Search

The AquaVIT-1 intercomparison of atmospheric water vapor measurement techniques was conducted at the aerosol and cloud simulation chamber AIDA (Aerosol Interaction and Dynamics in the Atmosphere) at the Karlsruhe Institute of Technology, Germany, in October 2007. The overall objective was to intercompare state-of-the-art and prototype atmospheric hygrometers with each other and with independent humidity standards under controlled conditions. This activity was conducted as a blind intercomparison with coordination by selected referees. The effort was motivated by persistent discrepancies found in atmospheric measurements involving multiple instruments operating on research aircraft and balloon platforms, particularly in the upper troposphere and lower stratosphere, where water vapor reaches its lowest atmospheric values (less than 10 ppm). With the AIDA chamber volume of 84m3, multiple instruments analyzed air with a common water vapor mixing ratio, by extracting air into instrument flow systems, by locating instruments inside the chamber, or by sampling the chamber volume optically. The intercomparison was successfully conducted over 10 days during which pressure, temperature, and mixing ratio were systematically varied (50 to 500 hPa, 185 to 243 K, and 0.3 to 152 ppm). In the absence of an accepted reference instrument, the absolute accuracy of the instruments was not established. To evaluate the intercomparison, the reference value was taken to be the ensemble mean of a core subset of the measurements. For these core instruments, the agreement between 10 and 150 ppm of water vapor is considered good with variation about the reference value of about ±10% (±1σ). In the region of most interest between 1 and 10 ppm, the core subset agreement is fair with variation about the reference value of ±20% (±1σ). The upper limit of precision was also derived for each instrument from the reported data. The implication for atmospheric measurements is that the substantially larger differences observed during in-flight intercomparisons stem from other factors associated with the moving platforms or the non-laboratory environment. The success of AquaVIT-1 provides a template for future intercomparison efforts with water vapor or other species that are focused on improving the analytical quality of atmospheric measurements on moving platforms. [ABSTRACT FROM AUTHOR]

Based on animal experiments conducted in the sixteenth century by Vesalius, the Royal Humane Society recommended fireside bellows to resuscitate victims of drowning. In the mid-twentieth century, the bellows concept was adapted by Kreiselman and others, though none of these devices gained widespread popularity. However in 1957 the "Ambu Bag" appeared and was an immediate success. The revolutionary design was the creation of Danish anaesthetist Dr Henning Ruben. A similar product was soon developed by Asmund Laerdal of Norway, in collaboration with American anaesthesiologists Drs Elam and Safar. The self-inflating bag is such a simple device, yet it is extremely effective--it has enabled rescuers around the world to support life in virtually any environment, simply by squeezing a bag. [ABSTRACT FROM AUTHOR]

The article describes the evolution of self-inflating resuscitator. The author states that the idea started with experiments on animals that enabled Andreas Vesalius to demonstrate the use of fireside bellows to revive animals in the sixteen century. The author adds that the Royal Humane Society recommended self-inflating resuscitator for drowning victims. In 1957, Danish doctor Henning Ruben developed the Ambu Bag which paved way to the creation of a self-inflating bag.

The article discusses the history and evolution of the self-inflating bag, a device that has enabled rescuers to support life in practically any environment by simply squeezing a bag. Sixteenth century animal experiments conducted by Vesalius led the Royal Humane Society to recommend fireside bellows to resuscitate drowning victims. Danish anesthetist Henning Ruben introduced the Ambu Bag in 1957, which was an immediate success. Soon after, a similar product was created by Norway's Åsmund Laerdal with American anesthesiologists.

We have developed a chemical ionization mass spectrometry technique for precise in situ measurements of hydrochloric acid (HCl) from a high-altitude aircraft. In measurements at subtropical latitudes, minimum HCl values found in the upper troposphere (UT) were often near or below the detection limit of the measurements (0.005 parts per billion by volume), indicating that background HCl values are much lower than a global mean estimate. However, significant abundances of HCl were observed in many UT air parcels, as a result of stratosphere-to-troposphere transport events. We developed a method for diagnosing the amount of stratospheric ozone in these UT parcels using the compact linear correlation of HCl with ozone found throughout the lower stratosphere (LS). Expanded use of this method will lead to improved quantification of cross-tropopause transport events and validation of global chemical transport models. [ABSTRACT FROM AUTHOR]

Background: The movement of public health professionals from health authorities to primary care trusts has increased their isolation and dependence on public health networks for communication. Methods: A cross sectional survey of 60 public health professionals working in England was performed to determine their understanding of the term "public health network" and to explore the functions that they would like these networks to perform. It also assessed their attitudes towards a national network and towards individual, local, and national web sites to support these networks. Results: The most popular functions were the support of CPD/education, the identification of expertise and maximization of scarce resources, information sharing, and efficient information/knowledge management. The local and national networks and their web sites should provide information on current projects of the network and searches to identify people, expertise, and reports. Conclusion: Public health professionals have a similar but broader understanding of the term "public health network" than that of the government with greater emphasis on sharing of information. The network is more likely to be successful if its priorities are maximizing scarce resources, identification of expertise, CPD/education, and knowledge management. [ABSTRACT FROM AUTHOR]

A letter to the editor about the failure of an infant Laerdal self-inflating resuscitator is presented.

In situ measurements of [OH], [HO] (square brackets denote species concentrations), and other chemical species were made in the tropical upper troposphere (TUT). [OH] showed a robust correlation with solar zenith angle. Beyond this dependence, however, [OH] did not correlate to its primary source, the product of [O] and [HO] ([O]•[HO]), or its sink [NO]. This suggests that [OH] is heavily buffered in the TUT. One important exception to this result is found in regions with very low [O], [NO], and [NO]. Under these conditions, [OH] is highly suppressed, pointing to the critical role of NO in sustaining OH in the TUT and the possibility of low [OH] over the western Pacific warm pool due to strong marine convections bringing NO-poor air to the TUT. In contrast to [OH], [HO] ([OH] + [HO]) correlated reasonably well with [O]•[HO]/[NO], suggesting that [O]•[HO] and [NO] are the significant source and sink, respectively, of [HO]. [ABSTRACT FROM AUTHOR]

Little research has been carried out on the agronomic and economic value of compost produced from garden organics for vegetable production. A field experiment was established in Camden, near Sydney, Australia (i) to evaluate the effect of the compost on vegetable production (ii) and to evaluate the economic returns from using compost in vegetable production. A total of five vegetable crops were grown and the results indicated that a once only application of compost at an agronomic rate of nitrogen (125 t/ha) produced similar or higher vegetable yields than that of current farmer's practice. For four of the five crops grown, yield was similar, and for one of the crops (capsicum), compost treatment yielded 21% higher than that of the farmers' practice. In addition to soil health benefits, using compost at this rate also resulted in considerable saving of chemical fertilisers. Over the period of the experimental trial, there was a 36% saving in urea as well as 100% saving in P and K fertilisers. For the Mixed treatment (compost at half rate and supplemented by chemical fertilisers), vegetable yield was similar to that of the farmers' practice for the first four crops but this declined to only 64% of that of the farmers' practice for the final crop of leek. Benefit cost analyses showed that for the vegetable compost trial, application of compost provided a benefit cost ratio (BCR) of 1 after five vegetable crops, indicating that this practice was very close to breaking even. On the other hand, BCR of Mix treatment (compost at half rate and supplemented by inorganic fertiliser) was negative due to significant yield decline after growing four crops. [ABSTRACT FROM AUTHOR]

In situ measurements of the relative humidity with respect to ice (RH[subo]) and of nitric acid (HNO[sub3]) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RH[subi] values show a sharp increase to average values of over 130% in both cloud types. These enhanced RH[subi] values are attributed to the presence of a new class of HNO[sub3]-containing ice particles (Δ-ice). We propose that surface HNO[sub3] molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Δ-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Δ-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor. [ABSTRACT FROM AUTHOR]

A light-weight, low-cost optical particle spectrometer for measurements of aerosol number concentrations and size distributions has been designed, constructed, and demonstrated. The spectrometer is suitable for use on small, unmanned aerial vehicles (UAVs) and in balloon sondes. The spectrometer uses a 405 nm diode laser to count and size individual particles in the size range 140–3000 nm. A compact data system combines custom electronics with a single-board commercial computer. Power consumption is 7W at 9–15 V. 3D printing technology was used in the construction of the instrument to reduce cost, manufacturing complexity, and weight. The resulting Printed Optical Particle Spectrometer (POPS) instrument weighs about 800 g with an approximate materials cost of 2500 USD. Several POPS units have been constructed, tested in the laboratory, and deployed on UAVs. Here we present an overview of the instrument design and construction, laboratory validation data, and field engineering data for POPS. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor and its response regarding effect of nitric acid on humidity in low-temperature clouds.

Global-scale atmospheric measurementsare used to investigate theeffectiveness of recent adjustments to production and consumptioncontrols on hydrochlorofluorocarbons (HCFCs) under the Montreal Protocolon Substances that Deplete the Ozone Layer (Montreal Protocol) andto assess recent projections of large increases in hydrofluorocarbon(HFC) production and emission. The results show that aggregate globalHCFC emissions did not increase appreciably during 2007–2012and suggest that the 2007 Adjustments to the Montreal Protocol playeda role in limiting HCFC emissions well in advance of the 2013 capon global production. HCFC emissions varied between 27 and 29 kt CFC-11-equivalent(eq)/y or 0.76 and 0.79 GtCO2-eq/y during this period.Despite slower than projected increases in aggregate HCFC emissionssince 2007, total emissions of HFCs used as substitutes for HCFCsand chlorofluorocarbons (CFCs) have not increased more rapidly thanrates projected [Velders, G. J. M.; Fahey, D. W.; Daniel, J. S.; McFarland,M.; Andersen, S. O. The Large Contribution of Projected HFC Emissionsto Future Climate Forcing. Proc. Natl. Acad. Sci. U.S.A.2009, 106, 10949−10954] for2007–2012. HFC global emission magnitudes related to this substitutiontotaled 0.51 (−0.03, +0.04) GtCO2-eq/y in 2012,a magnitude about two times larger than emissions reported to theUnited Nations Framework Convention on Climate Change (UNFCCC) forthese HFCs. Assuming accurate reporting to the UNFCCC, the resultsimply that developing countries (non-Annex I Parties) not reportingto the UNFCCC now account for nearly 50% of global HFC emissions usedas substitutes for ozone-depleting substances (ODSs). Global HFC emissions(as CO2-eq) from ODS substitution can be attributed approximatelyequally to mobile air conditioning, commercial refrigeration, andthe sum of all other applications. [ABSTRACT FROM AUTHOR]

Measurements of surface ozone (O), nitrogen oxides (NO = NO + NO), carbon monoxide (CO), and dew point were made at Qinghai Lake (QHL), China, a basin in the remote Tibetan Plateau area, in October 2010 and October 2011. The O mixing ratio was found to be high with average of 41 ± 9 ppb in October 2010 and 57 ± 10 ppb in October 2011. The observed diurnal pattern of O mixing ratio was characterized by a minimum between 07:00 and 10:00 local standard time (LST) increasing ~20 ppb to a broad peak occurring between 13:00 and 18:00 LST. This diurnal pattern differs substantially from that observed at WMO's GAW Baseline Observatory located above the basin on Mount Waliguan, ~130 km southeast of QHL. The elevated O mixing ratios observed in the afternoon are attributed to in situ photochemical production in the air trapped in the QHL basin by surrounding mountains. The low O mixing ratios observed in the morning are most likely due to surface removal in a shallow nocturnal boundary layer. The data indicate substantial impacts of pollution on air quality even in this remote area. The high O values observed in 2011 may cause observable damage to the vegetation, adding stress to an ecosystem ready under the threat of desertification. [ABSTRACT FROM AUTHOR]

The majority of airborne aerosol measurements employ forward-facing inlets with near-isokinetic sampling; these inlets have known artifacts when sampling in clouds such that data taken in cloud must typically be discarded. Here we report first results from a perpendicular inlet for sampling interstitial submicron black-carbon (BC) containing aerosol. The inlet, consisting of a flat plate to stabilize flow prior to perpendicular sampling, was evaluated using a single particle soot photometer (SP2) aboard the NASA WB-57F aircraft during the Midlatitude Airborne Cirrus Properties Experiment (MACPEX) of 2011. The new inlet rejects large particles and is free of aerosol artifacts when sampling in ice clouds while allowing sampling of submicron BC-containing aerosol with the same unit efficiency as a validated isokinetic inlet, thus allowing for airborne sampling of interstitial BC aerosol. Copyright 2013 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

A chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O) at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS). A low-pressure flow of sample air passes through an ionization volume containing an -particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+) from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45 min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm, 10-6 mol mol-1) generated by Pt-catalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB- 57F high-altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1 s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hz ppm-1 at 3 ppm with a signal to noise ratio (2σ, 1 s) greater than 32. The total measurement uncertainty was 9 to 11 %, derived from the uncertainty in the in situ calibrations. [ABSTRACT FROM AUTHOR]

A chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O) at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS). A low-pressure flow of sample air passes through an ionization volume containing an α-particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+) from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm) generated by Ptcatalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB-57 high altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1-s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hzppm-1 at 3 ppm with a signal to noise ratio (2σ, 1-s) greater than 32. The total measurement uncertainty was 9 to 11%, derived from the uncertainty in the in situ calibrations. [ABSTRACT FROM AUTHOR]

The article presents a study that evaluates the performance of the Single Particle Soot Photometer (SP2) and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) in measuring the concentration of refractory black carbon (BC) in snow. It found that the SP2 can be used to measure the size distribution and mass concentration of BC in the snow. It suggests that estimates of BC mass concentration may be associated with significant underestimates of uncertainty.

The article focuses on the design and use of the new ultraviolet (UV) photometer for in situ measurement of atmospheric ozone (O 3) from research aircraft. It says that a polarization optical-isolator configuration is used to fold the UV-beam within the absorption cells. It also mentions that the photometer has high accuracy, fast sampling rate, and excellent precision.

The article presents a study which describes the design of an ultraviolet (UV) photometer instrument for the measurement of atmospheric ozone. The accuracy, sampling rate and precision of the instrument for research aircraft platforms are outlined. The inlet and exhaust configurations of the instrument for unmanned aircraft systems (UASs) are examined.

The article presents a study which assesses the measurement techniques in quantifying the concentration of refractory black carbon (BC) in snow samples. The comparison of the Single Particle Soot Photometer (SP2) and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) in the quantification of BC concentration is outlined. Underestimates of uncertainty in the measurement of BC concentration using SP2 or ISSW are investigated.

The article describes and evaluates a system for converting mixtures of hydrogen in air to water on heated platinum surface and generate low mixing ratio water standards. It states that the technique has proved to be accurate and can be used to produce a wide range of water vapor concentrations on demand easily and reliably. It details how the experiment was conducted which found a water standard that is reportedly expected to be appropriate for in situ-calibration of aircraft hygrometers.

The article presents a study which examines the method for in situ calibration of atmospheric hygrometers which uses catalytic oxidation of deuterium (H2) on a platinum (Pt) surface. The study develops catalytic conversion flow PT tubes and the Pt gauze rolled inside a tube. It is found out that the technique can produce accurate results and a wide range of water vapor concentrations.

A large fraction of atmospheric aerosols are derived from organic compounds with various volatilities. A National Oceanic and Atmospheric Administration (NOAA) WP-3D research aircraft made airborne measurements of the gaseous and aerosol composition of air over the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico that occurred from April to August 2010. A narrow plume of hydrocarbons was observed downwind of DWH that is attributed to the evaporation of fresh oil on the sea surface. A much wider plume with high concentrations of organic aerosol (>25 micrograms per cubic meter) was attributed to the formation of secondary organic aerosol (SOA) from unmeasured, less volatile hydrocarbons that were emitted from a wider area around DWH. These observations provide direct and compelling evidence for the importance of formation of SOA from less volatile hydrocarbons. [ABSTRACT FROM AUTHOR]

The article presents a study on the effect of nitric acid on frost point hyrgrometer performance. It offers information on chilled mirror hygrometers (CMH) which are used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. It discusses how the study was conducted wherein the potential interference of gas-phase nitric acid with frost point temperature measurements were examined. It also details the results of the study.

A single particle soot photometer (SP2) uses an intense laser to heat individual aerosol particles of refractory black carbon (rBC) to vaporization, causing them to emit detectable amounts of thermal radiation that are used to quantify rBC mass. This approach is well suited for the detection of the majority of rBC mass loading in the ambient atmosphere, which occurs primarily in the accumulation mode (∼ 1-300 fg-rBC/particle). In addition to operator choices about instrument parameters, SP2 detection of rBC number and/or mass can be limited by the physical process inherent in the SP2 detection technique — namely at small rBC mass or low laser intensities, particles fail to heat to vaporization, a requirement for proper detection. In this study, the SP2's ability to correctly detect and count individual flame-generated soot particles was measured at different laser intensities for different rBC particle masses. The flame-generated soot aerosol used for testing was optionally prepared with coatings of organic and non-organic material and/or thermally denuded. These data are used to identify a minimum laser intensity for accurate detection at sea level of total rBC mass in the accumulation mode (300 nW/(220-nm PSL)), a minimum rBC mass (∼ 0.7-fg rBC-mass corresponding to 90 nm volume-equivalent diameter) for near-unity number detection efficiency with a typical operating laser intensity (450 nW/(220-nm PSL)), and a methodology using observed color temperature to recognize laser intensity insufficient for accurate rBC mass detection. Additionally, methods for measurement of laser intensity using either laboratory or ambient aerosol are presented. [ABSTRACT FROM AUTHOR]

A Single-Particle Soot Photometer (SP2) detects black refractory or elemental carbon (EC) in particles by passing them through an intense laser beam. The laser light heats EC in particles causing them to vaporize in the beam. Detection of wavelength-resolved thermal radiation emissions provides quantitative information on the EC mass of individual particles in the size range of 0.2–1 μm diameter. Non-absorbing particles are sized based on the amount of light they scatter from the laser beam. The time series of the scattering signal of a non-absorbing particle is a Gaussian, because the SP2 laser is in the TEM00 mode. Information on the scattering properties of externally and internally mixed EC particles as detected by the SP2 is lost in general, because each particle changes size, shape, and composition as it passes through the laser beam. Thus, scattered light from a sampled EC particle does not yield a full Gaussian waveform. A method for determining the scattering properties of EC particles using a two-element avalanche photodiode (APD) is described here. In this method, the Gaussian scattering function is constructed from the leading edge of the scattering signal (before the particle is perturbed by the laser), the Gaussian width, and the location of the leading edge in the beam derived from the two-element APD signal. The method allows an SP2 to determine the scattering properties of individual EC particles as well as the EC mass. Detection of polystyrene latex spheres, well-characterized EC particles with and without organic coatings, and Mie scattering calculations are used to validate the method. [ABSTRACT FROM AUTHOR]

Accurate and reliable predictions and an understanding of future changes in the stratosphere are major aspects of the subject of climate change. Simulating the interaction between chemistry and climate is of particular importance, because continued increases in greenhouse gases and a slow decrease in halogen loading are expected. These both influence the abundance of stratospheric ozone. In recent years a number of coupled chemistry–climate models (CCMs) with different levels of complexity have been developed. They produce a wide range of results concerning the timing and extent of ozone-layer recovery. Interest in reducing this range has created a need to address how the main dynamical, chemical, and physical processes that determine the long-term behavior of ozone are represented in the models and to validate these model processes through comparisons with observations and other models. A set of core validation processes structured around four major topics (transport, dynamics, radiation, and stratospheric chemistry and microphysics) has been developed. Each process is associated with one or more model diagnostics and with relevant datasets that can be used for validation. This approach provides a coherent framework for validating CCMs and can be used as a basis for future assessments. Similar efforts may benefit other modeling communities with a focus on earth science research as their models increase in complexity. [ABSTRACT FROM AUTHOR]

During a campaign to study ozone loss mechanisms in the Arctic stratosphere (SOLVE), several instruments on NASA's ER-2 aircraft observed a very low number density (0.1 l-1) of large, nitric-acid-containing particles that form the polar stratospheric clouds (PSCs). For effective physical and chemical characterization of these particles, the measurements from these instruments have to be intercompared and integrated. In particular, proper interpretation requires knowledge of the sampling characteristics of the particles into the instruments. Here, we present the calculation of the sampling characteristics of the one of the instruments on the ER-2, the NOAA NOy instrument. This instrument sampled ambient particles and gas from two forward-facing inlets located fore and aft on a particle-separation housing (the football) and measured total NOy in the sample. In recent studies, ambient aerosol mass has been estimated by the difference of the measurements of the two inlets with the assumption that the rear inlet observations represent the gas-phase NOy and small particles and the front inlet samples represent gas-phase NOy and all particle sizes with varied efficiency (anisokinetic sampling). This knowledge was derived largely from semiempirical relations and potential flow studies of the housing. In our study, we used CFD simulations to model the compressible flow conditions and considered noncontinuum effects in calculating particle trajectories. Our simulations show that the blunt body housing the inlets has a strong and complex interaction with the flow and particles sampled by the two inlets. The simulations show that the front inlet characteristics are influenced by the effect of the blunt body on the upstream pressure field. The rear inlet sampling characteristics are influenced both by the shape and size of the inlet and its location on the blunt body. These interactions result in calculated inlet characteristics that are significantly different from previously assumed values. Analysis of the SOLVE data, considering the ambient conditions and the calculated inlet sampling characteristics, in conjunction with thermodynamic growth modeling of super-cooled ternary solution (STS) particles, provides validation of the CFD results. [ABSTRACT FROM AUTHOR]

A compact, light-weight, two-dimension translatable slit aperture is described. The slit dimensions are scalable, allowing for wide application. With all metal construction, the device would be suitable for high temperature degassing and vacuum compatible. Alternatively, the main structure may be printed using a 3D printer for rapid prototyping and/or lighter weight. The precision of the slit movement is 0.014 mm. [ABSTRACT FROM AUTHOR]