634 research outputs found
A Toy Model Approach to the Canonical Non-perturbative Quantization of the Spatially Flat Robertson-Walker Spacetimes with Cosmological Constant
We present a toy model approach to the canonical non-perturbative
quantization of the spatially-flat Robertson-Walker Universes with cosmological
constant, based on the fact that such models are exactly solvable within the
framework of a simple Lagrangian formulation. The essential quantum dynamical
metric-field and the corresponding Hamiltonian, explicitly derived in terms of
annihilation and creation operators, point out that the Wheeler - DeWitt
equation is a natural (quantum) generalization of the - Einstein
equation for the classical De Sitter spacetime and selects the physical states
of the quantum De Sitter Universe. As a result of the exponential universal
expansion, the usual Fock states (defined as the eigenstates of the
number-operator) are no longer invariant under the derived Hamiltonian. They
exhibit quantum fluctuation of the energy and of the metric field which lead to
a (geometrical) volume quantization.Comment: 22 pages, LaTe
Determinants of the adoption of integrated soil fertility management technologies in Mbale division, Kenya
The agro-climatic conditions in western Kenya present the region as a food surplus area yet people are still reliant on food imports, with the region registering high poverty levels. Depletion of soil fertility and the resulting decline in agricultural productivity in Mbale division has led to many attempts to develop and popularize Integrated Soil Fertility Management (ISFM) technologies that could restore soil fertility. These technologies bridge the gap between high external inputs and extreme forms of traditional low external input agriculture. Some of the ISFM components used by farmers are organic and inorganic inputs and improved seeds. However, the adoption of these technologies is low. The study aimed to examine the factors that influence the adoption of ISFM technologies by smallholder farmers in Mbale division, Kenya. The study was conducted in 9 sub-locations in Mbale division. Purposive sampling was used in selecting the 80 farmers to get the data based on a farm-household survey. Self-administered questionnaires were used to collect data on the determinants of the adoption of ISFM technologies from the sampled farmers in the study area. The study sought to answer the research question: What factors influence the uptake of ISFM technologies by farmers in Mbale division? The hypothesis tested was that the adoption of ISFM technologies is not influenced by age, education, extension services, labour, off-farm income and farm size. Data was analyzed using descriptive statistics. Cross tabulation was used for examining the relationship between categorical (nominal or ordinal) variables, and the bivariate correlations procedure was used to compute the pair wise associations between scale or ordinal variables. Probit regression was used to predict the socio-economic factors influencing the adoption of ISFM technologies among smallholder farmers. Results of the study indicated that education of household head, membership in social groups, age of the household head, off-farm income and farm size were the variables that significantly influenced the adoption of ISFM technologies. The findings show that there is need for a more pro-poor focused approach to achieve sustainable soil fertility management among smallholder farmers. The findings will help farmers, extension officers, researchers and donors in identifying region-specific entry points that can help in developing innovative ISFM technologies.Keywords: Soil fertility, adoption, smallholder farmer, integrated soil fertility managemen
The only constant is change:a case study of business model change in the context of COVID-19 pandemic
Abstract. The spread of the COVID-19 pandemic has led to major changes across different sectors of the economy. The difficult situation of the business environments in various industries caused by the COVID-19 virus made companies struggle, some more than others. Profitable functioning in the market has therefore become more difficult. What is interesting, some companies survived, or even succeeded, during restrictions and managed to understand and operate with the changed customer behavior during and after worst phases of the world-wide pandemic.
The aim of this research study is to find out if there are dynamic capabilities as business model change enablers by understanding the activities in the design and trans-forming new, successful business model and to explain, how it was possible for these case companies to change the existing business model. The underlying assumption is, that companies which have changed their existing business model to a new one due to COVID-19 pandemic and its effect to their market environment, have had certain dynamic capabilities and a process in a form of actions in place to succeed.
This research study presents empirical findings to support theories of dynamic capabilities as enablers for business model change. One of the concrete goals of this research is to provide insights and learnings about what do the capabilities of successful companies look like, and how do they act, when they sense the change in their company’s business environment, mobilize their resources to act on those findings and finally execute and implement the change.
The empirical findings show, that dynamic capabilities work as enablers for business model innovation and business model transformation. Thus, findings support the importance of knowing and understanding your customers’ behavior and needs, as well as the knowledge of the resource potential in and outside of the company, in order to design viable business models and implement them.
Learnings gained from this research are valuable and interesting for strategists and leaders in companies when trying to improve their readiness for future environment changes. In addition, organizations, who are helping companies either to 1) grow their business or 2) survive from difficulties caused by rapid market environment change, can adopt learnings from this research study.
The methods of this research study are qualitative. In this research study, a case study method was applied and the data was collected by in-depth semi-structured interviews, complemented with questions and answers via email and by collecting articles and other media content in public sources
Quantitative Analysis of DoS Attacks and Client Puzzles in IoT Systems
Denial of Service (DoS) attacks constitute a major security threat to today's
Internet. This challenge is especially pertinent to the Internet of Things
(IoT) as devices have less computing power, memory and security mechanisms to
mitigate DoS attacks. This paper presents a model that mimics the unique
characteristics of a network of IoT devices, including components of the system
implementing `Crypto Puzzles' - a DoS mitigation technique. We created an
imitation of a DoS attack on the system, and conducted a quantitative analysis
to simulate the impact such an attack may potentially exert upon the system,
assessing the trade off between security and throughput in the IoT system. We
model this through stochastic model checking in PRISM and provide evidence that
supports this as a valuable method to compare the efficiency of different
implementations of IoT systems, exemplified by a case study
Key exchange with the help of a public ledger
Blockchains and other public ledger structures promise a new way to create
globally consistent event logs and other records. We make use of this
consistency property to detect and prevent man-in-the-middle attacks in a key
exchange such as Diffie-Hellman or ECDH. Essentially, the MitM attack creates
an inconsistency in the world views of the two honest parties, and they can
detect it with the help of the ledger. Thus, there is no need for prior
knowledge or trusted third parties apart from the distributed ledger. To
prevent impersonation attacks, we require user interaction. It appears that, in
some applications, the required user interaction is reduced in comparison to
other user-assisted key-exchange protocols
DETERMINANTS OF THE ADOPTION OF INTEGRATED SOIL FERTILITY MANAGEMENT TECHNOLOGIES IN MBALE DIVISION, KENYA
ABSTRACT The agro-climatic conditions in western Kenya present the region as a food surplus area yet people are still reliant on food imports, with the region registering high poverty levels. Depletion of soil fertility and the resulting decline in agricultural productivity in Mbale division has led to many attempts to develop and popularize Integrated Soil Fertility Management (ISFM) technologies that could restore soil fertility. These technologies bridge the gap between high external inputs and extreme forms of traditional low external input agriculture. Some of the ISFM components used by farmers are organic and inorganic inputs and improved seeds. However, the adoption of these technologies is low. The study aimed to examine the factors that influence the adoption of ISFM technologies by smallholder farmers in Mbale division, Kenya. The study was conducted in 9 sublocations in Mbale division. Purposive sampling was used in selecting the 80 farmers to get the data based on a farm-household survey. Self-administered questionnaires were used to collect data on the determinants of the adoption of ISFM technologies from the sampled farmers in the study area. The study sought to answer the research question: What factors influence the uptake of ISFM technologies by farmers in Mbale division? The hypothesis tested was that the adoption of ISFM technologies is not influenced by age, education, extension services, labour, off-farm income and farm size. Data was analyzed using descriptive statistics. Cross tabulation was used for examining the relationship between categorical (nominal or ordinal) variables, and the bivariate correlations procedure was used to compute the pair wise associations between scale or ordinal variables. Probit regression was used to predict the socio-economic factors influencing the adoption of ISFM technologies among smallholder farmers. Results of the study indicated that education of household head, membership in social groups, age of the household head, off-farm income and farm size were the variables that significantly influenced the adoption of ISFM technologies. The findings show that there is need for a more pro-poor focused approach to achieve sustainable soil fertility management among smallholder farmers. The findings will help farmers, extension officers, researchers and donors in identifying region-specific entry points that can help in developing innovative ISFM technologies
NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations
We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects)
cosmological simulations to study the effects of galaxy formation on key
properties of dark matter (DM) haloes. NIHAO consists of
high-resolution SPH simulations that include (metal-line) cooling, star
formation, and feedback from massive stars and SuperNovae, and cover a wide
stellar and halo mass range: ( ). When compared to DM-only simulations,
the NIHAO haloes have similar shapes at the virial radius, R_{\rm vir}, but are
substantially rounder inside . In NIHAO simulations
increases with halo mass and integrated star formation efficiency,
reaching at the Milky Way mass (compared to 0.5 in DM-only),
providing a plausible solution to the long-standing conflict between
observations and DM-only simulations. The radial profile of the phase-space
parameter () is best fit with a single power law in DM-only
simulations, but shows a flattening within for NIHAO
for total masses . Finally, the global velocity
distribution of DM is similar in both DM-only and NIHAO simulations, but in the
solar neighborhood, NIHAO galaxies deviate substantially from Maxwellian. The
distribution is more symmetric, roughly Gaussian, with a peak that shifts to
higher velocities for Milky Way mass haloes. We provide the distribution
parameters which can be used for predictions for direct DM detection
experiments. Our results underline the ability of the galaxy formation
processes to modify the properties of dark matter haloes.Comment: 19 pages, 17 figures, analysis strongly improved, main conclusions
unchanged, accepted for publication in MNRA
Design of High-Speed Dual Port 8T SRAM Cell with Simultaneous and Parallel READ-WRITE Feature
An innovative 8 transistor (8T) static random access memory (SRAM) architecture with a simple and reliable read operation is presented in this study. LTspice software is used to implement the suggested topology in the 16nm predictive technology model (PTM). Investigations into and comparisons with conventional 6T, 8T, 9T, and 10T SRAM cells have been made regarding read and write operations\u27 delay and power consumption as well as power delay product (PDP). The simulation outcomes show that the suggested design offers the fastest read operation and PDP optimization overall. Compared to the current 6T and 9T topologies, the noise margin is also enhanced. Finally, the comparison of the figure of merit (FoM) indicates the best efficiency of the proposed design
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