544 research outputs found
The Efficient Market Hypothesis, Price Multiples, And The German Stock Market
One of the great exercises of financial research is to examine the efficiency of the stock markets. There are many reasons for this endeavor. One is due to the importance efficiency has on the allocation of capital and the impact on economic activity. Others center on the desire to find an exploitable anomaly for active investment management. This paper sought to do both. The paper explores the German stock market over a five year period ending December 31, 2007. The objective was to examine the value of price multiples in developing portfolios that would not only question the efficient market hypothesis for the market but provide an investment tool to achieve above market risk adjusted returns for an active investment style. The paper explored this by creating portfolios of (1) top ranked (low) price multiples and (2) bottom ranked (high) price multiples. Three multiples were chosen. These were (1) Price to Book (PBK); (2) Price to Current Earnings (PEC), and (3) Price to Normalized Earnings (PER). The hypotheses were that low price multiples would outperform, on a risk adjusted basis, high price multiples, and hedged (long/short) would likewise outperform the market on a risk adjusted basis. Support for either of these hypotheses questions the efficiency of the markets and could provide a pragmatic investment strategy. The results of the study suggest not only that the efficiency of the German stock market can be questioned but that a workable investment strategy involving price multiples could be implemented. The results noted that low price multiples outperformed high price multiples in all cases but not necessarily on a risk adjusted basis. Hedged portfolios likewise outperformed the universe and population. Hedged PBK had an Adjusted Sharpe Ratio of 0.50; the Hedged PEC had an Adjusted Sharpe Ratio of 0.30; and the Hedged PER had an Adjusted Sharpe Ratio of 0.23. These should be compared against an Adjusted Sharpe Ratio for the market of 0. Finally, an equally-weighted Hedged position of PBK, PEC, and PER had an Adjusted Sharpe Ratio of 0.44.
Matrix-assisted ionisation in vacuum mass spectrometry and imaging on a modified quadrupole-quadrupole-time-of-flight mass spectrometer
Matrix-Assisted Ionisation in Vacuum (MAIV) is a new ionisation technique which ionises non-volatile compounds producing electrospray ionisation-like spectra. Its simple, matrix-assisted laser desorption/ionisation-like sample preparation allows for rapid analysis, with no requirement for external energy in the form of a laser or high voltage to produce ions. Ionisation occurs when the matrix (often 3-nitrobenzonitrile) is exposed to sub-ambient pressure. Here, the first use of this revolutionary new ionisation technique to image biological samples is reported. A commercial quadrupole-quadrupole-time-of-flight mass spectrometer was modified to incorporate control of the ion source pressure and a reduced sampling cone orifice diameter. In initial experiments, optimisation of source pressure and matrix composition was carried out to increase the longevity of ion formation. It was noted during these experiments that ion production was only observed when the sample was directly under the sampling cone. Optimisation of sample extraction into the MAIV matrix by the addition of 5 % chloroform enabled MAIV mass spectrometry imaging of lipids in rat brain sections to be carried out in raster imaging mode. Modification of the size and position of the sampling cone improved the selectivity obtainable in these images. Although the quality of these initial images is relatively poor, work is underway to improve the spatial resolution by further modification of the ion source and progress is reported
Blending video-reflexive ethnography with solution-focused approach: A strengths-based approach to practice improvement in health care
Professionals seldom discuss those things that go well-rather the focus is often on problems, poor outcomes, and what does not go well. Exnovation is about illuminating the invisible or hidden strengths of existing practices in order to improve practice and is central to the contemporary, qualitative elicitation method: video-reflexive ethnography (VRE). VRE is a method to explore and articulate the taken for granted by means of short video clips of one’s own work practice that provides a basis for sharing experiences, assumptions, questions, and concerns about the way things are done in order to effect practice improvement. Reflexivity is key to the method. The creation of a safe space for this shared reflexivity is essential. Improvement activities frequently draw upon problem-focused approaches that imply blame and fault. Such approaches can serve to close down discussion, give rise to anxiety, and inhibit the very improvements sought. In contrast, a strengths-based, solution-focused approach serves to create the safe place where shared practices, rather than individuals, are the center of attention. By focusing on what works well practitioners are encouraged to identify and build on existing strengths. A solution-focused approach used alongside VRE provides a scaffold for building improvement that is relevant to context. In this article, we discuss exnovation, the elicitation method of video-reflexivity, and the incorporation of a strengths-based solution-focused approach with VRE. We highlight the transformative and complementary qualities of these methods and draw upon practical examples from health care to demonstrate how they serve to strengthen and enhance each other
A systematic review of school-based sexual health interventions to prevent STI/HIV in sub-Saharan Africa
Background
The HIV/AIDS epidemic remains of global significance and there is a need to target (a) the adolescent age-groups in which most new infections occur; and (b) sub-Saharan Africa where the greatest burden of the epidemic lies. A focused systematic review of school-based sexual health interventions in sub-Saharan Africa to prevent HIV/AIDS and Sexually Transmitted Infections (STI) in this age group was therefore conducted.
Methods
Searches were conducted in Medline, Embase, Cinahl and PsychINFO according to agreed a priori criteria for studies published between 1986 and 2006. Further searches were conducted in UNAIDS and WHO (World Health Organization) websites, and 'Google'. Relevant journals were hand-searched and references cited in identified articles were followed up.
Data extraction and quality assessment was carried out on studies selected for full text appraisal, and results were analysed and presented in narrative format.
Results
Some 1,020 possible titles and abstracts were found, 23 full text articles were critically appraised, and 12 articles (10 studies) reviewed, reflecting the paucity of published studies conducted relative to the magnitude of the HIV epidemic in sub-Saharan Africa. Knowledge and attitude-related outcomes were the most associated with statistically significant change. Behavioural intentions were more difficult to change and actual behaviour change was least likely to occur. Behaviour change in favour of abstinence and condom use appeared to be greatly influenced by pre-intervention sexual history.
Conclusion
There is a great need in sub-Saharan Africa for well-evaluated and effective school-based sexual health interventions
Groundwater shapes sediment biogeochemistry and microbial diversity in a submerged Great Lake sinkhole
For a large part of earth’s history, cyanobacterial mats thrived in lowâ oxygen conditions, yet our understanding of their ecological functioning is limited. Extant cyanobacterial mats provide windows into the putative functioning of ancient ecosystems, and they continue to mediate biogeochemical transformations and nutrient transport across the sedimentâ water interface in modern ecosystems. The structure and function of benthic mats are shaped by biogeochemical processes in underlying sediments. A modern cyanobacterial mat system in a submerged sinkhole of Lake Huron (LH) provides a unique opportunity to explore such sedimentâ mat interactions. In the Middle Island Sinkhole (MIS), seeping groundwater establishes a lowâ oxygen, sulfidic environment in which a microbial mat dominated by Phormidium and Planktothrix that is capable of both anoxygenic and oxygenic photosynthesis, as well as chemosynthesis, thrives. We explored the coupled microbial community composition and biogeochemical functioning of organicâ rich, sulfidic sediments underlying the surface mat. Microbial communities were diverse and vertically stratified to 12Â cm sediment depth. In contrast to previous studies, which used lowâ throughput or shotgun metagenomic approaches, our highâ throughput 16S rRNA gene sequencing approach revealed extensive diversity. This diversity was present within microbial groups, including putative sulfateâ reducing taxa of Deltaproteobacteria, some of which exhibited differential abundance patterns in the mats and with depth in the underlying sediments. The biological and geochemical conditions in the MIS were distinctly different from those in typical LH sediments of comparable depth. We found evidence for active cycling of sulfur, methane, and nutrients leading to high concentrations of sulfide, ammonium, and phosphorus in sediments underlying cyanobacterial mats. Indicators of nutrient availability were significantly related to MIS microbial community composition, while LH communities were also shaped by indicators of subsurface groundwater influence. These results show that interactions between the mats and sediments are crucial for sustaining this hot spot of biological diversity and biogeochemical cycling.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136330/1/gbi12215_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136330/2/gbi12215.pd
Sedimentary pyrite sulfur isotope compositions preserve signatures of the surface microbial mat environment in sediments underlying low-oxygen cyanobacterial mats
The sedimentary pyrite sulfur isotope (delta S-34) record is an archive of ancient microbial sulfur cycling and environmental conditions. Interpretations of pyrite delta S-34 signatures in sediments deposited in microbial mat ecosystems are based on studies of modern microbial mat porewater sulfide delta S-34 geochemistry. Pyrite delta S-34 values often capture delta S-34 signatures of porewater sulfide at the location of pyrite formation. However, microbial mats are dynamic environments in which biogeochemical cycling shifts vertically on diurnal cycles. Therefore, there is a need to study how the location of pyrite formation impacts pyrite delta S-34 patterns in these dynamic systems. Here, we present diurnal porewater sulfide delta S-34 trends and delta S-34 values of pyrite and iron monosulfides from Middle Island Sinkhole, Lake Huron. The sediment-water interface of this sinkhole hosts a low-oxygen cyanobacterial mat ecosystem, which serves as a useful location to explore preservation of sedimentary pyrite delta S-34 signatures in early Earth environments. Porewater sulfide delta S-34 values vary by up to similar to 25 parts per thousand throughout the day due to light-driven changes in surface microbial community activity that propagate downwards, affecting porewater geochemistry as deep as 7.5 cm in the sediment. Progressive consumption of the sulfate reservoir drives delta S-34 variability, instead of variations in average cell-specific sulfate reduction rates and/or sulfide oxidation at different depths in the sediment. The delta S-34 values of pyrite are similar to porewater sulfide delta S-34 values near the mat surface. We suggest that oxidative sulfur cycling and other microbial activity promote pyrite formation in and immediately adjacent to the microbial mat and that iron geochemistry limits further pyrite formation with depth in the sediment. These results imply that primary delta S-34 signatures of pyrite deposited in organic-rich, iron-poor microbial mat environments capture information about microbial sulfur cycling and environmental conditions at the mat surface and are only minimally affected by deeper sedimentary processes during early diagenesis
Research on the Geography of Agricultural Change: Redundant or Revitalized?
Future research directions for agricultural geography were the subject of debate in Area in the late 1980s. The subsequent application of political economy ideas undoubtedly revived interest in agricultural research. This paper argues that agricultural geography contains greater diversity than the dominant political economy discourse would suggest. It reviews ‘other’ areas of agricultural research on policy, post-productivism, people, culture and animals, presenting future suggestions for research. They should ensure that agricultural research continues revitalized rather than redundant into the next millennium
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