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Background: Pediatric posterior fossa ependymoma contributes to morbidity and mortality in children. Following gross total resection and adjuvant radiotherapy, there is a known risk of local recurrence that portends a dismal prognosis. We sought to characterize survival in a molecularly defined cohort with an emphasis on recurrence patterns that influence outcome. Methods: This study was approved by the Ethics Board of the Hospital for Sick Children. We performed a twenty-year single-center retrospective study to identify clinical, demographic and treatment characteristics of patients with pathologically diagnosed posterior fossa ependymoma. Results: There were 60 patients identified that underwent primary resection. Recurrence rate in the cohort was 48% with 29 cases of recurrent ependymoma occurring at a mean time of 24 months after index surgery. No mortalities were observed among patients undergoing primary resection without recurrent disease. Median cohort survival was 12.3 years in the primary cohort and and 6.32 years among patients recurrent ependymoma. Recurrent disease was significantly associated with worse overall survival after multivariate analysis (HR = 0.024). Conclusions: We highlight overall survival and factors influencing mortality in pediatric posterior fossa ependymoma. Recurrent disease confers a worse prognosis. We describe for the first time survival trends following local and distant recurrences managed through multiple resections.
The most westerly Pacific island chain, running from Taiwan southwards through the Philippines, has long been central in debates about the origins and early migrations of Austronesian-speaking peoples from the Asian mainland into the islands of Southeast Asia and Oceania. Focusing on the Cagayan Valley of northern Luzon in the Philippines, the authors combine new and published radiocarbon dates to underpin a revised culture-historical synthesis. The results speak to the initial contacts and long-term relationships between Indigenous hunter-gatherers and immigrant Neolithic farmers, and the question of how the early speakers of Malayo-Polynesian languages spread into and through the Philippines.
Cassowaries (Casuarius) are one of the largest indigenous animal species of New Guinea. Researchers have long been trying to understand their local socio-cultural significance. Here we present new results from interviews recorded in 2018 on ethnography associated with bone daggers, a material culture ornament and tool carved from the cassowary's tibiotarsus. We present a ‘storied notion’—a contemporary narrative from oral history of why cassowary is not simply a bird, and briefly describe cassowary bone ornamentation in Auwim, East Sepik Province of Papua New Guinea. By exploring the material history of Casuarius through a ‘storied notion’ approach, we reveal that cassowary bone daggers in rock art are narrative ideas of the species from its landscape to ornamentation and through to people's cosmological beliefs surrounding Casuarius. We argue that the cassowary bone dagger stencil can be seen as part of the life history of this animal.
Older adults are often underrepresented in clinical research, even though older adults are major consumers of novel therapies. We present major themes and recommendations from the 2021 "Inclusion of Older Adults in Clinical Research" Workshop, convened by the Clinical and Translational Science Award (CTSA) Inclusion of Older Adults as a Model for Special Populations Workgroup and the Research Centers Collaborative Network (RCCN). The goal of this workshop was to develop strategies to assist the research community in increasing the inclusion of older adults in clinical research. Major identified barriers include historical lack of federal guidelines, ageist biases and stereotypes, and lack of recruitment and retention techniques or infrastructure focused on older adults. Three key recommendations emerged: 1) engaging with the policymaking process to further promote inclusion; 2) using the CTSA Workgroup Presentation Materials Library and other resources to overcome ageism, and 3) building institutional capacity to support age inclusion.
Background: Standard of care treatment for adult intracranial ependymoma patients includes maximal safe surgical resection, while the role for adjuvant radiotherapy remains unclear with existing data from small retrospective series’. Accordingly, we built a multi-institutional cohort to assess the prognostic value of adjuvant radiotherapy and other clinical factors in these patients. Methods: Patients managed for adult intracranial ependymomas from 1968 onwards within the University Health Network in Toronto, The University of Oklahoma Health Sciences Center, and The Ottawa Hospital were identified. Multivariate models assessing the prognostic value of clinical factors were built using variables with known prognostic value and/or significance in univariate Cox models. Results: Of 122 ependymomas, 71% were infratentorial, 78% grade two, 55% gross/near-totally resected (GTR/NTR), and 65% treated with adjuvant radiotherapy. Multivariate analyses identified GTR/NTR (vs. subtotal resection; HR=0.2, 95%CI=0.1–0.4, p<0.0001) and cranial (HR=0.5, 95%CI=0.2–1.1) or craniospinal (HR=0.2, 95%CI=0.04–0.5) radiotherapy receipt (p=0.01) as independent statistically significant predictors of more favourable PFS. Grade II pathology (vs. grade III; HR=0.2, 95%CI=0.05–0.6, p=0.006) and GTR/NTR (vs. subtotal resection; HR=0.1, 95%CI=0.03–0.3, p=0.0001) were independent statistically significant predictors of better OS. Conclusions: This work confirms the importance of maximal safe resection for adult intracranial ependymomas and establishes that adjuvant radiotherapy improves progression-free survival in these patients.
Background: Mean arterial pressure augmentation is one current established practice for management of patients with SCI. We present the first data investigating the effectiveness of Intrathecal Pressure (ITP) reduction through CSF drainage (CSFD) in managing patients with acute traumatic SCI at a large academic center. Methods: Data from 6 patients with acute traumatic SCI were included. A lumbar intrathecal catheter was used to monitor ITP and volume of CSFD. CSFD was performed and recorded hourly. ITP recordings were collected hourly and the change in ITP was calculated (hour after minus before CSFD). 369 data points were collected and change in ITP was plotted against volume of CSFD. Results: Data across all patients showed variability in the ITP over time without a significant trend (slope=0.016). We found no significant change in ITP with varying amounts of CSFD (slope=0.007, r2=0.00, p=0.88). Changes in ITP were not significantly different across groups of CSFD but the variation in the data decreased with increasing levels of CSFD. Conclusions: We present the first known data on changes in ITP with varying degrees of CSFD in patients with acute traumatic SCI. These results may provide insight into the complexity of ITP changes in patients post-injury and help inform future SCI management.
The excavation of the Qin wooden documents from Well No. 1 at Liye 里耶, Hunan province has significantly reshaped our knowledge of Qin history. This article examines a multi-slip manuscript from Liye on the Qin management of human resources in a newly conquered area, Qianling County. The manuscript is the best example of the multi-layered structure of a Qin administrative document; it also sheds new light on the difficulties the Qin encountered in resource management during the early years of unification. The manuscript shows that the responsible officials in Qianling County had failed to engage tuli 徒隸 (laborer-servants)—a major labor source in the Qin—in agricultural production, which appears to have deviated from the Qin strategy of managing human resources. To minimize the harmfulness that this deviation might cause, the Qin heavily relied upon a system of supervision and punishment. This article offers a contextualized study of the manuscript with an analysis of the related Qin excavated sources.
The introduction of new animals into hunter-gatherer societies produces a variety of cultural responses. This article explores the role of rock art in western Arnhem Land, Australia, in helping to mediate contact-period changes in Indigenous society in the nineteenth century. The authors explore etic and emic perspectives on the ‘re-emergence’ of water buffalo into Aboriginal cultural life. Merging archaeological analysis, rock art and ethnographic accounts, the article demonstrates how such artworks were used as a tool for maintaining order in times of dramatic social change. The results of this research have significant implications for understanding how cultural groups and individuals worldwide used rock art during periods of upheaval.
For some decades now, China’s environmental problems have been well known. Ranging from headline-grabbing instances of life-threatening air pollution in the country’s major cities, to horrendous industrial accidents that claim shocking numbers of lives, to water pollution that make the rivers run black, the world has come to know China’s pollution problems as systemic and serious in nature. For decades, the government has taken the position that pollution was an unavoidable by-product of the nation’s need to industrialize and develop economically. Nevertheless, concern about pollution has now become so widespread among ordinary citizens that an investigative documentary on China’s air pollution issues, “Under the Dome,”1 garnered tens of millions of views on YouTube before the government shut it down.2 Across China, public protests and activism related to environmental issues are now commonplace.
This article examines the evolution of the video game industry in Britain from its start in 1978. The industry originated with passionate hobbyists and amateurs who benefited from the national broadcaster's campaign to expand computer literacy. Unlike the regional clustering of the industry in the United States and Japan, the British industry was dispersed geographically, consisting of mini-clusters with porous boundaries. During the 2000s, the fragmented British industry was largely acquired by U.S. and Japanese multinational companies and became part of global value chains, but the development of mobile gaming and digital distribution provided opportunities for a new generation of start-ups to emerge in Britain.
Phase-only Fresnel holograms have two major advantages over complex-valued or amplitude-only hologram. First, they can be displayed with a single phase-only SLM, leading to simplification on the holographic display system. Second, due to the high optical efficiency of phase-only holograms, the reconstructed image is brighter than that of an amplitude-only hologram. On the downside, the fidelity of the reconstructed image is degraded as a result of discarding the magnitude component of the hologram. In this chapter, a number of methods, each with pros and cons, for generating phase-only holograms are described. These methods can be divided into two types, iterative and the non-iterative. Iterative methods include the iterative Fresnel transform algorithm (IFTA) and its variants, which find their origin in the classical Gerchberg–Saxton algorithm (GSA). Reconstructed images of a phase-only hologram obtained with IFTA are generally good in quality, but the computation time is rather lengthy. Another iterative method, based on direct binary search (DBS), can be applied in generating binary phase-only holograms. Non-iterative methods are based on modifying the source image in certain ways prior to the generation of the hologram. These include noise addition, patterned phase addition, and downsampling. The modification is similar to overlaying a diffuser onto the image, so that the magnitude of the diffracted waves on the hologram is close to homogeneous. The phase component alone, therefore, can be taken to represent the hologram.
In Chapter 3 a number of methods were described for generating a phase-only hologram of an object. However, these methods are not applicable if the source image of the object is not present, and only its hologram is available. Such a situation happens if a hologram is directly captured from a physical object (for example applying phase-shifting holography), instead of generated from a numerical graphic model. This chapter describes six methods for converting a complex-valued hologram into a phase-only hologram. The first two methods, complex amplitude modulation (CAM) and double-phase methods, convert a complex-valued hologram into a pure phase representation. When the latter is displayed on an SLM with suitable optical filtering, a visual 3-D image is reconstructed. The third to fifth methods apply different variants of the Floyd–Steinberg error diffusion algorithm to convert a complex-valued hologram into a continuous tone phase-only hologram. Among these three error diffusion methods, bi-directional error diffusion results in the best reconstructed image, while the local error diffusion method can be implemented with parallel computing devices such as GPUs. The last method, known as direct binary search (DBS), converts a complex-valued hologram into a binary phase-only hologram through an iterative process. The quality of the reconstructed image is generally poor unless more iterations are performed at the expense of longer computation time. A phase-only hologram generated by error diffusion or DBS can be displayed directly with a phase-only SLM without additional optical processing.
In this chapter, a number of quick methods for generating digital Fresnel holograms are introduced. For an object comprising a small number of depth planes, the layer-based method implemented in the Fourier space is preferred for fast hologram generation. The point-based method is more suitable for generating objects with a large number of object points that are scattered over a wide range of distances from the hologram plane. To enhance the speed of hologram generation with the point-based method, different variants and sizes of the look-up-table (LUT) algorithms to trade-off computation time are described. A number of methods based on the concept of a wavefront recording plane (WPR) are presented. Being different from the LUT approach, the WRP methods speed up the hologram-generation process. Instead of generating the full hologram for each object point, only a small area of fringe patterns is computed on a WRP that is at close proximity to the object space. The computation time is substantially reduced. Further enhancement of the computation speed is attained with the warped wavefront recording plane (WWRP) method. A 3-D object image is decomposed into a 2-D intensity image and a depth map. The intensity image is used to generate an interim hologram on a WRP. Different regions of the hologram fringes on the WRP are resized according to their distances (obtained from the depth map) from the hologram plane to generate a hologram from the WRP.
Digital holography has indeed led to numerous advancement of the classical, analog holographic technology that only permits a hologram to be permanently recorded onto a photographic film. In digital holography, a hologram can be captured from a real object. It can also be numerically generated as an array of numbers that can be stored as digital data, processed through computation, and distributed via digital communication links. In general, the primary purpose of holograms is to display 3-D images. Hence, a digital hologram in digital data form will not be of much practical use if it cannot be visually seen as a 3-D image. This is one of the major disadvantages of a digital hologram compared with the optical hologram, which can be readily captured with our eyes. However, a digital hologram can have different applications apart from generating 3-D images. In fact, recent research has shown that a digital hologram can be utilized in protecting sensitive data (a task referred to as cryptography), or in steganography for embedding large amount of additional data. This chapter describes some of the important applications of digital phase-only holograms in 3-D display, holographic cryptography, and steganography.
The fundamental principles of optical holography for capturing the optical waves of physical objects, and its difference from photography, are described. A photograph can only record a single view of an object scene; a hologram is capable of capturing the entire optical wavefront that impinges on it. There should be little difference between observing a hologram and the physical object scene. Numerical generation of digital holograms, commonly known as computer-generated holography (CGH), is presented. Two important approaches in CGH, the point-based and the layer-based methods, are described. The point-based method is suitable for generating holograms of simple objects with a small number of object points; the layer-based method is preferred for an object scene with a large number of object points concentrated in a few depth planes. The method for recovering a 3-D scene image from a digital hologram is provided. Three different methods for capturing digital holograms of physical object scene are described. The first method is similar to the art of optical holography, but instead of a photographic film, a digital camera is used to record the holographic waves emitted from the scene. As a digital camera can only record intensity information, the method can only be employed to capture an off-axis, amplitude-only hologram. The other two methods, known as phase-shifting holography (PSH) and optical scanning holography (OSH), are capable of capturing both the magnitude and phase components of the holographic signals. PSH is faster in operation, while OSH can be used to capture holograms of large objects. A simplified version of OSH, known as non-diffractive optical scanning holography (ND-OSH), is presented. ND-OSH is similar in principle to OSH, but the complexity of the optical and electronic setups is reduced.