Tighter Security for Efficient Lattice Cryptography via the Rényi Divergence of Optimized Orders

In security proofs of lattice based cryptography, bounding the closeness of two probability distributions is an important procedure. To measure the closeness, the Rényi divergence has been used instead of the classical statistical distance. Recent results have shown that the Rényi divergence offers security reductions with better parameters, e.g. smaller deviations for discrete Gaussian distributions. However, since previous analyses used a fixed order Rényi divergence, i.e., order two, they lost tightness of reductions. To overcome the deficiency, we adaptively optimize the orders based on the advantages of the adversary for several lattice-based schemes. The optimizations enable us to prove the security with both improved efficiency and tighter reductions. Indeed, our analysis offers security reductions with smaller parameters than the statistical distance based analysis and the reductions are tighter than those of previous Rényi divergence based analyses. As applications, we show tighter security reductions for sampling discrete Gaussian distributions with smaller precomputed tables for Bimodal Lattice Signature Scheme (BLISS), and the variants of learning with errors (LWE) problem and the small integer solution (SIS) problem called k-LWE and k-SIS, respectively

Unusual abscesses associated with colon cancer: report of three cases

Three cases of colon cancer accompanied by unusual abscess formation are reported. Case I : A 77-year-old man was diagnosed with a paracolic abscess formation behind the cecum and a swollen appendix by computed tomography (CT) scan. Case II : An 85-year-old woman was diagnosed with an abscess formation of the right iliopsoas muscle, a swollen appendix, and a thickened right colon wall by CT scan. After antibiotic therapy failed, both patients underwent ileocecal resection urgently under suspicion of appendicitis, but cecal cancer around the entrance to the appendix caused secondary appendicitis in both cases. Case III : A 50-year-old woman was diagnosed with sigmoid colon cancer with an abscess formation in the pelvic cavity concomitant with ovarian tumor. A Hartmann procedure was performed, and a pathological examination revealed that a subserosal abscess behind the sigmoid colon cancer perforated the rectum with abscess formation. All cases were definitively diagnosed intraoperatively. The cancer recurred in cases I and III. We emphasize that precise surgical evaluation has an important role in the diagnosis of these complicated diseases. In addition, surgery affords the patient the best chance of recovery, and in these advanced cases radical treatment is recommended as early as possible

Orbital- and spin-phase variability in the X-ray emission from the accreting pulsar Cen X-3

We analyzed 39 ks NuSTAR observation data of the high mass X-ray binary Cen X-3 in order to investigate the orbital- and spin-phase spectral variability. The observation covers the orbital phase of $\Phi=0.199$-$0.414$ of the source, where $\Phi=0$ corresponds to the mid-eclipse. The orbital-phase-resolved spectroscopy revealed that low energy photons are more dominant for the spectral fluctuation, and a large part of the variability can be explained in terms of absorption by clumps of stellar wind. The spin-phase-resolved spectroscopy together with energy-resolved pulse profiles, on the other hand, presented large flux variations in high energy bands, which suggests that the origin of the variability is the different efficiency of Comptonization inside the accretion column. The energy band which includes Fe emission lines or cyclotron resonance scattering feature (CRSF) shows distinct variability compared to the nearby bands. The Fe lines show low variability along the spin phase, which indicates that the emission regions are apart from the neutron star. The central energy and strength of the CRSF are both positively correlated with the spin-phase-resolved flux, which suggests that the emitted photons face stronger magnetic fields and deeper absorption when they come from high-flux regions. We also examined the independence of the orbital- and spin-phase variability. They showed no correlation with each other and were highly independent, which implies the accretion stream is stable during the observation.Comment: 20 pages, 12 figures, accepted for publication in Ap

Fabrication of a nanofiber Bragg cavity with high quality factor using a focused helium ion beam

Nanofiber Bragg cavities (NFBCs) are solid-state microcavities fabricated in an optical tapered fiber. NFBCs are promising candidates as a platform for photonic quantum information devices due to their small mode volume, ultra-high coupling efficiencies, and ultra-wide tunability. However, the quality (Q) factor has been limited to be approximately 250, which may be due to limitations in the fabrication process. Here we report high Q NFBCs fabricated using a focused helium ion beam. Whenan NFBC with grooves of 640 periods is fabricated, the Q factor is over 4170, which is more than 16 times larger than that previously fabricated using a focused gallium ion beam

Discovery and informing research participants of incidental findings detected in brain magnetic resonance imaging studies : Review and multi‐institutional study

Background: Brain imaging studies using magnetic resonance imaging (MRI ) sometimes reveal incidental findings (IFs) that might be relevant to some of the health issues in research participants. Although professional communities have discussed how to manage these IFs, there is no global consensus on the concrete handling procedures including how to inform participants of IFs. Methods: First, this study reviewed previous studies for the number of IFs discovered in brain imaging studies using MEDLINE. Second, a multi‐institutional study determined the number of IF discoveries and evaluated the method of informing participants at multiple institutions, which participated in a national brain science project in Japan. Results: Both the review and multi‐institutional study showed that IFs with a high urgency level were discovered in 0–2.0% of participants, including healthy volunteers, and that the rate of IF discovery in general was higher in studies conducted in elderly population. Moreover, multi‐institutional study suggested the criteria used to judge whether or not to inform participants of IFs may differ by institution. Conclusions: Our results suggest that in order to ensure informing the participants of high urgency IFs, physicians who are capable of interpreting brain images clinically should review all brain images, and the establishment of a support system is required for brain imaging studies at nonmedical institutions. Since the method of informing participants of IFs might affect their understanding and acceptance of IFs, which are related to managing risks of false “clean bill of health” or psychological impacts of informing IFs, further research focusing on communication of IFs is needed

Efficacy and Tolerability of Weekly Paclitaxel in Combination with High-dose Toremifene Citrate in Patients with Metastatic Breast Cancer

Toremifene citrate is expected to prevent drug resistance in cancer patients by inhibiting p-glycoprotein activity. The safety and efficacy of combination therapy with high-dose toremifene citrate and paclitaxel were investigated. Between December 2003 and June 2004, 15 women with a mean age of 53 years old with metastatic breast cancer were enrolled. The administration schedule was 80mg/m2 of paclitaxel given on Days 1, 8, and 15, and 120mg/day of toremifene citrate orally administered starting on Day 18. On Days 32 and 39, paclitaxel was concurrently administered again. Toxicities, response rate, and time to treatment failure were assessed. All patients had been treated with endocrine or chemotherapy. Grade 3 leukopenia occurred in 2 patients on the administration of paclitaxel alone, and grade 3 febrile neutropenia occurred in 1 patient given the combination therapy. There was no grade 3 or greater non-hematological toxicity. There was no complete response and 1 partial response, producing a response rate of 6.7%. Median time to treatment failure was 2.7 months. Combination therapy of paclitaxel and toremifene was safe and well tolerated with minimal toxicity. Further clinical trials targeting patients with functional p-glycoprotein are warranted.</p