Léo A. - Academia.edu (original) (raw)
Papers by Léo A.
Nature, 1991
Wild-type p53 protein has many properties consistent with its being the product of a tumour suppr... more Wild-type p53 protein has many properties consistent with its being the product of a tumour suppressor gene. Although the normal roles of tumour suppressor genes are still largely unknown, it seems that they could be involved in promoting cell differentiation as well as in mediating growth arrest by growth-inhibitory cytokines. Hence, the abrogation of wild-type p53 expression, which is a common feature of many tumours, could eliminate these activities. We have now tested this notion by restoring the expression of p53 in a murine myeloid leukaemic cell line that normally lacks p53. The use of a temperature-sensitive p53 mutant allowed us to analyse cells in which the introduced p53 had either wild-type or mutant properties. Although there seemed to be no effect on differentiation, the introduction of wild-type p53 resulted in rapid loss of cell viability in a way characteristic of apoptosis (programmed cell death). The effect of wild-type p53 was counteracted by interleukin-6. Thus products of tumour suppressor genes could be involved in restricting precursor cell populations by mediating apoptosis.
New England Journal of Medicine, 1999
Since in hospitalized older patients delirium is associated with poor outcomes, we evaluated the ... more Since in hospitalized older patients delirium is associated with poor outcomes, we evaluated the effectiveness of a multicomponent strategy for the prevention of delirium. We studied 852 patients 70 years of age or older who had been admitted to the general-medicine service at a teaching hospital. Patients from one intervention unit and two usual-care units were enrolled by means of a prospective matching strategy. The intervention consisted of standardized protocols for the management of six risk factors for delirium: cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment, and dehydration. Delirium, the primary outcome, was assessed daily until discharge. Delirium developed in 9.9 percent of the intervention group as compared with 15.0 percent of the usual-care group, (matched odds ratio, 0.60; 95 percent confidence interval, 0.39 to 0.92). The total number of days with delirium (105 vs. 161, P=0.02) and the total number of episodes (62 vs. 90, P=0.03) were significantly lower in the intervention group. However, the severity of delirium and recurrence rates were not significantly different. The overall rate of adherence to the intervention was 87 percent, and the total number of targeted risk factors per patient was significantly reduced. Intervention was associated with significant improvement in the degree of cognitive impairment among patients with cognitive impairment at admission and a reduction in the rate of use of sleep medications among all patients. Among the other risk factors per patient there were trends toward improvement in immobility, visual impairment, and hearing impairment. The risk-factor intervention strategy that we studied resulted in significant reductions in the number and duration of episodes of delirium in hospitalized older patients. The intervention had no significant effect on the severity of delirium or on recurrence rates; this finding suggests that primary prevention of delirium is probably the most effective treatment strategy.
Chemical Reviews, 1971
... Introduction A. Purpose B. Historical Theoretical A. Henry&am... more ... Introduction A. Purpose B. Historical Theoretical A. Henry's Law B. Nonideal Behavior of Solutes C. Thermodynamics ... From references in these papers, many other values have come to light. ... This partitioning process is related linearly to log P which is the partition CO-efficient of ...
Neural Computation, 1999
The theory behind the success of adaptive reweighting and combining algorithms (arcing) such as A... more The theory behind the success of adaptive reweighting and combining algorithms (arcing) such as Adaboost (Freund & Schapire, 1996a, 1997) and others in reducing generalization error has not been well understood. By formulating prediction as a game where one player makes a selection from instances in the training set and the other a convex linear combination of predictors from a finite set, existing arcing algorithms are shown to be algorithms for finding good game strategies. The minimax theorem is an essential ingredient of the convergence proofs. An arcing algorithm is described that converges to the optimal strategy. A bound on the generalization error for the combined predictors in terms of their maximum error is proven that is sharper than bounds to date. Schapire, Freund, Bartlett, and Lee (1997) offered an explanation of why Adaboost works in terms of its ability to produce generally high margins. The empirical comparison of Adaboost to the optimal arching algorithm shows that their explanation is not complete.
Proceedings of The National Academy of Sciences, 1987
A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Arm... more A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Armenian hamsters with a murine cytolytic T-cell clone. The antibody is specific for a 25-kDa protein component (T3-epsilon) of the antigen-specific T-cell receptor. It reacts with all mature T cells and can both activate and inhibit T-cell function. These results identify T3-epsilon as a cell surface protein involved in the transduction of activation signals.
Journal of The American Statistical Association, 1960
A simple exact formula for the variance of the product of two random variables, say, x and y, is ... more A simple exact formula for the variance of the product of two random variables, say, x and y, is given as a function of the means and central product-moments of x and y. The usual approximate variance formula for xy is compared with this exact formula; e.g., we note, in the special case where x and y are independent, that the “variance” computed by the approximate formula is less than the exact variance, and that the accuracy of the approximation depends on the sum of the reciprocals of the squared coefficients of variation of x and y. The case where x and y need not be independent is also studied, and exact variance formulas are presented for several different “product estimates.” (The usefulness of exact formulas becomes apparent when the variances of these estimates are compared.) When x and y are independent, simple unbiased estimates of these exact variances are suggested; in the more general case, consistent estimates are presented.
Journal of The American Statistical Association, 1985
In regression analysis the response variable Y and the predictor variables X 1 …, Xp are often re... more In regression analysis the response variable Y and the predictor variables X 1 …, Xp are often replaced by functions θ(Y) and Ø1(X 1), …, Øp (Xp). We discuss a procedure for estimating those functions θ and Ø1, …, Øp that minimize e 2 = E{[θ(Y) — Σ Øj (Xj)]2}/var[θ(Y)], given only a sample {(yk, xk1, …, xkp), 1 k N} and making minimal assumptions concerning the data distribution or the form of the solution functions. For the bivariate case, p = 1, θ and Ø satisfy ρ = p(θ, Ø) = maxθ,Øρ[θ(Y), Ø(X)], where ρ is the product moment correlation coefficient and ρ is the maximal correlation between X and Y. Our procedure thus also provides a method for estimating the maximal correlation between two variables.
The Experimental Physics and Industrial Control System (EPICS), has been used at a number of site... more The Experimental Physics and Industrial Control System (EPICS), has been used at a number of sites for performing data acquisition, supervisory control, closed-loop control, sequential control, and operational optimization. The EPICS architecture was originally developed by a group with diverse backgrounds in physics and industrial control. The current architecture represents one instance of the "standard model". It provides distributed processing and communication from any local area network (LAN) device to the front end controllers. This paper presents the current architecture, performance envelope, current installations, and planned extensions for requirements not met by the current architecture.
Nature, 1991
Wild-type p53 protein has many properties consistent with its being the product of a tumour suppr... more Wild-type p53 protein has many properties consistent with its being the product of a tumour suppressor gene. Although the normal roles of tumour suppressor genes are still largely unknown, it seems that they could be involved in promoting cell differentiation as well as in mediating growth arrest by growth-inhibitory cytokines. Hence, the abrogation of wild-type p53 expression, which is a common feature of many tumours, could eliminate these activities. We have now tested this notion by restoring the expression of p53 in a murine myeloid leukaemic cell line that normally lacks p53. The use of a temperature-sensitive p53 mutant allowed us to analyse cells in which the introduced p53 had either wild-type or mutant properties. Although there seemed to be no effect on differentiation, the introduction of wild-type p53 resulted in rapid loss of cell viability in a way characteristic of apoptosis (programmed cell death). The effect of wild-type p53 was counteracted by interleukin-6. Thus products of tumour suppressor genes could be involved in restricting precursor cell populations by mediating apoptosis.
New England Journal of Medicine, 1999
Since in hospitalized older patients delirium is associated with poor outcomes, we evaluated the ... more Since in hospitalized older patients delirium is associated with poor outcomes, we evaluated the effectiveness of a multicomponent strategy for the prevention of delirium. We studied 852 patients 70 years of age or older who had been admitted to the general-medicine service at a teaching hospital. Patients from one intervention unit and two usual-care units were enrolled by means of a prospective matching strategy. The intervention consisted of standardized protocols for the management of six risk factors for delirium: cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment, and dehydration. Delirium, the primary outcome, was assessed daily until discharge. Delirium developed in 9.9 percent of the intervention group as compared with 15.0 percent of the usual-care group, (matched odds ratio, 0.60; 95 percent confidence interval, 0.39 to 0.92). The total number of days with delirium (105 vs. 161, P=0.02) and the total number of episodes (62 vs. 90, P=0.03) were significantly lower in the intervention group. However, the severity of delirium and recurrence rates were not significantly different. The overall rate of adherence to the intervention was 87 percent, and the total number of targeted risk factors per patient was significantly reduced. Intervention was associated with significant improvement in the degree of cognitive impairment among patients with cognitive impairment at admission and a reduction in the rate of use of sleep medications among all patients. Among the other risk factors per patient there were trends toward improvement in immobility, visual impairment, and hearing impairment. The risk-factor intervention strategy that we studied resulted in significant reductions in the number and duration of episodes of delirium in hospitalized older patients. The intervention had no significant effect on the severity of delirium or on recurrence rates; this finding suggests that primary prevention of delirium is probably the most effective treatment strategy.
Chemical Reviews, 1971
... Introduction A. Purpose B. Historical Theoretical A. Henry&am... more ... Introduction A. Purpose B. Historical Theoretical A. Henry's Law B. Nonideal Behavior of Solutes C. Thermodynamics ... From references in these papers, many other values have come to light. ... This partitioning process is related linearly to log P which is the partition CO-efficient of ...
Neural Computation, 1999
The theory behind the success of adaptive reweighting and combining algorithms (arcing) such as A... more The theory behind the success of adaptive reweighting and combining algorithms (arcing) such as Adaboost (Freund & Schapire, 1996a, 1997) and others in reducing generalization error has not been well understood. By formulating prediction as a game where one player makes a selection from instances in the training set and the other a convex linear combination of predictors from a finite set, existing arcing algorithms are shown to be algorithms for finding good game strategies. The minimax theorem is an essential ingredient of the convergence proofs. An arcing algorithm is described that converges to the optimal strategy. A bound on the generalization error for the combined predictors in terms of their maximum error is proven that is sharper than bounds to date. Schapire, Freund, Bartlett, and Lee (1997) offered an explanation of why Adaboost works in terms of its ability to produce generally high margins. The empirical comparison of Adaboost to the optimal arching algorithm shows that their explanation is not complete.
Proceedings of The National Academy of Sciences, 1987
A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Arm... more A monoclonal antibody (145-2C11) specific for the murine T3 complex was derived by immunizing Armenian hamsters with a murine cytolytic T-cell clone. The antibody is specific for a 25-kDa protein component (T3-epsilon) of the antigen-specific T-cell receptor. It reacts with all mature T cells and can both activate and inhibit T-cell function. These results identify T3-epsilon as a cell surface protein involved in the transduction of activation signals.
Journal of The American Statistical Association, 1960
A simple exact formula for the variance of the product of two random variables, say, x and y, is ... more A simple exact formula for the variance of the product of two random variables, say, x and y, is given as a function of the means and central product-moments of x and y. The usual approximate variance formula for xy is compared with this exact formula; e.g., we note, in the special case where x and y are independent, that the “variance” computed by the approximate formula is less than the exact variance, and that the accuracy of the approximation depends on the sum of the reciprocals of the squared coefficients of variation of x and y. The case where x and y need not be independent is also studied, and exact variance formulas are presented for several different “product estimates.” (The usefulness of exact formulas becomes apparent when the variances of these estimates are compared.) When x and y are independent, simple unbiased estimates of these exact variances are suggested; in the more general case, consistent estimates are presented.
Journal of The American Statistical Association, 1985
In regression analysis the response variable Y and the predictor variables X 1 …, Xp are often re... more In regression analysis the response variable Y and the predictor variables X 1 …, Xp are often replaced by functions θ(Y) and Ø1(X 1), …, Øp (Xp). We discuss a procedure for estimating those functions θ and Ø1, …, Øp that minimize e 2 = E{[θ(Y) — Σ Øj (Xj)]2}/var[θ(Y)], given only a sample {(yk, xk1, …, xkp), 1 k N} and making minimal assumptions concerning the data distribution or the form of the solution functions. For the bivariate case, p = 1, θ and Ø satisfy ρ = p(θ, Ø) = maxθ,Øρ[θ(Y), Ø(X)], where ρ is the product moment correlation coefficient and ρ is the maximal correlation between X and Y. Our procedure thus also provides a method for estimating the maximal correlation between two variables.
The Experimental Physics and Industrial Control System (EPICS), has been used at a number of site... more The Experimental Physics and Industrial Control System (EPICS), has been used at a number of sites for performing data acquisition, supervisory control, closed-loop control, sequential control, and operational optimization. The EPICS architecture was originally developed by a group with diverse backgrounds in physics and industrial control. The current architecture represents one instance of the "standard model". It provides distributed processing and communication from any local area network (LAN) device to the front end controllers. This paper presents the current architecture, performance envelope, current installations, and planned extensions for requirements not met by the current architecture.