213 research outputs found
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Cryptography and the Internet: lessons and challenges
The popularization of the Internet has brought fundamental changes to the world, because it allows a universal method of communication between computers. This carries enormous benefits with it, but also raises many security considerations. Cryptography is a fundamental technology used to provide security of computer networks, and there is currently a widespread engineering effort to incorporate cryptography into various aspects of the Internet. The system-level engineering required to provide security services for the Internet carries some important lessons for researchers whose study is focused on narrowly defined problems. It also offers challenges to the cryptographic research community by raising new questions not adequately addressed by the existing body of knowledge. This paper attempts to summarize some of these lessons and challenges for the cryptographic research community
Baby-Step Giant-Step Algorithms for the Symmetric Group
We study discrete logarithms in the setting of group actions. Suppose that
is a group that acts on a set . When , a solution
to can be thought of as a kind of logarithm. In this paper, we study
the case where , and develop analogs to the Shanks baby-step /
giant-step procedure for ordinary discrete logarithms. Specifically, we compute
two sets such that every permutation of can be
written as a product of elements and . Our
deterministic procedure is optimal up to constant factors, in the sense that
and can be computed in optimal asymptotic complexity, and and
are a small constant from in size. We also analyze randomized
"collision" algorithms for the same problem
Lattice sieving and trial division
Reports on work in progress on our new implementation of the relation collection stage of the general number field sieve integer factoring algorithm. Our experiments indicate that we have achieved a substantial speed-up compared to other implementations that are reported in the literature. The main improvements are a new lattice sieving technique and a trial division method that is based on lattice sieving in a hash table. This also allows us to collect triple and quadruple large prime relations in an efficient manner. Furthermore, we show how the computation can efficiently be shared among multiple processors in a high-bandwidth environmen
A Framework for Adversarially Robust Streaming Algorithms
We investigate the adversarial robustness of streaming algorithms. In this
context, an algorithm is considered robust if its performance guarantees hold
even if the stream is chosen adaptively by an adversary that observes the
outputs of the algorithm along the stream and can react in an online manner.
While deterministic streaming algorithms are inherently robust, many central
problems in the streaming literature do not admit sublinear-space deterministic
algorithms; on the other hand, classical space-efficient randomized algorithms
for these problems are generally not adversarially robust. This raises the
natural question of whether there exist efficient adversarially robust
(randomized) streaming algorithms for these problems.
In this work, we show that the answer is positive for various important
streaming problems in the insertion-only model, including distinct elements and
more generally -estimation, -heavy hitters, entropy estimation, and
others. For all of these problems, we develop adversarially robust
-approximation algorithms whose required space matches that of
the best known non-robust algorithms up to a multiplicative factor (and in some cases even up to a constant
factor). Towards this end, we develop several generic tools allowing one to
efficiently transform a non-robust streaming algorithm into a robust one in
various scenarios.Comment: Conference version in PODS 2020. Version 3 addressing journal
referees' comments; improved exposition of sketch switchin
Information integrity and privacy for computerized medical patient records
Sandia National Laboratories and Oceania, Inc. entered into a Cooperative Research and Development Agreement (CRADA) in November 1993 to provide ``Information Integrity and Privacy for Computerized Medical Patient Records`` (CRADA No. SC93/01183). The main objective of the project was to develop information protection methods that are appropriate for databases of patient records in health information systems. This document describes the findings and alternative solutions that resulted from this CRADA
Recommended from our members
Information integrity and privacy for computerized medical patient records
Sandia National Laboratories and Oceania, Inc. entered into a Cooperative Research and Development Agreement (CRADA) in November 1993 to provide ``Information Integrity and Privacy for Computerized Medical Patient Records`` (CRADA No. SC93/01183). The main objective of the project was to develop information protection methods that are appropriate for databases of patient records in health information systems. This document describes the findings and alternative solutions that resulted from this CRADA
Impact of an integrated disease management program in reducing exacerbations in patients with severe asthma and COPD
SummaryBackgroundConflicting data exists on the effectiveness of integrated programs in reducing recurrent exacerbations and hospitalizations in patients with Asthma and chronic obstructive lung disease (COPD). We developed a Pulmonologist-led Chronic Lung Disease Program (CLDP) for patients with severe asthma and COPD and analyzed its impact on healthcare utilization and predictors of its effectiveness.MethodsCLDP elements included clinical evaluation, onsite pulmonary function testing, health education, and self-management action plan along with close scheduled and on-demand follow-up. Patients with ≥2 asthma or COPD exacerbations requiring emergency room visit or hospitalization within the prior year were enrolled, and followed for respiratory related ER visits (RER) and hospitalizations (RHA) over the year (357 ± 43 days) after CLDP interventions.ResultsA total of 106 patients were enrolled, and 104 patients were subject to analyses. During the year of follow-up after CLDP enrollment, there was a significant decrease in mean RER (0.56 ± 1.48 versus 2.62 ± 2.81, p < 0.0001), mean RHA (0.39 ± 0.08 versus 1.1 ± 1.62, p < 0.0001), and 30 day rehospitalizations (0.05 ± 0.02 versus 0.28 ± 0.07, p < 0.0001). Reduction of healthcare utilization was strongly associated with GERD and sinusitis therapy, and was independent of pulmonary rehabilitation. Direct variable cost analyses estimated annual savings at $1.17 million. Multivariate logistic regression analysis revealed lack of spirometry utilization as an independent risk factor for severe exacerbations.ConclusionsA Pulmonologist-led disease management program integrating key elements of care is cost effective and significantly decreases severe exacerbations. Integrated programs should be encouraged for care of frequent exacerbators of asthma and COPD
Tools to Detect Delirium Superimposed on Dementia:A Systematic Review
BACKGROUND: Delirium commonly occurs in patients with dementia. Though several tools for detecting delirium exist, it is unclear which are valid in patients with delirium superimposed on dementia. OBJECTIVES: Identify valid tools to diagnose delirium superimposed on dementia DESIGN: We performed a systematic review of studies of delirium tools, which explicitly included patients with dementia. SETTING: In-hospital patients PARTICIPANTS: Studies were included if delirium assessment tools were validated against standard criteria, and the presence of dementia was assessed according to standard criteria that used validated instruments. MEASUREMENTS: PubMed, Embase, and Web of Science databases were searched for articles in English published between January 1960 and January 2012. RESULTS: Nine studies fulfilled the selection criteria. Of the total of 1569 patients, 401 had dementia, and 50 had delirium superimposed on dementia. Six delirium tools were evaluated. One studyusing the Confusion Assessment Method (CAM) with 85% patients with dementia showed a high specificity (96–100%) and moderate sensitivity (77%).Two intensive care unit studies that used the CAM for the Intensive Care Unit (CAM-ICU) ICU reported 100% sensitivity and specificity for delirium among 23 dementia patients. One study using electroencephalography reported a sensitivity of 67% and a specificity of 91% among a population with 100% prevalence of dementia. No studies examined potential effects of dementia severity or subtype upon diagnostic accuracy. CONCLUSIONS: The evidence base on tools for detection of delirium superimposed on dementia is limited, although some existing tools show promise. Further studies of existing or refined tools with larger samples and more detailed characterization of dementia are now required to address the identification of delirium superimposed on dementia
Alterations in vascular function in primary aldosteronism - a cardiovascular magnetic resonance imaging study
Introduction: Excess aldosterone is associated with increased cardiovascular risk. Aldosterone has a permissive effect on vascular fibrosis. Cardiovascular magnetic resonance imaging (CMR) allows study of vascular function by measuring aortic distensibility. We compared aortic distensibility in primary aldosteronism (PA), essential hypertension (EH) and normal controls and explored the relationship between aortic distensibility and pulse wave velocity (PWV).<p></p>
Methods: We studied PA (n=14) and EH (n=33) subjects and age-matched healthy controls (n=17) with CMR, including measurement of aortic distensibility, and measured PWV using applanation tonometry. At recruitment, PA and EH patients had similar blood pressure and left ventricular mass.<p></p>
Results: Subjects with PA had significantly lower aortic distensibilty and higher PWV compared to EH and healthy controls. These changes were independent of other factors associated with reduced aortic distensibility, including aging. There was a significant relationship between increasing aortic stiffness and age in keeping with physical and vascular aging. As expected, aortic distensibility and PWV were closely correlated.<p></p>
Conclusion: These results demonstrate that PA patients display increased arterial stiffness compared to EH, independent of vascular aging. The implication is that aldosterone invokes functional impairment of arterial function. The long-term implications of arterial stiffening in aldosterone excess require further study.<p></p>
Nuclear receptors in vascular biology
Nuclear receptors sense a wide range of steroids and hormones (estrogens, progesterone, androgens, glucocorticoid, and mineralocorticoid), vitamins (A and D), lipid metabolites, carbohydrates, and xenobiotics. In response to these diverse but critically important mediators, nuclear receptors regulate the homeostatic control of lipids, carbohydrate, cholesterol, and xenobiotic drug metabolism, inflammation, cell differentiation and development, including vascular development. The nuclear receptor family is one of the most important groups of signaling molecules in the body and as such represent some of the most important established and emerging clinical and therapeutic targets. This review will highlight some of the recent trends in nuclear receptor biology related to vascular biology
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