Momentum profits and macroeconomic factors

This article tests whether macroeconomic variables and market sentiment influence the size of momentum profits. It finds that although returns to the winner and loser portfolios are influenced by a range of macroeconomic and market wide variables; momentum profits are influenced only by the scale of portfolio outflows. Thus, when investors are sending their capital elsewhere, reduced funds at home, dampen the profitability of the momentum trading strategy. It also finds that when the market closes, below its opening level in the previous six months, momentum profits are higher, which might be a reflection of mean reversion in the market. © 2004 Taylor and Francis Ltd.

Do external funds yield lower returns? Recent evidence from East Asian economies

One of the central explanations of the recent Asian Crisis has been the problem of moral hazard as the source of over-investment and excessive external borrowing. There is however rather limited firm-level empirical evidence to characterise inefficient use of internal and external finances. Using a large firm-level panel data-set from four badly affected Asian countries, this paper compares the rates of return to various internal and external funds among firms with low and high debt financing (relative to equity) among financially constrained and other firms. Selectivity-corrected estimates obtained from random effects panel data model do suggest evidence of significantly lower rates of return to long-term debt, even among firms relying more on debt relative to equity in our sample. There is also evidence that average effective interest rates often significantly exceeded the average returns to long-term debt in the sample countries in the pre-crisis period. © 2006 Elsevier Inc. All rights reserved.

Does move to market have an impact on earnings gap across gender? Some evidence from India

We use Indian National Sample Survey employment–unemployment data for the urban sector for the years 1987 and 1999. Our results indicate that the gender wage gap had narrowed considerably between these two years, for all earnings deciles and for all education cohorts. The narrowing of the earnings gap can be attributed largely to a sharp increase in the returns to the labour market experience of women.

Scaling up question-answering to linked data

Linked Data semantic sources, in particular DBpedia, can be used to answer many user queries. PowerAqua is an open multi-ontology Question Answering (QA) system for the Semantic Web (SW). However, the emergence of Linked Data, characterized by its openness, heterogeneity and scale, introduces a new dimension to the Semantic Web scenario, in which exploiting the relevant information to extract answers for Natural Language (NL) user queries is a major challenge. In this paper we discuss the issues and lessons learned from our experience of integrating PowerAqua as a front-end for DBpedia and a subset of Linked Data sources. As such, we go one step beyond the state of the art on end-users interfaces for Linked Data by introducing mapping and fusion techniques needed to translate a user query by means of multiple sources. Our first informal experiments probe whether, in fact, it is feasible to obtain answers to user queries by composing information across semantic sources and Linked Data, even in its current form, where the strength of Linked Data is more a by-product of its size than its quality. We believe our experiences can be extrapolated to a variety of end-user applications that wish to scale, open up, exploit and re-use what possibly is the greatest wealth of data about everything in the history of Artificial Intelligence. © 2010 Springer-Verlag.

R&D and productivity:using UK firm-level data to inform policy

The UK's business R&D (BERD) to GDP ratio is low compared to other leading economies, and the ratio has declined over the 1990s. This paper uses data on 719 large UK firms to analyse the link between R&D and productivity during 1989-2000. The results indicate that UK returns to R&D are similar to returns in other leading economies and have been relatively stable over the 1990s. The analysis suggests that the low BERD to GDP ratio in the UK is unlikely to be due to direct financial or human capital constraints (as these imply finding relatively high rates of return). © Springer Science+Business Media, LLC 2009.

An Approach to Wealth Modelling

2000 Mathematics Subject Classification: 60G48, 60G20, 60G15, 60G17. JEL Classification: G10

Returns on key accounts:do the results justify the expenditures?

Purpose – The use of key accounts has become a mature trend and most industrial firms use this concept in some form. Selling firms establish key account teams to attend to important customers and consolidate their selling activities. Yet, despite such increased efforts on behalf of key accounts, sufficient research has not quantified the returns on key account strategy nor has it firmly established performance differences between key and non-key accounts within a firm. In response to this shortcoming, this study aims to examine returns on key accounts. Design Methodology/approach – Data were collected from a global consulting firm. The data collection started two years after the implementation of the key account program. Data were collected on recently acquired customers (within the previous year) at two time periods: year 1 and year 3 (based on company access of data). Findings – Initially, key accounts perform as well or better than other types of accounts. However, in the long term, key accounts are less satisfied, less profitable and less beneficial for a firm’s growth than other types of accounts. Because the returns to key account expenditures, thus, appear mixed, firms should be cautious in expanding their key account strategies. Research limitations implications – The study contributes to research in three areas. First, most research on the effectiveness of key accounts refers to the between-firm level, whereas this study examines the effect within a single firm. Second, this study examines the temporal aspects of key accounts, namely, what happens to key accounts over time, in comparison with other accounts in a fairly large sample. Third, it considers the survival rates of key accounts versus other types of accounts. Practical implications – The authors suggest that firms also need to track their key accounts better because the results show that key accounts are less satisfied, less profitable and less beneficial for a firm’s growth than other types of accounts. Originality/value – Extant research has not examined these issues.

A túl- és az alulképzés bérhozama 25 európai országban (Returns for over-education and under-education for 25 European countries)

A tanulmányban 25 ország, kétezres évek közepi állapotot tükröző, reprezentatív keresztmetszeti mintáin egyrészt a Duncan-Hoffman-féle modellre támaszkodva megvizsgáljuk, hogy adatbázisunk milyen mértékben tükrözi az illeszkedés bérhozamával foglalkozó irodalom legfontosabb empirikus következtetéseit, másrészt - a Hartog- Oosterbeek-szerzőpáros által javasolt statisztikai próbák segítségével - azt elemezzük, hogy a becslések eredményei alapján mit mondhatunk Mincer emberitőke-, valamint Thurow állásversenymodelljének érvényességéről. Heckman szelekciós torzítást kiküszöbölő becslőfüggvényén alapuló eredményeink jórészt megerősítik az irodalomban vázolt legfontosabb empirikus sajátosságokat, ugyanakkor a statisztikai próbák az országok többségére nézve cáfolják mind az emberi tőke, mind az állásverseny modelljének empirikus érvényességét. / === / Using the Duncan–Hoffman model, the paper estimates returns for educational mismatch using comparable micro data for 25 European countries. The aim is to gauge the extent to which the main empirical regularities shown in other papers on the subject are confirmed by this data base. Based on tests proposed by Hartog and Oosterbeek, the author also considers whether the observed empirical patterns accord with the Mincerian basic human-capital model and Thurow's job-competition model. Heckman's sample-selection estimator shows the returns to be fairly consistent with those found in the literature; the job-competition model and the Mincerian human-capital model can be rejected for most countries.

The commercial bark harvest of the African cherry (Prunus africana) on Mount Oku, Cameroon: Effects on traditional uses and population dynamics

Bark extracts of the African cherry (Prunus africana) are used to treat benign prostatic hyperplasia. This study examined the effects of commercial bark harvest on population dynamics in the Kilum-Ijim Forest Preserve on Mount Oku, Cameroon and on traditional uses. P. africana is valued for its timber and as fuel although its greatest value is as a traditional medicine for human and animal ailments. Harvest has depleted the resource and has eroded traditional forest protection practices. I constructed matrix models to examine the effects of bark harvest on population structure and on population dynamics in harvested and unharvested populations. Harvesting simulations examined the effect on the population growth rate (λ) with differing levels of mortality of harvest-sized and large trees and differing harvest frequencies. Size class frequencies for the entire forest decreased in a reverse j-shaped curve, indicating adequate recruitment in the absence of harvest. Individual plots showed differences from the overall forest data, suggesting effects of natural and man-made perturbations, particularly due to bark harvest. One plot (harvested in the 1980s) showed a temporal difference in λ and fluctuated around one, due to alternating high and low fruiting years; other unharvested plots showed smaller temporal differences. Harvested plots (harvested illegally in 1997) had values of λ less than one and showed small temporal differences. The control plot also showed λ less than one, due to poor recruitment in the closed canopy forest. The value of λ for the combined data was 0.9931 suggesting a slightly declining population. The elasticity matrix for the combined data indicated the population growth rate was most sensitive to the survival of the large reproductive trees (42.5% of the elasticity). In perturbation analyses, reducing the survival of the large trees caused the largest reductions in λ. Simulations involving harvesting frequency indicated λ returns to pre-harvest conditions if trees are re-harvested after 10–15 years, but only if the large trees are left unharvested. Management scenarios suggest harvest can be sustainable if seedlings and small saplings are planted in the forest and actively managed, although large-scale plantations may be the only feasible option to meet market demand. ^

Predicting Forest Responses to Changing Environmental Conditions

Forests change with changes in their environment based on the physiological responses of individual trees. These short-term reactions have cumulative impacts on long-term demographic performance. For a tree in a forest community, success depends on biomass growth to capture above- and belowground resources and reproductive output to establish future generations. Here we examine aspects of how forests respond to changes in moisture and light availability and how these responses are related to tree demography and physiology.

First we address the long-term pattern of tree decline before death and its connection with drought. Increasing drought stress and chronic morbidity could have pervasive impacts on forest composition in many regions. We use long-term, whole-stand inventory data from southeastern U.S. forests to show that trees exposed to drought experience multiyear declines in growth prior to mortality. Following a severe, multiyear drought, 72% of trees that did not recover their pre-drought growth rates died within 10 years. This pattern was mediated by local moisture availability. As an index of morbidity prior to death, we calculated the difference in cumulative growth after drought relative to surviving conspecifics. The strength of drought-induced morbidity varied among species and was correlated with species drought tolerance.

Next, we investigate differences among tree species in reproductive output relative to biomass growth with changes in light availability. Previous studies reach conflicting conclusions about the constraints on reproductive allocation relative to growth and how they vary through time, across species, and between environments. We test the hypothesis that canopy exposure to light, a critical resource, limits reproductive allocation by comparing long-term relationships between reproduction and growth for trees from 21 species in forests throughout the southeastern U.S. We found that species had divergent responses to light availability, with shade-intolerant species experiencing an alleviation of trade-offs between growth and reproduction at high light. Shade-tolerant species showed no changes in reproductive output across light environments.

Given that the above patterns depend on the maintenance of transpiration, we next developed an approach for predicting whole-tree water use from sap flux observations. Accurately scaling these observations to tree- or stand-levels requires accounting for variation in sap flux between wood types and with depth into the tree. We compared different models with sap flux data to test the hypotheses that radial sap flux profiles differ by wood type and tree size. We show that radial variation in sap flux is dependent on wood type but independent of tree size for a range of temperate trees. The best-fitting model predicted out-of-sample sap flux observations and independent estimates of sapwood area with small errors, suggesting robustness in new settings. We outline a method for predicting whole-tree water use with this model and include computer code for simple implementation in other studies.

Finally, we estimated tree water balances during drought with a statistical time-series analysis. Moisture limitation in forest stands comes predominantly from water use by the trees themselves, a drought-stand feedback. We show that drought impacts on tree fitness and forest composition can be predicted by tracking the moisture reservoir available to each tree in a mass balance. We apply this model to multiple seasonal droughts in a temperate forest with measurements of tree water use to demonstrate how species and size differences modulate moisture availability across landscapes. As trees deplete their soil moisture reservoir during droughts, a transpiration deficit develops, leading to reduced biomass growth and reproductive output.

This dissertation draws connections between the physiological condition of individual trees and their behavior in crowded, diverse, and continually-changing forest stands. The analyses take advantage of growing data sets on both the physiology and demography of trees as well as novel statistical techniques that allow us to link these observations to realistic quantitative models. The results can be used to scale up tree measurements to entire stands and address questions about the future composition of forests and the land’s balance of water and carbon.

A comparative study: long and short term effect of a nutrition sensitive approach to delay the progression of HIV to AIDS among people living with HIV (PLWH) in Nigeria

Background: Malnutrition has a negative impact on optimal immune function, thus increasing susceptibility to morbidity and mortality among HIV positive patients. Evidence indicates that the prevalence of macro and micronutrient deficiencies (particularly magnesium, selenium, zinc, and vitamin C) has a negative impact on optimal immune function, through the progressive depletion of CD4 T-lymphocyte cells, which thereby increases susceptibility to morbidity and mortality among PLWH. Objective: To assess the short and long term effects of a nutrition sensitive intervention to delay the progression of human immune-deficiency virus (HIV) to AIDS among people living with HIV in Abuja, Nigeria. Methods: A randomized control trial was carried out on 400 PLWH (adult, male and female of different religious background) in Nigeria between January and December 2012. Out of these 400 participants, 100 were randomly selected for the pilot study, which took place over six months (January to June, 2012). The participants in the pilot study overlapped to form part of the scale-up participants (n 400) monitored from June to December 2012. The comparative effect of daily 354.92 kcal/d optimized meals consumed for six and twelve months was ascertained through the nutritional status and biochemical indices of the study participants (n=100 pilot interventions), who were and were not taking the intervention meal. The meal consisted of: Glycine max 50g (Soya bean); Pennisetum americanum 20g (Millet); Moringa oleifera 15g (Moringa); Daucus carota spp. sativa 15g (Carrot). Results: At the end of sixth month intervention, mean CD4 cell count (cell/mm3) for Pre-ART and ART Test groups increased by 6.31% and 12.12% respectively. Mean mid upper arm circumference (MUAC) for Pre-ART and ART Test groups increased by 2.72% and 2.52% within the same period (n 400). Comparatively, participants who overlapped from pilot to scale-up intervention (long term use, n 100) were assessed for 12 months. Mean CD4 cell count (cell/mm3) for Pre-ART and ART test groups increased by 2.21% and 12.14%. Mean MUAC for Pre-ART and ART test groups increased by 2.08% and 3.95% respectively. Moreover, student’s t-test analysis suggests a strong association between the intervention meal, MUAC, and CD4 count on long term use of optimized meal in the group of participants being treated with antiretroviral therapy (ART) (P<0.05). Conclusion: Although the achieved results take the form of specific technology, it suggests that a prolong consumption of the intervention meal will be suitable to sustain the gained improvements in the anthropometric and biochemical indices of PLWHIV in Nigeria.

Gendered Responses to Global Crisis: Circular Migration and Return among Ecuadorian Families in Spain and Ecuador

This paper analyzes the impact of Spain’s economic crisis on social reproduction strategies of Ecuadorian migrant families in Madrid and Quito. The paper analyzes circular migration experiences and more permanent returns to Ecuador. I argue that these strategies and migrants' greater or lesser capabilities to move between different migration destinations show significant gender differences. On the one hand, men and women make a differential use of their migratory status to deploy transnational strategies and expand their mobility. On the other hand, migrants’ degree of mobility and flexibility with regard to the labor market and transnational social reproduction are derivative of a specific gendered order and sexual division of labor.

A simple approach to the supernova progenitor–explosion connection

We present a new approach to understand the landscape of supernova explosion energies, ejected nickel masses, and neutron star birth masses. In contrast to other recent parametric approaches, our model predicts the properties of neutrino-driven explosions based on the pre-collapse stellar structure without the need for hydrodynamic simulations. The model is based on physically motivated scaling laws and simple differential equations describing the shock propagation, the contraction of the neutron star, the neutrino emission, the heating conditions, and the explosion energetics. Using model parameters compatible with multi-D simulations and a fine grid of thousands of supernova progenitors, we obtain a variegated landscape of neutron star and black hole formation similar to other parametrized approaches and find good agreement with semi-empirical measures for the ‘explodability’ of massive stars. Our predicted explosion properties largely conform to observed correlations between the nickel mass and explosion energy. Accounting for the coexistence of outflows and downflows during the explosion phase, we naturally obtain a positive correlation between explosion energy and ejecta mass. These correlations are relatively robust against parameter variations, but our results suggest that there is considerable leeway in parametric models to widen or narrow the mass ranges for black hole and neutron star formation and to scale explosion energies up or down. Our model is currently limited to an all-or-nothing treatment of fallback and there remain some minor discrepancies between model predictions and observational constraints.

Leverage, Volatile Future Earnings Growth and Expected Stock Returns

We provide theory and evidence to complement Choi's [RFS, 2013] important new insights on the returns to equity in `value' firms. We show that higher future earnings growth ameliorates the value-reducing effect of leverage and, because the market for earnings is incomplete, reduces the earnings-risk sensitivity of the default option. Ceteris paribus, a levered firm with low (high) earnings growth is more sensitive to the first (second) of these effects thus generating higher (lower) expected returns. We demonstrate this by modeling equity as an Asian-style call option on net earnings and find significant empirical support for our hypotheses.

A petrographic investigation into the durability of common replacement sandstones to the crystallisation of de-icing salts

Scottish sandstone buildings are now suffering the long-term effects of salt-crystallisation damage, owing in part to the repeated deposition of de-icing salts during winter months. The use of de-icing salts is necessary in order to maintain safe road and pavement conditions during cold weather, but their use comes at a price. Sodium chloride (NaCl), which is used as the primary de-icing salt throughout the country, is a salt known to be damaging to sandstone masonry. However, there remains a range of alternative, commercially available de-icing salts. It is unknown however, what effect these salts have on porous building materials, such as sandstone. In order to protect our built heritage against salt-induced decay, it is vital to understand the effects of these different salts on the range of sandstone types that we see within the historic buildings of Scotland. Eleven common types of sandstone were characterised using a suite of methods in order to understand their mineralogy, pore structure and their response to moisture movement, which are vital properties that govern a stone’s response to weathering and decay. Sandstones were then placed through a range of durability tests designed to measure their resistance to various weathering processes. Three salt crystallisation tests were undertaken on the sandstones over a range of 16 to 50 cycles, which tested their durability to NaCl, CaCl2, MgCl2 and a chloride blend salt. Samples were primarily analysed by measuring their dry weight loss after each cycle, visually after each cycle and by other complimentary methods in order to understand their changing response to moisture uptake after salt treatment. Salt crystallisation was identified as the primary mechanism of decay across each salt, with the extent of damage in each sandstone influenced by environmental conditions and pore-grain properties of the stone. Damage recorded in salt crystallisation tests was ultimately caused by the generation of high crystallisation pressures within the confined pore networks of each stone. Stone and test-specific parameters controlled the location and magnitude of damage, with the amount of micro-pores, their spatial distribution, the water absorption coefficient and the drying efficiency of each stone being identified as the most important stone-specific properties influencing salt-induced decay. Strong correlations were found between the dry weight loss of NaCl treated samples and the proportion of pores <1µm in diameter. Crystallisation pressures are known to scale inversely with pore size, while the spatial distribution of these micro-pores is thought to influence the rate, overall extent and type of decay within the stone by concentrating crystallisation pressures in specific regions of the stone. The water absorption determines the total amount of moisture entering into the stone, which represents the total amount of void space for salt crystallisation. The drying parameters on the other hand, ultimately control the distribution of salt crystallisation. Those stones that were characterised by a combination of a high proportion of micro-pores, high water absorption values and slow drying kinetics were shown to be most vulnerable to NaCl-induced decay. CaCl2 and MgCl2 are shown to have similar crystallisation behaviour, forming thin crystalline sheets under low relative humidity and/or high temperature conditions. Distinct differences in their behaviour that are influenced by test specific criteria were identified. The location of MgCl2 crystallisation close to the stone surface, as influenced by prolonged drying under moderate temperature drying conditions, was identified as the main factor that caused substantial dry weight loss in specific stone types. CaCl2 solutions remained unaffected under these conditions and only crystallised under high temperatures. Homogeneous crystallisation of CaCl2 throughout the stone produced greater internal change, with little dry weight loss recorded. NaCl formed distinctive isometric hopper crystals that caused damage through the non-equilibrium growth of salts in trapped regions of the stone. Damage was sustained as granular decay and contour scaling across most stone types. The pore network and hydric properties of the stones continually evolve in response to salt crystallisation, creating a dynamic system whereby the initial, known properties of clean quarried stone will not continually govern the processes of salt crystallisation, nor indeed can they continually predict the behaviour of stone to salt-induced decay.