Carlos A. Garcia

Hydropower generation management under uncertainty via scenario analysis and parallel computation

The authors present a modeling framework for the robust solution of hydroelectric power generation management problems with uncertainty in the values of the water inflows and outflows. A deterministic treatment of the problem provides unsatisfactory results, except for very short time horizons. They describe a model based on scenario analysis that allows a satisfactory treatment of uncertainty in the model data for medium and long-term planning problems. Their approach results in a huge model with a network submodel per scenario plus coupling constraints. The size of the problem and the structure of the constraints are adequate for the use of decomposition techniques and parallel computation tools. They present computational results for both sequential and parallel implementation versions of the codes, running on a cluster of workstations. The codes have been tested on data obtained from the reservoir network of Iberdrola, an electric utility owning 50% of the total installed hydroelectric capacity of Spain, and generating 40% of the total energy demand.

A parallel computation approach for solvingmultistage stochastic network problems

This paper presents a parallel computation approach for the efficient solution of verylarge multistage linear and nonlinear network problems with random parameters. Theseproblems result from particular instances of models for the robust optimization of networkproblems with uncertainty in the values of the right‐hand side and the objective functioncoefficients. The methodology considered here models the uncertainty using scenarios tocharacterize the random parameters. A scenario tree is generated and, through the use offull‐recourse techniques, an implementable solution is obtained for each group of scenariosat each stage along the planning horizon.As a consequence of the size of the resulting problems, and the special structure of theirconstraints, these models are particularly well‐suited for the application of decompositiontechniques, and the solution of the corresponding subproblems in a parallel computationenvironment. An augmented Lagrangian decomposition algorithm has been implementedon a distributed computation environment, and a static load balancing approach has beenchosen for the parallelization scheme, given the subproblem structure of the model. Largeproblems ‐ 9000 scenarios and 14 stages with a deterministic equivalent nonlinear modelhaving 166000 constraints and 230000 variables ‐ are solved in 45 minutes on a cluster offour small (11 Mflops) workstations. An extensive set of computational experiments isreported; the numerical results and running times obtained for our test set, composed oflarge‐scale real‐life problems, confirm the efficiency of this procedure.

Higher T-cell imbalance and growth factor receptor expression in B-cell chronic lymphocytic leukemia (B-CLL) as compared to monoclonal B-cell lymphocytosis of undetermined significance (B-MLUS)

The surface marker phenotype of lymphocytes derived from 12 patients with B-CLL was compared to that of lymphocytes from 10 patients with an other monoclonal but clinical benign form of B-cell proliferative disorder termed monoclonal B-cell lymphocytosis of undetermined significance (B-MLUS). A panel of well characterized monoclonal antibodies was used for the surface marker determinations. The mean total number of B cells (CD20) was 8.5 x 10(9)/1 in B-MLUS as compared to 44 x 10(9)/1 in B-CLL (p less than 0.001). B-CLL had a greater imbalance in T-cell subpopulations than B-MLUS and healthy controls. Total numbers of CD3+, CD8+ cells as well as cells expressing the NK-related antigens (CD16, Leu-7) and IL-2 receptor (CD25) bearing lymphocytes were statistically significant higher in B-CLL than in B-MLUS. Analyses of B-cell enriched populations showed that B-CLL represented B cells of an early maturation stage, whereas B cells from B-MLUS were more mature as judged by the loss of the CD21 surface marker. A larger fraction of B cells in B-CLL compared to B-MLUS exhibited a higher activation stage as revealed by the expression of the CD21, CD25 and CD35 structures as well as the FMC7 antigen.

Higher proliferative response in B-chronic lymphocytic leukemia (B-CLL) as compared to B-monoclonal lymphocytosis of undetermined significance (B-MLUS) after stimulation with Staphylococcus aureus and anti-CD40 monoclonal antibodies

B-CLL is a malignant monoclonal B-cell disorder and B-MLUS is the benign counterpart. The proliferative response and the capacity to secrete IgM was measured in B-CLL and B-MLUS, respectively, and compared to normal B-cells. SAC and a mAb against CD40 were used as stimulatory agents. No cell population responded to anti-CD40 mAb alone. SAC only induced a high DNA synthesis rate in normal B-cells as well as in B-CLL cells, although the magnitude was three-fold lower and delayed for about 48 h in B-CLL. B-MLUS cells did not proliferate in response to SAC. The combination of anti-CD40 and SAC enhanced the proliferative capacity of normal B-cells and produced a more rapid response in B-CLL. B-MLUS cells were not activated. Normal B-cells and B-MLUS did not secrete IgM after SAC stimulation, while B-CLL cells had a continuous increase in the IgM production during a 6-day culture period. The higher proliferative capacity of B-CLL cells compared with B-MLUS cells may be explained by an increased expression of activation molecules e.g. receptors for various cytokines and growth factors. Moreover, the inertness and inability of B-MLUS cells in comparison to normal B- and B-CLL cells to respond to powerful activation signals might indicate an intrinsic defect of B-MLUS cells in the signal transduction leading to a block of mitosis and a benign course of the disease.

Cell–cell adherence as a selection method for the generation of anti-melanoma monoclonal antibodies

The aim of the present study was to obtain monoclonal antibodies (mAbs) recognising human melanoma-associated antigens after immunisation of BALB/c mice with a 70-150 kDa membrane fraction from melanoma tumour tissues. Screening of specific antibody- producing hybridomas was performed using a novel cell-cell adherence method with the melanoma cell line M-14. Three mAbs of IgG1 isotype were selected: Mel-1, Mel-2 and Mel-3 which recognised the immunogen by ELISA and stained several melanoma cell lines positive in immunofluorescence. The molecular weight of the antigen was studied by different methods; a 170-kDa band was identified following immunoblotting of tumour lysate and a 72-kDa band was observed following immunoaffinity purification. Cell-cell adherence appears to be a reliable procedure for the generation of mAbs against native cellular antigens.

Erratum to “Higher T-cell imbalance and growth factor receptor expression in B-cell chronic lymphocytic leukemia (B-CLL) as compared to monoclonal B-cell lymphocytosis of undetermined significance (B-MLUS)” [Leukemia Res. 13(1) (1989) 31–37]

Please cite this article in press as: C. Garcia, et al., Erratum to “Higher T-cell imbalance and growth factor receptor expression in Bcell chronic lymphocytic leukemia (B-CLL) as compared to monoclonal B-cell lymphocytosis of undetermined significance (B-MLUS)” [Leukemia Res. 13(1) (1989) 31–37], Leuk Res (2017), http://dx.doi.org/10.1016/j.leukres.2017.01.029 The publisher regrets that the name of an author was mis-spelt (Björkhilm M. should read Bjorkholm M.). The publisher would like to apologise for any inconvenience caused.