Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer

Over the past 20 years, many efforts have been made to understand and control decoherence in 2D electron systems. In particular, several types of electronic interferometers have been considered in GaAs heterostructures, in order to protect the interfering electrons from decoherence. Nevertheless, it is now understood that several intrinsic decoherence sources fundamentally limit more advanced quantum manipulations. Here, we show that graphene offers a unique possibility to reach a regime where the decoherence is frozen and to study unexplored regimes of electron interferometry. We probe the decoherence of electron channels in a graphene quantum Hall PN junction, forming a Mach-Zehnder interferometer1,2, and unveil a scaling behavior of decay of the interference visibility with the temperature scaled by the interferometer length. It exhibits a remarkable crossover from an exponential decay at higher temperature to an algebraic decay at lower temperature where almost no decoherence occurs, a regime previously unobserved in GaAs interferometers.

Heat Equilibration of Integer and Fractional Quantum Hall Edge Modes in Graphene

Hole-conjugate states of the fractional quantum Hall effect host counterpropagating edge channels which are thought to exchange charge and energy. These exchanges have been the subject of extensive theoretical and experimental works; in particular, it is yet unclear if the presence of integer quantum Hall edge channels stemming from fully filled Landau levels affects heat equilibration along the edge. In this Letter, we present heat transport measurements in quantum Hall states of graphene demonstrating that the integer channels can strongly equilibrate with the fractional ones, leading to markedly different regimes of quantized heat transport that depend on edge electrostatics. Our results allow for a better comprehension of the complex edge physics in the fractional quantum Hall regime.

Quantum Hall Valley Splitters and a Tunable Mach-Zehnder Interferometer in Graphene

Graphene is a very promising test bed for the field of electron quantum optics. However, a fully tunable and coherent electronic beam splitter is still missing. We report the demonstration of electronic beam splitters in graphene that couple quantum Hall edge channels having opposite valley polarizations. The electronic transmission of our beam splitters can be tuned from zero to near unity. By independently setting the beam splitters at the two corners of a graphene p-n junction to intermediate transmissions, we realize a fully tunable electronic Mach-Zehnder interferometer. This tunability allows us to unambiguously identify the quantum interferences due to the Mach-Zehnder interferometer, and to study their dependence with the beam-splitter transmission and the interferometer bias voltage. The comparison with conventional semiconductor interferometers points toward universal processes driving the quantum decoherence in those two different 2D systems, with graphene being much more robust to their effect.

Myasthenia gravis and pregnancy

Myasthenia gravis is an autoimmune disease characterised by fluctuating muscle weakness, which worsens during activity. It affects particularly scapular and pelvic girdles, axial and bulbar muscles. Myasthenia gravis is twice more frequent in women and symptoms often appear in the second and third decade of life. Thus, a growing number of women affected by this condition become pregnant. To minimise the effects of myasthenia gravis on pregnancy and the newborn, and to avoid myasthenia crisis in the post-partum, the pregnancy must be planned as far as possible. During pregnancy, treatment must be reviewed due to the threat of teratogenic effects (mycophenolate mofetil, rituximab), and the follow-up must be multidisciplinary.

Pharmacological inhibition of syntenin PDZ2 domain impairs breast cancer cell activities and exosome loading with syndecan and EpCAM cargo

Exosomes support cell-to-cell communication in physiology and disease, including cancer. We currently lack tools, such as small chemicals, capable of modifying exosome composition and activity in a specific manner. Building on our previous understanding of how syntenin, and its PDZ partner syndecan (SDC), impact on exosome composition we optimized a small chemical compound targeting the PDZ2 domain of syntenin. In vitro , in tests on MCF-7 breast carcinoma cells, this compound is non-toxic and impairs cell proliferation, migration and primary sphere formation. It does not affect the size or the number of secreted particles, yet it decreases the amounts of exosomal syntenin, ALIX and SDC4 while leaving other exosomal markers unaffected. Interestingly, it also blocks the sorting of EpCAM, a bona fide target used for carcinoma exosome immunocapture. Our study highlights the first characterization of a small pharmacological inhibitor of the syntenin-exosomal pathway, of potential interest for exosome research and oncology.

Valuing All Voices: refining a trauma-informed, intersectional and critical reflexive framework for patient engagement in health research using a qualitative descriptive approach

BACKGROUND

Critical stakeholder-identified gaps in current health research engagement strategies include the exclusion of voices traditionally less heard and a lack of consideration for the role of trauma in lived experience. Previous work has advocated for a trauma-informed, intersectional, and critical reflexive approach to patient and public involvement in health research. The Valuing All Voices Framework embodies these theoretical concepts through four key components: trust, self-awareness, empathy, and relationship building. The goal of this framework is to provide the context for research teams to conduct patient engagement through the use of a social justice and health equity lens, to improve safety and inclusivity in health research. The aim of this study was to revise the proposed Valuing All Voices Framework with members of groups whose voices are traditionally less heard in health research.

METHODS

A qualitative descriptive approach was used to conduct a thematic analysis of participant input on the proposed framework. Methods were co-developed with a patient co-researcher and community organizations.

RESULTS

Group and individual interviews were held with 18 participants identifying as Inuit; refugee, immigrant, and/or newcomer; and/or as a person with lived experience of a mental health condition. Participants supported the proposed framework and underlying theory. Participant definitions of framework components included characterizations, behaviours, feelings, motivations, and ways to put components into action during engagement. Emphasis was placed on the need for a holistic approach to engagement; focusing on open and honest communication; building trusting relationships that extend beyond the research process; and capacity development for both researchers and patient partners. Participants suggested changes that incorporated some of their definitions; simplified and contextualized proposed component definitions; added a component of "education and communication"; and added a 'how to' section for each component. The framework was revised according to participant suggestions and validated through member checking.

CONCLUSIONS

The revised Valuing All Voices Framework provides guidance for teams looking to employ trauma-informed approaches, intersectional analysis, and critical reflexive practice in the co-development of meaningful, inclusive, and safe engagement strategies.

PLAIN ENGLISH SUMMARY

Patient engagement in health research continues to exclude many people who face challenges in accessing healthcare, including (but not limited to) First Nations, Inuit, and Metis people; immigrants, refugees, and newcomers; and people with lived experience of a mental health condition. We proposed a new guide to help researchers engage with patients and members of the public in research decision-making in a meaningful, inclusive, and safe way. We called this the Valuing All Voices Framework, and met with people who identify as members of some of these groups to help define the key parts of the framework (trust; self-awareness; empathy; and relationship building), to tell us what they liked and disliked about the proposed framework, and what needed to be changed. Input from participants was used to change the framework, including clarifying definitions of the key parts, adding another key part called "education and communication", and providing action items so teams can put these key parts into practice.

Relaxation and revival of quasiparticles injected in an interacting quantum Hall liquid

The one-dimensional, chiral edge channels of the quantum Hall effect are a promising platform in which to implement electron quantum optics experiments; however, Coulomb interactions between edge channels are a major source of decoherence and energy relaxation. It is therefore of large interest to understand the range and limitations of the simple quantum electron optics picture. Here we confirm experimentally for the first time the predicted relaxation and revival of electrons injected at finite energy into an edge channel. The observed decay of the injected electrons is reproduced theoretically within a Tomonaga-Luttinger liquid framework, including an important dissipation towards external degrees of freedom. This gives us a quantitative empirical understanding of the strength of the interaction and the dissipation.

Monitoring black grouse Tetrao tetrix in Isère, northern French Alps: cofactors, population trends and potential biases

Wildlife management benefits from studies that verify or improve the reliability of monitoring protocols. In this study in Isère, France, we tested for potential links between the abundance of black grouse (Tetrao tetrix) in lek–count surveys and cofactors (procedural, geographical and meteorological cofactors) between 1989 and 2016. We also examined the effect of omitting or considering the important cofactors on the long–term population trend that can be inferred from lek–count data. Model selections for data at hand highlighted that the abundance of black grouse was mainly linked to procedural cofactors, such as the number of observers, the time of first observation of a displaying male, the day, and the year of the count. Some additional factors relating to the surface of the census sector, temperature, northing, altitude and wind conditions also appeared depending on the spatial or temporal scale of the analysis. The inclusion of the important cofactors in models modulated the estimates of population trends. The results of the larger dataset highlighted a mean increase of +17 % (+5.3 %; +29 %) of the abundance of black grouse from 1997 to 2001, and a mean increase in population of +47 % (+16 %; +87 %) throughout the study period (1989–2016). We discuss the hypothesis of plausible links between this past increase in the number of black grouse and the ecological impact of the winter storm ‘Vivian’. Findings from our study and the ecological phenomena that were concomitant with the observed population trend provide opportunities to strengthen the monitoring and management of black grouse in the Alps.

Antibunched Photons Emitted by a dc-Biased Josephson Junction

We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97  kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^{7} photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain.

Strongly Correlated Charge Transport in Silicon Metal-Oxide-Semiconductor Field-Effect Transistor Quantum Dots

Quantum shot noise probes the dynamics of charge transfers through a quantum conductor, reflecting whether quasiparticles flow across the conductor in a steady stream, or in syncopated bursts. We have performed high-sensitivity shot noise measurements in a quantum dot obtained in a silicon metal-oxide-semiconductor field-effect transistor. The quality of our device allows us to precisely associate the different transport regimes and their statistics with the internal state of the quantum dot. In particular, we report on large current fluctuations in the inelastic cotunneling regime, corresponding to different highly correlated, non-Markovian charge transfer processes. We have also observed unusually large current fluctuations at low energy in the elastic cotunneling regime, the origin of which remains to be fully investigated.

Erratum: Fluctuation-Dissipation Relations of a Tunnel Junction Driven by a Quantum Circuit [Phys. Rev. Lett. 114, 126801 (2015)]

This corrects the article DOI: 10.1103/PhysRevLett.114.126801.

Emission of Nonclassical Radiation by Inelastic Cooper Pair Tunneling

We show that a properly dc-biased Josephson junction in series with two microwave resonators of different frequencies emits photon pairs in the resonators. By measuring auto- and intercorrelations of the power leaking out of the resonators, we demonstrate two-mode amplitude squeezing below the classical limit. This nonclassical microwave light emission is found to be in quantitative agreement with our theoretical predictions, up to an emission rate of 2 billion photon pairs per second.

The role of transmembrane domains in the March-I-mediated downregulation of MHC-II and CD86

MHC class II molecules on APCs bind to and presents peptides to antigen-specific CD4 T cells. DCs are the most potent subset of APC and can activate naïve T cells. Immature DCs possess relatively low expression of the costimulatory molecule CD86 and have a rapid rate of turnover of MHC-II. This is due in part to ubiquitin-mediated degradation of MHC-II and CD86 by the transmembrane (TM) ubiquitin ligase March-I in immature DCs. Curiously, March-I activity is suppressed by CD83, a TM protein that is upregulated by DC activation. Despite the well-documented role of March-I in specifically regulating MHC-II and CD86 expression, little is known about how these substrates interact with March-I and how CD83 is able to suppress March-I function. In this study we have examined the importance of TM domain interactions in March-I function by replacing TM domain sequences in March-I or CD83 with that of ICAM-1. A March-I TM1 mutant had reduced ability to affect MHC-II expression and had no effect on CD86 expression. Binding studies demonstrated that that March-I TM1 mutant lost all ability to bind to CD86. Whereas wild-type CD83 was able to block March-I downregulation of MHC-II and CD86, replacement of the CD83 TM domain with that of ICAM-1 completely abrogated CD83 suppression of March-I function. Binding studies confirmed that the CD83 TM mutant had lost all ability to bind to March-I. Our data therefore suggest that March-I binds to MHC-II and CD86 by TM domain interactions and that CD83 blocks March-I function by competitively inhibiting the binding of March-I to MHC-II and CD86.

Rab11a Regulates MHC Class II Recycling and Promotes Antigenic Peptide Exchange in Recycling Endosomes of Mature Dendritic Cells

Dendritic cells (DCs) specialize in antigen capture and maintain a highly dynamic pool of peptide-MHC class II complexes (MHC-II) that continuously internalized and degraded in immature DCs. By contrast, in mature DCs pMHC-II internalizes but is efficiently recycled back to the plasma membrane for recognition by CD4 T cells. Regulation of pMHC-II biosynthesis and degradation is essential for optimal DC function, however the molecular basis of pMHC-II recycling and the cellular machinery that orchestrates pMHC-II trafficking are incompletely understood. In the present study we found that internalized pMHC-II on mature DCs, but not immature DCs, colocalizes with the regulator of endosome recycling Rab11a. Using a lentivirus encoded shRNA, we show that Rab11a knock-down inhibits recycling of pMHC-II in mature DCs. Moreover, Rab11a knock-down results in the intracellular accumulation of internalized surface pMHC-II. We also show that Rab11a knock-down in mature DCs specifically inhibits presentation of a “recycling endosome” epitope of internalized influenza hemagglutinin only in mature DCs. Our study thus identifies Rab11a as an important regulator of pMHC-II recycling that can enhance presentation of certain antigenic peptides in mature DCs.

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.

Factors affecting perceived stigma in leprosy affected persons in western Nepal

Background

There are various factors which construct the perception of stigma in both leprosy affected persons and unaffected persons. The main purpose of this study was to determine the level of perceived stigma and the risk factors contributing to it among leprosy affected person attending the Green Pastures Hospital, Pokhara municipality of western Nepal.

Methods

A cross-sectional study was conducted among 135 people affected by leprosy at Green Pastures Hospital and Rehabilitation Centre. Persons above the age of 18 were interviewed using a set of questionnaire form and Explanatory Model Interview Catalogue (EMIC). In addition, two sets of focused group discussions each containing 10 participants from the ward were conducted with the objectives of answering the frequently affected EMIC items.

Results

Among 135 leprosy affected persons, the median score of perceived stigma was 10 while it ranged from 0–34. Higher perceived stigma score was found in illiterate persons (p = 0.008), participants whose incomes were self-described as inadequate (p = 0.014) and who had changed their occupation due to leprosy (p = 0.018). Patients who lacked information on leprosy (p = 0.025), knowledge about the causes (p = 0.02) and transmission of leprosy (p = 0.046) and those who had perception that leprosy is a severe disease (p<0.001) and is difficult to treat (p<0.001) had higher perceived stigma score. Participants with disfigurement or deformities (p = 0.014), ulcers (p = 0.022) and odorous ulcers (p = 0.043) had higher perceived stigma score.

Conclusion

The factors associated with higher stigma were illiteracy, perceived economical inadequacy, change of occupation due to leprosy, lack of knowledge about leprosy, perception of leprosy as a severe disease and difficult to treat. Similarly, visible deformities and ulcers were associated with higher stigma. There is an urgent need of stigma reduction strategies focused on health education and health awareness programs in addition to the necessary rehabilitation support.

A total of 135 leprosy affected persons were interviewed with a questionnaire containing EMIC questions designed to assess the level of perceived stigma and the questionnaire containing variables for socio-demographic characteristics, knowledge about leprosy and the clinical presentations of the participants. Clinical presentation as disability was graded according to WHO guidelines, where grade 0 means no disability found, grade I means loss of sensation has been noted in the hand or foot while grade II means visible damage or disability. Total EMIC score was analyzed between sub-variables to see the factors associated with the higher level of perceived stigma score. Additionally, among the total participants, we included 20 of them who were admitted at hospital for various reasons. Two sets of focus group discussions were conducted with additional questions to derive the reasons behind frequently affected EMIC stigma domains. The factors associated with higher perceived stigma score were illiteracy (those who could not read and write), perceived economical inadequacy, lack of knowledge on leprosy, the perceptions as difficult to treat and severe disease and presence of visible deformities and ulcers. Considering our findings pertaining to higher perceived stigma, there is an urgent need of stigma reduction strategies which should focus on health education about leprosy that can change the perceived stigma in leprosy.

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.

Encounter with antigen-specific CD4 T cells promotes down-regulation of MHC-II in Dendritic cells (106.18)

Major histocompatibility complex class II molecules (MHC-II) on dendritic cells (DCs) present antigenic peptides to CD4 T cells. MHC-II and T cell receptor (TCR)-mediated DC-T cell interactions induce activation and proliferation of naïve CD4 T cells. The fate of MHC-II molecules after engagement with TCR has not been extensively studied. In this study we investigated the effects of engagement of cell surface MHC-II with TCR. By incubating DCs with T cells, we found that activated CD4 T cells induced degradation of cell surface MHC-II in an antigen-specific manner. T cell engagement-induced degradation of MHC-II was also mimicked by crosslinking of MHC-II by anti-MHC-II mAb. After MHC-II crosslinking, clustering and endocytosis of MHC-II were induced and MHC-II was transported to lysosomes and degraded. MHC-II clustering and endocytosis were inhibited by cell surface cholesterol-depletion using methyl β-cyclodextrin (MβCD). Although ubiquitination is known to regulate cell surface expression of MHC-II in DCs, by using ubiquitination site-deficient MHC-II mutant mice we found that ubiquitination was not required for crosslinking induced MHC-II degradation. Finally, we found that crosslinking of MHC-II on DCs inhibited their ability to stimulate additional naïve CD4 T cells. These results demonstrate that CD4 T cells promote the down-regulation of MHC-II and limit antigen presentation by inducing endocytosis and degradation of MHC-II in DCs.

Transmembrane domain sequences regulate the association of MHC- class II with lipid raft microdomains (106.19)

MHC II is known to be present in cholesterol-dependent lipid raft plasma membrane microdomains, and this association is important for MHC II- dependent activation of CD4 T cells by Dendritic cells (DCs). Until now it is not clear what regulates MHC II lipid raft association. In the present study we attempt to define the signals present in the MHC II transmembrane (TM) domain that regulate MHC II association with lipid rafts. Palmitoylation of cysteine residues is a well-known modification that often results in lipid raft association of TM protein and each MHC II I-Ab subunit contains a TM cysteine. We therefore expressed MHC II-α and β-chains containing TM domain cysteine → serine mutants in DCs obtained from MHC II null mice and analyzed MHC II lipid raft association. These experiments showed that the mutation of the TM cysteine residues actually enhanced MHC II raft localization about 3 fold. We also examined the role of the entire MHC II TM domain in lipid raft association. Replacement of the MHC II-α and β-chain TM domains with that of the non-raft protein ICAM 1 reduces MHC II lipid raft association 5 fold. We are currently examining the role of TM domain sequences present in each MHC II subunit in an attempt to identify dominant raft localization sequences in MHC II.

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.

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.

Australia's notifiable diseases status, 2006: annual report of the National Notifiable Diseases Surveillance System

In 2006, 66 diseases and conditions were nationally notifiable in Australia. States and territories reported a total of 138,511 cases of communicable diseases to the National Notifiable Diseases Surveillance System: an increase of 10.4% on the number of notifications in 2005. In 2006, the most frequently notified diseases were sexually transmissible infections (57,941 notifications, 42% of total notifications), gastrointestinal diseases (27,931 notifications, 20% of total notifications) and vaccine preventable diseases (22,240 notifications, 16% of total notifications). There were 19,111 notifications of bloodborne diseases; 8,606 notifications of vectorborne diseases; 1,900 notifications of other bacterial infections; 767 notifications of zoonoses and 3 notifications of quarantinable diseases.

Direct measurement of the coherence length of edge states in the integer quantum Hall regime

We have determined the finite temperature coherence length of edge states in the integer quantum Hall effect regime. This was realized by measuring the visibility of electronic Mach-Zehnder interferometers of different sizes, at filling factor 2. The visibility shows an exponential decay with the temperature. The characteristic temperature scale is found inversely proportional to the length of the interferometer arm, allowing one to define a coherence length l_(phi). The variations of l_(phi) with magnetic field are the same for all samples, with a maximum located at the upper end of the quantum Hall plateau. Our results provide the first accurate determination of l_(phi) in the quantum Hall regime.

Experimental test of the high-frequency quantum shot noise theory in a quantum point contact

We report on direct measurements of the electronic shot noise of a quantum point contact at frequencies nu in the range 4-8 GHz. The very small energy scale used ensures energy independent transmissions of the few transmitted electronic modes and their accurate knowledge. Both the thermal energy and the quantum point contact drain-source voltage V_{ds} are comparable to the photon energy hnu leading to observation of the shot noise suppression when V_{ds}<hnu/e. Our measurements provide the first complete test of the finite frequency shot noise scattering theory without adjustable parameters.

Invasive pneumococcal disease in Australia, 2005

Enhanced surveillance for invasive pneumococcal disease (IPD) was carried out in all Australian states and territories in 2005 with comparative data available since 2001. There were 1,680 cases of IPD notified to the National Notifiable Diseases Surveillance System in Australia in 2005; a notification rate of 8.3 cases per 100,000 population. The rates varied between states and territories and by geographical region with the highest rates in the Northern Territory, the jurisdiction with the largest proportion of Indigenous people. Invasive pneumococcal disease was reported most frequently in those aged 85 years or over (41 cases per 100,000 population) and in 1-year-old children (36.5 cases per 100,000 population). Enhanced data provided additional information on 1,015 (60%) of all notified cases. The overall rate of IPD in Indigenous Australians was 8.6 times the rate in non-Indigenous Australians. There were 126 deaths attributed to IPD resulting in an overall case fatality rate of 7.5%. While the rate of IPD in the Indigenous under 2-year-old population decreased from 219 cases per 100,000 population since targeted introduction of the 7-valent conjugate pneumococcal vaccine (7vPCV) in 2001, the rate in 2005 (94 cases per 100,000 population) was significantly greater than in non-Indigenous children (20.4 cases per 100,000 population). Rates of disease in all children aged less than 2 years, caused by serotypes in the 7vPCV decreased by 75% between 2004 and 2005 as a result of the introduction of a universal childhood 7vPCV immunisation program. Significant decreases in IPD caused by 7vPCV serotypes also occurred in the 2-14 years and 65 years or over age groups. There is no evidence of replacement disease with non-vaccine serotypes. Serotypes were identified in 90% of all notified cases, with 61% of disease caused by serotypes in the 7vPCV and 88% caused by serotypes in the 23-valent polysaccharide pneumococcal vaccine (23vPPV). Reduced penicillin susceptibility remains low and reduced susceptibility to 3rd generation cephalosporins is rare.

Tuberculosis notifications in Australia, 2005

The National Notifiable Disease Surveillance System received 1,072 tuberculosis (TB) notifications in 2005, of which 1,022 were new cases and 50 were relapses. The incidence of TB in Australia was 5.3 cases per 100,000 population in 2005 and has remained at a stable rate since 1985. The high-incidence groups remain people born overseas and Indigenous Australians at 20.6 and 5.9 cases per 100,000 population, respectively. By contrast, the incidence of TB in the non-Indigenous Australian-born population was 0.8 cases per 100,000 population. Rates in the Australian-born, both Indigenous and non-Indigenous have been declining since 1991, while rates in the overseas-born have been increasing. TB control in Australia relies on pre-migration screening and provision of free and effective treatment.

Optimization of an implantable volume conduction antenna

As implantable devices become increasingly sophisticated, there is a strong need for developing a wireless data communication channel between these devices and external computers. This important problem has been studied and an antenna is being designed based on the volume conduction of biological tissues. Closed-form equation and finite element analyses were performed for the case of brain implantation using a spherical volume conduction model of the head. Finite element proofs of concept in 2D and 3D demonstrated the influence of epoxy and a volume conductor reflector on volume currents, exhibiting changes in the far field as controlled by the near field. A 3D finite element analysis showed an increased signal transduction of 35% as compared to the 3D analytical analysis, which was not able to simulate the epoxy. The optimum angle of inclination is shallower than what was intuitively thought, indicating that the antenna elements destructively interfere with the generated surface voltages, requiring the antenna elements to be rotated away from each other.

A novel luminescent lifetime-based optrode for the detection of gaseous and dissolved oxygen utilising a mixed ormosil matrix containing ruthenium (4,7-diphenyl-1,10-phenanthroline)3Cl2 (Ru.dpp)

A novel luminescent lifetime optrode is presented for the detection of gaseous and dissolved oxygen. The optrode utilises ruthenium (4,7-diphenyl-1,10-phenanthroline)(3)Cl(2) as the sensing fluorophore immobilised in a hydrophobic ormosil matrix. The ormosil matrix is synthesised at room temperature from octyltriethoxysilane and methyltriethoxysilane precursors. Investigations of different ormosils were conducted and the most effective one was selected for optrode production. Optrodes were tested for responses to gaseous and dissolved oxygen. Their responses were modelled using traditional two-site or two-exponential methods and feed-forward artificial neural networks. Comparison of the two modelling methodologies is presented and further improvements in modelling and ormosil design are suggested.