1,354,758 research outputs found
Coleman-weinberg model in Einstein space-time
No full textWe study radiative, symmetry breaking, h ht ('olemav,-
~,Veinb(,r(_,, in the /eometry of a .~tatic Einstein mfivcrsc. \Vc prove that
the syvmnetric gv'om,d state (oi~510 > - . r in a nouminimally coupled mass-
1,,s,~ ).r theory, can l)et'onw, u,,st al)lc at high curvature only if 0 "4 ~ )..;: 1.
As far as mas.sles~ scalar (~I".I) is ('oncerned, we find lhat pha.~c transitions
can already oc('m" at low cttrvature. These conchisions arc improvc(l
by nwans of r,*norm:diz:alion group tcwhniques
Symmetry restoration in conformally flat metrics
No full textWe study symmetry restoration in a curved-background
metric. Massless scalar QED is considered in the de Sitter space-time.
The radius of the cosmological-event horizon corresponding to the critical
temperature turns out to be of the order of the Compton wave-length
of the vector bosom Quite similarly, the Gross-Neveau model in the twodimensional
Schwarzschild background shows symmetry restoration
when the radius of the black-hole horizon becomes comparable with
the Compton wave-length of the spinor
Induced quantum gravity from heat kernel expansion
No full textThe asymptotic expansion of the heat kernel is employed
to derive the Einstein action from the matter effective action. The
advantages of this approach are discussed. We point out some problems
arising when scalar fields, nonminimally coupled to the background
geometry, are used as fundamental pregeometric objects
Curvature and symmetry breaking: An induced-action approach
No full textWe recover the general form of the one-loop effective
potential for a Ar 4 theory, nonminimally coupled to a constant-curvature
background geometry, in the low-energy limit, i.e. for small curvature.
Renormalization is carried out and the massless limit of the renormalized
theory is performed. Then we study the symmetry properties of the
vacuum state according to the value of the nonminimal coupling constant
~ and the sign of the curvature
How Electrostatic Speakers Work [video]
No full textNPS Physics EDUHere's how Electrostatic Speakers Work. Did you know that a regular old loudspeaker converts electrical energy into acoustic energy? But what about an electrostatic speaker? In this video Dr. Bruce Denardo explains how an electrostatic loud speaker works. This video was originally created during a 2015 MAOS visit at the naval postgraduate school
Ultrastructural and immunocytochemical features of the epidermis of the lizard Heloderma suspectum indicate richness in lipids and lack of a specialized shedding complex
No full textThe epidermis of the venomous lizard Heloderma suspectum has been studied for
detecting generalized and desert adaptations. A thick and non-completely syncytial
beta-keratin layer is followed by 60–90 layers of mesos-cells. Non-lamellated
or sparse lamellated lipid material is seen among mesos-cells where lipids
form the main barrier against water loss. The alpha-layer is made of interlocking
cells with irregular perimeter that are connected through desmosomal remnants.
Immunocytochemistry shows that beta-keratin is present in beta-cells,
disappears in mesos-cells but is diffuse in alpha-cells. Alpha-keratin is seen in
mesos-cells but lowers in alpha-cells where alpha-keratin probably mixes with
beta-keratin. Although the sequence of layers formed during the renewal stage
of the epidermis was not available, a specialized shedding layer with an outer
oberhautchen faced to an inner clear layer appears absent in this species. This
condition suggests that shedding occurs at the boundary between the outer
(old) alpha-layer and the inner (new) beta-layer formed underneath the alphalayer.
The thick mesos layer is likely an efficient adaptation to limit water loss
in desert conditions while the poorly specialized shedding complex may suggest
a primitive stage in the evolutio
NCOA4-mediated ferritinophagy promotes ferroptosis induced by erastin, but not by RSL3 in HeLa cells
No full textFerroptosis is a regulated cell death characterized by a lethal accumulation of lipid peroxides due to an increase of intracellular iron and a decrease of antioxidant capacity. The reduction of antioxidant activity is obtained by using chemical agents, such as erastin and RSL3, the first one inhibiting the transmembrane cystine-glutamate antiporter causing a cysteine and glutathione depletion and the second one inactivating directly the glutathione peroxidase 4 (GPX4) respectively. The role of iron and its related proteins in supporting the formation of lipid peroxides, is not completely understood hence to try to shed light on it we generated HeLa clones with altered ferritinophagy, the ferritin degradation process, by knocking-out or overexpressing Nuclear Receptor Coactivator 4 (NCOA4), the ferritin autophagic cargo-receptor. NCOA4 deficiency abolished ferritinophagy increasing ferritin level and making the cells more resistant to erastin, but unexpectedly more sensitive to RSL3. Interestingly, we found that erastin promoted ferritinophagy in HeLa cells expressing NCOA4, increasing the free iron, lipid peroxidation and the sensitivity to ferroptosis. In contrast, RSL3 did not modulate ferritinophagy, while NCOA4 overexpression delayed RSL3-induced cell death suggesting that RSL3 mechanism of action is independent of ferritin degradation process. Therefore, the ferritin-iron release in the execution of ferroptosis seems to depend on the inducing compound, its target and downstream pathway of cell death activation
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