Gravity waves in parity-violating Copernican universes

In recent work minimal theories allowing the variation of the cosmological constant, Λ , by means of a balancing torsion, have been proposed. It was found that such theories contain parity violating homogeneous and isotropic solutions, due to a torsion structure called the Cartan spiral staircase. Their dynamics are controlled by Euler and Pontryagin quasitopological terms in the action. Here we show that such theories predict a dramatically different picture for gravitational wave fluctuations in the parity violating branch. If the dynamics are ruled solely by the Euler-type term, then linear tensor mode perturbations are entirely undetermined, hinting at a new type of gauge invariance. The Pontryagin term not only permits for phenomenologically sounder background solutions (as found in previous literature), but for realistic propagation of gravitational wave modes. These have the general property that the right and left handed gravitational waves propagate with different speeds. More generally they imply modified dispersion relations for the graviton, with both parity violating and non-violating deformations, including an effective mass for both gravitational wave polarizations. We discuss the observational constraints and predictions of these theories

Small molecule activators of SIRT1 replicate signaling pathways triggered by calorie restriction in vivo

<p>Abstract</p> <p>Background</p> <p>Calorie restriction (CR) produces a number of health benefits and ameliorates diseases of aging such as type 2 diabetes. The components of the pathways downstream of CR may provide intervention points for developing therapeutics for treating diseases of aging. The NAD⁺-dependent protein deacetylase SIRT1 has been implicated as one of the key downstream regulators of CR in yeast, rodents, and humans. Small molecule activators of SIRT1 have been identified that exhibit efficacy in animal models of diseases typically associated with aging including type 2 diabetes. To identify molecular processes induced in the liver of mice treated with two structurally distinct SIRT1 activators, SIRT501 (formulated resveratrol) and SRT1720, for three days, we utilized a systems biology approach and applied Causal Network Modeling (CNM) on gene expression data to elucidate downstream effects of SIRT1 activation.</p> <p>Results</p> <p>Here we demonstrate that SIRT1 activators recapitulate many of the molecular events downstream of CR <it>in vivo</it>, such as enhancing mitochondrial biogenesis, improving metabolic signaling pathways, and blunting pro-inflammatory pathways in mice fed a high fat, high calorie diet.</p> <p>Conclusion</p> <p>CNM of gene expression data from mice treated with SRT501 or SRT1720 in combination with supporting <it>in vitro </it>and <it>in vivo </it>data demonstrates that SRT501 and SRT1720 produce a signaling profile that mirrors CR, improves glucose and insulin homeostasis, and acts via SIRT1 activation <it>in vivo</it>. Taken together these results are encouraging regarding the use of small molecule activators of SIRT1 for therapeutic intervention into type 2 diabetes, a strategy which is currently being investigated in multiple clinical trials.</p

A New Definition of Entropy of Belief Functions in the Dempster-Shafer Theory

We propose a new definition of entropy for basic probability assignments (BPA) in the Dempster-Shafer (D-S) theory of belief functions, which is interpreted as a measure of total uncertainty in the BPA. Our definition is different from the definitions proposed by H¨ohle, Smets, Yager, Nguyen, Dubois-Prade, Lamata-Moral, Klir-Ramer, Klir-Parviz, Pal et al., MaedaIchihashi, Harmanec-Klir, Jousselme et al., and Pouly et al. We state a list of five desired properties of entropy for D-S belief functions theory that are motivated by Shannon’s definition of entropy for probability functions together with the requirement that any definition should be consistent with the semantics of D-S belief functions theory

Experimental and numerical study of cemented bone-implant interface behavior

Although the total hip replacement (THR) is a long-proven method of surgical treatment of diseases and disorders of the human hip, the surgery brings some risk of long-term instability of the joint. The aim of the research was to investigate the cemented bone-implant interface behavior. The main problems (cement layer degradation and bone-cement interface debonding) during physiological loading conditions have been investigated using a custom hip simulator. The experimental setup was designed to allow cyclic loading of the sample of pelvic bone with implanted cemented acetabular component. The hip contact force of required direction and magnitude was applied to the implant using a spherical femoral component head. The most unfavorable activity (downstairs walking) was simulated. The process of damage accumulation in the fixation was monitored by repeated scanning using high resolution micro Computed Tomography (µCT). Use of micro-focus source and large high-resolution flat panel detector allows investigation of structural changes and crack propagation both in the cement layer and the trabecular bone

Timing System for the Laser Altimeter for Planetary Exploration Technology Demonstrator

We are presenting the design, construction and tests of the timing system for the Laser Altimeter technology demonstrator. Altimeter Timing System (ATS) is a universal timing system for laser ranging in ground-ground, air-ground and ground-satellite experiments. It is dedicated to measure precise time interval with sub-nanosecond resolution. The device for advanced range gating is included. The unit is interfaced to a host personal computer via a serial data link for control, two-way data transfer and diagnostics. The entire ATS has been designed and constructed on the basis of the Portable Calibration Standard (PCS) for satellite laser ranging, which has been developed in our labs within the last ten years. To reduce the complexity, costs, weight and power, considering the modest timing resolution requirements, the sub-nanoseconds instead of picoseconds resolution of the time intervals, the timing part of the original device has been replaced by the Mini Counter. The overall design philosophy, the operational control software, the epoch timing, the range gate generation have been preserved along with the concept of the host computer software package for data acquisition, control and data analysis including the communication protocol, data and command formats etc. The use of well-tested concept of both the HW and SW enabled to shorten the design, construction and testing phase of the final device down to several weeks. The ATS consists of the Mini Counter module, the epoch timing and range gate generator module, the control processing unit, the input/output circuits and of the power supplies. The entire control logic hardware including the epoch timing and range gate generator and the input/output board logic is based on the FPGA (ispGAL) programmable logical arrays. There is a significant array capacity still available for future functional extensions and device upgrades, the arrays are field programmable. This fact ensures the maximum device flexibility and upgradability. The main parameters are: resolution 0.25 ns, linearity and stability better than 0.1 ns and 0.1 ns per K and per hour resp. The laser fire epoch resolution is 100 ns, the range gate is programmable in 40 ns steps. The device is small (2 kg), low power, it is capable to operate 3 hours on eight pieces of AA batteries