982 research outputs found
Small-signal amplifier based on single-layer MoS2
In this Letter we demonstrate the operation of an analog small-signal
amplifier based on single-layer MoS2, a semiconducting analogue of graphene.
Our device consists of two transistors integrated on the same piece of
single-layer MoS2. The high intrinsic band gap of 1.8 eV allows MoS2-based
amplifiers to operate with a room temperature gain of 4. The amplifier
operation is demonstrated for the frequencies of input signal up to 2 kHz
preserving the gain higher than 1. Our work shows that MoS2 can effectively
amplify signals and that it could be used for advanced analog circuits based on
two-dimensional materials.Comment: Submitted version of the manuscrip
Consistent Poverty across the EU
This paper investigates consistent poverty defined as living at the risk of both income poverty and material deprivation. Using EU-SILC data from 2012, we analyze patterns of consistent poverty across EU member states and in the main individual and household-level factors predicting this status. According to our results, consistent poverty is present in all Member States, although its extent displays fairly large cross-country differences. The share of those living in consistent poverty is highest in the New Member States and the Southern countries. Living in consistent poverty is associated with several household characteristics. Those living in consistent poverty are more likely than those in severe material deprivation or income poverty to live in bigger families, to have lower levels of education, and to have weak or non-existent links to the labor market. In addition, they evaluate their financial circumstances as being worse, ceteris paribus
The Sorption Behavior of Cs+ ion On Clay Minerals and Zeolite in Radioactive Waste Managemen: Sorption Kinetics and Themodynamics
Cataloged from PDF version of article.In this work, Cs+ ion sorption on some clays and zeolite were investigated. Cs-137 was used as a tracer. Activities were measured with a NaI crystal gamma counter. The particle size distribution was determined by a laser sizer. Surface area of the particles were determined by BET (Brunauer, Emmett and Teller method). Structure analysis was made by using X-ray diffraction. The chemical compositions of the solid samples were determined using a ICAP-OE spectrometer. Kinetic and thermodynamic parameters were determined. Due to very high uptake results; clay and zeolite can be proposed as a good sorbents in waste management considerations
Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects
Here, we present a numerical post-processing method for removing the effect
of anti-symmetric residual aberrations in high-resolution transmission electron
microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based
on applying the same aberrations with the opposite phase to the Fourier
transform of the recorded image intensity and subsequently inverting the
Fourier transform. We present the theoretical justification of the method and
its verification based on simulated images in the case of low-order
anti-symmetric aberrations. Ultimately the method is applied to experimental
hardware aberration-corrected HRTEM images of single-layer graphene and MoSe2
resulting in images with strongly reduced residual low-order aberrations, and
consequently improved interpretability. Alternatively, this method can be used
to estimate by trial and error the residual anti-symmetric aberrations in HRTEM
images of weakly scattering objects
Production of photon states from Î-atoms in a cavity
We analyse the system of Î-atoms in a cavity QED of semi-transparent mirror and driven by laser fields. We derive effective models and connect concepts (photonic flux, input-output operators, photonic state) characterizing the propagation of the resulting leaking photons. We propose an atom-cavity non-resonant scheme for single-and 2-photons generation. The pulse shapes of outgoing single photons are tailored using a specifically designed driving field envelope. For the production of 2-photon states, two trapped atoms are used with two driving pulses. Their pulse shapes are characterized and it is shown that the multiphoton outgoing photonic states cannot be Fock states, since the photons are not generated strictly simultaneously
Stimulated Raman Adiabatic Passage (STIRAP) Among Degenerate-Level Manifolds
We examine the conditions needed to accomplish stimulated Raman adiabatic
passage (STIRAP) when the three levels (g, e and f) are degenerate, with
arbitrary couplings contributing to the pump-pulse interaction (g - e) and to
the Stokes-pulse interaction (e-f). We show that in general a sufficient
condition for complete population removal from the g set of degenerate states
for arbitrary, pure or mixed, initial state is that the degeneracies should not
decrease along the sequence g, e and f. We show that when this condition holds
it is possible to achieve the degenerate counterpart of conventional STIRAP,
whereby adiabatic passage produces complete population transfer. Indeed, the
system is equivalent to a set of independent three-state systems, in each of
which a STIRAP procedure can be implemented. We describe a scheme of unitary
transformations that produces this result. We also examine the cases when this
degeneracy constraint does not hold, and show what can be accomplished in those
cases. For example, for angular momentum states when the degeneracy of the g
and f levels is less than that of the e level we show how a special choice for
the pulse polarizations and phases can produce complete removal of population
from the g set. Our scheme can be a powerful tool for coherent control in
degenerate systems, because of its robustness when selective addressing of the
states is not required or impossible. We illustrate the analysis with several
analytically solvable examples, in which the degeneracies originate from
angular momentum orientation, as expressed by magnetic sublevels.Comment: 21 pages, 17 figure
Dehydroepiandrosterone sulfate (DHEAS) is neuroprotective when administered either before or after injury in a focal cortical cold lesion model
Dehydroepiandrosterone and its sulfate (DHEAS) are sex hormone precursors that exert marked neurotrophic and/or neuroprotective activity in the central nervous system. The
present study evaluated the effects of DHEAS and 17ïżœ-estradiol (E2) in a focal cortical cold lesion model, in which DHEAS (50 mg/kg, sc) and E2 (35 mg/kg, sc) were administered either as pretreatment (two subsequent injections 1 d and 1 h before lesion induction) or posttreatment (immediately after lesion induction). The focal cortical cold lesion was induced in the primary motor cortex by means of a cooled copper cylinder placed directly onto the cortical surface. One hour later, the animals were killed, the brains cut into 0.4-mm-thick slices, and the sections stained with 1% triphenyltetrazolium chloride.
The volume of the hemispheric lesion was calculated for
each animal. The results demonstrated that the lesion area
was significantly attenuated in both the DHEAS- and E2- preand posttreated groups and that in the presence of letrozole, a nonsteroidal aromatase inhibitor, no neuroprotection was observed, suggesting that the beneficial effect of DHEAS on the cold injury might depend on the conversion of DHEAS to E2 within the brain. It is concluded that even a single posttraumatic administration of DHEAS may be of substantial therapeutic benefit in the treatment of focal brain injury with vasogenic edema
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