防黑客设计技术

随着嵌入设备渗透进社会,并承担起更加重要的角色,安全失效会带来潜在的灾难性的后果。嵌入设备以无人干预方式运行在很多领域的数千种关键任务或安全相关系统中,如制造、健康保健、运输、金融和军事等。虽然我们不假思索地依赖于这些嵌入系统,但任何一种嵌入系统都可能成为临时黑客、犯罪团伙、恐怖分子,甚至敌对政府分子的潜在目标。阻止这些攻击的重任就落在了系统设计者的肩上,他不仅要保证通过或保存在嵌入设备中的数据的安全,而且还要保护产品本身的知识产权。     

An epidemic of roller-blade injuries in children

Roller blading is a new and increasingly popular leisure activity in many countries. We reviewed 110 consecutive patients with roller-blade injuries between 1 January and 30 June 1996. The patients ranged from 4 to 14 years in age (mean 6.5 years). Eighty-three (75.4%) sustained injuries to the upper limb and 27 (24.5%) injured the lower limb. Fifty-six patients, were girls and 54 were boys. Of the 110 patients, 79 (72.7%) sustained fractures, 28 (25.4%) soft tissue injuries and 3 (2.7%) dislocations. Eighty-three (75.4%) of the patients wore no protective equipment on the limbs. Four months following injury 103 (93.6%) patients were fully recovered. The mean duration of school absence was 3 days. Subsequently 101 children returned to using roller-blades following injury. Seventy-three (66.3%) of these now use protective equipment. We found that injuries were unrelated to age or duration of roller-blading experience or to the brand-name of roller blades used, and that most of our patients wore no protective equipment at the time of injury.     

Short contact time dissolution of vitrinite and inertinite concentrates

The short contact time dissolution of vitrinite and inertinite concentrates of an Australian bituminous coal was studied under isothermal conditions with tetralin as solvent. The reactivity of the two maceral types and the yields and nature of the products were determined for a range of reaction temperatures (400, 420 and 440 °C) and reaction times (2–20 min). The dissolution of vitrinite proceeded at a significantly greater rate than for inertinite and was associated with greater selectivity to soluble non-gaseous products. At very short reaction times (2 min), the vitrinite underwent solubilizing reactions to yield products of higher molecular weight and greater oxygen functionality than was the case for inertinite, for which changes in the chemical nature of the products were negligible over the range of conditions studied. At longer reaction times (5 min), the composition of the vitrinite-derived products was similar to that of the inertinite-derived products.     

Particle Penetration through Inclined and L-Shaped Cracks

This paper presents a particle penetration model predicting particle penetration coefficient (Pp) through a narrow crack of arbitrary incline angles (θ). The objective was to simulate Pp for outdoor-to-indoor particle penetration for residential infiltration conditions. This model assumes laminar infiltration flow and considers particle deposition from both gravitational sedimentation and Brownian diffusion. For micron-sized particles, modeling results indicate that gravitational sedimentation is the major deposition mechanism. Pp increases monotonically with ∣θ∣ because effective particle sedimentation velocity (vs?cos?θ) decreases monotonically with ∣θ∣. For submicron-sized particles (0.1?μm), Brownian diffusion is the major particle deposition mechanism. Because Brownian diffusion is a nondirectional deposition mechanism, crack inclination did not affect Pp. This study applied this model to estimate Pp for L-shaped cracks, and validated modeling results with experiments. Experimental results indicated that inertial impaction and crack entrance cutoff effects were not significant particle deposition mechanisms for the test micron-sized particles. Gravitational sedimentation was the major deposition mechanism. An L-shaped crack can be simulated as the combination of horizontal and vertical sections. This model agreed reasonably with experimental results.     

Infectious disease mortality among adults by race and socioeconomic status: metropolitan Ohio, 1989-1991

The data presented here are part of an on-going longitudinal study of the relationship between socioeconomic status and mortality in the major metropolitan centers of Ohio. Using a Standardized Mortality Ratio, we find that mortality in the seven-city urban aggregate exceeds that of the rest of the state by 39 per cent for the nonwhite population and only 1 per cent for the white population. Further, for the nonwhite population, living in a high income area has no discernible health benefit for nonwhites as compared to whites. On the other hand, for the AIDS virus, there is a clear inverse association between economic status and mortality from AIDS. It is clear that the interrelationship among race, economic status, and health continues to be a complex one on which further research is needed.     

Antiserum against Escherichia coli J5 contains antibodies reactive with outer membrane proteins of heterologous gram-negative bacteria

The binding of IgG in antiserum to Escherichia coli J5 to the surface of Enterobacteriaceae and to cell wall fragments released from serum-exposed bacteria was studied in a search for potentially protective epitopes other than lipopolysaccharide (LPS). IgG titers to multiple heterologous gram-negative smooth bacteria increased following incubation of the bacteria in serum and decreased following absorption with serum-exposed heterologous bacteria. IgG eluted from absorbing bacteria bound to at least three conserved bacterial outer membrane proteins (OMPs), but not LPS, as assessed by immunoblotting. The same OMPs were present in LPS-containing macromolecular cell wall fragments released by incubation of heterologous gram-negative bacteria in human serum. Part of the protection offered by J5 antiserum could be from binding of IgG to conserved OMPs at the bacterial surface or to OMPs in cell-wall fragments released from dying bacteria.     

Expandable metal mesh stents for treatment of tracheal stenoses and tracheomalacia

The treatment of tracheo-bronchial stenosis or tracheomalacia is mainly carried out by means of resection or tracheoplastic operative strategies. Since the introduction of metal-mesh stents, a definitive endoluminal therapy has to be considered under new aspects. Six patients with malignant stenosis or tracheomalacia due to compression were treated by implantation of Palmaz- or Wallstents. Immediately after the implantation, patients were relieved from dyspnoea, the forced inspiratory volume-1 (FIV1) was normalized. All implanted stents were well tolerated, even in the long-time follow-up (19 months). Bronchoscopic control showed overgrowth of the metal meshes by respiratory epithelium. The implantation of metal-mesh stents is an adequate alternative in the treatment of malignant stenosis and tracheomalacia.