Analytical and experimental investigation of gas bearing tilting pad pivots Final report

Fretting damage in gas bearing tilting pad pivot

Comparison of LOQC C-sign gates with ancilla inefficiency and an improvement to functionality under these conditions

We compare three proposals for non-deterministic C-sign gates implemented using linear optics and conditional measurements with non-ideal ancilla mode production and detection. The simplified KLM gate [Ralph et al, Phys.Rev.A {\bf 65}, 012314 (2001)] appears to be the most resilient under these conditions. We also find that the operation of this gate can be improved by adjusting the beamsplitter ratios to compensate to some extent for the effects of the imperfect ancilla.Comment: to appear in PR

Validation Capital

Although it is well understood that activist shareholders challenge management, they can also serve as a shield. This Article describes “validation capital,” which occurs when a bloc holder’s — and generally an activist hedge fund’s — presence protects management from shareholder interference and allows management’s pre-existing strategy to proceed uninterrupted. When a sophisticated bloc holder with a large investment and the ability to threaten management’s control chooses to vouch for management’s strategy after vetting it, this support can send a credible signal to the market that protects management from disruption. By protecting a value-creating management strategy that might otherwise be misjudged, providers of validation capital benefit all shareholders, including themselves. However, validation capital may also have a dark side: it could be used to entrench under-performing management from outside interference that would benefit the company and its shareholders. In this scenario, the bloc holder acts as a hired “bodyguard” who receives a side payment in exchange for the promise to ward off other investors. We argue that legal and market forces do much to constrain the corrupt form of validation capital, and our empirical study of hedge fund activism events from 2015 offers evidence in support of our theory. We find that although side payments from corporate management to hedge funds are relatively common, they tend to be small and not of the magnitude necessary to induce corruption of the sophisticated funds capable of generating a persuasive signal

Selection of reliable reference genes for the normalisation of gene expression levels following time course LPS stimulation of murine bone marrow derived macrophages

© 2017 The Author(s). Background: Macrophages are key players in the initiation, perpetuation and regulation of both innate and adaptive immune responses. They largely perform these roles through modulation of the expression of genes, especially those encoding cytokines. Murine bone marrow derived macrophages (BMDMs) are commonly used as a model macrophage population for the study of immune responses to pro-inflammatory stimuli, notably lipopolysaccharide (LPS), which may be pertinent to the human situation. Evaluation of the temporal responses of LPS stimulated macrophages is widely conducted via the measurement of gene expression levels by RT-qPCR. While providing a robust and sensitive measure of gene expression levels, RT-qPCR relies on the normalisation of gene expression data to a stably expressed reference gene. Generally, a normalisation gene(s) is selected from a list of "traditional" reference genes without validation of expression stability under the specific experimental conditions of the study. In the absence of such validation, and given that many studies use only a single reference gene, the reliability of data is questionable. Results: The stability of expression levels of eight commonly used reference genes was assessed during the peak (6 h) and resolution (24 h) phases of the BMDM response to LPS. Further, this study identified two additional genes, which have not previously been described as reference genes, and the stability of their expression levels during the same phases of the inflammatory response were validated. Importantly, this study demonstrates that certain "traditional" reference genes are in fact regulated by LPS exposure, and, therefore, are not reliable candidates as their inclusion may compromise the accuracy of data interpretation. Testament to this, this study shows that the normalisation of gene expression data using an unstable reference gene greatly affects the experimental data obtained, and, therefore, the ultimate biological conclusions drawn. Conclusion: This study reaffirms the importance of validating reference gene stability for individual experimental conditions. Given that gene expression levels in LPS stimulated macrophages is routinely used to infer biological phenomena that are of relevance to human conditions, verification of reference gene expression stability is crucial

Elastic forces that do no work and the dynamics of fast cracks

Elastic singularities such as crack tips, when in motion through a medium that is itself vibrating, are subject to forces orthogonal to the direction of motion and thus impossible to determine by energy considerations alone. This fact is used to propose a universal scenario, in which three dimensionality is essential, for the dynamic instability of fast cracks in thin brittle materials.Comment: 8 pages Latex, 1 Postscript figur

Self-Accleration and Instability of Gravity Wave Packets: 1. Effects of Temporal Localization

An anelastic numerical model is used to explore the dynamics accompanying the attainment of large amplitudes by gravity waves (GWs) that are localized in altitude and time. GW momentum transport induces mean flow variations accompanying a GW packet that grows exponentially with altitude, is localized in altitude, and induces significant GW phase speed, and phase, variations across the GW packet. These variations arise because the GW occupies the region undergoing accelerations, with the induced phase speed variations referred to as “self-acceleration.” Results presented here reveal that self-acceleration of a GW packet localized in time and altitude ultimately leads to stalling of the vertical propagation of the GW packet and accompanying two- and three-dimensional (2-D and 3-D) instabilities of the superposed GW and mean motion field. The altitudes at which these effects occur depend on the initial GW amplitude, intrinsic frequency, and degree of localization in time and altitude. Larger amplitudes and higher intrinsic frequencies yield strong self-acceleration effects at lower altitudes, while smaller amplitudes yield similar effects at higher altitudes, provided the Reynolds number, Re, is sufficiently large. Three-dimensional instabilities follow 2-D “self-acceleration instability” for sufficiently high Re. GW packets can also exhibit self-acceleration dynamics at more than one altitude because of continued growth of the GW packet leading edge above the previous self-acceleration event. --From the publisher\u27s website