Interactions between the aging brain and motor task complexity across the lifespan: balancing brain activity resource demand and supply.

The Compensation Related Utilization of Neural Circuits Hypothesis (CRUNCH) proposes a framework for understanding task-related brain activity changes as a function of healthy aging and task complexity. Specifically, it affords the following predictions: (i) all adult age groups display more brain activation with increases in task complexity, (ii) older adults show more brain activation compared with younger adults at low task complexity levels, and (iii) disproportionately increase brain activation with increased task complexity, but (iv) show smaller (or no) increases in brain activation at the highest complexity levels. To test these hypotheses, performance on a bimanual tracking task at 4 complexity levels and associated brain activation were assessed in 3 age groups (20-40, 40-60, and 60-80 years, n = 99). All age groups showed decreased tracking accuracy and increased brain activation with increased task complexity, with larger performance decrements and activation increases in the older age groups. Older adults exhibited increased brain activation at a lower complexity level, but not the predicted failure to further increase brain activity at the highest complexity level. We conclude that older adults show more brain activation than younger adults and preserve the capacity to deploy increased neural resources as a function of task demand.

Network-specific differences in transient brain activity at rest are associated with age-related reductions in motor performance.

Multiple functional changes occur in the brain with increasing age. Among those, older adults typically display more restricted fluctuations of brain activity, both during resting-state and task execution. These altered dynamic patterns have been linked to reduced task performance across multiple behavioral domains. Windowed functional connectivity, which is typically employed in the study of connectivity dynamics, however, might not be able to properly characterize moment-to-moment variations of individual networks. In the present study, we used innovation-driven co-activation patterns (ICAP) to overcome this limitation and investigate the length (duration) and frequency (innovation) in which various brain networks emerged across the adult lifespan (N= 92) during a resting-state period. We identified a link between increasing age and a tendency to engage brain areas with distinct functional associations simultaneously as a single network. The emergence of isolated and spatially well-defined visual, motor, frontoparietal, and posterior networks decreased with increased age. This reduction in dynamics of specialized networks mediated age-related performance decreases (i.e., increases in interlimb interference) in a bimanual motor task. Altogether, our findings demonstrated that older compared to younger adults tend to activate fewer network configurations, which include multiple functionally distinct brain areas. The reduction in independent emergence of functionally well-defined and task-relevant networks may reflect an expression of brain dedifferentiation and is likely associated with functional modulatory deficits, negatively impacting motor behavior.

Age-related differences in network flexibility and segregation at rest and during motor performance.

Brain networks undergo widespread changes in older age. A large body of knowledge gathered about those changes evidenced an increase of functional connectivity between brain networks. Previous work focused mainly on cortical networks during the resting state. Subcortical structures, however, are of critical importance during the performance of motor tasks. In this study, we investigated age-related changes in cortical, striatal and cerebellar functional connectivity at rest and its modulation by motor task execution. To that end, functional MRI from twenty-five young (mean age 21.5 years) and eighteen older adults (mean age 68.6 years) were analysed during rest and while performing a bimanual tracking task practiced over a two-week period. We found that inter-network connectivity among cortical structures was more positive in older adults both during rest and task performance. Functional connectivity within striatal structures decreased with age during rest and task execution. Network flexibility, the changes in network composition from rest to task, was also reduced in older adults, but only in networks with an age-related increase in connectivity. Finally, flexibility of areas in the prefrontal cortex were associated with lower error scores during task execution, especially in older adults. In conclusion, our findings indicate an age-related reduction in the ability to suppress irrelevant network communication, leading to less segregated and less flexible cortical networks. At the same time, striatal connectivity is impaired in older adults, while cerebellar connectivity shows heterogeneous age-related effects during rest and task execution. Future research is needed to clarify how cortical and subcortical connectivity changes relate to one another.

Quantum Bath Control with Nuclear Spin State Selectivity via Pulse-Adjusted Dynamical Decoupling.

Dynamical decoupling (DD) is a powerful method for controlling arbitrary open quantum systems. In quantum spin control, DD generally involves a sequence of timed spin flips (π rotations) arranged to either average out or selectively enhance coupling to the environment. Experimentally, errors in the spin flips are inevitably introduced, motivating efforts to optimize error-robust DD. Here we invert this paradigm: by introducing particular control "errors" in standard DD, namely, a small constant deviation from perfect π rotations (pulse adjustments), we show we obtain protocols that retain the advantages of DD while introducing the capabilities of quantum state readout and polarization transfer. We exploit this nuclear quantum state selectivity on an ensemble of nitrogen-vacancy centers in diamond to efficiently polarize the ^{13}C quantum bath. The underlying physical mechanism is generic and paves the way to systematic engineering of pulse-adjusted protocols with nuclear state selectivity for quantum control applications.

Age-Related Declines in Motor Performance are Associated With Decreased Segregation of Large-Scale Resting State Brain Networks.

Aging is typically associated with substantial declines in motor functioning as well as robust changes in the functional organization of brain networks. Previous research has investigated the link between these 2 age-varying factors but examinations were predominantly limited to the functional organization within motor-related brain networks. Little is known about the relationship between age-related behavioral impairments and changes in functional organization at the whole brain (i.e., multiple network) level. This knowledge gap is surprising given that the decreased segregation of brain networks (i.e., increased internetwork connectivity) can be considered a hallmark of the aging process. Accordingly, we investigated the association between declines in motor performance across the adult lifespan (20-75 years) and age-related modulations of functional connectivity within and between resting state networks. Results indicated that stronger internetwork resting state connectivity observed as a function of age was significantly related to worse motor performance. Moreover, performance had a significantly stronger association with the strength of internetwork as compared with intranetwork connectivity, including connectivity within motor networks. These findings suggest that age-related declines in motor performance may be attributed to a breakdown in the functional organization of large-scale brain networks rather than simply age-related connectivity changes within motor-related networks.

Imaging Correlations in Heterodyne Spectra for Quantum Displacement Sensing.

The extraordinary sensitivity of the output field of an optical cavity to small quantum-scale displacements has led to breakthroughs such as the first detection of gravitational waves and of the motions of quantum ground-state cooled mechanical oscillators. While heterodyne detection of the output optical field of an optomechanical system exhibits asymmetries which provide a key signature that the mechanical oscillator has attained the quantum regime, important quantum correlations are lost. In turn, homodyning can detect quantum squeezing in an optical quadrature but loses the important sideband asymmetries. Here we introduce and experimentally demonstrate a new technique, subjecting the autocorrelators of the output current to filter functions, which restores the lost heterodyne correlations (whether classical or quantum), drastically augmenting the useful information accessible. The filtering even adjusts for moderate errors in the locking phase of the local oscillator. Hence we demonstrate the single-shot measurement of hundreds of different field quadratures allowing the rapid imaging of detailed features from a simple heterodyne trace. We also obtain a spectrum of hybrid homodyne-heterodyne character, with motional sidebands of combined amplitudes comparable to homodyne. Although investigated here in a thermal regime, the method's robustness and generality represents a promising new approach to sensing of quantum-scale displacements.

Antibacterial and antifungal activities of pyroligneous acid from wood of Eucalyptus urograndis and Mimosa tenuiflora.

AIMS: This work aimed to evaluate the antibacterial and antifungal activities of two types of pyroligneous acid (PA) obtained from slow pyrolysis of wood of Mimosa tenuiflora and of a hybrid of Eucalyptus urophylla × Eucalyptus grandis. METHODS AND RESULTS: Wood wedges were carbonized on a heating rate of 1·25°C min-1 until 450°C. Pyrolysis smoke was trapped and condensed to yield liquid products. Crude pyrolysis liquids were bidistilled under 5 mmHg vacuum yielding purified PA. Multi-antibiotic-resistant strains of Escherichia coli, Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) had their sensitivity to PA evaluated using agar diffusion test. Two yeasts were evaluated as well, Candida albicans (ATCC 10231) and Cryptococcus neoformans. GC-MS analysis of both PAs was carried out to obtain their chemical composition. Regression analysis was performed, and models were adjusted, with diameter of inhibition halos and PA concentration (100, 50 and 20%) as parameters. Identity of regression models and equality of parameters in polynomial orthogonal equations were verified. Inhibition halos were observed in the range 15-25 mm of diameter. CONCLUSIONS: All micro-organisms were inhibited by both types of PA even in the lowest concentration of 20%. SIGNIFICANCE AND IMPACT OF THE STUDY: The feasibility of the usage of PAs produced with wood species planted in large scale in Brazil was evident and the real potential as a basis to produce natural antibacterial and antifungal agents, with real possibility to be used in veterinary and zootechnical applications.

Nonlinear Dynamics and Strong Cavity Cooling of Levitated Nanoparticles.

Optomechanical systems explore and exploit the coupling between light and the mechanical motion of macroscopic matter. A nonlinear coupling offers rich new physics, in both quantum and classical regimes. We investigate a dynamic, as opposed to the usually studied static, nonlinear optomechanical system, comprising a nanosphere levitated in a hybrid electro-optical trap. The cavity offers readout of both linear-in-position and quadratic-in-position (nonlinear) light-matter coupling, while simultaneously cooling the nanosphere, for indefinite periods of time and in high vacuum. We observe the cooling dynamics via both linear and nonlinear coupling. As the background gas pressure was lowered, we observed a greater than 1000-fold reduction in temperature before temperatures fell below readout sensitivity in the present setup. This Letter opens the way to strongly coupled quantum dynamics between a cavity and a nanoparticle largely decoupled from its environment.

Cavity cooling a single charged levitated nanosphere.

Optomechanical cavity cooling of levitated objects offers the possibility for laboratory investigation of the macroscopic quantum behavior of systems that are largely decoupled from their environment. However, experimental progress has been hindered by particle loss mechanisms, which have prevented levitation and cavity cooling in a vacuum. We overcome this problem with a new type of hybrid electro-optical trap formed from a Paul trap within a single-mode optical cavity. We demonstrate a factor of 100 cavity cooling of 400 nm diameter silica spheres trapped in vacuum. This paves the way for ground-state cooling in a smaller, higher finesse cavity, as we show that a novel feature of the hybrid trap is that the optomechanical cooling becomes actively driven by the Paul trap, even for singly charged nanospheres.

Luminescence studies on SnO2 and SnO2:Eu nanocrystals grown by laser assisted flow deposition.

Transparent conductive tin oxide materials have been a research topic extensively studied in recent years due to the great interest for many applications. However, in most of them, the pure form is rarely used, being usually modified by the incorporation of dopants. Selecting the most appropriate technique to develop nanocrystals of doped tin oxide and understanding the influence of dopant on the optical properties are the challenges that need to be addressed when envisaging devices. To fulfill this objective, the recently developed laser assisted flow deposition (LAFD) method is explored to grow SnO2 and SnO2:Eu nanocrystals. The morphology of these nanocrystals was investigated by scanning electron microscopy and well defined prismatic nanocrystals with sizes of ∼60 nm were identified. The crystalline quality assessed by X-ray diffraction measurements and Raman spectroscopy indicates that the produced nanocrystals are monophasic and crystallize in the tetragonal rutile structure. Steady state luminescence studies provide the information on the optical active centres in the SnO2 and SnO2:Eu nanocrystals. For the undoped samples only broad emission bands were observed by pumping the samples in the ultraviolet region. The broad emission was found to be an overlap of green and red optical centres as identified by temperature and excitation intensity dependent luminescence. The latter was found to exhibit an excitonic-related behaviour and the green emission was found to be of utmost importance to discuss the intraionic luminescence in the doped samples. For the SnO2:Eu nanocrystals the luminescence is dominated by the magnetic allowed (5)D0 → (7)F1 transition with the ions in almost undistorted centrosymmetric sites. The ion luminescence integrated intensity is found to increase with increasing temperatures being well accounted for a thermal population provided by the thermal quenching of the green band.

State of refractive surgery with Visian ICL posterior chamber phakic lens in Spain.

OBJECTIVES: To analyse the state of refractive surgery with Visian ICL phakic lens implantation in Spain, indicating the mean ranges of implanted powers, visual and refractive outcomes obtained and safety and efficacy indices. METHOD: This is a population-based, cross-sectional, descriptive, analytical, retrospective, multicentre study in which each co-author collected data from at least the last 10 patients (up to a maximum of 30) with Visian ICL phakic lens implantation. One eye from each subject was randomly selected for study inclusion, and the variables analysed were: age, gender, visual acuities with and without correction pre and post-surgery, preoperative and residualrefraction, keratometry, endothelial cellular density, anterior chamber depth from endothelium, central corneal pachymetry, intraocular pressure, white-white, implanted lens (power and size), expected and achieved spherical equivalent (SEQ) post-surgery at one month after surgery. RESULTS: A sample of 140 eyes was obtained from 140 patients with a mean age of 31.35 ± 7.28 years. Mean preoperative SEQ was -6.33 ± 3.69D, mean CDVA was 0.96 ± 0.16, ACD was 3.30 ± 0.29 mm, WTW 12.02 ± 0.40 mm, CCT 535.03 ± 37.68 µm, ECD 2684.37 ± 313.74 cels/mm2 and IOP 14.84 ± 2.59 mmHg. 66.4% of the implanted lenses were spherical ICLs and 33.6% toric, with a mean power of -7.81 ± 4.09D and a mean cylinder of 2.27 ± 1.23D. 5.7% of the implanted lenses were hypermetropic. The mean SEQ target selected was +0.04 ± 0.27D. 48.92% of the implanted lenses were of size 13.2 mm, with the remaining 36.69, 10.79 and 3.60% being of sizes 12.6, 12.1 and 13.7 mm, respectively. At one month after surgery a residual SEQ of -0.01 ± 0.31D was obtained. The efficacy and safety indices were 1.06 ± 0.18 and 1.10 ± 0.19, respectively. The mean central vault was 508.80 ± 201.04 µm. The accuracy between the calculated SEQ and the obtained SEQ was 99.3% for spherical lenses and 88.2% for Cyl correction. The mean ECD at 1 month after surgery was 2805.53±273.30céls/mm2, which was a difference from preoperative of 0.11% (p = 0.922), similarly, the mean IOP was 13.98 ± 2.57 mmHg, which was a difference of -0.92 ± 2.80 mmHg. CONCLUSIONS: ICL phakic lens surgery is an effective, safe and predictable procedure. There were no significant changes in endothelial cell count or intraocular pressure measurement one month after surgery.

Study of the optical and dielectric properties of TiO2 nanocrystals prepared by the Pechini method.

Titanium oxide nanocrystals synthesized by the Pechini method were calcinated at temperatures between 300 and 1000 degrees C. The crystalline structure was analysed by X-ray diffraction, scanning electron microscopy (SEM) and Raman spectroscopy. A phase transition from the anatase to rutile crystalline phase was found to occur at temperatures near 500 degrees C. The samples were characterized by photoluminescence (PL) and dielectric spectroscopy. The influence of the calcination temperature on the visible and near infrared luminescence is discussed. A correlation between the structural properties, luminescence and dielectric properties are discussed.

The roles of GSTM1 and GSTT1 null genotypes and other predictors in anti-tuberculosis drug-induced liver injury.

WHAT IS KNOWN AND OBJECTIVE: Anti-tuberculosis drugs (ATD), although highly effective, often cause liver injury. Glutathione S-transferases (GST) play a crucial protective role in the detoxifying mechanisms of drugs. Several studies have investigated the genetic null variants of GSTM1 and GSTT1 as possible risk factors for ATD-induced liver injury; however, those findings are inconsistent. We investigated GSTM1 and GSTT1 null genotypes in Brazilian patients with tuberculosis (TB), adjusting for other possible predictors of ATD-induced liver injury. METHODS: This was a prospective cohort study with patients who were treated for TB from 2006 to 2011. GSTM1 and GSTT1 gene deletions were analysed from genomic DNA by polymerase chain reaction (PCR). Demographic, clinical and laboratory data were extracted from medical records and possible predictors of liver injury were evaluated. RESULTS AND DISCUSSION: This study enrolled 177 patients. Anti-tuberculosis drugs-induced liver injury incidence was 33.3%. Hepatitis B infection (HBV) and increased alanine aminotransferase (ALT) baseline were significant predictors. Neither GSTM1 nor GSTT1 null genotypes were associated with ATD-induced liver injury; nevertheless, the comparison among four different liver toxicity grades showed that GSTM1 non-null genotype was significant more frequent among the higher grades of liver toxicity. WHAT IS NEW AND CONCLUSION: GSTM1 and GSTT1 null genotypes do not seem to play important roles in ATD-induced liver injury in Brazilians. However, there was evidence that GSTM1 polymorphisms were possibly related to the intensity of toxicity. Active HBV and initial high ALT could predict ATD-induced liver injury.

Hearing loss in diffuse cutaneous systemic scleroderma.

OBJECTIVES: Patients with diffuse cutaneous systemic sclerosis (dcSSc) have distinct clinical manifestations, usually with more aggressive organ involvement and highermortality than limited cutaneous systemic sclerosis (lcSSC). Hearing loss had not yet been evaluated in this subtype, so our aim was to assess the auditory system of dcSSc patients in a controlled study. METHODS: Twenty-six patients with dcSSc, according to American College of Rheumatology (ACR) criteria, were evaluated. For each dcSSc patient included in the study, two healthy controls were matched for sex and age (± 2 years). All patients responded to a structured questionnaire regarding otological symptoms and risk factors with regard to hearing loss. A complete ear/nose/throat physical examination was performed followed by speech/pure tone audiometry and impedance measurements. RESULTS: The mean age of the dcSSc patients was 47.0 ± 11.9 years; the mean disease duration was 9.4 ± 9.1 years, and there was a clear female predominance (83%). The questionnaire revealed auditory complaints in 54% of the dcSSc patients (25% hearing loss, 21% aural fullness, 21% tinnitus, and 21% dizziness) and normal otoscopy. Nearly half (46%) of the dcSSc patients were diagnosed as having hearing loss on audiogram compared to only 19% in the control group (p = 0.01). All dcSSc with hearing loss had a sensorineural component, eight (73%) with excellent discrimination on the Percentage Index of Speech Recognition (PISR). Descending configuration and Metz recruitment were observed in 54% of these patients, suggesting cochlear involvement. CONCLUSION: Patients with dcSSc have a high prevalence of sensorineural audiometric hearing impairment and otological complaints, suggesting that the cochlea is an additional target organ in this disease.

Electrochemical and photoluminescence response of laser-induced graphene/electrodeposited ZnO composites.

The inherent scalability, low production cost and mechanical flexibility of laser-induced graphene (LIG) combined with its high electrical conductivity, hierarchical porosity and large surface area are appealing characteristics for many applications. Still, other materials can be combined with LIG to provide added functionalities and enhanced performance. This work exploits the most adequate electrodeposition parameters to produce LIG/ZnO nanocomposites. Low-temperature pulsed electrodeposition allowed the conformal and controlled deposition of ZnO rods deep inside the LIG pores whilst maintaining its inherent porosity, which constitute fundamental advances regarding other methods for LIG/ZnO composite production. Compared to bare LIG, the composites more than doubled electrode capacitance up to 1.41 mF cm-2 in 1 M KCl, while maintaining long-term cycle stability, low ohmic losses and swift electron transfer. The composites also display a luminescence band peaked at the orange/red spectral region, with the main excitation maxima at ~ 3.33 eV matching the expected for the ZnO bandgap at room temperature. A pronounced sub-bandgap tail of states with an onset absorption near 3.07 eV indicates a high amount of defect states, namely surface-related defects. This work shows that these environmentally sustainable multifunctional nanocomposites are valid alternatives for supercapacitors, electrochemical/optical biosensors and photocatalytic/photoelectrochemical devices.

Bismuth qubits in silicon: the role of EPR cancellation resonances.

We investigate electron paramagnetic resonance spectra of bismuth-doped silicon, at intermediate magnetic fields B≃0.1-0.6 T, theoretically and experimentally (with 9.7 GHz X-band spectra). We identify a previously unexplored regime of "cancellation resonances," where a component of the hyperfine coupling is resonant with the external field. We show that this regime has experimentally accessible consequences for quantum information applications, such as reduction of decoherence, fast manipulation of the coupled electron-nuclear qubits, and spectral line narrowing.

Structural and optical characterization of ZnO nanowires grown on alumina by thermal evaporation method.

Zinc oxide nanowires have been grown on alumina substrate by thermal evaporation of zinc nanopowder in the presence of oxygen flow. The growth was performed under ambient pressure and without the use of foreign catalyst. Scanning electron microscopy (SEM) observation showed that the as-grown sample consists of bulk ZnO crystal on the substrate surface with nanowires growing from this base. Growth mechanism of the observed morphology is suggested to be governed by the change of zinc vapour supersaturation during the growth process. X-ray diffraction (XRD) measurement was used to identify the crystalline phase of the nanowires. Optical properties of the nanowires were investigated using Raman scattering and photoluminescence (PL). The appearance of dominant, Raman active E2 (high) phonon mode in the Raman spectrum has confirmed the wurtzite hexagonal phase of the nanowires. With above bandgap excitation the low temperature PL recombination is dominated by donor bound exciton luminescence at -3.37 eV with a narrow full width at half maximum. Free exciton emission is also seen at low temperature and can be observed up to room temperature. The optical data indicates that the grown nanowires have high optical quality.

Optical and structural properties of an Eu implanted gallium nitride quantum dots/aluminium nitride superlattice.

GaN/AIN structures made of GaN quantum dots (QDs) separated by AIN spacer layers, were doped with Europium by ion implantation. Rutherford Backscattering/Channelling measurements showed that Eu is incorporated mainly on near-substitutional cation sites within the superlattice region. Only slight deterioration of the crystal quality and no intermixing of the different layers are observed after implantation and annealing. After thermal annealing, photoluminescence associated with Eu3+ ions was observed. From its behaviour under different photon energy excitation and sample temperature we concluded that the Eu-related emitting centres are located inside the GaN QDs or dispersed in the GaN and AIN buffer or spacer layers. The 624 nm PL line, associated with Eu-doped GaN QDs, shows very low thermal quenching, suggesting recombination of confined carriers through rare-earth ion excitation.

Intrinsic p type ZnO films deposited by rf magnetron sputtering.

ZnO films were deposited on c-plane sapphire substrates in Ar atmosphere by rf magnetron sputtering and were post-annealed at 400 degrees C in green gas (95% N2 + 5% H2). The properties of the as-grown and annealed films have been characterized by X-ray diffraction (XRD), Rutherford backscattering (RBS), elastic recoil detection analysis (ERDA), Hall measurement and photoluminescence spectra. XRD studies confirmed the variation in strain and an improvement in crystallinity. From RBS and ERDA analysis, the presence of H atoms on the surface of the as-grown ZnO films was evidenced. Annealing in green gas increased the amount of H in the film. Compared with the as-grown films, the ultra exciting intensity obviously decreases in the annealed films and new optical active centres in the blue/violet (approximately 3.0 eV) and red (approximately 1.9) regions are emerged in the PL spectrum. The positive sign of Hall coefficient confirmed the low p-type conductivity in the as grown films, which was improved after annealing. However, the p-type conductivity was not stable, especially for the annealed sample it changes from p type to n type after 9 days.