Thermal Microwave Emission from Vegetated Fields: A Comparison between Theory And Experiment

The radiometric measurements over bare field and fields covered with grass, soybean, corn, and alfalfa were made with 1.4-and 5-GHz microwave radiometers during August-October 1978. The measured results are compared with radiative transfer theory treating the vegetated fields as a two-layer random medium. It is found that the presence of a vegetation cover generally gives a higher brightness temperature TB than that expected from a bare soil. The amount of this TB excess increases with increase in the vegetation biomass and in the frequency of the observed radiation. The results of radiative transfer calculations, which include a parameter characterizing ground surface roughness, generally match well with the experimental data.     

Hyperprolactinaemia and verapamil: prevalence and potential association with hypogonadism in men

OBJECTIVE: Verapamil has been associated with hyperprolactinaemia, but there have been no population-based studies. Our objective was to determine the prevalence and degree of hyperprolactinaemia associated with verapamil in the clinical setting. DESIGN: Observation with cross-sectional and longitudinal components in the setting of an urban teaching hospital and its satellite out-patient clinics. PATIENTS: Male out-patients excluding those taking other drugs known to raise PRL, renal failure and known primary hypothyroidism (1265 eligible subjects). Control subjects were drawn from eligible out-patients not taking verapamil. MEASUREMENTS: Serum PRL levels, frequency of persistent hyperprolactinaemia and total testosterone levels. RESULTS: Prolactin levels were obtained in 449 subjects on verapamil (35.5% response rate) and 166 controls. The proportions of individuals with hyperprolactinaemia (PRL > 460 mU/l) were 0.085 and 0.030 in the verapamil and control groups, respectively (P = 0.012, X2-test). The mean (+/- SD) serum PRL levels were 267 +/- 205 and 203 +/- 118 mU/l in the verapamil and control groups, respectively (P < 0.001, independent t-test). Of the 38 patients with previously determined elevated PRL levels, follow-up data were obtained in 25 (65.8%); one was found to have a pituitary adenoma and was excluded from the analysis. Fifteen of the 24 were still on verapamil (Group 1) and 14 (93.3%) continued to be hyperprolactinaemic. In 9 patients verapamil had been discontinued (Group 2) and all had normal PRL levels. Continued verapamil use was associated with persistent hyperprolactinaemia (odds ratio > 120, P < 0.00001). The mean +/- SD serum testosterone levels at follow-up were significantly lower in Group 1 (6.16 +/- 2.52 nmol/l) than in Group 2 (9.42 +/- 3.92 nmol/l, P = 0.029, independent t-test). CONCLUSIONS: The prevalence of hyperprolactinaemia associated with verapamil use in this study of male out-patients was 8.5% (95% CI 5.9-11.1%). The persistence of hyperprolactinaemia when verapamil was continued (Group 1) and the return to normal PRL levels when verapamil was discontinued (Group 2) confirm verapamil's causal role in the development of hyperprolactinaemia. While low testosterone levels were common in both groups, testosterone levels were lower in patients on verapamil. Our data suggest that screening for hyperprolactinaemia should be considered in male patients taking verapamil.     

Vertical optimization of data transmission for mobile wireless terminals

A major problem for TCP connections over wireless links is that errors introduced by the wireless channel interfere with the TCP protocol, leading to reduced data rates and power wastage. Based on accurate simulations for the TCP and IEEE 802.11 MAC protocols, we discuss recipes to optimize transmission. It is argued that the best approach is to restrict modifications to the mobile device. While this requires separate solutions for the uplink and downlink, the results of optimization are then available when roaming into any WLAN obeying the relevant MAC protocol. Simulation results show that the combination of specific strategies with a vertical interaction between the protocol layers can lead to the required improvements, giving a promising approach to enhance the performance of wireless mobile terminals.     

A Photometric Study of the Thickness of Liquid Sheets Produced from Spinning Cups

An account is given of the way in which photometry may be utilized to measure the thickness of liquid sheets produced from spinning cup atomisers. The theory of the technique is discussed and its limitations are noted.     

Adaptive Configuration of a Lean Production System in Small and Medium-sized Enterprises

Small and Medium-sized Enterprises (SMEs) are facing everyday the hard competition of global markets and higher requirements of the customers. For coping with these changing conditions many large enterprises implement a Lean Production System (LPS). An LPS offers a holistic strategy to eliminate waste in processes, to achieve high product and process quality, and to reduce lead times. The structure of an LPS is described by hierarchical connections of different elements and is configured in four levels: the goals, the sub-goals, the methods, and tools (Dombrowski et al. ZWF Zeitschrift für wirtschaftlichen Fabrikbetrieb 101:113–118, 2006). While large enterprises are able to provide necessary resources and experts’ know-how to configure and implement an LPS, SMEs lack these essential resources for organizational, technological, and workforce-related changes. Due to the complexity of the structure of an LPS, SMEs have in practice a small opportunity to configure a suitable structure and often fail in selecting and evaluating the most adequate methods and tools to be used. In this regard, the paper presents a framework to support an adaptive configuration of an LPS in SMEs which has been partly developed in the research project ProfiL in close cooperation with six SMEs.