Multiple-membership multiple-classification models for social network and group dependences

The social network literature on network dependences has largely ignored other sources of dependence, such as the school that a student attends, or the area in which an individual lives. The multilevel modelling literature on school and area dependences has, in turn, largely ignored social networks. To bridge this divide, a multiple-membership multiple-classification modelling approach for jointly investigating social network and group dependences is presented. This allows social network and group dependences on individual responses to be investigated and compared. The approach is used to analyse a subsample of the Adolescent Health Study data set from the USA, where the response variable of interest is individual level educational attainment, and the three individual level covariates are sex, ethnic group and age. Individual, network, school and area dependences are accounted for in the analysis. The network dependences can be accounted for by including the network as a classification in the model, using various network configurations, such as ego-nets and cliques. The results suggest that ignoring the network affects the estimates of variation for the classifications that are included in the random part of the model (school, area and individual), as well as having some influence on the point estimates and standard errors of the estimates of regression coefficients for covariates in the fixed part of the model. From a substantive perspective, this approach provides a flexible and practical way of investigating variation in an individual level response due to social network dependences, and estimating the share of variation of an individual response for network, school and area classifications

Morphological variation of Galapagos island populations of the Yellow Warbler Dendroica petechia aureola

Culmen (beak) length and width, wing length and body mass varied significantly among six Galapagos island populations of the Yellow Warbler Dendroica petechia aureola. Culmen length and body mass were also significantly different between Galapagos and North American populations of D. petechia. Morphological differences among island populations of D. p. aureola may be related to resource variability and the presence of different bird species on different islands

A Front Tracking Model of the MAXUS-8 Microgravity Solidification Experiment on a Ti-45.5at.% Al-8at.%Nb Alloy

On 26th March 2010 the MAXUS-8 sounding rocket was launched from the Esrange Space Center in Sweden. As part of the Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project, a solidification experiment was conducted on a Ti-45.5at.%Al-8at.%Nb intermetallic alloy in a module on this rocket. The experiment was designed to investigate columnar and equiaxed microstructures in the alloy. A furnace model of the MAXUS 8 experiment with a Front Tracking Model of solidification has been developed to determine the macrostructure and thermal history of the samples in the experiment. This paper gives details of results of the front tracking model applied to the MAXUS 8 microgravity experiment. A model for columnar growth is presented and compared to experimental results for furnace A of the experiment module

Comprehensive thermal analysis of a high stability Cu-Zr-Al bulk metallic glass subjected to high-pressure torsion

Bulk metallic glass of Cu38Zr54Al8 nominal composition was synthesized by copper mold casting into 6 mm diameter rods. Disks of the as-cast glass were subjected to severe plastic deformation by high-pressure torsion for different number of revolutions. The microstructure and the thermal behavior of the as-cast, isothermally annealed and deformed glass have been investigated by X-ray diffraction and differential scanning calorimetry, respectively. Continuous heating experiments revealed a two-stage devitrification event with excellent glass forming parameters, such as glass transition (T-g = 671 K), supercooled liquid region ( increment T-x = 80 K), reduced glass transition (T-r = 0.57) and gamma parameter (gamma = 0.41). Power law crystal growth during diffusion-controlled homogeneous nucleation was observed for isothermal annealings. Glassy state was preserved almost in the entire sample volume of the as-cast alloy during the high-pressure torsion process, corresponding to the extreme stability of the Cu38Zr54Al8 alloy against deformation-induced devitrification. This is in accordance with the transition of the reversible specific heat from the glassy to supercooled liquid state measured by modulated calorimetry. It was also concluded that glassy structure is more ordered in the severely deformed state

Three-dimensional laser surface imaging and geometric morphometrics resolve frontonasal dysmorphology in schizophrenia.

BACKGROUND: Although a role for early developmental disturbance(s) in schizophrenia is postulated, it has proved difficult to identify hard, biological evidence. The brain and face emerge in embryologic intimacy, such that in neurodevelopmental disorders, brain dysmorphogenesis is accompanied by facial dysmorphogenesis. METHODS: Three-dimensional (3D) laser surface imaging was used to capture the facial surface of patients and control subjects in 37 male and 32 female patients who satisfied DSM-IV criteria for schizophrenia in comparison with 58 male and 34 female control subjects. Surface images were analyzed using geometric morphometrics and 3D visualizations to identify domains of facial shape that distinguish patients from control subjects. RESULTS: Both male and, particularly, female patients evidenced significant facial dysmorphology. There was narrowing and reduction of the mid to lower face and frontonasal prominences, including reduced width and posterior displacement of the mouth, lips, and chin; increased width of the upper face, mandible, and skull base, with lateral displacement of the cheeks, eyes, and orbits; and anterior displacement of the superior margins of the orbits. CONCLUSIONS: The frontonasal prominence, which enjoys the most intimate embryologic relationship with the anterior brain and also orchestrates aspects of development in maxillary and mandibular domains, evidences a characteristic topography of dysmorphogenesis in schizophrenia

The anhydrobiotic potential and molecular phylogenetics of species and strains of Panagrolaimus (Nematoda, Panagrolaimidae)

Members of the genus Panagrolaimus are bacterialfeeding nematodes that occupy a diversity of niches ranging from Antarctic and temperate soils to terrestrial mosses. Some members of this genus are able to survive extreme desiccation by entering into a state of suspended animation known as anhydrobiosis. We have assembled a collection of Panagrolaimus species and strains and have investigated their anhydrobiotic phenotypes. Our data show that within the genus Panagrolaimus there is a continuum of strains ranging from those unable to survive exposure to low relative humidity (RH) without prior preconditioning at high RH (slow desiccation strategists), through strains that have limited ability to survive rapid desiccation but whose anhydrobiotic ability improves upon preconditioning, to strains such as P. superbus that can readily survive immediate exposure to severe desiccation (fast desiccation strategists). Using this panel of nematodes we investigated the effect of preincubation at high RH on the accumulation of trehalose and on the nematodesâ anhydrobiotic potential. We found that there is a strong correlation between trehalose induction and anhydrobiotic survival in Panagrolaimus. Furthermore, the high trehalose levels observed in fully hydrated P.superbus (10% dry mass) suggest that constitutive expression of trehalose pre-adapts this fast dehydration strategist to combat desiccation. All the strains observed, regardless of survival rates, undertook both coiling and clumping, which has the effect of reducing surface area and slowing the rate of water loss during desiccation. Phylogenetic analyses were carried out to investigate whether the observed anhydrobiotic phenotypes were the result of convergent evolution or represented a single phylogenetic lineage. These analyses, derived from alignments of the rDNA ITS and D3 sequences, indicate that the strongly anhydrobiotic strains of Panagrolaimus form a single phylogenetic lineage, which is separate from the weakly anhydrobiotic strains. The weakly anhydrobiotic strains are also phylogenetically divergent from each other. Our data indicate that Panagrolaimus has the potential to be an excellent model system for the investigation of molecular aspects of nematode anhydrobiosis

The anhydrobiotic potential and molecular phylogenetics of species and strains of Panagrolaimus (Nematoda, Panagrolaimidae)

Members of the genus Panagrolaimus are bacterialfeeding nematodes that occupy a diversity of niches ranging from Antarctic and temperate soils to terrestrial mosses. Some members of this genus are able to survive extreme desiccation by entering into a state of suspended animation known as anhydrobiosis. We have assembled a collection of Panagrolaimus species and strains and have investigated their anhydrobiotic phenotypes. Our data show that within the genus Panagrolaimus there is a continuum of strains ranging from those unable to survive exposure to low relative humidity (RH) without prior preconditioning at high RH (slow desiccation strategists), through strains that have limited ability to survive rapid desiccation but whose anhydrobiotic ability improves upon preconditioning, to strains such as P. superbus that can readily survive immediate exposure to severe desiccation (fast desiccation strategists). Using this panel of nematodes we investigated the effect of preincubation at high RH on the accumulation of trehalose and on the nematodesâ anhydrobiotic potential. We found that there is a strong correlation between trehalose induction and anhydrobiotic survival in Panagrolaimus. Furthermore, the high trehalose levels observed in fully hydrated P.superbus (10% dry mass) suggest that constitutive expression of trehalose pre-adapts this fast dehydration strategist to combat desiccation. All the strains observed, regardless of survival rates, undertook both coiling and clumping, which has the effect of reducing surface area and slowing the rate of water loss during desiccation. Phylogenetic analyses were carried out to investigate whether the observed anhydrobiotic phenotypes were the result of convergent evolution or represented a single phylogenetic lineage. These analyses, derived from alignments of the rDNA ITS and D3 sequences, indicate that the strongly anhydrobiotic strains of Panagrolaimus form a single phylogenetic lineage, which is separate from the weakly anhydrobiotic strains. The weakly anhydrobiotic strains are also phylogenetically divergent from each other. Our data indicate that Panagrolaimus has the potential to be an excellent model system for the investigation of molecular aspects of nematode anhydrobiosis

Quantum oscillations with angular dependence in PdTe2single crystals

The layered transition-metal dichalcogenide PdTe2 has been discovered to possess bulk Dirac points as well as topological surface states. By measuring the magnetization (up to 7 T) and magnetic torque (up to 35 T) in single crystalline PdTe2, we observe distinct de Haas-van Alphen (dHvA) oscillations. Eight frequencies are identified with H||c, with two low frequencies (F α = 8 T and F β = 117 T) dominating the spectrum. The effective masses obtained by fitting the Lifshitz-Kosevich (LK) equation to the data are mα∗=0.059m0 and mβ∗=0.067m0 where m 0 is the free electron mass. The corresponding Landau fan diagrams allow the determination of the Berry phase for these oscillations resulting in values of ∼0.67π for the 3D α band (hole-type) (down to the 1st Landau level) and ∼0.23π-0.73π for the 3D β band (electron-type) (down to the 3rd Landau level). By investigating the angular dependence of the dHvA oscillations, we find that the frequencies and the corresponding Berry phase (ΦB) vary with the field direction, with a ΦB ∼ 0 when H is 10°-30° away from the ab plane for both α and β bands. The multiple band nature of PdTe2 is further confirmed from Hall effect measurements