Encoding of 1- and 5-kHz pure tones by auditory-nerve (AN) fibers and choppers of the posteroventral cochlear nucleus (PVCN) was investigated. Neuronal responses were analyzed as the discharge rate, ...rate change, and the mean and standard deviation (or sigma) of spike counts. The major findings are: (1) Sideband inhibitory areas were observed in spatial profiles of rate changes of PVCN choppers whereas they were absent in those of AN fibers; (2) spatial profiles of rate changes and mean discharge rates of PVCN choppers were sharper than those of high spontaneous-rate (HSR) AN fibers and were comparable to those of low and medium SR (LMSR) AN fibers for 1 kHz at 50 and 70 dB SPL re: 20 microPa; (3) to 5 kHz, 30 dB SPL, PVCN choppers were strongly driven comparable to HSR AN fibers whereas LMSR AN fibers were weakly driven (implying higher thresholds); (4) PVCN choppers exhibited higher maximum discharge rates (300-600 spikes/s) than either LMSR AN fibers (200-250 spikes/s) or HSR AN fibers (150-250 spikes/s); (5) mean-to-sigma ratios of PVCN choppers, particularly at 70 dB SPL, were much higher than those of LMSR or HSR AN fibers; (6) rate-change profiles of LMSR AN fibers were distinct from those of HSR AN fibers, more conspicuously for 1 kHz than for 5 kHz; (7) the neural response profiles to 5 kHz were sharper than those to 1 kHz; and (8) 45% of PVCN choppers in the present study exhibited SR greater than 20 spikes/s whereas only 11%-12% of AVCN choppers in previous studies of anesthetized cats exhibited the same SR, which may represent an effect of anesthesia. The observations support a hypothesis that the transformation of the discharge-rate signal from AN fibers to PVCN choppers leads to an amplification of the mean discharge-rate signal with an increase in the signal-to-noise ratio. The observations suggest that PVCN choppers can encode pure-tone frequency in a spatial profile more accurately than HSR or LMSR AN fibers. The present data on AN and PVCN spatial profiles should be valuable to CN modeling studies by providing the input to the CN and the output of a class of physiologically characterized CN neurons for an identical set of stimuli.
This document presents a selection of QCD studies accessible to high-precision studies with hadronic final states in \(e^+e^-\) collisions at Belle II. The exceptionally clean environment and the ...state-of-the-art capabilities of the Belle~II detector (including excellent particle identification and improved vertex reconstruction), coupled with an unprecedented data-set size, will make possible to carry out multiple valuable measurements of the strong interaction including hadronic contributions to the muon \((g-2)\) and the QCD coupling, as well as advanced studies of parton hadronization and dynamical quark mass generation.
A series of 3 beta-(p-substituted phenyl)tropane-2 beta-carboxylic acid methyl esters (2) were synthesized and found to possess high affinity for the cocaine binding site in rat striatum. The ...p-chloro (2c) and p-iodo (2n) compounds, which were the most potent analogues prepared, were found to be 85 and 78 times more potent than (-)-cocaine. The p-bromo (2m) and p-methyl (2d) were also 56 and 60 times more potent than cocaine. QSAR and CoMFA studies were conducted to correlate binding affinity of the cocaine analogues with their structural features. Whereas the QSAR study gave relatively low correlations, the CoMFA study gave a correlation with high predictive value.
Upgrading the SuperKEKB electron-positron collider with polarized electron beams opens a new program of precision physics at a center-of-mass energy of 10.58 GeV. This white paper describes the ...physics potential of this `Chiral Belle' program. It includes projections for precision measurements of \(\sin^2\theta_W\) that can be obtained from independent left-right asymmetry measurements of \(e^+e^-\) transitions to pairs of electrons, muons, taus, charm and b-quarks. The \(\sin^2\theta_W\) precision obtainable at SuperKEKB will match that of the LEP/SLC world average, but at the centre-of-mass energy of 10.58 GeV. Measurements of the couplings for muons, charm, and \(b\)-quarks will be substantially improved and the existing \(3\sigma\) discrepancy between the SLC \(A_{LR}\) and LEP \(A_{FB}^b\) measurements will be addressed. Precision measurements of neutral current universality will be more than an order of magnitude more precise than currently available. As the energy scale is well away from the \(Z^0\)-pole, the precision measurements will have sensitivity to the presence of a parity-violating dark sector gauge boson, \(Z_{\rm dark}\). The program also enables the measurement of the anomalous magnetic moment \(g-2\) form factor of the \(\tau\) to be made at an unprecedented level of precision. A precision of \(10^{-5}\) level is accessible with 40~ab\(^{-1}\) and with more data it would start to approach the \(10^{-6}\) level. This technique would provide the most precise information from the third generation about potential new physics explanations of the muon \(g-2\) \(4\sigma\) anomaly. Additional \(\tau\) and QCD physics programs enabled or enhanced with having polarized electron beams are also discussed in this White Paper. This paper includes a summary of the path forward in R&D and next steps required to implement this upgrade and access its exciting discovery potential.
Belle II Executive Summary Asner, D M; Atmacan, H; Banerjee, Sw ...
arXiv (Cornell University),
03/2022
Paper, Journal Article
Odprti dostop
Belle II is a Super \(B\) Factory experiment, expected to record 50 ab\(^{-1}\) of \(e^+e^-\) collisions at the SuperKEKB accelerator over the next decade. The large samples of \(B\) mesons, charm ...hadrons, and tau leptons produced in the clean experimental environment of \(e^+e^-\) collisions will provide the basis of a broad and unique flavor-physics program. Belle II will pursue physics beyond the Standard Model in many ways, for example: improving the precision of weak interaction parameters, particularly Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and phases, and thus more rigorously test the CKM paradigm, measuring lepton-flavor-violating parameters, and performing unique searches for missing-mass dark matter events. Many key measurements will be made with world-leading precision.
We are studying the interconnections between the anteroventral cochlear nucleus (AVCN) and the dorsal cochlear nucleus (DCN). Biotinylated dextran was injected into the DCN, where the best frequency ...of responses was also recorded. Ventrotubercular neurons in AVCN were labeled, along with cochlear nerve fibers and the axons of cells in DCN. In AVCN, a central band of labeled cochlear nerve axons and large endbulbs was labeled. Bordering this band was a `fringe' of smaller tuberculoventral axonal endings forming pericellular nests. Most AVCN neurons projecting to DCN were stellate, elongate, or giant cells, located in the posterior division of AVCN, regardless of the DCN injection site. About 75% of the labeled AVCN cells lay within the bands of labeled cochlear nerve fibers. Another 15% were in the outer fringes on either side of these bands, while 10% were outside the bands and the fringes. These findings suggest that most AVCN neurons projecting to the DCN conform to the tonotopic map. A significant portion of the ventrotubercular neurons occupy side-bands in AVCN. Reciprocally, the tuberculoventral tract forms a robust fringe of axonal endings flanking the central bands. The neuronal and axonal bands and side-bands may underlie excitatory and inhibitory signal transformations.
CBA mice do not exhibit age-related loss of auditory sensitivity or cochlear pathology until relatively late in life. Therefore, this strain is believed to be an excellent animal model for the ...examination of the effects of age on the cochlea. To evaluate the effects of age on outer hair cell function, 2
f
1−
f
2 distortion product otoacoustic emissions (DPOAEs) were measured for
f
2 between 8 and 16 kHz in CBA/J mice between 1 and 25 months of age. CBA mice exhibited mild age-related changes in DPOAE level and detection threshold at 17 months of age, and changes of 20–40 dB by 25 months of age. The DPOAE level decreased and detection threshold increased with age in a frequency-dependent manner, starting at high frequencies and eventually extending to low frequencies. The range of frequencies in which notches were observed in the DPOAE input/output (I/O) functions extended toward lower frequencies by 17 months of age. Notches were absent in the I/O functions of 25-month-old mice. The present results for a frequency range of 8–16 kHz suggest that age has modest effects on outer hair cell function in CBA mice.
Thresholds of neurons to sounds were compared as a function of central auditory structure ventral cochlear nucleus (VCN), dorsal cochlear nucleus (DCN), and inferior colliculus (IC) in young and ...middle-aged C57BL/6J mice (multiple- and single-unit recordings) and in young and old CBA/J mice (single-unit recordings). Middle-aged C57 mice show progressive loss of sensitivity to high frequencies and noise due to cochlear pathology; CBA mice show little loss of sensitivity through most of their lifespan. Multiple-unit threshold curves (MTCs) for tones indicated that neurons in the C57 VCN suffered a greater degree of age-related loss of sensitivity than neurons in the IC (from an earlier study). Furthermore, whereas the low frequency portions of MTCs in IC neurons in high frequency tonotopic regions typically become 'sensitized' in middle-aged C57 mice (i.e., lower thresholds than young mice), such was not the case for VCN neurons. In contrast to VCN neurons, MTCs of the population of DCN neurons studied were statistically indistinguishable from those of the IC. Measurements of single-unit response areas in C57 mice corroborated the MTCs. In CBA mice, little effect of age was found in comparing single-unit response areas of young and old mice. The findings indicate that sensorineural impairment in middle-aged C57 mice is accompanied by threshold changes that are more severe in the VCN than in the IC or DCN. Because the VCN and DCN are believed to play different roles in hearing, the functions they support should, likewise, be affected to different extents by age-related hearing loss.
