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Showing papers by "Minia University published in 2007"


Journal ArticleDOI
TL;DR: In this article, the adsorption capacity of each dye-adsorbent system has been determined and the relative costs of dye removal were reported based on adsorptive capacity only.
Abstract: A number of low-cost materials (natural clay, bagasse pith and maize cob) have been used as adsorbents for dyestuffs (Astrazon Blue, Maxilon Red and Telon Blue) in aqueous solutions. The adsorption capacity for each dye-adsorbent system has been determined. The relative costs of dye removal were reported based on adsorption capacity only. The following results were found. First, the relative cost of the removal of Astrazon Blue using natural clay, bagasse pith and maize cob was found to be only 1·7%, 3·9% and 4·1% that of carbon respectively. Second, the relative cost of the removal of Maxilon Red using natural clay, maize cob and bagasse pith was found to be only 2·4%, 8·3% and 10·3% that of carbon respectively. Last, the relative cost of the removal of Telon Blue using maize cob, natural clay and bagasse pith was found to be only 2·9%, 3·0% and 5·2% that of carbon respectively.

250 citations


Journal ArticleDOI
10 Oct 2007-PLOS ONE
TL;DR: Standard criteria for the definition of the different haplogroups is proposed based on the result of mismatch analysis and on the use of sequences of reference for clarifying the nomenclature of mitochondrial haplog groups in other domestic species.
Abstract: Background. From the beginning of domestication, the transportation of domestic animals resulted in genetic and demographic processes that explain their present distribution and genetic structure. Thus studying the present genetic diversity helps to better understand the history of domestic species. Methodology/Principal Findings. The genetic diversity of domestic goats has been characterized with 2430 individuals from all over the old world, including 946 new individuals from regions poorly studied until now (mainly the Fertile Crescent). These individuals represented 1540 haplotypes for the HVI segment of the mitochondrial DNA (mtDNA) control region. This large-scale study allowed the establishment of a clear nomenclature of the goat maternal haplogroups. Only five of the six previously defined groups of haplotypes were divergent enough to be considered as different haplogroups. Moreover a new mitochondrial group has been localized around the Fertile Crescent. All groups showed very high haplotype diversity. Most of this diversity was distributed among groups and within geographic regions. The weak geographic structure may result from the worldwide distribution of the dominant A haplogroup (more than 90% of the individuals). The large-scale distribution of other haplogroups (except one), may be related to human migration. The recent fragmentation of local goat populations into discrete breeds is not detectable with mitochondrial markers. The estimation of demographic parameters from mismatch analyses showed that all groups had a recent demographic expansion corresponding roughly to the period when domestication took place. But even with a large data set it remains difficult to give relative dates of expansion for different haplogroups because of large confidence intervals. Conclusions/Significance. We propose standard criteria for the definition of the different haplogroups based on the result of mismatch analysis and on the use of sequences of reference. Such a method could be also applied for clarifying the nomenclature of mitochondrial haplogroups in other domestic species.

216 citations


Journal ArticleDOI
TL;DR: In this paper, the equilibrium conditions of adsorption of a basic dye on hardwood sawdust were studied using the Langmuir and Freundlich isotherms, and two sets of experiments were carried out at different particle sizes and temperatures.
Abstract: Equilibrium conditions of adsorption of a basic dye on hardwood sawdust were studied using the Langmuir and Freundlich isotherms. Two sets of experiments were carried out at different particle sizes and temperatures. The adsorption of the basic dye on hardwood was found to conform with the two isotherms. The capacity of hardwood for the adsorption of basic dye was found to increase by decreasing the particle size and increasing the temperature. The cost of hardwood adsorbent is only 8.4% that of activated carbon.

209 citations


Journal ArticleDOI
M. A. Kaid1, A. Ashour1
TL;DR: In this article, the structural and optical properties of al-doped zinc oxide (AZO) thin films were examined by X-ray diffraction (XRD) and double-beam spectrophotometry.

133 citations


Journal ArticleDOI
TL;DR: The presence of antibiotic-resistant P. aeruginosa isolates could be attributed to beta-lactamase production and the use of multiple drug resistance efflux pumps.
Abstract: Objectives: To assess the prevalence, levels of antimicrobial susceptibility and resistance mechanisms of Pseudomonas. Methods: A total of 445 clinical isolates and 200 environmental isolates were collected from three hospitals in Minia, Egypt. The MICs of different antibiotics were determined using the agar dilution method. The isolates were tested for b-lactamase production and for the presence of efflux pumps. Results: Out of the 445 clinical specimens, 107 Pseudomonas strains (24%) and 81 Pseudomonas aeruginosa strains were isolated (18.2%). Out of the 200 environmental specimens, 57 Pseudomonas strains (28.5%) and 39 P. aeruginosa strains were isolated (19.5%). Amikacin was the most active drug against P. aeruginosa followed by meropenem, cefepime and fluoroquinolones. P. aeruginosa was highly resistant to all other antibiotics tested. The environmental isolates of P. aeruginosa exhibited higher antibiotic resistance than clinical isolates. Mechanisms of resistance used by P. aeruginosa included b-lactamase production and multiple drug resistance efflux pumps. Our results showed that 29 (36%) of the clinical P. aeruginosa isolates and 37 (95%) of the environmental P. aeruginosa isolates were b-lactamase producers. In addition, P. aeruginosa isolates effectively used an efflux-mediated mechanism of resistance against ciprofloxacin and meropenem, but not gentamicin or cefotaxime. Conclusions: This study examined the prevalence of P. aeruginosa, and its susceptibility patterns to different antibiotics. The presence of antibiotic-resistant P. aeruginosa isolates could be attributed to b-lactamase production and the use of multiple drug resistance efflux pumps.

131 citations


Journal ArticleDOI
TL;DR: Sera from 131 Egyptians were genotyped by restriction fragment-length polymorphism and phylogenetic analyses of sequences from the mid-core and non-structural 5B regions, and subtype 4o showed an association with HCC, which merits further investigation.
Abstract: Egypt has one of the world’s highest prevalences of hepatitis C virus (HCV) infection, with a majority of genotype 4 infections. To explore the genetic diversity of HCV in Egypt, sera from 131 Egyptians [56 from community studies, 37 chronic hepatitis patients, 28 hepatocellular carcinoma (HCC) patients and 10 patients with non-Hodgkin’s lymphoma] were genotyped by restriction fragment-length polymorphism and phylogenetic analyses of sequences from the mid-core and non-structural 5B regions. The different genotyping methods showed good agreement. The majority of the viruses (83 of 131; 63 %) were of subtype 4a, but five other subtypes within genotype 4 were also observed, as well as three genotype 1b, five genotype 1g and one genotype 3a samples. Interestingly, subtype 4o, which was easily identifiable in all three genomic regions, showed an association with HCC (P=0.017), which merits further investigation.

131 citations


Journal ArticleDOI
TL;DR: In this paper, the role of temperature and metal/Te ratio on the composition and crystallization temperature of sulfides and tellurides in the Fe-Cu-Ni-Pd-Pt-Te-S system was evaluated experimentally.
Abstract: We evaluate experimentally the role of temperature and metal/Te ratio on the composition and crystallization temperature of sulfides and tellurides in the Fe–Cu–Ni–Pd–Pt–Te–S system. The monosulfide–sulfide melt partition coefficients decrease with increasing Te concentration and decreasing S/Te ratio of the bulk composition because Pt and Pd are strongly complexed by Te and thus stabilized in the melt phase. The solubility of Te in Fe-rich monosulfide solid solution and Cu-rich intermediate solid solution is around 0.2 wt% and largely insensitive to temperature down to 320°C, indicating that Te substitutes in sulfides as an anion replacing S. Solid solution between moncheite PtTe2 and merenskyite PdTe2 is more limited than implied by natural telluride phase compositions. Solid solution between tellurides with variable metal/Te stoichiometry also appears to be limited, again in contrast to natural phase compositions. Natural tellurides are compositionally more flexible than the experimental compositions synthesized here. It is argued, therefore, that many natural tellurides coexisting with sulfides may be metastable, i.e. modified by exsolution of a Ni–Te component from the coexisting high-temperature sulfides. From Te concentrations in monosulfide solid solution it is deduced that natural sulfide–telluride assemblages record equilibration temperatures as low as 200–250°C. With respect to Te and precious metal mineralization, no systematic temperature difference exists between sulfide–telluride ores referred to in the descriptive ore petrography literature as magmatic and ores termed hydrothermal in origin.

130 citations


Journal ArticleDOI
TL;DR: Only limited duration of sun exposure, contributing 55% to the variance of 25 OHD, limited areas of skin exposed, and increased number of pregnancies, were significant determinants of vitamin D levels in patients.
Abstract: Chronic low back pain (LBP) is an extremely common problem in practice, where it is often labeled idiopathic. No sufficient studies have been conducted to analyze the contribution of hypovitaminosis D to the etiology of chronic LBP in populations wherein vitamin D deficiency is endemic. The present study was, therefore, carried out to examine hypovitaminosis D and its determinants in female patients with chronic LBP during the childbearing period. Sixty female patients complaining of LBP lasting more than 3 months were clinically studied rheumatologically and neurologically. Questionnaires and indices quantifying risk factors associated with vitamin D deficiency were utilized. Biochemical assays of serum calcium, phosphorus, alkaline phosphatase (ALP), parathormone (PTH), and 25-hydroxyvitamin D (25 OHD) were performed and compared to those of 20 matched healthy controls. The determinants of vitamin D levels in patients were examined by stepwise regression. Patients with LBP had significantly lower 25 OHD levels (p < 0.05) and significantly higher PTH (p < 0.05) and ALP (p < 0.001) than controls, although there were no significant group differences in calcium and phosphorus. Hypovitaminosis D (25 OHD < 40 ng/ml) was found in 49/60 patients (81%) and 12/20 (60%) of controls, with an odds ratio of 2.97. Although many risk factors related to sun exposure, clothing, diet, and pregnancy were significantly correlated with vitamin D levels in patients, only limited duration of sun exposure, contributing 55% to the variance of 25 OHD, limited areas of skin exposed (13%), and increased number of pregnancies (2%), were significant determinants of vitamin D levels in patients. Despite the sunny climate, hypovitaminosis D is prevalent among Egyptian women in the childbearing period, especially those presenting with chronic LBP, where it is associated with hyperphosphatasia and hyperparathyroidism, without alterations in serum calcium. The major determinant of hypovitaminosis D in our patients is limited sun exposure.

119 citations


Journal ArticleDOI
TL;DR: In this article, a dilute solution of a basic dyestuff was decoloured by using hardwood sawdust as an adsorbent and the activation energy of the process was 9.83 kJ mol−1 which shows that the rate controlling step is intraparticle diffusion.
Abstract: Decolourisation of a dilute solution of a basic dyestuff was carried out by using hardwood sawdust as adsorbent. At 80°C 85% decolourisation occurred within 100 min at an initial concentration (Co) of 200 mg dm−3. There was a 44% reduction in contact time when the temperature was raised from 25 to 80°C. The rate parameter for different initial dye concentrations was found to follow the equation: kco=4.20Co0.88 and the rate parameter for different mean diameter dm followed the equation kdm=4.1 (l/dm)0.135. The activation energy of the process was 9.83 kJ mol−1 which shows that the rate controlling step is intraparticle diffusion.

113 citations


Journal ArticleDOI
TL;DR: In this article, Petrological and geochemical data are presented for a selection of the two groups, the I-type, El Bula tonalite-granodiorite suite, and the A-type Lomân alkali granites, with the aim of discussing their origin and geotectonic implications.

101 citations


Journal ArticleDOI
TL;DR: The literature on synthesis and applications of aroyl substituted thioureas is updated to 2006 as discussed by the authors, with a focus on the relationship of structural features of the tracers to their applications in such diverse areas as trace analysis of metals, materials science and agriculture.

Journal ArticleDOI
TL;DR: Carnosine can be useful as a prophylactic treatment to protect the liver against hypoxia-reoxygenation damage and is markedly ameliorated by pre-ischemic treatment with carnosine.

Journal ArticleDOI
TL;DR: MC- and Alg-based tablet formulations showed high release-retarding efficiency, and good reproducibility and stability of the drug release profiles when stored for 6 months in ambient room conditions, suggesting that MC and AlG are good candidates for preparing modified-release baclofen tablet formulations.
Abstract: This work aims at investigating different types and levels of hydrophilic matrixing agents, including methylcellulose (MC), sodium alginate (Alg), and sodium carboxymethylcellulose (CMC), in an attempt to formulate controlled-release matrix tablets containing 25 mg baclofen. The tablets were prepared by wet granulation. Prior to compression, the prepared granules were evaluated for flow and compression characteristics. In vitro, newly formulated controlled-release tablets were compared with standard commercial tablets (Lioresal and baclofen). The excipients used in this study did not alter physicochemical properties of the drug, as tested by the thermal analysis using differential scanning calorimetry. The flow and compression characteristics of the prepared granules significantly improved by virtue of granulation process. Also, the prepared matrix tablets showed good mechanical properties (hardness and friability). MC- and Alg-based tablet formulations showed high release-retarding efficiency, and good reproducibility and stability of the drug release profiles when stored for 6 months in ambient room conditions, suggesting that MC and Alg are good candidates for preparing modified-release baclofen tablet formulations.

Journal ArticleDOI
TL;DR: The chloroform extract of the aerial parts of Caralluma russelsiana yielded four acylated pregnane glycosides, namely russeliosides E-H, three of which were found now.

Journal ArticleDOI
TL;DR: Piroxicam has a time-dependent toxic effect on both liver and kidney tissues and there was a positive correlation between these pathological changes and the increased treatment periods.
Abstract: Piroxicam is a non-steroidal anti-inflammatory drug widely used in rheumatic diseases. The aim of this study was to investigate Piroxicam-induced histopathological changes in livers and kidneys of male albino mice. Methods: Animals were classified into a control group and 4 treated groups. Piroxicam was injected intraperitoneally using 0.3 mg/kg every day for four weeks. Each week a group of mice was sacrificed. Liver and kidneys were obtained for histological and histochemical examination. Animals were classified into a control group and 4 treated groups. Piroxicam was injected intraperitoneally using 0.3 mg/kg every day for four weeks. Each week a group of mice was sacrificed. Liver and kidneys were obtained for histological and histochemical examination. Results: Liver sections appeared with inflammatory cellular infiltration, vacuolated hepatocytes, dilated sinusoids, and increased number of Kupffer cells. Kidney sections appeared with some cellular inflammations. The glomeruli were shrunk resulting in widening of the urinary space. Oedema and vacuolations were noticed in the tubular cells. There was a positive correlation between these pathological changes and the increased treatment periods. Histochemical staining revealed that glycogen and protein contents had decreased in the hepatocytes. This depletion worsened gradually in liver cells after two, three, and four weeks. Similar depletion of the glycogen content was observed in kidney tissue. However, protein content appeared to be slightly decreased in the kidney tubules and glomeruli. Incensement of coarse chromatin in the nuclei of hepatocytes, Kupffer cells and most inflammatory cells were detected by Fuelgen method. Kidney tissues appeared with a severe decrease in coarse chromatin in the nuclei. Liver sections appeared with inflammatory cellular infiltration, vacuolated hepatocytes, dilated sinusoids, and increased number of Kupffer cells. Kidney sections appeared with some cellular inflammations. The glomeruli were shrunk resulting in widening of the urinary space. Oedema and vacuolations were noticed in the tubular cells. There was a positive correlation between these pathological changes and the increased treatment periods. Histochemical staining revealed that glycogen and protein contents had decreased in the hepatocytes. This depletion worsened gradually in liver cells after two, three, and four weeks. Similar depletion of the glycogen content was observed in kidney tissue. However, protein content appeared to be slightly decreased in the kidney tubules and glomeruli. Incensement of coarse chromatin in the nuclei of hepatocytes, Kupffer cells and most inflammatory cells were detected by Fuelgen method. Kidney tissues appeared with a severe decrease in coarse chromatin in the nuclei. Conclusion: Piroxicam has a time-dependent toxic effect on both liver and kidney tissues. Key Words: Histology, piroxicam, liver, kidney, mice.

Journal ArticleDOI
TL;DR: An HEV-specific interferon-gamma (IFN-γ) ELISPOT assay was optimized to analyze HEv-specific CMI responses, which correlated strongly and significantly with anti-HEV ELISA positive/negative results.

Journal ArticleDOI
TL;DR: In Egyptians with chronic HCV, young patients with low levels of HA are at very low risk of fibrosis, and this can limit the number of liver biopsies to those whose clinical findings conflict with the biomarker results.

Journal ArticleDOI
TL;DR: A set of six peptides distinguished with high prediction accuracy HCC from controls in an Egyptian population with a high rate of chronic HCV infection by mass spectrometric analysis of enriched serum.
Abstract: Hepatocellular carcinoma (HCC) represents an important public health problem in Egypt where up to 90% of HCC cases are attributable to hepatitis C viral (HCV) infection. Serum alpha-fetoprotein is elevated in only approximately 60% of HCC patients. The development of effective markers for the detection of HCC could have an impact on cancer mortality and significant public health implications worldwide. The objective of our study was to assess six candidate markers for detection of HCC identified by mass spectrometric analysis of enriched serum. The study examined 78 HCC cases and 72 age- and gender-matched cancer-free controls recruited from the Egyptian population. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometric analysis of enriched low-molecular weight fraction of serum was used for identification of the candidate markers. Our analyses show that all six candidate markers are associated with HCC after adjustment for important covariates including HCV and hepatitis B viral infections. The marker candidates are independently predictive of HCC with areas under the receiver operating characteristic (AuROC) curve ranging from 63-93%. A combination of the six markers improves prediction accuracy to 100% sensitivity, 91% specificity and 98% AuROC curve in an independent test set of 50 patients. Two of the candidate markers were identified by sequencing as fragments of complement C3 and C4. In conclusion, a set of six peptides distinguished with high prediction accuracy HCC from controls in an Egyptian population with a high rate of chronic HCV infection. Further evaluation of these marker candidates for the diagnosis of HCC is needed.

Journal ArticleDOI
TL;DR: Microwave irradiation can be used as a facile and general method for the construction of a wide variety of triazoloquinzolinones and benzimidazoquinazolinones.
Abstract: Benzimidazoquinazolinones and related quinazolines are classes of heterocycles that are of considerable interest because of the diverse range of their biological properties. Although numerous classes of quinazolines have been conventionally synthesized, their syntheses have been suffered due to the multiple steps that sometimes have described in their preparation and also their chemical transformations that have been taken hours or even days to be completed. However, microwave energy can offer numerous benefits for performing synthesis of organic compounds including reduced pollution, increased reaction rates, yield enhancements, and cleaner chemistries.

Proceedings ArticleDOI
28 Oct 2007
TL;DR: FiVaTech is a page-level data extraction system which deduces the data schema and templates for the input pages generated from a CGI program, and uses tree templates to model the generation of dynamic Web pages.
Abstract: In this paper, we proposed a new approach, called FiVaTech for the problem of Web data extraction. FiVaTech is a page-level data extraction system which deduces the data schema and templates for the input pages generated from a CGI program. FiVaTech uses tree templates to model the generation of dynamic Web pages. FiVaTech can deduce the schema and templates for each individual Deep Web site, which contains either singleton or multiple data records in one Web page. FiVaTech applies tree matching, tree alignment, and mining techniques to achieve the challenging task. The experiments show an encouraging result for the test pages used in many state-of-the-art Web data extraction works.

Journal ArticleDOI
TL;DR: The past population dynamics of four domestic and one wild species of bovine were estimated using Bayesian skyline plots, a coalescent Markov chain Monte Carlo method that does not require an assumed parametric model of demographic history.
Abstract: The past population dynamics of four domestic and one wild species of bovine were estimated using Bayesian skyline plots, a coalescent Markov chain Monte Carlo method that does not require an assumed parametric model of demographic history. Four domestic species share a recent rapid population expansion not visible in the wild African buffalo (Syncerus caffer). The estimated timings of the expansions are consistent with the archaeological records of domestication.

Journal ArticleDOI
TL;DR: In this article, amorphous tungsten trioxide (a-WO 3 ) thin films were prepared by thermal evaporation technique and the electrical conductivity and dielectric properties of the prepared films have been investigated.
Abstract: Amorphous tungsten trioxide (a-WO 3 ) thin films were prepared by thermal evaporation technique. The electrical conductivity and dielectric properties of the prepared films have been investigated in the frequency range from 100 Hz to 100 kHz and in the temperature range 293–393 K. In spite of the absence of the dielectric loss peaks, application of the dielectric modulus formulism gives a simple method for evaluating the activation energy of the dielectric relaxation. The frequency dependence of σ ( ω ) follows the Jonscher’s universal dynamic law with the relation σ ( ω ) = σ dc + Aω s , where s is the frequency exponent. The conductivity in the direct regime, σ dc , is described by the small polaron model. The electrical conductivity and dielectric properties show that Hunt’s model is well adapted to a-WO 3 films.

Journal ArticleDOI
TL;DR: Sequence variation in the hypervariable domain-1 of the mitochondrial (mt) control region of hares with different coat colour from north-central Tunisia and NW Egypt is studied to test Petter's hypothesis that North African hares belong to L. capensis, and indicated occurrence of introgression and/or shared ancestral polymorphism.

Journal ArticleDOI
TL;DR: The results indicate that threshold and amplitude measures fail to detect peripheral pathology until some relatively high threshold level of damage has been exceeded, which has important implications for monitoring peripheral damage and interpreting electrophysiological test results in animals and humans.

Journal ArticleDOI
TL;DR: A significant reduction of AGE‐induced NF‐κB‐activation and Il‐6 expression was observed, which points to potential antioxidative qualities of TQ.
Abstract: The inhibitory effects of thymoquinone (TQ) on activation of the redox-sensitive transcription factor nuclear factor kappa B (NF-κB) and interleukin-6 (IL-6) were studied in vitro. Human proximal tubular epithelial cells (pTECs) were cultivated and stimulated with advanced glycation end products (AGEs) and the effects of TQ were studied. A significant reduction of AGE-induced NF-κB-activation and Il-6 expression was observed. This points to potential antioxidative qualities of TQ. Copyright © 2007 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, compositional dependencies of the optical properties of amorphous antimony selenide Sb x Se (1−x) (with 5≤x≤20 at%) prepared by thermal evaporation have been studied.

Journal ArticleDOI
TL;DR: The solubilizing power, dissolution-enhancing effect, and analgesic effect enhancer ability toward the drug make Tris particularly suitable for developing a reduced-dose, fast-release solid oral dosage form of nimesulide.
Abstract: The solubilizing and absorption enhancer properties towards nimesulide (ND) of tromethamine (Tris) and polyvinylpyrrolidone (PVP) have been investigated. Solid binary systems were prepared at various drug-polymer ratios by mixing or coprecipitation, characterized by differential scanning calorimetry, X-ray diffractometry, and Fourier transform infrared spectroscopy, and tested for dissolution behavior. Both carriers improved drug dissolution and their performance depended on concentration of the hydrophilic carrier in coprecipitates. Tris was more effective than PVP, despite the amorphizing power of PVP as revealed by solid state analyses. Complete drug amorphiztion was attained at 1∶3 (wt/wt) drug: PVP, 25% (wt/wt) ND in PVP. According to thermal behavior of ND and Tris, ND-Tris systems present a eutectic behavior. The eutectic composition was 30% ND-70% Tris at ∼129°C. Amorphous ND-PVP and eutectic ND-Tris mixtures showed an improvement of 5.55 and 6.6 times of drug dissolution efficiency, respectively. In vivo experiments in mice demonstrated that administration of 60 mg/kg of drug coprecipitated with PVP or Tris resulted, respectively, in a 50% and 94% reduction of acetic acid-induced writhings in comparison with pure drug, which, instead, was statistically ineffective as compared with the control group. Moreover, the eutectic mixture of ND-Tris demonstrated antiwrithing potency 1.88 times higher than amorphous ND-PVP coprecipitate. Thus, the solubilizing power, dissolution-enhancing effect, and analgesic effect enhancer ability toward the drug make Tris particularly suitable for developing a reduced-dose, fast-release solid oral dosage form of nimesulide.

Journal ArticleDOI
TL;DR: In this paper, the authors considered the problem of a three-level atom interacting with a single mode of the quantized electromagnetic cavity field and derived the general forms for both the constants of motion and the wavefunction when the atom is initially prepared in one of its states.
Abstract: In this paper, the problem of a three-level atom interacting with a single mode of the quantized electromagnetic cavity field is considered. The considered theoretical model describes the distinct configurations of a three-level atom. Also, this model includes a detuning and arbitrary forms of both the field and the intensity-dependent atom-field coupling. We obtain the general forms for both the constants of motion and the wavefunction when the atom is initially prepared in one of its states. We use this model for computing a number of statistical aspects of the three-level system. As an illustration, we use the model for studying the time evolution of the second-order correlation function when the atom is initially in an upper state and the field is considered in a coherent state.

Journal ArticleDOI
TL;DR: The results support auditory nerveMyelinopathy as a possible pathomechanism of auditory neuropathy but indicate that myelinopathy must be severe before physiological measures are affected.
Abstract: The goals were to study the physiological effects of auditory nerve myelinopathy in chinchillas and to test the hypothesis that myelin abnormalities could account for auditory neuropathy, a hearing disorder characterized by absent auditory brainstem responses (ABRs) with preserved outer hair cell function. Doxorubicin, a cytotoxic drug used as an experimental demyelinating agent, was injected into the auditory nerve bundle of 18 chinchillas; six other chinchillas were injected with vehicle alone. Cochlear microphonics, compound action potentials (CAPs), inferior colliculus evoked potentials (IC-EVPs), cubic distortion product otoacoustic emissions and ABRs were recorded before and up to 2 months after injection. Cochleograms showed no hair cell loss in any of the animals and measures of outer hair cell function were normal (cubic distortion product otoacoustic emissions) or enhanced (cochlear microphonics) after injection. ABR was present in animals with mild myelin damage (n = 10) and absent in animals with severe myelin damage that included the myelin surrounding spiral ganglion cell bodies and fibers in Rosenthal's canal (n = 8). Animals with mild damage had reduced response amplitudes at 1 day, followed by recovery of CAP and enhancement of the IC-EVP. In animals with severe damage, CAP and IC-EVP thresholds were elevated, amplitudes were reduced, and latencies were prolonged at 1 day and thereafter. CAPs deteriorated over time, whereas IC-EVPs partially recovered; latencies remained consistently prolonged despite changes in amplitudes. The results support auditory nerve myelinopathy as a possible pathomechanism of auditory neuropathy but indicate that myelinopathy must be severe before physiological measures are affected.

Journal ArticleDOI
TL;DR: In this paper, the electron dynamics during the mode transition (E- to H-mode) in a hydrogen radio-frequency (RF) inductively coupled plasma are investigated using space and phase resolved optical emission spectroscopy.
Abstract: Changes of the electron dynamics during the mode transition (E- to H-mode) in a hydrogen radio-frequency (rf) inductively coupled plasma are investigated using space and phase resolved optical emission spectroscopy. The E-mode is characterized through relatively weak optical emission which is strongly modulated on a nanosecond time scale during the rf-cycle, with one pronounced maximum per cycle. The modulation in H-mode, with twice the rf-frequency, is significantly weaker while the emission intensities are about two orders of magnitude higher. In particular the transition between these two modes is studied under variations of rf-power input and gas pressure. Characteristic spatio-temporal structures are observed and can be understood in the frame of a simple model combining both coupling mechanisms in the transition regime.