Wider Limits Research Articles

A discussion about the limitations of the Eurocode’s high-speed load model for railway bridges

High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations. For the design of these structures, the European norm EN 1991-2 introduces the high-speed load model (HSLM)—a set of point loads intended to include the effects of existing high-speed trains. Yet, the evolution of current trains and the recent development of new load models motivate a discussion regarding the limits of validity of the HSLM. For this study, a large number of randomly generated load models of articulated, conventional, and regular trains are tested and compared with the envelope of HSLM effects. For each type of train, two sets of 100,000 load models are considered: one abiding by the limits of the EN 1991-2 and another considering wider limits. This comparison is achieved using both a bridge-independent metric (train signatures) and dynamic analyses on a case study bridge (the Canelas bridge of the Portuguese Railway Network). For the latter, a methodology to decrease the computational cost of moving loads analysis is introduced. Results show that some theoretical load models constructed within the stipulated limits of the norm can lead to effects not covered by the HSLM. This is especially noted in conventional trains, where there is a relation with larger distances between centres of adjacent vehicle bogies.

АНАЛІЗ КОНТРАСТНОСТІ МЕЗОСТРУКТУР ҐРУНТОВОГО ПОКРИВУ АГРОЛАНДШАФТІВ ПАСМОВОГО ПОБУЖЖЯ

Under the influence of anthropogenic stress, soil cover undergoes significant transformations, which become apparent in its structure changes. The analysis of the mesostructured contrast of the soil agrarian landscape will allow us to duly detect the areas of agrogenic heterogeneity intensification and introduce measures to prevent soil mantle deterioration, which today is a necessary condition for the sustainable use of soils. The object of research is soil mesocombinations of the Pasmove Pobuzhzhia agro landscapes – the region of intensive agricultural use. The study was conducted in an attempt to establish the reasons for the contrast formation of the soil cover mesocombinations, determine the partial coefficients and the integral contrast index, and group the soil combinations according to these indicators. Comparative geographical, field-map metric, and calculation methods were used for the research. A soil map on a scale of 1:10,000 was taken as the cartographic base for the research. The soil cover of Pasmove Pobuzhzhia is formed by automorphic (grey forest, dark grey podzols, sod-carbonate), semi-hydromorphic (meadow), and hydromorphic (swampy, swampy-meadow, peatland) soils. In the structure of the soil landscape under study, the variations, combinations, soil associations, and mosaics are highlighted. The main factors determining the formation of the soil mantle contrast of mesocombinations are the genetic heterogeneity of the soils, the different granulometric composition and the level of denuded soil. The division of soil combinations into groups according to the degree of contrast and the number of factors determining it is proposed. It has been established that the soil variations are characterized by a minimum integral contrast index (45.25-49.6 %). This type of soil combinations contrast is formed almost exclusively due to the development of erosion processes and the formation of denuded to different extent soils (single-factor contrast). The combinations and soil associations contrast is much higher than that of variations. Soil combinations, it is formed under the influence of erosion processes and the genetic heterogeneity of soils. It has been stated that as for the combinations, the partial coefficients of genetic contrast fluctuate within wider limits (7.9¬29.2 %) than the coefficients according to the degree of soil erosion (53.6-66.1 %). For soil associations, contrast is formed due to genetic heterogeneity and granulometric composition. According to the number of factors, it is proposed to consider the contrast of combinations and soil associations as two-factor. Even though mosaics are classified as medium-contrast combinations, the value of the integral contrast index approaches the range of high-contrast combinations. Their contrast is multifactorial, i.e. caused by all the listed factors. Regarding the findings of the study, it has been stated that water erosion processes are the main factor in the soil cover contrast formation in the agro-landscapes of Pasmove Pobuzhzhia. The temporal dynamics analysis of the soil cover contrast indicators will allow us not only to identify the areas of the most important implementation of soil protection measures but also to evaluate their effectiveness.

Automated Clinical Chemistry Platform Performance Across Two Academic Medical Centers

Abstract Our objective was to define the performance of automated chemistry platforms at two large academic medical centers by calculating and comparing sigma metrics for 28 analytes. Performance characteristics of chemistry assays on two Roche Cobas analyzers and four Abbott Architect analyzers were estimated using 12 months of Bio-Rad quality control (QC) data at two concentrations. Method imprecision was calculated as the cumulative QC coefficient of variation (CV) across analyzers at each QC concentration and percent bias was calculated by comparison of analyzer QC mean to peer group means. Sigma values were calculated for each method as [(TEa – Bias%)/CV%] using allowable total error (TEa) from two sources: the CLIA evaluation limits and desirable biological variation. Average sigma values were generated for each site and graded as optimal, >6 sigma; good, 5 to 6 sigma; marginal, 3 to 5 sigma; or poor, <3 sigma. Analysis of NIST SRM1950 standards for a subset of analytes allowed an estimation of absolute bias. Sigma metrics were highly comparable across both study sites. Considering CLIA TEa, just over half (Roche 57%; Abbott 54%) of the 28 analytes met the six-sigma standard of performance. The highest performing groups to meet or exceed the six-sigma standard were lipids (cholesterol, LDL, HDL, and triglycerides) and enzymes (ALP, ALT, AST, CK, GGT, LDH, and lipase). Electrolytes (Na, K, Cl, Mg) and metabolites (total bilirubin, BUN, CO2) failed to meet six-sigma. Notably, there were dramatic differences in sigma values calculated using CLIA and Ricos TEa criteria. Almost 40% of the analytes had at least one QC that performed poorly using Ricos criteria. Only 4 of the 28 assays (CK, GGT, lipase, and triglycerides) demonstrated optimal performance at both study sites using Ricos and CLIA criteria. Overall, 11 analytes at each institution exhibited unacceptable performance using Ricos criteria as opposed to only two analytes with the CLIA TEa limits. Analysis of NIST SRM1950 at both study sites gave comparable sigmas for all analytes except total bilirubin, cholesterol, Mg, and total protein. Neither Abbott nor Roche analyzers met six-sigma quality standards for all analytes tested. Overall assay performance across these two platforms at two major academic medical centers was almost identical. CLIA TEa and RICOS TEa criteria are significantly different, with wider limits of acceptability for CLIA. Variations between individual analyzers and manufacturers and limitations in automation would make tailored QC rules based on sigma metrics difficult to implement in a high-volume laboratory.

VARIATION OF CHEMICAL COMPOSITION OF MEDICINAL HERBS OF DIFFERENT PRODUCERS

The paper goal was to measure the content of bioactive substances, such as hypericins, some flavonoids and hydroxycinnamic acids, and concentrations of chemical elements, including essential macro- (K, Mg and Na), microelements (Zn, Mn, Cu, Fe, Cr, Ni and Co), as well as toxic metals (Pb and Cd), in samples of St. John's wort herbs of four different producers. High-performance liquid chromatography and atomic absorption spectroscopy were used; sample preparation was based on the procedures described in the State Pharmacopoeia of Ukraine. Significant variation in the content of organic compounds was detected: The difference between the maximum and minimum concentrations reaches a factor of 5 for hypericins, 10 for rutin and 2 for hyperoside. The concentration of quercetin was more stable than those of other flavonoids, and its fluctuations did not exceed 30%. The measured concentrations of hypericin and hyperoside, which are regulated by the Pharmacopoeia, were found to be lower than the norms. Elemental composition is also characterised by variability. Changes in the concentration of essential macroelements (K, Mg and Na) and some of the microelements (Zn, Cu and Ni) do not exceed 30-40%. The concentration of other essential microelements (Fe, Mn, Co and Cr) varies in much wider limits - from a factor of 2 (Mn) to 6 (Fe). In most cases, the measured concentrations of Pb and Cd fluctuate in the ranges of 0.15-0.25 μg/g and 0.25-0.35 μg/, respectively. However, some samples are enriched to 0.7-0.75 μg/g with both toxic metals. The measured concentrations are lower than the WHO norm for Pb (10 μg/g) in all samples and exceed the norm for Cd (0.3 μg/g) in three out of four studied samples. Statistically significant positive or negative correlations were found between the concentrations of certain elements (K, Mg, Fe, Mn and Cd) and the content of organic substances (rutin, hyperoside, hypericin and rosemary and chlorogenic acids). From a practical viewpoint, the most important are positive correlations of Fe with rutin, as well as negative correlations between Mn and hyperosid, and Cd and chlorogenic acid. Existing requirements and norms for medicinal plants in Ukraine do not guarantee the stability of the chemical composition of plants that are sold in the pharmacy network and, accordingly, the stability of their therapeutic properties.

PO-268 Heart rate variability to assess ventilatory threshold in overweight young men

Objective The individualized training intensity is important in the prevention of overweight and obesity. Our study compared heart rate (HR), oxygen uptake (VO2), and work load (WL) corresponded to the anaerobic threshold during an incremental cycling test between ventilatory (VT) and heart rate variability threshold (HRVT) methods. Further, we examined the validity of three heart rate variability analyses to assess VT in overweight young men.
 Methods Sixteen overweight young men (age 21.1±1.7 years, height 175.3±5.5 cm, weight 84.0±6.7kg, body mass index 27.3±1.2 kg/m2, VO2peak33.6±4.3ml/min/kg ) performed a gradual exercise test on a cycle ergometer (Lode Corival，Lode B.V.，Groningen，Newtherlands).The protocol started at 30 W for 2 minutes with subsequent increments of 30 W every 2 minutes until exhaustion. During test, gas exchanges (VO2, VCO2) and ventilation (VE) were measured by breath-by-breath using Metamax 3B portable analyzer (CORTEX, Biophysik GmbH，Leipzig，Germany). The ventilatory threshold (VT) was identified as the point at which VE for O2 began to rise without a concomitant rise in ventilator equivalent for CO2. The R-R intervals were continuously recorded using a Polar RS800cx HR monitor(Kempele, Finland). HRV data were further analyzed by Kubios HRV analysis software (Kuopio, Finland) based on time-domain (RMSSD) , Poincare plots(SD1) and time-varying spectral (fHF×HFP) methods. Data were analyzed using SPSS 22.0. Normal distribution of variables was verified by Kolmogorov-Smirnov test. The relationship between HRVT variables and VT was assessed using paired t-test and Pearson’s production correlation. The magnitude of concordance between the methods was further evaluated by Bland-Altman plots.
 Results No significant difference was witnessed in HR, VO2, and WL related to AT between HRVT and VT methods（P<0.05）. The relationships were found between the methods to determine the AT for all variables analyzed (r=0.40-0.91). Additionally, the Bland-Altman plots revealed that findings showing narrow limits of agreement present for fHF×HFP and the VT whilst the association between RMSSD, SD1 and VT showed wider limits.
 Conclusions The estimation of the HRVT, especially derived through the time-varying spectral (fHF×HFP), may be a noninvasive and more robust method to determine the VT, which could be used to adapt individualized training intensity to overweight young men for training prescription.

Changes in the Chemical Composition of Blood

The chemical composition of blood varies within rather narrow limit values. Relative constancy is more marked when certain components are concerned and less manifest when others are involved. Thus, mineral components allow narrower quantitative variation limits than organic substances concentration, more precisely than extractive substances, which may vary between wider limits. The variations of the formed elements/plasma ratio, which are common in pathological states, hinder the study of the chemical composition of blood, due to the fact that these oscillations are reflected in the overall chemical composition of blood. In most cases, chemical research needs to be conducted on blood serum and plasma, as they are more constant in their composition.

Combustion Characteristics of Hydrogen by the Thermodynamic Properties Analysis

Hydrogen has some remarkably high values of the key properties for transport processes, such as kinematic viscosity, thermal conductivity and diffusion coefficient. Hydrogen, as an energy medium, has some distinct benefits for its high efficiency and convenience in storage, transportation and conversion. Hydrogen has much wider limits of flammability in air than methane, propane or gasoline and the minimum ignition energy is about an order of magnitude lower than for other combustibles. Statistical thermodynamics provides the relationships that we need in order to bridge this gap between the macro and the micro. Our most important application will involve the calculation of the thermodynamic properties of the ideal gas.

Comparison of rumination activity measured using rumination collars against direct visual observations and analysis of video recordings of dairy cows in commercial farm environments

Automated systems for monitoring the behavior of cows have become increasingly important for management routines and for monitoring health and welfare. In the past few decades, various devices that record rumination have been developed. The aim of the present study was to compare rumination activity measured with a commercially available rumination collar (RC) against that obtained by direct visual observations and analysis of video recordings in commercial dairy cows. Rumination time from video recordings was recorded by a trained observer. To assess observer reliability, data were recorded twice, and the duration of recorded behaviors was very similar and highly correlated between these 2 measurements (mean=39±4 and 38±4min/2h). Measurements of rumination time obtained with RC when compared with analysis of video recordings and direct observations were variable: RC output was significantly positively related to observed rumination activity when dealing with animals housed indoors (trial 1 video recordings: slope=1.02, 95% CI=0.92–1.12), and the limits of agreement method (LoA) showed differences (in min per 2-h block) to be within −26.92 lower and 24.27 upper limits. Trial 1 direct observations: slope=1.08, 95% CI=0.62–1.55, and the LoA showed differences to be within −28.54 lower and 21.98 upper limits. Trial 2: slope=0.93, 95% CI=0.64–1.23, and the LoA showed differences to be within −32.56 lower and 19.84 upper limits. However, the results were poor when cows were outside grazing grass (trial 3: slope=0.57, 95% CI=0.13–1.02, and the LoA showed differences to be within wider limits −51.16 lower and 53.02 upper). Our results suggest that RC can determine rumination activity and are an alternative to visual observations when animals are housed indoors. However, they are not an alternative to direct observations with grazing animals on pasture and its use is not advisable until further research and validation are carried out.

Cardiac MRI Volumetric Assessment by Short-Axis has Better Reproducibility than the Axial Orientation in Functionally Single Right Ventricle Hearts Prior to Bidirectional Cavopulmonary Anastomosis

Cardiac MRI Volumetric Assessment by Short-Axis has Better Reproducibility than the Axial Orientation in Functionally Single Right Ventricle Hearts Prior to Bidirectional Cavopulmonary Anastomosis Background: Cardiovascular Magnetic resonance imaging (CMR) is the standard for assessment of ventricular volumes and function. However, few reports exist regarding methodology for measurements of functionally single right ventricular (RV) volumes in congenital heart disease. This study aims to determine which imaging plane, the short axis oblique (SAO) or the axial orientation (AX), provides greater reproducibility in evaluation of RV volumes and function in patients with hypoplastic left heart syndrome (HLHS) prior to bidirectional cavopulmonary anastomosis (BCPA). Methods: CMR was performed under general anesthesia in 23 patients (5 ± 3.4 months) with single RV prior to BCPA to obtain ventricular volumes from the axial and/or short-axis cine orientations. Postprocessing (cmr42 - Circle Imaging, Calgary, Alberta) was performed by two independent observers to obtain end-diastolic (EDV), end-systolic (ESV) volumes and ejection fraction (EF) in both SAO (n=23) and AX (n=16) planes. Absolute differences (mean ± SD), repeatability values, intraclass correlation coefficients (ICC), coefficient of variation, and Bland Altman plots were used to assess the reproducibility between methods, and interobserver and intraobserver variability. Results: Comparisons of SAO versus AX volumes revealed small absolute differences, with better repeatability for ESV (4.6 ml) compared to EDV (8.5 ml), and high agreement between the 2 methods. Interobserver variability showed high correlations and narrow limits of agreements for SAO and AX measured ESV. However, AX EDV had poorer repeatability (11 ml) and wider limits of agreement than SAO EDV (6.4 ml). Intraobserver testing showed higher correlations for all measurements, but SAO EDV (2.7 ml) showed better repeatability than AX EDV (5.7 ml). Conclusion: CMR assessment of single RV volumes showed better inter and intra-observer reproducibility for the SAO than the AX methods suggesting that the addition of an axial stack does not provide any benefit over the short axis orientation in the assessment of single RV volumes and function.

R2P and Humanitarian Action

The responsibility to protect was not the only concept that grew out of the world’s failure to tackle the mass atrocities of the 1990s in Rwanda, Bosnia and elsewhere. So too did a new approach to humanitarian action which placed a higher priority on protecting civilians, and on advocacy to do so, than had hitherto been common. Oxfam’s role in the campaign to persuade the 2005 World Summit to adopt the responsibility to protect was one prominent example, but, to different degrees, this broad approach has become widely shared among many international humanitarian agencies. Since 2005, however, even Oxfam has made little use of the responsibility to protect to frame its own work to help protect civilians, or to advocate to prevent mass atrocities in specific crises. This is partly because of the fear that R2P can be misapplied to justify military intervention where the benefits do not clearly outweigh the risks. But it is also because of the continuing suspicion around R2P among many governments. This seems to reflect the wider limits of what largely Western-based humanitarian agencies and governments can do to develop new international norms and put them into effect. When R2P was first developed, humanitarian agencies played a part in broadly similar alliances to ban landmines, establish the icc and so on. Some of these have already had a substantial effect, while it may be a generation before the value of R2P and others can be fairly evaluated. Looking ahead, humanitarian agencies will have to put an increasing emphasis on influencing emerging powers and other Southern governments, while alliances between governments and ngos, to be effective, will have to be genuinely global.

Analysis of variations of basic morphometric characters in the species of grenadier (Macrouridae, Gadiformes) from the waters of the northern part of the Mid-Atlantic ridge

We investigate variations of the basic morphometric characters (length of head, length of snout, diameter of orbit, interorbital distance, etc.) of ten of the most common species of grenadiers (Macrouridae) in the waters of the northern part of the Mid-Atlantic ridge: Coelorinchus labiatus, Coryphaenoides armatus, C. brevibarbis, C. carapinus, C. guentheri, C. leptolepis, C. mediterraneus, C. rupestris, Macrourus berglax, and Paracetonurus flagellicauda. It is shown that most morphometric characters of the investigated species vary within the wider limits as compared with the published data. The representatives of genera Coelorinchus, Macrourus, and Paracetonurus well differ by a number of characters from the species of genus Coryphaenoides and from each other. In spite of a significant likeness in many characters of the species of genus Coryphaenoides, there are individual characters that differ well from one species to another.

Defining the Topography of Deletion 5q Using SNP-A Identifies Patients with More Aggressive Disease and Correlates with Additional Lesions

Abstract 2795Interstitial deletions of chromosome 5q are common in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), pointing towards the pathogenic role of this region in disease phenotype and clonal evolution. The higher level of resolution of single nucleotide polymorphism array (SNP-A) karyotyping may be used to find cryptic abnormalities, and to precisely define the topographic features of the genomic lesions allowing for more accurate clinical correlations. In order to better address the genetic and genomic complexity of 5q abnormalities in myeloid malignances, we analyzed a large series of 1,155 clinically well-annotated patients with malignant myeloid disorders with SNP-A-based karyotyping to define: i) the extent of the 5q deletion, investigating whether loss of genes is different among 5q disorders; ii) minimally deleted region(s); iii) associated non-5q genomic lesions with 5q abnormalities; and iv) the association of genomic abnormalities with clinical features. We identified chromosome 5q deletions in 142/1155 patients (12%) and uniparental disomy segments (UPD) in 4/1155 patients (0.35%).With increased resolution there was a shift towards more complex karyotypes and increased identification of additional lesions among the patients with 5q aberrations. By SNP-A, previously cryptic lesions were identified in 52% of the patients who otherwise showed a singular del(5q) lesion by metaphase cytogenetics (MC). The presence of chromosome 5q material in all our cases with apparent monosomy 5 (N=11) by conventional MC serves as an illustration for SNP array-based mapping allowing for a more precise definition of the breakpoints; in addition, 48% of MC results localized both the beginning and end of the deletion to a different band than SNP-A, and in only 9% of cases, MC and SNP-A boundaries coincided. The CDR defined in our 5q-syndrome, though with wider limits (145,279,940–153,809,148), encompasses the CDR described by Boultwood et al; the CDR in advanced del(5q) MDS and AML patients is centered on a sub-section of bands 5q31.2 and 5q31.3 (137,528,564–139,451,907) and includes the defect initially mapped by Le Beau et al. Patients with MDS and deletions involving the centromeric and telomeric extremes of 5q have a more aggressive disease phenotype (median overall survival: 32 months, p=0.04, HR 1.9; median number of chromosome lesions: 5.8 vs. 1.1, p<0.001:; median time to progression: 30 months vs not reached, p<0.001). Moreover, lesions not involving the centromeric or telomeric extremes of 5q are not exclusive to 5q- syndrome but can be associated with other less aggressive forms of MDS. In addition, larger 5q deletions are associated with either del(17p) or UPD17p (25% vs 11% of cases, respectively). We closely investigated the outlying cases of aggressive disease and shorter interstitial deletions. We chose to test for 6 possible tumor suppressor genes, located within the extremes of 5q and related to the TP53 pathway that, if defective, might explain a clonal advantage. In our AML cohort only 5 patients showed a deletion not involving the 5q extremes: 4/5 of them displayed either NPM1 and/or MAML1 heterozygous mutations. In summary, the present study of 5q disorders shows that SNP-A can complement traditional MC, not only by finding cryptic abnormalities, but also by precisely defining the extent of the lesions. Moreover, we have perfomed whole exon sequencing but to date the analysis did not identify genes mutated on 5q rather the ones described above. Our results strongly suggest that while genes widely deleted among 5q disorders may be responsible for the characteristics of the dysplastic clone, the loss of an additional gene or genes in the proximal and telomeric extremes of 5q may be responsible of increasing genomic instability, favoring AML transformation. Disclosures:No relevant conflicts of interest to declare.

Accuracy and Reproducibility of Strain by Speckle Tracking in Pediatric Subjects with Normal Heart and Single Ventricular Physiology: A Two-Dimensional Speckle-Tracking Echocardiography and Magnetic Resonance Imaging Correlative Study

Myocardial strain is a sensitive measure of ventricular systolic function. Two-dimensional speckle-tracking echocardiography (2DSE) is an angle-independent method for strain measurement but has not been validated in pediatric subjects. The aim of this study was to evaluate the accuracy and reproducibility of 2DSE-measured strain against reference tagged magnetic resonance imaging-measured strain in pediatric subjects with normal hearts and those with single ventricles (SVs) of left ventricular morphology after the Fontan procedure. Peak systolic circumferential strain and longitudinal strain (LS) in segments (n = 16) of left ventricles in age-matched and body surface area-matched 20 healthy and 12 pediatric subjects with tricuspid atresia after the Fontan procedure were measured by 2DSE and tagged magnetic resonance imaging. Average (global) and regional segmental strains measured by the two methods were compared using Spearman's and Bland-Altman analyses. Global strains measured by 2DSE and tagged magnetic resonance imaging demonstrated close agreements, which were better for LS than circumferential strain and in normal left ventricles than in SVs (95% limits of agreement, +0.0% to +3.12%, -2.48% to +1.08%, -4.6% to +1.8%, and -3.6% to +1.8%, respectively). There was variability in agreement between regional strains, with wider limits in apical than in basal regions in normal left ventricles and heterogeneity in SVs. Strain values were significantly (P < .05) higher in normal left ventricles than in SVs except for basal LS, which were similar in both cohorts. The regional strains in normal left ventricles demonstrated an apicobasal magnitude gradient, whereas SVs showed heterogeneity. Reproducibility was the most robust for images obtained with frame rates between 60 and 90 frames/sec, global LS in both cohorts, and basal strains in normal left ventricles. Strains measured by 2DSE agree with strain measured by magnetic resonance imaging globally but vary regionally, particularly in SVs. Global strain may be a more robust tool for cardiac functional evaluation than regional strain in SV physiology. The reliability of 2DSE-measured strain is affected by the frame rate, the nature of strain, and ventricular geometry.

Six Sigma® can be dangerous to your health

Six Sigma® is a popular quality program that has been applied to clinical laboratory assays. Sigma is calculated as (TEa − bias)/CV and these sigma numbers are often claimed as a sole measure of quality based on medical requirements. But these sigma calculations do not account for all results. An additional set of wider limits must be added, such that all data are accounted for. This gives a minimum of three zones: zone A, where 95% of the data should be; zone C, where there should be no data; and zone B, where 5% of the data is allowed. An additional problem is that sigma calculations are often based on valid analytical data, meaning that pre-analytical and post-analytical errors are excluded. Also, samples that are flagged by the system and produce no results are, of course, excluded, but delayed results can cause patient harm. A better measure of assay quality can be provided by a failure mode effects analysis (FMEA), which attempts to assess the probability of failure and its severity for every possible failure mode. In this paper, an example of what is entailed is described for two failure modes and the overall process is outlined. The amount of effort required for a full FMEA is beyond virtually any clinical laboratory. Some compromises are suggested. Calculating sigma values, which have little meaning about patient harm, is not recommended.

Spatial coherence of transient stimulated Raman scattering

The Stokes wave evolution at transient stimulated Raman Scattering (SRS) in compressed hydrogen was simulated taking into account diffraction effects. A corresponding numerical model was developed to study different amplitude-phase SRS characteristics, such as space–time and phase dependencies, spectrum and spatial coherence function of pump and Stokes waves. Simulation results showed significant differences in these characteristics between transient and quasi-stationary cases. The strong oscillatory process of energy exchange between pump and Stokes waves in the transient case results in complicated intensity and phase space–time dependencies. However, under quasi-stationary conditions the Stokes wave phase varies in wider limits, which leads to spatial coherency lowering. The module value of the spatial coherency function lowers to a threshold and then becomes stable as the conversion coefficient increases for both the transient and quasi-stationary cases. Stokes beam focusing is shown for SRS, which arises from competition between diffraction and non-uniform in a cross-section strong Raman amplification. Results of simulations are in good agreement with experimental data.

Influence of the Evaporation Coefficient and Temperature Jumps on the Thermophoresis of a Moderately Large Volatile High-Viscosity Sphere in a Binary Gas Mixture with Allowance for Volume Thermodiffusion and Stefan Effects

The theory of a uniform thermophoretic motion of a volatile high‐viscosity sphere with the phase transition of one component of a moderately rarefied binary gas mixture on its surface has been constructed on the basis of the hydrodynamic method in the regime with slip. The relative influence of the evaporation coefficient and the boundary temperature jumps on the distributions of the velocities, temperatures, and concentrations of the volatile component and the thermophoresis rate has been analyzed. Allowance has been made for the thermodiffusion terms, Stefan effects, and the heat due to the convective transfer of the substance of the condensed phase. The formula obtained has wider limits of application than the existing results. The conclusions of the traditional theories are successfully generalized to the cases of weak and moderately strong processes of diffusion evaporation of a single high‐viscosity droplet that moves in a nonuniformly heated binary mixture of gases.

Synthesis and characterization of neutral newly substituted polyalkylthiophenes

In this work, two newly substituted polyalkylthiophenes, poly(3,4-dihexyl-2,2′-bithiophene) and its didodecyl analogue have been prepared in order to compare their properties with those of the regioisomeric poly(3-alkylthiophene)s containing the same amount of head-to-tail configuration (conventional PATs). Remarkable differences between the material characteristics of these two kinds of polyalkylthiophene have been observed, thus enabling us to elucidate the side chains effects exclusively attributable to the difference between the side chains distribution along the polythiophene backbone. In the neutral bulk state, compared to that of the conventional PATs, the polymers prepared for this study have been found more thermostable materials exhibiting higher flexibility and less ordered (in the crystallographic sense) molecular assemblies, still able to afford an average conjugation length as long as that of the conventional PATs, but varying between wider limits. This seems to be closely connected with a lower degree of side chains interactions and/or the high proportion (50%) of unsubstituted thiophene rings. Based on these effects of molecular structure on the material properties at room temperature, we have anticipated in the novel polymers, at higher temperatures, the possibility of weaker thermochromism and better conductivity stability than in their regioisomeric conventional PATs.

Resistance of Oligochaetes of the Family Tubificidae to Organophosphorus Pesticides

Nine species of oligochaetes of the family Tubificidae were exposed to solution of organophosphorus pesticides during 48 hours. Thresholds of toxic effects of phosdrin, paraoxon, phosalon, and dichlorovos differ in the species studied, but range within 0.1−1.0 mg/L in general. Alongside with this, there exist also interspecies distinctions in resistance to pesticides as well as in an intensity of biocidal affect; specific sensitivities (ascertained by LC50) range in wider limits, from 0.5 to 120 mg/L. Potamotrix species are less resistant to pesticides used in the experiment than Aulodrilus pluriseta, Tubifex tubifex and species of the genus Limnodrilus. The sensitivity of oligochaetes is compared with that reported in literature on some other worms .

Dissolution specifications based on release rates

A procedure based on release rates is proposed for the establishment of dissolution specifications that ensure the bioequiva-lence of a test and a reference product. This procedure, which confines Cmax (the maximum concentration of the drug in vivo) and AUC∞(the area under the time–concentration curve, extrapolated to infinity) values within any desired range (relative to a reference product), can be used as an alternative to the methods presented in the FDA guidance1 or the USP2. The method is appropriate for zero-order or first-order release products with linear Level A in vitro/in vivo correlations (IVIVC). Based on the result that the relative difference in Cmax must always be smaller than the relative difference in the absorption rate constants (for any test and reference products of a given drug), the “minimum range” specifications are set. These specifications, which are identical for both zero-order and first-order release products, are of general validity. They depend only on the relative extents of release, but are otherwise drug or formulation independent. For certain extended release products demonstrating a constant release rate that is unaffected by dissolution conditions (thus allowing the assumption of Level A IVIVC), the “minimum range” dissolution limits are applicable even when in vivo data is not available. If the reference product in vivo data is available, wider limits (which are product specific) may be set. If the drug disposition is monoexponential, the specifications generated are the widest possible. They are termed the “ideal” specifications. In the case of a multiexponential disposition, the limits set by the procedure will (generally) not be the widest possible. Although the method is based on one-compartment models, it is essentially model independent in the sense that microscopic modeling is redundant for its application.

Ways to improve the analysis of multi-level accelerated life testing

Multi-level accelerated life tests (ALTs), MEOST (multiple extreme overstress testing) and traditional step-stress approaches (hereafter all called simply step-stress) have a number of worthwhile applications for the analysis of the projected reliability of components and systems. These test methods are considered for many common situations of accelerated life testing (ALT). Some of the main purposes of ALT are to measure projected system life and to identify product weaknesses in order to improve reliability. These methods may apply well when only a small number of systems are available, when extremely long, specialized test equipment is required, when limited environmental chamber capability and/or test fixtures are involved and, lastly, when very expensive support equipment represents a serious test limit. The accelerated testing methods mentioned have had some limited applications in the past. The limits have been sometimes due to poorly described degradation or accumulative fatigue and the subsequent difficulty with the analysis of the failure data themselves. A tight series of ground rules is proposed in this paper that may help solve, mitigate or prevent this possibility. This paper also presents methods to improve the analysis of these multi-level stress tests. While the methods shown are approximate, they easily lend themselves to analysis on a computer by standard software packages or through manual techniques. Additionally, the ground rules presented suggest that wider limits may often be taken for running this type of accelerated testing than has been suggested in the past. These ground rules aid the analysis by ensuring uniformity of results. As an aid to test set-up, neither the step intervals need be of the same length nor the stress steps uniform. A recent paper by van Dorp et al. (IEEE Trans. Reliab., REL-45, 491–497 (1996)) provides a theoretical basis for some of these suggestions. Another paper by Bhote (Trans. Am. Soc. Met., 237–243 (1985)) identifies many reasons to perform this type of reliability test and credits Dorian Shainin with the development of many of the early MEOST techniques. Clearly, step-stress approaches and applications have not been exhausted for measuring life and identifying design or manufacturing flaws. Copyright © 1998 John Wiley & Sons, Ltd.