The electrostatic instability for realistic pair distributions in blazar/EBL cascades

This work revisits the electrostatic instability for blazar-induced pair beams propagating through IGM with the methods of linear analysis and PIC simulations. We study the impact of the realistic distribution function of pairs resulting from interaction of high-energy gamma-rays with the extragalactic background light. We present analytical and numerical calculations of the linear growth rate of the instability for arbitrary orientation of wave vectors. Our results explicitly demonstrate that the finite angular spread of the beam dramatically affects the growth rate of the waves, leading to fastest growth for wave vectors quasi-parallel to the beam direction and a growth rate at oblique directions that is only by a factor of 2-4 smaller compared to the maximum. To study the non-linear beam relaxation, we performed PIC simulations that take into account a realistic wide-energy distribution of beam particles. The parameters of the simulated beam-plasma system provide an adequate physical picture that can be extrapolated to realistic blazar-induced pairs. In our simulations the beam looses only 1\% percent of its energy, and we analytically estimate that the beam would lose its total energy over about $100$ simulation times. Analytical scaling is then used to extrapolate to the parameters of realistic blazar-induced pair beams. We find that they can dissipate their energy slightly faster by the electrostatic instability than through inverse-Compton scattering. The uncertainties arising from, e.g., details of the primary gamma-ray spectrum are too large to make firm statements for individual blazars, and an analysis based on their specific properties is required.Comment: Accepted for publication in ApJ (2018), in prin

Plasma effects on relativistic pair beams from TeV blazars: PIC simulations and analytical predictions

Pair beams produced by very high-energy radiation from TeV blazars emit gamma rays in the GeV band by inverse-Compton scattering of soft photons. The observed GeV-band signal is smaller than that expected from the full electromagnetic cascade. This means that the pair beams must be affected by other physical processes reducing their energy flux. One possible loss mechanism involves beam-plasma instabilities that we consider in the present work. For realistic parameters the pair beams can not be simulated by modern computers. Instead, we use a simple analytical model to find a range of the beam parameters that (i) provides a physical picture similar to that of realistic pair beams and (ii) at the same time can be handled by available computational resources. Afterwards, we performed corresponding 2D PIC simulations. We confirm that the beams experience only small changes in the relevant parameter regime, and other processes such as deflection in magnetic field must be at play.Comment: 11 pages, 19 figures, 1table, accepted for publication in A&

Non-relativistic perpendicular shocks modeling young supernova remnants: nonstationary dynamics and particle acceleration at forward and reverse shocks

For parameters that are applicable to the conditions at young supernova remnants, we present results of 2D3V particle-in-cell simulations of a non-relativistic plasma shock with a large-scale perpendicular magnetic field inclined at 45-deg angle to the simulation plane to approximate 3D physics. We developed an improved clean setup that uses the collision of two plasma slabs with different density and velocity, leading to the development of two distinctive shocks and a contact discontinuity. The shock formation is mediated by Weibel-type filamentation instabilities that generate magnetic turbulence. Cyclic reformation is observed in both shocks with similar period, for which we note global variations on account of shock rippling and local variations arising from turbulent current filaments. The shock rippling occurs on spatial and temporal scales given by gyro-motions of shock-reflected ions. The drift motion of electrons and ions is not a gradient drift, but commensurates with E x B drift. We observe a stable suprathermal tail in the ion spectra, but no electron acceleration because the amplitude of Buneman modes in the shock foot is insufficient for trapping relativistic electrons. We see no evidence of turbulent reconnection. A comparison with other 2D simulation results suggests that the plasma beta and the ion-to-electron mass ratio are not decisive for efficient electron acceleration, but pre-acceleration efficacy might be reduced with respect to the 2D results once three-dimensional effects are fully accounted for. Other microphysical factors may also be at play to limit the amplitude of Buneman waves or prevent return of electrons to the foot region.Comment: Astrophysical Journal, in press, some figures with low resolutio

Automatic and adaptable registration of live RGBD video streams sharing partially overlapping views

In this thesis, we introduce DeReEs-4v, an algorithm for unsupervised and automatic registration of two video frames captured depth-sensing cameras. DeReEs-4V receives two RGBD video streams from two depth-sensing cameras arbitrary located in an indoor space that share a minimum amount of 25% overlap between their captured scenes. The motivation of this research is to employ multiple depth-sensing cameras to enlarge the field of view and acquire a more complete and accurate 3D information of the environment. A typical way to combine multiple views from different cameras is through manual calibration. However, this process is time-consuming and may require some technical knowledge. Moreover, calibration has to be repeated when the location or position of the cameras change. In this research, we demonstrate how DeReEs-4V registration can be used to find the transformation of the view of one camera with respect to the other at interactive rates. Our algorithm automatically finds the 3D transformation to match the views from two cameras, requires no human interference, and is robust to camera movements while capturing. To validate this approach, a thorough examination of the system performance under different scenarios is presented. The system presented here supports any application that might benefit from the wider field-of-view provided by the combined scene from both cameras, including applications in 3D telepresence, gaming, people tracking, videoconferencing and computer vision

Utilization of bio-waste cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) in wood-based composite particleboard

The objective of this study was to investigate some mechanical (modulus of rupture, modulus of elasticity and internal bond) and physical (thickness swelling and water absorption) properties of wood-based three-layer particleboard containing different cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) wood particle ratios (30, 50 and 70%) using urea formaldehyde resin. Addition of cotton stalk and paulownia wood in particleboard improved mechanical properties of resulting composites boards significantly. However, the water resistance decreased with increasing cotton stalk and paulownia wood particle contents. The highest mechanical properties were obtained at cotton stalk and paulownia wood particle loading of 50 and 70%, respectively. Conclusively, valuable underutilized natural resources, cotton stalk and paulownia wood can be used with the mixture of industrial wood particles in the production of particleboards with high mechanical properties.Keywords: Wood, resin, urea-formaldehyde, mechanical properties, physical propertie

Talaş Kaldırma İşlemlerinde Takım Durumunun İzlemesi İçin Son Gelişmelerin İncelenmesi

Bu çalışmada, takım durumunun izlemesi için son yıllarda yapılan çalışmalar incelenmiş ve talaş kaldırma işlemlerinin izlenmesinde etki sağlayan parametreler tartışılmıştır. Son yıllardaki çalışmalar göz önüne alınarak, takım durumunun izlenmesi için etkili değişkenler, sinyal işleme metotları, veri seçilmesi ve izleme sınırlıkları tartışılarak tüm avantajları ve dezavantajları incelenmiştir. Ayrıca bu makalede takım izleme modelinin genelliğinin geliştirilmesi için kullanılan ve en çok tanınan deney tasarım metotlarından bahsedilmiştir. Son olarak, takım durumunun tahmini için kullanılan tüm karar destek sistemleri bahsedilerek gerekli karşılaştırmalar yapılmıştır. Buna ek olarak, en güvenilir karar destek sistemleri açık bir şekilde anlatılmış ve farklı deney tasarımı prosedürüne uygun olan yöntemler bahsedilmiştir

Study of factors influencing job satisfaction education and training staff

ABSTRACT Job satisfaction is an important factor to increase productivity and employee attachment to the workplace. It is vital to identify the factors which influence the job satisfaction because the consequences of organizational and individual life plays an important role. We aimed to investigate the factors affecting the job satisfaction dealing with education and examines which components has a greater role in job satisfaction. A total of 90 employees were randomly sampled in education. Job satisfaction questionnaire for data collection was provided for this organization that has 11 dimensions (career development, empowerment, equal opportunities organizations participation, learning opportunities and achieve goals, gratitude, explanation and evaluation purposes development and training, human resources, facilities and services, wages and benefits, contact colleagues).To analyze the data, SPSS software was used. The results showed that the recognition of employees (r = .889) and the acknowledgments, respectively, human resource training and participation has the greatest impact on job satisfaction. According to research findings, as appreciation increase among the employee, job satisfaction increases, and improves the performance of the organization effectively and valuably

National Health Service Principles as Experienced by Vulnerable London Migrants in "Austerity Britain": A Qualitative Study of Rights, Entitlements, and Civil-Society Advocacy

Background: Recent British National Health Service (NHS) reforms, in response to austerity and alleged ‘health tourism,’ could impose additional barriers to healthcare access for non-European Economic Area (EEA) migrants. This study explores policy reform challenges and implications, using excerpts from the perspectives of non-EEA migrants and health advocates in London. Methods: A qualitative study design was selected. Data were collected through document review and 22 indepth interviews with non-EEA migrants and civil-society organisation representatives. Data were analysed thematically using the NHS principles. Results: The experiences of those ‘vulnerable migrants’ (ie, defined as adult non-EEA asylum-seekers, refugees, undocumented, low-skilled, and trafficked migrants susceptible to marginalised healthcare access) able to access health services were positive, with healthcare professionals generally demonstrating caring attitudes. However, general confusion existed about entitlements due to recent NHS changes, controversy over ‘health tourism,’ and challenges registering for health services or accessing secondary facilities. Factors requiring greater clarity or improvement included accessibility, communication, and clarity on general practitioner (GP) responsibilities and migrant entitlements. Conclusion: Legislation to restrict access to healthcare based on immigration status could further compromise the health of vulnerable individuals in Britain. This study highlights current challenges in health services policy and practice and the role of non-governmental organizations (NGOs) in healthcare advocacy (eg, helping the voices of the most vulnerable reach policy-makers). Thus, it contributes to broadening national discussions and enabling more nuanced interpretation of ongoing global debates on immigration and health

National Health Service Principles as Experienced by Vulnerable London Migrants in “Austerity Britain”: A Qualitative Study of Rights, Entitlements, and CivilSociety Advocacy

Background: Recent British National Health Service (NHS) reforms, in response to austerity and alleged ‘health tourism,’ could impose additional barriers to healthcare access for non-European Economic Area (EEA) migrants. This study explores policy reform challenges and implications, using excerpts from the perspectives of non-EEA migrants and health advocates in London. Methods: A qualitative study design was selected. Data were collected through document review and 22 indepth interviews with non-EEA migrants and civil-society organisation representatives. Data were analysed thematically using the NHS principles. Results: The experiences of those ‘vulnerable migrants’ (ie, defined as adult non-EEA asylum-seekers, refugees, undocumented, low-skilled, and trafficked migrants susceptible to marginalised healthcare access) able to access health services were positive, with healthcare professionals generally demonstrating caring attitudes. However, general confusion existed about entitlements due to recent NHS changes, controversy over ‘health tourism,’ and challenges registering for health services or accessing secondary facilities. Factors requiring greater clarity or improvement included accessibility, communication, and clarity on general practitioner (GP) responsibilities and migrant entitlements. Conclusion: Legislation to restrict access to healthcare based on immigration status could further compromise the health of vulnerable individuals in Britain. This study highlights current challenges in health services policy and practice and the role of non-governmental organizations (NGOs) in healthcare advocacy (eg, helping the voices of the most vulnerable reach policy-makers). Thus, it contributes to broadening national discussions and enabling more nuanced interpretation of ongoing global debates on immigration and health