Robert Frank

Respiratory Uptake of Ozone in Dogs

We measured the uptake of ozone by the surgically isolated upper airways in 11 anesthetized, paralyzed, mechanically ventilated dogs. The gas was administered either by nose or mouth, each exposure lasting 20 to 30 minutes. The relative uptake of O3 was found to be inversely related to concentration and flow rate, and was higher nasally than orally. Changes in nasal flow resistance, induced by aerosols of histamine and phenylephrine (Neo-Synephrine) hydrochloride, had little effect on the process. The removal of O3 from inspired air by the lower airways and parenchyma was measured in five additional dogs that were mechanically ventilated through a tracheal cannula. The concentration ranged from 20 to 85 pphm, the tidal volume was constant, and the pump frequently was either 20 or 30 cycles per minute. Under these circumstances, the rate of uptake varied between 80% and 87%.

Primitive C‐Command

Work in syntactic theory almost universally assumes that hierarchy in syntactic structure is characterized in terms of an abstract primitive relation of dominance. In this paper, we suggest that hierarchy should instead be determined via a primitive c-command relation. This perspective turns out to restrict the range of possible syntactic structures in a linguistically natural way, deriving restrictions on possible configurations that must otherwise be stipulated. Furthermore, we show that a primitive c-command view of syntactic structure provides the basis for a radically simplified conception of adjunction structure, one that not only allows us to understand why the adjunction operation exists alongside substitution, but also explains why these operations have their distinctive structural and derivational properties.

Inhalation of acid coated carbon black particles impairs alveolar macrophage phagocytosis

A flow-past nose-only inhalation system was used for the co-exposure of mice to carbon black aerosols (CBA) and sulfur dioxide (SO2) at varying relative humidities (RH). The conversion of SO2 to sulfate (SO4(-2)) on the CBA, at a fixed aerosol concentration, was dependent on RH and SO2 concentration. The effect of the aerosol-gas mixture on alveolar macrophage (AM) phagocytosis was assessed three days following exposure for 4 h. Exposure to 10 mg/m3 CBA alone at low RH (10%) and high RH (85%), to 10 ppm SO2 alone at both RH, and to the mixture at low RH had no effect on AM phagocytosis. In contrast, AM phagocytosis was significantly suppressed following co-exposure at 85% RH, the only circumstance in which significant chemisorption of the gas by the aerosol and oxidation to SO4(-2) occurred. The results suggest that fine carbon particles can be an effective vector for the delivery of toxic amounts of SO4(-2) to the periphery of the lung.

Structural complexity and the time course of grammatical development

One traditional view of the time course of language acquisition holds that a childs difficulties in learning her language are due to general processing, memory or conceptual limitations. As the childs cognitive capacities expand, so do her abilities to use her already-acquired grammar or to recognize additional properties of her soon-to-be native language. Recent work in the study of child language, however, has discovered the existence of a number of characteristic stages, transitions between which are best described in the terms of linguistic theory proper. These stages are surprising under a view of language acquisition according to which developmental delay derives from general cognitive limitations, which cannot characterize difficulties explicable only in language-specific terms. At the same time, current linguistic theories so severely restrict the variation among possible human grammars that there remains little reason why there should be any learning problem at all or characteristic developmental stages. In this paper, I propose that these two views can be reconciled. I show that childrens difficulties with a wide range of syntactic constructions, which are indeed best defined in linguistic terms, should nonetheless be derived from limitations on the childs ability to deal with processing load and formal representational complexity. I suggest however that this can be done only in the context of a particular view of syntactic representation, one which is articulated in the terms of the formal system of tree adjoining grammar (TAG). I demonstrate how precisely those difficulties that children experience in the acquisition of relative clauses, adjectival modification, control constructions, raising, wh-questions and the obligatoriness of finite inflection can be traced to the complexity associated with one of the TAG combinatory operations, adjoining. This proposal relates this apparently disparate set of constructions in a novel way and provides us with a new type of explanation for the time course of syntactic development in terms of the complexity of formal grammatical devices.

INHALED PARTICLE-BOUND SULFATE: Effects on Pulmonary Inflammatory Responses and Alveolar Macrophage Function

Acid sulfate-coated solid particles are a significant environmental hazard produced primarily by the combustion of fossil fuels. We have previously described a system for the nascent generation of carbonaceous particles surface coated with approximately 140 mug/ m3 acid sulfate [cpSO42-; 10 mg/m3 carbon black (CB) and 10 ppm sulfur dioxide (SO2) at 85% relative humidity (RH)]. The effects of inhaled cpSO42- on pulmonary host defenses are assessed in the present work. Mice were acutely exposed (4 h) to either 10 mg/m3 CB, 10 ppm SO2, or their combination at 10% or 85% RH in a nose-only inhalation chamber. No evidence of an inflammatory response was found following any of the exposures as assessed by total cell counts and differential cell counts from bronchoalveolar lavage fluid. However, alveolar macrophage Fc receptor-mediated phagocytosis decreased only following exposure to 140 mug cpSO42-, significant suppression occurred after 24 h, maximal suppression occurred at 3 days postexposure, and recovery to preexposure levels required 7-14 days. Intrapulmonary bactericidal activity (IBA) was also suppressed only after exposure to 140 mug cpSO42-; suppression was maximal at 1 day postexposure and recovered by day 7. To assess the effects of lower cpSO42- concentrations, mice were repeatedly exposed to 1 mg/m3 CB and 1 ppm SO2 at 85% RH (20 mug/m3 cpSO42- for 4 h/day) for up to 6 days. A significant decrement in IBA was observed following 5 and 6 days of exposure. These studies indicated that acute or repeated exposure to cpSO42- could alter pulmonary host defense mechanisms.Acid sulfate-coated solid particles are a significant environmental hazard produced primarily by the combustion of fossil fuels. We have previously described a system for the nascent generation of carbonaceous particles surface coated with approximately 140 microg/m(3) acid sulfate [cpSO(4)(2-); 10 mg/m(3) carbon black (CB) and 10 ppm sulfur dioxide (SO(2)) at 85% relative humidity (RH)]. The effects of inhaled cpSO(4)(2-) on pulmonary host defenses are assessed in the present work. Mice were acutely exposed (4 h) to either 10 mg/m(3) CB, 10 ppm SO(2), or their combination at 10% or 85% RH in a nose-only inhalation chamber. No evidence of an inflammatory response was found following any of the exposures as assessed by total cell counts and differential cell counts from bronchoalveolar lavage fluid. However, alveolar macrophage Fc receptor-mediated phagocytosis decreased only following exposure to 140 microg cpSO(4)(2-), significant suppression occurred after 24 h, maximal suppression occurred at 3 days postexposure, and recovery to preexposure levels required 7-14 days. Intrapulmonary bactericidal activity (IBA) was also suppressed only after exposure to 140 microg cpSO(4)(2-); suppression was maximal at 1 day postexposure and recovered by day 7. To assess the effects of lower cpSO(4)(2-) concentrations, mice were repeatedly exposed to 1 mg/m(3) CB and 1 ppm SO(2) at 85% RH ( approximately 20 microg/m(3) cpSO(4)(2-) for 4 h/day) for up to 6 days. A significant decrement in IBA was observed following 5 and 6 days of exposure. These studies indicated that acute or repeated exposure to cpSO(4)(2-) could alter pulmonary host defense mechanisms.

The Head Dome: A Simplified Method for Human Exposures to Inhaled Air Pollutants

Acute controlled exposures of human subjects to air pollutants are customarily carried out with whole-body chambers, masks, or mouthpieces. The use of these methods may be limited by cost or technical considerations. To permit a study involving a highly unstable pollutant, artificial acid fog, administered to subjects during natural breathing, a head-only exposure chamber, called a head dome, was developed. It consists of a transparent cylinder with a neck seal which fits over the subjects head and rests lightly on his shoulders. The head dome does not constrain the upper airways or impede exercise on a bicycle ergometer. Ventilation can be monitored accurately and unobtrusively with a pneumotachograph at the exhaust port of the dome. A thermocouple may be used to monitor the onset and persistence of oronasal breathing. For short-term exposures to unstable or reactive pollutants lasting up to several hours, the head dome is an effective alternative to a whole-body chamber and probably superior to a face mask or mouthpiece.

Factors Governing the Mass Loading of Aerosolized Carbon Black Particles with Acid Sulfates, Inhalation Exposure, and Alveolar Macrophage Phagocytic Function

AbstractA flow-past nose-only inhalation system is described for the coexposure of animals to carbon black aerosols (CBA) and sulfur dioxide (SO2) at varying relative humidities (RH). The conversion of (SO2 to sulfate (SO42-) on the CBA, at a fixed aerosol concentration, was dependent on RH and SO2 concentration. The effect of the aerosol-gas mixture on alveolar macrophage (AM) phagocytosis was assessed 3 days following nose-only exposure of mice for 4 h. Exposure to 10 mg/m3 CBA alone at low RH (10%) and high RH (85%), to 10 ppm SO2 alone at both RH, and to the mixture at low RH had no effect on AM phagocytosis. In contrast, AM phagocytosis was significantly suppressed following coexposure at 85% RH, the only circumstance in which significant chemisorption of the gas and oxidation to SO42- occurred. The results suggest that fine carbon particles are an effective vector for the delivery of toxic amounts of SO42- to the periphery of the lung under conditions of elevated RH.

A Method for Assessing Small Airways Independent of Inspiratory Capacity

Reduced forced vital capacity may confound assessment of small-airway function. In 17 healthy and 16 asthmatic volunteers, we validated a method for measuring mean expiratory flow during the middle half of the forced vital capacity, mean expiratory flow during the third quarter of the forced vital capacity, instantaneous forced expiratory flow at 50% of forced vital capacity , and instantaneous expiratory flow at 75% of forced vital capacity. These measurements were conducted at the same absolute lung volume (isovolume) when forced vital capacity was reduced voluntarily to 100%, 85%, and 75% of maximum, and the variances, expressed as the coefficients of variations, were compared. Absolute lung volumes above residual volume were determined with two reference spirograms: 100% and 75% forced vital capacity. In normals, means of flow rates at the same absolute lung volume did not differ with the three forced vital capacities, regardless of whether the 100% or 75% forced vital capacity served as the reference spirogram. Reduced forced vital capacity among asthmatics was associated with modest increases in isovolume flow rates, an effect that may underestimate airway narrowing. Intrasubject variability was least among volume-averaged flow rates (e.g., mean expiratory flow during the middle half of the forced vital capacity). Volume-adjusted flow rates can be used to assess small-airways narrowing when forced vital capacity is reduced, and volume-averaged rates provide the least variability.

Monotonic C-Command: A New Perspective on Tree Adjoining Grammar

In this paper we argue for a reconceptualization of the Tree Adjoining Grammar (TAG) formalism, in which the elementary structures are collections of c-command relations, and the combinatory operation is substitution. We show how the formalism we sketch resolves a number of problems for TAG that have been identified in the literature. Additionally, we demonstrate that our proposal is preferable to other previously proposed extensions to TAG, for example D-tree grammars (Rambow et al., 1995), in that it preserves many of the linguistically desirable aspects of TAGs restrictiveness, specifically concerning the derivation of locality constraints on unbounded dependencies.

Acute Exposure to Acid Fog: Influence of Breathing Pattern on Effective Dose

Concern about the possible adverse health effects of acid fog has been fed by two observations: air pollution disasters earlier in this century were typically associated with fog, and current samples of fog water can be strongly acid. To study the acute effects of acid fog on the lung, the authors generated a monodisperse 10 microM MMAD aerosol of H2SO4 with a pH of 2.0 and a nominal concentration of 500 micrograms/m3. They exposed seven healthy young men on alternate days to acid or control equiosmolar NaCl aerosol during 40 min of resting ventilation and 20 min of exercise; the latter was sufficiently intense to induce oronasal breathing. Exposure was by means of a head dome, a head-only exposure device that permitted continuous measurement (unfettered breathing) of Vr, f, VE, and the onset and persistence of oronasal breathing. In this article the authors compare the relative importance of parameters contributing to the between-subject variability in estimated hydrogen ion dose to the lower airways (H+LAW), based on analysis of variance. Physiologic parameters accounted for 70% of the variability, of which 34% was due to differences in duration of oronasal breathing (tON) and 36% to differences in ventilation rate during oronasal breathing (VE(ON)); inhaled hydrogen ion concentration [H+], the environmental parameter, contributed only 30%. Minute ventilation at the time of transition from nasal to oronasal breathing varied significantly among subjects even if normalized to FVC, an index of lung size.