title: New exact Betchov-like relation for the helicity flux in homogeneous turbulence

authors: Capocci, Damiano

abstract: In homogeneous and isotropic turbulence, the relative contributions of different physical mechanisms to the energy cascade can be quantified by an exact decomposition of the energy flux (Johnson, Phys. Rev. Lett., vol. 124, 2020, 104501; J. Fluid Mech., vol. 922, 2021, A3). We extend the formalism to the transfer of kinetic helicity across scales, important in the presence of large-scale mirror-breaking mechanisms, to identify physical processes resulting in helicity transfer and quantify their contributions to the mean flux in the inertial range. All subfluxes transfer helicity from large to small scales. Approximately 50% of the mean flux is due to the scale-local vortex flattening and vortex twisting. We derive a new exact relation between these effects, similar to the Betchov relation for the energy flux, revealing that the mean contribution of the former is three times larger than that of the latter. Multi-scale effects account for the remaining 50% of the mean flux, with approximate equipartition between multi-scale vortex flattening, twisting and entangling.

text: New exact Betchov-like relation for the helicity flux in homogeneous turbulence In homogeneous and isotropic turbulence, the relative contributions of different physical mechanisms to the energy cascade can be quantified by an exact decomposition of the energy flux (Johnson, Phys. Rev. Lett., vol. 124, 2020, 104501; J. Fluid Mech., vol. 922, 2021, A3). We extend the formalism to the transfer of kinetic helicity across scales, important in the presence of large-scale mirror-breaking mechanisms, to identify physical processes resulting in helicity transfer and quantify their contributions to the mean flux in the inertial range. All subfluxes transfer helicity from large to small scales. Approximately 50% of the mean flux is due to the scale-local vortex flattening and vortex twisting. We derive a new exact relation between these effects, similar to the Betchov relation for the energy flux, revealing that the mean contribution of the former is three times larger than that of the latter. Multi-scale effects account for the remaining 50% of the mean flux, with approximate equipartition between multi-scale vortex flattening, twisting and entangling.

year: 2023-05-11

title: Escrow: A large-scale web vulnerability assessment tool

authors: Delamore, Baden

abstract: The reliance on Web applications has increased rapidly over the years. At the same time, the quantity and impact of application security vulnerabilities have grown as well. Amongst these vulnerabilities, SQL Injection has been classified as the most common, dangerous and prevalent web application flaw. In this paper, we propose Escrow, a large-scale SQL Injection detection tool with an exploitation module that is light-weight, fast and platform-independent. Escrow uses a custom search implementation together with a static code analysis module to find potential target web applications. Additionally, it provides a simple to use graphical user interface (GUI) to navigate through a vulnerable remote database. Escrow is implementation-agnostic, i.e. It can perform analysis on any web application regardless of the server-side implementation (PHP, ASP, etc.). Using our tool, we discovered that it is indeed possible to identify and exploit at least 100 databases per 100 minutes, without prior knowledge of their underlying implementation. We observed that for each query sent, we can scan and detect dozens of vulnerable web applications in a short space of time, while providing a means for exploitation. Finally, we provide recommendations for developers to defend against SQL injection and emphasise the need for proactive assessment and defensive coding practices.

text: Escrow: A large-scale web vulnerability assessment tool The reliance on Web applications has increased rapidly over the years. At the same time, the quantity and impact of application security vulnerabilities have grown as well. Amongst these vulnerabilities, SQL Injection has been classified as the most common, dangerous and prevalent web application flaw. In this paper, we propose Escrow, a large-scale SQL Injection detection tool with an exploitation module that is light-weight, fast and platform-independent. Escrow uses a custom search implementation together with a static code analysis module to find potential target web applications. Additionally, it provides a simple to use graphical user interface (GUI) to navigate through a vulnerable remote database. Escrow is implementation-agnostic, i.e. It can perform analysis on any web application regardless of the server-side implementation (PHP, ASP, etc.). Using our tool, we discovered that it is indeed possible to identify and exploit at least 100 databases per 100 minutes, without prior knowledge of their underlying implementation. We observed that for each query sent, we can scan and detect dozens of vulnerable web applications in a short space of time, while providing a means for exploitation. Finally, we provide recommendations for developers to defend against SQL injection and emphasise the need for proactive assessment and defensive coding practices.

year: 2015-01-15

title: Challenges to psychology in Aotearoa

authors: Awatere-Huata, Donna

subjects: Maori

abstract: Maori people are putting up with a lot right now. If governments can transfer $20 billion in the past ten years for hand outs and write offs to Pakeha people who have endured little, then they can do a lot better than the $150 million they’ve transferred to our people that have endured so much for 150 years.  The big issue is still the Treaty, and the need to re-negotiate this nation’s management. The challenge is to design a political system that is based on Maori ways of doing things rather than Pakeha ways of doing things. To achieve this requires relinquishing colonial patterns of thinking and the certainty that pakeha people and their ways are superior to Maori. For psychologists the issue is their role in maintaining Pakeha economic and political power. It may well be that psychologists provide lousy value for money from the Maori point of view, but provide excellent value for money from the government’s point of view.

text: Challenges to psychology in Aotearoa Maori people are putting up with a lot right now. If governments can transfer $20 billion in the past ten years for hand outs and write offs to Pakeha people who have endured little, then they can do a lot better than the $150 million they’ve transferred to our people that have endured so much for 150 years.  The big issue is still the Treaty, and the need to re-negotiate this nation’s management. The challenge is to design a political system that is based on Maori ways of doing things rather than Pakeha ways of doing things. To achieve this requires relinquishing colonial patterns of thinking and the certainty that pakeha people and their ways are superior to Maori. For psychologists the issue is their role in maintaining Pakeha economic and political power. It may well be that psychologists provide lousy value for money from the Maori point of view, but provide excellent value for money from the government’s point of view.

year: 1993