21,273 research outputs found
Calcified amorphous tumor: A rare cause of central retinal artery occlusion.
PurposeWe report the case of a central retinal artery occlusion secondary to presumed embolus from a calcified amorphous tumor of the heart, a very rare non-neoplastic cardiac mass.ObservationsA 60-year-old female presented with acute unilateral vision loss of the left eye. Examination revealed hand motion visual acuity of the left eye and a left relative afferent pupillary defect. Fundoscopy showed whitening of the macula with a cherry red spot, consistent with a central retinal artery occlusion. Initial workup was unremarkable, including hypercoagulability labs, magnetic resonance imaging of the brain, and magnetic resonance angiography of the head and neck. Transthoracic echocardiogram (TTE) showed calcification of the mitral valve but no masses. Subsequently, transesophageal echocardiogram (TEE) was performed, which revealed a mobile calcified amorphous tumor of the heart.ConclusionsCalcified amorphous tumor of the heart is a very rare cardiac mass that may cause retinal artery occlusion. TEE is a more sensitive imaging modality to assess for potential cardio-embolic sources if TTE is unrevealing
Gravitational waves from three-dimensional core-collapse supernova models: The impact of moderate progenitor rotation
We present predictions for the gravitational-wave (GW) emission of
three-dimensional supernova (SN) simulations performed for a 15 solar-mass
progenitor with the Prometheus-Vertex code using energy-dependent, three-flavor
neutrino transport. The progenitor adopted from stellar evolution calculations
including magnetic fields had a fairly low specific angular momentum (j_Fe <~
10^{15} cm^2/s) in the iron core (central angular velocity ~0.2 rad/s), which
we compared to simulations without rotation and with artificially enhanced
rotation (j_Fe <~ 2*10^{16} cm^2/s; central angular velocity ~0.5 rad/s). Our
results confirm that the time-domain GW signals of SNe are stochastic, but
possess deterministic components with characteristic patterns at low
frequencies (<~200 Hz), caused by mass motions due to the standing accretion
shock instability (SASI), and at high frequencies, associated with gravity-mode
oscillations in the surface layer of the proto-neutron star (PNS). Non-radial
mass motions in the post-shock layer as well as PNS convection are important
triggers of GW emission, whose amplitude scales with the power of the
hydrodynamic flows. There is no monotonic increase of the GW amplitude with
rotation, but a clear correlation with the strength of SASI activity. Our
slowly rotating model is a fainter GW emitter than the non-rotating model
because of weaker SASI activity and damped convection in the post-shock layer
and PNS. In contrast, the faster rotating model exhibits a powerful SASI spiral
mode during its transition to explosion, producing the highest GW amplitudes
with a distinctive drift of the low-frequency emission peak from ~80-100 Hz to
~40-50 Hz. This migration signifies shock expansion, whereas non-exploding
models are discriminated by the opposite trend.Comment: Added new figure, figure 9. Updated figure 9, now figure 10. Modified
the discussion of the proto-neutron star convection. Added a figure showing
the average rotation rate as a function of radius. Added a section discussing
where the low-frequency gravitational waves are generated, this information
is visualized in figure 9. We also made some minor changes to the text and
selected plot
Conformity Through Fear: A Multimodal Critical Discourse Analysis of COVID-19 Information Adverts
The UK Government has produced an array of televised information adverts or ‘campaigns’ to increase public awareness of COVID-19 and promote compliance with its subsequent policy. Research has shown that compliance with public health policy is influenced by fearful visual-verbal campaign messaging strategies, and that emotive representations of ‘risk’ are generally perceived to be more effective than non-emotive discourse. However, how the Government has semiotically constructed and utilised fear within their COVID-19 campaigns to nudge public compliance remains unexplored. Preliminary analysis of seventeen COVID-19 adverts revealed four sequential phases to the Government’s pandemic response: responsibility, management, mitigation, and reflection. An in-depth Multimodal Critical Discourse Analysis of four selected adverts (one screenshot per advert, per phase), revealed that fear was constructed using less conventional meaning potentials in favour of more implicit multimodal semiotic interactions. By portraying a ‘good’ pandemic subject as one who makes ‘moral’ and ‘rational’ decisions to comply with COVID-19 policy, pre-existing societal inequalities which might hinder compliance, particularly for the socioeconomically disadvantaged groups of society, were reduced and problematised. This raises ethical concerns over notions of ‘expertise’ and the ‘rationalising’ of ‘irrational’ lifestyles. Future research should further explore multimodal nudges in public health campaigns to hold producers accountable
Unique Mass Texture for Quarks and Leptons
Texture specific quark mass matrices which are hermitian and hierarchical are
examined in detail . In the case of texture 6 zeros matrices, out of sixteen
possibilities examined by us, none is able to fit the low energy data (LED),
for example, , ,
, lies in the range (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered
is able to reproduce LED. In particular, the latest data from LEP regarding
rules out all of them. In the texture 4
zeros case, we find that there is a unique texture structure for and
mass matrices which is able to fit the data.Comment: 12 pages, LaTeX,some changes in the references,minor changes in the
text,to appear in Phys Rev D(Rapid communications
Induction of Mutation in Rough Lemon (Citrus jambhiri Lush.) Using Gamma Rays
The present investigation was carried out to study variability induced by gamma rays with respect to vegetative characters and LD50 dose in Rough lemon. Rough lemon seeds were gamma irradiated at doses of 0, 4, 6 and 8 kr along with control. Seed germination decreased with increasing dose of gamma radiation. Seedling height and leaf size also decreased with increasing dose of gamma radiation, whereas, apical branching, number of branches/seedling, number of variegated / albino seedlings and number of leaves increased with increasing dose of gamma radiation. Maximum variability for seedling height, number of leaves, leaf size, colour, internode length, and per cent apical branching was observed at two months from sowing in seeds treated with 8 kr dose of gamma radiation. Variability for all characters was, however, found to be minimum in the control
The breaking of the flavour permutational symmetry: Mass textures and the CKM matrix
Different ansaetze for the breaking of the flavour permutational symmetry
according to S(3)L X S(3)R in S(2)L X S(2) give different Hermitian mass
matrices of the same modified Fritzsch type, which differ in the symmetry
breaking pattern. In this work we obtain a clear and precise indication on the
preferred symmetry breaking scheme from a fit of the predicted theoretical Vckm
to the experimentally determined absolute values of the elements of the CKM
matrix. The preferred scheme leads to simple mass textures and allows us to
compute the CKM mixing matrix, the Jarlskog invariant J, and the three inner
angles of the unitarity triangle in terms of four quark mass ratios and only
one free parameter: the CP violating phase Phi. Excellent agreement with the
experimentally determined absolute values of the entries in the CKM matrix is
obtained for Phi = 90 deg. The corresponding computed values of the Jarlskog
invariant and the inner angles are J = 3.00 X 10^-5, alpha= 84 deg, beta= 24
deg and gamma =72 deg in very good agreement with current data on CP violation
in the neutral kaon-antikaon system and oscillations in the B-Bbar system.Comment: 21 pages, 1 fig. Content enlarged, references added and typos
corrected. To be published in Phys Rev
Estimating the spectrum of a density matrix with LOCC
The problem of estimating the spectrum of a density matrix is considered.
Other problems, such as bipartite pure state entanglement, can be reduced to
spectrum estimation. A local operations and classical communication (LOCC)
measurement strategy is shown which is asymptotically optimal. This means that,
for a very large number of copies, it becomes unnecessary to perform collective
measurements which should be more difficult to implement in practice.Comment: 12 pages, uses iopart.cls and iopart10.clo. Improved version. v3:
Reference updated, added journal referenc
Estimation of unitary quantum operations
The problem of optimally estimating an unknown unitary quantum operation with
the aid of entanglement is addressed. The idea is to prepare an entangled pair,
apply the unknown unitary to one of the two parts and then measure the joint
output state. This measurement could be an entangled one or it could be
separable (e.g., LOCC). A comparison is made between these possibilities and it
is shown that by using non-separable measurements one can improve the accuracy
of the estimation by a factor of where is the dimension of the
Hilbert space on which acts.Comment: 6 pages. Revised version. Typos corrected. Some discussion added.
Reference fixe
Dynamin-related protein 1 is required for normal mitochondrial bioenergetic and synaptic function in CA1 hippocampal neurons.
Disrupting particular mitochondrial fission and fusion proteins leads to the death of specific neuronal populations; however, the normal functions of mitochondrial fission in neurons are poorly understood, especially in vivo, which limits the understanding of mitochondrial changes in disease. Altered activity of the central mitochondrial fission protein dynamin-related protein 1 (Drp1) may contribute to the pathophysiology of several neurologic diseases. To study Drp1 in a neuronal population affected by Alzheimer's disease (AD), stroke, and seizure disorders, we postnatally deleted Drp1 from CA1 and other forebrain neurons in mice (CamKII-Cre, Drp1lox/lox (Drp1cKO)). Although most CA1 neurons survived for more than 1 year, their synaptic transmission was impaired, and Drp1cKO mice had impaired memory. In Drp1cKO cell bodies, we observed marked mitochondrial swelling but no change in the number of mitochondria in individual synaptic terminals. Using ATP FRET sensors, we found that cultured neurons lacking Drp1 (Drp1KO) could not maintain normal levels of mitochondrial-derived ATP when energy consumption was increased by neural activity. These deficits occurred specifically at the nerve terminal, but not the cell body, and were sufficient to impair synaptic vesicle cycling. Although Drp1KO increased the distance between axonal mitochondria, mitochondrial-derived ATP still decreased similarly in Drp1KO boutons with and without mitochondria. This indicates that mitochondrial-derived ATP is rapidly dispersed in Drp1KO axons, and that the deficits in axonal bioenergetics and function are not caused by regional energy gradients. Instead, loss of Drp1 compromises the intrinsic bioenergetic function of axonal mitochondria, thus revealing a mechanism by which disrupting mitochondrial dynamics can cause dysfunction of axons
- …