Low frequency waves in HF heating of the mid-latitude ionosphere

The heating of the ionsosphere by high frequency (HF) radio waves leads to plasma processes with a wide range of scales. In the high-latitude ionosphere, extensive studies using numerical simulations using a Hall-magnetohydrodynamic model and experiments with the HAARP facility have provided a comprehensive understanding of the generation of low frequency hydromagnetic waves, both in the presence and absence of the auroral electrojet. Modulated HF heating in the F-region produces a local modulation of the electron temperature and the resulting pressure gradient give rise to a diamagnetic current, which in turn excites magnetosonic waves that propagate away from the heating region. In the E-region, where the Hall conductivity is dominant, these waves lead to oscillating Hall currents that produce shear Alfvén waves. These waves propagate along the field lines to the ground, where they are detected by ground-based magnetometers and into the magnetosphere. The observations of the shear Alfven waves by DEMETER satellite when its trajectory is over the HAARP magnetic zenith have shown the wave propagation to higher altitudes. For the mid latitude ionosphere the simulations use the Earth’s dipole magnetic field and the heating region is located at L = 1.6 and altitude of 300 km. With HF waves modulated at 2 – 10 Hz the low frequency waves are generated by essentially the same processes as in the high-latitude case, with additional features arising from the magnetic geometry of the mid-latitude ionosphere. The shear Alfven waves propagating to the magnetosphere become electromagnetic ion cyclotron (EMIC) waves at higher altitudes but do not propagate beyond the ion cyclotron resonance layer. The heating of the ionosphere generates many plasma modes, viz., the Alfven, magnetosonic, helicon, whistler and electromagnetic ion cyclotron waves, and comparison of their properties with measurements during experiments (Arecibo and Sura) will be presented

25 Years of Self-Organized Criticality: Solar and Astrophysics

Shortly after the seminal paper {\sl "Self-Organized Criticality: An explanation of 1/f noise"} by Bak, Tang, and Wiesenfeld (1987), the idea has been applied to solar physics, in {\sl "Avalanches and the Distribution of Solar Flares"} by Lu and Hamilton (1991). In the following years, an inspiring cross-fertilization from complexity theory to solar and astrophysics took place, where the SOC concept was initially applied to solar flares, stellar flares, and magnetospheric substorms, and later extended to the radiation belt, the heliosphere, lunar craters, the asteroid belt, the Saturn ring, pulsar glitches, soft X-ray repeaters, blazars, black-hole objects, cosmic rays, and boson clouds. The application of SOC concepts has been performed by numerical cellular automaton simulations, by analytical calculations of statistical (powerlaw-like) distributions based on physical scaling laws, and by observational tests of theoretically predicted size distributions and waiting time distributions. Attempts have been undertaken to import physical models into the numerical SOC toy models, such as the discretization of magneto-hydrodynamics (MHD) processes. The novel applications stimulated also vigorous debates about the discrimination between SOC models, SOC-like, and non-SOC processes, such as phase transitions, turbulence, random-walk diffusion, percolation, branching processes, network theory, chaos theory, fractality, multi-scale, and other complexity phenomena. We review SOC studies from the last 25 years and highlight new trends, open questions, and future challenges, as discussed during two recent ISSI workshops on this theme.Comment: 139 pages, 28 figures, Review based on ISSI workshops "Self-Organized Criticality and Turbulence" (2012, 2013, Bern, Switzerland

Does microcredit empower micro-entrepreneurs? Empirical evidence from Indonesia

Purpose This study provides fresh survey-based evidence from Indonesia on the impact of microcredit on empowerment of micro-entrepreneurs. Methodology Data was collected from a survey of microcredit-funded microenterprises in Surabaya, Indonesia, and its surroundings; 556 microenterprises participated voluntarily in the survey. Weighted least square mean and variance adjusted structural equation modelling (WLSMV-SEM) estimator was used to analyse the data. Findings Results show that microcredit has a positive and significant relationship on control over resources, but business performance does not significantly mediate the microcredit-empowerment relationship. Limitations Some limitations noted in this study are that the sample was obtained from one region of Indonesia, and was unbalanced in gender. The cross-sectional data of this study limits inferences of causality in the analyses, and prohibits the study from assessing longitudinal effects and from examining non-recursive models. Contribution At least in the case of Indonesia, the microcredit programme is working and the actions of policymakers and donors can be justified. However, further, more detailed and cross-country investigations are required to help donors and policymakers take a more informed approach in continuing to invest in microcredit programmes at the cost of other competing alternative strategies

Microfinance and microenterprise performance in Indonesia: an extended and updated survey

Purpose – The purpose of this paper is to address the small, women micro-entrepreneur dominated and heterogeneity limitations of the Atmadja et al. (2016) study. The sample is much larger, includes more men andismoreheterogeneous,which allows deeper insights and more meaningful explanation of the relationship between microfinance and microenterprise performance in the case of Indonesia, including the effects of gender, lending scheme and money separation. Design/methodology/approach – This study used a survey of 556 respondents across five microcredit providers in the city of Surabaya using an updated instrument. Ordered probit is used to analyse data. Findings – Microfinance may not matter for microenterprise performance in the case of Indonesia. Additionally,microcredit schemes(individual vs group)and gender may also not matter for performance,but money separation might have some influence. Practical implications – Non-financial factors such as human capital, spousal involvement, and money separation should be considered as important factors for improving microenterprise business performance in Indonesia, with less focus on microcredit per se. Originality/value – This study provides further evidence that microfinance may not matter for microenterprise performance in the case of Indonesia, a populous middle income country with a very long history of microfinance

Micro-entrepreneurs� Subjective Wellbeing: Does loan enhance happiness?

Over the last several years, microfinance has increasingly become a common financial policy tool for supporting and enhancing formation and expansion of microenterprises worldwide, particularly in developing and emerging markets. At the same time, over the last decade, intrigued by the enormous resources, including financial, allocated to developing the microfinance industry, empirical research has also exploded assessing the impact of microfinance on various aspects of micro entrepreneurship, including business formation and expansion, empowerment, and poverty alleviation�challenges which, among others, microfinance is believed to help facilitate�the results have been mixed, at best. One area that seems to have received very little, attention is the impact of microfinance on the subjective wellbeing of micro-entrepreneurs. This study endeavours to fill that gap in the literature by investigating the issue for the first time in the case of Indonesia�a developing, populous, G20 economy with a long history of microfinance. To do this, a survey was conducted in 2014 of 556 women and men micro entrepreneurs in the city of Surabaya, Indonesia�s second largest city, covering five microcredit providers. The multiple regression analysis is used to test the relationship. Intriguingly, results show that while Indonesia continues to allocate huge resources into developing its microfinance industry, microfinance, measured by microcredit, has a negative and significant association with subjective wellbeing. Thus, microcredit may be making micro-entrepreneurs less rather than more happy. Results also show that the interaction between microcredit and lending group worsen the entrepreneurs� subjective wellbeing, while business performance (proxy by change in profit), which remains a challenge, might help enhance subjective wellbeing

Examining the impact of microfinance on microenterprise performance (implications for women-owned microenterprises in Indonesia)

Purpose – The purpose of this paper is to examine the impacts of microfinance on women-owned microenterprises’ (WMEs) performance in Indonesia. It especially observes how financial, human and social capital influences performance of enterprises. Design/methodology/approach – Data were collected from a survey conducted in Surabaya, Indonesia’s second largest city, covering more than 100 WMEs. The ordered probit technique is applied to estimate the performance vis-à-vis financial, social and human capital relationships. Findings – This study finds a negative relationship between performance and financial capital, and positive relationships between performance-human capital and performance-social capital. However, with respect to human capital, the level of education has a marginally significant relationship with performance. Practical implications – Microcredit for the purposes of enhancing business performance might not necessarily be a good idea, if it is unable to generate higher returns. As a business develops, the volume of microcredit should be reduced, and replaced by owners’ own savings and retained profits. Regarding the non-financial factors, it might be useful for policy makers to contemplate providing incentives for spouse involvement in microenterprises run by women, and to consider them in designing credit policies. Group meetings activities should be extended to facilitate members to engage in business-related conversations and to develop social relationships. The ability of loan officers and group leaders to facilitate such conversations appears important. Originality/value – To the best of the authors’ knowledge, this study provides the first in-depth understanding of the role of microfinance programmes in the case of performance of WMEs in Indonesia, one of the world’s most populous economies

Detection of the Glottal Closure Instants Using Empirical Mode Decomposition

This work explores the effectiveness of the Intrinsic Mode Functions (IMFs) of the speech signal, in estimating its Glottal Closure Instants (GCIs). The IMFs of the speech signal, which are its AM–FM or oscillatory components, are obtained from two similar nonlinear and non-stationary signal analysis techniques—Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN), and Modified Empirical Mode Decomposition (MEMD). Both these techniques are advanced variants of the original technique—Empirical Mode Decomposition (EMD). MEMD is much faster than ICEEMDAN, whereas the latter curtails mode-mixing (a drawback of EMD) more effectively. It is observed that the partial summation of a certain subset of the IMFs results in a signal whose minima are aligned with the GCIs. Based on this observation, two different methods are devised for estimating the GCIs from the IMFs of ICEEMDAN and MEMD. The two methods are captioned ICEEMDAN-based GCIs Estimation (IGE) and MEMD-based GCIs Estimation (MGE). The results reveal that IGE and MGE provide consistent and reliable estimates of the GCIs, compared to the state-of-the-art methods, across different scenarios—clean, noisy, and telephone channel conditions.Fil: Sharma, A. Surja. Indian Institute of Technology; IndiaFil: Prasanna, S. R. M.. Indian Institute of Technology; IndiaFil: Rufiner, Hugo Leonardo. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas. Departamento de Informática. Laboratorio de Investigaciones en Señales e Inteligencia Computacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schlotthauer, Gaston. Universidad Nacional de Entre Ríos. Facultad de Ingeniería. Departamento de Matemática e Informática. Laboratorio de Señales y Dinámicas no Lineales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Entre Ríos. Universidad Nacional de Entre Ríos. Centro de Investigaciones y Transferencia de Entre Ríos; Argentin

Medium Range Thermosphere Ionosphere Storm Forecasts

No abstract availabl

Medium Range Thermosphere-Ionosphere Storm Forecasts

Overview of medium-range thermosphere-ionosphere storm forecasts