| 10261. |
- Eppe, Manfred, et al.
(författare)
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Approximate postdictive reasoning with answer set programming
- 2015
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Ingår i: Journal of Applied Logic. - : Elsevier. - 1570-8683 .- 1570-8691. ; 13:4, s. 676-719
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Tidskriftsartikel (refereegranskat)abstract
- We present an answer set programming realization of the h-approximation (HPX) theory [8] as an efficient and provably sound reasoning method for epistemic planning and projection problems that involve postdictive reasoning. The efficiency of HPX stems from an approximate knowledge state representation that involves only a linear number of state variables, as compared to an exponential number for theories that utilize a possible-worlds based semantics. This causes a relatively low computational complexity, i.e, the planning problem is in NP under reasonable restrictions, at the cost that HPX is incomplete. In this paper, we use the implementation of HPX to investigate the incompleteness issue and present an empirical evaluation of the solvable fragment and its performance. We find that the solvable fragment of HPX is indeed reasonable and fairly large: in average about 85% of the considered projection problem instances can be solved, compared to a PWS-based approach with exponential complexity as baseline. In addition to the empirical results, we demonstrate the manner in which HPX can be applied in a real robotic control task within a smart home, where our scenario illustrates the usefulness of postdictive reasoning to achieve error-tolerance by abnormality detection in a high-level decision-making task.
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| 10262. |
- Eppe, Manfred, et al.
(författare)
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h-approximation : History-Based Approximation of Possible World Semantics as ASP
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We propose a history-based approximation of the Possible Worlds Semantics (PWS) for reasoning about knowledge and action. A respective planning system is implemented by a transformation of the problem domain to an Answer-Set Program. The novelty of our approach is elaboration tolerant support for postdiction under the condition that the plan existence problem is still solvable in NP, as compared to ΣP2 for non-approximated PWS of Son and Baral [19]. We demonstrate our planner with standard problems and present its integration in a cognitive robotics framework for high-level control in a smart home.
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| 10263. |
- Eppe, Manfred, et al.
(författare)
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Narrative based Postdictive Reasoning for Cognitive Robotics
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Making sense of incomplete and conflicting narrative knowledge in the presence of abnormalities, unobservable processes, and other real world considerations is a challenge and crucial requirement for cognitive robotics systems. An added challenge, even when suitably specialised action languages and reasoning systems exist, is practical integration and application within large-scale robot control frameworks.In the backdrop of an autonomous wheelchair robot control task, we report on application-driven work to realise postdiction triggered abnormality detection and re-planning for real-time robot control: (a) Narrative-based knowledge about the environment is obtained via a larger smart environment framework; and (b) abnormalities are postdicted from stable-models of an answer-set program corresponding to the robot's epistemic model. The overall reasoning is performed in the context of an approximate epistemic action theory based planner implemented via a translation to answer-set programming.
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| 10264. |
- Epstein, Mara M, et al.
(författare)
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Dietary fatty acid intake and prostate cancer survival in Örebro county, Sweden
- 2012
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Ingår i: American Journal of Epidemiology. - : Oxford University Press (OUP). - 0002-9262 .- 1476-6256. ; 176:3, s. 240-252
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Tidskriftsartikel (refereegranskat)abstract
- Although dietary fat has been associated with prostate cancer risk, the association between specific fatty acids and prostate cancer survival remains unclear. Dietary intake of 14 fatty acids was analyzed in a population-based cohort of 525 Swedish men with prostate cancer in Örebro County (1989-1994). Multivariable hazard ratios and 95% confidence intervals for time to prostate cancer death by quartile and per standard deviation increase in intake were estimated by Cox proportional hazards regression. Additional models examined the association by stage at diagnosis (localized: T0-T2/M0; advanced: T0-T4/M1, T3-T4/M0). Among all men, those with the highest omega-3 docosahexaenoic acid and total marine fatty acid intakes were 40% less likely to die from prostate cancer (P(trend) = 0.05 and 0.04, respectively). Among men with localized prostate cancer, hazard ratios of 2.07 (95% confidence interval: 0.93, 4.59; P(trend) = 0.03) for elevated total fat, 2.39 (95% confidence interval: 1.06, 5.38) for saturated myristic acid, and 2.88 (95% confidence interval: 1.24, 6.67) for shorter chain (C4-C10) fatty acid intakes demonstrated increased risk for disease-specific mortality for the highest quartile compared with the lowest quartile. This study suggests that high intake of total fat and certain saturated fatty acids may worsen prostate cancer survival, particularly among men with localized disease. In contrast, high marine omega-3 fatty acid intake may improve disease-specific survival for all men.
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| 10265. |
- Epstein, Mara M., et al.
(författare)
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Dietary zinc and prostate cancer survival in a Swedish cohort
- 2011
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 93:3, s. 586-593
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Tidskriftsartikel (refereegranskat)abstract
- Background: Zinc is involved in many essential cellular functions, including DNA repair and immune system maintenance. Although experimental evidence supports a role for zinc in prostate carcinogenesis, epidemiologic data are inconsistent; no data on cancer-specific survival have been reported. Objective: Our objective was to determine whether dietary zinc assessed near the time of prostate cancer diagnosis is associated with improved disease-specific survival. Design: This population-based cohort consists of 525 men aged < 80 y from Orebro County, Sweden, with a diagnosis of prostate cancer made between 1989 and 1994. Study participants completed self-administered food-frequency questionnaires, and zinc intake was derived from nutrient databases. Cox proportional hazards regression was used to estimate multivariate hazard ratios (HRs) and 95% CIs for time to death from prostate cancer as well as death from all causes through February 2009 by quartile (Q) of dietary zinc intake. Models were also stratified by disease stage at diagnosis (localized or advanced). Results: With a median follow-up of 6.4 y, 218 (42%) men died of prostate cancer and 257 (49%) died of other causes. High dietary zinc intake was associated with a reduced risk of prostate cancer-specific mortality (HRQ4 vs Q1: 0.64; 95% CI: 0.44, 0.94; P for trend = 0.05) in the study population. The association was stronger in men with localized tumors (HR: 0.24; 95% CI: 0.09, 0.66; P for trend = 0.005). Zinc intake was not associated with mortality from other causes. Conclusion: These results suggest that high dietary intake of zinc is associated with lower prostate cancer-specific mortality after diagnosis, particularly in men with localized disease.
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| 10266. |
- Epstein, Mara M, et al.
(författare)
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Seasonal variation in expression of markers in the vitamin D pathway in prostate tissue
- 2012
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Ingår i: Cancer Causes and Control. - : Springer. - 0957-5243 .- 1573-7225. ; 23:8, s. 1359-1366
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Recent studies suggest variation in genes along the vitamin D pathway, as well as vitamin D receptor (VDR) protein levels, may be associated with prostate cancer. As serum vitamin D levels vary by season, we sought to determine whether the expression of genes on the vitamin D pathway, assessed in prostate tumor tissue, do the same.METHODS: Our study incorporates mRNA expression data from 362 men in the Swedish Watchful Waiting cohort, diagnosed between 1977 and 1999, and 106 men enrolled in the US Physicians' Health Study (PHS) diagnosed between 1983 and 2004. We also assayed for VDR protein expression among 832 men in the PHS and Health Professionals Follow-up Study cohorts. Season was characterized by date of initial tissue specimen collection categorically and by average monthly ultraviolet radiation levels. One-way analysis of variance was used to examine variation in the expression levels of six genes on the vitamin D pathway-VDR, GC, CYP27A1, CYP27B1, RXRα, CYP24A1-and VDR protein by season, adjusted for age at diagnosis and Gleason grade. Variation was also examined separately among lethal and nonlethal cases.RESULTS: Tumor expression levels of the six genes did not vary significantly by season of tissue collection. No consistent patterns emerged from subgroup analyses by lethal versus nonlethal cases.CONCLUSIONS: Unlike circulating levels of 25(OH) vitamin D, expression levels of genes on the vitamin D pathway and VDR protein did not vary overall by season of tissue collection. Epidemiological analyses of vitamin D gene expression may not be biased by seasonality.
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| 10267. |
- Erbes, C. R., et al.
(författare)
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Characterizing spouse/partner depression and alcohol problems over the course of military deployment
- 2017
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Ingår i: Journal of Consulting and Clinical Psychology. - Washington : American Psychological Association (APA). - 0022-006X .- 1939-2117. ; 85:4, s. 297-308
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Spouse/partners of military personnel demonstrate elevated levels of distress during military deployments, yet there is insufficient information about courses of adjustment over time. The current study identified trajectories of depression and alcohol use problems and predictors of those trajectories across the deployment cycle.Method: National Guard soldiers (N = 1973) and spouses/intimate partners (N = 1020) completed assessments of risk/protective factors and baseline measures of mental health functioning 2 to 5 months prior to soldiers' 1-year deployments (Time 1) to Kuwait/Iraq in support of Operation New Dawn or Afghanistan in support of Operation Enduring Freedom. Partners' mental health was reassessed at 4 months (Time 2) and 8 months (Time 3) after soldiers deployed, and both spouses/partners and soldiers were reassessed 2-3 months postdeployment (Time 4).Results: Latent class growth modeling of partner depression symptoms over time revealed 4 groups: Resilience (79.9%), Deployment Distress (8.9%), Anticipatory Distress (8.4%), and Post-Deployment Distress (2.7%). Three alcohol misuse trajectories were identified: Resilience (91.3%), Deployment Onset (5.4%), and Deployment Desistance (3.3%). Predeployment predictors of partners' depression symptom trajectories varied by group and included soldier reports of stressors and social support and partner levels of neuroticism, introversion, disconstraint, and reported stressors. Predeployment predictors of alcohol misuse trajectories varied by group, and included soldier levels of alcohol misuse as well as partner neuroticism, disconstraint, and family readiness.Conclusions: Delineating and predicting trajectories of partner adjustment can allow for better targeted interventions toward those most at risk for heightened distress or alcohol problems over the deployment cycle.
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| 10268. |
- Erdtman, Edvin, 1981-
(författare)
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5-Aminolevulinic acid and derivatives thereof : properties, lipid permeability and enzymatic reactions
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 5-aminolevulinic acid (5-ALA) and derivatives thereof are widely usedprodrugs in treatment of pre-malignant skin diseases of the cancer treatmentmethod photodynamic therapy (PDT). The target molecule in 5-ALAPDTis protoporphyrin IX (PpIX), which is synthesized endogenously from5-ALA via the heme pathway in the cell. This thesis is focused on 5-ALA,which is studied in different perspectives and with a variety of computationalmethods. The structural and energetic properties of 5-ALA, itsmethyl-, ethyl- and hexyl esters, four different 5-ALA enols, and hydrated5-ALA have been investigated using Quantum Mechanical (QM) first principlesdensity functional theory (DFT) calculations. 5-ALA is found to bemore stable than its isomers and the hydrolysations of the esters are morespontaneous for longer 5-ALA ester chains than shorter. The keto-enoltautomerization mechanism of 5-ALA has been studied, and a self-catalysismechanism has been proposed to be the most probable. Molecular Dynamics(MD) simulations of a lipid bilayer have been performed to study themembrane permeability of 5-ALA and its esters. The methyl ester of 5-ALAwas found to have the highest permeability constant (PMe-5-ALA = 52.8 cm/s).The mechanism of the two heme pathway enzymes; Porphobilinogen synthase(PBGS) and Uroporphyrinogen III decarboxylase (UROD), have beenstudied by DFT calculations and QM/MM methodology. The rate-limitingstep is found to have a barrier of 19.4 kcal/mol for PBGS and 13.7kcal/mol for the first decarboxylation step in UROD. Generally, the resultsare in good agreement with experimental results available to date.
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| 10269. |
- Erdtman, Edvin, 1981-
(författare)
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A theoretical study of 5-Aminolevulinic acid and its esters : properties and lipid permeability
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 5-aminolevulinic acid (5ALA) is a widely used prodrug in Photodynamic therapy (PDT). The target molecule in 5ALA-PDT is Protoporphyrin IX (PpIX), which is synthesized endogenously via the heme pathway in the cell. In this thesis; the structural and energetic properties of 5ALA, its methyl-, ethyl- and hexyl esters, four different 5ALA enols, and hydrated 5ALA have been investigated using Quantum Mechanical (QM) first principles calculations. The vacuum proton affinity (PA) of 5ALA is found to be in good agreement with other similar compounds. The keto-enol tautomerization mechanism of 5ALA has been studied, and a self-catalysis mechanism has been proposed to be the most probable. Molecular Dynamics (MD) simulations of a lipid bilayer have been performed to study the membrane permeability of 5ALA and its esters. In the simulations the molecules were inserted in the middle of the membrane, equilibrated, and then simulated in 20 ns. It has been found that there are some differences in penetration between the molecules studied. The methyl ester of 5ALA is diverging from the others by having its barrier not in the middle of the membrane, as the others have.
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| 10270. |
- Erdtman, Edvin, et al.
(författare)
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Computational insights into the mechanism of porphobilinogen synthase
- 2010
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Ingår i: Journal of Physical Chemistry B. - Washington : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 114:50, s. 16860-16870
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Tidskriftsartikel (refereegranskat)abstract
- Porphobilinogen synthase (PBGS) is a key enzyme in heme biosynthesis that catalyzes the formation of porphobilinogen (PBG) from two 5-aminolevulinic acid (5-ALA) molecules via formation of intersubstrateC-N and C-C bonds. The active site consists of several invariant residues, including two lysyl residues (Lys210 and Lys263; yeast numbering) that bind the two substrate moieties as Schiff bases. Based on experimental studies, various reaction mechanisms have been proposed for this enzyme that generally can be classified according to whether the intersubstrate C-C or C-N bond is formed first. However, the detailed catalytic mechanism of PBGS remains unclear. In the present study, we have employed density functional theory methods in combination with chemical models of the two key lysyl residues and two substrate moieties in order to investigate various proposed reaction steps and gain insight into the mechanism of PBGS. Importantly, it is found that mechanisms in which the intersubstrate C-N bond is formed first have a ratelimiting barrier (17.5 kcal/mol) that is lower than those in which the intersubstrate C-C bond is formed first (22.8 kcal/mol).
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