17,949 research outputs found
Three-Loop Four-Point Correlator in N=4 SYM
We explicitly compute the complete three-loop (O(g^4)) contribution to the
four-point function of chiral primary current-like operators <(q)^2 q^2 (q)^2
q^2> in any finite N=2 SYM theory. The computation uses N=2 harmonic
supergraphs in coordinate space. Dramatic simplifications are achieved by a
double insertion of the N=2 SYM linearized action, and application of
superconformal covariance arguments to the resulting nilpotent six-point
amplitude. The result involves polylogarithms up to fourth order of the
conformal cross ratios. It becomes particularly simple in the N=4 special case.Comment: 8 pages, standard latex, uses feynman and curves.st
Solid state convection models of lunar internal temperature
Thermal models of the Moon were made which include cooling by subsolidus creep and consideration of the creep behavior of geologic material. Measurements from the Apollo program on seismic velocities, electrical conductivity of the Moon's interior, and heat flux at two locations were used in the calculations. Estimates of 1500 to 1600 K were calculated for the temperature, and one sextillion to ten sextillion sq cm/sec were calcualted for the viscosity of the deep lunar interior
Vertebrate DNA in Fecal Samples from Bonobos and Gorillas: Evidence for Meat Consumption or Artefact?
Background: Deciphering the behavioral repertoire of great apes is a challenge for several reasons. First, due to their elusive behavior in dense forest environments, great ape populations are often difficult to observe. Second, members of the genus Pan are known to display a great variety in their behavioral repertoire; thus, observations from one population are not necessarily representative for other populations. For example, bonobos (Pan paniscus) are generally believed to consume almost no vertebrate prey. However, recent observations show that at least some bonobo populations may consume vertebrate prey more commonly than previously believed. We investigated the extent of their meat consumption using PCR amplification of vertebrate mitochondrial DNA (mtDNA) segments from DNA extracted from bonobo feces. As a control we also attempted PCR amplifications from gorilla feces, a species assumed to be strictly herbivorous. Principal Findings: We found evidence for consumption of a variety of mammalian species in about 16% of the samples investigated. Moreover, 40% of the positive DNA amplifications originated from arboreal monkeys. However, we also found duiker and monkey mtDNA in the gorilla feces, albeit in somewhat lower percentages. Notably, the DNA sequences isolated from the two ape species fit best to the species living in the respective regions. This result suggests that the sequences are of regional origin and do not represent laboratory contaminants. Conclusions: Our results allow at least three possible and mutually not exclusive conclusions. First, all results may represent contamination of the feces by vertebrate DNA from the local environment. Thus, studies investigating a species' diet from feces DNA may be unreliable due to the low copy number of DNA originating from diet items. Second, there is some inherent difference between the bonobo and gorilla feces, with only the later ones being contaminated. Third, similar to bonobos, for which the consumption of monkeys has only recently been documented, the gorilla population investigated (for which very little observational data are as yet available) may occasionally consume small vertebrates. Although the last explanation is speculative, it should not be discarded a-priori given that observational studies continue to unravel new behaviors in great ape species
Investigation of electrochemistry of high energy compounds in organic electrolytes Third progress report, Nov. 1, 1965 - Apr. 30, 1966
Electrochemical properties, and chemical reactions between cyclic esters and certain metal
Formal mechanization of device interactions with a process algebra
The principle emphasis is to develop a methodology to formally verify correct synchronization communication of devices in a composed hardware system. Previous system integration efforts have focused on vertical integration of one layer on top of another. This task examines 'horizontal' integration of peer devices. To formally reason about communication, we mechanize a process algebra in the Higher Order Logic (HOL) theorem proving system. Using this formalization we show how four types of device interactions can be represented and verified to behave as specified. The report also describes the specification of a system consisting of an AVM-1 microprocessor and a memory management unit which were verified in previous work. A proof of correct communication is presented, and the extensions to the system specification to add a direct memory device are discussed
Investigation of electrochemistry of high energy compounds in organic electrolytes, May 1 - October 31, 1965
High energy compounds in organic electrolytes - electrochemical and chemical properties of cyclic esters, gamma butyrolactone, gamma valerolactone, and propylene carbonat
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