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Search Results: 1 - 10 of 26277 matches for " Richard Adam "
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Anisotropic dark energy and CMB anomalies
Richard Battye,Adam Moss
Physics , 2009, DOI: 10.1103/PhysRevD.80.023531
Abstract: We investigate the breaking of global statistical isotropy caused by a dark energy component with an energy-momentum tensor which has point symmetry, that could represent a cubic or hexagonal crystalline lattice. In such models Gaussian, adiabatic initial conditions created during inflation can lead to anisotropies in the cosmic microwave background whose spherical harmonic coefficients are correlated, contrary to the standard assumption. We develop an adaptation of the line of sight integration method that can be applied to models where the background energy-momentum tensor is isotropic, but whose linearized perturbations are anisotropic. We then show how this can be applied to the cases of cubic and hexagonal symmetry. We compute quantities which show that such models are indistinguishable from isotropic models even in the most extreme parameter choices, in stark contrast to models with anisotropic initial conditions based on inflation. The reason for this is that the dark energy based models contribute to the CMB anistropy via the inegrated Sachs-Wolfe effect, which is only relevent when the dark energy is dominant, that is, on the very largest scales. For inflationary models, however, the anisotropy is present on all scales.
Updated constraints on the cosmic string tension
Richard Battye,Adam Moss
Physics , 2010, DOI: 10.1103/PhysRevD.82.023521
Abstract: We re-examine the constraints on the cosmic string tension from Cosmic Microwave Background (CMB) and matter power spectra, and also from limits on a stochastic background of gravitational waves provided by pulsar timing. We discuss the different approaches to modeling string evolution and radiation. In particular, we show that the unconnected segment model can describe CMB spectra expected from thin string (Nambu) and field theory (Abelian-Higgs) simulations using the computed values for the correlation length, rms string velocity and small-scale structure relevant to each variety of simulation. Applying the computed spectra in a fit to CMB and SDSS data we find that $G\mu/c^2< 2.6\times 10^{-7}$ ($2 \sigma$) if the Nambu simulations are correct and $G\mu /c^2< 6.4\times 10^{-7}$ in the Abelian-Higgs case. The degeneracy between $G\mu/c^2$ and the power spectrum slope $n_{\rm S}$ is substantially reduced from previous work. Inclusion of constraints on the baryon density from Big Bang Nucleosynthesis (BBN) imply that $n_{\rm S} <1$ at around the $4\sigma$ level for both the Nambu and Abelian-Higgs cases. As a by-product of our results, we find there is "moderate-to-strong" Bayesian evidence that the Harrison-Zel'dovich spectrum is excluded (odds ratio of $\sim 100:1$) by the combination of CMB, SDSS and BBN when compared to the standard 6 parameter fit. Using the contribution to the gravitational wave background from radiation era loops as a conservative lower bound on the signal for specific values of $G\mu/c^2$ and loop production size, $\alpha$, we find that $G\mu /c^2< 7\times 10^{-7} $ for $\alpha c^2/(\Gamma G\mu)\ll1$ and $G\mu/c^2 < 5\times 10^{-11}/\alpha$ for $\alpha c^2/(\Gamma G\mu) \gg1$.
Reconfigurable Digital Circuits Based on Chip Expander with Integrated Temperature Regulation  [PDF]
Vaclav Simek, Richard Ruzicka, Adam Crha, Michal Reznicek
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.311027
Abstract:

This article is dealing with a development of custom chip expander platform with the possibility of accurate temperature control and integration of additional silicon-based features. Such platform may serve as a useful tool which facilitates the burdens connected with measurement and analysis tasks of experimental semiconductor structures. The devised solution provides the functionality of carrier substrate (Al2O3 compound) with CTE compatibility to the experimental silicon chip and is fully customizable with respect to a particular chip. It also allows achieving an easy fan-out of small-diameter chip terminals into a larger, more convenient area and placement of chip specimens conveniently into space-constrained chamber of the AFM microscopes, probe stations, etc. Real application of the developed chip expander platform is demonstrated in context of digital reconfigurable circuits based on polymorphic electronics. In this case the chip expander with attached polymorphic chip REPOMO is thermally stabilized at an ambient temperature level up to approximately 135C and its sensitivity to this phenomenon is demonstrated.

Evidence for massive neutrinos from CMB and lensing observations
Richard A. Battye,Adam Moss
Physics , 2013, DOI: 10.1103/PhysRevLett.112.051303
Abstract: We discuss whether massive neutrinos (either active or sterile) can reconcile some of the tensions within cosmological data that have been brought into focus by the recently released {\it Planck} data. We point out that a discrepancy is present when comparing the primary CMB and lensing measurements both from the CMB and galaxy lensing data using CFHTLenS, similar to that which arises when comparing CMB measurements and SZ cluster counts. A consistent picture emerges and including a prior for the cluster constraints and BAOs we find that: for an active neutrino model with 3 degenerate neutrinos, $\sum m_{\nu}= (0.320 \pm 0.081)\,{\rm eV}$, whereas for a sterile neutrino, in addition to 3 neutrinos with a standard hierarchy and $\sum m_{\nu}= 0.06\,{\rm eV}$, $m_{\nu, \, \rm sterile}^{\rm eff}= (0.450 \pm 0.124)\,{\rm eV}$ and $\Delta N_{\rm eff} = 0.45 \pm 0.23$. In both cases there is a significant detection of modification to the neutrino sector from the standard model and in the case of the sterile neutrino it is possible to reconcile the BAO and local $H_0$ measurements. However, a caveat to our result is some internal tension between the CMB and lensing/cluster observations, and the masses are in excess of those estimated from the shape of the matter power spectrum from galaxy surveys.
Adaptive confidence sets in L^2
Adam D. Bull,Richard Nickl
Statistics , 2011,
Abstract: The problem of constructing confidence sets that are adaptive in L^2-loss over a continuous scale of Sobolev classes of probability densities is considered. Adaptation holds, where possible, with respect to both the radius of the Sobolev ball and its smoothness degree, and over maximal parameter spaces for which adaptation is possible. Two key regimes of parameter constellations are identified: one where full adaptation is possible, and one where adaptation requires critical regions be removed. Techniques used to derive these results include a general nonparametric minimax test for infinite-dimensional null- and alternative hypotheses, and new lower bounds for L^2-adaptive confidence sets.
Pharmacist-documented interventions during the dispensing process in a primary health care facility in Qatar
Richard Hooper, Abdullah Adam, Nadir Kheir
Drug, Healthcare and Patient Safety , 2009, DOI: http://dx.doi.org/10.2147/DHPS.S5534
Abstract: rmacist-documented interventions during the dispensing process in a primary health care facility in Qatar Original Research (5309) Total Article Views Authors: Richard Hooper, Abdullah Adam, Nadir Kheir Published Date November 2009 Volume 2009:1 Pages 73 - 80 DOI: http://dx.doi.org/10.2147/DHPS.S5534 Richard Hooper1, Abdullah Adam2, Nadir Kheir3 1Medical Services Department, 2Pharmacy Department, Medical Services, Qatar Petroleum, Doha, Qatar; 3Qatar University, College of Pharmacy, Doha, Qatar Objectives: To characterize prescribing error interventions documented by pharmacists in four pharmacies in a primary health care service in Qatar. Methods: The study was conducted in a primary health care service in the State of Qatar in the period from January to March 2008. Pharmacists in four clinics within the service used online, integrated health care software to document all clinical interventions made. Documented information included: patient’s age and gender, drug therapy details, the intervention’s details, its category, and its outcome. Interventions were categorized according to the Pharmaceutical Care Network Europe Classification of drug-related problems (DRP). Results: The number of patients who had their prescriptions intercepted were 589 (0.71% of the total 82,800 prescriptions received). The intercepted prescriptions generated 890 DRP-related interventions (an average of 1.9% DRPs identified across the four clinics). Fifty-four percent of all interventions were classified as drug choice problems, and 42% had safety problems (dose too high, potential significant interaction). The prescriber accepted the intervention in 53% of all interventions, and the treatment was changed accordingly. Interventions as a result of transcription errors, legality and formulary issues were eliminated from this study through the use of computerized physician order entry (CPOE). Conclusions: Documenting and analyzing interventions should be a routine activity in pharmacy practice setting in primary health care services. Educational outreach visits and other strategies can improve prescribing practices and enhance patient safety.
Genetic interactions and modifier genes in Hirschsprung's disease
Adam S Wallace,Richard B Anderson
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i45.4937
Abstract: Hirschsprung’s disease is a congenital disorder that occurs in 1:5000 live births. It is characterised by an absence of enteric neurons along a variable region of the gastrointestinal tract. Hirschsprung’s disease is classified as a multigenic disorder, because the same phenotype is associated with mutations in multiple distinct genes. Furthermore, the genetics of Hirschsprung’s disease are highly complex and not strictly Mendelian. The phenotypic variability and incomplete penetrance observed in Hirschsprung’s disease also suggests the involvement of modifier genes. Here, we summarise the current knowledge of the genetics underlying Hirschsprung’s disease based on human and animal studies, focusing on the principal causative genes, their interactions, and the role of modifier genes.
Pharmacist-documented interventions during the dispensing process in a primary health care facility in Qatar
Richard Hooper,Abdullah Adam,Nadir Kheir
Drug, Healthcare and Patient Safety , 2009,
Abstract: Richard Hooper1, Abdullah Adam2, Nadir Kheir31Medical Services Department, 2Pharmacy Department, Medical Services, Qatar Petroleum, Doha, Qatar; 3Qatar University, College of Pharmacy, Doha, QatarObjectives: To characterize prescribing error interventions documented by pharmacists in four pharmacies in a primary health care service in Qatar.Methods: The study was conducted in a primary health care service in the State of Qatar in the period from January to March 2008. Pharmacists in four clinics within the service used online, integrated health care software to document all clinical interventions made. Documented information included: patient’s age and gender, drug therapy details, the intervention’s details, its category, and its outcome. Interventions were categorized according to the Pharmaceutical Care Network Europe Classification of drug-related problems (DRP).Results: The number of patients who had their prescriptions intercepted were 589 (0.71% of the total 82,800 prescriptions received). The intercepted prescriptions generated 890 DRP-related interventions (an average of 1.9% DRPs identified across the four clinics). Fifty-four percent of all interventions were classified as drug choice problems, and 42% had safety problems (dose too high, potential significant interaction). The prescriber accepted the intervention in 53% of all interventions, and the treatment was changed accordingly. Interventions as a result of transcription errors, legality and formulary issues were eliminated from this study through the use of computerized physician order entry (CPOE).Conclusions: Documenting and analyzing interventions should be a routine activity in pharmacy practice setting in primary health care services. Educational outreach visits and other strategies can improve prescribing practices and enhance patient safety.Keywords: pharmacists, interventions, prescribing errors
Inferior Vena Cava Torsion and Stenosis Complicated by Compressive Pericaval Regional Ascites following Orthotopic Liver Transplantation
Adam Alli,Richard Gilroy,Philip Johnson
Case Reports in Radiology , 2013, DOI: 10.1155/2013/576092
Abstract: Inferior vena cava (IVC) stenosis and torsion are well-described rare complications following orthotopic liver transplantation (OLT). We present a case of inferior vena cava intermittent torsion and stenosis complicated by compressive regional ascites. To the best of our knowledge, this is the second case of post-OLT regional ascites related compressive IVC stenosis reported and the first reported case of torsion complicated by regional ascites compression. 1. Introduction We report the case of inferior vena cava (IVC) torsion following orthotopic liver transplantation (OLT) complicated by compression secondary to compressive regional ascites. To the best of our knowledge, this is the second case of post-OLT ascites related compressive IVC stenosis reported and the first reported case of torsion complicated by regional ascites compression. 2. Case Report A 51-year-old male with Hepatitis C cirrhosis and hepatocellular carcinoma underwent piggyback orthotopic liver transplantation (OLT). During the immediate postoperative period, the patient had typical recovery with postoperative sonographic interrogation demonstrating expected perioperative edema. Increased velocities were reported near the inferior vena and portal veins which resolved with improving perioperative edema. No additional vascular compromise was identified in the immediate postoperative period. The patient presented 4 weeks following OLT with shortness of breath and was found to have bilateral pleural effusions, recurrent ascites, and acute renal insufficiency. The findings were all assumed to be related to OLT vascular compromise. Thoracentesis and paracentesis (3 liters of ascitic fluid drained) were performed, and the following day ultrasound and Doppler imaging were performed to evaluate the hepatic vasculature. This revealed mild ascites without evidence of hepatic vascular compromise. Clinically, the patient demonstrated no improvement and had additional paracentesis 3 days following admission in which 5 liters of ascitic fluid was drained. On the 10th day following admission, laparoscopic exploration of the abdomen with liver biopsy and lysis of adhesions was performed. The liver biopsy revealed sinusoidal congestion without evidence of hepatic graft rejection or malignancy. On the 13th day following admission, repeat ultrasound with Doppler imaging demonstrated severe stenosis of the intrahepatic vena cava, portal hypertension, and perihepatic ascites. The stenosis was shown to be worse in the supine position. The following day, inferior vena cavagram was performed demonstrating
Constraints on the anisotropy of dark energy
Stephen Appleby,Richard Battye,Adam Moss
Physics , 2009, DOI: 10.1103/PhysRevD.81.081301
Abstract: If the equation of state of dark energy is anisotropic there will be additional quadrupole anisotropy in the cosmic microwave background induced by the time dependent anisotropic stress quantified in terms of $\Delta w$. Assuming that the entire amplitude of the observed quadrupole is due to this anisotropy, we conservatively impose a limit of $|\Delta w| < 2.1\times 10^{-4}$ for any value of $w\ge -1$ assuming that $\Omega_{\rm m}<0.5$. This is considerably tighter than that which comes from SNe. Stronger limits, upto a factor of 10, are possible for specific values of $\Omega_{\rm m}$ and $w$. Since we assume this component is uncorrelated with the stochastic component from inflation, we find that both the expectation value and the sample variance are increased. There no improvement in the likelihood of an anomalously low quadrupole as suggested by previous work on an elliptical universe.
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