Bilal Khan - Academia.edu (original) (raw)

Papers by Bilal Khan

JOURNAL OF WEED SCIENCE RESEARCH

Crop plants release biochemicals into surrounding environment that help in obtaining maximum yiel... more Crop plants release biochemicals into surrounding environment that help in obtaining maximum yield of crop by acting bioherbicide at high concentration and plant growth hormone at low concentration. Therefore, this study was planned at Department of Agronomy in Weed Science Laboratory, University of Agriculture Faisalabad during Winter 2018 to evaluate the hermetic effects of Althaea officinalis L. (khatami) on vegetable crop Radish (Raphanus sativus) The experiments were laid out under completely randomized design (CRD) having three replications. The aqueous extracts of A. officinalis L. were used on radish different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%). Data regarding seed germination and seedling growth (shoot length, root length, shoot fresh weight, root dry weigh) of radish were recorded using standard procedures. Results Reveals that the aqueous extract of A. officinalis at higher concentration (80%) act as bioherbicide and produced inhibitory effects on R. sativus...

JOURNAL OF WEED SCIENCE RESEARCH

Crop plants release biochemicals into surrounding environment that help in obtaining maximum yiel... more Crop plants release biochemicals into surrounding environment that help in obtaining maximum yield of crop by acting bioherbicide at high concentration and plant growth hormone at low concentration. Therefore, this study was planned at Department of Agronomy in Weed Science Laboratory, University of Agriculture Faisalabad during Winter 2018 to evaluate the allelopathic effects of A. officinalis on weed Wild Pea (Pisum sativum subsp. elatius). The experiments were laid out under completely randomized design (CRD) having three replications. The aqueous extracts of C. verum. were used on radish and wild pea seeds at different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%). Data regarding seed germination and seedling growth (shoot length, root length, shoot fresh weight, root dry weigh) of weed were recorded following standard procedures. Results Reveals that the aqueous extract of A. officinalis at higher concentration (80%) act as bioherbicide and produced inhibitory effects on R. ...

JOURNAL OF WEED SCIENCE RESEARCH

Weeds are unwanted plants in crop that can be control by different methods among them use of aque... more Weeds are unwanted plants in crop that can be control by different methods among them use of aqueous extract of crop is an imperative method. To investigate the allopathic potential of aqueous extract of winter crop Papavare somniferum (opium) on summer weed Echinochloa cruss-galli (barnyard grass) laboratory experiments were conducted. The experiment coomprised seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different plant parts i.e., leaves, stem and flower of P. somniferumwere. All the tested concentrations and plant parts of P. somniferum significantly reduced mean emergence time, germination index, germination percentage, time to 50% germination as well as well growth of E. cruss-galliweed. However, maximum mean emergence time (9.07 days), time to 50% germination (3.67 days) was noted at leaves and stem extract, respectively. Application of aqueous extract of stem at 8% concentration resulted in greatest time to complete 50% germination (5.42 days) and lowest fresh we...

Energies

The study experimentally investigated a novel approach for producing hydrogen from methane cracki... more The study experimentally investigated a novel approach for producing hydrogen from methane cracking in dielectric barrier discharge catalytic plasma reactor using a nanocatalyst. Plasma-catalytic methane (CH4) cracking was undertaken in a dielectric barrier discharge (DBD) catalytic plasma reactor using Ni/MgAl2O4. The Ni/MgAl2O4 was synthesised through co-precipitation followed customised hydrothermal method. The physicochemical properties of the catalyst were examined using X-ray diffraction (XRD), scanning electron microscopy—energy dispersive X-ray spectrometry (SEM-EDX) and thermogravimetric analysis (TGA). The Ni/MgAl2O4 shows a porous structure spinel MgAl2O4 and thermal stability. In the catalytic-plasma methane cracking, the Ni/MgAl2O4 shows 80% of the maximum conversion of CH4 with H2 selectivity 75%. Furthermore, the stability of the catalyst was encouraging 16 h with CH4 conversion above 75%, and the selectivity of H2 was above 70%. This is attributed to the synergistic ...

Sustainability

A piperazine (PZ)-promoted methyldiethanolamine (MDEA) solution for a carbon dioxide (CO2) remova... more A piperazine (PZ)-promoted methyldiethanolamine (MDEA) solution for a carbon dioxide (CO2) removal process from the flue gas of a large-scale coal power plant has been simulated. An Aspen Plus® was used to perform the simulation process. Initially, the effects of MDEA/PZ concentration ratio and stripper pressure on the regeneration energy of CO2 capture process were investigated. The MDEA/PZ concentration ratio of 35/15 wt.% (35 wt. MDEA and 15 wt.% PZ) was selected as an appropriate concentration. The reboiler duty of 3.235 MJ/kg CO2 was obtained at 35/15 wt.% concentration ratio of MDEA/PZ. It was considered a reference or base case, and process modifications including rich vapor compression (RVC) process, cold solvent split (CSS), and the combination of both processes were investigated to check its effect on the energy requirement. A total equivalent work of 0.7 MJe/kg CO2 in the RVC and a reboiler duty of 2.78 MJ/kg CO2 was achieved in the CSS process. Similarly, the total equiv...

New Journal of Chemistry

High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted sol... more High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted solution-phase method.

American Journal of Ophthalmology Case Reports

We report 2 cases of young diabetic mothers with pre-eclampsia and no previously documented visua... more We report 2 cases of young diabetic mothers with pre-eclampsia and no previously documented visual deficits prior to pregnancy who were found to have profound retinal circulation loss during the postpartum period. Fluorescein angiogram in both cases documented profound ischemia of retinal and macular circulation with resulting severe vision loss, leading to legal blindness. While Pre-eclampsia and Eclampsia are well known clinical entities with potentially grave effects on both the mother and child, there is little information about the possible combined effects of diabetes and Pre-eclampsia/Eclampsia on the retinal circulation. We aim to raise awareness about this devastating association with a need for aggressive monitoring and prompt treatment of similar patients to potentially avoid poor visual outcomes.

Frontiers in physiology, 2018

Hypoglycemia is a profound threat to the brain since glucose is its primary fuel. As a result, gl... more Hypoglycemia is a profound threat to the brain since glucose is its primary fuel. As a result, glucose sensors are widely located in the central nervous system and periphery. In this perspective we will focus on the role of hypothalamic glucose-inhibited (GI) neurons in sensing and correcting hypoglycemia. In particular, we will discuss GI neurons in the ventromedial hypothalamus (VMH) which express neuronal nitric oxide synthase (nNOS) and in the perifornical hypothalamus (PFH) which express orexin. The ability of VMH nNOS-GI neurons to depolarize in low glucose closely parallels the hormonal response to hypoglycemia which stimulates gluconeogenesis. We have found that nitric oxide (NO) production in low glucose is dependent on oxidative status. In this perspective we will discuss the potential relevance of our work showing that enhancing the glutathione antioxidant system prevents hypoglycemia associated autonomic failure (HAAF) in non-diabetic rats whereas VMH overexpression of t...

Bioorganic & medicinal chemistry, Jul 23, 2018

The prime objective of this research work is to prepare readily soluble synthetic analogues of na... more The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, H, C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21-30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior w...

2016 International Conference on Frontiers of Information Technology (FIT), 2016

Organic letters, Mar 14, 2017

A catalyst system composed of [(C6Me6)RuCl2]2, potassium carbonate/guanidine carbonate, and mesit... more A catalyst system composed of [(C6Me6)RuCl2]2, potassium carbonate/guanidine carbonate, and mesitoic acid efficiently promotes the doubly regioselective C-H hydroarylation of unsymmetrical alkynes. The process involves carboxylate-directed ortho-C-H bond activation followed by regioselective addition to the alkyne C-C triple bond with concerted decarboxylation. This action of the carboxylate as a deciduous directing group ensures exclusive monovinylation with high selectivity for the (E)-1,2-diarylalkene.

Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing Connecting the World Wirelessly - IWCMC '09, 2009

In this paper, we present new techniques to detect interposition attacks on stream-based connecti... more In this paper, we present new techniques to detect interposition attacks on stream-based connections in local and wide area networks. The approach developed here is general enough to apply uniformly to all circumstances where the manin-the-middle attacker achieves interposition by corrupting higherlayer to low-layer address mappings. Thus, both the problem of local area network interposition through ARP poisoning, and the problem wide area interposition through DNS poisoning are addressed as special cases of our work. Like other solutions that reside between Layers 3 and 4 (e.g. IPSEC), our techniques enjoy the property that they do not require redesigning legacy software, as is the case for approaches that reside above Layer 4 (e.g. SSL/TLS). Unlike IPSEC, however, the developed system is tailored only to the detection of interposition attacks, and thus circumvents the overhead and complexity introduced in guaranteeing stream confidentiality and integrity. We describe the design of the system, demonstrate its efficacy, and provide a publicly accessible prototype implementation.

PLOS ONE, 2015

Researchers interested in studying populations that are difficult to reach through traditional su... more Researchers interested in studying populations that are difficult to reach through traditional survey methods can now draw on a range of methods to access these populations. Yet many of these methods are more expensive and difficult to implement than studies using conventional sampling frames and trusted sampling methods. The network scale-up method (NSUM) provides a middle ground for researchers who wish to estimate the size of a hidden population, but lack the resources to conduct a more specialized hidden population study. Through this method it is possible to generate population estimates for a wide variety of groups that are perhaps unwilling to self-identify as such (for example, users of illegal drugs or other stigmatized populations) via traditional survey tools such as telephone or mail surveys-by asking a representative sample to estimate the number of people they know who are members of such a "hidden" subpopulation. The original estimator is formulated to minimize the weight a single scaling variable can exert upon the estimates. We argue that this introduces hidden and difficult to predict biases, and instead propose a series of methodological advances on the traditional scale-up estimation procedure, including a new estimator. Additionally, we formalize the incorporation of sample weights into the network scale-up estimation process, and propose a recursive process of back estimation "trimming" to identify and remove poorly performing predictors from the estimation process. To demonstrate these suggestions we use data from a network scale-up mail survey conducted in Nebraska during 2014. We find that using the new estimator and recursive trimming process provides more accurate estimates, especially when used in conjunction with sampling weights.

Procedia Computer Science, 2014

There has been considerable prior research on the biological processes of morphogenesis and cellu... more There has been considerable prior research on the biological processes of morphogenesis and cellular differentiation, and the manner by which these processes give rise to symmetries in biological structures. Here we extend our previous work on thermal robustness and attractor density in cyclic formal Boolean dynamical systems, introducing a new form of spectral analysis on digital organisms at the cellular level. We interpret the phenomena of radial and bilateral symmetry in terms of spatial periodicities in the color sequences, as manifested by an organism while it orbits in its attractors. We provide new results on the influence of various organism properties on its emergent color symmetries-providing initial insights toward an eventual formal understanding of metamerism and Bateson's Rule.

Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing Connecting the World Wirelessly - IWCMC '09, 2009

We present new power distribution schemes on an active route in wireless ad hoc networks, with th... more We present new power distribution schemes on an active route in wireless ad hoc networks, with the objective of maximizing connection lifetime against node mobility. Through experiments with each of the proposed power distribution schemes, we obtain a description of the relationship between control traffic overhead and their expected gains in connection lifetime, as well as an understanding of the influence of various system parameters (e.g. connection size, node density, and power budget size) on this relationship.

2010 The 9th IFIP Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net), 2010

In this research we develop new techniques for optimizing the performance of a reactive routing p... more In this research we develop new techniques for optimizing the performance of a reactive routing protocol in operational environments characterized by high node mobility and long-lived connections. The question we seek to answer is whether in such environments, reactive routing protocols necessarily exhibit a tradeoff between control traffic and route optimality. More specifically, does a protocol which makes use of less control traffic (i.e. better) than standard AODV, necessarily exhibit connection routes that are longer (i.e. worse) than those achieved by standard AODV? We show that the commonly assumed tradeoff can be avoided, and that it is possible to "Have one's cake and eat it too". Towards this, we design an extension of the AODV protocol, and show through extensive ns2 simulation experiments that the new protocol both significantly reduces the control traffic overhead, while simultaneously improving the topological optimality of connections. These remarkable conclusions are seen to continue to hold scalably as one varies situational parameters such as network size, number of connections, and node mobility.

American Heart Journal, 2015

Efficient conduct of clinical trials is essential for the timely generation of critical medical k... more Efficient conduct of clinical trials is essential for the timely generation of critical medical knowledge. We systematically assessed size, duration, enrollment rates, and geographic distribution of randomized cardiovascular trials published between 2001 and 2012 in the 8 highest-impact journals in general medicine and cardiology. Of the 1,224 trials, 27.0% were conducted in North America, 36.5% in Western Europe, and 7.7% in other countries, and 28.8% were multiregional. Trials enrolled a median of 452 patients (interquartile range 167-1,530) in 20 sites (2-76). Median duration was 2.1 (1.3-3.3) years, with an estimated enrollment rate of 1.1 (0.5-3.5) patients/site per month. Between 2001-2003 and 2009-2012, the proportion of North American trials decreased from 34.5% to 25.7% (P = .006), whereas that of multiregional trials (from 26.0% to 30.3%; P = .046) and trials conducted in other countries (from 4.6% to 10.3%; P = .012) increased. Over time, trials involved more patients (from 400 to 500 [median]; P = .032) and sites (from 20 to 22; P = .049), multiregional trials involved more countries (from 12 to 18; P = .031), and enrollment rate declined from 1.2 to 0.9 patients/site per month (P = .017). The proportion of trials meeting their primary end point…

Lecture Notes in Computer Science, 2001

Traditional network management software implementations have used central-ized paradigms based on... more Traditional network management software implementations have used central-ized paradigms based on sNMPv1 or sNMPv2c, or weakly distributed hier-archical paradigms based on sNMPv2, RMON, CMIP, or CMIP derivatives such as TMN [17, p. 5]. While these ...

JOURNAL OF WEED SCIENCE RESEARCH

Crop plants release biochemicals into surrounding environment that help in obtaining maximum yiel... more Crop plants release biochemicals into surrounding environment that help in obtaining maximum yield of crop by acting bioherbicide at high concentration and plant growth hormone at low concentration. Therefore, this study was planned at Department of Agronomy in Weed Science Laboratory, University of Agriculture Faisalabad during Winter 2018 to evaluate the hermetic effects of Althaea officinalis L. (khatami) on vegetable crop Radish (Raphanus sativus) The experiments were laid out under completely randomized design (CRD) having three replications. The aqueous extracts of A. officinalis L. were used on radish different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%). Data regarding seed germination and seedling growth (shoot length, root length, shoot fresh weight, root dry weigh) of radish were recorded using standard procedures. Results Reveals that the aqueous extract of A. officinalis at higher concentration (80%) act as bioherbicide and produced inhibitory effects on R. sativus...

JOURNAL OF WEED SCIENCE RESEARCH

Crop plants release biochemicals into surrounding environment that help in obtaining maximum yiel... more Crop plants release biochemicals into surrounding environment that help in obtaining maximum yield of crop by acting bioherbicide at high concentration and plant growth hormone at low concentration. Therefore, this study was planned at Department of Agronomy in Weed Science Laboratory, University of Agriculture Faisalabad during Winter 2018 to evaluate the allelopathic effects of A. officinalis on weed Wild Pea (Pisum sativum subsp. elatius). The experiments were laid out under completely randomized design (CRD) having three replications. The aqueous extracts of C. verum. were used on radish and wild pea seeds at different concentrations (2.5%, 5%, 10%, 20%, 40% and 80%). Data regarding seed germination and seedling growth (shoot length, root length, shoot fresh weight, root dry weigh) of weed were recorded following standard procedures. Results Reveals that the aqueous extract of A. officinalis at higher concentration (80%) act as bioherbicide and produced inhibitory effects on R. ...

JOURNAL OF WEED SCIENCE RESEARCH

Weeds are unwanted plants in crop that can be control by different methods among them use of aque... more Weeds are unwanted plants in crop that can be control by different methods among them use of aqueous extract of crop is an imperative method. To investigate the allopathic potential of aqueous extract of winter crop Papavare somniferum (opium) on summer weed Echinochloa cruss-galli (barnyard grass) laboratory experiments were conducted. The experiment coomprised seven concentrations (0, 0.25, 0.50, 1, 2, 4, and 8%) of different plant parts i.e., leaves, stem and flower of P. somniferumwere. All the tested concentrations and plant parts of P. somniferum significantly reduced mean emergence time, germination index, germination percentage, time to 50% germination as well as well growth of E. cruss-galliweed. However, maximum mean emergence time (9.07 days), time to 50% germination (3.67 days) was noted at leaves and stem extract, respectively. Application of aqueous extract of stem at 8% concentration resulted in greatest time to complete 50% germination (5.42 days) and lowest fresh we...

Energies

The study experimentally investigated a novel approach for producing hydrogen from methane cracki... more The study experimentally investigated a novel approach for producing hydrogen from methane cracking in dielectric barrier discharge catalytic plasma reactor using a nanocatalyst. Plasma-catalytic methane (CH4) cracking was undertaken in a dielectric barrier discharge (DBD) catalytic plasma reactor using Ni/MgAl2O4. The Ni/MgAl2O4 was synthesised through co-precipitation followed customised hydrothermal method. The physicochemical properties of the catalyst were examined using X-ray diffraction (XRD), scanning electron microscopy—energy dispersive X-ray spectrometry (SEM-EDX) and thermogravimetric analysis (TGA). The Ni/MgAl2O4 shows a porous structure spinel MgAl2O4 and thermal stability. In the catalytic-plasma methane cracking, the Ni/MgAl2O4 shows 80% of the maximum conversion of CH4 with H2 selectivity 75%. Furthermore, the stability of the catalyst was encouraging 16 h with CH4 conversion above 75%, and the selectivity of H2 was above 70%. This is attributed to the synergistic ...

Sustainability

A piperazine (PZ)-promoted methyldiethanolamine (MDEA) solution for a carbon dioxide (CO2) remova... more A piperazine (PZ)-promoted methyldiethanolamine (MDEA) solution for a carbon dioxide (CO2) removal process from the flue gas of a large-scale coal power plant has been simulated. An Aspen Plus® was used to perform the simulation process. Initially, the effects of MDEA/PZ concentration ratio and stripper pressure on the regeneration energy of CO2 capture process were investigated. The MDEA/PZ concentration ratio of 35/15 wt.% (35 wt. MDEA and 15 wt.% PZ) was selected as an appropriate concentration. The reboiler duty of 3.235 MJ/kg CO2 was obtained at 35/15 wt.% concentration ratio of MDEA/PZ. It was considered a reference or base case, and process modifications including rich vapor compression (RVC) process, cold solvent split (CSS), and the combination of both processes were investigated to check its effect on the energy requirement. A total equivalent work of 0.7 MJe/kg CO2 in the RVC and a reboiler duty of 2.78 MJ/kg CO2 was achieved in the CSS process. Similarly, the total equiv...

New Journal of Chemistry

High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted sol... more High-purity anatase nanocrystals were prepared by using a low-temperature surfactant-assisted solution-phase method.

American Journal of Ophthalmology Case Reports

We report 2 cases of young diabetic mothers with pre-eclampsia and no previously documented visua... more We report 2 cases of young diabetic mothers with pre-eclampsia and no previously documented visual deficits prior to pregnancy who were found to have profound retinal circulation loss during the postpartum period. Fluorescein angiogram in both cases documented profound ischemia of retinal and macular circulation with resulting severe vision loss, leading to legal blindness. While Pre-eclampsia and Eclampsia are well known clinical entities with potentially grave effects on both the mother and child, there is little information about the possible combined effects of diabetes and Pre-eclampsia/Eclampsia on the retinal circulation. We aim to raise awareness about this devastating association with a need for aggressive monitoring and prompt treatment of similar patients to potentially avoid poor visual outcomes.

Frontiers in physiology, 2018

Hypoglycemia is a profound threat to the brain since glucose is its primary fuel. As a result, gl... more Hypoglycemia is a profound threat to the brain since glucose is its primary fuel. As a result, glucose sensors are widely located in the central nervous system and periphery. In this perspective we will focus on the role of hypothalamic glucose-inhibited (GI) neurons in sensing and correcting hypoglycemia. In particular, we will discuss GI neurons in the ventromedial hypothalamus (VMH) which express neuronal nitric oxide synthase (nNOS) and in the perifornical hypothalamus (PFH) which express orexin. The ability of VMH nNOS-GI neurons to depolarize in low glucose closely parallels the hormonal response to hypoglycemia which stimulates gluconeogenesis. We have found that nitric oxide (NO) production in low glucose is dependent on oxidative status. In this perspective we will discuss the potential relevance of our work showing that enhancing the glutathione antioxidant system prevents hypoglycemia associated autonomic failure (HAAF) in non-diabetic rats whereas VMH overexpression of t...

Bioorganic & medicinal chemistry, Jul 23, 2018

The prime objective of this research work is to prepare readily soluble synthetic analogues of na... more The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, H, C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21-30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior w...

2016 International Conference on Frontiers of Information Technology (FIT), 2016

Organic letters, Mar 14, 2017

A catalyst system composed of [(C6Me6)RuCl2]2, potassium carbonate/guanidine carbonate, and mesit... more A catalyst system composed of [(C6Me6)RuCl2]2, potassium carbonate/guanidine carbonate, and mesitoic acid efficiently promotes the doubly regioselective C-H hydroarylation of unsymmetrical alkynes. The process involves carboxylate-directed ortho-C-H bond activation followed by regioselective addition to the alkyne C-C triple bond with concerted decarboxylation. This action of the carboxylate as a deciduous directing group ensures exclusive monovinylation with high selectivity for the (E)-1,2-diarylalkene.

Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing Connecting the World Wirelessly - IWCMC '09, 2009

In this paper, we present new techniques to detect interposition attacks on stream-based connecti... more In this paper, we present new techniques to detect interposition attacks on stream-based connections in local and wide area networks. The approach developed here is general enough to apply uniformly to all circumstances where the manin-the-middle attacker achieves interposition by corrupting higherlayer to low-layer address mappings. Thus, both the problem of local area network interposition through ARP poisoning, and the problem wide area interposition through DNS poisoning are addressed as special cases of our work. Like other solutions that reside between Layers 3 and 4 (e.g. IPSEC), our techniques enjoy the property that they do not require redesigning legacy software, as is the case for approaches that reside above Layer 4 (e.g. SSL/TLS). Unlike IPSEC, however, the developed system is tailored only to the detection of interposition attacks, and thus circumvents the overhead and complexity introduced in guaranteeing stream confidentiality and integrity. We describe the design of the system, demonstrate its efficacy, and provide a publicly accessible prototype implementation.

PLOS ONE, 2015

Researchers interested in studying populations that are difficult to reach through traditional su... more Researchers interested in studying populations that are difficult to reach through traditional survey methods can now draw on a range of methods to access these populations. Yet many of these methods are more expensive and difficult to implement than studies using conventional sampling frames and trusted sampling methods. The network scale-up method (NSUM) provides a middle ground for researchers who wish to estimate the size of a hidden population, but lack the resources to conduct a more specialized hidden population study. Through this method it is possible to generate population estimates for a wide variety of groups that are perhaps unwilling to self-identify as such (for example, users of illegal drugs or other stigmatized populations) via traditional survey tools such as telephone or mail surveys-by asking a representative sample to estimate the number of people they know who are members of such a "hidden" subpopulation. The original estimator is formulated to minimize the weight a single scaling variable can exert upon the estimates. We argue that this introduces hidden and difficult to predict biases, and instead propose a series of methodological advances on the traditional scale-up estimation procedure, including a new estimator. Additionally, we formalize the incorporation of sample weights into the network scale-up estimation process, and propose a recursive process of back estimation "trimming" to identify and remove poorly performing predictors from the estimation process. To demonstrate these suggestions we use data from a network scale-up mail survey conducted in Nebraska during 2014. We find that using the new estimator and recursive trimming process provides more accurate estimates, especially when used in conjunction with sampling weights.

Procedia Computer Science, 2014

There has been considerable prior research on the biological processes of morphogenesis and cellu... more There has been considerable prior research on the biological processes of morphogenesis and cellular differentiation, and the manner by which these processes give rise to symmetries in biological structures. Here we extend our previous work on thermal robustness and attractor density in cyclic formal Boolean dynamical systems, introducing a new form of spectral analysis on digital organisms at the cellular level. We interpret the phenomena of radial and bilateral symmetry in terms of spatial periodicities in the color sequences, as manifested by an organism while it orbits in its attractors. We provide new results on the influence of various organism properties on its emergent color symmetries-providing initial insights toward an eventual formal understanding of metamerism and Bateson's Rule.

Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing Connecting the World Wirelessly - IWCMC '09, 2009

We present new power distribution schemes on an active route in wireless ad hoc networks, with th... more We present new power distribution schemes on an active route in wireless ad hoc networks, with the objective of maximizing connection lifetime against node mobility. Through experiments with each of the proposed power distribution schemes, we obtain a description of the relationship between control traffic overhead and their expected gains in connection lifetime, as well as an understanding of the influence of various system parameters (e.g. connection size, node density, and power budget size) on this relationship.

2010 The 9th IFIP Annual Mediterranean Ad Hoc Networking Workshop (Med-Hoc-Net), 2010

In this research we develop new techniques for optimizing the performance of a reactive routing p... more In this research we develop new techniques for optimizing the performance of a reactive routing protocol in operational environments characterized by high node mobility and long-lived connections. The question we seek to answer is whether in such environments, reactive routing protocols necessarily exhibit a tradeoff between control traffic and route optimality. More specifically, does a protocol which makes use of less control traffic (i.e. better) than standard AODV, necessarily exhibit connection routes that are longer (i.e. worse) than those achieved by standard AODV? We show that the commonly assumed tradeoff can be avoided, and that it is possible to "Have one's cake and eat it too". Towards this, we design an extension of the AODV protocol, and show through extensive ns2 simulation experiments that the new protocol both significantly reduces the control traffic overhead, while simultaneously improving the topological optimality of connections. These remarkable conclusions are seen to continue to hold scalably as one varies situational parameters such as network size, number of connections, and node mobility.

American Heart Journal, 2015

Efficient conduct of clinical trials is essential for the timely generation of critical medical k... more Efficient conduct of clinical trials is essential for the timely generation of critical medical knowledge. We systematically assessed size, duration, enrollment rates, and geographic distribution of randomized cardiovascular trials published between 2001 and 2012 in the 8 highest-impact journals in general medicine and cardiology. Of the 1,224 trials, 27.0% were conducted in North America, 36.5% in Western Europe, and 7.7% in other countries, and 28.8% were multiregional. Trials enrolled a median of 452 patients (interquartile range 167-1,530) in 20 sites (2-76). Median duration was 2.1 (1.3-3.3) years, with an estimated enrollment rate of 1.1 (0.5-3.5) patients/site per month. Between 2001-2003 and 2009-2012, the proportion of North American trials decreased from 34.5% to 25.7% (P = .006), whereas that of multiregional trials (from 26.0% to 30.3%; P = .046) and trials conducted in other countries (from 4.6% to 10.3%; P = .012) increased. Over time, trials involved more patients (from 400 to 500 [median]; P = .032) and sites (from 20 to 22; P = .049), multiregional trials involved more countries (from 12 to 18; P = .031), and enrollment rate declined from 1.2 to 0.9 patients/site per month (P = .017). The proportion of trials meeting their primary end point…

Lecture Notes in Computer Science, 2001

Traditional network management software implementations have used central-ized paradigms based on... more Traditional network management software implementations have used central-ized paradigms based on sNMPv1 or sNMPv2c, or weakly distributed hier-archical paradigms based on sNMPv2, RMON, CMIP, or CMIP derivatives such as TMN [17, p. 5]. While these ...