The hormone leptin controls food intake and body weight through its receptor in the hypothalamus,... more The hormone leptin controls food intake and body weight through its receptor in the hypothalamus, and may modulate physiological functions such as reproduction, sleep or circadian timing. In the present study, the effects of leptin on the resetting of the circadian clock, the hypothalamic suprachiasmatic nucleus (SCN) and on the activity of the hypocretinergic system were examined in vivo, with comparative analysis between male and female mice. A single leptin injection (5 mg/kg) at both the onset and offset of the activity period did not alter locomotion of mice housed under a 12 : 12 h light/dark cycle and did not shift the circadian behavioral rhythm of mice housed in constant darkness. By contrast, leptin potentiated the phase-shifting effect of a 30-min light-pulse on behavioural rhythms during the late subjective night, although only in females. This was accompanied by a higher induction of the clock genes Per1 and Per2 in the SCN. A 2-week chronic exposure to a physiological dose of leptin (100 μg/kg per day) decreased locomotor activity, expression of hypocretin receptor 1 and 2, as well as the number of hypocretin-immunoreactive neurones only in female mice, whereas the number of c-fos-positive hypocretinergic neurones was reduced in both genders. These results highlight a dimorphic effect of leptin on the hypocretinergic system and on the response of the circadian clock to light. Leptin may thus modulate the sleep/wake cycle and circadian system beside its well-established action on food intake and regulation of body weight.
The surface recombination velocity at the AlGaAs/GaAs single heterostructure interface is determi... more The surface recombination velocity at the AlGaAs/GaAs single heterostructure interface is determined using the photoacoustic technique. We analyze different heat generation mechanisms for this type of heterostructure with different Al composition and thickness of the AlGaAs layers. A theoretical model of the photoacoustic signal generation in the heat transmission detection configuration was developed. The values of the surface recombination velocity obtained by comparing the theoretical expressions with the experimental results are in good agreement with the literature reported ones. The results were also correlated with those of photoluminescence measurements in the same samples.
The Multi-Compartment Vehicle Routing Problem (MC-VRP) consists of designing transportation route... more The Multi-Compartment Vehicle Routing Problem (MC-VRP) consists of designing transportation routes to satisfy the demands of a set of costumers for several products that because of incompatibility constraints must be loaded on independent vehicle compartments. Despite its wide practical applicability the MC-VRP has not received much attention in the literature, and the few existing methods assume perfect knowledge of the customer demands, regardless of their stochastic nature. This paper extends the MC-VRP by introducing uncertainty on what it is known as the MC-VRP with stochastic demands (MC-VRPSD). The MC-VRPSD is modeled as a stochastic program with recourse and solved by means of a memetic algorithm. The proposed algorithm couples genetic operators and local search procedures proven to be effective on deterministic routing problems with a novel individual evaluation and reparation strategy that accounts for the stochastic nature of the problem. The algorithm was tested on instances of up to 241 customers adapted from the literature, and its results were compared to those obtained by a construction heuristic and a deterministic approach based on real-world practices arising in the dairy industry.
1. Med Clin (Barc). 2006 Feb 18;126(6):220-2. [Transient elastography (Fibroscan), a new non-inva... more 1. Med Clin (Barc). 2006 Feb 18;126(6):220-2. [Transient elastography (Fibroscan), a new non-invasive method to evaluate hepatic fibrosis]. [Article in Spanish]. Mendoza J, Gómez-Domínguez E, Moreno-Otero R. Servicio de ...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 3, 2010
The cerebellum participates in motor coordination as well as in numerous cerebral processes, incl... more The cerebellum participates in motor coordination as well as in numerous cerebral processes, including temporal discrimination. Animals can predict daily timing of food availability, as manifested by food-anticipatory activity under restricted feeding. By studying ex vivo clock gene expression by in situ hybridization and recording in vitro Per1-luciferase bioluminescence, we report that the cerebellum contains a circadian oscillator sensitive to feeding cues (i.e., whose clock gene oscillations are shifted in response to restricted feeding). Food-anticipatory activity was markedly reduced in mice injected intracerebroventricularly with an immunotoxin that depletes Purkinje cells (i.e., OX7-saporin). Mice bearing the hotfoot mutation (i.e., Grid2 ho/ho ) have impaired cerebellar circuitry and mild ataxic phenotype. Grid2 ho/ho mice fed ad libitum showed regular behavioral rhythms and day-night variations of clock gene expression in the hypothalamus and cerebellum. When challenged with restricted feeding, however, Grid2 ho/ho mice did not show any food-anticipatory rhythms, nor timed feeding-induced changes in cerebellar clock gene expression. In hypothalamic arcuate and dorsomedial nuclei, however, shifts in Per1 expression in response to restricted feeding were similar in cerebellar mutant and wild-type mice. Furthermore, plasma corticosterone and metabolites before mealtime did not differ between cerebellar mutant and wild-type mice. Together, these data define a role for the cerebellum in the circadian timing network and indicate that the cerebellar oscillator is required for anticipation of mealtime. ) for their generous supply of hotfoot mice and to Dr. Stéphane Heitz for taking care of the breeding colony of this cerebellar mutant line. We thank Prof. M. Menaker (University of Virginia, Charlottesville, VA) for his generous gift of Per1:luc rats. The plasmids for synthesis of Per1 and
A procedure that utilizes the sample multiple correlation to form a lower bound for the level of ... more A procedure that utilizes the sample multiple correlation to form a lower bound for the level of predictive precision of a fitted regression equation is suggested. The procedure is shown to yield probability statements which are true at least 100(1 --a)% of the time.
The paper obtains a maximum likelihood criterion test for multisample sphericity. The test contai... more The paper obtains a maximum likelihood criterion test for multisample sphericity. The test contains Mauchly's sphericity test as a special case.
The validity of a test is often estimated in a nonrandom sample of selected individuals. To accur... more The validity of a test is often estimated in a nonrandom sample of selected individuals. To accurately estimate the relation between the predictor and the criterion we correct this correlation for range restriction. Unfortunately, this corrected correlation cannot be transformed using Fisher's Z transformation, and asymptotic tests of hypotheses based on small or moderate samples are not accurate. We developed a Fisher r to Z transformation for the corrected correlation for each of two conditions: (a) the criterion data were missing due to selection on the predictor (the missing data were MAR); and (b) the criterion was missing at random, not due to selection (the missing data were MCAR). The two Z transformations were evaluated in a computer simulation. The transformations were accurate, and tests of hypotheses and confidence intervals based on the transformations were superior to those that were not based on the transformations.
Corrections of correlations for range restriction (i.e., selection) and unreliability are common ... more Corrections of correlations for range restriction (i.e., selection) and unreliability are common in psychometric work. The current rule of thumb for determining the order in which to apply these corrections looks to the nature of the reliability estimate (i.e., restricted or unrestricted). While intuitive, this rule of thumb is untenable when the correction includes the variable upon which selection is made, as is generally the case. Using classical test theory, we show that it is the nature of the range restriction, not the nature of the available reliability coefficient, that determines the sequence for applying corrections for range restriction and unreliability.
Corrections of correlations for range restriction (i.e., selection) and unreliability are common ... more Corrections of correlations for range restriction (i.e., selection) and unreliability are common in psychometric work. The current rule of thumb for determining the order in which to apply these corrections looks to the nature of the reliability estimate (i.e., restricted or unrestricted). While intuitive, this rule of thumb is untenable when the correction includes the variable upon which selection is made, as is generally the case. Using classical test theory, we show that it is the nature of the range restriction, not the nature of the available reliability coefficient, that determines the sequence for applying corrections for range restriction and unreliability.
Large-sample confidence intervals (CI) for reliability, validity, and unattenuated validity are p... more Large-sample confidence intervals (CI) for reliability, validity, and unattenuated validity are presented. The CI for unattenuated validity is based on the Bonferroni inequality, which relies on one CI for test-retest reliability and one for validity. Covered are four reliability-validity situations: (a) both estimates were from random samples; (b) reliability was from a random sample but validity was from a selected sample; (c) validity was from a random sample but reliability was from a selected sample; and (d) both estimates were from selected samples. All CIs were evaluated by using a simulation. CIs on reliability, validity, or unattenuated validity are accurate as long as selection ratio is at least 20% and selected sample size is 100 or larger. When selection ratio is less than 20%, estimators tend to underestimate their parameters.
Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psych... more Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psychological Association, Inc. 0033-2909/82/9202-0532S00.75 The Statistical Analysis of Dyadic Social Behavior: A Multivariate Approach ...
Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psych... more Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psychological Association, Inc. 0033-2909/82/9202-0532S00.75 The Statistical Analysis of Dyadic Social Behavior: A Multivariate Approach ...
Page 1. Psychological Bulletin 1991,\fol. 110, No. 3, 596-610 Copyright 1991 by the American Psyc... more Page 1. Psychological Bulletin 1991,\fol. 110, No. 3, 596-610 Copyright 1991 by the American Psychological Association, Inc. 0033-2909/91/J3.00 Validity Generalization Procedures Using Sample-Based Estimates: A Comparison of Six Procedures ...
A MONTE CARLO COMPARISON OF THE UNIVARIATE AND MULTIVARIATE METHODS FOR THE GROUPS BY TRIALS REPE... more A MONTE CARLO COMPARISON OF THE UNIVARIATE AND MULTIVARIATE METHODS FOR THE GROUPS BY TRIALS REPEATED MEASURES DESIGN ... JORGE L. MENDOZA, LARRY E. TOOTHAKER and W. ALAN NICEWANDER The University of Oklahoma
Under special restricted feeding conditions the mammalian circadian clock, contained in the hypot... more Under special restricted feeding conditions the mammalian circadian clock, contained in the hypothalamic suprachiasmatic nucleus (SCN), can be entrained by food. During food restriction, hungry animals are very motivated to obtain food. This motivational state could be a key component in altering the SCN timing by feeding. In order to comprehend how hedonic signals of food affect the SCN clock, we evaluated the effects of a daily palatable snack on the behavioural rhythm of mice fed ad libitum with regular food, and housed under constant darkness conditions. As light synchronization of the SCN is modulated by feeding/metabolic cues, the effects of a palatable meal coupled to a light pulse were tested on behavioural and molecular rhythms. A daily palatable snack entrained behavioural rhythms of mice in constant darkness conditions. Furthermore, palatable meal access at the activity onset reduced light-induced behavioural phase-delays and Period genes expression in the SCN. In addition, an increase in the dopamine content and Period genes expression in the forebrain of mice was observed, concomitant with a c-FOS activation in dopaminergic and orexinergic neurons, suggesting that the effects of a palatable snack on the SCN clock are mediated by the reward/arousal central systems. In conclusion, this study establishes an underlying sensitivity of the master circadian clock to changes in motivational states related to palatable food intake.
The hormone leptin controls food intake and body weight through its receptor in the hypothalamus,... more The hormone leptin controls food intake and body weight through its receptor in the hypothalamus, and may modulate physiological functions such as reproduction, sleep or circadian timing. In the present study, the effects of leptin on the resetting of the circadian clock, the hypothalamic suprachiasmatic nucleus (SCN) and on the activity of the hypocretinergic system were examined in vivo, with comparative analysis between male and female mice. A single leptin injection (5 mg/kg) at both the onset and offset of the activity period did not alter locomotion of mice housed under a 12 : 12 h light/dark cycle and did not shift the circadian behavioral rhythm of mice housed in constant darkness. By contrast, leptin potentiated the phase-shifting effect of a 30-min light-pulse on behavioural rhythms during the late subjective night, although only in females. This was accompanied by a higher induction of the clock genes Per1 and Per2 in the SCN. A 2-week chronic exposure to a physiological dose of leptin (100 μg/kg per day) decreased locomotor activity, expression of hypocretin receptor 1 and 2, as well as the number of hypocretin-immunoreactive neurones only in female mice, whereas the number of c-fos-positive hypocretinergic neurones was reduced in both genders. These results highlight a dimorphic effect of leptin on the hypocretinergic system and on the response of the circadian clock to light. Leptin may thus modulate the sleep/wake cycle and circadian system beside its well-established action on food intake and regulation of body weight.
The surface recombination velocity at the AlGaAs/GaAs single heterostructure interface is determi... more The surface recombination velocity at the AlGaAs/GaAs single heterostructure interface is determined using the photoacoustic technique. We analyze different heat generation mechanisms for this type of heterostructure with different Al composition and thickness of the AlGaAs layers. A theoretical model of the photoacoustic signal generation in the heat transmission detection configuration was developed. The values of the surface recombination velocity obtained by comparing the theoretical expressions with the experimental results are in good agreement with the literature reported ones. The results were also correlated with those of photoluminescence measurements in the same samples.
The Multi-Compartment Vehicle Routing Problem (MC-VRP) consists of designing transportation route... more The Multi-Compartment Vehicle Routing Problem (MC-VRP) consists of designing transportation routes to satisfy the demands of a set of costumers for several products that because of incompatibility constraints must be loaded on independent vehicle compartments. Despite its wide practical applicability the MC-VRP has not received much attention in the literature, and the few existing methods assume perfect knowledge of the customer demands, regardless of their stochastic nature. This paper extends the MC-VRP by introducing uncertainty on what it is known as the MC-VRP with stochastic demands (MC-VRPSD). The MC-VRPSD is modeled as a stochastic program with recourse and solved by means of a memetic algorithm. The proposed algorithm couples genetic operators and local search procedures proven to be effective on deterministic routing problems with a novel individual evaluation and reparation strategy that accounts for the stochastic nature of the problem. The algorithm was tested on instances of up to 241 customers adapted from the literature, and its results were compared to those obtained by a construction heuristic and a deterministic approach based on real-world practices arising in the dairy industry.
1. Med Clin (Barc). 2006 Feb 18;126(6):220-2. [Transient elastography (Fibroscan), a new non-inva... more 1. Med Clin (Barc). 2006 Feb 18;126(6):220-2. [Transient elastography (Fibroscan), a new non-invasive method to evaluate hepatic fibrosis]. [Article in Spanish]. Mendoza J, Gómez-Domínguez E, Moreno-Otero R. Servicio de ...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 3, 2010
The cerebellum participates in motor coordination as well as in numerous cerebral processes, incl... more The cerebellum participates in motor coordination as well as in numerous cerebral processes, including temporal discrimination. Animals can predict daily timing of food availability, as manifested by food-anticipatory activity under restricted feeding. By studying ex vivo clock gene expression by in situ hybridization and recording in vitro Per1-luciferase bioluminescence, we report that the cerebellum contains a circadian oscillator sensitive to feeding cues (i.e., whose clock gene oscillations are shifted in response to restricted feeding). Food-anticipatory activity was markedly reduced in mice injected intracerebroventricularly with an immunotoxin that depletes Purkinje cells (i.e., OX7-saporin). Mice bearing the hotfoot mutation (i.e., Grid2 ho/ho ) have impaired cerebellar circuitry and mild ataxic phenotype. Grid2 ho/ho mice fed ad libitum showed regular behavioral rhythms and day-night variations of clock gene expression in the hypothalamus and cerebellum. When challenged with restricted feeding, however, Grid2 ho/ho mice did not show any food-anticipatory rhythms, nor timed feeding-induced changes in cerebellar clock gene expression. In hypothalamic arcuate and dorsomedial nuclei, however, shifts in Per1 expression in response to restricted feeding were similar in cerebellar mutant and wild-type mice. Furthermore, plasma corticosterone and metabolites before mealtime did not differ between cerebellar mutant and wild-type mice. Together, these data define a role for the cerebellum in the circadian timing network and indicate that the cerebellar oscillator is required for anticipation of mealtime. ) for their generous supply of hotfoot mice and to Dr. Stéphane Heitz for taking care of the breeding colony of this cerebellar mutant line. We thank Prof. M. Menaker (University of Virginia, Charlottesville, VA) for his generous gift of Per1:luc rats. The plasmids for synthesis of Per1 and
A procedure that utilizes the sample multiple correlation to form a lower bound for the level of ... more A procedure that utilizes the sample multiple correlation to form a lower bound for the level of predictive precision of a fitted regression equation is suggested. The procedure is shown to yield probability statements which are true at least 100(1 --a)% of the time.
The paper obtains a maximum likelihood criterion test for multisample sphericity. The test contai... more The paper obtains a maximum likelihood criterion test for multisample sphericity. The test contains Mauchly's sphericity test as a special case.
The validity of a test is often estimated in a nonrandom sample of selected individuals. To accur... more The validity of a test is often estimated in a nonrandom sample of selected individuals. To accurately estimate the relation between the predictor and the criterion we correct this correlation for range restriction. Unfortunately, this corrected correlation cannot be transformed using Fisher's Z transformation, and asymptotic tests of hypotheses based on small or moderate samples are not accurate. We developed a Fisher r to Z transformation for the corrected correlation for each of two conditions: (a) the criterion data were missing due to selection on the predictor (the missing data were MAR); and (b) the criterion was missing at random, not due to selection (the missing data were MCAR). The two Z transformations were evaluated in a computer simulation. The transformations were accurate, and tests of hypotheses and confidence intervals based on the transformations were superior to those that were not based on the transformations.
Corrections of correlations for range restriction (i.e., selection) and unreliability are common ... more Corrections of correlations for range restriction (i.e., selection) and unreliability are common in psychometric work. The current rule of thumb for determining the order in which to apply these corrections looks to the nature of the reliability estimate (i.e., restricted or unrestricted). While intuitive, this rule of thumb is untenable when the correction includes the variable upon which selection is made, as is generally the case. Using classical test theory, we show that it is the nature of the range restriction, not the nature of the available reliability coefficient, that determines the sequence for applying corrections for range restriction and unreliability.
Corrections of correlations for range restriction (i.e., selection) and unreliability are common ... more Corrections of correlations for range restriction (i.e., selection) and unreliability are common in psychometric work. The current rule of thumb for determining the order in which to apply these corrections looks to the nature of the reliability estimate (i.e., restricted or unrestricted). While intuitive, this rule of thumb is untenable when the correction includes the variable upon which selection is made, as is generally the case. Using classical test theory, we show that it is the nature of the range restriction, not the nature of the available reliability coefficient, that determines the sequence for applying corrections for range restriction and unreliability.
Large-sample confidence intervals (CI) for reliability, validity, and unattenuated validity are p... more Large-sample confidence intervals (CI) for reliability, validity, and unattenuated validity are presented. The CI for unattenuated validity is based on the Bonferroni inequality, which relies on one CI for test-retest reliability and one for validity. Covered are four reliability-validity situations: (a) both estimates were from random samples; (b) reliability was from a random sample but validity was from a selected sample; (c) validity was from a random sample but reliability was from a selected sample; and (d) both estimates were from selected samples. All CIs were evaluated by using a simulation. CIs on reliability, validity, or unattenuated validity are accurate as long as selection ratio is at least 20% and selected sample size is 100 or larger. When selection ratio is less than 20%, estimators tend to underestimate their parameters.
Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psych... more Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psychological Association, Inc. 0033-2909/82/9202-0532S00.75 The Statistical Analysis of Dyadic Social Behavior: A Multivariate Approach ...
Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psych... more Page 1. Psychological Bulletin 1982, Vol. 92, No. 2, 532-540 Copyright 1982 by the American Psychological Association, Inc. 0033-2909/82/9202-0532S00.75 The Statistical Analysis of Dyadic Social Behavior: A Multivariate Approach ...
Page 1. Psychological Bulletin 1991,\fol. 110, No. 3, 596-610 Copyright 1991 by the American Psyc... more Page 1. Psychological Bulletin 1991,\fol. 110, No. 3, 596-610 Copyright 1991 by the American Psychological Association, Inc. 0033-2909/91/J3.00 Validity Generalization Procedures Using Sample-Based Estimates: A Comparison of Six Procedures ...
A MONTE CARLO COMPARISON OF THE UNIVARIATE AND MULTIVARIATE METHODS FOR THE GROUPS BY TRIALS REPE... more A MONTE CARLO COMPARISON OF THE UNIVARIATE AND MULTIVARIATE METHODS FOR THE GROUPS BY TRIALS REPEATED MEASURES DESIGN ... JORGE L. MENDOZA, LARRY E. TOOTHAKER and W. ALAN NICEWANDER The University of Oklahoma
Under special restricted feeding conditions the mammalian circadian clock, contained in the hypot... more Under special restricted feeding conditions the mammalian circadian clock, contained in the hypothalamic suprachiasmatic nucleus (SCN), can be entrained by food. During food restriction, hungry animals are very motivated to obtain food. This motivational state could be a key component in altering the SCN timing by feeding. In order to comprehend how hedonic signals of food affect the SCN clock, we evaluated the effects of a daily palatable snack on the behavioural rhythm of mice fed ad libitum with regular food, and housed under constant darkness conditions. As light synchronization of the SCN is modulated by feeding/metabolic cues, the effects of a palatable meal coupled to a light pulse were tested on behavioural and molecular rhythms. A daily palatable snack entrained behavioural rhythms of mice in constant darkness conditions. Furthermore, palatable meal access at the activity onset reduced light-induced behavioural phase-delays and Period genes expression in the SCN. In addition, an increase in the dopamine content and Period genes expression in the forebrain of mice was observed, concomitant with a c-FOS activation in dopaminergic and orexinergic neurons, suggesting that the effects of a palatable snack on the SCN clock are mediated by the reward/arousal central systems. In conclusion, this study establishes an underlying sensitivity of the master circadian clock to changes in motivational states related to palatable food intake.
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Papers by Jorge Mendoza