Production constraints on utterance-final consonant characteristics in babbling

In order to evaluate hypotheses regarding production constraints on final consonants in babbling, 721 utterance-final consonants produced by 6 infants in consonant-vowel-consonant (CVC) syllables were examined and compared with the preceding consonant in the CVC. Consistent with earlier studies, major patterns were observed for each of the three main consonantal properties--place and manner of articulation and voicing. These patterns included a strong tendency for final consonants to repeat the place of articulation of nonfinal consonants and a tendency for relatively more fricative, nasal and voiceless consonants to occur in final position than in nonfinal position. The high frequency with which final consonants shared place of articulation with the preceding consonant was considered to reflect 'frame dominance' or the tendency of a relatively constant mandibular cycle (the frame) to determine the structure of utterances with very little contribution from other active articulators. The manner and voicing effects were attributed to an overall terminal energy decrease in the vocal production system.     

Fourier Transform Infrared Emission Spectroscopy of the C4Delta-X4Phi, G4Phi-X4Phi, and G4Phi-C4Delta Systems of TiCl

The emission spectrum of TiCl has been investigated in the 3000-12 000 cm-1 region at high resolution using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a flowing mixture of TiCl4 and helium. The observed bands have been classified into three electronic transitions, C4Delta-X4Phi, G4Phi-X4Phi, and G4Phi-C4Delta. In the 3000-3500 cm-1 region, four bands with R heads at 3368.7, 3331.8, 3291.9, and 3243.4 cm-1 have been assigned as the 0-0 bands of the 1/2-3/2, 3/2-5/2, 5/2-7/2, and 7/2-9/2 subbands, respectively, of the C4Delta-X4Phi transition. To higher wavenumbers, four transitions with 0-0 R heads at 10 930.7, 10 921.3, 10 906.5, and 10 886.9 cm-1 have been assigned as the 3/2-3/2, 5/2-5/2, 7/2-7/2, and 9/2-9/2 subbands, respectively, of the G4Phi-X4Phi system of TiCl. Four additional bands with 0-0 R heads at 7568.8, 7596.4, 7622.2, and 7651.7 cm-1 have been identified as the 1/2-3/2, 3/2-5/2, 5/2-7/2, and 7/2-9/2 subbands of the G4Phi-C4Delta transition, respectively. A rotational analysis of a number of vibrational bands of these transitions has been obtained and molecular constants have been extracted. The lowest 4Phi state has been assigned as the ground state of TiCl, by analogy with our recent work on TiF (R. S. Ram and P. F. Bernath, J. Mol. Spectrosc., in press). The correspondence between the electronic states of TiCl, TiF, TiH, and Ti+ is also discussed. Copyright 1997 Academic Press. Copyright 1997Academic Press     

Sulfide inhibition of the methanogenic activity of granular sludge at various pH-levels

The effect of sulfide on the formation of methane from acetate in granular sludge originating from a UASB reactor has been determined using a new batch anaerobic toxicity assay. The assay is based on measurement of the methane concentration in the closed head space of a serum bottle, thus allowing operation at constant pH and without loss of sulfide via off-gases.

Sulfide toxicity appeared to be correlated with the free hydrogen sulfide concentration in the pH range 6.4–7.2. However this correlation did not hold at pH = 7.8–8.0. Free hydrogen sulfide concentrations leading to 50% inhibition were 250 mgS l⁻¹ in the pH range 6.4–7.2 and 90 mgS l⁻¹ at pH = 7.8–8.0.

The high tolerance for sulfide toxicity exhibited by the granular sludge can probably be attributed to the existence of a pH gradient in the sludge granules leading to an increased internal pH.     

Compositional Dependence of the Performance of Poly(p‐phenylene vinylene):Methanofullerene Bulk‐Heterojunction Solar Cells

The dependence of the performance of OC₁C₁₀‐PPV:PCBM (poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐p‐phenylene vinylene):methanofullerene [6,6]‐phenyl C₆₁‐butyric acid methyl ester)‐based bulk heterojunction solar cells on their composition has been investigated. With regard to charge transport, we demonstrate that the electron mobility gradually increases on increasing the PCBM weight ratio, up to 80 wt.‐%, and subsequently saturates to its bulk value. Surprisingly, the hole mobility in the PPV phase shows an identical behavior and saturates beyond 67 wt.‐% PCBM, a value which is more than two orders of magnitude higher than that of the pure polymer. The experimental electron and hole mobilities were used to study the photocurrent generation of OC₁C₁₀‐PPV:PCBM bulk‐heterojunction (BHJ) solar cells. From numerical calculations, it is shown that for PCBM concentrations exceeding 80 wt.‐% reduced light absorption is responsible for the loss of device performance. From 80 to 67 wt.‐%, the decrease in power conversion efficiency is mainly due to a decreased separation efficiency of bound electron–hole (e–h) pairs. Below 67 wt.‐%, the performance loss is governed by a combination of a reduced generation rate of e–h pairs and a strong decrease in hole transport.     

Angiotensin-converting enzyme inhibition and angiotensin II subtype-1 receptor blockade during the progression of left ventricular dysfunction: differential effects on myocyte contractile processes

Inhibition of the angiotensin-converting enzyme (ACE) in the setting of chronic left ventricular (LV) dysfunction has been demonstrated to have beneficial effects on survival and symptoms. However, whether ACE inhibition has direct effects on myocyte contractile processes and if these effects are mediated primarily through the AT1 angiotensin-II receptor subtype remains unclear. The present project examined the relationship between changes in LV and myocyte function and beta adrenergic receptor transduction in four groups of six dogs each: (1) Rapid Pace: LV failure induced by chronic rapid pacing (4 weeks; 216 +/- 2 bpm); (2) Rapid Pace/ACEI: concomitant ACE inhibition (ACEI: fosinopril 30 mg/kg b.i.d.) with chronic pacing; (3) Rapid Pace/AT1 Block: concomitant AT1 Ang-II receptor blockade [Irbesartan: SR 47436(BMS-186295) 30 mg/kg b.i.d.] with chronic pacing; and (4) Control: sham controls. With Rapid Pace, the LV end-diastolic volume increased by 62% and the ejection fraction decreased by 53% from control. With Rapid Pace/ACEI, the LV end-diastolic volume was reduced by 24% and the ejection fraction increased by 26% from Rapid Pace only values. Rapid Pace/AT1 Block did not improve LV geometry or function from Rapid Pace values. Myocyte contractile function decreased by 40% with Rapid Pace and increased from this value by 32% with Rapid Pace/ACEI. Rapid Pace/AT1 Block had no effect on myocyte function when compared with Rapid Pace values. With Rapid Pace/ACEI, beta receptor density and cyclic AMP production were normalized and associated with an improvement in myocyte beta adrenergic response compared with Rapid Pace only. Although Rapid Pace/AT1 also normalized beta receptor density, cyclic AMP production was unchanged and myocyte beta adrenergic response was reduced by 15% compared with Rapid Pace only. ACE inhibition with chronic rapid pacing improved LV and myocyte geometry and function, and normalized beta receptor density and cyclic AMP production. However, AT1 Ang-II receptor blockade with chronic rapid pacing failed to provide similar protective effects on LV and myocyte geometry and function. These unique findings suggest that the effects of ACE inhibition on LV geometry and myocyte contractile processes in the setting of developing LV failure are not primarily caused by modulation of AT1 Ang-II receptor activation.     

Accuracy of formulae for calculating left ventricular volumes of the equine heart

Echocardiography may be an accurate method of measuring left ventricular (LV) volumes and mass of the horse's heart. If so, studies of the heart size and hypertrophy would be possible. This study evaluated geometric models of the external and internal LV shapes, to determine which could be applied to echocardiographic measurements. We preserved 30 horses' hearts and measured their dimensions and cross sectional areas. These measurements were entered into seven formulae representing different geometric models of the ventricle and its chamber. We derived a correction factor to estimate the long axis as a fixed proportion of the external diameter, so that volumes could be determined from an M-mode or a cross sectional echocardiogram. Statistical analysis of the regressions of known volumes against calculated volumes measured by water displacement, demonstrated that the ellipsoid formula using cross sectional areas was very accurate in representing the external shape of the left ventricle (slope = 1.01 r2 = 96.3) and its chamber (slope = 0.83, r2 = 94.3). Myocardial volume, measured by subtracting internal (chamber) volume from external volume, was also calculated accurately (slope = 1.01, r2 = 96.5). The ellipsoid formula using directly measured diameter was only slightly less accurate. LV mass could be calculated by applying the specific gravity of equine myocardium, 1.05, to the myocardial volume. Formulae recommended for evaluating are, with M-mode echocardiography: [equation: see text] and with 2D echocardiography [equation: see text] where De is the external diameter, Di is the internal diameter, Ae the external area and Ai the internal area.