4,493 research outputs found
Best Effort and Practice Activation Codes
Activation Codes are used in many different digital services and known by
many different names including voucher, e-coupon and discount code. In this
paper we focus on a specific class of ACs that are short, human-readable,
fixed-length and represent value. Even though this class of codes is
extensively used there are no general guidelines for the design of Activation
Code schemes. We discuss different methods that are used in practice and
propose BEPAC, a new Activation Code scheme that provides both authenticity and
confidentiality. The small message space of activation codes introduces some
problems that are illustrated by an adaptive chosen-plaintext attack (CPA-2) on
a general 3-round Feis- tel network of size 2^(2n) . This attack recovers the
complete permutation from at most 2^(n+2) plaintext-ciphertext pairs. For this
reason, BEPAC is designed in such a way that authenticity and confidentiality
are in- dependent properties, i.e. loss of confidentiality does not imply loss
of authenticity.Comment: 15 pages, 3 figures, TrustBus 201
Dip-coating of suspensions
Withdrawing a plate from a suspension leads to the entrainment of a coating
layer of fluid and particles on the solid surface. In this article, we study
the Landau-Levich problem in the case of a suspension of non-Brownian particles
at moderate volume fraction . We observe different regimes
depending on the withdrawal velocity , the volume fraction of the suspension
, and the diameter of the particles . Our results exhibit three
coating regimes. (i) At small enough capillary number , no particles are
entrained, and only a liquid film coats the plate. (ii) At large capillary
number, we observe that the thickness of the entrained film of suspension is
captured by the Landau-Levich law using the effective viscosity of the
suspension . (iii) At intermediate capillary numbers, the situation
becomes more complicated with a heterogeneous coating on the substrate. We
rationalize our experimental findings by providing the domain of existence of
these three regimes as a function of the fluid and particles properties
Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach
Life has significantly altered the Earth’s atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life’s ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes
Picking battles: The impact of trust assumptions on the elaboration of security requirements
This position paper describes work on trust assumptions in the con-text of security requirements. We show how trust assumptions can affect the scope of the analysis, derivation of security requirements, and in some cases how functionality is realized. An example shows how trust assumptions are used by a requirements engineer to help define and limit the scope of analysis and to document the decisions made during the process
Up and Out: Journalism, Social Media, and Historical Sensibility
Much of the modern theorizing about journalism and communication attained its robustness due to a powerful convergence of distinct middle-range scholarly findings that emerged primarily in the 1970s and 1980s. In the present day, when we turn our analytical gaze to the relationship between journalism and social media, we thus need to strike a delicate balance between conducting new qualitative research, re-conceptualizing and re-interrogating the classic conclusions of political communication scholarship, and linking these two aspects of research together. However, we might also wish to extend our analytical gaze “out,” interrogating the movement of journalistic technology across history, as well as “up,” looking at how journalism fits within larger structural explanations regarding the shape of political life
Celebrity, Death, and Taxes: Michael Jackson\u27s Estate
The untimely death of Michael Jackson this past June presents an opportunity to reassess certain thorny estate tax issues that may arise when a celebrity dies owning valuable intellectual property. Elsewhere we have debated hypothetical, tax-motivated changes to state laws relating to postmortem publicity rights. This article focuses on existing legislation, like California’s, that makes publicity rights both devisable and descendible. Federal transfer taxes are levied on intangible property as well as tangible assets, and therefore apply to intellectual property, including a celebrity’s right of publicity and copyrights retained by an artist in his or her creations. Using Michael Jackson’s estate as an example, and focusing primarily on publicity rights, we examine two questions that any estate planner representing a celebrity client ought to consider. First, how should a personal representative value intellectual property for estate tax purposes? Second, what strategies are available to lessen the estate tax burden associated with certain intellectual property rights
Wave-Measuring Performance Characteristics of Spoondrift Spotter
Spoondrift Spotter represents a state-of-the-art wave measurement buoy developed by Spoondrift (www.spoondrift.co) and supported by funding from the Advanced Research Projects Agency – Energy (ARPA-E). A low-cost buoy platform like Spotter enables a range of new applications. For instance, coherent arrays of Spotters can support adaptive tuning of marine and hydrokinetic energy devices. In general, the availability of high-fidelity wave measurements can help support wave assessments for a variety of commercial, military, operational, academic, and recreational users
The association between neuroticism and self-reported common somatic symptoms in a population cohort
OBJECTIVE: To test the hypotheses that (1) neuroticism is associated with self-reported somatic symptoms; (2) this association is especially found with regard to psychosomatic symptoms; and (3) it is not solemnly explained by somatic reflections of psychological distress. METHODS: We studied the cross-sectional association between neuroticism (as measured by EPQ-RSS-N), psychological distress (as measured by GHQ-12 sum score), and the occurrence of 22 common somatic symptoms by linear and logistic regression analyses in a population cohort of 6894 participants. RESULTS: Neuroticism is more strongly associated with the total number of somatic symptoms reported (beta=.32) than GHQ-12 sum score (beta=.15) and well-established risk markers such as gender (beta=.11) and age (beta=.04). Neuroticism was associated with all symptoms in individual logistic regressions controlled for age, gender, and psychological distress. Neuroticism is significantly more strongly related to psychosomatic symptoms (beta=.36) than to infectious/allergic symptoms (beta=.28). CONCLUSION: In a large, population-based cohort, we confirmed that neuroticism is associated with self-reported somatic symptoms. The associations were not attributable to somatic reflections of psychological distress associated with neuroticism and were relatively strong with respect to psychosomatic symptoms. Future studies should include both objective and subjective measures of health to study the mechanisms that connect neuroticism and ill health
Does higher cost mean better quality? evidence from highly-regarded adolescent drug treatment programs
We conducted a survey to examine whether reimbursement levels are associated with the quality of adolescent substance use treatment programs in the United States. Between March and September 2005, telephone and written surveys were administered to program, clinical, and finance directors of previously surveyed highly regarded programs. Differences in quality scores were compared for programs with above versus below median reimbursement levels and examined in multivariate regression models constructed separately for programs offering residential and outpatient treatment. In residential treatment multivariate regression models, higher quality scores were associated with higher reimbursement, but this relationship was not observed for outpatient treatment. Even the highest level of outpatient reimbursement received may be too low to support quality improvement initiatives. Our results suggest that higher reimbursement may be a necessary component of quality improvement for residential adolescent drug treatment programs, and emphasize the need for further research to determine what levels of reimbursement and insurance coverage policies will encourage the expansion of high quality outpatient programs
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