The effect of air-entrainment on concrete containing chert gravel

The problem which the writer is analyzing in this paper has been suggested to him by Prof. Carlton of the Civil Engineering Department. It consists of two parts. 1. Bar-Run aggregate is to be obtained from Springcreek near Rolla. This material is to be screened and recombined to obtain the best gradation for highest strength concrete obtainable. Durability studies are to be made on the concrete resulting from best established mix by varying the amount of air entrainment compound (Vinsol Resin) to be added to the cement --Introduction, page 1

INTERPRETATION OF CLAY SWELLING VIA NON- CONTACT LINEAR DISPLACEMENT METER (NC-LDM)

Shale instability is one of the ongoing major problems when drilling oil/gas wellbores. The interaction of aqueous drilling fluids or fracturing fluids, with reactive clay minerals in shales causes swelling, in turn causing costly wellbore instabilities. In this study, the swelling of compacted commercial Na-bentonite clay mineral cores was investigated using a novel non-contact displacement meter with various organic solvents and salt solutions as the electrolyte. Swelling results with organic solvents were correlated with the dielectric constant, dipole moment, surface tension and viscosity of the solvent. It was found that swelling rate and total swelling were proportional to dielectric constant and inversely proportional to viscosity, representing the chemical and capillary components of swelling, respectively. Results of swelling tests with salt solutions are discussed in the context of diffuse double layer (DDL) theory. Swelling behaviour of smectite clay minerals were found to be highly affected by cation concentration. Tests with CaCl2 solutions showed that divalent cations were effective at suppressing swelling at low concentrations. At high concentrations KCl and KI solutions were more effective at inhibiting swelling owing to the lower hydration enthalpy of K+ cations. Repeats of selected tests with non-swelling illite rich shale compacted cores were compared with the swelling Na-bentonite clay mineral compacted cores. Comparison between Na-bentonite and illite swelling shows that, for reconstituted compacted cores, the initial stage of clay swelling is dominated by capillary action. Then, depending on the reactivity of the clay and the medium, chemical swelling occurs. Consequently, the swelling behaviour of compacted clay cores, as used by many drilling fluid research laboratories, is highly dependent on the domination of different swelling components in different time periods as an artefact of the sample preparation and care should be taken when using ground and compacted shales to assess either reactivity of shale formations to drilling fluids or the effectiveness of swelling inhibitor systems

FEAR, ANXIETY, BURNOUT, AND INSOMNIA LEVELS OF HEALTHCARE WORKERS DURING COVID-19 PANDEMIC IN TURKEY

Background: This study aims to assess fear, anxiety, anxiety sensitivity, burnout, and insomnia of healthcare workers (HCWs) during novel coronavirus-2019 (COVID-19) outbreak and to identify their relation to sociodemographic and clinical characteristics. Subjects and methods: Totally 600 HCWs were included in this cross-sectional study. A Sociodemographic Data Form, Coronavirus Anxiety Scale (CAS), Fear of COVID-19 Scale (FCV-19S), Anxiety Sensitivity Index-3 (ASI-3), Maslach Burnout Inventory (MBI), and Insomnia Severity Index (ISI) were used. Results: Of participants, 364 were females and 236 were males with a mean age of 33,49+-7,29 years. About 95.3% of HCWs had a fear of infecting their loved ones. Mean MBI and ISI scores were significantly higher among HCWs working in COVID-19 clinics and intensive care units (p=0.000; p=0.039). Mean CAS, FCV-19S, MBI, and ISI scores were significantly higher in women than men (p=0.000; p=0.000; p=0.027; p=0.005). Mean CAS and ISI scores were significantly higher among nurses (p=0.008; p=0.004), while mean ASI-3 of the other HCWs and MBI scores of physicians were significantly higher (p=0.009; p=0.000). Conclusion: The COVID-19 pandemic is a major health issue associated with psychiatric illnesses in HCW subgroups with distinct sociodemographic characteristics. It is of utmost importance to develop individualized preventive and therapeutic psychiatric services for HCWs

Metode savladavanja dormantnosti i značajke klijavosti sjemena vrste Acer trautvetteri Medvedev

In this study, seed dormancy removal and germination characteristics of Acer trautvetteri Medvedev, is one of the major maple species of the eastern Black Sea region, were studied. To do that, the seeds were collected in 2008 three times with aproximately 15-days intervals. In order to remove dormancy, several germination treatments were applied. The treatments were (1) different seed collection time, (2) soaking in water, (3) cold-moist stratification and (4) GA3 (gibberellic acid) application. The treated seeds were germinated in growing chamber at 5 0C and in greenhouse conditions. This research indicated that seeds of Acer trautvetteri exhibit physiological dormancy and require stratification period to remove seed dormancy. The highest germination percentage in the growing chamber subjected to GA3 application after eight weeks of stratification treatment was 66 % for Acer trautvetteri seeds. The highest germination percentage in greenhouse was obtained with cold stratification after eight weeks (81 %). Although GA3 treatment had a positive effect on germination in growth chamber + 5 0C, GA3 treatment had a negative effect on germination in greenhouse conditions. Soaking in water of nonstratified seeds wasn’t any significant difference on seed germination. There was a positive correlation between seed collection time and germination (r=0.59). As a result, the third collection time (in october) should be preferred as seed collection time in Acer trautvetteri seeds, considering that it may vary according to the climatic conditions of the year.Vrsta Acer trautvetteri Medvedev geografski je rasprostranjen na Kavkazu i u Turskoj. Pridolazi na visinama od 400 do 2100 m. U ovom radu raspravljamo o savladavanju dormantnosti i značajkama klijanja sjemena vrste Acer trautvetteri Medvedev, jedne od glavnih vrsta javora u istočnom crnomorskom području. U tu je svrhu godine 2008. prikupljano sjeme u tri navrata s razmakom od 15 dana. Kako bismo savladali dormantnost, primijenili smo nekoliko tretmana klijanja. Tretmani su uključivali (1) različito vrijeme sakupljanja sjemena, (2) namakanje u vodi, (3) hladno-vlažnu stratifikaciju i (4), primjenu GA3 (giberelinske kiseline). Tretirano sjeme klijalo je u komori rasta pri 5 0C i u stakleničkim uvjetima. Ovom studijom utvrđeno je da sjeme vrste Acer trautvetteri pokazuje fiziološku dormantnost i da je za savladavanje dormantnosti potreban period stratifikacije. Najviši postotak klijavosti sjemena vrste Acer trautvetteri u komori rasta uz primjenu GA3 nakon osam tjedana stratifikacije iznosio je 66 % . Najviši postotak klijanja u stakleniku postignut je hladnom stratifikacijom nakon osam tjedana (81 %). Postotak klijanja sjemena vrste Acer trautvetteri stratificiranog tijekom osam tjedana bio je viši od postotka klijanja nestratificiranog sjemena i u komori rasta i u stakleničkim uvjetima. Ova činjenica potvrđuje da sjeme vrste Acer trautvetteri pokazuje fiziološku dormantnost i da je za savladavanje dormantnosti sjemena potreban period stratifikacije. Iako je tretman s GA3 imao pozitivan utjecaj na klijavost u komori rasta pri +5 0C, tretman s GA3 negativno je utjecao na klijanje u stakleničkim uvjetima. Namakanje nestratificiranog sjemena u vodi nije pokazalo neku značajniju razliku na klijavost sjemena. Postoji pozitivna korelacija između vremena prikupljanja sjemena i klijanja (r=0.59). Shodno tome, preporučuje se treće vrijeme prikupljanja (u listopadu) sjemena vrste Acer trautvetteri. Točno vrijeme sakupljanja sjemena može varirati ovisno o klimatskim godišnjim uvjetima

FEAR, ANXIETY, BURNOUT, AND INSOMNIA LEVELS OF HEALTHCARE WORKERS DURING COVID-19 PANDEMIC IN TURKEY

Background: This study aims to assess fear, anxiety, anxiety sensitivity, burnout, and insomnia of healthcare workers (HCWs) during novel coronavirus-2019 (COVID-19) outbreak and to identify their relation to sociodemographic and clinical characteristics. Subjects and methods: Totally 600 HCWs were included in this cross-sectional study. A Sociodemographic Data Form, Coronavirus Anxiety Scale (CAS), Fear of COVID-19 Scale (FCV-19S), Anxiety Sensitivity Index-3 (ASI-3), Maslach Burnout Inventory (MBI), and Insomnia Severity Index (ISI) were used. Results: Of participants, 364 were females and 236 were males with a mean age of 33,49+-7,29 years. About 95.3% of HCWs had a fear of infecting their loved ones. Mean MBI and ISI scores were significantly higher among HCWs working in COVID-19 clinics and intensive care units (p=0.000; p=0.039). Mean CAS, FCV-19S, MBI, and ISI scores were significantly higher in women than men (p=0.000; p=0.000; p=0.027; p=0.005). Mean CAS and ISI scores were significantly higher among nurses (p=0.008; p=0.004), while mean ASI-3 of the other HCWs and MBI scores of physicians were significantly higher (p=0.009; p=0.000). Conclusion: The COVID-19 pandemic is a major health issue associated with psychiatric illnesses in HCW subgroups with distinct sociodemographic characteristics. It is of utmost importance to develop individualized preventive and therapeutic psychiatric services for HCWs

Utjecaj različitih tretmana na prekid dormantnosti i klijavost sjemena Acer cappadocicum Gleditsch var. cappadocicum

This study was carried out to determine effects of different pretreatment on seed germination and to overcome dormancy in Acer cappadocicum seeds. The seeds were collected in 2008 three times with aproximately 15-days intervals. In order to overcome dormancy, several germination treatments were applied. The treatments were (1) different seed collection time, (2)soaking in water, (3) cold-moist stratification and (4) GA3 (gibberellic acid) application. The treated seeds were germinated in growing chamber at 5 0C and in greenhouse conditions. This research showed that seeds of Acer cappadocicum exhibit physiological dormancy and require stratification period to overcome seed dormancy. The highest germination percentage in the growing chamber subjected to GA3 process after eight weeks of stratification treatment was 62 % for Acer cappadocicum seeds. The highest germination percentage in greenhouse was obtained with cold stratification after eight weeks (95 %). It was found out that GA3 treatment had a significant effect on germination in growth chamber + 5 0C but GA3 treatment didn’t have a significant effect on germination in greenhouse conditions. GA3 treatment and soaking of unstratified seeds in water for 48 hr didn’t have any positive effect on germination value in greenhouse conditions. Although growth chamber and green house results both indicated that seed collection time did not seem to play a role as statistically on seed germination, Duncan’s test showed that the third seed collection time was in a different group.Acer cappadocicum var. cappadocicum široko je rasprostranjen na Kavkazu, u Zapadnoj Aziji i na Himalaji. Javlja se u sjeveroistočnoj Anatoliji u Turskoj na visinama od 400 m do 1600 m, a uobičajen je i u regijama Ordu, Giresun, Trabzon, Rize i Artvin u Turskoj. Iako se Acer cappadocicum prirodno širi u šumama istočnog Crnog mora, on se ne može proizvesti u dovoljnim količinama u privatnim i šumskim rasadnicima. U istraživanju pošumljavanja jedno od glavnih načela odnosi se na korištenje prirodno rastućih vrsta. U ovom radu istraženo je otklanjanje dormantnosti sjemena Acer cappadocicum, jedne od važnih vrsta Acer u području istočnog Crnog mora. Ovaj rad bavi se istraživanjem ­utjecaja U ovom radu istražen je utjecaj predtretmana na klijavost sjemena i otklanjanja dormantnosti sjemena Acer cappadocicum. Sjeme je prikupljeno 2008. godine u tri navrata u intervalima od približno 15 dana. Kako bi se otklonila dormantnost, primijenjeno je nekoliko tretmana klijanja. Tretmani su uključivali (1) različito vrijeme prikupljanja sjemena, (2) potapanje u vodi, (3) hladno-vlažnu stratifikaciju i (4) primjenu GA3 (giberelinska kiselina). Tretirano sjeme podvrgnuto je klijanju u komori rasta na temperaturi od 5 0C i u stakleničkim uvjetima. Ovim istraživanjem je utvrđeno da sjeme Acer cappadocicum pokazuje fiziološku dormantnost i da je za otklanjanje dormantnosti sjemena potrebno razdoblje stratifikacije. U preliminarnim pokusima sjeme Acer cappadocicum podvrgnuto je hladno-vlažnoj stratifikaciji tijekom osam tjedana. Kad je period stratifikacije produžen, većina sjemena proklijala je tijekom perioda stratifikacije. Najviši postotak klijavosti u komori rasta izloženom postupku s GA3 nakon osam tjedana stratifikacije iznosio je 62. Najviši procenat klijavosti u stakleniku postignut je postupkom hladne stratifikacije nakon osam tjedana (95 %). Utvrđeno je da tretman s GA3 nije imao značajniji utjecaj na klijavost u stakleničkim uvjetima. Prema tomu, za sijanje sjemena Acer cappadocicum u stakleničkim uvjetima ne preporučuje se primjena GA3. Tretman s GA3 i potapanje nestratificiranog sjemena u vodi 48 sati nije imao pozitivne učinke na vrijednosti klijavosti u stakleničkim uvjetima. Iako rezultati dobiveni u komori rasta i stakleniku pokazuju da vrijeme prikupljanja sjemena nije statistički utjecalo na klijavost sjemena, Dunkanov test ukazuje na to da se kllijavost sjemena sakupljenog u trećem navratu signifikantno razlikuje u odnosu na klijavost sjemena sakupljenog u prva dva navrata. Rezultati pokazuju da je najbolje vrijeme za prikupljanje sjemena Acer cappadicucum ono iz trećeg navrata (u listopadu), ali ono može i varirati ovisno o klimatskim uvjetima tijekom godine

RENTQUAL: a new measurement scale for car rental services

Service quality perception is one of the key determinants of customer satisfaction and repeat purchase. As such, it has received considerable attention in the marketing literature. Quality issues in the car rental industry, however, have received less attention. Furthermore, there is lack of a scale developed to measure service quality in car rental services. This paper aims to develop a measurement scale in accordance with the procedure recommended by Churchill (1979) and Parasuraman, Zeithaml, and Berry (1988). Empirical studies were conducted in two waves. First, qualitative research was undertaken in the form of 23 in-depth interviews that produced 61 items describing tourists’ perceptions. Then, a quantitative study was used to purify the scale items and to examine dimensionality, reliability, factor structure and validity. Finally, an 18-item RENTQUAL scale with the following six factors emerged: comfort, delivery, safety, handing over, ergonomics and accessibility. Results show that safety is the most important factor in car rental services. Paper also presents scale development procedure, discussion, implications and limitations

A nonlocal physics-informed deep learning framework using the peridynamic differential operator

The Physics-Informed Neural Network (PINN) framework introduced recently incorporates physics into deep learning, and offers a promising avenue for the solution of partial differential equations (PDEs) as well as identification of the equation parameters. The performance of existing PINN approaches, however, may degrade in the presence of sharp gradients, as a result of the inability of the network to capture the solution behavior globally. We posit that this shortcoming may be remedied by introducing long-range (nonlocal) interactions into the network's input, in addition to the short-range (local) space and time variables. Following this ansatz, here we develop a nonlocal PINN approach using the Peridynamic Differential Operator (PDDO)---a numerical method which incorporates long-range interactions and removes spatial derivatives in the governing equations. Because the PDDO functions can be readily incorporated in the neural network architecture, the nonlocality does not degrade the performance of modern deep-learning algorithms. We apply nonlocal PDDO-PINN to the solution and identification of material parameters in solid mechanics and, specifically, to elastoplastic deformation in a domain subjected to indentation by a rigid punch, for which the mixed displacement--traction boundary condition leads to localized deformation and sharp gradients in the solution. We document the superior behavior of nonlocal PINN with respect to local PINN in both solution accuracy and parameter inference, illustrating its potential for simulation and discovery of partial differential equations whose solution develops sharp gradients

The Relationship between Institutional Structure and Economic Growth: A Comparative Analysis for Selected Countries

This study explores the long-run relationship between institutional structure and economic growth for selected countries for 1993-2012 period by using dynamic panel data analysis. The results can be summarized as follows: i) There exists a cross-sectional dependence for variables and models ii) All variables are stationary at their first difference except for institutional indicator of second group. iii) There exists a cointegration relationship between non-stationary variables. iv) Institutional structure has positive and statistically significant impact on economic growth in First group of countries. v) There is no significant relationship between institutional structure and economic growth in second group of countries. vi) Gross capital formation has positive impact on economic growth in both groups. Keywords: Institutional Economics, Institutional Structure, Economic Growth, Panel Data Analysis, International Country Risk Guide. JEL Classifications: C33, D72, O5

The Convergence Behavior of CO2 Emissions in Seven Regions under Multiple Structural Breaks

The aim of this paper is to examine the convergence behavior of carbon dioxide emissions per capita (co) in seven regions for 1960-2011 period by using recently developed the second generation panel data methods. Empirical results are as follows: i) there exists cross-sectional dependency for co variable ii) the CADF unit root test without structural breaks shows that the co variable is stationary at its first differences, iii) but the PANKPSS unit root test with structural breaks the co variable is stationary at its level. The overall results indicate that the regional stochastic convergence of carbon emission per capita is valid for the seven regions under structural breaks and any environmental shock has temporary effect. Keywords: Carbon Emissions, Stochastic Convergence, Panel Data. JEL Classifications: C33, Q53, Q5