1,635 research outputs found
Hodge Dualities on Supermanifolds
We discuss the cohomology of superforms and integral forms from a new
perspective based on a recently proposed Hodge dual operator. We show how the
superspace constraints (a.k.a. rheonomic parametrisation) are translated from
the space of superforms to the space of integral forms
where , is the bosonic dimension of the
supermanifold and its fermionic dimension. We dwell on the relation between
supermanifolds with non-trivial curvature and Ramond-Ramond fields, for which
the Laplace-Beltrami differential, constructed with our Hodge dual, is an
essential ingredient. We discuss the definition of Picture Lowering and Picture
Raising Operators (acting on the space of superforms and on the space of
integral forms) and their relation with the cohomology. We construct
non-abelian curvatures for gauge connections in the space and
finally discuss Hodge dual fields within the present framework.Comment: 35 page
Mode space approach for tight-binding transport simulations in graphene nanoribbon field-effect transistors including phonon scattering
In this paper, we present a mode space method for atomistic non-equilibrium
Green's function simulations of armchair graphene nanoribbon FETs that includes
electron-phonon scattering. With reference to both conventional and tunnel FET
structures, we show that, in the ideal case of a smooth electrostatic
potential, the modes can be decoupled in different groups without any loss of
accuracy. Thus, inter-subband scattering due to electron-phonon interactions is
properly accounted for, while the overall simulation time considerably improves
with respect to real-space, with a speed-up factor of 40 for a 1.5-nm-wide
device. Such factor increases with the square of the device width. We also
discuss the accuracy of two commonly used approximations of the scattering
self-energies: the neglect of the off-diagonal entries in the mode-space
expressions and the neglect of the Hermitian part of the retarded self-energy.
While the latter is an acceptable approximation in most bias conditions, the
former is somewhat inaccurate when the device is in the off-state and optical
phonon scattering is essential in determining the current via band-to-band
tunneling. Finally, we show that, in the presence of a disordered potential, a
coupled mode space approach is necessary, but the results are still accurate
compared to the real-space solution.Comment: 10 pages, 12 figures. Copyright (2013) American Institute of Physics.
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prior permission of the author and the American Institute of Physic
Boosting the voltage gain of graphene FETs through a differential amplifier scheme with positive feedback
We study a possible circuit solution to overcome the problem of low voltage
gain of short-channel graphene FETs. The circuit consists of a fully
differential amplifier with a load made of a cross-coupled transistor pair.
Starting from the device characteristics obtained from self-consistent
ballistic quantum transport simulations, we explore the circuit parameter space
and evaluate the amplifier performance in terms of dc voltage gain and voltage
gain bandwidth. We show that the dc gain can be effectively improved by the
negative differential resistance provided by the cross-coupled pair. Contact
resistance is the main obstacle to achieving gain bandwidth products in the
terahertz range. Limitations of the proposed amplifier are identified with its
poor linearity and relatively large Miller capacitance.Comment: 19 pages, 10 figure
The antimicrobial photodynamic therapy in the treatment of peri-implantitis
The aim of this study is to demonstrate the effectiveness of addition of the antimicrobial photodynamic therapy to
the conventional approach in the treatment of peri-implantitis. Materials and Methods. Forty patients were randomly assigned
to test or control groups. Patients were assessed at baseline and at six (T1), twelve (T2), and twenty-four (T3) weeks recording
plaque index (PlI), probing pocket depth (PPD), and bleeding on probing (BOP); control group received conventional periodontal
therapy, while test group received photodynamic therapy in addition to it. Result. Test group showed a 70% reduction in the plaque
index values and a 60% reduction in PD values compared to the baseline. BOP and suppuration were not detectable. Control
group showed a significative reduction in plaque index and PD. Discussion. Laser therapy has some advantages in comparison to
traditional therapy, with faster and greater healing of the wound. Conclusion. Test group showed after 24 weeks a better value in
terms of PPD, BOP, and PlI, with an average pocket depth value of 2 mm, if compared with control group (3 mm).Our results suggest
that antimicrobial photodynamic therapy with diode laser and phenothiazine chloride represents a reliable adjunctive treatment
to conventional therapy. Photodynamic therapy should, however, be considered a coadjuvant in the treatment of peri-implantitis
associated with mechanical (scaling) and surgical (grafts) treatments
-Algebra from Supermanifolds
Inspired by the analogy between different types of differential forms on
supermanifolds and string fields in superstring theory, we construct new
multilinear non-associative products of forms which yield an
-algebra.Comment: 29 pages, no figure
Reconfiguration Viewer
Grassi PR, Pohl C, Porrmann M. Reconfiguration Viewer. In: Design Automation and Test in Europe, DATE University Booth. Nice, France; 2009.The proposed approach allows debugging of partial dynamic reconfiguration. It shows where and when FPGA areas are reconfigured at runtime
Mouthwash Based on Ozonated Olive Oil in Caries Prevention: A Preliminary In-Vitro Study
(1) Background: Ozone (O3) proved to oxidize organic and inorganic compounds, and its efficacy against bacteria, viruses and fungi plasma membranes was of interest. Ozone vehicle can be a gaseous form, ozonated water or ozonized oil. The aim of this in-vitro study was to evaluate the efficacy of ozonated olive oil against Streptococcus mutans. (2) Methods: Two different commercial mouthwashes were tested: Ialozon Blu (IB) (Gemavip, Cagliari, Italy), with ozonated olive oil, and Ialozon Rose (IR) (Gemavip, Cagliari, Italy), with ozonated olive oil, hyaluronic acid and vitamin E. All formulates were analyzed in a dilution range from 2- to 256-folds in saline solution, as to reproduce the salivary dilution. Streptococcus mutans CIP103220 strain was used for the antimicrobial susceptibility test, and the Kirby-Bauer inhibition method was performed to evaluate the Minimum Inhibitory (MIC), Minimum Bactericidal (MBC), and Minimum Biofilm Inhibitory Concentration (MBIC). (3) Results: Both formulates showed the same antimicrobial activity. MIC, MBC, and MBIC were observed for dilution factors of 1/32, 1/8 and 1/8, respectively. The mean value of inhibition zone diameter was 16.5 mm for IB, and 18 mm for IR. (4) Conclusions: The results suggested that ozonized olive oil formulates were able to inactivate Streptococcus mutans avoiding the salivary dilution effect in the oral cavity
Contact-induced negative differential resistance in short-channel graphene FETs
In this work, we clarify the physical mechanism for the phenomenon of
negative output differential resistance (NDR) in short-channel graphene FETs
(GFETs) through non-equilibrium Green's function (NEGF) simulations and a
simpler semianalytical ballistic model that captures the essential physics.
This NDR phenomenon is due to a transport mode bottleneck effect induced by the
graphene Dirac point in the different device regions, including the contacts.
NDR is found to occur only when the gate biasing produces an n-p-n or p-n-p
polarity configuration along the channel, for both positive and negative
drain-source voltage sweep. In addition, we also explore the impact on the NDR
effect of contact-induced energy broadening in the source and drain regions and
a finite contact resistance.Comment: 7 pages, 9 figure
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