A framework for analysis of the effect of time on shopping behavior

Due to technological developments, data about how many items a customer buys and how long the customer spends in a supermarket are available. A major problem with the data, however, is that there is no framework that considers the heterogeneity hidden in the data. In this article, we propose a framework that considers heterogeneity in the number of items a customer buys. The first step of our framework is based on the Poisson mixture regression model using a stationary time in the department where the items are sold as its independent variable. This model finds latent homogeneous groups of customers and gives the regression models within each group. It simultaneously classifies the customers into the homogeneous groups. In the second step of our framework, a method to investigate whether another factor (variable) influences the classification into homogeneous groups is presented. This proposed framework is applied to real data collected from the customers, and the effectiveness of the framework is shown. The managerial implications are drawn from the result of the analysis.     

Selective adsorption of precious metals from hydrochloric acid solutions using porous carbon prepared from barley straw and rice husk

Porous carbon was prepared by carbonization from agro-waste such as rice husk and barley straw to evaluate the adsorption of precious and base metals from metal solutions. The effects of hydrochloric acid concentration, metal ion concentration, and contact time on adsorption were examined. Rice husk carbon was found to be highly selective for Au(III) and inert to Pt(IV), Pd(II) and other base metals. Barley straw carbon adsorbed these three precious metal ions, but was inert to base metal ions such as Cu(II), Fe(III) and Ni(II). The maximum adsorption capacity of rice husk carbon for Au(III) was 0.76 mol/kg and the maximum adsorption capacity of barley straw carbon for Au(III), Pt(IV) and Pd(II) was 1.47, 0.39 and 0.64 mol/kg, respectively. The effectiveness of recovery of precious metals from industrial solution was also tested and barley straw carbon was found to be highly efficient and selective for the targeted metal ions in the presence of excess of other metal ions. Rice husk and barley straw carbon are thus potential alternatives to commercially available activated carbon as they have high selectivity and are efficient with low production costs.     

In vivo evaluation of magnetite nanoparticles for use as a tumor contrast agent in MRI

Magnetite nanoparticles, coated by three different artificial polypeptides, were conjugated to an antibody specific to the carcinoembryonic antigen (CEA). To protect the particles from fast blood elimination, the coats were modified by various sugars, polyethyleneglycol, albumin, and sialoproteins, respectively. The protective effect was determined by using a specific in vitro test and by analyzing the biodistribution of the nanoparticles in nude mice grafted with CEA-tumors. In particular, a prolongation of the blood circulation time has been expected, if a natural modifier is attached to the coated nanoparticles. Although the elimination rate could hardly be decreased by any modifiers, the tumor accumulation is slightly improved by using the specific sialoprotein glycophorin B. The usefulness of nanoparticles as image contrast agents is probably limited by their microdistribution within the tumor tissue. The requirements for a contrast agent to be highly tissue specific are discussed.     

Expression of growth factors and their receptors in the postnatal rat cochlea

RT-PCR was used to assay for growth factors and receptors from seven different protein families in cochlea tissues of the juvenile rat. There was a broad representation of the growth factor families in all the cochlea tissues examined, though the organ of Corti and stria vascularis expressed a greater variety than the spiral ganglion. This broad expression suggests that a variety of known growth factors play significant roles in the development, maintenance, and repair of the inner ear. The results of this survey serve as a basis for the design of future in vitro experiments that will address the ability of growth factors to protect hair cells from damage and to evoke a repair-regeneration response by injured hair cells.     

The CT nephrogram: implications for evaluation of urinary tract disease

The urographic nephrogram is an important indicator of underlying functional and structural renal disease. With expansions in use of cross-sectional imaging, the computed tomographic (CT) nephrogram (ie, contrast material enhancement within the renal parenchyma) has assumed a greater role in the evaluation of urinary tract disorders. Both quantitative and qualitative nephrographic abnormalities are well demonstrated by CT, including global or segmental absence or persistence of the nephrogram, slowed temporal progression, striated pattern, and rim pattern. Global absence is nearly always unilateral and is most often seen with blunt abdominal trauma with renal pedicle injury. Segmental absence is attributable to focal renal infarction, most likely due to arterial emboli. Global persistence, which is much more common than segmental persistence, may be unilateral (caused by renal artery stenosis, renal vein thrombosis, or urinary tract obstruction) or bilateral (due to systemic hypotension, intratubular obstruction, or abnormalities in tubular function). Striated nephrograms may be unilateral or bilateral and are caused by ureteric obstruction, acute pyelonephritis, contusion, renal vein thrombosis, tubular obstruction, hypotension, and autosomal recessive polycystic kidney disease. The rim pattern is most often associated with renal infarction and occasionally with acute tubular necrosis and renal vein thrombosis. Careful evaluation of the CT nephrogram is an integral part of the abdominal CT examination.     

Relationship of hydrophobicity and solubility with some functional properties of cowpea (Vigna unguiculata) protein isolate

The relationship of hydrophobicity and solubility with some functional properties of cowpea protein isolate was determined. Cowpea protein isolate was prepared by alkali extraction followed by precipitation at pH 4.5. The precipitated proteins were then neutralized to pH 7. Heating of the protein isolate to 100°C for 10 min followed by cooling to room temperature resulted in a significant (P ≦ 0.05) decrease in aromatic hydrophobicity (ARH) when compared to the native protein isolate. The inclusion of sodium dodecyl sulfate (SDS) during heating gave a significant (P ≦ 0-05) 1.7-fold increase while inclusion of mercaptoethanol (ME) gave a significant (P ≦ 0.05) 2.5-fold increase in ARH of the cooled protein solution. Protein solubility (PS), foam expansion (FE) and emulsification activity index (EAI) of the isolate generally increased significantly (P ≦ 0.05) upon heating or treatment with urea or SDS or a combination of SDS and ME. Backward stepwise multiple regression was used to obtain equations for predicting emulsifying and foaming properties of the protein isolate from solubility and hydrophobicity parameters. PS, ARH and aliphatic hydrophobicity (ALH) were important in predicting foam stability and emulsion stability, while PS and ALH were important for predicting FE. ALH alone was important for predicting EAI.     

Proliferative potential and apoptosis in rat glioma cell lines after hyperthermia

The proliferative potential of cultured rat glioma cells (C6 and 9L) was evaluated after hyperthermia using immunohistochemical staining with bromodeoxyuridine (BrdU) and Ki-67 monoclonal antibodies. Apoptosis was assessed by in situ end-labeling of deoxyribonucleic acid breaks. Both BrdU and Ki-67 labeling indexes decreased with increasing hyperthermia time. The decrease of the Ki-67 labeling index was not as great as that of the BrdU labeling index. The number of apoptotic cells increased with time after hyperthermia. These results indicate that the antitumor effect of hyperthermia may reflect the induction of apoptosis in the cells within the cell cycle, and the resultant reduction of the proliferative potential of surviving cells, especially in the S phase.