Rt Values Research Articles

Subjective evaluation of new room acoustic measures

A series of experiments were conducted to evaluate several acoustical measures as predictors of subjective judgments. Subjects were asked to rank binaurally reproduced sound fields in terms of loudness, clarity, reverberance, bass, treble, envelopment, apparent source width, and overall preference. The binaural impulse responses were measured in several North American concert halls and were chosen so as to cover as broad a range as possible of RT, EDT, C80, G, IACC, and LF values. The results of these tests were then correlated with the various octave-band objective measures to find the best predictor of each subjective parameter. New objective quantities were found that are correlated with loudness, clarity, bass, and treble judgments. The relative importance of the various subjective parameters to the overall preference of these sound fields was also examined.

Computerized Old E-Log Analysis of the Pennsylvanian Strawn (Cross Cut/Morris) Sandstone, TWP and Busher Fields, Runnels County, Texas: ABSTRACT

In the area of the TWP and Busher fields approximately 15 percent of the wells were logged with old electric logs (SP-LATERAL-LN-SN-ML). In order to be able to determine net pay thicknesses and to calculate volumetric oil reserves for the Strawn pay in these two fields log analysis of the wells with Old E-Logs should be included. The Old E-Logs were first digitized and then loaded into a computer program called Old E-Log Advisor (OEA). In the program the electrode spacings of the Lateral (LAT), Long Normal (LN), and Short Normal (SN) logs were required as input became corrections for bad thickness and the method of Rt determination are a function of tool spacing. Porosities were calculated from both the microlog (ML) and the Short Normal log, and the volume of clay was determined from the SP. Before the calculation of net pay and hydrocarbon pore-feet thicknesses, the log was displayed like a modern log with the SP in track No. 1, the SN-LN-Rt in track No. 2 (logarithmic scale), and the Porosity in track No. 3. The reasons for re-displaying the old log data like a modem log was to first observe and compare the old log data withmore » nearby modern logs and to be able to observe resistivity invasion profiles (SN-LN-Rt), When the porosity and Rt values determined from the old log data were comparable to the modern log data, net pay and hydrocarbon pore-feet thicknesses were determined. In the example presented there are two thin ( 8%, and Sw < 50% only the upper sand contained net pay, because the lower sand is too shaly and has low permeability.« less

Pharmacokinetics and Pharmacodynamics of β&lt;sub&gt;2&lt;/sub&gt;-Agonists (in the Light of Fenoterol)

As an example of beta 2-agonists fenoterol was used in this study on 27 patients with chronic obstructive airways diseases (COAD). After refraining from any kind of bronchodilator during 12 h the patients were given the drug in a crossover design in three groups. Using aerosol inhalation, intravenous route and nasal instillation we measured the response of airway resistance, intrathoracic gas volume and fenoterol plasma concentrations. The plethysmographic measurement of airways resistance (Rt) and intrathoracic gas volume showed comparable results of bronchodilation (at different dosages) for each of the routes. Even the onset of action was nearly the same with all the different routes. The amount of bronchodilatation was in the range of 59% of the initial Rt values. The duration of bronchodilatation was much longer after metered dose inhalers (MDI) inhalation ( > 4 h) than after intravenous routes. The duration after nasal administration was in between. The infusion maintains its effect only as long as the infusion is given. The bronchodilation response induced by fenoterol reaches the same values with different routes of administration and depends on the amount of decrease of airway obstruction. The highest plasma concentrations were reached with the intravenous boluses. Immediately after injection the concentration decreased rapidly. The maximum plasma concentrations after MDI were around 20% of that after the intravenous route for the same bronchodilatation. The heart rate is a function of the plasma concentration. At low concentrations such as after aerosol inhalation of 200 micrograms the influence on the heart rate is not significant. After aerosol inhalation the effect at the receptor can be calculated to be > 7 times stronger than seen from any plasma concentration after intravenous administration. It is assumed that there are structures near the beta 2-bronchodilator receptor which are responsible for the long-lasting effect that is observed only after aerosol inhalation. These depot structures cannot be reached from the plasma in concentrations needed under in vivo conditions. Loss of these structures shortens the duration of the bronchodilator effect. In respect to effect/side effect relationship, more frequent administration of smaller doses may be the best method for administering beta 2-agonists as aerosols in patients with COAD. For many patients with severe forms of this disease, individual optimal dosage with MDI has to be defined following repeated measurements of the airway obstruction so as to achieve the best possible bronchodilatation.

Competing exchange interactions and their relevance for the magnetisation process in RMn 6- xCr xSn 6 powders (R=Y, Gd, Tb, Dy, Ho, Er)

The free-powder magnetisation of RMn 6- x Cr x Sn 6 compounds has been measured for compounds with R = Y, Gd, Tb, Dy, Ho, Er in fields up to 38 T, and interpreted in terms of simple model, which is also outlined in this paper. From the measurements, estimates for the R-3d mean-field coupling constant ( n RT) could be derived for the cases where R = Gd, Tb, Dy, Ho, Er. In turn, the n RT values can be related to the microscopic spin-coupling constant ( J RT). In the case of YMn 6Sn 6 the high-field measurement presents evidence for a very weak antiferromagnetic coupling between the Mn layers. Furthermore, values for the Mn moments (μ Mn) were also derived from the magnetisation measurements. The estimated μ Mn values are of the order of 2.0μ B.

Concurrent infection of human macrophages with HIV-1 and Mycobacterium avium results in decreased cell viability, increased M. avium multiplication and altered cytokine production.

The effects of a concurrent HIV-1 and Mycobacterium avium infection in vitro were assessed in human peripheral blood-derived macrophages (M phi). M phi were infected with HIV-1Ba-L strain for 14 days then infected with M. avium (HIV/M. avium) or treated with LPS (HIV/LPS). At various times after M. avium or LPS treatment, Mo phi cultures were harvested for quantitation of HIV and M. avium replication, as well as M phi cellular viability. In addition, mRNA and supernatants were collected for assessment of induction of the cytokines TNF-alpha, IL-1 beta and IL-6. M. avium multiplication was greater in HIV-infected M phi, whereas no difference in virus production, based on p24 and RT values, was observed between HIV-infected cells and HIV/M. avium or HIV/LPS M phi. M. avium infection of HIV-1-infected M phi also caused a decrease in viability of the M phi. HIV-1/M. avium-infected M phi had a 24 h delay in induction of TNF-alpha steady state mRNA when compared with HIV/LPS or M. avium only or LPS-only treated M phi. HIV infection also increased the amount and the length of induction of IL-1 beta and IL-6 steady state mRNA stimulated by either M. avium or LPS. In addition, prolonged and increased protein production of TNF-alpha, IL-6, and IL-1 beta was observed in HIV/M. avium-infected cells when compared with the other treatments. In direct contrast to M. avium infection, no significant differences in LPS-induced protein production of the three cytokines was observed between HIV-1-infected and -noninfected M phi. Treatment of HIV/M. avium-infected cells with human rGM-CSF did not increase either the time or quantity of induction of TNF-alpha mRNA or protein production in HIV/M. avium-infected M phi. The increase in M. avium numbers, dysregulation of cytokine production, and subsequent cell death seen in vitro in HIV/M. avium-infected human M phi may reflect part of the underlying cause of the highly disseminated M. avium disease pattern observed in AIDS patients.

ELECTRICAL CONDUCTIVITY OF COBALT-SUBSTITUTED BaZn-W HEXAGONAL FERRITES

The D.C. electrical conductivity of cobalt substituted BaZn-W hexagonal ferrites has been studied as a function of composition and temperature over a temperature range of 300–800 K. It has been observed that the cobalt doping has no influence on the RT values of electrical conductivity, although it does affect many other physical properties. For the first time, the authors noticed two clear and distinct transitions in the conductivity vs. temperature plots of all the samples, the first being ≈475 K and the second near their Curie temperatures. The transition T1 has been attributed to the spin reorientation while the second could be due to the Curie temperature. The activation energy values obtained for the paramagnetic region are found to be higher than those of the ferrimagnetic one for all the samples.

Strength of the R-T exchange coupling in R 2T 17 compounds

The R-T exchange-coupling parameter J RT has been deduced for a number of ferrimagnetic R 2T 17 compounds (Dy 2Co 17, Ho 2Co 17, Er 2Co 17 and Ho 2Co 14Fe 3) from high-field magnetisation measurements on single-crystalline spheres that are allowed to orient themselves in the applied magnetic field. For J RT values ranging from 0.942 to 1.020×10 −22 J have been deduced.

89 ASSESSMENT OF CRANULOCYTE VIABILITY AND NBT REDUCTION TEST RESULTS IN CHILDREN LIVING IN AN AREA POLLUTED BY HEAVY METALS

Granulocyte Viability /G.V.T/ and the Nitro-blue-Tetrazolium reduction test /NBT RT/were evaluated in 258 children living in the area of Zinc Smelting Works, Miasteczko Śląskie/Katowice District/ polluted very strongly by heavy metals /Pb, Zn, Cd/. G.V.T. was determined by Cocchi and al. and NBT RT by Raman and al. method. An increase in the percentage of dead granulocytes and a decrease in the value of NBT RT were found, particularly in the youngest children. A large number of examined children showed an elevated Pb and decreased Zn and Mg levels in blood. A correlation was found between Mg and granulocyte viability /t=-3,011, p<0,05/, as well as between Zn and NBT RT values / t = 4,434, p<0,05/. The results of investigations confirm the negative influence of heavy metals polluted environment on intracellular metabolic processes in granulocytes. This phenomenon is highly intensified in the youngest children. The unfavourable Pb influence on children's immunity may be also caused by the interaction of Pb with Mg and Zn in the process of absorption in the intestinal tract.

Effect of Temperature and Dissolved Oxygen on the Corrosion Behavior of Carbon Steel in High-Temperature Water

Abstract The corrosion behavior of carbon steel in high-temperature water, and the structure and composition of the oxide film were examined as functions of dissolved oxygen concentration (DO), temperature (T), and corrosion time (t). The total amount of iron corroded (WT) was differentiated into the amounts of iron ions in the oxide (WF) and dissolved into the water (WD). The total rate of corrosion (rT), the rate of iron dissolution (rD), and the rate of accumulation of iron in the oxide (rF) were obtained by differentiating the time variations in WT, WF, and WD. The structure and composition of the oxide film were examined by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and transmission and scanning electron microscopy. In general, rT increases with increasing DO and T, rD shows T- and DO-dependent minimum, and there is serious localized corrosion at high DO above 500 ppb. Oxide films consist of magnetite except at T=60°C, DO=50 to 200 ppb where a thin layer of hydrous ferric oxide is formed. At DO=500 ppb , the outermost part of the magnetite changes into γ-Fe2O3, and above DO=1.0 ppm, appreciable amounts of α-Fe2O3 cover the magnetite oxide layer. The rT and rD values are not related to the presence of αFe2O3 or Fe3O4 in the surface structure of the oxide, but clearly decrease as the OH−/Fe mole ratio at the oxide surface increases. The mechanism determining the corrosion rate changes is discussed.

Estimating Organic Maturity from Well Logs, Upper Cretaceous Austin Chalk, Texas Gulf Coast: ABSTRACT

ABSTRACT The Austin Chalk is both a source rock for oil and a fractured reservoir, and the evaluation of its organic maturity from well logs could be an aid to exploration and production. Geochemical and core measurements have shown three zones of organic maturity for source materials: (1) an immature zone above 6000 ft, (2) a peak-generation and accumulation zone from 6000 to 7000 ft, and (3) a mature, expulsion and migration zone below 7000 ft. The response of common well logs identifies these zones. True resistivity (Rt) is low in the immature zone, increases to a maximum in the accumulation zone, and decreases to intermediate values in the migration zone. Density and neutron porosities are different in the immature zone but are nearly equal in the accumulation and migration zones. Correlations with conventional core analyses indicate that Rt values between 9 and 40 ohm-m in the migration zone reflect a moveable oil saturation of 10% to 20% in the rock matrix. The moveable saturation provides oil from the matrix to fractures and is essential for sustained oil production. Therefore, the log evaluation of moveable oil could be important in exploration.

Regeneration of resistance and ion transport in rabbit corneal epithelium after induced surface cell exfoliation.

Exposure of the rabbit corneal surface to a 20-microM digitonin-0.9% NaCl solution leads to permeabilization of the most superficial cells of the stratified epithelium. The devitalized cells exfoliate spontaneously from the corneal surface. Detergent exposure limited to 4-8 min leads to permeabilization and rapid exfoliation of a monolayer of surface cells. Consistent with the presence of the epithelial paracellular permeability barrier in this cell layer, their permeabilization results in complete loss of transepithelial resistance (Rt). Within minutes after detergent removal an initial recovery of Rt can be noticed indicating generation of a new paracellular permeability barrier by the viable sub-surface cells. This recovery proceeds rapidly and Rt reaches within 70 min a maximum equal to greater than 90% of the preexfoliation values (= 2.43 k omega.cm2, n = 22). The Rt recovery is fully blocked in a reversible manner by 10 microM dihydrocytochalasin B. The recovery is not affected by inhibition of protein synthesis with 5 microM cycloheximide. When the ocular surface is treated again with digitonin the permeabilization and exfoliation of a monolayer of cells and loss of Rt are repeated. After the second detergent exposure an initial recovery of Rt occurs as before within minutes. However, the pace of Rt recovery is much slower: 4-5 hr are required to reach a stable maximal Rt values amounting to about 73% of initial control. This recovery can be fully blocked by 5 microM cycloheximide indicating that protein synthesis is required for generation of tight junctions by the second subcellular layer. With only a fraction of Rt recovered, short-circuit currents amounting to, at least, 50% of control values and attributable in part to cell-to-tear movement of Cl- through the apical surface can be measured. This suggests that apical-type Cl- channels are either present in the apically facing membrane of subsurface cells or that they are rapidly inserted in it from preexisting intracellular pools immediately following the devitalization of the surface cells by digitonin.

Reproducibility of responsiveness to a standardized bronchial allergen provocation-Rt compared to FEV1 as measurement of response to provocation.

Standardized bronchial allergen provocation was performed twice in nineteen extrinsic, well defined, stable asthmatic patients, with an interval of median 15 days (range 14-19) to study the reproducibility of the bronchial response. Smoking and medications were withheld prior to the provocation after a rigid scheme. Ten-fold increasing concentrations of allergen solution 0.9 ml were inhaled by tidal volume breathing for 5 min with intervals of 10 min. The bronchial response to inhaled allergen was determined by forced expiratory volume in the first sec (FEV1) and by total resistance to breathing (Rt) determined by an opening interrupter method. The provocation was continued until an allergen concentration causing at least 20%, decrease of the postsaline FEV1 or a 40% increase in Rt was reached. A PC20-FEV1 and a PC40-Rt was calculated by interpolation on the log-dose-response curve. The reproducibility of PC20-FEV1 allergen was high with a 95% confidence interval (CI) for a single determination being the observed value +/- 0.83, ten-fold concentration difference, the intraclass correlation (IC) was 0.99 and the coefficient of variation 8.46%. Concerning PC40-Rt a 95% CI for a single determination was calculated being the observed value +/- 0.58, ten-fold concentration difference, IC was 0.99 and the coefficient of variation was 5.79%. No significant correlation was found between differences in pre-challenge FEV1 and Rt values and the corresponding PC20-FEV1 and PC40-Rt values. Least square regression between PC20-FEV1 and PC40-Rt was performed for the first and the second provocation (P less than 0.05). We conclude that bronchial allergen challenge performed in stable asthmatics is highly reproducible and as such a valuable test in the diagnosis of allergic asthma when connected with anamnesis, skin-prick test and the level of specific immunoglobulin E in peripheral blood.

Modeling optical and thermal distributions in tissue during laser irradiation.

The propagation of light energy in tissues is an important problem in phototherapy, especially with the increased use of lasers as light sources. Often a slight difference in delivered energy separates a useless, efficacious, or disastrous treatment. Methods are presented for experimental characterization of the optical properties of a tissue and computational prediction of the distribution of light energy within a tissue. A standard integrating sphere spectrophotometer measured the total transmission, Tt, total reflectance, Rt, and the on-axis transmission, Ta, for incident collimated light that propagated through the dermis of albino mouse skin, over the visible spectrum. The diffusion approximation solution to the one-dimensional (1-D) optical transport equation computed the expected Tt and Rt for different combinations of absorbance, k, scattering, s, and anisotropy, g, and by iterative comparison of the measured and computed Tt and Rt values converged to the intrinsic tissue parameters. For example, mouse dermis presented optical parameters of 2.8 cm-1, 239 cm-1, and 0.74 for k, s, and g, respectively, at 488 nm wavelength. These values were used in the model to simulate the optical propagation of the 488-nm line of an argon laser through mouse skin in vivo. A 1-D Green's function thermal diffusion model computed the temperature distribution within the tissue at different times during laser irradiation. In vitro experiments showed that the threshold temperature range for coagulation was 60 degrees-70 degrees C, and the kinetics were first order, with a temperature-dependent rate constant that obeyed an Arrhenius relation (molar entropy 276 cal/mol-degrees K, molar enthalpy 102 kcal/mol). The model simulation agreed with the corresponding in vivo experiment that a 2-s pulse at 55 W/cm2 irradiance will achieve coagulation of the skin.

Surface elasticity and dynamic stability of wet foams

Solutions of n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol and n-decanol were studied. The frothability of the solutions was determined by a pneumatic method, surface elasticity forces were measured using the oscillating bubble technique, and the average lifetimes of gas bubbles in a top foam layer were determined by cinephotography. The frothability of solutions was described in terms of the retention time ( rt) values. The rt values depend strongly on the kind of surface-active substance and on its concentrations. The frothabilities of the various n-alkanols were compared at the same values of their reduced concentrations c 0/ a, where a is the concentration of the half surface coverage. The rt values initially increase with increasing number ( n) of carbon atoms in n-alkanol molecules, reach a maximum for C 6C 8, and then rapidly decrease for n-nonanol and n-decanol. The surface activity of the solute, its adsorption kinetics, the lifetime of the foam films, and the frequency of the external disturbances are the main factors determining the magnitude of the effective elasticity forces ( E eff). Similar to the rt values, the E eff values initially increase with increasing n, reach a maximum for C 6C 8, and then rapidly decrease for higher members of the n-alkanol homologous series. The magnitude and the position of these maxima are a function of the solute concentration, adsorption times, and frequency of external disturbances. The results obtained show that the effective elasticity forces are the major factors determining the stability of wet dynamic foams.

Steady-state foams: Influence of the type of liquid films

Properties of “dry” steady-state foams formed from sodium lauryl sulphate (NaLS) solutions containing various amounts of electrolyte have been investigated. The results of the foamability measurements performed under dynamic steady-state conditions are described in terms of retention time ( rt) values. Upper limits of NaLS concentrations, for which the measurements of steady-state foamability could be performed were found to depend strongly on the amounts of electrolyte added. Investigations of the action of α-particle showed that three types of foam film were formed in the highest layers of the foams studied. Newton black, common black and normal thin liquid films were formed in the presence of 0.5, 0.1 and 10 −4 M NaCl, respectively. The properties of these three types of film determined the observed behaviour of the steady-state foam formed.

Characterization of flow in intravenous infusion systems.

The pressure-flow (P-F) relationship for intravenous infusion systems is found to be nonlinear, and may be expressed by the mathematical model P = RLF + RTF2. The parameters RL and RT both show linear increase with tubing length. Devices have been identified with an isolated effect on RL (5 ?fiter) or on RT (check valve). The total RL and RT of an infusion system may be obtained by adding the RL and RT values of component devices. The sources of the turbulence suggested by the nonlinear P-F relationship are discussed. The coefficients RL and RT may relate to actual laminar and turbulent flow conditions. Knowledge of flow characteristics can be used to evaluate and design intravenous tubing systems, particularly for high-flow intravenous fluid resuscitation in surgery or after trauma.

The Furocoumarin Composition ofPituranthos triradiatus

Five furocoumarins were isolated by HPLC from the petroleum ether extract of shoots of Pituranthos triradiatus (Hochst. ex Boiss.) Aschers. et Schweif. (Umbelliferae). This species is commonly used by Beduins still practicing folk medicine in the Negev and Sinai Deserts. The furocoumarins were found to be: isoimperatorin, 5-(3-methyl-2-butenyloxy)-psoralen; cnidilin, 8-methoxy-5-(3-methyl-2-butenyloxy)-psoralen; imperatorin, 8-(3-methyl-2-butenyloxy)-psoralen; bergapten, 5-methoxypsoralen; and isopimpinellin, 5,8-dimethoxypsoralen. Some chemical and physical characteristics of these compounds, including RT values, were determined.

Voice onset and offset RTs in spastic dysphonia

Recent evidence suggests peripheral and/or central nervous system involvement in the etiology of spastic dysphonia, a communicative disorder characterized by difficulties in voice control, specifically voice initiation, termination, and maintenance. Temporal measures of vocal RTs to auditory stimulus, for voice initiation and termination, were obtained in ten adult male and female patients suspected of having spastic dysphonia. These auditory‐vocal RTs were obtained for voice within and above the voice frequency used in normal speech production, since spastic dysphonic patients often exhibit differences in control of voice within and above the speech frequency range. The temporal measures obtained are used to explore the nature of RT variability as indications of their peripheral or central locus. The derived data are also compared with available RT values for other voice pathologies which presumably affect control and timing of laryngeal behavior (stuttering and dysarthrias). [Work supported by NIH.]

Effects of fatiguing isometric and isotonic exercise on resisted and unresisted reaction time components.

Fractionated resisted and unresisted RT for a knee-extension task was assessed on 12 male subjects over a 10-day treatment period. The first 4 days were baseline days and were designed to stabilize all RT values as well as strength measures. For the next 6 days the subjects were alternately administered isometric and isotonic exercise designed to fatigue the quadriceps musculature. Although significant strength decrements were manifested for both isometric exercise (57%) and isotonic exercise (35%), no changes were shown in the unresisted fractionated RT components. Conversely all resisted RT changes were manifested in the muscular component suggesting a peripheral site for neuromuscular fatigue.

Reaction time to incremental and decremental target luminance changes at various photopic background levels

The experimental data clearly confirm a general luminance-contrast principle established in this laboratory on other visual functions: For contrasts just beyond some critical near-zero value, visual performance is determined by the prevailing retinal illuminance of that component, either target or background, which has the higher illumination level. Thus, for positive contrasts, RT progressively decreases to an asymptotic value as target luminance (the higher component) is increased. However, as negative contrast is increased (i.e. as target luminance is decreased at any background level), RT remains constant at a value which is determined by the prevailing background illumination level (now the higher component); the higher the prevailing background, the lower is the corresponding value of RT. A schematic model which predicts the results of these contrast effects is presented. The data on positive contrast were used to generate typical photopic intensity-discrimination curves, using several selected RT values as response criteria.