A hybrid model combining the critical path method (CPM) with material requirements planning (MRP) has been suggested (Aquilano) as a more robust method for scheduling projects and resources. The primary advantage of this technique is that resource acquisition lead times as well as inventory records are integrated into the process of computing the project schedule. This paper presents a set of formal CPM/MRP algorithms that may be used to compute the early and late start schedules as well as the critical sequence. A number of modifications have been incorporated into the CPM/MRP technique to improve the viability of CPM/MRP as a tool for application to actual project scheduling problems. A simple example project is used to demonstrate the CPM/MRP model. The CPM/MRP technique is designed to overcome a basic shortcoming of previously suggested project scheduling methodologies. CPM was initially designed to schedule projects subject to technological constraints only. Later, additional techniques were introduced to consider constraints upon various aspects of resource availability (Davis). None of the suggested techniques attempted to integrate resource acquisition lead time with the generation of requirements for resources. Obviously such a technique would require the integration of inventory records into the scheduling technique. The combination of CPM and MRP provides a possible vehicle for overcoming this drawback in CPM. Both CPM and MRP are linear models that generate schedules based upon precedence relationships. An integrated approach is useful since activities could be scheduled subject to information about the inventory position. An activity may be scheduled as soon as all resources are on hand. It is only delayed by those resources which must be acquired and activities which proceed it in the project network. CPM/MRP also shows promise as an aid to constrained resource scheduling since computations regarding resource availability are an integrated part of the technique. The effect of resource allocation decisions is immediately evident in the MRP‐type time phased records. Results of the tests run on short projects of up to 300 activities and resources have shown that the program does work satisfactorily. Execution time for a 300 item network tested was approximately ten seconds on a CYBER 175.
Serum levels of four acute phase proteins, alpha1‐acid glycoprotein (AAGP), alpha1‐antitrypsin (AAT), haptoglobin (Hpt), and C3, were measured prior to biopsy in 38 women subsequently shown to have Stage I and II breast cancer and prior to treatment in 16 women with Stage IV disease. Sixty‐one women with benign and 28 women with no breast disease served as controls. Mean serum levels of all four proteins were significantly elevated in women with stage IV disease as compared to women with Stage I or II disease or controls. Normal versus elevated levels for each protein were defined and AAGP was found to be the single most sensitive predictor of disseminated disease among the four. AAGP was elevated in 81.3% of Stage IV, 25% of Stage II, 14.3% of Stage I, and 12.4% of controls. Women with multiple proteins elevated were most likely to have advanced stage disease. Composite analysis of all four proteins using number of proteins abnormal or logistic regression analysis gave results similar to AAGP, both showing increasing numbers of proteins abnormal with increasing stage of breast cancer. These results indicate that measurement of serum acute phase proteins may be useful in initial staging of breast cancer patients and in following patients for indications of disseminated disease.
Integrated serum screening for Down syndrome was successfully implemented in primary care settings; screening performance was consistent with predictions. It provides an accessible and acceptable alternative to screening protocols that require nuchal translucency measurements.
Maternal serum alpha-fetoprotein concentrations are influenced by maternal weight during the second trimester. Heavier pregnant women have lower median values, apparently as a result of a diluting effect of larger blood volume. This phenomenon is of clinical interest because alpha-fetoprotein concentration in a pregnant woman's serum is one of the factors considered in assessing risk of poor outcome. A revision of the reference interval for alpha-fetoprotein to take body weight into account might improve its use as a diagnostic aid, especially in heavier women.
Lowered serum concentrations of albumin, IgG, IgM, and transferrin have been identified preopera-tively in a population of otherwise healthy white women over age 40 with early stage breast cancer. Definition of low values for each of the four serum proteins has been arrived at via comparison with age-matched controls, consisting of disease-free women and women with benign breast lesions. Thus defined, low values for the individual serum proteins have been found to occur in malignantlcontrol study subjects at the following frequencies: albumin 68%/4.7% (P < 0.OOOl); IgG 56%/21% (P < 0.02); IgM SWi/19% (P < 0.001), and transferrin 50%/4.7% (P < 0.OOOl). Among the relevant historical and pathologic data evaluated in addition to the presence or absence of malignancy, only age has been found significant in influencing serum protein concentrations, and this has been taken into account in analyzing results. Forty-four percent of study sujects subsequently found to have breast cancer have low concentrations of at least three of the four discriminant proteins simqltaneously in the pre-operative sample. None of the contrsls have these findings. Twenty-nine percent of women with a malignant breqt lesion and WO of controls have simultaneously low concentrations of two of the four discriminant proteins. Using these measurements of serum proteins it thus becomes possible to assign risk of malignancy when a woman is found to have a breast mass. Cancer 48:793-798, 1981. NE OF THE SIGNIFICANT recent advances in can-0 cer diagnosis has been the discovery of several soluble tumor-associated proteins which can be assayed in serum. Carcinoembryonic antigen, the first among these to find clinical application, is now recognized as lacking specificity for diagnosing gastrointes-tinal tumors.' Alpha-fetoprotein demonstrates better specificity for hepatomas and germ cell tumors, a relatively uncommon group of malignancies in the United States. Human chorionic gonadotropin falls into a similar category.2 Breast cancer is one of the tumors for which no specific circulating protein has yet been found.3 As an alternate path of study, a number of investigators have measured normally occurring, nonspecific serum proteins in breast cancer patients. To date, these studies have produced inconclusive ~esults,4-~O possibly because clinical parameters have been insufficiently documented and methodology has been relatively imprecise. The present report continues along this line of investigation, utilizing more precise methodology both for the laboratory and for clinical data
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