3,982 research outputs found
Beam Management for Millimeter Wave Beamspace MU-MIMO Systems
Millimeter wave (mmWave) communication has attracted increasing attention as
a promising technology for 5G networks. One of the key architectural features
of mmWave is the use of massive antenna arrays at both the transmitter and the
receiver sides. Therefore, by employing directional beamforming (BF), both
mmWave base stations (MBSs) and mmWave users (MUEs) are capable of supporting
multi-beam simultaneous transmissions. However, most researches have only
considered a single beam, which means that they do not make full potential of
mmWave. In this context, in order to improve the performance of short-range
indoor mmWave networks with multiple reflections, we investigate the challenges
and potential solutions of downlink multi-user multi-beam transmission, which
can be described as a high-dimensional (i.e., beamspace) multi-user
multiple-input multiple-output (MU-MIMO) technique, including multi-user BF
training, simultaneous users' grouping, and multi-user multibeam power
allocation. Furthermore, we present the theoretical and numerical results to
demonstrate that beamspace MU-MIMO compared with single beam transmission can
largely improve the rate performance of mmWave systems.Comment: The sixth IEEE/CIC International Conference on Communications in
China (ICCC2017
Study on fault mechanism of shaft hoist steelwork
AbstractSome achievements have been made in detecting the vibration faults in shaft hoist steelwork, but very little information is currently available to help study the faults mechanism. The faults during the run-ups stage are different from the faults during even speed stage. This paper deals with the fault mechanism through establishing the vibration model as the conveyance moves in shaft. By simulation we can see different vibrating instances correspond to different steelwork faults, and then we put forward suitable fault diagnosis methods
(4-CarbÂoxy-2-sulfonatoÂbenzoato-Îş2 O 1,O 2)bisÂ(1,10-phenanthroline-Îş2 N,N′)manganese(II)
In the title complex, [Mn(C8H4O7S)(C12H8N2)2], the MnII atom is chelated by one 4-carbÂoxy-2-sulfonatoÂbenzoate anion and two phenathroline (phen) ligands in a distorted octaÂhedral MnN4O2 geometry. The benzene ring of the 4-carbÂoxy-2-sulfonatoÂbenzoate anion is twisted with respect to the two phen ring systems at dihedral angles of 66.38 (9) and 53.56 (9)°. In the crystal, interÂmolecular O—Hâ‹ŻO and C—Hâ‹ŻO hydrogen bonding links the molÂecules into chains running parallel to [100]. InterÂmolecular π–π stacking is also observed between parallel phen ring systems, the face-to-face distance being 3.432 (6) Å
Chk1/2 inhibitor AZD7762 blocks the growth of preantral follicles by inducing apoptosis, suppressing proliferation, and interfering with the cell cycle in granulosa cells
Background. Checkpoint kinases 1/2
(Chk1/2) have an important role in somatic cell
development and oocyte meiotic maturation. However,
the role of Chk1/2 in folliculogenesis has not been fully
elucidated. The aim of this study was to assess the
effects of Chk1/2 inhibition on ovarian folliculogenesis
and granulosa cell development in mice.
Methods. Preantral follicles (100-120 ÎĽm) and
granulosa cells from pre-ovulatory follicles (pre-GCs) of
mice were isolated and cultured with or without Chk1/2
inhibitor AZD7762. Preantral follicles were cultured for
96h. Then, follicle morphology and follicular growth
were assessed every 48h. Granulosa cells were cultured
for 48h with or without AZD7762, after which cell
apoptosis, cell proliferation, and cell cycle analysis were
assessed; meanwhile, the mRNA expression of PCNA
and Bax were measured by real-time RT-PCR, and
PCNA and Bax protein were measured by Western blot.
Results. Compared with control follicles, AZD7762
inhibited growth of preantral follicles (P<0.05).
Furthermore, inhibition of Chk1/2 significantly induced
apoptosis (P<0.05) and inhibited the proliferation of
granulosa cells (P<0.01), arrested cell cycle at S and
G2/M phases, and decreased G1 phase fraction
(P<0.001). Also, the expression of PCNA mRNA and
protein were reduced (P<0.01), while Bax mRNA and
protein were increased (P<0.05) post AZD7762
treatment in granulosa cells.
Conclusions. This study revealed that Chk1 and
Chk2 have a crucial role during preantral follicular
development by regulating the proliferation and
apoptosis of granulosa cells
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