White-box cryptography presented by Chow et al. is an obfuscation technique for protecting secret keys in software implementations even if an adversary has full access to the implementation of the encryption algorithm and full control over its execution platforms. Despite its practical importance, progress has not been substantial. In fact, it is repeated that as a proposal for a whitebox implementation is reported, an attack of lower complexity is soon announced. This is mainly because most cryptanalytic methods target specific implementations, and there is no general attack tool for white-box cryptography.
Although chest CT has been discussed as a first-line test for coronavirus disease 2019 (COVID-19), little research has explored the implications of CT exposure in the population. To review chest CT protocols and radiation doses in COVID-19 publications and explore the number needed to diagnose (NND) and the number needed to predict (NNP) if CT is used as a first-line test.We searched nine highly cited radiology journals to identify studies discussing the CT-based diagnosis of COVID-19 pneumonia. Study-level information on the CT protocol and radiation dose was collected, and the doses were compared with each national diagnostic reference level (DRL). The NND and NNP, which depends on the test positive rate (TPR), were calculated, given a CT sensitivity of 94% (95% confidence interval [CI]: 91%-96%) and specificity of 37% (95% CI: 26%-50%), and applied to the early outbreak in Wuhan, New York, and Italy.From 86 studies, the CT protocol and radiation dose were reported in 81 (94.2%) and 17 studies (19.8%), respectively. Low-dose chest CT was used more than twice as often as standard-dose chest CT (39.5% vs.18.6%), while the remaining studies (44.2%) did not provide relevant information. The radiation doses were lower than the national DRLs in 15 of the 17 studies (88.2%) that reported doses. The NND was 3.2 scans (95% CI: 2.2-6.0). The NNPs at TPRs of 50%, 25%, 10%, and 5% were 2.2, 3.6, 8.0, 15.5 scans, respectively. In Wuhan, 35418 (TPR, 58%; 95% CI: 27710-56755) to 44840 (TPR, 38%; 95% CI: 35161-68164) individuals were estimated to have undergone CT examinations to diagnose 17365 patients. During the early surge in New York and Italy, daily NNDs changed up to 5.4 and 10.9 times, respectively, within 10 weeks.Low-dose CT protocols were described in less than half of COVID-19 publications, and radiation doses were frequently lacking. The number of populations involved in a first-line diagnostic CT test could vary dynamically according to daily TPR; therefore, caution is required in future planning.Coronavirus disease 2019 (이하 COVID-19) 폐렴에서 CT를 일차 진단 검사로 사용하고자 하는 논의가 있지만, 대규모 인구에게 CT 검사를 적용했을 때의 상황을 고찰한 연구는 없었다. 본 연구에서는 COVID-19 폐렴을 다룬 연구들에서 CT 프로토콜과 방사선량을 분석하고, CT 검사가 일차 진단 검사법으로 사용될 때 필요한 CT 검사량에 대해 알아보고자 한다.본 연구는 9개의 인용도가 높은 영상의학과 저널에서 COVID-19 폐렴의 CT 기반 진단을 다룬 문헌들을 검색하였다. 먼저, 연구에서 제시된 CT 프로토콜, 방사선량을 조사하여, 이를 해당 국가의 diagnostic reference level과 비교하였다. 추가로, COVID-19에 대한 CT 민감도 94%, 특이도 37%를 적용하여, 우한시와 뉴욕, 이탈리아의 초기 COVID-19 outbreak에서 polymerase chain reaction (이하 PCR) 검사 양성률에 기반한 number needed to diagnose (이하 NND)와 number needed to predict (이하 NNP)를 계산하였다.총 86개의 연구가 검색되었고, 그중 CT 프로토콜은 81개의 연구에서(94.2%), 방사선량은 17개의 연구에서(19.8%) 보고되었다. 저선량 흉부 CT는 표준선량 흉부 CT보다 2배 많은 연구에서 활용되었다(39.5% vs. 18.6%). 방사선량을 보고한 17개의 연구들 중, 15개의 연구에서 방사선량은 해당 국가의 diagnostic reference level 수치보다 낮았다(88.2%). COVID-19에 대한 CT 민감도 94%, 특이도 37%를 적용하였을 때, NND는 3.2회 CT scans으로 나타났다. 한편, PCR 검사 양성률 50%, 25%, 10%, 5%에서의 한 명의 COVID-19 환자를 진단 위한 CT 검사량을 나타내는 NNP는 각각 2.2, 3.6, 8.0, 15.5회의 CT scans로 나타났다. 우한시에서는 최종 17365명의 COVID-19 환자를 진단하기 위하여 약 35418명에서(PCR 검사 양성률 58%) 44840명(PCR 검사 양성률 38%)의 사람들이 CT 검사를 받은 것으로 나타났다. 뉴욕시와 이탈리아의 초기 COVID-19 유행 10주간, PCR 검사 양성률에 따라 일 CT 검사량이 최대 5.4, 10.9배까지 변화하였다.CT를 COVID-19에 대한 일차적인 진단검사로 사용할 경우, PCR 검사 양성률에 따라 CT 검사량은 변동량이 크고, 이는 추후 판데믹 상황에서 고려되어야 할 것이다.
Tumors of the clivus and metastases to the clivus are very rare. Metastasis involving the clivus has previously been described in only two case reports. In skull metastasis, the breast and prostate are the most common primary foci, while metastasis from gastric carcinoma is extremely rare. A review of the English literature revealed only one published case of clivus metastases from gastric adenocarcinoma. There is no literature thoroughly explaining the differential diagnosis between chordoma and metastasis. Here we report a rare case of metastasis to the clivus from a gastric adenocarcinoma in a 42-year-old female patient with sudden blurry vision, presenting as bilateral cranial nerve VI palsy.
We conducted a meta-analysis to determine a practical observation time for detecting a biphasic reaction after resolution of the initial anaphylactic reaction.A systematic literature search identified studies on adult patients with anaphylaxis and a subsequent biphasic reaction due to various causes that contained sufficient data to extract outcomes. The outcomes were pooled using a random-effects model.Twelve studies with a total of 2,890 adult patients with anaphylaxis and 143 patients with a biphasic reaction were included. In terms of the pooled negative predictive value, 1 h of observation achieved a 95.0% negative predictive value and ≥6 h of observation provided a 97.3% negative predictive value (95% CI: 95.0-98.5). The negative predictive value for a biphasic reaction increased with a longer observation time after initial anaphylaxis, and the increasing trend slowed down from 6 h of observation time. The pooled additional incidence rates of biphasic reactions per 100 person-hours after 1- and 4-h observations were 0.45 (95% CI: 0.20-1.04) and 0.41 (95% CI: 0.19-0.87), respectively. After > 8-12 h of postanaphylactic observation, the negative predictive value reached > 98%, while the additional incidence per 100 person-hours was < 0.10.An observation time of ≥6 h after resolution of an initial anaphylaxis symptom can exclude recurrence of a secondary reaction in > 95% of patients. Although longer observation periods resulted in the detection of more biphasic reactions, 6-12 h of observation time would be practical, supporting current relevant guidelines.
As the associations between pediatric overweight/obesity and bone health remain controversial, we investigated the effects of overweight/obesity as well as lean mass (LM) and fat mass (FM) on bone parameters in adolescents. Bone parameters were evaluated using dual-energy X-ray absorptiometry (DXA) data of 982 adolescents (aged 12-19 years) from the Korea National Health and Nutrition Examination Survey (2009-2010). Z-scores for LM, FM, bone mass, bone mineral density (BMD), and bone mineral apparent density (BMAD) using Korean pediatric reference values were used for analysis. Adolescents with overweight/obesity had significantly higher bone mass and density of the total-body-less-head (TBLH), lumbar spine, and femur neck than underweight or normal-weight adolescents (P < 0.001) after adjusting for vitamin D deficiency, calcium intake, and insulin resistance in both sexes. LM was positively associated with bone parameters at all skeletal sites in both sexes (P < 0.001). FM was negatively related to TBLH BMD in boys (P = 0.018) but was positively associated to BMD and BMAD of the lumbar spine and femur neck in girls. In conclusion, overweight/obesity and LM play a positive role in bone health in adolescents. The effect of FM on bone parameters is sex- and site-specific.
Objectives : This study is to evaluate the awareness, attitude, practice and the countermeasures against passive smoking in Korean adults. Methods : By self-administered questionnaires, we assessed the knowledge, attitude, behavior for passive smoking and the countermeasure for reduction of it's harmful effects in 289 men and 238 women. Results : The subjects that have heard about passive smoking were 96.8% in total and well known were 26.4% of current smoker, 56.6% of ex-smoker, and 14.8% of non-smoker(p=0.001). The irritative symptom from passive smoking was the most frequent in non-smokers and the most common place where exposed to passive smoking was public place. For attitude against passive smoking in 'no smoking allowed area', ex-smokers were the most active to recommend to stop smoking. And for opinion about establishment of 'no smoking allowed area', the restriction by law was the best acceptable method in smokers, exsmokers, and nonsmokers. In marking of 'no smoking allowed area', 69.9% of smokers answered no smoking, but in non-marking area only 6.3% stop smoking. When smokers were recommended to stop smoking, the more subjects stop smoking with good feeling in marking area, but the less in non-marking area. The factor associated the high awareness of passive smoking were aged(OR=1.07, 1.03-1.12), men(OR=4.34, 2.32-8.46). The persons who have known well about passive smoking had good attitude and behavior to prevent of harmful effect of passive smoking. Conclusions : This study suggested that education program would be necessary to reduce the passive smoking.
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