Digital evidence: dream and reality

Digital evidence is inherently weak. New evidence-gathering technologies-digital black boxes-must be developed and deployed to support investigations of irreproducible events such as digitally signing a document or electronically casting a ballot.     

The influence of composition and processing parameters on the mechanical properties and erosion response of Ni + TiB2 coatings

Sputtered Ni + TiB₂ coatings have been shown to protect Inconel* 718 and Ti-6A1-4V substrates from solid particle erosion. However, before new erosion-resistant coatings can be efficiently designed, it is essential that the role of mechanical properties in determining erosion resistance be fully understood. In this investigation, nanoindentation techniques were used to quantify the effects of substrate preparation, coating composition, and sputtering process parameters on the elastic moduli and indentation hardness of thin coatings deposited on Ti-6A1-4V and Inconel 718 substrates. The influence of these parameters on coating adhesion was determined using a conventional scratch test. Elastic moduli, indentation hardnesses, and coating adhesion were correlated with erosion behavior. The erosion resistance of those coatings that exhibited microscopic ductility is dependent on the nodule diameter and coating properties such as hardness, elastic modulus, and fracture toughness. Inconel 718 is a trademark of The International Nickel Co.     

Life-cycle economic analysis of distributed manufacturing with open-source 3-D printers

The recent development of open-source 3-D printers makes scaling of distributed additive-based manufacturing of high-value objects technically feasible and offers the potential for widespread proliferation of mechatronics education and participation. These self-replicating rapid prototypers (RepRaps) can manufacture approximately half of their own parts from sequential fused deposition of polymer feedstocks. RepRaps have been demonstrated for conventional prototyping and engineering, customizing scientific equipment, and appropriate technology-related manufacturing for sustainable development. However, in order for this technology to proliferate like 2-D electronic printers have, it must be economically viable for a typical household. This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average US household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of 20 open-source printable designs (representing less than 0.02% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs. The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected 20 products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25 h of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4 months to 2 years and provide an ROI between >200% and >40%. As both upgrades and the components that are most likely to wear out in the RepRap can be printed and thus the lifetime of the distributing manufacturing can be substantially increased the unavoidable conclusion from this study is that the RepRap is an economically attractive investment for the average US household already. It appears clear that as RepRaps improve in reliability, continue to decline in cost and both the number and assumed utility of open-source designs continues growing exponentially, open-source 3-D printers will become a mass-market mechatronic device.     

Targeting Telomere Biology in Acute Lymphoblastic Leukemia

Increased cell proliferation is a hallmark of acute lymphoblastic leukemia (ALL), and genetic alterations driving clonal proliferation have been identified as prognostic factors. To evaluate replicative history and its potential prognostic value, we determined telomere length (TL) in lymphoblasts, B-, and T-lymphocytes, and measured telomerase activity (TA) in leukocytes of patients with ALL. In addition, we evaluated the potential to suppress the in vitro growth of B-ALL cells by the telomerase inhibitor imetelstat. We found a significantly lower TL in lymphoblasts (4.3 kb in pediatric and 2.3 kb in adult patients with ALL) compared to B- and T-lymphocytes (8.0 kb and 8.2 kb in pediatric, and 6.4 kb and 5.5 kb in adult patients with ALL). TA in leukocytes was 3.2 TA/C for pediatric and 0.7 TA/C for adult patients. Notably, patients with high-risk pediatric ALL had a significantly higher TA of 6.6 TA/C compared to non-high-risk patients with 2.2 TA/C. The inhibition of telomerase with imetelstat ex vivo led to significant dose-dependent apoptosis of B-ALL cells. These results suggest that TL reflects clonal expansion and indicate that elevated TA correlates with high-risk pediatric ALL. In addition, telomerase inhibition induces apoptosis of B-ALL cells cultured in vitro. TL and TA might complement established markers for the identification of patients with high-risk ALL. Moreover, TA seems to be an effective therapeutic target; hence, telomerase inhibitors, such as imetelstat, may augment standard ALL treatment.     

Participant registration, validation, and key distribution forlarge-scale conferencing systems

DiRK (Distributed Registration and Key distribution) is a technique that can be used in large-scale conferencing systems to handle participant registration, validation, and key distribution in a decentralized and distributed way. The basic idea is to distinguish active and passive participants in a conference session, and to have the active participants assist the session holder to register participants and distribute session keys accordingly. This article introduces the basic principles of DiRK and overviews a prototype implementation for the Internet Multicast Backbone (MBone). As an exemplary application, the article also addresses the use of DiRK in distance education and teleteaching     

Internet security enters the Middle Ages

The Internet continues its triumphant advance. It is commonly seen as the first incarnation of an information superhighway, or a national information infrastructure (NII). Because the Internet is dynamic, it has already changed significantly. The initial, research-oriented Internet and its protocol suite were designed for a benign environment best described as collegial, where users and hosts were mutually trusting and interested in a free, open exchange of information. These days, the Internet environment is less collegial and trustworthy; it encompasses all the risks, dangerous situations, and human vices found in society as a whole. The Internet has just entered the Middle Ages. The simple security model of the Stone Age still works for single hosts and LANs. But it no longer works for WANs in general and the Internet in particular. As a first step, firewalls have been erected at the Internet gateways. Because they are capable of selectively dropping or forwarding IP datagrams, firewalls also restrict the connectivity of the Internet as a whole. The Internet's firewalls are thus comparable to the town walls and front gates of the Middle Ages. Screening routers correspond to general-purpose gates, while proxy servers and application-layer gateways correspond to specialized gates     

Microsoft .Net Passport: a security analysis

.NET Passport is a password-based single sign-in service that lets users visit multiple Web sites without having to authenticate at each site. Despite its widespread deployment, several open issues remain.