Communication-Efficient Proactive Secret Sharing for Dynamic Groups with Dishonest Majorities

In standard Secret Sharing (SS), a dealer shares a secret $s$ among $n$ parties such that an adversary corrupting no more than $t$ parties does not learn $s$, while any $t+1$ parties can efficiently recover $s$. Proactive Secret Sharing (PSS) retains confidentiality of $s$ even when a mobile adversary corrupts all parties over the lifetime of the secret, but no more than a threshold $t$ in each epoch (called a refresh period). Withstanding such adversaries has become of increasing importance with the emergence of settings where private keys are secret shared and used to sign cryptocurrency transactions, among other applications. Feasibility of single-secret PSS for static groups with dishonest majorities was demonstrated but with a protocol that requires inefficient communication of $O(n^4)$. In this work, we improve over prior work in three directions: batching without incurring a linear loss in corruption threshold, communication efficiency, and handling dynamic groups. While each of properties we improve upon appeared independently in the context of PSS and in other previous work, handling them simultaneously (and efficiently) in a single scheme faces non-trivial challenges. Some PSS protocols can handle batching of $\ell \sim n$ secrets, but all of them are for the honest majority setting. Techniques typically used to accomplish such batching decrease the tolerated corruption threshold bound by a linear factor in $\ell$, effectively limiting the number of elements that can be batched with dishonest majority. We solve this problem by reducing the threshold decrease to $\sqrt{\ell}$ instead, allowing us to deal with the dishonest majority setting when $\ell \sim n$. This is accomplished based on new bivariate-polynomials-based techniques for sharing, and refreshing and recovering of shares, that allow batching of up to $n-2$ secrets in our PSS. To tackle the efficiency bottleneck the constructed PSS protocol requires only $O(n^3/\ell)$ communication for $\ell$ secrets, i.e., an amortized communication complexity of $O(n^2)$ when the maximum batch size is used. To handle dynamic groups we develop three new sub-protocols to deal with parties joining and leaving the group

Oncological and functional outcomes following open radical prostatectomy: how patients may achieve the "trifecta"?

PURPOSE: The desirable outcomes after open radical prostatectomy (RP) for localized prostate cancer (PC) are to: a) achieve disease recurrence free, b) urinary continence (UC), and c) maintain sexual potency (SP). These 3 combined desirable outcomes we called it the "Trifecta". Our aim is to assess the likelihood of achieving the Trifecta, and to analyze the influencing the Trifecta . MATERIALS AND METHODS: A total of 1738 men with localized PC underwent RP from 1992-2007 by a single surgeon. The exclusion criteria for this analysis were: preoperative hormonal or radiation therapy, preoperative urinary incontinence or erectile dysfunction, follow-up less than 24 months or insufficient data. Post-operative Trifecta factors were analyzed, including biochemical recurrence (BR).. We defined: BR as PSA > 0.2 ng/mL, urinary continence as wearing no pads, and sexual potency as having erections sufficient for intercourse with or without a phosphodiesterase-5 inhibitor. RESULTS: A total of 831 patients met the inclusion criteria. The mean age of the entire cohort was 59 years old. The median follow-up was 52 months (mean 60, range 24-202). The BR, UC and SP rates were 18.7%, 94.5%, and 71% respectively. Trifecta was achieved in 64% at 2 year follow-up, and 61% at 5 year follow-up. Multivariate analysis revealed age at time of surgery, pathologic Gleason score (PGS), pathologic stage, specimen weight, and nerve sparing (NS) were independent factors. CONCLUSIONS: Age at time of surgery, pathologic GS, pathologic stage, specimen weight and NS were independent predictors to achieve the Trifecta following radical prostatectomy. This information may help patients counseling undergoing radical prostatectomy for localized prostate cancer

Comparison of urologist reimbursement for managing patients with low-risk prostate cancer by active surveillance versus total prostatectomy

Active surveillance (AS) is an alternative to total prostatectomy (TP) in managing low-risk prostate cancer (PC). Our aim is to compare urologist reimbursement for managing low-risk PC by AS or TP. The urologist's reimbursement for TP includes the fee for the procedure and follow-up visits. For AS, our protocol involves digital rectal examination (DRE) and PSA testing every 3 months for first 2 years and every 6 months thereafter. Transrectal ultrasound (TRUS)-guided biopsies are performed yearly. Some urologists recommend spacing the biopsies by 1-3 years. Medicare reimbursement values were used. The urologist reimbursements for a follow-up visit, prostate biopsy, open TP and robotic TP are $72,$595, $1905 and$2939, respectively. We also corrected for a 15% chance of having TP after being on AS. The cumulative reimbursements from open TP and following the patient up to 10 years are approximately $2121 (1 year),$2265 (2 years), $2697 (5 years) and$3057 (10 years). For robotic TP, the urologist reimbursements are $3155 (1 year),$3259 (2 years), $3731 (5 years) and$4091 (10 years). For AS, the urologist reimbursements are $883 (1 year),$1766 (2 years), $4269 (5 years) and$7964 (10 years). The urologist reimbursement from AS and TP become nearly equal between 3 and 4 years follow-up, subsequently AS attains higher reimbursement

Application of selective solid-phase extraction using a new core-shell-shell magnetic ion-imprinted polymer for the analysis of ultra-trace mercury in serum of gallstone patients

A new ultrasonically assisted spectrophotometric method was developed using stabilized ion polymer on a modified nano-absorbent as a core- shell-shell absorbent (Fe3O4@SiO2@TiO2–IIP). It has the advantages of further stabilizing the polymer and consequently and much higher efficiency than its conventional adsorbents. The prepared sorbent was characterized and Its parameters were investigated by a Box–Behnken design. The linear dynamic range and limit of detection were 0.20–28.00 µg L−1 and 0.05 µg L−1 respectively. In selectivity study, it was founded that imprinting causes increased affinity of the prepared IIP toward Hg2+ ion. The proposed IIP is considered to be promising and selective sorbent for solid-phase extraction and preconcentration of Hg2+ ion in sera of different types of gallstone patients. © 2019 Taylor & Francis