bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of the Bentonite Content in Diaphragm Wall Filter Cakes Based on Cation Exchange Capacity
Authors: von Blumenthal Achim , Lieske Wolfgang , König Diethard , Wichtmann Torsten 
Published: May 2021

Abstract
The formation of filter cakes is caused by filtration on the interface between soil and supporting fluid during the construction of diaphragm walls. The supporting fluid, basically a slurry of water and 4–8 % bentonite, is loaded with minerals from the soil while the trench is excavated. The filter cakes, mixtures of in situ soil and bentonite originating from the supporting fluid, are generally believed to be the weakest and therefore most significant transition zone concerning the shear force transfer from the soil to the concrete wall. Previous research has been devoted to the understanding of the composition and mechanical behavior of filter cakes. In this context, the content of bentonite in the filter cake was identified as the governing parameter. The current paper presents a novel concept to determine the amount of bentonite in the filter cake. Based on an iterative approach, the cation exchange capacity (CEC) of the filter cake, the pure bentonite, and the in situ soil is determined. A linear correlation between CEC and bentonite content in the range between 0 and 100 % could be established based on an extensive laboratory program for numerous soils and types of bentonite. This correlation can be applied to determine the bentonite content for a given filter cake. A comparison of the actual bentonite percentage of artificial sand-bentonite mixtures and the bentonite percentage determined by the CEC method revealed a good agreement (R2 ≥ 0.9825). In addition, filter cakes obtained on construction sites were examined, and a maximum deviation of ±0.84 % bentonite content was measured in duplicate tests.
A Method of Evaluating Geomembrane Strain Caused by Point Loading from Aggregates
Authors: Marcotte B. A. , Fleming I. R. 
Published: May 2021

Abstract
This paper describes the test device and performance test methodology for measuring and evaluating geomembrane strain for large gravel or tire derived aggregate (TDA). The primary purpose of evaluating geomembrane strain is for determining the adequate protection layers required in long-term waste facilities. The procedure has many advantages over previous versions, such as removal of the lead impression sheet, elimination of operator bias, and a defined method of calculation. A photogrammetry procedure is described in detail as an alternative to laser scanners. An example of a typical comparison between different protection layers is provided for a TDA sample.
Inhibition of Elevated Ras-MAPK Signaling Normalizes Enhanced Motor Learning and Excessive Clustered Dendritic Spine Stabilization in the MECP2-Duplication Syndrome Mouse Model of Autism
Authors: Ash Ryan Thomas , Buffington Shelly Alexandra , Park Jiyoung , Suter Bernhard , Costa-Mattioli Mauro , Zoghbi Huda Yaya , Smirnakis Stelios Manolis 
Published: May 2021

AbstractThe inflexible repetitive behaviors and “insistence on sameness” seen in autism imply a defect in neural processes controlling the balance between stability and plasticity of synaptic connections in the brain. It has been proposed that abnormalities in the Ras-ERK/MAPK pathway, a key plasticity-related cell signaling pathway known to drive consolidation of clustered synaptic connections, underlie altered learning phenotypes in autism. However, a link between altered Ras-ERK signaling and clustered dendritic spine plasticity has yet to be explored in an autism animal modelin vivo. The formation and stabilization of dendritic spine clusters is abnormally increased in the MECP2-duplication syndrome mouse model of syndromic autism, suggesting that ERK signaling may be increased. Here, we show that the Ras-ERK pathway is indeed hyperactive following motor training in MECP2-duplication mouse motor cortex. Pharmacological inhibition of ERK signaling normalizes the excessive clustered spine stabilization and enhanced motor learning behavior in MECP2-duplication mice. We conclude that hyperactive ERK signaling may contribute to abnormal clustered dendritic spine consolidation and motor learning in this model of syndromic autism.
Redox homeostasis in Mycobacterium tuberculosis is modulated by a novel actinomycete‐specific transcription factor
Authors: Khan Mehak Zahoor , Singha Biplab , Ali Mohammad Farhan , Taunk Khushman , Rapole Srikanth , Gourinath Samudrala , Nandicoori Vinay Kumar 
Published: May 2021

AbstractMycobacterium tuberculosis (Mtb) has evolved diverse cellular processes in response to the multiple stresses it encounters within the infected host. We explored available TnSeq datasets to identify transcription factors (TFs) that are essential for Mtb survival inside the host. The analysis identified a single TF, Rv1332 (AosR), conserved across actinomycetes with a so‐far uncharacterized function. AosR mitigates phagocyte‐derived oxidative and nitrosative stress, thus promoting mycobacterial growth in the murine lungs and spleen. Oxidative stress induces formation of a single intrasubunit disulphide bond in AosR, which in turn facilitates AosR interaction with an extracytoplasmic‐function sigma factor, SigH. This leads to the specific upregulation of the CysM‐dependent non‐canonical cysteine biosynthesis pathway through an auxiliary intragenic stress‐responsive promoter, an axis critical in detoxifying host‐derived oxidative and nitrosative radicals. Failure to upregulate AosR‐dependent cysteine biosynthesis during the redox stress causes differential expression of 6% of Mtb genes. Our study shows that the AosR‐SigH pathway is critical for detoxifying host‐derived oxidative and nitrosative radicals to enhance Mtb survival in the hostile intracellular environment.
Dynamics of pine stands condition in SE “Lymanske Forest Economy”
Authors: P. Pasternak Volodymyr , B. Prihodko Olexiy , S. Pyvovar Tetiana , Yu. Yarotsky Volodymyr 
Published: May 2021

The issue of pine forest stands health condition and mortality at the scale of one state enterprise (SE "Lymanske Forest Economy"), located in the Northern part of the Steppe zone of Ukraine, is considered.
For the study data from two repeated observations at 8 permanent plots, laid in 2019, in forest stands with varying degrees of mortality and those damaged by fire was used. A re-survey was carried out in 2020. Using the GIS Field-Map, trees were mapped at the permanent plots and their health condition, mortality, and damage were assessed. For the background assessment of pine forests condition, the results of observations at 7 forest monitoring plots (I level) (surveys of 2015 and 2020) were used. The source of climate data was the online resource ClimateCharts.net.
It was found out that over the last 10 years, due to climate change, the temperature in the region increased and the amount of precipitation decreased, which led to the appearance of a dry period in August, which is unfavourable for the growth of pine forests at the limit of their range. Groundwater levels have changed, as evidenced by the drying of Lake Lyman during 2013-2020. Obtained results showed, that the condition of pine stands in the monitoring plots significantly deteriorated compared to 2015. Currently, the condition of pine forests are considered as "weakened" and "severely weakened" (the health condition index (HCI) of living trees varied from 1.53 to 2.70), the average defoliation and mortality of trees have increased significantly. In weakened stands, the proportion of trees with damage increases over time, in particular, due to the colonization of stem insects. Forest fires pose a significant threat to the pure artificial pine forests that predominate in the region. As a result of fires, the condition of the stands deteriorated (HCI 2.49–2.70) and the number of dead trees increased.
Justification of ways increasing the immunity of special purpose radio communications
Authors: Shyshatskyi Andrii , Hasan Vitalii , Kryvenko Mykola , Petrov Oleksandr , Kravchuk Serhii , Shidlovsky Yuriy , Opalak Andrii , Modlinskyi Oleksandr , Kobylynskyi Oleksii , Bezstrochnyi Ihor 
Published: May 2021

The object of research is the military radio communication system. One of the most problematic areas in the military radio resources management is the interference of military radio systems and facilities. A number of works have been devoted to the study of ways to increase the noise immunity of military radio communication systems and facilities. However, the known works contain some research results by scientists, which are aimed at increasing the noise immunity of military radio communication systems and devices and do not have a comprehensive approach. This work solves the problem of substantiating ways to increase the noise immunity of military radio communication systems and facilities.
The scientific problem is solved by substantiating the methodological principles of increasing the noise immunity of military radio communication systems in conditions of a priori uncertainty. During the research, the authors used the main provisions of the queuing theory, the theory of automation, the theory of complex technical systems, as well as general scientific methods of cognition, namely analysis and synthesis. The novelty is that in the course of work:
– the purpose of functioning of the noise protection system of military radio communication systems is formulated;
– indicators and criteria for increasing the noise immunity of military radio communication systems have been determined;
– decomposition of the solution of this problem into problems depending on the signal and noise situation is carried out.
An approach based on the hierarchical decomposition of the networks functional structure, the behavior of which is described by stochastic differential (or difference) equations of the high dimension state, into a number of interconnected but simpler functional structures is used for the functional description of military radio communication systems. The proposed approach to describe the behavior of military radio systems will allow to decompose the military radio system state and increase the efficiency of decision-making to adjust operating modes and parameters in real time. The results of the research should be used at the stage of parameters operational management and modes of the system operation.
Recommendation of RILEM TC 261-CCF: test method to determine the flexural creep of fibre reinforced concrete in the cracked state
Authors: Llano-Torre A. , Serna P. 
Published: May 2021

AbstractTo date there is no clear consensus about how creep of cracked FRC structural elements should be considered. In recent years, different methodologies have been developed for multiple stress cases. The absence of a standardised methodology to evaluate flexural creep in the cracked state has hindered general comparisons and conclusions that could lead to significant advances in this topic. Since 2014, the study of the creep behaviour of cracked FRC has been coordinated by the RILEM TC 261-CCF. All the available creep methodologies were analysed in terms of procedure, equipment and results. A comprehensive Round-Robin Test (RRT) on the creep behaviour of cracked sections of FRC was proposed and undertaken by a total of 19 participant laboratories from 14 countries all over the world. The analysis and conclusions of the RRT results and the different methodologies provided the basis for this recommendation. This recommendation focuses on the test method to evaluate the flexural creep of FRC specimens in the cracked state. Guidelines on specimen production, detailed test equipment, experimental setup and test procedure as well as the definitions of the most relevant parameters are provided.
Burnout and Compassion Satisfaction: Survey Findings of Healthcare Employee Wellness During COVID-19 Pandemic using ProQOL
Authors: Dwyer Meagan , Alt Marcus , Brooks Joanna , Katz Hannah , Poje Albert 
Published: May 2021

Introduction. Healthcare systems are being bombarded during the COVID-19 pandemic. Understanding burnout, compassion fatigue, and potential protective factors, such as compassion satisfaction, will be important in supporting the vital healthcare workforce. The goal of the current study was to understand the key factors of burnout, compassion fatigue, and compassion satisfaction among healthcare employees during the pandemic within the U.S. in April 2020.
Methods. The authors conducted a single-center, cross-sectional online survey using the Professional Quality of Life (ProQOL) Questionnaire and three open-ended questions around stress and responses to stress during COVID-19 at a large Midwestern academic medical center with nearly 16,000 employees.
Results. Healthcare employees (613) representing over 25 professions or roles and 30 different departments within the health system were surveyed. Participants reported low levels of compassion fatigue and burnout, but moderate levels of compassion satisfaction. Compassion satisfaction was notably higher than prior literature. Key areas of stress outside of work included family, finances and housing, childcare and homeschooling, and personal health.
Conclusions. This was a cross-sectional survey, limiting causal analyses. Also, based on the qualitative responses, the ProQOL was somewhat insufficient in assessing the breadth of stressors, particularly outside of work, that healthcare employees faced due to the pandemic. Although compassion satisfaction was elevated during the initial phases of the pandemic, providing some possible protection against burnout, this may change as COVID-19 continues to surge. Healthcare systems are encouraged to assess and address the broad range of work and non-work-related stressors to best serve their vital workforce.
The Airy phase of shallow-focus submarine earthquakes*
Authors: Press Frank , Ewing Maurice , Tolstoy Ivan 
Published: May 2021

AbstractAn extension of the theoretical work of Lamb and Pekeris shows that a prominent phase (Airy phase) consisting of a group of waves of period 9-11 seconds, traveling across the ocean with a velocity of approximately 0.7 of the speed of sound in water, should be present on the seismograms of shallow-focus submarine earthquakes. This arrival corresponds to normal mode propagation at a stationary value of group velocity through the acoustic system consisting of the ocean and the rigid ocean bottom.A phase fitting this description has been observed on the Milne-Shaw instruments at Bermuda for a series of Dominican Republic shocks. The Wenner seismographs at Huancayo recorded the Airy phase of a shock southwest of the Galapagos Islands.The study of the Airy phase of a sufficient number of sea quakes would provide information concerning the nature of the ocean bottom since the latter affects both the periods and velocities of the Airy phase.
Volcanic Tremor*
Authors: Omer Guy C. 
Published: May 2021

Abstract
It is proposed that volcanic tremor originates in the vibration of laminae which are partly freed by the differential tilting of the surface of the earth around a volcanic vent during an eruption. The topographic evidence around Kilauea caldera is examined and a probable range of the free vibrating lengths is determined. The various possible modes of vibration are considered and it is concluded that longitudinal vibration would best explain the observed seismograms.
Seismic refraction measurements in the Atlantic Ocean Basin*
Authors: Ewing Maurice , Worzel J. L. , Hersey J. B. , Press Frank , Hamilton G. R. 
Published: May 2021

Abstract
A reversed seismic refraction measurement was made 120 miles northwest of Bermuda (400 miles east of Cape Hatteras) in 2,800 fathoms of water. A velocity of 24,800 feet per second (7.58 km/sec.) for the second layer was identified with the ultrabasic layer of earthquake seismology. Assuming a velocity of 5,600 feet per second (1.70 km/sec.), clearly indicated by earlier measurements, a thickness of 4,500 feet was obtained for the sedimentary layer. The granitic and intermediate layers were absent.
Velocities of P at short distances*
Authors: Richter C. F. 
Published: May 2021

abstract
Recording of P and S at six or more stations to epicentral distances not over 160 km. makes it possible to calculate the velocities, assuming only that they are constant. Origin times, epicenters, and depths are found independently of velocity.
Installation of new temporary stations has supplied appropriate data in southern California. For 6 of 8 well-recorded shocks the calculated velocity of P is near 6.4 km/sec.
Investigation of the T phase
Authors: Leet L. Don , Linehan Daniel , Berger Philip R. 
Published: May 2021

Abstract
In the bulletin of the Harvard Seismograph Station, under date of September 15, 1935, attention was directed to the unusual character of certain records from the vicinity of 17° N, 62° W. One of the novel features was a short-period phase about 23 minutes after P. It has become known as T, for third, with P and S constituting the first and second groups of short-period waves of similar general appearance. The problem was discussed with Weston, and since that time those two stations have been working on it. Linehan published in 1940 the first description outside station bulletins.
From detailed studies of more than 250 earthquakes, with all records from Harvard and Weston and selected ones from Fordham, Ottawa, and Tucson, the following results have been obtained.
The T phase ranges in period from 0.5 to 1.0 sec. It originates under the ocean and is characteristic of oceanic areas. It is generated by earthquakes of which the majority are between about 40 and 100 km. in depth. It clearly is not limited to shallow foci. It has been observed at Harvard and Weston from distances between 1,060 and 7,000 km.; from foci north of the Greater Antilles, near Bermuda, on the Mid-Atlantic Ridge in the North Atlantic, and south of the equator; originating under water ranging down to 3,000 fathoms in depth. It consists primarily of shear waves, with a velocity of between 1.6 and 2.7 km/sec. over oceanic paths and 2.1 km/sec. over land. (The velocity of sound in water of the Atlantic Ocean is from 1.46 to 1.53 km/sec.).
It is suggested that the T phase may be short-period shear waves traveling in ocean-bottom sediments and the top continental layer. An overwhelming preponderance of the evidence contradicts any hypothesis that significant amounts of the energy are water-borne.
A progressively changing angle of approach for waves in different parts of the T phase has been observed at Harvard and Weston.
In 1949, the Columbia University group composed of Ewing, Press, and Tolstoy, under a government contract, printed two reports on this subject, “The T phase of Shallow-Focus Submarine Earthquakes,” and “Proposed Tsunami Warning System.” The former was based largely on 20 Weston records which were included without discussion of the investigation or its results with either Weston or Harvard. They decided that “the T phase is characterized by periods of 0.5 sec. or less, a velocity identical with that of sound in water for the part of its path crossing deep water and by speeds from 12,000 to 18,000 ft/sec. (3.7 to 5.5 km/sec.) across shallow water or land,” and that “propagation through the sound channel accounts for the major part of the observed T phase.”
In checking their report against the original Weston records, we find that they have made elementary errors, such as misreading iP from −16 to +18 sec., and incorrectly computing epicentral distance by more than a degree. These and many others so greatly affect the fundamental solution of the problem that their conclusions cannot be accepted. This aspect will be discussed in a separate paper.
Revised travel times in southern California*
Authors: Gutenberg B. 
Published: May 2021

Abstract
Discrepancies of up to 20 per cent between wave velocities calculated from blast records in southern California and those found from earthquakes necessitate a reinterpretation of seismograms of all near-by shocks and a revision of travel-time curves. A combination of findings for S — P intervals as a function of distance in southern California earthquake records with the ratio of mean interval velocities for P and S waves shows (without assumption of origin times) that the mean velocities of the two waves between the source and the surface are about 6.35 and 3.67 km/sec., respectively. This agrees with the results found from blast records. Most revised origin times are between ¾ sec. and 1 1/2 sec. later than those found previously from P¯. The method applied here removes the difference in origin time for longitudinal and transverse waves which was found formerly for earthquakes. Travel-time curves of various phases are revised and reinterpreted. The change in amplitudes with distance of several wave types is discussed.
Hydrodynamic experiments with rigid cylindrical tanks subjected to transient motions*
Authors: Jacobsen Lydik S. , Ayre Robert S. 
Published: May 2021

Abstract
Four tanks, from 6 inches to 4 feet in diameter, have been subjected simultaneously to transient, horizontal “ground motions” of simplified type. The important parameters, in addition to size of tank, were depth of fluid and frequency, duration, and amplitude of ground motion. The envelopes of the gravity-wave profiles have been recorded on a vertical plane of symmetry placed within each tank in a direction parallel to the ground motion. The data include samples of the wave envelopes, photographic studies of the wave formation, maximum wave heights and the locations of these maxima, and the fluid damping coefficients. Equivalent mass and overturning moment due to the fluid have been shown for various degrees of confinement of the upper surface, from complete confinement (owing to use of a rigid cover) to a free surface. The study relates to the effect of earthquakes and other ground motions on oil and water storage tanks. The results can be extrapolated with reasonable certainty to full-scale tanks.
Estudio comparativo de flujo de fluido a través de una placa de orificio usando las ecuaciones de Stokes y de Navier-Stokes
Authors: Guerra-Mazo Miryam Lucía , García-Buitrago María Vilma , Rodríguez-Acevedo Elizabeth 
Published: May 2021

Presenta los resultados de la comparación entre las ecuaciones de Stokes y de Navier-Stokes para la simulación del flujo de agua líquida, a condiciones atmosféricas, a través de una placa orificio concéntrica. A partir de los datos experimentales que fueron tomados en el banco de fluidos, se evaluaron las simulaciones de ambas ecuaciones, usando el software libre Freefem++cs, que se basa en el método de los elementos finitos, las variables evaluadas son velocidad y presión en un intervalo de tiempo. Al analizar los resultados obtenidos con las simulaciones y comparar con los datos experimentales se encontró que las ecuaciones de Navier-Stokes representan mejor el sistema que la ecuación de Stokes.