780 research outputs found
Dynamix on the Frame VM: Declarative dynamic semantics on a VM using scopes as frames
No full textOver the years virtual machines (VMs) have been created to abstract over computer hardware. This simplified code generation and allowed for easy portability between hardware platforms. These VMs are however highly tailored to a particular runtime model. This improves the execution speed, but places restrictions on the types of languages that the VM supports. In this thesis the Frame VM was developed as a VM that supports many different types of languages in a principled way. Achieving this is done by basing the VM on language independent models of memory and control flow. Usage of the scopes-as-frames paradigm and control frames resulted in an instruction set that is relatively small at its core, but does allow for the construction of complex control flow. As an effect, many different programming languages can be compiled to the Frame VM. In addition to this VM, a Domain Specific Language (DSL) for executable semantics of programming languages was created. This language, Dynamix, allows for a modular approach to writing the semantics of a language. Additionally, Dynamix provides a meta-compiler that uses these semantics of a language to compile programs to the Frame VM. To validate the Frame VM, direct compilers for Rust and Prolog have been created in a student project and compilers for Scheme and Tiger were created using Dynamix. Using these semantics of Scheme and Tiger, it was possible to execute programs containing usage of call/cc and a suite of Tiger benchmark programs. Furthermore, the control flow of Tiger was extended with exceptions and generator functions. This extension did not require any changes to the existing semantics, showing the modularity of control achieved when using Dynamix and the Frame VM.Computer Scienc
The Predictive Effects of Resting-State and Task-Related Prefrontal and Vagal Activity on Cognitive Performances
No full textPerformance efficiency in cognitive tasks is a combination of effectiveness, that is, accuracy, and cognitive effort. Resting-state and task-related autonomic and cortical activity, together with psychological variables, may represent effective predictors of performance efficiency. This study aimed to investigate the impact of these variables in the prediction of performance during a set of cognitive tasks in a sample of young adults. The 76 participants (age: 23.96 +/- 2.69 years; 51.3% females) who volunteered for this study completed several psychological questionnaires and performed a set of attention and executive functions tasks. Resting-state and task-related prefrontal and autonomic activity were collected through a Time-Domain and a Continuous Wave 2-channel Functional Near-Infrared Spectroscopy (fNIRS) and a portable Electrocardiogram (ECG) monitoring system, respectively. A set of Machine Learning (ML) approaches were employed to (i) predict the performance of each cognitive task, while minimizing and quantifying the prediction error, and to (ii) quantitatively evaluate the predictors that most affected the cognitive outcome. Results showed that perfectionistic traits, as well as both resting-state and task-related autonomic and cortical activity, predicted performance for most of the tasks, partially supporting previous evidence. Our results add to the knowledge of psycho-physiological determinants of performance efficiency in cognitive tasks and provide preliminary evidence on the role of ML approaches in detecting important predictors in cognitive neuroscience
Interference and conflict monitoring in individuals with anmestic mild cognitive impairment: A structural stuudy of the anterior cingulate cortex
No full textAmnestic mild cognitive impairment (aMCI) is a clinical condition characterized by memory impairment in the absence of any other cognitive impairment and is commonly associated with high conversion to Alzheimer's disease. Recent evidence shows that executive functions and selective attention mechanisms could also be impaired in aMCI. In this study, we investigated performance differences (i.e., reaction times [RTs] and accuracy) between a group of aMCI participants and a group of age-matched healthy individuals on the attentional network task (ANT) focusing on situations with increased interference. In particular, we assessed the relationship between interference and conflict effects and grey matter volumes (GMVs) of the anterior cingulate cortex (ACC)/pre-supplementary motor area in the entire sample because of its crucial role in conflict monitoring. When compared with controls, aMCI participants were less accurate on the ANT, showing increased interference and conflict effects, but no differences in RTs. In addition, aMCI participants exhibited lower GMV in the ACC than controls. While better accuracy for interference and conflict effects was associated with an increase of GMV in the ACC for both groups, RTs from the interference effect were negatively correlated with GMV of the ACC only in aMCI participants. In other words, lower GMV values of the ACC were paralleled with significantly impaired performance in terms of interference resolution. In conclusion, our study suggests the presence of a selective impairment in interference and conflict monitoring in aMCI, which in turn is associated with decreased GMVs in the ACC
Functional correlates of preserved naming performance in amnestic Mild Cognitive Impairment
No full textMIME Configurations for Using VM on Emacs
No full textP(論文)Emacsは単なる文書編集アプリケーションではなく、様々な機能をマクロとして附加することができる。本稿では、このEmacsでメールを読み書きするための追加マクロとしてVMを取り上げる。VMでは電子メール本文におけるMIME対応はなされているが、ヘッダにおけるMIME対応はなされていない。本稿では、VMからSEMIを利用し、電子メールヘッダに日本語を利用するためのMIME設定について述べる。当初の目的であるEmacsとVMによる電子メールヘッダにおける日本語のMIME処理は実現できた。ただし、Emacsの版によってはうまく実現できないという情報もある。汎用的な方法を確立するためには、更なる調査が必要である。Emacs is an application software that can be used not only for editing plain texts but also for many other purposes by adding facilities as macros. In this study, VM was used as auxiliary macro for reading and writing e-mails by Emacs. VM has MIME reading and writing ability in the body part of e-mail messages but not in the header part. In this paper, MIME configurations for using SEMI from VM for processingJapanese characters in e-mail headers are described. The goal of this study, i.e., reading and writing MIME messages in header parts, was achieved. However, the author has information that the method described in this paper does not work well with one version of Emacs (Emacs 22). Establishment of a general method is a subject of future work.departmental bulletin pape
Flow compensation in a MEMS dual-thermal conductivity detector for hydrogen sensing in natural gas
No full textConventional thermal conductivity detectors (TCDs) demonstrate a flow dependence. The approach presented here to reduce the flow dependence is based on the on-line flow compensation using two thin-film sensors on membranes in parallel on the same chip that are differentially operated. These are laterally identically, but with a different depth of the detection chamber, resulting in different quasi-static sensitivities to the thermal conductivity of the sample gas. The effects of conduction and convection in the structure have been studied using COMSOL Multiphysics. First prototypes have been fabricated and are presently tested.Accepted Author ManuscriptElectronic Instrumentatio
Who creates the narrative? The case of RE/F/r:ACE, a participatory media artwork in city space
No full textThis paper discusses the roles of artist, author, participant and spectator within the context of participatory media art events, with reference to RE/F/r.ACE, a participatory video project developed by Andy Best-Dunkley, Merja Puustinen and Victor Khachtchanski. RE/F/r.ACE enables participants to easily contribute their own images as raw material to the ongoing flow of visual and audio narrative projected into the public city environment. Situating the project within an art historical context, the paper discusses the social and political coding of the architectonic urban environment, and the rules and norms relating to, and controlling, our everyday use of public space. When the notion of free “open to all” public space is under threat from ongoing commercialisation and gentrification of urban centres worldwide, RE/F/r.ACE is an example of one attempt to draw attention to this transformation in a creative, positive, and artistic manner.Peer reviewe
Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance
No full textBackground: Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined. Objectives: The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR). Methods: A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes. Results: In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation. Conclusions: Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.ImPhys/Tao grou
Evaluation of SLA-based decision strategies for VM scheduling in cloud data centers
No full textCopyright © 2016 held by owner/author(s). Service level agreements (SLAs) gain more and more importance in the area of cloud computing. An SLA is a contract between a customer and a cloud service provider (CSP) in which the CSP guarantees functional and non-functional quality of service parameters for cloud services. Since CSPs have to pay for the hardware used as well as penalties for violating SLAs, they are eager to fulfill these agreements while at the same time optimizing the utilization of their resources. In this paper we examine SLA-aware VM scheduling strategies for cloud data centers. The service level objectives considered are resource usage and availability. The sample resources are CPU and RAM. They can be overprovisioned by the CSPs which is the main leverage to increase their revenue. The availability of a VM is affected by migrating it within and between data centers. To get realistic results, we simulate the effect of the strategies using the FederatedCloudSim framework and real-world workload traces of business-critical VMs. Our evaluation shows that there are considerable differences between the scheduling strategies in terms of SLA violations and the number of migrations. From all strategies considered, the combination of the Minimization of Migrations strategy for VM selection and the Worst Fit strategy for host selection achieves the best results
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