Predicting rainfall and irrigation requirements of corn in Ecuador

This work is a case study whose objective is prediction of irrigation needs of corn crops in different regions of Ecuador; being this a fundamental basic food for the country's economy, as in the remaining countries of the Andean area. The proposed methodology seeks to help improving the quality of corn crop. Specifically, we propose the application of regression models, within the framework of Functional Data Analysis (FDA), to predict the amount of rainfall (scalar response variable) in the places with the highest production of corn in Ecuador, as a function of functional covariates such as temperature and wind speed. From the estimation of the amount of rainfall, effective precipitation is calculated. This is the fraction of water used by the crops, from which the value of real evapotranspiration or ETc is obtained and, more importantly, the irrigation requirements at each stage of the corn crop, for its adequate physiological development. Application of regression models based on functional basis, Functional Principal Components (FPC) or Functional Partial Least Squares (FPLS) for scalar response variable, allows us to use the information of variables such as wind speed and temperature (of functional nature) in a better way than using multivariate models, for predicting the amount of rainfall, obtaining, as a result, very explicative models, defined by a high goodness of fit (R 2 = 0.97 , with 6 significant parameters and an error of 0.14) and practical utility. The model has been also applied to North Peru regions, obtaining rainfall prediction errors between 9% and 22%. Thus, the geographical limitations of the model could be the Andean regions with similar climate. In addition, this study proposes the application of FDA exploratory analysis and FDA outlier detection techniques as a common and useful practice in the specific domain of rainfall prediction studies, prior to applying the regression models.

Comparison of prostatic cancer tissue dihydrotestosterone levels at the time of relapse following orchiectomy or estrogen therapy

Dihydrotestosterone concentrations have been measured in prostatic tissue from patients with recurrent advanced prostatic cancer after 1.0 to 5.0 mg. diethylstilbestrol per day or castration with or without estrogen therapy. Although medical or surgical castration usually leads to tissue dihydrotestosterone concentrations of less than 2.4 ng./gm. 2 of 20 surgically castrated and 4 of 9 estrogen-treated patients had values above this level. The difference between the number of patients with dihydrotestosterone levels greater than 2.4 ng./gm. in the surgical castrated and estrogen-treated groups was statistically significant by a chi-square test. These differences suggest that 1) increased tissue dihydrotestosterone levels in diethylstilbestrol-treated patients may be caused by inadequate dosage or decreased compliance, and 2) increased tissue dihydrotestosterone concentrations greater than 2.4 ng./gm. in castrated patients suggest an adrenocortical androgen contribution to the prostatic dihydrotestosterone level. Therefore, patients who are castrated or treated with diethylstilbestrol should have plasma testosterone and tissue dihydrotestosterone measurements at the time of relapse. If plasma and tissue dihydrotestosterone levels are at castrate levels (plasma levels less than 0.5 ng./ml. and tissue levels less than 2.4 ng./gm.) then further hormonal therapy is not indicated. Otherwise, adrenocortical suppression should be done if plasma testosterone is at castrate levels and tissue dihydrotestosterone is elevated. When plasma testosterone is above castrate levels titration with hormonal therapy should be done while plasma testosterone is monitored to achieve plasma testosterone levels below 0.5 ng./ml.

Medical castration of males with megestrol acetate and small doses of diethylstilbestrol

An alternative program for medical castration for treatment of prostate cancer has been developed using a progestational antiandrogen, megestrol acetate (MA), in combination with small doses of diethylstilbestrol (DES; 0.1 mg/day). The administration of MA (40-80 mg/day) with 0.1 mg DES to nine patients resulted in castrate levels of plasma testosterone (less than 0.4 ng/ml) and significant suppression of both FSH and LH (P less than 0.05) for up to 12 months. Although large clinical trials must ultimately establish its safety, clinical side effects of this combined therapy to date have consisted of mild gynecomastia in two patients. The symptoms did not necessitate discontinuing the medications. It is concluded that the use of 0.1 mg DES with a minimum of 40 mg/day MA results in medical castration with sustained suppression of plasma testosterone. Because of the possible additional therapeutic advantage of blockade of intracellular androgen-mediated action by MA in androgen-dependent tumors, this combined therapy should be further explored as a possible initial treatment of choice for advanced prostate cancer.

Dihydrotestosterone concentration in prostate cancer tissue as a predictor of tumor differentiation and hormonal dependency

Tissue dihydrotestosterone and 5alpha-reductase (delta4-3-ketosteroid-5alpha-oxidoreductase) levels have been measured in prostates of patients with cancer and benign prostatic hypertrophy; significant decreases in average values for both of these biochemical parameters were noted in prostate cancer compared to benign prostatic hypertrophy, although individual values overlapped in both groups. Prostate cancer tissue dihydrotestosterone levels appeared to correlate better than did either histological tumor grading or 5alpha-reductase with the ultimate clinical response to antiandrogen therapy. These results suggest that assay of tissue dihydrotestosterone levels in prostate cancer should be further explored as a possible marker for tumor differentiation.