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Brainstem electrical responses (BSER) to 60-dB-SL click in noise high passed at various cutoff frequencies separated b 1/2-octave steps were recorded in normal-hearing adult subjects. By applying a derived response technique, narrow-band contributions to the BSER from specific portions of the basilar membrane were revealed. Latencies and amplitudes of the various waves in the derived BSER were recorded. Results indicate that nearly the whole cochlear partition can contribute to the brainstem response. The shifts in latency of waves I, III, and V and amplitude changes of waves I and III as a function of CF appear to be fully comparable to those of the AP. In contrast, the amplitude behavior of wave V as a function of CF is different from waves I and III depending upon frequency range. The discrepency in the behavior of wave V with respect to the earlier waves suggests some sort of neural reorganization at the level where was V is generated. The fact that there are contributions to the brainstem response from apical portions of the cochlea opens the possibility for extending the brainstem technique in assessing the higher cochlear turn function. 相似文献
54.
Don Weingarten 《Nuclear Physics B》1974,70(3):501-533
We will define a sequence of functions called density correlations which measure statistical correlations between momentum space densities of particles in the ensemble of inelastic final states produced by scattering a pair of hadrons. Then we will show that early multiplicity scaling of the distribution of charged particles produced by pp collisions can primarly be explained by the assumption that fluctuations of the density of charged particles are quite random and therefore higher correlation functions are small in an appropriate sense, combined with the assumption that the first three density correlations fulfill an approximate form of Feyman scaling at small values of x. These assumptions will aslo be used to derive an expression for the scaling function Ψ(η) which is completely determined by <N2>S/<N>S2 and <N3>S/<N>S3, and recursion relation to calculate <Nm>S/<N>Sm, m ? 4, from <N2>S/<N>S2 and <N3>S/<N>S3. The prediction for Ψ(η) accurately reproduces data in the interval 0.2 ? η ? 3.1, 50 GeV/c ? pL ? 303 GeV/c, and the predictions for <NS>m/<N>Sm, 4 ? m ? 10, agree with observed values in the interval 50 GeV/c ? pL ? 303 GeV/c. 相似文献
55.
Don N. Page 《Physics letters. A》1982,91(2):57-60
Quantum mechanics can completely describe what may actually be predicted about any system, contrary to the argument of Einstein, Podolsky, and Rosen. One does not however need to restric predictions to specified experimental arrangements as Bohr did. 相似文献
56.
The Einstein equations with a negative cosmological constant admit black hole solutions which are asymptotic to anti-de Sitter space. Like black holes in asymptotically flat space, these solutions have thermodynamic properties including a characteristic temperature and an intrinsic entropy equal to one quarter of the area of the event horizon in Planck units. There are however some important differences from the asymptotically flat case. A black hole in anti-de Sitter space has a minimum temperature which occurs when its size is of the order of the characteristic radius of the anti-de Sitter space. For larger black holes the red-shifted temperature measured at infinity is greater. This means that such black holes have positive specific heat and can be in stable equilibrium with thermal radiation at a fixed temperature. It also implies that the canonical ensemble exists for asymptotically anti-de Sitter space, unlike the case for asymptotically flat space. One can also consider the microcanonical ensemble. One can avoid the problem that arises in asymptotically flat space of having to put the system in a box with unphysical perfectly reflecting walls because the gravitational potential of anti-de Sitter space acts as a box of finite volume. 相似文献
57.
Partial fluorination overcomes herringbone crystal packing in small polycyclic aromatics 总被引:1,自引:0,他引:1
[structure: see text] We report the synthesis and characterization of partially fluorinated condensed tetracyclic aromatic compounds. Typical edge-to-face/herringbone packing of nonfluorinated analogues is replaced here by columnar stacks with disk planes orthogonal to the columnar axes. Enhanced pi-overlap results with overlaid electron-poor and -rich regions. 相似文献
58.
Bunch J Clench MR Richards DS 《Rapid communications in mass spectrometry : RCM》2004,18(24):3051-3060
Matrix-assisted laser desorption/ionisation (MALDI) quadrupole time-of-flight mass spectrometry (Q-TOFMS) has been used to detect and image the distribution of a xenobiotic substance in skin. Porcine epidermal tissue was treated with 'Nizoral', a medicated shampoo containing ketoconazole (+/-)-1-acetyl-4-[p-[[(2R,4S)-2-(2,4-dichlorophenyl)-2-(imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) as active ingredient. Following incubation for 1 h at 37 degrees C all excess formulation was washed from the surface. A cross-section of the drug-treated tissue was then blotted onto a cellulose membrane, precoated in matrix (alpha-cyano-4-hydroxycinnamic acid (CHCA)), by airspray deposition. In separate experiments the tissue surface was treated with Nizoral within a triangular former, and subsequently blotted onto a matrix-coated membrane. Sample membranes were then mounted into the recess of specialised MALDI targets with adhesive tape. All samples were analysed by MALDI-TOFMS using an Applied Biosystem 'Q-star Pulsar i' hybrid Q-TOF mass spectrometer fitted with an orthagonal MALDI ion source and imaging software. Detection of the protonated molecule was readily achievable by this technique. Treatment of the tissue within a template gave rise to images depicting the expected distribution of the drug, demonstrating that this technique is capable of producing spatially useful data. Ion images demonstrating the permeation of the applied compound into the skin were achieved by imaging a cross-sectional imprint of treated tissue. A calibration graph for the determination of ketoconazole was prepared using the sodium adduct of the matrix ion as an internal standard. This enabled construction of a quantitative profile of drug in skin. Conventional haematoxylin and eosin staining and microscopy methods were employed to obtain a histological image of the porcine epidermal tissue. Superimposing the mass spectrometric and histological images appeared to indicate drug permeation into the dermal tissue layer. 相似文献
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Lowe Terry C. Bishop Alan Burns Carol Hartford Allen Parkin Don Trewhella Jill 《Journal of nanoparticle research》2000,2(3):249-266
Research in the emerging field of nanoscale science and technology has grown steadily at Los Alamos National Laboratory since 1990. This article summarizes some of this work, examining research highlights within the seven key categories of nanoscience in which Los Alamos has ongoing projects, capabilities, and facilities: (1) Materials and chemistry, (2) Theory and modeling, (3) Bioscience, (4) Investigative tools and facilities, (5) Sensors and devices, (6) Synthesis and fabrication, and (7) Education and outreach. Future research horizons are indicated throughout while institutional strategies for advancing nanoscale science are summarized at the end. 相似文献