Ellipsoidal optical reflectors reproduced by electroforming

An accurately dimensioned convex ellipsoidal surface, which will become a master after polishing, is fabricated from 316L stainless steel. When polishing of the master is completed, it is suspended in a modified watt bath for electroforming of nickel reflectors

Conforming polisher for aspheric surface of revolution Patent

Conforming polisher for aspheric surfaces of revolution with inflatable tub

Lathe converted for grinding aspheric surfaces

A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile

LDC savings rates and debt crises

Conventional wisdom holds that LDC debt problems reflect, in part, the switch of foreign financing towards commercial loans. With no adequate supervision over the use of these funds, international finance may not have improved the capacity to repay external debt. This paper tests two aspects of this proposition. First, have commercial loans been directed more towards consumption and less to investment than official loans? We find no evidence to suggest this has been true. Second, does an increase in the marginal propensity to invest out of foreign loans improve creditworthiness? Again, we find no supporting evidence. We do find, however, that raising the marginal rate of domestic saving out of income does improve creditworthiness. This provides justification for policy conditionality associated with foreign borrowing that goes beyond concern with the uses of individual loans.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27256/1/0000265.pd

Somatic Mutations in NEK9 Cause Nevus Comedonicus

Acne vulgaris (AV) affects most adolescents, and of those affected, moderate to severe disease occurs in 20%. Comedones, follicular plugs consisting of desquamated keratinocytes and sebum, are central to its pathogenesis. Despite high heritability in first-degree relatives, AV genetic determinants remain incompletely understood. We therefore employed whole-exome sequencing (WES) in nevus comedonicus (NC), a rare disorder that features comedones and inflammatory acne cysts in localized, linear configurations. WES identified somatic NEK9 mutations, each affecting highly conserved residues within its kinase or RCC1 domains, in affected tissue of three out of three NC-affected subjects. All mutations are gain of function, resulting in increased phosphorylation at Thr210, a hallmark of NEK9 kinase activation. We found that comedo formation in NC is marked by loss of follicular differentiation markers, expansion of keratin-15-positive cells from localization within the bulge to the entire sub-bulge follicle and cyst, and ectopic expression of keratin 10, a marker of interfollicular differentiation not present in normal follicles. These findings suggest that NEK9 mutations in NC disrupt normal follicular differentiation and identify NEK9 as a potential regulator of follicular homeostasis

Optimal geographic diversification and firm performance:evidence from the U.K.

This paper examines the relationship between multinationality and firm performance. The analysis is based on a sample of over 400 UK multinationals, and encompasses both service sector and manufacturing sector multinationals. This paper confirms the non-linear relationship between performance and multinationality that is reported elsewhere in the literature, but offers further analysis of this relationship. Specifically, by correcting for endogeneity in the investment decision, and for shocks in productivity across countries, the paper demonstrates that the returns to multinationality are greater than those that have been reported elsewhere, and persist to higher degrees of international diversification

Challenging the production function approach to assess the developmental effects of FDI

From a theoretical point of view, it is traditionally assumed that foreign firms possess a centrally accumulated firm-specific technological advantage over domestic firms (see, for example, Findlay, 1978; Dunning, 1979). Given a sufficient level of absorptive capacity and human capital, domestic firms in host economies are able to benefit from various externalities stimulated by the presence of foreign firms

Evaluation of the impact of vasa previa on feto-placental hormonal synthesis and fetal growth

Introduction A vasa previa (VP) refers to aberrant chorionic vessels which can either connect the chorionic plate to a velamentous cord (type I) or a succenturiate or accessory lobe to the main placental mass (type II). Methods We performed retrospective cohort study of 32 singleton pregnancies diagnosed with VP. The levels of maternal serum alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG) and unconjugated estriol (uE3) were measured at 15–18 weeks as part of the triple test screening for Trisomy 21. The data were subdivided according to the type of VP and compared with those of a control group with central cord insertion and no succenturiate or accessory placental lobe. Results Twenty one (65.6%) parturient women presented with VP type I and 11 (34.4%) with VP type II. The mean birthweight and placental weight was significantly higher in pregnancies with VP type II than in pregnancies with VP with VP type I (3037.3 ± 400.9 gr vs 2493.5 ± 491.6 gr; p = 0.004 and 511.0 ± 47.2 gr vs 367.1 ± 64.3 gr; p < 0.0001; respectively). The mean hCG level in VP type II was significantly (p < 0.001) higher than those with type I (2.38 MoM vs 1.17 MoM) and compared to controls (2.38 MoM vs 0.99 MoM). Conclusions There is no obvious impact on both placental and fetal growth in VP type II. By contrast, VP type I is associated with slower feto-placental growth secondary to impaired development and biological functions of the placenta during the first half of pregnancy