Macro-Micro Modelling Analysis for High Density Packaged Flip Chips

A wide range of flip chip technologies with solder or adhesives have become dominant solutions for high density packaging applications due to the excellent electrical performance, high I/O density and good thermal performance. This paper discusses the use of modeling technique to predict the reliability of high density packaged flip chips in the humid environment. Reliability assessment is discussed for flip chip package at ultra-fine pitch with anisotropic conductive film (ACF). The purpose of this modeling work is to understand the role that moisture plays in the failure of ACF flip chips. A macro-micro 3D finite element modeling technique was used in order to make the multi-length-scale modeling of the ACF flip chip possible. Modeling results are consistent with the findings in the experimental work

Relationships between biodiversity and the stability of marine ecosystems: comparisons at a European scale using meta-analysis.

The relationship between biodiversity and stability of marine benthic assemblages was investigated using existing data sets (n = 28) covering various spatial (m-km) and temporal (1973-2006) scales in different benthic habitats (emergent rock, rock pools and sedimentary habitats) through meta-analyses. Assemblage stability was estimated by measuring temporal variances of species richness, total abundance (density or % cover) and community species composition and abundance structure (using multivariate analyses). Positive relationships between temporal variability in species number and richness were generally observed at both quadrat (<1 m2) and site (100 m2) scales, while no relationships were observed by multivariate analyses. Positive relationships were also observed at the scale of site between temporal variability in species number and variability in community structure with evenness estimates. This implies that the relationship between species richness or evenness and species richness variability is slightly positive and depends on the scale of observation, suggesting that biodiversity per se is important for the stability of ecosystems. Changes within community assemblages in terms of structure are, however, generally independent of biodiversity, suggesting no effect of diversity, but the potential impact of individual species, and/or environmental factors. Except for sedimentary and rock pool habitats, no relationship was observed between temporal variation of the aggregated variable of total abundances and diversity at either scale. Overall our results emphasise that relationships depend on scale of measurements, type of habitats and the marine systems (North Atlantic and Mediterranean) considered.

Differences in mitochondrial and nuclear DNA status of high-density and low-density sperm fractions after density centrifugation preparation

Background: In order to isolate the â??bestâ?? sperm for assisted conception a discontinuous two-step density gradient centrifugation is usually employed. This technique is known to isolate a subpopulation with good motility, morphology and nuclear DNA (nDNA) integrity. As yet its ability to isolate sperm with unfragmented mitochondrial DNA (mtDNA) is unknown. Methods: Semen was obtained from men (n=28) attending our Regional Fertility Centre for infertility investigations. We employed a modified long polymerase chain reaction to study mtDNA and a modified alkaline Comet assay to determine nDNA fragmentation. Results: The high- density fraction displayed significantly more wild type mtDNA (75% of samples) than that of the low- density fraction (25% of samples). In the high-density fraction, there was a higher incidence of single, rather than double or multiple deletions and the deletions were predominantly small scale (0.1-4.0kb). There was a strong correlation between nDNA fragmentation, the number of mtDNA deletions (r=0.7, p

Effect of plasma scale length on multi-MeV proton production by intense laser pulses

The influence of the plasma density scale length on the production of MeV protons from thin foil targets irradiated at I lambda (2) = 5 x 10(19) Wcm(-2) has been studied. With an unperturbed foil, protons with energy >20 MeV were formed in an exponential energy spectrum with a temperature of 2.5 +/- 0.3 MeV. When a plasma with a scale length of 100 mum was preformed on the back of the foil, the maximum proton energy was reduced to

Current-induced forces in atomic-scale conductors

We present a self-consistent tight-binding formalism to calculate the forces on individual atoms due to the flow of electrical current in atomic-scale conductors. Simultaneously with the forces, the method yields the local current density and the local potential in the presence of current flow, allowing a direct comparison between these quantities. The method is applicable to structures of arbitrary atomic geometry and can be used to model current-induced mechanical effects in realistic nanoscale junctions and wires. The formalism is implemented within a simple Is tight-binding model and is applied to two model structures; atomic chains and a nanoscale wire containing a vacancy.

Algal epiphytes of Zostera marina: Variation in assemblage structure from individual leaves to regional scale

Data from a hierarchical study of four Zostera marina beds in Wales were used to identify the spatial scales of variation in epiphyte assemblages. There were significant within and among bed differences in assemblage structure. The differences in assemblage structure with spatial scale generally persisted when species identifications were aggregated into functional groups. There was also significant within and among bed variability in Zostera density and average length. Local variations in Zostera canopy variables at the quadrat scale (total leaf length, average leaf length and leaf density per quadrat) were not related to epiphyte species richness nor to the structure of the assemblage. In contrast, individual leaf length was significantly related to species richness in two of the beds and the structure of epiphyte assemblages was always related to individual leaf lengths. The absence of links between quadrat scale measurements of canopy variables and assemblage structure may reflect the high turnover of individual Zostera leaves. Experimental work is required to discriminate further between the potential causes of epiphyte assemblage variation within and between beds. No bed represented a refuge where a rare species was abundant. If a species was uncommon at the bed scale, it was also uncommon in beds where it occurred. The heterogeneous assemblages found in this study suggest that a precautionary approach to conservation is advisable.

Diagnostic-based modeling on a micro-scale atmospheric-pressure plasma jet

Diagnostic-based modeling (DBM) actively combines complementary advantages of numerical plasma simulations and relatively simple optical emission spectroscopy (OES). DBM is applied to determine spatial absolute atomic oxygen ground-state density profiles in a micro atmospheric-pressure plasma jet operated in He–O2. A 1D fluid model with semi-kinetic treatment of the electrons yields detailed information on the electron dynamics and the corresponding spatio-temporal electron energy distribution function. Benchmarking this time- and space-resolved simulation with phase-resolved OES (PROES) allows subsequent derivation of effective excitation rates as the basis for DBM. The population dynamics of the upper O(3p3P) oxygen state (? = 844 nm) is governed by direct electron impact excitation, dissociative excitation, radiation losses, and collisional induced quenching. Absolute values for atomic oxygen densities are obtained through tracer comparison with the upper Ar(2p1) state (? = 750.4 nm). The resulting spatial profile for the absolute atomic oxygen density shows an excellent quantitative agreement to a density profile obtained by two-photon absorption laser-induced fluorescence spectroscopy.

Late Holocene linkages between decade-century scale climate variability and productivity at Lake Tanganyika, Africa

Microlaminated sediment cores from the Kalya slope region of Lake Tanganyika provide a near-annually resolved paleoclimate record between similar to 2,840 and 1,420 cal. yr B.P. demonstrating strong linkages between climate variability and lacustrine productivity. Laminae couplets comprise dark, terrigenous-dominated half couplets, interpreted as low density underflows deposited from riverine sources during the rainy season, alternating with light, planktonic diatomaceous ooze, with little terrigenous component, interpreted as windy/dry season deposits. Laminated portions of the studied cores consist of conspicuous dark and light colored bundles of laminae couplets. Light and dark bundles alternate at decadal time scales. Within dark bundles, both light and dark half couplets are significantly thinner than within light bundles, implying slower sediment accumulation rates during both seasons over those intervals.

Wasp-17b: An Ultra-Low Density Planet in a Probable Retrograde Orbit

We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a retrograde orbit (? ˜ -150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric orbit, such as the highly eccentric orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.

Spatially Resolved Measurements of Laser Filamentation in Long Scale Length Underdense Plasmas with and without Beam Smoothing

The onset of filamentation, following the interaction of a relatively long (tau(L) similar or equal to 1 ns) and intense (I-L similar or equal to 5 x 10(14) W/cm(2)) laser pulse with a neopentane filled gas bag target, has been experimentally studied via the proton radiography technique, in conditions of direct relevance to the indirect drive inertial confinement fusion scheme. The density gradients associated with filamentation onset have been spatially resolved yielding direct and unambiguous evidence of filament formation and quantitative information about the filamentation mechanism in agreement with previous theoretical modelings. Experimental data confirm that, once spatially smoothed laser beams are used, filamentation is not a relevant phenomenon during the heating laser beams propagation through typical hohlraum gas fills.

Early-type stars observed in the ESO UVES Paranal Observatory Project - III. Sub-parsec and AU-scale structure in the interstellar medium

UVES interstellar observations from the Paranal Observatory Project are presented for early-type stars located in the line of sight to the nearby open clusters IC 2391 (Omni Vel) and NGC 6475 (M7), with spectroscopic resolution R similar to 80 000 and signal-to-noise ratios in the Ti II (3383 angstrom), Ca II K, CH+ (4232 angstrom), Na I D and K I (7698 angstrom) lines of several hundred. The sightlines are a mixture of cluster and non-cluster objects. A total of 22 early-type stars (A and B type) are present in our sample towards IC 2391, with 21 towards NGC 6475/M7, and enable us to probe for differences in column density on scales from similar to 0.07 to 7.3 and similar to 0.05 to 4.9 pc in the respective clusters. Additionally, towards Praesepe the Na I D interstellar variation only is probed towards 13 sightlines and transverse scales of similar to 0.16-10.7 pc at R = 70 000. Towards IC 2391 variations are found in Ti II, Ca II K and Na I D column density in different sightlines of up to 0.7, 1.0 and 1.8 dex (excluding one star), respectively. This kind of variability correlates well with the Hipparcos parallax of the objects, and probes structure within the Local Bubble. For cluster-only objects the variations are 0.3, 0.3 and 0.5 dex, respectively. For the field of view towards NGC6475 the corresponding maximum variations are somewhat smaller, being 0.5, 0.3, 0.8 and 1.0 dex for Ti II, Ca II K, Na I and K I, respectively, for all objects and 0.4, 0.2, 0.6 and 0.7 dex for the cluster-only objects. These are uncorrelated with parallax, and again demonstrate that Ca II K tends to be more smoothly distributed than Na I D. A few likely cluster sightlines show evidence for CH+ and variations in this molecular species of a factor of 10 in equivalent width over sub-pc scales. Towards Praesepe variation in interstellar Na I D is small, being a maximum of only similar to 0.4 dex (including measurement errors), but with fewer sightlines studied. Overall, the scatter in the data is similar for the singly ionized species Ti II and Ca II, lending more support to the hypothesis that these two species sample similar parts of the interstellar medium (ISM). This also appears to be the case for the neutral species Na I D and K I in the one cluster studied. Finally, multiple-epoch observations from a variety of archive sources are used to search for astronomical unit (au) scale structure in the ISM towards 46 sightlines. There are tentative indications of structure on scales of tens to thousands of au for three sightlines. Future observations will confirm the veracity or otherwise of the time-variable components and others presented.

Dynamics of nanometer-scale foil targets irradiated with relativistically intense laser pulses

In this paper we report on an experimental study of high harmonic radiation generated in nanometer-scale foil targets irradiated under normal incidence. The experiments constitute the first unambiguous observation of odd-numbered relativistic harmonics generated by the v x B component of the Lorentz force verifying a long predicted property of solid target harmonics. Simultaneously the observed harmonic spectra allow in-situ extraction of the target density in an experimental scenario which is of utmost interest for applications such as ion acceleration by the radiation pressure of an ultraintense laser.

Role of the plasma scale length in the harmonic generation from solid targets

We have investigated the generation of high harmonics from the interaction of 150 fsec, 790 nm, and 395 nm laser pulses with solid targets. Experiments are presented that demonstrate a strong dependence of the conversion efficiency on the temporal pulse shape and the resulting density scale length (L/lambda) of the preformed plasma. The highest conversion efficiencies are achieved for short density scale lengths (L/lambda less than or equal to 0.4), which result from high contrast ratio pulse interactions. [S1063-651X(98)50211-5].

Heritability of the spatial distribution and peak density of macular pigment:a classical twin study

Purpose: To elucidate the heritability of peak density and spatial width of macular pigment (MP) using a Classical Twin Study.

Methods: Fundus autofluorescence images were obtained at 488?nm from 86 subjects or 43 twin pairs (21 monozygotic (MZ) and 22 dizygotic (DZ)) (27 male, 59 female) aged from 55 to 76 years (mean 62.2±5.3 years). The relative topographic distribution of MP was measured using a grey scale of intensity (0-255 units) in a 7° eccentricity around the fovea. Relative peak MP density (rPMPD) and relative spatial distribution of MP (rSDMP) were used as the main outcome measure in the statistical analysis.

Results: A significantly higher correlation was found within MZ pairs as compared with that within DZ pairs for rPMPD, (r=0.99, 95% confidence interval (95% CI) 0.93 to 1.00) and 0.22, 95% CI -0.34 to 0.71), respectively, suggesting strong heritability of this trait. When rSDMP was compared, there was no significant difference between the correlations within MZ pairs (r=0.48, 95% CI -0.02 to 0.83) and DZ pairs (r=0.63, 95% CI 0.32 to 0.83), thus rSDMP is unlikely to have a considerable heritable component. In addition, there was no difference between any MP parameter when normal maculae were compared with early age-related macular degeneration (AMD) (rPMPD 0.36 vs 0.34, t=1.18 P=0.243, rSDMP 1.75 vs 1.75, t=0.028 P=0.977).ConclusionsrPMPD is a strongly heritable trait whereas rSDMP has minimal genetic influence and a greater influence by environmental factors. The presence of macular changes associated with early AMD did not appear to influence any of these pigment parameters. © 2012 Macmillan Publishers Limited All rights reserved 0950-222X/12

Irish study on high-density schizophrenia families:field methods and power to detect linkage

Large samples of multiplex pedigrees will probably be needed to detect susceptibility loci for schizophrenia by linkage analysis. Standardized ascertainment of such pedigrees from culturally and ethnically homogeneous populations may improve the probability of detection and replication of linkage. The Irish Study of High-Density Schizophrenia Families (ISHDSF) was formed from standardized ascertainment of multiplex schizophrenia families in 39 psychiatric facilities covering over 90% of the population in Ireland and Northern Ireland. We here describe a phenotypic sample and a subset thereof, the linkage sample. Individuals were included in the phenotypic sample if adequate diagnostic information, based on personal interview and/or hospital record, was available. Only individuals with available DNA were included in the linkage sample. Inclusion of a pedigree into the phenotypic sample required at least two first, second, or third degree relatives with non-affective psychosis (NAP), one whom had schizophrenia (S) or poor-outcome schizo-affective disorder (PO-SAD). Entry into the linkage sample required DNA samples on at least two individuals with NAP, of whom at least one had S or PO-SAD. Affection was defined by narrow, intermediate, and broad criteria. The phenotypic sample contained 277 pedigrees and 1,770 individuals and the linkage sample 265 pedigrees and 1,408 individuals. Using the intermediate definition of affection, the phenotypic sample contained 837 affected individuals and 526 affected sibling pairs. Parallel figures for the linkage sample were 700 and 420. Individuals with schizophrenia from these multiplex pedigrees resembled epidemiologically sampled cases with respect to age at onset, gender distribution, and most clinical symptoms, although they were more thought-disordered and had a poorer outcome. Power analyses based on the model of linkage heterogeneity indicated that the ISHDSF should be able to detect a major locus that influences susceptibility to schizophrenia in as few as 20% of families. Compared to first-degree relatives of epidemiologically sampled schizophrenic probands, first-degree relatives of schizophrenic members from the ISHDSF had a similar risk for schizotypal personality disorder, affective illness, alcoholism, and anxiety disorder. With sufficient resources, large-scale ascertainment of multiplex schizophrenia pedigrees is feasible, especially in countries with catchmented psychiatric care and stable populations. Although somewhat more severely ill, schizophrenic members of such pedigrees appear to clinically resemble typical schizophrenic patients. Our ascertainment process for multiplex schizophrenia families did not select for excess familial risk for affective illness or alcoholism. With its large sample ascertained in a standardized manner from a relatively homogeneous population, the ISHDSF provides considerable power to detect susceptibility loci for schizophrenia.