Magnetic Breakdown and Topology in the Kagome Superconductor CsV_{3}Sb_{5} under High Magnetic Field

The recently discovered layered kagome metals of composition AV_{3}Sb_{5} (A=K, Rb, Cs) exhibit a complex interplay among superconductivity, charge density wave order, topologically nontrivial electronic band structure and geometrical frustration. Here, we probe the electronic band structure underlying these exotic correlated electronic states in CsV_{3}Sb_{5} with quantum oscillation measurements in pulsed fields up to 86 T. The high-field data reveal a sequence of magnetic breakdown orbits that allows the construction of a model for the folded Fermi surface of CsV_{3}Sb_{5}. The dominant features are large triangular Fermi surface sheets that cover almost half the folded Brillouin zone. These sheets have not yet been detected in angle resolved photoemission spectroscopy and display pronounced nesting. The Berry phases of the electron orbits have been deduced from Landau level fan diagrams near the quantum limit without the need for extrapolations, thereby unambiguously establishing the nontrivial topological character of several electron bands in this kagome lattice superconductor.

Observing the Suppression of Superconductivity in RbEuFe_{4}As_{4} by Correlated Magnetic Fluctuations

In this Letter, we describe quantitative magnetic imaging of superconducting vortices in RbEuFe_{4}As_{4} in order to investigate the unique interplay between the magnetic and superconducting sublattices. Our scanning Hall microscopy data reveal a pronounced suppression of the superfluid density near the magnetic ordering temperature in good qualitative agreement with a recently developed model describing the suppression of superconductivity by correlated magnetic fluctuations. These results indicate a pronounced exchange interaction between the superconducting and magnetic subsystems in RbEuFe_{4}As_{4}, with important implications for future investigations of physical phenomena arising from the interplay between them.

Effect on Cs removal of solid-phase metal oxidation in metal ferrocyanides

Metal ferrocyanides (MFCs) have been studied for many years and are regarded as efficient adsorbents for the selective removal of radioactive cesium (Cs) from contaminated aqueous solutions. Although their efficiency has been demonstrated, various investigations on the physicochemical, thermal, and radiological stability of the solids of MFCs are required to enhance the applicability of MFCs in the treatment process. We observed that the Cs adsorption efficiencies of cobalt and nickel ferrocyanides decreased as their aging period increased, while the Cs adsorption efficiencies of copper and zinc ferrocyanides did not decrease. The tendencies of these ferrocyanides were accelerated by exposure of the solids at a higher temperature for a longer time. Our comprehensive analyses demonstrated that only the oxidizable metals in the MFCs can be oxidized by aging time and increasing temperature; also, this affects the Cs removal efficiency by decreasing the exchangeable sites in the solids. The chemical stability of MFCs is very important for the optimization of the synthesis and storage conditions.

Novel application of nanozeolite for radioactive cesium removal from high-salt wastewater

Finding a striking peculiarity of nanomaterials and evaluating its feasibility for practical use are interesting topics of research. We investigated the application of nanozeolite's outstanding reactivity for a rapid and effective method for radioactive cesium removal in the wastewater generated from nuclear power plant accident, as a new concept. Extremely fast removal of cesium, even without stirring, was achieved by the nanozeolite at efficiencies never observed with bulk materials. The nanozeolite reached an adsorption equilibrium state within 1 min. Cesium adsorption by nanozeolite was demonstrated at reaction rates of orders of magnitude higher than that of larger zeolite phases. This observation was strongly supported by the positive correlation between the rate constant ratio (k2,bulk/k2,nano) and the initial Cs concentrations with a correlation coefficient (R(2)) of 0.99. A potential drawback of a nanoadsorbent is the difficulty of particle settling and separation because of its high dispersivity in solution. However, our results also demonstrated that the nanozeolite could be easily precipitated from the high-salt solution with ferric flocculant. The flocculation index reached a steady state within 10 min. A series of our experimental results met the goal of rapid processing in the case of emergency by applying the well-suited nanozeolite adsorption and flocculation.

Equilibrium, kinetic and thermodynamic study of cesium adsorption onto nanocrystalline mordenite from high-salt solution

In this study, the equilibrium, kinetics and thermodynamics of cesium adsorption by nanocrystalline mordenite were investigated under cesium contamination with high-salt solution, simulating the case of an operation and decommissioning of nuclear facilities or an accident during the processes. The adsorption rate constants were determined using a pseudo second-order kinetic model. The kinetic results strongly demonstrated that the cesium adsorption rate of nano mordenite is extremely fast, even in a high-salt solution, and much faster than that of micro mordenite. In the equilibrium study, the Langmuir isotherm model fit the cesium adsorption data of nano mordenite better than the Freundlich model, which suggests that cesium adsorption onto nano mordenite is a monolayer homogeneous adsorption process. The obtained thermodynamic parameters indicated that the adsorption involved a very stable chemical reaction. In particular, the combination of rapid particle dispersion and rapid cesium adsorption of the nano mordenite in the solution resulted in a rapid and effective process for cesium removal without stirring, which may offer great advantages for low energy consumption and simple operation.

Association between shortened cervical length at 34-36 weeks' gestation and term labour in Asian women

Cervical length was measured at 34-36 weeks' gestation by transvaginal ultrasound. The purpose of measurement of cervical length before term was to reveal the association with the onset of term labour. This was a retrospective study of 362 women who were delivered at term at Mizmedi hospital, between August 2006 and November 2011. There was significant linear correlation between cervical length and the scan-to-labour interval in women with labour before 41 weeks. The measurement of cervical length at 34-36 weeks' gestation might be helpful in predicting the onset of term labour before 41 weeks.

Biosorption of uranium(VI) from aqueous solution by biomass of brown algae Laminaria japonica

The uranium(VI) adsorption efficiency of non-living biomass of brown algae was evaluated in various adsorption experimental conditions. Several different sizes of biomass were prepared using pretreatment and surface-modification steps. The kinetics of uranium uptake were mainly dependent on the particle size of the prepared Laminaria japonica biosorbent. The optimal particle size, contact time, and injection amount for the stable operation of the wastewater treatment process were determined. Spectroscopic analyses showed that uranium was adsorbed in the porous inside structure of the biosorbent. The ionic diffusivity in the biomass was the dominant rate-limiting factor; therefore, the adsorption rate was significantly increased with decrease of particle size. From the results of comparative experiments using the biosorbents and other chemical adsorbents/precipitants, such as activated carbons, zeolites, and limes, it was demonstrated that the brown algae biosorbent could replace the conventional chemicals for uranium removal. As a post-treatment for the final solid waste reduction, the ignition treatment could significantly reduce the weight of waste biosorbents. In conclusion, the brown algae biosorbent is shown to be a favorable adsorbent for uranium(VI) removal from radioactive wastewater.

Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures

This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature.

Effect of Fermi surface nesting on resonant spin excitations in Ba(1-x)K(x)Fe2As2

We report inelastic neutron scattering measurements of the resonant spin excitations in Ba(1-x)K(x)Fe(2)As(2) over a broad range of electron band filling. The fall in the superconducting transition temperature with hole doping coincides with the magnetic excitations splitting into two incommensurate peaks because of the growing mismatch in the hole and electron Fermi surface volumes, as confirmed by a tight-binding model with s(±)-symmetry pairing. The reduction in Fermi surface nesting is accompanied by a collapse of the resonance binding energy and its spectral weight, caused by the weakening of electron-electron correlations.

Prolonged paralysis following mivacurium administration

Mivacurium is a benzylisoquinolone, choline-like, non-depolarizing muscle relaxant. Its onset of action is similar to that of atracurium but its duration of action is shorter (approximately 10-15 minutes). Mivacurium is metabolized by plasma cholinesterases at approximately 70% of the rate of metabolism of suxamethonium. Deficiency or abnormality of plasma cholinesterase may cause the duration of action of both suxamethonium and mivacurium to be greatly prolonged. We describe a case of prolonged mivacurium paralysis after day surgery. Laboratory investigations showed a genetic tendency toward abnormal cholinesterase levels, but markedly depressed cholinesterase activity was suggestive of additional acquired causes. This patient had a history of liver disease, malnutrition and anticholinesterase use, which we believe were the most significant factors involved.

Structure and thermoelectric properties of the new quaternary bismuth selenides A(1-x)M(4-x)Bi(11+x)Se21 (A = K and Rb and Cs; M = Sn and Pb)--members of the grand homologous series Km(M6Se8)m(M(5+n)Se(9+n))

Several members of the new family A(1-x)M(4-x)Bi(11+x)Se21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800 degrees C. The single-crystal structures of K(0.54)Sn(3.54)Bi(11.46)Se21, K(1.46)Pb(3.08)Bi(11.46)Se21, Rb(0.69)Pb(3.69)Bi(11.31)Se21, and Cs(0.65)Pb(3.65)Bi(11.35)Se21 were determined. The compounds A(1-x)M(4-x)Bi(11+x) Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M(5+n)Se(9+n)) has been identified of which the compounds A(1-x)M(4-x)Bi(11+x)Se21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A(1-x)M(4-x)Bi(11+x)Se21.

Spectral analysis of fetal heart rate variability as a predictor of intrapartum fetal distress

OBJECTIVE

To evaluate the usefulness of power spectral analysis on fetal heart rate variability as a new diagnostic method of fetal distress.

STUDY DESIGN

Among 76 pregnant women who underwent computerized electronic fetal monitoring and cord blood gas analysis, we divided them into three groups: normal fetus group (36); presumed distress group (26); and acidemic distress group (14). In order to perform linear analysis on the raw data of the fetal heart rate, after resampling, we performed Fourier transformation and investigated power distributions among very low frequency (VLF), low frequency (LF), high frequency (HF) bands, and autonomic balance (LF/HF).

RESULTS

The results of the spectral analysis showed that in normal fetus group, the difference in the distribution of power spectrums of VLF, LF and HF was significantly higher than in presumed distress group and acidemic distress group. In fetal distress, the LF and VLF value (< or = 0.0023, > or = 0.0437) were good predictors (sensitivity 97.5%, 75.0% and specificity 86.1%, 94.4%). The LF value (< or = 0.0013) was a good predictor in fetal acidemia (sensitivity 97.5% and specificity 86.1%).

CONCLUSIONS

A computerized spectral analysis of fetal heart rate variation is a good predictor of fetal distress, which is made automatically and objectively.

CsBi(4)Te(6): A high-performance thermoelectric material for low-temperature applications

Thermoelectric (Peltier) heat pumps are capable of refrigerating solid or fluid objects, and unlike conventional vapor compressor systems, they can be miniaturized without loss of efficiency. More efficient thermoelectric materials need to be identified, especially for low-temperature applications in electronics and devices. The material CsBi(4)Te(6) has been synthesized and its properties have been studied. When doped appropriately, it exhibits a high thermoelectric figure of merit below room temperature (ZT(max) approximately 0.8 at 225 kelvin). At cryogenic temperatures, the thermoelectric properties of CsBi(4)Te(6) appear to match or exceed those of Bi(2-x)Sb(x)Te(3-y)Se(y) alloys.

CsBi(4)Te(6): A high-performance thermoelectric material for low-temperature applications

Thermoelectric (Peltier) heat pumps are capable of refrigerating solid or fluid objects, and unlike conventional vapor compressor systems, they can be miniaturized without loss of efficiency. More efficient thermoelectric materials need to be identified, especially for low-temperature applications in electronics and devices. The material CsBi(4)Te(6) has been synthesized and its properties have been studied. When doped appropriately, it exhibits a high thermoelectric figure of merit below room temperature (ZT(max) approximately 0.8 at 225 kelvin). At cryogenic temperatures, the thermoelectric properties of CsBi(4)Te(6) appear to match or exceed those of Bi(2-x)Sb(x)Te(3-y)Se(y) alloys.

A case of nephrogenic diabetes insipidus caused by obstructive uropathy due to prostate cancer

Nephrogenic diabetes insipidus (DI) secondary to chronic urinary tract obstruction is a rare disease. The exact cause is unknown but it is likely that increased collecting duct pressures cause damage to the tubular epithelium, resulting in insensitivity to the action of arginine-vasopressin (AVP). A 77-year-old man complaining of polyuria and polydipsia was treated with alpha glucosidase inhibitor under the impression of polyuria due to diabetes mellitus. But his symptoms did not improve. Water deprivation and AVP administration study revealed that the patient had nephrogenic DI. Urinary tract obstruction due to an enlarged prostate was suggested as a principal cause of nephrogenic DI. The patient underwent transurethral resection of the prostate and bilateral subcapsular orchiectomy. After surgery, the urine osmolarity was normalized and the patient became symptom-free. We report a case of nephrogenic DI due to obstructive uropathy which was cured by surgery eliminating obstruction.

Antioxidant effects of extracts from Cassia tora L. prepared under different degrees of roasting on the oxidative damage to biomolecules

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting (unroasted and roasted at 150, 200, and 250 degrees C) on the oxidative damage to deoxyribose, DNA, and DNA base in vitro were investigated. It was found that WECT alone induced a slight strand breaking of DNA. In the presence of Fe(3+)/H(2)O(2), WECT accelerated the strand breaking of DNA at a concentration of 2 microg/mL; however, it decreased with increasing concentrations (>5 microg/mL) of WECT. WECT also accelerated the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2) at a concentration of 0.2 mg/mL but inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2)/ascorbic acid. Furthermore, WECT accelerated the oxidation of 2'-deoxyguanosine (2'-dG) to form 8-OH-2'-dG induced by Fe(3+)-EDTA/H(2)O(2). The prooxidant action of WECT on the oxidation of 2'-dG was in the order of unroasted > roasted at 150 degrees C > roasted at 200 degrees C > roasted at 250 degrees C. The decrease in the prooxidant activity of the roasted sample might be due to the reduction in its anthraquinone glycoside content or the formation of antioxidant Maillard reaction products after roasting. Thus, WECT exhibited either a prooxidant or an antioxidant property in the model system that was dependent on the activities of the reducing metal ions, scavenging hydroxyl radical, and chelating ferrous ion.

Subepithelial hematoma of the renal pelvis simulating neoplasm (Antopol-Goldman lesion)

Subepithelial hematoma of the renal pelvis (Antopol-Goldman lesion) is an extremely rare lesion. We report on a 55-year-old woman who presented with gross hematuria. It was incorrectly diagnosed as renal pelvic cancer and left radical nephroureterectomy with bladder cuff resection was performed. With awareness and high suspicion of Antopol-Goldman lesion in the radiographic differential diagnosis of a renal pelvic mass, this lesion can be treated conservatively or with partial nephrectomy.

Elevated serum nicked and urinary beta-core fragment hCG in preeclamptic pregnancies

OBJECTIVE

To determine whether different molecular forms of hCG in serum and urine are elevated in preeclamptic pregnancies.

METHODS

Forty-three pregnant women were studied: 25 preeclamptic women and 18 normotensive women. Immediately after blood and urine samples were collected, the protease inhibitors leupeptin (0.35 mM) and phenanthroline (22 mM) were added. Various molecular forms of hCG in serum (complete hCG, nonnicked hCG, complete free beta hCG) and in urine (complete hCG, beta-core fragment hCG) were measured by matched immunoassays with a common enzyme-labeled tracer antibody. The nicked hCG assay used a coating of beta-subunit monoclonal antibody with the addition of scavenger antibody to remove nonnicked hCG. Mann-Whitney U test and chi 2 test were used for statistical analyses.

RESULTS

Preeclamptic women had significantly higher median (range) levels of serum complete and nicked hCG than did normotensive women (3620 [850-12,000] versus 2420 [310-4840] ng/mL, P = .024; and 102 [45-275] versus 71 [11-143] ng/mL, P = .010, respectively). Both median (range) urinary complete hCG-creatinine and beta-core fragment-creatinine ratios were significantly higher in preeclamptic women than in normotensive women (37.6 [0.5-185] versus 11.3 [1.9-54], P = .013; and 11.8 [2-67] versus 5.3 [0.3-29], P = .009, respectively).

CONCLUSIONS

Various molecular forms of hCG in serum and urine were significantly higher in preeclamptic than in normotensive pregnancies.

Partial anatomical and physiological characterization and dissociated cell culture of the nervous system of the marine mollusc Aplysia kurodai

Snail nervous systems are powerful tools for neurobiological studies as the biophysical properties of the giant neurons and their neural circuits can be examined in relation to specific behaviors of animals. The marine mollusc Aplysia californica is particularly useful for analyzing the components of learning and memory at the molecular and cellular levels. Here we partially examined the nervous systems of two species (A. kurodai and A. juliana) commonly found along the Korean coast in comparison with that of A. californica, one of the American marine snails. A. kurodai appeared to be identical to A. californica in both anatomical and physiological properties of the nervous system. A. juliana could be distinguished from A. californica in certain morphological aspects of the nervous system. The hemolymph either from A. kurodai or from A. juliana was required for effectively elongating neurite outgrowth of A. kurodai neurons in dissociated cell culture. The cultured cells retained neuronal properties such as neurite outgrowth, synapse formation, and generation of action potentials. The sensory cells of A. kurodai in dissociated cultures showed a response to serotonin (5-HT) of spike broadening and enhanced membrane excitability as in intact ganglia. Therefore, the nervous system and dissociated neuronal culture of A. kurodai may be useful for studying learning and memory in the context-of well-defined neural circuits of A. californica.

Transplantation of reproductive organs

A historical review of the literature concerning replantation and transplantation of reproductive organs has included studies from this laboratory, using rats, over the past 25 years. From the basic observation of ischemic and traumatic injury due to the transplantation, syngeneic testicle transplants, resulting in a partner's impregnation and histological restoration of the testicles, led to human testicular transplantation. As to the ovarian transplants, granulosa-theca cell tumors may transform into malignancies if followed for a prolonged period as intrasplenic ovaries, and high doses (15 to 20 mg/kg b.w.) of azathioprine can produce such malignant tumors in a shorter period. By caval-portal shunt, ovarian hormones enter directly into the portal blood stream and no typical granulosa-theca cell tumors were produced, owing to the fact that the liver cannot degrade all the hormones secreted by both ovaries. While en-bloc vagino-utero-ovarian transplantation in the rat is possible, no impregnation has been yet achieved. Finally, it is hypothesized that those who have acquired microsurgical techniques and have a full understanding of the anatomy of the reproductive system will not only be able to perform replantation of the penis, but also will be capable of allogeneic transplantation of genital organs, whether ethically approved or not, and sooner than one may think. In such cases a penile part may be obtained at a sex-change surgery or from a cadaveric donor, similar to other vital organ transplantation practices.

Effect of caval-portal shunt on ovarian tissue in rats: I. Histological observation

Forty-three female Sprague Dawley rats were divided into five groups, with groups 1-4 subjected to end-to-side caval-portal shunt (CPS). In addition to CPS, group 1 (n = 13), group 2 (n = 10), and group 3 (n = 7) rats had undergone removal of the right ovary and one-half of the left ovary, the left ovary, and one-half of the left ovary, respectively. Group 4 (n = 6) rats were not subjected to ovariectomy. Group 5 (n = 7) animals were not subjected to CPS but underwent left ovarian hemiresection. The ovarian volume of the hemiresected ovaries increased to 393.00 +/- 4.83 mm3 and 126.00 +/- 44.3 mm3 from 18.40 +/- 0.54 mm3 and 18.40 +/- 0.59 mm in groups 1 and 3, respectively, at the end of three postoperative months. The nonresected ovaries enlarged to 339.98 +/- 5.09 mm3 and 226.3 +/- 46.2 mm3 from 36.79 +/- 1.09 mm3 in groups 2 and 3, respectively. When no ovaries were resected, the CPS animals in group 4 showed an increment of ovarian volume of 1.75-2.2 times as much as the preoperative ones. In the animals that had undergone simple hemiovariectomy (group 5), the contralateral ovaries showed a significant increase in volume (40.2 +/- 8.3 mm3 to 243.1 +/- 114.8 mm3) at 3 months. The hemiresected ovarian volume increased from 27.1 +/- 5.5 mm3 to 44.1 +/- 11.8 mm3.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting the prevalence of tinnitus

The prevalence of tinnitus was studied in a large population of noise-exposed workers. It was found that 6.6% had tinnitus which was more than momentary. Results of two other studies were compared. Factors possibly relating to the prevalence of tinnitus were studied. The single most important factor found to be related to tinnitus is hearing level. The higher the hearing level, the faster the rate of increase in the prevalence of tinnitus. Other factors such as sex, age, laterality, smoking and shooting do not seem to have a significant, direct relationship with tinnitus, but they are related to the prevalence of tinnitus indirectly through the influence they have on hearing loss.

The performance of circumaural hearing protectors by dosimetry

The performance of earmuffs in the actual working environment was studied with two modified dosimeters. It was found that personal hearing protection, at least with earmuffs, is a potentially adequate method of protection against noise-induced hearing loss in most industrial working situations. Most of the problems involving the use of hearing protectors in a hearing conservation program can be overcome by education and proper fitting.

Asymmetrical noise exposure and hearing loss among shingle sawyers

Shingle sawyers are exposed to noise predominantly from the left side. This study examined the asymmetry in hearing loss among shingle sawyers and its possible relation to the difference in noise exposure to the two ears. The results suggest that the lateral difference in noise exposure in industry, even in the obvious case of a shingle sawyer, is small. The resulting asymmetrical noise-induced hearing loss is also relatively small. Therefore, significant asymmetry in hearing loss in this type of occupation should be viewed with caution. Special tests and medical examination should be undertaken to determine if there are other contributing factors.

The ear effect as a function of age and hearing loss

Many studies have shown that the right ear statistically is slightly more sensitive than the left ear, particularly in the male adult population. In this study, we examined the lateral difference in hearing sensitivity, termed the ear effect here, in an industrial noise-exposed, nonshooting population, by sex, age, and hearing level. It was found that the male population had a larger ear effect (right ear being more sensitive) than the female population. The magnitude of the ear effect was found to be significantly related to the hearing threshold level. The ear effect was highest when the threshold was between 30- and 40-dB HL. Several possible causes for the ear effect are discussed.

Lateral differences in susceptibility to noise damage

Usually equal noise exposure is considered to cause symmetrical hearing loss. In studying 1 461 audiometric records of claims for noise-induced hearing loss, it was found that 69 (4.7%) had a well-defined pattern of hearing loss in which only 2 kHz is asymmetrical by 20 dB or more. Audiograms of this type suggest that the cochlea of the worse ear has been damaged more extensively towards the apex. Of the 69 cases with a 2-kHz asymmetry, 82.6% had worse hearing thresholds in the left ear at 2 kHz. In 50% of the 69 cases, the asymmetry could not be accounted for even after the examination of their medical, occupational and nonoccupational histories. It is believed that the asymmetry at 2 kHz is a manifestation of a lateral difference in susceptibility to noise damage and that the left ear is the more susceptible one in the majority of cases.

Temporal integration: its relationship with noise-induced hearing loss

Hearing thresholds at 0.5, 1, 2, 3, 4, and 6 kHz were measured with 20-msec and 500-msec tones for 14 normal hearers and 23 subjects with nose-induced hearing loss. The differences between the hearing thresholds of the long- and short-duration tones were plotted as a function of frequency (temporal integration function). Preliminary data from this study suggest that temporal integration function is more closely related to the configuration of the audiogram than the hearing threshold level when data of an individual are concerned. The results also support the notion that temporal integration function is affected by the presence of 'subclinical' cochlear lesions.

Tone-on-tone masking in subjects with normal hearing and with sensorineural hearing loss

Quiet and masked thresholds were obtained from 5 subjects with normal hearing and 31 subjects with sensorineural hearing loss. Maskers were pure tones varying in frequency and intensity. The hearing-impaired subjects showed an abnormal spread of masking when masking was measured in terms of masked threshold. The abnormal spread of masking seems to be related to both the hearing threshold of the masker and the quiet threshold of the test signal. The notch due to detection of combination tones found on the high-frequency slope of masked audiograms of normal subjects (obscuring the actual extent to which the signal is masked) tends to accentuate the apparent abnormal upward spread of masking in the hearing-impaired subjects. The abnormal spread in the latter case is real, but comparison with the normal case must take the notch into account.

Masking, temporal integration, and sensorineural hearing loss

This study was undertaken basically to examine the effect of white noise masking on temporal integration and how the frequency dependence of temporal integration is related to hearing loss. The threshold differences between 500-msec and 20-msec tones at .5, 1, 2, and 4 kHz were found for 147 ears of 86 subjects with normal hearing and with various amounts of cochlear hearing loss. Thresholds were measured in three levels of background white noise--30, 60, and 90 dB SPL. The principal finding was that temporal integration is frequency dependent and this dependence is not an epiphenomenon of the decrease in temporal integration due to cochlear hearing loss.

Shooting, sensorineural hearing loss, and workers' compensation

Pure-tone audiograms of 29,953 workers with histories of shooting and occupational noise exposure were analyzed. The analysis was based on the asymmetry of hearing loss. Results of this study show that shooting is related to asymmetrical hearing loss, suggesting that shooting may cause an additional amount of hearing loss other than that due to occupational noise exposure. Asymmetry was found to increase as the length of shooting history increased and was significant only at 2 kHz and above and most prominent at 4 kHz. Results also indicated that as long as compensable frequencies remain below 3 kHz the shooting effect is not likely to influence compensation for workers with histories of less than ten years of shooting.

Speech discrimination and effectiveness of hearing aids under listening conditions similar to those of a transit operator

Some controversy exists regarding regulations that permit hearing impaired drivers to operate passenger carrying vehicles. In other situations it has been shown that the hearing impaired generally have more difficulty than normals discriminating speech in noise. The present study investigates this under listening conditions simulating those of a transit operator, and also looks at the effects of a hearing aid on speech discrimination in the same situation. One normal hearing group and three groups representing varying degrees of symmetrical sensorineural hearing loss were given a sentence type discrimination test in a background of recorded diesel bus noise at different speech-to-noise ratios. The hearing impaired groups performed more poorly than normals and the use of hearing aids did not affect the performance of the hearing impaired groups. Regulations pertaining to licensing of transit operators should take into account hearing above 2,000 Hz. The results of this study, combined with the possibility of noise damage from amplified noise levels, lead us to conclude that hearing aids should not be worn by transit operators on the job.

Hearing loss due to noise trauma

Three different types of noise-induced hearing loss have been reported in the literature. The two less common types are described here. Three cases of these two types from our clinic are reported. Since these 2 types of noise-induced hearing loss often involve low frequencies it is important to recognize them in compensation cases.

Meanings of a double-notch audiogram

Audiological findings in patients with histories of noise exposure were examined. 27 patients (1.5%) were found to have audiograms with a double-notch configuration. Information from their occupational history, medical history, and audiological findings was gathered and analysed. Their results were compared with those of 50 random samples of patients without the double-notch audiogram. Analyses suggest that the low frequency notch is probably also caused by noise damage. The low incidence of double-notch audiogram reflects the small proportion of people with susceptibility to noise damage at the 500 Hz to 1 kHz region in addition to the 3 to 6 kHz region. This double-notch configuration could be exaggerated possibly by the release from inhibition by damaged hair cells.

Quiet and masked brief-tone audiometry in subjects with normal hearing and with noise-induced hearing loss

Twenty subjects with normal hearing and 20 with noise-induced hearing loss (NIHL) were tested with brief-tone audiometry at 500 and 4000 Hz in both quiet and masked conditions. The two tone durations used were 20 and 500 msec. The masker was a continuous white noise at 90 dB SPL. Results are consistent with other studies in that subjects with NIHL showed less temporal integration than normals. The frequency effect was found both in normals and in the hearing-impaired. The discrepancy of results on frequency effect found in the literature was discussed. Also, results suggest that suprathreshold measurement of temporal integration with the masking technique deserves further study.

Is a healthier person less susceptible to noise-induced hearing loss?

Several studies in the literature suggest that poor health is related to hearing loss. One hundred subjects claiming occupational hearing loss were chosen randomly for this study. Information was obtained on employment, noise exposure, medical history, family history, and use of cigarettes, alcohol, and medication. Physical examination audiometric tests, and biological tests were carried out. Computer analysis of the data with chi-square test did not show conclusively that noise-induced hearing loss is related to poor health, indicated by abnormal biological or physical findings, or both. There were, however, some indications that the presence of cardiovascular risk factors may influence hearing loss.

The effect of ear protectors on word discrimination in subject with normal hearing and subjects with noise-induced hearing loss

Two groups of subjects with normal hearing and three groups of subjects with noise-induced hearing loss were studied for the effect of ear protectors on word discrimination in two different speech-to-noise ratios. Various interactions in the analyses of variance were shown to be significant. The important demonstration in this study is that at high speech intensity, subjects with normal hearing should obtain higher word discrimination score with ear protectors than without if the signal-to-noise ratio is high. Albeit, the same is not true for a low signal-to-noise ratio, for a low speech intensity, or when subjects have hearing losses; the improvements in these conditions are not high enough to warrant the disuse of ear protectors. Results are discussed and compared with other studies.

Interaction of kanamycin and noise exposure

The amount of hair cell damage in the cochleas of guinea pigs after exposure to different experimental conditions suggests that a 'safe' level of kanamycin has a potentiating effect on damage due to noise. Such an effect lasts more than 20 days after the cessation of the drug administration.

The effect of masking by noise on word discrimination scores in listeners with normal hearing and with noise-induced hearing loss

Patients with high-frequency hearing loss often complain at the Workers' Compensation Board that they find it difficult to hear speech in a noisy environment. This study was undertaken to test the validity of their complaints. The experiment had a 2x3x3 factorial design. The factors were subject group (normal hearing versus sensorineural hearing loss), stimulus level (65, 75, and 85 dB SPL), and speech-to-noise ratio (5, 12, and 19 dB). There were 6 subjects in each condition. Each subject was tested for his speech discrimination with three CID W-22 50-word lists, one in each of the three different speech-to-noise ratios. Both speech and pink noise were presented through loudspeakers in a sound field. The results support the patients' complaints. Possible explanations for the results are discussed.

Relationship between uncomfortable loudness level and acoustic reflex threshold as a function of hearing loss

While many studies examined the relationship between Acoustic Reflex Threshold (ART) and Uncomfortable Loudness Level (UCL) and the possibility of predicting one from the other, no study to the authors' knowledge has shown the relationship between these two measures with respect to hearing loss, and uses such a relationship to predict either measure from the other plus the hearing loss. To achieve these relationships and uses, 80 Ss were studied, 20 in each of 4 groups, with normal hearing and with mild, moderate, and severe noise-induced hearing loss. ARTs and UCLs were obtained at 0.5, 1, 2, and 4 kc/s. The results demonstrated that db sensation level (SL) of ART and UCL were highly correlated with pure-tone hearing threshold level (HTL). An equation was derived: UCL (in db SL) - ART (in db SL) = 6 - .05 HTL, which shows that the relationship between ART and UCL varies as a function of hearing loss. Data from other studies were compared and discussed.

The effect of middle ear disorders on noise-induced hearing loss

Two groups of subjects, 50 noise-exposed and 50 non-noise-exposed, both with unilateral conductive hearing loss, were studied in terms of the amount of conductive hearing loss and difference in the bone conduction thresholds at 4 kHz between the two ears. The results support the hypothesis that middle ear disorders provide the ear some protection from noise-induced hearing loss.