Investigation of Surface Integrity Induced by Ultra-Precision Grinding and Scratching of Glassy Carbon

Glassy carbon provides material characteristics that make it a promising candidate for use as a mould material in precision glass moulding. However, to effectively utilize glassy carbon, a thorough investigation into the machining of high-precision optical surfaces is necessary, which has not been thoroughly investigated. This research analyses the process of material removal and its resulting surface integrity through the use of nano-scratching and ultra-precision grinding. The nano-scratching process begins with ductile plastic deformation, then progresses with funnel-shaped breakouts in the contact zone, and finally concludes with brittle conchoidal breakouts when the cutting depth is increased. The influence of process factors and tool-related parameters resulting from grinding has discernible impacts on the ultimate surface roughness and topography. Enhancing the cutting speed during cross-axis kinematic grinding results in improved surface roughness. Increasing the size of diamond grains and feed rates leads to an increase in surface roughness. An achievable surface roughness of Ra < 5 nm together with ductile-regime grinding behaviour meet optical standards, which makes ultra-precision grinding a suitable process for optical surface generation.

The strong arm of the law: a unified account of necessary and contingent laws of nature

A common feature of all standard theories of the laws of nature is that they are 'absolutist': They take laws to be either all metaphysically necessary or all contingent. Science, however, gives us reason to think that there are laws of both kinds, suggesting that standard theories should make way for 'non-absolutist' alternatives: theories which accommodate laws of both modal statuses. In this paper, we set out three explanatory challenges for any candidate non-absolutist theory, and discuss the prospects of the two extant candidates in light of these challenges. We then develop our own non-absolutist theory, the essentialist DTA account, which combines the nomic-necessitation or DTA account with an essentialist approach to metaphysical modality in order to meet the three explanatory challenges. Finally, we argue that the distinction between kinematical and dynamical laws found in physical theories supports both non-absolutism in general and our proposed essentialist DTA view in particular.

The modal status of the laws of nature. Tahko's hybrid view and the kinematical/dynamical distinction

In a recent paper, Tuomas Tahko has argued for a hybrid view of the laws of nature, according to which some physical laws are metaphysically necessary, while others are metaphysically contingent. In this paper, we show that his criterion for distinguishing between these two kinds of laws - which crucially relies on the essences of natural kinds - is on its own unsatisfactory. We then propose an alternative way of drawing the metaphysically necessary/contingent distinction for laws of physics based on the central kinematical/dynamical distinction used in physical theorising, and argue that the criterion can be used to amend Tahko's own account, but also that it can be combined with different metaphysical views about the source of necessity.

Magnification—a New Look at a Long-known Optical Property of Dentin

Light propagation in human dentin exhibits a strong directional dependence featuring the long-known optical magnification property. We hypothesized that this anisotropic effect is caused by multiple scattering at the dentin tubules, and not by fiberoptic effects, as had been previously assumed. We performed measurements of the transmitted intensity from dentin disks and compared them with Monte Carlo simulations of light propagation in dentin, considering the scattering by the tissue’s microstructure. We found that the optical anisotropy of dentin can be fully explained with this model. We concluded that the magnification property of dentin is due to multiple scattering by the dental microstructure.

Thoughts on the Present and Future of Psychoanalytic Education

This paper originated in a series of dialogues between the authors over a period of approximately one year, focused on present problems (and possible solutions) in psychoanalytic education, internationally but particularly in the U.S. Both authors have been involved in psychoanalytic education and governance over many years and share a concern with where psychoanalysis presently stands and where it is going. They share the experience of being part of what today is a significant minority of psychoanalysts involved in academic pursuits, thus being situated at the boundary between psychoanalysis and university-based psychiatry as professions. Having been involved in the leadership of both psychoanalytic and psychiatric organizations, they share an interest in organizational theory, an additional joint interest influencing their approach to institutional aspects of psychoanalysis. Despite these commonalities, however, they have been identified as having differently shaded positions and views within psychoanalytic politics: Robert Michels, as relatively conservative regarding controversial issues in psychoanalytic institutional functioning and governance, and Otto Kernberg as inclined toward rapid change regarding these issues (Auchincloss and Michels 2003; Kernberg 2014). This difference determined a dynamic of particular interest in their dialogue: the extent to which mutual respect yet differing viewpoints might issue in an analysis and joint recommendations that might be of interest to the field. In what follows, their achievement in that direction is spelled out in some detail.

Neuroscience in the residency curriculum: the psychoanalytic psychotherapy perspective

Educators of future psychiatrists tend to teach an array of approaches to the mind and brain, including among them the neurobiologic perspective and the psychoanalytic perspective. These may be considered at opposite ends of many spectra, including the fact that psychoanalysis takes a large-scale and treatment-oriented perspective and has helped countless patients over the years, while neuroscience has tended to be reductionistic, focused on understanding, and has helped very few people. A tension, therefore, exists for the educator in teaching neuroscience: is it wise to spend valuable time and energy teaching this interesting but, thus far, impractical field to future practitioners? Here, we argue that neuroscience is re-orienting itself towards more psychoanalytically relevant questions and is likely, in future years, to give new insights into the nature of basic drives and social relations. We additionally argue for balance on the part of providers in both acknowledging biologic underpinnings for clinical phenomena and yet continuing to take a stance oriented towards appropriate change. Given the burgeoning new focus within neuroscience on topics directly relating to the human internal experience and the novel challenges in both understanding those advances and appropriately using them, we encourage educators to continue to give future psychiatrists the educational foundation they need to follow neuroscientific discoveries into the future.

NEbivolol inhibition of coronary artery smooth muscle cell proliferation after percutaneous coronary artery intervention. Results of the NESCIO Study, a randomized, double blind trial

OBJECTIVES

This study compared the efficacy of metoprolol and nebivolol in reducing the frequency of in-stent restenosis (ISR) after a percutaneous coronary intervention (PCI).

BACKGROUND

ISR results from excessive neointimal proliferation. Nebivolol inhibits proliferation of human coronary endothelial and smooth muscle cells in vitro. Its efficacy has not been studied in clinical trials.

MATERIAL AND METHODS

In a single-centre double-blind study, 79 subjects with de novo lesions were randomly assigned to receive either nebivolol (n=37) or metoprolol (n=42) 3 to 7 days before elective PCI with bare metal stents. The study medication was continued for 6 months. Nebivolol was administered at 5 mg/day for 3 weeks, then at 10 mg/day. Metoprolol was administered at 100 mg/day. The endpoints were the difference in fractional flow reserve (deltaFFR) between values immediately after PCI and those at 6 months and ISR during the 6 months following PCI The study was powered to detect a deltaFFR of 6% with 30 subjects per treatment group.

RESULTS

Among subjects who underwent angiography at 6 months, mean deltaFFR was--0.08 for the nebivolol group (n=25) and -0.12 in the metoprolol group (n=26; p = 0.367). ISR occurred in 11 subjects (26.2%) on metoprolol and in 3 (8.1%) on nebivolol during treatment, and in 7 subjects on metoprolol and in 3 on nebivolol at 6 months (p = 0.014)

CONCLUSION

There was a non-significant trend toward less decline in detaFFR at 6 months with nebivolol. Nebivolol should be investigated further in larger trials. Nebivolol significantly reduced the frequency of ISR as compared to metoprolol.