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During the time elapsed since the last general assembly of the I.A.U., many activities have been pursued by the astronomers engaged in research work in the wide fields of problems concerning nebulae and clusters. In fact a number of important discoveries have been made and earlier work has been extended in a way to consolidate earlier views or revise them. The embarras de richesse in this field and the extremely short time available for the compilation of a report make it impossible to present anything else than a few short notes partly written by heart and only intended to express personal views on the question of how the research work on nebulae and clusters might be carried on.
The following report is mainly restricted to work done since the last meeting of the I.A.U., but in a few cases it has been necessary to mention earlier results.
Parental depressive symptoms are associated with emotional and behavioural problems in offspring. However, genetically informative studies are needed to distinguish potential causal effects from genetic confounds, and longitudinal studies are required to distinguish parent-to-child effects from child-to-parent effects.
We conducted cross-sectional analyses on a sample of Swedish twins and their adolescent offspring (n = 876 twin families), and longitudinal analyses on a US sample of children adopted at birth, their adoptive parents, and their birth mothers (n = 361 adoptive families). Depressive symptoms were measured in parents, and externalizing and internalizing problems measured in offspring. Structural equation models were fitted to the data.
Results of model fitting suggest that associations between parental depressive symptoms and offspring internalizing and externalizing problems remain after accounting for genes shared between parent and child. Genetic transmission was not evident in the twin study but was evident in the adoption study. In the longitudinal adoption study child-to-parent effects were evident.
We interpret the results as demonstrating that associations between parental depressive symptoms and offspring emotional and behavioural problems are not solely attributable to shared genes, and that bidirectional effects may be present in intergenerational associations.
Past research has documented pervasive genetic influences on emotional and behavioral disturbance across the life span and on liability to adult psychiatric disorder. Increasingly, interest is turning to mechanisms of gene–environment interplay in attempting to understand the earliest manifestations of genetic risk. We report findings from a prospective adoption study, which aimed to test the role of evocative gene–environment correlation in early development. Included in the study were 561 infants adopted at birth and studied between 9 and 27 months, along with their adoptive parents and birth mothers. Birth mother psychiatric diagnoses and symptoms scales were used as indicators of genetic influence, and multiple self-report measures were used to index adoptive mother parental negativity. We hypothesized that birth mother psychopathology would be associated with greater adoptive parent negativity and that such evocative effects would be amplified under conditions of high adoptive family adversity. The findings suggested that genetic factors associated with birth mother externalizing psychopathology may evoke negative reactions in adoptive mothers in the first year of life, but only when the adoptive family environment is characterized by marital problems. Maternal negativity mediated the effects of genetic risk on child adjustment at 27 months. The results underscore the importance of genetically influenced evocative processes in early development.
Wireless communications such as those in cell phones are utilizing increasing chip design complexity. For example analog mixed-signal chips can contain RF capability which requires integrated inductors [1,2]. High performance RF designs are enabled by the use of thick Copper (Cu) and Aluminum (Al) wires (>3um). In particular, the quality factor of the inductor, which is the ratio of magnetic stored energy over average dissipation, is dependent on the metal thickness. High quality factors, can be achieved by using thick Cu inductors. In some applications, the total thickness of Cu in the inductor can be as much as 12 um.
The fabrication of thick Cu layers is in many ways easier than that of thin Cu layers. For example, there are no limitations in terms of lithography or liner and seed layer thickness. However, there are still challenges with fabrication due to stress. Cracking of the dielectric can occur, due to the mismatch in coefficient of thermal expansion between Cu and SiO2, and due to the thick Cu layers in the inductor stack. Both the layout and the processing must be optimized to ensure that cracking does not occur.
This paper will discuss current applications, inductor design, and the reliability challenges and solutions associated with thick Cu interconnects.
To better understand mechanisms underlying the intergenerational transmission of social anxiety, we used a prospective adoption design to examine the roles of genetic influences (inferred from birth mothers' social phobia) and rearing environment (adoptive mothers' and fathers' responsiveness) on the development of socially inhibited, anxious behaviors in children between 18 and 27 months of age. The sample consisted of 275 adoption-linked families, each including an adopted child, adoptive parents, and a birth mother. Results indicated that children whose birth mothers met criteria for the diagnosis of social phobia showed elevated levels of observed behavioral inhibition in a social situation at 27 months of age if their adoptive mothers provided less emotionally and verbally responsive rearing environments at 18 months of age. Conversely, in the context of higher levels of maternal responsiveness, children of birth mothers with a history of social phobia did not show elevated levels of behavioral inhibition. These findings on maternal responsiveness were replicated in a model predicting parent reports of child social anxiety. The findings are discussed in terms of gene–environment interactions in the intergenerational transmission of social anxiety.
By incorporating a localized heating system within a scanning ion-conductance microscopy (SICM) system, we have performed stable ‘hopping-mode’ (HPICM) imaging for live cells maintained at temperatures ranging up to human body temperature. This allows the accurate study of cell volume and morphology variation versus temperature over extended periods of time. The integration of SICM with scanning electrochemical microscopy (SECM) provides the simultaneous mapping of electrochemical and topographic information for soft samples, such as live cells. This combined technique overcomes the limitations of resolution and topographical artifacts typically associated with SECM. However, previously reported SECM-SICM probe production required expensive and time-consuming focused ion beam (FIB) methods and produced pipettes that are typically hundreds of nanometers in diameter. We report a simple and rapid production method for SECM-SICM double-barrel probes with apertures down to 20 nm in diameter. The characterization of these SECM-SICM probes using scanning electron microscopy (SEM) imaging, cyclic voltammetry (CV) and Raman spectroscopy is also detailed. These SECM-SICM probes were subsequently used to study the morphology and electrochemical activity of several samples, ranging from hard metallic/insulating samples to live cells.
The current study examines the interplay between parental overreactivity and children's genetic backgrounds as inferred from birth parent characteristics on the development of negative emotionality during infancy, and in turn, to individual differences in externalizing problems in toddlerhood. The sample included 361 families linked through adoption (birth parents and adoptive families). Data were collected when the children were 9, 18, and 27 months old. Results indicated links between individual levels and changes in negative emotionality during infancy and toddlerhood to externalizing problems early in the third year of life. Findings also revealed an interaction between birth mother negative affect and adoptive mother overreactive parenting on children's negative emotionality. This Genotype × Environment interaction predicted externalizing problems indirectly through its association with negative emotionality and revealed stronger effects of genetic risk for children with less overreactive parenting from their mothers. Limitations of this study and directions for future research are discussed.
A sample of ~150 compact Galactic PNe has been observed with the Spitzer/IRS spectrograph to characterize their dust properties. These PNe are likely to be at the onset of the PN evolutionary phase, and are therefore ideal for probing dust evolution. The molecular emission features in these Galactic PN spectra are similar to those found in our Magellanic Cloud sample, except that we found a sizable fraction of PNe with mixed-chemistry dust which are not observed in the Clouds. We also found that the distribution among dust types depends strongly on the metallicity of the parent population, implying that the metallicity of the progenitors affects the evolution of a PN from its early stages.
Zinc selenide films have been grown heteroepitaxially on Si(100) substrates by molecular beam epitaxy. The growth has been carried out for raised substrate temperatures and also at room temperature followed by solid-phase epitaxial (SPE) regrowth. The ZnSe films have been characterized by a number of surface-sensitive techniques and both the interface and the bulk material have been examined with high resolution transmission electron microscopy (HRTEM). We find that an interlayer, which is most likely SiSex, is present between the ZnSe film and the Si substrate for growths made at 300 °C and causes loss of epitaxy. In the case of room temperature deposition and SPE, it is absent, leading to good epitaxy. In the latter situation, the films are very uniform and there is a 4° rotation of the ZnSe crystal axes relative to those of the Si substrate.
Monocrystalline cubic SiC (β -SiC) thin films with lower defect densities have been epitaxially grown by chemical vapor deposition on off-axis Si (100) substrates with off-directions different from the conventional 〈011〉. Stacking faults of β -SiC films are investigated by the electrolytic etching and SEM observation. The effects of off-direction deviated from 〈011〉 are examined for the first time. The off-angle is fixed at 2 degrees. We find a reduction in defect density with increasing deviation angle θ, of off-direction from  toward [011[ (θ = 0 - 45°). The defect density becomes one order of magnitude smaller than that of on-axis (100) substrates. A typical value of the stacking fault density is approximately 6 × 106 cm−2 on the substrate with θ = 30° (film thickness: 24μ m).
Growth of SiGe alloys on GaAs substrates at temperatures as low as 590 °C is described. The growth has been accomplished using the pyrolysis of disilane (Si2H6) and Germane (GeH4) at such temperatures. The layers were characterized electrically and show n-type conduction with a carrier concentration of ~ 1 × 1018 cm−3. The high quality of the SiGe layers are evident in the Rutherford backscattering (RBS) channeling results on SiGe/GaAs structures. A Xmin of 5.6% has been obtained for a Si0.05Ge0 95 layer on GaAs. Xmin increases with increasing silicon content in the SiGe layers. The SiGe alloy layers were studied by x-ray diffraction, and the composition was determined assuming coherent, but tetragonally-distorted growth of SiGe on GaAs. The distortion calculations, based on theoretical elastic-constants, were confirmed using Auger electron spectroscopy to check alloy composition.