197,854 research outputs found
[A-mode ultrasonic pointer for navigated pelvic surgery]
No full textSurgical navigation has proven to be a minimally invasive procedure that enables precise surgical interventions with reduced exposure to irradiation for patient and personnel. Fluoroscopy-based modules have prevailed on the market. For certain operations of the pelvis computed tomography is necessary with its high imaging quality and considerably larger scan volume. To enable navigation in these cases, matching of the CT data set and the patient's real pelvic bone is essential. The common pair point-matching algorithm is complemented by the surface-matching algorithm to achieve an even higher overall precision of the system. For conventional surface matching with a solid pointer, the bone has to be exposed from soft tissue quite extensively, using a solid pointer. This conflicts with the claim of computer-assisted surgery to be minimally invasive. We integrated an A-mode ultrasonic pointer with the intention to perform extended surface matching on the pelvic bone noninvasively. Related to the conventional method, comparable and to some extent even improved precision conditions could be established
Refining the PoinTER “human firewall” pentesting framework
No full textPurposePenetration tests have become a valuable tool in the cyber security defence strategy, in terms of detecting vulnerabilities. Although penetration testing has traditionally focused on technical aspects, the field has started to realise the importance of the human in the organisation, and the need to ensure that humans are resistant to cyber-attacks. To achieve this, some organisations “pentest” their employees, testing their resilience and ability to detect and repel human-targeted attacks. In a previous paper we reported on PoinTER (Prepare TEst Remediate), a human pentesting framework, tailored to the needs of SMEs. In this paper, we propose improvements to refine our framework. The improvements are based on a derived set of ethical principles that have been subjected to ethical scrutiny.MethodologyWe conducted a systematic literature review of academic research, a review of actual hacker techniques, industry recommendations and official body advice related to social engineering techniques. To meet our requirements to have an ethical human pentesting framework, we compiled a list of ethical principles from the research literature which we used to filter out techniques deemed unethical.FindingsDrawing on social engineering techniques from academic research, reported by the hacker community, industry recommendations and official body advice and subjecting each technique to ethical inspection, using a comprehensive list of ethical principles, we propose the refined GDPR compliant and privacy respecting PoinTER Framework. The list of ethical principles, we suggest, could also inform ethical technical pentests.OriginalityPrevious work has considered penetration testing humans, but few have produced a comprehensive framework such as PoinTER. PoinTER has been rigorously derived from multiple sources and ethically scrutinised through inspection, using a comprehensive list of ethical principles derived from the research literature
Pointer Machines and Pointer Algorithms: an Annotated Bibliography
No full textThe term pointer machine has been used ambiguously in Computer Science literature. In this report we give precise definitions of several models that have been referred to as "pointer machines" and list references for each of these models under the appropriate heading. 1 Introduction In a 1992 paper by Galil and the author we referred to a "pointer machine" model of computation. A subsequent survey of related literature has produced over thirty references to papers having to do with "pointer machines", naturally containing a large number of cross-references. These papers address a range of subjects that range from the model considered in the above paper to some other ones which are barely comparable. The fact that such different notions have been discussed under the heading of "pointer machines" has produced the regrettable effect that cross references are sometimes found to be misleading. Clearly, it is easy for a reader who does not follow a paper carefully to misinterpret its claims..
What is a "Pointer Machine"?
No full textA "Pointer Machine" is many things. Authors who consider referring to this term are invited to read the following note first. 1 Introduction In a 1992 paper by Galil and the author we referred to a "pointer machine " model of computation. A subsequent survey of related literature has produced over twenty references to papers having to do with "pointer machines", naturally containing a large number of cross-references. These papers address a range of subjects that range from the model considered in the above paper to some other ones which are barely comparable. The fact that such different notions have been discussed under the heading of "pointer machines" has produced the regrettable effect that cross references are sometimes found to be misleading. Clearly, it is easy for a reader who does not follow a paper carefully to misinterpret its claims when a term that is so ill-defined is used. This note is an attempt to rectify the situation. We start with a survey of the different notions..
Pointer Machines and Pointer Algorithms: an Annotated Bibliography
No full textThe term pointer machine has been used ambiguously in Computer Science literature. In this report we give precise definitions of several models that have been referred to as "pointer machines" and list references for each of these models under the appropriate heading
Calculational Derivation of Pointer Algorithms from Tree Operations
No full textWe describe an approach to the derivation of correct algorithms on treebased pointer structures. The approach is based on enriching trees in a way that allows us to model commonly-used pointer manipulations on tree structures
A combined representation for the maintenance of C programs
No full textA programmer wishing to make a change to a piece of code must first gain a full understanding of the behaviours and functionality involved. This process of program comprehension is difficult and time consuming, and often hindered by the absence of useful program documentation. Where documentation is absent, static analysis techniques are often employed to gather programming level information in the form of data and control flow relationships, directly from the source code itself. Software maintenance environments are created by grouping together a number of different static analysis tools such as program sheers, call graph builders and data flow analysis tools, providing a maintainer with a selection of 'views' of the subject code. However, each analysis tool often requires its own intermediate program representation (IPR). For example, an environment comprising five tools may require five different IPRs, giving repetition of information and inefficient use of storage space. A solution to this problem is to develop a single combined representation which contains all the program relationships required to present a maintainer with each required code view. The research presented in this thesis describes the Combined C Graph (CCG), a dependence-based representation for C programs from which a maintainer is able to construct data and control dependence views, interprocedural control flow views, program slices and ripple analyses. The CCG extends earlier dependence-based program representations, introducing language features such as expressions with embedded side effects and control flows, value returning functions, pointer variables, pointer parameters, array variables and structure variables. Algorithms for the construction of the CCG are described and the feasibility of the CCG demonstrated by means of a C/Prolog based prototype implementation
Analogue mouse pointer control via an online steady state visual evoked potential (SSVEP) brain-computer interface
No full textThe steady state visual evoked protocol has recently become a popular paradigm in brain–computer interface (BCI) applications. Typically (regardless of function) these applications offer the user a binary selection of targets that perform correspondingly discrete actions. Such discrete control systems are appropriate for applications that are inherently isolated in nature, such as selecting numbers from a keypad to be dialled or letters from an alphabet to be spelled. However motivation exists for users to employ proportional control methods in intrinsically analogue tasks such as the movement of a mouse pointer. This paper introduces an online BCI in which control of a mouse pointer is directly proportional to a user's intent. Performance is measured over a series of pointer movement tasks and compared to the traditional discrete output approach. Analogue control allowed subjects to move the pointer faster to the cued target location compared to discrete output but suffers more undesired movements overall. Best performance is achieved when combining the threshold to movement of traditional discrete techniques with the range of movement offered by proportional control
Pointer years of Norway spruce in the Western Beskidy Mountains (southern Poland)
No full textThe frequency of site and zonal pointer years in Norway spruce in two altitudinal zones (500−900 m and 900−1370 m a.s.l.) in the Western Beskidy Mountains was analysed. In total, 32 tree stands were studied – 16 in each zone. In both zones number of negative site pointer years increased along with increase of number of positive site pointer years. Above 900 m a. s. l. number of site pointer years increased along with the altitude, while below 900 m a.s.l. their number decreased along with the altitude. We found no common pointer years for all 32 populations. In lower zone, short winter, early and very warm spring or high precipitation in June and July in a given year caused negative pointer years. In the upper one positive pointer years occurred after the warm autumn and in years with the warm growing season
- …
