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This article focuses on a particular type of horizontal ground heat exchangers (HGHE) which can be used as a heat source (or heat sink) for geothermal heat pumps. It consists of a long pipe buried about 1 m below the ground surface and arranged in parallel regularly spaced sections, forming a serpentine. This article proposes a model for such a heat exchanger, where the serpentine is discretized axially and a three-step calculation procedure is performed on each node. The axial fluid temperature variation in the pipe is first computed by using an implicit numerical resolution scheme. Then, heat transfer in the ground surrounding the pipe is obtained by using the analytical cylindrical heat source solution. In the third step, used for mid- to long-term simulations, thermal interference between parallel pipe sections is taken into account using spatial superposition. Finally, these solutions are coupled iteratively to obtain the axial fluid and pipe temperatures at each time step. The model is then validated using a full-scale experimental facility located in Orléans, France. Following a brief description of the facility, validation results are reported. The main validation test consists of supplying the HGHE with a constant inlet fluid temperature (40°C [104°F]) for a 200-h period in soil at an initial temperature of 7.5°C (45.5°F). After an initial transient period, the recorded outlet fluid temperature matches the model prediction within 1°C (1.8°F). [ABSTRACT FROM AUTHOR]

Background and Objectives: The various epitopes of the CD34 molecule have been classified according to their different sensitivities to enzymatic cleavage by neuraminidase, chymopapain and a glycoprotease from Pasteurella haemolytica. Although monoclonal antibodies have been developed that specifically identify these epitopes, few studies have evaluated the distribution and quantitative expression of such epitopes on leukemic blasts., Design and Methods: We report here a prospective multicenter study in which we examined and quantified the expression of the 3 classes of CD34 on fresh leukemic blast cells from 300 cases of acute myeloid leukemia (AML). The binding of monoclonal antibodies was studied by flow cytometry, allowing evaluation of blast cell positivity as well as their mean fluorescence intensity. These quantitative data were made comparable between centers by means of a calibration curve established with the same reagents in all laboratories., Results: Quantitative expression of class I epitope was significantly higher than that of class II and class III epitopes (p<0.0001). The three classes were more frequently expressed in M0 and M1 and less in M3 and M5. The highest levels of CD34 expression were observed in M2, M0 and M1 and the lowest in M3, M5 and BAL for class II and III. CD34 expression was lower for all classes in cases with a normal karyotype, compared to in cases with structural or numerical abnormalities., Interpretation and Conclusions: In cases with a t(9;22) the expression of class I was significantly higher than that of class II and III and the opposite was observed in AML with t(15;17). Moreover, as a whole, a high intensity of class III CD34 appeared to be a marker of good prognosis.