230 research outputs found

    Mobile Robot Performance Analysis for Indoor Robotics

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    In the last few years the market of robotics has significantly changed and the growing sector of service robotics requires new considerations in civil engineering. This paper investigates different room and furniture arrangements in the view of mobile robot navigation requirements. The described method provides robot motion and path planning cost functions for different furniture arrangements and floor maps. During mobile robot path planning ISO 7176-10:2008 and ISO 7176-5:2008 (electrically powered wheelchair) compatible buildings were considered to find the optimal solutions over the minimal standardized requirements. The proposed method can provide efficient results regarding navigation error, time and power consumption

    Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]

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    We demonstrate that a minor modification of the extrapolation proposed by Jensen [(2005): Theor Chem Acc 113:267] yields very reliable estimates of the Hartree-Fock limit in conjunction with correlation consistent basis sets. Specifically, a two-point extrapolation of the form EHF,L=EHF,+A(L+1)exp(9L)E_{HF,L}=E_{HF,\infty}+A(L+1)\exp(-9\sqrt{L}) yields HF limits EHF,E_{HF,\infty} with an RMS error of 0.1 millihartree using aug-cc-pVQZ and aug-cc-pV5Z basis sets, and of 0.01 millihartree using aug-cc-pV5Z and aug-cc-pV6Z basis sets.Comment: Theoretical Chemistry Accounts, in pres

    Performance of ab initio and density functional methods for conformational equilibria of CnH2n+2 alkane isomers (n=2-8)

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    Conformational energies of n-butane, n-pentane, and n-hexane have been calculated at the CCSD(T) level and at or near the basis set limit. Post-CCSD(T) contribution were considered and found to be unimportant. The data thus obtained were used to assess the performance of a variety of density functional methods. Double-hybrid functionals like B2GP-PLYP and B2K-PLYP, especially with a small Grimme-type empirical dispersion correction, are capable of rendering conformational energies of CCSD(T) quality. These were then used as a `secondary standard' for a larger sample of alkanes, including isopentane and the branched hexanes as well as key isomers of heptane and octane. Popular DFT functionals like B3LYP, B3PW91, BLYP, PBE, and PBE0 tend to overestimate conformer energies without dispersion correction, while the M06 family severely underestimates GG interaction energies. Grimme-type dispersion corrections for these overcorrect and lead to qualitatively wrong conformer orderings. All of these functionals also exhibit deficiencies in the conformer geometries, particularly the backbone torsion angles. The PW6B95 and, to a lesser extent, BMK functionals are relatively free of these deficiencies. Performance of these methods is further investigated to derive conformer ensemble corrections to the enthalpy function, H298H0H_{298}-H_0, and the Gibbs energy function, gef(T)[G(T)H0]/T{\rm gef}(T)\equiv - [G(T)-H_0]/T, of these alkanes. While H298H0H_{298}-H_0 is only moderately sensitive to the level of theory, gef(T){\rm gef}(T) exhibits more pronounced sensitivity. Once again, double hybrids acquit themselves very well.Comment: J. Phys. Chem. A, revised [Walter Thiel festschrift

    Randomized Comparison of a CrossBoss First Versus Standard Wire Escalation Strategy for Crossing Coronary Chronic Total Occlusions: The CrossBoss First Trial

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    OBJECTIVES: The authors performed a multicenter, randomized-controlled, clinical trial comparing upfront use of the CrossBoss catheter versus antegrade wire escalation for antegrade crossing of coronary chronic total occlusions. BACKGROUND: There is equipoise about the optimal initial strategy for crossing coronary chronic total occlusions. METHODS: The primary endpoints were the time required to cross the chronic total occlusion or abort the procedure and the frequency of procedural major adverse cardiovascular events. The secondary endpoints were technical and procedural success, total procedure time, fluoroscopy time required to cross and total fluoroscopy time, total air kerma radiation dose, total contrast volume, and equipment use. RESULTS: Between 2015 and 2017, 246 patients were randomized to the CrossBoss catheter (n = 122) or wire escalation (n = 124) at 11 U.S. centers. The baseline clinical and angiographic characteristics of the study groups were similar. Technical and procedural success were 87.8% and 84.1%, respectively, and were similar in the 2 groups. Crossing time was similar: 56 min (interquartile range: 33 to 93 min) in the CrossBoss group and 66 min (interquartile range: 36 to 105 min) in the wire escalation group (p = 0.323), as was as the incidence of procedural major adverse cardiovascular events (3.28% vs. 4.03%; p = 1.000). There were no significant differences in the secondary study endpoints. CONCLUSIONS: As compared with wire escalation, upfront use of the CrossBoss catheter for antegrade crossing of coronary chronic total occlusions was associated with similar crossing time, similar success and complication rates, and similar equipment use and cost

    A Halomethane thermochemical network from iPEPICO experiments and quantum chemical calculations

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    Internal energy selected halomethane cations CH3Cl+, CH2Cl2+, CHCl3+, CH3F+, CH2F2+, CHClF2+ and CBrClF2+ were prepared by vacuum ultraviolet photoionization, and their lowest energy dissociation channel studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO). This channel involves hydrogen atom loss for CH3F+, CH2F2+ and CH3Cl+, chlorine atom loss for CH2Cl2+, CHCl3+ and CHClF2+, and bromine atom loss for CBrClF2+. Accurate 0 K appearance energies, in conjunction with ab initio isodesmic and halogen exchange reaction energies, establish a thermochemical network, which is optimized to update and confirm the enthalpies of formation of the sample molecules and their dissociative photoionization products. The ground electronic states of CHCl3+, CHClF2+ and CBrClF2+ do not confirm to the deep well assumption, and the experimental breakdown curve deviates from the deep well model at low energies. Breakdown curve analysis of such shallow well systems supplies a satisfactorily succinct route to the adiabatic ionization energy of the parent molecule, particularly if the threshold photoelectron spectrum is not resolved and a purely computational route is unfeasible. The ionization energies have been found to be 11.47 ± 0.01 eV, 12.30 ± 0.02 eV and 11.23 ± 0.03 eV for CHCl3, CHClF2 and CBrClF2, respectively. The updated 0 K enthalpies of formation, ∆fHo0K(g) for the ions CH2F+, CHF2+, CHCl2+, CCl3+, CCl2F+ and CClF2+ have been derived to be 844.4 ± 2.1, 601.6 ± 2.7, 890.3 ± 2.2, 849.8 ± 3.2, 701.2 ± 3.3 and 552.2 ± 3.4 kJ mol–1, respectively. The ∆fHo0K(g) values for the neutrals CCl4, CBrClF2, CClF3, CCl2F2 and CCl3F and have been determined to be –94.0 ± 3.2, –446.6 ± 2.7, –702.1 ± 3.5, –487.8 ± 3.4 and –285.2 ± 3.2 kJ mol–1, respectively

    Correct quantum chemistry in a minimal basis from effective Hamiltonians

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    We describe how to create ab-initio effective Hamiltonians that qualitatively describe correct chemistry even when used with a minimal basis. The Hamiltonians are obtained by folding correlation down from a large parent basis into a small, or minimal, target basis, using the machinery of canonical transformations. We demonstrate the quality of these effective Hamiltonians to correctly capture a wide range of excited states in water, nitrogen, and ethylene, and to describe ground and excited state bond-breaking in nitrogen and the chromium dimer, all in small or minimal basis sets

    Prevalence and Outcomes of Percutaneous Coronary Interventions for Ostial Chronic Total Occlusions: Insights From a Multicenter Chronic Total Occlusion Registry

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    Ostial chronic total occlusions (CTOs) can be challenging to recanalize.We sought to examine the prevalence, angiographic presentation, and procedural outcomes of ostial (side-branch ostial and aorto-ostial) CTOs among 1000 CTO percutaneous coronary interventions (PCIs) performed in 971 patients between 2015 and 2017 at 14 centres in the US, Europe, and Russia.Ostial CTOs represented 16.9% of all CTO PCIs: 9.6% were aorto-ostial, and 7.3% were side-branch ostial occlusions. Compared with nonostial CTOs, ostial CTOs were longer (44 ± 33 vs 29 ± 19 mm, P < 0.001) and more likely to have proximal-cap ambiguity (55% vs 33%, P < 0.001), moderate/severe calcification (67% vs 45%, P < 0.001), a diffusely diseased distal vessel (41% vs 26%, P < 0.001), interventional collaterals (64% vs 53%, P = 0.012), and previous coronary artery bypass graft surgery (CABG) (51% vs 27%, P < 0.001). The retrograde approach was used more often in ostial CTOs (54% vs 29%, P < 0.001) and was more often the final successful crossing strategy (30% vs 18%, P = 0.003). Technical (81% vs 84%, P = 0.280), and procedural (77% vs 83%, P = 0.112) success rates and the incidence of in-hospital major complication were similar (4.8% vs 2.2%, P = 0.108), yet in-hospital mortality (3.0% vs 0.5%, P = 0.010) and stroke (1.2% vs 0.0%, P = 0.030) were higher in the ostial CTO PCI group. In multivariable analysis, ostial CTO location was not independently associated with higher risk for in-hospital major complications (adjusted odds ratio 1.27, 95% confidence intervals 0.37 to 4.51, P = 0.694).Ostial CTOs can be recanalized with similar rates of success as nonostial CTOs but are more complex, more likely to require retrograde crossing and may be associated with numerically higher risk for major in-hospital complications

    In-hospital Outcomes of Attempting More Than One Chronic Total Coronary Occlusion Through Percutaneous Intervention During the Same Procedure

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    The frequency and outcomes of patients who underwent chronic total occlusion (CTO) percutaneous coronary intervention (PCI) of more than one CTO during the same procedure have received limited study. We compared the clinical and angiographic characteristics and procedural outcomes of patients who underwent treatment of single versus >1 CTOs during the same procedure in 20 centers from the United States, Europe, and Russia. A total of 2,955 patients were included: mean age was 65 ± 10 years and 85% were men with high prevalence of previous myocardial infarction (46%), and previous coronary artery bypass graft surgery (33%). More than one CTO lesions were attempted during the same procedure in 58 patients (2.0%) and 70% of them were located in different major epicardial arteries. Compared with patients who underwent PCI of a single CTO, those who underwent PCI of >1 CTOs during the same procedure had similar J-CTO (2.4 ± 1.3 vs 2.5 ± 1.3, p = 0.579) and Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (1.5 ± 1.2 vs 1.3 ± 1.0 p = 0.147) scores. The multi-CTO PCI group had similar technical success (86% vs 87%, p = 0.633), but higher risk of in-hospital major complications (10.3% vs 2.7%, p = 0.005), and consequently numerically lower procedural success (79% vs 85%, p = 0.197). The multi-CTO PCI group had higher in-hospital mortality (5.2% vs 0.5%, p = 0.005) and stroke (5.2%vs 0.2%, p 1 CTO lesions requiring revascularization, as treatment during a single procedure was associated with higher risk for periprocedural complications
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