Classifier primitive

From a purely cosmochemical perspective, the present asteroid-comet terminology is a confusing and often misleading means of classifying primitive solar system bodies. An improvement would be to consider any primitive undifferentiated body that ever contained trace of higher amounts of ice to be an ice-bearing planetesimal or true comet. By this scheme, most of the planetesimals in the solar nebula were ice-bearing particles or tme comets. 

Percentage of meteorites seen to fall. Chondrites. Over 90% of meteorites that are observed to fall out of the sky are classified as chondrites, samples that are distinguished from terrestrial rocks in many ways (3). One of the most fundamental is age. Like most meteorites, chondrites have formation ages close to 4.55 Gyr. Elemental composition is also a property that distinguishes chondrites from all other terrestrial and extraterrestrial samples. Chondrites basically have undifferentiated elemental compositions for most nonvolatile elements and match solar abundances except for moderately volatile elements. The most compositionaHy primitive chondrites are members of the type 1 carbonaceous (Cl) class. The analyses of the small number of existing samples of this rare class most closely match estimates of solar compositions (5) and in fact are primary source solar or cosmic abundances data for the elements that cannot be accurately determined by analysis of lines in the solar spectmm (Table 2). Table 2. Solar System Abundances of the Elements ... 

Miscellaneous pheromone components, which are classified as neither Type I nor II, are listed in Table 4. Secondary alcohols with a C7 or C9 chain have been identified from some primitive species i.e., saturated and monoenyl alcohols from three species in Eriocraniidae (Eriocranioidea) [77,78] and dienyl alcohols from one species in Nepticulidae (Nepticuloidea) [79]. Their hydroxyl group is always located at the 2-position, and this is illustrated in the table with the abbreviation 2-OH in place of the OH which was used for the Type I pheromones. Furthermore, esters between a long chain acid and a rather small alcohol have been characterized from species in Tineoidea and Zygaenoidea. Phero-... 

Fig. 3.2 Different carbon compounds in primitive meteorites. Species classified as interstellar on the basis of C-isotopes are shaded. Only a minor fraction of organic carbon is interstellar, (after Ming et al. 1989)...

I believe it is possible [he said] to establish in the realm of the imagination, a law ofthejbur elements which classifies various kinds of material imagination by their coimections with fire, air, water or earth. .. A material element must provide its own substance, its particular rules and poetics. It is not simply coincidental that primitive philosophies often made a decisive choice along these lines. They associated with their formal principles one of the four fundamental elements, which thus became signs of philosophic disposition. 

Chondrites. Over 909, of the meteorites lhat are observed lo fall out of the sky are classified as chondrites, samples lhat are distinguished from terrestrial rocks in many ways. One of the most fundamental is age. Like most meteorites, chondrites have formation ages close to 4.55 Gyr. Chondrites also have basically undifferentiated elemental compositions lor most nonvolatile elements and match solar abundances except for moderately volatile elements. The imtsl cunipositionally primitive chondrites are members for the type I carbonaceous f Cl I class. 

Such plants—now classified as psychoactive or hallucinogenic—became a centerpiece for sacred rituals, a means to explain the unexplainable, and a mainstay of medicine bags. How a primitive people or another culture might use a drug as part of their worship rituals differs greatly from its use as a recreational or street drug where very often it is misused and abused. 

Bravais showed in 1850 that all three-dimensional lattices can be classified into 14 distinct types, namely the fourteen Bravais lattices, the unit cells of which are displayed in Fig. 9.2.3. Primitive lattices are given the symbol P. The symbol C denotes a C face centered lattice which has additional lattice points at the centers of a pair of opposite faces defined by the a and b axes likewise the symbol A or B describes a lattice centered at the corresponding A or B face. When the lattice has all faces centered, the symbol F is used. The symbol I is applicable when an additional lattice point is located at the center of the unit cell. The symbol R is used for a rhombohedral lattice, which is based on a rhombohedral unit cell (with a = b = c and a = ft = y 90°) in the older literature. Nowadays the rhombohedral lattice is generally referred to as a hexagonal unit cell that has additional lattice points at (2/3,1 /3, /s) and (V3,2/3,2/3) in the conventional obverse setting, or ( /3,2/3, ) and (2/3, /3,2/3) in the alternative reverse setting. In Fig. 9.2.3 both the primitive rhombohedral (.R) and obverse triple hexagonal (HR) unit cells are shown for the rhombohedral lattice. 

Along with the primitive translations, and glide-reflections when appropriate, there axe other symmetry operations belonging to the space group. In bipartite systems, it is relevant to classify any symmetry operation according to whether it leaves each sublattice invariant or transforms one into each other (see, for instance, Fig. 2). 

If the primitive cell contains a molecules, each of which contains p atoms, then the number of acoustic modes is 3, and that of optical modes is (3internal modes and (6er - 3) lattice modes. Analysis of these optical modes will be carried out in the following section. 

The brachinite group is small and of somewhat diverse petrology. Nehru et al. (1992) classified them as primitive achondrites, but recent studies have favored cumulate origin for several members (Mittlefehldt et al., 2003 Swindle et al., 1998 Warren and KaUemeyn, 1989a). 

From the four possible triplets of resulting vectors (vi, v, V3 to V2, V3, V4), the one that has shortest vectors is selected because the angles among these vectors are closest to 90°. The Delaunay-Ito reduced primitive cells can be classified into 24 types according to the relationships between unit cell vectors and their scalar products. They are easily converted into one of the 14 Bravais lattices. For example, if V = V2 and s u = s 23 = 0 (an = a23 = 90°), the standard unit cell is orthorhombic C-centered, with lattice vectors, v° calculated as follows ... 

The solid state structure of a homologous series of mesogenic aromatic-aliphatic azomethine ether polymers (AZMEP-n), with n (=1-16) methylene spacers in the main chain, has been studied by X-ray fiber diffraction techniques. Unit cell parameters determined from the fiber patterns of heat-treated single filaments have been used to classify the polymers into distinct groups having different chain conformations and crystal systems. The even members of the. series, where n = 2 4, have C-centered monoclinic unit cells while the unit cells for polymers with n = 6 8 are I-centered monoclinic. When n is even and 10 the unit cells are (primitive) triclinic. The fiber repeat, in the triclinic cells correspond to one chemical moiety while in the monoclinic cells the fiber repeat corresponds to two chemical residues. In addition, the fiber repeat distances are consistent with the methylene spacers adopting an all-trans conformation for all even AZMEP-n polymers. 

Translational modes for four rigid water molecules in a primitive cell are classified as Eig + E2g+Aig+E2u+B2u+Big in Ih phase (D6h). According to the dispersion curves obtained from neutron scattering for ice Ih and also by MD calculation by Tse et al. the peaks at 230cm is assigned as Eig + E2g (with almost same frequency) and a peak at 315cm as Aig in D6h. The frequencies of B2u could appear at around 270 cm but it is not seen clearly in Fig.3. The frequencies of E2u and Big are lower than 150cm In XI phase... 

Before the details of the implementation of MCSCF methods are discussed, it is useful to introduce a few general computer programming concepts. Modern computers may be classified in several ways depending on size, cost, capabilities, or architecture. One such classification divides computers into scalar and vector machines. Scalar computers (e.g. the VAX 11/780) perform primitive arithmetic operations such as additions and multiplications on pairs of arguments. Vector computers (e.g. the CRAY X-MP and CYBER-205) have, in addition to scalar operations, vector instructions ... 

Primitive bile acids in mammals may be classified by carbon numbers as higher bile acids and as cholenoic acid derivatives. A list of primitive bile acids from mammalian sources is given in Table 4. 

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