High-β_{θe} (a ratio of the electron thermal pressure to the poloidal magnetic pressure) steady-state long-pulse plasmas with steep central electron temperature gradient are achieved in the ...Experimental Advanced Superconducting Tokamak. An intrinsic current is observed to be modulated by turbulence driven by the electron temperature gradient. This turbulent current is generated in the countercurrent direction and can reach a maximum ratio of 25% of the bootstrap current. Gyrokinetic simulations and experimental observations indicate that the turbulence is the electron temperature gradient mode (ETG). The dominant mechanism for the turbulent current generation is due to the divergence of ETG-driven residual flux of current. Good agreement has been found between experiments and theory for the critical value of the electron temperature gradient triggering ETG and for the level of the turbulent current. The maximum values of turbulent current and electron temperature gradient lead to the destabilization of an m/n=1/1 kink mode, which by counteraction reduces the turbulence level (m and n are the poloidal and toroidal mode number, respectively). These observations suggest that the self-regulation system including turbulence, turbulent current, and kink mode is a contributing mechanism for sustaining the steady-state long-pulse high-β_{θe} regime.
Abstract
We present the discovery and timing results of four pulsars discovered in a pilot survey at intermediate Galactic latitudes with the Five-hundred Aperture Spherical Telescope (FAST). Among ...these pulsars, two belong to the category of millisecond pulsars (MSPs) with spin periods of less than 20 ms. The other two fall under the classification of “mildly recycled” pulsars, with massive white dwarfs as companions. Remarkably, this small survey, covering an area of 4.7 deg
2
, led to the discovery of four recycled pulsars. Such success underscores the immense potential of future surveys at intermediate Galactic latitudes. In order to assess the potential yield of MSPs, we conducted population simulations and found that both FAST and Parkes new phased array feed surveys, focusing on intermediate Galactic latitudes, have the capacity to uncover several hundred new MSPs.
The type VI secretion system (T6SS) is a lethal weapon used by many bacteria to kill eukaryotic predators or prokaryotic competitors. Killing by the T6SS results from repetitive delivery of toxic ...effectors. Despite their importance in dictating bacterial fitness, systematic prediction of T6SS effectors remains challenging due to high effector diversity and the absence of a conserved signature sequence. Here, we report a class of T6SS effector chaperone (TEC) proteins that are required for effector delivery through binding to VgrG and effector proteins. The TEC proteins share a highly conserved domain (DUF4123) and are genetically encoded upstream of their cognate effector genes. Using the conserved TEC domain sequence, we identified a large family of TEC genes coupled to putative T6SS effectors in Gram-negative bacteria. We validated this approach by verifying a predicted effector TseC in Aeromonas hydrophila . We show that TseC is a T6SS-secreted antibacterial effector and that the downstream gene tsiC encodes the cognate immunity protein. Further, we demonstrate that TseC secretion requires its cognate TEC protein and an associated VgrG protein. Distinct from previous effector-dependent bioinformatic analyses, our approach using the conserved TEC domain will facilitate the discovery and functional characterization of new T6SS effectors in Gram-negative bacteria.
How different microbial species compete for specific niches is not fully understood. Here, we focus on the type VI secretion system (T6SS), a specialized protein delivery system, which many Gram-negative bacteria use to kill eukaryotic and prokaryotic competitors by translocating toxic protein molecules to target cells. Identification of effectors is required for understanding the pivotal role that the T6SS plays in dictating interbacterial and bacterialâhost dynamics. In this study, we describe a new approach to systematically identify T6SS effectors. We also demonstrate that secretion of effectors requires interaction with a set of cognate effector-binding chaperone proteins that we define in this study, providing important insights for understanding the mechanism of T6SS effector delivery.
Abstract
Ultrafast control of material physical properties represents a rapidly developing field in condensed matter physics. Yet, accessing the long-lived photoinduced electronic states is still in ...its early stages, especially with respect to an insulator to metal phase transition. Here, by combining transport measurement with ultrashort photoexcitation and coherent phonon spectroscopy, we report on photoinduced multistage phase transitions in Ta
2
NiSe
5
. Upon excitation by weak pulse intensity, the system is triggered to a short-lived state accompanied by a structural change. Further increasing the excitation intensity beyond a threshold, a photoinduced steady new state is achieved where the resistivity drops by more than four orders at temperature 50 K. This new state is thermally stable up to at least 350 K and exhibits a lattice structure different from any of the thermally accessible equilibrium states. Transmission electron microscopy reveals an in-chain Ta atom displacement in the photoinduced new structure phase. We also found that nano-sheet samples with the thickness less than the optical penetration depth are required for attaining a complete transition.
Abstract
We present an analysis of both Transiting Exoplanet Survey Satellite (TESS) and Zwicky Transient Facility (ZTF) observations of the eclipsing cataclysmic variable IPHAS J051814.34+294113.2 ...(IPHAS J0518). The TESS light curve shows numerous eclipses superimposed on two outbursts, and ZTF data show frequently outbursts recurring on average every 20.7 days and 12.9 days for long and short outbursts, respectively. This makes IPHAS J0518 to be identified as a possible Z Cam-type dwarf nova. Its quiescent magnitude is ∼16.7 in the
g
band. The orbital period is determined to be 4.95 hr. By combining the observed orbital period with the semiempirical relations of Knigge et al., we estimate the donor mass as
M
2
= 0.48
M
⊙
. The eclipse phase measurements are used to constrain the binary parameters. The orbital inclination is limited in the range of 75.°3 ≤
i
< 81.°7, and the mass ratio is derived as 0.33 <
q
≤ 0.73. Furthermore, we analysis the accretion disk eclipse and find that the total disk eclipse is possible during quiescence, whereas during outburst the disk would be only partially obscured. This indicates that the disk will become larger as the outburst proceeds. We also study the changes of the eclipse depth against the out-of-eclipse flux in IPHAS J0518. The results show evidence of the expansion in the disk size and the variations in the radial-temperature gradient during outburst.
The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a ...dominant GAM, and m/n=6/2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m/n=6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n=6/2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. Such nonlinear synchronization may also contribute to low-frequency zonal flow formation, reduction of turbulence level, and thus confinement regime transitions.
Objective
To investigate the clinical outcome and endocrinological characteristics of progestin‐primed ovarian stimulation (PPOS) using 4 versus 10 mg of medroxyprogesterone acetate (MPA) per day in ...infertile women with normal ovary reserve.
Design
A randomised parallel controlled trial.
Setting
Tertiary‐care academic medical centre.
Participants
A cohort of 300 infertile women undergoing in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) treatment.
Methods
Human menopausal gonadotropin (hMG; 225 iu per day) and MPA (group A, 10 mg per day; group B, 4 mg per day) were started simultaneously from cycle day 3 onwards. Ovulation was co‐triggered by human chorionic gonadotropin (hCG; 1000 iu) and gonadotropin‐releasing hormone agonist (GnRH agonist; 0.1 mg) when dominant follicles matured. Viable embryos were cryopreserved for later frozen embryo transfer (FET) in both groups.
Main outcome measures
The primary outcome measure was the number of oocytes retrieved. Secondary outcomes included the incidence of a premature surge in luteinising hormone (LH), the number of viable embryos, and clinical pregnancy outcomes.
Results
The number of oocytes retrieved and viable embryos were similar between two groups (9.8 ± 6.3 versus 9.6 ± 5.9; 4.2 ± 2.6 versus 3.7 ± 3.0; P > 0.05). No significant difference was found in clinical pregnancy rate (58.0 versus 48.7%) and live birth rate per participant (48.7 versus 42.0%; P > 0.05). No premature LH surge and ovarian hyperstimulation syndrome (OHSS) occurred in either group.
Conclusions
Progestin‐primed ovarian stimulation (PPOS) using 4 or 10 mg of MPA per day was comparable in terms of the number of oocytes retrieved and pregnancy outcome after FET. The administration of 4 mg of MPA per day was sufficient to prevent an untimely LH rise in women undergoing IVF/ICSI treatment.
Tweetable
An RCT confirmed similar pregnancy outcome in P‐primed ovarian stimulation with a daily dose of 4 or 10 mg MPA.
Tweetable
An RCT confirmed similar pregnancy outcome in P‐primed ovarian stimulation with a daily dose of 4 or 10 mg MPA.
We present a timing analysis of the eclipsing post-common envelope binary (PCEB) DE CVn. Based on new CCD photometric observations and published data, we found that the orbital period in DE CVn has a ...cyclic period oscillation with an amplitude of 28.08 s and a period of 11.22 years plus a rapid period decrease at a rate of . According to the evolutionary theory, secular period decreases in PCEBs arise from angular momentum losses (AMLs) driven by gravitational radiation (GR) and magnetic braking (MB). However, the observed orbital decay is too fast to be produced by AMLs via GR and MB, indicating that there could be another AML mechanism. We suggest that a circumbinary disk around DE CVn may be responsible for the additional AML. The disk mass was derived as a few ×10−4-10−3 M , which is in agreement with that inferred from previous studies in the order of magnitude. The cyclic change is most likely the result of the gravitational perturbation by a circumbinary object due to the Applegate's mechanism failing to explain such a large period oscillation. The mass of the potential third body is calculated as . Supposing the circumbinary companion and the eclipsing binary are coplanar, its mass would correspond to a giant planet. This hypothetical giant planet is moving in a circular orbit of a radius of ∼5.75( 2.02) au around its host star.
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two ...types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (Formula: see text 5-10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local Formula: see text shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.
PDF
