3,823 research outputs found

    Holographic heat engine with momentum relaxation

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    We investigate the heat engine defined via black hole with momentum relaxation, which is introduced by massless axion fields. We first study the extended thermodynamical properties of the black hole and then apply it to define a heat engine. Then, we analyze how the momentum relaxation affects the efficiency of the heat engine in the limit of high temperature. We find that depending on the schemes of specified parameters in the engine circle, the influence of momentum relaxation on the efficiency of the heat engine behaves novelly, and the qualitative behaviors do depend on the dimension of the gravity theory.Comment: 11 pages, 6 figure

    Fermionic phase transition induced by the effective impurity in holography

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    We investigate the holographic fermionic phase transition induced by the effective impurity in holography, which is introduced by massless scalar fields in Einstein-Maxwell-massless scalar gravity. We obtain a phase diagram in (α,T)(\alpha, T) plane separating the Fermi liquid phase and the non-Fermi liquid phase.Comment: 17 pages, 9 figure

    Balance between Privacy Protecting and Selling User Data of Wearable Devices

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    Smart bracelets are capable of identifying individual data, which can synchronize the step count, mileage, calorie consumption, heart rate, sleeping data and even the pictures users uploaded with the APP. This feature is so convenient on one hand but makes us lose control of our privacy on the other hand. With poor privacy protection mechanism embedded in these wearable devices that hackers can easily invade and steal user data. In addition, most smart bracelet companies have not made a clear declaration of which third parties are able to get users’ data, nor how long will the user's physical and health-related information be stored. These companies understand well that large amount of the user's movement and physiological monitoring data are valuable, because each user's information can be a unique sample. As soon as the smart bracelet companies collect extensive and diverse samples, they can figure out a variety of specific and practical applications through excavate data. Therefore, the research questions of this study are 1. how do smart bracelet companies strike a balance between protecting consumer privacy and selling user data to get more business opportunities? 2. In order to achieve this balance, what kind of strategy should smart bracelet companies adopt? This study addresses what measures smart bracelet companies take as well as what attitude they hold through literature review and the comparison of Fitbit, Xiaomi and Garmin's privacy policies. Meanwhile we adopt PEST analysis model and Porter’s diamond model to engage external analysis of three main vendors in order to have a further understanding of the environment in which the industry is poised. At last, we apply the stakeholder analysis to determine what strategies the companies should take in correspondence after identifying the direct and indirect stakeholders of the smart bracelet companies. This research outcome indicates that beneficial tangible service is the main factor affecting consumers whether to share their data with wearable vendors, but vendors have to be aware of the impacts of privacy issues by selling user data. It is possible that consumers resist buying the wearable products if they find their privacy is disturbed. Furthermore, this study is valuable not only to wearable device vendors to strike balance between privacy and profits but also policy makers to figure out the necessity to get involve in personal data protection over wearable device market

    Degree one loading by pressure variations at the CMB

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    Hemispherical asymmetry in core dynamics induces degree-1 pressure variations at the core mantle boundary (CMB), which in turn deforms the overlaying elastic mantle, at the same time keeps center of mass of the whole Earth stationary in space. We develop a systematic procedure to deal with the degree-1 CMB pressure loading. We find by direct calculation a surprisingly negative load Love number h[subscript 1]=−1.425 for vertical displacement. Further analysis indicates that the negative h[subscript 1] corresponds to thickening above the positive load that defies intuition that pressure inflation pushes overlaying material up and thins the enveloping shell. We also redefine the pressure load Love numbers in general to enable comparison between the surface mass load and the CMB pressure load for the whole spectrum of harmonic degrees. We find that the gravitational perturbations from the two kinds of loads at degrees n>1 are very similar in amplitude but opposite in sign. In particular, if the CMB pressure variation at degree 2 is at the level of ∼1 hpa/yr (1 cm water height per year), it would perturb the variation of Earth’s oblateness, known as the J[subscript 2], at the observed level.United States. National Aeronautics and Space Administration (No. NNX09AK 70G

    Whole exome and targeted deep sequencing identify genome-wide allelic loss and frequent SETDB1 mutations in malignant pleural mesotheliomas.

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    Malignant pleural mesothelioma (MPM), a rare malignancy with a poor prognosis, is mainly caused by exposure to asbestos or other organic fibers, but the underlying genetic mechanism is not fully understood. Genetic alterations and causes for multiple primary cancer development including MPM are unknown. We used whole exome sequencing to identify somatic mutations in a patient with MPM and two additional primary cancers who had no evidence of venous, arterial, lymphovascular, or perineural invasion indicating dissemination of a primary lung cancer to the pleura. We found that the MPM had R282W, a key TP53 mutation, and genome-wide allelic loss or loss of heterozygosity, a distinct genomic alteration not previously described in MPM. We identified frequent inactivating SETDB1 mutations in this patient and in 68 additional MPM patients (mutation frequency: 10%, 7/69) by targeted deep sequencing. Our observations suggest the possibility of a new genetic mechanism in the development of either MPM or multiple primary cancers. The frequent SETDB1 inactivating mutations suggest there could be new diagnostic or therapeutic options for MPM

    In vivo sub-femtoliter resolution photoacoustic microscopy with higher frame rates

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    Microscopy based on non-fluorescent absorption dye staining is widely used in various fields of biomedicine for 400 years. Unlike its fluorescent counterpart, non-fluorescent absorption microscopy lacks proper methodologies to realize its in vivo applications with a sub-femtoliter 3D resolution. Regardless of the most advanced high-resolution photoacoustic microscopy, sub-femtoliter spatial resolution is still unattainable, and the imaging speed is relatively slow. In this paper, based on the two-photon photoacoustic mechanism, we demonstrated a in vivo label free laser-scanning photoacoustic imaging modality featuring high frame rates and sub-femtoliter 3D resolution simultaneously, which stands as a perfect solution to 3D high resolution non-fluorescent absorption microscopy. Furthermore, we first demonstrated in vivo label-free two-photon acoustic microscopy on the observation of non-fluorescent melanin distribution within mouse skin

    Dynamic modelling of heart rate response under different exercise intensity.

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    Heart rate is one of the major indications of human cardiovascular response to exercises. This study investigates human heart rate response dynamics to moderate exercise. A healthy male subject has been asked to walk on a motorised treadmill under a predefined exercise protocol. ECG, body movements, and oxygen saturation (SpO2) have been reliably monitored and recorded by using non-invasive portable sensors. To reduce heart rate variation caused by the influence of various internal or external factors, the designed step response protocol has been repeated three times. Experimental results show that both steady state gain and time constant of heart rate response are not invariant when walking speed is faster than 3 miles/hour, and time constant of offset exercise is noticeably longer than that of onset exercise

    Virtual k -Space Modulation Optical Microscopy

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    We report a novel superresolution microscopy approach for imaging fluorescence samples. The reported approach, termed virtual k-space modulation optical microscopy (VIKMOM), is able to improve the lateral resolution by a factor of 2, reduce the background level, improve the optical sectioning effect and correct for unknown optical aberrations. In the acquisition process of VIKMOM, we used a scanning confocal microscope setup with a 2D detector array to capture sample information at each scanned x-y position. In the recovery process of VIKMOM, we first modulated the captured data by virtual k-space coding and then employed a ptychography-inspired procedure to recover the sample information and correct for unknown optical aberrations. We demonstrated the performance of the reported approach by imaging fluorescent beads, fixed bovine pulmonary artery endothelial (BPAE) cells, and living human astrocytes (HA). As the VIKMOM approach is fully compatible with conventional confocal microscope setups, it may provide a turn-key solution for imaging biological samples with ∼100  nm lateral resolution, in two or three dimensions, with improved optical sectioning capabilities and aberration correcting.National Institutes of Health (U.S.) (9P41EB015871-26A1)National Institutes of Health (U.S.) (1R01HL121386-01A1
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