Observational evidence

Astronomers use a variety of methods to determine the distance to objects in the universe. One of the most effective is the standard candle provided by Type la supemovae. These supemovae originate in a binary star system when a white dwarf star accretes matter from its companion. When the white dwarf reaches the Chandrasekhar limit of 1.4 solar masses, a thermonuclear runaway occurs that completely disrupts the star in a cataclysmic explosion that makes the supernova as bright as an entire galaxy. Because Type la supemovae occur in stars with similar masses and because the nuclear burning affects the entire star, they all have essentially the same intrinsic brightness and their apparent brightness observed from Earth can be used to derive the distance to the supernova. 

Hubble s crucial observation was that, in every direction one looks, the farther away a galaxy is, the more the light from that galaxy is red-shifted. If the red shift is a Doppler shift, this implies that the farther away the galaxy is, the faster it is moving away from us. The most reasonable explanation for this observation is that the universe is uniformly expanding everywhere. The current best estimate for the Hubble Constant, which describes the rate of expansion, is 70.8 km s-1 megaparsec-1, with an uncertainty of 5.6%. 

There is good agreement between observations and the predictions of Big Bang synthesis. The abundances of H, 4He, 3He, and deuterium, match the predictions very well. For 7Li, observations and predictions match within about a factor of two. It is likely that the main uncertainty for 7Li is in the nuclear physics of its synthesis. This level of agreement represents an impressive success of modem cosmology. 

While the variations of climate over time scales of ten thousand to a hundred thousand years in all likelihood are caused by variations in solar irradiation over the year due to orbital effects, the so-called Milankovitch effect (Milankovitch, 1920, 1941 Berger, 

climate variations on shorter time scales are still rather mysterious. The most spectacular of these variations, at least as interpreted from ice-core measurements, appear to have amplitudes of several degrees Kelvin and were particularly common during the last glaciation (e.g.. Alley et al, 1993). Occurrence of such extreme events during the Holocene, at least for the last 8000 years or so, has so far not been reported. Also, the less extreme climate fluctuations are of considerable importance to society. There have been numerous reports of climate variations over the last several hundred years, including a period of relatively warm climate, at 

Observed surface temperature correlated with the global average temperature 

FIGURE 1 (a) Observed pointwise correlation of the annual surface temperature with the global averaged 

FIGURE 2 Reconstructed surface temperature from 1400 until present (after Mann et al., 1998). Ob.served surface temperature data from Parker (1999, personal communication) have beeen inserted. 

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Studies on the UV irradiation of the 1-phthalimidoaziridine system have been carried out (71JCS(C)988). When the photolysis was performed in the presence of an alkene, an exchange reaction was observed. Evidence was presented which showed that the reaction involved concerted fragmentation of the phthalimidoaziridine (114) to an alkene and... 

Complete and correct diagnosis of failures will account for all observed evidence. In this case, although some questions remain unanswered, it is judged that galvanic corrosion exercised the predominant influence. 

The discovery of ozone holes over Antarctica in the mid-1980s was strong observational evidence to support the Rowland and Molina hypothesis. The atmosphere over the south pole is complex because of the long periods of total darkness and sunlight and the presence of a polar vortex and polar stratospheric clouds. However, researchers have found evidence to support the role of CIO in the rapid depletion of stratospheric ozone over the south pole. Figure 11-3 shows the profile of ozone and CIO measured at an altitude of 18 km on an aircraft flight from southern Chile toward the south pole on September 21, 1987. One month earlier the ozone levels were fairly uniform around 2 ppm (vol). 

While there is agreement that the rates of clay dehydroxylations are predominantly deceleratory and sensitive to PH2G, there is uncertainty as to whether these reactions are better represented by the first-order or by the diffusion-control kinetic expressions. In the absence of direct observational evidence of interface advance phenomena, it must be concluded that the presently available kinetic analyses do not provide an unambiguous identification of the reaction mechanisms. The factors which control the rates of dehydroxylation of these structurally related minerals have not been identified. 

Although the submitters report that this reagent is stable at 0° i.e., still reactive toward benzoyl chloride) for periods of at least one hour under a nitrogen atmosphere,4 the checkers repeatedly observed evidence of thermal decomposition when the solution was allowed to warm above —40°. This decomposition was indicated by the appearance of a red-brown coloration as the reagent was warmed to —40° as the... 

Fig. 3. Abundances within the hydrogen-burning shell as function of relative mass 5m, defined as ranging from 0 to 1 between the bottom of the shell and the convective envelope. From observational evidence a penetration of extra-mixing down to 5m 0.15 has been inferred...

Although we have never observed evidence of saturation kinetics in any of the metal-catalyzed reactions of the neutral phosphorus esters,17 it is difficult to envision... 

The EoS HHJ - INCQM with 2SC quark matter phase has a type of hard -soft - hard EoS [40], Therefore critical line is mainly orthogonal to the mass axis and the expected population clustering seems to be not frequency but mass clustering. As already reported by M.C. Miller at this conference, there is observational evidence that the population of LMXB s is mainly homogeneous. 

DR. NORTON An excellent attempt to observe such hydrogen bonding was made recently by Fachinetti, et al. [Calderazzo, F. Fachinetti, G. Marchetti, F. Zanazzi, P. F. J. Chem. Soc., Chem. Commun. 1981, 181]. They took hydridocobalttetracarbonyl and triethylamine, and crystallized out a species which one can only describe as the tetracarbonylcobaltate of protonated triethylamine. They proposed some type of interaction between the hydrogen and a face of the cobalt tetrahedral complex, but it was clear that the interaction was almost entirely with nitrogens. The conclusion I would draw is that the complex appears to proceed directly to full protonation of the amine without any observable evidence for a hydrogen bonded intermediate. 

Observe evidence that a precipitate is in equilibrium with its ions in solution. 

The maximum value of the diffusivity occurs when zJzi — 0.5 and has a magnitude 0.21w.Zj. For typical meteorological conditions this corresponds to a diffusivity of 0(100 m sec" ) and a characteristic diffusion time defined by of 0(5zi/w ). Yamada (1977), for example, has observed dififusivities of 0(100 m sec" ) when simulating the Wangara day 34 field experiment. Above the surface layer the observational evidence is inadequate to verify more than an order of magnitude estimate of the diffusivity. Clearly there is a need for more field data to establish the shape of the profile in the upper portions of the mixed layer. 

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