4,518 research outputs found
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 non-persistent client storage for
, our POPE scheme provides extremely fast batch insertion
consisting of a single round, and efficient search with O(1) amortized cost for
up to 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 Childrenās 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 Fisherās 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 Fisherās 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
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 , and
many prior treatments have essentially assumed that . 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 .Comment: 10 pages, 8 figures, resubmitted to ApJ, added reference
Classrooms as Workplace: āEarly Pre-serviceā 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 participantsā (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 /
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