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We describe a new tunable diode laser (TDL) absorption instrument, the Chicago Water Isotope Spectrometer, designed for measurements of vapor-phase water isotopologues in conditions characteristic of the upper troposphere [190–235 K temperature and 2–500 parts per million volume (ppmv) water vapor]. The instrument is primarily targeted for measuring the evolving ratio of HDO/H2O during experiments in the "Aerosol Interaction and Dynamics in the Atmosphere" (AIDA) cloud chamber. The spectrometer scans absorption lines of both H2O and HDO near the 2.64 µm wavelength in a single current sweep, increasing the accuracy of isotopic ratio measurements. At AIDA, the instrument is configured with a 256-m path length White cell for in situ measurements, and effective sensitivity can be augmented by enhancing the HDO content of chamber water vapor by an order of magnitude. The instrument has participated to date in the 2012–2013 IsoCloud campaigns studying isotopic partitioning during the formation of cirrus clouds and in the AquaVIT-II instrument intercomparison campaign. Realized precisions for 1-s measurements during these campaigns were 22 ppbv for H2O and 16 ppbv for HDO, equivalent to relative precisions of less than 0.5% for each species at 8 ppmv water vapor. The 1-s precision of the [HDO]/[H2O] ratio measurement ranged from 1.6‰ to 5.6‰ over the range of experimental conditions. H2O measurements showed agreement with calculated saturation vapor pressure to within 1% in conditions of sublimating ice and agreement with other AIDA instruments (the AIDA SP-APicT reference TDL instrument and an MBW 373LX chilled mirror hygrometer) to within 2.5% and 3.8%, respectively, over conditions suitable for all instruments (temperatures from 204 K to 234 K and H2O content equivalent to 15–700 ppmv at 200 hPa). [ABSTRACT FROM AUTHOR]

Microwave spectra of the propiolic acid-formic acid doubly hydrogen bonded complex were measured in the 1 GHz to 21 GHz range using four different Fourier transform spectrometers. Rotational spectra for seven isotopologues were obtained. For the parent isotopologue, a total of 138 a-dipole transitions and 28 b-dipole transitions were measured for which the a-dipole transitions exhibited splittings of a few MHz into pairs of lines and the b-type dipole transitions were split by ∼580 MHz. The transitions assigned to this complex were fit to obtain rotational and distortion constants for both tunneling levels: A0+ = 6005.289(8), B0+ = 930.553(8), C0+ = 803.9948(6) MHz, Δ0+J = 0.075(1), Δ0+JK = 0.71(1), and δ0+j = -0.010(1) kHz and A0- = 6005.275(8), B0- = 930.546(8), C0- = 803.9907(5) MHz, Δ0-J = 0.076(1), Δ0-JK = 0.70(2), and δ0-j = -0.008(1) kHz. Double resonance experiments were used on some transitions to verify assignments and to obtain splittings for cases when the b-dipole transitions were difficult to measure. The experimental difference in energy between the two tunneling states is 291.428(5) MHz for proton-proton exchange and 3.35(2) MHz for the deuterium-deuterium exchange. The vibration-rotation coupling constant between the two levels, Fab, is 120.7(2) MHz for the proton-proton exchange. With one deuterium atom substituted in either of the hydrogen-bonding protons, the tunneling splittings were not observed for a-dipole transitions, supporting the assignment of the splitting to the concerted proton tunneling motion. The spectra were obtained using three Flygare-Balle type spectrometers and one chirped-pulse machine at the University of Virginia. Rotational constants and centrifugal distortion constants were obtained for HCOOH···HOOCCCH, H13COOH···HOOCCCH, HCOOD···HOOCCCH, HCOOH···DOOCCCH, HCOOD···DOOCCCH, DCOOH···HOOCCCH, and DCOOD···HOOCCCH. High-level ab initio calculations provided initial rotational constants for the complex, structural parameters, and some details of the proton tunneling potential energy surface. A least squares fit to the isotopic data reveals a planar structure that is slightly asymmetric in the OH distances. The formic OH···O propiolic hydrogen bond length is 1.8 Å and the propiolic OH···O formic hydrogen bond length is 1.6 Å, for the equilibrium configuration. The magnitude of the dipole moment was experimentally determined to be 1.95(3) × 10-30 C m (0.584(8) D) for the 0+ states and 1.92(5) × 10-30 C m (0.576(14) D) for the 0- states. [ABSTRACT FROM AUTHOR]

High-altitude cirrus clouds are climatically important: their formation freeze-dries air ascending to the stratosphere to its final value, and their radiative impact is disproportionately large. However, their formation and growth are not fully understood, and multiple in situ aircraft campaigns have observed frequent and persistent apparent water vapor supersaturations of 5 %–25 % in ultracold cirrus (T<205 K), even in the presence of ice particles. A variety of explanations for these observations have been put forth, including that ultracold cirrus are dominated by metastable ice whose vapor pressure exceeds that of hexagonal ice. The 2013 IsoCloud campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud and aerosol chamber allowed explicit testing of cirrus formation dynamics at these low temperatures. A series of 28 experiments allows robust estimation of the saturation vapor pressure over ice for temperatures between 189 and 235 K, with a variety of ice nucleating particles. Experiments are rapid enough (∼10 min) to allow detection of any metastable ice that may form, as the timescale for annealing to hexagonal ice is hours or longer over the whole experimental temperature range. We show that in all experiments, saturation vapor pressures are fully consistent with expected values for hexagonal ice and inconsistent with the highest values postulated for metastable ice, with no temperature-dependent deviations from expected saturation vapor pressure. If metastable ice forms in ultracold cirrus clouds, it appears to have a vapor pressure indistinguishable from that of hexagonal ice to within about 4.5 %. [ABSTRACT FROM AUTHOR]

A large pulsed-beam, Fourier transform microwave spectrometer employing 48 in. diameter mirrors and 35″ (NHS-35) diffusion pump has been constructed at the University of Arizona. The Fabry-Perot-type cavity, using the large mirrors provides Q-values in the 15 000 to 40 000 range. Test spectra were obtained using transverse and coaxial injection of the pulsed-nozzle molecular beams. The measured molecular resonance linewidths were 8 kHz for the transverse injection and 2 kHz for coaxial molecular beam injection. Good signal to noise ratios were obtained for the test signals. Strong lines for butadiene iron tricarbonyl were seen with a single beam pulse (S/N = 5/1). Transitions were measured as low as 900 MHz and some previously unresolved hyperfine structure is now resolved for the butadiene iron tricarbonyl spectra. The spectrometer is operated using a personal computer with LABVIEW programs, with provisions for automatic frequency scanning. The extended, low-frequency range of this spectrometer should make it very useful for making measurements on significantly larger molecules and complexes than have been previously studied. The improved resolution, in the coaxial beam mode, will allow better resolution of hyperfine structure. The large diffusion pump allows a higher beam pulse frequency to compensate for the generally lower sensitivity at lower frequencies. [ABSTRACT FROM AUTHOR]

In evolving toward the postindustrial society there is increasing need for the development of conceptual models based on system theoretic principles. Identification and measurement of system inputs, the dynamic behavior of identifiable subsystems, the appreciation of stochastic factors and overall system behavior are important not only to our political and professional social system managers, but also more generally to everyone in society. Our implicit aim is to plan for and to control the system so as to perform in a socially good way. However there remain major difficulties caused by the lack of data on which evaluations of societal functions can be based, and the limitations of existing system methodologies to deal with the full range of complexity in societal systems. In this paper the relationship between general systems theory and social systems is explored, including an introduction to the general system characteristics which seem basic to social systems. Emphasis is placed on the discussion of social indicators and social accounts in the system theoretic context, and the adaptibility of system and control concepts to the social environment. [ABSTRACT FROM AUTHOR]

The sound-pressure transformation of the pinna and the ear canal of the guinea pig has been measured in the frequency range 1-15 kHz. Below 1 kHz, the outer ear does not cause any significant modification in sound pressure. Between 3 and 10 kHz, the pinna provides a boost in pressure which can specifically be attributed to resonance in the concha. This boost, however, is dependent on the location of the sound source with respect to the pinna. The largest amplification is obtained when the speaker is pointed directly into the entrance of the ear canal. The acoustic behavior of the ear canal of the guinea pig is similiar to that of a rigid circular cylinder, open at both ends, about 9 mm long and 2.5 mm in diameter. The pressure transformation between the eardrum and the entrance to the ear canal is strongly dependent on the loading effect of the middle ear. Thus, experimentally induced changes in the impedance of the middle ear, and natural changes due to disease alter the sound transmission across the eardrum of this animal. In normal animals, the eardrum pressure is roughly 5 dB higher than the free-field pressure in the frequency range 1-10 kHz. This boost is attributed partly to the effects of the body and partly to the sound-pressure transformation by the outer ear. [ABSTRACT FROM AUTHOR]

A combination of mathematical modeling techniques and computer simulation methods has been used for the interpretation of the behavior of the experimentally observed cochlear potentials. In particular, the models of the mechano-acoustical system and of the electrical potential generating mechanism of the transducer cells have been derived in terms of state variables and of equivalent functional relationships, respectively. These formulations allow economical numerical solution of the complex equations which describe cochlear functions. Using these techniques we have been able to confirm that nonlinearity of the individual haircell output is compatible with the observed apparent linearity of the experimentally observed macroscopic CM (cochlear microphonic) potential and that effective low-pass filtering reduces distortion in the measured potential waveform due to the interaction of the electrical outputs of the haircells along the basilar membrane. This filtering is not influenced to a great extent by the attenuation along the cochlea. Further filtering may also be contributed by the RC networks formed by the various membrane capacitances and resistances. Comparison of the experimental and simulated CM vs SPL functions (frequency as parameter) shows that a simple phase cancellation process is not sufficient, but that an additional mechanism must be postulated to account for the decrease of the CM at very high sound intensities; the IHC (internal haircell) output is assumed to be 20 dB less sensitive than the OHC (outer haircell) output and of opposite sign. A similar comparison for the CM amplitude, CM phase, and SP- amplitude as functions of frequency (SPL as parameter) also provides good agreement. Our results demonstrate that the particular behavior of the basilar membrane and the interference effect between haircell outputs account for the majority of electrical phenomena observed by the classical differential electrode method. [ABSTRACT FROM AUTHOR]

Accurate frequency-response data for the cochlear potentials of the guinea pig were required for the description of the electrical events in the inner ear in terms of a mathematical model. Previously used methods did not ensure constancy of the input stimulus to the ear, and it was, therefore, necessary to monitor the sinusoidal-input amplitude and phase at the eardrum. Simultaneously, the cochlear microphonic potential (CM) amplitude and phase were measured over the frequency range 100-10 000 Hz, with differential electrodes inserted in three turns of the guinea pig's cochlea. The CM-amplitude versus frequency curves showed a 'tuning-curve' shape in general, but the exact shape of these curves was influenced by the location of the electrodes and the sound pressure level (SPL) used. The peak of the CM-amplitude versus frequency plots never appeared at frequencies higher than 2000 Hz owing to the 'low-pass' characteristics of the middle ear. The CM-phase versus frequency plots showed increasing phase lag, but there was relatively slow increase of the measured phase delay in the basal turn. Both these observations and the CM-amplitude measurements indicated that the electrodes picked up the CM from many potential generators that were not excited in phase and that interference between the outputs of the individual hair-cell generators occurred. [ABSTRACT FROM AUTHOR]

We have investigated the dependence of several anatomical parameters of the guinea-pig middle ear on body weight, and thus on age. In particular, the volumes of the tympanic and epitympanic cavities are found to increase with age, with the tympanic cavity growing somewhat more slowly. The mass of the incus appears to be independent of body weight. These results are important for establishing the values of parameters used in mathematical models of the middle ear. They are also relevant to theoretical considerations of the significance of middle-ear resonances. [ABSTRACT FROM AUTHOR]

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There appears to be a significant discrepancy between the results of Drescher and Eldredge [J. Acoust. Soc. Am. 56, 929-934 (1974)] and those reported by Sinyor and Laszlo on the transmission characteristics of the ear canal of the guinea pig. We suggest that this discrepancy is due mainly to the differences in the conditions of the middle ears of the guinea pigs at the time of measurement. Subject Classification: [43]65.24, [43]65.22. [ABSTRACT FROM AUTHOR]

Mathematical models of the peripheral auditory system have not so far described the cochlear microphonic (CM) potential. To gather suitable data, measurements were made of the CM potential as a function of frequency at various points along the basilar membrane for constant input sound-pressure level (SPL) at the eardrum. Differential electrodes were implanted in Turns 1 and 3 or Turns 1 and 2 of the cochlea. The exact location of the electrodes was determined from von Békésy's anatomical data and later confirmed histologically. The input was a continuous sine wave, and the frequency range extended from 100 to 9 Hz. The SPL was measured with a probe microphone just external to the eardrum in all experiments. The SPL was kept constant at 60 dB so as to ensure that the CM was in the linear intensity region for all frequencies of interest. The magnitude of the CM output was measured with a narrow-band analyzer. Plotting the CM versus frequency for constant SPL at the eardrum, we established the electrical tuning curves of the guinea-pig cochlea. These electrical tuning curves correspond to the mechanical tuning curves of the cochlea observed by von Békésy. [ABSTRACT FROM AUTHOR]