Asset Abandonment Analysis and Decision Making Evaluation of Asset Abandonment Decision Models

Abandonment is something that happens everyday within companies and with consumers. Nearly every person has decided to throw something away at one point in their life. Businesses make similar decisions every day. Sometimes the decisions are made voluntarily by the compames. Market and economic conditions frequently change. These changes require that projects and assets be reviewed periodically with respect to current and future profitability. Those assets (or projects) whose future profitability is questioned become candidates for possible abandonment. Many times certain projects only remain profitable when interest rates are low, or energy costs high, or tax laws favor investment. When their direction changes, the wise manager must make the decision that continues to enhance the profits of the firm. This paper will review the types of models presented for use in making abandonment decisions and how these apply to the abandonment of physical assets. Two new models will be developed to assist the manager in making these abandonment decisions. Analysis will include reviewing the important variables and assessmg the relative weight of each. The models developed provide an enhancement to those found in the literature. The two new models proposed are contrasted with a model presented by another author. In the p:uticular example, circumstances occur where the published model does not indicate abandonment and the new models do. It is these borderline cases where the use of the proper model can make a big difference in a go/no go decision. It is the very fact that these things do change that causes us to not only evaluate the future cash flows and abandonment value but also make the decision whether or not to abandon the asset or keep it. It is hoped that this paper provides the analyst with a tool to evaluate the question and make the proper decision.Business Administratio

Circulating endothelial cells as biomarker for cardiovascular diseases.

Background: Endothelial dysfunction is involved in several cardiovascular diseases. Elevated levels of circulating endothelial cells (CECs) and low levels of endothelial progenitor cells (EPCs) have been described in different cardiovascular conditions, suggesting their potential use as diagnostic biomarkers for endothelial dysfunction. Compared to typical peripheral blood leukocyte subsets, CECs and EPCs occur at very low frequency. The reliable identification and characterization of CECs and EPCs is a prerequisite for their clinical use, however, a validated method to this purpose is still missing but a key for rare cell events. Objectives: To establish a validated flow cytometric procedure in order to quantify CECs and EPCs in human whole blood. Methods: In the establishment phase, the assay sensitivity, robustness, and the sample storage conditions were optimized as prerequisite for clinical use. In a second phase, CECs and EPCs were analyzed in heart failure with preserved (HFpEF) and reduced (HFrEF) ejection fraction, in arterial hypertension (aHT), and in diabetic nephropathy (DN) in comparison to age-matched healthy controls. Results: The quantification procedure for CECs and EPCs showed high sensitivity and reproducibility. CEC values resulted significantly increased in patients with DN and HFpEF in comparison to healthy controls. CEC quantification showed a diagnostic sensitivity of 90% and a sensitivity of 68.0%, 70.4%, and 66.7% for DN, HFpEF, and aHT, respectively. Conclusion: A robust and precise assay to quantify CECs and EPCs in pre-clinical and clinical studies has been established. CEC counts resulted to be a good diagnostic biomarker for DN and HFpEF

Photo- and Electroproduction of Eta Mesons

Eta photo- and electroproduction off the nucleon is investigated in an effective lagrangian approach that contains Born terms and both vector meson and nucleon resonance contributions. In particular, we review and develop the formalism for coincidence experiments with polarization degrees of freedom. The different response functions appearing in single and double polarization experiments have been studied. We will present calculations for structure functions and kinematical conditions that are most sensitive to details of the lagrangian, in particular with regard to contributions of nucleon resonances beyond the dominant $S_{11}$(1535) resonance.Comment: 24 pages RevTeX/LaTeX2.09, NFSS1, 13 figures (in separate file (tar,gzip and uue)), accepted for publication in Z. Phys.

New Concepts of the Chemistry of Electric-Discharge Oxygen-Iodine Lasers

ABSTRACT The chemistry of electric discharge driven oxygen iodine lasers (EOIL) has long been believed to have O 2 (a 1 Δ g ) as the sole energy carrier for excitation of the lasing state I( 2 P 1/2 ), and O( 3 P) as the primary quencher of this state. In many sets of experimental measurements over a wide range of conditions, we have observed persistent evidence to the contrary. In this paper, we review our experimental data base in both room-temperature discharge-flow measurements and EOIL reactor results, in comparison to model predictions and kinetics analysis, to identify the missing production and loss terms in the EOIL reaction mechanism. The analysis points to a significantly higher level of understanding of this energetic chemical system, which can support advanced concepts in power scaling investigations

Prosthetic heart valve assessment with multidetector-row CT: imaging characteristics of 91 valves in 83 patients

Multidetector CT (MDCT) has shown potential for prosthetic heart valve (PHV) assessment. We assessed the image quality of different PHV types to determine which valves are suitable for MDCT evaluation. All ECG-gated CTs performed in our institutions since 2003 were reviewed for the presence of PHVs. After reconstruction in 3 specific PHV planes, image quality of the supravalvular, perivalvular, subvalvular and valvular regions was scored on a four-point scale (1 = non-diagnostic, 2 = moderate, 3 = good and 4 = excellent) by two independent observers. Eighty-four CT examinations (66 cardiac, 18 limited-dose aortic protocols) of 83 patients with a total of 91 PHVs in the aortic (n = 71), mitral (n = 17), pulmonary (n = 1) and tricuspid (n = 2) position were included. CT was performed on a 16-slice (n = 4), 64-slice (n = 28) or 256-slice (n = 52) MDCT system. Median image quality scores for the supra-, peri- and subvalvular regions and valvular detail were (3.5, 3.3, 3.5 and 3.5, respectively) for bileaflet PHV; (3.0, 3.0, 3.5 and 3.0, respectively) for Medtronic Hall PHV; (1.0, 1.0, 1.0 and 1.0, respectively) for Björk-Shiley and Sorin monoleaflet PHV and (3.5, 3.5, 4.0 and 2.0 respectively) for biological PHV. Currently implanted PHVs have good image quality on MDCT and are suitable for MDCT evaluatio

Multidetector CT imaging of mechanical prosthetic heart valves: quantification of artifacts with a pulsatile in-vitro model

Item does not contain fulltextOBJECTIVES: Multidetector computed tomography (MDCT) can detect the cause of prosthetic heart valve (PHV) dysfunction but is hampered by valve-induced artifacts. We quantified artifacts of four PHV using a pulsatile in-vitro model and assessed the relation to leaflet motion and valve design. METHODS: A Medtronic Hall tilting disc (MH), and Carbomedics (CM), St Jude (SJM), and ON-X bileaflet valves underwent CT in an in-vitro model using retrospective gating with a 64 detector CT system in stationary and pulsatile conditions. Artifacts and radiopaque component volumes were quantified with thresholds based on surrounding structures and valvular components. RESULTS: Hypodense artifacts volumes (mm(3)) were 1,029 +/- 147, 535 +/- 53, 371 +/- 16, and 366 +/- 18 for the SJM, MH, CM and ON-X valves (p < 0.001 except for the latter two valves p = 0.43). Hyperdense artifact volumes were 3,546 +/- 141, 2,387 +/- 103, 2,003 +/- 102, and 3,033 +/- 31 for the SJM, MH, CM and ON-X valve, respectively (all differences p < 0.001). Leaflet motion affected hypodense (F = 41.5, p < 0.001) and hyperdense artifacts (F = 53.7, p < 0.001). Closed and moving leaflets were associated with the least and the most artifacts respectively (p < 0.001, both artifact types). CONCLUSION: Both valve design and leaflet motion affect PHV-induced artifacts. Best imaging results may be expected for the CM valve during phases in which the leaflets are closed

Coronary artery assessment by multidetector computed tomography in patients with prosthetic heart valves

Objectives Patients with prosthetic heart valves may require assessment for coronary artery disease. We assessed whether valve artefacts hamper coronary artery assessment by multidetector CT. Methods ECG-gated or -triggered CT angiograms were selected from our PACS archive based on the presence of prosthetic heart valves. The best systolic and diastolic axial reconstructions were selected for coronary assessment. Each present coronary segment was scored for the presence of valve-related artefacts prohibiting coronary artery assessment. Scoring was performed in consensus by two observers. Results Eighty-two CT angiograms were performed on a 64-slice ( = 27) or 256-slice ( = 55) multidetector CT. Eighty-nine valves and five annuloplasty rings were present. Forty-three out of 1160 (3.7%) present coronary artery segments were non-diagnostic due to valve artefacts (14/82 patients). Valve artefacts were located in right coronary artery (15/43; 35%), left anterior descending artery (2/43; 5%), circumflex artery (14/43; 32%) and marginal obtuse (12/43; 28%) segments. All cobalt-chrome containing valves caused artefacts prohibiting coronary assessment. Biological and titanium-containing valves did not cause artefacts except for three specific valve types. Conclusions Most commonly implanted prosthetic heart valves do not hamper coronary assessment on multidetector CT. Cobalt-chrome containing prosthetic heart valves preclude complete coronary artery assessment because of severe valve artefacts. Key Points Most commonly implanted prosthetic heart valves do not hamper coronary artery assessment Prosthetic heart valve composition determines the occurrence of prosthetic heart valve-related artefacts Bjork-Shiley and Sorin tilting disc valves preclude diagnostic coronary artery segment assessmen

Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT

Item does not contain fulltextOBJECTIVES: Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related to pulsating PHV. METHODS: In a pulsatile in vitro model, a mono- and bileaflet PHV were imaged using 256 MDCT at 60, 75 and 90 beats per minute (BPM) with either retrospective gating (120 kV, 600 mAs, pitch 0.2, CTDI(vol) 39.8 mGy) or prospective triggering (120 kV, 200 mAs, CTDI(vol) 13.3 mGy). Two thresholds (>175 and <-45HU), derived from the density of surrounding structures, were used for quantification of hyper- and hypodense artefacts. Image noise and artefacts were compared between protocols. RESULTS: Prospective triggering reduced hyperdense artefacts for both valves at every BPM (P = 0.001 all comparisons). Hypodense artefacts were reduced for the monoleaflet valve at 60 (P = 0.009), 75 (P = 0.016) and 90 BPM (P = 0.001), and for the bileaflet valves at 60 (P = 0.001), 90 (P = 0.001) but not at 75 BPM (P = 0.6). Prospective triggering reduced image noise at 60 (P = 0.001) and 75 (P < 0.03) but not at 90 BPM. CONCLUSIONS: Compared with retrospective gating, prospective triggering reduced most artefacts related to pulsating PHV in vitro. KEY POINTS: * Computed tomographic images are often degraded by prosthetic heart valve-induced artefacts * Prospective triggering reduces prosthetic heart valve-induced artefacts in vitro * Artefact reduction at 90 beats per minute occurs without image noise reduction * Prospective triggering may improve CT image quality of moving hyperdense structures.1 juni 201

Preliminary Study of Prospective ECG-Gated 320-Detector CT Coronary Angiography in Patients with Ventricular Premature Beats

BACKGROUND: To study the applicability of prospective ECG-gated 320-detector CT coronary angiography (CTCA) in patients with ventricular premature beats (VPB), and determine the scanning mode that best maximizes image quality and reduces radiation dose. METHODS: 110 patients were divided into a VPB group (60 cases) and a control group (50 cases) using CTCA. All the patients then underwent coronary angiography (CAG) within one month. CAG served as a reference standard through which the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTCA in diagnosing significant coronary artery stenosis (luminal stenosis ≥50%) could be analyzed. The two radiologists with more than 3 years' experience in cardiac CT each finished the image analysis after consultation. A personalized scanning mode was adopted to compare image quality and radiation dose between the two groups. METHODOLOGY/PRINCIPAL FINDINGS: At the coronary artery segment level, sensitivity, specificity, PPV, and NPV in the premature beat group were 92.55%, 98.21%, 88.51%, and 98.72% respectively. In the control group these values were found to be 95.79%, 98.42%, 90.11%, and 99.28% respectively. Between the two groups, specificity, sensitivity PPV, NPV was no significant difference. The two groups had no significant difference in image quality score (P>0.05). Heart rate (77.20±12.07 bpm) and radiation dose (14.62±1.37 mSv) in the premature beat group were higher than heart rate (58.72±4.73 bpm) and radiation dose (3.08±2.35 mSv) in the control group. In theVPB group, the radiation dose (34.55±7.12 mSv) for S-field scanning was significantly higher than the radiation dose (15.10±1.12 mSv) for M-field scanning. CONCLUSIONS/SIGNIFICANCE: With prospective ECG-gated scanning for VPB, the diagnostic accuracy of coronary artery stenosis is very high. Scanning field adjustment can reduce radiation dose while maintaining good image quality. For patients with slow heart rates and good rhythm, there was no statistically significant difference in image quality