To retrospectively evaluate the diagnostic performance of a serum human tissue kallikrein 11 (hK1... more To retrospectively evaluate the diagnostic performance of a serum human tissue kallikrein 11 (hK11) assay to predict the presence of prostate cancer in a screened population of men with a total prostate-specific antigen (PSA) level between 2.5 and 10.0 ng/mL.
Background: Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of cirrhosis in w... more Background: Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of cirrhosis in which IPV results in progressive hypoxemia and increases mortality. ET-1 has been identified as a mediator of IPV in an animal model of HPS, but the pathophysiology of human HPS has not been defined. Aim: To assess whether IPV in patients with cirrhosis, which often leads to HPS, is associated with increased HV ET-1. Methods: Prospective cohort study of 40 patients with liver disease undergoing transjugular liver biopsy from 11/1/2008 -8/30/2009. Patients were categorized according to absence (-) or presence (+) of IPV as determined by bubble-contrasted echocardiography. HV blood was sampled for ET-1 assay by ELISA. Demographic and clinical data (including the hepatic venous pressure gradient, HVPG) were collected. Descriptive statistics: Chi-Square, Wilcoxon Rank Sum, and Spearman Correlation. A multivariate logistic regression model was created for IPV using covariates from the univariate analyses. Results: Six subjects without cirrhosis and 1 with patent foramen ovale were excluded. Of the remaining 33 subjects, 17 (52%) women and 16 (48%) men with mean age of 55 yrs ± 10.6 SD; IPV was present in 19 subjects (58%). Median HV ET-1 was higher with IPV(+) than IPV(-): 2.3pg/mL (1.6 -9.2) vs. 9.2pg/mL (7.4 -13.4) respectively, p=0.02. IPV was also associated with higher bilirubin (Bili) and INR, but not creatinine (Cr), MELD, blood pressure (BP), or HVPG . ET-1 was inversely correlated with both systolic (ρ= -0.45, p=0.007 and diastolic (ρ= -0.50, p=0.003) BP, but not with liver dysfunction (Bili, INR, MELD, or HVPG), Cr, or severity of hypoxemia (PaO2). When correcting for Bili and INR by Logistic Regression, higher ET-1 still predicted IPV (OR 1.46, 1.02 -2.07). Conclusion: In human cirrhosis, increased HV ET-1 is associated with IPV. Further studies are needed to better define the hepatic origin of ET-1, its role in IPV, and its utility as a therapeutic target.
According to common criteria, 11 patients were classified as type 1 HRS, 7 patients had type 2 HR... more According to common criteria, 11 patients were classified as type 1 HRS, 7 patients had type 2 HRS. After TIPS, HVPG was effectively reduced in all patients (before TIPS: 22,5 mmHg (SD 5,6); after TIPS 5,5 mmHg (SD 3,4)). No major procedure-related complication was observed. Renal function improved within hospital stay (serum creatinine 3.0 mg/dL (SD 2,7) to 1,9 mg/dL (SD 2,8)). Of all patients, 13 (72,2%) could be discharged from hospital with stable or improved renal function, one of them requiring continued hemodialysis; 5 Patients died (27,8%). Of patients with type 1 HRS, 6 (54,5%) were discharged from hospital whereas 5 (45,5%) died. Of patients with type 2 HRS, 6 (86%) survived, 1 patient (0,14%) died during hospital stay. CONCLUSION: In this retrospective study, transjugular intrahepatic portosystemic shunt has been shown to be able to improve renal function in cirrhotic patients with HRS and is associatited with comparatively low in-hospital mortality.
IEEE Transactions on Geoscience and Remote Sensing, 2009
In the U.S. Wide Area Augmentation System, European Geostationary Navigation Overlay Service, and... more In the U.S. Wide Area Augmentation System, European Geostationary Navigation Overlay Service, and Indian Global Positioning System Aided Geo Augmented Navigation, a near real-time grid-based single-shell model is proposed to correct the ionospheric delay at the user aircrafts. The single-shell model is based on the assumption that the whole ionosphere is compressed at a fixed altitude at 350 km. This assumption may not be appropriate for the Indian region, which falls in the Equatorial Ionospheric Anomaly belt. In this paper, a two-shell model which incorporates two different shells, at 300-and 500-km altitudes, having different weights at different time domains has been implemented. A statistical comparison between single-and two-shell models has been done for all quiet days of year 2005. Based on the results, it is observed that there is at least 60% improvement in the performance of the two-shell model in comparison to the single-shell model for the Indian region.
Intersite separation (ISS) between two terminals is one of the important parameters required for ... more Intersite separation (ISS) between two terminals is one of the important parameters required for implementation of site diversity (SD), as a fade mitigation technique (FMT), in moderate to heavy rain conditions usually encountered in tropical climates. This paper presents the findings of an experiment during the monsoon periods of years 2007 and 2008. It establishes the existence of micro rain
Future Satellite Based Navigation Systems based on GPS, like US Wide Area Augmentation Sysytem (W... more Future Satellite Based Navigation Systems based on GPS, like US Wide Area Augmentation Sysytem (WAAS), are of global interest to the scientific community. Precise estimation of ionospheric delay is most crucial for successful implementation of the systems. Due to the complex ionospheric structure and large variation of Total Electron Content (TEC) in low latitudes, it is necessary to compare and validate the efficiency of the existing algorithms in this region. In this study, performances of the various interpolation algorithms for TEC calculation at ionospheric grid point (IGP) and user position for gridbased Single Shell Model have been tested for 72 test days of 2005. Based on the results obtained from this analysis, it has been found that, for the Indian region, it would be more suitable to use Ordinary Kriging in place of Planar Fit to estimate delay at an IGP (as used by US WAAS). It has also been found that Ordinary Kriging performs better than the Bilinear Interpolation technique at the user end.
Intersite separation (ISS) between two terminals is one of the important parameters required for ... more Intersite separation (ISS) between two terminals is one of the important parameters required for implementation of site diversity (SD), as a fade mitigation technique (FMT), in moderate to heavy rain conditions usually encountered in tropical climates. This paper presents the findings of an experiment during the monsoon periods of years 2007 and 2008. It establishes the existence of micro rain
The ionosphere acts as a prominent source of range errors for users of Global Positioning System ... more The ionosphere acts as a prominent source of range errors for users of Global Positioning System (GPS) satellite signals requiring accurate position determination. Various models and mathematical formulations have been devised to calculate the absolute range error caused due to ionospheric delay. The present study aims at comparing two methods for calculating delay due to ionosphere: (i) using grid based model at L1 carrier frequency with bilinear interpolation technique; and (ii) using pseudo-range measurements at both L1 and L2 carrier frequency. For analyzing the effect of ionospheric delay on the seasonal behaviour of positional accuracy, a quantitative analysis has been done for all quiet days (Ap index < 50) in 2005 using GPS data for International GNSS Service (IGS) Bangalore (IISc) receiver in January, March and June. Various corrections such as satellite clock bias, transit time, ionospheric delay corrections, etc. are applied to pseudo-ranges to calculate the user coordinates. For single frequency (L1) receivers, ionospheric delay corrections have been applied using IGS total electron content data derived from grid based ionospheric model; and for the dual frequency receivers, pseudorange measurements at L1 and L2 carrier frequencies have been used. It has been observed that there is an improvement of 1-4 m in the standard deviation of position errors when the ionospheric delay correction is applied using pseudo-range measurements at L1 and L2 frequencies (dual frequency receiver) as compared to L1 frequency only. It has also been observed that some residual errors still remain in the estimated user position even after using dual frequency receivers.
In this paper experimental study has been carried out in a cascade greenhouse with inner thermal ... more In this paper experimental study has been carried out in a cascade greenhouse with inner thermal curtain to see the effect of thermal curtain. A thermal model has also been developed to predict the air temperature in a cascade greenhouse. The fan-pad system has been used for ...
In this paper the thermal model given by Ghoshal and Tiwari has been validated by round-the-year ... more In this paper the thermal model given by Ghoshal and Tiwari has been validated by round-the-year experimental work at IIT Delhi, New Delhi (28° 35′N, 77° 12′E), India. The correlation coefficient and root-mean-square percentage deviation have been computed ...
In this paper, a thermal model for heating of greenhouse by using different combinations of inner... more In this paper, a thermal model for heating of greenhouse by using different combinations of inner thermal curtain, an earth-air heat exchanger, and geothermal heating has been developed. The analysis incorporates the study of thermal performance of threezone greenhouse. The calculations have been made for a typical production greenhouse in southern part of Argentina; available climatic data has been used. The thermal performance of a greenhouse having thermal curtain and an earth-air heat exchanger has been compared with a greenhouse having thermal curtain and geothermal energy. It is seen that the fluctuations in temperature in the vicinity of plants are comparable in the two cases. From the results, it is seen that an earth-air heat exchanger might prove an alternative source for heating of greenhouse when geothermal energy is not available. It has also been observed that, the increase in temperature of zone I is more for the greenhouse with geothermal than the greenhouse with an earth-air heat exchanger. r
In this paper an attempt has been made to develop a simple methodology to calculate embodied ener... more In this paper an attempt has been made to develop a simple methodology to calculate embodied energy of the adobe house at Solar Energy Park, Indian Institute of Technology Delhi, New Delhi (28°35′N, 77°12′E) and its effect on the environment. The special feature of the adobe ...
To retrospectively evaluate the diagnostic performance of a serum human tissue kallikrein 11 (hK1... more To retrospectively evaluate the diagnostic performance of a serum human tissue kallikrein 11 (hK11) assay to predict the presence of prostate cancer in a screened population of men with a total prostate-specific antigen (PSA) level between 2.5 and 10.0 ng/mL.
Background: Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of cirrhosis in w... more Background: Hepatopulmonary syndrome (HPS) is a pulmonary vascular complication of cirrhosis in which IPV results in progressive hypoxemia and increases mortality. ET-1 has been identified as a mediator of IPV in an animal model of HPS, but the pathophysiology of human HPS has not been defined. Aim: To assess whether IPV in patients with cirrhosis, which often leads to HPS, is associated with increased HV ET-1. Methods: Prospective cohort study of 40 patients with liver disease undergoing transjugular liver biopsy from 11/1/2008 -8/30/2009. Patients were categorized according to absence (-) or presence (+) of IPV as determined by bubble-contrasted echocardiography. HV blood was sampled for ET-1 assay by ELISA. Demographic and clinical data (including the hepatic venous pressure gradient, HVPG) were collected. Descriptive statistics: Chi-Square, Wilcoxon Rank Sum, and Spearman Correlation. A multivariate logistic regression model was created for IPV using covariates from the univariate analyses. Results: Six subjects without cirrhosis and 1 with patent foramen ovale were excluded. Of the remaining 33 subjects, 17 (52%) women and 16 (48%) men with mean age of 55 yrs ± 10.6 SD; IPV was present in 19 subjects (58%). Median HV ET-1 was higher with IPV(+) than IPV(-): 2.3pg/mL (1.6 -9.2) vs. 9.2pg/mL (7.4 -13.4) respectively, p=0.02. IPV was also associated with higher bilirubin (Bili) and INR, but not creatinine (Cr), MELD, blood pressure (BP), or HVPG . ET-1 was inversely correlated with both systolic (ρ= -0.45, p=0.007 and diastolic (ρ= -0.50, p=0.003) BP, but not with liver dysfunction (Bili, INR, MELD, or HVPG), Cr, or severity of hypoxemia (PaO2). When correcting for Bili and INR by Logistic Regression, higher ET-1 still predicted IPV (OR 1.46, 1.02 -2.07). Conclusion: In human cirrhosis, increased HV ET-1 is associated with IPV. Further studies are needed to better define the hepatic origin of ET-1, its role in IPV, and its utility as a therapeutic target.
According to common criteria, 11 patients were classified as type 1 HRS, 7 patients had type 2 HR... more According to common criteria, 11 patients were classified as type 1 HRS, 7 patients had type 2 HRS. After TIPS, HVPG was effectively reduced in all patients (before TIPS: 22,5 mmHg (SD 5,6); after TIPS 5,5 mmHg (SD 3,4)). No major procedure-related complication was observed. Renal function improved within hospital stay (serum creatinine 3.0 mg/dL (SD 2,7) to 1,9 mg/dL (SD 2,8)). Of all patients, 13 (72,2%) could be discharged from hospital with stable or improved renal function, one of them requiring continued hemodialysis; 5 Patients died (27,8%). Of patients with type 1 HRS, 6 (54,5%) were discharged from hospital whereas 5 (45,5%) died. Of patients with type 2 HRS, 6 (86%) survived, 1 patient (0,14%) died during hospital stay. CONCLUSION: In this retrospective study, transjugular intrahepatic portosystemic shunt has been shown to be able to improve renal function in cirrhotic patients with HRS and is associatited with comparatively low in-hospital mortality.
IEEE Transactions on Geoscience and Remote Sensing, 2009
In the U.S. Wide Area Augmentation System, European Geostationary Navigation Overlay Service, and... more In the U.S. Wide Area Augmentation System, European Geostationary Navigation Overlay Service, and Indian Global Positioning System Aided Geo Augmented Navigation, a near real-time grid-based single-shell model is proposed to correct the ionospheric delay at the user aircrafts. The single-shell model is based on the assumption that the whole ionosphere is compressed at a fixed altitude at 350 km. This assumption may not be appropriate for the Indian region, which falls in the Equatorial Ionospheric Anomaly belt. In this paper, a two-shell model which incorporates two different shells, at 300-and 500-km altitudes, having different weights at different time domains has been implemented. A statistical comparison between single-and two-shell models has been done for all quiet days of year 2005. Based on the results, it is observed that there is at least 60% improvement in the performance of the two-shell model in comparison to the single-shell model for the Indian region.
Intersite separation (ISS) between two terminals is one of the important parameters required for ... more Intersite separation (ISS) between two terminals is one of the important parameters required for implementation of site diversity (SD), as a fade mitigation technique (FMT), in moderate to heavy rain conditions usually encountered in tropical climates. This paper presents the findings of an experiment during the monsoon periods of years 2007 and 2008. It establishes the existence of micro rain
Future Satellite Based Navigation Systems based on GPS, like US Wide Area Augmentation Sysytem (W... more Future Satellite Based Navigation Systems based on GPS, like US Wide Area Augmentation Sysytem (WAAS), are of global interest to the scientific community. Precise estimation of ionospheric delay is most crucial for successful implementation of the systems. Due to the complex ionospheric structure and large variation of Total Electron Content (TEC) in low latitudes, it is necessary to compare and validate the efficiency of the existing algorithms in this region. In this study, performances of the various interpolation algorithms for TEC calculation at ionospheric grid point (IGP) and user position for gridbased Single Shell Model have been tested for 72 test days of 2005. Based on the results obtained from this analysis, it has been found that, for the Indian region, it would be more suitable to use Ordinary Kriging in place of Planar Fit to estimate delay at an IGP (as used by US WAAS). It has also been found that Ordinary Kriging performs better than the Bilinear Interpolation technique at the user end.
Intersite separation (ISS) between two terminals is one of the important parameters required for ... more Intersite separation (ISS) between two terminals is one of the important parameters required for implementation of site diversity (SD), as a fade mitigation technique (FMT), in moderate to heavy rain conditions usually encountered in tropical climates. This paper presents the findings of an experiment during the monsoon periods of years 2007 and 2008. It establishes the existence of micro rain
The ionosphere acts as a prominent source of range errors for users of Global Positioning System ... more The ionosphere acts as a prominent source of range errors for users of Global Positioning System (GPS) satellite signals requiring accurate position determination. Various models and mathematical formulations have been devised to calculate the absolute range error caused due to ionospheric delay. The present study aims at comparing two methods for calculating delay due to ionosphere: (i) using grid based model at L1 carrier frequency with bilinear interpolation technique; and (ii) using pseudo-range measurements at both L1 and L2 carrier frequency. For analyzing the effect of ionospheric delay on the seasonal behaviour of positional accuracy, a quantitative analysis has been done for all quiet days (Ap index < 50) in 2005 using GPS data for International GNSS Service (IGS) Bangalore (IISc) receiver in January, March and June. Various corrections such as satellite clock bias, transit time, ionospheric delay corrections, etc. are applied to pseudo-ranges to calculate the user coordinates. For single frequency (L1) receivers, ionospheric delay corrections have been applied using IGS total electron content data derived from grid based ionospheric model; and for the dual frequency receivers, pseudorange measurements at L1 and L2 carrier frequencies have been used. It has been observed that there is an improvement of 1-4 m in the standard deviation of position errors when the ionospheric delay correction is applied using pseudo-range measurements at L1 and L2 frequencies (dual frequency receiver) as compared to L1 frequency only. It has also been observed that some residual errors still remain in the estimated user position even after using dual frequency receivers.
In this paper experimental study has been carried out in a cascade greenhouse with inner thermal ... more In this paper experimental study has been carried out in a cascade greenhouse with inner thermal curtain to see the effect of thermal curtain. A thermal model has also been developed to predict the air temperature in a cascade greenhouse. The fan-pad system has been used for ...
In this paper the thermal model given by Ghoshal and Tiwari has been validated by round-the-year ... more In this paper the thermal model given by Ghoshal and Tiwari has been validated by round-the-year experimental work at IIT Delhi, New Delhi (28° 35′N, 77° 12′E), India. The correlation coefficient and root-mean-square percentage deviation have been computed ...
In this paper, a thermal model for heating of greenhouse by using different combinations of inner... more In this paper, a thermal model for heating of greenhouse by using different combinations of inner thermal curtain, an earth-air heat exchanger, and geothermal heating has been developed. The analysis incorporates the study of thermal performance of threezone greenhouse. The calculations have been made for a typical production greenhouse in southern part of Argentina; available climatic data has been used. The thermal performance of a greenhouse having thermal curtain and an earth-air heat exchanger has been compared with a greenhouse having thermal curtain and geothermal energy. It is seen that the fluctuations in temperature in the vicinity of plants are comparable in the two cases. From the results, it is seen that an earth-air heat exchanger might prove an alternative source for heating of greenhouse when geothermal energy is not available. It has also been observed that, the increase in temperature of zone I is more for the greenhouse with geothermal than the greenhouse with an earth-air heat exchanger. r
In this paper an attempt has been made to develop a simple methodology to calculate embodied ener... more In this paper an attempt has been made to develop a simple methodology to calculate embodied energy of the adobe house at Solar Energy Park, Indian Institute of Technology Delhi, New Delhi (28°35′N, 77°12′E) and its effect on the environment. The special feature of the adobe ...
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Papers by Ashish Shukla