2,228 research outputs found

    Non-abelian instantons on a fuzzy four-sphere

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    We study the compatibility between the BPSTSU(2)BPST SU(2) instanton and the fuzzy four-sphere algebra. By using the projective module point of view as an intermediate step, we are able to identify a non-commutative solution of the matrix model equations of motion which minimally extends the SU(2) instanton solution on the classical sphere S4S^4. We also propose to extend the non-trivial second Chern class with the five-dimensional noncommutative Chern-Simons term

    Grasping the concept of personal property.

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    The concept of property is integral to personal and societal development, yet understanding of the cognitive basis of ownership is limited. Objects are the most basic form of property, so our physical interactions with owned objects may elucidate nuanced aspects of ownership. We gave participants a coffee mug to decorate, use and keep. The experimenter also designed a mug of her own. In Experiment 1, participants performed natural lifting actions with each mug. Participants lifted the Experimenter's mug with greater care, and moved it slightly more towards the Experimenter, while they lifted their own mug more forcefully and drew it closer to their own body. In Experiment 2, participants responded to stimuli presented on the mug handles in a computer-based stimulus-response compatibility task. Overall, participants were faster to respond in trials in which the handles were facing in the same direction as the response location compared to when the handles were facing away. The compatibility effect was abolished, however, for the Experimenter's mug - as if the action system is blind to the potential for action towards another person's property. These findings demonstrate that knowledge of the ownership status of objects influences visuomotor processing in subtle and revealing ways

    The Free Energy of N=4 Super-Yang-Mills and the AdS/CFT Correspondence

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    We compute the high-temperature limit of the free energy for four-dimensional N=4 supersymmetric SU(N_c) Yang-Mills theory. At weak coupling we do so for a general ultrastatic background spacetime, and in the presence of slowly-varying background gauge fields. Using Maldacena's conjectured duality, we calculate the strong-coupling large-N_c expression for the special case that the three-space has constant curvature. We compare the two results paying particular attention to curvature corrections to the leading order expressions.Comment: 26 pages.Minor corrections to eqs.(19),(21). Results and conclusions unchanged. References adde

    1,4-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)­oxy]butane

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    The title compound, C34H28N6O2, has an inversion centre located at the mid-point of the central C—C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Å above the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1)°, repectively. In the crystal, weak C—H⋯N inter­actions link the mol­ecules into infinite chains parallel to the a axis

    Quantitative Physicochemical Analysis of Acid-Base Balance and Clinical Utility of Anion Gap and Strong Ion Gap in 806 Neonatal Calves with Diarrhea

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    BackgroundAcid-base abnormalities in neonatal diarrheic calves can be assessed by using the Henderson-Hasselbalch equation or the simplified strong ion approach which use the anion gap (AG) or the strong ion gap (SIG) to quantify the concentration of unmeasured strong anions such as d-lactate. Hypothesis/ObjectivesTo determine and compare the clinical utility of AG and SIG in quantifying the unmeasured strong anion charge in neonatal diarrheic calves, and to examine the associations between biochemical findings and acid-base variables by using the simplified strong ion approach. We hypothesized that the SIG provides a more accurate prediction of unmeasured strong anions than the AG. AnimalsEight hundred and six neonatal diarrheic calves admitted to a veterinary teaching hospital. MethodsRetrospective study utilizing clinicopathologic findings extracted from medical records. ResultsHyperphosphatemia was an important predictor of venous blood pH. Serum inorganic phosphorus and plasma d-lactate concentrations accounted for 58% of the variation in venous blood pH and 77% of the variation in AG and SIG. Plasma d- and total lactate concentrations were slightly better correlated with SIG (r(s)=-0.69;-0.78) than to AG (r(s)=0.63;0.74). Conclusions and Clinical ImportanceStrong ion gap is slightly better at quantifying the unmeasured strong anion concentration in neonatal diarrheic calves than AG. Phosphorus concentrations should be included as part of the calculation of A(tot) when applying the simplified strong ion approach to acid-base balance to critically ill animals with hyperphosphatemia

    Quantitative Physicochemical Analysis of Acid-Base Balance and Clinical Utility of Anion Gap and Strong Ion Gap in 806 Neonatal Calves with Diarrhea

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    BackgroundAcid-base abnormalities in neonatal diarrheic calves can be assessed by using the Henderson-Hasselbalch equation or the simplified strong ion approach which use the anion gap (AG) or the strong ion gap (SIG) to quantify the concentration of unmeasured strong anions such as d-lactate. Hypothesis/ObjectivesTo determine and compare the clinical utility of AG and SIG in quantifying the unmeasured strong anion charge in neonatal diarrheic calves, and to examine the associations between biochemical findings and acid-base variables by using the simplified strong ion approach. We hypothesized that the SIG provides a more accurate prediction of unmeasured strong anions than the AG. AnimalsEight hundred and six neonatal diarrheic calves admitted to a veterinary teaching hospital. MethodsRetrospective study utilizing clinicopathologic findings extracted from medical records. ResultsHyperphosphatemia was an important predictor of venous blood pH. Serum inorganic phosphorus and plasma d-lactate concentrations accounted for 58% of the variation in venous blood pH and 77% of the variation in AG and SIG. Plasma d- and total lactate concentrations were slightly better correlated with SIG (r(s)=-0.69;-0.78) than to AG (r(s)=0.63;0.74). Conclusions and Clinical ImportanceStrong ion gap is slightly better at quantifying the unmeasured strong anion concentration in neonatal diarrheic calves than AG. Phosphorus concentrations should be included as part of the calculation of A(tot) when applying the simplified strong ion approach to acid-base balance to critically ill animals with hyperphosphatemia

    AdS_3 OM theory and the self-dual string or Membranes ending on the Five-brane

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    We describe properties of the M-theory five-brane containing QQ coincident self-dual strings on its worldvolume. This is the five-brane description of Q membranes ending on the five-brane. In particular, we consider a Maldacena-like low energy limit in the six-dimensional worldvolume which yields a near `horizon' description of the self-dual string using light open membranes, i.e. OM theory, in an AdS_3 x S^3 geometry.Comment: 13 pages, latex, v2: corrected open membrane metric prefactor + typo

    An analysis of the fluctuations of the geomagnetic dipole

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    The time evolution of the strength of the Earth's virtual axial dipole moment (VADM) is analyzed by relating it to the Fokker-Planck equation, which describes a random walk with VADM-dependent drift and diffusion coefficients. We demonstrate first that our method is able to retrieve the correct shape of the drift and diffusion coefficients from a time series generated by a test model. Analysis of the Sint-2000 data shows that the geomagnetic dipole mode has a linear growth time of 13 to 33 kyr, and that the nonlinear quenching of the growth rate follows a quadratic function of the type [1-(x/x0)^2]. On theoretical grounds, the diffusive motion of the VADM is expected to be driven by multiplicative noise, and the corresponding diffusion coefficient to scale quadratically with dipole strength. However, analysis of the Sint-2000 VADM data reveals a diffusion which depends only very weakly on the dipole strength. This may indicate that the magnetic field quenches the amplitude of the turbulent velocity in the Earth's outer core.Comment: 11 pages, 6 figure

    Enhancing surgical performance in cardiothoracic surgery with innovations from computer vision and artificial intelligence: a narrative review

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    When technical requirements are high, and patient outcomes are critical, opportunities for monitoring and improving surgical skills via objective motion analysis feedback may be particularly beneficial. This narrative review synthesises work on technical and non-technical surgical skills, collaborative task performance, and pose estimation to illustrate new opportunities to advance cardiothoracic surgical performance with innovations from computer vision and artificial intelligence. These technological innovations are critically evaluated in terms of the benefits they could offer the cardiothoracic surgical community, and any barriers to the uptake of the technology are elaborated upon. Like some other specialities, cardiothoracic surgery has relatively few opportunities to benefit from tools with data capture technology embedded within them (as is possible with robotic-assisted laparoscopic surgery, for example). In such cases, pose estimation techniques that allow for movement tracking across a conventional operating field without using specialist equipment or markers offer considerable potential. With video data from either simulated or real surgical procedures, these tools can (1) provide insight into the development of expertise and surgical performance over a surgeon’s career, (2) provide feedback to trainee surgeons regarding areas for improvement, (3) provide the opportunity to investigate what aspects of skill may be linked to patient outcomes which can (4) inform the aspects of surgical skill which should be focused on within training or mentoring programmes. Classifier or assessment algorithms that use artificial intelligence to ‘learn’ what expertise is from expert surgical evaluators could further assist educators in determining if trainees meet competency thresholds. With collaborative efforts between surgical teams, medical institutions, computer scientists and researchers to ensure this technology is developed with usability and ethics in mind, the developed feedback tools could improve cardiothoracic surgical practice in a data-driven way
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