Purpose -One of the implications of Islamic investment principles is the availability of Islamic financial instruments in the financial market. The main aim of this research is to observe the differences in terms of performance between Islamic and conventional mutual fund in the context of Malaysian capital market. Design/methodology/approach -To achieve the major objectives of this paper standard methods wereused for evaluating the mutual funds performance, for example, Sharpe index and adjusted Sharpe index, Jensen Alpha, Timing and selectivity ability. The scope of the paper is to measure the relative quantitative performance of funds which was managed based on two different approaches. Findings -The basic finding of the paper is that Islamic funds performed better than the conventional funds during bearish economic trends while, conventional funds showed better performance than Islamic funds during bullish economic conditions. In addition to that finding, both conventional and Islamic funds were unable to achieve at least 50 per cent market diversification levels, though conventional funds are found to have a marginally better diversification level than the Islamic funds. The results also suggest that fund managers are unable to correctly identify good bargain stocks and to forecast the price movements of the general market.Research limitations/implications -The main limitation is that the samples of conventional and Islamic mutual funds were from one developing market. The findings could be better validated if the sample included the mutual funds from other developed and developing economies, where both Islamic and conventional funds are available. Practical implications -The findings suggest that having Islamic mutual funds in an investment portfolio helps to hedge the downside risk in an adverse economic situation. Originality/value -So far there is no published evidence on the relative performance of Islamic and conventional mutual funds in Malaysia as well as other developing countries. Therefore, this paper adds new knowledge to the mutual funds literature.
Purpose: This paper aims to investigate the differences in mean cost, revenue and profit efficiency scores of conventional versus Islamic banks. It also aims to examine the effect of size and age on cost, revenue and profit efficiency of the sampled banks.Design/methodology/approach: This study evaluates a cross-country level data compiled from the financial statements of 40 banks in 11 Organisation of Islamic Conference (OIC) countries over the period 1990-2005. The data were collected for each year available from the BankScope database. The DEA nonparametric efficiency approach originally developed by Farrell was applied to analyse the data.Findings: The findings suggest no significant differences between the overall efficiency of conventional and Islamic banks. However, it was noted that, on average, banks are more efficient in using their resources compared to their ability to generate revenues and profits. The average bank lost an opportunity to receive 27.9 percent more revenue, given the same amount of resources. Similarly, the average bank lost the opportunity to make 20.9 percent more profits utilising the same level of inputs. Clearly there is substantial room for improvement in cost minimisation and revenue and profit maximisation in both banking systems. The size and age factor did not significantly influence the efficiency scores in both banking streams.Originality/value: This research is substantially different from the prior work in this area in three main ways. First, it investigates cost, revenue, and profit efficiency, whereas previous studies focus on cost, profit, or cost and profit efficiency. Also, no previous studies have compared conventional and Islamic banks. Second, this study distinguishes differences among big versus small, and old versus new banks, which allows more detailed insights on the efficiency issue. Third, the age issue in Islamic banks has been addressed, so far undocumented.
Abstract. By regulating the global transport of heat, freshwater, and carbon, the Atlantic meridional overturning circulation (AMOC) serves as an important component of the climate system. During the late 20th and early 21st centuries, indirect observations and models suggest a weakening of the AMOC. Direct AMOC observations also suggest a weakening during the early 21st century but with substantial interannual variability. Long-term weakening of the AMOC has been associated with increasing greenhouse gases (GHGs), but some modeling studies suggest the build up of anthropogenic aerosols (AAs) may have offset part of the GHG-induced weakening. Here, we quantify 1900–2020 AMOC variations and assess the driving mechanisms in state-of-the-art climate models from the Coupled Model Intercomparison Project phase 6 (CMIP6). The CMIP6 forcing (GHGs, anthropogenic and volcanic aerosols, solar variability, and land use and land change) multi-model mean shows negligible AMOC changes up to ∼ 1950, followed by robust AMOC strengthening during the second half of the 20th century (∼ 1950–1990) and weakening afterwards (1990–2020). These multi-decadal AMOC variations are related to changes in North Atlantic atmospheric circulation, including an altered sea level pressure gradient, storm track activity, surface winds, and heat fluxes, which drive changes in the subpolar North Atlantic surface density flux. To further investigate these AMOC relationships, we perform a regression analysis and decompose these North Atlantic climate responses into an anthropogenic aerosol-forced component and a subsequent AMOC-related feedback. Similar to previous studies, CMIP6 GHG simulations yield robust AMOC weakening, particularly during the second half of the 20th century. Changes in natural forcings, including solar variability and volcanic aerosols, yield negligible AMOC changes. In contrast, CMIP6 AA simulations yield robust AMOC strengthening (weakening) in response to increasing (decreasing) anthropogenic aerosols. Moreover, the CMIP6 all-forcing AMOC variations and atmospheric circulation responses also occur in the CMIP6 AA simulations, which suggests these are largely driven by changes in anthropogenic aerosol emissions. More specifically, our results suggest that AMOC multi-decadal variability is initiated by North Atlantic aerosol optical thickness perturbations to net surface shortwave radiation and sea surface temperature (and hence sea surface density), which in turn affect sea level pressure gradient and surface wind and – via latent and sensible heat fluxes – sea surface density flux through its thermal component. AMOC-related feedbacks act to reinforce this aerosol-forced AMOC response, largely due to changes in sea surface salinity (and hence sea surface density), with temperature-related (and cloud-related) feedbacks acting to mute the initial response. Although aspects of the CMIP6 all-forcing multi-model mean response resembles observations, notable differences exist. This includes CMIP6 AMOC strengthening from ∼ 1950 to 1990, when the indirect estimates suggest AMOC weakening. The CMIP6 multi-model mean also underestimates the observed increase in North Atlantic ocean heat content, and although the CMIP6 North Atlantic atmospheric circulation responses – particularly the overall patterns – are similar to observations, the simulated responses are weaker than those observed, implying they are only partially externally forced. The possible causes of these differences include internal climate variability, observational uncertainties, and model shortcomings, including excessive aerosol forcing. A handful of CMIP6 realizations yield AMOC evolution since 1900 similar to the indirect observations, implying the inferred AMOC weakening from 1950 to 1990 (and even from 1930 to 1990) may have a significant contribution from internal (i.e., unforced) climate variability. Nonetheless, CMIP6 models yield robust, externally forced AMOC changes, the bulk of which are due to anthropogenic aerosols.
Absorbing aerosols, like black carbon (BC), give rise to rapid adjustments, and the associated perturbation to the atmospheric temperature structure alters the cloud distribution. The level of scientific understanding of these rapid cloud adjustmentsotherwise known as semi-direct effects (SDEs)-is considered low, with models indicating a likely negative (−0.44 to +0.1 Wm −2) forcing. Recent studies suggest this negative SDE is primarily driven by decreases in high-level clouds and enhanced longwave cooling. Here, we investigate the SDE using multiple models driven by observationally constrained fine-mode aerosol forcing without dust and sea salt. Unlike aerosol simulations, which yield a relatively vertically uniform aerosol atmospheric heating profile with significant upper-tropospheric heating, observation-based heating peaks in the lower-troposphere and then decays to zero in the mid-troposphere. We find a significant global annual mean decrease in low-and mid-level clouds, and weaker decreases in high-level clouds, which leads to a positive SDE dominated by shortwave radiation. Thus, in contrast to most studies, we find a robust positive SDE, implying cloud adjustments act to warm the climate system. Sensitivity tests with identical average, but vertically uniform observationally constrained aerosol atmospheric heating result in a negative SDE, due to enhanced longwave cooling as a result of large reductions in high-level clouds. Our results therefore suggest that model simulations lead to a negatively biased SDE, due to an aerosol atmospheric heating profile that is too vertically uniform.
Objective and Aims. In the last two decades, fine-needle aspiration cytology (FNAC) of thyroid has been introduced as the most reliable and cost-effective method for diagnosing of clinically important thyroid disorders. The aim of our study was to determine the accuracy and reliability of FNAC in our center. Materials and Methods. Thyroid fine-needle aspiration cytology (FNAC) of 1639 patients from October 2007 to September 2011 was evaluated in our center. Only patients which had a solitary or multiple thyroid nodules were selected for FNA. The FNAC results are classified as benign, malignant, suspicious, and unsatisfactory. From above patients, 192 (11.7%) cases underwent surgery, and histopathologic examination was performed. By comparing the FNAC reports with the corresponding histopathologic results, the accuracy of thyroid FNAC was determined. Results. According to FNAC diagnostic criteria, there were 1054 (64.3%) benign cases, 128 (7.8%) malignant, 306 (18.66%) suspicious and 151 (9.2%) inadequate for diagnosis. In 192 cases, which underwent surgery, FNAC reports were compared with histopathologic results and statistical indices were calculated. The sensitivity, specificity, and accuracy were 91.6%, 100%, and 97%, respectively. These findings strongly support that FNAC as a useful technic for preoperative diagnosis of thyroid lesions. Conclusion. This technique is easy to perform, cost effective, minimally invasive with few complications. FNAC has high sensitivity in diagnosis of thyroid malignancy and also has high diagnostic accuracy in the evaluation of thyroid disorders.
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