Segmentation of cone-beam CT using a hidden Markov random field with informative priors

Cone-beam computed tomography (CBCT) has enormous potential to improve the accuracy of treatment delivery in image-guided radiotherapy (IGRT). To assist radiotherapists in interpreting these images, we use a Bayesian statistical model to label each voxel according to its tissue type. The rich sources of prior information in IGRT are incorporated into a hidden Markov random field model of the 3D image lattice. Tissue densities in the reference CT scan are estimated using inverse regression and then rescaled to approximate the corresponding CBCT intensity values. The treatment planning contours are combined with published studies of physiological variability to produce a spatial prior distribution for changes in the size, shape and position of the tumour volume and organs at risk. The voxel labels are estimated using iterated conditional modes. The accuracy of the method has been evaluated using 27 CBCT scans of an electron density phantom. The mean voxel-wise misclassification rate was 6.2\%, with Dice similarity coefficient of 0.73 for liver, muscle, breast and adipose tissue. By incorporating prior information, we are able to successfully segment CBCT images. This could be a viable approach for automated, online image analysis in radiotherapy.

Vision-based estimation of airborne target pseudobearing rate using hidden Markov model filters

The problem of estimating pseudobearing rate information of an airborne target based on measurements from a vision sensor is considered. Novel image speed and heading angle estimators are presented that exploit image morphology, hidden Markov model (HMM) filtering, and relative entropy rate (RER) concepts to allow pseudobearing rate information to be determined before (or whilst) the target track is being estimated from vision information.

The use of Facebook in tertiary education : case study of a unit-related Facebook page in a university justice class

Purpose – This study aims to evaluate the usefulness of a university unit Facebook page, which was established to support a first-year university justice unit. The study pays particular regard to the Facebook page's impact on students learning outcomes and communications amongst students and between students and teaching staff. Design/methodology/approach – All students enrolled in the unit were asked to complete an online survey, which sought to determine whether they used the unit Facebook page and if so, the nature and extent of their use. Findings – The study found that the unit Facebook page was useful in achieving most learning objectives for the unit. This included enhancing students' knowledge and understanding of unit content, as well as their ability to critically analyse unit materials. Students also indicated that they found the Facebook page better than the university's central learning management system across a range of areas. It was particularly useful for facilitating unit-related discussions. Research limitations/implications – The survey results reported in this paper are based on a relatively small sample of students (n=67) from a first-year university justice unit. Future studies should seek to garner evidence from broader and larger samples that transcend specific unit populations. However, the findings of this study do indicate further support for the use of Facebook as a supplementary tool in university education. Originality/value – This study focuses on two aspects of social networking technologies that have not been previously researched and thus contributes to the growing literature on the uses and benefits of Facebook in tertiary education.

Hidden credential retrieval from a reusable password

We revisit the venerable question of access credentials management, which concerns the techniques that we, humans with limited memory, must employ to safeguard our various access keys and tokens in a connected world. Although many existing solutions can be employed to protect a long secret using a short password, those solutions typically require certain assumptions on the distribution of the secret and/or the password, and are helpful against only a subset of the possible attackers. After briefly reviewing a variety of approaches, we propose a user-centric comprehensive model to capture the possible threats posed by online and offline attackers, from the outside and the inside, against the security of both the plaintext and the password. We then propose a few very simple protocols, adapted from the Ford-Kaliski server-assisted password generator and the Boldyreva unique blind signature in particular, that provide the best protection against all kinds of threats, for all distributions of secrets. We also quantify the concrete security of our approach in terms of online and offline password guesses made by outsiders and insiders, in the random-oracle model. The main contribution of this paper lies not in the technical novelty of the proposed solution, but in the identification of the problem and its model. Our results have an immediate and practical application for the real world: they show how to implement single-sign-on stateless roaming authentication for the internet, in a ad-hoc user-driven fashion that requires no change to protocols or infrastructure.

Estimating hidden message length in binary image embedded by using boundary pixels steganography

In this paper, we propose a new steganalytic method to detect the message hidden in a black and white image using the steganographic technique developed by Liang, Wang and Zhang. Our detection method estimates the length of hidden message embedded in a binary image. Although the hidden message embedded is visually imperceptible, it changes some image statistic (such as inter-pixels correlation). Based on this observation, we first derive the 512 patterns histogram from the boundary pixels as the distinguishing statistic, then we compute the histogram difference to determine the changes of the 512 patterns histogram induced by the embedding operation. Finally we propose histogram quotient to estimate the length of the embedded message. Experimental results confirm that the proposed method can effectively and reliably detect the length of the embedded message.

UbiOpticon : participatory sousveillance with urban screens and mobile phone cameras

In many cities around the world, surveillance by a pervasive net of CCTV cameras is a common phenomenon in an attempt to uphold safety and security across the urban environment. Video footage is being recorded and stored, sometimes live feeds are being watched in control rooms hidden from public access and view. In this study, we were inspired by Steve Mann’s original work on sousveillance (surveillance from below) to examine how a network of camera equipped urban screens could allow the residents of Oulu in Finland to collaborate on the safekeeping of their city. An agile, rapid prototyping process led to the design, implementation and ‘in the wild’ deployment of the UbiOpticon screen application. Live video streams captured by web cams integrated at the top of 12 distributed urban screens were broadcast and displayed in a matrix arrangement on all screens. The matrix also included live video streams of two roaming mobile phone cameras. In our field study we explored the reactions of passers-by and users of this screen application that seeks to inverse Bentham’s original panopticon by allowing the watched to be watchers at the same time. In addition to the original goal of participatory sousveillance, the system’s live video feature sparked fun and novel user-led apprlopriations.

Unveiling hidden unstructured regions in process models

Process models define allowed process execution scenarios. The models are usually depicted as directed graphs, with gateway nodes regulating the control flow routing logic and with edges specifying the execution order constraints between tasks. While arbitrarily structured control flow patterns in process models complicate model analysis, they also permit creativity and full expressiveness when capturing non-trivial process scenarios. This paper gives a classification of arbitrarily structured process models based on the hierarchical process model decomposition technique. We identify a structural class of models consisting of block structured patterns which, when combined, define complex execution scenarios spanning across the individual patterns. We show that complex behavior can be localized by examining structural relations of loops in hidden unstructured regions of control flow. The correctness of the behavior of process models within these regions can be validated in linear time. These observations allow us to suggest techniques for transforming hidden unstructured regions into block-structured ones.

Educational paradox : the hidden obstacles to the integration of mobile phones in the language classroom

This paper reports on the findings of an international telecollaboration study using Facebook, in which teachers studying in M. Ed programs in Australia and Greece, discussed the use of mobile phones in language classrooms. Results suggest that invisible barriers exist in the use of mobile phones in the classroom, including bans on use in schools, lack of familiarity with educational uses for mobile phones, and negative perceptions about mobile phones specifically in terms of classroom management.

Hidden innovation : Policy, industry and the creative sector

The term ‘two cultures’ was coined more than 50 years ago by scientist and novelist C.P. Snow to describe the divergence in the world views and methods of scientists and the creative sector. This divergence has meant that innovation systems and policies have focused for decades on science, engineering, technology and medicine and the industries that depend on them. The humanities, arts and social sciences have been bit players at best; their contributions hidden from research agendas, policy and program initiatives, and the public mind. But structural changes to advanced economies and societies have brought services industries and the creative sector to greater prominence as key contributors to innovation. Hidden Innovation peels back the veil, tracing the way innovation occurs through new forms of screen production enabled by social media platforms as well as in public broadcasting. It shows that creative workers are contributing fresh ideas across the economy and how creative cities debates need reframing. It traces how policies globally are beginning to catch up with the changing social and economic realities. In his new book, Cunningham argues that the innovation framework offers the best opportunity in decades to reassess and refresh the case for the public role of the humanities, particularly the media, cultural and communication studies disciplines.

Compressed sensing using hidden Markov models with application to vision based aircraft tracking

This paper investigates compressed sensing using hidden Markov models (HMMs) and hence provides an extension of recent single frame, bounded error sparse decoding problems into a class of sparse estimation problems containing both temporal evolution and stochastic aspects. This paper presents two optimal estimators for compressed HMMs. The impact of measurement compression on HMM filtering performance is experimentally examined in the context of an important image based aircraft target tracking application. Surprisingly, tracking of dim small-sized targets (as small as 5-10 pixels, with local detectability/SNR as low as − 1.05 dB) was only mildly impacted by compressed sensing down to 15% of original image size.

Degradation modeling and monitoring of machines using operation-specific hidden Markov models

In this paper, a novel data-driven approach to monitoring of systems operating under variable operating conditions is described. The method is based on characterizing the degradation process via a set of operation-specific hidden Markov models (HMMs), whose hidden states represent the unobservable degradation states of the monitored system while its observable symbols represent the sensor readings. Using the HMM framework, modeling, identification and monitoring methods are detailed that allow one to identify a HMM of degradation for each operation from mixed-operation data and perform operation-specific monitoring of the system. Using a large data set provided by a major manufacturer, the new methods are applied to a semiconductor manufacturing process running multiple operations in a production environment.

Death on the front page : “Awesome things” and this thing called humanity

It has been called “the world’s worst recorded natural disaster,” and “the largest earthquake in 40 years,” galvanizing the largest global relief effort in history. For those of us involved in the discipline and/or the practice of communications, we realized that it presented a unique case study from a number of perspectives. Both the media and the public became so enraptured and enmeshed in the story of the tsunami of December 26, 2004, bringing to the fore a piece of geography and a peoples too rarely considered prior to the tragedy, that we felt compelled to examine the phenomenon. The overwhelming significance of this volume comes from its being a combination of both academic scholars and development practitioners in the field. Its poignancy becomes underscored from their wide-ranging perspectives, with 21 chapters representing some 14 different countries. Their realities provide not only credibility but also an unprecedented sensitivity to communication issues. Our approach here considers Tsunami 2004 from five communication perspectives: 1.) Interpersonal/ intercultural, 2.) Mass media, 3.) Telecommunications, 4.) Ethics, philanthropy, and development communication, and; 5.) Personal testimonies and observations. You will learn even more here about the theory and practice of disaster/crisis communication.

From stadium to page : why football deserves more fiction

A great football novel is like a perfectly executed bicycle-kick goal, like players such as Argentine legends Diego Maradona and Lionel Messi; they come along once in a generation. Against the accumulated volume of non-fiction football literature (some people still call it soccer), which could fill and spill out of a World Cup Stadium, football novels are comparatively rare. That said, football or soccer fiction is a genre with a very real and important historical longevity...

The Soldier's Wife (LP)

Audio recording of 10 tracks funded by Legacy, The Australia Council, and Arts Queensland. The recordings explore the untold stories of soldiers' wives through song. It features the vocal and songwriting talents of Jackie Marshall, Bertie Page, Sahara Beck, Emma Bosworth, Roz Pappalardo, and Kristy Apps. Recorded, Mixed, Mastered, and Co-Produced by Phil Graham.

Guardians of hidden universes

“Guardians of Hidden Universes” is a playful story for experiencing on your phone in the street. You’re a Guardian of Hidden Universes, and when you check your Communication Terminal you find the Guild has made a terrible mistake they need you to repair. The experience lasts about 15-25 minutes, and takes you around whatever city you happen to be in. That’s right – you can play it in any city in the world! The app was launched at Popup Playground‘s 2013 Fresh Air Festival – a new pervasive gaming festival in Melbourne, Australia. This playful story is inspired by the idea of creating a locative-experience that is not site-specific. How can we have an experience than engages with the environment that also can work worldwide? The story is also playing with the idea of engaging with a character and a space and intuition within a short period of time. The short and playful experience is a Universe Creation 101 production. It was conceived, written, and designed by Christy Dena; with artwork, coding, and interface design by Elroy.