Mark Hodges - Academia.edu (original) (raw)
Papers by Mark Hodges
Journal of Computing Sciences in Colleges, Oct 1, 2013
This study investigates the ability of a system, using sensors to observe the performance of a si... more This study investigates the ability of a system, using sensors to observe the performance of a simple task, to automatically recognize which individuals have a cognitive impairment, such as traumatic brain injury (TBI) or dementia, and which do not. The study uses data collected from five individuals with a cognitive impairment and five unimpaired individuals, and extends previous work that looked only at impaired individuals to assess the severity of their impairments. One of the metrics presented is able to completely separate the impaired individuals from the unimpaired individuals, with statistically significant differences between the two sets of individuals.
Proceedings of the 2004 Congress on Evolutionary Computation (IEEE Cat. No.04TH8753)
This work introduces visualization techniques that allow for a multivariate approach in understan... more This work introduces visualization techniques that allow for a multivariate approach in understanding the dynamics that underlie genetic programming (GP). Emphasis is given toward understanding the relationship between problem difficulty and the loss of diversity. The visualizations raise questions about diversity and problem solving efficacy, as well as the role of the initial population in determining solution outcomes.
Lecture Notes in Computer Science, 2010
Indications of cognitive impairments such as dementia and traumatic brain injury (TBI) are often ... more Indications of cognitive impairments such as dementia and traumatic brain injury (TBI) are often subtle and may be frequently missed by primary care physicians. We describe an experiment where we unobtrusively collected sensor data as individuals with TBI performed a routine daily task (making coffee). We computed a series of four features of the sensor data that were increasingly representative of the task, and that we hypothesized might correlate with severity of cognitive impairment. Our main result is a significant correlation between the most representational feature and an apparent indicator of general neuropsychological integrity, namely, the first principal component of a standard suite of neuropsychological assessments. We also found suggestive but preliminary evidence of correlations between the computed features and a number of the individual tests in the assessment suite; this evidence can be used as the basis of larger-scale studies to validate significance.
Health Libraries Review, 1991
Tetrahedron Letters, 1998
The outcome of rhodium(II) pivalate catalyzed decomposition of diaozoacetates in the presence of ... more The outcome of rhodium(II) pivalate catalyzed decomposition of diaozoacetates in the presence of cyclohexane is highly dependent on carbenoid structure. Carbenoids derived from phenyldiazoacetates or diazoketoesters undergo high yielding intermolecular C-H insertions while other carbenoid systems undergo rearrangements, dimerization or trimerization.
Synapse, 2000
A series of PET imaging studies were conducted with two fluorine-18-labeled tropane analoges, [(1... more A series of PET imaging studies were conducted with two fluorine-18-labeled tropane analoges, [(18)F](+)-FTT and [(18)F](+)-FCT. Both compounds possessed a high affinity and selectivity for the dopamine transporter and had a higher accumulation in the basal ganglia, a brain region having a high density of the dopamine transporter (DAT) than the cerebellum, a reference region devoid of dopaminergic terminals. [(18)F](+)-FCT had a higher brain uptake and more suitable basal ganglia:cerebellum (BG:Cb) ratio than [(18)F](+)-FTT. [(18)F](+)-FCT also displayed reversible binding kinetics in vivo, indicating that the measurement of DAT density in vivo with PET will be relatively insensitive to changes in cerebral blood flow that can occur as a consequence of disease or prolonged cocaine abuse. The uptake of [(18)F](+)-FCT was also displaced by an intravenous injection of cocaine (1.0 mg/kg), which is consistent with the labeling of the DAT in vivo by this radiotracer. These data suggest that [(18)F](+)-FCT may be a suitable radiotracer for studying DAT function in vivo with PET.
Psychopharmacology, 1999
Rationale: A novel scheme for the synthesis of cocaine analogs from vinylcarbenoid precursors has... more Rationale: A novel scheme for the synthesis of cocaine analogs from vinylcarbenoid precursors has made available compounds that have a diverse range of affinities for the DA and 5-HT transporters. These compounds were used to explore the relationship between their biochemical properties and their reinforcing effects. Objectives: The objective was to assess the reinforcing efficacy of selected cocaine analogs and compare the results with their selectivity in binding to DA and 5-HT transporters. Methods: Rats were prepared with chronically indwelling intravenous cannulae and trained to self-administer cocaine on a progressive ratio (PR) schedule. A range of doses of seven cocaine analogs were substituted for cocaine in separate groups of animals. Results: The results demonstrate a wide range of reinforcing efficacies and potencies among the seven selected drugs. Four tropane analogs (WF-11, WF-23, WF-24, WF-55) were found to support self-administration behavior on a PR schedule while three did not (WF-31, WF-54 and WF-60). The DA/5-HT selectivity ratio was found to be a better predictor of self-administration behavior than affinity at the DA transporter alone. Conclusion: These data suggest that drugs with a higher affinity for the DA versus the 5-HT transporter are more likely to be self-administered.
Crop Science, 1997
Maize (Zea mays L.), one of the most economically important plants grown in North America, is oft... more Maize (Zea mays L.), one of the most economically important plants grown in North America, is often subjected to cool conditions soon after sowing which can disrupt development. No studies on chilling sensitivity of maize at both germination and early growth developmental stages have been reported. To discern differences in chilling sensitivity between the germination and early growth phases, twelve hybrids originating from a complete diailel of four inbreds which differed in their sensitivity to chilling were subjected to laboratory screening tests at both these stages. Corresponding field trials were sown and parameters refiecting those evaluated in the laboratory were assessed. Estimates of general combining abilities and specific combining abilities were performed. Some lines that were initally chilling sensitive or tolerant at the germination stage altered their sensitivity to chilling at the early growth stage. This suggests that it is only possible to accurately evaluate chilling tolerance of maize by examining plants at both the germination-emergence and early growth stages as these two stages may be under the control of different genetic factors. Furthermore, based on the physiological growth parameters assessed both in the laboratory and in the field, it is not possible to reliably predict hybrid maize cold tolerance from knowledge of the inbreds' responses. M AIZE is an economically important crop, but as it is of subtropical origin, chilling temperatures are a major environmental constraint that limits its range of adaptation (Cutworth and Shaykewich, 1990; Koscielniak, 1993). The introduction of maize with high potentials of emergence and growth in cold soils has long been an important objective of maize breeders in temperate regions with short growing seasons (Eagles and Brooking, 1981). Chilling sensitive plants such as maize can exhibit several observable characteristics of chilling stress. Examples of such are reduced germination-emergence and increased time taken to germinate-emerge (Eagles and
Crop Science, 1997
Chilling sensitive species often have lower antioxidant capacities than do tolerant species. This... more Chilling sensitive species often have lower antioxidant capacities than do tolerant species. This study was conducted to determine if antioxidant capacities and carbohydrate concentrations would be usefui in a proposed screening technique for chilling sensitivity in maize (Zea mays L.). Leaves of 12 maize hybrids exhibiting differential sensitivity to chilling were harvested at the third-leaf stage under either (i) a constant 25°C control regime or (ii) the control regime plus a short-term chilling shock of 11°C for 1 d prior to harvesting. Catalase (CAT; EC 1.11.1.6), monodehydroascorbate reductase (MDHAR; EC 1.6.5.4), and ascorbate peroxidase (ASPX; EC 1.11.1.11) activities were assessed. Carbohydrate levels were determined as general metabolic indicators of chilling stress. The chill/ control ratios of CAT, MDHAR, and ASPX were lowest and concentrations of carbohydrates highest in the most chilling sensitive hybrids. Differences between hybrids in antioxidant capacities to detoxify toxic oxygen compounds may be important in differential chilling sensitivity. The higher chili/control ratios of carbohydrates in the sensitive hybrids after chilling indicated that their rate of assimilate utilization was reduced by the chilling treatment more so than those of the chilling tolerant hybrids. Activities of CAT, MDHAR, and ASPX and concentrations of carbohydrates would thus make excellent indicators of chilling stress in a screening technique for chilling sensitivity of maize. EXl~,OSU~a~ to sub-optimal chilling temperatures may ead to an increased proliferation of toxic oxygen compounds present in chilling sensitive plants such as maize. These toxic oxygen byproducts, such as superoxide (O~-), hydrogen peroxide (H202), and the hydroxyl radical (. OH), may be produced under low temperatures due to chilling-induced photoinhibition (Hodgson and
Computer Methods and Programs in Biomedicine, 1994
Opened in March 1994, the new library at Vanderbilt was planned to be at the intellectual and geo... more Opened in March 1994, the new library at Vanderbilt was planned to be at the intellectual and geographical heart of the medical center. Constructed of white precast blocks with a glass curtain wall, the building cost $12.5 million. Under an integrated advanced information management system (IAIMS) initiative, the building includes a center for biomedical informatics, which serves as the nerve center of the information enterprise at the medical center. Floor by floor descriptions are provided, including such design details as placing workstations directly inside the first floor entrance, a measure thought to contribute to increased use of the medical center network. User reaction to the building was highly positive in the first month of operation.
Chest, 1998
Study objectives: Reversible myocardial contraction abnormalities are usually observed in patient... more Study objectives: Reversible myocardial contraction abnormalities are usually observed in patients with acute ischemic syndromes caused by coronary artery disease. In this study, we report the occurrence of reversible anterior-apical contraction abnormalities in patients with an acute noncardiac illness. Setting: This was a retrospective study of 22 patients with the following characteristics: (I) hospitalization for an acute noncardiac illness; (2) appearance of deep T-wave inversion in the precordial leads of the ECG; and (3) presence of an anterior wall motion abnormality on an echocardiogram. Standard clinical information was collected together with results of serial ECGs, echocardiograms, and coronary angiograms. Results: The primary diagnoses for the 22 acutely ill patients included CNS injury (n=6); sepsis (n=3); acute pulmonary disease (n=3); drug overdose or metabolic abnormality (n=7); and post noncardiac surgery (n=3). An initial echocardiogram revealed an anterior apical wall motion abnormality. At follow-up, all patients had progressive improvement in anterior wall motion with return of normal wall motion in 16 patients (73%). All patients evolved deep T-wave inversion (average, 7.8 mm) and QT interval lengthening in the precordial leads. Coronary angiography revealed a significant stenosis in the likely culprit artery (left anterior descending) in only one patient. Conclusion: A reversible cardiac contraction abnormality of the anterior wall and apex of the left ventricle can complicate the clinical course of critically ill patients in the absence of significant coronary artery disease. This phenomenon is associated with striking T-wave inversion and QT interval lengthening. Mechanisms other than myocardial ischemia may lead to the occurrence of reversible regional myocardial contraction abnormalities.
Journal of Computing Sciences in Colleges, Oct 1, 2013
This study investigates the ability of a system, using sensors to observe the performance of a si... more This study investigates the ability of a system, using sensors to observe the performance of a simple task, to automatically recognize which individuals have a cognitive impairment, such as traumatic brain injury (TBI) or dementia, and which do not. The study uses data collected from five individuals with a cognitive impairment and five unimpaired individuals, and extends previous work that looked only at impaired individuals to assess the severity of their impairments. One of the metrics presented is able to completely separate the impaired individuals from the unimpaired individuals, with statistically significant differences between the two sets of individuals.
Proceedings of the 2004 Congress on Evolutionary Computation (IEEE Cat. No.04TH8753)
This work introduces visualization techniques that allow for a multivariate approach in understan... more This work introduces visualization techniques that allow for a multivariate approach in understanding the dynamics that underlie genetic programming (GP). Emphasis is given toward understanding the relationship between problem difficulty and the loss of diversity. The visualizations raise questions about diversity and problem solving efficacy, as well as the role of the initial population in determining solution outcomes.
Lecture Notes in Computer Science, 2010
Indications of cognitive impairments such as dementia and traumatic brain injury (TBI) are often ... more Indications of cognitive impairments such as dementia and traumatic brain injury (TBI) are often subtle and may be frequently missed by primary care physicians. We describe an experiment where we unobtrusively collected sensor data as individuals with TBI performed a routine daily task (making coffee). We computed a series of four features of the sensor data that were increasingly representative of the task, and that we hypothesized might correlate with severity of cognitive impairment. Our main result is a significant correlation between the most representational feature and an apparent indicator of general neuropsychological integrity, namely, the first principal component of a standard suite of neuropsychological assessments. We also found suggestive but preliminary evidence of correlations between the computed features and a number of the individual tests in the assessment suite; this evidence can be used as the basis of larger-scale studies to validate significance.
Health Libraries Review, 1991
Tetrahedron Letters, 1998
The outcome of rhodium(II) pivalate catalyzed decomposition of diaozoacetates in the presence of ... more The outcome of rhodium(II) pivalate catalyzed decomposition of diaozoacetates in the presence of cyclohexane is highly dependent on carbenoid structure. Carbenoids derived from phenyldiazoacetates or diazoketoesters undergo high yielding intermolecular C-H insertions while other carbenoid systems undergo rearrangements, dimerization or trimerization.
Synapse, 2000
A series of PET imaging studies were conducted with two fluorine-18-labeled tropane analoges, [(1... more A series of PET imaging studies were conducted with two fluorine-18-labeled tropane analoges, [(18)F](+)-FTT and [(18)F](+)-FCT. Both compounds possessed a high affinity and selectivity for the dopamine transporter and had a higher accumulation in the basal ganglia, a brain region having a high density of the dopamine transporter (DAT) than the cerebellum, a reference region devoid of dopaminergic terminals. [(18)F](+)-FCT had a higher brain uptake and more suitable basal ganglia:cerebellum (BG:Cb) ratio than [(18)F](+)-FTT. [(18)F](+)-FCT also displayed reversible binding kinetics in vivo, indicating that the measurement of DAT density in vivo with PET will be relatively insensitive to changes in cerebral blood flow that can occur as a consequence of disease or prolonged cocaine abuse. The uptake of [(18)F](+)-FCT was also displaced by an intravenous injection of cocaine (1.0 mg/kg), which is consistent with the labeling of the DAT in vivo by this radiotracer. These data suggest that [(18)F](+)-FCT may be a suitable radiotracer for studying DAT function in vivo with PET.
Psychopharmacology, 1999
Rationale: A novel scheme for the synthesis of cocaine analogs from vinylcarbenoid precursors has... more Rationale: A novel scheme for the synthesis of cocaine analogs from vinylcarbenoid precursors has made available compounds that have a diverse range of affinities for the DA and 5-HT transporters. These compounds were used to explore the relationship between their biochemical properties and their reinforcing effects. Objectives: The objective was to assess the reinforcing efficacy of selected cocaine analogs and compare the results with their selectivity in binding to DA and 5-HT transporters. Methods: Rats were prepared with chronically indwelling intravenous cannulae and trained to self-administer cocaine on a progressive ratio (PR) schedule. A range of doses of seven cocaine analogs were substituted for cocaine in separate groups of animals. Results: The results demonstrate a wide range of reinforcing efficacies and potencies among the seven selected drugs. Four tropane analogs (WF-11, WF-23, WF-24, WF-55) were found to support self-administration behavior on a PR schedule while three did not (WF-31, WF-54 and WF-60). The DA/5-HT selectivity ratio was found to be a better predictor of self-administration behavior than affinity at the DA transporter alone. Conclusion: These data suggest that drugs with a higher affinity for the DA versus the 5-HT transporter are more likely to be self-administered.
Crop Science, 1997
Maize (Zea mays L.), one of the most economically important plants grown in North America, is oft... more Maize (Zea mays L.), one of the most economically important plants grown in North America, is often subjected to cool conditions soon after sowing which can disrupt development. No studies on chilling sensitivity of maize at both germination and early growth developmental stages have been reported. To discern differences in chilling sensitivity between the germination and early growth phases, twelve hybrids originating from a complete diailel of four inbreds which differed in their sensitivity to chilling were subjected to laboratory screening tests at both these stages. Corresponding field trials were sown and parameters refiecting those evaluated in the laboratory were assessed. Estimates of general combining abilities and specific combining abilities were performed. Some lines that were initally chilling sensitive or tolerant at the germination stage altered their sensitivity to chilling at the early growth stage. This suggests that it is only possible to accurately evaluate chilling tolerance of maize by examining plants at both the germination-emergence and early growth stages as these two stages may be under the control of different genetic factors. Furthermore, based on the physiological growth parameters assessed both in the laboratory and in the field, it is not possible to reliably predict hybrid maize cold tolerance from knowledge of the inbreds' responses. M AIZE is an economically important crop, but as it is of subtropical origin, chilling temperatures are a major environmental constraint that limits its range of adaptation (Cutworth and Shaykewich, 1990; Koscielniak, 1993). The introduction of maize with high potentials of emergence and growth in cold soils has long been an important objective of maize breeders in temperate regions with short growing seasons (Eagles and Brooking, 1981). Chilling sensitive plants such as maize can exhibit several observable characteristics of chilling stress. Examples of such are reduced germination-emergence and increased time taken to germinate-emerge (Eagles and
Crop Science, 1997
Chilling sensitive species often have lower antioxidant capacities than do tolerant species. This... more Chilling sensitive species often have lower antioxidant capacities than do tolerant species. This study was conducted to determine if antioxidant capacities and carbohydrate concentrations would be usefui in a proposed screening technique for chilling sensitivity in maize (Zea mays L.). Leaves of 12 maize hybrids exhibiting differential sensitivity to chilling were harvested at the third-leaf stage under either (i) a constant 25°C control regime or (ii) the control regime plus a short-term chilling shock of 11°C for 1 d prior to harvesting. Catalase (CAT; EC 1.11.1.6), monodehydroascorbate reductase (MDHAR; EC 1.6.5.4), and ascorbate peroxidase (ASPX; EC 1.11.1.11) activities were assessed. Carbohydrate levels were determined as general metabolic indicators of chilling stress. The chill/ control ratios of CAT, MDHAR, and ASPX were lowest and concentrations of carbohydrates highest in the most chilling sensitive hybrids. Differences between hybrids in antioxidant capacities to detoxify toxic oxygen compounds may be important in differential chilling sensitivity. The higher chili/control ratios of carbohydrates in the sensitive hybrids after chilling indicated that their rate of assimilate utilization was reduced by the chilling treatment more so than those of the chilling tolerant hybrids. Activities of CAT, MDHAR, and ASPX and concentrations of carbohydrates would thus make excellent indicators of chilling stress in a screening technique for chilling sensitivity of maize. EXl~,OSU~a~ to sub-optimal chilling temperatures may ead to an increased proliferation of toxic oxygen compounds present in chilling sensitive plants such as maize. These toxic oxygen byproducts, such as superoxide (O~-), hydrogen peroxide (H202), and the hydroxyl radical (. OH), may be produced under low temperatures due to chilling-induced photoinhibition (Hodgson and
Computer Methods and Programs in Biomedicine, 1994
Opened in March 1994, the new library at Vanderbilt was planned to be at the intellectual and geo... more Opened in March 1994, the new library at Vanderbilt was planned to be at the intellectual and geographical heart of the medical center. Constructed of white precast blocks with a glass curtain wall, the building cost $12.5 million. Under an integrated advanced information management system (IAIMS) initiative, the building includes a center for biomedical informatics, which serves as the nerve center of the information enterprise at the medical center. Floor by floor descriptions are provided, including such design details as placing workstations directly inside the first floor entrance, a measure thought to contribute to increased use of the medical center network. User reaction to the building was highly positive in the first month of operation.
Chest, 1998
Study objectives: Reversible myocardial contraction abnormalities are usually observed in patient... more Study objectives: Reversible myocardial contraction abnormalities are usually observed in patients with acute ischemic syndromes caused by coronary artery disease. In this study, we report the occurrence of reversible anterior-apical contraction abnormalities in patients with an acute noncardiac illness. Setting: This was a retrospective study of 22 patients with the following characteristics: (I) hospitalization for an acute noncardiac illness; (2) appearance of deep T-wave inversion in the precordial leads of the ECG; and (3) presence of an anterior wall motion abnormality on an echocardiogram. Standard clinical information was collected together with results of serial ECGs, echocardiograms, and coronary angiograms. Results: The primary diagnoses for the 22 acutely ill patients included CNS injury (n=6); sepsis (n=3); acute pulmonary disease (n=3); drug overdose or metabolic abnormality (n=7); and post noncardiac surgery (n=3). An initial echocardiogram revealed an anterior apical wall motion abnormality. At follow-up, all patients had progressive improvement in anterior wall motion with return of normal wall motion in 16 patients (73%). All patients evolved deep T-wave inversion (average, 7.8 mm) and QT interval lengthening in the precordial leads. Coronary angiography revealed a significant stenosis in the likely culprit artery (left anterior descending) in only one patient. Conclusion: A reversible cardiac contraction abnormality of the anterior wall and apex of the left ventricle can complicate the clinical course of critically ill patients in the absence of significant coronary artery disease. This phenomenon is associated with striking T-wave inversion and QT interval lengthening. Mechanisms other than myocardial ischemia may lead to the occurrence of reversible regional myocardial contraction abnormalities.