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Xiaoping Wu, Edward J Auerbach, An T Vu, Steen Moeller, Christophe Lenglet, Sebastian Schmitter, Pierre-François Van de Moortele, Essa Yacoub, Kâmil Uğurbil
PURPOSE: Investigating the utility of RF parallel transmission (pTx) for Human Connectome Project (HCP)-style whole-brain diffusion MRI (dMRI) data at 7 Tesla (7T). METHODS: Healthy subjects were scanned in pTx and single-transmit (1Tx) modes. Multiband (MB), single-spoke pTx pulses were designed to image sagittal slices. HCP-style dMRI data (i.e., 1.05-mm resolutions, MB2, b-values = 1000/2000 s/mm2 , 286 images and 40-min scan) and data with higher accelerations (MB3 and MB4) were acquired with pTx...
March 30, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Cedrigue Boris Djiongo Kenfack, Olivier Monga, Serge Moto Mpong, René Ndoundam
Within the last decade, several approaches using quaternion numbers to handle and model multiband images in a holistic manner were introduced. The quaternion Fourier transform can be efficiently used to model texture in multidimensional data such as color images. For practical application, multispectral satellite data appear as a primary source for measuring past trends and monitoring changes in forest carbon stocks. In this work, we propose a texture-color descriptor based on the quaternion Fourier transform to extract relevant information from multiband satellite images...
March 21, 2018: Acta Biotheoretica
Yanmeng Shi, Shi Che, Kuan Zhou, Supeng Ge, Ziqi Pi, Timothy Espiritu, Takashi Taniguchi, Kenji Watanabe, Yafis Barlas, Roger Lake, Chun Ning Lau
As the Fermi level and band structure of two-dimensional materials are readily tunable, they constitute an ideal platform for exploring the Lifshitz transition, a change in the topology of a material's Fermi surface. Using tetralayer graphene that host two intersecting massive Dirac bands, we demonstrate multiple Lifshitz transitions and multiband transport, which manifest as a nonmonotonic dependence of conductivity on the charge density n and out-of-plane electric field D, anomalous quantum Hall sequences and Landau level crossings that evolve with n, D, and B...
March 2, 2018: Physical Review Letters
Hailong Huang, Hui Xia, Wenke Xie, Zhibo Guo, Hongjian Li, Ding Xie
In this paper, a tunable broadband metamaterial absorber (MA) based on graphene is investigated theoretically and numerically at mid-infrared regions. Compared with the previously reported multiband graphene-based MAs, a broad bandwidth of 11.7 THz with the absorption over 90% is obtained in the proposed MA, which is composed of a Jerusalem cross (JC) metal encrusting into the slot graphene layer in the top layer. The results show that the origin of broadband absorption is caused by coupling effect between metal and graphene, and this effect is explained by the two-mode waveguide coupling theory...
March 8, 2018: Scientific Reports
Alem Gebru, Samuel Jansson, Rickard Ignell, Carsten Kirkeby, Jord C Prangsma, Mikkel Brydegaard
We present a dual-wavelength polarimetric measurement method to distinguish species and sexes of disease transmitting mosquitoes in flight. By measuring co- and de-polarized backscattered light at 808 and 1550 nm, the degree of linear polarization, wingbeat frequency, reflectance, spectral ratio and glossiness of mosquitoes can be retrieved. Body and wing contributions to these signals can be separated. Whereas the optical cross-section is sensitive to the aspect of observation, thus the heading direction of the insect in flight, we demonstrate that polarimetric- and spectral- band ratios are largely invariant to the aspect of observation...
March 5, 2018: Journal of Biophotonics
Sio Hang Pun, Yuanyu Yu, Jian Zhang, Jiujiang Wang, Ching-Hsiang Cheng, Kin Fong Lei, Zhen Yuan, Peng Un Mak
Among the biomedical imaging modalities, photoacoustic computed tomography (PACT) was one of the emerging hybrid techniques in recent years. In designing the PACT imaging system, a finite-bandwidth transducer is one of the limited factors for the overall performance. As the target size is inversely proportional to the dominant frequency components of the generated photoacoustic (PA) signal, a broad bandwidth transducer is desired for different scales' imaging. In this paper, a monolithic multiband capacitive micromachined ultrasonic transducer (CMUT) array was designed and fabricated for the reception of the wideband PA signals so as to provide high-resolution images with high-frequency CMUT arrays and present the high signal-to-noise-ratio major structure with low-frequency CMUT arrays...
March 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Jacob Itzhacki, Bart H W Te Lindert, Wisse P van der Meijden, Morten L Kringelbach, Jorge Mendoza, Eus J W Van Someren
Several studies demonstrated effects of light on affect via projections from the retina of the eye to the circadian clock or via projections to areas involved in mood and reward. Few field studies investigated how naturally fluctuating light levels affect positive and negative mood in everyday life, but none addressed two key components of the reward system: wanting and liking. To elucidate diurnal profiles and immediate effects of dynamically changing light intensity in everyday life, subjective wanting and liking were assessed using experience sampling, while continuously monitoring environmental illuminance...
March 5, 2018: Emotion
Shu-Cheng Dong, Jian Wang, Qi-Jie Tang, Feng-Xin Jiang, Jin-Ting Chen, Yi-Hao Zhang, Zhi-Yue Wang, Jie Chen, Hong-Fei Zhang, Hai-Jiao Jiang, Qing-Feng Zhu, Peng Jiang, Tuo Ji
Infrared sky background level is an important parameter of infrared astronomy observations from the ground, particularly for a candidate site of an infrared capable observatory since low background level is required for such a site. The Chinese astronomical community is looking for a suitable site for a future 12 m telescope, which is designed for working in both optical and infrared wavelengths. However, none of the proposed sites has been tested for infrared observations. Nevertheless, infrared sky background measurements are also important during the design of infrared observing instruments...
February 2018: Review of Scientific Instruments
A A Kalenyuk, A Pagliero, E A Borodianskyi, A A Kordyuk, V M Krasnov
Josephson current provides a phase-sensitive tool for probing the pairing symmetry. Here we present an experimental study of high-quality Josephson junctions between a conventional s-wave superconductor Nb and a multiband iron-pnictide Ba_{1-x}Na_{x}Fe_{2}As_{2}. Junctions exhibit a large enough critical current density to preclude the d-wave symmetry of the order parameter in the pnictide. However, the I_{c}R_{n} product is very small ≃3μV, which is not consistent with the sign-preserving s_{++} symmetry either...
February 9, 2018: Physical Review Letters
Sharna D Jamadar, Francesco Sforazzini, Parnesh Raniga, Nicholas J Ferris, Bryan Paton, Michael J Bailey, Amy Brodtmann, Paul A Yates, Geoffrey A Donnan, Stephanie A Ward, Robyn L Woods, Elsdon Storey, John J McNeil, Gary F Egan
Objectives: The onset of many illnesses is confounded with age and sex. Increasing age is a risk factor for the development of many illnesses, and sexual dimorphism influences brain anatomy, function, and cognition. Here, we examine frequency-specific connectivity in resting-state networks in a large sample (n = 406) of healthy aged adults. Method: We quantify frequency-specific connectivity in three resting-state networks known to be implicated in age-related decline: the default mode, dorsal attention, and salience networks, using multiband functional magnetic resonance imaging...
February 17, 2018: Journals of Gerontology. Series B, Psychological Sciences and Social Sciences
Alexander D Cohen, Andrew S Nencka, Yang Wang
Typical simultaneous blood oxygenation-level dependent (BOLD) and arterial spin labeling (ASL) sequences acquire two echoes, one perfusion-sensitive and one BOLD-sensitive. However, for ASL, spatial resolution and brain coverage are limited due to the T1 decay of the labeled blood. This study applies a sequence combining a multiband acquisition with four echoes for simultaneous BOLD and pseudo-continuous ASL (pCASL) echo planar imaging (MBME ASL/BOLD) for block-design task-fMRI. A multiband acceleration of four was employed to increase brain coverage and reduce slice-timing effects on the ASL signal...
2018: PloS One
Jinchao Tong, Landobasa Y M Tobing, Yu Luo, Dawei Zhang, Dao Hua Zhang
Dual-band photodetection in mid- and near-wave infrared spectral bands is of scientific interest and technological importance. Most of the state-of-the-art mid-infrared photodetectors normally operate at low temperature and/or suffer from toxicity and high cost due to limitations of material properties and device structures. The capability of surface plasmons in confining electromagnetic waves into extremely small volume provides an opportunity for improving the performance for room temperature operation. Here, we report an n-InAsSb/n-GaSb heterostructure photodiode integrated with plasmonic two-dimensional subwavelength hole array (2DSHA) for room temperature two band photodetection...
January 24, 2018: Scientific Reports
Ashish Kaul Sahib, Michael Erb, Justus Marquetand, Pascal Martin, Adham Elshahabi, Silke Klamer, Serge Vulliemoz, Klaus Scheffler, Thomas Ethofer, Niels K Focke
The human brain is known to contain several functional networks that interact dynamically. Therefore, it is desirable to analyze the temporal features of these networks by dynamic functional connectivity (dFC). A sliding window approach was used in an event-related fMRI (visual stimulation using checkerboards) to assess the impact of repetition time (TR) and window size on the temporal features of BOLD dFC. In addition, we also examined the spatial distribution of dFC and tested the feasibility of this approach for the analysis of interictal epileptiforme discharges...
2018: PloS One
Xuan Cao, Gang Lei, Jingjing Feng, Qi Pan, Xiaodong Wen, Yan He
Creating color difference and improving the color resolution in digital imaging is crucial for better application of color analysis. Herein, a novel color modulation analysis strategy was developed by using a homemade tunable multiband laser illumination device, in which the portions of R, G, and B components of the illumination light are discretionarily adjustable, and hence the sample color could be visually modulated continuously in the RGB color space. Through this strategy, the color appearance of single gold nanorods (AuNRs) under dark-field microscopy was migrated from the spectrally insensitive red region to the spectrally sensitive green-yellow region...
February 20, 2018: Analytical Chemistry
Makoto Uji, Ross Wilson, Susan T Francis, Karen J Mullinger, Stephen D Mayhew
We established an optimal combination of EEG recording during sparse multiband (MB) fMRI that preserves high-resolution, whole-brain fMRI coverage while enabling broad-band EEG recordings which are uncorrupted by MRI gradient artefacts (GAs). We first determined the safety of simultaneous EEG recording during MB fMRI. Application of MB factor = 4 produced <1°C peak heating of electrode/hardware during 20 min of GE-EPI data acquisition. However, higher SAR sequences require specific safety testing, with greater heating observed using PCASL with MB factor = 4...
April 2018: Human Brain Mapping
Katharina Paul, Till Huelnhagen, Eva Oberacker, Daniel Wenz, André Kuehne, Helmar Waiczies, Sebastian Schmitter, Oliver Stachs, Thoralf Niendorf
Diffusion-weighted imaging (DWI) provides information on tissue microstructure. Single-shot echo planar imaging (EPI) is the most common technique for DWI applications in the brain, but is prone to geometric distortions and signal voids. Rapid acquisition with relaxation enhancement [RARE, also known as fast spin echo (FSE)] imaging presents a valuable alternative to DWI with high anatomical accuracy. This work proposes a multi-shot diffusion-weighted RARE-EPI hybrid pulse sequence, combining the anatomical integrity of RARE with the imaging speed and radiofrequency (RF) power deposition advantage of EPI...
March 2018: NMR in Biomedicine
S Conti, A Perali, F M Peeters, D Neilson
Superfluidity in coupled electron-hole sheets of bilayer graphene is predicted here to be multicomponent because of the conduction and valence bands. We investigate the superfluid crossover properties as functions of the tunable carrier densities and the tunable energy band gap E_{g}. For small band gaps there is a significant boost in the two superfluid gaps, but the interaction-driven excitations from the valence to the conduction band can weaken the superfluidity, even blocking the system from entering the Bose-Einstein condensate (BEC) regime at low densities...
December 22, 2017: Physical Review Letters
Jenni Schulz, José P Marques, Annemieke Ter Telgte, Anouk van Dorst, Frank-Erik de Leeuw, Frederick J A Meijer, David G Norris
As a single-shot sequence with a long train of refocusing pulses, Half-Fourier Acquisition Single-Shot Turbo-Spin-Echo (HASTE) suffers from high power deposition limiting use at high resolutions and high field strengths, particularly if combined with acceleration techniques such as simultaneous multi-slice (SMS) imaging. Using a combination of multiband (MB)-excitation and PINS-refocusing pulses will effectively accelerate the acquisition time while staying within the SAR limitations. In particular, uncooperative and young patients will profit from the speed of the MB-PINS HASTE sequence, as clinical diagnosis can be possible without sedation...
January 2018: European Journal of Radiology
Joaquín Rodríguez-Sánchez, Eva De la Santa Belda, Pilar Olivencia Palomar, Margarita Úbeda Muñoz, José Olmedo Camacho
BACKGROUND AND STUDY AIMS:  Endoscopic mucosal resection is the gold standard treatment for non-pedunculated colorectal polyps; however, some specific situations (location behind folds, scarred or flat morphology) can make this technique challenging. We aimed to assess the efficacy and safety of multiband mucosectomy (MBM) for resection of non-pedunculated colorectal polyps. PATIENTS AND METHODS:  This was a retrospective study of patients in whom MBM was performed to resect large non-pedunculated colorectal polyps...
March 2018: Endoscopy
Rachael M Tillman, Melissa D Stockbridge, Brendon M Nacewicz, Salvatore Torrisi, Andrew S Fox, Jason F Smith, Alexander J Shackman
The central extended amygdala (EAc)-including the bed nucleus of the stria terminalis (BST) and central nucleus of the amygdala (Ce)-plays a critical role in triggering fear and anxiety and is implicated in the development of a range of debilitating neuropsychiatric disorders. Although it is widely believed that these disorders reflect the coordinated activity of distributed neural circuits, the functional architecture of the EAc network and the degree to which the BST and the Ce show distinct patterns of functional connectivity is unclear...
March 2018: Human Brain Mapping
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