12,586 research outputs found
Effect of a weak longitudinal modulation in refractive index on transverse localization of light in 1D disordered waveguide lattices
We report the enhancement of the effect of transverse localization of light
(TL) in presence of a weak longitudinal modulation of refractive index in
disordered waveguide lattices. In our chosen lattices, tunneling inhibition
along length favors to achieve the diffraction-free propagation along with the
simultaneous presence of transverse disorder. Results will be useful to tune
the threshold value of disorder to achieve localized light.Comment: 4 pages. arXiv admin note: text overlap with arXiv:1204.614
Observation of topologically protected helical edge modes in Kagome elastic plates
The investigation of topologically protected waves in classical media has
opened unique opportunities to achieve exotic properties like one-way phonon
transport, protection from backscattering and immunity to imperfections.
Contrary to acoustic and electromagnetic domains, their observation in elastic
solids has so far been elusive due to the presence of both shear and
longitudinal modes and their modal conversion at interfaces and free surfaces.
Here we report the experimental observation of topologically protected
helical edge waves in elastic media. The considered structure consists of an
elastic plate patterned according to a Kagome architecture with an accidental
degeneracy of two Dirac cones induced by drilling through holes. The careful
breaking of symmetries couples the corresponding elastic modes which
effectively emulates spin orbital coupling in the quantum spin Hall effect.
The results shed light on the topological properties of the proposed plate
waveguide and opens avenues for the practical realization of compact, passive
and cost-effective elastic topological waveguides
Effects of vitamins on thyroid and suprarenals
I. EFFECTS OF VITAMINS A AND B ON THYROID AND SUPRARENALS:
1. vitamin A containing diet affects the thyroid similarly to thyroid feeding in small doses, causing inactivity
whereas deficiency leads to increased activity on
the part of the gland.
2. A resting gland can exert its detoxicating function
more than an actively secreting one. This is why vitamin
A-fed animals can resist toxins better than the deficient
ones.
3. vitamin A acts specifically against Acetonitril like
thyroid extract, as is shown by an increased number of
phagocytic cells in the gland. The gland is kept in a
resting phase so that it can counteract toxins. But when
the glands become exhausted by active secretion under
the influence of toxin, death takes place.
4. The growth promoting property of the vitamin A may
be explained by diminished metabolism caused by producing
the resting phase of the gland.
5. The growth promoting nature of vitamin B may be also
explained by the diminished metabolism it causes.
6. The deficiency of vitamin B caused more increased
secretion and ultimately hyperplasia of the thyroid.
7. vitamin E. is not antitoxic.
8. There is a striking similarity between the effects of
vitamins A and B upon the thyroid gland (with
the exception of the specific action of the vitamin A
in resisting toxins).
9. vitamin A or B deficiency alone cannot cause a complete
absence of lipoid content of the cortex of the suprarenal
gland.
10. Adrenaline content of the suprarenals is increased
by vitamin A deficiency, whereas vitamin B deficiency
produces a smaller amount than normal.
11. vitamin B deficiency ultimately leads to an acute
insufficiency of the medulla of the suprarenals.II. EFFECTS OF VITAMIN C ON THYROID AND SUPRARENALS:
1. Deficiency of vitamin C leads to an increase in the
amount of secretion by the thyroid. °Thus the antiscorbubic
factor has an action on the thyroid similar to but
less in amount than vitamins A and B.
2. vitamin C like the other water soluble factor B is
not antitoxic to acetonitril.
3. Adrenaline content of the suprarenals is diminished
by a deficiency of vitamin C: in this respect it resembles
vitamin B.
4. vitamin C deficiency does not lead to any appreciable
change in the lipoid content of the suprarenal cortex.III. EFFECTS OF VITAMIN D ON THYROID AND SUPRARENALS:
1. Vitamin D behaves towards the thyroid exactly as
vitamins A,B and C. It promotes a resting condition of
the gland and in this respect, substances like cod liver
oil and irradiated milk which contain the antirachitic
factor, or ultra violet rays which produce it, contribute
towards the resting phase, proportional to the amount
of the antirachitic substance they contain or are capable
of producing. Deficiency of vitamin D leads to an actively
secreting condition of the gland.
2. vitamin D, although it is a fat soluble factor and is
almost always closely associated with vitamin A, is not
antitoxic to acetonitril.
3. deficiency of vitamin D leads to a slight diminution
in the adrenaline content of the suprarenal glands.
4. ultra violet radiation leads to a scanty amount of
adrenaline in the medulla of the suprarenals. This effect
is probably due to the direct effect of the rays rather
than to the chemical substance vitamin D, which is produced
under their influence.
5. vitamin D deficiency alone does not lead to any appreciable
difference in the lipoid content of the cortex of
the suprarenal glands
Ultrafast laser inscribed waveguide lattice in glass for direct observation of transverse localization of light
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