronics communities. Compared to conventional semiconductor-based diffusive transport electron devices, electron tunneling devices provide significantly faster response times due to near-instantaneous tunneling that occurs at sub-femtosecond timescales. As a result, the enhanced performance of electron tunneling devices is demonstrated, time and again, to reimagine a wide variety of traditional electronic devices with a variety of new “lightwave electronics” emerging, each capable of reducing the electron transport channel transit time down to attosecond timescales. In response to unprecedented rapid progress within this field, here the current state-of-the-art in electron tunneling devices is reviewed, current challenges and opportunities are highlighted, and possible future research directions are identified.<br/

EFFECTS OF PLYOMTRIC TRAIN lNG ON MUSCLE FATIGUE AND MAXIMAL RATE OF FORCE DEVELOPMENT OF LOWER-LIMB

The purpose of this study was to examine the effects of ploymetric training on muscle fatigue and maximal rate of force development in volleyball players. Ten college volleyball players volunteered to participate in this study and underwent a 6-week plyometric training. The BTS free EMG and force-plate were used to evaluate the median frequency (MDF) of the rectus femoris (RF), anterior tibialis (AT), lateral gastrocnemius (LG), biceps femoris (BF) and maximum rate of force development (mRFD). The results revealed that the plyometric training significantly improves the MDF of RF and AT and mRFD. This study demonstrated hat by using plyometric training could facilitate the mRFD and postpone muscle fatigue for trained volleyball players

THE ACUTE EFFECT OF WHOLE BODY VIBRATION TRAINING ON AGILITY, SPEED AND POWER IN MALE VOLLEYBALL PLAYERS

The purpose of this study was to examine the acute effect of whole body vibration training on agility, speed and power in male volleyball players. Ten college volleyball players volunteered to participate in this study. The vibration training (VT) consisted of 60% with 28 Hz frequencies and 1Omm amplitudes. Counter movement jump (CMJ), blocking agility test (BAT), agility test (AT) and 10 meters sprinting (1 OMS) were performed at pre-test and post-test (60s rest). The peak force (PF). mean force (MF), maximum rate of force development (mRFD) and relative net impulse (RNI) from the CMJs were computed. A repeated measures ANOVA was applied to obtain the variables. The present study indicated that the WBV significantly improves the MF, mRFD and BAT parameters of CMJ and BAT performances excluding the PF. Speed and agility does not seem to be enhanced by VT