On gravitational-wave spectroscopy of massive black holes with the space interferometer LISA

Newly formed black holes are expected to emit characteristic radiation in the form of quasi-normal modes, called ringdown waves, with discrete frequencies. LISA should be able to detect the ringdown waves emitted by oscillating supermassive black holes throughout the observable Universe. We develop a multi-mode formalism, applicable to any interferometric detectors, for detecting ringdown signals, for estimating black hole parameters from those signals, and for testing the no-hair theorem of general relativity. Focusing on LISA, we use current models of its sensitivity to compute the expected signal-to-noise ratio for ringdown events, the relative parameter estimation accuracy, and the resolvability of different modes. We also discuss the extent to which uncertainties on physical parameters, such as the black hole spin and the energy emitted in each mode, will affect our ability to do black hole spectroscopy.Comment: 44 pages, 21 figures, 10 tables. Minor changes to match version in press in Phys. Rev.

Baseline Shifts do not Predict Attentional Modulation of Target Processing During Feature-Based Visual Attention

Cues that direct selective attention to a spatial location have been observed to increase baseline neural activity in visual areas that represent a to-be-attended stimulus location. Analogous attention-related baseline shifts have also been observed in response to attention-directing cues for non-spatial stimulus features. It has been proposed that baseline shifts with preparatory attention may serve as the mechanism by which attention modulates the responses to subsequent visual targets that match the attended location or feature. Using functional MRI, we localized color- and motion-sensitive visual areas in individual subjects and investigated the relationship between cue-induced baseline shifts and the subsequent attentional modulation of task-relevant target stimuli. Although attention-directing cues often led to increased background neural activity in feature specific visual areas, these increases were not correlated with either behavior in the task or subsequent attentional modulation of the visual targets. These findings cast doubt on the hypothesis that attention-related shifts in baseline neural activity result in selective sensory processing of visual targets during feature-based selective attention

Piezoelectric-based apparatus for strain tuning

We report the design and construction of piezoelectric-based apparatus for applying continuously tuneable compressive and tensile strains to test samples. It can be used across a wide temperature range, including cryogenic temperatures. The achievable strain is large, so far up to 0.23% at cryogenic temperatures. The apparatus is compact and compatible with a wide variety of experimental probes. In addition, we present a method for mounting high-aspect-ratio samples in order to achieve high strain homogeneity.Comment: 8 pages, 8 figure

Non-equilibrium microtubule fluctuations in a model cytoskeleton

Biological activity gives rise to non-equilibrium fluctuations in the cytoplasm of cells; however, there are few methods to directly measure these fluctuations. Using a reconstituted actin cytoskeleton, we show that the bending dynamics of embedded microtubules can be used to probe local stress fluctuations. We add myosin motors that drive the network out of equilibrium, resulting in an increased amplitude and modified time-dependence of microtubule bending fluctuations. We show that this behavior results from step-like forces on the order of 10 pN driven by collective motor dynamics

Efficacy and safety of sitagliptin for the treatment of new-onset diabetes after renal transplantation.

New-onset diabetes after transplantation (NODAT) is a common comorbidity after renal transplantation. Though metformin is the first-line agent for the treatment of type 2 diabetes, in renal transplant recipients, metformin is frequently avoided due to concerns about renal dysfunction and risk for lactic acidosis. Therefore, alternative first-line agents for the treatment of NODAT in renal transplant recipients are needed. Sitagliptin, a dipeptidyl-peptidase-4 (DPP-4) inhibitor, has a low incidence of hypoglycemia, is weight neutral, and, in a small study, did not affect immunosuppressant levels. However, long-term sitagliptin use for the treatment of NODAT in kidney transplant recipients has not been studied. We retrospectively analyzed renal transplant recipients diagnosed with NODAT and treated with sitagliptin to assess safety and efficacy. Twenty-two patients were started on sitagliptin alone. After 12 months of followup, 19/22 patients remained on sitagliptin alone with a significant improvement in hemoglobin A1c. Renal function and immunosuppressant levels remained stable. Analysis of long-term followup (32.5 ± 17.8 months) revealed that 17/22 patients remained on sitagliptin (mean hemoglobin A1c \u3c 7%) with 9/17 patients remaining on sitagliptin alone. Transplant-specific adverse events were rare. Sitagliptin appears safe and efficacious for the treatment of NODAT in kidney transplant recipients

Experimental implementation of optimal WLAN channel selection without communication

Proposed a simple decentralised algorithm for channel allocation that is provably correct and requires no message passing or common administrative control between interfering WLANs. In this paper we implement this algorithm using a standard 802.11 hardware testbed and demonstrate that it does indeed offer the potential for effective channel allocation in realistic environments. This includes environments with complex, spatially varying noise and channel dependent propagation behaviour and with time-varying load