| 1. |
- Al-Shishtawy, Ahmad, et al.
(författare)
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A design methodology for self-management in distributed environments
- 2009
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Ingår i: IEEE International conference on Computational Science and Engineering. - 9780769538235 ; , s. 430-436
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Konferensbidrag (refereegranskat)abstract
- Autonomic computing is a paradigm that aims at reducing administrative overhead by providing autonomic managers to make applications selfmanaging. In order to better deal with dynamic environments, for improved performance and scalability, we advocate for distribution of management functions among several cooperative managers that coordinate their activities in order to achieve management objectives. We present a methodology for designing the management part of a distributed self-managing application in a distributed manner. We define design steps, that includes partitioning of management functions and orchestration of multiple autonomic managers. We illustrate the proposed design methodology by applying it to design and development of a distributed storage service as a case study. The storage service prototype has been developed using the distributing component management system Niche. Distribution of autonomic managers allows distributing the management overhead and increased management performance due to concurrency and better locality.
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| 2. |
- Al-Shishtawy, Ahmad, 1978-, et al.
(författare)
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Distributed Control Loop Patterns for Managing Distributed Applications
- 2008
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Ingår i: SASOW 2008. - LOS ALAMITOS : IEEE Computer Society. - 9781424434688 ; , s. 260-265
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Konferensbidrag (refereegranskat)abstract
- In this paper we discuss various control loop patterns for managing distributed applications with multiple control loops. We introduce a high-level framework, called DCMS, for developing, deploying and managing component-based distributed applications in dynamic environments. The control loops, and interactions among them, are illustrated in the context of a distributed self-managing storage service implemented using DCMS to achieve various self-* properties. Different control loops are used for different self-* behaviours, which illustrates one way to divide application management, which makes for both ease of development and for better scalability and robustness when managers are distributed. As the multiple control loops are not completely independent, we demonstrate different patterns to deal with the interaction and potential conflict between multiple managers.
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| 3. |
- Al-Shishtawy, Ahmad, et al.
(författare)
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Enabling Self-Management Of Component Based Distributed Applications
- 2008
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Ingår i: FROM GRIDS TO SERVICE AND PERVASIVE COMPUTING. - Boston, MA : Springer-Verlag New York. - 9780387094557 ; , s. 163-174
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Konferensbidrag (refereegranskat)abstract
- Deploying and managing distributed applications in dynamic Grid environments requires a high degree of autonomous management. Programming autonomous management in turn requires programming environment support and higher level abstractions to become feasible. We present a framework for programming self-managing component-based distributed applications. The framework enables the separation of application’s functional and non-functional (self-*) parts. The framework extends the Fractal component model by the component group abstraction and one-to-any and one-to-all bindings between components and groups. The framework supports a network-transparent view of system architecture simplifying designing application self-* code. The framework provides a concise and expressive API for self-* code. The implementation of the framework relies on scalability and robustness of the Niche structured p2p overlay network. We have also developed a distributed file storage service to illustrate and evaluate our framework.
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| 4. |
- Al-Shishtawy, Ahmad, 1978-
(författare)
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Self-Management for Large-Scale Distributed Systems
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autonomic computing aims at making computing systems self-managing by using autonomic managers in order to reduce obstacles caused by management complexity. This thesis presents results of research on self-management for large-scale distributed systems. This research was motivated by the increasing complexity of computing systems and their management.In the first part, we present our platform, called Niche, for programming self-managing component-based distributed applications. In our work on Niche, we have faced and addressed the following four challenges in achieving self-management in a dynamic environment characterized by volatile resources and high churn: resource discovery, robust and efficient sensing and actuation, management bottleneck, and scale. We present results of our research on addressing the above challenges. Niche implements the autonomic computing architecture, proposed by IBM, in a fully decentralized way. Niche supports a network-transparent view of the system architecture simplifying the design of distributed self-management. Niche provides a concise and expressive API for self-management. The implementation of the platform relies on the scalability and robustness of structured overlay networks. We proceed by presenting a methodology for designing the management part of a distributed self-managing application. We define design steps that include partitioning of management functions and orchestration of multiple autonomic managers.In the second part, we discuss robustness of management and data consistency, which are necessary in a distributed system. Dealing with the effect of churn on management increases the complexity of the management logic and thus makes its development time consuming and error prone. We propose the abstraction of Robust Management Elements, which are able to heal themselves under continuous churn. Our approach is based on replicating a management element using finite state machine replication with a reconfigurable replica set. Our algorithm automates the reconfiguration (migration) of the replica set in order to tolerate continuous churn. For data consistency, we propose a majority-based distributed key-value store supporting multiple consistency levels that is based on a peer-to-peer network. The store enables the tradeoff between high availability and data consistency. Using majority allows avoiding potential drawbacks of a master-based consistency control, namely, a single-point of failure and a potential performance bottleneck.In the third part, we investigate self-management for Cloud-based storage systems with the focus on elasticity control using elements of control theory and machine learning. We have conducted research on a number of different designs of an elasticity controller, including a State-Space feedback controller and a controller that combines feedback and feedforward control. We describe our experience in designing an elasticity controller for a Cloud-based key-value store using state-space model that enables to trade-off performance for cost. We describe the steps in designing an elasticity controller. We continue by presenting the design and evaluation of ElastMan, an elasticity controller for Cloud-based elastic key-value stores that combines feedforward and feedback control.
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| 5. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 6. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
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Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
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Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 7. |
- Borgquist, Signe, et al.
(författare)
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Long-term exposure to insulin and volumetric mammographic density : Observational and genetic associations in the Karma study
- 2018
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Ingår i: Breast Cancer Research. - : Springer Science and Business Media LLC. - 1465-5411 .- 1465-542X. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Long-term insulin exposure has been implicated in breast cancer etiology, but epidemiological evidence remains inconclusive. The aims of this study were to investigate the association of insulin therapy with mammographic density (MD) as an intermediate phenotype for breast cancer and to assess associations with long-term elevated circulating insulin levels using a genetic score comprising 18 insulin-associated variants. Methods: We used data from the KARolinska MAmmography (Karma) project, a Swedish mammography screening cohort. Insulin-treated patients with type 1 (T1D, n = 122) and type 2 (T2D, n = 237) diabetes were identified through linkage with the Prescribed Drug Register and age-matched to 1771 women without diabetes. We assessed associations with treatment duration and insulin glargine use, and we further examined MD differences using non-insulin-treated T2D patients as an active comparator. MD was measured using a fully automated volumetric method, and analyses were adjusted for multiple potential confounders. Associations with the insulin genetic score were assessed in 9437 study participants without diabetes. Results: Compared with age-matched women without diabetes, insulin-treated T1D patients had greater percent dense (8.7% vs. 11.4%) and absolute dense volumes (59.7 vs. 64.7 cm3), and a smaller absolute nondense volume (615 vs. 491 cm3). Similar associations were observed for insulin-treated T2D, and estimates were not materially different in analyses comparing insulin-treated T2D patients with T2D patients receiving noninsulin glucose-lowering medication. In both T1D and T2D, the magnitude of the association with the absolute dense volume was highest for long-term insulin therapy (≥ 5 years) and the long-acting insulin analog glargine. No consistent evidence of differential associations by insulin treatment duration or type was found for percent dense and absolute nondense volumes. Genetically predicted insulin levels were positively associated with percent dense and absolute dense volumes, but not with the absolute nondense volume (percentage difference [95% CI] per 1-SD increase in insulin genetic score = 0.8 [0.0; 1.6], 0.9 [0.1; 1.8], and 0.1 [- 0.8; 0.9], respectively). Conclusions: The consistency in direction of association for insulin treatment and the insulin genetic score with the absolute dense volume suggest a causal influence of long-term increased insulin exposure on mammographic dense breast tissue.
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| 8. |
- Brand, Judith S, et al.
(författare)
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Chemotherapy, genetic susceptibility, and risk of venous thromboembolism in breast cancer patients
- 2016
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Ingår i: Clinical Cancer Research. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 1078-0432. ; 22:21, s. 5249-5255
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Venous thromboembolism (VTE) is highly heritable and a serious complication of cancer and its treatment. We examined the individual and joint effects of chemotherapy and genetic susceptibility on VTE risk in patients with breast cancer. Experimental design: A Swedish population-based study including 4,261 women diagnosed with primary invasive breast cancer between 2001 and 2008 in Stockholm, followed until 2012. Risk stratification by chemotherapy and genetic susceptibility [a polygenic risk score (PRS), including nine established VTE loci] was assessed using Kaplan-Meier and flexible parametric survival analyses, adjusting for patient, tumor, and treatment characteristics. Results: In total, 276 patients experienced a VTE event during a median follow-up of 7.6 years. Patients receiving chemotherapy [HR (95% CI) = 1.98; 1.40-2.80] and patients in the highest 5% of the PRS [HR (95% CI) = 1.90; 1.24-2.91] were at increased risk of developing VTE. Chemotherapy and PRS acted independently on VTE risk and the 1-year cumulative incidence in patients carrying both risk factors was 9.5% compared with 1.3% in patients not having these risk factors (P < 0.001). Stratified analyses by age showed that the risk-increasing effect of PRS was stronger in older patients (P interaction = 0.04), resulting in an excess risk among genetically susceptible patients receiving chemotherapy aged ≥ 60 years (1-year cumulative incidence = 25.0%). Conclusions: Risk stratification by chemotherapy and genetic susceptibility identifies patients with breast cancer at high VTE risk, who could potentially benefit from thromboprophylaxis. Our results further suggest that genetic testing is more informative in older patients with breast cancer.
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| 9. |
- Brand, Judith S, et al.
(författare)
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Infection-related hospitalizations in breast cancer patients : risk and impact on prognosis
- 2016
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Ingår i: Journal of Infection. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 0163-4453 .- 1532-2742.
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Infections are a common cause of hospitalization in breast cancer patients. We studied the risk, clinical characteristics and outcomes of infection-related hospitalizations in this patient population. METHODS: A Swedish registry-based study including 8338 breast cancer patients diagnosed between 2001 and 2008, followed prospectively for infection-related hospitalizations until 2010. Standardized incidence ratios (SIRs) were calculated using background rates from the general female population. Associations with clinical characteristics and mortality were analyzed using flexible parametric survival models. RESULTS: In total, 720 patients experienced an infection-related hospitalization during a median follow-up of 4.9 years. Infection rates were highest within the first year of diagnosis (SIR = 5.61, 95% CI; 4.98-6.32), and site-specific risks were most pronounced for sepsis (SIR = 3.14, 95% CI; 2.66-3.71) and skin infections (SIR = 2.80, 95% CI; 2.24-3.50). Older age at diagnosis, comorbidities, markers of tumor aggressiveness, chemotherapy and axillary node dissection were independent predictors of infectious disease risk. Infection-related hospitalizations were also independently associated with overall and breast cancer-specific death. CONCLUSIONS: A significant number of breast cancer patients are hospitalized with an infection following diagnosis, which in turn predicts poor prognosis. The risk profile of infection-related hospitalizations is multifactorial, including patient, tumor and treatment-related factors.
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| 10. |
- Brand, Judith S, et al.
(författare)
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Time-dependent risk and predictors of venous thromboembolism in breast cancer patients: a population-based cohort study
- 2016
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Ingår i: Cancer. - Stockholm : Karolinska Institutet, Dept of Medical Epidemiology and Biostatistics. - 0008-543X .- 1097-0142.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Venous thromboembolism (VTE) is a serious complication of cancer and its treatment. The current study assessed the risk and clinical predictors of VTE in breast cancer patients by time since diagnosis. METHODS: This Swedish population-based study included 8338 breast cancer patients diagnosed from 2001 to 2008 in the Stockholm-Gotland region with complete follow-up until 2012. Their incidence of VTE was compared with the incidence among 39,013 age-matched reference individuals from the general population. Cox and flexible parametric models were used to examine associations with patient, tumor, and treatment characteristics, accounting for time-dependent effects. RESULTS: Over a median follow-up of 7.2 years, 426 breast cancer patients experienced a VTE event (cumulative incidence, 5.1%). The VTE incidence was 3-fold increased (hazard ratio [HR], 3.28; 95% confidence interval [CI], 2.87-3.74) in comparison with the incidence in the general population and was highest 6 months after diagnosis (HR, 8.62; 95% CI, 6.56-11.33) with a sustained increase in risk thereafter (HR at 5 years, 2.19; 95% CI, 1.80-2.67). Independent predictors of VTE included the following: older age, being overweight, preexisting VTE, comorbid disease, tumor size > 40 mm, progesterone receptor (PR)-negative status, more than 4 affected lymph nodes, and receipt of chemo- and endocrine therapy. The impact of chemotherapy was limited to early-onset VTE, whereas comorbid disease and PR-negative status were more strongly associated with late-onset events. CONCLUSIONS: This study confirms the long-term risk of VTE in breast cancer patients and identifies a comprehensive set of clinical risk predictors. Temporal associations with patient, tumor, and treatment characteristics provide insight into the time-dependent etiology of VTE.
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