159 research outputs found

    Near-infrared spectroscopy as a tool for in vivo analysis of human muscles

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    Recent advances in materials and fabrication techniques provided portable, performant, sensing optical spectrometers readily operated by user-friendly cabled or wireless systems. Such systems allow rapid, non-invasive, and not destructive quantitative analysis of human tissues. This proof-of-principle investigation tested whether infrared spectroscopy techniques, currently utilized in a variety of areas, could be applied in living humans to categorize muscles. Using an ASD FieldSpec\uae 4 Standard-Res Spectroradiometer with a spectral sampling capability of 1.4 nm at 350\u20131000 nm and 1.1 nm at 1001\u20132500 nm, we acquired reflectance spectra in visible short-wave infra-red regions (350\u20132500 nm) from the upper limb muscles (flexors and extensors) of 20 healthy subjects (age 25\u201389 years, 9 women). Spectra off-line analysis included preliminary preprocessing, Principal Component Analysis, and Partial Least-Squares Discriminant Analysis. Near-infrared (NIR) spectroscopy proved valuable for noninvasive assessment of tissue optical properties in vivo. In addition to the non-invasive detection of tissue oxygenation, NIR spectroscopy provided the spectral signatures (ie, \u201cfingerprints\u201d) of upper limb flexors and extensors, which represent specific, accurate, and reproducible measures of the overall biological status of these muscles. Thus, non-invasive NIR spectroscopy enables more thorough evaluation of the muscular system and optimal monitoring of the effectiveness of therapeutic or rehabilitative interventions

    The Ventricular System Enlarges Abnormally in the Seventies, Earlier in Men, and First in the Frontal Horn: A Study Based on More Than 3,000 Scans

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    Objectives: To detect on computed tomography (CT) brain scans the trajectories of normal and abnormal ventricular enlargement during aging. Methods: For each 1-year age cohort, we assessed in 3,193 axial CT scans the Evans’ index (EI) in the anterior frontal horns and the parieto-occipital (POR) and temporal ratio (TR) in the posterior and inferior horns. Cut-off values for abnormal enlargement were based on previous clinical studies. Results: The mean age associated with normal linear measures was 71 years. Values for all three measures increased with age, showing a linear relationship below—but not above—each cut-off value. The mean age of participants with abnormal enlargement on CT progressed from 79 years for EI to 83 years for POR to 87 years for TR. These results suggested that ventricular dilatation progresses in an age–location relationship. First comes enlargement of the frontal horns (13.8% of scans), followed by the parieto-occipital horns (15.1% of scans) and then temporal horn enlargement (6.8% of scans). Scans from men displayed abnormal values earlier than scans from women (on average 6 years). Risk increased 5.1% annually for abnormal EI, 9.0% for abnormal POR, and 11% for abnormal TR (all p < 0.001). The most frequent agreement between categories (normal–abnormal) for values of neuroimaging measures was identified for POR–TR. Conclusion: The results of this large radiological study suggest that the ventricular system enlarges progressively during aging, and in a subset of patients follows an abnormal consecutive geometric dilatation, influenced by age and sex

    Qualitative aspects of entanglement in the Jaynes-Cummings model with an external quantum field

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    We present a mathematical procedure which leads us to obtain analytical solutions for the atomic inversion and Wigner function in the framework of the Jaynes-Cummings model with an external quantum field, for any kinds of cavity and driving fields. Such solutions are expressed in the integral form, with their integrands having a commom term that describes the product of the Glauber-Sudarshan quasiprobability distribution functions for each field, and a kernel responsible for the entanglement. Considering two specific initial states of the tripartite system, the formalism is then applied to calculate the atomic inversion and Wigner function where, in particular, we show how the detuning and amplitude of the driving field modify the entanglement. In addition, we also obtain the correctComment: 15 pages and 21 figure

    Factors influencing overall survival rates for patients with pineocytoma

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    Given its rarity, appropriate treatment for pineocytoma remains variable. As the literature primarily contains case reports or studies involving a small series of patients, prognostic factors following treatment of pineocytoma remain unclear. We therefore compiled a systematic review of the literature concerning post-treatment outcomes for pineocytoma to better determine factors associated with overall survival among patients with pineocytoma. We performed a comprehensive search of the published English language literature to identify studies containing outcome data for patients undergoing treatment for pineocytoma. Kaplan–Meier analysis was utilized to determine overall survival rates. Our systematic review identified 168 total patients reported in 64 articles. Among these patients, 21% underwent biopsy, 38% underwent subtotal resection, 42% underwent gross total resection, and 29% underwent radiation therapy, either as mono- or adjuvant therapy. The 1 and 5 year overall survival rates for patients receiving gross total resection versus subtotal resection plus radiotherapy were 91 versus 88%, and 84 versus 17%, respectively. When compared to subtotal resection alone, subtotal resection plus radiation therapy did not offer a significant improvement in overall survival. Gross total resection is the most appropriate treatment for pineocytoma. The potential benefit of conventional radiotherapy for the treatment of these lesions is unproven, and little evidence supports its use at present

    Microstructural and mechanical characterisation of laser-welded high-carbon and stainless steel

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    The final publication is available at Springer via http://dx.doi.org/10.1007/s00170-015-7111-5Laser welding is becoming an important joining technique for welding of stainless steel to carbon steel and is extensively used across various sectors, including aerospace, transportation, power plants, electronics and other industries. However, welding of stainless steel to high-carbon steel is still at its early stage, predominantly due to the formation of hard brittle phases, which undermine the mechanical strength of the joint. This study reports a scientific investigation on controlling the brittle phase formation during laser dissimilar welding of high-carbon steel to stainless steel. Attempts have been made to tailor the microstructure and phase composition of the fusion zone through influencing the alloying composition and the cooling rate. Results show that the heat-affected zone (HAZ) within the high-carbon steel has significantly higher hardness than the weld area, which severely undermines the weld quality. To reduce the hardness of the HAZ, a new heat treatment strategy was proposed and evaluated using a finite element analysis-based numerical simulation model. A series of experiments has been performed to verify the developed thermo-metallurgical finite element analysis (FEA) model, and a qualitative agreement of predicted martensitic phase distribution is shown to exist

    Feshbach resonances and mesoscopic phase separation near a quantum critical point in multiband FeAs-based superconductors

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    High Tc superconductivity in FeAs-based multilayers (pnictides), evading temperature decoherence effects in a quantum condensate, is assigned to a Feshbach resonance (called also shape resonance) in the exchange-like interband pairing. The resonance is switched on by tuning the chemical potential at an electronic topological transition (ETT) near a band edge, where the Fermi surface topology of one of the subbands changes from 1D to 2D topology. We show that the tuning is realized by changing i) the misfit strain between the superconducting planes and the spacers ii) the charge density and iii) the disorder. The system is at the verge of a catastrophe i.e. near a structural and magnetic phase transition associated with the stripes (analogous to the 1/8 stripe phase in cuprates) order to disorder phase transition. Fine tuning of both the chemical potential and the disorder pushes the critical temperature Ts of this phase transition to zero giving a quantum critical point. Here the quantum lattice and magnetic fluctuations promote the Feshbach resonance of the exchange-like anisotropic pairing. This superconducting phase that resists to the attacks of temperature is shown to be controlled by the interplay of the hopping energy between stripes and the quantum fluctuations. The superconducting gaps in the multiple Fermi surface spots reported by the recent ARPES experiment of D. V. Evtushinsky et al. arXiv:0809.4455 are shown to support the Feshbach scenario.Comment: 31 pages, 7 figure
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