How to Generate Repeatable Keys Using Physical Unclonable Functions Correcting PUF Errors with Iteratively Broadening and Prioritized Search

We present an algorithm for repeatably generating keys using entropy from a Physical Unclonable Function (PUF). PUFs are logically identical physical constructs with Challenge-Response Pairs (CRPs) unique to each device. Applications include initialization of server keys and encryption of FPGA configuration bitstreams. One problem with PUFs is response errors. Our algorithm corrects PUF errors that inhibit key repeatability. Our approach uses a PUF to generate an error-free PUF value in three steps. First, we repeatedly sample the PUF to determine the most likely value. Second, we apply an iteratively-broadening search to search up to some number of bit errors (in our experiments we use two). Third, we apply exhaustive search until the correct value is found or failure is declared. The searches are prioritized by the known bit error rates in decreasing magnitude. We assume the application includes a test for the correct value (e.g., some matching plaintext-ciphertext pairs). Previous algorithms often omit noisy PUF bits or use error-correcting codes and helper data. Our algorithm can use all PUF bits regardless of noise. Our approach is simple, and for appropriate parameter choices, fast. Unlike previous approaches using error-correcting codes, when used for public-key cryptography our method requires storing only the public key and no other helperdata in non-volatile storage. We implemented a latch-based PUF on FPGAs and measured PUF characteristics to analyze the effectiveness of the algorithm. Tests for a 1024-bit PUF show 351 samples reduce the probability of errors to less than 10^-6. The iterative broadening and exhaustive searches further reduce failure rates

Radio Astronomy

Contains research objectives, summary of research and reports on two research projects.National Aeronautics and Space Administration (Grant NGL 22-009-016)National Science Foundation (Grant GP-8415)National Science Foundation (Grant GP-7156)Joint Services Electronics Programs (U. S. Army, U.S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E

RNAi gene knockdown in the poultry red mite, Dermanyssus gallinae (De Geer 1778), a tool for functional genomics

The authors gratefully acknowledge funding for this project from the Scottish Government Rural Affairs, Food and the Environment (RAFE) Strategic Research Portfolio 2016-2021. DRGP is supported by a research fellowship provided by the Moredun Foundation. WC is supported by a studentship provided by the University of Aberdeen and the Moredun Foundation.Peer reviewedPublisher PD

Radio Astronomy

Contains research objectives, summary of research and reports on six research projects.National Aeronautics and Space Administration (Grant NGL 22-009-016)National Aeronautics and Space Administration (Grant NGR 22-009-421)National Aeronautics and Space Administration (Langley Research Center Contract NAS1-10693)National Science Foundation (Grant GP-20769A#2)National Science Foundation (Grant GP-21348A#2)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300U. S. Air Force -- Wright-Patterson (Contract F33615-72-C-2129)California Institute of Technology Contract 952568M.I.T. Sloan Fund for Basic Research (Grant 241)M.I.T. Thomas C. Desmond Fun

Main-Belt Comet P/2012 T1 (PANSTARRS)

We present initial results from observations and numerical analyses aimed at characterizing main-belt comet P/2012 T1 (PANSTARRS). Optical monitoring observations were made between October 2012 and February 2013 using the University of Hawaii 2.2 m telescope, the Keck I telescope, the Baade and Clay Magellan telescopes, Faulkes Telescope South, the Perkins Telescope at Lowell Observatory, and the Southern Astrophysical Research (SOAR) telescope. The object's intrinsic brightness approximately doubles from the time of its discovery in early October until mid-November and then decreases by ~60% between late December and early February, similar to photometric behavior exhibited by several other main-belt comets and unlike that exhibited by disrupted asteroid (596) Scheila. We also used Keck to conduct spectroscopic searches for CN emission as well as absorption at 0.7 microns that could indicate the presence of hydrated minerals, finding an upper limit CN production rate of QCN<1.5x10^23 mol/s, from which we infer a water production rate of QH2O<5x10^25 mol/s, and no evidence of the presence of hydrated minerals. Numerical simulations indicate that P/2012 T1 is largely dynamically stable for >100 Myr and is unlikely to be a recently implanted interloper from the outer solar system, while a search for potential asteroid family associations reveal that it is dynamically linked to the ~155 Myr-old Lixiaohua asteroid family.Comment: 15 pages, 4 figures, accepted for publication in ApJ Letter

Neurocognitive function in HIV infected patients on antiretroviral therapy

OBJECTIVE To describe factors associated with neurocognitive (NC) function in HIV-positive patients on stable combination antiretroviral therapy. DESIGN We undertook a cross-sectional analysis assessing NC data obtained at baseline in patients entering the Protease-Inhibitor-Monotherapy-Versus-Ongoing-Triple therapy (PIVOT) trial. MAIN OUTCOME MEASURE NC testing comprised of 5 domains. Raw results were z-transformed using standard and demographically adjusted normative datasets (ND). Global z-scores (NPZ-5) were derived from averaging the 5 domains and percentage of subjects with test scores >1 standard deviation (SD) below population means in at least two domains (abnormal Frascati score) calculated. Patient characteristics associated with NC results were assessed using multivariable linear regression. RESULTS Of the 587 patients in PIVOT, 557 had full NC results and were included. 77% were male, 68% Caucasian and 28% of Black ethnicity. Mean (SD) baseline and nadir CD4+ lymphocyte counts were 553(217) and 177(117) cells/µL, respectively, and HIV RNA was <50 copies/mL in all. Median (IQR) NPZ-5 score was -0.5 (-1.2/-0) overall, and -0.3 (-0.7/0.1) and -1.4 (-2/-0.8) in subjects of Caucasian and Black ethnicity, respectively. Abnormal Frascati scores using the standard-ND were observed in 51%, 38%, and 81%, respectively, of subjects overall, Caucasian and Black ethnicity (p<0.001), but in 62% and 69% of Caucasian and Black subjects using demographically adjusted-ND (p = 0.20). In the multivariate analysis, only Black ethnicity was associated with poorer NPZ-5 scores (P<0.001). CONCLUSIONS In this large group of HIV-infected subjects with viral load suppression, ethnicity but not HIV-disease factors is closely associated with NC results. The prevalence of abnormal results is highly dependent on control datasets utilised. TRIAL REGISTRY ClinicalTrials.gov, NCT01230580