26 research outputs found
Electromagnetic Lifshitz formula for small-width mirrors from functional determinants
We extend a recently proposed Quantum Field Theory (QFT) approach to the
Lifshitz formula, originally implemented for a real scalar field, to the case
of a fluctuating vacuum electromagnetic (EM) field, coupled to two flat,
parallel mirrors. The general result is presented in terms of the invariants of
the vacuum polarization tensors due to the media on each mirror. We consider
mirrors that have small widths, with the zero-width limit as a particular case.
We apply the latter to models involving graphene sheets, obtaining results
which are consistent with previous ones.Comment: 15 pages, 2 figure
Quantum dissipative effects in graphene-like mirrors
We study quantum dissipative effects due to the accelerated motion of a
single, imperfect, zero-width mirror. It is assumed that the microscopic
degrees of freedom on the mirror are confined to it, like in plasma or graphene
sheets. Therefore, the mirror is described by a vacuum polarization tensor
concentrated on a time-dependent surface. Under certain
assumptions about the microscopic model for the mirror, we obtain a rather
general expression for the Euclidean effective action, a functional of the
time-dependent mirror's position, in terms of two invariants that characterize
the tensor . The final result can be written in terms of the
TE and TM reflection coefficients of the mirror, with qualitatively different
contributions coming from them. We apply that general expression to derive the
imaginary part of the `in-out' effective action, which measures dissipative
effects induced by the mirror's motion, in different models, in particular for
an accelerated graphene sheet.Comment: 8 pages, 2 figures. Minor changes, version to be published in Phys.
Rev.
A digital waveguide-based approach for Clavinet modeling and synthesis
The Clavinet is an electromechanical musical instrument produced in the mid-twentieth century. As is the case for other vintage instruments, it is subject to aging and requires great effort to be maintained or restored. This paper reports analyses conducted on a Hohner Clavinet D6 and proposes a computational model to faithfully reproduce the Clavinet sound in real time, from tone generation to the emulation of the electronic components. The string excitation signal model is physically inspired and represents a cheap solution in terms of both computational resources and especially memory requirements (compared, e.g., to sample playback systems). Pickups and amplifier models have been implemented which enhance the natural character of the sound with respect to previous work. A model has been implemented on a real-time software platform, Pure Data, capable of a 10-voice polyphony with low latency on an embedded device. Finally, subjective listening tests conducted using the current model are compared to previous tests showing slightly improved results
On the static Casimir effect with parity-breaking mirrors
We study the Casimir interaction energy due to the vacuum fluctuations of the electromagnetic (EM) field in the presence of two mirrors, described by -dimensional, generally nonlocal actions, which may contain both parity-conserving and parity-breaking terms. We compare the results with the ones corresponding to ChernâSimons boundary conditions and evaluate the interaction energy for several particular situations
Development and single laboratory validation of a targeted liquid chromatography-triple quadrupole mass spectrometry-based method for the determination of insulin like growth factor-1 in different types of milk samples
A simple and reliable targeted liquid chromatography-electrospray-tandem mass spectrometry (LC-MS/MS) method was developed and validated through the selection of two biomarker peptides for the identification and determination of bovine insulin like growth factor-1 (IGF-1) in milk samples. Two urea-based sample extraction procedures were tested. The validation results provided detection limits at the 1â5 ng IGF-1/mL level as a function of the milk matrix, precision ranged from 3 to 8% and the method accuracy in the different milk matrices was assured. Finally, IGF-1 was measured in milk samples obtained by treatment with eleven different technological processes: IGF-1 concentrations were spread over a wide range from 11.2 ± 0.3 ng/mL to 346 ± 8 ng/mL with a median of 57.0 ± 0.2 ng/mL. The highest amount of IGF-1 was found in fresh whole milk samples and no significant correlation was found between the total milk protein content and the IGF-1 concentration level
Biocompatible 3d printed chitosan-based scaffolds containing α-tocopherol showing antioxidant and antimicrobial activity
Active dressings acting on multiple fronts are requested in the field of care for chronic skin ulcers in order to ameliorate patient compliance and tissue restoration. Currently, three-dimensional polymeric hydrogels are widely investigated; however, no prototypes aiming to control oxidative stress and bacterial proliferation in the wound bed have been developed up until now. The present work describes the formulation of a novel chitosan-based printable material containing α-tocopherol at stable dosages to obtain reproducible 3D scaffolds possessing antioxidant and antimicrobial activity without the use of organic solvents. Stability assays mimicking the manufacturing process and storage conditions reveal no significant drug loss. Chemico-physical characterizations including porosity and behavior after dehydration/hydration demonstrate that the dressings are highly porous, can be dehydrated up to 80%, and can recover more than 90% of water upon 1 h of rehydration. Elasticity determined by stress/strain tests was higher than human skin and was sufficiently resistant for potential clinical manipulation. Footage of fibroblasts in in vitro cultures demonstrated the biocompatibility of the constructs over 28 days. Finally, scaffolds loaded with α-tocopherol showed dose-dependent antioxidant activity (up to 80% in less than 1 h), while antimicrobial action versus multi-drug resistant strains of Pseudomonas aeruginosa and Staphilococcus aureus was assessed by inhibition rings obtained through the KirbyâBauer technique. The proposed hydrogels can be useful as dressings for the treatment of chronically infected wounds
P1081: PET-ADAPTED THERAPY AFTER THREE CYCLES OF ABVD FOR ALL STAGES OF HODGKIN LYMPHOMA: LONG TERM FOLLOW UP OF THE GATLA LH-05 TRIAL
An Audio-Visual Method for Room Boundary Estimation and Material Recognition
In applications such as virtual and augmented reality, a plausible and coherent audio-visual reproduction can be achieved by deeply understanding the reference scene acoustics. This requires knowledge of the scene geometry and related materials. In this paper, we present an audio-visual approach for acoustic scene understanding. We propose a novel material recognition algorithm, that exploits information carried by acoustic signals. The acoustic absorption coefficients are selected as features. The training dataset was constructed by combining information available in the literature, and additional labeled data that we recorded in a small room having short reverberation time (RT60). Classic machine learning methods are used to validate the model, by employing data recorded in five rooms, having different sizes and RT60s. The estimated materials are utilized to label room boundaries, reconstructed by a visionbased method. Results show 89 % and 80 % agreement between the estimated and reference room volumes and materials, respectively