509 research outputs found
Conformal Solutions Of Duality Invariant 2D Magnetohydrodynamic Turbulence
We consider possible conformal field theory (CFT) descriptions of the various
inertial ranges that exist in duality invariant Magnetohydrodynamics. Such
models arise as effective theories of dyonic plasmas in 3 dimensions in which
all fields are independent of the third coordinate. We find new constraints on
the allowed CFT's compared to those that may describe turbulence in
plasmas of electric charges only. The predictions from CFT concerning
equipartition of energy amongst the electric and magnetic fields are discussed,
and quantities exhibiting universal scaling are derived.Comment: Latex, 8 page
Duality Invariant Magnetohydrodynamics And Dyons
The theory of magnetohydrodynamics is extended to the cases of a plasma of
separate magnetic and electric charges, as well as to a plasma of dyons
respectively. In both these cases the system possesses electric-magnetic
duality symmetry. In the former case we find that because of the existence of
two independent generalized Ohm's law equations, the limit of infinite electric
and magnetic conductivity results in the vanishing of both electric and
magnetic fields, as well as the corresponding currents. In the dyonic case, we
find that the resulting duality-invariant system of equations are equivalent to
those of ordinary MHD, after suitable field redefinitions.Comment: 11 pages, late
Black Holes and Flop Transitions in M-Theory on Calabi-Yau Threefolds
We present fivedimensional extreme black hole solutions of M-theory
compactified on Calabi-Yau threefolds and study these solutions in the context
of flop transitions in the extended Kahler cone. In particular we consider a
specific model and present black hole solutions, breaking half of N=2
supersymmetry, in two regions of the extended Kahler cone, which are connected
by a flop transition. The conditions necessary to match both solutions at the
flop transition are analysed. Finally we also discuss the conditions to obtain
massless black holes at the flop transition.Comment: 19 pp, LaTe
HKT Geometry and Fake Five Dimensional Supergravity
Recent results on the relation between hyper-Kahler geometry with torsion and
solutions admitting Killing spinors in minimal de sitter supergravity are
extended to more general supergravity models with vector multiplets.Comment: 14 pages, latex. Minor typos corrected, references adde
Virtual Interview Preparation for Generation Z Science, Technology, Engineering, and Math (STEM) Students - A Necessity for the Post-Pandemic Era
Social distancing and remote work were mandated worldwide during the COVID-19 lockdown. While virtual interviews were conducted prior to lockdown due to the growing global workforce, they became normalized during the pandemic for both work and school. Hiring agents may believe that having grown up with technology and the internet Generation Z (Gen Z) may be well-prepared for virtual interviews. However, the challenge they face is not technology-related. Gen Z individuals, particularly those in STEM fields, often lack well-developed practical and pragmatic life skills, such as effective communication. A remote independent research scholar and her student compiled this field report. First, the general characteristics of Gen Z STEM students are presented, followed by a virtual interview preparation guide with tips, recommendations and examples. Given the ever-changing global remote workforce, future empirical studies are recommended on the virtual hiring process of Gen Z STEM students which includes and expands upon virtual interviews
Toward Forecasting Volcanic Eruptions using Seismic Noise
During inter-eruption periods, magma pressurization yields subtle changes of
the elastic properties of volcanic edifices. We use the reproducibility
properties of the ambient seismic noise recorded on the Piton de la Fournaise
volcano to measure relative seismic velocity variations of less than 0.1 % with
a temporal resolution of one day. Our results show that five studied volcanic
eruptions were preceded by clearly detectable seismic velocity decreases within
the zone of magma injection. These precursors reflect the edifice dilatation
induced by magma pressurization and can be useful indicators to improve the
forecasting of volcanic eruptions.Comment: Supplementary information:
http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguier_SI.pdf Supplementary
video:
http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguierMovieVolcano.av
Optical IFU Observations of the Brightest Cluster Galaxy NGC 4696: The Case for a Minor Merger and Shock-excited Filaments
We present deep optical integral-field spectroscopic observations of the
nearby (z ~ 0.01) brightest cluster galaxy NGC 4696 in the core of the
Centaurus Cluster, made with the Wide Field Spectrograph (WiFeS) on the ANU
2.3m telescope at Siding Spring Observatory. We investigate the morphology,
kinematics, and excitation of the emission-line filaments and discuss these in
the context of a model of a minor merger. We suggest that the emission-line
filaments in this object have their origin in the accretion of a gas-rich
galaxy and that they are excited by v ~100-200 km/s shocks driven into the cool
filament gas by the ram pressure of the transonic passage of the merging system
through the hot halo gas of NGC 4696.Comment: 19 pages, 15 figures, accepted for publication in The Astrophysical
Journa
Sex chromosome complement contributes to sex differences in coxsackievirus B3 but not influenza A virus pathogenesis
<p>Abstract</p> <p>Background</p> <p>Both coxsackievirus B3 (CVB3) and influenza A virus (IAV; H1N1) produce sexually dimorphic infections in C57BL/6 mice. Gonadal steroids can modulate sex differences in response to both viruses. Here, the effect of sex chromosomal complement in response to viral infection was evaluated using four core genotypes (FCG) mice, where the <it>Sry </it>gene is deleted from the Y chromosome, and in some mice is inserted into an autosomal chromosome. This results in four genotypes: XX or XY gonadal females (XXF and XYF), and XX or XY gonadal males (XXM and XYM). The FCG model permits evaluation of the impact of the sex chromosome complement independent of the gonadal phenotype.</p> <p>Methods</p> <p>Wild-type (WT) male and female C57BL/6 mice were assigned to remain intact or be gonadectomized (Gdx) and all FCG mice on a C57BL/6 background were Gdx. Mice were infected with either CVB3 or mouse-adapted IAV, A/Puerto Rico/8/1934 (PR8), and monitored for changes in immunity, virus titers, morbidity, or mortality.</p> <p>Results</p> <p>In CVB3 infection, mortality was increased in WT males compared to females and males developed more severe cardiac inflammation. Gonadectomy suppressed male, but increased female, susceptibility to CVB3. Infection with IAV resulted in greater morbidity and mortality in WT females compared with males and this sex difference was significantly reduced by gonadectomy of male and female mice. In Gdx FCG mice infected with CVB3, XY mice were less susceptible than XX mice. Protection correlated with increased CD4+ forkhead box P3 (FoxP3)+ T regulatory (Treg) cell activation in these animals. Neither CD4+ interferon (IFN)Îł (T helper 1 (Th1)) nor CD4+ interleukin (IL)-4+ (Th2) responses differed among the FCG mice during CVB3 infection. Infection of Gdx FCG mice revealed no effect of sex chromosome complement on morbidity or mortality following IAV infection.</p> <p>Conclusions</p> <p>These studies indicate that sex chromosome complement can influence pathogenicity of some, but not all, viruses.</p
- …