Non-linear magnetic buoyancy instability and turbulent dynamo

\ua9 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Stratified discs with strong horizontal magnetic fields, are susceptible to magnetic buoyancy instability (MBI). Modifying the magnetic field and gas distributions, this can play an important role in galactic evolution. The MBI and the Parker instability, in which MBI is exacerbated by cosmic rays, are often studied using an imposed magnetic field. However, in galaxies and accretion discs, the magnetic field is continuously replenished by a large-scale dynamo action. Using non-ideal MHD equations, we model a section of the galactic disc (we neglect rotation and cosmic rays considered elsewhere), in which the large-scale field is generated by an imposed α-effect of variable intensity to explore the interplay between dynamo instability and MBI. The system evolves through three distinct phases: the linear (kinematic) dynamo stage, the onset of linear MBI when the magnetic field becomes sufficiently strong and the non-linear, statistically steady state. Non-linear effects associated with the MBI introduce oscillations which do not occur when the field is produced by the dynamo alone. The MBI initially accelerates the magnetic field amplification but the growth is quenched by the vertical motions produced by MBI. We construct a 1D model, which replicates all significant features of 3D simulations to confirm that magnetic buoyancy alone can quench the dynamo and is responsible for the magnetic field oscillations. Unlike similar results obtained with an imposed magnetic field, the non-linear interactions do not reduce the gas scale height, so the consequences of the magnetic buoyancy depend on how the magnetic field is maintained

Effect of Modified Atmosphere Packaging on Maintenance of Quality in Apple

An experiment was conducted to study the effect of modified atmosphere packaging (MAP) on the quality of 'Red Delicious' and 'Golden Delicious' apples. Freshly harvested fruits were wiped clean and (25 μm thick) with varying number of perforations and stored in cardboard boxes at ambient temperature. 'Golden Delicious' showed higher incidence of bitter pit as compared to 'Red Delicious' apples. MAP proved effective in controlling the bitter pit disorder and in maintenance of quality. The least incidence of bitter pit in 'Golden Delicious' was recorded with T4 (30 x 2 mm perforation) and T3 (20 x 2 mm) treatment in 'Red Delicious' apples. However, MAP retained more freshness in 'Golden Delicious' than in 'Red Delicious'

On Physical Vapor Deposition of Organic Semiconductor CuPc Thin Films in High Gravity

Thin organic films of p-type semiconductor copper phthalocyanine (CuPc, C32H16N8Cu) deposited by vacuum evaporation on glass substrates at different gravity conditions, from 50 g to –50 g (g – denotes the terrestrial gravity acceleration) in a centrifugal machine, were investigated. Thickness distribution of the film deposited was determined by measurement of absorbance using a scanning light beam probe. An anisotropic distribution of the film was observed in the direction of source and substrate rotation. The anisotropy is associated with centrifugal motion of the source-substrate system. In a direction perpendicular to the rotation, the deposition distribution was isotropic and obeyed, in principle, the theoretical approach which requires a maximum deposition in the centre of the sample. The experimentally observed influence of the acceleration on the deposition rate of the CuPc films on the substrate was simulated

Drosophila Sperm Swim Backwards in the Female Reproductive Tract and Are Activated via TRPP2 Ion Channels

Sperm have but one purpose, to fertilize an egg. In various species including Drosophila melanogaster female sperm storage is a necessary step in the reproductive process. Amo is a homolog of the human transient receptor potential channel TRPP2 (also known as PKD2), which is mutated in autosomal dominant polycystic kidney disease. In flies Amo is required for sperm storage. Drosophila males with Amo mutations produce motile sperm that are transferred to the uterus but they do not reach the female storage organs. Therefore Amo appears to be a mediator of directed sperm motility in the female reproductive tract but the underlying mechanism is unknown.Amo exhibits a unique expression pattern during spermatogenesis. In spermatocytes, Amo is restricted to the endoplasmic reticulum (ER) whereas in mature sperm, Amo clusters at the distal tip of the sperm tail. Here we show that flagellar localization of Amo is required for sperm storage. This raised the question of how Amo at the rear end of sperm regulates forward movement into the storage organs. In order to address this question, we used in vivo imaging of dual labelled sperm to demonstrate that Drosophila sperm navigate backwards in the female reproductive tract. In addition, we show that sperm exhibit hyperactivation upon transfer to the uterus. Amo mutant sperm remain capable of reverse motility but fail to display hyperactivation and directed movement, suggesting that these functions are required for sperm storage in flies.Amo is part of a signalling complex at the leading edge of the sperm tail that modulates flagellar beating and that guides a backwards path into the storage organs. Our data support an evolutionarily conserved role for TRPP2 channels in cilia

Facile green synthesis of magnesium oxide nanoparticles using tea (Camellia sinensis) extract for efficient photocatalytic degradation of methylene blue dye

Herein, we report, for the first time, the synthesis, characterization, and the photocatalytic methyl blue dye degradation performance of magnesium oxide (MgO) nanoparticles (NPs) synthesized by a facile green approach using Camellia sinensis (tea leaves) extract as a reducing agent. The as-prepared materials were characterized by x-ray diffraction (XRD), which confirmed the large-scale synthesis of well crystalline cubic crystalline phase MgO NPs. Rietveld refinement analysis of the XRD pattern was done to determine the crystallographic parameters of the MgO NPs and to investigate lattice defects. Microstrain, lattice stress and energy density were calculated using Williamson-Hall analysis The synthesized nanoparticles exhibited over 97% photocatalytic degradation efficiency of methylene blue (MB) dye. Complementary density functional theory (DFT) calculations revealed the favorable formation of O 2 − radicals on the MgO (001) surface as the drivers of the MB dye degradation

Precise measurement of the W-boson mass with the CDF II detector

We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined

Microglia/macrophage derived human CCL18 promotes glioma progression via CCR8-ACP5 axis analyzed in humanized slice model

Factors released from glioma-associated microglia/macrophages (GAMs) play a crucial role in glioblastoma multiforme (GBM) progression. Here, we study the importance of CCL18, a cytokine expressed in human but not in rodent GAMs, as a modulator of glioma growth. Since CCL18 signaling could not be studied in classical mouse glioma models, we developed an approach by transplanting induced pluripotent stem cell-derived human microglia and human glioma cells into mouse brain slices depleted of their intrinsic microglia. We observe that CCL18 promotes glioma cell growth and invasion. Chemokine (C-C motif) receptor 8 (CCR8) is identified as a functional receptor for CCL18 on glioma cells, and ACP5 (acid phosphatase 5) is revealed as an important part of the downstream signaling cascade for mediating glioma growth. We conclude, based on the results from an in vitro, ex vivo humanized glioma model and an in vivo GBM model that microglia/macrophage-derived CCL18 promotes glioma growth

Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE