Synthesis of amphiphilic magnetic microspheres by dispersion copolymerization of styrene and poly(ethylene oxide) macromonomer

Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe₃O₄ magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g^?1. © 2003 Society of Chemical Industry     

Impact of power control and lognormal shadowing on the mean transmit power of Bluetooth devices

This letter analyzes Bluetooth's power-control algorithm with a goal to study the mean transmit power required in the presence of lognormal shadowing. The following results are found. 1) A smaller power-control step size yields a lower mean transmit power. 2) When the standard deviations of lognormal shadowing are 3 and 6 dB, respectively, a Bluetooth device needs to consume 11.1 dB and 15.0 dB more in the transmit energy than the minimum one required in the absence of shadowing. 3) The transmit energy consumption varies by around 6 dB among Bluetooth devices as a result of the /spl plusmn/6 dB tolerance in the golden receive power range, which has a nominal size of 20 dB.     

Border crossing for hospital care and its implications for the use of statewide data

A major concern of researchers using state data sets for population-based analyses and market share studies in the health care sector is the potential bias caused by 'border crossing'--patients receiving care out of state. By using the Health Care Financing Administration (HCFA) discharge abstract files for 1987 and 1988, we found that 'border crossing' is not a serious problem for the two large states we examined. Only 4.4% of New York patients and 2.15% of California patients received care out of state. At the county and zip code level, 'border crossing' is more frequent but tends to be concentrated in areas adjacent to other states. Even excluding all zips with more than 10% of patients crossing the 'border' results in a small loss of patients (2.2% for New York and 1.0% for California).     

Hickman catheter-related infections in patients with cancer

There is strong evidence to support the hypothesis that the rapid effects of steroids on neurons are membrane-mediated. Rapid steroid effects have been demonstrated in the absence of intracellular receptors, in the presence of RNA or protein synthesis inhibitors, and in response to steroids coupled to large proteins that block access to intracellular receptors. This study selectively reviewed the emerging body of evidence suggesting that steroids have multiple sites of cellular actions, and explored in depth one possible membrane-mediated mechanism of action, the membrane-intercalation model.     

An order-clique-based approach for mining maximal co-locations

Most algorithms for mining spatial co-locations adopt an Apriori-like approach to generate size-k prevalence co-locations after size-(k − 1) prevalence co-locations. However, generating and storing the co-locations and table instances is costly. A novel order-clique-based approach for mining maximal co-locations is proposed in this paper. The efficiency of the approach is achieved by two techniques: (1) the spatial neighbor relationships and the size-2 prevalence co-locations are compressed into extended prefix-tree structures, which allows the order-clique-based approach to mine candidate maximal co-locations and co-location instances; and (2) the co-location instances do not need to be stored after computing some characteristics of the corresponding co-location, which significantly reduces the execution time and space required for mining maximal co-locations. The performance study shows that the new method is efficient for mining both long and short co-location patterns, and is faster than some other methods (in particular the join-based method and the join-less method).     

Weak link between conventional and unconventional superconductors

In this paper we consider the Josephson coupling between a conventional and an unconventional superconductor through a constriction. It is demonstrated that a weak link is very different from a tunnel junction. In particular, in an orientation where the coupling in a tunnel junction vanishes because of symmetry, the Josephson current in the case of a weak link can nevertheless be finite, albeit with the distinctive characteristics of(i) a current phase relationship with a period of 2/n, (ii) the critical current near but below the transition temperature T ₁ of the lower transition temperature superconductor is proportional to (1–(T/T ₁)) ^n/2, where n is an integer determined by the symmetry.