1,427 research outputs found
Do activity monitors increase physical activity in adults with overweight or obesity? A systematic review and meta-analysis
Objective: To systematically assess contemporary knowledge regarding behavioral physical activity interventions including an activity monitor (BPAI+) in adults with overweight or obesity. Methods: PubMed/MEDLINE, Embase, CINAHL, PsycINFO, CENTRAL and PEDro were searched for eligible full text articles up to July 1st 2015. Studies eligible for inclusion were (randomized) controlled trials describing physical activity outcomes in adults with overweight or obesity. Methodological quality was independently assessed employing the Cochrane Collaboration's tool for risk of bias. PROSPERO registration: CRD42015024086. Results: Fourteen studies (1157 participants) were included for systematic review and eleven for meta-analysis. A positive trend in BPAI+ effects on several measures of physical activity was ascertained compared to both waitlist or usual care (WL/UC) and behavioral physical activity interventions without an activity monitor (BPAI-). No convincing evidence of BPAI+ effectiveness on weight loss was found compared to BPAI-. Conclusions: Behavioral physical activity interventions with an activity monitor increase physical activity in adults with overweight or obesity. Also, adding an activity monitor to behavioral physical activity interventions appears to increase the effect on physical activity, although current evidence has not yet provided conclusive evidence for its effectiveness
A priori model independent inverse potential mapping: the impact of electrode positioning
__Introduction:__ In inverse potential mapping, local epicardial potentials are computed from recorded body surface potentials (BSP). When BSP are recorded with only a limited number of electrodes, in general biophysical a priori models are applied to facilitate the inverse computation. This study investigated the possibility of deriving epicardial potential information using only 62 torso electrodes in the absence of an a priori model.
__Methods:__ Computer simulations were used to determine the optimal in vivo positioning of 62 torso electrodes. Subsequently, three different electrode configurations, i.e., surrounding the thorax, concentrated precordial (30 mm inter-electrode distance) and super-concentrated precordial (20 mm inter-electrode distance) were used to record BSP from three healthy volunteers. Magnetic resonance imaging (MRI) was performed to register the electrode positions with respect to the anatomy of the patient. Epicardial potentials were inversely computed from the recorded BSP. In order to determine the reconstruction quality, the super-concentrated electrode configuration was applied in four patients with an implanted MRI-conditional pacemaker system. The distance between the position of the ventricular lead tip on MRI and the inversely reconstructed pacing site was determined.
__Results:__ The epicardial potential distribution reconstructed using the super-concentrated electrode configuration demonstrated the highest correlation (R = 0.98; p < 0.01) with the original epicardial source model. A mean localization error of 5.3 mm was found in the pacemaker patients.
__Conclusion:__ This study demonstrated the feasibility of deriving detailed anterior epicardial potential information using only 62 torso electrodes without the use of an a priori model
Integrated whole-heart computational workflow for inverse potential mapping and personalized simulations
Background: Integration of whole-heart activation simulations and inverse potential mapping (IPM) could benefit the guidance and planning of electrophysiological procedures. Routine clinical application requires a fast and adaptable workflow. These requirements limit clinical translation of existing simulation models. This study proposes a comprehensive finite element model (FEM) based whole-heart computational workflow suitable for IPM and simulations. Methods: Three volunteers and eight patients with premature ventricular contractions underwent body surface potential (BSP) acquisition followed by a cardiac MRI (CMR) scan. The cardiac volumes were segmented from the CMR images using custom written software. The feasibility to integrate tissue-characteristics was assessed by generating meshes with virtual edema and scar. Isochronal activation maps were constructed by identifying the fastest route through the cardiac volume using the Möller-Trumbore and Floyd-Warshall algorithms. IPM's were reconstructed from the BSP's. Results: Whole-heart computational meshes were generated within seconds. The first point of atrial activation on IPM was located near the crista terminalis of the superior vena cave into the right atrium. The IPM demonstrated the ventricular epicardial breakthrough at the attachment of the moderator band with the right ventricular free wall. Simulations of sinus rhythm were successfully performed. The conduction through the virtual edema and scar meshes demonstrated delayed activation or a complete conductional block respectively. Conclusion: The proposed FEM based whole-heart computational workflow offers an integrated platform for cardiac electrical assessment using simulations and IPM. This workflow can incorporate patient-specific electrical parameters, perform whole-heart cardiac activation simulations and accurately reconstruct cardiac activation sequences from BSP's
Human Detection and Classification of Landing Sites for Search and Rescue Drones
Search and rescue is often time and labour intensive. We present a system to be used in drones to make search and rescue operations more effective. The system uses a drone downward facing camera to detect people and to evaluate potential sites as being safe or not for the drone to land. Histogram of Oriented Gradients (HOG) features are extracted and a Support Vector Machine (SVM) is used as classifier. Our results show good performance on classifying frames as containing people (Sensitivity > 78%, Specificity > 83%), and distinguishing between safe and dangerous landing sites (Sensitivity > 87%, Specificity > 98%)
Regulacija puta razgradnje pentoza s pomoću gena izoliranih iz plijesni Aspergillus niger
The aim of this study was to obtain a better understanding of the pentose catabolism in Aspergillus niger and the regulatory systems that affect it. To this end, we have cloned and characterised the genes encoding A. niger L-arabitol dehydrogenase (ladA) and xylitol dehydrogenase (xdhA), and compared the regulation of these genes to other genes of the pentose catabolic pathway. This demonstrated that activation of the pathway depends on two transcriptional regulators, the xylanolytic activator (XlnR) and an unidentified L-arabinose specific regulator (AraR). These two regulators affect those genes of the pentose catabolic pathway that are related to catabolic conversion of their corresponding inducers (D-xylose and L-arabinose, respectively).Istraživanje je provedeno radi boljeg razumijevanja puta razgradnje pentoza plijesni Aspergillus niger i regulacijskih sustava koji na njega utječu. Klonirani su i karakterizirani geni koji kodiraju L-arabitol dehidrogenazu (ladA) i ksilitol dehidrogenazu (xdhA) plijesni A. niger, te uspoređeni s ostalim genima koji reguliraju put razgradnje pentoza. Otkriveno je da aktivacija puta razgradnje ovisi o dva regulatora transkripcije gena, tj. aktivatoru razgradnje D-ksiloze (XlnR) i regulatoru ekspresije gena pri razgradnji L-arabinoze (AraR)
Importance of circulating tumor cells in newly diagnosed colorectal cancer
Background: The presence of circulating tumor cells (CTC) is associated with poor prognosis in patients with metastatic colorectal cancer (CRC). This study was conducted to determine if the presence of CTC prior to surgery and during follow-up in patients with newly diagnosed non-metastatic CRC identifies patients who are at risk for disease recurrence. Methods: In a prospective single center study 183 patients with newly diagnosed non-disseminated CRC scheduled for surgery were enrolled from 2003 till 2008 and followed up for a median of 5.1 years. CTC were enumerated with the CellSearch System in 4 aliquots of 7.5 ml of peripheral blood before and after surgery (1-26 weeks), after adjuvant therapy and 1, 2, 3 and 4 years after surgery. Findings: ≥1 CTC/ 30ml of blood were detected in 44 (24%) patients before surgery. CTC frequency did not change significantly at the time points after surgery. Patients with CTC before surgery had a significant decrease in Recurrence Free Survival (RFS, logrank test p=0.014) and Colon Cancer Related Survival (CCRS, p=0.002). Five year RFS dropped from 75% to 61% and five year CCRS from 83% to 69% for patients with CTC before surgery. In a multivariate analysis of CTC, T-Stage and N-stage, the presence of CTC and N-stage remained as significant factors for RFS and CCRS. Surprisingly the presence of CTC after surgery was not significantly associated with RFS and CCRS whereas CTC 2-3 years after surgery was again significantly associated with RFS and CCRS. Interpretation: The presence of CTC in patients with stage I-III CRC before surgery is associated with a significant reduction RFS and CCRS. Although similar amounts of CTC were detected within 3 months after surgery they were not associated with RFS or CCRS. In contrast CTC were again highly significant for RFS and CCRS 2-3 years after surgery. These findings suggest a role of CTC detection, to assess which patients need adjuvant treatment. To implement CTC detection in the non-metastatic setting a validated CTC detection technology is needed with increased sensitivity and specificity
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