| 1. |
- Abdullah, Muhammad Imran, et al.
(författare)
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Quantum Chemical Designing of Efficient Sensitizers for Dye Sensitized Solar Cells
- 2013
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Ingår i: Bulletin of the Korean Chemical Society (Print). - : Korean Chemical Society. - 0253-2964 .- 1229-5949. ; 34:7, s. 2093-2098
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Tidskriftsartikel (refereegranskat)abstract
- Density functional theory (DFT) was used to determine the ground state geometries of indigo and new design dyes (IM-Dye-1 IM-Dye-2 and IM-Dye-3). The time dependant density functional theory (TDDFT) was used to calculate the excitation energies. All the calculations were performed in both gas and solvent phase. The LUMO energies of all the dyes were above the conduction band of TiO2, while the HOMOs were below the redox couple (except IM-Dye-3). The HOMO-LUMO energy gaps of new design dyes were smaller as compared to indigo. All new design dyes were strongly red shifted as compared to indigo. The improved light harvesting efficiency (LHE) and free energy change of electron injection Delta G(inject) of new designed sensitizers revealed that these materials would be excellent sensitizers. The broken coplanarity between the benzene near anchoring group having LUMO and the last benzene attached to TPA unit in all new design dyes consequently would hamper the recombination reaction. This theoretical designing will the pave way for experimentalists to synthesize the efficient sensitizers for solar cells.
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| 2. |
- Ali, Imran, et al.
(författare)
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Associations between cadmium exposure and circulating levels of sex hormones in postmenopausal women.
- 2014
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Ingår i: Environmental Research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 134, s. 265-269
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Tidskriftsartikel (refereegranskat)abstract
- Recent epidemiological as well as in vivo and in vitro studies collectively suggest that the metalloestrogen cadmium (Cd) could be a potential risk factor for hormone-related cancers in particularly breast cancer. Assessment of the association between Cd exposure and levels of endogenous sex hormones is of pivotal importance, as increased levels of such have been associated with a higher risk of breast cancer in postmenopausal women. The present study investigated the perceived relationship (multivariable-adjusted linear regression analyses) between Cd exposure [blood Cd (B-Cd) and urinary Cd (U-Cd)], and serum levels of androstenedione, testosterone, estradiol, and sex-hormone binding globulin (SHBG), in 438 postmenopausal Swedish women without hormone replacement therapy (HRT). A significant positive association between B-Cd (median 3.4nmol/L) and serum testosterone levels, as well as a significant inverse association between B-Cd and serum estradiol levels and with the estradiol/testosterone ratio were encountered. However, U-Cd (median 0.69nmol/mmol creatinine) was inversely associated with serum estradiol levels only. Our data may suggest that Cd interferes with the levels of testosterone and estradiol in postmenopausal women, which might have implications for breast cancer risk.
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| 3. |
- Ali, Imran, et al.
(författare)
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Cadmium-induced effects on cellular signaling pathways in the liver of transgenic estrogen reporter mice.
- 2012
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Ingår i: Toxicological Sciences. - : Oxford University Press (OUP). - 1096-6080 .- 1096-0929. ; 127:1, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Estrogen-like effects of cadmium (Cd) have been reported in several animal studies, and recent epidemiological findings suggest increased risk of hormone-dependent cancers after Cd exposure. The mechanisms underlying these effects are still under investigation. Our aim was to study the effects of Cd on cellular signaling pathways in vivo with special focus on estrogen signaling and to perform benchmark dose analysis on the effects. Transgenic adult ERE-luciferase male mice were exposed subcutaneously to 0.5-500 μg CdCl(2) per kg body weight (bw) or 17α-ethinylestradiol (EE2) for 3 days. These doses had no effects on organ and bw or testicular histology, indicating subtoxic exposure levels. The transgene luciferase, reporting genomic estrogen response, was significantly increased by EE2 but not by Cd. However, Cd significantly affected kinase phosphorylation and endogenous gene expression. Interestingly, gene expression changes displayed a traditional dose-response relationship, with benchmark dose levels for the expression of Mt1, Mt2, p53, c-fos, and Mdm2 being 92.9, 19.9, 7.6, 259, and 25.9 μg/kg bw, respectively, but changes in kinase phosphorylation were only detected at low exposure levels. Phosphorylation of Erk1/2 was significantly increased even in the lowest dose group, 0.5 μg/kg bw, rendering pErk1/2 a more sensitive sensor of exposure than changes in gene expression. Collectively, our data suggest that the effects triggered by Cd in vivo are markedly concentration dependent. Furthermore, we conclude that the estrogen-like effects of Cd are likely to result from a mechanism different from steroidal estrogens.
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| 4. |
- Ali, Imran, et al.
(författare)
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Estrogen-like effects of cadmium in vivo do not appear to be mediated via the classical estrogen receptor transcriptional pathway.
- 2010
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 118:10, s. 1389-94
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cadmium (Cd), a ubiquitous food contaminant, has been proposed to be an endocrine disruptor by inducing estrogenic responses in vivo. Several in vitro studies suggested that these effects are mediated via estrogen receptors (ERs). OBJECTIVE: We performed this study to clarify whether Cd-induced effects in vivo are mediated via classical ER signaling through estrogen responsive element (ERE)-regulated genes or if other signaling pathways are involved. METHODS: We investigated the estrogenic effects of cadmium chloride (CdCl2) exposure in vivo by applying the Organisation for Economic Co-operation and Development (OECD) rodent uterotrophic bioassay to transgenic ERE-luciferase reporter mice. Immature female mice were injected subcutaneously with CdCl2 (5, 50, or 500 µg/kg body weight) or with 17α-ethinylestradiol (EE2) on 3 consecutive days. We examined uterine weight and histology, vaginal opening, body and organ weights, Cd tissue retention, activation of mitogen-activated protein kinase (MAPK) pathways, and ERE-dependent luciferase expression. RESULTS: CdCl2 increased the height of the uterine luminal epithelium in a dose-dependent manner without increasing the uterine wet weight, altering the timing of vaginal opening, or affecting the luciferase activity in reproductive or nonreproductive organs. However, we observed changes in the phosphorylation of mouse double minute 2 oncoprotein (Mdm2) and extracellular signal-regulated kinase (Erk1/2) in the liver after CdCl2 exposure. As we expected, EE2 advanced vaginal opening and increased uterine epithelial height, uterine wet weight, and luciferase activity in various tissues. CONCLUSION: Our data suggest that Cd exposure induces a limited spectrum of estrogenic responses in vivo and that, in certain targets, effects of Cd might not be mediated via classical ER signaling through ERE-regulated genes.
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| 5. |
- Ali, Imran
(författare)
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Modulation of hormone signaling by cadmium : from molecular mechanisms to health implications
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cadmium is a toxic metal classified as human carcinogen and ubiquitously found in our environment mainly from anthropogenic activities. Exposure to cadmium has been associated with increased risk of certain hormone-dependent cancers in humans, and the metal has been proposed to possess endocrine disruptive properties by mimicking the physiological actions of estrogens. However, the mechanisms behind these effects are unclear. The overall aim of this thesis was to provide mechanistic insights into the estrogenicity of cadmium that may have implications for the human health. To achieve this aim, investigations on the estrogen-like effects of cadmium as well as possible involvement of classical/non-classical estrogen receptor signaling was studied in mice, and these mechanisms were further scrutinized in cell-based models. Furthermore, associations of biomarker of cadmium exposure with endogenous circulating sex hormones were evaluated in a population-based study of women. Results presented here indicate that exposure to cadmium does not affect the genomic estrogen response in vivo in mice, suggesting that classical estrogen signaling is not targeted by cadmium. However, some estrogen-like effects were observed in cadmium exposed mice, i.e. significant thickening of uterine epithelia, in the absence of uterine weight increase, and activation of ERK1/2 MAPKs in the liver. This suggests the existence of alternative signaling pathways modulated by cadmium. In addition, exposure to a wide dose range of cadmium, dose-dependently increased the expression of the endogenous genes Mt1, Mt2, p53, c-fos, and Mdm2 in mouse liver, with p53 being the most sensitive gene. However, phosphorylation of ERK1/2 was already induced at the lowest exposure level (0.5µg/kg body weight), rendering ERK1/2 a more sensitive marker of exposure than any change in gene expression. Furthermore, in vivo findings suggest that cadmium-induced effects are markedly concentration dependent: low-level exposure activates protein-kinases whereas high-level exposure turns on cellular stress responses. The data from in vitro studies indicate that cadmium at regular human exposure levels activates protein-kinase signaling through Raf-MEK-ERK/MAPKs, and we identified EGFR and GPR30 as the mediating receptors. This cadmium-induced activation of protein-kinases further leads to a disturbance in Mdm2/p53 balance, with a significant increase in the Mdm2/p53 ratio in the presence of genotoxic compounds, which in turn suggest that cadmium may disrupt stress response to genotoxins. In 438 postmenopausal women, a positive association was observed between the concentrations of cadmium in blood and testosterone in serum, while an inverse association was observed with estradiol. This may suggest that cadmium affects steroidogenesis. In conclusion, data presented in this thesis collectively suggests that cadmium-induced estrogen-like effects do not involve classical estrogen receptor signaling but rather appear to be mediated via membrane-associated signaling. The activation/ transactivation of GPR30/EGFR-Raf-MEK-ERK/MAPKs and Mdm2 represent a general mechanism by which cadmium may exert its effects. Since EGFR, ERK and Mdm2 are all known key players in cancer promotion, cadmium-induced activation of these and disturbance in the estradiol/testosterone balance in women may have implications for the promotion/development of hormone-related cancers.
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| 6. |
- Chatzinotas, Symeon, et al.
(författare)
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Multicell LMMSE Filtering Capacity under Correlated Multiple BS Antennas
- 2010
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Ingår i: Proceedings IEEE Vehicular Technology Conference, Fall. - : IEEE. - 9781424435746 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Multicell joint processing has been shown to efficiently suppress inter-cell interference, while providing a high capacity gain due to spatial multiplexing across distributed Base Stations (BSs). However, the complexity of the optimal joint decoder in the multicell uplink channel grows exponentially with the number of users, making it prohibitive to implement in practice. In this direction, this paper investigates the uplink capacity performance of multicell joint linear minimum mean square error (LMMSE) filtering, followed by single-user decoding. The considered cellular multiple-access channel model assumes both Rayleigh and Rician flat fading, path loss, distributed users and correlated multiple antennas at the base station side. The case of Rayleigh fading is tackled using a free probability approach, while the case of Rician fading is addressed through a deterministic equivalent calculated using non-linear programming techniques. In this context, it is shown that LMMSE can provide high spectral efficiencies in practical macrocellular scenarios.
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| 7. |
- Jamali, Imran Ali, et al.
(författare)
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A spatial multi-criteria analysis approach for locating suitable sites for construction of subsurface dams in northern Pakistan
- 2014
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Ingår i: Water resources management. - : Springer Science and Business Media LLC. - 0920-4741 .- 1573-1650. ; 28:14, s. 5157-5174
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Tidskriftsartikel (refereegranskat)abstract
- Pakistan is an agricultural country with an increasing interest for hydropower. Water management problems such as sedimentation and evaporation have been of high concern for surface water reservoirs for many years. Therefore, groundwater storage through subsurface dams could be promising, especially considering the monsoon rainfall and seasonal river flows in Pakistan. The paper aims to develop and test a methodology to locate suitable sites for construction of subsurface dams using spatial multi-criteria analysis (SMCA) in the northern parts of Pakistan. For the study, spatial data on geology, slope, land cover, soil depth and topographic wetness index (TWI) was used. Two weighting techniques, i.e. the analytic hierarchy process (AHP) and the factor interaction method (FIM), were employed and compared. The sensitivity of the two methods as well as of the model parameters was analysed. The suitability map derived from AHP yielded about 3 % (16 km(2)) of the total area as most suitable, about 4 % (22 km(2)) as moderately suitable and about 0.8 % (5 km(2)) as least suitable. The suitability map derived from FIM identified about 2.7 % (14 km(2)) of the total area as most suitable, about 4 % (22 km(2)) as moderately suitable and about 1 % (7 km(2)) as least suitable. The sensitivity analyses suggested that AHP was a more robust weighting technique than FIM and that land cover was the most sensitive factor. The methodology presented here shows promising results and could be used in early planning to locate suitable sites for construction of subsurface dams.
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| 8. |
- Jamali, Imran Ali, et al.
(författare)
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Locating suitable sites for the construction of subsurface dams using GIS
- 2013
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Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 70:6, s. 2511-2525
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Tidskriftsartikel (refereegranskat)abstract
- Subsurface dams constitute an affordable and effective method for the sustainable development and management of groundwater resources when constructed on suitable sites. Such dams have rarely been constructed in crystalline rock areas and to best of our knowledge, geographic information system (GIS) has never been used in any methodology for locating suitable sites for constructing these dams. This paper presents a new methodology to locate suitable sites for the construction of subsurface dams using GIS software supported by groundwater balance modelling in a study area Boda-Kalvsvik, Sweden. Groundwater resources were calculated based on digitized geological data and assumptions regarding stratigraphic layering taken from well archive data and geological maps. These estimates were then compared with future extractions for domestic water supply using a temporally dynamic water balance model. Suitability analyses for subsurface dams were based on calculated topographic wetness index (TWI) values and geological data, including stratigraphic information. Groundwater balance calculations indicated that many of the most populated areas were susceptible to frequent water supply shortages. Of the 34 sub-catchments within the study area: ten were over-extracted, nine did not have any water supply demand at all, one was self-sufficient and the remaining 14 were able to meet the water supply demand with surplus storage capacity. Six suitable sites for the construction of subsurface dams were suggested in the vicinity of the over-extracted sites based on suitability analysis and groundwater balance estimates. The new methodology shows encouraging results for regions with humid climate but having limited natural water storage capacities. The developed methodology can be used as a preliminary planning step for subsurface dam construction, establishing a base for more detailed field investigations.
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| 9. |
- Karlsson, Caroline, et al.
(författare)
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Comparison of methods for predicting regolith thickness in previously glaciated terrain, Stockholm, Sweden
- 2014
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 226, s. 116-129
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge about regolith thickness is important in several civil and environmental engineering fields. However, subsurface characteristics such as regolith thickness are difficult to determine through surface investigations and maps at regional scales. This paper presents four methods for estimating regolith thickness in a GIS environment for previously glaciated terrain with high frequency of rock outcrops: linear regression (LR) using topographical covariates; inverse distance weighting (IOW) interpolation of regolith thickness point data from well drillings: a trigonometrical approach (TA) developed for this study which uses outcrop slopes and distance between outcrops; and a simplified regolith model (SRM). The SRM is a model modified from TA which estimates the regolith thickness based on outcrops, slopes and the distance to outcrops in eight directions. The methods were compared for three study areas (Tyreso, Vallentuna and Osteraker) in Stockholm County, Sweden. Based on the results in this paper, LR proved to be the most accurate method for regolith thickness estimation, measured through root mean square error values. Whereas IDW was the most accurate method in terms of error within 2 m, which would make it a suitable model if and when large datasets of regolith point data are available. When drilling data is scarce then both the TA and SRM methods can be used for regolith estimations. However, the SRM proved to be a more accurate regolith thickness model compared to TA. SRM shows promising results and could be used at a preliminary stage in engineering projects where little or no data is available prior to detailed field investigations in previously glaciated terrain.
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| 10. |
- Kastrati, Zenun, 1984-, et al.
(författare)
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Adaptive Concept Vector Space Representation Using Markov Chain Model
- 2014
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Ingår i: Knowledge Engineering and Knowledge Management. - Cham : Springer. - 9783319137032 - 9783319137049 ; , s. 203-208
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Konferensbidrag (refereegranskat)abstract
- This paper proposes an adaptive document representation (concept vector space model) using Markov Chain model. The vector space representation is one of the most common models for representing documents in classification process. The document classification based on ontology classification approach is represented as a vector, whose components are ontology concepts and their relevance. The relevance is represented the by frequency of concepts’ occurrence. These concepts make various contributions in classification process. The contributions depend on the position of concepts where they are depicted in the ontology hierarchy. The hierarchy such as classes, subclasses and instances may have different values to represent the concepts’ importance. The weights to define concepts’ importance are generally selected by empirical analysis and are usually kept fixed. Thus, making it less effective and time consuming. We therefore propose a new model to automatically estimate weights of concepts within the ontology. This model initially maps the ontology to a Markov chain model and then calculates the transition probability matrix for this Markov chain. Further, the transition probability matrix is used to compute the probability of steady states based on left eigenvectors. Finally, the importance is calculated for each ontology concept. And, an enhanced concept vector space representation is created with concepts’ importance and concepts’ relevance. The concept vector space representation can be adapted for new ontology concepts.
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