22 research outputs found
Audiological study of hearing impaired infants and young children
No full text의학과/석사[한글]
[영문]
A hearing test for young children is one of the difficult problems which an otolaryngologist meets daily.
Both subjective and objective methods of testing have been devised.
Among the subjective tests are applications of reflex audiometry, play audiometry and response audiometry while the objective test mothods include psychogalvanic skin resistance test, evoked response audiometry and electrocochleography.
Historically, Ewing & Ewing(1944) began to develop the pediatric audiometry by conducting investigations into 2-3 year old children, using a set of toys capable of attracting their attention, which was so called play audiometry.
Dix & Hallpike(1947) introduced into clinical practice a method of instrumental conditioning for examining deaf children using a device called peep-show.
Since then, various proposed modifications for Dix & Hallpike's peep show have been suggested.
Bordley and Hardy(1949) reported on a electrophysiological device: a study in objective audiometry with the use of psychogalvanometric response.
Psychogalvanometric reflex audiometry and instrumental conditioned reflex audiometry did not allow sufficiently demonstrable data to be obtained in children under 3 years of age.
Suzuki & Ogiba(1960) invented an investigation method enabling the number of failures in the P.G.R. and I.C.R. to be reduced.
This method is based on the finding that children, when subjected to a sudden light stimulus, turn their heads instinctively towards the light source. This is evidantly a wholly unconditioned oriented reflex.
It can however be conditioned by making a sound stimulus precede the luminous one, a conditioned oriented reflex(C.O.R.) can thus be achieved for the auditory stimulus.
The C.O.R. audiometry of Suzuki & Ogiba also has other handicaps in that it is not capabling of testing unilateral hearing acuity nor loss of interest in the test on the part of older children.
Here, the author investigated 180 young deaf children from one to six who come to Yonsei Medical Center during the last four years.
By means of subjective audiometry as mentioned above, the author studied ways of building a more simple and accurate testing method for the very young child and infant in Korea.
A series of tests were performed using a pure tone, speech babbling, broad band noise, musical sound and calling of patients name as acoustic signals and the following results were obtained.
1. Speech babbling was used most commonly for the acoustic signal followed by pure tone, broad band noise and music etc., in that order.
2. Before 3 age, responses of the children were reflex responses such as head turning or startle and natural response such as a smile, but after 3 age, cooperative behavior such as block-dropping and hand-raising were used for auditory response.
3. The success rate of each signal is high in general for the age group over 3 but the age group below 3 shows a high success rate only where broad band noise, music sound and calling of patient's name are used as signals.
4. The number of trials to determine the sound detection threshold and pure tone threshold are in general below 3 times, but four or five times are needed on occasion to determine the threshold.
5. The etiology of the cases where the author failed to determine the sound detection threshold are due in most cases to unconditioning of the children in 40 cases(60.6%) and next those referred for speech therapy and no return cases in descending order.
6. 75% of the cases of children who received pure tone tests successfully could wear ear phones to determine the type of hearing impairment and they are above 4 years of age in most cases.
7. 60.4% of the patients tested by pure tone signals showed hearing impairment from moderate to severe form, all these and more severe cases need special auditory training.
8. Of the 66 children tested with ear phones, sensori-neural hearing impairment 66.7% and next mixed type in 22.7%.
9. The Average of the sound detection thresholds were in general 10-20 dB below the average of the pure tone thresholds and the difference becoming greater as the degree of the hearing impairment increased.restrictio
Multimuons in cosmic-ray events as seen in ALICE at the LHC
No full textALICE is a large experiment at the CERN Large Hadron Collider. Located 52 meters underground, its detectors are suitable to measure muons produced by cosmic-ray interactions in the atmosphere. In this paper, the studies of the cosmic muons registered by ALICE during Run 2 (2015–2018) are described. The analysis is limited to multimuon events defined as events with more than four detected muons (Nµ > 4) and in the zenith angle range 0◦ < θ < 50◦. The results are compared with Monte Carlo simulations using three of the main hadronic interaction models describing the air shower development in the atmosphere: QGSJET-II-04, EPOS-LHC, and SIBYLL 2.3d. The interval of the primary cosmic-ray energy involved in the measured muon multiplicity distribution is about 4×1015 < Eprim < 6×1016 eV. In this interval none of the three models is able to describe precisely the trend of the composition of cosmic rays as the energy increases. However, QGSJET-II-04 is found to be the only model capable of reproducing reasonably well the muon multiplicity distribution, assuming a heavy composition of the primary cosmic rays over the whole energy range, while SIBYLL 2.3d and EPOS-LHC underpredict the number of muons in a large interval of multiplicity by more than 20% and 30%, respectively. The rate of high muon multiplicity events (Nµ > 100) obtained with QGSJET-II-04 and SIBYLL 2.3d is compatible with the data, while EPOS-LHC produces a significantly lower rate (55% of the measured rate). For both QGSJET-II-04 and SIBYLL 2.3d, the rate is close to the data when the composition is assumed to be dominated by heavy elements, an outcome compatible with the average energy Eprim ∼ 1017 eV of these events. This result places significant constraints on more exotic production mechanisms. © 2025 The Author(s)
First Measurement of A=4 Hypernuclei and Antihypernuclei at the LHC
No full textInternational audienceIn this Letter, the first evidence of the antihypernucleus is presented, along with the first measurement at the LHC of the production of (anti)hypernuclei with mass number , specifically (anti) and (anti). In addition, the antiparticle-to-particle ratios for both hypernuclei ( and ) are shown, which are sensitive to the baryochemical potential of the strongly interacting matter created in heavy-ion collisions. The results are obtained from a data sample of central Pb--Pb collisions, collected during the 2018 LHC data taking at a center-of-mass energy per nucleon pair of \sqrt{s_{\mathrm{NN}}} = \SI{5.02}{\tera\electronvolt}. The yields measured for the average of the charge-conjugated states are found to be for the (anti) and for the (anti), and the measured antiparticle-to-particle ratios are in agreement with unity. The presence of (anti) and (anti) excited states is expected to strongly enhance the production yield of these hypernuclei. The yield values exhibit a combined deviation of from the theoretical ground-state-only expectation, while the inclusion of the excited states in the calculations leads to an agreement within with the present measurements. Additionally, the measured (anti) and (anti) masses are compatible with the world-average values within the uncertainties
Particle production as a function of charged-particle flattenicity in pp collisions at s =13 TeV
No full textThis paper reports the first measurement of the transverse momentum (pT) spectra of primary charged pions, kaons, (anti)protons, and unidentified particles as a function of the charged-particle flattenicity in pp collisions at s=13 TeV. Flattenicity is a novel event shape observable that is measured in the pseudorapidity intervals covered by the V0 detector, 2.8<η<5.1 and -3.7<η<-1.7. According to QCD-inspired phenomenological models, it shows sensitivity to multiparton interactions and is less affected by biases toward larger pT due to local multiplicity fluctuations in the V0 acceptance than multiplicity. The analysis is performed in minimum-bias (MB) as well as in high-multiplicity events up to pT=20 GeV/c. The event selection requires at least one charged particle produced in the pseudorapidity interval |η|<1. The measured pT distributions, average pT, kaon-to-pion and proton-to-pion particle ratios, presented in this paper, are compared to model calculations using pythia 8 based on color strings and EPOS LHC. The modification of the pT-spectral shapes in low-flattenicity events that have large event activity with respect to those measured in MB events develops a pronounced peak at intermediate pT (2<pT<8 GeV/c), and approaches the vicinity of unity at higher pT. The results are qualitatively described by pythia, and they show different behavior than those measured as a function of charged-particle multiplicity based on the V0M estimator
Measurement of f1(1285) production in pp collisions at s = 13 TeV
No full textThis study presents the first measurement of the f1(1285) resonance using the ALICE detector in inelastic proton–proton collisions at a center-of-mass energy of 13 TeV. The resonance is reconstructed at midrapidity (|y|< 0.5) through the hadronic decay channel f1(1285)→KS0K±π∓. Key measurements include the determination of its mass, transverse-momentum integrated yield, and average transverse momentum. Additionally, the ratio of the transverse-momentum integrated yield of f1(1285) to pion is compared with calculations from the canonical statistical hadronization model. The model calculation, assuming a zero total strangeness content for f1(1285), reproduces the data within 1σ deviation, shedding light on the quark composition of f1(1285)
Investigating Λ baryon production in p -Pb collisions in jets and the underlying event using angular correlations
No full textFirst measurements of hadron-Λ (h-Λ) azimuthal angular correlations in p-Pb collisions at sNN =5.02 TeV using the ALICE detector at the Large Hadron Collider are presented. These correlations are used to separate the production of associated Λ baryons into three different kinematic regions, namely those produced in the direction of the trigger particle (near side), those produced in the opposite direction (away side), and those whose production is uncorrelated with the jet axis (underlying event). The per-trigger associated Λ yields in these regions are extracted, along with the near- and away-side azimuthal peak widths, and the results are studied as a function of associated particle pT and event multiplicity. Comparisons with the dpmjet event generator and previous measurements of the φ(1020) meson are also made. The final results indicate that strangeness production in the highest multiplicity p-Pb collisions is enhanced relative to low multiplicity collisions in both the jetlike regions and the underlying event. The production of Λ relative to charged hadrons is also enhanced in the underlying event when compared to the jetlike regions. Additionally, the results hint that strange quark production in the away-side of the jet is modified by soft interactions with the underlying event
Probing Strangeness Hadronization with Event-by-Event Production of Multistrange Hadrons
No full textThis Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons Ξ- and Ξ¯+ and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p-Pb, and Pb-Pb collisions at a center-of-mass energy per nucleon pair sNN=5.02 TeV. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data
Measurement of the impact-parameter dependent azimuthal anisotropy in coherent ρ0 photoproduction in Pb–Pb collisions at sNN=5.02 TeV
No full textThis Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced ρ0 mesons. The ρ0 mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the cos(2φ) modulation, where φ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb−Pb collisions at a center-of-mass energy of √sNN = 5.02 TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the cos(2φ) modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured cos(2φ) anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction
Medium-induced modification of groomed and ungroomed jet mass and angularities in Pb–Pb collisions at sNN=5.02 TeV
No full textThe ALICE Collaboration presents a new suite of jet substructure measurements in Pb–Pb and pp collisions at a center-of-mass energy per nucleon pair sNN=5.02 [Figure presented]. These measurements provide access to the internal structure of jets via the momentum and angle of their constituents, probing how the quark–gluon plasma modifies jets, an effect known as jet quenching. Jet grooming additionally removes soft wide-angle radiation to enhance perturbative accuracy and reduce experimental uncertainties. We report the groomed and ungroomed jet mass mjet and jet angularities λα κ using κ=1 and α>0. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with resolution parameter R=0.2. A narrowing of the jet mass and angularity distributions in Pb–Pb collisions with respect to pp is observed and is enhanced for groomed results, confirming modification of the jet core. By using consistent jet definitions and kinematic cuts between the mass and angularities for the first time, previous inconsistencies in the interpretation of quenching measurements are resolved, rectifying a hurdle for understanding how jet quenching arises from first principles and highlighting the importance of a well-controlled baseline. These results are compared with a variety of theoretical models of jet quenching, providing constraints on jet energy-loss mechanisms in the quark–gluon plasma
System size and energy dependence of the mean transverse momentum fluctuations at the LHC
No full textEvent-by-event fluctuations of the event-wise mean transverse momentum, ⟨pT⟩, of charged particles produced in proton–proton (pp) collisions at s = 5.02 TeV, Xe–Xe collisions at sNN = 5.44 TeV, and Pb–Pb collisions at sNN = 5.02 TeV are studied using the ALICE detector based on the integral correlator ⟨⟨ΔpTΔpT⟩⟩. The correlator strength is found to decrease monotonically with increasing produced charged-particle multiplicity measured at midrapidity in all three systems. In Xe–Xe and Pb–Pb collisions, the multiplicity dependence of the correlator deviates significantly from a simple power-law scaling as well as from the predictions of the HIJING and AMPT models. The observed deviation from power-law scaling is expected from transverse radial flow in semicentral to central Xe–Xe and Pb–Pb collisions. In pp collisions, the correlation strength is also studied by classifying the events based on the transverse spherocity, S0, of the particle production at midrapidity, used as a proxy for the presence of a pronounced back-to-back jet topology. Low-spherocity (jetty) events feature a larger correlation strength than those with high spherocity (isotropic). The strength and multiplicity dependence of jetty and isotropic events are well reproduced by calculations with the PYTHIA 8 and EPOS LHC models
