Computational modelling of movement-related beta-oscillatory dynamics in human motor cortex

Oscillatory activity in the beta range, in human primary motor cortex (M1), shows interesting dynamics that are tied to behaviour and change systematically in disease. To investigate the pathophysiology underlying these changes, we must first understand how changes in beta activity are caused in healthy subjects. We therefore adapted a canonical (repeatable) microcircuit model used in dynamic causal modelling (DCM) previously used to model induced responses in visual cortex. We adapted this model to accommodate cytoarchitectural differences between visual and motor cortex. Using biologically plausible connections, we used Bayesian model selection to identify the best model of measured MEG data from 11 young healthy participants, performing a simple handgrip task. We found that the canonical M1 model had substantially more model evidence than the generic canonical microcircuit model when explaining measured MEG data. The canonical M1 model reproduced measured dynamics in humans at rest, in a manner consistent with equivalent studies performed in mice. Furthermore, the changes in excitability (self-inhibition) necessary to explain beta suppression during handgrip were consistent with the attenuation of sensory precision implied by predictive coding. These results establish the face validity of a model that can be used to explore the laminar interactions that underlie beta-oscillatory dynamics in humans in vivo. Our canonical M1 model may be useful for characterising the synaptic mechanisms that mediate pathophysiological beta dynamics associated with movement disorders, such as stroke or Parkinson's disease

Skeletal muscle ATP turnover by 31P magnetic resonance spectroscopy during moderate and heavy bilateral knee-extension

During constant-power high-intensity exercise, the expected increase in oxygen uptake (V̇O2) is supplemented by a V̇O2 slow component (V̇O2 sc ), reflecting reduced work efficiency, predominantly within the locomotor muscles. The intracellular source of inefficiency is postulated to be an increase in the ATP cost of power production (an increase in P/W). To test this hypothesis, we measured intramuscular ATP turnover with (31)P magnetic resonance spectroscopy (MRS) and whole-body V̇O2 during moderate (MOD) and heavy (HVY) bilateral knee-extension exercise in healthy participants (n = 14). Unlocalized (31)P spectra were collected from the quadriceps throughout using a dual-tuned ((1)H and (31)P) surface coil with a simple pulse-and-acquire sequence. Total ATP turnover rate (ATPtot) was estimated at exercise cessation from direct measurements of the dynamics of phosphocreatine (PCr) and proton handling. Between 3 and 8 min during MOD, there was no discernable V̇O2 sc (mean ± SD, 0.06 ± 0.12 l min(-1)) or change in [PCr] (30 ± 8 vs. 32 ± 7 mm) or ATPtot (24 ± 14 vs. 17 ± 14 mm min(-1); each P = n.s.). During HVY, the V̇O2 sc was 0.37 ± 0.16 l min(-1) (22 ± 8%), [PCr] decreased (19 ± 7 vs. 18 ± 7 mm, or 12 ± 15%; P < 0.05) and ATPtot increased (38 ± 16 vs. 44 ± 14 mm min(-1), or 26 ± 30%; P < 0.05) between 3 and 8 min. However, the increase in ATPtot (ΔATPtot) was not correlated with the V̇O2 sc during HVY (r(2) = 0.06; P = n.s.). This lack of relationship between ΔATPtot and V̇O2 sc , together with a steepening of the [PCr]-V̇O2 relationship in HVY, suggests that reduced work efficiency during heavy exercise arises from both contractile (P/W) and mitochondrial sources (the O2 cost of ATP resynthesis; P/O)

Modeling the gas-phase chemistry of the transitional disk around HD 141569A

Aims: The chemistry, distribution and mass of the gas in the transitional disk around the 5 Myr old B9.5 V star HD 141569A are constrained. Methods: A quasi 2-dimensional (2D) chemistry code for photon dominated regions (PDR) is used to calculate the chemistry and gas temperatures in the disk. The calculations are performed for several gas distributions, PAH abundances and values of the total gas mass. The resulting CO J=2-1 and J=3-2 emission lines are computed with a 2D radiative transfer code and are compared to observations. Results: The CO abundance is very sensitive to the total disk mass because the disk is in a regime where self-shielding just sets in. The observed CO emission lines are best fit by a power-law gas distribution of 80 M_earth starting at 80 AU from the central star, indicating that there is some gas in the inner hole. Predictions are made for intensities of atomic fine-structure lines. [C I], which is the dominant form of carbon in large parts of the disk, is found to be a good alternative tracer of the gas mass.Comment: 11 pages, 9 figures. Accepted for publication in A&

The Doppler Shadow of WASP-3b: A tomographic analysis of Rossiter-McLaughlin observations

Hot-Jupiter planets must form at large separations from their host stars where the temperatures are cool enough for their cores to condense. They then migrate inwards to their current observed orbital separations. Different theories of how this migration occurs lead to varying distributions of orbital eccentricity and the alignment between the rotation axis of the star and the orbital axis of the planet. The spin-orbit alignment of a transiting system is revealed via the Rossiter-McLaughlin effect, which is the anomaly present in the radial velocity measurements of the rotating star during transit due to the planet blocking some of the starlight. In this paper we aim to measure the spin-orbit alignment of the WASP-3 system via a new way of analysing the Rossiter-McLaughlin observations. We apply a new tomographic method for analysing the time variable asymmetry of stellar line profiles caused by the Rossiter-McLaughlin effect. This new method eliminates the systematic error inherent in previous methods used to analyse the effect. We find a value for the projected stellar spin rate of v sin i = 13.9 \pm 0.03 km/s which is in agreement with previous measurements but has a much higher precision. The system is found to be well aligned which favours an evolutionary history for WASP-3b involving migration through tidal interactions with a protoplanetary disc. Using gyrochronology we estimate the age of the star to be ~300 Myr with an upper limit of 2 Gyr from comparison with isochrones.Comment: Accepted for publication in A&A, 8 pages, 4 figures, 2 table

A new bronchodilator response grading strategy ıdentifies distinct patient populations

Rationale: A positive bronchodilator response (BDR) according to American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines require both 200 ml and 12% increase in forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) after bronchodilator inhalation. This dual criterion is insensitive in those with high or low FEV1. Objectives: To establish BDR criteria with volume or percentage FEV1 change. Methods: The largest FEV1 and FVC were identified fromthree pre- and three post-bronchodilator maneuvers in COPDGene (Genetic Epidemiology of COPD) participants. A total of 7,741 individuals with coefficient of variation less than 15% for both FEV1 and FVC formed bronchodilator categories of FEV1 response: negative (0.00% to 0.00 L to 9.00% to 16.00% to 0.16 L to 26.00% or >0.26 L). These response size categories are based on empirical limits considering average FEV1 increase of approximately 160 ml and the clinically important difference for FEV1. To compare flow and volume response characteristics, BDR-FEV1 category assignments were applied for the BDR-FVC response. Results: Twenty percent met mild and 31% met moderate or marked BDR-FEV1 criteria, whereas 12% met mild and 33% met moderate or marked BDR-FVC criteria. In contrast, only 20.6% met ATS/ERS positive criteria. Compared with the negative BDR-FEV1 category, the minimal, mild, moderate, and marked BDR-FEV1 categories were associated with greater 6-minute-walk distance and lower St. George's Respiratory Questionnaire and modified Medical Research Council dyspnea scale scores. Compared with negative BDR, moderate and marked BDR-FEV1 categories were associated with fewer exacerbations, and minimal BDR was associated with lower computed tomography airway wall thickness. Compared with the negative category, all BDR-FVC categories were associated with increasing emphysema percentage and gas trapping percentage. Moderate and marked BDR-FVC categories were associated with higher St. George's Respiratory Questionnaire scores but fewer exacerbations and lower dyspnea scores. Conclusions: BDR grading by FEV1 volume or percentage response identified subjects otherwise missed by ATS/ERS criteria. BDR grades were associated with functional exercise performance, quality of life, exacerbation frequency, dyspnea, and radiological airway measures. BDR grades in FEV1 and FVC indicate different clinical and radiological characteristics.United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Heart Lung & Blood Institute (NHLBI)National Center for Advancing Translational Sciences through UCLA CTSI Gran

WASP-23b: a transiting hot Jupiter around a K dwarf and its Rossiter-McLaughlin effect

We report the discovery of a new transiting planet in the Southern Hemisphere. It has been found by the WASP-south transit survey and confirmed photometrically and spectroscopically by the 1.2m Swiss Euler telescope, LCOGT 2m Faulkes South Telescope, the 60 cm TRAPPIST telescope and the ESO 3.6m telescope. The orbital period of the planet is 2.94 days. We find it is a gas giant with a mass of 0.88 \pm 0.10 Mj and a radius estimated at 0.96 \pm 0.05 Rj . We have also obtained spectra during transit with the HARPS spectrograph and detect the Rossiter-McLaughlin effect despite its small amplitude. Because of the low signal to noise of the effect and of a small impact parameter we cannot place a constraint on the projected spin-orbit angle. We find two confiicting values for the stellar rotation. Our determination, via spectral line broadening gives v sin I = 2.2 \pm 0.3 km/s, while another method, based on the activity level using the index log R'HK, gives an equatorial rotation velocity of only v = 1.35 \pm 0.20 km/s. Using these as priors in our analysis, the planet could either be misaligned or aligned. This should send strong warnings regarding the use of such priors. There is no evidence for eccentricity nor of any radial velocity drift with time.Comment: 13 pages, 8 figures, 7 tables, accepted for publication in A&

Rossiter-McLaughlin Effect Measurements for WASP-16, WASP-25 and WASP-31

We present new measurements of the Rossiter-McLaughlin (RM) effect for three WASP planetary systems, WASP-16, WASP-25 and WASP-31, from a combined analysis of their complete sets of photometric and spectroscopic data. We find a low amplitude RM effect for WASP-16 (Teff = 5700 \pm 150K), suggesting that the star is a slow rotator and thus of an advanced age, and obtain a projected alignment angle of lambda = -4.2 degrees +11.0 -13.9. For WASP-25 (Teff = 5750\pm100K) we detect a projected spin-orbit angle of lambda = 14.6 degrees \pm6.7. WASP-31 (Teff = 6300\pm100K) is found to be well-aligned, with a projected spin-orbit angle of lambda = 2.8degrees \pm3.1. A circular orbit is consistent with the data for all three systems, in agreement with their respective discovery papers. We consider the results for these systems in the context of the ensemble of RM measurements made to date. We find that whilst WASP-16 fits the hypothesis of Winn et al. (2010) that 'cool' stars (Teff < 6250K) are preferentially aligned, WASP-31 has little impact on the proposed trend. We bring the total distribution of the true spin-orbit alignment angle, psi, up to date, noting that recent results have improved the agreement with the theory of Fabrycky & Tremaine (2007) at mid-range angles. We also suggest a new test for judging misalignment using the Bayesian Information Criterion, according to which WASP-25 b's orbit should be considered to be aligned.Comment: 20 pages, 14 tables, 10 figures. Accepted to MNRA

DISTRIBUTION AND PROPERTIES OF CDP-DIGLYCERIDE:INOSITOL TRANSFERASE FROM BRAIN 1

CDP-diglyceride is converted to phosphatidyl inositol by several particulate subcellular fractions of guinea pig brain, with highest specific activity in the microsomal fraction. Optimal conditions with respect to pH, metal ion concentration, and substrate concentrations have been determined. The reaction was stimulated by the addition of bovine serum albumin and by Tween 80. Of several dl-CDP-diglycerides synthesized and used as substrates in a spectrophoto-metric assay for the enzyme, dl-CDP-didecanoin was the most active. The enzyme showed a high selectivity for myo-inositol. Of a number of compounds tested, only scyllo -inosose and epi -inosose served as substrates. Three inositol isomers and three myo -inositol monophosphates inhibited the reaction slightly. The most potent inhibitor found was galactinol, a myo -inositol galactoside.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66197/1/j.1471-4159.1969.tb06850.x.pd

WASP-42 b and WASP-49 b: two new transiting sub-Jupiters

We report the discovery of two new transiting planets from the WASP survey. WASP-42 b is a 0.500 +/- 0.035 M_jup planet orbiting a K1 star at a separation of 0.0548 +/- 0.0017 AU with a period of 4.9816872 +/- 7.3 x 10^-6 days. The radius of WASP-42 b is 1.080 +/- 0.057 R_jup while its equilibrium temperature is T_eq = 995 +/- 34 K. We detect some evidence for a small but non-zero eccentricity of e=0.060 +/- 0.013. WASP-49 b is a 0.378 +/- 0.027 M_jup planet around an old G6 star. It has a period of 2.7817387 +/- 5.6 x 10^-6 days and a separation of 0.0379 +/- 0.0011 AU. This planet is slightly bloated, having a radius of 1.115 +/- 0.047 R_jup and an equilibrium temperature of T_eq = 1369 +/- 39 K. Both planets have been followed up photometrically, and in total we have obtained 5 full and one partial transit light curves of WASP-42 and 4 full and one partial light curves of WASP-49 using the Euler-Swiss, TRAPPIST and Faulkes South telescopes