Earthquake Early Warning and Beyond: Systems Challenges in Smartphone-based Seismic Network

Earthquake Early Warning (EEW) systems can effectively reduce fatalities, injuries, and damages caused by earthquakes. Current EEW systems are mostly based on traditional seismic and geodetic networks, and exist only in a few countries due to the high cost of installing and maintaining such systems. The MyShake system takes a different approach and turns people's smartphones into portable seismic sensors to detect earthquake-like motions. However, to issue EEW messages with high accuracy and low latency in the real world, we need to address a number of challenges related to mobile computing. In this paper, we first summarize our experience building and deploying the MyShake system, then focus on two key challenges for smartphone-based EEW (sensing heterogeneity and user/system dynamics) and some preliminary exploration. We also discuss other challenges and new research directions associated with smartphone-based seismic network.Comment: 6 pages, conference paper, already accepted at hotmobile 201

Restricted Access and Delays to HCV Treatment Among Medicaid Patients in Louisiana

Background: Many people living with chronic Hepatitis C Virus (HCV) have seen delays in accessing treatment or been denied entirely due to Medicaid restrictions requiring patients to meet certain criteria prior to receiving approval for medication pre-authorization. Methods: This study identified a cohort of Medicaid-insured patients with chronic HCV infection within New Orleans, LA. Patient medical records were reviewed and information regarding HCV care was gathered. This study sought to determine the degree to which HCV care was delayed for this population and describe common reasons for prior-authorization denials for direct-acting antiviral (DAA) medications. Results: For this population of Medicaid-insured patients with HCV RNA assay-confirmed chronic infection, the average number of days it took to reach a specialist was three-times greater than the number of days it took to reach a primary care physician. After attending an appointment with a specialist to seek HCV care, patients experienced wait periods of an average of 150 days before being deemed eligible for treatment per Medicaid requirements. After being deemed eligible for treatment, patients experienced an average wait period of 194.4 days to initiation of treatment, with low fibrosis status being cited as the most common reason for treatment delay. Conclusion: This population of Medicaid-insured patients in New Orleans, LA with chronic HCV infection experienced delays in treatment related to reduced accessibility of a specialist who was eligible to request DAA prior-authorization. Prior-authorization was most frequently denied based on low fibrosis status or recent alcohol/drug use

Density of Yang-Lee zeros for the Ising ferromagnet

The densities of Yang-Lee zeros for the Ising ferromagnet on the $L\times L$ square lattice are evaluated from the exact grand partition functions ($L=3\sim16$). The properties of the density of Yang-Lee zeros are discussed as a function of temperature $T$ and system size $L$. The three different classes of phase transitions for the Ising ferromagnet, first-order phase transition, second-order phase transition, and Yang-Lee edge singularity, are clearly distinguished by estimating the magnetic scaling exponent $y_h$ from the densities of zeros for finite-size systems. The divergence of the density of zeros at Yang-Lee edge in high temperatures (Yang-Lee edge singularity), which has been detected only by the series expansion until now for the square-lattice Ising ferromagnet, is obtained from the finite-size data. The identification of the orders of phase transitions in small systems is also discussed using the density of Yang-Lee zeros.Comment: to appear in Physical Review