Abd Can - Academia.edu (original) (raw)

Papers by Abd Can

Asynchronous signal processing is an appropriate low-power approach for the processing of bursty ... more Asynchronous signal processing is an appropriate low-power approach for the processing of bursty signals typical in biomedical applications and sensing networks. Different from the synchronous processing, based on the Shannon-Nyquist sampling theory, asynchronous processing is free of aliasing constrains and quantization error, while allowing continuous-time processing. In this paper we connect levelcrossing sampling with time-encoding using asynchronous sigma delta modulators, to develop an asynchronous decomposition procedure similar to the Haar transform wavelet decomposition. Our procedure provides a way to reconstruct bounded signals, not necessarily band-limited, from related zero-crossings, and it is especially applicable to decompose sparse signals in time and to denoise them. Actual and synthetic signals are used to illustrate the advantages of the decomposer. Index Terms-Continuous-time digital signal processing, time-encoding of signals, level-crossing sampling, asynchronous sigma delta modulators, asynchronous signal processing.

Continuous-time digital signal processors not only offer significant energy savings in important ... more Continuous-time digital signal processors not only offer significant energy savings in important applications such as implantable biomedical devices, but can implement asynchronous procedures. In this paper, we propose an asynchronous signal decomposition for continuous-time signals based on scale rather than frequency. Because the implementation of the proposed procedure does not use a clock it is not affected by aliasing, and moreover no quantization is involved. Such procedure is specially applicable to biomedical signals delivering information in bursts rather than continuously. The decomposer consists of cascaded modules that expand the signal onto different resolution scales and each is composed of an asynchronous sigma delta modulator (ASDM) followed by a local averager and a lowpass filter. The ASDM is a non-linear feedback system used to represent the amplitude of a continuous-time signal by a binary signal whose zero-crossings are used to reconstruct the original signal. One of the parameters of the ASDM is used as a scaling parameter, permitting us to represent the signal by its local means-at different scales-and computed from the zerocrossing times of the output of the ASDM. We develop a compact signal representation that is described by a small number of scale parameters and contains information useful in the continuoustime processing and transmission of the data. The performance of the proposed procedure is illustrated using different types of signals. As a practical application, we consider the non-linear denoising of swallowing signals. Potentially our procedure will find application in asynchronous signal acquisition, continuoustime digital signal processing and transmission in low-power biomedical applications.

Monitoring physiological functions such as swallowing often generates large volumes of samples to... more Monitoring physiological functions such as swallowing often generates large volumes of samples to be stored and processed, which can introduce computational constraints especially if remote monitoring is desired. In this article, we propose a compressive sensing (CS) algorithm to alleviate some of these issues while acquiring dual-axis swallowing accelerometry signals. The proposed CS approach uses a time-frequency dictionary where the members are modulated discrete prolate spheroidal sequences (MDPSS). These waveforms are obtained by modulation and variation of discrete prolate spheroidal sequences (DPSS) in order to reflect the time-varying nature of swallowing acclerometry signals. While the modulated bases permit one to represent the signal behavior accurately, the matching pursuit algorithm is adopted to iteratively decompose the signals into an expansion of the dictionary bases. To test the accuracy of the proposed scheme, we carried out several numerical experiments with synthetic test signals and dual-axis swallowing accelerometry signals. In both cases, the proposed CS approach based on the MDPSS yields more accurate representations than the CS approach based on DPSS. Specifically, we show that dual-axis swallowing accelerometry signals can be accurately reconstructed even when the sampling rate is reduced to half of the Nyquist rate. The results clearly indicate that the MDPSS are suitable bases for swallowing accelerometry signals.

Transportation Research Part D: Transport and Environment, 2011

This paper examines the effects of two traffic management measures, speed limit reduction and coo... more This paper examines the effects of two traffic management measures, speed limit reduction and coordinated traffic lights, in a case study area in Antwerp, Belgium. For this purpose, an integrated model that combines the microscopic traffic simulation model Paramics with the CO 2 and NO x emission model VERSIT+ is constructed and validated. On the one hand, reductions in CO 2 and NO x emissions in the order of 25 % were found if speed limits are lowered from 50 to 30 km/h in the residential part of the case study area. On the other hand, reductions in the order of 10 % can be expected from the implementation of a green wave signal coordination scheme along an urban arterial road.

Stroke, 2004

Background and Purpose-Both necrotic and apoptotic cell death mechanisms are activated after cere... more Background and Purpose-Both necrotic and apoptotic cell death mechanisms are activated after cerebral ischemia. However, whether they are concomitantly active in the same cell or in discrete cell populations is not known. Methods-We investigated activation of both pathways at the cellular level in mice brains subjected to transient or permanent focal ischemia. Results-Four hours after ischemia, diffuse cathepsin-B spillage into cytoplasm, suggesting lysosomal leakage, was observed within neurons immunoreactive for the active form of caspase-3 (p20). Ischemic neurons with a leaky plasma membrane (positive for propidium iodide) were colabeled with caspase-cleaved actin fragment and exhibited TUNEL-positive nuclei having apoptotic morphology. At 72 hours, up to 27% of cells with caspase activity displayed morphological features suggestive of secondary necrosis. Conclusions-These data, demonstrating an early and concurrent increase in caspase-3 and cathepsin-B activities followed by appearance of caspase-cleavage products, DNA fragmentation, and membrane disintegration, suggest that subroutines of necrotic and apoptotic cell death are concomitantly activated in ischemic neurons and that the dominant cell death phenotype is determined by the relative speed of each process.

Molecular reproduction and development, 1997

The effects of the pesticide carbendazim (MBC) on the in vitro meiotic maturation of mouse oocyte... more The effects of the pesticide carbendazim (MBC) on the in vitro meiotic maturation of mouse oocytes were evaluated using conventional and confocal fluorescence microscopy. The response of oocytes exposed to 0, 3, 10, or 30 mM MBC during meiotic maturation was analyzed with respect to chromosome organization, meiotic spindle microtubules, and cortical actin using fluorescent labels for each of these structures. Continuous exposure to MBC during the resumption of meiosis resulted in a dose-dependent inhibition of meiotic cell cycle progression at metaphase of meiosis-1. Drug exposure at the metaphaseanaphase transition of meiosis-1 did not interfere with cell cycle progression to metaphase-2 except at high concentrations (30 mM). At the level of spindle microtubule organization, MBC caused a loss of nonacetylated microtubules and a decrease in spindle size at 3 or 10 mM concentrations. Thirty mM MBC prevented spindle assembly when added at the beginning of meiotic maturation or caused spindle pole disruption and fragmentation when added to preformed spindles. Spindle disruption involved a loss of phosphoprotein epitopes, as monitored by MPM-2 staining, and resulted in the appearance of dispersed chromosomes that retained a metaphase-plate location on spindle fragments associated with the oocyte cortex. Polar body extrusion was impaired by MBC, and abnormal polar bodies were observed in most treated oocytes. The results suggest that MBC disrupts cell cycle progression in mouse oocytes by altering meiotic spindle microtubule stability and spindle pole integrity.

Stroke, 2004

Background and Purpose-Use of thrombolysis in stroke is limited by a short therapeutic window bec... more Background and Purpose-Use of thrombolysis in stroke is limited by a short therapeutic window because delayed reperfusion may cause brain hemorrhage and edema. Available evidence suggests a role for superoxide, NO, and peroxynitrite in reperfusion-induced injury. However, depending on their cellular origin and interactions between them, these molecules may exert protective or deleterious actions, neither of which is characterized in the intact brain. Methods-Using fluorescent probes, we determined superoxide and peroxynitrite formation within neurons, astrocytes, and endothelium, and the association between oxidative/nitrative stress and vascular injury in mice brains subjected to 2-hour middle cerebral artery occlusion and 3 or 5 hours of reperfusion. Results-Both signals were colocalized, suggesting that the main source of peroxynitrite in the reperfused brain was a reaction between superoxide and NO. Superoxide and peroxynitrite formation was particularly intense in microvessels and astrocytic end-feet surrounding them, and overlapped with dense mitochondrial labeling. Sites of oxidative/nitrative stress on microvessels were colocalized with markers of vascular injury such as Evans blue (EB) leakage and matrix metalloproteinase-9 (MMP-9) expression, suggesting an association between peroxynitrite and microvascular injury. Supporting this idea, partial inhibition of endothelial NO synthesis at reperfusion with a low dose of L-nitroarginine (1 mg/kg IP) reduced 3-nitrotyrosine formation in microvessels and EB extravasation. Conclusion-During reperfusion, intense superoxide, NO, and peroxynitrite formation on microvessels and surrounding end-feet may lead to cerebral hemorrhage and edema by disrupting microvascular integrity. Combination of thrombolysis with agents diminishing oxidative/nitrative stress may reduce reperfusion-induced injury and extend the therapeutic window for thrombolysis. (Stroke. 2004;35:1449-1453.) Key Words: blood-brain barrier Ⅲ matrix metalloproteinases Ⅲ nitric oxide Ⅲ peroxynitrite Ⅲ reactive oxygen species Ⅲ reperfusion injury Ⅲ thrombolysis

Indian journal of …, 2004

Significant degenerative changes were observed in the kidney tissue of untreated neonatal strepto... more Significant degenerative changes were observed in the kidney tissue of untreated neonatal streptozotocin (n0STZ)-induced type-II diabetic rats. These degenerative changes were diminished in the kidney tissue of diabetic animals given glibenclamide and Aloe leaf gel and pulp extracts. Kidney lipid peroxidation levels were increased in diabetic rats compared to healthy rats; these levels were higher in rats treated with glibenclamide than in those which received Aloe extracts. Serum urea and creatinine levels were higher in diabetic rats in comparison to healthy rats. The administration of Aloe gel extract and glibenclamide decreased serum urea and creatinine levels in comparison to diabetic controls. Only A. vera leaf gel extract showed improvement both in histological and biochemical parameters suggesting a protective effect of A. vera on mild damage caused by type-II diabetes on kidney tissue.

Phytotherapy …, 2001

Aloe vera (L.) Burm. fil. (= A. barbadensis Miller) (Liliaceae) is native to North Africa and als... more Aloe vera (L.) Burm. fil. (= A. barbadensis Miller) (Liliaceae) is native to North Africa and also cultivated in Turkey. Aloes have long been used all over the world for their various medicinal properties. In the past 15 years, there have been controversial reports on the hypoglycaemic activity of Aloe species, probably due to differences in the parts of the plant used or to the model of diabetes chosen. In this study, separate experiments on three main groups of rats, namely, non-diabetic (ND), type I (IDDM) and type II (NIDDM) diabetic rats were carried out. A. vera leaf pulp and gel extracts were ineffective on lowering the blood sugar level of ND rats. A. vera leaf pulp extract showed hypoglycaemic activity on IDDM and NIDDM rats, the effectiveness being enhanced for type II diabetes in comparison with glibenclamide. On the contrary, A. vera leaf gel extract showed hyperglycaemic activity on NIDDM rats. It may therefore be concluded that the pulps of Aloe vera leaves devoid of t...

Tribology International, 2000

Since any state of residual stress influences the service behavior of a material, it is of partic... more Since any state of residual stress influences the service behavior of a material, it is of particular interest for engineers and designers to know its benefits to machine parts, and where it can be utilized successfully. From this point of view, mechanical tangential pre-stress as circumferential compressive residual stress has been investigated for wear performance. For this purpose, a thick

Journal of Biotechnology, 2008

Members of the genus Shewanella inhabit various environments, and are well known for their versat... more Members of the genus Shewanella inhabit various environments, and are well known for their versatile respiratory capabilities, cou

This paper presents ongoing research of the IDEA (Intelligent, Distributed, Environmental assessm... more This paper presents ongoing research of the IDEA (Intelligent, Distributed, Environmental assessment) project. The aim is to build an extensive multi-sensor urban measurement network. The focus is on noise and air pollution caused by road traffic. The use of cheap sensors is an important prerequisite to come to implementation of such a network. The potentially lower data quality resulting from the use of cheaper sensors should then be overcome by adding intelligence to the network at various levels. A flexible network architecture was designed for the specific aims of the IDEA project. Two noise-related aspects are dealt with in more detail in this paper. Firstly, results from indoor and outdoor testing of different types of microphones are shown. Secondly, the estimation of pollutant concentrations based on noise measurements is proposed to help interpolating expensive-tomeasure air pollutants.

Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (pr... more Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (prediction of 15 min and 60 min evolution of L(Aeq) and statistical levels L(A90,)L(A50) and L(A10)) noise level monitoring are investigated in this paper. Noise levels are measured for 72 consecutive days at 5 neighboring streets in an inner-city noise measurement network in Gent, Flanders, Belgium. We present a method to make predictions based on a fixed monitoring station, combined with short-term sampling at temporary stations. It is shown that relying on a fixed station improves the estimation of L(den) at other locations, and allows for the reduction of the number of samples needed and their duration; L(den) is estimated with an error that does not exceed 1.5 dB(A) to 3.4 dB(A) according to the location, for 90% of the 3 × 15 min samples. Also the diurnal averaged noise pattern can be estimated with a good accuracy in this way. It was shown that there is an optimal location for the fixed station which can be found by short-term measurements only. Short-term level predictions were shown to be more difficult; 7 day samples were needed to build models able to estimate the evolution of L(Aeq,60min) with a RMSE ranging between 1.4 dB(A) and 3.7 dB(A). These higher values can be explained by the very pronounced short-term variations appearing in typical streets, which are not correlated between locations. On the other hand, moderately accurate predictions can be achieved, even based on short-term sampling (a 3 × 15 minute sampling duration seems to be sufficient for many of the accuracy goals set related to static and dynamic monitoring). Finally, the method proposed also allows for the prediction of the evolution of statistical indicators.

Due to their typically high traffic intensity, urban ring roads are characterized by high noise l... more Due to their typically high traffic intensity, urban ring roads are characterized by high noise levels and high concentrations of airborne pollutants. Hence, such locations are often priority measurement locations in monitoring networks. Unfortunately, the high purchase and operational cost of most airborne pollutant sensors severely limits the number of such sensors that can be deployed, leading to a (too) limited spatial resolution. The present research describes how low cost microphones could be used as proxies for traffic parameters. We consider a 7 day measurement campaign for an urban ring road in Antwerp, Belgium, where noise levels and traffic parameters were measured simultaneously. Noise indicators are calculated and are used to construct models to estimate traffic parameters. It was found that a proper choice of noise indicators allows for the accurate estimation of traffic intensities and means vehicle speeds, both for light and heavy vehicles. Furthermore, the usefulness of these estimated traffic indicators in a monitoring strategy is assessed. Carbon monoxide, hydrocarbon and nitrogen oxide emissions are calculated with the pollutant emission model Artemis. By comparing the Artemis outputs when using measured and estimated traffic parameters as input, the suitability of the constructed models is assessed. Estimations of emitted airborne pollutants were shown to be accurate, leading us to conclude that there are indeed significant opportunities to use noise measurements as proxies for traffic parameter measurements for the estimation of airborne pollutant emissions.

spie.org

Prostate cancer is diagnosed by histopathology interpretation of hematoxylin and eosin (H and E)-... more Prostate cancer is diagnosed by histopathology interpretation of hematoxylin and eosin (H and E)-stained tissue sections. Gland and nuclei distributions vary with the disease grade. The morphological features vary with the advance of cancer where the epithelial regions grow into the ...

Asynchronous signal processing is an appropriate low-power approach for the processing of bursty ... more Asynchronous signal processing is an appropriate low-power approach for the processing of bursty signals typical in biomedical applications and sensing networks. Different from the synchronous processing, based on the Shannon-Nyquist sampling theory, asynchronous processing is free of aliasing constrains and quantization error, while allowing continuous-time processing. In this paper we connect levelcrossing sampling with time-encoding using asynchronous sigma delta modulators, to develop an asynchronous decomposition procedure similar to the Haar transform wavelet decomposition. Our procedure provides a way to reconstruct bounded signals, not necessarily band-limited, from related zero-crossings, and it is especially applicable to decompose sparse signals in time and to denoise them. Actual and synthetic signals are used to illustrate the advantages of the decomposer. Index Terms-Continuous-time digital signal processing, time-encoding of signals, level-crossing sampling, asynchronous sigma delta modulators, asynchronous signal processing.

Continuous-time digital signal processors not only offer significant energy savings in important ... more Continuous-time digital signal processors not only offer significant energy savings in important applications such as implantable biomedical devices, but can implement asynchronous procedures. In this paper, we propose an asynchronous signal decomposition for continuous-time signals based on scale rather than frequency. Because the implementation of the proposed procedure does not use a clock it is not affected by aliasing, and moreover no quantization is involved. Such procedure is specially applicable to biomedical signals delivering information in bursts rather than continuously. The decomposer consists of cascaded modules that expand the signal onto different resolution scales and each is composed of an asynchronous sigma delta modulator (ASDM) followed by a local averager and a lowpass filter. The ASDM is a non-linear feedback system used to represent the amplitude of a continuous-time signal by a binary signal whose zero-crossings are used to reconstruct the original signal. One of the parameters of the ASDM is used as a scaling parameter, permitting us to represent the signal by its local means-at different scales-and computed from the zerocrossing times of the output of the ASDM. We develop a compact signal representation that is described by a small number of scale parameters and contains information useful in the continuoustime processing and transmission of the data. The performance of the proposed procedure is illustrated using different types of signals. As a practical application, we consider the non-linear denoising of swallowing signals. Potentially our procedure will find application in asynchronous signal acquisition, continuoustime digital signal processing and transmission in low-power biomedical applications.

Monitoring physiological functions such as swallowing often generates large volumes of samples to... more Monitoring physiological functions such as swallowing often generates large volumes of samples to be stored and processed, which can introduce computational constraints especially if remote monitoring is desired. In this article, we propose a compressive sensing (CS) algorithm to alleviate some of these issues while acquiring dual-axis swallowing accelerometry signals. The proposed CS approach uses a time-frequency dictionary where the members are modulated discrete prolate spheroidal sequences (MDPSS). These waveforms are obtained by modulation and variation of discrete prolate spheroidal sequences (DPSS) in order to reflect the time-varying nature of swallowing acclerometry signals. While the modulated bases permit one to represent the signal behavior accurately, the matching pursuit algorithm is adopted to iteratively decompose the signals into an expansion of the dictionary bases. To test the accuracy of the proposed scheme, we carried out several numerical experiments with synthetic test signals and dual-axis swallowing accelerometry signals. In both cases, the proposed CS approach based on the MDPSS yields more accurate representations than the CS approach based on DPSS. Specifically, we show that dual-axis swallowing accelerometry signals can be accurately reconstructed even when the sampling rate is reduced to half of the Nyquist rate. The results clearly indicate that the MDPSS are suitable bases for swallowing accelerometry signals.

Transportation Research Part D: Transport and Environment, 2011

This paper examines the effects of two traffic management measures, speed limit reduction and coo... more This paper examines the effects of two traffic management measures, speed limit reduction and coordinated traffic lights, in a case study area in Antwerp, Belgium. For this purpose, an integrated model that combines the microscopic traffic simulation model Paramics with the CO 2 and NO x emission model VERSIT+ is constructed and validated. On the one hand, reductions in CO 2 and NO x emissions in the order of 25 % were found if speed limits are lowered from 50 to 30 km/h in the residential part of the case study area. On the other hand, reductions in the order of 10 % can be expected from the implementation of a green wave signal coordination scheme along an urban arterial road.

Stroke, 2004

Background and Purpose-Both necrotic and apoptotic cell death mechanisms are activated after cere... more Background and Purpose-Both necrotic and apoptotic cell death mechanisms are activated after cerebral ischemia. However, whether they are concomitantly active in the same cell or in discrete cell populations is not known. Methods-We investigated activation of both pathways at the cellular level in mice brains subjected to transient or permanent focal ischemia. Results-Four hours after ischemia, diffuse cathepsin-B spillage into cytoplasm, suggesting lysosomal leakage, was observed within neurons immunoreactive for the active form of caspase-3 (p20). Ischemic neurons with a leaky plasma membrane (positive for propidium iodide) were colabeled with caspase-cleaved actin fragment and exhibited TUNEL-positive nuclei having apoptotic morphology. At 72 hours, up to 27% of cells with caspase activity displayed morphological features suggestive of secondary necrosis. Conclusions-These data, demonstrating an early and concurrent increase in caspase-3 and cathepsin-B activities followed by appearance of caspase-cleavage products, DNA fragmentation, and membrane disintegration, suggest that subroutines of necrotic and apoptotic cell death are concomitantly activated in ischemic neurons and that the dominant cell death phenotype is determined by the relative speed of each process.

Molecular reproduction and development, 1997

The effects of the pesticide carbendazim (MBC) on the in vitro meiotic maturation of mouse oocyte... more The effects of the pesticide carbendazim (MBC) on the in vitro meiotic maturation of mouse oocytes were evaluated using conventional and confocal fluorescence microscopy. The response of oocytes exposed to 0, 3, 10, or 30 mM MBC during meiotic maturation was analyzed with respect to chromosome organization, meiotic spindle microtubules, and cortical actin using fluorescent labels for each of these structures. Continuous exposure to MBC during the resumption of meiosis resulted in a dose-dependent inhibition of meiotic cell cycle progression at metaphase of meiosis-1. Drug exposure at the metaphaseanaphase transition of meiosis-1 did not interfere with cell cycle progression to metaphase-2 except at high concentrations (30 mM). At the level of spindle microtubule organization, MBC caused a loss of nonacetylated microtubules and a decrease in spindle size at 3 or 10 mM concentrations. Thirty mM MBC prevented spindle assembly when added at the beginning of meiotic maturation or caused spindle pole disruption and fragmentation when added to preformed spindles. Spindle disruption involved a loss of phosphoprotein epitopes, as monitored by MPM-2 staining, and resulted in the appearance of dispersed chromosomes that retained a metaphase-plate location on spindle fragments associated with the oocyte cortex. Polar body extrusion was impaired by MBC, and abnormal polar bodies were observed in most treated oocytes. The results suggest that MBC disrupts cell cycle progression in mouse oocytes by altering meiotic spindle microtubule stability and spindle pole integrity.

Stroke, 2004

Background and Purpose-Use of thrombolysis in stroke is limited by a short therapeutic window bec... more Background and Purpose-Use of thrombolysis in stroke is limited by a short therapeutic window because delayed reperfusion may cause brain hemorrhage and edema. Available evidence suggests a role for superoxide, NO, and peroxynitrite in reperfusion-induced injury. However, depending on their cellular origin and interactions between them, these molecules may exert protective or deleterious actions, neither of which is characterized in the intact brain. Methods-Using fluorescent probes, we determined superoxide and peroxynitrite formation within neurons, astrocytes, and endothelium, and the association between oxidative/nitrative stress and vascular injury in mice brains subjected to 2-hour middle cerebral artery occlusion and 3 or 5 hours of reperfusion. Results-Both signals were colocalized, suggesting that the main source of peroxynitrite in the reperfused brain was a reaction between superoxide and NO. Superoxide and peroxynitrite formation was particularly intense in microvessels and astrocytic end-feet surrounding them, and overlapped with dense mitochondrial labeling. Sites of oxidative/nitrative stress on microvessels were colocalized with markers of vascular injury such as Evans blue (EB) leakage and matrix metalloproteinase-9 (MMP-9) expression, suggesting an association between peroxynitrite and microvascular injury. Supporting this idea, partial inhibition of endothelial NO synthesis at reperfusion with a low dose of L-nitroarginine (1 mg/kg IP) reduced 3-nitrotyrosine formation in microvessels and EB extravasation. Conclusion-During reperfusion, intense superoxide, NO, and peroxynitrite formation on microvessels and surrounding end-feet may lead to cerebral hemorrhage and edema by disrupting microvascular integrity. Combination of thrombolysis with agents diminishing oxidative/nitrative stress may reduce reperfusion-induced injury and extend the therapeutic window for thrombolysis. (Stroke. 2004;35:1449-1453.) Key Words: blood-brain barrier Ⅲ matrix metalloproteinases Ⅲ nitric oxide Ⅲ peroxynitrite Ⅲ reactive oxygen species Ⅲ reperfusion injury Ⅲ thrombolysis

Indian journal of …, 2004

Significant degenerative changes were observed in the kidney tissue of untreated neonatal strepto... more Significant degenerative changes were observed in the kidney tissue of untreated neonatal streptozotocin (n0STZ)-induced type-II diabetic rats. These degenerative changes were diminished in the kidney tissue of diabetic animals given glibenclamide and Aloe leaf gel and pulp extracts. Kidney lipid peroxidation levels were increased in diabetic rats compared to healthy rats; these levels were higher in rats treated with glibenclamide than in those which received Aloe extracts. Serum urea and creatinine levels were higher in diabetic rats in comparison to healthy rats. The administration of Aloe gel extract and glibenclamide decreased serum urea and creatinine levels in comparison to diabetic controls. Only A. vera leaf gel extract showed improvement both in histological and biochemical parameters suggesting a protective effect of A. vera on mild damage caused by type-II diabetes on kidney tissue.

Phytotherapy …, 2001

Aloe vera (L.) Burm. fil. (= A. barbadensis Miller) (Liliaceae) is native to North Africa and als... more Aloe vera (L.) Burm. fil. (= A. barbadensis Miller) (Liliaceae) is native to North Africa and also cultivated in Turkey. Aloes have long been used all over the world for their various medicinal properties. In the past 15 years, there have been controversial reports on the hypoglycaemic activity of Aloe species, probably due to differences in the parts of the plant used or to the model of diabetes chosen. In this study, separate experiments on three main groups of rats, namely, non-diabetic (ND), type I (IDDM) and type II (NIDDM) diabetic rats were carried out. A. vera leaf pulp and gel extracts were ineffective on lowering the blood sugar level of ND rats. A. vera leaf pulp extract showed hypoglycaemic activity on IDDM and NIDDM rats, the effectiveness being enhanced for type II diabetes in comparison with glibenclamide. On the contrary, A. vera leaf gel extract showed hyperglycaemic activity on NIDDM rats. It may therefore be concluded that the pulps of Aloe vera leaves devoid of t...

Tribology International, 2000

Since any state of residual stress influences the service behavior of a material, it is of partic... more Since any state of residual stress influences the service behavior of a material, it is of particular interest for engineers and designers to know its benefits to machine parts, and where it can be utilized successfully. From this point of view, mechanical tangential pre-stress as circumferential compressive residual stress has been investigated for wear performance. For this purpose, a thick

Journal of Biotechnology, 2008

Members of the genus Shewanella inhabit various environments, and are well known for their versat... more Members of the genus Shewanella inhabit various environments, and are well known for their versatile respiratory capabilities, cou

This paper presents ongoing research of the IDEA (Intelligent, Distributed, Environmental assessm... more This paper presents ongoing research of the IDEA (Intelligent, Distributed, Environmental assessment) project. The aim is to build an extensive multi-sensor urban measurement network. The focus is on noise and air pollution caused by road traffic. The use of cheap sensors is an important prerequisite to come to implementation of such a network. The potentially lower data quality resulting from the use of cheaper sensors should then be overcome by adding intelligence to the network at various levels. A flexible network architecture was designed for the specific aims of the IDEA project. Two noise-related aspects are dealt with in more detail in this paper. Firstly, results from indoor and outdoor testing of different types of microphones are shown. Secondly, the estimation of pollutant concentrations based on noise measurements is proposed to help interpolating expensive-tomeasure air pollutants.

Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (pr... more Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (prediction of 15 min and 60 min evolution of L(Aeq) and statistical levels L(A90,)L(A50) and L(A10)) noise level monitoring are investigated in this paper. Noise levels are measured for 72 consecutive days at 5 neighboring streets in an inner-city noise measurement network in Gent, Flanders, Belgium. We present a method to make predictions based on a fixed monitoring station, combined with short-term sampling at temporary stations. It is shown that relying on a fixed station improves the estimation of L(den) at other locations, and allows for the reduction of the number of samples needed and their duration; L(den) is estimated with an error that does not exceed 1.5 dB(A) to 3.4 dB(A) according to the location, for 90% of the 3 × 15 min samples. Also the diurnal averaged noise pattern can be estimated with a good accuracy in this way. It was shown that there is an optimal location for the fixed station which can be found by short-term measurements only. Short-term level predictions were shown to be more difficult; 7 day samples were needed to build models able to estimate the evolution of L(Aeq,60min) with a RMSE ranging between 1.4 dB(A) and 3.7 dB(A). These higher values can be explained by the very pronounced short-term variations appearing in typical streets, which are not correlated between locations. On the other hand, moderately accurate predictions can be achieved, even based on short-term sampling (a 3 × 15 minute sampling duration seems to be sufficient for many of the accuracy goals set related to static and dynamic monitoring). Finally, the method proposed also allows for the prediction of the evolution of statistical indicators.

Due to their typically high traffic intensity, urban ring roads are characterized by high noise l... more Due to their typically high traffic intensity, urban ring roads are characterized by high noise levels and high concentrations of airborne pollutants. Hence, such locations are often priority measurement locations in monitoring networks. Unfortunately, the high purchase and operational cost of most airborne pollutant sensors severely limits the number of such sensors that can be deployed, leading to a (too) limited spatial resolution. The present research describes how low cost microphones could be used as proxies for traffic parameters. We consider a 7 day measurement campaign for an urban ring road in Antwerp, Belgium, where noise levels and traffic parameters were measured simultaneously. Noise indicators are calculated and are used to construct models to estimate traffic parameters. It was found that a proper choice of noise indicators allows for the accurate estimation of traffic intensities and means vehicle speeds, both for light and heavy vehicles. Furthermore, the usefulness of these estimated traffic indicators in a monitoring strategy is assessed. Carbon monoxide, hydrocarbon and nitrogen oxide emissions are calculated with the pollutant emission model Artemis. By comparing the Artemis outputs when using measured and estimated traffic parameters as input, the suitability of the constructed models is assessed. Estimations of emitted airborne pollutants were shown to be accurate, leading us to conclude that there are indeed significant opportunities to use noise measurements as proxies for traffic parameter measurements for the estimation of airborne pollutant emissions.

spie.org

Prostate cancer is diagnosed by histopathology interpretation of hematoxylin and eosin (H and E)-... more Prostate cancer is diagnosed by histopathology interpretation of hematoxylin and eosin (H and E)-stained tissue sections. Gland and nuclei distributions vary with the disease grade. The morphological features vary with the advance of cancer where the epithelial regions grow into the ...