Torsion-rotation-vibration Effects In The V20, 2v21, 2v13 And V21+v13 States Of Ch3ch2cn

Ethyl cyanide, CH$_{3}$CH$_{2}$CN, is a highly abundant molecule in hot cores associated with massive star formation where temperatures often approach 200 K. Astrophysicists would like to use the many thousands of observed lines to evaluate thermal equilibrium, temperature distributions, heating sources, and radiative pumping effects. In spite of a recent partial success in characterizing the v$_{20}$ and v$_{12}$ vibrational states$^{a}$, many aspects of the spectroscopy of the v$_{20}$ state are not adequately characterized. Torsional splittings in the b-type spectrum of v$_{20}$ are typically a few MHz and many a-type transitions also show resolved torsional splittings, both are incompatible with the expected 1200 cm$^{-1}$ barrier to internal rotation in a v$_{t}$ = 0 state. Additionally all K values above 2 show some obvious perturbations. The three states that lie just above v$_{20}$ are 2v$_{21}$, 2v$_{13}$ and v$_{21}$ + v$_{13}$. It has been determined that v$_{20}$ interacts weakly with both 2v$_{21}$ and 2v$_{13}$ and that 2v$_{21}$ interacts weakly with 2v$_{13}$, in spite of their common symmetry and very close proximity. However, all the interactions of v$_{21}$ + v$_{13}$ appear to be very strong, making assignments of the combination band particularly problematic. The numerous interactions result in wide spread anomalous torsional splittings. These splittings provide valuable insight into the nature of the interactions, however without a reasonable model, assignment of A or E to a torsional component is far from obvious. There remains no reasonable quantum mechanical description of how to proceed with a torsion-rotation-vibration analysis involving large and small amplitude motions. We present what is known and unknown in this quartet of CH$_{3}$CH$_{2}$CN states. $^{a}$Daly, A. M., Berm\'{u}dez, C., L\'{o}pez, A., et al., 768, 1, ApJ, 201

THE BAND OF CH3CH2D FROM 770-880 cm_1

To extend the ethane database we recorded a 0.0028 wn resolution spectrum of chem{CH_3CH_2D} from 650 to 1500 wn using a Bruker IFS-125HR at the Jet Propulsion Laboratory. The 98% deuterium-enriched sample was contained in the 0.2038 m absorption cell; one scan was taken with the sample cryogenically cooled to 130 K and another at room temperature. From the cold data, we retrieved line positions and intensities of 8704 individual absorption features from 770 � 880 wn using a least squares curve fitting algorithm. From this set of measurements, we assigned 5041 transitions to the nub{17} fundamental at 805.3427686(234) wn; this band is a c-type vibration, with A and E components arising from internal rotation. The positions were modeled using a 22 term torsional Hamiltonian using SPFIT producing the A and E energy splitting of 5.409(25)x10$^{-3}$ wn (162.2(8) MHz) with a standard deviation of 7x10$^{-4}$ wn (21 MHz). The calculated line intensities at 130 K agree very well with retrieved intensities. To predict line intensities at different temperatures, the partition function value was determined at eight temperatures between 9.8 and 300 K by summing individual energy levels up to J = 99 and K$_{a}$ = 99 for the six states up through nub{17} at 805 wn. The resulting prediction of singly-deuterated ethane absorption at 12.5 $mu$m enables its detection in planetary atmospheres, including those of Titan and exoplanets

UPDATE OF THE ANALYSIS OF THE PURE ROTATIONAL SPECTRUM OF EXCITED VIBRATIONS OF CH3CH2CN

The torsion-vibration-rotation analysis of nearly degenerate vibrational states involving both small and large amplitude motion has escaped satisfactory quantum mechanical description. Unfortunately the interstellar medium is filled with many prevalent molecules that feature internal rotation that couples strongly with torsional bath states. Many excited states are observed in emission in hot cores associated with massive star formation and it is likely that absorption in the infrared will be seen by JWST. We present our progress on the analysis of the high resolution pure rotational spectrum of ethyl cyanide, CH$_{3}$CH$_{2}$CN, which is highly abundant in hot cores with massive star formation and can serve as a sensitive temperature and source size probefootnote{A.M. Daly, C. Bermﾜdez, A. Lﾗpez, B. Tercero, J.C. Pearson, N. Marcelino, J.L. Alonso, J. Cernicharo textit{Astrophys. J.}, textbf{768} 81 (2013)}. Although the ground state has been assigned to 1.6 THzfootnote{C.S. Brauer, J.C. Pearson, B.J. Drouin, S. Yu textit{ApJ Suppl. Ser.}, textbf{184} 133 (2009)}, the two vibrational states nub{13} and nub{21}, the C-C-N bend and torsion, have only been assigned up to 400 GHzfootnote{D.M. Mehringer, J.C. Pearson, J. Keene, T.G. Phillips textit{Astrophys. J.}, textbf{608} 306 (2004)}. It is clear that detailed understanding of excited states will help properly model the temperature dependence of the intensity. We will report the progress on the fit up to 1.5 THz for the states nub{13} , nub{21} , nub{20} and nub{12}, at 206.5 wn, 212 wn, 375 wn and 532 wn respectively. In spite of a nearly 1200 wn barrier to internal rotation all the vibrational states observed feature A/E splittings inconsistent with such a high barrier suggesting that there is extensive coupling between the torsional bath states and the excited vibrations. The low lying states of ethyl cyanide provide an opportunity to assess all the possible interaction under the C$_{S}$ group for both A and E symmetry in the high barrier case to serve as a benchmark for developing theory for the analysis of lower barrier cases

Additional measurements and analyses of H217O and H218O

Historically the analysis of the spectrum of water has been a balance between the quality of the data set and the applicability of the Hamiltonian to a highly non-rigid molecule. Recently, a number of different non-rigid analysis approaches have successfully been applied to $^{16}$O water resulting in a self-consistent set of transitions and energy levels to high J which allowed the spectrum to be modeled to experimental precisionfootnote{SS. Yu, J.C. Pearson, B.J. Drouin textit{et al. J. Mol. Spectrosc.} textbf{279},~16-25 (2012)}footnote{J. Tennyson, P.F. Bernath, L.R. Brown textit{et al. J. Quant. Spectrosc. Rad. Trans.} textbf{117}, 29-58 (2013)}. The data set for $^{17}$O and $^{18}$O water was previously reviewed and many of the problematic measurements identifiedfootnote{J. Tennyson, P.F. Bernath, L.R. Brown textit{et al. J. Quant. Spectrosc. Rad. Trans.} textbf{110}, 573-596 (2009)}, but Hamiltonian modeling of the remaining data resulted in significantly poorer quality fits than that for the $^{16}$O parent. As a result, we have made additional microwave measurements and modeled the existing $^{17}$O and $^{18}$O data sets with an Euler series modelfootnote{H.M. Pickett, J.C. Pearson, C.E. Miller textit{J. Mol. Spectrosc.} textbf{233}, 174-179 (2005)}. This effort has illuminated a number of additional problematic measurements in the previous data sets and has resulted in analyses of $^{17}$O and $^{18}$O water that are of similar quality to the $^{16}$O analysis. We report the new lines, the analyses and make recommendations on the quality of the experimental data sets

The millimeter and submillimeter wave spectrum of cis-methyl vinyl ether

Among the species of potential interstellar relevance, methyl vinyl ether (CH3OCH=CH2) is the simplest ether compound containing both alkyl and alkene functional groups. In order to facilitate its detection in the ISM, we have measured the millimeter and submillimeter wave spectra from 50 to 650 GHz. We present the analysis of pure rotational spectrum of the cis-methyl vinyl ether in the vibrational ground state and in the first excited states of in-plane bending mode (v16) and methyl (v23) and skeletal (v24) torsional modes. Coriolis and Fermi type interactions between the v24 = 1 and v23 = 1 states have been explicitly treated using an effective two-state Hamiltonian

Comprehensive analysis of prebiotic propenal up to 660 GHz

Since interstellar detection of propenal is only based on two rotational transitions in the centimeter wave region, its high resolution rotational spectrum has been measured up to 660 GHz and fully characterized by assignment of more than 12,000 transitions to provide direct laboratory data to the astronomical community. Spectral assignments and analysis include transitions from the ground state of the trans and cis isomers, three trans-13C isotopologues, and ten excited vibrational states of the trans form. Combining new millimeter and submillimeter data with those from the far-infrared region has yielded the most precise set of spectroscopic constants of trans-propenal obtained to date. Newly determined rotational constants, centrifugal distortion constants, vibrational energies, and Coriolis and Fermi interaction constants are given with high accuracy and were used to predict transition frequencies and intensities over a wide frequency range. Results of this work should facilitate astronomers further observation of propenal in the interstellar medium

Gas Phase Measurements of Mono-Fluoro-Benzoic Acids and the Dimer of 3-Fluoro-Benzoic Acid

The microwave spectrum of the mono-fluoro-benzoic acids, 2-fluoro-, 3-fluoro-, and 4-fluoro-benzoic acid have been measured in the frequency range of 4-14 GHz using a pulsed beam Fourier transform microwave spectrometer. Measured rotational transition lines were assigned and fit using a rigid rotor Hamiltonian. Assignments were made for 3 conformers of 2-fluorobenzoic acid, 2 conformers of 3-fluorobenzoic acid, and 1 conformer of 4-fluorobenzoic acid. Additionally, the gas phase homodimer of 3-fluorobenzoic acid was detected, and the spectra showed evidence of proton tunneling. Experimental rotational constants are A(0+) = 1151.8(5), B(0+) = 100.3(5), C(0+) = 87.64(3) MHz and A(0−) = 1152.2(5), B(0−) = 100.7(5), C(0−) = 88.85(3) MHz for the two ground vibrational states split by the proton tunneling motion. The tunneling splitting (ΔE) is approximately 560 MHz. This homodimer appears to be the largest carboxylic acid dimer observed with F-T microwave spectroscopy

Reply to : On powerful GWAS in admixed populations

Non peer reviewe

The genetics of virus particle shape in equine influenza A virus

Background Many human strains of influenza A virus produce highly pleomorphic virus particles that at the extremes can be approximated as either spheres of around 100 nm diameter or filaments of similar cross-section but elongated to lengths of many microns. The role filamentous virions play in the virus life cycle remains enigmatic. Objectives/Methods Here, we set out to define the morphology and genetics of virus particle shape in equine influenza A virus, using reverse genetics and microscopy of infected cells. Results and Conclusions The majority of H3N8 strains tested were found to produce filamentous virions, as did the prototype H7N7 A/eq/Prague/56 strain. The exception was the prototype H3N8 isolate, A/eq/Miami/63. Reassortment of equine influenza virus M genes from filamentous and non-filamentous strains into the non-filamentous human virus A/PR/8/34 confirmed that segment 7 is a major determinant of particle shape. Sequence analysis identified three M1 amino acid polymorphisms plausibly associated with determining virion morphology, and the introduction of these changes into viruses confirmed the importance of two: S85N and N231D. However, while either change alone affected filament production, the greatest effect was seen when the polymorphisms were introduced in conjunction. Thus, influenza A viruses from equine hosts also produce filamentous virions, and the major genetic determinants are set by the M1 protein. However, the precise sequence determinants are different to those previously identified in human or porcine viruses

Contribution of glycogen in supporting axon conduction in the peripheral and central nervous systems: the role of lactate

The role of glycogen in the central nervous system is intimately linked with the glycolytic pathway. Glycogen is synthesized from glucose, the primary substrate for glycolysis, and degraded to glucose-6-phosphate. The metabolic cost of shunting glucose via glycogen exceeds that of simple phosphorylation of glucose to glucose-6-phosphate by hexokinase; thus, there must be a metabolic advantage in utilizing this shunt pathway. The dogmatic view of glycogen as a storage depot persists, based on initial descriptions of glycogen supporting neural function in the face of aglycemia. The variable latency to conduction failure, dependent upon tissue glycogen levels, provided convincing evidence of the role played by glycogen in supporting neural function. Glycogen is located predominantly in astrocytes in the central nervous system, thus for glycogen to benefit neural elements, intercellular metabolic communication must exist in the form of astrocyte to neuron substrate transfer. Experimental evidence supports a model where glycogen is metabolized to lactate in astrocytes, with cellular expression of monocarboxylate transporters and enzymes appropriately located for lactate shuttling between astrocytes and neural elements, where lactate acts as a substrate for oxidative metabolism. Biosensor recordings have demonstrated a significant steady concentration of lactate present on the periphery of both central white matter and peripheral nerve under unstimulated baseline conditions, indicating continuous cellular efflux of lactate to the interstitium. The existence of this lactate pool argues we must reexamine the “on demand” shuttling of lactate between cellular elements, and suggests continuous lactate efflux surplus to immediate neural requirements