7,711 research outputs found

    Automated Adaptive Intrusion Containment in Systems of Interacting Services

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    Large scale distributed systems typically have interactions among different services that create an avenue for propagation of a failure from one service to another. The failures being considered may be the result of natural failures or malicious activity, collectively called disruptions. To make these systems tolerant to failures it is necessary to contain the spread of the occurrence automatically once it is detected. The objective is to allow certain parts of the system to continue to provide partial functionality in the system in the face of failures. Real world situations impose several constraints on the design of such a disruption tolerant system of which we consider the following - the alarms may have type I or type II errors; it may not be possible to change the service itself even though the interaction may be changed; attacks may use steps that are not anticipated a priori; and there may be bursts of concurrent alarms. We present the design and implementation of a system named ADEPTS as the realization of such a disruption tolerant system. ADEPTS uses a directed graph representation to model the spread of the failure through the system, presents algorithms for determining appropriate responses and monitoring their effectiveness, and quantifies the effect of disruptions through a high level survivability metric. ADEPTS is demonstrated on a real e-commerce testbed with actual attack patterns injected into it

    An efficient surrogate model for emulation and physics extraction of large eddy simulations

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    In the quest for advanced propulsion and power-generation systems, high-fidelity simulations are too computationally expensive to survey the desired design space, and a new design methodology is needed that combines engineering physics, computer simulations and statistical modeling. In this paper, we propose a new surrogate model that provides efficient prediction and uncertainty quantification of turbulent flows in swirl injectors with varying geometries, devices commonly used in many engineering applications. The novelty of the proposed method lies in the incorporation of known physical properties of the fluid flow as {simplifying assumptions} for the statistical model. In view of the massive simulation data at hand, which is on the order of hundreds of gigabytes, these assumptions allow for accurate flow predictions in around an hour of computation time. To contrast, existing flow emulators which forgo such simplications may require more computation time for training and prediction than is needed for conducting the simulation itself. Moreover, by accounting for coupling mechanisms between flow variables, the proposed model can jointly reduce prediction uncertainty and extract useful flow physics, which can then be used to guide further investigations.Comment: Submitted to JASA A&C

    THE EFFECTS OF EXTERNAL LOAD ON LOWER EXTREMiTY ELECTROMYOGRAPHY AMPLITUDE DURING COUNTERMOVEMENT JUMP

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    The purpose of this study was to investigate the effects of different loads on the mean electromyography (EMG) amplitude of the gluteus maximus, biceps fernoris, vastus medialis, gastrocnemius, soleus, and tibialis anterior during the deceleration phase and the acceleration phase of the countermovement jumps (CMJ). Ten male physical education students performed different CMJs with and without an external load (0,2.5,5.0, 7.5, or 10.0 kg hold in arms). The results s h o w the amplitude of the gluteus maximus with load of 7.5 kg was higher than with load of 2.5 kg during the deceleration phase (p < .05), and the amplitude of the soleus with load of 10.0 kg was higher than with load of 2.5 kg during the acceleration phase (p < .05). It indicated that the activities of lower limb muscles were not influenced by the relative lower of external loading during CMJ

    Beyond the Innovation: An Exploratory Study of Designing Web-based Self-services

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    AbstractCustomized web-based self-services play an important role in today's product/service innovation. Compared to traditional tangible services, helpful web-based self-services and off-line services may better facilitate creativity, accelerate value co-creation, and reduce the costs and risks of development and commercialization. Therefore, in order to offer a conceptual framework for a web-based self-service system that enhances the fuzzy-front end (FFE) of new product/service development, this study analyzed the needs and challenges found during the transition of the Dechnology (Design Thinking plus Technology Innovation) project at the Industrial Technology Research Institute (ITRI), the largest R&D organization in Taiwan. Through literature review, in-depth interviews, and participatory action research, we formalized five core system modules, including: 1) user behavior and lifestyle, 2) thematic trend analysis, 3) technology screening and translation, 4) idea visualization, and 5) O2O service connection, with corresponding design principles for supporting user creativity in a web-based self-services environment. Finally, this study proposes a conceptual framework integrated with service design to serve as an important reference for enterprises that undergo similar innovation projects in the future

    Enhanced Osteogenesis of Adipose-Derived Stem Cells by Regulating Bone Morphogenetic Protein Signaling Antagonists and Agonists.

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    UnlabelledAlthough adipose-derived stem cells (ASCs) are an attractive cell source for bone tissue engineering, direct use of ASCs alone has had limited success in the treatment of large bone defects. Although bone morphogenetic proteins (BMPs) are believed to be the most potent osteoinductive factors to promote osteogenic differentiation of ASCs, their clinical applications require supraphysiological dosage, leading to high medical burden and adverse side effects. In the present study, we demonstrated an alternative approach that can effectively complement the BMP activity to maximize the osteogenesis of ASCs without exogenous application of BMPs by regulating levels of antagonists and agonists to BMP signaling. Treatment of ASCs with the amiloride derivative phenamil, a positive regulator of BMP signaling, combined with gene manipulation to suppress the BMP antagonist noggin, significantly enhanced osteogenic differentiation of ASCs through increased BMP-Smad signaling in vitro. Furthermore, the combination approach of noggin suppression and phenamil stimulation enhanced the BMP signaling and bone repair in a mouse calvarial defect model by adding noggin knockdown ASCs to apatite-coated poly(lactic-coglycolic acid) scaffolds loaded with phenamil. These results suggest novel complementary osteoinductive strategies that could maximize activity of the BMP pathway in ASC bone repair while reducing potential adverse effects of current BMP-based therapeutics.SignificanceAlthough stem cell-based tissue engineering strategy offers a promising alternative to repair damaged bone, direct use of stem cells alone is not adequate for challenging healing environments such as in large bone defects. This study demonstrates a novel strategy to maximize bone formation pathways in osteogenic differentiation of mesenchymal stem cells and functional bone formation by combining gene manipulation with a small molecule activator toward osteogenesis. The findings indicate promising stem cell-based therapy for treating bone defects that can effectively complement or replace current osteoinductive therapeutics

    Missing link in community psychiatry: When a patient with schizophrenia was expelled from her home

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    Treatment and disposition of homeless patients with schizophrenia represent a great challenge in clinical practice. We report a case of this special population, and discuss the development of homelessness, the difficulty in disposition, their utilization of health services, and possible applications of mandatory community treatment in this group of patients. A 51-year-old homeless female was brought to an emergency department for left femur fracture caused by an assault. She was diagnosed with schizophrenia about 20 years ago but received little help from mental health services over the decades. During hospitalization, her psychotic symptoms were only partially responsive to treatment. Her family refused to handle caretaking duties. The social welfare system was mobilized for long-term disposition. Homeless patients with schizophrenia are characterized by family disruption, poor adherence to health care, and multiple emergency visits and hospitalization. We hope this article can provide information about the current mental health policy to medical personnel. It is possible that earlier intervention and better outcome can be achieved by utilizing mandatory community treatment in the future, as well as preventing patients with schizophrenia from losing shelters
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