1,516 research outputs found
On the Incompatibility of Standard Quantum Mechanics and the de Broglie-Bohm Theory
It is shown that the de Broglie-Bohm quantum theory of multi-particle systems
is incompatible with the standard quantum theory of such systems unless the
former is ergodic. A realistic experiment is suggested to distinguish between
the two theories.Comment: A few technical changes incorporated in section V without any change
in conclusion
Spin-dependent direct gap emission in tensile-strained Ge films on Si substrates
The circular polarization of direct gap emission of Ge is studied in
optically-excited tensile-strained Ge-on-Si heterostructures as a function of
doping and temperature. Owing to the spin-dependent optical selection rules,
the radiative recombinations involving strain-split light (cG-LH) and heavy
hole (cG-HH) bands are unambiguously resolved. The fundamental cG-LH transition
is found to have a low temperature circular polarization degree of about 85%
despite an off-resonance excitation of more than 300 meV. By photoluminescence
(PL) measurements and tight binding calculations we show that this
exceptionally high value is due to the peculiar energy dependence of the
optically-induced electron spin population. Finally, our observation of the
direct gap doublet clarifies that the light hole contribution, previously
considered to be negligible, can dominate the room temperature PL even at low
tensile strain values of about 0.2%
Duality in Left-Right Symmetric Seesaw Mechanism
We consider type I+II seesaw mechanism, where the exchanges of both
right-handed neutrinos and isotriplet Higgs bosons contribute to the neutrino
mass. Working in the left-right symmetric framework and assuming the mass
matrix of light neutrinos and the Dirac-type Yukawa couplings to be
known, we find the triplet Yukawa coupling matrix , which carries the
information about the masses and mixing of the right-handed neutrinos. We show
that in this case there exists a duality: for any solution , there is a dual
solution , where is the VEV of the triplet Higgs.
Thus, unlike in pure type I (II) seesaw, there is no unique allowed structure
for the matrix . For lepton generations the number of solutions is
. We develop an exact analytic method of solving the seesaw non-linear
matrix equation for .Comment: 4 pages, revtex, small clarifications added, title changed to match
published versio
A constant dark matter halo surface density in galaxies
We confirm and extend the recent finding that the central surface density
r_0*rho_0 galaxy dark matter halos, where r_0 and rho_0 are the halo core
radius and central density, is nearly constant and independent of galaxy
luminosity. Based on the co-added rotation curves of about 1000 spiral
galaxies, mass models of individual dwarf irregular and spiral galaxies of late
and early types with high-quality rotation curves and, galaxy-galaxy weak
lensing signals from a sample of spiral and elliptical galaxies, we find that
log(r_0*rho_0) = 2.15 +- 0.2, in units of log(Msol/pc^2). We also show that the
observed kinematics of Local Group dwarf spheroidal galaxies are consistent
with this value. Our results are obtained for galactic systems spanning over 14
magnitudes, belonging to different Hubble Types, and whose mass profiles have
been determined by several independent methods. In the same objects, the
approximate constancy of rho_0*r_0 is in sharp contrast to the systematical
variations, by several orders of magnitude, of galaxy properties, including
rho_0 and central stellar surface density.Comment: Accepted for publication in MNRAS. 9 pages, 4 figure
Strategy for the development of a new stick formula without microplastics
Plastic is a synthetic, malleable, and durable material that has been used for various applications since its invention in the late 19th century. During its very long-time degradation process, mechanical and/or photochemical processes fragment plastic into increasingly smaller fragments called microplastics (MPs). In the cosmetic field, MPs are directly added to many products for various functions, including to exploit their exfoliating and structuring power. Unfortunately, it has been realized that MPs are not retained in purification plants and therefore end up in the aquatic environment causing a high problem of environmental pollution. Polyethene (PE) is the most widely used MP in cosmetics due to its use as a structuring agent, to provide consistency to formulations and as a key ingredient in lipsticks and mascaras. Given the limitations imposed by regulations and the growing demand from consumers for chemical-free and eco-friendly products, the common synthetic and petroleum-based waxes used in lipstick formulations, such as PE, must necessarily be replaced by natural waxes of plant origin. In this paper we report the development of a chemical-free and eco-friendly cosmetic stick. To achieve the goal, it was necessary to study the compatibility of the ABWAX® Revowax, natural alternative to PE, with oils and colours to predict the behaviour of these structuring waxes in more complex systems. Through a systematic comparative study, the two waxes showed similar thermal characteristics and showed similar penetration curves, presenting overall comparable performance in the MP-free finished product. We can therefore consider ABWAX® Revowax natural wax a valid alternative to PE
Aquaporins influence seed dormancy and germination in response to stress
Aquaporins influence water flow in plants, yet little is known of their involvement in the water‐driven process of seed germination. We therefore investigated their role in seeds in the laboratory and under field and global warming conditions. We mapped the expression of tonoplast intrinsic proteins (TIPs) during dormancy cycling and during germination under normal and water stress conditions. We found that the two key tonoplast aquaporins, TIP3;1 and TIP3;2, which have previously been implicated in water or solute transport, respectively, act antagonistically to modulate the response to abscisic acid, with TIP3;1 being a positive and TIP3;2 a negative regulator. A third isoform, TIP4;1, which is normally expressed upon completion of germination, was found to play an earlier role during water stress. Seed TIPs also contribute to the regulation of depth of primary dormancy and differences in the induction of secondary dormancy during dormancy cycling. Protein and gene expression during annual cycling under field conditions and a global warming scenario further illustrate this role. We propose that the different responses of the seed TIP contribute to mechanisms that influence dormancy status and the timing of germination under variable soil conditions
bullous wells syndrome associated with non hodgkin s lymphocytic lymphoma
3/µl; eosinophils 14.3% neutrophils 48%, lymphocytes 31.2%, monocytes 6.5%, basophils 0.2%), total immunoglobulin E (IgE) = 751 IU/ml, C-reactive protein (CRP) 1.25 mg/dl, erythrocyte sedimentation rate (ESR) in the first hour 60 mm; viral markers (Epstein Barr virus, cytomegalovirus, hepatitis A, B and C virus), cryoglobulin, ANCA, LAC, ANA, ENA and anti-DNA antibodies were all negative. Histopathological examination of the lesion on the left leg showed an epidermis characterized by multiple, sometimes confluent vesicles containing serum and eosinophil granulocytes. The underlying papillary dermis was markedly oedematous, with focal and minimal erythrocytic extravasations and an interstitial eosinophil granulocytic infiltrate. The reticular dermis was infiltrated by a large number of prevalently perivascular lymphocytic elements and numerous perivascular and interstitial eosinophil granulocytes, which also extended along the interlobular hypodermal septa and, to a lesser extent, the hypodermic lobules. The reticular dermis also showed some small and isolated flame figures (Fig. 2). The diagnosis of Wells' syndrome was made on the basis of the clinical picture and the histological findings, together with a negative direct immunofluorescence test (5). Having excluded pharmacological, infective, vasculitic and inflammatory causes, the subsequent instrumental and laboratory investigations were aimed at identifying a possible relapse of the patient's previous neoplastic disease. Complete abdominal ultrasonography, chest radiography and colonoscopy were negative, as was a search for tumour markers. The physical examination findings of numerous swollen inguinal and axillary lymph nodes therefore drew our attention to a possible underlying lymphoproliferative disease, and a subsequent lymph node biopsy revealed a picture compatible with a diffuse, small-cell non-Hodgkin's B lymphoma/ B-cell CLL, which was confirmed by a bone marrow biopsy
Mid-Infrared Plasmonic Platform Based on n-Doped Ge-on-Si: Molecular Sensing with Germanium Nano-Antennas on Si
CMOS-compatible, heavily-doped semiconductor
films are very promising for applications in mid-infrared
plasmonic devices because the real part of their dielectric
function is negative and broadly tunable in this wavelength
range. In this work we investigate n-type doped germanium
epilayers grown on Si substrates. We design and realize Ge nanoantennas
on Si substrates demonstrating the presence of localized
plasmon resonances, and exploit them for molecular sensing in
the mid-infrared
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