Recurrent Laryngeal Nerve Electrophysiologic Monitoring in Thyroid Surgery: The Standard of Care?

Reports in the literature suggest that the rate of transient and permanent vocal fold immobility (VFI) after thyroid surgery is 4% to 7% and 1% to 4%. The intraoperative use of nerve integrity monitors has been advocated to reduce the incidence of VFI during thyroid surgery. The purpose of this study was to compare postoperative VFI after unmonitored and monitored thyroid surgical procedures. The charts of 136 consecutive patients who underwent thyroid surgery from 1998 to 2003 were retrospectively surveyed. Fifty-four patients had total thyroidectomies, bringing the total recurrent laryngeal nerves (RLNs) dissected to 190. Three of 190 (1.6%) and 7 of 190 (3.7%) RLNs dissected had permanent and transient vocal fold dysfunction. Overall, 107 RLNs were unmonitored compared with 83 RLNs that were monitored. Unmonitored and monitored RLNs had a 4 of 83 (4.8%) versus 3 of 107 (2.8%) rate of transient VFI (P > 0.05). Unmonitored and monitored RLNs had a 1 of 107 (0.9%) versus 2 of 83 (2.4%) rate of permanent VFD (P > 0.05). Electrophysiologic RLN monitoring was not demonstrated in this study to reduce the incidence of transient or permanent VFI after thyroid surgery. Electrophysiologic RLN integrity does not always translate into clinical postoperative vocal fold mobility. Electrophysiologic RLN monitoring may support that the RLN was not severed in the patient with postoperative VFI.     

Electroexcitation of magnetic dipole and other modes in46Ti and48Ti

With high-resolution inelastic electron scattering measurements on⁴⁶Ti and⁴⁸Ti the excitation mechanism of the transition into low lying J^π=1⁺ states is investigated. The experimental evidence of considerable contribution of the orbital part of theM1 operator to the total transition strength is given by a model dependent analysis of form factors. The possibility of physical relationship to low lying J^π=1⁺ states in the rare earth nuclei is discussed in various models. MoreoverE2 form factors and good candidates forM3 form factors are presented.     

Prediction and understanding system peaks in capillary zone electrophoresis

Introduction of a sample into the separation column (microchip channel) in capillary zone electrophoresis (microchip electrophoresis) will cause a disturbance in the originally uniform composition of the background electrolyte. The disturbance, a system zone, can move in some electrolyte systems along the separation channel and, on reaching the position of the detector, cause a system peak. As shown by the linear theory of electromigration based on linearized continuity equations formulated in matrix form, the mobility of the system zone--the system eigenmobility--can be obtained as the eigenvalue of the matrix. Progress in the theory of electromigration allows us to predict the existence and mobilities of the system zones, even in very complex electrolyte systems consisting of several multivalent weak electrolytes, or in micellar systems (systems with SDS micelles) used for protein sizing in microchips. The theory is implemented in PeakMaster software, which is available as freeware (www.natur.cuni.cz/gas). The linearized theory also predicts background electrolytes having no stationary injection zone (water zone, water gap, water dip, EO zone) or unstable electrolyte systems exhibiting oscillations and creating periodic structures. The oscillating systems have complex system eigenmobilities (eigenvalues of the matrix are complex). This paper reviews the theoretical background of the system peaks (system eigenpeaks) and gives practical hints for their prediction and for preparing background electrolytes not perturbed by the occurrence of system peaks and by excessive peak broadening.     

High-precision frequency measurements: indispensable tools at the core of the molecular-level analysis of complex systems

This perspective article provides an assessment of the state-of-the-art in the molecular-resolution analysis of complex organic materials. These materials can be divided into biomolecules in complex mixtures (which are amenable to successful separation into unambiguously defined molecular fractions) and complex nonrepetitive materials (which cannot be purified in the conventional sense because they are even more intricate). Molecular-level analyses of these complex systems critically depend on the integrated use of high-performance separation, high-resolution organic structural spectroscopy and mathematical data treatment. At present, only high-precision frequency-derived data exhibit sufficient resolution to overcome the otherwise common and detrimental effects of intrinsic averaging, which deteriorate spectral resolution to the degree of bulk-level rather than molecular-resolution analysis. High-precision frequency measurements are integral to the two most influential organic structural spectroscopic methods for the investigation of complex materials—NMR spectroscopy (which provides unsurpassed detail on close-range molecular order) and FTICR mass spectrometry (which provides unrivalled resolution)—and they can be translated into isotope-specific molecular-resolution data of unprecedented significance and richness. The quality of this standalone de novo molecular-level resolution data is of unparalleled mechanistic relevance and is sufficient to fundamentally advance our understanding of the structures and functions of complex biomolecular mixtures and nonrepetitive complex materials, such as natural organic matter (NOM), aerosols, and soil, plant and microbial extracts, all of which are currently poorly amenable to meaningful target analysis. The discrete analytical volumetric pixel space that is presently available to describe complex systems (defined by NMR, FT mass spectrometry and separation technologies) is in the range of 10^8–14 voxels, and is therefore capable of providing the necessary detail for a meaningful molecular-level analysis of very complex mixtures. Nonrepetitive complex materials exhibit mass spectral signatures in which the signal intensity often follows the number of chemically feasible isomers. This suggests that even the most strongly resolved FTICR mass spectra of complex materials represent simplified (e.g. isomer-filtered) projections of structural space.     

Kinetic performance limits of constant pressure versus constant flow rate gradient elution separations. Part II: experimental

We report on a first series of experiments comparing the selectivity and the kinetic performance of constant flow rate and constant pressure mode gradient elution separations. Both water-methanol and water-acetonitrile mobile phase mixtures have been considered, as well as different samples and gradient programs. Instrument pressures up to 1200 bar have been used. Neglecting some small possible deviations caused by viscous heating effects, the experiments could confirm the theoretical expectation that both operation modes should lead to identical separation selectivities provided the same mobile phase gradient program is run in reduced volumetric coordinates. Also in agreement with the theoretical expectations, the cP-mode led to a gain in analysis time amounting up to some 17% for linear gradients running from 5 to 95% of organic modifier at ultra-high pressures. Gains of over 25% were obtained for segmented gradients, at least when the flat portions of the gradient program were situated in regions where the gradient composition was the least viscous. Detailed plate height measurements showed that the single difference between the constant flow rate and the constant pressure mode is a (small) difference in efficiency caused by the difference in average flow rate, in turn leading to a different intrinsic band broadening. Separating a phenone sample with a 20-95% water-acetonitrile gradient, the cP-mode leads to gradient plate heights that are some 20-40% smaller than in the cF-mode in the B-term dominated regime, while they are some 5-10% larger in the C-term dominated regime. Considering a separation with sub 2-μm particles on a 350 mm long coupled column, switching to the constant pressure mode allowed to finish the run in 29 instead of in 35 min, while also a larger peak capacity is obtained (going from 334 in the cF-mode to 339 in the cP-mode) and the mutual selectivity between the different peaks is fully retained.     

Nonexistence of Marginally Trapped Surfaces and Geons in 2 + 1 Gravity

We use existence results for Jang’s equation and marginally outer trapped surfaces (MOTSs) in 2 + 1 gravity to obtain nonexistence of geons in 2 + 1 gravity. In particular, our results show that any 2 + 1 initial data set, which obeys the dominant energy condition with cosmological constant Λ ≥ 0 and which satisfies a mild asymptotic condition, must have trivial topology. Moreover, any data set obeying these conditions cannot contain a MOTS. The asymptotic condition involves a cutoff at a finite boundary at which a null mean convexity condition is assumed to hold; this null mean convexity condition is satisfied by all the standard asymptotic boundary conditions. The results presented here strengthen various aspects of previous related results in the literature. These results not only have implications for classical 2 + 1 gravity but also apply to quantum 2 + 1 gravity when formulated using Witten’s solution space quantization.     

Selectively N‐Protected Enantiopure 2,5‐Disubstituted Piperazines: Avoiding the Pitfalls in Solid‐Phase Fukuyama–Mitsunobu Cyclizations

Robust protocol! A diverse array of piperazine scaffolds was obtained by a robust solid‐phase‐synthesis protocol involving multistep elaboration of a resin‐bound aziridine (see scheme). Microwave‐assisted on‐resin protectinggroup introduction and manipulation as well as intramolecular Fukuyama–Mitsunobu cyclization conditions were key features.