929 research outputs found
Fracture Blisters
Fracture blisters are a relatively uncommon complication of fractures in locations of the body, such as the ankle, wrist elbow and foot, where skin adheres tightly to bone with little subcutaneous fat cushioning. The blister that results resembles that of a second degree burn
Electrocatalytic CO2 reduction by M(bpy-R)(CO)4 (M = Mo, W; R = H, tBu) complexes. Electrochemical, spectroscopic, and computational studies and comparison with group 7 catalysts
The tetracarbonyl molybdenum and tungsten complexes of 2,2′-bipyridine and 4,4′-di-tert-butyl-2,2′-bipyridine (M(bpy-R)(CO)4; R = H, M = Mo (1), W (2); R = tBu, M = Mo (3), W (4)) are found to be active electrocatalysts for the reduction of CO2. The crystal structures of M(bpy-tBu)(CO)4 (M = Mo (3), W (4)), the singly reduced complex [W(bpy)(CO)4][K(18-crown-6] (5) and the doubly reduced complex [W(bpy-tBu)(CO)3][K(18-crown-6)]2 (6) are reported. DFT calculations have been used to characterize the reduced species from the reduction of W(bpy-tBu)(CO)4 (4). These compounds represent rare examples of group 6 electrocatalysts for CO2 reduction, and comparisons are made with the related group 7 complexes that have been studied extensively for CO2 reduction
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Shifts of criteria or neural timing? The assumptions underlying timing perception studies
In timing perception studies, the timing of one event is usually manipulated relative to another, and participants are asked to judge if the two events were synchronous, or to judge which of the two events occurred first. Responses are analyzed to determine a measure of central tendency, which is taken as an estimate of the timing at which the two events are perceptually synchronous. When these estimates do not coincide with physical synchrony, it is often assumed that the sensory signals are asynchronous, as though the transfer of information concerning one input has been accelerated or decelerated relative to the other. Here we show that, while this is a viable interpretation, it is equally plausible that such effects are driven by shifts in the criteria used to differentiate simultaneous from asynchronous inputs. Our analyses expose important ambiguities concerning the interpretation of simultaneity judgement data, which have hitherto been underappreciated
Higgs and Dark Matter Hints of an Oasis in the Desert
Recent LHC results suggest a standard model (SM)-like Higgs boson in the
vicinity of 125 GeV with no clear indications yet of physics beyond the SM. At
the same time, the SM is incomplete, since additional dynamics are required to
accommodate cosmological dark matter (DM). In this paper we show that
interactions between weak scale DM and the Higgs which are strong enough to
yield a thermal relic abundance consistent with observation can easily
destabilize the electroweak vacuum or drive the theory into a non-perturbative
regime at a low scale. As a consequence, new physics--beyond the DM
itself--must enter at a cutoff well below the Planck scale and in some cases as
low as O(10 - 1000 TeV), a range relevant to indirect probes of flavor and CP
violation. In addition, this cutoff is correlated with the DM mass and
scattering cross-section in a parameter space which will be probed
experimentally in the near term. Specifically, we consider the SM plus
additional spin 0 or 1/2 states with singlet, triplet, or doublet electroweak
quantum numbers and quartic or Yukawa couplings to the Higgs boson. We derive
explicit expressions for the full two-loop RGEs and one-loop threshold
corrections for these theories.Comment: 29 pages, 13 figure
Optical twists in phase and amplitude
Light beams with helical phase profile correspond to photons having orbital angular momentum (OAM). A Laguerre-Gaussian (LG) beam is an example where its helical phase sets a phase-singularity at the optical axis and forms a ring-shaped transverse amplitude profile. Here, we describe a unique beam where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters' path. Unlike LG beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps for cold atoms and for optical manipulation of microscopic particles.V.R.D. has been funded
partially by the Australian National University – Office of the Vice-Chancellor. D.P. and J.G.
acknowledge financial support from the Danish Technical Scientific Research Council (FTP)
Incorporation of Pendant Bases into Rh(diphosphine)_2 Complexes: Synthesis, Thermodynamic Studies, And Catalytic CO_2 Hydrogenation Activity of [Rh(P_2N_2)_2]^+ Complexes
A series of five [Rh(P_2N_2)_2]^+ complexes (P_2N_2 = 1,5-diaza-3,7-diphosphacyclooctane) have been synthesized and characterized: [Rh(P^(Ph)_2N^(Ph)_2)_2]^+ (1), [Rh(P^(Ph)_2N^(Bn)_2)_2]^+ (2), [Rh(P^(Ph)_2N^(PhOMe)_2)_2]^+ (3), [Rh(P^(Cy)_2N^(Ph)_2)_2]^+ (4), and [Rh(P^(Cy)_2N^(PhOMe)_2)_2]^+ (5). Complexes 1–5 have been structurally characterized as square planar rhodium bis-diphosphine complexes with slight tetrahedral distortions. The corresponding hydride complexes 6–10 have also been synthesized and characterized, and X-ray diffraction studies of HRh(P^(Ph)_2N^(Bn)_2)_2 (7), HRh(P^(Ph)_2N^(PhOMe)_2)_2 (8) and HRh(P^(Cy)_2N^(Ph)_2)_2 (9) show that the hydrides have distorted trigonal bipyramidal geometries. Equilibration of complexes 2–5 with H_2 in the presence of 2,8,9-triisopropyl-2,5,8,9-tetraaza-1-phosphabicyclo[3,3,3]undecane (Verkade’s base) enabled the determination of the hydricities and estimated pK_a’s of the Rh(I) hydride complexes using the appropriate thermodynamic cycles. Complexes 1–5 were active for CO_2 hydrogenation under mild conditions, and their relative rates were compared to that of [Rh(depe)_2]^+, a nonpendant-amine-containing complex with a similar hydricity to the [Rh(P_2N_2)_2]^+ complexes. It was determined that the added steric bulk of the amine groups on the P_2N_2 ligands hinders catalysis and that [Rh(depe)_2]^+ was the most active catalyst for hydrogenation of CO_2 to formate
Science and Ideology in Economic, Political, and Social Thought
This paper has two sources: One is my own research in three broad areas: business cycles, economic measurement and social choice. In all of these fields I attempted to apply the basic precepts of the scientific method as it is understood in the natural sciences. I found that my effort at using natural science methods in economics was met with little understanding and often considerable hostility. I found economics to be driven less by common sense and empirical evidence, then by various ideologies that exhibited either a political or a methodological bias, or both. This brings me to the second source: Several books have appeared recently that describe in historical terms the ideological forces that have shaped either the direct areas in which I worked, or a broader background. These books taught me that the ideological forces in the social sciences are even stronger than I imagined on the basis of my own experiences.
The scientific method is the antipode to ideology. I feel that the scientific work that I have done on specific, long standing and fundamental problems in economics and political science have given me additional insights into the destructive role of ideology beyond the history of thought orientation of the works I will be discussing
Expression, purification, crystallization and preliminary crystallographic analysis of a putative Clostridium difficile surface protein Cwp19
Cwp19 is a putatively surface-located protein from Clostridium difficile. A recombinant N-terminal protein (residues 27–401) lacking the signal peptide and the C-terminal cell-wall-binding repeats (PFam04122) was crystallized using the sitting-drop vapour-diffusion method and diffracted to 2 Å resolution
Why Economics Does Not An Ethics Make: A Case Study
This essay is a multidisciplinary case study of environmental injustice. It demonstrates that misuse of the environment can ultimately impact humans unjustly and further that attempts to remediate injustice in one area merely shifts the burden of injustice to others. After providing the historical, sociological and scientific facts surrounding the 50-acre site, an ethical assessment is presented. It was determined that the actors in this case study were not employing any ethical valuing in their decision making process, but rather relied upon economic values to make their choices. The authors then suggest that judging them from within their own economic valuing system that the actors’ decisions had failed to meet their own values, i.e. good economics
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