Fermionic phase transition induced by the effective impurity in holography

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 $(\alpha, T)$ 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

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

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

Effects of airflow on the acoustic attenuation performance of reactive muffler

In order to study the effect of airflow on the acoustic attenuation performance of reactive muffler, firstly, the formulas of wavenumber, transfer matrix method and three point method were deduced in the case of uniform flow. Then, the differences between transfer matrix method and three point method were compared based on the results of finite element method (FEM), for the no-flow, uniform flow and non-uniform flow three different cases. The results showed that both the transfer matrix method and three point method can accurately calculate the transmission loss (TL) of muffler under no-flow and uniform flow conditions. But, for the non-uniform flow case, both the results calculated by the two methods above have deviations on account of the complexity of flow field and the limitations of calculation methods. In addition, negative values even appear in the low frequency range. Finally, comparative study about the effect of uniform flow and non-uniform flow on the acoustic attenuation performance of muffler was made. Results showed that the difference of the effect of uniform flow and non-uniform flow on the acoustic attenuation performances is little when the airflow regenerated noise is ignored and the existence of airflow has little effect on the acoustic attenuation performance of reactive muffler. Therefore, the effect of airflow on the acoustic attenuation performance can be neglected during the initial phase of muffler design