Fluctuation-dissipation relations of a tunnel junction driven by a quantum circuit

We derive fluctuation-dissipation relations for a tunnel junction driven through a resonator displaying strong quantum fluctuations. We find that the fluctuation-dissipation relations derived for classical external drives hold, provided the effect of the circuit's quantum fluctuations is incorporated into the modified nonlinear current voltage characteristics. We also demonstrate that all quantities measured under a time dependent bias can be reconstructed from their values measured under a dc bias using photoassisted tunneling relations. We confirm these predictions by implementing the circuit and measuring the dc current through the junction, its high frequency admittance, and its current noise at the frequency of the resonator.

Transcriptional control of collagen I gene expression

Cardiac fibrosis is the pathological remodeling of the extracellular matrix (ECM) in response to stresses such as pressure overload or injury. While initially adaptive, myocardial remodeling and subsequent fibrosis causes increased wall stiffness, arrhythmias, cardiac dysfunction, and eventually heart failure. Though the disease processes and origins may differ, excess deposition of fibrillar collagens type I and III characterizes fibrosis in the heart, lungs, kidneys, liver, and skin. Under normal physiological conditions, high tensile strength collagen fibers maintain cardiac structural integrity, connect individual cardiomyocytes, transmit contractile force, and resist deformation and rupture of the ventricle during systole. Various factors contribute to the development of fibrosis by altering expression of ECM genes, including increased synthesis of pro-inflammatory cytokines, alterations in the levels of circulating hormones, and mechanical strain resulting from ECM degradation. This review focuses on the transcriptional mechanisms governing expression of the major cardiac collagen, type I. Key cis- and trans-acting regulators of collagen I gene expression are discussed. Surprisingly, relatively few transcriptional regulators of collagen synthesis have been identified specifically in cardiac fibroblasts. However, key players have been identified in other tissue and cell types, and are important to consider in elucidating the molecular mechanisms underpinning collagen gene expression in the heart in both health and disease.

Carrier drift velocity and edge magnetoplasmons in graphene

We investigate electron dynamics at the graphene edge by studying the propagation of collective edge magnetoplasmon excitations. By timing the travel of narrow wave packets on picosecond time scales around exfoliated samples, we find chiral propagation with low attenuation at a velocity that is quantized on Hall plateaus. We extract the carrier drift contribution from the edge magnetoplasmon propagation and find it to be slightly less than the Fermi velocity, as expected for an abrupt edge. We also extract the characteristic length for Coulomb interaction at the edge and find it to be smaller than that for soft depletion-edge systems.

Process design for wastewater treatment: catalytic ozonation of organic pollutants

Emerging micropollutants have been recently the target of interest for their potential harmful effects in the environment and their resistance to conventional water treatments. Catalytic ozonation is an advanced oxidation process consisting of the formation of highly reactive radicals from the decomposition of ozone promoted by a catalyst. Nanocarbon materials have been shown to be effective catalysts for this process, either in powder form or grown on the surface of a monolithic structure. In this work, carbon nanofibers grown on the surface of a cordierite honeycomb monolith are tested as catalyst for the ozonation of five selected micropollutants: atrazine (ATZ), bezafibrate, erythromycin, metolachlor, and nonylphenol. The process is tested both in laboratorial and real conditions. Later on, ATZ was selected as a target pollutant to further investigate the role of the catalytic material. It is shown that the inclusion of a catalyst improves the mineralization degree compared to single ozonation.

Quantum coherence engineering in the integer quantum Hall regime

We present an experiment where the quantum coherence in the edge states of the integer quantum Hall regime is tuned with a decoupling gate. The coherence length is determined by measuring the visibility of quantum interferences in a Mach-Zehnder interferometer as a function of temperature, in the quantum Hall regime at a filling factor 2. The temperature dependence of the coherence length can be varied by a factor of 2. The strengthening of the phase coherence at finite temperature is shown to arise from a reduction of the coupling between copropagating edge states. This opens the way for a strong improvement of the phase coherence of quantum Hall systems. The decoupling gate also allows us to investigate how interedge state coupling influences the quantum interferences' dependence on the injection bias. We find that the finite bias visibility can be decomposed into two contributions: a Gaussian envelope which is surprisingly insensitive to the coupling, and a beating component which, on the contrary, is strongly affected by the coupling.

Bright side of the Coulomb blockade

We explore the photonic (bright) side of the dynamical Coulomb blockade (DCB) by measuring the radiation emitted by a dc voltage-biased Josephson junction embedded in a microwave resonator. In this regime Cooper pair tunneling is inelastic and associated with the transfer of an energy 2eV into the resonator modes. We have measured simultaneously the Cooper pair current and the photon emission rate at the resonance frequency of the resonator. Our results show two regimes, in which each tunneling Cooper pair emits either one or two photons into the resonator. The spectral properties of the emitted radiation are accounted for by an extension to DCB theory.

The property/privacy conundrum over human tissue

This paper analyzes court rulings on tissue samples as property and critiques objections that have been raised to the recognition of DNA samples as personal property. The cases are: Moore v. Regents of the University of California (1988, 1990), Greenberg v. Miami Children's Research Institute (2003), and Washington University v. Catalona (2007). The paper argues that it is possible for the law to support both individual privacy and property rights in DNA, recognizing nevertheless that some unresolved questions remain, including what exercising those rights means on a practical level. Finally, it offers suggestions for changes in law based on those considerations.

Autologous bone pate in middle ear and mastoid reconstruction

OBJECTIVE

To review outcomes of middle ear and mastoid surgery where autologous bone pate was used.

DESIGN

Retrospective review of 42 consecutive patients who underwent middle ear and mastoid reconstruction using autologous bone pate by the senior author over a three year period.

PARTICIPANTS

Patients underwent surgery for a spectrum of disease from chronic suppurative otitis media, to extensive cholesteatoma with intracranial abscess formation.

RESULTS

Autologous bone pate was used in conjunction with an anteriorly based musculo-fascial flap via a layered technique using tragal cartilage and temporalis fascia, to obliterate cavities in all patients. To date, there has been no evidence of recurrence or otorrhea in the cohort. Shallow retraction has been observed in 6.8%.

CONCLUSION

We advocate that bone pate, when used in conjunction with a middle temporal artery flap and layers of tragal cartilage and fascia, is a safe, effective treatment for problematic middle ear disease.

Experimental determination of the statistics of photons emitted by a tunnel junction

We report on an Hanbury Brown-Twiss experiment probing the statistics of microwave photons emitted by a tunnel junction in the shot-noise regime at low temperature. By measuring the cross correlation of the fluctuations of the occupation numbers of the photon modes of both detection branches, we show that while the statistics of electrons is Poissonian, the photons obey chaotic statistics. This is observed even for low photon occupation number when the voltage across the junction is close to hν/e.

Environmental control of terpene emissions from Cistus monspeliensis L. in natural Mediterranean shrublands

The large amount of volatile organic compound (VOC) emitted by vegetation modifies air quality contributing to both tropospheric ozone and secondary organic aerosol production. A better understanding of the factors controlling VOC emissions by vegetation is mandatory in order to improve emission estimates derived from tropospheric chemistry models. Although the Mediterranean shrublands are particularly abundant and rich in emitting species, their emission potential is poorly known. Focusing on a VOC-emitting shrub species widespread in the Mediterranean area (Cistus monspeliensis L.), we measured and analysed its emissions of terpenes taking into account the age of individuals, the season of sampling and the soil type. Sampling was done under natural environmental conditions. Species of the genus Cistus are frequently reported to be storing species, although we found only one stored monoterpene and three sesquiterpenes in very low amount. Major emitted compounds were alpha-pinene and beta-myrcene. Total terpene emissions were not influenced by plant age but emission of some individual terpenes was positively correlated with age. A strong seasonal effect was evidenced. A larger amount of terpenes was emitted during spring and summer than during fall and winter. Summer emission rates were nearly 70 times higher than winter emission rates. Total and individual terpene emissions were influenced by soil type; emissions on siliceous substrate were ca. seven times higher than those on calcareous substrate. In conclusion, it appears clearly that environmental factors such as soil nature and season should be taken into account in order to achieve improved modelling of terpene emissions by shrub species.

Carbon nanotubes as cooper-pair beam splitters

We report on conductance measurements in carbon nanotube based double quantum dots connected to two normal electrodes and a central superconducting finger. By operating our devices as beam splitters, we provide evidence for crossed Andreev reflections tunable in situ. This opens an avenue to more sophisticated quantum opticslike experiments with spin entangled electrons.

Tuning decoherence with a voltage probe

We present an experiment where we tune the decoherence in a quantum interferometer using one of the simplest objects available in the physics of quantum conductors: an Ohmic contact. For that purpose, we designed an electronic Mach-Zehnder interferometer which has one of its two arms connected to an Ohmic contact through a quantum point contact. At low temperature, we observe quantum interference patterns with a visibility up to 57%. Increasing the connection between one arm of the interferometer to the floating Ohmic contact, the voltage probe, reduces quantum interference as it probes the electron trajectory. This unique experimental realization of a voltage probe works as a trivial which-path detector whose efficiency can be simply tuned by a gate voltage.

Noise dephasing in edge states of the integer quantum Hall regime

An electronic Mach-Zehnder interferometer is used in the integer quantum Hall regime at a filling factor 2 to study the dephasing of the interferences. This is found to be induced by the electrical noise existing in the edge states capacitively coupled to each other. Electrical shot noise created in one channel leads to phase randomization in the other, which destroys the interference pattern. These findings are extended to the dephasing induced by thermal noise instead of shot noise: it explains the underlying mechanism responsible for the finite temperature coherence time tau_{phi}(T) of the edge states at filling factor 2, measured in a recent experiment. Finally, we present here a theory of the dephasing based on Gaussian noise, which is found to be in excellent agreement with our experimental results.