Advanced Load Effect Model for Probabilistic Structural Design

In probabilistic structural design some actions on structures can be well described by renewal processes with intermittencies. The expected number of renewals for a given time interval and the probability of “on“-state at an arbitrary point in time are of a main interest when estimating the structural reliability level related to the observed period. It appears that the expected number of renewals follows the Poisson distribution. The initial probability of “on”-state is derived assuming random initial conditions. Based on a two-state Markov process, the probability of “on”-state at an arbitrary point in time then proves to be a time-invariant quantity under random initial conditions. The results are numerically verified by Monte Carlo simulations. It is anticipated that the proposed load effect model will become a useful tool in probabilistic structural design. The aims of future research are outlined in the conclusions of the paper.

Reliability Analysis of a Steel Frame

A steel frame with haunches is designed according to Eurocodes. The frame is exposed to self-weight, snow, and wind actions. Lateral-torsional buckling appears to represent the most critical criterion, which is considered as a basis for the limit state function. In the reliability analysis, the probabilistic models proposed by the Joint Committee for Structural Safety (JCSS) are used for basic variables. The uncertainty model coefficients take into account the inaccuracy of the resistance model for the haunched girder and the inaccuracy of the action effect model. The time invariant reliability analysis is based on Turkstra's rule for combinations of snow and wind actions. The time variant analysis describes snow and wind actions by jump processes with intermittencies. Assuming a 50-year lifetime, the obtained values of the reliability index b vary within the range from 3.95 up to 5.56. The cross-profile IPE 330 designed according to Eurocodes seems to be adequate. It appears that the time invariant reliability analysis based on Turkstra's rule provides considerably lower values of b than those obtained by the time variant analysis

Target reliability levels in Eurocodes and ISO standards

TARGET RELIABILITY LEVELS IN EUROCODES AND ISO STANDARDS. M. HOLICKÝ, J. MARKOVÁ, M. SÝKORA (Czech Technical University, Prague, Klokner Institute)The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is vague only. In some documents the target reliability index is indicated for one or two reference periods (1 year, 50 years or life-time) without providing appropriate links to the design working life. This contribution attempts to clarify the relationship between the target reliability levels, costs of safety measures, failure consequences, reference periods and the design working life. For ultimate limit states of common buildings and bridges (RC2), it is recommended to consider reliability index of 3.8 for a reference period equal to the design working life (50 years for buildings, 100 for bridges).= Рассматриваются условные уровни надежности, рекомендованные в национальных и международных документах. Показано, что эти уровни варьируются в широком диапазоне, в то время как ссылки на соответствующие затраты и последовательность отказов недостаточно изучена. В некоторых документах индекс целевой надежности определяется для одного или двух базовых периодов (1 год, 50 лет или в течение всего жизненного цикла) без предоставления соответствующих ссылок на проекты. В данной работе делается попытка прояснить отношения между уровнями целевой надежности, затратами на обеспечение безопасности, последовательностью отказов, базовыми периодами и сроком эксплуатации. Для предельных уровней состояния общественных зданий и мостов (RC2) рекомендовано использовать целевой индекс 3.8 для периода, равного проектному сроку службы: 50 лет – для зданий,100 лет – для мостов

Optimal embedding of a toroidal mesh in a path

We prove that the dilation of an $m \times n$ toroidal mesh in an $mn$-vertex path equals $2\min\{m,n\}$, if $m\not= n$ and $2n-1$, if $m=n$

Double-blind, placebo-controlled evaluation of grass pollen specific immunotherapy with oral drops administered sublingually or supralingually

SummaryForty-one patients suffering from grass pollen allergy underwent specific immunotherapy with standardized allergen extract consisting of six grass pollens (H-Al per os) administered either sublingually or supralingually for one year. In order to investigate clinical and immunological changes induced by the administration of allergens via the oral mucosa, the double-blind, placebo-controlled, randomized design of the trial with 30 other patients enrolled in placebo groups was applied.Specific immunotherapy with oral drops administered sublingually or supralingually was performed in the same way, keeping the drops under or on the tongue, respectively, for 1–2min before swallowing them; at the end of the trial the cumulative dose of the allergen was almost 20 times higher than that of the subcutaneous therapy with corresponding allergen preparation. Data about symptoms scores and drugs intake during grass pollen season, as well as skin reactivity, levels of specific IgG and IgE antibodies, before the study and after the study's completion, were obtained.It was found that both routes of administration are effective according to subjective clinical parameters and drug consumption, with a highly significant reduction of symptoms and drug intake favoring sublingual administration where a reduction of more than 60% was achieved. Only sublingual active group showed a significant increase in Dactylis glomerata-specific IgG serum levels. Adverse effects were limited to a small number of generally mild local and/or systemic reactions.The results suggest that the administration of allergens via the oral mucosa is safe and clinically effective, favoring the sublingual rather than supralingual route

Target reliability levels in Eurocodes and ISO standards

TARGET RELIABILITY LEVELS IN EUROCODES AND ISO STANDARDS. M. HOLICKÝ, J. MARKOVÁ, M. SÝKORA (Czech Technical University, Prague, Klokner Institute)The target reliability levels recommended in national and international documents vary within a broad range, while the reference to relevant costs and failure consequences is vague only. In some documents the target reliability index is indicated for one or two reference periods (1 year, 50 years or life-time) without providing appropriate links to the design working life. This contribution attempts to clarify the relationship between the target reliability levels, costs of safety measures, failure consequences, reference periods and the design working life. For ultimate limit states of common buildings and bridges (RC2), it is recommended to consider reliability index of 3.8 for a reference period equal to the design working life (50 years for buildings, 100 for bridges).= Рассматриваются условные уровни надежности, рекомендованные в национальных и международных документах. Показано, что эти уровни варьируются в широком диапазоне, в то время как ссылки на соответствующие затраты и последовательность отказов недостаточно изучена. В некоторых документах индекс целевой надежности определяется для одного или двух базовых периодов (1 год, 50 лет или в течение всего жизненного цикла) без предоставления соответствующих ссылок на проекты. В данной работе делается попытка прояснить отношения между уровнями целевой надежности, затратами на обеспечение безопасности, последовательностью отказов, базовыми периодами и сроком эксплуатации. Для предельных уровней состояния общественных зданий и мостов (RC2) рекомендовано использовать целевой индекс 3.8 для периода, равного проектному сроку службы: 50 лет – для зданий,100 лет – для мостов

Light-Induced Nanosecond Relaxation Dynamics of Rhenium-Labeled Pseudomonas aeruginosa Azurins.

Time-resolved phosphorescence spectra of Re(CO)3(dmp)+ and Re(CO)3(phen)+ chromophores (dmp = 4,7-dimethyl-1,10-phenanthroline, phen = 1,10-phenanthroline) bound to surface histidines (H83, H124, and H126) of Pseudomonas aeruginosa azurin mutants exhibit dynamic band maxima shifts to lower wavenumbers following 3-exponential kinetics with 1-5 and 20-100 ns major phases and a 1.1-2.5 μs minor (5-16%) phase. Observation of slow relaxation components was made possible by using an organometallic Re chromophore as a probe whose long phosphorescence lifetime extends the observation window up to ∼3 μs. Integrated emission-band areas also decay with 2- or 3-exponential kinetics; the faster decay phase(s) is relaxation-related, whereas the slowest one [360-680 ns (dmp); 90-140 ns (phen)] arises mainly from population decay. As a result of shifting bands, the emission intensity decay kinetics depend on the detection wavelength. Detailed kinetics analyses and comparisons with band-shift dynamics are needed to disentangle relaxation and population decay kinetics if they occur on comparable timescales. The dynamic phosphorescence Stokes shift in Re-azurins is caused by relaxation motions of the solvent, the protein, and solvated amino acid side chains at the Re binding site in response to chromophore electronic excitation. Comparing relaxation and decay kinetics of Re(dmp)124K122Cu II and Re(dmp)124W122Cu II suggests that electron transfer (ET) and relaxation motions in the W122 mutant are coupled. It follows that nanosecond and faster photo-induced ET steps in azurins (and likely other redox proteins) occur from unrelaxed systems; importantly, these reactions can be driven (or hindered) by structural and solvational dynamics

The African Swine Fever Virus Transcriptome

African swine fever virus (ASFV) causes hemorrhagic fever in domestic pigs, presenting the biggest global threat to animal farming in recorded history. Despite the importance of ASFV, little is known about the mechanisms and regulation of ASFV transcription. Using RNA sequencing methods, we have determined total RNA abundance, transcription start sites, and transcription termination sites at single-nucleotide resolution. This allowed us to characterize DNA consensus motifs of early and late ASFV core promoters, as well as a polythymidylate sequence determinant for transcription termination. Our results demonstrate that ASFV utilizes alternative transcription start sites between early and late stages of infection and that ASFV RNA polymerase (RNAP) undergoes promoter-proximal transcript slippage at 5= ends of transcription units, adding quasitemplated AU- and AUAU-5= extensions to mRNAs. Here, we present the first much-needed genome-wide transcriptome study that provides unique insight into ASFV transcription and serves as a resource to aid future functional analyses of ASFV genes which are essential to combat this devastating disease

Analysis of coupled heat and moisture transfer in masonry structures

Evaluation of effective or macroscopic coefficients of thermal conductivity under coupled heat and moisture transfer is presented. The paper first gives a detailed summary on the solution of a simple steady state heat conduction problem with an emphasis on various types of boundary conditions applied to the representative volume element -- a periodic unit cell. Since the results essentially suggest no superiority of any type of boundary conditions, the paper proceeds with the coupled nonlinear heat and moisture problem subjecting the selected representative volume element to the prescribed macroscopically uniform heat flux. This allows for a direct use of the academic or commercially available codes. Here, the presented results are derived with the help of the SIFEL (SIimple Finite Elements) system.Comment: 23 pages, 11 figure

Large-scale horizontal flows in the solar photosphere I: Method and tests on synthetic data

We propose a useful method for mapping large-scale velocity fields in the solar photosphere. It is based on the local correlation tracking algorithm when tracing supergranules in full-disc dopplergrams. The method was developed using synthetic data. The data processing the data are transformed during the data processing into a suitable coordinate system, the noise is removed, and finally the velocity field is calculated. Resulting velocities are compared with the model velocities and the calibration is done. From our results it becomes clear that this method could be applied to full-disc dopplergrams acquired by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SoHO).Comment: Accepted in Astronomy and Astrophycic