Electrical Cardiometry and Cardiac Biomarkers in 24-h and 48-h Ultramarathoners.

Our study aimed to (i) utilize novel electrical cardiometry and observe acute changes in cardiac biomarkers among 24-h and 48-h ultra-marathoners, and (ii) examine whether alterations in cardiac responses were associated with the average running speed of these participants. Twenty-four 24-h and sixteen 48-h ultra-marathoners were recruited. Electrical cardiometry in the 2 groups showed significant post-race drops in systolic pressure (24-h: p=0.001; 48-h: p=0.016) and rapid increases in heart rate (24-h, p=0.004; 48-h, p=0.001). Cardiac output increased in 48-h runners (p=0.012) and stroke volume decreased in 24-h runners (p=0.009) at post-test. Six of 20 (30%) 24-h and 4 of 16 (25%) 48-h runners had high-sensitivity troponin T values above the reference interval after the races. N-terminal proB-type natriuretic peptide levels showed a 15-fold increase in 24-h runners and a 10-fold increase in 48-h runners at post-race. There was a positive correlation between delta N-terminal proB-type natriuretic peptide and running mileage (rs=0.629, p=0.003) in 24-h ultra-marathoners. In conclusion, stroke volume and cardiac output showed inconsistent changes between the 2 groups. Average running speed has a significant effect on post-exercise elevation in cardiac biomarkers.

Graphene Ambipolar Nanoelectronics for High Noise Rejection Amplification.

In a modern wireless communication system, signal amplification is critical for overcoming losses during multiple data transformations/processes and long-distance transmission. Common mode and differential mode are two fundamental amplification mechanisms, and they utilize totally different circuit configurations. In this paper, we report a new type of dual-gate graphene ambipolar device with capability of operating under both common and differential modes to realize signal amplification. The signal goes through two stages of modulation where the phase of signal can be individually modulated to be either in-phase or out-of-phase at two stages by exploiting the ambipolarity of graphene. As a result, both common and differential mode amplifications can be achieved within one single device, which is not possible in the conventional circuit configuration. In addition, a common-mode rejection ratio as high as 80 dB can be achieved, making it possible for low noise circuit application. These results open up new directions of graphene-based ambipolar electronics that greatly simplify the RF circuit complexity and the design of multifunction device operation.

Molecular analysis of codon 548 in the rpoB gene involved in Mycobacterium tuberculosis resistance to rifampin.

Most Mycobacterium tuberculosis rifampin-resistant strains have been associated with mutations in an 81-bp rifampin resistance-determining region (RRDR) in the gene rpoB. However, if this region alone were targeted, rifampin-resistant strains with mutations outside the RRDR would not be detected. In this study, among 51 rifampin-resistant clinical isolates analyzed by sequencing 1,681-bp-long DNA fragments containing the RRDR, 47 isolates contained mutations within the RRDR, three isolates contained mutations both within and outside the RRDR, and only one isolate had a single missense mutation (Arg548His) located outside the RRDR. A drug susceptibility test of recombinant Mycobacterium smegmatis and M. tuberculosis isolates carrying mutated rpoB (Arg548His) showed an increased MIC for rifampin compared to that of the control strains. Modeling of the Arg548His mutant RpoB-DNA complex revealed that the His548 side chain formed a more stable hydrogen bond structure than did Arg548, reducing the flexibility of the rifampin-resistant cluster II region of RpoB, suggesting that the RpoB Arg548His mutant does not effectively interact with rifampin and results in bacterial resistance to the drug. This is the first report on the relationship between the mutation in codon 548 of RpoB and rifampin resistance in tuberculosis. The novel mutational profile of the rpoB gene described here will contribute to the comprehensive understanding of rifampin resistance patterns and to the development of a useful tool for simple and rapid drug susceptibility tests.

Using Unified Theory of Acceptance and Use of Technology to Evaluate the Impact of a Mobile Payment App on the Shopping Intention and Usage Behavior of Middle-Aged Customers.

This research adopted the unified theory of acceptance and use of technology (UTAUT) to emphasize the use of the PX Pay mobile payment app for PX Mart, the most popular supermarket in Taiwan, and examine the degree of involvement as a moderator. The influence of factors related to PX Mart's target customer groups on their shopping intentions and usage behaviors were discussed, with subsequent benefits and optimization directions. This study indicated the following results. First, performance expectations, ease-of-use expectations, and social impact enhance consumers' behavioral intention and behavioral intention significantly influence usage behavior. Second, gender has no significant moderating effect on the proposed model. Third, age has a moderating effect from performance expectations and ease-of-use expectations, social influence on behavioral intention. Fourth, use is more significantly affected by perceived stakeholders for customers over age 50 than for those age 30-39. Fifth, the degree of involvement significantly affects the relationship between behavioral intention and usage behavior in terms of social influence and facilitating conditions effects. Finally, we provided academic and practical implications and make contributions to both the online payment industry and academia.

Neural network based 3D tracking with a graphene transparent focal stack imaging system.

Recent years have seen the rapid growth of new approaches to optical imaging, with an emphasis on extracting three-dimensional (3D) information from what is normally a two-dimensional (2D) image capture. Perhaps most importantly, the rise of computational imaging enables both new physical layouts of optical components and new algorithms to be implemented. This paper concerns the convergence of two advances: the development of a transparent focal stack imaging system using graphene photodetector arrays, and the rapid expansion of the capabilities of machine learning including the development of powerful neural networks. This paper demonstrates 3D tracking of point-like objects with multilayer feedforward neural networks and the extension to tracking positions of multi-point objects. Computer simulations further demonstrate how this optical system can track extended objects in 3D, highlighting the promise of combining nanophotonic devices, new optical system designs, and machine learning for new frontiers in 3D imaging.

The changes of red blood cell viscoelasticity and sports anemia in male 24-hr ultra-marathoners.

BACKGROUND: In endurance sports, stress, dehydration and release of chemical factors have been associated with red blood cell (RBC) alterations of structure and function, which may contribute to sports anemia, a well-observed phenomenon during long-distance running. Until now, the investigation of the changes of viscoelastic properties of RBC membrane, a decisive factor of RBC deformability to avoid hemolysis, is lacking, especially in an Oriental population. METHODS: nineteen runners were prospectively recruited into our study. Hematological parameters were analyzed before and immediately after the 2015 Taipei 24H Ultra-Marathon Festival, Taiwan. Video particle tracking microrheology was used to determine viscoelastic properties of each RBC sample by calculating the dynamic elastic modulus G'(f) and the viscous modulus G″(f) at frequency f = 20 Hz. RESULTS: Haptoglobin, RBC count, hemoglobin, hematocrit, mean cell hemoglobin, plasma free hemoglobin and unsaturated iron-binding capacity values of the recruited runners showed a statistically significant drop in the post-race values. Blood concentration of reticulocyte and ferritin were significantly higher at post-race compared with pre-race. 15 out of the 19 runners had a concurrent change in the elastic and the viscous moduli of their RBCs. Changes in the elastic and the viscous moduli were correlated with changes in the RBC count, hemoglobin and hematocrit. CONCLUSION: Viscoelasticity properties, the elastic modulus G'(f) and the viscous modulus G″(f) of RBCs are associated with endurance exercise-induced anemia.

Realization of mid-infrared graphene hyperbolic metamaterials.

While metal is the most common conducting constituent element in the fabrication of metamaterials, graphene provides another useful building block, that is, a truly two-dimensional conducting sheet whose conductivity can be controlled by doping. Here we report the experimental realization of a multilayer structure of alternating graphene and Al2O3 layers, a structure similar to the metal-dielectric multilayers commonly used in creating visible wavelength hyperbolic metamaterials. Chemical vapour deposited graphene rather than exfoliated or epitaxial graphene is used, because layer transfer methods are easily applied in fabrication. We employ a method of doping to increase the layer conductivity, and our analysis shows that the doped chemical vapour deposited graphene has good optical properties in the mid-infrared range. We therefore design the metamaterial for mid-infrared operation; our characterization with an infrared ellipsometer demonstrates that the metamaterial experiences an optical topological transition from elliptic to hyperbolic dispersion at a wavelength of 4.5 µm.

Microscopic origins of the terahertz carrier relaxation and cooling dynamics in graphene.

The ultrafast dynamics of hot carriers in graphene are key to both understanding of fundamental carrier-carrier interactions and carrier-phonon relaxation processes in two-dimensional materials, and understanding of the physics underlying novel high-speed electronic and optoelectronic devices. Many recent experiments on hot carriers using terahertz spectroscopy and related techniques have interpreted the variety of observed signals within phenomenological frameworks, and sometimes invoke extrinsic effects such as disorder. Here, we present an integrated experimental and theoretical programme, using ultrafast time-resolved terahertz spectroscopy combined with microscopic modelling, to systematically investigate the hot-carrier dynamics in a wide array of graphene samples having varying amounts of disorder and with either high or low doping levels. The theory reproduces the observed dynamics quantitatively without the need to invoke any fitting parameters, phenomenological models or extrinsic effects such as disorder. We demonstrate that the dynamics are dominated by the combined effect of efficient carrier-carrier scattering, which maintains a thermalized carrier distribution, and carrier-optical-phonon scattering, which removes energy from the carrier liquid.

Acute aortic dissection (AAD) in the elderly.

AAD is a relatively uncommon yet catastrophic disease. Though the relationship between AAD and age has been discussed in several previous studies, many facets of the relationship between AAD and the elderly still remain unclear. From a retrospective review of charts from January 1, 2005 to December 31, 2010, we collected data of 132 spontaneous AAD cases in a medical center in Taiwan, 83 of which were enrolled in our study. We divided patients into two groups: one above 65 years old (elderly), and a second, non-elderly group. Data collected for statistical analysis included: clinical manifestations on arrival, time of onset, type of AAD, width of mediastinum, whether or not the patient underwent an operation, number of days spent hospitalized, and in-hospital mortality rates. We found that in the elderly group there were more instances of hyperglycemia (p=0.0001), more neurologic defects (p=0.001), less chest pain (p=0.001), and less abdominal pain (p=0.003). SBP was also lower in the elderly group (139±48mmHg, p=0.0001), while there was no difference in mediastinal width between these two groups. In both groups, most AAD cases were DeBakey type III, but type I AAD was more commonly seen in the elderly (p=0.0011). We found that there were both lower SBP and higher rate of diabetes in the elderly group. The elderly group also had longer hospital stays (14.6±16.3 days, p=0.0001) and almost twice the mortality rate (31.1% vs. 15.8%, p=0.0001).