POPE: Partial Order Preserving Encoding

Recently there has been much interest in performing search queries over encrypted data to enable functionality while protecting sensitive data. One particularly efficient mechanism for executing such queries is order-preserving encryption/encoding (OPE) which results in ciphertexts that preserve the relative order of the underlying plaintexts thus allowing range and comparison queries to be performed directly on ciphertexts. In this paper, we propose an alternative approach to range queries over encrypted data that is optimized to support insert-heavy workloads as are common in "big data" applications while still maintaining search functionality and achieving stronger security. Specifically, we propose a new primitive called partial order preserving encoding (POPE) that achieves ideal OPE security with frequency hiding and also leaves a sizable fraction of the data pairwise incomparable. Using only O(1) persistent and $O(n^\epsilon)$ non-persistent client storage for $0<\epsilon<1$, our POPE scheme provides extremely fast batch insertion consisting of a single round, and efficient search with O(1) amortized cost for up to $O(n^{1-\epsilon})$ search queries. This improved security and performance makes our scheme better suited for today's insert-heavy databases.Comment: Appears in ACM CCS 2016 Proceeding

TriviaQA: A Large Scale Distantly Supervised Challenge Dataset for Reading Comprehension

We present TriviaQA, a challenging reading comprehension dataset containing over 650K question-answer-evidence triples. TriviaQA includes 95K question-answer pairs authored by trivia enthusiasts and independently gathered evidence documents, six per question on average, that provide high quality distant supervision for answering the questions. We show that, in comparison to other recently introduced large-scale datasets, TriviaQA (1) has relatively complex, compositional questions, (2) has considerable syntactic and lexical variability between questions and corresponding answer-evidence sentences, and (3) requires more cross sentence reasoning to find answers. We also present two baseline algorithms: a feature-based classifier and a state-of-the-art neural network, that performs well on SQuAD reading comprehension. Neither approach comes close to human performance (23% and 40% vs. 80%), suggesting that TriviaQA is a challenging testbed that is worth significant future study. Data and code available at -- http://nlp.cs.washington.edu/triviaqa/Comment: Added references, fixed typos, minor baseline updat

The effects of oral vs nasal intubation on endotracheal tube complications in cardiac patients

Thesis (M.A.)--Boston UniversityObjective: To test the hypothesis that nasal endotracheal tubes are more secure and associated with fewer complications than oral endotracheal tubes. This involves establishing the incidence of specific endotracheal tube complications between cardiac patients who are intubated via the oral and nasal route. In addition, a secondary objective is to identify specific risk groups that could benefit from a change in practice or implementation of guidelines. Design: A retrospective chart review of 100 patients who were admitted to the Pediatric Cardiac Intensive Care Unit with an endotracheal tube in place was performed. Patients involved in this preliminary study were selected from a larger patient population admitted to Boston Children’s Hospital during the fiscal year of 2011 (October 1, 2010 through September 30, 2011). Variables that were collected include: gender, type of mechanical ventilation, reasons for admission, RACHS-1 scores, outcome of respiratory support, age and weight of patients, duration of ventilation, reason for ventilation, cuffed vs. un-cuffed ETT, size of ETT, initial tube depth, route of intubation, location of intubation, duration of ventilation, CICU and hospital length of stay, and inotropic scores. The specific complications that were analyzed were: inadequate ETT positioning or securing with the need for re-adjustment, accidental or unplanned extubations, device related pressure ulcers and skin breakdown, and feeding problems related to dysphagia. The Z-test was used to determine if the difference in rate of complications between cardiac patients who were orally intubated and cardiac patients who were nasally intubated was statistically significant. The Fisher’s Exact test was also used to confirm the z-test since the sample size was relatively small. Finally, a multi-variable regression with select variables was performed to observe possible confounding factors. The Fisher’s Exact test and Mann-Whitney U-test were used to determine which covariates would be included in the multivariable regression. [TRUNCATED

ObliviSync: Practical Oblivious File Backup and Synchronization

Oblivious RAM (ORAM) protocols are powerful techniques that hide a client's data as well as access patterns from untrusted service providers. We present an oblivious cloud storage system, ObliviSync, that specifically targets one of the most widely-used personal cloud storage paradigms: synchronization and backup services, popular examples of which are Dropbox, iCloud Drive, and Google Drive. This setting provides a unique opportunity because the above privacy properties can be achieved with a simpler form of ORAM called write-only ORAM, which allows for dramatically increased efficiency compared to related work. Our solution is asymptotically optimal and practically efficient, with a small constant overhead of approximately 4x compared with non-private file storage, depending only on the total data size and parameters chosen according to the usage rate, and not on the number or size of individual files. Our construction also offers protection against timing-channel attacks, which has not been previously considered in ORAM protocols. We built and evaluated a full implementation of ObliviSync that supports multiple simultaneous read-only clients and a single concurrent read/write client whose edits automatically and seamlessly propagate to the readers. We show that our system functions under high work loads, with realistic file size distributions, and with small additional latency (as compared to a baseline encrypted file system) when paired with Dropbox as the synchronization service.Comment: 15 pages. Accepted to NDSS 201

Momentum Driving: which physical processes dominate AGN feedback?

The deposition of mechanical feedback from a supermassive black hole (SMBH) in an active galactic nucleus (AGN) into the surrounding galaxy occurs via broad-line winds which must carry mass and radial momentum as well as energy. The effect can be summarized by the dimensionless parameter $\eta=dot{M_outflow}/dot{M_accretion}= (2 \epsilon_w c^2)/v_w^2$ where (\epslion_w \equiv dot{E}_w/(dot{M_accretion} c^2)) is the efficiency by which accreted matter is turned into wind energy in the disc surrounding the central SMBH. The outflowing mass and omentum are proportional to $\eta$, and many prior treatments have essentially assumed that $\eta=0$. We perform one- and two-dimensional simulations and find that the growth of the central SMBH is very sensitive to the inclusion of the mass and momentum driving but is insensitive to the assumed mechanical efficiency. For example in representative calculations, the omission of momentum and mass feedback leads to an hundred fold increase in the mass of the SMBH to over 10^{10} \Msun. When allowance is made for momentum driving, the final SMBH mass is much lower and the wind efficiencies which lead to the most observationally acceptable results are relatively low with $\epsilon_w \lesssim 10^{-4}$.Comment: 10 pages, 8 figures, resubmitted to ApJ, added reference

Classrooms as Workplace: “Early Pre-service” STEM Teaching Experience in a University-Based Summer STEM Institute

The focus of study is to examine the impact that The Orange County Teacher Pathway Partnership (OC-TPP) at CSU Fullerton has had on participants’ (community college transfer students) skills and experiences gained in each of the program years from years 2015-2018. Students who participated in the STEM Institute gained pre-professional skills and teaching experience through various activities in the program. Students remained on the teacher pathway because the program allowed them to break out of their comfort zones, build social connections, and adjust to various groups of people. Attending the program increased college student confidence in content knowledge and content-based pedagogy, through their university-based experience. In addition, participants gained technical skills in science and teaching through professional exposure

Transconductance and Coulomb blockade properties of in-plane grown carbon nanotube field effect transistors

Single electron transistors (SETs) made from single wall carbon nanotubes (SWCNTs) are promising for quantum electronic devices operating with ultra-low power consumption and allow fundamental studies of electron transport. We report on SETs made by registered in-plane growth utilizing tailored nanoscale catalyst patterns and chemical vapor deposition. Metallic SWCNTs have been removed by an electrical burn-in technique and the common gate hysteresis was removed using PMMA and baking, leading to field effect transistors with large on/off ratios up to 10^5. Further segmentation into 200 nm short semiconducting SWCNT devices created quantum dots which display conductance oscillations in the Coulomb blockade regime. The demonstrated utilization of registered in-plane growth opens possibilities to create novel SET device geometries which are more complex, i.e. laterally ordered and scalable, as required for advanced quantum electronic devices.Comment: 15 pages, 4 figure

Volatility spillover between New Zealand stock market returns and exchange rate changes before and after the 1997 Asian financial crisis

Researchers in the last decade have been investigating the interdependence of stock returns and exchange rate changes within the same economy. Kanas (2000) and Yang and Doong (2004) find that for the G-7 countries, in general, the volatility of the stock market spills over to the exchange rate market but that volatility spillovers from the exchange rate market to the stock market are insignificant. Chen, Naylor, and Lu (2004) find that NZ individual firm returns are significantly exposed to exchange rate changes. This study complements their work by investigating the volatility spillover between the stock market and the foreign exchange market within the NZ economy.<br /