Experimental ground-state combination differences of CH5 Asvany, Oskar; Yamada, Koichi M. T.; Brünken, Sandra ...
Science (American Association for the Advancement of Science),
03/2015, Letnik:
347, Številka:
6228
Journal Article
Recenzirano
Protonation of methane (CH4), a rather rigid molecule well described by quantum mechanics, produces CH5+, a prototypical floppy molecule that has eluded definitive spectroscopic description. ...Experimental measurement of high-resolution spectra of pure CH5+ samples poses a formidable challenge. By applying two types of action spectroscopy predicated on photoinduced reaction with CO2 and photoinhibition of helium cluster growth, we obtained low-temperature, high-resolution spectra of mass-selected CH5+. On the basis of the very high accuracy of the line positions, we determined a spectrum of combination differences. Analysis of this spectrum enabled derivation of equally accurate ground state–level schemes of the corresponding nuclear spin isomers of CH5+, as well as tentative quantum number assignment of this enfant terrible of molecular spectroscopy.
Human activities pose a significant threat to the water quality of rivers when pollution exceeds the threshold limit. Urban activities in particular are highlighted as one of the major causes of ...contamination in surface water bodies in Asian countries. Evaluation of sustainable human population capacities in river watersheds is necessary to maintain better freshwater ecosystems in a country while achieving its development goals as a nation. We evaluated the correlation between the growth rate of the population in a watershed area and water quality parameters of a river ecosystem. The Kelani River in Sri Lanka was selected for the study. The highest correlation coefficients of 0.7, 0.69, 0.69 (p < 0.01) corresponding to biochemical oxygen demand (BOD), dissolved oxygen (DO) and total coliform (TC) were obtained with the population in watersheds of the Kelani river in Sri Lanka. Thus, we propose a quantitative approach to estimating the population capacity of watersheds based on water quality classification standards (WQCS), employing the Bayesian network (BN) classification model. The optimum population ranges were obtained from the probability distribution table of the population node in the BN. The results showed that the population density should be approximately less than 2375 to keep the water quality in the watershed for bathing and drinking purposes and approximately less than 2672 for fish and other aquatic organisms. This research will offer a means that can used to understand the impact of population on water quality in river basins and confer direct influence on natural water bodies.
Dempster rule of combination is the standard way of combining multiple pieces of evidence given by independent sources of information. However, it aroused many controversies about its validity, and ...many alternatives have been proposed. The paper examines the model of combination in Dempster's original paper and indicates that handling of the independence required among multiple pieces of evidence is strange from the viewpoint of semantics, where the independence among occurrences of multiple pieces of information might be confused with the consistency among contents of the information. The paper then proposes a new model of combination and a new rule of combination called
combination by compromise as a consensus generator. The properties of the proposed combination as well as several alternative combination methods proposed so far are discussed in the light of the drawbacks and advantages of Dempster rule. Several numerical examples which demonstrate the properties are also shown. The discussion and the examples suggest that the proposed combination produces the most preferable results among them from the viewpoints of consensus generation.
Antifungal stewardship (AFS), compared with antimicrobial stewardship (AS), requires more advanced knowledge, skills, and multidisciplinary collaboration in its implementation. Therefore, fewer ...facilities are performing AFS compared with AS. At our hospital, we started AS and AFS in 2014. Our AFS programs include the following: i) interventions for patients with yeast-positive blood cultures, ii) introduction of a conditional antifungal notification system, and iii) commencement of AS team rounds. AFS for filamentous fungi includes bronchoscopy and microbial identification, including genetic and drug susceptibility testing. These AFS activities have improved several processes and outcome measures. However, our AFS team has faced several problems owing to the impact of COVID-19. This review introduces the practice of AFS, which we initiated at our hospital in 2014, and presents the current problems.
A novel rotational spectroscopy method applicable to ions stored in cold traps is presented. In a double resonance scheme, rotational excitation is followed by vibrational excitation into a ...dissociative resonance. Its general applicability is demonstrated for the CH3+−He complex, which undergoes predissociation through its C-H stretching modes ν1 and ν3. High resolution rotational transitions are recorded for this symmetric top, and small unexpected splittings are resolved for K=1. Advantages and potential future applications of this new approach are discussed.
Uncertainty aggregation is an important reasoning for making decisions in the real world, which is full of uncertainty. The paper proposes an information source model for aggregating epistemic ...uncertainties about truth and discusses uncertainty aggregation in the form of possibility distributions. A new combination rule of possibilities for truth is proposed. Then, this paper proceeds to discussion about a traditional but seemingly forgotten representation of uncertainty (i.e., certainty factors (CFs)) and proposes a new interpretation based on possibility theory. CFs have been criticized because of their lack of sound mathematical interpretation from the viewpoint of probability. Thus, this paper first establishes a theory for a sound interpretation using possibility theory. Then it examines aggregation of CFs based on the interpretation and some combination rules of possibility distributions. The paper proposes several combination rules for CFs having sound theoretical basis, one of which is exactly the same as the oft-criticized combination.
We demonstrate that dual-comb spectroscopy, which allows one to record broadband spectra with high frequency accuracy in a relatively short time, provides a real advantage for the observation of ...pressure-broadening and pressure-shift effects. We illustrate this with the ν_{1}+ν_{3} vibration band of ^{12}C_{2}H_{2}. We observe transitions from P(26) to R(29), which extend over a 3.8 THz frequency range, at six pressures ranging up to 2654 Pa. Each observed absorption line profile is fitted to a Voigt function yielding pressure-broadening and pressure-shift coefficients for each rotation-vibration transition. The effectiveness of this technique is such that we are able to discern a clear dependence of the pressure-broadening coefficients on the nuclear spin state, i.e., on the ortho or para modification. This information, combined with the pressure-shift coefficients, can facilitate a detailed understanding of the mechanism of molecular collisions.
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•Observation of ten pseudo a-type transitions and triplets due to the coupling with the internal rotation of the second methyl group.•Analysis of the observed transition ...frequencies.•Obtained barrier height V3(CH2-CH3) = 1078 (12) cm−1 using the splittings of the second methyl group.•Explanation for the abnormal intensities and the hyperfine structures of the E state using the wavefunctions.
We observed ten pseudo a-type transitions in the E state of N-ethylacetamide (NEAA) using a Fourier transform microwave spectrometer. We found triplets caused by the coupling between the two methyl groups for the observed pseudo a-type transitions. Also, we succeeded in observing similar triplets for the 5 a-type Q-branch transitions, 20 b-type and 7 c-type transitions of the E state of NEAA. These observed triplets allowed us to determinate the potential barrier V3 to internal rotation of the ethyl-methyl group to be 1078 (12) cm−1. In addition, though the observed intensities of the c-type transitions in the A state were weak, the c-type transition in the E state were observed to be as intense as the b-type transitions of the E state. We explained in this paper the abnormal intensities of the c-type transitions and pseudo a-type transitions in the E state of NEAA.
We propose and demonstrate a novel method for temperature determination using dual-comb spectroscopy and a novel analysis technique, “Rotational-state Distribution Thermometry: RDT.” We obtained the ...spectral profile of a vibration–rotation band of
12
C
2
H
2
using dual-comb spectroscopy at room temperature. The line-center absorbance was determined for each transition by fitting the line profile to a Gaussian function. A model function that relates the rotational temperature of the molecule to the distribution of the line-center absorbance was introduced; the gas temperature was determined by fitting the distribution to the model function. The determined temperature agrees to within 0.6 K with the cell-wall temperature measured with a platinum resistance thermometer. In addition, using the spectral profile obtained in this study, we compare the present analysis with two conventional methods for determining the gas temperature; one is based on the line-center absorbance ratio, and the other on the Doppler width. The present method takes full advantage of the supreme characteristics of dual-comb spectroscopy and has the potential to offer fast and precise thermometry.
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