Crisis Communication Patterns in Social Media during Hurricane Sandy

Hurricane Sandy was one of the deadliest and costliest of hurricanes over the past few decades. Many states experienced significant power outage, however many people used social media to communicate while having limited or no access to traditional information sources. In this study, we explored the evolution of various communication patterns using machine learning techniques and determined user concerns that emerged over the course of Hurricane Sandy. The original data included ~52M tweets coming from ~13M users between October 14, 2012 and November 12, 2012. We run topic model on ~763K tweets from top 4,029 most frequent users who tweeted about Sandy at least 100 times. We identified 250 well-defined communication patterns based on perplexity. Conversations of most frequent and relevant users indicate the evolution of numerous storm-phase (warning, response, and recovery) specific topics. People were also concerned about storm location and time, media coverage, and activities of political leaders and celebrities. We also present each relevant keyword that contributed to one particular pattern of user concerns. Such keywords would be particularly meaningful in targeted information spreading and effective crisis communication in similar major disasters. Each of these words can also be helpful for efficient hash-tagging to reach target audience as needed via social media. The pattern recognition approach of this study can be used in identifying real time user needs in future crises

Helical motion of magnetic flux tubes in the solar atmosphere

Photospheric granulation may excite transverse kink pulses in anchored vertical magnetic flux tubes. The pulses propagate upwards along the tubes with the kink speed, while oscillating wakes are formed behind the wave front in a stratified atmosphere. The wakes oscillate at the kink cut-off frequency of stratified medium and gradually decay in time. When two or more consecutive kink pulses with different polarizations propagate in the same thin tube, then the wakes corresponding to different pulses may superimpose. The superposition sets up helical motions of magnetic flux tubes in the photosphere/chromosphere as seen by recent Hinode movies. The energy carried by the pulses is enough to heat the solar chrmosphere/corona and accelerate the solar wind.Comment: Accepted in ApJ

Photoproduction of electron-positron pairs in bent single crystals

The process of photoproduction of electron-positron pairs in bent single crystals is considered in this paper. In particular, it is shown that the probability of the process for gamma-quanta with energies from 100 GeV on is significantly higher than the one in an amorphous medium. A possible scenario for the experimental validation of the process is discussed and the positive features of the photoproduction in bent crystals compared to straight ones are underlined from the point of view of possible applications.Comment: 13 pages, 6 figure

Strong Upper Limits on Sterile Neutrino Warm Dark Matter

Sterile neutrinos are attractive dark matter candidates. Their parameter space of mass and mixing angle has not yet been fully tested despite intensive efforts that exploit their gravitational clustering properties and radiative decays. We use the limits on gamma-ray line emission from the Galactic Center region obtained with the SPI spectrometer on the INTEGRAL satellite to set new constraints, which improve on the earlier bounds on mixing by more than two orders of magnitude, and thus strongly restrict a wide and interesting range of models.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in Physical Review Letter

Chemically gated electronic structure of a superconducting doped topological insulator system

Angle resolved photoemission spectroscopy is used to observe changes in the electronic structure of bulk-doped topological insulator Cu$_x$Bi$_2$Se$_3$ as additional copper atoms are deposited onto the cleaved crystal surface. Carrier density and surface-normal electrical field strength near the crystal surface are estimated to consider the effect of chemical surface gating on atypical superconducting properties associated with topological insulator order, such as the dynamics of theoretically predicted Majorana Fermion vortices

The Effects of Focus and Diversification on Bank Risk and Return: Evidence from Individual Bank Loan Portfolios

We study empirically the effect of focus (specialization) vs. diversification on the return and the risk of banks using data from 105 Italian banks over the period 1993–1999. Specifically, we analyze the tradeoffs between (loan portfolio) focus and diversification using a unique data set that is able to identify individual bank loan exposures to different industries, to different sectors, and to different geographical regions. Our results are consistent with a theory that predicts a deterioration in bank monitoring quality at high levels of risk and a deterioration in bank monitoring quality upon lending expansion into newer or competitive industries. We find that industrial loan diversification reduces bank return while endogenously producing riskier loans for all banks in our sample, this effect being most powerful for high-risk banks. Sectoral loan diversification only produces an inefficient risk–return trade-off for banks with very high levels of risk. Geographical diversification on the other hand does result in an improvement in the risk–return tradeoff for banks with low levels of risk. Overall, our results suggest that diversification of bank assets is not guaranteed to produce more performance efficient and/or safer banks

Development of farm pond operational modeling using Neuro-Fuzzy technique

Study was conducted to derive operational model for a farm pond of 3000 cubic meter capacity at Center for protected cultivation technology (CPCT), Indian Agricultural Research Institute, New Delhi, India which was the important source of irrigation water of the farm of the area 10 ha. The Neuro-Fuzzy approach was used to develop the operational model and to derive operational rules for proper irrigation scheduling of the horticultural crops grown at CPCT. Based upon the inputs like crop water requirement, evaporation losses and farm pond inflow the model predicting outflow of the reservoir was developed. The developed model was having high accuracy and predictability when tested statistically. The coefficient of determination (R2) was found to be 0.96, whereas the model efficiency (E) was 0.97 which shows the high reliability of the model. The operating rules which were of ‘If-Then’ form were also developed which would lead to better management of the farm pond system and would also improve the irrigation scheduling at CPCT farm, IARI, New Delhi

The Effects of Focus and Diversification on Bank Risk and Return: Evidence from Individual Bank Loan Portfolios

We study empirically the effect of focus (specialization) vs. diversification on the return and the risk of banks using data from 105 Italian banks over the period 1993–1999. Specifically, we analyze the tradeoffs between (loan portfolio) focus and diversification using a unique data set that is able to identify individual bank loan exposures to different industries, to different sectors, and to different geographical regions. Our results are consistent with a theory that predicts a deterioration in bank monitoring quality at high levels of risk and a deterioration in bank monitoring quality upon lending expansion into newer or competitive industries. We find that industrial loan diversification reduces bank return while endogenously producing riskier loans for all banks in our sample, this effect being most powerful for high risk banks. Sectoral loan diversification only produces an inefficient risk–return tradeoff for banks with very high levels of risk. Geographical diversification on the other hand does result in an improvement in the risk–return tradeoff for banks with low levels of risk. Overall, our results suggest that diversification of bank assets is not guaranteed to produce more performance efficient and/or safer banks