18,880 research outputs found
The Relationship Between the Random Walk of the Returns of Financial Market Indices and Market Efficiency: an Analytical Study of the Indicators of a Sample of Arab Financial Markets
Purpose:Â The aim of this article is to study focused through the sample that was selected for the Arab financial markets (Iraq, Kuwait, Dubai) on testing the behavior of the returns of the stock indices for the sample to verify whether they follow the random walk or not.
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Theoretical framework: The concept of financial market indices and market efficiency was considered as a  complex multi-tiered system. theory of capital markets functioning were employed in the study.
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Design/methodology/approach: Â At the weak level, the research dealt with the returns of the daily market indices during the period from January 5/2021 to December 1, 2021.
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Findings: through the use of three tests, which are to test the normal distribution of the studied observations using the test (Kolmogorov-Smirnov test), and the time-series stability test (Stationary), which is known as the unit root test through the use of the modified Dickey-Fuller Test, and the serial self-correlation test (Q-Stat) as part of the financial markets efficiency test.which means that the conscious investor can benefit from achieving extraordinary returns in those markets.
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Research, Practical & Social implications: We suggest a future research agenda and highlight the contributions made to executive and financial market.
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Originality/value: Â The research concluded that the random movement hypothesis was accepted, and that the stock indices reflect all the historical information in the researched markets, and then the efficiency of the studied markets at the weak level.
Long-term zooplankton dynamics in Lake TaupĆ: 2000-2020
Long-term monitoring is essential for distinguishing between natural and anthropogenically induced changes within ecosystems, particularly those with high degrees of natural fluctuation. In order to gain further understanding of the links between physical, chemical and biotic factors, zooplankton have been highlighted as useful bioindicators within aquatic ecosystems. Long-term zooplankton monitoring studies have been utilized to highlight changes in lake trophic state, changes within catchments, fisheries practices and invasions.
Lake TaupĆ, New Zealandâs largest lake, has been subject to a long-term monitoring programme by NIWA since 1994, commissioned by the Waikato Regional Council, with the primary purpose of detecting changes in the lakeâs trophic state through time. Since January 2000, the monitoring programme has included biweekly zooplankton sampling; no results of this have yet been published. The purpose of my research was to assess if there have been any significant changes in the zooplankton community composition over the monitoring period (2000-2020), with a particular focus on the last 12 years of data (2009-2020), and determine the importance of measured environmental variables in influencing changes in the zooplankton community composition.
Lake TaupĆ was assessed as microtrophic to oligotrophic throughout the monitoring period (Trophic Level Index (TLI) between 1.5 and 2.9), and there were no significant linear changes in any of the measured environmental variables (R-squared values all 0.05). The zooplankton data was separated into two separate datasets; a shorter February 2009 â December 2020 dataset with samples analysed entirely by myself, and a longer January 2000-December 2020 dataset, with earlier samples analysed by NIWA, utilising a lower taxonomic resolution.
Multivariate analyses (nMDS and ANOSIM) indicated significant differences among three yearly groups of zooplankton data within both the shorter (Global R statistic = 0.179, p = 0.014) and longer dataset (Global R statistic = 0.353, p = 0.001). Time and temperature were inferred by Redundancy Analysis (RDA) as the most important environmental variables associated with change in zooplankton community composition in both the shorter 2009-2020 (Lambda-A = 0.08 for both, p = 0.002 for both) and longer 2000-2020 datasets (Lambda-A = 0.15, p = 0.002 for time, and Lambda-A = 0.06, p = 0.002 for temperature). Both ordinations indicated that changes associated with time (long-term) and changes in temperature were primarily unrelated. Changes in zooplankton community composition influenced by temperature were attributed to seasonal succession.
Zooplankton community composition differed between the beginning and end of the monitoring periods in both datasets. However, the direction of the community change seemingly reversed around 2009-2011, with assemblages late in the study reverting to communities similar to those observed earlier in the study. Decreases in the native large Daphnia thomsoni and increased importance of the non-native Daphnia galeata indicate that colonisation by the invading species has influenced the observed changes in zooplankton community composition. The influences of top-down control in the form of predation on the zooplankton community by fish (an unmeasured variable) may have also influenced communities, with shifts from large- to small-sized species observed. Rotifers indicative of both low and high TLI are present throughout the study (e.g., Polyarthra dolichoptera and Keratella cochlearis respectively), but the community is dominated throughout by species indicative of low trophic state (e.g., Conochiloides dossuarius), which is consistent with previous zooplankton studies within Lake TaupĆ. Continued monitoring of zooplankton, physical and chemical lake properties, algae, and bacteria is advised, with the inclusion of fish monitoring recommended
Movers and shakers: exploring the complex dynamics of aquatic biological invasions
Human-mediated introductions of non-native species have provoked innumerable biological invasions, which can have a suite of adverse effects on the communities into which they are introduced. Despite extensive research, there remains a need in invasion ecology for simple methods of predicting how an introduced species will spread and become established. While I predicted that spread can be modelled simply using the characteristics of the invading population, establishment should be explained by the characteristics of the receiving ecosystem. Using the brown trout (Salmo trutta) invasion on the Island of Newfoundland as a case study, I fit a reaction-diffusion model to brown trout population data to predict expected spread and test these predictions against extensive occurrence data. I use statistical models to test the influence of a suite of environmental variables on the establishment of brown trout within the invasion range. I find that observed spread in Newfoundland is slow compared to invasions elsewhere and that two landscape environmental variables show evidence of explaining establishment patterns, but their influence is likely moderated by other factors. My study contextualises the mechanisms contributing to slow aquatic invasions, revealing that studies need to integrate a variety of methods to elucidate the processes governing biological invasions
TOWARDS AN UNDERSTANDING OF EFFORTFUL FUNDRAISING EXPERIENCES: USING INTERPRETATIVE PHENOMENOLOGICAL ANALYSIS IN FUNDRAISING RESEARCH
Physical-activity oriented community fundraising has experienced an exponential growth in popularity over the past 15 years. The aim of this study was to explore the value of effortful fundraising experiences, from the point of view of participants, and explore the impact that these experiences have on peopleâs lives. This study used an IPA approach to interview 23 individuals, recognising the role of participants as proxy (nonprofessional) fundraisers for charitable organisations, and the unique organisation donor dynamic that this creates. It also bought together relevant psychological theory related to physical activity fundraising experiences (through a narrative literature review) and used primary interview data to substantiate these. Effortful fundraising experiences are examined in detail to understand their significance to participants, and how such experiences influence their connection with a charity or cause. This was done with an idiographic focus at first, before examining convergences and divergences across the sample. This study found that effortful fundraising experiences can have a profound positive impact upon community fundraisers in both the short and the long term. Additionally, it found that these experiences can be opportunities for charitable organisations to create lasting meaningful relationships with participants, and foster mutually beneficial lifetime relationships with them. Further research is needed to test specific psychological theory in this context, including self-esteem theory, self determination theory, and the martyrdom effect (among others)
Quantifying the Indirect Effect of Wolves on Aspen in Northern Yellowstone National Park: Evidence for a Trophic Cascade?
Yellowstone National Park is renowned for its incredible wildlife, and perhaps the most famous of these species is the gray wolf, which was reintroduced to the Park in the mid-1990s. After reintroduction, it was highly publicized by scientists, journalists, and environmentalists that the wolf both decreased elk density and changed elk behavior in a way that reduced elk effects on plants, a process known as a âtrophic cascade.â Aspen, which is eaten by elk in winter, is one species at the forefront of Yellowstone trophic cascade research because it has been in decline across the Park for over a century. However, due to the challenges of measuring trophic cascades, there is continued uncertainty regarding the effects of wolves on aspen in northern Yellowstone. Thus, the purpose of my dissertation was to provide a comprehensive test of a trophic cascade in this system. Specifically, I used 20 years of data on aspen, elk, and wolves in Yellowstone to: 1) clarify annual trends in browsing and height of young aspen (a proxy for regeneration) after wolf reintroduction, 2) assess the influence of wolves scaring elk on aspen (âtrait-mediated indirect effectsâ), and 3) evaluate the effect of wolves killing elk on aspen (âdensity-mediated indirect effectsâ).
My research suggests that wolves indirectly contributed to increased aspen over story recruitment following their reintroduction by helping to reduce the elk population size, but elk response to the risk of wolf predation did not reduce elk foraging in a way that measurably increased aspen recruitment. Additionally, hunter harvest of elk north of the park was twice as important as wolf predation in causing increased aspen recruitment. However, despite wolves and hunters limiting elk abundance, it is still uncommon for young aspen to grow past peak browsing height (120-cm), indicating that many stands remain vulnerable to elk herbivory nearly 30 years after wolf reintroduction. These results highlight that the strength and mechanism of predator effects on plant communities are context-specific. Thus, using predator reintroduction as a tool for ecosystem restoration without considering the many factors that shape trophic cascades may result in different management and conservation outcomes than intended
The effect of breached relay ramp structures on deepâlacustrine sedimentary systems
Fault relay ramps are important sediment delivery points along rift margins and often provide persistent flow pathways in deepwater sedimentary basins. They form as tilted rock volumes between en-echelon fault segments, which become modified through progressive deformation, and may develop through-going faults that âbreachâ the relay ramp. It is well established that hinterland drainage (fluvial/alluvial systems) is greatly affected by the presence of relay ramps at basin margins. However, the impact on deepwater (deep-marine/lacustrine) subaqueous sediment gravity flow processes, particularly by breached relay ramps, is less well documented. To better evaluate the complex geology of breached relay settings, this study examines a suite of high-quality subsurface data from the Early Cretaceous deep-lacustrine North Falkland Basin (NFB). The Isobel Embayment breached relay-ramp, an ideal example, formed during the syn-rift and was later covered by a thick transitional and early post-rift succession. Major transitional and early post-rift fan systems are observed to have consistently entered the basin at the breached relay location, directed through a significant palaeo-bathymetric low associated with the lower, abandoned ramp of the structure. More minor systems also entered the basin across the structure-bounding fault to the north. Reactivation of basin-bounding faults is shown by the introduction of new point sources along its extent. This study shows the prolonged influence of margin-located relay ramps on sedimentary systems from syn-rift, transitional and into the early post-rift phase. It suggests that these structures can become reactivated during post-rift times, providing continued control on deposition and sourcing of overlying sedimentary systems. Importantly, breached relays exert control on fan distribution, characterised by laterally extensive lobes sourced by widespread feeder systems, and hanging walls settings by small-scale lobes, with small, often line-sourced feeders. Further characterising the likely sandstone distribution in these structurally complex settings is important as these systems often form attractive hydrocarbon reservoirs
The Adirondack Chronology
The Adirondack Chronology is intended to be a useful resource for researchers and others interested in the Adirondacks and Adirondack history.https://digitalworks.union.edu/arlpublications/1000/thumbnail.jp
Monsoonal Precipitation in a Model Hierarchy: Impact of Continental Geometry and Global Warming
Monsoon systems around the world vary in their onset timing and precipitation spatial extent, suggesting that continental geometry could play an important role in differentiating between different monsoons systems. Since over half the world's population is dependent on monsoonal precipitation, it is of crucial importance to understand what controls the strength, seasonal evolution, and spatial extent of the tropical circulation and its associated precipitation and how they will evolve in a warmer climate. Recent studies suggest that individual monsoon regions will respond differently to climate change, highlighting the potential influence continental geometry may have on the current and future monsoon. In this thesis, we study the response of monsoonal precipitation, in its precipitation intensity, pattern, and onset timing, to idealized continent and climate change using a model hierarchy. By progressively building up complexity, we can gain insight from the idealized cases to determine responsible mechanisms in the responses to warming found in individual monsoon regions within the full general circulation models (GCMs).
First, we study the influence of continental geometry on the timing and spatial distribution of monsoonal precipitation under our current climate using an idealized aquaplanet model run with different zonally symmetric configurations of Northern Hemispheric land. We show that having continent extending to the tropical latitudes is necessary to generate monsoons that feature a rapid migration of the convergence zone over the continent, similar to observed monsoons. Without these regions, the tropical circulation is not able to rapidly transition into an angular momentum conserving monsoon regime. Next, we focus only on the effect of climate warming on the monsoon by using a set of idealized aquaplanet simulations with uniform mixed-layer depth, run with different atmospheric longwave optical depths to simulate a large range of both colder and warmer climates than the current climate. We show that as the climate warms, during the spring the atmospheric energy storage increases, which compensates the thermal forcing and allows for the tropical circulation transitions to be delayed, resulting in a delay in monsoon onset. Furthermore, we find that in extremely warm climates, the compensating effect of the energy storage is limited due to complex changes in the surface temperature seasonality. As a result, eventually the monsoon onset delay with warming saturates. These results highlight the important role the surface, both in its physical conditions and energy balance, has on setting the monsoon.</p
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