Calculation of renormalized viscosity and resistivity in magnetohydrodynamic turbulence

A self-consistent renormalization (RG) scheme has been applied to nonhelical magnetohydrodynamic turbulence with normalized cross helicity $\sigma_c =0$ and $\sigma_c \to 1$. Kolmogorov's 5/3 powerlaw is assumed in order to compute the renormalized parameters. It has been shown that the RG fixed point is stable for $d \ge d_c \approx 2.2$. The renormalized viscosity $\nu^*$ and resistivity $\eta^*$ have been calculated, and they are found to be positive for all parameter regimes. For $\sigma_c=0$ and large Alfv\'{e}n ratio (ratio of kinetic and magnetic energies) $r_A$, $\nu^*=0.36$ and $\eta^*=0.85$. As $r_A$ is decreased, $\nu^*$ increases and $\eta^*$ decreases, untill $r_A \approx 0.25$ where both $\nu^*$ and $\eta^*$ are approximately zero. For large $d$, both $\nu^*$ and $\eta^*$ vary as $d^{-1/2}$. The renormalized parameters for the case $\sigma_c \to 1$ are also reported.Comment: 19 pages REVTEX, 3 ps files (Phys. Plasmas, v8, 3945, 2001

Starbursts in multiple galaxy mergers

We numerically investigate stellar and gaseous dynamical evolution of mergers between five identical late-type disk galaxies with the special emphasis on star formation history and chemical evolution of multiple galaxy mergers. We found that multiple encounter and merging can trigger repetitive massive starbursts (typically $\sim$ 100 $M_{\odot}$ ${\rm yr}^{-1}$) owing to the strong tidal disturbance and the resultant gaseous dissipation during merging. The magnitude of the starburst is found to depend on initial virial ratio (i.e., the ratio of total kinematical energy to total potential energy) such that the maximum star formation rate is larger for the merger with smaller virial ratio. Furthermore we found that the time interval between the epochs of the triggered starbursts is longer for the merger with the larger virial ratio. The remnant of a multiple galaxy merger with massive starbursts is found to have metal-poor gaseous halo that is formed by tidal stripping during the merging. We accordingly suggest that metal-poor gaseous halo in a field elliptical galaxy is a fossil record of the past multiple merging events for the galaxy.Comment: 23 pages 16 figures,2000,ApJ,545 in press. For all ps figures, see http://newt.phys.unsw.edu.au/~bekki/res.dir/paper.dir/mul.dir/fig.tar.g

Characteristics of constrained turbulent transport in flux-driven toroidal plasmas

We study the dynamics of turbulence transport subject to a constraint on the profile formation and relaxation, dominated by the ion temperature gradient modes, within the framework of adiabatic electron response using a flux-driven global gyro-kinetic toroidal code, GKNET. We observe exponentially constrained profiles, with two different scale lengths, that are spatially constant in each region in higher input power regimes. The profiles are smoothly connected in the knee region located at 1/2−2/3 of the minor radius, outside which the gradient is steepened and shows a weak confinement improvement. Based on the probability density function analysis of heat flux eddies, the power law demonstrates a dependence on the eddy size S, as P∼S[−α], which distinguishes events into diffusive and non-diffusive parts including the validation of quasi-linear hypotheses. Radially localized avalanches and global bursts, which exhibit different spatial scales, play central roles in giving rise to constrained profiles on an equal footing. It is also found that the E×B shear layers are initiated by the global bursts, which evolve downward on a slow time scale across the knee region and play a role in adjusting the profile by increasing the gradient

Targeting the differential addiction to anti-apoptotic BCL-2 family for cancer therapy

AbstractBCL-2 family proteins are central regulators of mitochondrial apoptosis and validated anti-cancer targets. Using small cell lung cancer (SCLC) as a model, we demonstrated the presence of differential addiction of cancer cells to anti-apoptotic BCL-2, BCL-XL or MCL-1, which correlated with the respective protein expression ratio. ABT-263 (navitoclax), a BCL-2/BCL-XL inhibitor, prevented BCL-XL from sequestering activator BH3-only molecules (BH3s) and BAX but not BAK. Consequently, ABT-263 failed to kill BCL-XL-addicted cells with low activator BH3s and BCL-XL overabundance conferred resistance to ABT-263. High-throughput screening identified anthracyclines including doxorubicin and CDK9 inhibitors including dinaciclib that synergized with ABT-263 through downregulation of MCL-1. As doxorubicin and dinaciclib also reduced BCL-XL, the combinations of BCL-2 inhibitor ABT-199 (venetoclax) with doxorubicin or dinaciclib provided effective therapeutic strategies for SCLC. Altogether, our study highlights the need for mechanism-guided targeting of anti-apoptotic BCL-2 proteins to effectively activate the mitochondrial cell death programme to kill cancer cells.</jats:p

Naturecultures guidance: steps in our journey

The emergence of cultural landscapes concepts heralded important mindset shifts in heritage practices. These have underpinned development of landscape approaches that recognise larger-scale interactions and the relationships between natural and cultural elements and processes. However, it has become apparent that an enduring nature-culture binary in heritage practices can result in adverse outcomes ‘on the ground’. The ISCCL has provided a forum and a source of global leadership for these issues, including the exploration of the implications of working with naturecultures to achieve conservation outcomes that are effective and inclusive. Naturecultures was coined by Donna Haraway in 2003 to recognise that natural and human environments, including non-human and more-than-human beings (such as spirits, creation ancestors, divinities) are intimately bound or entangled within different places. There is a now a growing desire to move beyond a curious consideration of the conceptual possibilities of naturecultures to implement its meanings in a wide array of everyday heritage management practices. Physically separated by the global pandemic, we are a small group of natural and cultural heritage practitioners and ISCCL members who decided to step briefly away from our organisational and institutional affiliations to connect with each other, reflect on our experiences, and offer guidance to others. This presentation will be our first opportunity to communicate what we’ve been up to, and to share some thoughts that our journey together has afforded. We argue that applying naturecultures in our practices is beneficial for people and places, and can support more effective conservation outcomes. Please join us to think further about these ideas. Français : L\u27émergence des concepts de paysages culturels a annoncé d\u27importants changements de mentalité dans les pratiques patrimoniales. Ceux-ci ont soutenu le développement d\u27approches paysagères qui reconnaissent les interactions à plus grande échelle et les relations entre les éléments et les processus naturels et culturels. Cependant, il est devenu évident qu\u27un binaire nature-culture durable dans les pratiques patrimoniales peut entraîner des résultats négatifs « sur le terrain ». L\u27ISCCL a fourni un forum et une source de leadership mondial pour ces questions, y compris l\u27exploration des implications du travail avec les cultures de la nature pour obtenir des résultats de conservation efficaces et inclusifs. Naturecultures a été inventé par Donna Haraway en 2003 pour reconnaître que les environnements naturels et humains, y compris les êtres non humains et plus qu\u27humains (tels que les esprits, les ancêtres de la création, les divinités) sont intimement liés ou enchevêtrés dans différents endroits. Il y a maintenant un désir croissant d\u27aller au-delà d\u27une curieuse considération des possibilités conceptuelles des cultures de la nature pour mettre en œuvre ses significations dans un large éventail de pratiques quotidiennes de gestion du patrimoine. Physiquement séparés par la pandémie mondiale, nous sommes un petit groupe de praticiens du patrimoine naturel et culturel et de membres de l\u27ISCCL qui ont décidé de s\u27éloigner brièvement de nos affiliations organisationnelles et institutionnelles pour se connecter les uns aux autres, réfléchir à nos expériences et offrir des conseils aux autres. Cette présentation sera notre première occasion de communiquer ce que nous avons fait et de partager quelques réflexions que notre voyage ensemble a permis. Nous soutenons que l\u27application des cultures de la nature dans nos pratiques est bénéfique pour les personnes et les lieux, et peut favoriser des résultats de conservation plus efficaces. Veuillez vous joindre à nous pour approfondir ces idées. Español: La aparición de conceptos de paisajes culturales anunció importantes cambios de mentalidad en las prácticas patrimoniales. Estos han apuntalado el desarrollo de enfoques de paisaje que reconocen interacciones a mayor escala y las relaciones entre elementos y procesos naturales y culturales. Sin embargo, se ha hecho evidente que un binario duradero entre naturaleza y cultura en las prácticas patrimoniales puede dar lugar a resultados adversos sobre el terreno . El ISCCL ha proporcionado un foro y una fuente de liderazgo global para estos temas, incluida la exploración de las implicaciones de trabajar con las culturas de la naturaleza para lograr resultados de conservación que sean efectivos e inclusivos. Naturecultures fue acuñada por Donna Haraway en 2003 para reconocer que los entornos naturales y humanos, incluidos los seres no humanos y más que humanos (como espíritus, antepasados de la creación, divinidades) están íntimamente ligados o enredados en diferentes lugares. Existe ahora un creciente deseo de ir más allá de una consideración curiosa de las posibilidades conceptuales de las culturas de la naturaleza para implementar sus significados en una amplia gama de prácticas cotidianas de gestión del patrimonio. Físicamente separados por la pandemia global, somos un pequeño grupo de practicantes del patrimonio natural y cultural y miembros de ISCCL que decidieron alejarse brevemente de nuestras afiliaciones organizacionales e institucionales para conectarnos unos con otros, reflexionar sobre nuestras experiencias y ofrecer orientación a los demás. Esta presentación será nuestra primera oportunidad para comunicar lo que hemos estado haciendo y compartir algunos pensamientos que nos ha brindado nuestro viaje juntos. Argumentamos que la aplicación de las culturas de la naturaleza en nuestras prácticas es beneficiosa para las personas y los lugares, y puede respaldar resultados de conservación más efectivos. Únase a nosotros para pensar más en estas ideas

Diffusion tensor imaging of Parkinson's disease, multiple system atrophy and progressive supranuclear palsy: a tract-based spatial statistics study

Although often clinically indistinguishable in the early stages, Parkinson's disease (PD), Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP) have distinct neuropathological changes. The aim of the current study was to identify white matter tract neurodegeneration characteristic of each of the three syndromes. Tract-based spatial statistics (TBSS) was used to perform a whole-brain automated analysis of diffusion tensor imaging (DTI) data to compare differences in fractional anisotropy (FA) and mean diffusivity (MD) between the three clinical groups and healthy control subjects. Further analyses were conducted to assess the relationship between these putative indices of white matter microstructure and clinical measures of disease severity and symptoms. In PSP, relative to controls, changes in DTI indices consistent with white matter tract degeneration were identified in the corpus callosum, corona radiata, corticospinal tract, superior longitudinal fasciculus, anterior thalamic radiation, superior cerebellar peduncle, medial lemniscus, retrolenticular and anterior limb of the internal capsule, cerebral peduncle and external capsule bilaterally, as well as the left posterior limb of the internal capsule and the right posterior thalamic radiation. MSA patients also displayed differences in the body of the corpus callosum corticospinal tract, cerebellar peduncle, medial lemniscus, anterior and superior corona radiata, posterior limb of the internal capsule external capsule and cerebral peduncle bilaterally, as well as the left anterior limb of the internal capsule and the left anterior thalamic radiation. No significant white matter abnormalities were observed in the PD group. Across groups, MD correlated positively with disease severity in all major white matter tracts. These results show widespread changes in white matter tracts in both PSP and MSA patients, even at a mid-point in the disease process, which are not found in patients with PD

Dark matter and non-Newtonian gravity from General Relativity coupled to a fluid of strings

An exact solution of Einstein's field equations for a point mass surrounded by a static, spherically symmetric fluid of strings is presented. The solution is singular at the origin. Near the string cloud limit there is a $1/r$ correction to Newton's force law. It is noted that at large distances and small accelerations, this law coincides with the phenomenological force law invented by Milgrom in order to explain the flat rotation curves of galaxies without introducing dark matter. When interpreted in the context of a cosmological model with a string fluid, the new solution naturally explains why the critical acceleration of Milgrom is of the same order of magnitude as the Hubble parameter.Comment: 12 pages, REVTeX, no figure

A Decadal Inversion of CO2 Using the Global Eulerian-Lagrangian Coupled Atmospheric Model (GELCA): Sensitivity to the Ground-Based Observation Network

We present an assimilation system for atmospheric carbon dioxide (CO2) using a Global Eulerian-Lagrangian Coupled Atmospheric model (GELCA), and demonstrate its capability to capture the observed atmospheric CO2 mixing ratios and to estimate CO2 fluxes. With the efficient data handling scheme in GELCA, our system assimilates non-smoothed CO2 data from observational data products such as the Observation Package (ObsPack) data products as constraints on surface fluxes. We conducted sensitivity tests to examine the impact of the site selections and the prior uncertainty settings of observation on the inversion results. For these sensitivity tests, we made five different sitedata selections from the ObsPack product. In all cases, the time series of the global net CO2 flux to the atmosphere stayed close to values calculated from the growth rate of the observed global mean atmospheric CO2 mixing ratio. At regional scales, estimated seasonal CO2 fluxes were altered, depending on the CO2 data selected for assimilation. Uncertainty reductions (URs) were determined at the regional scale and compared among cases. As measures of the model-data mismatch, we used the model-data bias, root-mean-square error, and the linear correlation. For most observation sites, the model-data mismatch was reasonably small. Regarding regional flux estimates, tropical Asia was one of the regions that showed a significant impact from the observation network settings. We found that the surface fluxes in tropical Asia were the most sensitive to the use of aircraft measurements over the Pacific, and the seasonal cycle agreed better with the results of bottom-up studies when the aircraft measurements were assimilated. These results confirm the importance of these aircraft observations, especially for constraining surface fluxes in the tropics