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991.
James R. Evans 《IIE Transactions》1977,9(1):75-81
The focus of this paper is on modelling dynamic, deterministic, multiproduct, multistage production planning problems as single commodity network flow problems. The advantages of such formulations are discussed relative to computation of good integer solutions and continuous solutions with additional constraints. Special results for a single period problem are developed. 相似文献
992.
In order to investigate the amount of charge introduced into Langmuir- Blodgett (LB) films, multilayers of ω-tricosenoic acid have been deposited onto a number of silicon substrates under different dipping conditions. The effects of moisture and storage conditions on film properties have been examined, and a new mathematical model for the charge distribution within an LB film multilayer will be proposed. 相似文献
993.
The authors describe the technique of RARE sequences (Hennig, 1986) and their hydrographic application to urinary imaging, RARE urography. Heavily T2-weighted non-tomographic images of the urinary tract are obtained in less than 30 seconds, without contrast medium or ionizing radiation. The whole urinary tract is visualised on one image with a spatial resolution superior to that of sonography. The semiology of RARE urography is similar to that of the intravenous pyelogram. Silent kidneys are also visualised. 相似文献
994.
A patient with malignant fibrous histiocytoma of the dorsum of the hand, managed with irradiation and wide local excision, is presented. Biopsy technique, the rationale for preoperative irradiation, and the details of extensor tendon reconstruction are discussed. Tendon grafts, rather than transfers, were used to reconstruct the extensor tendon defects. Although this approach is simple, little is known regarding the healing of irradiated tendons or the use of dynamic splinting protocols in this setting. Our patient experienced no difficulty with either tendon healing or early dynamic splinting and achieved an acceptable range of motion. 相似文献
995.
R Curtis JR Tonra JL Stark KM Adryan JS Park KD Cliffer RM Lindsay PS DiStefano 《Canadian Metallurgical Quarterly》1998,12(3):105-118
We investigated the retrograde axonal transport of 125I-labeled neurotrophins (NGF, BDNF, NT-3, and NT-4) from the sciatic nerve to dorsal root ganglion (DRG) sensory neurons and spinal motor neurons in normal rats or after neuronal injury. DRG neurons showed increased transport of all neurotrophins following crush injury to the sciatic nerve. This was maximal 1 day after sciatic nerve crush and returned to control levels after 7 days. 125I-BDNF transport from sciatic nerve was elevated with injection either proximal to the lesion or directly into the crush site and after transection of the dorsal roots. All neurotrophin transport was receptor-mediated and consistent with neurotrophin binding to the low-affinity neurotrophin receptor (LNR) or Trk receptors. However, transport of 125I-labeled wheat germ agglutinin also increased 1 day after sciatic nerve crush, showing that increased uptake and transport is a generalized response to injury in DRG sensory neurons. Spinal cord motor neurons also showed increased neurotrophin transport following sciatic nerve injury, although this was maximal after 3 days. The transport of 125I-NGF depended on the expression of LNR by injured motor neurons, as demonstrated by competition experiments with unlabeled neurotrophins. The absence of TrkA in normal motor neurons or after axotomy was confirmed by immunostaining and in situ hybridization. Thus, increased transport of neurotrophic factors after neuronal injury is due to multiple receptor-mediated mechanisms including general increases in axonal transport capacity. 相似文献
996.
Simple mechanical models which could be used to calculate the stresses in an oxide scale on a flat metal substrate are presented. The sources for these stresses and the experimental techniques for measuring stresses and oxide failure are also briefly summarized. The options for stress relief in oxide scales are listed. The importance of lateral oxide growth and oxide plasticity is emphasized. Both processes result in stress relief without scale failure. This is followed by a detailed survey of the proposed mechanisms and models for oxide scale failure under tensile or compressive forces. Experimental evidence in support of these mechanisms is examined and the critical factors for predicting oxide failure are given. 相似文献
997.
998.
999.
The need for energy reduction in the electrolytic production of aluminum led to the concept of advanced Hall cells that can
be operated at lower interelectrode gaps compared to existing cells. However, gas bubbles generated by the anodic reaction
increase the resistivity of electrolyte and cancel out part of the reduction in interelectrode resistance expected from bringing
the electrodes closer together. Therefore, the primary objective of this work was to determine a cell design in which flow
can be managed to promote the removal of anode gas bubbles from the interelectrode gap. In particular, this article focuses
on advanced Hall cells equipped with “flat” anodes, similar to those used in existing cells. The principal experimental tool
has been a “water” model consisting of a large tank in which simulated anodes can be suspended in either the horizontal or
near-horizontal configurations. Gas was generated by forcing compressed air through porous graphite, and the fine bubbles
characteristic of inert anodes used in advanced Hall cells were produced by adding butanol to water. Velocities were measured
using a laser-Doppler velocimeter (LDV). This study indicates that the existing cell configuration might not be the optimum
configuration for advanced Hall cells. The results also show that operation of an advanced Hall cell with a fully submerged
anode should give rise to higher electrolyte velocities and thus rapid removal of bubbles. The bubble effect should be further
lowered in a near-horizontal configuration; however, the flow pattern could have an adverse effect on current efficiency and
alumina distribution in the cell. It has also been shown that the bubble size, and, therefore, the physical properties of
the electrolyte, can have a significant effect on the electrolyte flow pattern in the interelectrode gap. 相似文献
1000.
JS Meyer SL Koehm JM Hughes E Higa JL Wittliff JA Lagos JL Manes 《Canadian Metallurgical Quarterly》1993,71(11):3531-3540
BACKGROUND: The S-phase fraction relates to proliferation, an important determinant of tumor behavior, and has been measured most accurately with the DNA precursor tritiated thymidine (TT). The TT labeling index (LI) is a strong stage-independent prognostic indicator for breast carcinoma. The thymidine analogue 5-bromodeoxyuridine (BrdU) is also incorporated into DNA and has the advantage over TT of immunohistochemical detectability rather than requiring autoradiography, but it is less well studied in breast carcinoma. This report demonstrates the equivalence of TT and BrdU LI and explores the relationships between LI and other biologic measurements. METHODS: The LI of 234 consecutive breast carcinomas were measured with TT as was a subsequent series of 450 cases with BrdU, both by incubation in vitro. RESULTS: The mean BrdU LI was 6.4 +/- 0.3% in comparison with 6.9 +/- 0.4% in the prior TT series. LI was unaffected by storage for 24 hours at 4 degrees C before labeling with BrdU. The BrdU and TT LI both correlated: (1) positively with tumor size, histologic type, nuclear size, the number of axillary metastases, the level of DNA ploidy, and the percent S-phase by flow cytometry and (2) negatively with the age of the patient and the levels of estrogen receptor and progesterone receptor measured either by ligand binding or by immunohistochemistry. CONCLUSIONS: BrdU labeling in vitro was an advantageous method for measuring S-phase fraction in breast carcinoma that produced results comparable to those from TT labeling. It should be equally effective for breast cancer kinetic classification and prognosis and is a suitable standard to evaluate newer methods for measuring cellular proliferation. 相似文献