bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of 10 trinucleotide microsatellite loci in the Critically Endangered Pyrenean yam Borderea chouardii (Dioscoreaceae)
Authors: Segarra‐Moragues J. G. , Palop‐Esteban M. , González‐Candelas F. , Catalán P.
Published: May 2003

The low levels of allozymic variability found in the Critically Endangered Borderea chouardii prompted us to develop microsatellite markers to assess the genetic variability and population structure for the adequate conservation management of this species. A (CTT)n‐enriched partial genomic library was constructed. Ten polymorphic microsatellite loci were isolated from it, rendering 51 alleles in 47 individuals analysed. The allelic pattern observed for all of the loci with more than two alleles suggests that B. chouardii is tetraploid.
Isolation and characterization of microsatellite loci from two inbreeding bark beetle species (Coccotrypes)
Authors: Berg P. R. , Dawson D. A. , Pandhal J. , Kirkendall L. R. , Burke T.
Published: May 2003

We developed 14 microsatellite markers in Coccotrypes carpophagus and 14 in C. dactyliperda. These loci will be used for studying genetic structure and the level of inbreeding in populations in the Canary Islands and Madeira. As a result of long‐term inbreeding, genetic variability is relatively low in these bark beetle species. We found one to five alleles per locus in 29 C. carpophagus and 41 C. dactyliperda from various localities. Eleven of the markers developed for C. carpophagus amplified in C. dactyliperda and seven of the markers developed for C. dactyliperda amplified in C. carpophagus.
Isolation and characterization of microsatellite loci in Greater Sage‐Grouse (Centrocercus urophasianus)
Authors: Taylor S. E. , Oyler‐Mccance S. J. , Quinn T. W.
Published: May 2003

Primers for five polymorphic microsatellite loci were developed for Greater Sage‐Grouse (Centrocercus urophasianus) using an enrichment/detection protocol. The high level of polymorphism (nine to 33 alleles) suggests that these loci will be applicable for investigating mating systems and paternity analysis as well as population genetics. Cross‐species amplification was successful for each locus in at least two other galliform species.
Microsatellites for the Tasmanian devil (Sarcophilus laniarius)
Authors: Jones Menna E. , Paetkau David , Geffen Eli , Moritz Craig
Published: May 2003

The Tasmanian devil (Sarcophilus laniarius), a medium‐sized predator/scavenger, is the largest member of the short‐lived carnivorous marsupial Family Dasyuridae. Now restricted to Tasmania, populations are impacted by habitat clearance and anthropogenic mortality and genetic studies could be of value in informing levels of genetic diversity, mating system, dispersal and the effects of natural and anthropogenic landscape features on gene flow. Microsatellite markers were isolated from a partial, size‐selected genomic library that was enriched for microsatellite sequences. Primer pairs were developed for 11 polymorphic dinucleotide microsatellite loci that conform with Hardy–Weinberg equilibrium and reveal moderate genetic variability across the species range.
A set of polymorphic SSR loci for subarctic willow (Salix lanata, S. lapponum and S. herbacea)
Authors: Stamati K. , Blackie S. , Brown J. W. S. , Russell J.
Published: May 2003

We report the development of seven microsatellite markers from a library enriched with [CA]15, [GA]15, [AAG]8 and [ATG]8. The library was constructed from Icelandic Salix lanata leaf DNA, and seven highly polymorphic single locus products were tested on a range of Scottish and Icelandic S. lanata samples. These seven loci also amplify polymorphic products when tested for cross amplification in a range of Scottish and Icelandic samples of two other subarctic willows (Salix lapponum and Salix herbacea). The microsatellites developed in this study will provide the framework for comparisons with other ecosystem components, and will ultimately inform conservation strategies.
Development of EST‐SSRs from the Alpine Lady‐fern, Athyrium distentifolium
Authors: Woodhead M. , Russell J. , Squirrell J. , Hollingsworth P. M. , Cardle L. , Ramsay L. , Gibby M. , Powell W.
Published: May 2003

The utility of EST‐simple sequence repeats (EST‐SSRs) was evaluated in the fern Athyrium distentifolium. From 1152 frond cDNA clones, 165 microsatellites, including di‐, tri‐, tetra and penta‐nucleotide repeat motifs, were identified. Primer design was possible for 74 of the SSRs; subsequent screening of 10 loci on 186 individuals from six natural populations revealed between two and seven alleles per locus and expected heterozygosity (HE) estimates ranging from 0.027 to 0.809. Eight of these loci were further examined for cross‐species and cross‐generic amplification in other Woodsiaceae species, and polymorphic products were detected. EST‐derived SSRs provide robust, informative and potentially transferable polymorphic markers suitable for biodiversity research.
Microsatellite loci for the North American tortoises (genus Gopherus) and their applicability to other turtle species
Authors: Schwartz T. S. , Osentoski M. , Lamb T. , Karl S. A.
Published: May 2003

We describe the development of nine microsatellite loci from the gopher tortoise (Gopherus polyphemus). Screening 270 individuals, we found these loci to be highly variable (from two to 15 alleles per locus) and thus likely to be applicable in parentage and population‐level analyses for G. polyphemus. All nine loci amplified readily in the other three species of Gopherus as well. This observation, together with successful cross amplification of several loci in two additional families (Cheloniidae, Kinosternidae), underscores their potential utility among turtles in general.
Population genetic differentiation and multiple paternity determined by novel microsatellite markers from the Mountain Log Skink (Pseudemoia entrecasteauxii)
Authors: Stapley Jessica , Hayes Christine M. , Scott Keogh J.
Published: May 2003

A total of 15 microsatellite primer pairs were developed from the Mountain Log Skink, Pseudemoia entrecasteauxii. Nine were used to screen 46 individuals from four populations, and a representative from P. spenceri and P. pagenstecheri. Seven of the loci exhibited large allele variation (16–30) and high heterozygosity (0.24–0.82), and the three populations were genetically differentiated. The markers were also used to screen 36 clutches of known maternity and identified high levels of multiple paternity clutches (57%). The primers developed will provide useful markers for the study of population biology and mating system of these lizards.
Isolation and characterization of polymorphic microsatellites in the groundnut seed beetle, Caryedon serratus (Coleoptera, Bruchidae)
Authors: Sembène M. , Vautrin D. , Silvain J. F. , Rasplus J. Y. , Delobel A.
Published: May 2003

Caryedon serratus feeds on the seeds of four genera of wild Caesalpinioideae. It recently became a major pest of groundnut in Africa. To determine the extent of gene flow and isolation between wild and groundnut‐feeding populations, we isolated and characterized 10 microsatellite loci in this species. Polymorphism ranged from three to 15 alleles in the 80 individuals collected in four localities in Senegal on five host plants.
Isolation of polymorphic microsatellite markers in the great tit (Parus major minor)
Authors: Kawano Katsura M.
Published: May 2003

Six microsatellite loci were developed for a passerine bird, the great tit (Parus major), using two methods. These loci were polymorphic (3–8 alleles per locus) and exhibited expected heterozygosities from 0.45 to 0.77. At one locus the genotypic frequencies deviated significantly from Hardy–Weinberg expectations.
Microsatellites in the bromeliads Tillandsia fasciculata and Guzmania monostachya
Authors: Boneh L. , Kuperus P. , Van Tienderen P. H.
Published: May 2003

We developed microsatellites for the bromeliads Tillandsia fasciculata and Guzmania monostachya, epiphytes of Central‐American montane rain forests. Fragments obtained using amplified fragment length polymorphism (AFLP) pre‐amplification were enriched by hybridization with biotin‐labelled repeat sequences, and subsequently cloned and sequenced. Primers were designed for 15 loci; seven produced interpretable and repeatable amplification products and five were polymorphic in one or both species. We will use these primers to study the population structure of Bromeliaceae in relation to their breeding system as well as to their role in (re‐)colonization of secondary rain forests.
Isolation and characterization of microsatellite loci in the antMyrmica scabrinodis
Authors: Henrich Kai‐Oliver , Sander Anna‐Christine , Wolters Volkmar , Dauber Jens
Published: May 2003

Five polymorphic microsatellite loci were developed for the antMyrmica scabrinodisusing a magnetic bead hybridization selection protocol. The number of alleles per locus varied between three and six. Cross‐species amplification of four of the loci yielded positive amplification products in fourMyrmicaspecies, suggesting their general suitability for microsatellite analysis within this taxonomic group.
Fast isolation of microsatellite loci of very diverse repeat motifs by library enrichment in echinoderm species, Amphipholis squamata and Echinocardium cordatum
Authors: Chenuil A. , Le Gac M. , Thierry M.
Published: May 2003

We conceived a microsatellite enrichment protocol in which probes of several repeat motifs are mixed during the whole procedure. The repeats found generally differed from those of the probes and were very diverse, from mononucleotides to pentanucleotides. We tested several modifications with alternative: (i) digestion/ligation buffers; (ii) polymerases; and (iii) purification methods. The simplest methods always worked as well as classical ones or even better, resulting in probably the simplest protocol for isolating microsatellites of diverse motifs from genomes with low microsatellite frequency. The proportion of positive clones, polymorphism levels and cross‐specific amplification of microsatellite loci significantly vary between species.
Identification and characterization of microsatellites loci in Brycon opalinus (Cuvier, 1819) (Characiforme, Characidae, Bryconiae)
Authors: Barroso R. M. , Hilsdorf A. W. S. , Moreira H. L. M. , Mello A. M. , Guimarães S. E. F. , Cabello P. H. , Traub‐Cseko Y. M.
Published: May 2003

Brycon species are present in various basins in Brazil and were or still are part of commercial fisheries and aquaculture activities (Ferreira et al. 1996, Mendonça 1994). Despite the importance of this group of fish, natural populations of some Brycon species are endangered (Lins et al. 1997). Here, we describe the characterization of seven microsatellite loci that will be useful for the genetic studies in natural and captive populations for these and other species of Brycon.
Five hundred and fifty microsatellite markers for the study of the honeybee (Apis mellifera L.) genome
Authors: Solignac Michel , Vautrin Dominique , Loiseau Anne , Mougel Florence , Baudry Emmanuelle , Estoup Arnaud , Garnery Lionel , Haberl Michael , Cornuet Jean‐Marie
Published: May 2003

Microsatellites are currently considered the most useful genetic markers with wide applications in genomics, quantitative and population genetics. We present here the structure of the core sequence of 552 microsatellites, together with the sequences of the primers and the length of the sequenced allele. These microsatellites were isolated from several libraries constructed from either fractions of total genomic DNA or from clones of a bacterial artificial chromosome (BAC) library. All 552 loci are polymorphic in the honeybee. Many of them were also successfully amplified in three other species of Apis: A. cerana (58%), A. dorsata (59%) and A. florea (38%). A summary of the variability of 36 loci in the three main evolutionary lineages of A. mellifera is given.
Species‐specific microsatellite loci for the European squid (Loligo vulgaris)
Authors: Guarniero Ilaria , Garoia Flavio , Di Placido Raffaele , Ramsak Andreja , Mannini Piero , Tinti Fausto
Published: May 2003

A microsatellite dinucleotide‐enriched library was obtained from the European squid (Loligo vulgaris) and five species‐specific dinucleotide markers were optimized. These markers are highly polymorphic with average expected heterozygosity ranging from 0.706 to 0.927 and allele number ranging from 7 to 17. This set of primers is suitable for population genetic studies.
Polymorphic dinucleotide microsatellites for the Mediterranean angler species (Lophiidae)
Authors: Garoia Flavio , Guarniero Ilaria , Tinti Fausto
Published: May 2003

A microsatellite‐enriched genomic library was obtained from black‐bellied angler Lophius budegassa and six polymorphic dinucleotide markers were successfully optimized. These markers showed levels of polymorphism ranging from 0.363 to 0.662 and allele numbers ranging from three to seven. These markers were also found to successfully amplify in the closely related Lophius piscatorius (angler) and thus appear to be useful for genetic stock structure analysis in both species.
Microsatellite loci for the field cricket, Gryllus bimaculatus and their cross‐utility in other species of Orthoptera
Authors: Dawson Deborah A. , Bretman Amanda J. , Tregenza Tom
Published: May 2003

We have isolated 16 microsatellite loci in the field cricket, Gryllus bimaculatus. Nine loci were found to be polymorphic in G. bimaculatus and the number of alleles varied from seven to 14. All 16 loci were tested for amplification in nine other species. In the five species tested belonging to the same subfamily (Gryllinae), a minimum of nine loci amplified. These loci will be used to determine paternity as part of a study to investigate the genetic benefits of polyandry.
The Lorenz theory of beauty
Authors: Fournier Pierre F
Published: May 2003

Konrad Lorenz's theory of beauty is developed in detail. To elicit a protective desire, an adult's face must display childlike traits or expressions, called beauty. The emotion of beauty is subjective. The personality and the qualities of the individuals also relevant. In those who feel this emotion, it is largely influenced by the emotions of their earlier life.
The field of cosmetic dermatology: the need for a patient‐centred approach
Authors: Wallach Daniel
Published: May 2003

Summary Similar of knowledge and skills are required to deal with certain skin disorders and their corresponding cosmetic complaints. The field of cosmetic dermatology is growing as an overlap between the medical treatment of skin diseases and traditional cosmetology. This poses problems for dermatologists and other professionals, including regulation agencies. Dermatology should be able patients to benefit from all that is necessary for their care, whether that be surgery, drugs or cosmetics. There is no need to modify current regulations. A patient‐orientated approach is advocated.
Facial blushing treated by sympathetic denervation – longlasting benefits in 831 patients
Authors: Drott Christer , Claes Göran , Rex Lars
Published: May 2003

Background  Severe facial blushing may have a strong negative impact on the quality of life and is one of the cardinal symptoms of social phobia. If traditional therapeutic options such as psychotherapy and pharmacological treatment fail, interruption of the sympathetic innervation to the face offers good results, however long‐term results may not be good.

Aim  To investigate whether endoscopic thoracic sympathecotomy (ETS) remains an effective treatment of facial blushing more than one year's follow up.

Method  1314 consecutive patients with severe facial blushing were treated with bilateral ETS. The results were evaluated by questionnaire and symptoms assessed with visual analogue scales (0–10).

Results  The questionnaire was completed by 831 patients (63%) a mean of 29 months (± 11 days) after surgery. Facial blushing was reduced from 8.8 ± 0.05 to 2.5 ± 0.09, P < 0.0001 by the operation. The quality of life was substantially improved. The main side‐effect was redistribution of sweating from the upper to the lower part of the body (compensatory sweating). Increased sweating of the trunk occurred in 83% of the responses. Overall, 85% of the respondents were satisfied with the result and 15% were to some degree not satisfied.

Conclusions  As this is an open study and 37% of patients did not respond to the questionnaire, the results must be viewed with caution. ETS, however, appears to be an effective, safe and lasting surgical method for the treatment of severe facial blushing. Side‐effects, especially compensatory sweating on the trunk and legs are common, and may be severe but only rarely result in the patient regretting the operation.
Facial lipoatrophy: report of five cases after injection of synthetic filler into naso‐labial folds
Authors: André P , Wechsler J , Revuz J
Published: May 2003

Background  Facial lipoatrophies are rare disfiguring syndromes, most commonly characterized by loss of buccal fat pads.

Aims  To demonstrate a relationship between facial lipoatrophy and a new synthetic filler device (Profill) used to correct naso‐labial folds.

Methods  Five cases of lipoatrophy, appeared 9 months or later after Profill injections. No systematic abnormalities were found. In one case biopsy reported a destruction of adipocytes with intense fibrosis in the hypodermis.

Discussion  The culpability of this new biodegradable product is highlighted. To our knowledge, this is the first time this adverse reaction has been reported.

Conclusion  Serious adverse reactions may appear months after Profill injection, skin testing is not always predictive or sufficient. Clinical studies with long‐term follow‐up need to be carried out before new filler devices are launched on the market.
Human exposure to solar ultraviolet radiation
Authors: Diffey Brian L
Published: May 2003

Solar ultraviolet (UV) irradiation depends upon the local UV climate, people's behaviour. Behaviour includes the time spent outdoors and the use of photoprotective agents.

In adult life, a British indoor worker in the UK might typically receive 30% of his or her annual UV exposure from sun‐seeking holidays, 40% from summer weekends, 20% from casual weekday exposure between April and September and just 10% from sun exposure during the 6 month period October to March.

Whilst climatic factors do influence levels of UV radiation (UVR) at the Earth's surface, it is people's behaviour out of doors that has a much greater impact on personal solar UV irradiation. Methods of personal protection include: avoiding direct sunlight in summer around noon; seeking the shade; wearing clothing absorbs UVR; wearing hats that shade face and neck; and using topical sunscreens.
IN VITRO SOMATIC EMBRYOGENESIS AND REGENERATION OF SOMATIC EMBRYOS FROM PIGMENTED CALLUS OF KAPPAPHYCUS ALVAREZII (DOTY) DOTY (RHODOPHYTA, GIGARTINALES)1
Authors: Reddy C. R. K. , Kumar G. Raja Krishna , Siddhanta A. K. , Tewari A. , Eswaran K.
Published: May 2003

In vitro somatic embryogenesis and regeneration of somatic embryos to whole plants through micropropagules was successfully demonstrated from pigmented uniseriate filamentous callus of Kappaphycus alvarezii (Doty) Doty in axenic cultures. More than 80% of the explants cultured on 1.5% (w/v) agar‐solidified Provasoli enriched seawater (PES) medium showed callus development. The callus induction rate was consistently higher for laboratory‐adapted plants. The excised callus grew well in subcultures and maintained its growth for prolonged periods if transferred to fresh medium in regular intervals. Some subcultured calli (<10%) did undergo transformation and produced densely pigmented spherical or oval‐shaped micropropagules (1–5 mm in diameter) that subsequently developed into young plantlets in liquid PES medium. The micropropagule production was further improved through somatic embryogenesis by a novel method of culturing thin slices of pigmented callus with naphthaleneacetic acid (NAA) or a mixture of NAA and 6‐benzylaminopurine. Transfer of embryogenic callus along with tiny somatic embryos to liquid medium and swirling on orbital shaker facilitated rapid growth and morphogenesis of somatic embryos into micropropagules that grew into whole plants in subsequent cultivation in the sea. The daily growth rate of one tissue cultured plant was monitored for seven generations in field and found to be as high as 1.5–1.8 times over farmed plants. The prolific somatic embryogenesis together with high germination potential of somatic embryos observed in this study offers a promising tool for rapid and mass clonal production of seed stock of Kappaphycus for commercial farming.
Ketone components in the contact sex pheromone of the white‐spotted longicorn beetle, Anoplophora malasiaca, and pheromonal activity of synthetic ketones
Authors: Yasui Hiroe , Akino Toshiharu , Yasuda Tetsuya , Fukaya Midori , Ono Hiroshi , Wakamura Sadao
Published: May 2003

Two active fractions were found during the isolation of contact sex pheromone of female elytra of the white‐spotted longicorn beetle, Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae), in addition to fraction of hydrocarbons that had previously been identified. One fraction was essential to evoke a series of precopulatory behaviors of males toward a glass dummy when coated together with the hydrocarbon blend. The other fraction enhanced this activity when added to the mixture. From the latter synergistic fraction, we isolated five novel compounds and identified them as 10‐heptacosanone, (Z)‐18‐heptacosen‐10‐one, (18Z,21Z)‐heptacosa‐18,21‐dien‐10‐one, (18Z,21Z,24Z)‐heptacosa‐18,21,24‐trien‐10‐one, and 12‐heptacosanone by GC‐MS and NMR analyses. A blend of four of these synthetic ketones, without 12‐heptacosanone, in the ratio and concentration found in female elytra extract (250 : 400 : 1000 : 180 ng FE−1) showed greater synergistic effect than the natural fraction containing the ketones. This effect was canceled out by further addition of 12‐heptacosanone (100 ng FE−1), which was still comparable to the effect of the natural ketone fraction.
Forest composition, host‐population density, and parasitism of spruce budworm Choristoneura fumiferana eggs by Trichogramma minutum
Authors: Quayle Debora , Régnière Jacques , Cappuccino Naomi , Dupont Alain
Published: May 2003

The frequency of egg parasitism in the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae) by Trichogramma minutum Riley (Hymenoptera: Trichogrammatidae) was recorded in several host populations during the rising phase of an outbreak in the Gatineau Valley (Quebec, Canada) in 1999 and 2000. Some of the observed spruce budworm populations were subjected to experimental aerial applications of Bacillus thuringiensis var. kurstaki during the course of the study. Untreated spruce budworm population densities at the onset of the study were directly related to stand composition (the proportion of non‐host basal area) but unrelated to plant species diversity. Much of the variation in budworm egg mass parasitism rates was accounted for (77.1% of total variance) by three variables: year, spruce budworm egg population density, and proportion of non‐host basal area in the stand. The exploitation of eggs within parasitised egg masses was related to year, B. thuringiensis treatment, egg mass size, and the proportion of egg masses parasitised in the host population (76.9% of variance). The yearly variation in parasitism rate was considerable, and was consistent with climatic conditions, namely heat accumulation and precipitation during the spruce budworm oviposition period. Parasitism by T. minutum on eggs of C. fumiferana was recorded in 16 additional sites in 2000, to confirm the general form of the inverse density dependence of parasitism. Observations recorded by Neilson in the Green River area of New Brunswick (Canada) between 1948 and 1957 are discussed in the context of the present analysis. These results indicate that parasitism by T. minutum may be more predictable than previously believed and may be an important and consistent source of mortality in the several years preceding an outbreak of C. fumiferana, especially in mixed‐wood stands and in warmer, drier portions of the spruce budworm's range.
Orientational ordering in solid hydrogens with J=1 in the presence of a crystal field
Authors: Antsygina T. N. , Tret’yak S. M. , Freiman Yu. A. , Hemley R. J.
Published: May 2003

A system of quantum linear rotators with quantum rotational angular momentum J=1 in a crystal field is investigated. An equation is derived for the orientational order parameter. The critical parameters, the phase-separation curve, and the line of superheating and supercooling points are found. It is shown that the thermodynamic behavior of a system of linear rotators in the classical case is identical to that of the limiting quantum (J=1) cases studied in this work. For positive crystal fields there is an analogy between orientational phase transitions in a system of rotators with J=1 and phase transformations in a liquid–vapor system. It is shown that states with J>1 radically change the character the phase transitions in the system of rotators: instead of one critical point characteristic for a system of J=1, now there is a line of critical points.
Atomic dynamics and the problem of the structural stability of free clusters of solidified inert gases
Authors: Verkhovtseva É. T. , Gospodarev I. A. , Grishaev A. V. , Kovalenko S. I. , Solnyshkin D. D. , Syrkin E. S. , Feodos’ev S. B.
Published: May 2003

The dependence of the rms amplitudes of atoms in free clusters of solidified inert gases on the cluster size is investigated theoretically and experimentally. Free clusters are produced by homogeneous nucleation in an adiabatically expanding supersonic stream. Electron diffraction is used to measure the rms amplitudes of the atoms; the Jacobi-matrix method is used for theoretical calculations. A series of distinguishing features of the atomic dynamics of microclusters was found. This was necessary to determine the character of the formation and the stability conditions of the crystal structure. It wass shown that for clusters consisting of less than N∼103 atoms, as the cluster size decreases, the rms amplitudes grow much more rapidly than expected from the increase in the specific contribution of the surface. It is also established that an fcc structure of a free cluster, as a rule, contains twinning defects (nuclei of an hcp phase). One reason for the appearance of such defects is the so-called vertex instability (anomalously large oscillation amplitudes) of the atoms in coordination spheres.
Surface and quasisurface states in a strongly anisotropic layered crystal
Authors: Kosevich A. M. , Minaev P. A. , Syrkin E. S. , Polyakov M. L.
Published: May 2003

In Part 1 a relatively simple model of a strongly anisotropic layered crystal is use to study various types of surface waves in the long-wavelength approximation. Particular solutions are obtained for the lattice-dynamics equations in the presence of a surface impurity monolayer. The solutions have frequencies that lying outside (surface states) and inside (quasisurface states) a band in the continuous spectrum of an ideal lattice. In Part 2 shear waves localized near a monatomic layer adsorbed on the free surface of a strongly anisotropic layered crystal are studied at the microscopic level using a vector laltice model with translational and rotational invariance and elastic stability. It is shown that in some cases a noncentral interatomic interaction results in the appearance of surface shear waves of a special type with one or two termination points and a damping parameter that is a nonmonotonic function the two-dimensional wave vector.
Interaction between C60 and gases under pressure
Authors: Sundqvist B.
Published: May 2003

A brief review is given of the interaction between fullerite C60 and various gases under elevated pressure. Subjects discussed include the formation of ordered interstitial gas-fullerene compounds, reactions between intercalated gases and fullerene molecules to form new endohedral and exohedral compounds, and changes in the structure and properties of C60 because of intercalated gas atoms or molecules.
Extra dimensions and nonlinear equations
Authors: Curtright Thomas , Fairlie David
Published: May 2003

Solutions of nonlinear multi-component Euler–Monge partial differential equations are constructed in n spatial dimensions by dimension-doubling, a method that completely linearizes the problem. Nonlocal structures are an essential feature of the method. The Euler–Monge equations may be interpreted as a boundary theory arising from a linearized bulk system such that all boundary solutions follow from simple limits of those for the bulk.
Hierarchy of equations for reduced density matrices at thermodynamic equilibrium with account taken of the spin of particles
Authors: Golovko V. A.
Published: May 2003

The new approach in quantum statistical mechanics proposed by the author in previous publications is extended to systems of nonzero-spin particles. It is shown that properties of particles relevant to their spin can well be incorporated into the approach proposed. In so doing the principal ideas of the approach undergo no changes and lead to a hierarchy of equations for reduced density matrices at thermodynamic equilibrium that generalizes the hierarchy obtained earlier for spinless particles. Thermodynamics based on the hierarchy is worked out as well. The hierarchy and relevant thermodynamics enable one to calculate both thermodynamical properties of a system of particles and structural ones. With the help of perturbation expansions it is shown that the hierarchy has a solution and the solution is unique at least in the case of a weakly interacting system. Using the example of a hard-sphere system wherein triplet correlations are disregarded it is demonstrated that the hierarchy may serve as basis for deriving various results. Comparison of these results with results of other theoretical treatments evidences complete agreement within the limits allowed by the approximation used.
Dissipative Schrödinger-type operators as a model for generation and recombination
Authors: Baro M. , Neidhardt H.
Published: May 2003

Non-self-adjoint operators play an important role in the modeling of open quantum systems. We consider a one-dimensional Schrödinger-type operator of the form −(1/2)(d/dx)(1/m)(d/dx)+V−∑κjδ(⋅−xj),  Im(κj)>0, with dissipative boundary conditions. An explicit description of the characteristic function, the minimal dilation and the generalized eigenfunctions of the dilation is given. The quantities of carrier and current densities are rigorously defined. Furthermore, we will show that the current is not constant and that the variation of the current depend essentially on the chosen density matrix and the imaginary parts of the delta potentials, i.e., Im(κj). This correspondence can be used to model a recombination-generation rate in the open quantum system.
On Alfvén waves in the solar breeze
Authors: Campos L. M. B. C. , Isaeva N. L.
Published: May 2003

The application to the solar wind motivates the consideration of Alfvén waves in a radial background magnetic field and radial mean flow, in two cases, viz., with velocity and magnetic field perturbations along parallels, or also with perturbations along meridians, combined in the radial components of vorticity and electric current. In both cases the same second-order Alfvén wave equation is obtained; it has, in general, two singularities. If the mean flow velocity is taken to be a power of radial distance, with exponent other than zero or unity, there is a transition layer. In general there is a second singularity, viz., a critical layer, where the Alfvén speed equals the mean flow velocity. There is one exceptional case in which the critical layer does not exist, namely a homogeneous medium, for which the mean flow velocity decays on the inverse square of the radial distance, and then Alfvén speed also decays in the same way, so that their ratio is a constant, leading to two possibilities: (i) the ratio is not unity, and the wave equation remains of the second-order; (ii) the wave equation becomes of first-order in the case the mean flow velocity and Alfvén speed are equal everywhere, because then the waves can propagate only in one direction. Case (i) corresponds to Alfvén waves in the solar breeze. Exact solutions of the wave equations are obtained for all values of the radius, as a single expression for the first-order wave equation, whereas for the second-order wave equation it is possible to obtain solutions for small and large radius; the transition level limits the radius of convergence of one of these solutions, but the two solutions together cover the full range of radial distances. The choices of boundary conditions are discussed and the wavefields plotted vs dimensionless distance for several values of the two dimensionless parameters of the problem, viz., the Alfvén number and dimensionless frequency, which appear in one combination only. The analytical results of the present paper are compared with the mostly numerical results in the literature. It is shown that the Alfvén waves exhibit some properties observed in the solar wind, like the nonequipartition of kinetic and magnetic energies.
Diagnostic characterization of ablation plasma ion implantation
Authors: Qi B. , Gilgenbach R. M. , Jones M. C. , Johnston M. D. , Lau Y. Y. , Wang L. M. , Lian J. , Doll G. L. , Lazarides A.
Published: May 2003

Experiments are reported in which two configurations for ablation-plasma-ion-implantation (APII) are characterized by diagnostics and compared. The first configuration oriented the target parallel to the deposition substrate. This orientation yielded ion-beam-assisted deposition of thin films. A delay (>5 μs) between laser and high voltage was necessary for this geometry to avoid arcing between negatively biased substrate and target. The second experimental configuration oriented the target perpendicular to the deposition substrate, reducing arcing, even for zero/negative delay between the laser and the high voltage pulse. This orientation also reduced neutral atom, ballistic deposition on the substrate resulting in a pure ion implantation mode. Ion density measurements were made by resonant laser diagnostics and Langmuir probes, yielding total ion populations in the range of 1014. Implanted ion doses were estimated by electrical diagnostics, and materials analysis, including x-ray energy dispersive spectroscopy and x-ray photoelectron spectroscopy, yielding implanted doses in the range 1012 ions/cm2 per pulse. This yields an APII efficiency of order 10% for implantation of laser ablated ions. Scaling of ion dose with voltage agrees well with a theory assuming the Child–Langmuir law and that the ion current at the sheath edge is due to the uncovering of the ions by the movement of the sheath. Thin film analysis showed excellent adhesion with smoother films for an accelerating voltage of −3.2 kV; higher voltages (−7.7 kV) roughened the film.
Comment on “Stimulated Brillouin scattering in a magnetized dusty plasma with charge fluctuation” [Phys. Plasmas 9, 3752 (2002)]
Authors: Stenflo L. , Shukla P. K.
Published: May 2003

The shortcomings of the stimulated scattering paper by Burman et al. [Phys. Plasmas 9, 3752 (2002)] are pointed out, and an improved theory is presented.
Low dielectric constant materials for microelectronics
Authors: Maex K. , Baklanov M. R. , Shamiryan D. , lacopi F. , Brongersma S. H. , Yanovitskaya Z. S.
Published: May 2003

The ever increasing requirements for electrical performance of on-chip wiring has driven three major technological advances in recent years. First, copper has replaced Aluminum as the new interconnect metal of choice, forcing also the introduction of damascene processing. Second, alternatives for SiO2 with a lower dielectric constant are being developed and introduced in main stream processing. The many new resulting materials needs to be classified in terms of their materials characteristics, evaluated in terms of their properties, and tested for process compatibility. Third, in an attempt to lower the dielectric constant even more, porosity is being introduced into these new materials. The study of processes such as plasma interactions and swelling in liquid media now becomes critical. Furthermore, pore sealing and the deposition of a thin continuous copper diffusion barrier on a porous dielectric are of prime importance. This review is an attempt to give an overview of the classification, the characteristics and properties of low-k dielectrics. In addition it addresses some of the needs for improved metrology for determining pore sizes, size distributions, structure, and mechanical properties.
Permutational symmetry, isotope effects, side crossing, and singlet-triplet splitting in anthracene⋅HeN (N=1, 2) clusters
Authors: Heidenreich Andreas , Jortner Joshua
Published: May 2003

We present quantum-mechanical calculations for the vibrational states of anthracene⋅3HeN and anthracene⋅4HeN (N=1, 2) clusters in the ground (S0) and first excited singlet state (S1) of the anthracene molecule. The anthracene-He potential in the S0 state was described in terms of a sum of Lennard-Jones atom-atom potentials, while the potential in the S1 state also included changes in the dispersive energy and in the repulsive interactions. Variational calculations were carried out for anthracene⋅He1. For anthracene⋅He2, configuration interaction calculations were performed, accounting for the boson and fermion permutation symmetry. For both helium isotopes of the N=1 cluster, tunneling splitting is negligible (<0.01 cm−1), as an appreciable interaction of the densities was only found for highly excited states above the potential-energy barrier of side crossing (for energy eigenvalues ⩾−22 cm−1 below the dissociation limit). The two-boson anthracene⋅4He2 system assumes a singlet A11 ground state due to zero spin of the He4 isotope. Because of the dominance of the two-particle over the one-particle interactions, the two-fermion anthracene⋅3He2 system has a triplet (3B2) vibrational ground state. The singlet-triplet (13B2-11B2) splitting between the two lowest states of the same spatial symmetry of anthracene⋅3He2 was calculated to be 10.5 cm−1. Mass and permutation symmetry effects on the vibrational level structure of anthracene⋅He1 and anthracene⋅He2 were explored for anthracene⋅4He1, anthracene⋅3He1, the two-boson system anthracene⋅4He2, the two-fermion system anthracene⋅3He2 and for the hypothetical fermion system of mass 4. While the isotope effect on the zero-point energies ε0 in the S0 state is Δε0(1)/ε0(1)=[ε0(anthracene⋅3He1)−ε0(anthracene⋅4He1)]/ε0(anthracene⋅4He1)=12%, in accord with the mass effect in the harmonic approximation, the zero-point energy difference between the ground states of the two-fermion anthracene⋅3He2 and the two-boson anthracene⋅4He2 system is Δε0(2)/ε0(2)=[ε0(anthracene⋅3He2)−ε0(anthracene⋅4He2)]/ε0(anthracene⋅4He2)=10%, manifesting a cancellation of mass and permutation symmetry effects. The isotope effect on the red spectral shift δ of the electronic origin for the S0→S1 transition of anthracene⋅He1 is Δδ(1)=δ(anthracene⋅4He1)-δ(anthracene⋅3He1)=0.28 cm−1, while Δδ(2)=δ(anthracene⋅4He2)-δ(anthracene⋅3He2)=−0.50 cm−1, being of the opposite sign than Δδ(1). These features of the spectral shifts as well as the small isotope effects on the energetics and Franck-Condon factors for the S0→S1 vibronic spectra exhibit a delicate balance between differences in mass effects, He-He repulsion, and permutational symmetry of the boson and fermion systems.
Weak transversality and partially invariant solutions
Authors: Grundland A. M. , Tempesta P. , Winternitz P.
Published: May 2003

New exact solutions are obtained for several nonlinear physical equations, namely the Navier–Stokes and Euler systems, an isentropic compressible fluid system and a vector nonlinear Schrödinger equation. The solution method makes use of the symmetry group of the system in situations when the standard Lie method of symmetry reduction is not applicable.
Force-based many-body interatomic potential for ZrC
Authors: Li Ju , Liao Dongyi , Yip Sidney , Najafabadi Reza , Ecker Lynne
Published: May 2003

A classical potential for ZrC is developed in the form of a modified second-moment approximation with emphasis on the strong directional dependence of the C–Zr interactions. The model has a minimal set of parameters, 4 for the pure metal and 6 for the cross interactions, which are fitted to the database of cohesive energies of B1–, B2–, and B3–ZrC, the heat of formation, and most importantly, the atomic force constants of B1–ZrC from first-principles calculations. The potential is then extensively tested against various physical properties, none of which were considered in the fitting. Finite temperature properties such as thermal expansion and melting point are in excellent agreement with experiments. We believe our model should be a good template for metallic ceramics.
Equation of state of polytetrafluoroethylene
Authors: Bourne N. K. , Gray G. T.
Published: May 2003

The present drive to make munitions as safe as is feasible and to develop predictive models describing their constitutive response, has led to the development and production of plastic bonded explosives and propellants. There is a range of elastomers used as binder materials with the energetic components. One of these is known as Kel-F-800™ (poly-chloro-trifluroethylene) whose structure is in some ways analogous to that of poly-tetrafluoroethylene (PTFE or Teflon). Thus, it is of interest to assess the mechanical behavior of Teflon and to compare the response of five different production Teflon materials, two of which were produced in pedigree form, one as-received product, and two from previous in-depth literature studies. The equations of state of these variants were quantified by conducting a series of shock impact experiments in which both pressure-particle velocity and shock velocity-particle velocity dependencies were measured. The compressive behavior of Teflon, based upon the results of this study, appears to be independent of the production route and additives introduced.
Kinetic effects on the stability properties of field-reversed configurations. I. Linear stability
Authors: Belova Elena V. , Davidson Ronald C. , Ji Hantao , Yamada Masaaki
Published: May 2003

New computational results are presented which advance the understanding of the stability properties of the field-reversed configuration (FRC). The results of hybrid and two-fluid [Hall-MHD (magnetohydrodynamic)] simulations of prolate FRCs are presented. The n=1 tilt instability mechanism and growth rate reduction mechanisms are investigated in detail, including resonant particle effects, finite Larmor radius and Hall stabilization, and profile effects. It is shown that the Hall effect determines the mode rotation and the change in the linear mode structure in the kinetic regime; however, the reduction in the growth rate is mostly due to finite Larmor radius effects. Resonant wave–particle interactions are studied as a function of (a) elongation, (b) the kinetic parameter S*, which is proportional to the ratio of the separatrix radius to the thermal ion Larmor radius, and (c) the separatrix shape. It is demonstrated that, contrary to the usually assumed stochasticity of the ion orbits in the FRC, a large fraction of the orbits are regular in long configurations when S* is small. A stochasticity condition is found, and a scaling with the S* parameter is presented. Resonant particle effects are shown to maintain the instability in the large gyroradius regime regardless of the separatrix shape.
Stress development in thin yttrium films on hard substrates during hydrogen loading
Authors: Dornheim M. , Pundt A. , Kirchheim R. , Molen S. J. v. d. , Kooij E. S. , Kerssemakers J. , Griessen R. , Harms H. , Geyer U.
Published: May 2003

Polycrystalline (0002)-textured yttrium (Y) films of 50–500 nm thickness on sapphire substrates were loaded electrolytically with hydrogen (H). The stresses which build up in these films were measured in situ using curvature measurements. The results are compared to the behavior of bulk Y–H. A linear elastic model is used to predict the behavior of clamped thin films. Basic properties of the bulk Y–H phase diagram and elastic constants resemble the measured values of the thin films. Compressive stress builds up during H-loading in the α-Y phase and in the (α-Y+β-YH2) two-phase field, showing an initial stress increase of −1.3 GPa per hydrogen concentration XH (compressive stress). While bulk Y–H samples are known to show a contraction in the β-YH2 phase during H loading, thin films show no evidence for such a contraction during the first loading cycle of the film. The stress remains constant in the bulk β-phase concentration range (ΔXH=0.1 H/Y). This is attributed to the narrow β-phase field (ΔXH=0.02 H/Y) of the thin film during the first loading. Only samples which have been kept at a hydrogen concentration of about 1.5 H/Y for weeks show tensile stress in the concentration range of the bulk β phase. Amazingly a stress increase of about +0.5 GPa/XH (tensile stress) is measured in the β+γ two-phase field. This is attributed to the smaller in-plane nearest-neighbor distance in the γ phase compared to the β phase. In the γ-phase field compressive stress is built up again, compensating the tensile stress. It increases by −1.3 GPa/XH. In total, the net stress in Y–H films remains comparably small. This could be a reason for the good mechanical stability of such Y–H switchable mirrors during H cycling.
Ion acceleration in plasmas emerging from a helicon-heated magnetic-mirror device
Authors: Cohen S. A. , Siefert N. S. , Stange S. , Boivin R. F. , Scime E. E. , Levinton F. M.
Published: May 2003

Using laser-induced fluorescence, measurements have been made of metastable argon-ion, Ar+*(3d4F7/2), velocity distributions on the major axis of an axisymmetric magnetic-mirror device whose plasma is sustained by helicon wave absorption. Within the mirror, these ions have sub-eV temperature and, at most, a subthermal axial drift. In the region outside the mirror coils, conditions are found where these ions have a field-parallel velocity above the acoustic speed, to an axial energy of ∼30 eV, while the field-parallel ion temperature remains low. The supersonic Ar+*(3d4F7/2) are accelerated to one-third of their final energy within a short region in the plasma column, ⩽1 cm, and continue to accelerate over the next 5 cm. Neutral-gas density strongly affects the supersonic Ar+*(3d4F7/2) density.
Secondary electron emission from dielectric materials of a Hall thruster with segmented electrodes
Authors: Dunaevsky A. , Raitses Y. , Fisch N. J.
Published: May 2003

The discharge parameters in Hall thrusters depend strongly on the yield of secondary electron emission from channel walls. Comparative measurements of the yield of secondary electron emission at low energies of primary electrons were performed for several dielectric materials used in Hall thrusters with segmented electrodes. The measurements showed that at low energies of primary electrons the actual energetic dependencies of the total yield of secondary electron emission could differ from fits, which are usually used in theoretical models. The observed differences might be caused by electron backscattering, which is dominant at lower energies and depends strongly on surface properties. Fits based on power or linear laws are relevant at higher energies of primary electrons, where the bulk material properties play a decisive role.
Dislocation loop evolution in ion implanted 4H–SiC
Authors: Persson P. O. Å. , Hultman L. , Janson M. S. , Hallén A. , Yakimova R.
Published: May 2003

4H–SiC epilayers were implanted with Al27 in doses from 1.3×1014 cm−2 to 7.8×1014 cm−2. Dislocation loop formation after high-temperature annealing was studied by plan-view transmission electron microscopy and high-resolution cross-sectional transmission electron microscopy. The total dislocation loop area was found to vary linearly with the implanted dose. For each dose, the total dislocation loop area, reflecting the amount of interstitials bound to loops, stays constant both with prolonged annealing and increasing temperature. Simultaneously, the average radius of the dislocation loops increases, indicating a process similar to Ostwald ripening.