Bronchodilator Reversibility in the GAN Severe Asthma Cohort.

BACKGROUND AND OBJECTIVE: Positive bronchodilator reversibility (BDR) is a diagnostic criterion for asthma. However, patients with asthma may exhibit a negative BDR response. Aim: To describe the frequency of positive and Negative BDR response in patients with severe asthma and study associations with phenotypic characteristics. METHODS: A positive BDR response was defined as an increase in FEV1 >200 mL and >12% upon testing with a short-acting ß-agonist. RESULTS: BDR data were available for 793 of the 2013 patients included in the German Asthma Net (GAN) severe asthma registry. Of these, 250 (31.5%) had a positive BDR response and 543 (68.5%) a egative BDR response. Comorbidities significantly associated with a negative response were gastroesophageal reflux disease (GERD) (28.0% vs 40.0%, P<.01) and eosinophilic granulomatosis with polyangiitis (0.4% vs 3.0%; P<.05), while smoking history (active: 2.8% vs 2.2%; ex: 40.0% vs 41.7%) and comorbid chronic obstructive pulmonary disease (COPD) (5.2% vs 7.2%) were similar in both groups. Patients with a positive BDR response had worse asthma control (median Asthma Control Questionnaire 5 score, 3.4 vs 3.0, P<.05), more frequently reported dyspnea at rest (26.8% vs 16.4%, P<.001) and chest tightness (36.4% vs 26.2%, P<.001), and had more severe airway obstruction at baseline (FEV1% predicted, 56 vs 64, P<.001) and higher fractional exhaled nitric oxide (FeNO) levels (41 vs 33 ppb, P<0.05). There were no differences in diffusion capacity of the lung for carbon monoxide, single breath (% pred, 70% vs 71%). Multivariate linear regression analysis identified an association between positive BDR response and lower baseline FEV1% (P<.001) and chest tightness (P<.05) and a negative association between BDR and GERD (P<.05). CONCLUSION: In this real-life setting, most patients with severe asthma had a negative BDR response. Interestingly, this was not associated with smoking history or COPD, but with lower FeNO and presence of GERD.

Bronchodilator Reversibility in the GAN Severe Asthma Cohort

Background: Positive bronchodilator reversibility (BDR) is a diagnostic criterion for asthma. However, patients with asthma may exhibit a negative BDR response. Aim: To describe the frequency of positive and negative BDR response in patients with severe asthma and study associations with phenotypic characteristics. Methods: A positive BDR response was defined as an increase in FEV1 >200 mL and >12% upon testing with a short-acting ß-agonist. Results: BDR data were available for 793 of the 2013 patients included in the German Asthma Net (GAN) severe asthma registry. Of these, 250 (31.5%) had a positive BDR response and 543 (68.5%) a negative BDR response. Comorbidities significantly associated with a negative response were gastroesophageal reflux disease (GERD) (28.0% vs 40.0%, P<.01) and eosinophilic granulomatosis with polyangiitis (0.4% vs 3.0%; P<.05), while smoking history (active: 2.8% vs 2.2%; ex: 40.0% vs 41.7%) and comorbid chronic obstructive pulmonary disease (COPD) (5.2% vs 7.2%) were similar in both groups. Patients with a positive BDR response had worse asthma control (median Asthma Control Questionnaire 5 score, 3.4 vs 3.0, P<.05), more frequently reported dyspnea at rest (26.8% vs 16.4%, P<.001) and chest tightness (36.4% vs 26.2%, P<.001), and had more severe airway obstruction at baseline (FEV1% predicted, 56 vs 64, P<.001) and higher fractional exhaled nitric oxide (FeNO) levels (41 vs 33 ppb, P<0.05). There were no differences in diffusion capacity of the lung for carbon monoxide, single breath (% pred, 70% vs 71%). Multivariate linear regression analysis identified an association between positive BDR response and lower baseline FEV1% (P<.001) and chest tightness (P<.05) and a negative association between BDR and GERD (P<.05). Conclusion: In this real-life setting, most patients with severe asthma had a negative BDR response. Interestingly, this was not associated with smoking history or COPD, but with lower FeNO and presence of GERD. (AU)

Antecedentes: La reversibilidad broncodilatadora (RB) positiva es un criterio diagnóstico para el asma. Sin embargo, los pacientes con asma pueden presentar una prueba RB negativa. Objetivos: Describir la frecuencia de RB positivas y negativas en pacientes con asma grave y sus asociaciones con características fenotípicas. Métodos: La RB positiva se definió como un aumento del FEV1 > 200 ml y > 12% tras la inhalación de un agonista beta de acción corta (SABA). Resultados: De 2013 pacientes incluidos en el registro de asma grave del German Asthma Net (GAN), 793 tenían datos sobre RB. De estos, 250 (31,5%) tuvieron una prueba RB positiva y 543 (68,5%) negativa. Las comorbilidades significativamente asociadas con RB negativa fueron el reflujo gastroesofágico (ERGE) (28,0% frente a 40,0%, p<0,01) y EGPA (0,4% frente a 3,0%; p<0,05), mientras que el antecedente de tabaquismo (activo: 2,8% frente a 2,2%; exfumador: 40,0% vs. 41,7%) y la comorbilidad de la EPOC (5,2% vs. 7,2%) fueron similares en ambos grupos. Los pacientes con RB positiva tenían peor control del asma (mediana ACQ-5 3,4 vs. 3,0, p<0,05), más disnea en reposo (26,8% vs. 16,4%, p<0,001) y mayor opresión torácica (36,4% vs. 26,2%, p<0,001), además presentaban una obstrucción de las vías respiratorias más grave al inicio del estudio (FEV1% pred: 56 frente a 64, p<0,001) y niveles más altos de FeNO (41 frente a 33 ppb, p<0,05), mientras que la capacidad de difusión fue similar (DLCO-SB% pred. 70% vs. 71%). El análisis de regresión lineal multivariable identificó una asociación de FEV1% basal inferior (p<0,001) y opresión torácica (p<0,05) con RB positiva y ERGE (p<0,05) con RB negativa. Conclusión: En este entorno en vida real, la mayoría de los pacientes con asma grave tuvieron una RB negativa. Curiosamente, esto no se asoció con antecedentes de tabaquismo o EPOC, sino con FeNO más bajo y presencia de ERGE. (AU)

Tailoring electron beams with high-frequency self-assembled magnetic charged particle micro optics.

Tunable electromagnets and corresponding devices, such as magnetic lenses or stigmators, are the backbone of high-energy charged particle optical instruments, such as electron microscopes, because they provide higher optical power, stability, and lower aberrations compared to their electric counterparts. However, electromagnets are typically macroscopic (super-)conducting coils, which cannot generate swiftly changing magnetic fields, require active cooling, and are structurally bulky, making them unsuitable for fast beam manipulation, multibeam instruments, and miniaturized applications. Here, we present an on-chip microsized magnetic charged particle optics realized via a self-assembling micro-origami process. These micro-electromagnets can generate alternating magnetic fields of about ±100 mT up to a hundred MHz, supplying sufficiently large optical power for a large number of charged particle optics applications. That particular includes fast spatiotemporal electron beam modulation such as electron beam deflection, focusing, and wave front shaping as required for stroboscopic imaging.

[Guidance to the Interpretation of Cardiopulmonary Exercise Testing]. / Spiroergometrie kompakt ­ Physiologie, Durchführung und Auswertung.

Cardiorespiratory fitness has been established as an independent overall predictor of morbidity and mortality. However, patients' symptoms or stated levels of exercise intolerance correlate only poorly with resting functional and imaging tests. Cardiopulmonary exercise testing (CPET) is the gold standard for the integrative assessment of the cardiocirculatory, pulmonary and metabolic response to exercise and can help identify the source of exercise limitation, monitor disease progression, evaluate treatment responsiveness and inform about prognosis. Though CPET offers more valuable and pertinent information with slightly more expenditure of time compared to other methods even at submaximal exercise levels, it remains underutilized for various reasons such as costs, reimbursement and expertise. CPET can be seen as a complex, but not necessarily difficult tool. The objective of this review was to provide a description of the underlying principles of physiology, and an easy-to-follow guidance to indications, methodology, and interpretative strategies of CPET.

Imperceptible magnetic sensor matrix system integrated with organic driver and amplifier circuits.

Artificial electronic skins (e-skins) comprise an integrated matrix of flexible devices arranged on a soft, reconfigurable surface. These sensors must perceive physical interaction spaces between external objects and robots or humans. Among various types of sensors, flexible magnetic sensors and the matrix configuration are preferable for such position sensing. However, sensor matrices must efficiently map the magnetic field with real-time encoding of the positions and motions of magnetic objects. This paper reports an ultrathin magnetic sensor matrix system comprising a 2 × 4 array of magnetoresistance sensors, a bootstrap organic shift register driving the sensor matrix, and organic signal amplifiers integrated within a single imperceptible platform. The system demonstrates high magnetic sensitivity owing to the use of organic amplifiers. Moreover, the shift register enabled real-time mapping of 2D magnetic field distribution.

Host identification in unfed ticks from stable isotope compositions (δ13 C and δ15 N).

Determination of the ratios of natural stable isotopes (13 C/12 C and 15 N/14 N) in unfed Ixodes ricinus nymphs and adults, which, in their previous stage, fed on captive wild rodents (Apodemus sylvaticus and Myodes glareolus), wild birds (Parus major and Cyanistes caeruleus) or domestic ruminants (Ovis aries and Bos taurus), demonstrated that it is possible to identify each host category with confidence. First, the tick-blood spacing, which is the difference between values obtained from ticks and the blood of hosts that they had fed on in the previous stage, was consistent (152 spacings investigated from 15 host individuals in total). Second, potential confounding factors (tick age and sex) did not affect the discriminatory power of the isotope patterns, nor did different rearing conditions (room temperature vs. 4 °C) or the duration of development (maximum of 430 days). The findings that the tick-blood isotope spacings, across a diverse range of hosts, were similar and predictable, and that confounders had little or no effect on this, strongly support the usage of the isotope approach. Because each of the host categories has a different role in the population dynamics of I. ricinus and in tick-borne pathogen ecology, the method described here has great potential for the clarification of tick and tick-borne pathogen ecology in the field.

The impact of cattle dung pats on earthworm distribution in grazed pastures.

BACKGROUND: Grazed grassland management regimes can have various effects on soil fauna. For example, effects on earthworms can be negative through compaction induced by grazing animals, or positive mediated by increases in sward productivity and cattle dung pats providing a food source. Knowledge gaps exist in relation to the behaviour of different earthworm species i.e. their movement towards and aggregation under dung pats, the legacy effects of pats and the spatial area of recruitment. The present study addressed these knowledge gaps in field experiments, over 2 years, using natural and simulated dung pats on two permanent, intensively grazed pastures in Ireland. RESULTS: Dung pats strongly affected spatial earthworm distribution, with up to four times more earthworms aggregating beneath pats, than in the control locations away from pats. In these earthworm communities comprising 11 species, temporally different aggregation and dispersal patterns were observed, including absence of individual species from control locations, but no clear successional responses. Epigeic species in general, but also certain species of the anecic and endogeic groups were aggregating under dung. Sampling after complete dung pat disappearance (27 weeks after application) suggested an absence of a dung pat legacy effect on earthworm communities. Based on species distributions, the maximum size of the recruitment area from which earthworms moved to pats was estimated to be 3.8 m2 per dung pat. Since actual grazing over 6 weeks would result in the deposition of about 300 dung pats per ha, it is estimated that a surface area of 1140 m2 or about 11% of the total grazing area can be influenced by dung pats in a given grazing period. CONCLUSIONS: This study showed that the presence of dung pats in pastures creates temporary hot spots in spatial earthworm species distribution, which changes over time. The findings highlight the importance of considering dung pats, temporally and spatially, when sampling earthworms in grazed pastures. Published comparisons of grazed and cut grasslands probably reached incorrect conclusions by ignoring or deliberately avoiding dung pats. Furthermore, the observed intense aggregation of earthworms beneath dung pats suggests that earthworm functions need to be assessed separately at these hot spots.

Correction: Energy-dependent nucleolar localization of p53 in vitro requires two discrete regions within the p53 carboxyl terminus.

Following the publication of this article the authors noted that two images were duplicated in Figure 2B. The corrected figure 2B is below. The authors wish to apologize for any inconvenience caused.

Real-life effectiveness of asthma treatment with a fixed-dose fluticasone/formoterol pressurised metered-dose inhaler - Results from a non-interventional study.

OBJECTIVE: Prospective, non-interventional study of fixed-dose inhaled corticosteroid (ICS)/long-acting beta2-agonist (LABA) combination therapy with fluticasone propionate/formoterol fumarate (FP/FORM) across a spectrum of community-based patients with asthma in a real-life setting. METHODS: In FP/FORM-treated patients aged ≥12 years, asthma control (Asthma Control Test™ [ACT]), incidence of severe exacerbations, lung function, quality of life (asthma quality of life questionnaire [AQLQ]) and adverse events (AEs) were assessed over one year. RESULTS: Almost 40% (n = 555) of the full analysis population (N = 1410) were receiving ICS/LABA therapy prior to enrolment; 69.8% completed the study. Asthma control (mean ACT ± standard deviation) improved from 16.3 ± 5.0 at baseline to 19.8 ± 4.5 at study end. ACT scores were significantly (p < 0.0001) higher than baseline at all observation timepoints, including the first assessment at 4-6 weeks. The percentage of patients with asthma control increased (baseline: 30.9%; study end: 62.4%), and the percentage of patients with ≥1 severe asthma exacerbation decreased (12 months before: 35.8%; during study: 5.9%). Lung function (forced expiratory volume in one second, peak expiratory flow) improved from baseline to each observation timepoint (p < 0.0001 for all). Improvement in asthma status was accompanied by ameliorated quality of life: AQLQ scores improved significantly from baseline to all observation timepoints (p < 0.0001 for all). AEs accorded with the summary of product characteristics. After study completion, 70% of patients continued FP/FORM treatment. CONCLUSION: In this one-year study, FP/FORM treatment was associated with clinically relevant improvements in asthma status in a diverse population of patients under real-life conditions.

Measurement of the spin temperature of optically cooled nuclei and GaAs hyperfine constants in GaAs/AlGaAs quantum dots.

Deep cooling of electron and nuclear spins is equivalent to achieving polarization degrees close to 100% and is a key requirement in solid-state quantum information technologies. While polarization of individual nuclear spins in diamond and SiC (ref. ) reaches 99% and beyond, it has been limited to 50-65% for the nuclei in quantum dots. Theoretical models have attributed this limit to formation of coherent 'dark' nuclear spin states but experimental verification is lacking, especially due to the poor accuracy of polarization degree measurements. Here we measure the nuclear polarization in GaAs/AlGaAs quantum dots with high accuracy using a new approach enabled by manipulation of the nuclear spin states with radiofrequency pulses. Polarizations up to 80% are observed-the highest reported so far for optical cooling in quantum dots. This value is still not limited by nuclear coherence effects. Instead we find that optically cooled nuclei are well described within a classical spin temperature framework. Our findings unlock a route for further progress towards quantum dot electron spin qubits where deep cooling of the mesoscopic nuclear spin ensemble is used to achieve long qubit coherence. Moreover, GaAs hyperfine material constants are measured here experimentally for the first time.

Quantum-Dot Single-Photon Sources for Entanglement Enhanced Interferometry.

Multiphoton entangled states such as "N00N states" have attracted a lot of attention because of their possible application in high-precision, quantum enhanced phase determination. So far, N00N states have been generated in spontaneous parametric down-conversion processes and by mixing quantum and classical light on a beam splitter. Here, in contrast, we demonstrate superresolving phase measurements based on two-photon N00N states generated by quantum dot single-photon sources making use of the Hong-Ou-Mandel effect on a beam splitter. By means of pulsed resonance fluorescence of a charged exciton state, we achieve, in postselection, a quantum enhanced improvement of the precision in phase uncertainty, higher than prescribed by the standard quantum limit. An analytical description of the measurement scheme is provided, reflecting requirements, capability, and restraints of single-photon emitters in optical quantum metrology. Our results point toward the realization of a real-world quantum sensor in the near future.

Interface Adhesion and Structural Characterization of Rolled-up GaAs/In0.2Ga0.8As Multilayer Tubes by Coherent Phonon Spectroscopy.

We present a detailed experimental and theoretical study of the acoustic phonon modes in rolled-up multilayers with thickness of the layers in the nanometre and diameters in the micrometre range. We compare our results to planar, unrolled multilayers grown by molecular beam epitaxy. For the planar multilayers the experimentally obtained acoustic modes exhibit properties of a superlattice and match well to calculations obtained by the Rytov model. The rolled-up superlattice tubes show intriguing differences compared to the planar structures which can be attributed to the imperfect adhesion between individual tube windings. A transfer matrix method including a massless spring accounting for the imperfect adhesion between the layers yields good agreement between experiment and calculations for up to five windings. Areas with sufficient mechanical coupling between all windings can be distinguished by their acoustic mode spectrum from areas where individual windings are only partially in contact. This allows the spatially resolved characterization of individual tubes with micrometre spatial resolution where areas with varying interface adhesion can be identified.

Weakly-coupled quasi-1D helical modes in disordered 3D topological insulator quantum wires.

Disorder remains a key limitation in the search for robust signatures of topological superconductivity in condensed matter. Whereas clean semiconducting quantum wires gave promising results discussed in terms of Majorana bound states, disorder makes the interpretation more complex. Quantum wires of 3D topological insulators offer a serious alternative due to their perfectly-transmitted mode. An important aspect to consider is the mixing of quasi-1D surface modes due to the strong degree of disorder typical for such materials. Here, we reveal that the energy broadening γ of such modes is much smaller than their energy spacing Δ, an unusual result for highly-disordered mesoscopic nanostructures. This is evidenced by non-universal conductance fluctuations in highly-doped and disordered Bi2Se3 and Bi2Te3 nanowires. Theory shows that such a unique behavior is specific to spin-helical Dirac fermions with strong quantum confinement, which retain ballistic properties over an unusually large energy scale due to their spin texture. Our result confirms their potential to investigate topological superconductivity without ambiguity despite strong disorder.

Tunable charge transfer properties in metal-phthalocyanine heterojunctions.

Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films of different organic materials to create organic heterostructures which combine the electrical capabilities of each material. This opens the possibility to precisely engineer and tune new electrical properties. In particular, similar transition metal phthalocyanines demonstrate hybridization and charge transfer properties which could lead to interesting physical phenomena. Although, when considering device dimensions, a better understanding and control of the tuning of the transport properties still remain in the focus of research. Here, by employing conductive atomic force microscopy techniques, we provide an insight about the nanoscale electrical properties and transport mechanisms of MnPc and fluorinated phthalocyanines such as F16CuPc and F16CoPc. We report a transition from typical diode-like transport mechanisms for pure MnPc thin films to space-charge-limited current transport regime (SCLC) for Pc-based heterostructures. The controlled addition of fluorinated phthalocyanine also provides highly uniform and symmetric-polarized transport characteristics with conductance enhancements up to two orders of magnitude depending on the polarization. We present a method to spatially map the mobility of the MnPc/F16CuPc structures with a nanoscale resolution and provide theoretical calculations to support our experimental findings. This well-controlled nanoscale tuning of the electrical properties for metal transition phthalocyanine junctions stands as key step for future phthalocyanine-based electronic devices, where the low dimension charge transfer, mediated by transition metal atoms could be intrinsically linked to a transfer of magnetic moment or spin.

Spin-orbit coupling of light in asymmetric microcavities.

When spinning particles, such as electrons and photons, undergo spin-orbit coupling, they can acquire an extra phase in addition to the well-known dynamical phase. This extra phase is called the geometric phase (also known as the Berry phase), which plays an important role in a startling variety of physical contexts such as in photonics, condensed matter, high-energy and space physics. The geometric phase was originally discussed for a cyclically evolving physical system with an Abelian evolution, and was later generalized to non-cyclic and non-Abelian cases, which are the most interesting fundamental subjects in this area and indicate promising applications in various fields. Here, we enable optical spin-orbit coupling in asymmetric microcavities and experimentally observe a non-cyclic optical geometric phase acquired in a non-Abelian evolution. Our work is relevant to fundamental studies and implies promising applications by manipulating photons in on-chip quantum devices.

Isotopic composition of sheep wool records seasonality of climate and diet.

RATIONALE: Hair keratin is a very important material in ecological and archaeological studies because it grows continuously, can be obtained non-invasively, does not require extensive processing prior to analysis and can be found in archaeological sites. Only a few studies have examined seasonal variations in hair isotope values, and there is no published dataset examining the isotope variability recorded in the keratinous tissues of stationary (i.e., non-migrating) domestic mammals. METHODS: Thirty-six Irish sheep were sampled in eight farms every three months between September 2006 and June 2007. A shearing strategy was adopted to sample only the most recently grown wool in order to represent an average of the summer, autumn, winter and spring conditions. The stable isotope ratios of the ground samples were measured using two different stable isotope mass spectrometers operated in dual-inlet (C, N) and continuous-flow (O, H) mode. RESULTS: Wool O isotope ratios are a good proxy for seasonal variability in climate and can be used to anchor a chronology independently of other isotope records (C, N) that are influenced by diet or physiology. By contrast, interpretation of seasonal variations in hair H isotope composition in terms of climate is more complex probably due to the influence of dietary H. The C and N isotope values of grass-fed animals varied seasonally, probably reflecting the annual cycle of seasonal variation in grass isotope values. The highest δ(13) C values were measured in summer-grown wool, while the highest δ(15) N values were measured in winter-grown wool. Supplementation of the sheep diet with concentrates was detected easily and was marked by an increase in δ(13) C values and a decrease in δ(15) N values in winter-grown wool. CONCLUSIONS: The present study demonstrates that time-resolved sampling and stable isotope ratio analysis of sheep wool can be used to identify short-term changes in diet and climate and therefore offer a tool to examine a wide variety of present and past husbandry practices.

[Reproducibility of subjective refraction measurement]. / Zur Reproduzierbarkeit von Refraktionsbestimmungen.

BACKGROUND: Reproducibility of subjective refraction measurement is limited by various factors. The main factors affecting reproducibility include the characteristics of the measurement method and of the subject and the examiner. METHODS AND RESULTS: This article presents the results of a study on this topic, focusing on the reproducibility of subjective refraction measurement in healthy eyes. The results of previous studies are not all presented in the same way by the respective authors and cannot be fully standardized without consulting the original scientific data. To the extent that they are comparable, the results of our study largely correspond largely with those of previous investigations: During repeated subjective refraction measurement, 95% of the deviation from the mean value was approximately ±0.2 D to ±0.65 D for the spherical equivalent and cylindrical power. The reproducibility of subjective refraction measurement in healthy eyes is limited, even under ideal conditions. CONCLUSION: Correct assessment of refraction results is only feasible after identifying individual variability. Several measurements are required. Refraction cannot be measured without a tolerance range. The English full-text version of this article is available at SpringerLink (under supplemental).

Experimental realization of coexisting states of rolled-up and wrinkled nanomembranes by strain and etching control.

Self-positioned nanomembranes, such as rolled-up tubes and wrinkled thin films, have been potential systems for a variety of applications and basic studies on elastic properties of nanometer-thick systems. Although there is a clear driving force towards elastic energy minimization in each system, the exploration of intermediate states, in which specific characteristics could be chosen by a slight modification of a processing parameter, have not been experimentally realized. In this work, arrays of freestanding III-V nanomembranes (NM) supported on one edge and presenting a coexistence of these two main behaviors were obtained by design of strain conditions in the NMs and controlled selective etching of patterned substrates. As the etching process continues, a mixture of wrinkled and rolled-up states is achieved. For very long etching times an onset of plastic cracks was observed in the points with localized stress. The well-defined morphological periodicity of the relaxed NMs was compared with finite element simulations of their elastic relaxation. The evolution of strain in the NMs with etching time was directly evaluated by X-ray diffraction, providing a comprehensive scenario of transitions among competing and coexisting strain states.

Role of surface-segregation-driven intermixing on the thermal transport through planar Si/Ge superlattices.

It has been highly debated whether the thermal conductivity κ of a disordered SiGe alloy can be lowered by redistributing its constituent species so as to form an ordered superlattice. By ab initio calculations backed by systematic experiments, we show that Ge segregation occurring during epitaxial growth can lead to κ values not only lower than the alloy's, but also lower than the perfect superlattice values. Thus we theoretically demonstrate that κ does not monotonically decrease as the Si- and Ge-rich regions become more sharply defined. Instead, an intermediate concentration profile is able to lower κ below both the alloy limit (total intermixing) and also the abrupt interface limit (zero intermixing). This unexpected result is attributed to the peculiar behavior of the phonon mean free path in realistic Si/Ge superlattices, which shows a crossover from abrupt-interface- to alloylike values at intermediate phonon frequencies of ∼3 THz. Our calculated κ's quantitatively agree with the measurements when the realistic, partially intermixed profiles produced by segregation are considered.

Quasiballistic transport of Dirac fermions in a Bi2Se3 nanowire.

Quantum coherent transport of surface states in a mesoscopic nanowire of the three-dimensional topological insulator Bi(2}Se(3) is studied in the weak-disorder limit. At very low temperatures, many harmonics are evidenced in the Fourier transform of Aharonov-Bohm oscillations, revealing the long phase coherence length of spin-chiral Dirac fermions. Remarkably, from their exponential temperature dependence, we infer an unusual 1/T power law for the phase coherence length L(φ)(T). This decoherence is typical for quasiballistic fermions weakly coupled to their environment.