High EI Research Articles

Processing of interaural time and intensity differences in the cat inferior colliculus.

1. Binaural neurones were recorded in the central nucleus of the cat inferior colliculus and were stimulated with tone and noise bursts. Closed field sound systems were used to produce independent interaural time (ITD) and intensity (IID) differences. Particular attention was paid to high frequency (above 2 kHz) cells. 2. Three main types of binaural neurone were found: High frequency excitatory-inhibitory neurones (EI cells), excited by input from the contralateral ear and inhibited by ipsilateral input, high frequency excitatory-excitatory cells (EE cells), excited by inputs from either ear and low frequency cells sensitive to interaural phase differences (IPD cells). 3. The EI cells had characteristics similar to those of IE cells in the contralateral lateral superior olive. They were sensitive to envelope ITDs (most cells) and IIDs (all cells) favouring the contralateral ear. The response of these cells increased with increasing contra lead ITDs or contra loud IIDs up to values well outside the physiological range. 4. Low frequency binaural cells were sensitive to interaural phase differences (IPDs). The peak response was often in the contralateral physiological range and the response was unaffected by IIDs. 5. Many high frequency EE cells were sensitive to envelope ITDs. These units were relatively unaffected by IID. Although the ITD sensitivity of these cells was generally less than that of the IPD cells, the peak response of the ITD curve was also often in the contralateral physiological range. 6. Some of the high frequency EI and EE cells were sensitive to ongoing time differences (OTDs) in white noise signals, i.e. they showed ITD response curves to carrier only shifted noise bursts. 7. The EI cells often showed recovery from inhibition at large ipsilateral lead. This tendency was increased as the sound pressure level on the inhibitory side was lowered and by the use of click stimuli. Similarly, cycles of suppression could be seen to follow excitation in some EE cells. The time course of these effects was in the order of hundreds of microseconds. 8. Binaural characteristics (degree of ITD, IID or OTD sensitivity) showed considerable interunit variation within each cell type. These variations were also affected by signal type (tone or noise bursts) and did not appear to be correlated with best frequency, nature of the tuning curve or PSTH type. We suggest that the time course of the inhibitory and excitatory effects at each unit (and its interaction with the signal type) determines the type of ITD response and that this time course varies from cell to cell.

Mass spectrometric methods in structural analysis of some vesicants

The utility of low and high resolution positive ion EI mass spectra, and positive and negative ion CI mass spectra was evaluated for the structural analysis and identification of the four vesicants of military significance. Reliable results are obtained after recording both the low resolution EI spectra and the positive CI spectra with isobutane as the reagent gas. The effect of chamber temperature on the fragmentation due to CI was investigated.

Effects of prey concentration, prey size, predator life stage, predator starvation, and season on predation rates of the carnivorous copepod Euchaeta elongata

Adult females of the large carnivorous copepod Euchaeta elongata Esterly were collected from 1977 to 1980 in Port Susan, Washington, USA. Predation rates of the adult females increased with increasing prey abundance when fed the following 4 sizes of copepods: adult females of Calanus pacificus (average prosome length [PL] of 2 650 μm), adults of Aetideus divergens (PL of 1 560 μm), adult females of Pseudocalanus spp. (PL of 1 060 μm), and nauplii of C. pacificus (PL of 410 μm). Saturation feeding levels were reached when adult females of the predator were fed the small adult copepod, Pseudocalanus spp. Maximum biomass ingested of this small copepod was more than the maximum amount ingested of the larger copepods. Predation rates of the predatory copepodids at Stages IV and V also increased with increasing concentration of the 1 060 μm (PL) prey. High feeding rates exhibited by both adults and copepodids at Stage V of the predator indicate their importance as sources of mortality on populations of small copepods. Ingestion efficiency E i (prey wholly consumed [prey attacked]-1) varied as follows: adults of E. elongata were more efficient than copepodids of E. elongata; adults were more efficient than copepodids when ingesting smaller prey; starved adults were more efficient than fed ones; and both adults and copepodids were more efficient at low food concentrations. For adults of E. elongata, there were no marked seasonal variations in predation or respiratory rates that would represent acclimatory responses; however, small adults obtained during winter were more efficient at ingesting prey than were the larger adults gathered in summer. This seasonal variation in the efficiency of ingestion may be a useful indicator of physiological state: high E i values could indicate that predators are starving in winter, and low E i values could indicate that predators are satiated in summer.

Polarization measures of 293 stars in Aquila.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarization measures of 293 stars in Aquila. Gossner, Joseph L. Abstract Photographic polarization measures of faint stars were made with the ~6-inch refractor for the study of galactic structure in Aquila. The method of measuring polarization, using calcite, is that described by Markowitz.1 Two hundred and ninety-three stars were measured in a field 50 minutes of arc in diameter centered on the star HD231564. This star, which occurs on the edge of a dark cloud, is listed by Popper as c Bi with the high color excess Ei = +0.58 mag. It shows a polarization of 3.5 per cent ~0.2 in position angle 1350 ~ 3. The other stars give the following results: Mean lflp Polarization Angle a 11.5-12.5 i.2%+o.15 II9~+2 45 12.5-13.5 1.9 +0.15 ii8 +2 105 13.5-14.5 i.8 +0.15 120 +2 142 The magnetic vector for these three groups is within a degree of being perpendicular to the galactic equator. By percentages we get the following results: Mean Polarization Polarization Angle a ~i.5o% o.6% 114 93 1.51t02.50 i.8 121 104 >2.51 2.9 120c 95 It appears that at least two-thirds of the stars in this one-half square degree field are polarized more than 1.5 per cent. The estimated distances of the polarized stars are about a kiloparsec. Additional information on the colors and spectra of some of the polarized stars would serve to fix the distance of the polarizing cloud. Plates of two nearby regions, one clear and the other heavily obscured, have been secured for future study. I.A. J. 56, 134, 1951; 55, 175, 1950. 2.Ap. J. III, 495, 1950. U. S. Naval Observatory, Washington, D. C. Publication: The Astronomical Journal Pub Date: April 1952 DOI: 10.1086/106784 Bibcode: 1952AJ.....57R..11G full text sources ADS |