24 resultados para Cold Neutron Research Facility (National Institute of Standards and Technology)
Resumo:
As ubiquitous computing becomes a reality, sensitive information is increasingly processed and transmitted by smart cards, mobile devices and various types of embedded systems. This has led to the requirement of a new class of lightweight cryptographic algorithm to ensure security in these resource constrained environments. The International Organization for Standardization (ISO) has recently standardised two low-cost block ciphers for this purpose, Clefia and Present. In this paper we provide the first comprehensive hardware architecture comparison between these ciphers, as well as a comparison with the current National Institute of Standards and Technology (NIST) standard, the Advanced Encryption Standard.
Resumo:
The ability to exchange keys between users is vital in any wireless based security system. A key generation technique exploits the randomness of the wireless channel is a promising alternative to existing key distribution techniques, e.g., public key cryptography. In this paper a secure key generation scheme based on the subcarriers’ channel responses in orthogonal frequencydivision multiplexing (OFDM) systems is proposed. We first implement a time-variant multipath channel with its channel impulse response modelled as a wide sense stationary (WSS) uncorrelated scattering random process and demonstrate that each subcarrier’s channel response is also a WSS random process. We then define the X% coherence time as the time required to produce an X% correlation coefficient in the autocorrelation function (ACF) of each channel tap, and find that when all the channel taps have the same Doppler power spectrum, all subcarriers’ channel responses has the same ACF as the channel taps. The subcarrier’s channel response is then sampled every X% coherence time and quantized into key bits. All the key sequences’ randomness is tested using National Institute of Standards and Technology (NIST) statistical test suite and the results indicate that the commonly used sampling interval as 50% coherence time cannot guarantee the randomness of the key sequence.
Resumo:
We report on calculations of energy levels, radiative rates, oscillator strengths and line strengths for transitions among the lowest 253 levels of the (1s22s22p6 ) 3s23p5 , 3s3p6 , 3s23p43d, 3s3p53d, 3s23p33d2 , 3s23p44s, 3s23p44p and 3s23p44d configurations of Ti VI. The general-purpose relativistic atomic structure package and flexible atomic code are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 253 levels, although calculations have been performed for a much larger number of levels. Comparisons are made with existing available results and the accuracy of the data is assessed. Additionally, lifetimes for all 253 levels are listed, although comparisons with other theoretical results are limited to only 88 levels. Our energy levels are estimated to be accurate to better than 1% (within 0.03 Ryd), whereas results for other parameters are probably accurate to better than 20%. A reassessment of the energy level data on the National Institute of Standards and Technology website for Ti VI is suggested.
Resumo:
The ability to exchange keys between users is vital in any wireless based security system. A key generation technique which exploits the randomness of the wireless channel is a promising alternative to existing key distribution techniques, e.g., public key cryptography. In this paper, a secure key generation scheme based on the subcarriers' channel responses in orthogonal frequency-division multiplexing (OFDM) systems is proposed. We first implement a time-variant multipath channel with its channel impulse response modelled as a wide sense stationary (WSS) uncorrelated scattering random process and demonstrate that each subcarrier's channel response is also a WSS random process. We then define the X% coherence time as the time required to produce an X% correlation coefficient in the autocorrelation function (ACF) of each channel tap, and find that when all the channel taps have the same Doppler power spectrum, all subcarriers' channel responses has the same ACF as the channel taps. The subcarrier's channel response is then sampled every X% coherence time and quantized into key bits. All the key sequences' randomness is tested using National Institute of Standards and Technology (NIST) statistical test suite and the results indicate that the commonly used sampling interval as 50% coherence time cannot guarantee the randomness of the key sequence.
Resumo:
BACKGROUND: In the previously reported ALSYMPCA trial in patients with castration-resistant prostate cancer and symptomatic bone metastases, overall survival was significantly longer in patients treated with radium-223 dichloride (radium-223) than in patients treated with placebo. In this study, we investigated safety and overall survival in radium-223 treated patients in an early access programme done after the ALSYMPCA study and before regulatory approval of radium-223.
METHODS: We did an international, prospective, interventional, open-label, single-arm, phase 3b study. Enrolled patients were aged 18 years or older with histologically or cytologically confirmed progressive bone-predominant metastatic castration-resistant prostate cancer with two or more skeletal metastases on imaging (with no restriction as to whether they were symptomatic or asymptomatic; without visceral disease but lymph node metastases were allowed). Patients received intravenous injections of radium-223, 50 kBq/kg (current recommendation 55 kBq/kg after implementation of National Institute of Standards and Technology update on April 18, 2016) every 4 weeks for up to six injections. Other concomitant anticancer therapies were allowed. Primary endpoints were safety and overall survival. The safety and efficacy analyses were done on all patients who received at least one dose of the study drug. The study has been completed, and we report the final analysis here. This study is registered with ClinicalTrials.gov, number NCT01618370, and the European Union Clinical Trials Register, EudraCT number 2012-000075-16.
FINDINGS: Between July 22, 2012, and Dec 19, 2013, 839 patients were enrolled from 113 sites in 14 countries. 696 patients received one or more doses of radium-223; 403 (58%) of these patients had all six planned injections. Any-grade treatment-emergent adverse events occurred in 523 (75%) of 696 patients; any-grade treatment-emergent adverse events deemed to be related to treatment were reported in 281 (40%) patients. The most common grade 3 or worse treatment-related treatment-emergent adverse events were anaemia in 32 (5%) patients, thrombocytopenia in 15 (2%) patients, neutropenia in ten (1%) patients, and leucopenia in nine (1%) patients. Any grade of serious adverse events were reported in 243 (35%) patients. Median follow-up was 7·5 months (IQR 5-11) and 210 deaths were reported; median overall survival was 16 months (95% CI 13-not available [NA]). In an exploratory analysis of overall survival with predefined factors, median overall survival was longer for: patients with baseline alkaline phosphatase concentration less than the upper limit of normal (ULN; median NA, 95% CI 16 months-NA) than for patients with an alkaline phosphatase concentration equal to or greater than the ULN (median 12 months, 11-15); patients with baseline haemoglobin levels 10 g/dL or greater (median 17 months, 14-NA) than for patients with haemoglobin levels less than 10 g/dL (median 10 months, 8-14); patients with a baseline Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 (median NA, 17 months-NA) than for patients with an ECOG PS of 1 (median 13 months, 11-NA) or an ECOG PS of 2 or more (median 7 months, 5-11); and for patients with no reported baseline pain (median NA, 16 months-NA) than for those with mild pain (median 14 months, 13-NA) or moderate-severe pain (median 11 months, 9-13). Median overall survival was also longer in patients who received radium-223 plus abiraterone, enzalutamide, or both (median NA, 95% CI 16 months-NA) than in those who did not receive these agents (median 13 months, 12-16), and in patients who received radium-223 plus denosumab (median NA, 15 months-NA) than in patients who received radium-223 without denosumab (median 13 months, 12-NA).
INTERPRETATION: Our findings show that radium-223 can be safely combined with abiraterone or enzalutamide, which are now both part of the standard of care for patients with metastatic castration-resistant prostate cancer. Furthermore, our findings extend to patients who were asymptomatic at baseline, unlike those enrolled in the pivotal ALSYMPCA study. The findings of prolonged survival in patients treated with concomitant abiraterone, enzalutamide, or denosumab require confirmation in prospective randomised trials.
FUNDING: Pharmaceutical Division of Bayer.
Resumo:
Bone disease and ectopic calcification are the two main consequences of hyperphosphataemia of chronic kidney disease (CKD). Observational studies have demonstrated that hyperphosphataemia in CKD is associated with increased mortality. Furthermore, the use of phosphate binders in dialysis patients is associated with significantly lower mortality. The UK Renal Registry data show significant underachievement of phosphate targets in dialysis patients. It is believed to be due to wide variation in how management interventions are used. The National Institute for Health and Clinical Excellence (NICE) has developed a guideline on the management of hyperphosphataemia in CKD. This is based on the evidence currently available using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. This review outlines the recommendations including research recommendations and discusses methodology, rationale and challenges faced in developing this guideline and the health economic model used to assess the cost-effectiveness of different phosphate binders. © 2013 S. Karger AG, Basel.