Self-centering probes with parallel kinematics to verify machine-tools

In this paper, a new type of self-centering probe is presented to verify the performance of machine-tools in an efficient and rapid way using ball artifacts. A self-centering probe is placed in the spindle of the machine-tool and a ball artifact on the work table. The probe is moved to the calibrated center positions of the balls of the reference artifact. The probe touches these balls and, in a single measurement, it provides the X, Y, Z offset of the actual machine position from the desired (programmed) position. A non-conventional probe design has been chosen: three independently movable probe styli form a miniature coordinate measuring machine with parallel kinematics. The development process of two variants of such a self-centering probe is presented in this paper. The results obtained in laboratory tests show a repeatability of less than 0.5 μm and an error range of less than 2 μm throughout the large measurement range (2 mm × 2 mm × 2 mm) of the probe.     

Perceived health and pregnancy: study of several behavioral and environmental determinants among a population of pregnant women

The nurturing of the adolescent patient's emerging sexuality can form the foundation for a lifelong ability to form intimate and trusting relationships. Teen pregnancy and sexually transmitted infections, the consequences of teen sexuality in crisis, impact the adolescent and our society. Psychosocial developmentally-appropriate counseling in the primary care physician's office must be part of each visit. A nonjudgmental, empathic approach is instrumental in the prevention of adolescent morbidity and mortality.     

Same-sex attraction, social relationships, psychosocial functioning, and school performance in early adolescence.

The authors examined whether 13- to 15-year-old adolescents who experience feelings of same-sex attraction (SSA) differ from those without such feelings in the quality of relationships with parents, peers, and class mentors and in psychosocial functioning (health status and school performance). The authors also assessed whether differences in psychosocial functioning resulted from differences in the quality of social relationships. Data were collected from 866 Dutch high school students (mean age 13.61 years) by means of a computer-based questionnaire. Of the participants, 74 (8.5%) reported having feelings of SSA. The participants with SSA rated the quality of their relationships with their fathers and their peers lower than did those without SSA. Participants with SSA also had poorer mental health (higher levels of depression and lower levels of self-esteem) and lower school performance. A mediation analysis revealed that differences in psychosocial functioning resulted from differences in the quality of the same-sex attracted youths' social relationships, especially with fathers and peers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

3D‐Printable Antimicrobial Composite Resins

3D printing is seen as a game‐changing manufacturing process in many domains, including general medicine and dentistry, but the integration of more complex functions into 3D‐printed materials remains lacking. Here, it is expanded on the repertoire of 3D‐printable materials to include antimicrobial polymer resins, which are essential for development of medical devices due to the high incidence of biomaterial‐associated infections. Monomers containing antimicrobial, positively charged quaternary ammonium groups with an appended alkyl chain are either directly copolymerized with conventional diurethanedimethacrylate/glycerol dimethacrylate (UDMA/GDMA) resin components by photocuring or prepolymerized as a linear chain for incorporation into a semi‐interpenetrating polymer network by light‐induced polymerization. For both strategies, dental 3D‐printed objects fabricated by a stereolithography process kill bacteria on contact when positively charged quaternary ammonium groups are incorporated into the photocurable UDMA/GDMA resins. Leaching of quaternary ammonium monomers copolymerized with UDMA/GDMA resins is limited and without biological consequences within 4–6 d, while biological consequences could be confined to 1 d when prepolymerized quaternary ammonium group containing chains are incorporated in a semi‐interpenetrating polymer network. Routine clinical handling and mechanical properties of the pristine polymer matrix are maintained upon incorporation of quaternary ammonium groups, qualifying the antimicrobially functionalized, 3D‐printable composite resins for clinical use.     

Influence of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) on the localization of cathepsin B and cathepsin L in human lung tumor cells

Scatter factor (SF), also known as hepatocyte growth factor, is a potent mitogen that has been suggested to exhibit greater efficacy than vascular endothelial growth factor (VEGF) in rabbits with hindlimb ischemia. Our study examined the effects of SF on cardiovascular hemodynamics and compared the responses to VEGF. Hemodynamic parameters were monitored before and after administration of SF or VEGF in conscious, instrumented rats. Intravenous injection of SF produced a dose-related reduction in mean arterial pressure (MAP) and increase in heart rate (HR). These responses were significantly attenuated by pretreatment with N omega-nitro-L-arginine methyl ester a nitric oxide (NO) synthase inhibitor, suggesting the depressor effect of SF may be mediated by NO. SF (250 micrograms/kg) reduced stroke volume and cardiac output, but did not affect the maximal first derivation of left ventricular pressure (dP/dt), suggesting that the reduction in cardiac output is caused by decreased stroke volume that probably results from a reduction in venous return. Compared with SF, VEGF produced greater hypotensive and tachycardic responses and greater reductions in stroke volume and cardiac output, indicating that SF has fewer side effects on hemodynamics. Although both growth factors might reduce venous return, SF decreased hematocrit presumably through venodilation, whereas VEGF increased hematocrit as a result of vascular hyperpermeability.     

The ‘Cash-Point’ Service: A Verification Case Study Using STeP

STeP, the Stanford Temporal Prover, supports the computer-aided formal verification of concurrent and reactive systems based on temporal specifications [MBB99]. Automated model checking is combined with computer-aided deductive methods to allow for the verification of a broad class of systems, including parameterised (N-component) circuit designs, parameterised (N-process) programs, and programs with infinite data domains. Received February 2000 / Accepted in revised form December 2000     

Values as determinants of preferences for housing attributes

Preferences for housing attributes have beenstudied from different theoretical perspectivesand with a great variety of methodologicalapproaches. In explaining housing preferencesthe influence of both macro-level andmicro-level factors has been shownextensively. Relatively little attention hasbeen given, though, to motivational micro-levelfactors such as goals and values. In thisarticle micro-level motivational factors arestudied as determinants of stated preferencesfor housing attributes. The relationshipsbetween such motivational factors as values andgoals on the one hand and preferences forhousing attributes on the other are consideredfrom the perspective of means-end theory. Asemi-structured interviewing technique calledladdering is used for the measurement ofmeans-end chains. Some of the results of apilot project in which means-end theory wasapplied to preferences for housing attributeswill be discussed in the sequel.     

Direct TEM Observation of Phase Separation and Crystallization in Cu_(45)Zr_(45)Ag_(10)Metallic Glass

The structural evolution of Cu_(45)Zr_(45)Ag_(10) metallic glass was investigated by in situ transmission electron microscopy heating experiments. The relationship between phase separation and crystallization was elucidated. Nucleation and growth-controlled nanoscale phase separation at early stage were seen to impede nanocrystallization, while a coarser phase separation via aggregation of Ag-rich nanospheres was found to promote the precipitation of Cu-rich nanocrystals.Coupling of composition and dynamics heterogeneities was supposed to play a key role during phase separation preceding crystallization.