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Low-intensity pulsed

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https://www.readbyqxmd.com/read/27929036/optimal-generation-of-spatially-coherent-soft-x-ray-isolated-attosecond-pulses-in-a-gas-filled-waveguide-using-two-color-synthesized-laser-pulses
#1
Cheng Jin, Kyung-Han Hong, C D Lin
We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays...
December 8, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27925675/effect-of-increasing-low-intensity-pulsed-ultrasound-and-a-functional-appliance-on-the-mandibular-condyle-in-growing-rats
#2
Harmanpreet Kaur, Hasan Uludağ, Douglas N Dederich, Tarek El-Bialy
OBJECTIVES: Functional appliances are used for treatment of lower-jaw deficiencies in growing individuals; however, their effectiveness is debatable. Low-intensity pulsed ultrasound (US) is a noninvasive method, which has been shown to stimulate cartilage and bone formation with 20 minutes of application. This study was designed to test the hypothesis that increasing low-intensity pulsed US application from 20 to 40 min/d will enhance mandibular condylar growth in growing rats, especially when combined with a functional appliance...
November 28, 2016: Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine
https://www.readbyqxmd.com/read/27920804/bone-healing-in-2016
#3
REVIEW
John A Buza, Thomas Einhorn
Delayed fracture healing and nonunion occurs in up to 5-10% of all fractures, and can present a challenging clinical scenario for the treating physician. Methods for the enhancement of skeletal repair may benefit patients that are at risk of, or have experienced, delayed healing or nonunion. These methods can be categorized into either physical stimulation therapies or biological therapies. Physical stimulation therapies include electrical stimulation, low-intensity pulsed ultrasonography, or extracorporeal shock wave therapy...
May 2016: Clinical Cases in Mineral and Bone Metabolism
https://www.readbyqxmd.com/read/27918005/a-review-of-melasma-treatment-focusing-on-laser-and-light-devices
#4
Janet Y Li, Elizabeth Rc Geddes, Deanne M Robinson, Paul M Friedman
Melasma is a pigmentary disorder of unclear etiology with numerous treatment options and high recurrence rates. Laser and light therapies may be utilized cautiously as second- or third-line options for recalcitrant melasma, but low-energy settings are preferred due to the risk of postinflammatory hyperpigmentation and melasma stimulation. Commonly used lasers include the low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, nonablative fractionated lasers, and intense pulsed light. Strict sun protection, concomitant use of bleaching agents, and maintenance treatments are necessary...
December 2016: Seminars in Cutaneous Medicine and Surgery
https://www.readbyqxmd.com/read/27886497/large-cross-phase-modulations-at-the-few-photon-level
#5
Zi-Yu Liu, Yi-Hsin Chen, Yen-Chun Chen, Hsiang-Yu Lo, Pin-Ju Tsai, Ite A Yu, Ying-Cheng Chen, Yong-Fan Chen
We demonstrate an efficient cross-phase modulation (XPM) based on a closed-loop double-Λ system. The property of the double-Λ medium can be controlled by changing the phases of the applied optical fields. This phase-dependent XPM scheme can achieve large phase modulations at low-light intensities without requiring cavities or tightly focusing laser beams. With this scheme, we observe a π-level phase shift with two pulses, both consisting of eight photons in cold rubidium atoms. Such a novel scheme provides a simple route to generate strong interactions between photons and may have potential applications in all-optical quantum signal processing...
November 11, 2016: Physical Review Letters
https://www.readbyqxmd.com/read/27886089/representation-method-for-spectrally-overlapping-signals-in-flow-cytometry-based-on-fluorescence-pulse-time-delay-estimation
#6
Wenchang Zhang, Xiaoping Lou, Xiaochen Meng, Lianqing Zhu
Flow cytometry is being applied more extensively because of the outstanding advantages of multicolor fluorescence analysis. However, the intensity measurement is susceptible to the nonlinearity of the detection method. Moreover, in multicolor analysis, it is impossible to discriminate between fluorophores that spectrally overlap; this influences the accuracy of the fluorescence pulse signal representation. Here, we focus on spectral overlap in two-color analysis, and assume that the fluorescence follows the single exponential decay model...
November 23, 2016: Sensors
https://www.readbyqxmd.com/read/27885999/peripheral-vasomotor-activity-assessment-using-a-continuous-wavelet-analysis-on-webcam-photoplethysmographic-signals
#7
F Bousefsaf, C Maaoui, A Pruski
BACKGROUND: Vasoconstriction and vasodilation phenomena reflect the relative changes in the vascular bed. They induce particular modifications in the pulse wave magnitude. Webcams correspond to remote sensors that can be employed to measure the pulse wave in order to compute the pulse frequency. OBJECTIVE: Record and analyze pulse wave signal with a low-cost webcam to extract the amplitude information and assess the vasomotor activity of the participant. METHODS: Photoplethysmographic signals obtained from a webcam are analyzed through a continuous wavelet transform...
November 25, 2016: Bio-medical Materials and Engineering
https://www.readbyqxmd.com/read/27884775/tuning-acoustic-and-mechanical-properties-of-materials-for-ultrasound-phantoms-and-smart-substrates-for-cell-cultures
#8
A Cafarelli, A Verbeni, A Poliziani, P Dario, A Menciassi, L Ricotti
: Materials with tailored acoustic properties are of great interest for both the development of tissue-mimicking phantoms for ultrasound tests and smart scaffolds for ultrasound mediated tissue engineering and regenerative medicine. In this study, we assessed the acoustic properties (speed of sound, acoustic impedance and attenuation coefficient) of three different materials (agarose, polyacrylamide and polydimethylsiloxane) at different concentrations or cross-linking levels and doped with different concentrations of barium titanate ceramic nanoparticles...
November 21, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27883051/lipid-coated-microbubbles-and-low-intensity-pulsed-ultrasound-enhance-chondrogenesis-of-human-mesenchymal-stem-cells-in-3d-printed-scaffolds
#9
Mitra Aliabouzar, Lijie Grace Zhang, Kausik Sarkar
Lipid-coated microbubbles are used to enhance ultrasound imaging and drug delivery. Here we apply these microbubbles along with low intensity pulsed ultrasound (LIPUS) for the first time to enhance proliferation and chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in a 3D printed poly-(ethylene glycol)-diacrylate (PEG-DA) hydrogel scaffold. The hMSC proliferation increased up to 40% after 5 days of culture in the presence of 0.5% (v/v) microbubbles and LIPUS in contrast to 18% with LIPUS alone...
November 24, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27875128/towards-a-robust-estimation-of-respiratory-rate-from-pulse-oximeters
#10
Marco A F Pimentel, Alistair E W Johnson, Peter H Charlton, Drew Birrenkott, Peter J Watkinson, Lionel Tarassenko, David A Clifton
OBJECTIVE: Current methods for estimating respiratory rate (RR) from the photoplethysmogram (PPG) typically fail to distinguish between periods of high- and low-quality input data, and fail to perform well on independent "validation" datasets. The lack of robustness of existing methods directly results in a lack of penetration of such systems into clinical practice. The present work proposes an alternative method to improve the robustness of the estimation of RR from the PPG. METHODS: The proposed algorithm is based on the use of multiple autoregressive models of different orders for determining the dominant respiratory frequency in the three respiratory-induced variations (frequency, amplitude and intensity) derived from the PPG...
November 18, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/27874284/effects-of-extremely-low-frequency-pulsed-electromagnetic-fields-elf-pemfs-on-glioblastoma-cells-u87
#11
Zeinab Akbarnejad, Hossein Eskandary, Cristian Vergallo, Seyed Noureddin Nematollahi-Mahani, Luciana Dini, Fatemeh Darvishzadeh-Mahani, Meysam Ahmadi
The impact of extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs) at various frequencies and amplitudes was investigated on cell cycle, apoptosis and viability of the Glioblastoma Multiforme (GBM) cell line (U87), in vitro. The GBM is a malignant brain tumor with high mortality in humans and poorly responsive to the most common type of cancer treatments, such as surgery, chemotherapy and radiation therapy. U87 cells with five experimental groups (I-V) were exposed to various ELF-PEMFs for 2, 4 and 24 h, as follows: (I) no exposure, control; (II) 50 Hz 100 ± 15 G; (III) 100 Hz 100 ± 15 G; (IV) 10 Hz 50 ± 10 G; (V) 50 Hz 50 ± 10 G...
November 22, 2016: Electromagnetic Biology and Medicine
https://www.readbyqxmd.com/read/27869832/generation-of-high-contrast-and-high-spatial-quality-idler-from-a-low-gain-optical-parametric-amplifier
#12
A B Sharba, G Nersisyan, M Zepf, N H Stuart, R A Smith, M Borghesi, G Sarri
The temporal contrast of a regeneratively amplified, sub-picosecond pulse is enhanced by employing a low-gain optical parametric amplification stage self-pumped by the second harmonic of the pulse. Through careful characterization of the two related nonlinear processes and optimization of the non-collinear geometry, a robust high-contrast idler pulse has been generated, with excellent spatial quality in both the near and far field. The overall energy conversion efficiency exceeds 14%, with 33% intensity conversion efficiency...
November 20, 2016: Applied Optics
https://www.readbyqxmd.com/read/27868127/digital-dna-detection-based-on-a-compact-optofluidic-laser-with-ultra-low-sample-consumption
#13
Wonsuk Lee, Qiushu Chen, Xudong Fan, Dong Ki Yoon
DNA lasers self-amplify optical signals from a DNA analyte as well as thermodynamic differences between sequences, allowing quasi-digital DNA detection. However, these systems have drawbacks, such as relatively large sample consumption and complicated dye labelling. Moreover, although the lasing signal can detect the target DNA, it is superimposed on an unintended fluorescence background, which persists for non-target DNA samples as well. From an optical point of view, it is thus not truly digital detection and requires spectral analysis to identify the target...
November 29, 2016: Lab on a Chip
https://www.readbyqxmd.com/read/27865881/modulation-of-quadriceps-corticospinal-excitability-by-femoral-nerve-stimulation
#14
Dan Río-Rodríguez, Eliseo Iglesias-Soler, Y Miguel Fernandez-Del-Olmo
INTRODUCTION: We explored the conditioning effect of a percutaneous electrical pulse of the femoral nerve on cortical motor evoked responses in the rectus femoris muscle. METHODS: Corticospinal excitability of rectus femoris muscle was measured in sixteen healthy subjects, when a single transcranial magnetic pulse was preceded by an electrical femoral nerve stimulus, using twelve inter-stimulus intervals (from 10 to 275ms). We also evaluated the effects of the intensities of the transcranial magnetic and of the electrical pulses...
November 16, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27858967/placental-pulsatility-index-a-new-more-sensitive-parameter-for-predicting-adverse-outcome-in-pregnancies-suspected-of-fetal-growth-restriction
#15
Saemundur Gudmundsson, Kari Flo, Gisela Ghosh, Tom Wilsgaard, Ganesh Acharya
INTRODUCTION: The pulsatility indices (PI) of the umbilical (UA) and uterine (UtA) arteries are used as the surrogate measures of utero-placental perfusion. Combining the two might simplify the evaluation of total placental vascular impedance, possibly improve prediction of adverse outcomes and help to identify pregnancies with suspected fetal growth restriction that need more intense surveillance. MATERIAL AND METHODS: UA and UtA blood flow velocities were recorded using pulsed-wave Doppler in a longitudinal study of 53 low-risk pregnancies (248 observations) during 20-40 weeks of gestation...
November 17, 2016: Acta Obstetricia et Gynecologica Scandinavica
https://www.readbyqxmd.com/read/27852520/evaluating-the-impact-of-watercell-%C3%A2-technology-on-pressure-redistribution-and-comfort-discomfort-of-adults-with-limited-mobility
#16
Carol Bartley, Melanie Stephens
AIM OF THE STUDY: The aim of the study was to evaluate the effect of WaterCell(®) Technology on pressure redistribution and self-reported comfort and discomfort scores of adults with mobility problems who remain seated for extended periods of time. METHODS: Twelve participants, were recruited and ranged in gender, age, height, weight, and body mass index. Five were male, seven were female, and five were permanent wheelchair users. Each participant was randomly allocated a chair, whose seat comprised of visco-elastic memory foam, high-elastic reflex foam, and watercells, to trial for a week...
November 5, 2016: Journal of Tissue Viability
https://www.readbyqxmd.com/read/27828039/implementation-of-a-svwp-based-laser-beam-shaping-technique-for-generation-of-100-mj-level-picosecond-pulses
#17
J Adamonis, A Aleknavičius, K Michailovas, S Balickas, V Petrauskienė, T Gertus, A Michailovas
We present implementation of the energy-efficient and flexible laser beam shaping technique in a high-power and high-energy laser amplifier system. The beam shaping is based on a spatially variable wave plate (SVWP) fabricated by femtosecond laser nanostructuring of glass. We reshaped the initially Gaussian beam into a super-Gaussian (SG) of the 12th order with efficiency of about 50%. The 12th order of the SG beam provided the best compromise between large fill factor, low diffraction on the edges of the active media, and moderate intensity distribution modification during free-space propagation...
October 1, 2016: Applied Optics
https://www.readbyqxmd.com/read/27827347/imaging-pulsed-laser-deposition-growth-of-homo-epitaxial-srtio3-by-low-energy-electron-microscopy
#18
A J H van der Torren, S J van der Molen, J Aarts
By combining low-energy electron microscopy with in situ pulsed laser deposition we have developed a new technique for film growth analysis, making use of both diffraction and real-space information. Working at the growth temperature, we can use: the intensity and profile variations of the specular beam to follow the coverage in a layer-by-layer fashion; real-space microscopy to follow e.g. atomic steps at the surface; and electron reflectivity to probe the unoccupied band structure of the grown material. Here, we demonstrate our methodology for homo-epitaxial growth of SrTiO3...
November 9, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27814934/effect-of-low-intensity-pulsed-ultrasound-on-a-rat-model-of-dentin-dental-pulp-injury-and-repair
#19
Fei Wang, Yueheng Li, Zhengyan Yang, Keke Lu, Jing Zuo, Zhi Zhou
This study investigated histopathologic changes in dental pulp after treatment with low-intensity pulsed ultrasound (LIPUS). Fifty rats were randomly divided into an experimental group (n = 25) and a blank control group (n = 25). In the experimental group, a cavity was prepared in the bilateral maxillary first molars. The upper right first molars were stimulated with LIPUS (30 mW/cm(2), 1.5 MHz) for 20 min/d. The cavities prepared in the left teeth were used as experimental controls (i.e., no LIPUS)...
January 2017: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/27805636/ultra-stable-high-average-power-femtosecond-laser-system-tunable-from-1-33-to-20%C3%A2-%C3%A2-%C3%AE-m
#20
Tobias Steinle, Florian Mörz, Andy Steinmann, Harald Giessen
A highly stable 350 fs laser system with a gap-free tunability from 1.33 to 2.0 μm and 2.13 to 20 μm is demonstrated. Nanojoule-level pulse energy is achieved in the mid-infrared at a 43 MHz repetition rate. The system utilizes a post-amplified fiber-feedback optical parametric oscillator followed by difference frequency generation between the signal and idler. No locking or synchronization electronics are required to achieve outstanding free-running output power and spectral stability of the whole system...
November 1, 2016: Optics Letters
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