Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\nu_1+\nu_2+\nu_3+\nu_4^1+\nu_5^{-1}$ in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) $\text{cm}^{-1}$, the rotational parameter $B$ was 1.162222 $\text{cm}^{-1}$, and the quartic centrifugal distortion parameter $D$ was 3.998(62)$\times 10^{-6} \text{cm}^{-1}$, where the numbers in the parenthesis are one-standard errors in the least significant digits

Acetylene in breath: background levels and real-time elimination kinetics after smoking

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Seven exercises planned to stimulate the flow of ideas in creative composition

Thesis (Ed.M.)--Boston Universit

Transitioning out of Leadership: Is There Life After Higher Administration?

This article showcases the case histories of three former higher education administrators who stepped down from their responsibilities to rejoin the faculty. From their collective experiences, they extracted the variables that tend to influence the change in professional trajectory. The authors explain how an assortment of cognitive biases can influence the success or failure of downward transitions. We conclude the article with suggestions regarding how to make a successful transition from academic administration back to faculty status

Intramedullary Fixation of Trochanteric Fractures Can Be Safely Performed by Senior Residents Without Immediate Consultant Supervision

OBJECTIVE: To assess the safety of senior residents performing trochanteric hip fracture surgery without immediate consultant supervision DESIGN: A retrospective chart review of trochanteric hip fractures (AO-OTA 31-A) operated in a single center between years 2011 and 2016 (inclusive). Operations were divided into three groups: Group 1 surgeon was a senior resident without any immediate supervision; Group 2 surgeon was a consultant and Group 3surgeon was a senior resident supervised by a consultant. The follow-up period was a minimum of 2 years or until death. All re-operations and surgical related mortality were assessed. SETTING: Helsinki University Hospital, Finland. A tertiary level trauma center. PARTICIPANTS: 987 consecutive trochanteric fractures on 966 patients treated by operative fixation of an intertrochanteric fracture with an intramedullary nail between 2011and 2016 (inclusive). RESULTS: The total number of reoperations was smaller in Group 1 where the surgeon was a senior resident without any immediate supervision compared to Group 2 where the surgeon was a consultant (5.5 % vs 8.8 %, p < 0.05). There were no significant differences in mortality or length of surgery. The total rate of mechanical complications was 2.0 %, with no significant differences between groups. The observed blade cut-out rate was low: 1.3 %, suggesting a good overall quality of surgery. CONCLUSIONS: Senior residents can safely perform intramedullary nailing of trochanteric fractures without immediate supervision. (C) 2021 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.)Peer reviewe

Nuclear Quadrupole Hyperfine Structure in HC14N/H14NC and DC15N/D15NC Isomerization: A Diagnostic Tool for Characterizing Vibrational Localization

Large-amplitude molecular motions which occur during isomerization can cause significant changes in electronic structure. These variations in electronic properties can be used to identify vibrationally-excited eigenstates which are localized along the potential energy surface. This work demonstrates that nuclear quadrupole hyperfine interactions can be used as a diagnostic marker of progress along the isomerization path in both the HC14N/H14NC and DC15N/D15NC chemical systems. Ab initio calculations at the CCSD(T)/cc-pCVQZ level indicate that the hyperfine interaction is extremely sensitive to the chemical bonding of the quadrupolar 14N nucleus and can therefore be used to determine in which potential well the vibrational wavefunction is localized. A natural bonding orbital analysis along the isomerization path further demonstrates that hyperfine interactions arise from the asphericity of the electron density at the quadrupolar nucleus. Using the CCSD(T) potential surface, the quadrupole coupling constants of highly-excited vibrational states are computed from a one-dimensional internal coordinate path Hamiltonian. The excellent agreement between ab initio calculations and recent measurements demonstrates that nuclear quadrupole hyperfine structure can be used as a diagnostic tool for characterizing localized HCN and HNC vibrational states.Comment: Accepted by Physical Chemistry Chemical Physic

Many-body wave function for a quantum dot in a weak magnetic field

The ground states of parabolically confined electrons in a quantum dot are studied by both direct numerical diagonalization and quantum Monte Carlo (QMC) methods. We present a simple but accurate variational many-body wave function for the dot in the limit of a weak magnetic field. The wave function has the center-of-mass motion restricted to the lowest-energy state and the electron-electron interaction is taken into account by a Jastrow two-body correlation factor. The optimized wave function has an accuracy very close to the state-of-the-art numerical diagonalization calculations. The results and the computational efficiency indicate that the presented wave function combined with the QMC method suits ideally for studies of large quantum dots.Peer reviewe

Peri-implant fracture : a rare complication after intramedullary fixation of trochanteric femoral fracture

Introduction Trochanteric femoral fractures are among the most common operatively treated fractures. Intramedullary fixation has become the treatment of choice in many centers around the world. Nevertheless, the knowledge of rare complications of these fractures is limited. In this study, the incidence and treatment strategies for peri-implant fractures (PIF) were assessed. Materials and methods A single-center retrospective cohort study was done on 987 consecutive operatively treated trochanteric fractures. PFNA cephalomedullary nail was used as a fixation method. All patients were followed up from patient records for peri-implant fractures. Plain radiographs as well as different salvage methods were analyzed and compared. Results The total rate of peri-implant fractures was 1.4% (n = 14). The rate of PIF for patients treated with short (200 mm) nails, intermediate-length (240 mm) nails, and long nails was 2.7% (n = 2), 1.5% (n = 11), and 0.7% (n = 1), respectively (ns, p > 0.05 for difference). Treatment of choice for PIF was either ORIF with locking plate (57%, n = 8) or exchange nailing (43%, n = 6). None of the PIF patients needed additional surgeries for non-union, malunion, or delayed union. Conclusions A PIF is a rare complication of intramedullary fixation of trochanteric fractures. It can be treated with either locking plates or exchange nailing with sufficient results. There are no grounds for favoring long nails to avoid PIFs.Peer reviewe