On the design of a real-time volume rendering engine

An architecture for a Real-Time Volume Rendering Engine (RT-VRE) is given, capable of computing 750 × 750 × 512 samples from a 3D dataset at a rate of 25 images per second. The RT-VRE uses for this purpose 64 dedicated rendering chips, cooperating with 16 RISC-processors. A plane interpolator circuit and a composition circuit, both capable to operate at very high speeds, have been designed for a 1.6 micron VLSI process. Both the interpolator and composition circuit are back from production. They have been tested and both complied with our specifications

Suicide prevention:investigating novel ways to improve suicide prevention strategies

This dissertation explored the effectiveness of an add-on module called Eye Movement Dual Task (EMDT) for treating intrusive suicide-related imagery, investigated identifying high-risk groups prone to suicide, and explored the experimental approach of intrusive memories and dual tasks. Chapter 1 provides a general introduction and highlights the global impact, prevalence rates, and demographic patterns of suicide. It explores at-risk populations, specific risk factors, intrusive suicidal mental imagery, and the challenges in predicting suicide. Chapter 2 investigates a risk marker that seems a new phenomenon – suicidal mental imagery. We describe theoretical approaches for suicide ideation and suicidal behavior and propose a model of suicidal intrusions by describing one of the assumed mechanisms in the etiology of suicide. Chapter 3 describes the initial stages of translating known experimental approaches (eye movements and dual tasks) to a clinical setting. This pilot study (N=6) aimed to evaluate the safety, tolerability, and feasibility of the EMDT add-on treatment based on Eye Movement Desensitization and Reprocessing (EMDR) but with omission of the installation of the positive cognition phase. Chapter 4 describes the study protocol of the Simagery project. This paper described the trial procedures for adding an EMDT intervention to regular treatment that may reduce the frequency and vividness of suicidal imagery. Chapter 5 describes the development of a new instrument (Suicidal Intrusions Attributes Scale; SINAS) to assess the severity and characteristics of suicidal intrusions and examines its psychometric properties. The brief SINAS measures six attributes of suicidal intrusions: frequency, controllability, closeness to a suicide attempt, distress/vividness, and compulsiveness. Chapter 6 includes results of a multi-center RCT on the efficacy of the EMDT add-on module. Adult suicidal psychiatric outpatients (N=91) with depressive symptoms were recruited across eight mental health institutions in the Netherlands. The primary outcome was severity (SINAS) and frequency (Clinical Interview for Suicidal Intrusions; CISI) of suicidal intrusions at 1-week posttreatment and 3-month follow-up. Secondary outcomes included suicidal ideation, depressive symptoms, hopelessness, and rumination. Chapter 7 focuses on one specific risk group, namely individuals with autism. Our study explores incidence rates of lifetime suicidality and suicidal ideation in the past month in a Dutch cohort (Netherlands Autism Register) of autistic adults, and particular risk factors associated with suicidality in autism. Chapter 8 continues to evaluate the components and characteristics of suicidal intrusions. Our study aimed to investigate the association between the subscales of childhood maltreatment (i.e., physical abuse and neglect, emotional abuse and neglect, and sexual abuse) and the occurrence of suicidal intrusions taking age, gender, posttraumatic stress disorder (PTSD) diagnosis and depressive symptoms into account. Chapter 9 examined the impact of two depression treatments, cognitive therapy (CT) and interpersonal therapy (IPT) on suicidal ideation using data from a previously conducted single-center RCT (Step-D). We used time-lagged mixed-effects models to evaluate the influence of depression treatment on suicidal ideation, and examine the temporal relationship between depressive symptoms and suicidal ideation during each therapy session. Chapter 10 describes a meta-analysis exploring the efficacy of cognitive interventions, including eye movements, in lab settings to reduce intrusive memories. We evaluated the efficacy of cognitive interventions compared to control in reducing intrusion frequency and PTSD symptoms in healthy individuals using the Trauma Film Paradigm. In chapter 11, we developed an Intrusion Film Paradigm (similar to Trauma Film Paradigm) that induced fleeting/temporary suicide-related intrusions. The chapter proceeds to evaluate the impact of eye movements to reduce the vividness and emotionality of suicide-related images in a healthy student sample. Chapter 12 concludes this dissertation and provides an overview of the empirical findings in this dissertation and discuss theoretical, methodological, and clinical implications for suicide prevention research and treatment strategies

Low pressure buried pipe distribution systems for surface irrigation

Findings of research work into the use of buried pipe distribution systems for surface irrigation are detailed, based on a literature review, field evaluation of existing systems in south Asia and field work on existing buried pipe systems in Bangladesh. The extent and history of the use of buried pipe distribution systems is detailed in chapter two, along with trends in the upgrading and development of buried pipe systems. The comparative performance of buried pipe systems and open channel alternatives is discussed. Measurable benefits from buried pipe systems include reductions in seepage losses and a lower land take by the distribution system. Systems which are lower in cost than most lined channels are documented for some south Asian systems. Although low pressure pipe systems vary widely in design they can be classified as open, closed or semi-closed with regard to the method of pressure control, and as gravity or pumped supply with regard to the source of the driving head. These definitions along with consideration of the methods of regulating pipe distribution systems and the choice of the operating and control system, form part of the framework and classification for buried pipe systems presented in chapter three. Pipe systems in India, Bangladesh and Thailand, visited as part of the research work, are described and evaluated within the individual case studies set out in chapter four, along with summaries of the standard features of each of the pipe systems. [Continues.

A novel astronomical application for formation flying small satellites

OLFAR, Orbiting Low Frequency Antennas for Radio Astronomy, will be a space mission to observe the universe frequencies below 30 MHz, as it was never done before with an orbiting telescope. Because of the ionospheric scintillations below 30 MHz and the opaqueness of the ionosphere below 15 MHz, a space mission is the only opportunity for this as yet unexplored frequency range in radio astronomy. The frequency band is scientifically very interesting for exploring the early cosmos at high hydrogen redshifts, the so-called dark-ages and the epoch of reionization, the discovery of planetary and solar bursts in other solar systems, for obtaining a tomographic view of space weather, ultra-high energy cosmic rays and for many other astronomical areas of interest. Because of the low observing frequency the aperture size of the instrument must be in the order of 100 km. This requires a distributed space mission which is proposed to be implemented using formation flying of small satellites. The individual satellites are broken down in five major subsystems: the spacecraft bus, the antenna design, the frontend, backend and data transport. One of the largest challenges is the inter-satellite communication. In this paper the concept and design considerations of OLFAR are presented

Daris, a low-frequency distributed aperture array for radio astronomy in space

DARIS (Distributed Aperture Array for Radio Astronomy in Space) is a radio astronomy space mission concept aimed at observing the low-frequency radio sky in the range 1-10 MHz. Because of the Earth's ionospheric disturbances and opaqueness, this frequency range can only be observed from space. The astronomical science cases include sensitive extragalactic surveys, radio transients such as Jupiter-like burst and Crab-like pulses, and coronal mass ejection tracking. The focus of the DARIS concept study is on feasibility aspects of a distributed aperture synthesis array in space, consisting of small satellite nodes and a mother-ship. The study selected suitable science cases, antenna concepts, communications, signal processing, orbital design, and mission analysis. With current-day technologies a satellite cluster can be built consisting of at least eight satellite nodes and a mother-ship, which could be launched with a Soyuz rocket from Kourou. Such a satellite cluster would open up the last unexplored frequency range for astronomy