520 research outputs found
Casimir effect of an ideal Bose gas trapped in a generic power-law potential
The Casimir effect of an ideal Bose gas trapped in a generic power-law
potential and confined between two slabs with Dirichlet, Neumann, and periodic
boundary conditions is investigated systematically, based on the grand
potential of the ideal Bose gas, the Casimir potential and force are
calculated. The scaling function is obtained and discussed. The special cases
of free and harmonic potentials are also discussed. It is found that when T<Tc
(where Tc is the critical temperature of Bose-Einstein condensation), the
Casimir force is a power-law decay function; when T>Tc, the Casimir force is an
exponential decay function; and when T>>Tc, the Casimir force vanishes.Comment: 5 pages, 1 figur
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Mindfulness-Based Intervention For Nurses In AIDS Care In China: A Pilot Study.
Background/purpose:Workplace stress among nurses providing care for people living with human immunodeficiency virus is a serious problem in China that may increase rates of job burnout and affect quality of care. Mindfulness-based intervention has been shown to be effective in relieving stress and burnout in nurses. Therefore, we designed a mixed-method pilot study to evaluate a mindfulness-based intervention for nurses providing care for people living with human immunodeficiency virus. Methods:Twenty nurses caring for people living with human immunodeficiency virus in the First Hospital of Changsha, China participated in a mindfulness-based intervention for 2 hr sessions weekly for 6 weeks. The Perceived Stress Scale, Maslach Burnout Inventory, Five Facets Mindfulness Questionnaire, State-Trait Anxiety Inventory, and the Beck Depression Inventory were used to collect data before and after the mindfulness-based intervention. Participants were invited to attend an in-depth interview 1 week after the end of the mindfulness-based intervention to give feedback. Results:The quantitative analyses revealed a significant change in Five Facets Mindfulness Questionnaire scores. There were no significant differences between pre- and post-intervention measures of any other variables. Qualitative results showed nurses experienced a decrease in work and daily life pressures; improvements in communications with patients, colleagues and families, with better regulation of negative emotions, and acceptance of other people and attention. Conclusion:This study supports the acceptability and potential benefits of the mindfulness-based intervention in helping nurses caring for people living with human immunodeficiency virus to manage stress and emotions, and improve their acceptance of others and attention. A larger study with a randomized controlled trial design is warranted to confirm the effectiveness of this mindfulness-based intervention
Influence of surface coating on structure and properties of metallic lithium anode for rechargeable Li-O2 battery
Abstract Amorphous lithium phosphorous oxynitride film was coated directly on pre-treated lithium metal as anode of lithium air battery by radio-frequency sputtering technique from a Li 3 PO 4 target. The structure and composition of modified anode was analyzed before and after charge/discharge test in a lithium-air battery, which comprises 0.5 M LiNO 3 /TEGDME as the electrolyte and super P carbon as cathode. Batteries were galvanostatically discharged by an Arbin BT-2000 battery tester between open current voltage and 2.15 V vs. Li + /Li at various current regimes ranging from 0.1–0.4 mA/cm 2 . Compared with fresh lithium, LIPON-coated anode exhibited better electrochemical performance. Good charging efficiency of 90% at a narrower voltage gap with high ionic conductivity of 9.4 × 10 −5 S/cm was achieved through optimizing lithium pre-treated conditions, sputtering N 2 flows and suitable solute for electrolyte
No-Reference Quality Assessment for 360-degree Images by Analysis of Multi-frequency Information and Local-global Naturalness
360-degree/omnidirectional images (OIs) have achieved remarkable attentions
due to the increasing applications of virtual reality (VR). Compared to
conventional 2D images, OIs can provide more immersive experience to consumers,
benefitting from the higher resolution and plentiful field of views (FoVs).
Moreover, observing OIs is usually in the head mounted display (HMD) without
references. Therefore, an efficient blind quality assessment method, which is
specifically designed for 360-degree images, is urgently desired. In this
paper, motivated by the characteristics of the human visual system (HVS) and
the viewing process of VR visual contents, we propose a novel and effective
no-reference omnidirectional image quality assessment (NR OIQA) algorithm by
Multi-Frequency Information and Local-Global Naturalness (MFILGN).
Specifically, inspired by the frequency-dependent property of visual cortex, we
first decompose the projected equirectangular projection (ERP) maps into
wavelet subbands. Then, the entropy intensities of low and high frequency
subbands are exploited to measure the multi-frequency information of OIs.
Besides, except for considering the global naturalness of ERP maps, owing to
the browsed FoVs, we extract the natural scene statistics features from each
viewport image as the measure of local naturalness. With the proposed
multi-frequency information measurement and local-global naturalness
measurement, we utilize support vector regression as the final image quality
regressor to train the quality evaluation model from visual quality-related
features to human ratings. To our knowledge, the proposed model is the first
no-reference quality assessment method for 360-degreee images that combines
multi-frequency information and image naturalness. Experimental results on two
publicly available OIQA databases demonstrate that our proposed MFILGN
outperforms state-of-the-art approaches
A high performance surface acoustic wave visible light sensor using novel materials: Bi2S3 nanobelts
Low dimensional Bi2S3 materials are excellent for use in photodetectors with excellent stability and fast response time. In this work, we developed a visible light sensor with good performance based on surface acoustic wave (SAW) devices using Bi2S3 nanobelts as the sensing materials. The SAW delay-line sensor was fabricated on ST-cut quartz with a designed wavelength of 15.8 microns using conventional photolithography techniques. The measured center frequency was 200.02 MHz. The Bi2S3 nanobelts prepared by a facile hydrothermal process were deposited onto SAW sensors by spin-coating. Under irradiation of 625 nm visible light with a power intensity of 170 μW cm−2, the sensor showed a fast and large response with a frequency upshift of 7 kHz within 1 s. The upshift of the frequency of the SAW device is mainly attributed to the mass loading effect caused by the desorption of oxygen from the Bi2S3 nanobelts under visible light radiation
A high performance surface acoustic wave visible light sensor using novel materials: Bi2S3 nanobelts
Low dimensional Bi2S3 materials are excellent for use in photodetectors with excellent stability and fast response time. In this work, we developed a visible light sensor with good performance based on surface acoustic wave (SAW) devices using Bi2S3 nanobelts as the sensing materials. The SAW delay-line sensor was fabricated on ST-cut quartz with a designed wavelength of 15.8 microns using conventional photolithography techniques. The measured center frequency was 200.02 MHz. The Bi2S3 nanobelts prepared by a facile hydrothermal process were deposited onto SAW sensors by spin-coating. Under irradiation of 625 nm visible light with a power intensity of 170 μW cm−2, the sensor showed a fast and large response with a frequency upshift of 7 kHz within 1 s. The upshift of the frequency of the SAW device is mainly attributed to the mass loading effect caused by the desorption of oxygen from the Bi2S3 nanobelts under visible light radiation
Blind Quality Assessment for Image Superresolution Using Deep Two-Stream Convolutional Networks
Numerous image superresolution (SR) algorithms have been proposed for
reconstructing high-resolution (HR) images from input images with lower spatial
resolutions. However, effectively evaluating the perceptual quality of SR
images remains a challenging research problem. In this paper, we propose a
no-reference/blind deep neural network-based SR image quality assessor
(DeepSRQ). To learn more discriminative feature representations of various
distorted SR images, the proposed DeepSRQ is a two-stream convolutional network
including two subcomponents for distorted structure and texture SR images.
Different from traditional image distortions, the artifacts of SR images cause
both image structure and texture quality degradation. Therefore, we choose the
two-stream scheme that captures different properties of SR inputs instead of
directly learning features from one image stream. Considering the human visual
system (HVS) characteristics, the structure stream focuses on extracting
features in structural degradations, while the texture stream focuses on the
change in textural distributions. In addition, to augment the training data and
ensure the category balance, we propose a stride-based adaptive cropping
approach for further improvement. Experimental results on three publicly
available SR image quality databases demonstrate the effectiveness and
generalization ability of our proposed DeepSRQ method compared with
state-of-the-art image quality assessment algorithms
A Prospective Study of the Incidence of Retinopathy of Prematurity in China: Evaluation of Different Screening Criteria
To investigate the incidence of Retinopathy of Prematurity (ROP) in Beijing, North China, and to evaluate the effectiveness of different ROP screening criteria, we conducted a prospective cohort study in a single-neonatal intensive care unit (NICU). A total of 2997 premature infants with birth weight (BW) ≤ 2000 g and/or gestational age (GA) ≤ 34 weeks had completed ROP screening. ROP was diagnosed in 356 (11.9%) infants. The mean GA was 30.46 ± 1.98 weeks and the mean BW was 1477.35 ± 371.29 g. Of the 59 (2.0%) infants receiving treatment, the mean GA was 29.37 ± 2.10 weeks, and the mean BW was 1240.80 ± 330.71 g. The incidence of ROP declined from 14.7% in 2009 and 11.1% in 2010 to 9.5% in 2011. The United Kingdom (UK) criteria could reduce the screening number by 40.8%, and 3 infants with type I ROP needing treatment were missed, but none in 2011. The United States (US) criteria could reduce the screening number by 66.5%, and 10 infants with type I ROP needing treatment were missed, including one in 2011. So the UK criteria may be appropriate for screening of ROP in our NICU in 2011. Future multisite epidemiologic studies are required to establish suitable ROP screening criteria in China
Analysis of Faraday effect in multimode tellurite glass optical fiber for magneto-optical sensing and monitoring applications
The design and fabrication of a tellurite glass multimode optical fiber for magneto-optical applications
are presented and discussed. The analysis of the polarization shows that an optical beam, linearly polarized
at the fiber input, changes to elliptically polarized with an ellipticity of 1∶4.5 after propagating
down the fiber. However, the elliptical distribution remains unchanged with or without an applied magnetic
field, demonstrating that no circular dichroism occurs within the fiber. The Verdet constant of the
tellurite glass in the fiber is measured to be 28 0.5 rad · T ·m−1, diverging by less than 3% from the
Verdet constant found on the same glass composition in bulk form. These results demonstrate the feasibility
to develop reliable tellurite glass fibers by the preform drawing method for magneto-optical
applications
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