Modeling Momentum-Diffusion in the Solar Wind

Energetic particles accelerated by large solar flares and coronal mass ejections (CMEs) are a threat to astronauts, global positioning systems (GPS), radio communications, and power grids. It is therefore vital that scientists be able to predict how such particles move and gain energy within the interplanetary medium in order to forewarn society impending hazards so that mitigating actions can be taken. In this work, I take a step towards this goal, using the Energetic Particle Radiation Environment Module (EPREM) code, which is used by UNH\u27s radiation-dosage predictions website, I model interstellar-pickup ions (PUIs). I add to the model by including a momentum-diffusion term which contributes to the change in the distribution as it evolves in time. Here, I investigate how the given model of momentum diffusion affects the energetic PUI population ($v\u3eu_{sw}$). This analysis focuses on the power-law spectra of the suprathermal tail of the PUI distribution. When the velocity dependence of the diffusion coefficient is normalized to the local solar-wind velocity, I have found little to no change in the spectra of the suprathermal ion tails when momentum-diffusion is included; however, when the velocity dependence of the diffusion coefficient is not normalized, hardening of the spectra of the suprathermal ion tail is observed. It is possible that the effect of momentum-diffusion and particle acceleration in CIRs is the source of the energetic seed particle population, which makes up the available particles to be accelerated by a shock. In order to understand these potentially dangerous seed particles, we hope to use new observations from Parker Solar Probe to determine the acceleration processes, such as momentum-diffusion, that yield the observed spectra

Modeling Momentum-Diffusion in the Solar Wind

The Sun is both a resource and a danger. We must be able to predict or have forewarning of large solar flares and coronal mass ejections (CMEs) and their potential threats to astronauts, GPS, radio communications, and power grids. I have used the Energetic Particle Radiation Environment Module (EPREM) code, which is used by PREDICCS, UNH\u27s radiation dosage predictions website, to model interstellar-pickup ions (PUIs). I add to the model by including a momentum-diffusion term which contributes to the change in the distribution as it evolves in time. Here, I investigate how the given model of momentum-diffusion affects the energetic PUI population (with velocity greater than the solar wind velocity). This analysis focuses on the power-law spectra of the suprathermal tail of the PUI distribution. When the velocity dependence of the diffusion coefficient is normalized to the local solar wind velocity, I have found little to no change in the spectra of the suprathermal ion tails when momentum-diffusion is included. When the velocity dependence of the diffusion coefficient is not normalized, hardening of the spectra of the suprathermal ion tail is observed. It is possible that the affect of momentum-diffusion and particle acceleration in CIR\u27s are the source of the energetic seed particle population, which makes up the available particles to be accelerated by a shock. In order to understand these potentially dangerous seed particles, we hope to use new observations from Parker Solar Probe to determine the acceleration processes, such as momentum-diffusion, that yield the observed spectra

A practical method for preparing Ca(OH)2 nanodispersions for the consolidation of archaeological calcareous stones

Exposure to atmospheric conditions results in considerable deterioration of calcareous building stones, lime mortars and plasters in archaeological monuments, requiring several conservation treatments. During the consolidation treatments of the deteriorated calcareous stones, compatibility can best be achieved by introducing a material that would have similar chemical composition and mineralogical structure with the original stone. In recent years, studies on the preparation of Ca(OH)2 nanodispersions for the consolidation of limestone and marble have increased but the preparation processes of these nanodispersions are usually complicated and time consuming. This study aimed to prepare Ca(OH)2 nanodispersions in ethyl alcohol at sufficient concentration levels with a practical method for the consolidation of calcareous archaeological materials. The preparation of higher concentrations of Ca(OH)2 nanodispersion in ethyl alcohol was done by using nano sized CaO and its dispersion in ethyl alcohol. Deteriorated marble pieces from Roman Marble Quarry near Pessinus Archaeological site (Ballıhisar, Turkey) were treated with the prepared Ca(OH)2 nanodispersion and kept at high relative humidity (~90%) at room temperature in the laboratory. Efficient penetration of the nanodispersion, and increase in the physicomechanical properties of treated marbles were followed by examinations with polarizing microscope, SEM, XRD and ultrasonic pulse velocity measurements. Carbonation of the dispersion was followed by titrimetric analysis. Calcite was the main polymorph observed after carbonation. The results showed that consolidation treatments with Ca(OH)2 nanodispersions similar to the one prepared in this study can be used for all calcareous archaeological materials that need improvements in their physical and mechanical properties. © 2018 MAA

A novel protective barrier for extremity surgeries during the COVID-19 pandemic

Aim: To present a novel protective barrier for COVID-19 transmission and investigate its effectiveness in protection against spreading aerosols and droplets during extremity surgery. Methods: We enrolled 436 patients who underwent urgent and essential surgery on the upper and lower extremity using a novel protective barrier under wide-awake local anesthesia. All patients were investigated in detail for COVID-19 infection with anamnesis, symptom questionnaires, and the required tests before surgery. Patient satisfaction regarding comfort during the surgery behind the protective barrier was analyzed using a five-point Likert scale. The protective effect of the transparent barrier was quantitatively and experimentally analyzed using smoke and saline transmission tests in different clinic scenarios with and without the protective barrier. Results: A total of 345 patients with no signs of COVID-19 infection underwent surgery. Ninety-one suspected patients who had positive COVID-19 symptoms or close contact with a COVID-19 infected patient underwent COVID-19 tests before surgery. All patients underwent urgent surgical treatment on the upper and lower extremities, and easily tolerated and were satisfied with the protective barrier. There was a statistically significant reduction in smoke and saline particles when using the protective barrier (p<0.001). The addition of negative suction and oxygen to the protective barrier potentiated the protective effect (p<0. 001). Conclusions: Extremity surgeries, especially hand surgeries, are one of the most common surgical procedures during the COVID-19 pandemic. Our protective barrier significantly reduced aerosol particles in our experimental model and was successfully used in clinical practice during extremity surgery. &nbsp

Early-age monitoring of fresh cementitious material by acoustic emission

Concrete properties are mainly affected by the fresh state since it has a significant impact on the long-term concrete performance. In this study, acoustic emission (AE) was applied to monitor the behavior of fresh cement paste. AE is based on the detection of high-frequency elastic waves originating from different material sources. This highly sensitive technique provides data that contribute to a deeper understanding of the different ongoing processes for fresh concrete, as the possible AE sources are many. Characterization of each different source type is difficult and therefore, a combined methodology of AE, capillary pressure in the matrix and specimen deformation was applied to monitor the fresh cement paste

Monitoring early-age acoustic emission of cement paste and fly ash paste

In this study, a combined approach of several monitoring techniques was applied to allow correlations between the AE activity and related processes such as shrinkage and settlement evolution, capillary pressure and temperature development in fresh cementitious media. AE parameters related to frequency, energy, and cumulative activity which exhibit sensitivity to the particle size distribution of cement paste are compared with inert fly ash (FA) leading to isolation of the mechanical sources from the chemical ones. Characterization of the origin of different processes occurring in cement paste during hydration is complex. Although acoustic emission (AE) monitoring has been used before, a qualitative relation between the microstructural formation or other early-age processes and the number or parameters of AE signals has not been established. The high sensitivity of AE enables the recording of elastic waves within the cementitious material, allowing the detection of even low-intensity activities

Saygun'u birinci ölüm yıldönümünde eşi Nilüfer Hanım anlatıyor:'Dostlarına açık bir insandı'

Taha Toros Arşivi, Dosya No: 9-Ahmet Adnan Saygun. Not: Gazetenin "Kültür-Sanat" köşesinde yayımlanmıştır.Unutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

Gerçek bir çağdaş sanatçı:Usmanbaş

Taha Toros Arşivi, Dosya No: 204-İlhan Usmanbaş. Not: Gazetenin "Allegro" köşesinde yayımlanmıştır

Türk müziğinde bir dönemin simgesi, çok sesli müziğin öncüsü Cemal Reşit Rey'i beş yıl önce bugün kaybettik:Kaideler gelip geçer, aslolan melodidir

Taha Toros Arşivi, Dosya No: 42-Cemal Reşit-Ahmet Reşit-Ekrem Reşit Re