Distortion-product otoacoustic emission suppression tuning curves in humans

Distortion-product otoacoustic emission (DPOAE) suppression data as a function of suppressor level (L(3)) for f(2) frequencies from 0.5 to 8 kHz and L(2) levels from 10 to 60 dB sensation level were used to construct suppression tuning curves (STCs). DPOAE levels in the presence of suppressors were converted into decrement versus L(3) functions, and the L(3) levels resulting in 3 dB decrements were derived by transformed linear regression. These L(3) levels were plotted as a function of f(3) to construct STCs. When f(3) is represented on an octave scale, STCs were similar in shape across f(2) frequency. These STCs were analyzed to provide estimates of gain (tip-to-tail difference) and tuning (Q(ERB)). Both gain and tuning decreased as L(2) increased, regardless of f(2), but the trend with f(2) was not monotonic. A roughly linear relation was observed between gain and tuning at each frequency, such that gain increased by 4-16 dB (mean ≈ 5 dB) for every unit increase in Q(ERB), although the pattern varied with frequency. These findings suggest consistent nonlinear processing across a wide frequency range in humans, although the nonlinear operation range is frequency dependent.     

GEODESIC PRECESSION IN THE (Ω,A_(ab))-FIELD THEORY

I.IntroductionSupposethata(small)torque-freegyroscopewithspinSmovesa1ongageodesic.ThueSisparallellytransported.TheagreementbetWeentheparalleltransportandthegyroscoPetransportonlyholdsalonggeodesic.Itisknownthatinthecurvedspacetime,paralleltranspotthasdrasticeffectsonthedirectionofavectorandwetherefOreexPectsimilareffeCtsonagyroscoPe.The'correspondingspinpreeessionintheSchwarzschildfieldhasbeendiscussedindetailbyQhanianl'l,Murray13],'andStraumannM,etal.usingdifferentapproaches.Here,inth…     

OPTIONS FOR THE REGULATION OF MEDITERRANEAN DEMERSAL FISHERIES

Research and management actions are reviewed with respect to demersal fisheries of the Mediterranean since the Second World War, as reflected in the activities of the General Fisheries Council for the Mediterranean, (GFCM). The scientific background to the priority concern expressed for minimum size limits in the 1960's and 1970's is discussed, and in particular, the mesh selectivity experiments that formed the basis for yield per recruit calculations, with respect to the trawl fishery. More recent considerations, changing our perception of the appropriateness of size at first capture of demersal fish as a management tool in trawl fisheries, are reviewed. It is concluded that for multispecies fisheries where the first priority for fishing effort control is not respected, size limits based on size at maturity, rather than yield per recruit criteria, are more feasible, but that changes in mesh size need to take into account subsequent changes in equity between inshore and offshore fleets, and changes in species composition and areas of distribution during the life history. They also need to consider the high landed value of small fish in many Mediterranean fisheries. Alternative, or supplementary, measures to mesh size regulation that affect capture of small fish are also reviewed, including seasonal closures, closed areas, bans on trawling inshore, and regulations on minimum size at sale. A range of problems to be considered prior to deciding on an increase in mesh size are reviewed, including changes in total effort exerted, changes in increases in fishing power (and especially the impacts on the spawning stock), changes in discard rate, “meshing” of small fish, and indirect mortality during fishing. A strategy for introducing new mesh sizes is suggested, with emphasis, where possible, on the experimental approach, and on supplementary measures to control fishing effort. The paper concludes by considering an alternative paradigm to minimum size regulation for demersal fisheries management; namely, the exploitation of juvenile fish, with provision for escapement of a small proportion of large, mature fish offshore, for which exploitation rate declines and remains low. It is suggested that this strategy may be, de facto, the one prevailing in the small mesh size inshore trawl fishery prior to development of offshore fisheries. The implications of this possibility have to be considered seriously if high effort levels are to be maintained while effective size limits are raised.     

Chromatographic screening for drugs of abuse using capillary columns. III. Quantitative analysis of CNS stimulant drugs in urine using support coated open tubular columns

Summary The limitations imposed by the use of a flame ionisation detector (FID) in the quantitative analysis of central nervous system (CNS) stimulant drugs on support coated open tubular (SCOT) columns are discussed and the use of an alkali flame ionisation detector (AFID) is advocated to improve sensitivity.     

Utilization of Moiré interferometry to study strain transfer across polymer interfaces within multilayer thermoplastic elastomers

In this paper, a moiré interferometry technique was used to study the viscoelastic strain distributions within and across the interfaces of multilayer thermoplastic elastomers, which were fabricated as models for functionally modulus‐graded materials. Two types of interfaces, those formed from miscible and immiscible pairs of the same thickness, were fabricated within multilayer thermoplastic samples. The analysis of the moiré fringe patterns indicated that there was a large normal strain, ε_y, concentration at the polymer interfaces formed from the immiscible or partially miscible pairs. However, this large normal strain was not observed at the interfaces formed from the miscible pairs. These results suggest that the magnitude of strain concentrations at polymer interfaces within functionally modulus‐graded materials could be significantly reduced by extensive chain interdiffusion, which could be promoted by careful selection of miscible polymer pairs. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2196–2206, 2005     

Photoactive liquid polysulfides: preparation, characterisation, photocuring and potential applications

Photoactive terminal groups X have been introduced into liquid polysulfides to give X(SCH₂CH₂OCH₂OCH₂CH₂S)_nX where X=acetyl, acryloyl, cinnamoyl, benzoyl, I-naphthaloyl, oxalyl, p-toluene sulfonyl, terephthaloyl, 1,3,5-benzene tricarbonyl and methylvinylsilyl. The resulting modified LPs have been characterised by IR, UV, ¹NMR spectroscopy, size exclusion chromatography and ESI and FAB mass spectrometry. The results of photoirradiating these materials were examined and some selected for further study with regard to their potential application as coatings, adhesives and photoresists, both as such and as components of formulations. While the slowness of cure of the modified LPs presents a difficulty, they function satisfactorily as components of established photocurable compositions, conferring advantages in a number of cases (scratch resistance, speed of cure, hardness).     

Thiocarbonyl ylides : Reactions and stereochemical properties of some 4-t-butylcyclohexyl derivatives

The azine from 4-t-butylcyclohexanone on treatment with hydrogen sulfide under pressure is converted to a mixture of stereoisomeric 1,3,4-thiadiazolidines. Dehydrogenation of this mixture with an alkyl azodicarboxylate afforded in quantitative yield (based on azine) a mixture of the three possible Δ³-1,3,4-thiadiazolines. These three isomers have been isolated and their structures have been established as trans,trans-3,11-di-[1,1-dimethylethyl]-14,15-diaza-7-thiadispiro[5.1.5.2]pentadeca-14-ene(5); the cis,cis-isomer (6), and the cis,trans-isomer (7). Pyrolysis of either 5 or 6 leads in quantitative yield to cis,trans-3,10-di-[1,1-dimethylethyl]thiadispiro[5.0.5.2]tridecane (8), the formation of which is rationalized by conrotatory ring closure of the same thiocarbonyl ylide (24) formed from either 5 or 6. Pyrolysis of 7 leads exclusively to a thiirane isomeric with 10 and which is assigned the cis,cis-structure (9). The thiiranes 8 and 9 are desulfurized by tri-n-butylphosphine to the anti- and syn-1-(1,1-dimethylethyl)-4-[4-(1,1-dimethylethyl)cyclohexylidene]cyclohexanes (11 and 12), respectively. The cycloadditions of the thiocarbonyl ylides derived from 5–7 with dimethyl acetylenedicarboxylate and dimethylazodicarboxylate have been examined but stereochemistries have not been assigned to these products. Cis additions to the olefins (11 and 12) have been investigated with the most attention having been paid to the reactions with osmium tetroxide. The configurations of the glycols expected from these reactions have been correlated by comparison with the three possible glycols (16–18) obtained from pinacol reduction of 4-t-butylcyclohexanone. These three glycols have been separated and their configurations assigned from PMR and IR data. A discussion of the stereochemical implications of the various results is given.