增强填料-聚合物相互作用降低轮胎滚动阻力

轮胎结构设计工程师宣称，他们已竭尽所能通过减小轮胎质量和改进轮胎设计降低滚动阻力，因此他们已转向请求胎面配方设计人员通过制造低滞后胎面胶料来完成这项工作。他们面临的问题是，如果简单地选择Tg较低的聚合物来获得理想的滞后，则必须牺牲某些其它性能，如湿牵引性，因此他们已致力于另一机理的研究。     

Recurrent and repeated infectious endocarditis: causes and preconditions (lecture)

A way of reducing the cost price of hospital automation is proposed. It is not necessary for it to update the whole equipment, but only a small part--the workstations used by programmers for their work, which support the stability of hospital automation; the working places of operators should be kept without modifications, but to allot them properties to inherit a potency and modernity of the purchased equipment; for this purpose they should be equipped with virtual machines copying properties of workstations being arrange in accordance with the pyramidal structure. A UNIX which represents a multi-user, multitask operational operative system providing an access on several pseudoterminals is simultaneously installed on the PENTIUM 100/133 workstation. A graphic terminal of the AMR "UnTerminal" firm (USA) is proposed for use as working places. Their advantage is that they have a special adapter connected directly to the bus of PC extension. Each user is allotted a video adapter, a keyboard controller, sequential and parallel interfaces for connection of the printer and manipulator. Each working place supports multitasking and it can be equipped with a printer, a "mouse" or modem. The image is transmitted on work places with a very high velocity-77 mehabits/sec that supports not only a text mode, but also VGA or SVGA graphics. Certainly, graphic terminals are more expensive than text terminals, but their capacities are similar to those of the main computer, here, the workstation. They may be located from the main computer at a distance of up to 75 meters or more and do not require adjustment during their installation.     

TRAUT: a Rorschach index for screening thought disorder. Tripartite Classification of Autisms

TRAUT, a new approach to the recognition and classification of perceptions on the Rorschach indicative of thought disorder, is based on the rationale that so-called autisms are really "absurdities" that lead to interpretive contradictions. Advantages of TRAUT's logically derived definitions include clarity, generalizeability, and teachability. TRAUT categorizes autisms according to whether they ignore the blot (HYPO), circumvent the task (HYPER) or rationalize counterfactual images by spatial juxtaposition (RELER). Norms and significance tests are presented, demonstrating that thought-disordered patients produce higher TRAUT scores than nonthought-disordered patients and normal individuals. TRAUT categories were also able to differentiate among various types of thought-disordered patients.     

Personal contact from friends to increase mammography usage

To increase the use of mammography among women 40 years of age and older, the American Cancer Society (ACS) designed a telephone intervention strategy (the "Tell A Friend" program) that relied on ACS volunteers. During a half-day training session, each volunteer provided a list of 10 women she was willing to contact over a 6-month period and encourage to have a mammogram. Each list was randomized, and five names were returned to each volunteer for inclusion in the intervention. The other women served as controls and were not contacted by the volunteers. All women were subsequently interviewed at the end of the intervention period. Forty-nine percent of the women in the intervention group (n = 289) had received their most recent mammogram since the start of the intervention period, whereas 34% of control women (n = 305) received mammograms during the same time period (p < or = .001, rate ratio = 1.4, 95% confidence interval = 1.2, 1.7). The effectiveness of the intervention remained after controlling for demographic characteristics. The strategy was effective for both black and white women of all ages, but principally among women with annual household incomes of less than $40,000. We conclude that a telephone intervention strategy of personal contacts between acquainted women can significantly increase mammography use, particularly among women with low-to-moderate income.     

Using simultaneous higher-level and partial lower-level data in reliability assessments

When a system is tested, besides system data, some lower-level data may become available such as a particular subsystem or component was successful or failed. Treating such simultaneous multi-level data as independent is a mistake because they are dependent. In this paper, we show how to handle simultaneous multi-level data correctly in a reliability assessment. We do this by determining what information the simultaneous data provides in terms of the component reliabilities using generalized cut sets. We illustrate this methodology with an example of a low-pressure coolant injection system using a Bayesian approach to make reliability assessments.     

National hospital discharge survey: annual summary, 1996

OBJECTIVES: This report presents national estimates of the use of non-Federal short-stay hospitals in the United States during 1996 and selected trend data. Estimates are provided by demographic characteristics of patients discharged, geographic region of hospitals, conditions diagnosed, and surgical and nonsurgical procedures performed. Measurements of hospital use include number and rate of discharges and days of care, and the average length of stay. METHODS: The estimates are based on data collected through the National Hospital Discharge Survey (NHDS). The survey has been conducted annually by the National Center for Health Statistics (NCHS) since 1965. In 1996, data were collected for approximately 282,000 discharges. Of the 507 eligible non-Federal short-stay hospitals in the sample, 480 (95 percent) responded to the survey. Diagnoses and procedures are coded according to the International Classification of Diseases, 9th Revision, Clinical Modification, or ICD-9-CM.     

Interactions between jointless and wild-type tomato tissues during development of the pedicel abscission zone and the inflorescence meristem

The jointless mutation of tomato results in the formation of flower pedicels that lack an abscission zone and inflorescence meristems that revert to vegetative growth. We have analyzed periclinal chimeras and mericlinal sectors of jointless and wild-type tissue to determine how cells in different meristem layers (L1, L2, and L3) and their derivatives interact during these two developmental processes. Cells in the inner meristem layer, L3, alone determined whether the meristem maintained the inflorescence state or reverted to vegetative growth. Moreover, L3 derivatives determined whether a functional pedicel abscission zone formed. Limited and disorganized autonomous development of wild-type L2-derived cells occurred when they overlay mutant tissue. Adjacent mutant and wild-type L3-derived tissues in pedicels developed autonomously, indicating little or no lateral communication. Only the outermost L3-derived cells within the pedicel were capable of orchestrating normal pedicel development in overlying tissues, revealing the special status of those cells as coordinators of development for L1- and L2-derived cells, whereas the innermost L3-derived cells developed autonomously but did not influence the development of other cells.     

Heat-induced oligomerization of the molecular chaperone Hsp90. Inhibition by ATP and geldanamycin and activation by transition metal oxyanions

It has been previously reported that heat shock protein 90 (Hsp90) oligomerizes at high temperatures and displays concomitantly a novel chaperone activity (Yonehara, M., Minami, Y., Kawata, Y., Nagai, J., and Yahara, I. (1996) J. Biol. Chem., 271, 2641-2645). In order to better define these oligomerization properties at high temperatures and to know whether they are influenced by modulators of Hsp90 function, heat-induced oligomerization of highly purified dimeric Hsp90 has been investigated over a wide range of temperature and protein concentrations by native polyacrylamide gel electrophoresis and size exclusion chromatography. Whereas below 50 degreesC, the dimeric form is maintained over a large range of concentrations, at the critical temperature of 50 degreesC, a sharp transition from dimeric to higher order oligomeric species takes place within minutes, in a highly ordered process, suggesting that a conformational change, leading to the appearance of a new oligomerization site, occurs in Hsp90 dimer. Moreover, at and above the critical temperature, the extent of oligomerization increases with Hsp90 concentration. Formation of high order oligomers at high temperatures is sensitive to modulators of Hsp90 function. ATP and geldanamycin, both known to bind to the same pocket of Hsp90, are inhibitors of this process, whereas molybdate, vanadate, and Nonidet P-40, which are thought to increase surface hydrophobicity of the protein, are activators. Thus, oligomerization of Hsp90 at high temperatures may be mediated through hydrophobic interactions that are hindered by ligands and favored by transition metal oxyanions. The fact that the heat-induced oligomerization of Hsp90 is affected by specific ligands that modulate its properties also suggests that this process may be involved in cell protection during heat shock.     

Spray-dried chitosan as a direct compression tableting excipient

The objective of this study was to prepare and evaluate a novel spray-dried tableting excipient using a mixture of chitosan and lactose. Three different grades of chitosan (low-, medium-, and high-molecular-weight) were used for this study. Propranolol hydrochloride was used as a model drug. A specific amount of chitosan (1, 1.9, and 2.5 g, respectively) was dissolved in 50 mL of an aqueous solution of citric acid (1%) and later mixed with 50 mL of an aqueous solution containing lactose (20, 19.1, and 18.5 g, respectively) and propanolol (2.2 g). The resultant solution was sprayed through a laboratory spray drier at 1.4 mL/min. The granules were evaluated for bulk density, tap density, Carr index, particle size distribution, surface morphology, thermal properties, and tableting properties. Bulk density of the granules decreased from 0.16 to 0.13 g/mL when the granules were prepared using medium- or high-molecular-weight chitosan compared with the low-molecular-weight chitosan. The relative proportion of chitosan also showed a significant effect on the bulk density. The granules prepared with 1 g of low-molecular-weight chitosan showed the minimum Carr index (11.1%) indicating the best flow properties among all five formulations. All three granules prepared with 1 g chitosan, irrespective of their molecular weight, showed excellent flow properties. Floating tablets prepared by direct compression of these granules with sodium bicarbonate showed 50% drug release between 30 and 35 min. In conclusion, the spray-dried granules prepared with chitosan and lactose showed excellent flow properties and were suitable for tableting.     

A glutamine 67--> histidine mutation in homotetrameric R67 dihydrofolate reductase results in four mutations per single active site pore and causes substantial substrate and cofactor inhibition

R67 dihydrofolate reductase (DHFR) is a type II DHFR produced by bacteria as a resistance mechanism to increasing clinical use of the antibacterial drug trimethoprim. Type II DHFRs are not homologous in either sequence or structure with chromosomal DHFRs. The crystal structure of R67 DHFR shows a single active site pore that spans the length of the homotetramer. Related sites (due to a 222 symmetry element at the center of the pore) are used to bind ligands, i.e. each half of the pore can accommodate either the substrate, dihydrofolate (DHF), or the cofactor, NADPH, although DHF and NADPH are bound differently. To evaluate the role of glutamine 67 (and its symmetry- related Q167, Q267 and Q367 residues which occur at the center of the active site pore), a Q67H mutation was constructed. Binary binding of dihydrofolate (DHF; monitored by isothermal titration calorimetry) displays two identical sites with a Kd value of 0.04 microM, while binding of NADPH shows two sites possessing negative cooperativity with Kd values of 0.027 and 0.62 microM. A comparison of ligand binding in Q67H versus wild-type (wt) R67 DHFR indicates both ligands bind more tightly (80-6000-fold) and DHF binding in Q67H R67 DHFR no longer displays positive cooperativity as seen in wt R67 DHFR. Ternary complex binding in the Q67H mutant indicates a total of two ligands can bind per pore. Substantial substrate and cofactor inhibition are observed during catalysis, consistent with non-productive binding of either two DHF or two NADPH molecules in Q67H R67 DHFR. Because of the symmetry- related binding sites in the active site pore, the accumulation of potentially positive mutations in R67 DHFR is limited by the balance between tighter binding of ligands (and thus potentially increased catalytic efficiency) and inhibition that arises upon tighter binding of two identical ligands at symmetry-related sites.