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51.
OBJECTIVES: To determine the extent and nature of local ordinances to regulate tobacco sales to minors, the level of enforcement of local and state laws concerning tobacco availability to minors, and sanctions applied as a result of enforcement. DESIGN: Tobacco control ordinances were collected in 1993 from 222 of the 229 cities greater than or equal to 2000 population in Minnesota, United States. In addition a telephone survey with the head of the agency responsible for enforcement of the tobacco ordinances was conducted. MAIN OUTCOME MEASURES: Presence or absence of legislative provisions dealing with youth and tobacco, including licensure of tobacco retailers, sanctions for selling tobacco products to minors, and restrictions on cigarette vending machines, self-service merchandising, and point-of-purchase advertising; and enforcement of these laws (use of inspections and "sting" operations, and sanctions imposed on businesses and minors). RESULTS: Almost 94% of cities required tobacco licences for retailers. However, 57% of the cities specified licences for cigarettes only. Annual licence fees ranged from $10 to $250, with the higher fees adopted in the previous four years. More than 25% of the cities had adopted some kind of restriction on cigarette vending machines, but only six communities had banned self-service cigarette displays. Three cities specified a minimum age for tobacco sales staff. Fewer than 25% of police officials reported having conducted compliance checks with minors or in-store observations of tobacco sales to determine if minors were being sold tobacco during the current year. Police carrying out compliance checks with youth were almost four times as likely to issue citations as those doing in-store observations. More than 90% of police reported enforcement of the law against tobacco purchase or possession by minors, and nearly 40% reported application of penalties against minors. CONCLUSIONS: Almost 75% of the cities have done nothing to change policies or enforcement practices to encourage compliance with tobacco age-of-sale legislation, and only a few of the remaining cities have adopted optimal policies. In addition, officials in Minnesota cities are much more likely to use enforcement strategies against minors who buy tobacco than against merchants who sell tobacco.


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52.
We present a detailed and accurate physics based transient simulation for modeling flash memory erasing. Typical cells are erased by moving electrons from the floating gate to the drain, source or substrate. This paper addresses substrate erasing using a negative gate bias voltage based on the approximate solution to Poisson’s equation. Substrate erasing using a negative gate bias voltage is one of the more prevalent ways to erase flash memory in currently available consumer products. Many papers have been published on this topic but rarely present detailed derivations and none using this exact set of equations to model this erasing process.  相似文献   
53.
We have synthesized the first deoxy analogues of myo-inositol 3,4,5, 6-tetrakisphosphate (1) [Ins(3,4,5,6)P4], rac-2-deoxy-myo-inositol 3, 4,5,6-tetrakisphosphate (rac-2), 2-deoxy-myo-inositol 1,4,5, 6-tetrakisphosphate (ent-2), and rac-1-deoxy-myo-inositol 3,4,5, 6-tetrakisphosphate (rac-3). In order to evaluate the binding properties of the three derivatives to the yet unidentified intracellular binding sites for Ins(3,4,5,6)P4, the analogues were converted to membrane-permeant derivatives. Starting with common inositol precursors, various forms of Barton-McCombie deoxygenation and classical protection/deprotection procedures yielded the desired precursors rac-1-O-butyryl-2-deoxy-myo-inositol (rac-12), ent-3-O-butyryl-2-deoxy-myo-inositol (ent-12), and rac-2-O-butyryl-1-deoxy-myo-inositol (rac-19), respectively. Phosphorylation and subsequent deprotection yielded rac-2, ent-2, and rac-3. Alternatively, phosphorylation followed by alkylation with acetoxymethyl bromide gave the membrane-permeant derivatives 1-O-butyryl-2-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-5), 3-O-butyryl-2-deoxy-myo-inositol 1,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (ent-5), and 2-O-butyryl-1-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-6), respectively. We examined the potency of the membrane-permeant deoxy derivatives in inhibition of calcium-mediated chloride secretion (CaMCS) in intact T84 cells. Compared to the 1,2-di-O-butyryl-myo-inositol 3,4,5, 6-tetrakisphosphate octakis(acetoxymethyl) ester (4), the membrane-permeant derivative of Ins(3,4,5,6)P4 (1), the 2-deoxy derivative (rac-5) exhibited a slightly weaker inhibitory effect, while the enantiomerically pure 2-deoxy-Ins(1,4,5,6)P4 (ent-5) and the 1-deoxy derivative (rac-6) were inactive. As expected, the effect was stereoselective. Thus, the 1-hydroxyl group is apparently essential for binding and the inhibitory effect of Ins(3,4,5,6)P4 on chloride secretion, whereas the 2-hydroxyl group plays a less important role.  相似文献   
54.
Pharmacological and expectancy effects of 0.3 mg/kg methylphenidate on the behavior and attributions of boys with attention-deficit/hyperactivity disorder were evaluated. In a within-subject, balanced-placebo design, 136 boys received 4 medication-expectancy conditions. Attributions for success and failure on a daily report card were gathered. Assessments took place within the setting of a summer treatment program and were repeated in boys' regular classrooms. Expectancy did not affect the boys' behavior; only active medication improved their behavior. Boys attributed their success to their effort and ability and attributed failure to task difficulty and the pill, regardless of medication and expectancy. Results were generally equivalent across the two settings; where there were differences, beneficial effects of medication were more apparent in the school setting. The findings were unaffected by individual difference factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
The constuction and performance of 12? × 12? flash chambers used in a 340 ton neutrino detector under construction at Fermilab is described. The flash chambers supply digital information with a spatial resolution of 0.2?, and are used to finely sample the shower development of the reaction products of neutrino interactions. The flash chambers are easy and inexpensive to build and are electronically read out.  相似文献   
56.
Intraperitoneal injection of two doses of vinblastine (10 mg/kg and 50 mg/kg) induced a prominent formation of autophagic vacuoles in mouse liver parenchymal cells in 4 h. Clearly recognizable organelles were seen inside these vacuoles. The amount of autophagy was dependent on doses in that autophagosomes almost disappeared within 12 h with the low dose, whereas with the high dose the -ells were filled with residual bodies. Defecation of lysosomal material was ovserved into the sinusoidal lumen 12 h after injection with high dose. The total activities of lysosomal enzymes acid phosphatase, beta-galactosidase, and beta-acetylglucosaminidase did not change in the liver after vinblastine administration. The soluble activities of beta-galactosidase and beta-glucosaminidase were elevated with the high dose 12 h after injection, indicating labilization of the lysosomal membranes. Simultaneously the activities of the three lysosomal enzymes were elevated in the serum. The injurious effect of VBL appeared in light-and electron microscopic levels indicating diffuse necrosis of the liver lobules with the high gose within 12 h, fat accumulation in the cells, accumulation of secretory vesicles containing very low density lipoprotein particles, partial dilatation, vesiculation of endoplasmic reticulum and dilatation of Golgi cisternae. The serum GOT and CPK levels were also elevated  相似文献   
57.
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Journal of Computer Science and Technology - In this article, we survey the main achievements of moving objects with transportation modes that span the past decade. As an important kind of human...  相似文献   
58.
Here we address the following questions. How many structurally different entries are there in the Protein Data Bank (PDB)? How do the proteins populate the structural universe? To investigate these questions a structurally non-redundant set of representative entries was selected from the PDB. Construction of such a dataset is not trivial: (i) the considerable size of the PDB requires a large number of comparisons (there were more than 3250 structures of protein chains available in May 1994); (ii) the PDB is highly redundant, containing many structurally similar entries, not necessarily with significant sequence homology, and (iii) there is no clear-cut definition of structural similarity. The latter depend on the criteria and methods used. Here, we analyze structural similarity ignoring protein topology. To date, representative sets have been selected either by hand, by sequence comparison techniques which ignore the three-dimensional (3D) structures of the proteins or by using sequence comparisons followed by linear structural comparison (i.e. the topology, or the sequential order of the chains, is enforced in the structural comparison). Here we describe a 3D sequence-independent automated and efficient method to obtain a representative set of protein molecules from the PDB which contains all unique structures and which is structurally non-redundant. The method has two novel features. The first is the use of strictly structural criteria in the selection process without taking into account the sequence information. To this end we employ a fast structural comparison algorithm which requires on average approximately 2 s per pairwise comparison on a workstation. The second novel feature is the iterative application of a heuristic clustering algorithm that greatly reduces the number of comparisons required. We obtain a representative set of 220 chains with resolution better than 3.0 A, or 268 chains including lower resolution entries, NMR entries and models. The resulting set can serve as a basis for extensive structural classification and studies of 3D recurring motifs and of sequence-structure relationships. The clustering algorithm succeeds in classifying into the same structural family chains with no significant sequence homology, e.g. all the globins in one single group, all the trypsin-like serine proteases in another or all the immunoglobulin-like folds into a third. In addition, unexpected structural similarities of interest have been automatically detected between pairs of chains. A cluster analysis of the representative structures demonstrates the way the "structural universe' is populated.  相似文献   
59.
This article describes the community activation and policy change process in seven Minnesota communities involved in the Tobacco Policy Options for Prevention (TPOP) study. The study's intervention employed a direct action organizing model, which relies on mobilizing large numbers of people to alter decision making and leverage the power of elites. As part of the organizing process, TPOP organizers and teams made 1,319 personal contacts with community members, generated 309 media stories, and initiated 445 public events related to tobacco use. These actions resulted in the establishment of comprehensive tobacco ordinances in all seven communities. The authors discuss the goals, training, activities and political factors relevant to four phases of the TPOP intervention: information gathering and team recruitment, community awareness building and ordinance development, preparing for city council, and ordinance establishment and enforcement. Included are suggestions for practitioners interested in using policy change and community-based advocacy to resolve public health problems.  相似文献   
60.
The structure of the complex of the chorismate mutase from the yeast Saccharomyces cerevisiae with a transition state analog is constructed using a suite of docking tools. The construction finds the best location for the active site in the enzyme, and the best orientation of the analog compound in the active site. The resulting complex shows extensive salt links and hydrogen bonds between the enzyme and the compound, including those mediated by water molecules. A network of polar interactions between amino acid residues is found to solidify the active site of the enzyme. The enzymatic mechanism suggested for a bacterial chorismate mutase, that the active site is by design capable of selecting an active conformer of the substrate, and of stabilizing the transition state, is apparently intact in the yeast enzyme. No direct evidence is found to support an alternative mechanism which involves specific catalytic groups, although the possibility is not eliminated. This finding reinforces the notion of a function being evolutionarily conserved via a common mechanism, rather than via sequential or structural homology.  相似文献   
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