2,354 research outputs found

### Non-commutative phase and the unitarization of GL_{p,q}(2)

In this paper, imposing hermitian conjugate relations on the two-parameter
deformed quantum group GL_{p,q}(2) is studied. This results in a
non-commutative phase associated with the unitarization of the quantum group.
After the achievement of the quantum group U_{p,q}(2) with pq real via a
non-commutative phase, the representation of the algebra is built by means of
the action of the operators constituting the U_{p,q}(2) matrix on states.Comment: 7 page

### String Theory in the Penrose Limit of AdS_2 x S^2

The string theory in the Penrose limit of AdS_2 x S^2 is investigated. The
specific Penrose limit is the background known as the Nappi-Witten spacetime,
which is a plane-wave background with an axion field. The string theory on it
is given as the Wess-Zumino-Novikov-Witten (WZNW) model on non-semi-simple
group H_4. It is found that, in the past literature, an important type of
irreducible representations of the corresponding algebra, h_4, were missed. We
present this "new" representations, which have the type of continuous series
representations. All the three types of representations of the previous
literature can be obtained from the "new" representations by setting the
momenta in the theory to special values. Then we realized the affine currents
of the WZNW model in terms of four bosonic free fields and constructed the
spectrum of the theory by acting the negative frequency modes of free fields on
the ground level states in the h_4 continuous series representation. The
spectrum is shown to be free of ghosts, after the Virasoro constraints are
satisfied. In particular we argued that there is no need for constraining one
of the longitudinal momenta to have unitarity. The tachyon vertex operator,
that correspond to a particular state in the ground level of the string
spectrum, is constructed. The operator products of the vertex operator with the
currents and the energy-momentum tensor are shown to have the correct forms,
with the correct conformal weight of the vertex operator.Comment: 30 pages, Latex, no figure

### Characterization of an embedded RF-MEMS switch

An RF-MEMS capacitive switch for mm-wave integrated circuits, embedded in the BEOL of 0.25ÎĽm BiCMOS process, has been characterized. First, a mechanical
model based on Finite-Element-Method (FEM) was developed by taking the residual stress of the thin film membrane into account. The pull-in voltage and the capacitance values obtained with the mechanical model agree very well with the
measured values. Moreover, S-parameters were extracted using Electromagnetic (EM) solver. The data observed in this way also agree well with the experimental ones measured up to 110GHz. The developed RF model was applied to a transmit/receive (T/R) antenna switch design. The results proved the feasibility of using the FEM model in circuit simulations for the development of RF-MEMS switch embedded, single-chip multi-band RF ICs

### Optical microsensor for counting food substance particles in lab-on-a-chips

Integrated optical detection is considered to be an important operation in lab-on-a-chips. This paper presents an optical fiber-based micro-sensor that is capable of detecting food substance particles in a lab-on-a-chip. The system consists of a microcontroller and associated circuitry, a laser emitter, a laser receiver, fiber optic cables, a microfluidics chip, and the food substance samples to be tested. When the particles flow through the microfluidic channel in the chip, the receiver’s output voltage varies due to the particles blocking the passage of the laser ray. The changes in the collected signals are analyzed to count the number of particles. Experiments are conducted on several food substance samples including talcum powder, ground ginger, and soy sauce. The experimental results are presented and discussed

### Biological Cell Discrimination Based on Their High Frequency Dielectropheretic Signatures at UHF Frequencies

2017 International Microwave Symposium paper entitled "Biological Cell Discrimination Based on Their High Frequency Dielectropheretic Signatures at UHF Frequencies". Honolulu June 4-9th 2017. Amended version: see additional notes.This version amends the wrong naming in the previous record: the conference is the IEEE IMS 2017, not 2018

### Improving the Surface Quality and Mechanical Properties of Selective Laser Sintered PA2200 Components by the Vibratory Surface Finishing Process

This paper attempts to improve the physical and mechanical properties of selective laser sintered polyamide PA2200
components through a vibratory surface finishing process by inducing severe plastic deformation at the outer surface
layers. The industrial target of additive manufacturing components is to obtain structures having surface roughness,
hardness, and other mechanical properties equivalent to or better than those produced conventionally. Compared to
the as-built SLS PA2200 samples, vibratory surface finishing treated specimens exhibited a smooth surface microstructure
and more favorable roughness, hardness, and tensile strength. Also, the duration of the vibratory surface finishing
process showed a further improvement in the surface roughness and hardness of the SLS samples. Compared to the asbuilt
state, the roughness and hardness of the surface-treated samples improved by almost 90% and 15%, respectively.
Consequently, microstructural analysis indicates that lower surface roughness and enhanced surface hardness is a crucial
factor in influencing the overall tensile strength of SLS-PA2200 components. We consider that the combination of VSF
and SLS processes can successfully handle a wide range of potential applications. This study also highlights the efficiency
and applicability of the vibratory surface finishing process to other additive manufacturing processes and materials

### Development of Silver Ion Doped Antibacterial Clays and Investigation of Their Antibacterial Activity

Kaolinite, sepiolite, and clinoptilolite were used as carriers to develop antibacterial materials. The materials were enriched in sodium by ion exchange. Silver ion exchange by silver nitrate followed by phosphoric acid treatment enabled the controlled release of silver. The antibacterial function of the materials was investigated by halo test and the amount of silver released was investigated by energy dispersive X-ray spectroscopy. The enhanced antibacterial efficiency was obtained by minimizing the silver release which further provided longevity to the material and prevented the health risks posed by excess silver release

### Point Interaction in two and three dimensional Riemannian Manifolds

We present a non-perturbative renormalization of the bound state problem of n
bosons interacting with finitely many Dirac delta interactions on two and three
dimensional Riemannian manifolds using the heat kernel. We formulate the
problem in terms of a new operator called the principal or characteristic
operator. In order to investigate the problem in more detail, we then restrict
the problem to one particle sector. The lower bound of the ground state energy
is found for general class of manifolds, e.g., for compact and Cartan-Hadamard
manifolds. The estimate of the bound state energies in the tunneling regime is
calculated by perturbation theory. Non-degeneracy and uniqueness of the ground
state is proven by Perron-Frobenius theorem. Moreover, the pointwise bounds on
the wave function is given and all these results are consistent with the one
given in standard quantum mechanics. Renormalization procedure does not lead to
any radical change in these cases. Finally, renormalization group equations are
derived and the beta-function is exactly calculated. This work is a natural
continuation of our previous work based on a novel approach to the
renormalization of point interactions, developed by S. G. Rajeev.Comment: 43 page

### Non-conformal Hydrodynamics in Einstein-dilaton Theory

In the Einestein-dilaton theory with a Liouville potential parameterized by
$\eta$, we find a Schwarzschild-type black hole solution. This black hole
solution, whose asymptotic geometry is described by the warped metric, is
thermodynamically stable only for $0 \le \eta < 2$. Applying the gauge/gravity
duality, we find that the dual gauge theory represents a non-conformal thermal
system with the equation of state depending on $\eta$. After turning on the
bulk vector fluctuations with and without a dilaton coupling, we calculate the
charge diffusion constant, which indicates that the life time of the quasi
normal mode decreases with $\eta$. Interestingly, the vector fluctuation with
the dilaton coupling shows that the DC conductivity increases with temperature,
a feature commonly found in electrolytes.Comment: 27 pages and 2 figures, published in JHE

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